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一种沥青储存罐[实用新型专利]

专利名称：一种沥青储存罐专利类型：实用新型专利
发明人：王新亮
申请号：CN202020304542.9申请日：20200312
公开号：CN211811356U
公开日：
20201030
专利内容由知识产权出版社提供
摘要：本实用新型公开了一种沥青储存罐，包括罐体和电机，所述罐体上端开口中设有密封板，密封板上设有一个以上的搅拌杆，罐体内部的底面上设有一环形槽，环形槽内部活动安装有相匹配的定位环，定位环与搅拌杆之间均安装有连接杆，密封板上端设有一环形结构的齿条，齿条上的凸齿设置于外圈上，齿条的底面与密封板之间焊接固定有一块以上的连接块，齿条被所述的电机驱动。

本实用新型结构简单，电机能带动密封板旋转，密封板的旋转带动了搅拌杆，从而有效的对内部的沥青进行搅拌，避免了凝固，且在出料时，能下压密封板，通过密封板及橡胶层能有效的将罐体内壁面上的沥青及搅拌杆上的沥青刮去，避免了残留，从而不影响后续的使用。

申请人：王新亮
地址：514531 广东省梅州市兴宁市叶塘镇大路下村无尽卢屋14号
国籍：CN
代理机构：深圳市世通专利代理事务所(普通合伙)
代理人：阮文沁
更多信息请下载全文后查看。

21238225

ｅ．２０
超高射频火炮射击实验及内弹道过程仿真
杨均匀，袁亚雄，张小兵，邹瑞荣
（南京理工大学动力工程学院，江苏南京２０￣）１０
摘
要：该文进行了超高射频火炮膛内串联排列的３发弹丸的射击实验，建立了膛内过程的经典
内弹道模型，并进行了数值模拟。计算结果和实验结果很接近，明该模型用于模拟超高射频表火炮高频连发的膛内过程是可行的。利用该模型分析了射击频率对最大膛压和初速的影响，计算结果表明：高射频火炮的射击频率应该有一上限，超就是在上一发弹出炮口并且膛内压力下
降到一定压力时再击发下一发弹，才能避免各弹丸之间的相互影响，使初速散布减小。关键词：高射频；超火炮；内弹道；数值模拟
中图分类号：Ｊ１．１Ｔ２１０
文献标识码：Ａ
文章编号：０５９３（０６０ — ０５０１ — ８０２０）１００ — ３０
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澳大利亚金属风暴公司研制的“ 金属风暴” 系列武器系统，它摒弃了传统的机械式供弹结构，采用１％电路来控制每发弹的击发。它的核心特００
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光子晶体的现代与未来

*Corresponding author.E-mail address:t.krauss @ (T.F.Krauss)Progress in Quantum Electronics 23(1999)51}96Photonic crystals in the optical regime *past,present and futureThomas F.Krauss *,Richard M.De La RueDepartment of Electronics and Electrical Engineering,The Uni v ersity of Glasgow,G128LT,Scotland,UK AbstractDuring the last decade,photonic crystals,also known as photonic microstructures or photonic bandgap structures,have matured from an intellectual curiosity concerning electro-magnetic waves to a "eld with real applications in both the microwave and optical regime.In this review,we shall focus on progress and the prospects for semiconductor structures that mainly involve guided modes interacting with periodic structures,but we also evaluate alterna-tive material systems and fabrication methods,e.g.those based on self-organisation.We shall go from basic concepts,via a discussion of the state of the art,to device applications.Naturally,the discussion of the applications will be more speculative,but we attempt to evaluate the real prospects o !ered by photonic crystals at optical frequencies while considering practical limita-tions.In doing so,we identify a variety of areas such as the combination of quantum dot light emitters with photonic crystals that seem particularly promising.We discuss the prospects for enhanced light }matter interactions in photonic crystals and the related material and design issues.Overall,the aim of this review is to introduce the reader to the concepts of photonic crystals,describe the state of the art and attempt to answer the question of what uses these peculiar structures may have. 1999Elsevier Science Ltd.All rights reserved.Keywords:Photonic crystal;Photonic bandgap;LED;Laser;Optoelectronic materials;Semiconductors1.Introduction522.The past *how did it all start?532.1.The basic concept532.2.Initial realisation543.The present *state-of-the-art573.1.How to make a photonic crystal?573.2.Di !erent methods of characterising photonic crystals670079-6727/99/$-see front matter 1999Elsevier Science Ltd.All rights reserved.PII:S 0079-6727(99)00004-X52T.F.Krauss,R.M.De La Rue/Progress in Quantum Electronics23(1999)51}964.The future*applications for photonic crystals704.1.Light emitting diodes(LEDs)70sers784.3.Other materials804.4.Photonic VLSI834.5.Surface plasmons854.6.Quasiperiodic structures864.7.Quantum cascade-based light emission895.Conclusions90 Acknowledgements92 References92 1.IntroductionFrom the beginning of civilisation,man has sought to illuminate the darkness. Fires,gas lights and Edison's light bulb are but a few in a long chain of light sources that have been employed.Considering the high level of technical sophistication that we have achieved,it is surprising that we still rely mainly on such archaic light sources as the incandescent light bulb or on#uorescent strip-lights,particularly since these light sources typically waste80}95%of the electrical energy input.This is a state of a!airs that needs to be improved,so better light sources are required.This need has already been recognised in a recent report compiled by the U.S.Academy of Sciences [1],who cite lighting by LEDs as having a major impact on the economy in the next century,both in terms of lighting and energy saving.In order to make more e$cient LEDs,we need to use the concepts of photonic crystals,which brings us to the main topic of this paper.As far as the material for LEDs is concerned,semiconductor-based light emitters are the obvious choice.Mainly driven by the needs of the information technology industry,semiconductor light-emitting materials have reached a level of sophistica-tion that surpasses that of any other light-emitting material known to man,with internal quantum e$ciencies above90%being routinely obtained.Unfortunately, most of this light is trapped inside the material,and only3}20%can escape,the remainder being eventually re-absorbed and lost as heat(Fig.1a).Laser diodes o!er one way out.They rely on stimulated emission and are therefore more e$cient than LEDs,but are not applicable to every problem.Some applications, such as displays,demand the simpler and cheaper LED,since the high level of coherence of laser light is not desirable,or the generally higher cost and temperature dependence of laser diodes is prohibitive.Therefore,a concept that o!ers the ability to improve the e$ciency of LEDs is a welcome addition to the toolbox.Photonic crystals represent this concept,and their advantage lies in addressing the extraction problem mentioned above.Moreover,photonic crystals not only o!er a simple improvement of the extraction of light from LEDs,they can also alter the fundamental process of light generation in the material itself(Fig.1b).Perhaps more signi"cantly,they can improve the operating characteristics of laser serT.F.Krauss,R.M.De La Rue/Progress in Quantum Electronics23(1999)51}9653Fig.1.(a)`Classical a LED:the emission cone(shaded)is very small and only a fraction of the light generated in the material can escape the device,the rest is trapped by total internal re#ection.(b)Micro-structured emitter:light that would not radiate into the emission cone is suppressed by the photonic crystal, i.e.there are no modes for the emission to radiate into,so all spontaneous emission is channelled into the `useful a modes of the device.In principle,the external e$ciency of such a device can reach the internal e$ciency of the material of'90%.diodes have experienced a tremendous development in recent years,and speci"c devices have already shown total external(`wallplug a)e$ciencies of50%and above [2}4].Most types of laser,however,still waste too much light,light that could be re-used,or not be emitted in the"rst place,if photonic band gap principles were applied.So,be it a laser or an LED,photonic crystals promise improvement.Their ability to control the#ow of light and their capacity to concentrate light and enhance light}matter interaction is certainly inspiring.Examining whether this promise is realistic and what else they have to o!er,e.g.in the realm of passive devices,such as "lters and waveguides,is the purpose of this paper.In Section2,we introduce photonic crystals and show how they have emerged.A review of the state of the art is given in Section3and a speculative forward-look at what they may be used for in the short and longer term is attempted in Section4.2.The past*how did it all start?In1946,Purcell[5]was the"rst to discuss the fact that the presence of a mirror can substantially alter the radiation properties of an electromagnetic dipole.This insight was further developed over the years,and in1987led to the concept of a photonic band gap[6,7],a concept that was borrowed from semiconducting crystals in analogy to their electronic band gap.2.1.The basic conceptThe general idea is that photonic crystals do to photons what semiconductor crystals do to electrons,i.e.they create a situation whereby photons in a certain energy range cannot travel through the crystal and are re#ected when impinging onto the crystal or are not allowed to propagate at all when generated inside it.The latter point is conceptually very important,because one should not imagine a situation whereby light is emitted from the source,re#ected back by the crystal,eventually re-absorbed, re-emitted and so on.The situation is rather that the photon is not emitted in the"rst54T.F.Krauss,R.M.De La Rue/Progress in Quantum Electronics23(1999)51}96place,because there is no quantum mechanical state into which it can go.Fora general introduction to the concepts and underlying theory of photonic crystals,the reader should consult earlier review papers[8}10]and the excellent textbook byJoannopoulos et al.[11].2.2.Initial realisation2.2.1.3-D photonic crystals in the microwa v e regimeAfter a period of speculation,some controversy[12,13]and a large theoreticale!ort,it was"nally shown conclusively that such photonic band gap materials wereindeed possible[14,15].The"rst experimental demonstration appeared in1991[16],using an array of holes drilled into high refractive index material.The arti"cial crystalthus created(later termed`Yablonovite a after its inventor)showed a stop-band forthe transmission of microwave radiation that extended from13GHz to about15GHz,irrespective of the direction of propagation,so these structures exhibiteda truly`forbidden a zone,a band gap.Another feature reminiscent of semiconductorsis the possibility of`doping a these structures.By including a defect,i.e.locally addingor removing material,it was possible to demonstrate localised states in the band gap[16].The semiconductor analogy extends as far as the type of dopant,with materialaddition leading to a`donor a-type defect,i.e.a state near the`conduction band a ofthe crystal band structure and material removal resulting in an`acceptor a state nearthe`valence band a.An immediate application was found by placing an antenna ontothe top of an(undoped)crystal[17].With no radiation being allowed to enter thecrystal side of the antenna,the emission into the air side was greatly enhanced,thusclearly showing that photonic crystals can alter the radiation process itself.2.2.2.3-D photonic crystals in the optical regimeAlthough the microwave regime is a very useful testing ground and o!ers a varietyof applications for photonic crystals,there has always been a drive towards truly`photonic a applications,i.e.structures that operate in the visible or near IR regime of the electromagnetic spectrum.One approach is to take fabrication methods that were"rst successfully demonstrated on samples in the microwave regime and then scalethem down,usually employing some sort of stacking technique.These`layer-by-layer a photonic crystals have now matured to the point of reaching into the far-infared, e.g.a structure displaying a stop-band between 1.35and 1.95 m wasdemonstrated recently[18].Another approach that has also been successful at making structutes for the1.5 mwindow is to use micro-fabrication techiques and re"ne them to the extent thatstructures can be made at the desired wavelength.Impressive results have beenachieved on that front[19,20]but have unfortunately failed to show the expectedsharp spectral response.A third approach is to let nature do the ordering,e.g.in the form of opal,a self-organised structure consisting of closely packed silica spheres.This is possiblythe most convincing of the di!erent approaches towards fully3-D periodic structures,although the results shown to-date indicate the promise of the approach rather thanT.F.Krauss,R.M.De La Rue/Progress in Quantum Electronics23(1999)51}9655providing a fully convincing demonstration.The main problems are the lack of`pure a material with su$cient uniformity and without unwanted defects,the relatively low intrinsic refractive index contrast and the fact that opal is optically passive.In order to increase the index contrast,and to achieve optical gain,the silica spheres that comprise opal can be doped,e.g.with rare-earth ions,or the voids between the individual spheres can be back-"lled(`loaded a)with suitable material.These tech-niques and their promise will be discussed in more detail in Section3.1.6.2.2.3.2-D photonic crystals in the optical regimeIn contrast to the limited experimental successes with three-dimensional structures, work on2-D structures has#ourished and produced many interesting results.This progress is mainly due to the fact that two-dimensional structures are easier to make, in particular with the aid of the tools developed for the silicon microchip industry. Lower dimensionality also implies easier manipulation of the photonic lattice to increase functionality,such as the deliberate inclusion of defects,as mentioned above, or interfacing with`standard a optical elements,such as waveguides,"bres,light sources and detectors.We shall discuss two-dimensional structures in more detail, because so much work has been done on them.The main factors that determine the properties of two-dimensional photonic crystals are the refractive index contrast,the fraction of high and low index materials in the lattice and the arrangement of the lattice elements.As a general rule,the higher the refractive index contrast,the stronger the expected e!ects and the larger the band gap achievable.The refractive index contrast is typically limited to that between GaAs (n"3.6)and air.As to lattice con"gurations,the most promising ones are the `honeycomb a[21](Fig.2)and the`graphite a[22]structure where the widest band gaps occur when small regions of semiconductor are surrounded by large regions ofair,i.e.when the semiconductor`area"ll-factor a is low,a direct consequence of the high refractive index of the semiconductor.The`hand-waving a reason for this condition is that the maximum e!ect can be achieved when the optical path length in both materials is roughly equal,in direct analogy to the` /4a criterion of dielectric Bragg mirrors.An additional factor is that of light con"nement in the third dimension;there,the structure must either:(a)be large compared to the beam size(i.e.many wavelengths deep)or(b)the beam must be su$ciently con"ned within a waveguide to experience the full interaction with the periodic lattice.Several`in"nitely deep a structures have been successfully demonstrated[23}27](Fig.3),although most structures presented to date utilise some sort of waveguide con"nement.The waveguide con"guration has obvious advantages,such as growth of layered structures by established epitaxial methods and compatibility with other planar optoelectronic elements.There are, however,major problems that need to be addressed when designing the structure. The naive point of view is as follows(Fig.3):A high refractive index contrast is typically achieved by etching,so the structure is separated into areas of high-indexThe` /4a criterion states that each layer in a Bragg mirror should be /4n thick for highest re#ectivity.Fig.2.Example of a typical 2-D photonic lattice,consisting of holes etched into semiconductor.The type of lattice is triangular,it is self-similar upon 603rotation and the arrows illustrate the two main directions of symmetry.Solid-state physics provides the terminology,with the direction indicated by the darker arrow referred to as !K and the lighter arrow pointing along !M.Fig.3.(a)A deeply etched waveguide,designed according to `conventional wisdom a for maximum re #ectivity with the high and low index layers /4n thick.This con "guration su !ers from di !raction losses,becauses light is not guided in the low index region and di !racts out of the waveguide plane.(b)If the air gaps,i.e.the etched holes or slots,are small enough,there is very little loss.Strong interaction between the periodic structure and the guided mode can then take place as long as the period of the structure is an integer multiple of half-wavelengths.material,typically semiconductor (with the in-built waveguide structure)and air.Light is then only guided in the semiconductor and not while travelling through the air,so di !raction loss and scattering into the third dimension (i.e.out of the plane of the waveguide)is inevitable.This loss can be minimised by increasing the "ll-fraction of semiconductor,for example by designing a lattice of pillars with narrow air gaps or a semiconductor honeycomb structure with small air holes.The principle of this approach is that light can `hop a across the narrow gaps without su !ering excessive loss,whilst still experiencing the full refractive index contrast between semiconductor and air.This solution compromises the highest achievable band gap and is in direct contrast to the ` /4a condition given above,but it56T.F.Krauss,R.M.De La Rue /Progress in Quantum Electronics 23(1999)51}96T.F.Krauss,R.M.De La Rue/Progress in Quantum Electronics23(1999)51}9657 is the approach that has so far shown the most convincing PBG e!ects in structures with low-contrast claddings,e.g.semiconductor heterostructure waveguides.These structures have allowed the observation of a variety of PBG e!ects,including high transmission,re#ection and very sharp"ltering characteristics[29,30].Also,keeping the substrate has the great advantage of allowing current injection.From an optical point of view,however,it would be better to remove the semiconductor substrate. Thin"lms of semiconductor on glass or in air,for example,support more strongly con"ned modes that can be inherently non-lossy[31,32]and thereby more suited to guiding and con"ning light.3.The present*state-of-the-art3.1.How to make a photonic crystal?There is a variety of ways of making photonic crystals,many of which have been borrowed from the silicon microelectronics industry.3.1.1.Lithography and etching3.1.1.1.Lithography.As stated above,some of the impressive progress has been made with planar structures that were patterned by lithographic means.Considering the small size of the lattice(periodicity between200and700nm,with sub-100nm control of feature size desirable),standard photolithography cannot be employed. The most popular alternative is electron-beam lithography,which has been exploited by a variety of groups to generate patterns for use in the visible[33]to near-IR [34,35].Several workers have also succeeded in using multiple exposure holography[36]to generate the triangular pattern.Multiple exposure holography is,in fact,a technique that has been used for some time[37,38]to produce two-dimensionally periodic structures.3.1.1.2.Masking.In several ways,the most suitable structure for a2-D photonic crystal is one consisting of a matrix of small holes etched deeply into the semiconduc-tor.This requires deep and anisotropic etching with high resolution,so generally,con-ventional wet etching techniques cannot be used.Anodic etching,i.e.wet etching with an applied electric"eld,is an exception and is discussed separately in Section3.1.2. One of the most important elements contributing to the success of the etching process is the choice of an appropriate mask layer.The most straightforward solution is to use the resist itself,after development.Since the resist erodes at a considerable rate during the dry etch process,however,the obtainable etch depth is limited, With optical lithography advancing to shorter and shorter wavelengths,however,it can be expected that by the time devices based on photonic crystals are entering the marketplace in large volume,they will be made by photolithographic means.58T.F.Krauss,R.M.De La Rue/Progress in Quantum Electronics23(1999)51}96 particularly for high-resolution patterns that demand thin resists.Therefore,in order to allow deeper etching,a dielectric pattern-transfer layer is usually added.This layer (typically SiO or Si N )is patterned by plasma etching using#uorine chemistry(wefound that CHF is superior to CF or C F because of lower resist erosion).The thickness chosen for this dielectric mask is a compromise and is typically around 100}200nm;the thicker the mask,the longer it withstands the plasma and the deeper one can etch the semiconductor.The thinner the mask,the thinner a resist one can use to pattern it and thus achieve higher resolution.In our work,we found an erosion rate for the dielectric mask of around15}20nm/min.Better masking is provided by a layer of oxidised Al V Ga \V As(&AlO x'),an approach that was"rst demonstrated by Cheng et al.[20].We have observed an erosion rate of only3nm/min for a layer of oxidised80%x-fraction AlGaAs,which is a considerable improvement over externally deposited dielectrics.The oxidation is carried out at 400}4503C in a wet steam atmosphere,a process that has been widely studied,mainly for current aperturing in vertical cavity surface-emitting lasers(VCSELs)[39,40]. Despite this obvious improvement in erosion rate,AlO V masks have not been widely used,in part because they have to be designed into the epitaxial material structure. Finally,one can add a thin layer of metal to the process,and pattern it either by lift-o! or by ion milling[19]and then use the patterned metal layer to transfer the structure into the dielectric.This approach gives better masking,but raises the question whether the improvement is worth the additional e!ort,considering that each pro-cessing step increases the cost and failure rate.3.1.1.3.Dry etching.The standard etch chemistry for GaAs/AlGaAs semiconductors is chlorine-based,using either SiCl or Cl .Chemically assisted ion-beam etching (CAIBE)is arguably the most suitable dry etching technique available,with aspect ratios'20:1achieved[41](120nm holes etched&2.5 m deep).In CAIBE, a collimated high-energy beam impinges on the sample,which results in better directionality and much reduced RIE lag.Our standard process for GaAs/AIGaAs-based fabrication uses e-beam patterning of PMMA(200nm thick,350K molecular weight),transfer into a&150nm layer of SiO and etching using SiCl in a standard RIE reactor.Typically,we obtain an aspect ratio of6}8:1(e.g.100nm holes etched600}800nm deep,Fig.4),which has been su$cient to demonstrate a range of PBG e!ects in the waveguide geometry,with moderate losses[28,29,42].InP-based photonic crystals can be etched in either CH /H [43]or in chlorine-containing plasmas.Although vertical sidewalls and non-selective etching have both been achieved with CH /H ,the process is plagued by the buildup of polymer,which tends to clog up small features and,in our case,has prohibited the etching of lattice periods smaller than0.5 m.This problem can be overcome by the use of chlorine chemistry,a solution that is not straightforward,however,because InCl ,one of theRIE lag describes the fact that small features experience a smaller etch depth than large features,which is related to the lateral motion of the impinging ions.Fig. 4.Two examples for 2-D photonic lattices,written by e-beam lithography and etched into a GaAs/AlGaAs waveguide structure using RIE and dielectric masks.The lattice periods are 290nm (right),respectively.Left micrograph courtesy of C.Smith,University of Glasgow.main reaction products,is not volatile below 1303C *and so a heated stage is required for the process.Hot etching of InP has been demonstrated successfully in both CAIBE [44]and with our standard RIE reactor,the main problem consists of "nding the (reactor dependent)balance between the chemical (temperature,reactive gas #ow)and physical (DC bias or acceleration voltage)etching components.3.1.2.ElectrochemistryAn alternative method for producing 2-D lattices involves electrochemistry,namely anodic etching and growth.Impressive aspect ratios have already been obtained,both in silicon (Fig.5)and alumina.Initial work by Gru ning et al.[23]produced 2-D crystals where the elusive goal of an `in "nitely high a array of holes was closely approximated.The term `in "nitely high a is to be understood in the context of the wavelength;the structures were up to 340 m deep and exhibited band gaps around 40 m wavelength.The etched holes had a diameter of 6.2 m,which constitutes an aspect ratio of '50:1and compares favourably with the ratios (10:1that are typically achieved by dry-etching.Due to the generally `macroscopic a (1}50 m)feature size of the electrochemically etched holes,the material thus produced is termed `macroporous a silicon,in contrast to its `microporous a relative (Section 4.3.1).Macroporous silicon with feature sizes in the sub-micron range has been demon-strated [27,45],although most PBG-related experimental work is aimed at mid-to far-IR wavelengths [25,26].Much smaller structures that could display photonic band gaps in the visible regime have already been produced by the related technique of anodic growth of alumina pores.The pores were grown on a surface of aluminium embossed with regular arrays of concave dimples that acted as seeds for the growth.Impressive aspect ratios forT.F.Krauss,R.M.De La Rue /Progress in Quantum Electronics 23(1999)51}9659Fig.5.Micrograph of a 2-D photonic crystal fabricated by anodic etching (`macroporous silicon a ).The structure depicts a hexagonal or `graphite a lattice as highlighted in the inset.Courtesy of A.Chelnokov and J.-M.Lourtioz,Universite Paris-Sud,France.holes,with diameters as small as 70nm and periodicities of 100nm,were reported by Masuda et al.[46].The high degree of regularity achievable with electrochemical processes surpasses that of structures generated by lithographic means,but constitutes a mixed blessing;the only requirement to initiate the process is some discontinuity on the surface.Once the process has started,the pore size is determined by the electrochemical current,not the size of the seed [46].Therefore,the growth mechanism has a tendency to accommodate deterministic defects and possibly eliminate them as the process pro-ceeds,producing a defect-free crystal after a certain depth (or height,respectively).3.1.3.Vertical selecti v e oxidationThe motivation for etching holes or slots into a material is to create a high refractive index contrast.By removing material,however,the surface is left perforated,which makes it di $cult to deposit mirrors or contacts afterwards.Also,the device may age prematurely because of chemical reactions at the exposed surface.An intriguing variant to removing material that addresses these issues is the technique of selective oxidation.A lattice produced by selective oxidation maintains the physical integrity of the material and produces an `all-solid a microstructure.The oxidation technique was "rst proposed in the early 1990's [40]as a way of converting AlAs (or AlGaAs with a high Al-content,generally Al '80%)into a thermodyn-amically stable oxide.The process involves placing the sample into a steam environ-ment at 400}4503C and produces an oxide with two desirable qualities:(a)The oxide is a good electrical insulator,which is the reason for its use as a current-blocking layer 60T.F.Krauss,R.M.De La Rue /Progress in Quantum Electronics 23(1999)51}96In collaboration with Dr.M.Dawson,Strathclyde University,Glasgow,UK.Fig.6.Example for the technilque of vertical oxidation,driven by a composition gradient.The oxidation rate in Al Ga \ As is exponentially dependent on the Al-fraction x .By increasing the Al-fraction with depth,an arti "cial anisotropy is introduced into the oxidation process,leading,ideally,to `oxide pillars a .The sketch illustrates the progression of the oxidation front in four steps with time and the micrograph depicts an oxide pillar that was slightly over-oxidised.In the particular example,the composition was graded from x "0.88near the surface to x "0.95near the substrate.The oxidation time was 3min at 4203C in an open-tube furnace.in vertical cavity surface-emitting lasers,VCSELs [47],and (b)it has a low refractive index,i.e.between 1.5and 1.6[48].The low refractive index is the most exciting aspect as far as photonic crystals are concerned,because it facilitates the growth of the entire structure,including all electrical and optical functions,by standard epitaxial means with the low-index areas being converted by relatively simple processing afterwards.The main problem with the technique is that it usually proceeds in the lateral direction,i.e.in a plane parallel to the surface,whereas typical photonic lattices are structured in the veritcal direction,i.e.normal to the surface.Our group has recently explored the possibility of vertical oxidation,with the aim to replace etched holes by `oxide pillars a (Fig.6).To accomplish substantially vertical oxidation,the Al-content of an AlGaAs layer is graded,with the higher Al-content closer to the substrate.The exponential dependence of the oxidation rate on the Al-content [39]then drives the reaction downwards in an anisotropic fashion.For masking,we have used a thin (50nm)layer of GaAs,which was either removed locally by wet etching or damaged by exposure to an RIE-generated plasma of CHF .The latter process has the great advantage of leaving a near-perfect surface with the high contrast microstructure embedded in the material underneath.Our current estimate for the aspect ratio of these pillars is around 1:1,which is not as impressive as the ratios of upto 10:1achieved with dry etching techniques.Another problem is the volume shrinkage of up to 13%[39]which can lead to strain,microcracks or structural problems such as delamination of the layer structure if the oxide is too thick.Careful process control is also required,as illustrated by the overshoot seen in Fig.6.Overall,the technique of vertical oxidation is not without drawbacks and requires more work,but it eliminates the side-e !ects of dry etching,such as damage and ion。

仙人掌外用治验实录

仙人掌外用治验实录
王保民
【期刊名称】《浙江中医杂志》
【年(卷),期】2001(036)010
【摘要】@@ 本品乃仙人掌科植物仙人掌的根和茎,在我国大部分地区均有分布或栽培 .笔者取其鲜品外敷治疗多种皮肤、外科疾病, 取效甚佳,现介绍于下.rn1 药物制备及用法rn取仙人掌鲜品若干,洗净、去针刺,捣烂如泥,加食醋或明矾少许,置干净容器内 .视病情轻重把配制好的药糊敷于患处,或1日1换,或半日1换,或数小时1换,敷药处上覆浸有生理盐水的消毒敷料保湿.rn2 临床应用
【总页数】1页(P460)
【作者】王保民
【作者单位】江苏省东海县中医院,
【正文语种】中文
【中图分类】R28
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亮丽数字彰显“十二五”开门红

亮丽数字彰显“十二五”开门红
佚名
【期刊名称】《中国农垦》
【年(卷),期】2012(000)003
【摘要】2011年，宁夏农垦抓改革、促发展、调结构、惠民生，创造了许多新记录，一组亮丽的数字彰显出“十二五”的开门红：清收土地5．39万亩，取得了阶段性成果；成功发行18亿元公司债券，成为全区、全国农垦发行额度最大的一支农业企业公司债券；
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家畜遗传评定方法研究进展王新亮摘要：家畜遗传评定是家畜育种的重要内容。

目前家畜遗传评定方法中应用最广的是基于表型信息的BLUP动物模型。

基因组学的发展和应用产生了大量分子遗传标记,结合分子遗传标记信息的遗传评定方法MBLUP随之产生.MBLUP将成为一种快速有效的家畜遗传评定方法。

本文着重介绍家畜遗传评定方法的研究进展和发展趋势.关键词:遗传评定;BLUP；MBLUP;分子遗传标记信息.一般而言,遗传性能越优秀的个体种用价值越高.家畜遗传评定即评估家畜种用价值的高低,遗传评定即评估家畜种用价值的高低,是家畜育种工作的中心任务。

家畜种用价值的高低通常用育种值的大小衡量，因为在影响性状表型的三种主要遗传效应，即加性效应、显性效应和上位效应中，只有加性效应值即育种值能够稳定遗传给后代。

因育种值无法直接测量，只能通过一定的统计学方法加以估计，所以遗传评定的实质内容就是育种值的估计.家畜的估计育种值是选择种家畜的主要依据,育种值估计的精确与否在很大程度上影响着家畜育种效果的好坏.近半个世纪以来，育种值估计方法在不断改进和发展，概括起来主要有选择指数法、群体比较法、最佳线性无偏预测法和标记辅助法等四种。

目前，以BLUP法应用最广，但其信息来源主要是表型和系谱记录的成绩，由于收集这些信息花时较长,致使遗传评定结果常常滞后于育种需求。

MBLUP法结合了表型和分子遗传标记两方面的信息,能尽早从分子水平对产生个体问表型差异的原因进行精细地剖分,不但增加了遗传评定的可靠性而且提高了家畜遗传评定的效率,在家畜育种中显示出了巨大的应用潜力。

本文主要就家畜遗传评定方法的研究进展及今后的发展趋势作一概述。

l选择指数法选择指数法是利用一切现有表型资料，包括本身、同胞、祖先和后裔的表型信息经适当加权后构成一个供选择的指数的育种值估计方法该法由Lush和Wright于1931年从植物育种中引入，并由Hazel 于1943年应用到动物育种实践中。

这是育种值估计的初级阶段，选择指数法主要包括合并选择指数法和综合选择指数法两种，目前国内一些小型农场还在使用这类方法.但是，选择指数法在实际应用中受到许多因素制约：要求表型观测值来源于同一总体，即待估种畜及其后代必须处于同一环境；需要有事先估计好的遗传参数；必须使用矫正过的观测值进行育种值估计。

2群体比较法随着人工授精技术的广泛应用,公畜的后代常常分布于不同的群体中，而不同的环境会影响性状的表现。

为校正环境差异对性状的影响,人们先后提出了多种群体比较方法用于育种值估计，主要包括:同群比较法、同期同龄女儿比较法、预测差值法、以及新近提出的测定日模型法等.目前这些方法主要用于奶牛育种工作中.3BLUP方法1949年,Henderson提出处理不均衡资料的混合模型方程组方法，并于1966年将该法应用于动物育种值估计中，形成了BLUP方法。

BIUP法将选择指数法和最小二乘估计方法有机结合起来，解决了选择指数法存在的问题.BLUP法可以在同一个混合模型方程组中，既估计出固定的环境效应和遗传效应，又预测出随机的遗传效应。

其中，固定的遗传效应和随机的遗传效应之和即估计育种值。

BLUP法具有估计值无偏、估计值方差最小、可消除因选择和淘汰等原因造成的偏差等特性，获得的个体育种值具有最佳线性无偏性，精确性较高，是当今世界范围内主要的种畜遗传评定方法.畜禽的重要经济性状大多为数量性状_.来自果蝇等模式动物的研究发现,绝大部分数量性状除受许多遗传效应较小的微效多基因作用外，还受一部分有中等遗传效应的基因和少数遗传效应较大的主基因或数量性状座位)的共同作用。

基于此，VanVern—dunk等将BLUP所用的模型划分为多基因模型和混合遗传模型两类。

3．1多基因模型多基因模型假定数量性状的遗传变异受微效多基因控制,个体育种值通常根据祖先和后代共有的、可确实遗传的基因加性效应来估计。

目前所用的畜禽育种值估计方法基本上均为多基因模型,如公畜模型、公畜一母畜模型、外祖父模型以及动物模型等，模型中的随机遗传效应分别对应于公畜效应、公畜一母畜效应、公畜～外祖父效应、个体加性效应等。

其中,以动物模型估计的育种值较为精确,在畜禽育种中广为应用。

动物模型为：Y=Xb+Za+e。

式中，Y为观察值向量；B为固定效应向量;a为随机的加性遗传效应(即育种值)向量；e为随机残差向量；X、z分别是与固定效应和加性遗传效应对应的关联矩阵。

3．2混合遗传模型当数量性状除受微效多基因作用外，还受到较大效应的主基因作用时，多基因模型发展为混合遗传模型。

混合遗传模型为：Y=Xb+Z“+e(1)其中Y为观察值向量,b为未知固定向量,“为未知随机向量,x和z分别为已知固定因子b和随机因子“的关联矩阵，e为随机剩余效应向量.且“E(Y)=Xb，E（“)：0，E（e）=0Var()=G，Var（e）：R，Cov（,e’）=0Var(Y）=ZGZ’+R=V，Cov（Y，’）=ZG,Cov（Y，e'、=R”需要对该模型中的固定效应b和“随机效应进行估计，对随机效应“的估计也称为预测。

4MBLUP方法针对BLUP方法存在的不足,人们又在探索新的育种值估计方法。

二十世纪九十年代以来,随着基因组学及相应分子生物学技术的快速发展和应用，涌现了大量分子遗传标记.研究者们将分子遗传标记提供的信息引入到BLUP方法中,形成了标记辅助BLUP(MBLUP）方法。

MBLUP法将表型信息和分子遗传标记信息有机结合起来，从分子水平对产生个体间表型差异的原因进行精细剖分。

由于分子遗传标记具有多态性丰富、检测效率高，且不受性别、年龄限制等优点，因此MBLUP 法在改善和提高畜禽遗传评定效率和准确性方面，尤其是对限性性状、低遗传力性状及难以度量性状的遗传评定上具有较大优势'“]。

分子遗传标记信息主要通过3个途径提高家畜遗传评定的准确性。

4．1利用主基因效应目前已检测到一些影响动物数量性状的主基因，在育种值估计模型中将这些主基因效应合并起来作为固定遗传效应，可提高育种值估计的准确性。

例如猪的雌激素受体基因、氟烷敏感基因、牛的双肌基因、鸡的矮小基因等，已逐步用于畜禽遗传评定工作中。

4．2标记辅助动物模型研究发现,虽然大部分遗传标记并非数量性状座位(QTL）本身,却很可能与某个QT连锁。

当QTI与遗传标记紧密连锁时．称之为标记连锁的QTL，如下图所示：堂M,P、M7丽指个体i的遗传标记的两个等位基因，分别南个体i的父亲和母亲传递下来。

指与M、M连锁的MQTL的两个等位基因。

通过遗传标记提供的基因型信息可以反映与该标记连锁的MQTL由亲代传递到子代的途径并预测其加性配子效应。

组成个体基因型的双亲配子的遗传贡献之和即该个体的育种值，通常将双亲配子的遗传贡献剖分为多基因的加性遗传效应和MQTL的加性配子效应。

其中，多基因的加性遗传效应可从系谱中观测到，MQTL的加性配子效应则可通过遗传标记预测。

基于此原理，Fernado等和VanArendonk等先后完善了标记辅助动物模型，该模型可同时估计固定效应、多基因的加性遗传效应以及MQTL的加性配子效应等［13，14］.当只考虑一个QTL与一个标记座位连锁的情况时,标记辅助动物模型为:Y=X口+Z“+wv+e。

式中，Y为性状的观察值向量；口为固定效应向量；U为随机的多基因加性效应向量;v为MQTL 的随机加性配子效应向量；e为随机残差向量;X、Z、W分别是与口、U、v相对应的关联矩阵.当一个QTL与多个标记座位连锁,或同时考虑多个MQTL时，模型要进行相应的变化.然而，这种标记辅助动物模型也存在不足之处，它只适于整个家畜均进行过分子标记检测的情况，当畜群中含有部分未经检测的个体时，计算起来十分复杂。

但目前分子标记的检测费用过高，大规模的检测工作不宜开展.为解决这一问题，Bink等提出一种利用与QTL连锁的单标记信息进行的标记辅助遗传评定方法。

该法通过简化动物模型可以吸收未经标记鉴定的个体遗传效应，既节省了检测费用,又简化了计算。

4．3基因组模型目前家畜遗传评定方法所依据的遗传信息主要是常染色体上呈孟德尔遗传的基因。

随着基因组研究的深入，人们又发现了配子印迹基因和性连锁基因等一系列呈非孟德尔遗传的基因。

例如，Nezer等(1999)、Jeon等（1999)研究发现，猪的第2号染色体上IGF-2座位附近的印迹基因影响肌肉的丰满度及脂肪的沉积量.基因组模型通过呈孟德尔遗传的常染色体基因,以及呈非孟德尔遗传的母系印迹基因、父系印迹基因和性连锁基因等四类基因的遗传效应，将目前获得的遗传信息应用于遗传评定中，可以较为准确地估计育种值。

综上所述，家畜遗传评定方法从最初的选择指数法、群体比较法到目前广为应用的BLUP法以及成为当前研究热点的MBLUP法，经历了一个不断改进和发展的过程。

综观家畜遗传评定方法的发展和现状，可以看出，动物遗传学理论、统计学方法、计算机模拟方法、基因组学及相应分子生物技术等理论和技术的发展及相互渗透，对遗传评定方法的发展起到了极为重要的推动作用。

可以预见的是，MBLUP 将成为一种重要的家畜遗传评定方法。

但是，到目前为止，MBLUP法仍处于理论探索和实验研究阶段,虽然已有少数分子遗传标记信息在家畜育种中得到应用，但涉及的范围还相当有限。

分析起来,限制MBLUP法应用于育种实践的因素可能主要与分子遗传标记的检测费用较高、与重要性状紧密连锁的分子标记较少等有很大关系。

家畜遗传评定的进一步工作，除加快MBLUP法相关的研究外,还应把现有的研究成果尽早应用于育种实践，亟待解决和改进的问题主要有：(1）遗传评定模型要适于现有的畜群结构;(2）遗传评定结果应与种畜选择方案有机结合，使家畜育种产生长期的遗传进展。

参考文献：（1)吴丽丽刘学洪动物科学与动物医学-2003年11期（2）俞英张沅遗传—2003年5期。