implantation on the passive layer and corrosion behaviour of AISI 304 and 430 stainless steels

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聚苯胺-聚噻吩自组装超薄膜的电化学性能

聚苯胺--聚噻吩自组装超薄膜的电化学性能1聚苯胺肖妙妙1，佟斌1，田谋锋1，赵玮1，石建兵1，潘月秀1，支俊格2，董宇平1*，唐本忠31北京理工大学材料科学与工程学院，北京（100081）2北京理工大学理学院，北京（100081）3香港科技大学化学系清水湾九龙香港e-mail:chdongyp@摘要：本论文以部分掺杂聚苯胺PAN为聚阳离子，聚（3-羧酸）噻吩P3TEA为聚阴离子，通过自组装技术构筑全共轭自组装膜。

实验结果表明聚电解质沉积量随层数的增加而线性增加，形成均匀的自组装超薄膜；循环伏安实验结果显示自组装膜的电化学性能与纯聚苯胺非常相似，而聚噻吩却是相对稳定的；同时氧化-还原电化学峰位及其电流强度取决于掺杂剂的种类：以H2SO4为最强，HCl次之，而1M KCl由于对聚苯胺不能解离出掺杂离子，所以只使聚苯胺呈现分子链中苯胺二聚体链节的氧化电化学反应。

关键词：聚苯胺、聚噻吩、自组装、电化学1．引言随着超大规模集成技术的不断改进，已要求信息功能材料能够达到智能化和超薄膜化。

在这一进程中，以高分子为基础的超薄膜研究与应用始终是一个非常活跃的领域。

制备超薄膜方法之一的自组装法是1991年Decher等人[1]基于在稀溶液中静电相互作用而提出的一种交替沉积制备超薄膜的方法。

该方法对设备和原材料没有特殊要求，以水为溶剂而对环境友好，在结构、厚度、表面特性上可以做到分子水平的调控，得到分子有序排列的多层膜，为此人们已从许多方面进行研究。

虽然近几年以共轭高分子为聚离子的研究报道逐渐增多，但多是研究具有部分共轭结构的自组装膜性能[2-7]。

我们在前期分别以聚（4-羧酸）苯乙炔、部分掺杂聚苯胺等为聚阴、阳离子，通过自组装技术制备具有完全共轭结构的超薄功能膜。

研究结果表明该自组装膜对酸、强电解质溶液和极性溶剂均具有良好的稳定性，其光电转换性质显著优于非共轭的自组装膜[8，9]。

聚苯胺和聚噻吩作为两种典型的共轭聚合物，因其优异的导电性、电化学性、半导体性和发光特性，广泛应用于许多半导体器件中，如聚合物场效应管、聚合物光电二极管、传感器件、静电屏蔽、电致变色显示屏以及光学器件上。

芬士多（Festo Multi）型号为2GEx h IIC T4 Gb X的气体传输系统说明书

Translation of the original instructions 1Identification EXTab. 1 2Further applicable documentsTechnical data for the product can have different values in other documents. For operation in an explosive atmosphere, the technical data in this document alwayshave priority.All available documents for the product è /pk.3FunctionWhen the compressed air supply ports are pressurized reciprocally, the internal slide in the pipe moves back and forth. The movement is transferred to the external slide by a rigid connection.4Safety 4.1Safety instructions–The device can be used under the stated operating conditions in zone 1 ofexplosive gas atmospheres.–All work must be carried out outside of potentially explosive areas.–Extraction of the operating medium outside the potentially explosive area.–The device is not intended for use with other fluids.4.2Intended useThe pneumatic linear drive is intended for the transportation of loads.4.3Identification X: special conditions –Danger of electrostatic discharge.–Ambient temperature: –10°C £ T a £ +60°C 5CommissioningThe discharge of electrostatically charged parts can lead to ignitable sparks. •Prevent electrostatic charging by taking appropriate installation and cleaningmeasures.•Include the device in the system’s potential equalisation.•The slide is electrically insulated from the actuator. Include the slide separately in the system potential equalisation.Installation and commissioning may only be performed in accordance with the operating instructions and by qualified personnel.Strong chargegenerating processes can charge nonconductive layers and coatings on metal surfaces.Escaping exhaust air can swirl up dust and create an explosive dust atmosphere.Related type of ignition protection: c (constructional safety)Particulate matter in the compressed air can cause electrostatic charges.–Observe the product labelling.–Seal unused openings with blanking plugs or slot covers.When using PPV endposition cushioning or shock absorbers:–Adjust the cushioning so that the piston rod safely reaches the end positionsand that it does not strike hard against them or rebound.–Only load the shock absorber in the axial direction. Avoid the generation oftransverse loads.6Maintenance and care–Check the operational reliability of the device regularly. Interval: 2 million movement cycles or after 6 months at the latest.–Clean the device with a damp cloth.–Lubricate the guide at the lubrication nipples in intervals. Interval: 400 km –Roller bearing cartridges of guide systems of the DGPL...KF und DGPL...HDafter a distance of 4500 km.Repairs of this type must only be carried out by trained and authorised specialists.–Please contact your Festo technical consultant.7Fault clearanceTab. 2 8Technical dataOperating conditionsMax. operating pressure [bar]8Ambient temperature [°C]–10 … +60Operating medium Compressed air to ISO 85731:2010 [7:4:4]Mounting position AnyDesignDoubleacting, with magnetic coupling, without piston rodTab. 38102472DGPL-...-EX3-...Linear drive8102472201811c [8102474]Festo SE & Co. KG Ruiter Straße 82 73734 Esslingen Germany+49 711 347。

layers 英文解释

layers 英文解释English Answer:Layers are a crucial concept in deep learning architectures. They are the fundamental building blocksthat transform input data into meaningful representations. Each layer in a neural network performs a specific operation or computation on the input, and the output of one layer becomes the input for the next. This process is repeated layer by layer until the final output is produced.Layers can be classified into different types based on their function and the operations they perform. Some common types of layers include:1. Convolutional Layers: Convolutional layers are designed to extract features from data, such as images or time series. They apply a filter or kernel to the input data, which slides over the input and computes the dot product between the filter and the local region of theinput. This process helps identify patterns andrelationships within the data.2. Pooling Layers: Pooling layers reduce the dimensionality of the feature maps generated byconvolutional layers. They combine neighboring values inthe feature map using operations like max pooling oraverage pooling. Pooling layers help reduce computational costs and control overfitting by reducing the number of parameters in the network.3. Activation Layers: Activation layers introduce non-linearity into the network. They apply non-linear functions, such as the ReLU (Rectified Linear Unit) or sigmoid function, to the output of the previous layer. Activation layers help the network learn complex relationships and make non-linear decisions.4. Fully Connected Layers: Fully connected layers are used to combine the features extracted by previous layers and make a final prediction or classification. Each neuronin a fully connected layer is connected to all neurons inthe previous layer. Fully connected layers are typically used in the final stages of a neural network architecture.The number and arrangement of layers in a deep learning architecture are determined by the complexity of the task and the size and nature of the input data. Deeper architectures, with more layers, can learn more complex relationships and solve more challenging problems. However, deeper networks also require more training data and computational resources.Optimizing the architecture of a deep learning model involves finding the right combination of layers and hyperparameters to achieve the best performance for the specific task. This process often involves experimentation and iterative refinement until a satisfactory model is obtained.中文回答：层是深度学习架构中的一个关键概念。

层序地层学的名词英语解释

层序地层学的名词英语解释GlossaryAccommodation. Another term for relative sea-level. Can be thought of as the space in which sediments can fill, defined at its base by the top of the lithosphere and at its top by the ocean surface.Basinward Shift in Facies. When viewed in cross-section, a shifting of all facies towards the center of a basin. Note that this is a lateral shift in facies, such that in vertical succession, a basinward shift in facies is characterized by a shift to shallow facies (and not a vertical shift to more basinward or deeper-water facies).Bed. Layer of sedimentary rocks or sediments bounded above and below by bedding surfaces. Bedding surfaces are produced during periods of nondeposition or abrupt changes in depositional conditions, including erosion. Bedding surfaces are synchronous when traced laterally; therefore, beds are time-stratigraphic units. See Campbell, 1967 (Sedimentology 8:7-26) for more information.Bedset. Two or more superposed beds characterized by the same composition, texture, and sedimentary structures. Thus, a bedset forms the record of deposition in an environment characterized by a certain set of depositional processes. In this way, bedsets are what define sedimentary facies. Equivalent to McKee and Weir's coset, as applied to cross-stratification. See Campbell, 1967 (Sedimentology 8:7-26) for more information.Condensation. Slow net rates of sediment accumulation. Stratigraphic condensation can occur not only through a cessation in the supply of sediment at the site of accumulation, but also in cases where the supply of sediment to a site is balanced by the rate of re moval of sediment from that site. Where net sediment accumulation rates are slow, a variety of unusual sedimentologic features may form, including burrowed horizons, accumulations of shells, authigenic minerals (such as phosphate, pyrite, siderite, glauconite, etc.), early cementation and hardgrounds, and enrichment in normally rare sedimentary components, such as volcanic ash and micrometeorites.Conformity. Bedding surface separating younger from older strata, along which there is no evidence of subaerial or submarine erosion or nondeposition and along which there is no evidence of a significant hiatus. Unconformities (sequence boundaries) and flooding surfaces (parasequence boundary) will pass laterally into correlative conformities, most commonly in deeper marine sediments.Eustatic Sea Level. Global sea level, which changes in response to changes in the volume of ocean water and the volume of ocean basins.Flooding Surface. Shortened term for a marine flooding surface.Highstand Systems Tract. Systems tract overlying a maximum flooding surface, overlain by a sequence boundary, and characterized by an aggradational to progradational parasequence set.High-Frequency Cycle. A term applied to a cycle of fourth order or higher, that is, having a period of less than 1 million years. Parasequences and sequences can each be considered high-frequency cycles when their period is less than 1 million years. Isostatic Subsidence. Vertical movements of the lithosphere as a result of increased weight on the lithosphere from sediments, water, or ice. Isostatic subsidence is a fraction of the thickness of accumulated material. For example, 100 meters of sediment will drive about 33 meters of subsidence (or less, depending on the rigidity of the lithosphere).Lowstand Systems Tract. Systems tract overlying a type 1 sequence boundary, overlain by a transgressive surface, and characterized by a progradational to aggradational parasequence set.Marine Flooding Surface. Surface separating younger from older strata, across which there is evidence of an abrupt increase in water depth. Surface may also display evidence of minor submarine erosion. Forms in response to an increase in water depth.Maximum Flooding Surface. Marine flooding surface separating the underlying transgressive systems tract from the overlying highstand systems tract. This surface also marks the deepest water facies within a sequence. This flooding surface lies at the turnaround from retrogradational to progradational parasequence stacking, although this turnaround may be gradational and characterized by aggradational stacking. In this case, a single surface defining the point of maximum flooding may not be identifiable, and a maximum flooding zone is recognized instead. The maximum flooding surface commonly, but not always, displays evidence of condensation or slow deposition, such as burrowing, hardgrounds, mineralization, and fossil accumulations. Because other flooding surfaces can have evidence of condensation (in some cases, more than the maximum flooding surface), condensation alone should not be used to define the maximum flooding surface. Meter-Scale Cycle. A term applied to a cycle with a thickness of a couple of meters or less. Parasequences and sequences can each be considered meter-scale cycles when they are thinner than a couple of meters.Parasequence. Relatively conformable (that is, containing no major unconformities), genetically related succession of beds or bedsets bounded by marine-flooding surfaces or their correlative surfaces. Parasequences are typically shallowing-upward cycles.Parasequence Boundary. A marine flooding surface.Parasequence Set. Succession of genetically related parasequences that form a distinctive stacking pattern, and typically bounded by major marine flooding surfaces and their correlative surfaces. Parasequence set boundaries may coincide with sequence boundaries in some cases. See progradational, aggradational and retrogradational parasequence sets.Peritidal. All of those depositional environments associated with tidal flats, including those ranging from the highest spring tides to somewhat below the lowest tides.Relative Sea Level. The local sum of global sea level and tectonic subsidence. Locally, a rise in eustatic sea level and an increase in subsidence rates will have the same effect on accommodation. Likewise, a fall in eustatic sea level and tectonic uplift will have the same effect on accommodation. Because of the extreme difficulty in teasing apart the effects of tectonic subsidence and eustatic sea level in regional or local studies, sequence stratigraphy now generally emphasizes relative changes in sea level, as opposed to its earlier e mphasis on eustatic sea level.Sequence. Relatively conformable (that is, containing no major unconformities), genetically related succession of strata bounded by unconformities or their correlative conformities.Sequence Boundary. Form in response to relative falls in sea level.Sequence Stratigraphy. The study of genetically related facies within a frameworkof chronostratigraphically significant surfaces.Shelf Margin Systems Tract. Systems tract overlying a type 2 sequence boundary, overlain by a transgressive surface, and characterized by a progradational to aggradational parasequence set. Without regional seismic control, most shelf margin systems tracts may be unrecognizable as such and may be inadvertently lumped with the underlying highstand systems tract as part of one uninterrupted progradational parasequence set. If this occurs, the overlying transgressive surface may be erroneously inferred to also be a type 1 sequence boundary.Systems Tract. Linkage of contemporaneous depositional systems, which are three-dimensional assemblages of lithofacies. For example, a systems tract might consist of fluvial, deltaic, and hemipelagic depositional systems. Systems tracts are defined by their position within sequences and by the stacking pattern of successive parasequences. Each sequence consists of three systems tract in a particular order. For a type 1 sequence, these are the lowstand, transgressive, and highstand systems tracts. For a type 2 sequence, these are the shelf margin, transgressive, and highstand systems tracts.Tectonic Subsidence. Vertical movements of the lithosphere, in the absence of any effects from changes in the weight of overlying sediments or water. Also called driving subsidence. Tectonic subsidence is generated primarily by cooling, stretching, loading (by thrust sheets, for example), and lateral compression of the lithosphere.Transgressive Surface. Marine flooding surface separating the underlying lowstand systems tract from the overlying transgressive systems tract. Typically, this is the first major flooding surface following the lowstand systems tract. In depositionally updip areas, the transgressive surface is commonly merged with the sequence boundary, with all of the time represented by the missing lowstand systems tract contained within the unconformity. The transgressive surface, like all of the major flooding surfaces within the transgressive systems tract, may display evidence of stratigraphic condensation or slow net deposition, such as burrowed surfaces, hardgrounds, mineralization, and fossil accumulations.Transgressive Systems Tract. Systems tract overlying a transgressive surface, overlain by a maximum flooding surface, and characterized by a retrogradational parasequence set.Type 1 Sequence Boundary. Characterized by subaerial exposure and associated erosion from downcutting streams, a basinward shift in facies, a downward shift in coastal onlap, and onlap of overlying strata. Forms when the rate of sea-level fall exceeds the rate of subsidence at the depositional shoreline break (usually at base level or at sea level). Note that this means that if such changes can be observed in outcrop and the underlying strata are marine, then the boundary is a type 1 sequence boundary.Type 2 Sequence Boundary. Characterized by subaerial exposure and a downward shift in onlap landward of the depositional shoreline break (usually at base level or at sea level). Overlying strata onlap this surface. Type 2 sequence boundaries lack subaerial erosion associated with the downcutting of streams and lack a basinward shift in facies. Forms when the rate of sea-level fall is less than the rate of subsidence at the depositional shoreline break. Note that the lack of a basinward shift in facies and the lack of a relative fall in sea level at the depositional shoreline break means that there are essentially no criteria by which to recognize a type 2 sequence boundary in outcrop.Unconformity. Surface separating younger from older strata, along which there is evidence of subaerial erosional truncation or subaerial exposure or correlative submarine erosion in some areas, indicating a significant hiatus. Forms in response to a relative fall in sea level. Note that this is a much more restrictive definition of unconformity than is commonly used or used in earlier works on sequence stratigraphy (e.g., Mitchum, 1977).Walther's Law states that "...only those facies and facies areas can be superimposed, without a break, that can be observed beside each other at the present time" (Middleton translation from German). At a Waltherian contact, one facies passes gradationally into an overlying facies, and those two facies represent sedimentary environments that were originally adjacent to one another.Water Depth. The distance between the sediment surface and the ocean surface. Water depth is reflected in sedimentary facies. A very large number of studies that purport to describe sea-level changes (both eustatic and relative) are actually only describing changes in water depth. The effects of isostatic subsidence and compaction must be removed from water depth to calculate relative sea level. This is typically done through backstripping. To calculate eustatic sea level, the rate of tectonic subsidence must then be subtracted from the relative sea-level term.。

Thesis statement 例子

Thesis statement一句话指出研究内容----详细列出主体章小标题内容---文章结论美国女性职场歧视微观原因及解决方案-以《Lean In》为例C.Thesis statementThis dissertation is an attempt to address the issue of microscopic factors of discrimination in US workplace against women. It will dig out several internal obstacles and find out effective solutions using gender theory as the main theoretical framework and setting “Lean In” which is written by Sheryl Sandberg as the case study. Although nearly whole society are concentrating on social and cultural aspects, “how to overcome the internal barriers” is sometimes more valuable if women aspire to increase the chances of being leaders in their fields and pursuing their career goals. This essay is going to analyze three main internal reasons that hindered the development of women’s careers. They are self-doubt, passive acceptation of stereotypical expectations and competition consciousness deficiency. Thus, a conclusion could be reached-being self-confident, being themselves ignoring what others say and taking risks in their careers instead of holding back will be the most effective ways to help women to overcome the internal barriers, hold more top positions and reach their career goals.西方消费主义对当代大学生的影响及原因C. Thesis statementThis paper will explore the characteristics of contemporary college students’ consumption and how the consumerism impacts their consumption action. On one hand, something new has occurred on college students’ consumpt ion, for example, overconsumption. These sorts of consumption are irrational. On the other hand, western values are increasingly dominant over these students’ mind. Among them is the conception----modern consumerism. Therefore, it is concluded that western consumerism has more or less guided college students’ consumption behavior. This paper will present a picture of their consumption deeds and cast light on why they are influenced by the western consumerism.从霍尔编解码理论看中国元素在美国动画电影中的运用—以《功夫熊猫》为例C. Thesis statementThis paper utilizes the Stuart Hall’s encoding-decoding theory in order to make a comprehensive analysis of the Chinese elements, which spread into Hollywood animation movies. It explores t he images of Chinese elements first-encoded in American animation movies from the aspects of character settings, scene settings and Chinese traditionalphilosophy. By analyzing with the second encoding theory, it analyzes the implantation of American culture such as individualism and heroism. It can be concluded that Chinese should learn from American animation industry and be the spokesmen for their own Chinese culture.从美国话语霸权视角看美国民主输出-以“中国威胁论”为例C. Thesis statementThe proportion of cultural factors in international politics has risen, while American democracy output has put more emphasis on culture field. This thesis makes a tentative study from a specific aspect of American culture output—discourse hegemony, by analyzing typical case,“China Threat Theory”, to have a macroscopical view on American discourse hegemony construction, and have a clear understanding of the political meanings of “China Threat Theory”. Finally conclusion is reached that driven by American scholar expounding, official behavior promotion, and mass media’s propaganda, America has successfully schemed a diplomatic conspiracy—“China Threat Theory”.。

Temperature dependence of the passivation layer on graphite

Ž.Journal of Power Sources 81–821999286–290 r locate r jpowsourTemperature dependence of the passivation layer on graphitea,)a b ˚bA.M.Andersson,K.Edstrom ,N.Rao ,A.Wendsjo ¨¨a˚Inorganic Chemistry,Angstrom Laboratory,Uppsala Uni Õersity,Box 538,SE-75121Uppsala,Sweden¨bDanionics,Hesteha Õen 21J,DK-5260Odense S,DenmarkAbstractŽ.The elevated temperature stability of the Solid Electrolyte Interface SEI formed on graphite during the first charge r discharge cycle has been investigated.This was done in order to determine its role in the high-temperature degradation process which occurs in a Ž.C r LiMn O Li-ion cell.X-ray photoelectron spectroscopy XPS is used to probe the surface-layer growth and elemental composition of 24graphite electrodes exposed to different thermal treatment.The surfaces of cycled electrodes,when stored below 608C,were seen to resemble closely those of unstored electrodes.An electrode stored at 608C exhibited a significant increase in the amount of oxidized carbon and oxygen.Analysis by Ar sputtering suggests that a thick ‘macroscopic’layer coats the graphite electrode surface,but not the separate graphite grains;this is consistent with the observed rapid decrease in capacity and large cell-resistance on cycling such cells after storage.This capacity decrease was not observed for the cells stored at RT and 408C.q 1999Elsevier Science S.A.All rights reserved.Keywords:Li-ion batteries;Graphite anode;High-temperature performance;X-ray photoelectron spectroscopy1.IntroductionAmbient and elevated temperature stability is a crucial factor in the performance of batteries for the ever-growing portable electronics market.Poor performance and prema-ture ‘cell death’have been reported for C r LiMn O Li-ion 24w x cells exposed to temperatures above 558C 1.Several groups have reported various parasitic reactions occurring at the cathode.Typically,oxidation of the electrolyte occurs at the spinel surface when the cell is charged and w x the open circuit potential is high 2.Moreover,these reactions are more aggressive at elevated temperatures.Manganese dissolution reactions also threaten high-temper-ature cathode stability;the spinel electrode is corroded by traces of HF in the electrolyte,and Mn 2q ions are trans-w x ferred to the electrolyte 1.Although such cathode-related reactions tend to be seen as the major contributor to high-temperature cell failure,the carbon electrode is also known to be unstable at these temperatures.In a charged cell,with Li q ions intercalated into the carbon,the Li C x phases and the electrolyte are believed to undergo an exothermic reaction at elevated temperatures,leading to delithiation of the carbon and the formation of an addi-Ž.tional solid electrolyte interface SEI layer on top of thatCorresponding author.Tel.:q 44-18-471-37-37;Fax:q 44-18-51-35-48;E-mail:ami@kemi.uu.se.already formed on the carbon surface,with resulting loss w x of capacity 3,4.However,the extent to which these reactions occur,and how they are related to the salts and solvents used in the electrolyte,have so far not been fully investigated.The destruction of the SEI layer in the dis-charged state,brought about by temperature induced reac-tions between the SEI and electrolyte species,has been discussed in earlier publications,but has not been analysed w x completely 4.The use of graphitic carbon as active anode material in Li-ion cells provides for a high energy density and good cycling performance.While the formation of the SEI layer Žon the graphite particles during the first charging tion of the cell brings with it certain disadvantages Ž.irreversible capacity loss ,provided that the film remains thin and covers the entire graphite surface,it preserves the favourable electrochemical properties of the graphite.The composition,functionality and morphology of the SEI layer is determined by the salts and solvents used in the electrolyte.The film formed on the graphite grains during the first charge,using LiBF salt in the standard EC r DMC 4alkyl carbonate liquid electrolyte,is known to contain some electrolyte–solvent reaction products such as Li CO 23and CH CO Li,and additional salt and trace–water reduc-33tion products,mainly LiF,as determined by FTIR spec-w x troscopy 5.While this technique provides qualitative information about the nature of the surface,X-ray Photo-0378-7753r 99r $-see front matter q 1999Elsevier Science S.A.All rights reserved.Ž.PII:S 0378-77539900202-5()A.M.Andersson et al.r Journal of Power Sources81–821999286–290287Fig.1.Reduction charge vs.cycle number for Li r graphite half-cellsŽ. precycled three times at room temperature cycle nos.1–3prior to storage at different temperatures for7days,followed by continued cycling at these same temperatures.electron Spectroscopy provides a quantitative analysis ofw x the surface composition and surface-layer thickness6. These features have been exploited here,where the main goal has been to analyse specifically the stability of the SEI layer on graphite at elevated temperatures.This has been done for standard Li r C half-cells,using the standard electrolyte referred to above,as a model system.GraphiteŽ. electrodes are analysed in their discharged deintercalated state,so that the reactions which relate solely to the SEI layer can be focused upon,without interference from other temperature related reactions at the anode or cathode,such as delithiation or Mn dissolution related reactions.2.Experimental2.1.Half-cell preparationCarbon electrodes were typically prepared by spreadingŽa mix of90wt.%Timrex KS6graphite Timcal,Switzer-.land,5wt.%Shewinigan Black carbon powder and5 wt.%EPDM rubber binder in cyclohexane onto a porousŽNi-foil current collector Fukuda Metal Foil and Powder, .Japan.The graphite loading on the current collector was typically5.4mg r cm2.The electrodes were cut into7or 25cm2pieces and dried under vacuum at1208C,before laminating them with a glass-wool separator soaked in electrolyte and the Li-foil counter electrode.A Li reference electrode was also placed in the battery stack to facilitate three-electrode studies.The laminates were packed in polymer-coated aluminium bags,evacuated and sealed.The electrolyte used in all experiments was1M LiBF4Ž.Ž.Žw Tomiyama in EC r DMC2:1Selectipur,Merck,.Darmstadt,Germany.The salt was dried in vacuum at 1208C prior to use,and the solvents were used as re-ceiÕed.The cells were assembled and packed in an argon-Ž.filled glove-box-3ppm H O and O.222.2.Electrochemical measurementsAll cell-cycling experiments were conducted at C r2 rate.The three-electrode set-up was used to follow exclu-sively the potential changes of the graphite electrode. Equivalent cells were precycled three times between10 mV and1.5V,with a relaxation period of10min at the end of each discharge r charge.The cycling procedure was interrupted at the 1.5V cut-off voltage,i.e.,with the graphite electrodes in their deintercalated state.The SEI layer formed during these initial cycles is generally seen as a thin,uniform film which provides a perfect passivation layer for the graphite grains.The chem-ical features of this film were analysed by DSC and XPS Ž.see below.The precycling of a number of equivalentŽ.cells was followed by storing the cells at208C RT,408C or608C for7days,to allow any reactions occurring at these temperatures to reach completion.Three of these stored electrodes were then also analysed with XPS,while the remainder of the cells continued to cycle at C r2rate at the same temperatures at which they had been stored.The resistance of the cells was measured during the relaxation period at the end of each discharge while the current was declining toward zero.2.3.DSC measurementsThe precycled,vacuum-sealed cells were dismantled in an Ar filled glove-box,and the electrodes were cut into Ž.small pieces 5.20mg of active material,and sealed in standard Al crucibles.The measurements were carried out on a Mettler DSC30calorimeter,with the heating rate set at58C r min in the temperature range208C to4008C. Complementary measurements were made on the‘pure’materials used in the cells,e.g.,Li metal foil,Li-salts, solvents,graphite powder,Ni-foil current collector and EPDM binder,and mixturesthereof.Fig.2.Plots of d Q r d V vs.potential during the first cycle for cells stored at different temperatures.The cycling is conducted at the same tempera-tures as the storage.()A.M.Andersson et al.r Journal of Power Sources 81–821999286–290288Fig.3.Resistance at the end of discharge plotted as a function of cycle number and storage temperature.2.4.XPS measurementsThe XPS measurements were conducted on a PHI 5500system,using an Al K a excitation source.The cells which had been exposed to the various pre-treatments were cut open in the glove-box and small pieces of the graphite electrodes were mounted on XPS sample holders.The holders were then vacuum-sealed in a polymer laminated aluminium bag in the glove-box,and transported to the XPS apparatus where they were cut open and placed in the Ž.spectrometer introduction chamber under a flow of N g .2The samples were first analysed as prepared,and then sputtered with an Ar beam until the amounts of the differ-ent elements reached a ‘steady state’at which the surface layer of the topmost graphite grains had been sputtered off.They were then reanalysed.All cycling and XPS studies were performed twice;essentially the same results were obtained.3.Results3.1.Electrochemical cyclingThe total reduction charge of the different cells have been extracted from the cycling data and plotted vs.num-ber of cycles;the results are shown in Fig.1.Ž.Fig.4.DSC trace of a deintercalated graphite electrode no storage.Fig.5.Elemental analysis of the graphite electrode surface;LiBF and 4graphite contribution is subtracted.The increased intercalation capacities in cycle 4for the samples stored above room temperature suggest secondary redox reactions occurring in the cell.d Q r d V plots for cycle 4reveal no additional solvent reduction around 0.7V as in the formation of the original SEI film;there is,however,an additional reduction peak at 0.3V for the cell Ž.stored at 608C Fig.2.The cells stored at RT and 408C could be cycled continuously from cycle 5onward with only small losses in capacity.The cells stored at 608C,however,showed a continuous loss in capacity,leading to ‘cell death’within 10cycles.The resistance of the heat-treated cells clearly increases after storage,becoming more than 3times larger Ž.for the ‘608C cell’on continued cycling Fig.3.Fig.6.The influence of storage temperature on the C1s XPS spectrum of Ž.Ž.Ž.Ž.graphite electrodes;a storage at 608C,b 408C,c 208C,d unstored electrode.()A.M.Andersson et al.r Journal of Power Sources 81–821999286–290289Spinel cathode half-cells treated in the same way as above display neither the increased reduction charge dur-ing cycle 4,nor the large drop in capacity on continued cycling.The elevated temperature performance of the graphite half-cells is thus not a result of poor Li-electrode performance,but reflects graphite electrode and electrolyte effects alone.3.2.DSC resultsFig.4shows the DSC trace for a deintercalated graphite electrode after cycles 1–3.Two features can be observed:the large endothermic peak assigned to chemical reactions involving the electrolyte solution,and the exothermic peak with its maximum at 79.58C which can be assigned to a reaction involving the SEI layer.3.3.XPS resultsThe elements detected on the surface of the graphite electrodes were,in all cases:F,O,C,B and Li,where certain peak shifts could be assigned directly to the LiBF 4salt,LiF and graphite.The amount of each element was calculated by integrating the intensities of the XPS peaks and correcting for the cross-section for the ionisation of each element.The contribution from LiBF and graphite 4were subtracted in the elemental analysis of the surface layer.The relative concentrations of the different elements found on the surface of the stored and unstored samples are shown in Fig. 5.An increase in Li and F content occurs on storing the samples at RT and 408C.The shifts in the Li and F peaks were assigned to the formation of LiF.The C and O content on the surface increased signifi-Ž.cantly for the sample stored at 608C Fig.5.The C1sXPSFig.7.Elemental analysis of the graphite electrode surface after Ar sputtering until a compositional ‘steady state’is reached;LiBF and 4graphite contribution subtracted.Ž.peak shifts Fig.6clearly show the evolution of C,with higher oxidation state on the surface of the ‘608C elec-trode’.The C and O increase is coupled to a decrease in Li and F content.Fig.7shows the relative concentrations of the elements on the graphite surface after Ar sputtering.It is clear that,when the outer layer of the electrode had been removed by sputtering,the electrodes had a very similar composition.A compositional ‘steady state’was reached for the electrodes stored at RT and 408C after less than 40s sputtering;however,it took more than 10min to ar-rive at a constant C concentration for the electrode stored at 608C.4.DiscussionFrom the above,the surface species on the graphite electrode are clearly seen to be influenced by elevated temperature.Evidence of several types of contributing reaction can be distinguished in the measurements.The XPS measurements indicate that storing the cells caused an increase in LiF content on the graphite electrode Ž.surfaces Fig.5;presumably a product of the acid–base w x reaction suggested by Kanamura et al.6:LiBF q H O ™2HF q LiF q BOF1Ž.42This reaction can occur both on the graphite surface and in the bulk electrolyte;the precipitation of LiF is,therefore,w x not limited to the surface.Aurbach et al.have proposed 5the conversion of Li CO on the graphite surface to LiF 23according to:Li CO q 2HF ™2LiF q H CO 2Ž.2323This type of reaction is typical for LiPF -and LiBF -con-64taining electrolytes,but is claimed to be more pronounced in the latter case.However,the LiF layer covering the graphite grains seems to remain sufficiently thin or porous to allow reasonable transport of the Li q ions during the continued cycling,even up to 408C.The graphite shift in Ž.the C peak at 284.2eV for the ‘208C electrode’and ‘408C electrode’is still clearly observable after storage Ž.Fig.6,which again suggests only small changes in the thickness of the surface layer.The relatively large amount of LiF formed on the graphite surface would seem to ŽŽ..precipitate from the electrolyte Eq.1to form small clusters within the electrode,leaving most of the graphite surface available for Li q -ion penetration.Cells stored at 608C experience more severe damage to the graphite electrode surface.The XPS results clearly show that an additional surface layer is formed during the storage.The elemental composition of all stored electrodes was very similar,however,after Ar sputtering,which would indicate that the secondary layer on the 608C sam-ple,is formed ‘macroscopically’on the electrode surface,and does not surround each individual graphite grain,as Ž.does the SEI layer Fig.8.()A.M.Andersson et al.r Journal of Power Sources 81–821999286–290290Fig.8.A schematic representation of a graphite electrode stored at 608C for 7days.The roughness of the electrodes means that it is difficult to estimate the actual thickness of the surface layers on the graphite.The mosaicity of species that build up the differ-ent layers also implies that it is difficult to relate sputtering time and sputtering depth.XPS measurements on reference samples with known surface-layer thickness are needed.It is clear from Fig.6,however,that the intensity of the graphite shift in the ‘608C electrode’has decreased signifi-cantly as the surface layer has grown.The thicker layer can function as a shield which effectively hinders the Li q ions from penetrating through to the active electrode.The XPS result is consistent with the electrochemical cycling experiments,which also indicate a blocking of the elec-trode and accompanying capacity fade for the ‘608C cell’.Additional redox reactions during cycle 4,resulting in the irreversible capacity loss,may also have implications for the subsequent cycling performance.These reactions can arise from a number of sources,e.g.,exposure of the graphite surface through the dissolution of the passivation Ž.layer Li carbonates,etc.,changes in the graphite surface Ž.structure e.g.,exfoliation and the subsequent formation of a second SEI layer.Further studies are needed,how-ever,to better understand the origins of this process.5.ConclusionsThe surface chemistry of a graphite anode in conjunc-tion with an electrolyte containing LiBF is clearly af-4fected by treatment at elevated temperature.Galvanostatic cycling in conjunction with XPS has been used here in a novel way to characterise electrochemical performance,surface composition and passivation layer growth on graphite electrodes cycled and stored in their deinterca-lated state.The XPS measurements are compatible with a model assuming an additional passivation layer on the ‘macro-scopic’surface of the graphite electrode for Li r C half-cells stored at 608C.The thickness of this new layer far exceeds that of the original SEI layer,even if this cannot be quantified at this stage.An increase in cell resistance and a related rapidly declining capacity is observed for these cells;this is consistent with the creation of an additional surface layer.Storing the cells also causes an increase in the amount of LiF on the surface of the electrodes at all temperatures.AcknowledgementsŽ.This work has been supported by the EU Joule III Programme,and in Sweden by The Swedish Natural Sci-Ž.ence Research Council NFR and The Board for Techni-Ž.cal Development NUTEK within projects led by Prof.Josh Thomas.Referencesw x 1G.G.Amatucci,C.N.Schmutz,A.Blyr,C.Sigala,A.S.Gozdz,D.Ž.Larcher,J.M.Tarascon,J.Power Sources 69199711.w x Ž.2 D.H.Jang,Y.J.Shin,S.M.Oh,J.Electrochem.Soc.14319962204.w x 3U.von Sacken,E.Nodwell,A.Sundher,J.R.Dahn,J.Power SourcesŽ.541995240.w x 4 A.Blyr,C.Sigala,G.Amatucci,D.Guyomard,Y.Chabre,J.M.Ž.Tarascon,J.Electrochem.Soc.1451998194.w x 5 D.Aurbach,Y.Ein-Eli, B.Markovsky, A.Zaban,S.Luski,Y.Ž.Carmeli,H.Yamin,J.Electrochem.Soc.14219952882.w x 6K.Kanamura,H.Tamura,S.Shiraishi,Z.Takehara,J.Electrochem.Ž.Soc.1421995340.。

等离激元共振峰英文

等离激元共振峰英文全文共四篇示例，供读者参考第一篇示例：Plasmon Resonance PeakIntroductionPlasmon resonance is a collective oscillation of free electrons in a material that occurs when the frequency of incident light matches the natural frequency of the electrons in the material. This phenomenon is often observed in metallic nanoparticles, where the conduction electrons can be excited by incident electromagnetic radiation. One of the most prominent features of plasmon resonance is the appearance of a distinct peak in the absorption or scattering spectra of the material, known as the plasmon resonance peak or plasmon resonance band.第二篇示例：Plasmon resonance refers to the collective oscillation of free electrons in a metal when it is subjected to electromagnetic radiation. This phenomenon, also known as surface plasmon resonance (SPR), has been extensively studied and applied invarious fields such as sensing, imaging, and light manipulation. One of the key features of plasmon resonance is the emergence of a characteristic peak in the absorption or scattering spectrum, known as the plasmon resonance peak or plasmon resonance band. In this article, we will focus on a specific type of plasmon resonance peak – the localized surface plasmon resonance peak, which is commonly referred to as the plasmon resonance peak.第三篇示例：Plasmonic resonance peak, also known as localized surface plasmon resonance (LSPR) peak, is a phenomenon in which free electrons in a metal nanoparticle oscillate collectively in response to incident light. This oscillation creates a strong electromagnetic field enhancement around the nanoparticle, leading to enhanced light-matter interactions. The spectral position of the plasmonic resonance peak, known as the plasmon resonance wavelength, depends on the size, shape, composition, and surrounding environment of the nanoparticle.第四篇示例：One specific type of surface plasmon resonance that has attracted attention is the localized surface plasmon resonance (LSPR) peak. LSPR peaks manifest as sharp extinction peaks inthe absorption or scattering spectra of metal nanoparticles due to the resonance between incident light and the localized surface plasmons on the nanoparticle surface. These peaks are highly sensitive to the size, shape, and composition of the nanoparticle, making them an excellent candidate for various applications such as chemical sensing, biological detection, and single molecule analysis.。

化境sublimation英文介绍

化境sublimation英文介绍Sublimation: The Transformative Journey of MatterThe concept of sublimation, a fundamental principle in the realm of physical chemistry, is a captivating and intricate phenomenon that has fascinated scientists and philosophers alike. Sublimation, the direct transition of a substance from the solid phase to the gaseous phase without passing through the liquid phase, is a remarkable process that defies the conventional understanding of matter and its behavior. This unique transformation not only challenges our perception of the physical world but also unveils the underlying complexities and interconnectedness that govern the very fabric of our universe.At its core, sublimation is a testament to the versatility and adaptability of matter. Unlike the more commonly observed phase changes, such as melting and boiling, sublimation presents a direct pathway for solids to transition into the gaseous state, bypassing the intermediate liquid phase. This process is driven by the delicate balance of intermolecular forces and the inherent energy dynamics within the material itself. As the solid substance is exposed to sufficient heat or reduced pressure, the kinetic energy of themolecules increases, causing them to break free from the rigid crystalline structure and transition directly into the gaseous state.The phenomenon of sublimation is not merely a scientific curiosity but has profound implications in various fields of study. In the realm of atmospheric science, the process of sublimation plays a crucial role in the formation and evolution of clouds, snow, and ice crystals. The transformation of solid water molecules into water vapor, without first passing through the liquid phase, is a key factor in the complex dynamics of weather patterns and climate systems. This understanding has far-reaching consequences, as it enables meteorologists to better predict and model the behavior of atmospheric phenomena, ultimately contributing to our ability to anticipate and respond to environmental changes.Furthermore, the study of sublimation has found applications in diverse industries, from the pharmaceutical sector to the semiconductor industry. In the pharmaceutical realm, the controlled sublimation of certain active pharmaceutical ingredients (APIs) is a crucial step in the development of effective and stable drug formulations. By carefully manipulating the sublimation process, pharmaceutical researchers can optimize the physical and chemical properties of these compounds, improving their bioavailability, solubility, and overall therapeutic efficacy. Similarly, in the semiconductor industry, the process of chemical vapor deposition(CVD), which relies on the sublimation of solid precursors, is a fundamental technique used in the fabrication of thin-film coatings and the growth of high-quality crystalline materials essential for electronic devices.Beyond its practical applications, the phenomenon of sublimation has also captured the imagination of philosophers and thinkers throughout history. The concept of sublimation has been explored in the realms of art, literature, and psychology, where it has been used as a metaphor for the transformation of the human spirit and the transcendence of the physical realm. In Sigmund Freud's psychoanalytic theory, for example, sublimation is recognized as a defense mechanism in which the energy associated with unacceptable or socially taboo desires is redirected towards more socially acceptable and constructive pursuits, such as artistic expression or intellectual endeavors.In the realm of art, the notion of sublimation has been a source of inspiration for countless creators. The ability of matter to transform directly from solid to gas, defying the conventional understanding of physical states, has been a powerful metaphor for the human capacity to transcend the limitations of the material world. Numerous works of art, from the ethereal sculptures of Anish Kapoor to the poetic writings of Rainer Maria Rilke, have explored the themes of sublimation, capturing the essence of this transformativeprocess and its impact on the human experience.In the end, the phenomenon of sublimation is a testament to the incredible complexity and dynamism of the physical world. It is a process that not only challenges our understanding of matter and its behavior but also serves as a bridge between the realms of science, philosophy, and the human experience. By delving deeper into the intricacies of sublimation, we gain a greater appreciation for the interconnectedness of the natural world and the profound insights it can offer into the very nature of our existence. As we continue to explore and unravel the mysteries of this transformative process, we may find that the boundaries between the physical and the metaphysical become increasingly blurred, opening up new avenues for discovery and a deeper understanding of the world we inhabit.。

LAYOUT详解1

Multiple contacts (reliability issue)
Metal
Oxide
I
I
IC Technology & Layout
SUBSTRATE BIASING
❒ Biasing must be as close as possible to the active devices ❒ Any noisy signal affecting the substrate or the well should be sinked by the biasing and not affecting the circuit itself
layoutaccuracyofresistorsthesheetresistanceisprettylow?longstripsmustbeusedserpentineshapesarecommonlyused?problemsofcornersestimatedhalfasquare?undercutwidthreduction?boundarydependentundercut?parametersgradientrr?????2l?l????2ww?????2?????2xjxj?????2ictechnologyamp
TYPICAL CMOS P-WELL PROCESS
– contact opening – metal deposition possibly: – thermal oxidation – via opening – second metal layer deposition – final passivation using silicon nitride (Si3N4) (typical thickness 1 µm)

UV固化条件聚合动力学和光泽度聚氨酯丙烯酸酯涂料的

Progress in Organic Coatings 76 (2013) 432–438Contents lists available at SciVerse ScienceDirectProgress in OrganicCoatingsj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /p o r g c o atInﬂuence of UV-curing conditions on polymerization kinetics and gloss of urethane acrylate coatingsViera Janˇc oviˇc ová∗,Milan Mikula,Bohuslava Havlínová,Zuzana JakubíkováInstitute of Polymer Materials,Department of Graphics Arts Technology and Applied Photochemistry,Faculty of Chemical and Food Technology,Slovak University of Technology,Radlinského 9,SK-81237Bratislava 1,Slovak Republica r t i c l ei n f oArticle history:Received 21April 2012Received in revised form 28September 2012Accepted 20October 2012Available online 14 November 2012Keywords:Photopolymerization Urethane acrylate Kinetics FTIR Glossa b s t r a c tThe photochemically curable polymer ﬁlms were prepared by addition of 2,2-dimethyl-2-hydroxyacetophenone (Darocure 1173)as a radical initiator to aliphatic urethane tetraacrylate Craynor 925.Kinetic study of the UV-curing of these ﬁlms by medium pressured mercury lamp was performed by means of infrared spectroscopy.The results showed that the photoinitiator concentration,the light inten-sity,sample coating thickness,presence of air oxygen,as well as the UV light intensity were the most signiﬁcant factors affecting the polymerization course of UV-cured ﬁlms.The inﬂuence of the sample coating thickness on the kinetics and ﬁnal gloss were also considerable.© 2012 Elsevier B.V. All rights reserved.1.IntroductionLight induced curing in polymer coating systems has been intensively studied due to environmental protection,lower energy consumption and rapid curing even at the room temperature.One of the most effective methods of fast generation of spatial crosslinked polymers is based on a multifunctional monomer or oligomer exposed by UV light in the presence of an initiator [1–3].Therefore,UV-curing technology has been considered as an alterna-tive to traditional solvent-borne coatings,due to its eco-compatible process and excellent properties,such as high hardness,gloss,scratch and chemical resistance caused by high crosslink density from acrylate groups [4].Desired ingredients in radically cured formulations are ure-thane acrylate oligomers providing chemical,water resistance and heat resistance and adhesion.Polyurethane acrylate resins are often used in the liquid state as precursors to produce three-dimensional networks giving high-performance ﬁnal materials [5].As UV curable resins they prove excellent adhesion,ﬂexibility,impact property,chemical and scratch resistance and weather-ability [6,7]but often suffer from the high viscosities.They are commercially available with molecular weights ranging from 600g/mol to 6000g/mol and with functionalities ranging from 2to 6.Depending on molecular weight and chemical structure,hard∗Corresponding author.Tel.:+421259325227;fax:+421252493198.E-mail address:viera.jancovicova@stuba.sk (V.Janˇc oviˇc ová).stiff to ﬂexible coatings can be prepared in a broad range of prop-erties [8,9].The photoinitiated polymerization with photoinitiatorDarocure 1173(2-hydroxy-2-methyl-1-phenylpropane-1-one)was studied and the maximal conversion was obtained at 70◦C [10].Several authors dealt with water based urethane acrylate coatings.The advantages offered by these environment-friendly systems are partially offset by the necessity to introduce a drying step before the UV-exposure,which will increase the overall processing time.The water sensitivity of these UV-cured polymers and their hydrophilic character may also restrict their use in a humid environment and in exterior applications [11,12].The important aspect of a coated material in terms of qual-ity is a gloss [13–16].It is inﬂuenced by many factors such as rheological properties and formulation of the coating,ﬁlm ﬂat-tening,curing rate,layer thickness,refraction index,substrate characteristics (roughness,pore size distribution),ﬁlm curing behaviour (wrinkling,cratering,and yellowing),etc.In principle,the gloss is a complex phenomenon resulting from the interaction between light and the surface of the coating.Kim et al.studied the inﬂuence of coating composition and curing conditions on the ﬁnal surface properties (pencil hardness and coating gloss).They found out that some gloss decrease can be caused by oxygen inhibition of polymerization.If simultaneously the lower layers are cross-linked,then shrinkage could occur resulting in puckering or wrinkling in the top layer.Consequently,the wrinkled pattern on the surface leads to low gloss since the surface is no longer smooth [17].The inﬂuence of the curing conditions (UV light intensity,coating thickness)and coating formulation (photoinitiator type0300-9440/$–see front matter © 2012 Elsevier B.V. All rights reserved./10.1016/j.porgcoat.2012.10.010V.Janˇc oviˇc ováet al./Progress in Organic Coatings76 (2013) 432–438433and concentration)on the UV-curing of1,6-hexandioldiacrylate andﬁnal gloss of the cured surface was signiﬁcant.In these low viscose formulations the gloss was decreasing during the curing process.The gloss decrease of the coatings thicker than15␮m was considerable,which might be caused by shrinking of the sample surface during its curing[15].Ruiz and Machado[16]discussed the behaviour of UV-clear coats submitted to degradation processes on the basis of gloss changes.The authors found that the composition of the curing system and the curing conditions effectively affect the rate of polymerization,the maximum conversion reached and the surface properties,including gloss,hydrophobicity,surface energy.Gloss is important parameter in the printing technology, providing products with a better overall look,higher chroma (greater depth of colours)[15].UV-cured urethane acrylate clear coats are suitable to function as protective coating for prints,their advantage is an improvement in the surface properties of the coated materials such as excellent scratch and abrasion resistance, the gloss and brilliancy of print[18].The aim of this study was to investigate the curing process of a simple varnish model system composed of urethane acrylate oligomer Craynor925and photoinitiator(Darocure1173)in rela-tion to a coating composition,curing conditions(UV light intensity, air)and coating thickness.Subsequently,the inﬂuence of these fac-tors on the gloss evolution during the curing process as well as the inﬂuence of coating on the colour stability was studied.2.Material and methods2.1.MaterialsLow viscosity modiﬁed aliphatic urethane tetraacrylate Craynor925(Sartomer,France)and radical photoinitiator,2-hydroxy-2-methyl-1-phenylpropane-1-one(Darocure1173,Ciba, Switzerland)were used in order to prepare a simple varnish model.The UV–vis spectrum of this photoinitiator has absorp-tion maxima at245nm(ε=7320dm3mol−1cm−1),280nm (ε=947dm3mol−1cm−1)and325nm(ε=85dm3mol−1cm−1).2.2.Preparation ofﬁlmsThe samples were applied immediately after preparation.Var-ious amounts of initiator(from0.5wt.%to5wt.%)were added to urethane acrylate,mechanically mixed and stored in opaque bot-tle.The viscosity of prepared coatings was2700mPa s at25◦C,the density1.1g cm−3and the surface energy about35mJ m−2.Pho-tocuring reactions were realized on aluminium and glass plates. The deﬁned sample volume(according to layer thickness)was spread on the plate by spin coating apparatus(Tesla Roˇz nov,Czech Republic).Different layer thicknesses were achieved by different spin velocity(2000–4000rpm)and different amount of applied sample,while the average layer thickness was determined by gravi-metric measurements.Consequently,some layers were covered with polyethylene foil(PE,Chemosvit,Slovak Republic,thickness 30␮m,molecular weight3×103kg mol−1,permeability for oxy-gen450cm3m−2day−1).The PE foil reduced the sample contact with atmospheric oxygen,thus,preventing the oxygen inhibition inﬂuence.PE foil had absorbed round40%of radiation in the spec-tral absorption region of the photoinitiator that was considered at the UV exposition.2.3.UV-curing of coatingsThe samples on the aluminium plates were irradiated by a medium pressure mercury lamp250W(RVC,Czech Republic)built into an UV-cure device constructed in our laboratory.The lamp (without anyﬁlters)emits standard medium pressure mercury radiation with narrow bands in UV and vis regions.However, the absorption regions of the used photoinitiator with maxima at245nm,280nm and325nm,causes that only UV radiation is photochemically active.In order to prevent the overheating during exposure the samples were placed on the water cooled Cu plate kept at25◦C.The intensity of incident light was changed with the varying distance of the light source from the sample(5cm=23mW cm−2,9cm=17mW cm−2, 12cm=12mW cm−2,15cm=7mW cm−2).The incident light intensity was measured by UVX digital radiometer(UVP,USA)with the probes for UVA and UVB region(the given values are the sum of the two measured values).Full sample area(12cm2)was exposed with the same light intensity.The curing process was evaluated by IR spectroscopy(FTIR spectrophotometer EXCALIBUR SERIES Digi-lab FTS3000NX,USA)based on the transmittance measurements. The degree of conversion in the curedﬁlm was determined accord-ing to the amount of acrylate double bond(twisting vibration at 810cm−1,stretching vibration at1610–1640cm−1)by a baseline method.The internal standard was a carbonyl peak at1725cm−1, in order to eliminate the inﬂuence of scatter in layer thickness.The degree of conversion X and relative polymerization rate R p were cal-culated from well-known equation(1)[19]which were modiﬁed according to the standard peak:X=1−A t( )A0( )·A0(1725)A t(1725)×100(1)where A0( )and A t( )is the absorbance of monomers C C bonds measured at chosen wavelength(810,1618or1635cm−1)before and after the exposure to UV light for the time t,respectively and A0(1725)and A t(1725)is the absorbance of carbonyl bonds at the same exposure time.Generally,our experiences show that the absorbance at1725cm−1did not change with irradiation.The relative polymerization rate R p was calculated from equa-tion R p=( X/ t),where X is the conversion degree of monomer’s C C bonds,at the exposure time t.The values of maximum conver-sion X max and maximum polymerization rate R p,max were obtained from the plots of X and R p vs.time in initial stage of curing.The time interval of curing steps was changed during the curing pro-cess to obtain nearly the same and noticeable change of absorbance at1635cm−1.2.4.Sample gloss estimationGloss(G)is deﬁned as the ability of a surface to reﬂect light to the specular angle.Gloss(in gloss units“GU”)can be measured by gloss-metres that are able to compare the amount of light reﬂected from the sample surface and from the gloss standard at the same geometry set-up.Glossy black glass with deﬁned refractive index is usually used as a calibration standard(GU=100).The sample surface appears to be matt if its gloss is less than6GU,if the sample gloss is in the range of6–30GU then the surface is semi-matt,if the surface reaches the gloss of30–70GU then the surface appears to be semi-glossy,and if its gloss is over70GU of the standard gloss then the surface is high-glossy.The gloss of coated lustrously foils is often pretty higher than100GU because of light reﬂection from 2or more boundaries.Gloss changes were monitored in real time during the sample curing process using a monochromatic gloss-metre constructed in our laboratory.The gloss measurements were carried out using the glass substrate samples with a matt-white surface.The sample was placed andﬁxed on a horizontal support,illuminated by red diode-laser light(650nm)at the angle of45◦,and the light reﬂected from the sample surface was detected by a silicon photodetector with the linear ampliﬁer.Illuminated area was10mm×5mm at the centre of the sample and the laser diode was25cm apart.At the434V.Janˇc oviˇc ováet al./Progress in Organic Coatings 76 (2013) 432–438same time,the sample was exposed and cured by UV light andthe change of the photodetector signal U t sample was recorded.The signal is proportional to the light reﬂected,i.e.to the gloss of the sample surface.The glossy black glass was used as the calibration standard (100GU).The gloss value at given exposure time t was calculated using equation:G t =U t sampleU standard×100(2)The ﬁnal gloss values of completely cured surfaces G ∞were obtained from plots of G t vs.time [15].2.5.Testing the effect of coating on the light fastness of ink-jet prints coloursThe samples (solid printed areas,4cm 2)were printed by ink jet printer Desk Jet 560C (Hewlett Packard,resolution 300dpi)with CMYK dye based inks on paper,then coated by bar ﬁlm applicator with a layer of urethane acrylate Craynor 925containing 3wt.%)of photoinitiator Darocure 1173.The coatings were cured (60s at 23mW cm −2).Consequently the samples were irradiated in the laboratory made box with metal halogen and ﬂuorescent lamps simulating day light exposition (colour temperature 5000K).The total light dose varied between 5and 20MJ m −2.UV–vis reﬂectance spectra were measured by spectrocolorimeter Spectrolino,GretagMacbeth AG.The total colour difference E ∗abwas calculated from Eq.(3)[20]:E ∗ab=[( L ∗)2+( a ∗)2+( b ∗)2]1/2(3)where L ∗=L ∗2−L ∗1; a ∗=a ∗2−a ∗1and b ∗=b ∗2−b ∗1.Value L *represents lightness of colour spot,chromatic coordi-nates a *and b *range from red to green and from yellow to blue colour respectively.Difference of the two colours in the CIELAB colour space is given by the length of the line connecting the points given by the L *,a *,b *coordinates of respective colours and can be calculated using equation [24],where values L 1,a 1,b 1were mea-sured immediately after samples preparation and L 2,a 2,b 2after irradiation with the above-mentioned lamp.3.Results and discussionPhotochemical curing of coatings prepared from urethane acrylate Craynor 925with various content of initiator 2-hydroxy-2-methyl-1-phenylpropane-1-one was observed by FTIR spectroscopy.The samples were coated on aluminium plates.The curing process resulted in a decrease of the intensity of C C band vibrations at 810,1618and 1635cm −1(Fig.1).The conversion was calculated according to equation for all three wavenumbers (Fig.2).The calculated values of consumption of monomer and polymer-ization rate were very similar and independent on wavenumber.In the following experiments the conversion degrees and the reac-tion rates were calculated only based on the values at 810cm −1.The spectra were normalized according to the carbonyl peak at 1725cm −1.The double bond content of the uncured formulation was deﬁned as 100%.3.1.Inﬂuence of the initiator concentrationThe photoinitiator plays a key role in the process of light induced curing.It produces free radicals that are initiating the chain reac-tion with double bond in tetrafunctional urethane acrylate.Hence it regulates the rate of initiation,the amount of light penetrating to the system and the degree of conversion.The lower production of initiating radicals at low photoinitiator concentration results in the20001750150 0125 0100 075020*********T r a n s m i t a n c e [%]Wavenumber [cm -1]Fig.1.Infrared spectra of a urethane acrylate Craynor 925with initiator Darocure 1173contents 3wt.%before (solid line)and after exposition 1min,light intensity 23mW cm −2(dot line).reduction of the polymerization rate and lower conversion.Another factor affecting the polymerization is the oxygen inhibition effect,which is due to the scavenging of the initiating and grows radi-cals by molecular oxygen [21,22].Longer UV exposure required at low photoinitiator concentration will increase the amount of atmospheric oxygen that diffuses into the sample and makes the oxygen inhibition to be more pronounced.In order to reduce the oxygen amount in the layer the samples were covered with thin polyethylene foil during curing.The samples were cured at various light intensities in the range from 7mW cm −2to 23mW cm −2.The curing at the lowest and at the highest intensity is presented in Fig.3and Table 1.The concentration of photoinitiator varied in the range of 0.5–5wt.%)according to the mass of urethane acrylate.The amount of initia-tor has signiﬁcant inﬂuence on the curing of urethane acrylate.The maximal conversion degree and maximal polymerization rate were reached at the initiator concentration of 3wt.%(X max 92%at 23mW cm −2and 86%at 7mW cm −2).These results are in a good agreement with the results of Huang and Shi [23]obtained for sim-ilar system by DSC analysis.In our experiment with the increase of the amount of photoinitiator from 3wt.%to 5wt.%,decreased the double bond conversion as well as the rate of polymerization was observed.Probably the higher concentration of 2-hydroxy-2-methyl-1-phenylpropane-1-one exhibits high absorption at its absorptions maximum at 245nm,and the initiator acts as inter-nal ﬁlter.This internal ﬁltration effect (decreased penetration of UV light)can give rise to a concentration gradient between surface and bottom layer of irradiated ﬁlm.Additionally,local high con-centration of initiator radicals can simultaneously promote radical recombination,and hence consumption of initiator in side reaction not leading to a polymerization.Table 1Effect of photoinitiator concentration and light intensity on maximal degree of con-version X max and maximal relative polymerization rate R p (layer thickness 10␮m,PE foil).Initiator concentration (wt.%)Light intensity (mW cm −2)237X max (%)R p,max (s −1)X max (%)R p,max (s −1)0.5660.06470.021790.33740.222860.42790.433920.71860.563.5890.44810.185850.37800.10V.Janˇc oviˇc ováet al./Progress in Organic Coatings 76 (2013) 432–438435180**** **** 0165 0160 0155 0150 0020406080100T r a n s m i t a n c e [%]Wavenumber [cm -1]Wavenumber [cm -1]A 0(1635) = 0.78A 60(1635)= 0.12X 1635= 84.6 %100095 090085 080 07507020406080100T r a n s m i t a n c e [%]A 0 (810] = 1.29A 60 (810) = 0.20X 810 = 84 .5%Fig.2.Double bond conversion (60s)estimation in urethane acrylate at wavenumbers 810,1618and 1635cm −1.C o n v e r s i o n [%]Irradiation time [s]C o n v e r s i o n [%]Irradiation time [s]Fig.3.Inﬂuence of irradiation time on the UV-curing of urethane acrylate Craynor 925at various Darocure 1173concentrations (layerthickness 10␮m,covered with PEfoil)at the light intensity 23mW cm −2(a)and 7mW cm −2(b).Although the conversion values achieved at total light dose 1J cm −2were very similar for both intensities,the maximal conversion achieved at higher intensity was higher compared to that at lower intensity (Fig.4).The inﬂuence of composition onC o n v e r s i o n [%]Concentration of initiator [wt %]Fig.4.The effect of initiator concentration on the conversion of double bond inurethane acrylate at different light intensity (X max is the maximal achieved double bond conversion,X 1J is the conversion after light dose 1J cm −2).maximal achieved conversion was more important for curing at light intensity of 7mW cm −2.For composition with 0.5wt.%of initiator the maximal conversion was only 47%at this intensity.The composition was uncured in fact and tacky.When the light intensity was 23mW cm −2.,the maximal conversion of 66%was obtained with the same initiator concentration and system was completely cured.Anyway,the highest conversion was observed at initiator concentration 3wt.%.The rate of polymerization,R p,max (Table 1)was also inﬂu-enced by the photoinitiator concentration.The highest value was achieved at the higher radiation intensity (23mW cm −2)and at the initiator concentration 3wt.%.3.2.Inﬂuence of the external conditionsThe radiation intensity,the thickness of the applied layer,the temperature [24]and the oxygen presence [21,22]are factors which can signiﬁcantly inﬂuence curing process and the ﬁnal quality of the cured ﬁlm.The inﬂuence of three of these factors (incident light intensity,layer thickness and oxygen presence)was observed (Figs.5and 6).The conversion degree of the double bond increased with increasing incident light intensity.Under the given experimental conditions the photopolymerization represents a complex process,with polymerization rate and conversion strongly436V.Janˇc oviˇc ováet al./Progress in Organic Coatings 76 (2013) 432–438C o n v e r s i o n [%]Irradiation time [s]C o n v e r s i o n [%]Irradiation time [s]Fig.5.The inﬂuence of irradiation time on the curing of urethane acrylate Craynor 925at various light intensities (initiator concentration 3wt.%,layer thickness 10␮m)unprotected (a)and covered with PE foil (b).dependent on light intensity.An extension of exposure does not lead to an increasing conversion and the conversion values for the formulations cured with the same UV dose but with higher incident light intensity were higher in comparison to those with lower incident light intensity in accordance with literature [25,26].The inﬂuence of light intensity was insigniﬁcant when cured samples were covered with PE foil preventing the air oxygen access into the cured layer (Fig.5).The inﬂuence of oxygen increased,when curing occurred in air without protection by PE foil.At low intensity the curing was very slow and the hardening was insufﬁ-cient obviously.The reaction of formed radicals with oxygen was faster than the initiation reaction with double bond.The effect of layer thickness on the curing of samples on the air is shown in Fig.6.The highest reaction rate was observed in the initial curing phase for the thickest layer.The reaction was proba-bly more effective in bottom layer of coating,following the effect of top layer as barrier for air oxygen.As viscosity increased dur-ing photopolymerization,theoxygen penetration throughout the coating became more difﬁcult and the photopolymerization was more effective in thinner layers (10and 15␮m).The highest max-imal conversion degree was observed for the thinnest layer;with the increasing layer thickness this value diminished.Slowdown of the reaction in the later reaction phase (exposure time longer that 10s)with the growing layer can be probably due to the decrease of UV light transmission involved higher absorption of reaction prod-ucts in surface layer of irradiated ﬁlm.Higher layer thickness willC o n v e r s i o n [%]Irradiation t ime [s]Fig.6.The inﬂuence of irradiation time on the curing of urethane acrylate Craynor925at various layer thicknesses (initiator concentration 3wt.%,light intensity 7mW cm −2,air).decrease the light penetration to the bottom of the coating and result in low and non-homogenous conversion,which may lead to inferior adhesion properties [22].The inﬂuence of air oxygen on the curing of tetrafunctional urethane acrylate in the presence of photoinitiator 2-hydroxy-2-methyl-1-phenylpropane-1-one (Fig.5)was very signiﬁcant.The samples covered with polyethylene foil were well hardened after 30s at the intensity 7mW cm −2(light dose 0.210J cm −2,conver-sion degree 75%);while the uncovered samples were insufﬁciently cured after 5min (light dose 2.1W cm −2,conversion degree 65%)and the samples were tacky.Air oxygen signiﬁcantly retarded the reaction.Even the longer exposition (3min,exposition doses 2–6J cm −2)was not enough to cure the coating at this light inten-sity.The coatings were tacky,smelling and cracked.Free radicals formed by the photolysis of the initiator are rapidly scavenged by O 2molecules to yield peroxyl radicals.They are not reactive towards the acrylate double bonds and cannot initiate or participate in any polymerization reaction.They cannot abstract also hydrogen atoms from the polymer backbone to generate hydroperoxides.Oxygen can also react with polymer grow-radicals to yield hydroperoxide and premature chain termination occurred.The elimination of air oxygen access to the cured layers increased the curing efﬁciency [21,22].3.3.Gloss changes during curingSpecular gloss is a measure of the ability of a coating surface to reﬂect a beam light in a particular angle without scattering.This is an important property of coating specially used for aesthetic and decorative purposes [27].The effect of layer thickness and curing conditions on the kinetics and gloss were investigated using the sample with constant composition and three different intensities of UV light.The layer thickness affected the ﬁnal gloss of the samples (Fig.7).It is obvious that the value of ﬁnal gloss was ﬁrstly increased with increasing the thickness of layers (at the range from 20␮m to 30␮m).In the case of layers thicker than 30␮m (40␮m)the lower value of G ∞was achieved.It was caused by the orange peel effect creation during the sample curing.Reducing either the sam-ple thickness or photopolymerization rate can eliminate the orange peel effect.Final gloss of the cured samples depended on the used UV light intensity (Fig.7).Time dependence of gloss had increas-ing character with the tendency to achieve a steady state where the gloss of the cured surface was constant.All samples showed very high-gloss and were transparent after curing.The change of gloss was more intense in the initial part of the curing process,and depended on both the above-mentioned factors.V.Janˇc oviˇc ováet al./Progress in Organic Coatings 76 (2013) 432–438437Irr adiati on ti me [s]G l o s s [G U ]G l o s s [G U ]Irradiati on time [s]Fig.7.Gloss changes during curing of urethane acrylate Craynor 925(initiator concentration 3wt.%)at the light intensity 23mW cm −2(a)and 7mW cm −2(b)and differentlayer thickness.Table 2Total colour differences E ∗abafter 5and 20h irradiation of unprotected samples and samples protected with the system urethane acrylate CN-925/initiator Darocure 1173(3wt.%),layer thickness 10,15and 20␮m for 4inks –cyan (C),magenta (M),yellow (Y)and black (B).Layer thickness of coatingIrradiation time (h)5h20hCMYBCMYB0␮m 4.1 5.7 1.00.918.222.1 5.1 1.210␮m 3.6 4.60.50.29.312.4 4.60.815␮m 3.8 5.30.60.310.013.1 4.20.420␮m3.74.60.60.310.113.13.80.43.4.The composition inﬂuence on the inks stabilityThe low stability of ink jet prints towards environmental inﬂu-ences represents an extensive problem especially for the outdoor use of prints or coatings.Inks are often very sensitive against light [28].One of the possible solutions could consist in the development of transparent layer with barrier properties against water,which will acts as protecting layer against the sunlight.UV–vis reﬂectance spectra of four inks (cyan,magenta,yellow and black)deposited on paper and corresponding CIELAB values L *,a *,b *were measured immediately after samples preparation and after irradiation withthe day light irradiation.The total colour difference E ∗abwas cal-culated according to equation from Hunt [20]mentioned in Section 2.5.The results summarized in Table 2show that the applied accel-erated ageing procedures caused signiﬁcant colour changes,asdocumented by the values of colour difference E ∗ab.The most signiﬁcant changes were observed for magenta and cyan.The coating inﬂuence was positive,the E ∗abfor coated foils was smaller compared to the uncoated foils,but no signiﬁcant differ-ence was observed between samples with various layer thicknesses (Table 2).As the layer thickness does not inﬂuence the colour sta-bility signiﬁcantly,it is possible to use the coating with the thinner layer (10␮m),allowing faster and more effective UV-curing.4.ConclusionsPhotochemical curing of coatings prepared from urethane acrylate Craynor 925with various content of initiator 2-hydroxy-2-methyl-1-phenylpropane-1-one was studied by FTIR spectroscopy.The samples were coated on aluminium plates.The conversion degrees and the reaction rates were calculated from values atwavenumber of 810cm −1,the carbonyl peak at 1725cm −1was used as an internal standard.The ﬁnal properties of UV-cured coatings depend on their com-position as well as on the experimental curing conditions.The highest conversion was achieved for initiator concentration 3wt.%.The initial slope of the curve of ﬁnal conversion vs.initiator con-centration was steepest for the lower irradiation intensities.The inﬂuence of light intensity was insigniﬁcant for curing samples covered with PE foil,which avoided the air oxygen access to the cured layer.Inﬂuence of light intensity increased when curing on air.Moreover,the layer thickness inﬂuenced the conversion degree.The highest conversion degree was calculated for the thinnest layer (10␮m).Final gloss of the cured samples depended on the UV light inten-sity used;the samples cured at higher light intensity reached the higher gloss values.It is obvious that the maximal value of ﬁnal gloss was obtained for layers with thickness of 30␮m.The inﬂuence of prepared coating on the colour ink stability waspositive;coated foils exhibited lower total colour difference E ∗abcompared to uncoated foils.However,the total colour differenceE ∗abdoes not depend on layer thickness of protective coating.AcknowledgementsThe authors thank the Slovak Grant Agencies APVV (Project No.0324-10)and VEGA (Project No.1/0811/11)for their ﬁnancial sup-port.Appendix A.Supplementary dataSupplementary data associated with this article can be found,in the online version,at /10.1016/j.porgcoat.2012.10.010.References[1]J.P.Fouassier,Photoinitiation,Photopolymerization and Photocuring,CarlHanser Verlag,München,1995.[2]J.Kindernay,A.Blaˇz ková,J.Rudá,V.Janˇc oviˇc ová,Z.Jakubíková,J.Photochem.Photobiol.A:Chem.151(2002)229–236.[3]J.F.Rabek,Mechanisms of Photophysical and Photochemical Reactions in Poly-mers,Theory and Practical Applications,Wiley,New York,1987.[4]H.Hwang,C.Park,J.Moon,H.Kim,T.Masubuchi,.Coat.72(2011)663–675.[5]X.Yu, B.P.Grady,R.S.Reiner,S.L.Cooper,J.Appl.Polym.Sci.49(1993)1943–1955.[6]R.Schwalm,UV,Coatings,Basics,Recent Developments and New Applications,ﬁrst ed.,Elsevier,Amsterdam,2007.[7]Y.Zhang,F.Zhan,W.Shi,.Coat.71(2011)399–405.。

光谱层英文版

光谱层英文版The Spectral Layer: Unveiling the Invisible RealmThe universe we inhabit is a tapestry of intricately woven elements, each thread contributing to the grand tapestry of existence. Amidst this intricate web, lies a realm that is often overlooked, yet holds the key to unlocking the mysteries of our reality. This realm is the spectral layer – a realm that transcends the boundaries of our visible world and delves into the unseen realms of energy and vibration.At the heart of the spectral layer lies the electromagnetic spectrum –a vast and diverse range of wavelengths and frequencies that encompass the entirety of our physical world. From the low-frequency radio waves to the high-energy gamma rays, the electromagnetic spectrum is the foundation upon which our understanding of the universe is built. It is within this spectrum that we find the familiar visible light, the spectrum of colors that we perceive with our eyes, but it is only a small fraction of the vast and diverse tapestry that makes up the spectral layer.Beyond the visible spectrum, there lies a realm of unseen energies that are integral to the very fabric of our existence. Infrared radiation, for instance, is a form of electromagnetic radiation that is invisible to the human eye but plays a crucial role in the transfer of heat and the functioning of various biological processes. Similarly, ultraviolet radiation, though invisible to us, is essential for the production of vitamin D and the regulation of circadian rhythms.But the spectral layer extends far beyond the confines of the electromagnetic spectrum. It is a realm that encompasses the vibrations and frequencies of all matter and energy, from the subatomic particles that make up the building blocks of our universe to the vast cosmic structures that span the vastness of space. These vibrations and frequencies, though often imperceptible to our senses, are the foundation upon which the entire universe is built.At the quantum level, the spectral layer reveals the true nature of reality. Subatomic particles, such as electrons and quarks, are not merely static entities but rather dynamic oscillations of energy, each with its own unique frequency and vibration. These vibrations, in turn, give rise to the fundamental forces that govern the behavior of matter and energy, from the strong nuclear force that holds the nucleus of an atom together to the mysterious dark energy that drives the expansion of the universe.But the spectral layer is not merely a realm of the infinitely small. It also encompasses the vast and expansive structures of the cosmos, from the intricate patterns of galaxies to the pulsing rhythms of celestial bodies. The stars that dot the night sky, for instance, are not merely points of light but rather vast nuclear furnaces, each emitting a unique spectrum of electromagnetic radiation that can be detected and analyzed by scientists.Through the study of the spectral layer, we have gained unprecedented insights into the nature of our universe. By analyzing the spectra of distant galaxies, for example, we can determine their chemical composition, their age, and even their rate of expansion –information that is crucial for our understanding of the origins and evolution of the cosmos.But the spectral layer is not just a realm of scientific inquiry – it is also a realm of profound spiritual and metaphysical exploration. Many ancient and indigenous cultures have long recognized the importance of the unseen realms of energy and vibration, and have developed sophisticated systems of understanding and interacting with these realms.In the traditions of Hinduism and Buddhism, for instance, the concept of the chakras – the seven energy centers that are believed to govern various aspects of our physical, emotional, and spiritualwell-being – is a manifestation of the spectral layer. These energy centers are believed to be connected to specific frequencies and vibrations, and the practice of chakra meditation and balancing is seen as a way to align oneself with the natural rhythms of the universe.Similarly, in the traditions of shamanism and indigenous healing practices, the concept of the "spirit world" or the "unseen realm" is closely tied to the spectral layer. Shamans and healers are often said to be able to perceive and interact with the unseen energies that permeate our world, using techniques such as drumming, chanting, and plant medicine to access these realms and bring about healing and transformation.In the modern era, the spectral layer has become the subject of intense scientific and technological exploration. From the development of advanced imaging technologies that can reveal the unseen structures of the human body to the creation of sophisticated communication systems that harness the power of the electromagnetic spectrum, the spectral layer has become an essential component of our understanding and manipulation of the physical world.Yet, despite the immense progress we have made in our understanding of the spectral layer, there is still much that remainsunknown and mysterious. The nature of dark matter and dark energy, for instance, remains one of the greatest unsolved puzzles in modern physics, and the true nature of consciousness and the relationship between the physical and the metaphysical realms continues to be a subject of intense debate and exploration.As we continue to delve deeper into the spectral layer, we may uncover even more profound insights into the nature of our reality. Perhaps we will discover new forms of energy and vibration that have yet to be detected, or perhaps we will find that the boundaries between the seen and the unseen are far more permeable than we ever imagined. Whatever the future may hold, one thing is certain: the spectral layer will continue to be a source of fascination, inspiration, and mystery for generations to come.。

光伏发电英文文献Ultra-High Efficiency Photovoltaic

Ultra-High Efﬁciency Photovoltaic Cells for Large Scale Solar Power GenerationYoshiaki NakanoAbstract The primary targets of our project are to dras-tically improve the photovoltaic conversion efﬁciency and to develop new energy storage and delivery technologies. Our approach to obtain an efﬁciency over40%starts from the improvement of III–V multi-junction solar cells by introducing a novel material for each cell realizing an ideal combination of bandgaps and lattice-matching.Further improvement incorporates quantum structures such as stacked quantum wells and quantum dots,which allow higher degree of freedom in the design of the bandgap and the lattice strain.Highly controlled arrangement of either quantum dots or quantum wells permits the coupling of the wavefunctions,and thus forms intermediate bands in the bandgap of a host material,which allows multiple photon absorption theoretically leading to a conversion efﬁciency exceeding50%.In addition to such improvements, microfabrication technology for the integrated high-efﬁ-ciency cells and the development of novel material systems that realizes high efﬁciency and low cost at the same time are investigated.Keywords Multi-junctionÁQuantum wellÁConcentratorÁPhotovoltaicINTRODUCTIONLarge-scale photovoltaic(PV)power generation systems, that achieve an ultra-high efﬁciency of40%or higher under high concentration,are in the spotlight as a new technology to ease drastically the energy problems.Mul-tiple junction(or tandem)solar cells that use epitaxial crystals of III–V compound semiconductors take on the active role for photoelectric energy conversion in such PV power generation systems.Because these solar cells operate under a sunlight concentration of5009to10009, the cost of cells that use the epitaxial crystal does not pose much of a problem.In concentrator PV,the increased cost for a cell is compensated by less costly focusing optics. The photons shining down on earth from the sun have a wide range of energy distribution,from the visible region to the infrared region,as shown in Fig.1.Multi-junction solar cells,which are laminated with multilayers of p–n junctions conﬁgured by using materials with different band gaps,show promise in absorbing as much of these photons as possible,and converting the photon energy into elec-tricity with minimum loss to obtain high voltage.Among the various types of multi-junction solar cells,indium gallium phosphide(InGaP)/gallium arsenide(GaAs)/ger-manium(Ge)triple-junction cells that make full use of the relationship between band gaps and diverse lattice con-stants offered by compound semiconductors have the advantage of high conversion efﬁciency because of their high-quality single crystal with a uniform-size crystal lat-tice.So far,a conversion efﬁciency exceeding41%under conditions where sunlight is concentrated to an intensity of approximately5009has been reported.The tunnel junction with a function equivalent to elec-trodes is inserted between different materials.The positive holes accumulated in the p layer and the electrons in the adjacent n layer will be recombined and eliminated in the tunnel junction.Therefore,three p–n junctions consisting of InGaP,GaAs,and Ge will become connected in series. The upper limit of the electric current is set by the mini-mum value of photonﬂux absorbed by a single cell.On the other hand,the sum of voltages of three cells make up the voltage.As shown in Fig.1,photons that can be captured in the GaAs middle cell have a smallﬂux because of the band gap of each material.As a result,the electric currentoutputAMBIO2012,41(Supplement2):125–131 DOI10.1007/s13280-012-0267-4from the GaAs cell theoretically becomes smaller than that of the others and determines the electric current output of the entire tandem cell.To develop a higher efﬁciency tandem cell,it is necessary to use a material with a band gap narrower than that of GaAs for the middle cell.In order to obtain maximum conversion efﬁciency for triple-junction solar cells,it is essential to narrow down the middle cell band gap to 1.2eV and increase the short-circuit current density by 2mA/cm 2compared with that of the GaAs middle cell.When the material is replaced with a narrower band gap,the output voltage will drop.However,the effect of improving the electric current balance out-performs this drop in output voltage and boosts the efﬁ-ciency of the entire multi-junction cell.When a crystal with such a narrow band gap is grown on a Ge base material,lattice relaxation will occur in the middle of epitaxial crystal growth because the lattice constants of narrower band-gap materials are larger than that of Ge (as shown in Fig.2).As a result,the carrier transport properties will degrade due to dislocation.Researchers from the international research center Solar Quest,the University of Tokyo,aim to move beyond such material-related restrictions,and obtain materials and structures that have effective narrow band gaps while maintaining lattice matching with Ge or GaAs.To achieve this goal,we have taken three approaches as indicated in Fig.3.These approaches are explained in detail below.DILUTE NITROGEN-ADDED BULK CRYSTAL Indium gallium nitride arsenide (InGaNAs)is a bulk material consists of InGaAs,which contains several percent of nitrogen.InGaNAs has a high potential for achieving a narrow band gap while maintaining lattice matching with Ge or GaAs.However,InGaNAs has a fatal problem,that is,a drop in carrier mobility due to inhomogeneousdistribution of nitrogen (N).To achieve homogeneous solid solution of N in crystal,we have applied atomic hydrogen irradiation in the ﬁlm formation process and addition of a very small amount of antimony (Sb)(Fig.3).The atomic hydrogen irradiation technology and the nitrogen radical irradiation technology for incorporating N efﬁciently into the crystal can be achieved only through molecular beam epitaxy (MBE),which is used to fabricate ﬁlms under high vacuum conditions.(Nitrogen radical irradiation is a technology that irradiates the surface of a growing crystal with nitrogen atoms that are resolved by passing nitrogen through a plasma device attached to the MBE system.)Therefore,high-quality InGaNAs has been obtained only by MBE until now.Furthermore,as a small amount of Sb is also incorporated in a crystal,it is nec-essary to control the composition of ﬁve elements in the crystal with a high degree of accuracy to achieve lattice matching with Ge or GaAs.We have overcome this difﬁculty by optimizing the crystal growth conditions with high precision and devel-oped a cell that has an InGaNAs absorption layer formed on a GaAs substrate.The short-circuit current has increased by 9.6mA/cm 2for this cell,compared with a GaAs single-junction cell,by narrowing the band gap down to 1.0eV.This technology can be implemented not only for triple-junction cells,but also for higher efﬁciency lattice-matched quadruple-junction cells on a Ge substrate.In order to avoid the difﬁculty of adjusting the compo-sition of ﬁve elements in a crystal,we are also taking an approach of using GaNAs with a lattice smaller than that of Ge or GaAs for the absorption layer and inserting InAs with a large lattice in dot form to compensate for the crystal’s tensile strain.To make a solid solution of N uniformly in GaNAs,we use the MBE method for crystal growth and the atomic hydrogen irradiation as in the case of InGaNAs.We also believe that using 3D-shaped InAs dots can effectively compensate for the tensile strainthatFig.1Solar spectrum radiated on earth and photon ﬂux collected by the top cell (InGaP),middle cell (GaAs),and bottom cell (Ge)(equivalent to the area of the ﬁlled portions in the ﬁgure)occurs in GaNAs.We have measured the characteristics of a single-junction cell formed on a GaAs substrate by using a GaNAs absorption layer with InAs dots inserted.Figure 4shows that we were able to succeed in enhancing the external quantum efﬁciency in the long-wavelength region (corresponding to the GaNAs absorp-tion)to a level equal to GaAs.This was done by extending the absorption edge to a longer wavelength of 1200nm,and increasing the thickness of the GaNAs layer by increasing the number of laminated InAs quantum dot layers.This high quantum efﬁciency clearly indicates that GaNAs with InAs dots inserted has the satisfactory quality for middle cell material (Oshima et al.2010).STRAIN-COMPENSATED QUANTUM WELL STRUCTUREIt is extremely difﬁcult to develop a narrow band-gap material that can maintain lattice matching with Ge orGaAs unless dilute nitrogen-based materials mentioned earlier are used.As shown in Fig.2,the conventionally used material InGaAs has a narrower band gap and a larger lattice constant than GaAs.Therefore,it is difﬁcult to grow InGaAs with a thickness larger than the critical ﬁlm thickness on GaAs without causing lattice relaxation.However,the total ﬁlm thickness of InGaAs can be increased as an InGaAs/GaAsP strain-compensated multi-layer structure by laminating InGaAs with a thickness less than the critical ﬁlm thickness in combination with GaAsP that is based on GaAs as well,but has a small lattice constant,and bringing the average strain close to zero (Fig.3.).This InGaAs/GaAsP strain-compensated multilayer structure will form a quantum well-type potential as shown in Fig.5.The narrow band-gap InGaAs layer absorbs the long-wavelength photons to generate electron–hole pairs.When these electron–hole pairs go over the potential bar-rier of the GaAsP layer due to thermal excitation,the electrons and holes are separated by a built-in electricﬁeldFig.2Relationship between band gaps and lattice constants of III–V-based and IV-based crystalsto generate photocurrent.There is a high probability of recombination of electron–hole pairs that remain in the well.To avoid this recombination,it is necessary to take out the electron–hole pairs efﬁciently from the well and transfer them to n-type and p-type regions without allowing them to be recaptured into the well.Designing thequantumFig.3Materials and structures of narrow band-gap middle cells being researched by thisteamFig.4Spectral quantum efﬁciency of GaAs single-junction cell using GaNAs bulk crystal layer (inserted with InAs dots)as the absorption layer:Since the InAs dot layer and the GaNAs bulk layer are stacked alternately,the total thickness of GaNAs layers increases as the number of stacked InAs dot layers is increased.The solid line in the graph indicates the data of a reference cell that uses GaAs for its absorption layer (Oshima et al.2010)well structure suited for this purpose is essential for improving conversion efﬁciency.The high-quality crystal growth by means of the metal-organic vapor phase epitaxy (MOVPE)method with excellent ability for mass production has already been applied for InGaAs and GaAsP layers in semiconductor optical device applications.Therefore,it is technologically quite possible to incorporate the InGaAs/GaAsP quantum well structure into multi-junction solar cells that are man-ufactured at present,only if highly accurate strain com-pensation can be achieved.As the most basic approach related to quantum well structure design,we are working on fabrication of super-lattice cells with the aim of achieving higher efﬁciency by making the GaAsP barrier layer as thin as possible,and enabling carriers to move among wells by means of the tunnel effect.Figure 6shows the spectral quantum efﬁ-ciency of a superlattice cell.In this example,the thickness of the GaAsP barrier layer is 5nm,which is not thin enough for proper demonstration of the tunnel effect.When the quantum efﬁciency in the wavelength range (860–960nm)that corresponds to absorption of the quan-tum well is compared between a cell,which has a con-ventionally used barrier layer and a thickness of 10nm or more,and a superlattice cell,which has the same total layer thickness of InGaAs,the superlattice cell demonstrates double or higher quantum efﬁciency.This result indicates that carrier mobility across quantum wells is promoted by even the partial use of the tunnel effect.By increasing the P composition in the GaAsP layer,the thickness of well (or the In composition)can be increased,and the barrier layer thickness can be reduced while strain compensation is maintained.A cell with higher quantum efﬁciency can befabricated while extending the absorption edge to the long-wavelength side (Wang et al.2010,2012).GROWTH TECHNIQUE FOR STRAIN-COMPENSATED QUANTUM WELLTo reduce the strain accumulated in the InGaAs/GaAsP multilayer structure as close to zero as possible,it is nec-essary to control the thickness and atomic content of each layer with high accuracy.The In composition and thickness of the InGaAs layer has a direct effect on the absorption edge wavelength and the GaAsP layer must be thinned to a satisfactory extent to demonstrate fully the tunnel effect of the barrier layer.Therefore,it is desirable that the average strain of the entire structure is adjusted mainly by the P composition of the GaAsP layer.Meanwhile,for MOVPE,there exists a nonlinear rela-tionship between the P composition of the crystal layer and the P ratio [P/(P ?As)]in the vapor phase precursors,which arises from different absorption and desorption phenomena on the surface.As a result,it is not easy to control the P composition of the crystal layer.To break through such a difﬁculty and promote efﬁcient optimiza-tion of crystal growth conditions,we have applied a mechanism to evaluate the strain of the crystal layer during growth in real time by sequentially measuring the curvature of wafers during growth with an incident laser beam from the observation window of the reactor.As shown in Fig.7,the wafer curvature during the growth of an InGaAs/GaAsP multilayer structure indicates a periodic behavior.Based on a simple mechanical model,it has become clear that the time changes ofwaferFig.5Distribution of potential formed by the InGaAs/GaAsP strain-compensated multilayer structure:the narrow band-gap InGaAs layer is sandwiched between wide band-gap GaAsP layers and,as a result,it as quantum well-type potential distribution.In the well,electron–hole pairs are formed by absorption of long-wavelength photons and at the same time,recombination of electrons and holes takes place.The team from Solar Quest is focusing on developing a superlattice structure with the thinnest GaAsP barrier layercurvature are proportionate to the strain of the crystal layer relative to a substrate during the growing process.One vibration cycle of the curvature is same as the growth time of an InGaAs and GaAsP pair (Sugiyama et al.2011).Therefore,the observed vibration of the wafer curvature reﬂects the accumulation of the compression strain that occurs during InGaAs growth and the release of the strain that occurs during GaAsP growth.When the strain is completely compensated,the growth of the InGaAs/GaAsP pair will cause this strain to return to the initial value and the wafer curvature will vibrate with the horizontal line as the center.As shown in Fig.7,strain can be compensated almost completely by adjusting the layer structure.Only by conducting a limited number of test runs,the use of such real-time observation technology of the growth layer enables setting the growth conditions for fabricating the layer structure for which strain has been compensated with highaccuracy.Fig.6Spectral quantum efﬁciency of GaAs single-junction cell using InGaAs/GaAsP superlattice as theabsorption layer:This structure consists of 60layers of InGaAs quantum wells.The graph also shows data of a reference cell that uses GaAs for its absorption layer (Wang et al.2010,2012)Fig.7Changes in wafer curvature over time during growth of the InGaAs/GaAsP multilayer structure.This graph indicates the measurement result and the simulation result of the curvature based on the layer structure(composition ?thickness)obtained by X-ray diffraction.Since compressive strain is applied during InGaAs growth,the curvature decreases as time passes.On the other hand,since tensile strain is applied during GaAsP growth,the curvature changes in the oppositedirection (Sugiyama et al.2011)FUTURE DIRECTIONSIn order to improve the conversion efﬁciency by enhancing the current matching of multi-junction solar cells using III–V compound semiconductors,there is an urgent need to create semiconductor materials or structures that can maintain lattice matching with Ge or GaAs,and have a band gap of1.2eV.As for InGaNAs,which consists of InGaAs with several percent of nitrogen added,we have the prospect of extending the band edge to1.0eV while retaining sufﬁcient carrier mobility for solar cells by means of atomic hydrogen irradiation and application of a small quantity of Sb during the growth process.In addition,as for GaNAs bulk crystal containing InAs dots,we were able to extend the band edge to1.2eV and produce a high-quality crystal with enoughﬁlm thickness to achieve the quantum efﬁciency equivalent to that of GaAs.These crystals are grown by means of MBE. Therefore,measures that can be used to apply these crys-tals for mass production,such as migration to MOVPE, will be investigated after demonstrating their high efﬁ-ciency by embedding these crystals into multi-junction cells.As for the InGaAs/GaAsP strain-compensated quantum well that can be grown using MOVPE,we are working on the development of a thinner barrier layer while compen-sating for the strain with high accuracy by real-time observation of the wafer curvature.We have had the prospect of achieving a quantum efﬁciency that will sur-pass existing quantum well solar cells by promoting the carrier transfer within the multilayer quantum well struc-ture using the tunnel effect.As this technology can be transferred quite easily to the existing multi-junction solar cell fabrication process,we strongly believe that this technology can signiﬁcantly contribute to the efﬁciency improvement of the latest multi-junction solar cells. REFERENCESOshima,R.,A.Takata,Y.Shoji,K.Akahane,and Y.Okada.2010.InAs/GaNAs strain-compensated quantum dots stacked up to50 layers for use in high-efﬁciency solar cell.Physica E42: 2757–2760.Sugiyama,M.,K.Sugita,Y.Wang,and Y.Nakano.2011.In situ curvature monitoring for metalorganic vapor phase epitaxy of strain-balanced stacks of InGaAs/GaAsP multiple quantum wells.Journal of Crystal Growth315:1–4.Wang,Y.,Y.Wen,K.Watanabe,M.Sugiyama,and Y.Nakano.2010.InGaAs/GaAsP strain-compensated superlattice solar cell for enhanced spectral response.In Proceedings35th IEEE photovoltaic specialists conference,3383–3385.Wang,Y.P.,S.Ma,M.Sugiyama,and Y.Nakano.2012.Management of highly-strained heterointerface in InGaAs/GaAsP strain-balanced superlattice for photovoltaic application.Journal of Crystal Growth.doi:10.1016/j.jcrysgro.2011.12.049. AUTHOR BIOGRAPHYYoshiaki Nakano(&)is Professor and Director General of Research Center for Advanced Science and Technology,the University of Tokyo.His research interests include physics and fabrication tech-nologies of semiconductor distributed feedback lasers,semiconductor optical modulators/switches,monolithically integrated photonic cir-cuits,and high-efﬁciency heterostructure solar cells.Address:Research Center for Advanced Science and Technology, The University of Tokyo,4-6-1Komaba,Meguro-ku,Tokyo153-8904,Japan.e-mail:nakano@rcast.u-tokyo.ac.jp。

Transistor with deep submicron channel

专利名称：Transistor with deep submicron channel 发明人：Huang, Daniel L.,Hsu, Louis Lu-Chen,Wang, Wen-Yuan申请号：EP93480143.2申请日：19930921公开号：EP0600814B1公开日：19960424专利内容由知识产权出版社提供摘要：A method of fabricating field effect transistors (FETs) that employs only optical lithography involves the formation of a relatively wide aperture using optical techniques is disclosed hereunder. The formation of composite sidewalls having differential etch resistance in the aperture to define a final aperture width less than that available with conventional optical techniques. A conventional P⁻is performed substrate (10) with ROI regions (15) defining an active N⁻ region (110) coated with a thin SiO2/Si3N4 insulating layer (20) is first provided. Then, a polish-stop layer of CVD boronitride (40) having a thickness equal to the desired thickness of the transistor gate is deposited. Next, an aperture (210) is formed therein by conventional optical lithrography and RIE using a CF ₄/O₂plasma. Two sidewall layers, a first layer of CVD oxide (50) and a second layer of CVD nitride (60) are now deposited onto the structure. A first selective etching step using an anisotropic dry etch of CHF ₃/C1₂removes the CVD nitride layer (60) from all the horizontal surfaces of the structure. A second selective etching step using a CF4/O₂plasma removes the CVD oxide layer (50) at the bottom of the aperture. A first boron implantation establishes the threshold level and another boron implantation prevents punch-through between the source and drain. They finally result in theformation of the channel (220). The thin insulating layer is stripped and a gate oxide (25) is grown within aperture (210).申请人：IBM地址：US国籍：US代理机构：Klein, Daniel Jacques Henri更多信息请下载全文后查看。

妇产科全英文名词解释和简答(含中文注释)全

妇产科全英文名词解释和简答（含中文注释）鸣谢美丽的美丽的和美丽的：O7和阿默名词解释妊娠生理Braxton hicks 收缩the pregnant uterus produces painless palpable contractions at irregular intervals from an early stage in gestation, these braxton hicks contractions, however, are not positive sighs of pregnancy, since similar contractions are sometimes noted in cases of hematometra（宫腔积血）and occasionally with soft myomas, especially the pedunculated submucous variety妊娠诊断Fetal lie胎产式the term lie refers to the relationship between the long axis(长轴) of the mother and the long axis of the fetus（胎儿）Fetal presentation胎先露the presenting part is the portion of the fetus that descend first through the birth canal（产道）Fetal position胎方位the exact fetal position is determined by the relationship of some definite part of the fetus （the guiding point）to a fixed area of the maternal pelvis（母体骨盆）Fetal attitude 胎势attitude refers to the relationship of the parts of the fetus to each otherHegar’s sign 黑格氏征on bimanual examination（双合诊）the isthmus uteri（子宫峡部）feels exceedingly doughy（柔软的）at about 6-8 week after the last period异常妊娠Abortion 流产abortion is the termination of a pregnancy before the end of the 28week when the fetus weight lesser than 1000gThreatened labor 先兆流产Before 28 weeks of gestation showed a small amount of vaginal bleeding, followed by paroxysmal（阵发性）abdominal pain, without rupture of fetal membranes （胎膜）and dilation of cervix, the size of the uterus is consistent with pregnant weeksMissed abortion 稽留流产when the embryon（胚胎）dies and it is retained in uterusHabitual abortion 习惯性流产/recurrent abortion（复发性流产）this is defined as 3 or more consecutive abortion with the same sexual partnerEctopic pregnancy 异位妊娠implantation of the fertilized ovum（受精卵）in a site outside the uterine cavity妊娠合并内科疾病HELLP syndrome HELLP 综合征hemolysis(溶血), elevated liver enzymes（肝酶）, and low platelets（血小板）syndrome胎盘与胎膜异常Placenta previa 前置胎盘the entire placenta or part of it is implanted in the lower portion of the uterus rather than in the upper active segment, and located lower than the presenting part of the fetus after 28 weekPlacenta abruption 胎盘早剥partial or complete detachment of the placenta from a site of normal implantation in the uterine wall before delivery of the fetus and may occur at any time after 20 week’s gestationUteroplacental apoplexy(couvelaire uterus) 子宫胎盘卒中hemorrhage infiltrates（浸润）the uterine wall. Making it appears purlish ecchymosis,（青紫瘀斑）muscle bundles disrupted and degenerated, then uterus loss its contractile power,（收缩力）resulting in postpartum hemorrhege产前检查与孕期保健OCT or CST (orytocin chellenge test, or contraction stress test) 缩宫素激惹试验measuring the FHR response to the stress of spontaneous or oxytocin（催产素）induced contraction (UC) forms to basis of this test of fetal placental reserve OCTpositive: recurrent (at least two) late deceleration of the FHR, i.e, slowing in the heart rate develops at about the middle of the contraction and returning to the baseline after the contraction subsides, in addition, the amplitude（振幅）and the duration of the deceleration must parallel the amplitude and duration of the underlying Negative: at least 3 contractions in 10 minutes, and each lasting at least 40 seconds, the FHR are observed without late deceleration, a negative test within a weak of delivery provided reliable assurance that the fetus will survive and probably tolerate labor and delivery wellNST (nor-stress test)无应激试验NST is a test for observing and recording reserve of fetus without any external stimulation and uterine contraction(子宫收缩）Divided into reactive NST,dubious NST,non-reactive NSTReactive:the Fad must have a smooth, regular configuration and there must be 3 or more FADs per 20 minutes with a duration of greater than 15 seconds and more than15bpm amplitudeNon-reactive: this classification includes no fetal activity either spontaneously oneously or with stimulation, and no demonsthable FHR change in response to stimulation正常分娩Mechanism of normal labor 分娩机制the mechanism of labor is a term applied to the series of changes in the attitude and position of the fetus that permits it to progress through the irregular shaped pelvic cavityEngagement 衔接the mechanism by which the biparietal diameter（双顶径）, the greatest transverse diamete of the head in vertex presentation（顶先露）,passes through the pelvic inlet is designated engagement, a phenomenon that usually occurs in primigravidas with normal pelves （骨盆）during the last few weeks of pregnancy but does not ordinarily take place in multiparas until after the commencement of laborInternal rotation 内旋转this movement is a turning of the head in such a manner that the occiput（枕骨）moves anteriorly around the The longitudinal axis of the pelvis（骨盆纵轴）making the interparietal suture（矢状缝）consistent with the anteroposterior diameter of the pelvis and pelvis outlet（骨盆以及骨盆出口的前后径）Onset and diagnosis of labor 临产诊断the contractions of labor occur regularly and usually increase until they recur every 5 to 6 minutes and last from 30 to 40 seconds, which cause progressive effacement （消失）and dilatation of the cervix, and descent of the presenting part（胎先露部）Physiologic retraction ring 生理性缩复环as a result of the thining of the loweruterine segment and the thicking of the upper. The boundary between them is marked by a ridge（隆起）on the inner uterine surface, the ridge is called the physiologic retraction ringSigns of separation of placenta 胎盘剥离征象1.the rising up of the uterus as a small firmly contracted mass，to a level above the umbilicus（脐）2. Lengthening of the cord（脐带）3. A small amount of vaginal bleeding 4.traction upwards of the fundus（宫底）fails to draw the cord up with itRetained placenta 胎盘滞留the placenta which retained in the uterine cavity for more than 30 minutes is called retained placenta异常分娩Prolonged latent phase 潜伏期延长the time started from regular uterine effacement（子宫收缩）to enter the active phase is longer than 16 hours. Prolonged active phase 活跃期延长after the cervix（宫颈）dilated（扩张）to 3cm,labor progresses over slow, the time of active phase lastes over 8 hours. The cervical dilatation progresses at a rate less than 1.2cm/hr in primigravida（初产妇）and less than 1.5cm/hr in multipara（经产妇）Arrested active phase 活跃期停滞the cervical dilatation does not change over 4 hours during the active phaseProtracted second stage 第二产程延长when the cervix fully dilates the contractions become weak and the intervals prolong, the span of time is over 2 hours in nullipara（初产妇）and over 1 hour in multipara（经产妇）, it is called that the second stage is prolongedNeglected transverse lie 忽略性横位in labor, the shoulder is forced into the pelvic but cannot descend, the hand and arm fall into the vagina, while, the head and buttocks（臀部）is obstructed above the inlet. （骨盆入口）the upper uterine segment becomes progressively thicker while the lower segment be thinner, a pathological retraction ring （病理性缩复环）can appear, the uterus may ruptureProlonged labor 滞产when the course of labor lasts for more than 24 hours it is called prolonged laborPathologic retraction ring 病理性缩复环a pathologic retraction ring (bundle ring) develops during obstructed but otherwise normal labor. The ring forms at the junction of the active upper and the relatively passive lower uterine segments and actually is the lower border of the unusually thick upper segment, because descent and expulsion（排出）of the fetus are impelled. The lower segment becomes excessively lengthened and thinned and the upper segment shortened and thickened. Unless the obstruction is overcome, the uterus may rupture（子宫破裂）. The ring can be felt and sometimes even seen as a ridge just below the umbilicus（脐）, it becomes more obvious as labor presses Constriction ring 痉挛性缩复环a constriction ring is tetanic（强直）annular（环）contraction of smooth muscle that may occur at any level in the uterine wall. The ring does not change position, and it may be applied so tightly around the fetus body that it prevents descent分娩期并发症Postpartum hemorrhage 产后出血the total blood loss with delivery and during the first 24 hours after birth is estimated to exceed 500ml正常产褥The puerperium 产褥期is the period generally 6 weeks that starts immediately after delivery and is completed when the reproductive tract has returned to the normal nonpregnant condition产褥期并发症Late puerperal hemorrhage 晚期产后出血hemorrhage may occur at any time during the first 24 hours after delivery (early delayed hemorrhage) or several days later (late delayed hemorrhage)Puerperal infection 产褥感染puerperal infection is any postpartum infection of the genital tract（生殖道）arousing partial or general infection morbidity 产褥病率puerperal morbidity is an oral temperature over 38℃2 times on any of the first 10 postpartum（产后的）days, excluding the first 24 hours子宫内膜异位症与子宫腺肌病Endometriosis 子宫内膜异位症it is the presence of functional endometrial(子宫内膜) tissue outside the uterine cavityAdenomyosis 子宫腺肌病adenomyosis means islands of endometrial tissue located deep in the myometriumAdenomyoma 子宫腺肌瘤if the endometrial（子宫内膜）implants in the myometrium（子宫肌层）and is localized as a circumscribled （局部的）mass, it is called adenomyoma on section you can see a whorled （漩涡的）grayish white mass very similar to that of a fibroid （子宫肌瘤）, but no capsule is present子宫颈肿瘤intraepithelial carcinoma or carcinoma in situ CIS 宫颈原位癌CIS of the cervix is terms used to describe the completely haphazard（杂乱无章）replacement of the stratified（分层的）epithelium上皮by abnormal cells showing the characteristic loss of polarity and nuclear atypism（非典型）and changes in nuclear cytoplasmic（细胞浆的）ratio of neoplastic（新生的）cells. The abnormal cells do not penetrate the basement membrance. The process limited to the epitheliumCarcinoma in situ with glandular involvement 原位癌累及腺体in intraepithelial carcinoma(上皮内癌症), these tumor frequently extend up into the cervical canal and replace the columnar cells（柱状上皮细胞）lining the cervical glands, put the basement membrane of the glands remains intact（完整的）and uninvadedEarly invasive carcinoma or microinvasive carcinoma 宫颈早期浸润癌或镜下浸润癌microinvasive（微创）carcinoma of the cervix is established only by histologic（组织学）study, since there is no grossly（肉眼的）visible or obvious malignant tumor in the cervix. In some cases the lesion（损伤）is largely carcinoma in situ（原位）, butpenetration（浸润）of the basement membrane by a small cluster of cells or spray of cells for a depth of less than 5mm below the basement membrane may occur. There is no evidence of lymphatic or blood vessel invasion and confluence（融合）of the spray-like arrangement（排列）of cancer cellsInvasive carcinoma of cervix 宫颈浸润癌it is defined as penetration of the basement membrane by carcinoma cells with or without blood vessels or lymphatic invasion. The depth of penetration is usually greater than 5mm below the basement membraneCervical intraepithelial neoplasia CIN 子宫颈上皮内瘤变a general term for thegrowth of abnormal cells on the surface of cervix. And was classified from 1~3 to described how much of the cervix contains abnormal cells子宫肿瘤Intramural myoma or interstitial myoma 肌壁间肌瘤the myoma lies within the uterine wall and surrounded by myometrium（子宫肌层）. It comprises（包括）approximately 70% of all uterine myomaSubserous myoma or subperitoneal myoma 浆膜下肌瘤the myoma just covered by the serosal（浆膜的）surface of the uterus and bulges （隆起）outward from the myometrium（子宫肌层）Intraligamentous myoma 阔韧带肌瘤the tumor that grow laterally between the leaves of the broad ligament are called intraligamentous myomaSubmucous myoma 粘膜下肌瘤the myoma lies beneath the endometrium（子宫内膜）and sticking out into the uterine cavityRed degeneration 肌瘤红色变性this type of degeneration occurs during pregnancy. Thrombosis（血栓形成）venous（静脉的）congestion（淤血）and the interstitial（间质的）hemorrhage（出血）are responsible for the color of a myoma undergoing red degeneration. The process is usually accompanied by extreme pain卵巢肿瘤Myxoma peritonei 腹膜粘液瘤in mucinous cystadenoma（粘液性囊腺瘤）a rare complication which sometimes develops if rupture of the cyst, the epithelium cells may seed onto the peritoneum（腹膜）and produce a pseudomyxoma peritonei（腹膜假粘液瘤）. The shape resembles the metastasis of ovarian carcinomaDermoid cyst 皮样囊肿the mature teratoma（畸胎瘤）which belongs to benign （良性）ovarian tumor,is also called dermoid cystMeig’s syndrome 美格斯综合征ovarian fibromas（卵巢纤维瘤）accompanied by ascites（腹水）or hydrothorax （胸水）Krukenberg’s tumor 库肯勃氏瘤an special metastatic（转移的）ovarian carcinomacomes from gastrointestinal tract, which usually bilateral（双侧的）of moderate size, and retained the normal shape of the ovary妊娠滋养细胞疾病Hydatidiform mole 葡萄胎trophoblastic cells（滋养细胞）have different degree of proliferation （增生）. There is significant cystic degeneration（囊性变）of villous（绒毛的）stroma. Various size of vesicle（水泡）are formed. Connected with small pedicle（蒂的）and looks like a cluster of grapes,so it is called hydatidiform moleInvasive mole 侵袭性葡萄胎trophoblastic cells（滋养层细胞）proliferate（增殖）more market than the cell of hydatidiform mole（葡萄胎）, the villous stroma（绒毛间质）also form grape-like vesicle(水泡状) due to cystic degeneration of stroma. It’s invasive ability is strong and can invade into the myometrium（肌层）and metastasize（转移）to romote places生殖内分泌疾病Secondary amenorrhea 继发闭经secondary amenorrhea（闭经）in the absence of menses（月经）far 6 months in a woman whose, normal menstrucation（月经）has been established or for 3 normal intervals in a womanDysfunctional uterine bleeding, DUB 功血occurence of irregular and excessive uterine bleeding, patients have no organic disorders. Uterine bleeding is caused by dysfunction of hypothalamus-pituitary-ovarian axis（下丘脑-垂体-卵巢轴）Premature ovarian failure 卵巢早衰amenorrhea（闭经）failure of ovary happened before 40Sheehan’s syndrome席汉综合征this syndrome is due to atrophy （萎缩）of the anterior lobe of the pituitary gland, caused by ischemic（缺血的）necrosis（坏死) followed severe postpartum hemorrhage or shock. Amenorrhea（闭经）occurs with atrophy of genitalia（生殖器）. Sterility（不育）,loss of libido（性欲）and often the feature of hypothyroidism（甲减）such as loss of hair, dry wrinkled skin, apathy（冷漠）and constantly feeling coldAsherman’s syndromeamenorrhea that follows distruction or climination（消除）of the endometriu（子宫肌层）. It is usually the result of overzealous curettage（清宫术）, postpartum or artificial abortion. The result is intrauterine scarification（宫内瘢痕）, which may beseen as a pattern of multiple synechiae（粘连）on hysterography（宫腔造影）不孕症与辅助生殖技术Infertility 不孕症a couple is said to be infertile if pregnancy does not resulted after 2 years of normal sexal activity without contraceptives（避孕）rd from the myometrium（子宫肌层）计划生育Artificial abortion syndrome 人流综合征the major symptoms are brachycardia（心动过缓）,arrhymia（心律失常），hypotension（低血压），pale-faced, profuse sweating （多汗）and syncope（晕厥）even convulsion（惊厥抽搐）during the artificial abortion operation简答1.test ovarian function in amenorrhea patients卵巢功能检查(1)basal body temperature(2)cytological examination of smears from the vagina（阴道脱略细胞学）(3)diagnostic curettage（诊断性刮宫）(4)examination of cervical mucus（宫颈粘液）(5)investigation of E2 and P levels in plasma(6)B-scan ultrasonography（B超）2.Test placental function胎盘功能检查(1)test E3 in urine(2)test PRL and hPL in blood serum(3)fetal movement(4)OCT(5)test vaginal exfoliated cells（宫颈脱落细胞）(6)Manning score3.Mechanism of labor in LOA 左枕前位的分娩机制(1)engagement（衔接）(2)descent（下降）(3)flexion（俯屈）(4)internal rotation（内旋转）(5)extension（仰伸）(6)restitution（复位）(7)external rotation（外旋转）(8)expulsion of fetus（胎儿娩出）mon causes of Postpartum hemorrhage产后出血的原因(1)uterine atony（子宫收缩乏力）(2)placenta factors（胎盘因素）(3)genital tract lacerations（软产道撕裂）(4)clotting defects（凝血功能障碍）5.Operation indication of urterine myoma 子宫肌瘤的手术指征(1)menorrhagia（月经过多）leading secongdary anemia（继发贫血）(2)compression symptoms（压迫症状）of bladder or rectum（膀胱或直肠）(3)infertility（不孕）or abortion（流产）excluding other cause(4)suspicion of sarcomatous（肉瘤）change(5)severe abdominal pain, sexual pain, chronic painplication of induced abortion人流的并发症(1)uterine perforation子宫穿孔(2)artificial abortion syndrome(3)incomplete removal of the fetus and placenta吸宫不全(4)hemorrhage(5)the implanted zygote being missed by the cure漏吸或空吸(6)intrauterine adhesions宫内粘连（书上没有这一条）(7)amniotic fluid embolism（AFC，羊水栓塞）(8)infection(9)distant complication请注意：妇产科的趋势是比较少出英文简答，而是出英文选择和名解。

微生物学史微生物学史9

Function of Capsules
• Capsules can help pathogenic bacteria resist phagocytosis by host phagocytes.
• Capsules can protect against desiccation because they contain a great deal of water.
• It is usually composed of polysaccharides but is not as easily observed by light microscopy.
• Gliding bacteria often produce slime, which in some cases has been shown to facilitate motility
• Help maintain the shape and envelope rigidity of some cells, and promote cell adhesion to surfaces.
• Protect some bacterial pathogens against host defenses, thus contributing to their virulence.
• It is associated with the peptidoglycan surface of typical Gram-positive cell walls.
Biological roles of S-layer
• Protect the cell against ion and pH fluctuations, osmotic stress, enzymes, or predatory bacteria.

关于魔方的英语作文

The Rubiks Cube,a threedimensional puzzle,has been a popular and challenging toy for decades.It was invented by ErnőRubik,a Hungarian architect and professor of architecture,in1974.The cube has since become a symbol of intellectual challenge and a staple in the world of competitive puzzlesolving.IntroductionThe Rubiks Cube is a fascinating puzzle that has captured the imagination of people all around the world.It consists of six faces,each covered by nine stickers,and the objective is to return the cube to its original state where each face is a single color.HistoryThe invention of the Rubiks Cube was initially a teaching tool to help students understand threedimensional problems.However,its popularity soared when it was released to the public,and it quickly became a global phenomenon.StructureThe cube is composed of smaller cubes,or cubies,which are grouped into three categories:the core,the edge pieces,and the corner pieces.The core cubies are fixed in place,while the edge and corner pieces can be moved around the cube.Solving TechniquesThere are numerous methods to solve the Rubiks Cube,ranging from simple stepbystep algorithms to more complex speedcubing techniques.Some of the most popular solving methods include:Beginners Method:This involves solving the cube layer by layer,starting with the first face and moving on to the second layer,and finally solving the last layer. Advanced Techniques:For those looking to solve the cube more quickly,advanced techniques such as F2L First Two Layers,OLL Orientation of Last Layer,and PLL Permutation of Last Layer are used.Speedcubing:This involves learning and practicing algorithms to solve the cube as quickly as possible,often in competition settings.BenefitsSolving the Rubiks Cube offers several cognitive benefits,including:Improving Spatial Awareness:Players learn to visualize the cube in three dimensions, which enhances spatial reasoning skills.Boosting Memory:Memorizing algorithms and sequences helps to improve memory retention.Developing ProblemSolving Skills:The process of solving the cube requires logical thinking and strategic planning.Enhancing HandEye Coordination:The physical manipulation of the cube improves fine motor skills and handeye coordination.Competitive SceneThe Rubiks Cube has a vibrant competitive scene with official World Cube Association WCA competitions held worldwide.Speedcubers compete in various categories, including the3x3x3,2x2x2,and4x4x4,among others.ConclusionThe Rubiks Cube is more than just a toy its a tool for mental exercise and a platform for friendly competition.Its enduring popularity is a testament to the universal appeal of challenging oneself and the joy of solving complex problems.Final ThoughtsWhether youre a beginner looking to solve your first cube or an experienced cuber aiming to break records,the Rubiks Cube offers a rewarding and engaging experience.Its ability to stimulate the mind and foster a sense of accomplishment makes it a timeless puzzle that continues to captivate solvers of all ages.。

1550 nm高对比度光栅的VCSEL(中英双语)

1550 nm high contrast grating VCSELChristopher Chase, Yi Rao, Werner Hofmann, and Connie J.Chang-Hasnain* Department of Eletrical Engineering and Computer Sciences, University of California, Berkeley,CA 94720, USAAbstract: We demonstrate an electrically pumped high contrast grating(HCG) VCSEL operating at 1550 nm incorporating a porton implant-defined aperture. Output powers of ＞1 mW are obtained at room temperature under continuous wave operation. Devices operate continuous wave at temperatures exceeding 60℃. The novel device design, which is grown in a single epitaxy step, may enable lower cost long wavelength VCSELs.References and Links1. C. J. Chang-Hasnain, “Tunable VCSEL,” IEEE J. Sel. Top. Quantum Electron. 6(6), 978–987(2000).2.M. Lackner, M. Schwarzott, F. Winter, B. Kögel, S. Jatta, H. Halbritter, and P. Meissner, “COand CO2 spectroscopy using a 60 nm broadband tunable MEMS-VCSEL at 1.55 μm,” Opt.Lett. 31(21), 3170–3172(2006).3.M. Ortsiefer, R. Shau, G. Böhm, F. Köhler, and M. C. Amann, “Low-threshold index-guided1.5 μm longwavelength vertical-cavity surface-emitting laser with high efficiency,” Appl.Phys. Lett. 76(16), 2179 (2000).4.W. Yuen, G. S. Li, R. F. Nabiev, J. Boucart, P. Kner, R. J. Stone, D. Zhang, M. Beaudoin, T.Zheng, C. He, K.Yu, M. Jansen, D. P. Worland, and C. J. Chang-Hasnain, “High-performance1.6 μm single-epitaxy top-emitting VCSEL,” Electron. Lett. 36(13), 1121–1123 (2000).5.S. Nakagawa, E. Hall, G. Almuneau, J. K. Kim, D. A. Buell, H. Kroemer, and L. A. Coldren,“88 °C, continuouswave operation of apertured, intracavity contacted, 1.55 μm vertical-cavity surface-emitting lasers,” Appl. Phys. Lett. 78(10), 1337 (2001).6.N.Nishiyama, C. Caneau, B. Hall, G. Guryanov, M. Hu, X. Liu, M. Li, R. Bhat, and C. Zah,“Long-Wavelength Vertical-Cavity Surface-Emitting Lasers on InP With Lattice Matched AlGaInAs-InP DBR Grown by MOCVD,” IEEE J. Sel. Top. Quantum Elec tron. 11(5), 990–998 (2005).7. A.Syrbu, A. Mereuta, A. Mircea, A. Caliman, V. Iakovlev, C. Berseth, G. Suruceanu, A.Rudra, E. Deichsel, and E. Kapon, “1550 nm-band VCSEL 0.76 mW singlemode output power in 20–80°C temperature range,” Electron. Lett. 40(5), 306 (2004).8. C.Mateus, M. Huang, L. Chen, C. Chang-Hasnain, and Y. Suzuki, “Broad-Band Mirror(1.12-1.62 μm) Using a Subwavelength Grating,” IEEE Photon. Technol. Lett. 16(7),1676–1678 (2004).9.M.C.Huang,Y.Zhou, and C. J. Chang-Hasnain, “A surface-emitting laser incorporating ahigh-index-contrast subwavelength grating,” Nat. Photonics 1(2), 119–122 (2007).10.Y. Zhou, M. C. Y. Huang, C. Chase, V. Karagodsky, M. Moewe, B. Pesala, F. G. Sedgwick,and C. J. Chang-Hasnain, “High-Index-Contrast Grating (HCG) and Its Applications in Optoelectronic Devices,” IEEE J. Sel.Top. Quantum Electron. 15(5), 1485–1499 (2009). 11. A.Haglund, J. Gustavsson, J. Bengtsson, P. Jedrasik, and A. Larsson, “Design and Evaluationof Fundamental-Mode and Polarization-Stabilized VCSELs With a Subwavelength Surface Grating,” IEEE J. Quantum Electron.42(3), 231–240 (2006).12.M.Ortsiefer, M. Gorblich, Y. Xu, E. Ronneberg, J. Rosskopf, R. Shau, and M. Amann,“Polarization Control in Buried Tunnel Junction VCSELs Using a Birefringent Semiconductor/Di electric Subwavelength Grating,” IEEE Photon. Technol. Lett. 22(1), 15–17 (2010).13.M.C. Y. Huang, Y. Zhou, and C. J. Chang-Hasnain, “A nanoelectromechanical tunable laser,”Nat. Photonics 2(3), 180–184 (2008).14. C. Chase, Y. Zhou, and C. J. Chang-Hasnain, “Si ze effect of high contrast gratings inVCSELs,” Opt. Express 17(26), 24002–24007 (2009).15.V. Karagodsky, B. Pesala, C. Chase, W. Hofmann, F. Koyama, and C. J. Chang-Hasnain,“Monolithically integrated multi-wavelength VCSEL arrays using high-contrast gratings,”Opt. Express 18(2), 694–699 (2010).16.W.Hofmann, C. Chase, M. Müller, Y. Rao, C. Grasse, G. Böhm, M. Amann, and C. J.Chang-Hasnain, “Long-Wavelength High-Contrast Grating Vertical-Cavity Surface-Emitting Laser,” IEEE Photon. J. 2(3), 415–422 (2010).17.P. Gilet, N. Olivier, P. Grosse, K. Gilbert, A. Chelnokov, I. Chung, and J. Mørk,“High-index-contrast subwavelength grating VCSEL,” in Vertical-Cavity Surface-EmittingLasers XIV, J. K. Guenter and K. D. Choquette, eds. (SPIE, 2010), V ol. 7615, p. 76150J.1. IntroductionLong wavelength VCSELs are promising as a low cost laser source for metro area access networks [1], high speed optical interconnects, and diode laser spectroscopy [2]. They have traditionally been more challenging to realize when compared to GaAs-based short wavelength VCSELs because of several additional technical challenges posed by the InP material system, the most difficult of which are the top mirror and current aperture.The InP system is challenging to form a current aperture in because there is no easily oxidizable material in the system, unlike GaAs in which an aluminum oxide current aperture can be easily formed. Traditionally this problem has been overcome by forming a buried tunnel junction in the VCSEL structure [3]. Other approaches to solving this problem have been shown using an oxide aperture formed after pseudomorphic growth of GaAs-based materials above the active region [4], or by etching away layers in the middle of the VCSEL structure [5]. These aperture approaches are technically challenging and add expense to mass manufacturing long wavelength VCSELs.In addition to the challenge of the current aperture, the p-side mirror on the VCSEL also poses problems. The index contrast available in the InGaAIAs/InGaAsP/InP material system is substantially smaller than other VCSEL material systems. This small index contrast means greater than 40 pairs of epitaxial DBR are required on both bottom and top of the VCSEL structure, an extremely challenging technological proposition from the standpoint of epitaxial growth.This necessitates an alternative approach to the p-side mirror of the VCSEL structure. Typically a short current spreading p-region followed by a tunnel junction with n- region and intra-cavity contacts is employed [3]. The top mirror is then formed by either evaporating a dielectric mirror [6], wafer fusing an epitaxially-grown DBR grown on another material system [7], using an Sb-based DBR [5], or a metamorphically grown GaAs/AIGaAs top DBR [4]. These options are technologically challenging from a growth and fabrication standpoint and relatively costly compared to using a monolithic structure already including a p-GaAs/A1GaAs DBR as is used in a short wavelength VCSEL.Our group has reported that a high contrast grating [8], a grating subwavelength in period made of high index bars completely surrounded by a low index media such as oxide or air, cantotally replace the top DBR in a VCSEL [9]. An HCG provides intrinsic polarization control to VCSELs [10], a highly sought feature. Previously subwavelength gratings have been shown to provide polarization differentiation in VCSELs [11, 12], but because they were not completely surrounded by a low index material, they do not provide enough reflectivity for a VCSEL to lase, so a mirror in addition to the subwavelength grating was still required. When integrated on a wavelength-tunable VCSEL, a much faster tuning speed can be achieved due to the small mass of the HCG compared to a conventional DBR [13, 14]. In addition, HCGs can be leveraged to make controllably-defined arrays of VCSELs operating at different wavelengths for use in applications such as wavelength division multiplexing [IS].Electrically-pumped HCG VCSELs have been demonstrated at wavelengths of 850 nm, 980 nm and recently 1.32 um [9,10,16,17]. Many potential applications for VCSE current aperture Ls in next generation access networks and passive optical networks (PONS) require the VCSELs to operate at 1.55 um, and the InP material system is the widespread choice for a 1.55um active region. Here we report for the first time a 1.55 um HCG VCSEL on an InP platform operating continuous wave at room temperature. Due to a great reduction in epitaxial layer thickness above the active region, we can use proton implantation to form a current aperture. This novel design, hence, enables only one epitaxy step and simple fabrication, a feature that is very promising to manufacture high yield, low cost, long wavelength VCSELs.2. VCSEL design and fabricationA cross section of the device is shown schematically in Fig. 1. It consists of, starting from the substrate side, 45 pairs of n-DBR, an InP heat sink layer, an active region with 6 GaAlInAs quantum wells, and a thin layer of p-GaAlInAs, followed by a tunnel junction. Above the tunnel junction there are 2 pairs of n-DBR, followed by a -1.8 um air gap and a 195 nm thick InP high contrast grating. The grating is 12 X 12 μm2wide in all cases described here. Electrical confinement is provided in the structure by a proton implantation at a depth near the tunnel junction. The size of the proton implant aperture is varied from 8 to 25 um. Contacts are deposited on the backside of the wafer and topside on a contact layer above the HCG layer and surrounding the etched HCG.Fig 1. Schematic of a 1550 nm VCSEL with a suspended TE-HCG in place of a typical top DBR. Current confinement isprovided through the use of a proton-implant-defined aperture.The HCG in this structure is～195 nm thick and has a period of～1070 nm and semiconductor width of ～370 nm. The grating is designed to highly reflect light with electric field polarized parallel to the direction of the grating bars (TE), but not to the orthogonal polarization (TM). The grating is optimized so that it has a wide tolerance to the air gap dimension for ease of fabrication. Figure 2(a) shows the simulated reflectivity of HCG as a function of wavelength and light polarization (TE light (blue) has its electric field polarized along the bar direction while TM (red) is polarized perpendicular to the grating bar direction). The simulation is performed using rigorous coupled wave analysis (RCWA) [18]. Over 99% of TE-polarized light is reflected, while only～50% of TM-polarized light is. Figure 2(b) shows the reflectivity of the TE light as a function of wavelength over a smaller reflectivity interval. The TE HCG is over 99% reflective over a 150 nm range. In this simulation, parameters are fixed at: a grating thickness of 195 nm, a period of 1075 nm, and a grating duty cycle of 35% (～370 nm InP/～700 nm air). The HCG material is InP with a refractive index of 3.17 in all cases.Fig.2. a) Reflectivity of the HCG as a function of wavelength and polarization. The grating is highly reflective for TE light (blue, light with electric field polarized along the direction of the grating), and much less so for TM light (red, light polarized perpendicular to the direction of the grating). b) Zoomed in reflectivity of the TE polarization. The grating is over 99%reflective over a bandwidth of 150 nm.Device fabrication was carried out as follows. A current aperture was formed by protecting the aperture area by a thick photoresist, followed by a H + ion implantation with a dosage between 1014cm-2to 1015cm-2 and energy between 250keV to 400keV. A top annular n-contact subsequently was fabricated by lithography, metal evaporation and lift-off. A mesa was etched around the contact ring to the depth of the n-DBRs to electrically isolate the devices from each other.The HCG was defined by electron beam lithography and transferred by several steps of wet etching. In principle, the pattern could also be defined using a standard DUV lithography stepper. The HCG is then released by a selective etch of a sacrificial region below the HCC followed by critical point drying to prevent the structure from being damaged during the drying process. A scanning electron microscope (SEM) image of a completed HCG VCSEL is shown in Fig. 3(a). A zoomed in SEM image of the HCG is shown in Fig. 3(b).Fig. 3. SEM images of a (a) a completed 1550 nm HCG VCSEL (b) Zoomed in image of the high contrast grating, which is just195 nm thick.3.Characteristics3.1 Light-current-voltage characteristicsA series of VCSELs were fabricated with an identical HCG size of 12 X 12 um2and various implant aperture sizes, ranging from 5 to 20 um. The fabricated devices show excellent electrical and optical characteristics. Figure 4(a) shows the light-current (solid) and voltage-current (dashed) characteristics of a VCSEL with a 13 um proton implant aperture at various heat sink temperatures. The VCSELs have a threshold current of～3 mA at room temperature (AT) and lase continuous wave (CW) at temperatures exceeding 60 ℃. The RT peak output power is ～1.1 mW with slope efficiencies >0.25 mW/mA. Other devices with slightly higher thresholds showed up to 1.4 mW peak output powers at room temperature. The devices show a differential resistance of 60-100 Ω depending on aperture size.Fig.4. a) Light-current (solid lines) and voltage-current (dashed lines) characteristics of a HCG VCSEL with a 13 μm proton implant aperture at various heat sink temperatures. Devices show over 1.1 mW output power at room temperature and operate continuous wave to >60° C.b) Spectrum of the same device under various heat sink temperatures. A wavelength shift of0.12nm/K is extractedFigure 4 (b) shows its optical spectrum at a constant bias current of 8 mA at various heat sink temperatures. A wavelength shift of 0.12 nm/K is observed. A thermal resistance of 1.55 K/mW is also obtained, indicating good heat transfer away from the active region. At all biases the VCSELs emit in a single transverse mode with a side mode suppression ratio > 45dB. Single mode emission was seen in VCSELs with proton implant aperture size up to 20um. It should be noted though that the HCG is only 12 X 12 μm2, so the finite HCG size is also providing some transverse mode discrimination.3.2 Optical mode characteristicsFavorable optical mode characteristics for optical communications applications are also obtained due to the use of the HCG and a proton implant aperture. An important characteristic for VCSELs for mid-and long-reach optical communications links is polarization stability, as any polarization instability can have deleterious effects on an optical link. HCG VCSELs are polarization stable due to the high differentiation between the reflectivity in the orthogonal electric field polarizations as is shown in Fig. 2(a). Figure 5(a) shows the polarization-resolved light-current characteristics of a device with a 15 um proton implant aperture and 12 X12um2 HCG. The orthogonal polarization is suppressed by >20 dB (limited by the polarizer in the experimental setup).Since proton implant defined apertures provide little optical index guiding, it is possible to achieve larger size apertures while maintaining a single transverse mode emission profile .This makes the devices ideal for high coupling efficiency to a single mode fiber. The near-field intensity profile of a device with a 15 um proton implant aperture and 12 X12um2 HCG is shown in Fig. 5(b). This device emits in a single fundamental transverse mode with a full width half maximum (FWHM) of ～6.5 um. Generally, the devices have FWHMs of 40-50% of their lithographically defined aperture size. VCSFLs with >20 um proton-implant-defined apertures show no significant higher order transverse mode, since the finite area of HCG reflectivity (12 X12um2)contributes to the suppression of the higher order transverse modes in the largest aperture devices.Fig.5. a) Polarization-resolved light-current characteristics of a 1550 nm HCG VCSEL. A polarization suppression ratio of >20 dB is achieved, with the measurement limited by the polarizer. b) Near field intensity profile of the device at 2.5 X I th. A FWHM of ~6.5μm is obtained with a VCSEL with a proton implant aperture size of 15 μm.4.ConclusionWe present a 1550 nm VCSEL utilizing an HCG as a top mirror and proton implantation to form an electrical aperture. These devices can be simply fabricated using a monolithic epitaxial growth without the need for additional regrowth or dielectric mirror deposition.These devices have >1 mW output power at room temperature and operate continuous wave to greater than 60℃. Single mode operation is achieved with large apertures and no degenerate polarization modes. This simple VCSEL structure is promising for manufacturable, low-cost, long wavelength VCSEL for optical communications applications.AcknowledgementsThe authors would like to acknowledge support from the National Science Foundation through CIAN NSP ERC under grant #EEC-0812072 and a National Science Foundation Graduate Research Fellowship. We also thank the Berkeley Microfabrication Laboratory for their fabrication support.(译文)1550 nm高对比度光栅的VCSEL克里斯托弗大通，易扰，沃纳霍夫曼，康妮J.Chang - Hasnain *电子工程与计算机科学系，加州大学伯克利分校，加州94720，美国摘要：我们展示了一个工作在1550nm波长集成了波顿植入定义光圈的电动泵高对比度光栅（HCG）的VCSEL。

造纸术英语作文

Papermaking is an ancient Chinese invention that has played a significant role in the development of human civilization.The process of making paper from raw materials such as plant fibers dates back to the Han Dynasty,around105AD,when a Chinese court official named Cai Lun is credited with improving the technique.The basic steps involved in traditional papermaking are as follows:1.Harvesting Raw Materials:The first step in the papermaking process is to gather the raw materials,which traditionally included the bark of certain trees,hemp,and other fibrous plants.2.Pulping:The collected materials are then soaked in water and boiled to break down the fibers.This process,known as pulping,separates the fibers and prepares them for the next stage.3.Beating:After pulping,the fibers are beaten to further disintegrate the plant material and create a slurry.This is done using a device that can be a simple wooden mallet or a more complex machine.4.Mixing:The pulp is then mixed with water to create a uniform consistency.This mixture,known as the pulp suspension,is the basis for the paper.5.Forming:The pulp suspension is spread out into a thin layer on a flat surface,often using a screen or mold.This step is crucial as it determines the thickness and texture of the paper.6.Drying:Once the paper has been formed,it is left to dry.Traditionally,this was done by hanging the paper on a line or placing it under a press to remove excess water.7.Finishing:After drying,the paper may undergo further processes such as smoothing, cutting,and polishing to achieve the desired finish.The invention of papermaking had a profound impact on the world.It revolutionized the way information was recorded and disseminated,leading to the spread of knowledge and ideas.The technique spread to other parts of Asia and eventually to the Middle East and Europe,where it was further refined and adapted to local materials and needs.In modern times,papermaking has evolved with the use of machinery and new materials, but the fundamental principles remain the same.The process continues to be an essential part of our daily lives,from the paper we write on to the packaging materials we use forgoods.The art of papermaking is not only a practical skill but also an expression of creativity and culture.In some societies,it has become an art form in itself,with intricate designs and patterns incorporated into the paper,making it a treasured craft item.In conclusion,papermaking is a testament to human ingenuity and the desire to improve communication and recordkeeping.Its origins in ancient China and its subsequent spread across the globe highlight the interconnectedness of human civilizations and the shared pursuit of knowledge and innovation.。

渗流叠加原理英文

渗流叠加原理英文The principle of superposition of seepageThe seepage through soil or rock is governed by the principle of superposition. This principle states that the total seepage through a soil or rock mass is equal to the sum of the individual seepages caused by each of the independent factors acting on the mass. In other words, the seepage through a soil or rock mass is the result of the superposition or combination of seepage caused by different types of boundary conditions, source and sink terms, and heterogeneous soil properties.The principle of superposition is one of the fundamental principles of seepage analysis and has important implications in the design and analysis of many geotechnical engineering problems involving seepage.The following are some of the key implications of the principle of superposition in seepage analysis:1. Additivity of flows: The principle of superposition implies that the flows due to different boundary conditions can be added together to obtain the total flow through a soil or rock mass. This is a useful property that allow us to analyze complex seepage problems by breaking them down into simpler components.2. Linear relationship: The principle of superposition implies linear relationships between flows and potential gradients. This implies that whenthe potential gradients are multiplied by a constant factor, the resulting seepage flows will also be multiplied by the same factor. This property is important in the analysis of seepage problems involving varying boundary conditions.3. Compatible solutions: The principle of superposition implies that the solutions for seepage through different parts of a soil or rock mass must be compatible in order to satisfy the overall mass balance. This is achieved by satisfying the continuity equation for seepage in each part of the mass and ensuring that the seepage flows are consistent at the interfaces between the parts.4. Nonlinearity: Although the principle of superposition implies linearity in the relationship between flows and potential gradients, the seepage itself may be nonlinear due to nonlinear soil properties or hydraulic gradients. This implies that seepage solutions for certain types of soils or boundary conditions may not be compatible with the principle of superposition.In summary, the principle of superposition is a powerful tool in seepage analysis that allows us to analyze complex seepage problems by breaking them down into simpler components. However, the principle has important limitations that must be considered in the analysis of nonlinear soils, nonlinear boundary conditions, and other conditions that may violate the linearity assumption.。

5 304不锈钢应力腐蚀的临界氯离子浓度

图 4 是应变为 30％的试样在不同浓度 Cl－溶液中的阳极极化曲线。腐蚀电流密度在钝化区内很小，约为 2 μA/cm2（实验数据中得知），钝化膜表现出很好保护性。当电位超过钝化膜的破裂电位时，腐蚀电流密度迅速增加，304 不锈钢遭到严重腐蚀。因此，钝化膜的破裂电位是一个很重要的参数，可用来评价钝化膜在溶液中的稳定性。破裂电位越正，钝化膜越稳定；破裂电位越负，钝化膜的稳定性越差。腐蚀电流密度为 10 μA/cm2 时对应的电位为钝化膜破裂电位 Eb[14]，即图 4 中各条曲线转折处的电位。
样施加拉应力，通过恒应变条件下的电化学原位测试研究了 304 不锈钢钝化膜破裂电位与氯离子浓度的关系。得
出导致钝化膜破裂电位突变的 Cl－浓度与发生应力腐蚀破裂的临界 Cl－浓度是基本一致的结论。
关键词：304 不锈钢；钝化膜；应力腐蚀；临界氯离子浓度
中图分类号：TG 172.6
文献标识码：A
文章编号：1000–6613（2008）08–1284–04
Abstract：The stress corrosion cracking（SCC）susceptibility of type 304 stainless steel in NaCl solution was studied by slow strain rate test（SSRT）. The fracture morphology of SCC was observed and analyzed by using scanning electron microscope（SEM）. A new instrument was designed to apply stress to the specimen of type 304 stainless steel. The effect of chloride concentration on the passive film crack potential was also studied in situ by using the electrochemical technology under constant strain. The critical chloride concentrations of SCC and passive film crack potential for type 304 stainless steel were obtained，and they were basically the same. Key words：304 stainless steels；passive film；SCC；critical chloride concentration

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Influence of N,Ar and Si ion implantation on the passive layer andcorrosion behaviour of AISI 304and 430stainless steelsE.Cano a ,L.Martı´nez b ,J.Simancas a ,F.J.Pe ´rez-Trujillo b ,C.Go ´mez b ,J.M.Bastidas a,*aCENIM-National Centre for Metallurgical Research,CSIC,Avda.Gregorio del Amo 8,E-28040Madrid,SpainbDepartment of Materials Science,University Complutense of Madrid,E-28040Madrid,SpainReceived 17February 2005;accepted in revised form 27May 2005Available online 21June 2005AbstractSpecimens of AISI 304and AISI 430stainless steels (SS)were implanted with nitrogen,argon and silicon up to an ion dose of 1Â1015ion/cm 2at an accelerating potential of 150keV .AISI 304and 430SS specimens were analysed as-received and after ion implantation using X-ray photoelectron spectroscopy (XPS)in conjunction with Ar +-ion sputtering.Surface chromium enrichment was observed with the argon ion-implanted specimens compared with the non-implanted specimens,enhancing their corrosion resistance.Nitrogen implantation does not seem to have a significant effect on the structure and composition of the passive layer.Finally,silicon-implanted SSs show a very different passive layer,in which SiO 2is the main component of the outer surface.D 2005Elsevier B.V .All rights reserved.Keywords:Ion implantation;Stainless steel;Corrosion resistance;X-ray photoelectron spectroscopy1.IntroductionStainless steels (SS)are materials of great interest in technological applications.The stability of the surface oxide (i.e.passive film)formed on a SS depends mainly on the passivation time,temperature,alloy composition and work-ing environment.The solid state properties of the passive film have been widely studied using X-ray photoelectron spectroscopy (XPS),Auger electron spectroscopy (AES)and X-ray absorption spectroscopy (XAS)techniques [1–4].These studies have shown that the passive film formed on a SS exposed to aqueous solutions are Cr-enriched close to the alloy,with hydroxide and water-containing com-pounds concentrated in the outermost region of the film and chromium oxide enrichment at the metal-film interface.The ion implantation technique as a surface modification method presents some advantages over other techniques:(i)high temperatures are not needed;(ii)the bulk materialremains unaffected after the implantation process;and (iii)the surface to be modified can be tailored by controlling the accelerating potential and the implantation dose [5].The changes introduced on the SS surface by ion implantation can be evaluated by testing the outer layer’s chemical composition,which may influence the corrosion behaviour of the alloy.In recent studies,AES and XAS were used to determine the presence of implanted species on the steel surface [6,7].The aim of this paper is to investigate by the XPS technique the influence of nitrogen,silicon and argon ion implantation on the chemical composition and structure of the surface of the AISI 304and AISI 430alloys and on the Cr/Fe ratio,which affects their corrosion properties.The corrosion behaviour of the tested materials is also studied.The results are compared with argon sputtering measurements.2.ExperimentalAISI 304(Cr:18.30wt.%,Ni:8.19)austenitic SS and AISI 430(Cr:16.50wt.%,Ni:0.21,C:0.064)ferritic SS0257-8972/$-see front matter D 2005Elsevier B.V .All rights reserved.doi:10.1016/j.surfcoat.2005.05.029*Corresponding author.Tel.:+34915538900;fax:+34915347425.E-mail address:bastidas@cenim.csic.es (J.M.Bastidas).Surface &Coatings Technology 200(2006)5123–5131/locate/surfcoatwere the materials tested.The AISI304and AISI430 specimens were implanted using an accelerating potential of 80keV up to an ion dose of1Â1015ions/cm2for N,Si and Ar.Both AISI304and AISI430SSs were studied as-received and after Si,N and Ar ion implantation.The native oxide layer of the SS was not removed prior to the implantation process.The ions(N,Si and Ar)were obtained from a Penning ion source with a maximum acceleration voltage of300kV.The ion beam current was400nA and the implantation lasted for1h53min,ensuring a low testing temperature(below200-C).A diffusion pump generated a vacuum of10À7Torr in the acceleration cabinet. The cabinet was equipped with a rotating circular specimen holder of9-cm diameter.Silicon was chosen because its addition enhances the localised corrosion resistance of SSs by increasing the stability of the passive layer[8–12].Nitrogen implantation has met with varying degrees of success,ranging from beneficial to detrimental effects[13],depending on the implantation energy,the temperature reached during the process and the test solution used[10].The response of the implanted material is dependent upon its solubility limit.If the implanted N remains in solid solution it may generate ‘‘expanded austenite’’[14],increasing the localised corro-sion resistance.However,if the solubility limit is exceeded, the precipitation of chromium and iron nitrides takes place and a decrease in the corrosion resistance is observed[15–18].In the present work,no evidence of nitride precipitation was observed in either the AISI304or AISI430SSs. Finally,the implantation of argon leads to physical modifications on the SS by breaking its crystalline structure and changing the surface morphology[19].Argon implan-tation was performed in order to test whether the mod-ification observed with ion implantation are predominantly due to the chemical effect of the implanted element or to the physical modifications induced by ion implantation.Noble gases like neon have not proven to be beneficial for enhancing corrosion resistance,because of the high dis-location density induced in the crystalline structure[20,21].The choice of ion and the amount of energy employed in the implantation process were the controlling factors of the modifications induced in the SSs[22].In metallurgical experiments an implantation energy of80keV is considered to be an intermediate value.High values originate a deep distribution and reduce the effect of the ion implantation process,while low energies can produce an ion distribution fairly close to the surface and originate highly damaged regions.In the case of N implantation the amount of energy employed is particularly important.For instance,in tribol-ogy experiments the energies commonly used range between10and40keV,yielding different degrees of success in terms of corrosion resistance[23,24].The reason for this behaviour is that the ion distribution closer to the surface increases the nitrogen concentration,generating a supersaturation of the structure and favouring nitride precipitation,which is detrimental for the material’s corrosion resistance properties.Furthermore,low energy implantation induces preferential sputtering along the grain boundaries and in certain crystallographic directions[25].Fig.1shows implantation profiles performed using the TRIM2003computational code[26],obtaining the range (R),projected range(PR)and range deviation(D PR) parison of the implanted N,Si and Ar profiles on AISI304SS shows that the lighter the ion,the higher the PR achieved;in other words,nitrogen obtained the deepest penetration with the widest distribution, remaining in an inner region of the bulk.In contrast,argon obtained a shallower distribution due to the larger ion size, achieving the lowest PR value,and silicon implantation obtained intermediate values between nitrogen and argon. The simulation on the AISI430SS yielded similar results, although its less compact structure allowed a deeper penetration of the implanted ions(between2and6nm deeper).Polarisation resistance(R p)(corrosion potential(E corr)T 20mV)and Tafel polarisation measurements(b a and b c parameters)(E corr T250mV)were performed in a0.5M sodium chloride(NaCl)test solution.A three-electrode configuration method was utilised,with a Ag/AgCl refer-ence electrode,a graphite bar as counter electrode and the N-,Ar-or Si-implanted specimen as working electrode,with a surface area of2.1cm2.A PAR EG&G,model283, potentiostat was used.For R p and Tafel experiments a scan rate of0.166mV/s was used.XPS experiments were conducted using a VG Microtech model MT500electron spectrometer with an Mg K a1.2 anode X-ray source(h m=1253.6eV),with a primary beam energy of15kV and an electron current of20mA.The pressure in the analysis cabinet was maintained at1Â10À9 Torr throughout the measurements.The regions of interest were Fe2p3/2,Cr2p3/2,O1s,C1s,Si2p,N1s,Ar2p and Ni2p3/2.The binding energy(BE)scale of the spectropho-tometer was periodically calibrated using Ag3d5/2(368.3 Fig.1.TRIM implantation profiles for N,Si and Ar on AISI304SS using 10000ions.E.Cano et al./Surface&Coatings Technology200(2006)5123–5131 5124eV,BE)and Au 4f 7/2(84.0eV,BE)substrates.The full width at half-maximum (FWHM)obtained for the Ag 3d 5/2line is 0.9eV .High-resolution spectra were recorded using 20eV pass energy.A Shirley background subtraction was made to obtain the XPS signal intensity.The peaks were fitted using a Gaussian/Lorentzian product function.The specimens were analysed as-received and after 1,6and 21min of Ar +-ion sputtering at an etching rate ¨5A˚/min.Ar +-ion sputtering was carried out with a primary beam energy of 5kV and an ion density of 1A A/cm 2,recording the corresponding spectrum for each sputtering cycle.The specimen storage time between ion implantation and characterisation was 4weeks.3.Results and discussionFigs.2and 3show high resolution O 1s spectra for AISI 304and AISI 430SS specimens as-received and after argon,nitrogen and silicon ion implantation.All the spectra show similar features,except for the Si-implanted SS.Oxygen spectra can be deconvoluted in three components:the main peak located at 531.7eV BE corresponding to Fe and/or Cr hydroxides;a smaller peak located at 529.8eV BE corresponding to Fe and Cr oxides;and a third peak at 533.0eV BE corresponding to adsorbed water.In Si-implanted specimens,the main component of the O 1s spectra is located at 532.2eV BE and may be attributed to SiO 2[27],and a second peak is located at 533.2eV BE corresponding to adsorbed water.No evidence of metallicoxides or hydroxides is found in these spectra (see Figs.2and 3).Figs.4and 5show high resolution Fe 2p 3/2spectra for AISI 304and AISI 430SS specimens.As in Figs.2and 3,the spectra for all the specimens with the exception oftheFig.2.Oxygen 1s XPS spectra for as-received and Ar-,N-and Si-implanted AISI 304SSspecimens.Fig.3.Oxygen 1s XPS spectra for as-received and Ar-,N-and Si-implanted AISI 430SSspecimens.Fig.4.Iron 2p 3/2XPS spectra for as-received and Ar-,N-and Si-implanted AISI 304SS specimens.E.Cano et al./Surface &Coatings Technology 200(2006)5123–51315125Si-implanted specimens show similar deconvolution,corre-sponding to Fe 3+oxides (at 710.6eV BE)and Fe 2+oxides (at 709.2eV BE).On the other hand the Si-implanted specimens show no Fe signal,indicating that Fe compounds are not present on the outer surface of the passive layer.Figs.6and 7show high resolution Cr 2p 3/2spectra for AISI 304and AISI 430SS specimens.Similar features to Fe 2p 3/2(Figs.4and 5)can be observed.The chromium signal is not present in the Si-implanted specimens of either stainless steel.In the other specimens,chromium is present as Cr 3+oxide (at 576.2eV BE)and Cr 3+hydroxide (at 577.4eV BE).Neither metallic chromium (at 574.1eV BE)nor hexavalent compound (at 580.1eV BE)signals are present in the XPS spectra.Fig.8shows high resolution XPS spectra for implanted elements:Ar 2p for argon-implanted AISI 304and AISI 430SS specimens;N 1s for nitrogen-implanted AISI 304and AISI 430SS specimens;and Si 2p for silicon-implanted AISI 304and AISI 430SS specimens.These spectra show that implanted elements are present in the passive layer of the stainless steels.The position of the Si 2p peak,at 102.2eV BE,corresponds to SiO 2[27],in agreement with the O 1s deconvolution for these speci-mens (Figs.2and 3).These results indicate that the outer surface of the passivating layer of Si-implanted SS has a significant amount of SiO 2,without metallic oxides or hydroxides.The position of the N 1s peak,at 400.0eV BE,indicates that nitrogen is not forming Fe or Cr nitrides,which are located at lower binding energies (397.2–397.3eV BE)[28,29].Previous studies performed by the authors [30],using glancing angle XPS measurements without argon sputter-ing,revealed that the implanted argon remained inside the structure of both AISI 304and AISI 430SSs.Fig.5.Iron 2p 3/2XPS spectra for as-received and Ar-,N-and Si-implanted AISI 430SSspecimens.Fig.6.Chromium 2p 3/2XPS spectra for as-received and Ar-,N-and Si-implanted AISI 304SSspecimens.Fig.7.Chromium 2p 3/2XPS spectra for as-received and Ar-,N-and Si-implanted AISI 430SS specimens.E.Cano et al./Surface &Coatings Technology 200(2006)5123–51315126Figs.9and 10include depth profile compositions for AISI 304and AISI 430SS specimens,obtained using Ar +-ion sputtering up to 21min for as-received specimens and up to 6min for implanted specimens.The values in Figs.9and 10were obtained from the intensities of the correspond-ing XPS spectra using sensitivity factors [31].C,mainly arising from the contamination layer,was excluded from the calculations,for up to 6min of sputtering O is the main component,indicating that the passive layer is composed of Fe and Cr oxides and hydroxides.After 21min of sputtering the O signal has decreased and the Fe and Cr signals have increased to levels close to the content in the bulk specimen.The Ni signal appears for AISI 304SS after sputtering,indicating the presence of the metal phase.The main feature of the Ar-and N-implanted specimens of both steels is the appearance of small amounts of the implanted elements.With both AISI 304and AISI 430SS,the amount of N is higher in the outermost layer and decreases with the sputtering time,while Ar is found deeper in the passivelayer and increases with sputtering time.On the other hand,Si-implanted specimens show a different pattern,with a thick carbon layer that does not disappear after 6min of Ar +-ion sputtering and a very important amount of oxygen and silicon.This suggests that in Si-implanted steels there is a thick layer of C,Si and O compounds over the metallic oxides and/or hydroxides.Fig.11shows the Cr/Fe ratio in the passive layer of all the specimens,on the original surface and after 1and 6min of Ar +-ion sputtering.This parameter is very important from the corrosion resistance viewpoint,because a higher Cr/Fe ratio value is related with greater corrosion resistance.As can be observed,only Ar-implanted specimens present a significant increase in the Cr/Fe ratio,compared with the as-received SS specimens,suggesting improved corrosion resistance.In Si-implanted SSs the Cr/Fe ratio inspecimensFig.8.Argon 2p,nitrogen 1s and silicon 2p XPS spectra for Ar-,N-and Si-implanted AISI 304and 430SSspecimens.Fig.9.Depth profiles for as-received and Ar-,N-and Si-implanted AISI 304SS specimens.E.Cano et al./Surface &Coatings Technology 200(2006)5123–51315127without sputtering cannot be calculated,since neither Cr nor Fe can be found in the passive layer.Nevertheless,this parameter may be insignificant from the corrosion resistance viewpoint for Si-implanted SSs,as the corrosion resistance of these specimens may be increased by the SiO 2present in the outermost layer.It should be noted that the Cr/Ni ratio for the AISI 304SS has not been included in this discussion because the Ni signal was not detected in the passive layer.Fig.12shows polarisation resistance (R p )measurements for AISI 304SS with the implanted elements.An important increase in the R p value,and therefore an increase in the protective properties of the AISI 304SS,can be observed after ion implantation.The biggest increase in R p was obtained with argon implantation,followed by nitrogen and finally silicon,in which a 5-fold increase in the R p value was found.These results are consistent with the XPS studies,as the Ar-implantedspecimen is the only one that showed a significant increase in the Cr/Fe ratio.On the other hand,the Si-implanted specimen presented a SiO 2layer in the outermost region that also affords additional protection to the AISI 304SS.Finally,even though the N-implanted specimen did not show a significant increase in the Cr/Fe ratio,this was sufficient to promote an increase in the corrosion protection to the AISI 304SS.Fig.13shows R p measurements for AISI 430SS with the implanted elements.In this case a different behaviour from Fig.12was obtained,and though all theimplantationFig.10.Depth profiles for as-received and Ar-,N-and Si-implanted AISI 430SSspecimens.Fig.11.Cr/Fe ratios derived from the corresponding XPS spectra of as-received and Ar-,N-and Si-implanted AISI 304and 430SSspecimens.Fig.12.R p for non-implanted and N-,Ar-and Si-implanted AISI 304SS specimens.E.Cano et al./Surface &Coatings Technology 200(2006)5123–51315128tests raised the R p value,the Ar-implanted specimen showed a similar R p value to the untreated AISI 430SS specimen.The biggest increase in the R p value was obtained with Si implantation.The Si-rich layer in the outermost region provides great protection to the AISI 430SS.However,the Cr/Fe ratio for the Ar-implanted speci-men was not as favourable as in the AISI 304SS and,as a consequence,a slight variation of the R p values was obtained.In the N-implanted specimen,where a decrease in the Cr/Fe ratio was observed,an increase in the protective properties was obtained,reaching intermediate values between Si and Ar.The reason for this behaviour may be that ion implantation promotes important physical and chemical modifications on the surface,whose combi-nation results in unique surface properties.In the case of argon implantation on AISI 430SS,the damage induced with ion implantation seems to be more important than with nitrogen implantation and,therefore,a smaller increase in R p was registered.In order to obtain more information on the corrosion resistance of ion-implanted AISI 304SS,Tafel experi-ments were performed.Fig.14shows the evolution of E corr and the current density (i corr )with the implantation dose.In all cases,ion implantation increases the E corr and decreases the i corr .The protection against corrosion is inversely proportional to the i corr measured [32].An increase in the i corr value means degradation of the protective properties of the passive film [33–35].In this case,the increase in E corr is accompanied by a decrease in i corr which confirms the improvement in the corrosion resistance of ion implanted AISI 304SS.As occurred in the R p experiments (Fig.12),the modifications induced in the Ar-implanted specimen promoted the best protection conditions of AISI 304SS,with the lowest i corr .Never-theless,nitrogen and silicon implantation also improved the protective properties of the SS.An increase in E corrwas also observed by Veerabadran et al.[36]on N-implanted SS,although no previous results have been found in the literature relation with silicon and argon implantation on the E corr or i corr .Fig.15shows the anodic (b a )and cathodic (b c )slopes for AISI 304SS with the implanted elements.Ion implantation increases b a ,hindering the anodic reaction,while smaller modifications were observed in b c .Thus,N,Ar and Si implantation in these experimental conditions polarised the anodic reaction,increasing the protective properties and decreasing the corrosion process of the passive layer.The small variations found in the cathodic reaction show that no significant influence in this reaction may be attributed to the ion implantation process.N-implantation is known to play an important role in modifying the anodic reaction,hindering the dissolutionofFig.13.R p for non-implanted and N-,Ar-and Si-implanted AISI 430SSspecimens.Fig.14.E corr and i corr for non-implanted and N-,Ar-and Si-implanted AISI 304SSspecimens.Fig.15.Tafel slopes (b a and b c )for non-implanted and N-,Ar-and Si-implanted AISI 304SS specimens.E.Cano et al./Surface &Coatings Technology 200(2006)5123–51315129the SS [33,35].However,no influence of nitrogen on the cathodic reaction has been found in the literature,verifying the present results.Up to now,previous studies have not demonstrated that ion implantation of an inert gas like argon improves the corrosion resistance of SS,since no remark-able effect on corrosion behaviour has been found [37,38].Takahashi and Iwaki [39]reported that argon implantation is not an effective method for inhibiting the anodic dissolution of iron.However,Bonora et al.[40]pointed out that the effect of argon implantation depends on the ion dose and the test solution.In the experimental conditions employed in this work,an impediment in anodic dissolution was found.On the other hand,the Si-implanted specimen presented the greatest impediment for the occurrence of the anodic reaction.The Si-rich layer on the outermost part of the passive film seems to cause a greater delay in anodic dissolution,increasing the protective properties.Fig.16shows E corr and i corr values for AISI 430SS versus the implantation dose.It can be observed that ion implantation decreases the E corr and increases the i corr .Only the N-implanted specimen maintained similar values to the non-implanted specimen.Fig.17shows the b a and b c slopes for AISI 430SS with the implanted elements.An increase in the b a value can be observed with N and Ar implantation,hindering the anodic reaction.In contrast,silicon implantation decreases b a and favours the passive layer dissolution.The SiO 2layer does not seem to be sufficiently stable.Once again,smaller modifications of b c were obtained,and an increase can only be outlined with argon implantation.Therefore,despite the increase in i corr ,argon implantation hinders both the anodic and the cathodic reactions.On the other hand,silicon implantation enhances the corrosion process,favouring the anodic and the cathodic reactions.As a consequence,the constant B of the Stern-Geary equation:i corr ¼BR p,is modified and the relationship between i corr and R p changes,explaining the increase obtained in the R pexperiments.Finally,N-implanted specimen presents small modifications in the corrosion behaviour,which provided good protection for AISI 430SS.4.ConclusionsAll the implanted elements can be found in the passive layers of AISI 304and AISI 430SSs.Nitrogen has no significant effect on the structure or composition of the passive layers and is not found to form chromium or iron nitrides.The main effect of argon implantation is to increase the Cr/Fe ratio of the passive layer,which is associated with an improvement in the corrosion resistance of implanted steels.The passive layer of silicon-implanted SSs has a very different structure,with an outer layer composed of SiO 2.Metallic oxides and/or hydroxides are found deeper in the passive layer of silicon-implanted steels.Ion implantation increases the corrosion resistance of AISI 304SS.The best protection conditions were obtained with argon implantation,with which the highest Cr/Fe ratio was obtained.Despite the Si-rich layer on the Si-implanted specimen,a favourable Cr/Fe ratio may promote a great increase in the protective properties of AISI 304SS.However,different behaviour was obtained with AISI 430SS,where despite the modification of the corrosion process,no clear improvement in the protective properties was observed.AcknowledgementsThe authors express their gratitude to the CAI de Implantacio ´n Io ´nica,Complutense University of Madrid,Spain,and to ACERINOX SA for supplying the AISI304Fig.16.E corr and i corr for non-implanted and N-,Ar-and Si-implanted AISI 430SSspecimens.Fig.17.Tafel slopes (b a and b c )for non-implanted and N-,Ar-and Si-implanted AISI 430SS specimens.E.Cano et al./Surface &Coatings Technology 200(2006)5123–51315130and AISI430stainless steels used.L.Martı´nez expresses her gratitude to the Local Government of Madrid for the scholarship granted to 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