Large-Amplitude Ultraviolet Variations in the RR Lyrae Star ROTSE-I J143753.84+345924.8

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High power pulsed magnetron sputtering A review on scientific and engineering state of the art

High power pulsed magnetron sputtering:A review on scienti ﬁc and engineering state of the artK.Sarakinos a ,⁎,1,J.Alami b ,1,S.Konstantinidis c ,1a Materials Chemistry,RWTH Aachen University,52074Aachen,Germanyb Sulzer Metaplas GmbH,Am Böttcherberg 30-38,51427,Bergisch Gladbach,GermanycLaboratoire de Chimie Inorganique et Analytique,Universitéde Mons,Avenue Copernic 1,7000Mons,Belgiuma b s t r a c ta r t i c l e i n f o Article history:Received 31March 2009Accepted in revised form 6November 2009Available online 19January 2010Keywords:HPPMS HiPIMSIonized PVDHigh power pulsed magnetron sputtering (HPPMS)is an emerging technology that has gained substantial interest among academics and industrials alike.HPPMS,also known as HIPIMS (high power impulse magnetron sputtering),is a physical vapor deposition technique in which the power is applied to the target in pulses of low duty cycle (b 10%)and frequency (b 10kHz)leading to pulse target power densities of several kW cm −2.This mode of operation results in generation of ultra-dense plasmas with unique properties,such as a high degree of ionization of the sputtered atoms and an off-normal transport of ionized species,with respect to the target.These features make possible the deposition of dense and smooth coatings on complex-shaped substrates,and provide new and added parameters to control the deposition process,tailor the properties and optimize the performance of elemental and compound ﬁlms.©2009Elsevier B.V.All rights reserved.Contents 1.Introduction ..............................................................16622.HPPMS:power supplies and processes .................................................16623.Plasma dynamics in HPPMS ......................................................16643.1.On the HPPMS plasma .....................................................16643.2.Determination of plasma properties:a theoretical overview ....................................16653.3.The HPPMS plasma properties ..................................................16663.3.1.The effect of the pulse on/off time con ﬁguration on the plasma properties .........................16683.3.2.Rarefaction in the HPPMS plasma ............................................16693.4.Instabilities in the HPPMS plasma ................................................16713.4.1.Plasma instabilities:an overview ............................................16713.4.2.Plasma initiation and the relationship between plasma instabilities and the chargetransport in the HPPMS plasma .....16714.Plasma-surface interactions and deposition rate .............................................16734.1.Non-reactive HPPMS ......................................................16734.1.1.Target-plasma interactions and target erosion rate ....................................16734.1.2.Transport of ionized sputtered species ..........................................16754.2.Reactive HPPMS ........................................................16755.Growth of thin ﬁlms by HPPMS ....................................................16765.1.HPPMS use for deposition on complex-shaped substrates .....................................16765.2.Interface engineering by HPPMS .................................................16775.3.The effect of HPPMS on the ﬁlm microstructure .........................................16785.4.Phase composition tailoring of ﬁlms deposited using HPPMS ...................................16796.Towards the industrialization of HPPMS ................................................16816.1.Examples of industrially relevant coatings by HPPMS .................................. (1681)Surface &Coatings Technology 204(2010)1661–1684⁎Corresponding author.Tel.:+492418025974,+492204299390,+3265554956.E-mail address:sarakinos@mch.rwth-aachen.de (K.Sarakinos).1All authors have contributed equally to the preparation of themanuscript.0257-8972/$–see front matter ©2009Elsevier B.V.All rights reserved.doi:10.1016/j.surfcoat.2009.11.013Contents lists available at ScienceDirectSurface &Coatings Technologyj o u r n a l h om e p a g e :w w w.e l s ev i e r.c o m /l o c a t e /s u r fc o a t6.2.Up-scaling of the HPPMS process (1682)6.3.Positioning HPPMS in the coating and components market (1682)Acknowledgements (1682)References (1682)1.IntroductionThinﬁlms are used in diverse technological applications,such as surface protection and decoration,data storage,and optical and microelectronic devices.The increasing demand for new functional ﬁlms has been a strong incentive for research towards not only understanding the fundamentals and technical aspects of thinﬁlm growth,but also developing new deposition techniques which allow for a better control of the deposition process.Among the various methods employed forﬁlm growth,Physical Vapor Deposition(PVD)techniques, such as magnetron sputtering,are widely used[1].Magnetron sputtering is a plasma-based technique,in which inert gas(commonly Ar)atoms are ionized and accelerated as a result of the potential difference between the negatively biased target(cathode)and anode.The interactions of the ions with the target surface cause ejection(sputtering)of atoms which condensate on a substrate and form aﬁlm[1,2].The condensation and ﬁlm growth processes frequently occur far from the thermodynamic equilibrium,due to kinetic restrictions[2,3].Thus,a good control of both the thermodynamic and the kinetic conditions has implications on the growth dynamics and enables the tailoring of the structural,optical, electrical,and mechanical properties of theﬁlms[4].One way to control the growth dynamics is by heating the substrate during the deposition [2].The magnitude of the deposition temperature affects the energy transferred to theﬁlm forming species(adatoms)[2].This energy is,for instance,decisive for the activation of surface and bulk diffusion processes[5,6]and enables control over theﬁlm morphology[7–10]. Another source of energy are the plasma particles that impinge onto the growingﬁlm transferring energy and momentum to the adatoms[4,5]. The bombardingﬂux consists both of neutral and charged gas particles,as well as sputtered species.Numerous studies have shown that the energy, theﬂux,the angle of incidence,and the nature of the bombarding species are of importance for the properties of the depositedﬁlms[4,5,11,12].In general,the plasma particles exhibit a relatively broad energy distribu-tion with a mean value of several eV[13].The particle energy,andﬂux are affected by the target-to-substrate distance and the working pressure[1]. When the particles are charged the control of their energy can additionally be achieved by the use of electricﬁelds,e.g.by applying a bias voltage to the substrate[4,14],while theirﬂux depends on a number of factors including the plasma density,the target power,and the magneticﬁeld conﬁguration at the target[4,14].It is therefore evident, that a high ion fraction in a depositingﬂux facilitates a more efﬁcient and accurate control of the bombardment conditions providing,thus,added means for the tuning of theﬁlm properties.In magnetron sputtering processes the degree of ionization of the plasma particles is relatively low[13],resulting in a low total ionﬂux towards the growingﬁlm[13].As a consequence,in many cases bias voltage values of several tenths or even hundreds of V are required in order to increase the average energy provided to the deposited atoms and signiﬁcantly affect theﬁlm properties[5].Moreover,the degree of ionization of sputtered species is typically less than1%[13,15,16].As a result,the majority of the charged bombarding particles is made of Ar+ions[13].This fact in combination with the relatively high bias voltages may cause subplantation of the Ar atoms in theﬁlm[17,18], leading to a generation of lattice defects,[18,19]high residual stresses [20–23],a deterioration of the quality of theﬁlm/substrate interface [21],and a poorﬁlm adhesion[24].Thus,the increase of the fraction of the ionized sputtered species has been an objective of many research works during the recent decades.Some of the approaches that have been demonstrated include the use of an inductively coupled plasma (ICP)superimposed on a magnetron plasma[25],the use of a hollow cathode magnetron[25],and the use of an external ion source[26]. Parallel to the above mentioned approaches Mozgrin et al.[27], Bugaev et al.[28]and Fetisov et al.[29]demonstrated in the mid90s that the operation of a conventional sputtering source in a pulsed mode,with a pulse duration ranging from1µs to1s and a frequency less than1kHz,allowed for pulsed target currents two orders of magnitude higher than the average target current in a conventional sputtering technique,such as direct current magnetron sputtering (dcMS)[27–29].These high pulse currents resulted,in turn,in ultra-dense plasmas with electron densities in the order of1018m−3[27–29],which are much higher than the values of1014–1016m−3 commonly obtained for dcMS[13,30].A few years later,Kouznetsov et al.[31]demonstrated in a publication,that received much acclaim,the high power pulsed operation of the sputtered target showing that in the case of Cu the high plasma densities obtained using this pulsed technique resulted in a total ionﬂux two orders of magnitude higher than that of a dcMS plasma,and a sputtered material ionization of ∼70%.The new deposition technique was called High Power Pulsed Magnetron Sputtering(HPPMS).In the years after Kouzsetov's report, HPPMS received extensive interest from researchers and led to a substantial increase of the HPPMS-related publications(Fig.1).Later, several research groups[25]adopted the alternative name High Power Impulse Magnetron Sputtering(HiPIMS)for this technique.The aim of this review paper is to describe the scientiﬁc and engineering state of the art of HPPMS.For this purpose,the principle and the basic structure of the existing HPPMS power supplies are described and the various existing approaches to produce high power pulses are demonstrated.The spatial and the temporal evolution of the HPPMS plasma and its interactions with the target and the growingﬁlm are discussed both from a theoretical and an experi-mental perspective.Furthermore,the effect of the HPPMS operation on the deposition rate and theﬁlm properties is presented.Finally,the use of HPPMS in industry and the challenges that the latter faces regarding the use of HPPMS are brieﬂy addressed.2.HPPMS:power supplies and processesThe experimental realization of HPPMS requires power supplies different than those used in conventional magnetron sputtering processes. Those power supplies must be able to provide the target with pulses of high power density(typically in the range of a few kW cm−2),while maintaining the time-averaged target power density in values similarto Fig.1.Number of HPPMS-related publications in the period1999–2008.1662K.Sarakinos et al./Surface&Coatings Technology204(2010)1661–1684those during dcMS (i.e.a few W cm −2).The low average target power density is necessary to prevent overheating of the cathode and damage of the magnets and the target.A number of research groups and companies have developed HPPMS arrangements for both laboratorial and industrial use.These devices exhibit similarities in their basic structure which is schematically depicted in Fig.2.A dc generator is used to load the capacitor bank of a pulsing unit,which is connected to the magnetron.The charging voltage of the capacitor bank ranges typically from several hundreds of V up to several kV.The stored energy is released in pulses of de ﬁned width and frequency using transistors with a switching capability in the µs range,located between the capacitors and the cathode.The pulse width (also referred to as pulse on-time)ranges,typically,from 5to 5000µs,while the pulse repetition frequency spans from 10Hz to 10kHz.Under these conditions,the peak target current density may reach values of up to several Acm −2,which are up to 3orders of magnitude higher than the current densities in dcMS [25].The high target current densities during the pulse on-time are accompanied by differences in the electrical characteristics of the discharge,as manifested by the current –voltage (I –V )curves of a magnetron operating in a dcMS and an HPPMS mode (Fig.3).According to Thornton [32]the target and the voltage of the magnetron are linked by the power law I ∝Vnð1ÞIn dcMS processes the exponent n in Eq.(1)ranges from 5up to 15(Fig.3).In HPPMS the exponent n changes from values similar to dcMS at low target voltages to values close to the unity when high voltages are applied (Fig.3)[33,34].Despite their common basic architecture,the available HPPMS power supplies exhibit differences primarily in the width and the shape of the pulses they can deliver,and in whether they can sustain a constant voltage during the pulse on-time.Arrangements able to provide high power pulses were already developed in the mid 90s,in order to explore the feasibility of producing high-current quasi-stationary magnetron glow discharges for high rate deposition [27–29].However,it was in 1999when Kouznetsov et al.[31]emphasizedthat the high power pulsing could allow for a high ionization degree of copper vapor (70%)as well as a homogeneous ﬁlling of 1:2aspect ratio trenches (see Fig.4).The time-dependent target current and target voltage curves of the HPPMS power supply developed by Kouznetsov et al.[31]are plotted in Fig.5where it is shown that the ignition of the plasma is accompanied by a drop of the voltage from ∼1000V to ∼800V,as the current increases to its peak value ranging from 200to 230A at the highest applied working pressure [35,36].A characteristic of this power supply is that the loading voltage is not maintained constant during the pulse on-time,and its temporal evolution is rather determined by the size of the capacitor bank and the time-dependent plasma impedance.Other power generators were designed to deliver voltage pulses with a rectangular shape (see Fig.6),i.e.a constant voltage value during the pulse on-time [34,37–39].It is to be noted that pulses with widths larger than about 50µs allow for a saturation of the discharge current and establishment of a steady-state plasma [40]provided that enough energy is stored in the capacitor bank.A common problem encountered in sputtering processes is the occurrence of arcs.This phenomenon is particularly pronounced during the deposition from conducting targets covered by insulating layers and can be detrimental for the quality of the ﬁlms,due to the ejection of µm sized droplets from the target [41,42].The high peak target currents during the HPPMS operation may enhance the frequency of the arc events [43].Therefore,sophisticated electronics can be used in conjunction with the HPPMS power supplies to limit their effect if formed [43].An alternative way to alleviate this problem is to operate HPPMS using short pulses with widths ranging from 5to 20µs [44].A waveform during this mode of operation is presented in Fig.7.Within this short period of time,the glow discharge remains in a transient regime [40](as manifested by the triangular form of the target current)so that an eventual glow-to-arc transition is prevented.These short pulses have been,for instance,shown to allow for a stable and an arc-free reactive deposition of metal oxide ﬁlms [45,46].However,in order to eliminate the time lag for plasma ignition which would allow for the production of high-current pulses within this short period of time,a pre-ionization stage has to be implemented [44,47].The pre-ionization of the discharge ensures that a low density plasma is maintained between the pulses as the charge carriers are already present before the voltage is turned on.The plasma pre-ionization step may be achieved by super-imposing a secondary plasma (such as a dc,a microwave,or an inductively coupled plasma)on the HPPMS plasma or by running the discharge at relatively high frequencies [44,47–49].The latter pre-ionization method is extensively implemented in mid-frequency pulsed plasmas [50–53].In contrast to the short pulses described above,long pulses with a width of several thousands of µs can also be used [54](Fig.8).In this case the pulse is composed of two (or more)stages.TheFig.2.Basic architecture of an HPPMS power supply.The dc generator charges the capacitor bank of a pulsing unit.The energy stored in the capacitors is dissipated into the plasma in pulses of well-de ﬁned width and frequency using ultra fastswitches.Fig.3.Current –voltage curves of a magnetron during operation in dcMS and HPPMS mode.The change of the slope from 7to 1at a voltage value of 650V indicates loss of the electron con ﬁnement (data taken from [33]).Fig. 4.Cross-section SEM image of two via holes with an aspect ratio 1:2homogeneously ﬁlled by Cu using HPPMS (reprinted from [31]after permission,1999©Elsevier).1663K.Sarakinos et al./Surface &Coatings Technology 204(2010)1661–1684ﬁrst step of the discharge is made of a weakly ionized regime,while the second part of the pulse brings the glow discharge to the high ionization state.The weakly ionized regime allows for the formation of a stable discharge prior to entering the highly ionized regime which helps to suppress the arc formation during the high power mode of operation [54].3.Plasma dynamics in HPPMS 3.1.On the HPPMS plasmaPlasmas are partially ionized gases characterized by,for example,the charge (electron)density or the electron energy distribution function [55].A classi ﬁcation of different plasmas could be based on the charge density as shown in Fig.9,where the magnetron sputtering plasmas are shown to exhibit densities ranging from ∼1014up to 1020m −3.It is known that high density plasmas such as arc plasmas exhibit high ionization fractions [25,31].This is not the case for conventional magnetron plasmas where the electron density does not exceed the value of 1016m −3,penning ionization is the main ionization mechanism [30]and therefore the ionization of the sputtered species is at the best of few percent [13].In order to achieve a high ion fraction in a discharge it is necessary to promote the electron impact ionization [55]which is best realized by increasing the electron density and temperature.Different approaches have been made to achieve this,for example by using an electron cyclotron resonance (ECR)plasma as a plasma electron source [56],or by employing an inductively coupled plasma (ICP)[57,58].A higher frequency of electron impact ionization collisions can alsobeFig.5.Target current and voltage waveforms produced by the power supply developed by Kouznetsov et al.at working pressures of (a)0.06Pa,(b)0.26Pa,(c)1.33Pa and (d)2.66Pa.The charging voltage of 1000V drops down to 800V and the plasma is ignited.Peak target currents of up to 230A are achieved.The time lag for the ignition of the plasma decreases when the pressure is increased (reprinted from [35]after permission,2002©Elsevier).Fig.6.Rectangular shape voltage waveforms generated by the HPPMS power supply developed by MELEC GmbH.The data were recorded from an Ar –Al HPPMS discharge operating at pulse on/off time con ﬁguration 25/475µs (K.Sarakinos,unpublisheddata).Fig.7.Temporal evolution of target voltage and current during operation using a 10µs long pulse.The target current is interrupted before the plasma enters into the steady-state regime.The data were recorded from an Ar –Ti HPPMS discharge (S.Konstantinidis unpublished data).1664K.Sarakinos et al./Surface &Coatings Technology 204(2010)1661–1684achieved by increasing the power to the sputter source and therewith the electron density.This approach is,however,limited since a power excess can result in an overheating of the target or an exceeding of the Curie temperature of the magnetron's magnets.Thus,the work of Kouznetsov et al.[31]opened a new era of magnetron sputtering deposition and plasma studies,since it allowed for the generation of highly ionized plasmas using a conventional magnetron source.The early analyses of the HPPMS plasma showed that its temporal characteristics are complex and unique [35,59,60].Understanding the discharge evolution and the mechanisms that take place in the plasma is therefore of utmost importance as this sheds light on the growth conditions during the thin ﬁlm deposition.To achieve this,modeling and a number of analytical studies have been carried out,using Langmuir probes as well as optical emission,mass,and absorption spectroscopy techniques.These studies are reviewed in the following chapters and the basic properties of the HPPMS plasma are thus outlined.3.2.Determination of plasma properties:a theoretical overview Plasmas are commonly modeled as ﬂuids,and each species is described with its ﬂuid equation [61].The ﬂuid approximation is suf ﬁciently accurate to describe the majority of observed plasma phenomena.When this is not viable,the accumulated behavior of anensemble of charged particles is described using a statistical approach,in the form of the velocity distribution function which is given as f (r,u,t )d 3r d 3u ,i.e.the number of particles inside a six-dimensional phase space volume d 3r d 3u at (r ,u )and time t [55].Here,r is the position vector and u is the speed vector.Knowing the distribution function,fundamental features of a large ensemble can be quanti ﬁed,i.e.by integrating over the velocity,the average (macroscopic)quantities associated with the plasma are de ﬁned as:n ðr ;t Þ=∫f ðr ;u ;t Þd u plasmanumber ðion ;electron ;orneutral Þdensityð2Þu Àðr ;t Þ=1n∫u f ðr ;u ;t Þd u plasmabulkfluid velocity ð3ÞεÀðr ;t Þ=m 2n∫ðu À−u Þ2f ðr ;u ;t Þd u plasmameankineticenergy ð4Þwhere m is the particle (ion,electron,or neutral)mass.This procedure of integrating over velocity space is referred to as taking velocity moments,with each one yielding a physically signi ﬁcant quantity.Knowledge of the electron energy (velocity)distribution function (EEDF)permits us to determine important parameters.The EEDF can be measured using a Langmuir probe,as was demonstrated by Druyvesteyn [55]:g e ðV Þ=2m e A pr 2eV m12d 2I edV ð5Þwhere A pr is the probe area,I e is the electron current,m is the electronmass,and V =V pl −V b is the potential difference between the plasma potential and the probe potential.With the change of variables ε=eV ,the electron density n e is determined as:n e =∫∞0g e ðεÞd εð6ÞPlasma parameters,such as the electron density,are easily obtained if the mathematical description of the EEDF is Maxwellian.The Maxwellian distribution is characterized by its single temperature and is obtained when plasma electrons undergo enough collisions and are in equilibrium with other plasma components and with the electron ensemble itself.At a low pressure,the EEDF is generally non-Maxwellian,and the electron temperature is thought of as aneffectiveFig.8.Target voltage and current waveforms during the long-pulse operation.In the ﬁrst 500µs a weakly ionized plasma is generated which is followed by a highly ionized steady-state plasma (reprinted from [54]after permission,Society of Vacuum Coaters ©2007).Fig.9.Plasma density is used in order to classify plasmas.The HPPMS plasma spans over a large density range depending on the pulse on/off time con ﬁguration used for a process and presents therefore a tool for better choosing the plasma dynamics needed for the deposition process.The abbreviation ECR stands for Electron Cyclotron Resonance (taken from [36]).1665K.Sarakinos et al./Surface &Coatings Technology 204(2010)1661–1684electron temperature,T eff∼23〈ε〉,representing the mean electron energy determined from the EEDF according to[55]:〈ε〉=1n e ∫∞εg eðεÞdεð7Þ3.3.The HPPMS plasma propertiesOne of the earliest works related to the study of the properties of the HPPMS plasma was carried out by Gudmundsson et al.[35,59]. Using a Langmuir probe[62]in an Ar–Ta plasma,they measured the temporal behavior of the EEDF by recording the time-dependent probe current curves.It was shown that the EEDF evolved from a Druyvesteyn-like distribution with a broad energy distribution(high average energy)during the pulse to a double Maxwellian distribution (i.e.a distribution that is composed of two-distinct energy-distribu-tions)toward the end of the pulse,andﬁnally a Maxwellian-like distribution hundreds ofµs after the pulse had been switched off.This is shown in Fig.10,where the temporal evolution of the EEDF is also seen to be affected by the working pressure[35].Similar results were obtained by Pajdarova et al.[63],although the double Maxwellian distribution was observed from the beginning of the pulse,which could be explained by the nature of the target material(Cu in this case)and the HPPMS parameters used in the experiments.Further-more,it was found that the effective electron temperature peaked a fewµs after the pulse start,and at the same time,independent of measurement position[35].This is indicative of the existence of high energy electrons accelerated by the target voltage,and thus escaping the conﬁnement region in the vicinity of the cathode[35].InaFig.10.The EEDF(electron energy distribution function)for an HPPMS plasma with a100µs on-time and a50Hz frequency at three chamber pressures(a)0.25,(b)1.33,and(c) 2.66Pa.The distribution function changes during the pulse from a Druvesteyn distribution to a double-Maxwellian distribution(reprinted from[35]after permission,Elsevier©2002).1666K.Sarakinos et al./Surface&Coatings Technology204(2010)1661–1684different study by Seo et al.[64],Langmuir probes were utilized to determine the properties of a HPPMS plasma at a higher pulsing frequency of 10kHz and a duty cycle of 10%.By using such a high frequency,the electron density reached a value of 1.5×1017m −3,which could be seen as a relatively low density HPPMS plasma.The temporal evolution of the energy distribution in this plasma showed ef ﬁcient electron heating,which took place within the ﬁrst few µs from the pulse start.This work revealed that the plasma dynamics presented in the studies by Gudmundsson et al.[35,59]are to a large extent general features of the low duty cycle pulsed plasmas regardless of the frequency.The early studies on the HPPMS plasma characteristics also showed the potentially high ionization fraction of the sputtered material that could be achieved by using this technique [16,25,33,60,65,66].Spectroscopic analyses,such as optical emission spectroscopy [67–69],mass spectroscopy [69],and absorption spectroscopy [68,69]were,therefore,employed in order to better quantify and understand the average and time-dependent evolution of the ion population in the HPPMS plasma.The optical emission studies [33,65,70–72],were performed both for the HPPMS and the dcMS discharges and showed the much higher metal ion emission intensity in HPPMS (Fig.11).However,in order to better quantify these observations,absorption spectroscopy [70,71,73,74]and mass spectroscopy [75,76]studies were performed,con ﬁrming the much higher ionization of the sputtered material and of the sputtering gas achieved in HPPMS.One well studied material in this regard is Ti.Mass spectroscopy measurements of the peak ion compositions in an Ar –Ti discharge for the pulse on-time of 100µs and a frequency of 50Hz [75]showed that the ionized part of the plasma contained 50%of Ti 1+,24%of Ti 2+,23%of Ar 1+,and 3%of Ar 2+ions.When longer pulse on-times of several hundreds of µs were used even Ti 3+and Ti 4+could also be detected [77].It is deduced that for the formation of multiply charged ions certain conditions should be ful ﬁlled [77];(i)the discharge should contain a high enough number of metal ions,(ii)the pulse on-time should be long enough (and the capacitance of the used power supply should be large enough to store enough energy for the whole pulse),(iii)the self-sputtering yield (i.e.the sputtering yield of the target material from ionized target species)should be low,and (iv)the ionization energy of each ionization step should not be too high.These two examples show clearly that the HPPMS plasma properties depend not only on the plasma density and energy distribution but also,to a large degree,on the pulse on/off time con ﬁguration.Since the introduction of the HPPMS technique,most of the discharge studies have been performed for pulses with pulses on-time longer than 50µs.Exceptions to this can be found in the works by Konstantinidis et al.[70,73],Ganciu et al.[44],and Vasina et al.[48],where shorter pulses ranging between 5and 30µs have been used,an example of which is shown in ing time-resolved optical emission spectroscopy in a Ti –Ar discharge,an increase in the line intensity ratio of the ion-to-neutral Ti and Ar species with increasing the pulse duration was observed [70].This means that the ionization degree increases with increasing pulse length,indicating the necessity for the sputtered atoms to reside a suf ﬁcient time in the target vicinity for the vapor to become ionized.The increase of the AremissionFig.11.Optical emission spectroscopy from a typical HPPMS plasma.The emission from the Ti and Ar species increases greatly in HPPMS indicating the high ionization of the metal and gas species (data taken from [72]).Fig.10(continued ).1667K.Sarakinos et al./Surface &Coatings Technology 204(2010)1661–1684。

不同预处理对热风干燥山药片品质特性及微观结构的影响

谭宏渊，凌玉钊，黄丽琪，等. 不同预处理对热风干燥山药片品质特性及微观结构的影响[J]. 食品工业科技，2023，44（20）：43−52.doi: 10.13386/j.issn1002-0306.2022110328TAN Hongyuan, LING Yuzhao, HUANG Liqi, et al. Effects of Different Pretreatment on the Quality Characteristics and Microstructure of Hot Air Dried Yam Slices[J]. Science and Technology of Food Industry, 2023, 44(20): 43−52. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022110328· 研究与探讨 ·不同预处理对热风干燥山药片品质特性及微观结构的影响谭宏渊1,2，凌玉钊1,2，黄丽琪1,2，熊光权2，乔　宇2, *，魏凌云1, *（1.武汉工程大学环境生态与生物工程学院，湖北武汉 430205；2.湖北省农业科学院农产品加工与核农技术研究所，湖北武汉 430064）摘　要：为比较不同干燥预处理对山药品质及微观结构的影响，以新鲜山药为原料，采用高压静电场、超高压和冷冻3种方式对切片后的山药进行预处理，利用低场核磁共振技术及干燥特性揭示干燥前后山药片内部的水分状态、分布及含量情况，分析山药片的微观结构、色泽、复水比、纤维素含量等特性的变化。

结果表明，冷冻处理对山药微观结构的破坏虽最为严重，但干燥时间最短，160 min 时水分比即可降为0.1以下；高压静电场预处理对山药片微观结构破坏程度低于其它处理方式，山药中原果胶及纤维素等细胞壁成分含量显著（P <0.05）更高，分别为11.91%和14.65%，且干燥后山药收缩较小，复水比也高于其它方式，为3.53；超高压预处理能够较好地保留山药的风味物质，且使干燥的山药白度值显著（P <0.05）提升，较干燥前提高35.10%。

nanoluc荧光素酶大亚基序列和小亚基专利

NaNoluc荧光素酶是一种蛋白质酶，被广泛用于生物学实验和生物成像领域。

它拥有优异的荧光特性和高度的稳定性，可以被用于研究细胞内、细胞间和动物体内的生物过程。

NaNoluc荧光素酶也被广泛应用于生物医学领域，成为了许多生物医学实验和临床诊断的利器。

在NaNoluc荧光素酶的研究和应用过程中，有两个重要的概念——大亚基序列和小亚基。

这两者对于NaNoluc荧光素酶的结构、功能和特性具有重要作用。

我们来讨论NaNoluc荧光素酶的大亚基序列。

NaNoluc荧光素酶的大亚基序列是指NaNoluc蛋白本身的序列。

NaNoluc荧光素酶的大亚基序列具有多个特点：它拥有较长的氨基酸序列，这使得NaNoluc 荧光素酶具有较大的空间结构和复杂的功能活性；NaNoluc荧光素酶的大亚基序列中可能存在着一些特定的结构域和功能区域，这些区域对于NaNoluc荧光素酶的荧光特性和酶活性具有重要的影响；NaNoluc荧光素酶的大亚基序列可能会存在一些变异和修饰，这些变异和修饰对于NaNoluc荧光素酶的稳定性和特异性也起着关键的作用。

接下来，我们再来探讨NaNoluc荧光素酶的小亚基。

NaNoluc荧光素酶的小亚基是指NaNoluc蛋白与其他辅助蛋白一起组成的复合物中的次要蛋白。

NaNoluc荧光素酶的小亚基具有以下几个特点：它可能不具有酶活性，但可以调节NaNoluc荧光素酶的活性和特性；NaNoluc荧光素酶的小亚基可能通过与NaNoluc蛋白的相互作用，影响NaNoluc荧光素酶的稳定性和定位；NaNoluc荧光素酶的小亚基在生物体内的表达水平和组织特异性也可能对NaNoluc荧光素酶的应用产生影响。

NaNoluc荧光素酶的大亚基序列和小亚基对于NaNoluc荧光素酶的结构、功能和应用有着重要作用。

研究和理解NaNoluc荧光素酶的大亚基序列和小亚基，有助于深入了解NaNoluc荧光素酶的生物学特性和应用潜力。

应用地球化学元素丰度数据手册-原版

应用地球化学元素丰度数据手册迟清华鄢明才编著地质出版社·北京·1内容提要本书汇编了国内外不同研究者提出的火成岩、沉积岩、变质岩、土壤、水系沉积物、泛滥平原沉积物、浅海沉积物和大陆地壳的化学组成与元素丰度，同时列出了勘查地球化学和环境地球化学研究中常用的中国主要地球化学标准物质的标准值，所提供内容均为地球化学工作者所必须了解的各种重要地质介质的地球化学基础数据。

本书供从事地球化学、岩石学、勘查地球化学、生态环境与农业地球化学、地质样品分析测试、矿产勘查、基础地质等领域的研究者阅读，也可供地球科学其它领域的研究者使用。

图书在版编目（CIP）数据应用地球化学元素丰度数据手册/迟清华，鄢明才编著. －北京：地质出版社，2007.12ISBN 978－7－116－05536－0Ⅰ. 应… Ⅱ. ①迟…②鄢…Ⅲ. 地球化学丰度－化学元素－数据－手册Ⅳ. P595－62中国版本图书馆CIP数据核字（2007）第185917号责任编辑：王永奉陈军中责任校对：李玫出版发行：地质出版社社址邮编：北京市海淀区学院路31号，100083电话：（010）82324508（邮购部）网址：电子邮箱：zbs@传真：（010）82310759印刷：北京地大彩印厂开本：889mm×1194mm 1/16印张：10.25字数：260千字印数：1－3000册版次：2007年12月北京第1版•第1次印刷定价：28.00元书号：ISBN 978－7－116－05536－0（如对本书有建议或意见，敬请致电本社；如本社有印装问题，本社负责调换）2关于应用地球化学元素丰度数据手册（代序）地球化学元素丰度数据，即地壳五个圈内多种元素在各种介质、各种尺度内含量的统计数据。

它是应用地球化学研究解决资源与环境问题上重要的资料。

将这些数据资料汇编在一起将使研究人员节省不少查找文献的劳动与时间。

这本小册子就是按照这样的想法编汇的。

分子生物学名词解释

AAbundance(mRNA丰度)：指每个细胞中mRNA分子的数目。

AbundantmRNA(高丰度mRNA)：由少量不同种类mRNA组成，每一种在细胞中出现大量拷贝。

Acceptorsplicingsite(受体剪切位点)：内含子右末端和相邻外显子左末端的边界。

Acentricfragment(无着丝粒片段)：(由打断产生的)染色体无着丝粒片段缺少中心粒，从而在细胞分化中被丢失。

Activesite(活性位点)：蛋白质上一个底物结合的有限区域。

Allele(等位基因)：在染色体上占据给定位点基因的不同形式。

Allelicexclusion(等位基因排斥)：形容在特殊淋巴细胞中只有一个等位基因来表达编码的免疫球蛋白质。

Allostericcontrol(别构调控)：指蛋白质一个位点上的反应能够影响另一个位点活性的能力。

Alu-equivalentfamily(Alu相当序列基因)：哺乳动物基因组上一组序列，它们与人类Alu家族相关。

Alufamily(Alu家族)：人类基因组中一系列分散的相关序列，每个约300bp长。

每个成员其两端有Alu切割位点(名字的由来)。

α-Amanitin(鹅膏覃碱)：是来自毒蘑菇Amanitaphalloides二环八肽，能抑制真核RNA聚合酶，特别是聚合酶II转录。

Ambercodon(琥珀密码子)：核苷酸三联体UAG，引起蛋白质合成终止的三个密码子之一。

Ambermutation(琥珀突变)：指代表蛋白质中氨基酸密码子占据的位点上突变成琥珀密码子的任何DNA改变。

Ambersuppressors(琥珀抑制子)：编码tRNA的基因突变使其反密码子被改变，从而能识别UAG密码子和之前的密码子。

Aminoacyl-tRNA(氨酰-tRNA)：是携带氨基酸的转运RNA，共价连接位在氨基酸的NH2基团和tRNA终止碱基的3￠或者2￠－OH基团上。

Aminoacyl-tRNAsynthetases(氨酰-tRNA合成酶)：催化氨基酸与tRNA3￠或者2￠－OH基团共价连接的酶。

微波场非热效应对巴氏杀菌三文鱼脂质品质的影响

微波场非热效应对巴氏杀菌三文鱼脂质品质的影响张玲1，张莉2，薛倩倩3，栾东磊1*（1.上海海洋大学食品学院，上海 201306；2.通标标准技术服务有限公司，山东青岛266101；3.中国海洋大学食品科学与工程学院，山东青岛 266003）摘要：为探究三文鱼微波巴氏杀菌过程中非热效应是否存在，采用无线温度传感器记录微波处理过程中三文鱼冷热点的时间温度-曲线后，用水浴加热方式分别对微波冷点和热点进行升温曲线的模拟，从上边界和下边界逼近微波冷热点的时间-温度曲线，即采用双向逼近法研究微波场非热效应。

同时研究了微波场非热效应对三文鱼总脂、过氧化值（Peroxide Value，POV）、硫代巴比妥酸值（Thiobarbituric Acid Reactive Substances，TBARs）、酸价（Acid Value，A V）以及脂肪酸组分的影响。

结果显示，微波处理组总脂肪酸含量显著高于两个水浴处理组，在测得的27种脂肪酸组分中有17种脂肪酸组分的提取系数显著高于两个水浴处理组（P＜0.05）。

研究结果表明，微波加热过程中存在非热效应，使得脂质成分更容易被提取，脂肪酸提取系数增加。

本研究可为微波加热过程中非热效应对食品品质的影响提供理论参考和数据支持。

关键词：三文鱼；微波杀菌；非热效应；双向逼近法；脂肪酸组分The Effect of Microwave Field Non Thermal Effect on the Lipid Quality of Pasteurized SalmonZHANG Ling1, ZHANG Li2, XUE Qianqian3, LUAN Donglei1*(1.College of Food Sciences and Technology, Shanghai Ocean University, Shanghai 201306, China; 2.SGS-CSTC Standard Technical Services, Qingdao 266101, China;3.School of Food Science and Technology, Ocean Universityof China, Qingdao 266003, China)Abstract: To explore the existence of non-thermal effects in the salmon microwave pasteurization, the time-temperature curves of salmon cold and hot spots during microwave processing were recorded with a wireless temperature sensor. Then the time-temperature curves of microwave cold and hot spots were simulated by water bath thermal groups, which were approached from the upper and lower boundaries. The Double sides approximate method studied the non-thermal effects of the microwave field. The effects of microwave field non-thermal effects on salmon total fat, peroxide value (POV), thiobarbituric acid reactive substances (TBARs), acid value (AV) and fatty acid components were studied. The results showed that the total fatty acid content of the microwave groups was not between the two water bath groups and the extraction coefficients of 17 fatty acid components among the 27 fatty acid components measured were higher than the two water bath groups (P＜0.05). The results suggested that the non-thermal eﬀects of the microwave heating made the lipid components easier to be extracted, increasing the fatty acids extraction coefficient. This study provides theoretical reference and data support for the eﬀect of non-thermal eﬀects on food quality during microwave therm al.Keywords:salmon; microwave pasteurization; non-thermal eﬀects; double sides approximate method; fatty acid components基金项目：上海市自然科学基金“微波杀菌处理对软包装秋刀鱼脂质组分的影响机制研究”（20ZR1423800）。

制冷型长波红外光学系统设计

制冷型长波红外光学系统设计单秋莎谢梅林刘朝晖陈荣利段晶刘凯姜凯周亮闫佩佩Design of cooled long-wavelength infrared imaging optical systemSHAN Qiu-sha, XIE Mei-lin, LIU Zhao-hui, CHEN Rong-li, DUAN Jing, LIU Kai, JIANG Kai, ZHOU Liang, YAN Pei-pei引用本文:单秋莎,谢梅林,刘朝晖,陈荣利,段晶,刘凯,姜凯,周亮,闫佩佩. 制冷型长波红外光学系统设计[J]. 中国光学, 2022, 15(1): 72-78. doi: 10.37188/CO.2021-0116SHAN Qiu-sha, XIE Mei-lin, LIU Zhao-hui, CHEN Rong-li, DUAN Jing, LIU Kai, JIANG Kai, ZHOU Liang, YAN Pei-pei. Design of cooled long-wavelength infrared imaging optical system[J].Chinese Optics, 2022, 15(1): 72-78. doi: 10.37188/CO.2021-0116在线阅读 View online: https:///10.37188/CO.2021-0116您可能感兴趣的其他文章Articles you may be interested in二次成像型库德式激光通信终端粗跟踪技术Coarse tracking technology of secondary imaging Coude-type laser communication terminal中国光学. 2018, 11(4): 644 https:///10.3788/CO.20181104.0644分孔径红外偏振成像仪光学系统设计Design of decentered aperture-divided optical system of infrared polarization imager中国光学. 2018, 11(1): 92 https:///10.3788/CO.20181101.0092大视场高像质简单光学系统的光学-算法协同设计Optical/algorithmic co-design of large-field high-quality simple optical system中国光学. 2019, 12(5): 1090 https:///10.3788/CO.20191205.1090激光位移传感器传感探头微小型光学系统设计Design of micro-optical system for laser displacement sensor sensing probe中国光学. 2018, 11(6): 1001 https:///10.3788/CO.20181106.1001多角度耦合分幅相机光学系统设计Optical system design of multi-angle coupled framing camera中国光学. 2018, 11(4): 615 https:///10.3788/CO.20181104.0615大相对孔径紫外成像仪光学系统设计Design of large aperture ultraviolet optical system for ultraviolet camera中国光学. 2018, 11(2): 212 https:///10.3788/CO.20181102.0212文章编号 2095-1531（2022）01-0072-07制冷型长波红外光学系统设计单秋莎1,2 *，谢梅林1，刘朝晖1 *，陈荣利1，段　晶1,2，刘　凯1，姜　凯1，周　亮1，闫佩佩1（1. 中国科学院西安光学精密机械研究所，陕西西安 710119；2. 中国科学院大学，北京 100049）摘要：针对640×512长波红外制冷型探测器，设计了一种制冷型长波红外光学系统，用于对目标的红外跟踪探测。

计量经济学中英文词汇对照

Common variance Common variation Communality variance Comparability Comparison of bathes Comparison value Compartment model Compassion Complement of an event Complete association Complete dissociation Complete statistics Completely randomized design Composite event Composite events Concavity Conditional expectation Conditional likelihood Conditional probability Conditionally linear Confidence interval Confidence limit Confidence lower limit Confidence upper limit Confirmatory Factor Analysis Confirmatory research Confounding factor Conjoint Consistency Consistency check Consistent asymptotically normal estimate Consistent estimate Constrained nonlinear regression Constraint Contaminated distribution Contaminated Gausssian Contaminated normal distribution Contamination Contamination model Contingency table Contour Contribution rate Control

Optimization of ultrasonic extraction of Flammulina velutipes polysaccharides and evaluation of its

Optimization of ultrasonic extraction of Flammulina velutipes polysaccharides and evaluation of its acetylcholinesterase inhibitory activityWenjian Yang a ,Yong Fang b ,Jin Liang a ,Qiuhui Hu a ,b ,⁎a College of Food Science and Technology,Nanjing Agricultural University,Weigang,Nanjing 210095,ChinabCollege of Food Science and Engineering,Nanjing University of Finance and Economics,Nanjing,210046,People's Republic of Chinaa b s t r a c ta r t i c l e i n f o Article history:Received 19September 2010Accepted 15November 2010Available online xxxxKeywords:Flammulina velutipes Polysaccharides OptimizationResponse surface methodology Ultrasonic extraction AcetylcholinesterasePolysaccharide was testi ﬁed to be the main component of Flammulina velutipes for inhibiting AChE activity in our preliminary study.Therefore,response surface methodology,based on Box –Behnken design,was used to optimize the ultrasonic extraction conditions of F.velutipes polysaccharides (FVP).Four independent variables (ratio of water to raw material,ultrasonic power,ultrasonic time,and ultrasonic temperature)were taken into consideration.A quadratic model,adequate for reasonably predicting the yield of FVP,was constructed between ultrasonic conditions and yield of FVP.A yield of FVP of 8.33%was obtained under a modi ﬁed condition (ratio of water to material of 25ml/g,ultrasonic power of 620W,ultrasonic time of 20min,and ultrasonic temperature of 45°C).Subsequently,acetylcholinesterase (AChE)inhibitory activity and 1,1-diphenyl-2-picryl hydrazine (DPPH)scavenging activity of FVP were determined.AChE inhibitory rate of 18.51%and DPPH scavenging rate of 61.24%were obtained at 0.6mg/ml of FVP,indicating a good potential of FVP to enhance learning and cognitive ability.©2010Elsevier Ltd.All rights reserved.1.IntroductionNowadays,edible mushrooms are distinguished as important natural resources of immunomodulating and anticancer agents and have been cultured on a large scale in Asia (Wasser,2002).Flammulina velutipes ,one of the most popular edible mushrooms,has attracted considerable attention in the ﬁelds of biochemistry and pharmacology due to its biological activities.Polysaccharides,as one of the important active components of F.velutipes ,have been proved to be bene ﬁcial in immunomodulating antitumor and anti-in ﬂammatory activities (Leung,Fung &Choy,1997).Therefore,much attention has been paid to the studies of F.velutipes polysaccharides (FVP).Although polysaccharides have been well known for their various pharmacological functions,their extraction is still mainly performed with conventional techniques,which are based on proper solvents,prolonging extraction time,heating process,and agitation to increase extraction yield (Wang,Cheng,Mao,Fan &Wu,2009).In these methods,the extraction process usually consumes a long time and a lot of energy,but the extraction ef ﬁciency is very low.Therefore,it is essential and desirable to ﬁnd out an economical and highly ef ﬁcient extraction method.Ultrasonic has been used to increase extraction yield of bioactive substances from natural products,which is mainly attributed to disruption of cell walls,particle-size reduction,and enhanced mass transfer to the cell contents as a result of cavitationbubble collapse (Li,Pordesimo,&Weiss,2004;Vinatoru et al.,1997;Wang et al.,2009).However,there is hardly any report that ultrasonic is applied to separate FVP.Therefore,ultrasonic was employed for the extraction of FVP in our study.Especially,temperature was controlled during the extraction process to prevent overheating-induced oxidation and degradation of polysaccharides.The worldwide population ageing has increased the incidence of cognitive de ﬁcits,such as the age-associated memory impairment and senile dementias and Alzheimer's disease (Hornick et al.,2008).Extensive evidence supports the view that cholinergic mechanisms modulate learning and memory formation.Neuropathological occur-rences of cognitive de ﬁcits are associated with the cholinergic de ﬁciency (Gold,2003;Roberson &Harrell,1997).Inhibitors of acetylcholinesterase (AChE)have been extensively used to increase the effectiveness of cholinergic transmissions and endogenous acetylcholine levels and thus overcome cognitive de ﬁcits (Hornick et al.,2008;Silman &Sussman,2005).F.velutipes is bene ﬁcial to human memory.FVP has been proven to improve learning and memory ability of scopolamine hydrobromid-induced model mice and rats using step-through test and Morris water test (Zou,Liao,Wu &Liu,2010).However,the effect of FVP on AChE activity has not been studied.In our preliminary study,crude polysaccharide solution was testi ﬁed to be the main fraction in F.velutipes for inhibiting AChE activity.In view of the above,it is necessary to research the AChE inhibitory activity of FVP.In addition,it is suggested that polysaccharides induced cognitive improvement owing to their antioxidant activity (Fan et al.,2005;Zhang,Zhang,Wang &Mao,2008),so antioxidant activity of FVP was also investigated.Food Research International xxx (2010)xxx –xxx⁎Corresponding author.Tel./fax:+862584399086.E-mail address:qiuhuihu@ (Q.Hu).FRIN-03416;No of Pages 70963-9969/$–see front matter ©2010Elsevier Ltd.All rights reserved.doi:10.1016/j.foodres.2010.11.027Contents lists available at ScienceDirectFood Research Internationalj o u r n a l h o me p a g e :w w w.e l s e v i e r.c om /l oc a te /fo o d r e sThe objective of this study was to optimize the ultrasonic-assisted extraction conditions of FVP using response surface methodology. Effects of ratio of water to raw material,ultrasonic power,ultrasonic time,and ultrasonic temperature on the extraction yield of FVP were fully examined.Moreover,AChE inhibitory activity of FVP was investigated to study its potential to improve memory impairment and cognitive deﬁcit.On account of the relationship between oxidative stress and cognitive deﬁcit,1,1-diphenyl-2-picryl hydrazine (DPPH)radicals scavenging assay was also conducted to evaluate the antioxidant ability of FVP.2.Materials and methods2.1.Materials and chemicalsF.velutipes was purchased from local market(Nanjing,China)and then dried at60°C and ground to pass through80mesh screen,the powder was stored at4°C until used.Glucose,phenol,and sulfuric acid were obtained from Shanghai Chemical Co.(Shanghai,China).1,1-Diphenyl-2-picryl hydrazine(DPPH),5,5′-dithio-bis-(2-nitrobenzoic) acid,acetylthiocholine iodide,ascorbic acid,acetylcholinesterase (AChE,type VI-S,EC3.1.1.7),and galanthamine were obtained from Sigma-Aldrich Chemical Co.(St.Louis,MO,USA).All other chemicals used in experiments were of analytical grade.2.2.AChE inhibitory activity of Flammulina velutipes extracts10g F.velutipes powder was extracted with200ml of different solvents(deionized water,ethanol,petroleum ether,and ethyl acetate),respectively,and AChE inhibitory activities of the extracts were compared.Subsequently,the water extract was mixed with quadruplicate anhydrous ethanol and then centrifuged.The precip-itate,crude polysaccharides,was lyophilized and redissolved in water as crude polysaccharide solution(CPS).The supernatant was concentrated under reduced pressure,lyophilized,and redissolved in water as water–ethanol solution(WES).The AChE inhibitory activities of CPS and WES were further investigated.2.3.Ultrasonic extraction and determination of polysaccharidesF.velutipes powder was weighed accurately(10.0g)and extracted with distilled water in ultrasonic cell disintegrator((DCTZ-2000, Beijing Hongxianglong Biotechnology Development Co.Ltd).Subse-quently,the treated mixture was air cooled to room temperature and centrifuged(10,000rpm/min,15min).The supernatant was concen-trated under reduced pressure at65°C.The polysaccharides extracts obtained above were then mixed with4-fold volume anhydrous ethanol(ethanolﬁnal concentration,80%)and kept at4°C for24h. After centrifugation at5000rpm/min for15min,the precipitate was washed three times with anhydrous ethanol and then dialyzed and lyophilized to yield FVP sample.The percentage polysaccharides yield(%)is calculated as follows:Yield of polysaccharideð%Þ¼weight of dried crude FVPðgÞ×1002.4.Experimental designA three-level-four-factor,Box–Behnken factorial design(BBD)was employed in this optimization study.Ratio of water to raw material (X1),ultrasonic power(X2),ultrasonic time(X3),and ultrasonic temperature(X4)were chosen for independent variables to be optimized for the extraction of FVP.Yield of polysaccharides(Y)was taken as the response of the design experiments.Twenty-nine experiments were carried out in BBD(Table1).Five replicates at the center point were used for estimation of a pure error sum of squares.Triplicate determinations were performed at all design points in randomized order.A quadratic polynomial model wasﬁtted to correlate the response variable(yield of polysaccharide)to the independent variables.The general form of quadratic polynomial equation is as follows:Y¼β0þ∑4i¼1βi X iþ∑4i¼1βii X i2þ∑i¼1∑4j¼iþ1βijXiXjwhere Y is the response variable,andβ0,βi,βii,andβij are the regression coefﬁcients for intercept,linearity,square,and interaction, respectively,while X i and X j are the independent variables.2.5.AChE inhibitory activityThe AChE inhibitory activity assay was performed according to the protocol described by Langjae,Bussarawit,Yuenyongsawad, Ingkaninan and Plubrukarn(2007)with slight modiﬁcations.Brieﬂy, 125μl of3mM5,5′-dithio-bis-(2-nitrobenzoic)acid,25μl of1.5mM acetylthiocholine iodide,50μl of50μM Tris–HCl buffer(pH8.0),25μl of sample,and25μl of0.25U/ml AChE were added consecutively into 96-well plate.Then the absorbance was measured immediately at 412nm using an ELISA plate reader(TECAN Inﬁnite F200, Switzerland).The potency of AChE inhibitory activity of FVP was expressed as the inhibition rate.Galanthamine was used as a positive control.Table1Experiment of ultrasonic extraction of polysaccharides from Flammulina velutipes.(Data presented are the mean of triplicate determinations.)Run X1-ratio(ml/g)X2-ultrasonicpower(W)X3-ultrasonictime(min)X4-ultrasonictemperature(°C)Yield of FVP(%)ActualvaluePredictedvalue 12060015508.218.08 2304001550 6.887.05 32060015507.998.08 4204001565 6.63 6.76 5208001565 6.46 6.38 6208002550 6.64 6.82 7206005357.577.30 820400550 6.45 6.25 9108001550 6.21 6.16 1010600550 6.33 6.57 11104001550 6.18 6.14 1220600565 6.897.09 132040025507.597.56 143060015657.797.48 152060015508.178.08 163080015507.467.61 173********.557.55 182******** 6.58 6.96 193060025508.398.03 202060015508.298.08 21106001565 6.28 5.94 222080015357.917.66 23204001535 6.75 6.70 242060025358.067.98 25106001535 6.63 6.92 26106002550 6.77 6.64 272060015507.788.08 283060015357.427.74 29208005507.577.58 Optimumconditions24.81618.9818.6444.73–8.32Modiﬁedconditions2562020458.338.302W.Yang et al./Food Research International xxx(2010)xxx–xxx2.6.DPPH radicals scavenging assayThe DPPH radicals scavenging assay was carried out as previously described by Yang et al (2009).Brie ﬂy,0.1ml of FVP in water was added directly to 3.9ml of a DPPH solution in ethanol (0.1mM).The mixture was immediately shaken for 10s using a vortex mixer,kept at 37°C for 30min,and then centrifuged at 5000rpm/min for 10min.Absorbance of the supernatant was measured at 517nm.Antioxidant capability (AA)was expressed as the percentage of DPPH radicals reduced,which was calculated with the following formula:AA DPPH =A B −A S ðÞ=A B ðÞ×100;where A S is the absorbance of the DPPH solution after reacting with FVP sample at a given concentration and A B is the absorbance of the DPPH solution after reacting with distilled water instead of sample.Ascorbic acid was measured as a positive control.2.7.Statistical analysesData were expressed as means of three replicated determinations.Design Expert (Trial Version 7.0.3)was employed for experimental design,analysis of variance (ANOVA),and model building.SPSS 12.0software was used for statistical calculations and correlation analysis.Values of p b 0.05were considered to be statistically signi ﬁcant.3.Result and discussion3.1.AChE inhibitory activities of Flammulina velutipes extracts In order to study the AChE inhibitory activity of F.velutipes ,four solvent extracts of F.velutipes were prepared for AChE inhibitory activities assay.Results showed that the AChE inhibitory activity of water extract was signi ﬁcantly better than the other solvents extracts (ethanol,petroleum ether,and ethyl acetate).Subsequently,water extract of F.velutipes was separated into two parts (CPS and WES).The results of CPS and WES inhibiting AChE activities suggested that polysaccharides were the principal effective fraction of water extract (Fig.1).Therefore,FVP was selected for further study.3.2.Fitting the model and evaluation of the model predictability In order to obtain more polysaccharides,ratio of water to raw material (10–30ml/g),ultrasonic power (400–800W),ultrasonictime (5–25min),and ultrasonic temperature (35–65°C)was adopted to research their effects on the yield of FVP.The experiments were designed to evaluate the effects of four factors on the yield of FVP using ultrasonic extraction method (Table 1).The mathematical model representing the yield of polysaccharides as a function of the independent variables within the region under investigation was expressed as follows:Y =−11:94+0:18d X 1+0:03d X 2+0:30d X 3+0:25d X 4+6:88×10−5d X 1X 2+1:0×10−3d X 1X 3+1:2×10−3d X 1X 4−2:59×10−4d X 2X 3−1:11×10−4d X 2X 4−1:33×10−3d X 3X 4−5:99×10−3d X 21−1:86×10−5d X 22−2:87×10−3d X 23−2:06×10−3d X 24where Y is the yield of polysaccharides,and X 1,X 2,X 3,and X 4represent ratio of water to raw material,ultrasonic power,ultrasonic time,and ultrasonic temperature,respectively.Predicted response values for the yield of polysaccharides could be obtained using this quadratic polynomial equation in terms of independent variables values.ANOVA for the ﬁtted quadratic polynomial model was given to check the model adequacy (Table 2).F -test suggested that model had a high F -value (F =10.627)and a very low p -value (p b 0.0001),indicating that the ﬁtness of this model was highly signi ﬁck of ﬁt is the variation of the data around the ﬁtted model.The F -value and p -value of the lack of ﬁt were 2.576and 0.188,respectively,which implied an insigni ﬁcant difference relative to the pure error and a good ﬁtness of the model.Coef ﬁcient of determination (R 2)is de ﬁned as the ratio of the explained variation to the total variation,and R 2=0.914approaching unity suggested a good relevance of the dependent variables in the model (Yang,Zhao,Shi,Yang &Jiang,2008).The adjusted determination coef ﬁcient of the model (R 2adj =0.828)con ﬁrmed that the model was signi ﬁcant,indicating a good degree of correlation between the actual values and the predicted values of FVP yield.Adeq precision measures the signal to noise ratio,and a ratio greater than 4is desirable (Zhu,Heo,&Row,2010).An adequate ratio (Adeq precision =10.00)of this ﬁtted model indicated that it can be used to navigate the design space.Coef ﬁcient of variation (CV)is a standard deviation expressed as a percentage of the mean.The lower the CV,the smaller the residuals relative to the predicted value (Zhong &Wang,2010).A low CV of the model (CV=4.12)suggested a good precision and higher reliability oftheFig. 1.AChE inhibitory activity of Flammulina velutipes extracts.CPS:crude polysaccharide solution,WES:water –ethanol solution.Values are means ±SD.Values with same superscript letters are statistically not signi ﬁcantly different at p b 0.05(analysis of variance).Table 2Analysis of variance for the ﬁtted quadratic polynomial model of extraction of polysaccharides.Source Sum of squares dfMean Square F Value p -value Prob N F X 1 4.1891 4.18947.237b 0.0001X 20.26110.261 2.9440.1082X 30.23210.232 2.6210.1278X 41.1471 1.14712.9340.0029X 1X 20.07610.0760.8530.3714X 1X 30.0410.040.4510.5128X 1X 40.13010.130 1.4610.2467X 2X 3 1.0711 1.07112.0800.0037X 2X 40.44210.442 4.9870.0424X 3X 40.16010.16 1.8040.2006X 12 2.3271 2.32726.2440.0002X 223.5911 3.59140.488b 0.0001X 320.53210.532 6.0040.0280X 42 1.3971 1.39715.7480.0014Model 13.194140.94210.627b 0.0001Residual 1.242140.0887Lack of ﬁt 1.07100.107 2.5760.188Pure error 0.1740.042Cor total14.4428R 2=0.914R 2Adj =0.828CV =4.12Adeq precision =10.003W.Yang et al./Food Research International xxx (2010)xxx –xxxexperiments carried out(Gangadharan,Nampoothir,Sivaramakrishnan, &Pandey,2009).These results suggested that the model equation was adequate for reasonably predicting the yield of polysaccharides under any combination of values of the variables.The correlation between the predicted values and the actual values of FVP yield was analyzed according previous reports(Gan,Abdul Manaf&Latiff,2010).The closer the value of correlation coefﬁcient to 1,the better the correlation between the observed and predicted values(Banik&Pandey,2009).As shown in Fig.2,the Pearson's correlation coefﬁcient R=0.962approaching unity indicated a good agreement between the predicted values and the actual values and a good suitability of theﬁtted model equation for reﬂecting the expected optimization.3.3.Effects of extraction conditions on the yield of FVPThe effects of ratio of water to raw material,ultrasonic power, ultrasonic time,and ultrasonic temperature on the yield of poly-saccharides as well as their interactions were analyzed.Three-dimensional response surface plots for the response(the yield of polysaccharides)were plotted in Fig.3.Fig.3a shows the effects of ratio of water to raw material(X1)and ultrasonic power(X2)on the yield of FVP.With the increase of ultrasonic power,the yield of polysaccharides increased to a value and then declined when ratio of water to raw material was low but constantly increased when ratio of water to raw material was high.The yield of polysaccharides increased with increasing of ratio of water to raw material when ultrasonic power,as well as ultrasonic time(Fig.3b)and ultrasonic temperature(Fig.3c)was kept at a constant value.Fig.3b shows the effects of ratio of water to raw material(X1)and ultrasonic time(X3) on the yield of FVP.The yield of polysaccharides increased with the extension of ultrasonic time.Fig.3c shows the effects of ratio of water to raw material(X1)and ultrasonic temperature(X4)on the yield of FVP.The yield of polysaccharides decreased with the elevation of ultrasonic temperature.Fig.3d shows the effects of ultrasonic power (X2)and ultrasonic time(X3)on the yield of FVP.The yield of polysaccharides increased with the increasing of ultrasonic power when extraction bearing a short ultrasonic time,while a contrary result was obtained when extraction bearing a long ultrasonic time. Similarly,the yield of polysaccharides increased with the extension of ultrasonic time when ultrasonic power was low but decreased when ultrasonic power was high.Fig.3e shows the effects of ultrasonic power(X2)and ultrasonic temperature(X4)on the yield of FVP.The extraction yield of polysaccharides decreased with the elevation of ultrasonic temperature when ultrasonic power was high,butﬁrstly increased to a value and then declined when ultrasonic power was low.The possible mechanism was due to the degradation effect of ultrasonic wave and too high temperature(Yang,Zhao&Jiang,2008). The extraction yield of polysaccharides increased with the increase of ultrasonic power at low ultrasonic temperature,butﬁrst increased to a value and then declined at high ultrasonic temperature.Fig.3f shows the effects of ultrasonic time(X3)and ultrasonic temperature (X4)on the yield of FVP.The longer ultrasonic time and lower ultrasonic temperature,the higher polysaccharides yield.Taken altogether,the augment of all the four factors in a certain extent could increase the yield of polysaccharides,but higher ultrasonic power,if accompanied with higher ultrasonic temperature or longer ultrasonic time,would lower the yield of the yield of polysaccharides.The signiﬁcance of each coefﬁcient was checked by F-test and p-value(Table2).Values of“prob N F”less than0.05indicate model terms are signiﬁcant.It can be seen that the variables with the largest effect on the yield of FVP were X1,X4,X2X3,X2X4,X12,X22,X32,and X42,which suggested that ratio of water to raw material and ultrasonic temperature signiﬁcantly inﬂuenced the yield of FVP.Meanwhile,signiﬁcant interactions between ultrasonic power and ultrasonic time,and ultrasonic power and ultrasonic temperature were observed.This indicated that high ultrasonic power could reduce extraction time and temperature to avoid oxidation induced by high temperature.3.4.The optimal conditions and validation of the modelBy prediction of computing program,the optimal conditions for the highest yield of polysaccharides were as follows:ratio of water to material of24.81ml/g,ultrasonic power of618.98W,ultrasonic time of18.64min,and ultrasonic temperature of44.73°C.A predicted value of8.32%was obtained for yield of polysaccharides under the optimal conditions.In order to facilitate the practical extraction process of FVP,the optimal conditions were modiﬁed as follows:ratio of water to material of25ml/g,ultrasonic power of620W,ultrasonic time of20min,and ultrasonic temperature of45°C.A predicted value of8.30%was obtained under the modiﬁed conditions.The modiﬁed conditions were used to validate the suitability of theﬁtted model equation for accurately predicting the responses values.The results showed that the actual values of polysaccharides yield were8.29% under the modiﬁed conditions(Table1),which were in agreement with the predict values signiﬁcantly(p N0.05).Furthermore,FVP was extracted with a conventional method (ratio of water to material of25ml/g,extraction in80°C water bath for4h),and a yield of5.12%was obtained,which is signiﬁcantly less than that obtained with the ultrasonic extraction method.The results suggested that ultrasonic assistant extraction of FVP was a time and energy saving and high yielding method.3.5.AChE inhibitory activity of FVPAlzheimer's disease,a disorder associated with progressive degeneration of memory and cognitive function,results from a deﬁcit of cholinergic function in brain.The most important changes observed in brain are a decrease in hippocampal and cortical levels of the neurotransmitter acetylcholine and associated choline transferase (López,Bastida,Viladomat&Codina,2002;Perry,1986).Inhibiting AChE activity is considered as one of the most important methods to improve cognitive deﬁcit and learning and memory impairment by restoring the level of acetylcholine.In this study,concentration-dependent inhibition of AChE was observed for galanthamine.FVP exhibited moderate AChE inhibitory activity(up to20%)that was not dose-dependent(Fig.4).It is reported that polyphenol-rich extract of Vaccinium angustifolium exhibited moderate AChE inhibitory activity in vitro(up to30%),but the polyphenol treated mice exhibited a signiﬁcant improvement in learning and memory(Papandreou et al.,2009).Theseﬁndings indicated that FVP may be having a potential application value in improving cognitive deﬁcit and memory impairment.It has been reported that FVP improved the learning and memory ability of dysmnesia model animals effectively evaluated bystep-Fig.2.Correlation between the predicted values and actual values of FVP yield.4W.Yang et al./Food Research International xxx(2010)xxx–xxxthrough test and Morris water test (Zou et al.,2010).In the present study,the results of AChE inhibitory activity in vitro suggest a potential application of FVP to improve cognitive de ﬁcit.This may be one of the most important pharmacological mechanisms of enhancing the learning and memory capability of dysmnesia mice,which need our furtherinvestigation.Fig.3.(a)Response surface plots showing the effects of ratio of water to raw material (X 1)and ultrasonic power (X 2)on the yield of FVP (Y ).(b)Response surface plots showing the effects of ratio of water to raw material (X 1)and ultrasonic time (X 3)on the yield of FVP (Y ).(c)Response surface plots showing the effects of ratio of water to raw material (X 1)and ultrasonic temperature (X 4)on the yield of FVP (Y ).(d)Response surface plots showing the effects of ultrasonic power (X 2)and ultrasonic time (X 3)on the yield of FVP (Y ).(e)Response surface plots showing the effects of ultrasonic power (X 2)and ultrasonic temperature (X 4)on the yield of FVP (Y ).(f)Response surface plots showing the effects of ultrasonic time (X 3)and ultrasonic temperature (X 4)on the yield of FVP (Y ).5W.Yang et al./Food Research International xxx (2010)xxx –xxx3.6.DPPH radicals scavenging activity of FVPFree radical species have been reported to contribute to cellular ageing and neuronal damage (Sastre,Pallardo &Vina,2000).Excess amount of reactive oxygen species,which causes oxidative stress,is associated with pathology of memory de ﬁcits and associated diseases including Alzheimer's disease (Silva et al.,2004;Soholm,1998).DPPH radicals have been widely used as model systems to investigate the antioxidant ability of compounds.In this study,the DPPH scavengingactivity of FVP was concentration-dependent and the scavenging rate was up to 61.24%at concentration of 0.6mg/ml (Fig.5).Good antioxidant ability of FVP implies a potential of FVP to protect cognitive impairment.Moreover,polysaccharides have been proved to exhibit indirect antioxidant ability in vivo by increasing glutathione peroxidase and superoxide dismutase activities (Zhang et al.,2003).Therefore,in order to have a thorough knowledge of pharmacological mechanisms of improving cognitive de ﬁcit,the effect of FVP on antioxidant enzymes in vivo needs to be further studied.4.ConclusionExtraction conditions of FVP were optimized using BBD in response surface methodology,and a quadratic model was ﬁtted for the extraction conditions of FVP.Results of ANOVA and validation experiments suggested that the ﬁtted model was adequate for reasonably predicting the yield of FVP.A FVP yield of 8.33%was obtained under the modi ﬁed conditions (ratio of water to material of 25ml/g,ultrasonic power of 620W,ultrasonic time of 20min,and ultrasonic temperature of 45°C).A good potential of FVP to enhance cognitive ability was testi ﬁed by DPPH scavenging activity assay and AChE inhibitory activity test,which indicate that consummation of F.velutipes is bene ﬁcial to improve learning and memory de ﬁcit.AcknowledgmentThis work is ﬁnancially supported by the earmarked fund for Modern Agro-industry Technology Research System of China.ReferencesBanik,R.M.,&Pandey,S.K.(2009).Selection of metal salts for alkaline phosphataseproduction using response surface methodology.Food Research International ,42,470−475.Fan,Y.,Hu,J.,Li,J.,Yang,Z.,Xin,X.,Wang,J.,Ding,J.,&Geng,M.(2005).Effect of acidicoligosaccharide sugar chain on scopolamine-induced memory impairment in rats and its related mechanisms.Neuroscience Letters ,374,222−226.Gan,C.-Y.,Abdul Manaf,N.H.,&Latiff,A.A.(2010).Optimization of alcohol insolublepolysaccharides (AIPS)extraction from the Parkia speciosa pod using response surface methodology (RSM).Carbohydrate Polymers ,79,825−831.Gangadharan, D.,Nampoothiri,K.M.,Sivaramakrishnan,S.,&Pandey, A.(2009).Immobilized bacterial α-amylase for effective hydrolysis of raw and soluble starch.Food Research International ,42,436−442.Gold,P.E.(2003).Acetylcholine modulation of neural systems involved in learning andmemory.Neurobiology of Learning and Memory ,80,194−210.Hornick,A.,Schwaiger,S.,Rollinger,J.M.,Vo,N.P.,Prast,H.,&Stuppner,H.(2008).Extracts and constituents of Leontopodium alpinum enhance cholinergic transmis-sion:Brain ACh increasing and memory improving properties.Biochemical Pharmacology ,76,236−248.Langjae,R.,Bussarawit,S.,Yuenyongsawad,S.,Ingkaninan,K.,&Plubrukarn,A.(2007).Acetylcholinesterase-inhibiting steroidal alkaloid from the sponge Corticium sp.Steroids ,72,682−685.Leung,M.Y.K.,Fung,K.P.,&Choy,Y.M.(1997).The isolation and characterization of animmunomodulatory and anti-tumor polysaccharide preparation from Flammulina velutipes .Immunopharmacology ,35,255−263.Li,H.,Pordesimo,L.,&Weiss,J.(2004).High intensity ultrasound-assisted extraction ofoil from soybeans.Food Research International ,37(7),731−738.López,S.,Bastida,J.,Viladomat,F.,&Codina,C.(2002).Acetylcholinesterase inhibitoryactivity of some Amaryllidaceae alkaloids and Narcissus extracts.Life Sciences ,71,2521−2529.Papandreou,M.A.,Dimakopoulou,A.,Linardaki,Z.I.,Cordopatis,P.,Klimis-Zacas,D.,Margarity,M.,&Lamari,F.N.(2009).Effect of a polyphenol-rich wild blueberry extract on cognitive performance of mice,brain antioxidant markers and acetylcholinesterase activity.Behavioural Brain Research ,198,352−358.Perry,E.K.(1986).The cholinergic hypothesis —ten years on.British Medical Bulletin ,42,63−69.Roberson,M.R.,&Harrell,L.E.(1997).Cholinergic activity and amyloid precursorprotein metabolism.Brain Research.Brain Research Reviews ,25,50−69.Sastre,J.,Pallardo,F.V.,&Vina,J.(2000).Mitochondrial oxidative stress plays a key rolein aging and apoptosis.IUBMB Life ,49,427−435.Silman,I.,&Sussman,J.L.(2005).Acetylcholinesterase:‘Classical ’and 'non-classical'functions and pharmacology.Current Opinion in Pharmacology ,5,293−302.Silva,R.H.,Abilio,V.C.,Takatsu,A.L.,Kameda,S.R.,Grassl,C.,Chehin,A.B.,Medrano,W.A.,Calzavara,M.B.,Registro,S.,Andersen,M.L.,Machado,R.B.,Carvalho,R.C.,Ribeiro,R.d.A.,Tu ﬁk,S.,&Frussa-Filho,R.(2004).Role of hippocampal oxidative stress in memory de ﬁcits induced by sleep deprivation in mice.Neuropharmacology ,46,895−903.Fig.4.AChE inhibitory activity of galanthamine and FVP with various concentrations (data are in mean ±SD,n =3).Fig. 5.DPPH radicals scavenging activity of FVP and ascorbic acid with various concentrations (data are in mean±SD,n =3).6W.Yang et al./Food Research International xxx (2010)xxx –xxx。

不同热处理方式下虾肉品质和蛋白质结构变化的差异

不同热处理方式下虾肉品质和蛋白质结构变化的差异于小番，袁亚明，叶宇，夏超，田颖，许慧卿（扬州大学旅游烹饪学院，江苏扬州 225127）摘要：为探讨三种常用热处理方式、加热程度对虾肉的品质影响以及蛋白质结构的变化的差异性影响，本试验以刀额新对虾为试验原料，采用蒸制、烤制和微波三种热处理方式，以测定原料第一节肌肉中心温度达到60 ℃、70 ℃、80 ℃和过热状态为加热程度，比较其水分含量、水分活度、质构特性、蛋白质二级结构和三级结构变化、蛋白质断裂情况及氧化情况的差异。

结果表明，蒸制对虾肉水分、弹性及蛋白质结构的保留效果最好，其中蒸制弹性在80 ℃时最高，为4.31；蒸制对蛋白质的破坏程度最低且在加热过程中蛋白质产生了新的交联。

烤制的虾肉硬度最佳，游离巯基由13.62 nmol/mg pro降至1.01 nmol/mg pro、总巯基由35.61 nmol/mg pro 降至3.77 nmol/mg pro，其过热处理时蛋白质氧化程度最大。

微波处理虾肉的水分含量由75.62%降至12.78%，水分活度由0.98降至0.40，其对蛋白质结构的破坏最大。

三种热处理中，蒸制处理对蛋白质结构的影响最小，烤制的影响主要集中于蛋白质的氧化，微波加热对蛋白质结构的破坏最为严重。

本试验结果为进一步研究不同热处理方式下蛋白质结构与蛋白质消化性、过敏源性的关系提供理论基础。

关键词：热处理；虾肉；品质；蛋白质结构文章篇号：1673-9078(2021)05-160-168 DOI: 10.13982/j.mfst.1673-9078.2021.5.1009 Effect of Cooking Shrimp at Different Temperatures Using Different Methods on Meat Quality and Protein StructureYU Xiao-fan, YUAN Y a-ming, YE Yu, XIA Chao, TIAN Ying, XU Hui-qing(College of food Science and Engineering, Y angzhou University, Y angzhou 225127, China) Abstract: The effects of three common heating methods and of different temperatures on meat quality and protein structures in shrimp meat were compared. Metapenaeus ensis was steamed, grilled, and microwave-heated until the core temperature in the muscles of the first segment reached 60 ℃, 70 ℃, 80℃ and until the shrimp was overcooked. W ater content, water activity, texture properties, variations in secondary and tertiary protein structures, and protein fragmentation and oxidation were assessed under each condition, and then compared. Steaming was found to best preserve water content, firmness, and protein structure in shrimp meat. The meat is firmest when it is cooked at 80 ℃ with a firmness of 4.31. Steaming also minimizes protein modification, but allows new crosslinks to form between proteins. Grilling shrimp meat gives optimal firmness. Grilling decreases sulfhydryl radical content from 13.62 nmol/mg pro to 1.01 nmol/mg pro, while total sulfhydryl content drops from 35.61 nmol/mg pro to 3.77 nmol/mg pro. Grilling also results in the greatest protein oxidation. W ater content in microwave-heated shrimp meat is reduced from 75.62% to 12.78%, and water activity decreases from 0.98 to 0.40. Microwave-heated shrimp meat experiences the most significant protein structure modification. Among the three heating methods, steaming affects protein structure the least. Grilling mainly increases protein oxidation, while microwave heating alters protein structure the most severely. The results of this study provide a theoretical basis for further research into relationships between protein structure and digestibility and allergenicity, and the influences of different heating methods on protein structure.引文格式：于小番,袁亚明,叶宇,等.不同热处理方式下虾肉品质和蛋白质结构变化的差异[J].现代食品科技,2021,37(5):160-168YU Xiao-fan, YUAN Y a-ming, YE Y u, et al. Effect of cooking shrimp at different temperatures using different methods on meat quality and protein structure [J]. Modern Food Science and Technology, 2021, 37(5): 160-168收稿日期：2020-11-02基金项目：国家自然科学基金项目（81472963）作者简介：于小番（1996-），女，硕士研究生，研究方向：营养与食品卫生学；通讯作者：许慧卿（1972-），女，博士，教授，研究方向：微生物160Key words: heating; shrimp meat; quality; protein structure刀额新对虾(Metapenaeusensis)，俗称基围虾、沙虾、泥虾，在我国主要分布于福建、台湾、广东和广西沿海，因其味道鲜美，壳薄体肥，营养丰富，深受广大消费者喜爱，是我国常见的食用虾种[1]。

欧洲药典7.5版

EUROPEAN PHARMACOPOEIA 7.5
INDEX
To aid users the index includes a reference to the supplement in which the latest version of a text can be found. For example : Amikacin sulfate...............................................7.5-4579 means the monograph Amikacin sulfate can be found on page 4579 of Supplement 7.5. Note that where no reference to a supplement is made, the text can be found in the principal volume.
English index ........................................................................ 4707
Latin index ................................................................................. 4739
EUROPEAN PHARMACOPபைடு நூலகம்EIA 7.5
Index
Numerics 1. General notices ................................................................... 7.5-4453 2.1.1. Droppers...................

A Statistical Theory of Mobile-Radio Reception

cases .
For simplicity, it \\;11 be assumed that at every point there are exactly N component waves and that these N waves have the same amplitude. I n additio n it will be assumed that the transmitted rad iation is vertically polarized , that is, with th e electric-field vector directcd verti cally, and that the polarization is unchanged on scattering so that the received field is also vert ically polarized. Th e model described so far gives what might be termed the "sca ttered field," since th e energy arrives at the receiver by way of a number of indirect paths. Another term for t his scattered field is the "incoherent ficld," because its phase is completely random. Sometimes a significant fraction of t he total reccived energy arrives by way of the direct line-of-sight path from t ransmitte r to receiver. Th e phase of th e "direct wave" is nonr andom and it may therefore he described as a "coherent wave." It will be seen later that th e field in a heavil y built-up area such as New York Cit y is entirely of the scatte red type, whereas the field in a suburban area with the transmitter not more t han a mile or two distant is often a combination of a scattered fi eld with a direct wave.

大黄鱼CPT1的真核表达及其动力学性质对禁食的响应研究

中文全称肉碱棕榈先转移酶 1
焦磷酸二乙酯乙二胺四乙酸
游离肉碱米氏常数丙二酸单酰辅酶 A 棕榈酰辅酶 A 聚合酶链式反应
总肉碱最大反应速率
I
目录
摘要 .................................................................................................................................... I ABSTRACT ..........................................................................................................................II 缩略词表 ............................................................................................................................. III 引言 ................................................................................................................................... 1 第一章文献综述 ................................................................................................................. 3
本研究结果表明 cpt1a 基因具有生物学功能，并阐明了 CPT1 在禁食过程中的转录和动力学调节，强调禁食诱导的脂肪酸氧化依赖于动力学性质的改变，而不是 CPT1 的活性和转录。在短期禁食期间，鱼肝脏通过调节肉碱依赖性 Km，保证其具有较强的催化效率。然而，长期禁食会对 CPT1 的催化效率产生负面影响。关键词：大黄鱼；禁食；CPT1 动力学；分子克隆

6种叶面肥对海南林下栽培金钗石斛生长和品质的影响

热带作物学报2021, 42(10): 2898 2903 Chinese Journal of Tropical Crops收稿日期 2020-12-03；修回日期 2021-02-01基金项目海南省重点研发计划项目（No. ZDYF2019061）。

作者简介刘迎（1981—），男，博士，副研究员，研究方向：资源利用与植物保护。

*通信作者（Corresponding author ）：陈青（CHEN Qing ），E-mail ：*****************。

6种叶面肥对海南林下栽培金钗石斛生长和品质的影响刘迎1,2，陈青1,2*，梁晓1,2，伍春玲1,21. 中国热带农业科学院环境与植物保护研究所/农业农村部热带作物有害生物综合治理重点实验室/海南省热带作物病虫害生物防治工程技术研究中心，海南海口 571101；2. 海南省南繁生物安全与分子育种重点实验室，海南三亚 572000摘要：为筛选适宜的叶面肥种类，促进金钗石斛生长和提高其品质，以海南林下栽培的金钗石斛为试材，采用喷雾处理的方式，研究3种化学叶面肥和3种有机叶面肥对金钗石斛生长和品质的影响。

结果表明：所有施肥处理均增加了金钗石斛的分蘖数、叶片数、茎节数、茎粗和株高，不同程度提高了金钗石斛的鲜重、干重、干鲜比和叶绿素含量，同时也提高了金钗石斛多糖和总生物碱含量，因此喷施叶面肥有利于促进金钗石斛生长和改善金钗石斛品质。

3种化学肥料中，沃生促进金钗石斛生长和改善金钗石斛品质的性能优于磷酸二氢钾，其次是碧护；与对照相比，沃生显著提高了金钗石斛的茎粗、鲜重、干重、叶片SPAD 值、多糖和石斛总生物碱含量，增长率分别达到21.87%、35.68%、39.50%、7.96%、15.01%和9.89%。

3种有机肥料中，黄腐酸钾促进金钗石斛生长和改善金钗石斛品质的性能优于杜高活力藻，其次是海岛素；与对照相比，黄腐酸钾显著提高了金钗石斛的茎粗、鲜重和干重，增长率分别达到20.68%、28.39%和34.50%。

基于尺度-频率的小波微幅构造识别方法与应用——以南美厄瓜多尔X区块为例

第30卷第4期油气地质与采收率Vol.30，No.4 2023年7月Petroleum Geology and Recovery Efficiency Jul.2023引用格式：徐海，王光付，孙建芳，等.基于尺度-频率的小波微幅构造识别方法与应用[J].油气地质与采收率，2023，30（4）：98-105.XU Hai，WANG Guangfu，SUN Jianfang，et al.Identification method and application of micro-structure based on scale-frequency wavelet in Block X of Ecuador，South America[J].Petroleum Geology and Recovery Efficiency，2023，30（4）：98-105.基于尺度-频率的小波微幅构造识别方法与应用——以南美厄瓜多尔X区块为例徐海，王光付，孙建芳，李发有（中国石化石油勘探开发研究院，北京102206）摘要：针对构造幅度小于10m的微幅构造精细识别，受地震资料品质及解释精度限制，常规成图与分析方法面临着难以有效突出微幅构造细节与提高识别效率的问题。

以南美厄瓜多尔X区块微幅构造研究为目标，探索以小波构造分解的方法，实现对目标层3m左右微幅构造快速有效的精细识别。

目标层受安第斯造山运动弱挤压作用影响，大部分微幅构造幅度小于5m。

采用小波构造分解方法，将等深或等T0构造数据进行等间距采样，建立尺度随频率变化的“尺度-频率”小波函数，通过该函数多尺度地分解微幅构造起伏特征。

利用阈值函数控制优选低频、中频、高频构造起伏等信息，根据相应小波系数对构造低频、中频、高频成分进行多尺度重组，提高相应高频成分对微幅构造的识别权重，从而降低构造低频成分对微幅构造识别的遮蔽作用。

基于小波变换的微幅构造识别方法，可以有效识别幅度小于3m的微幅构造，极大提高了斜坡区小型微幅构造油藏预测精度与分析效率，应用该成果相继部署完钻一系列评价井，均获得成功及良好油气显示，取得了良好实钻效果。

Nature子刊张晓辉钟涛李大力合作开发超高活性的腺嘌呤碱基编辑器及超高活性双碱基编辑器

Nature子刊张晓辉钟涛李大力合作开发超高活性的腺嘌呤碱基编辑器及超高活性双碱基编辑器在人类遗传变异类型中，单核苷酸变异(SNV)在疾病相关的突变中占据了近60%1,2，因此开发高效精确的基因编辑工具对于治疗棘手的遗传疾病带来了希望。

碱基编辑器（Base editor,BE）最早由哈佛大学David R.Liu开发，是一类可以在不产生双链DNA断裂的基础上高效催化碱基转换，在临床基因治疗领域展现了极大的潜力。

目前，碱基编辑器主要包括ABE（Adenine base editor）和CBE(Cytosine base editor)，它们是将Cas9缺口酶（nickase）分别与腺嘌呤脱氨酶和胞嘧啶脱氨酶融合，实现A-to-G和C-to-T转换1, 2。

CBE, ABE开发之出均存在不同程度的技术缺陷，如如效率低、靶向范围小、产物不纯、“邻近碱基”突变、体积太大、DNA和RNA 脱靶等。

随着技术发发展，碱基编辑器存在活性低、靶向范围不足、精准性不足、脱靶效应等多个技术缺陷逐渐得到被国内外科学家们攻破。

我们前期已开发了克服其技术缺陷的多款新性能碱基编辑器，如克服单一底物限制的双功能碱基编辑器（A&C-BEmax）（Nature Biotechnology, 2020）3、超高活性的胞嘧啶碱基编辑器hyCBEs(Nature Cell Biology, 2020)4, 构建了一系列不依赖天然胞嘧啶脱氨酶家族的“精准且安全”的新型胞嘧啶碱基编辑器—TadA-derived CGBE/CBEs (Td-CGBE/Td-CBEs)（Nature Biotechnology, 2022）5，编辑窗口为1-2碱基的高精度的腺嘌呤碱基编辑器（ABE9）(Nature Chemical Biology, 2022)6和多个拓展靶向范围的PAM灵活的ABE系统(Protein &Cell, 2018)7等。

微泡弹性动力学

Microbubble Oscillations in Capillary Tubes david H. Thomas, Vassilis sboros, Marcia Emmer, Hendrik Vos, and nico de JongAbstract—In diagnostic medicine, microbubbles are used as contrast agents to image blood flow and perfusion in large and small vessels. The small vessels (the capillaries) have di-ameters from a few hundred micrometers down to less than 10 μm. The effect of such microvessels surrounding the oscil-lating microbubbles is currently unknown, and is important for increased sensitivity in contrast diagnostics and manipulation of microbubbles for localized drug release. H ere, oscillations of microbubbles in tubes with inner diameters of 25 μm and 160 μm are investigated using an ultra-high-speed camera at frame rates of ~12 million frames/s. A reduction of up to 50% in the amplitude of oscillation was observed for microbubbles in the smaller 25-μm tube, compared with those in a 160-μm tube. In the 25-μm tube, at 50 kPa, a 48% increase of mi-crobubbles that did not oscillate above the noise level of the system was observed, indicating increased oscillation damping. No difference was observed between the resonance frequen-cy curves calculated for microbubbles in 25-μm and 160-μm tubes. Although previous investigators have shown the effect of microvessels on microbubble oscillation at high ultrasound pressures, the present study provides the first optical images of low-amplitude microbubble oscillations in small tubes.I. Introductiono ne of the major goals of contrast ultrasound is to accurately measure the vascularization of tissue to the capillary level, which is relevant to a large number of pathological conditions [1]. The use of microbubbles as drug/gene delivery agents is also attractive, because they can provide: 1) site-specific targeting [2]; 2) increased cell permeability and membrane permeation [3]; and 3) deliv-ery of genes or other drugs safely in a variety of techniques [4], [5]. a precise understanding of microbubble behavior within microvessels is necessary to achieve these. The ma-jority of past theoretical work attempting to predict the forced oscillations of microbubbles has been focused on using various modified rayleigh–Plesset equations, which are based upon the assumption that microbubbles are sur-rounded by an infinite fluid and remain spherical until collapse. although such predictions have been useful for creating various diagnostic and therapeutic techniques [1], the assumption that a microbubble exists in an infinite fluid may not hold for a microbubble within the micro-vasculature. arterioles and capillaries less than 25 μm in diameter are abundant within the body, and account for a large proportion of the blood volume, e.g., 80% to 90% of the blood in the myocardium is in the capillaries [6]. a microbubble in vivo can rarely be considered to be in an infinite space, and will more often be closely surrounded by the vessel wall.The experimental observation of microbubble behavior in a limited fluid space is important to aid the under-standing of such behavior, and may lead to the develop-ment of useful signal processing strategies. recent theo-retical work simplifies the in vivo case to a microbubble oscillating in the center of a rigid tube. This has led to predictions that a decrease in both magnitude of micro-bubble oscillation and the resonance frequency will occur because of the restriction from a tube with a diameter of the same order of magnitude as the microbubble, as com-pared with oscillation in large vessels [7]–[11]. caskey et al. [12] have used high-speed streak images to show that at high acoustic pressures (1.4 MPa) microbubbles in a tube with a diameter on the order of the microbubble diameter expand less than microbubbles in larger tubes. However, the restrictive effect of the surrounding tube has not been previously shown at lower incident pressures. lower pres-sures are relevant to microvascular imaging, which uses low-mechanical-index (MI) ultrasound because of its high-ly sensitive pulse-sequence imaging protocols. a previous convention found in the literature proposes that micro-bubble response to low acoustic pressures (100 kPa for 1 MHz) is linear [13], [14]. In recent years, the breadth of optical information on microbubble behavior has proved that this is not true for phospholipid-coated bubbles. at low acoustic pressures (30 to 120 kPa) these microbubbles displayed strong nonlinear microbubble responses, such as compression-only behavior [15] and thresholded onset of scatter [16]. Both behaviors can be explained by a shell elasticity that is dependent on surface concentration of phospholipids [17], [18].With such evidence for the influence of the shell on mi-crobubble behavior at low acoustic pressures, we are inter-ested in the oscillations of microbubbles in small tubes at pressures ranging from 50 to 250 kPa. Here, we compare oscillations in a 25-μm tube with oscillations in a 160-μm tube using high-speed imaging.Ultra-high-speed optical imaging of microbubbles in narrow tubes of 25 μm diameter is performed here to vi-sualize microbubbles in an environment that is closer to in vivo imaging conditions.II. MethodsExperiments were performed with the commercially available contrast agent definity (lantheus Medical Imag-Manuscript received March 27, 2012; accepted september 3, 2012.This work was supported by The British Heart Foundation (Fs/07/052)and the royal society of Edinburgh (scotland’s national academy, scot-tish charity no. sc000470).d. H. Thomas and V. sboros are at the department of Medical Phys-ics and Medical Engineering, University of Edinburgh, Edinburgh, UK(e-mail: d.h.thomas@).M. Emmer, H. Vos, and n. de Jong are at the Thorax center, depart-ment of Biomedical Engineering, Erasmus Medical center, The nether-lands.doI /10.1109/TUFFc.2013.25420885–3010/$25.00 © 2013 IEEEing Inc., n. Billerica, Ma), a soft-shelled agent consist-ing of perfluorocarbon gas encapsulated by a lipid shell.a highly diluted solution of definity was used to ensure a sparse distribution of microbubbles within the imaging field. single microbubbles were isolated in the microscope field of view to enable the study of isolated microbubbles and minimize the effect of bubble–bubble interactions. The microbubble solution was refreshed with freshly shak-en and similarly diluted definity solution every 20 min to ensure microbubbles did not degrade with time. Because acoustic data were not recorded here, the bubbles were considered isolated if there were no other bubbles visible in the microscope field of view. The oscillations of micro-bubbles with resting diameters of D0 = 2 to 10 μm were measured here. The experiments were performed within six hours of the preparation of the microbubble solution.The microbubble solution flowed from a reservoir into either a cellulose tube of diameter φ = 160 μm (spectrum laboratories, rancho dominguez, ca) or a poly(methyl methacrylate) (PMMa) tube of diameter φ = 25 μm (Paradigm optics, Vancouver, Wa, canada). The differ-ence in tube material was a result of the limited availabil-ity of such small diameter tubing, and the two tubes were chosen because they had the most similar stiffness of the materials available. Tubing was not available in cellulose material in sizes down to 25 μm, so PMMa was used for the smaller tube. The tubes’ internal/external diameters were φ/φout = 25/50 and 160/200 μm, respectively. To avoid overpressure on the microbubbles, a manual micro-syringe of 1 ml volume was used to flush the tubes with water, allowing capillary action to draw the microbubble solution from an external reservoir. The position of indi-vidual microbubbles once in the tubes was manually con-trolled using a 1-ml syringe connected to a fine pitch micrometer screw to increase and decrease flow.Fig. 1 shows a schematic drawing of the experimental set-up. The tubes were mounted in a water tank and held in place horizontally in the field of view of an upright mi-croscope (BXFM, olympus, nederland BV, Zoeterwoude, The netherlands) with a 60× magnification objective (lUMFPl, olympus; na = 1.00, water immersion) and a 4× magnifier (U-ca, olympus). an optical fiber (olym-pus) was placed under the capillary tube and connected to a MVs-7010 fiber optic strobe (PerkinElmer optoelec-tronics, salem, Ma) for illumination. Bright-field trans-mission imaging combined with a charge-coupled device (ccd) camera (lcl-902Hs, Watec, Middletown, ny, 6% efficiency at 1000 nm) was performed through the same objective, allowing a single microbubble to be aligned with the focus of the microscope [19].a n unfocused 2.25-MHz transducer (V306, Panamet-rics Inc., Waltham, Ma) was mounted with the tube and the optical focus in the center of the incident beam, at an angle of 45° to the top of the tank. a function gen-erator (8026, Tabor Electronics ltd., Tel Hanan, Israel) was used to produce gated 1.7-MHz 6-cycle driving pulses, which were then amplified by a 52-dB linear power am-plifier (150a100B, ar Worldwide, souderton, Pa). The programming of the waveforms was performed in Matlab (r2007b, The MathWorks Inc., natick, Ma). The acous-tic beam was 1 to 5 mm diameter at focus and fully over-laps the optical field of view (38 × 29 μm). Peak nega-tive acoustic pressures from 50 to 200 kPa were calibrated by a needle hydrophone (0.2-mm PVdF probe, Precision a coustics, dorchester, UK), in a separate setup. Pulses at a range of incident frequencies from 0.5 to 5 MHz at 50 kPa peak negative pressure were calibrated in the same way.Microbubble oscillations at ultrasound frequencies were recorded optically using the Brandaris 128 ultra-high-speed camera, which was specifically developed for inves-tigating microbubble dynamics [20]. Using the camera in segmented region of interest mode, a single capture by the camera allowed oscillations of individual microbubbles to be recorded in up to 128 separate movies of 64 image frames each, at a speed of 12 million frames per second. The time between movies was 80 ms. In each movie, the individual microbubble was recorded without ultrasound transmission for 20 frames to determine resting microbub-ble size. The remaining 44 frames were then used to record microbubble oscillation in response to the ultrasound. The resolution limit for measurement of microbubble oscilla-tion has been previously shown to be 150 nm [16].Two separate experimental protocols were followed. In the first, microbubbles were insonfied by four sepa-rate pulses of 1.7 MHz, with the peak negative pressure increased in each movie in steps of 50 kPa from 50 kPa to 200 kPa. This allowed each single microbubble to be insonated with four different acoustic pressures in a single capture.In a second experiment, a range of frequencies was transmitted at 50 kPa incident pressure, one in each movie. Incident pulse amplitude was limited to 50 kPa so as not to disrupt the integrity of the bubble shell over multiple incident pulses. Microbubbles that underwent a reduction in initial diameter greater than 10% betweenpulses were considered to have been disrupted by the im-Fig. 1. schematic drawing of the tube phantoms, showing the relative dimensions and the position of the bubble and the tube. (The 25-μm and 160-μm tubes are not to scale.)thomas et al.: microbubble oscillations in capillary tubes 107aging pulses, and discounted from further analysis. This occurred in less than 15% of microbubbles measured in each tube. Each individual microbubble was insonified from 0.5 MHz to 5 MHz in steps of 200 kHz, in a single capture. Each individual capture ended with the starting frequency being repeated to ensure that the microbubble remained intact, had the same initial diameter, and that the response of the bubble was not changed by the mul-tiple insonations.a semiautomatic procedure using a minimal-cost algo-rithm [21] implemented in Matlab was used to measure the diameters of the individual microbubbles in each im-age frame, allowing the microbubble diameter response as a function of time to be extracted. all diameter–time curves were visually inspected to ensure that bubbles that gave no oscillation above noise were noted as such. as the sampling rate of the optical system is limited to 12 MHz, high-frequency components of the diameter–time response may be aliased [21], and manifest themselves as over-shoots in the diameter–time curve. The data was carefully checked to remove any erroneous values arising from such high-frequency transients. To calculate the amplitude of oscillation, the fundamental component of response was extracted, because this is much less sensitive to errors. This was performed by applying a fourth-order elliptical filter with 400 kHz passband, which was confirmed by vi-sual inspection of the spectra to be sufficiently wide to ex-tract the fundamental response. The incident ultrasound center frequency transmitted to the transducer is used as the center frequency of the elliptical filter. a sufficiently wide bandwidth of 400 kHz ensured that the exact center frequency was not critical in the resulting fundamental response, as verified by visually inspecting the frequency spectra.The amplitude of oscillation is calculated as the differ-ence between the maximum and minimum amplitude of fundamental response:∆I I I fun fun fun =−max min. (1)The relative amplitude of oscillation is defined as the amplitude of oscillation normalized by the resting diam-eter (D 0) of the microbubble,A I D fun fun=∆0, (2)and was used to compare the behavior of bubbles of differ-ent sizes in different microvessel phantoms, and also as a criterion for the identification of resonance [21].To investigate the nonlinearity of microbubble oscilla-tion the expansion, E , to compression, C , ratio was also determined. Using the recorded diameter–time curves, the expansion-to-compression ratio was calculated before fun-damental filtering, as [22]E C D D D D /=−−max min.00 (3)The application of the fundamental filter acts to re-move nonlinearities and the fundamental signals are most-ly symmetrical. Values of E /C were therefore calculatedbefore fundamental filtering was applied, and signals were carefully checked to ensure overshoots in the diameter–time curves did not produce erroneous values; such signals were removed from further analysis, and accounted for less than 5% of signals.III. resultsFig. 2 shows the typical oscillations of two similarly sized microbubbles in 160-μm and 25-μm tubes in re-sponse to a 50-kPa 1.7-MHz 6-cycle pulse. Figs. 2(a) and 2(d) show the diameter–time curve extracted using the minimal-cost algorithm in each case, Figs. 2(b) and 2(e) show the FFT amplitude of response with 400 kHz pass-band fourth-order elliptical filter superimposed, and Figs. 2(c) and 2(f) show the subsequent filtered fundamental component of response. Figs. 2(a)–2(c) show the oscil-lations of a 2.75-μm microbubble in a 160-μm diameter tube, and the relative amplitude of fundamental response has been calculated as A fun = 0.14. This compares to the 2.8-μm microbubble in a 25-μm diameter tube shown in Figs. 2(d)–2(f) which has relative amplitude of fundamen-tal response of A fun = 0.04.A. Amplitude of Oscillationa total of 35 microbubbles were measured in the 160-μm tube and 43 microbubbles in the 25-μm tube. Fig. 3 shows the relative amplitude of fundamental oscillation for microbubbles in the two microvessel phantoms (25 μm and 160 μm), plotted against initial diameter (D 0), in re-sponse to increasing acoustic pressures (50 to 200 kPa). The amplitude of microbubble oscillation in the 25-μm vessel is significantly reduced compared with the relative amplitude in the larger vessel, in response to all incident pressures. Microbubbles with initial diameters D 0 = 2.5 to 3.5 μm which have small amplitude oscillations (A fun < 0.1) show some overlap between the amplitude of oscil-lation in the two tube diameters. The largest difference between the two tube diameters occurs at maximum am-plitude of oscillation, which in response to 50-kPa incident pressure was measured to be 0.36 in the 160-μm tube and 0.26 in the 25-μm tube.In both tube sizes, several microbubbles below 4 μm showed no oscillation above the noise level of the system. These instances were much higher in the smaller 25-μm tube; in response to 50 kPa, 56% of microbubbles below 4 μm (18 of 32 microbubbles measured) gave no above-noise response in the 25-μm tube. This compares to only 25% of microbubbles measured less than 4 μm (3 of 12 mi-crobubbles measured) in the 160-μm tube. although the number of bubbles analyzed in this size range is greater in the 25-μm tube (32 versus 12), which may bias the analy-sis here, it is clear there is a significant increase the num-108IEEE TransacTIons on UlTrasonIcs, FErroElEcTrIcs, and FrEqUEncy conTrol, vol. 60, no. 1, JanUary 2013Fig. 2. diameter–time curves for microbubbles inside (a)–(c) a 160-μm tube and (d)–(f) a 25-μm tube. (a), (d): the diameter–time curves of a 2.75-μm bubble and a 2.80-μm bubble; (b), (e): the corresponding frequency responses; and (c), (f): diameter–time curve using the fundamental filter as shown in (b), (e) as a dotted line.thomas et al.: microbubble oscillations in capillary tubes 109ber of bubbles which give no response in the smaller ves-sel. The maximum diameter of microbubbles which gave no response was D 0 = 3.1 μm in the 25-μm tube, com-pared with D 0 = 2.0 μm in the 160-μm tube. In response to 100 kPa, the proportion of microbubbles that show no oscillation above the noise level of the system is reduced to 7.6% in the 25-μm tube and to zero in the 160-μm tube, where all microbubbles give a response above noise. In re-sponse to pressures above 100 kPa, all microbubbles gave a response in both tubes.Fig. 4 shows the relative expansion-to-compression ra-tio (E /C ) of microbubbles in both the 25-μm and 160-μm diameter tubes. Microbubbles which gave no response above noise have been given a value of E /C = 0. note that an E /C of 1 indicates that the expansion amplitude equals the compression amplitude. a microbubble shows com-pression-only behavior when its E /C ratio <0.5, and ex-pansion dominates for an E /C >1.5 [22]. The majority of microbubbles here expressed an E /C below 1.0, indicating that the compression amplitude dominates at these acous-tic pressures. The majority of bubbles with a diameter smaller than 4 μm showed compression-only behavior. at 50 kPa, the increased numbers of microbubbles that give no response in the 25-μm tube leads to a reduction in the numbers of microbubbles with compression-only behavior.The microbubbles that do give a response show similarFig. 3. relative amplitude of fundamental oscillation A fun for definity microbubbles D 0 = 2 to 10 μm, in microvessels of inner diameters 25 μm and 160 μm, in response to (a) 50 kPa, (b) 100 kPa, (c) 150 kPa, and (d) 200 kPa peak negative pressure, 6-cycle pulses at 1.7 MHz incident frequency.IEEE TransacTIons on UlTrasonIcs, FErroElEcTrIcs, and FrEqUEncy conTrol , vol. 60, no. 1, JanUary 2013110E /C values as similar sized microbubbles in the 160-μm tube. a t larger incident acoustic pressures, there is no significant difference between the two data sets. Maximum expansion corresponds approximately with those micro-bubble radii with largest amplitudes of oscillation, in both tubes and in response to all acoustic pressures measured.B. Resonance Frequency The relative fundamental amplitude of oscillation A fun was calculated in response to a range of incident frequen-cies using repetitive pulsing for a range of frequencies. The maximum A fun corresponds to the frequency of maximum response of the individual microbubble [21], [23]. The in-sert of Fig. 5 shows an example resonance curve for a microbubble of D 0 = 2.54 μm in a 25-μm tube (relevant frequencies of 3 to 5 MHz shown), where the maximum amplitude of oscillation A fun = 0.17 occurred in responseto a 3.6-MHz incident pulse.Fig. 5 shows the resonance frequencies calculated fromthe resonance curves of 33 and 27 microbubbles in 25-μmand 160-μm tubes, respectively. after the increasing fre-Fig. 4. relative expansion-to-compression ratios for microbubbles in 25-μm- and 160-μm-diameter tubes to (a) 50 kPa, (b) 100 kPa, (c) 150 kPa, and (d) 200 kPa peak negative pressure, 6-cycle pulses at 1.7 MHz incident frequency. There is no significant difference observed between the two data sets.thomas et al.: microbubble oscillations in capillary tubes 111quency sweep, all microbubbles in both tubes have shown a return to the original amplitude of oscillation in response to a repeat of initial incident parameters, which confirms the reproducibility of the experiment. The two data sets exhibit similar trends, with increasing D 0 corresponding to decreasing resonance frequency and no significant dif-ference observed between the two tubes. data points are limited for small microbubbles (D 0 < 3 μm), because of the bandwidth of the transducer used and the difficulty of isolating and positioning smaller microbubbles, and thus any differences in this regime are hard to quantify.IV. discussionThe effect of microvessels surrounding oscillating mi-crobubbles has been investigated here using the ultra-high-speed Brandaris 128 camera and low incident acous-tic pressures. a reduction of up to 50% in oscillation was observed for microbubbles in the smaller 25-μm tube com-pared with those in a 160-μm tube. single-plane optical measurement of microbubble oscillation was chosen here to maximize the detection of the reduced oscillations in the small tubes. The main effect of having a microbubble in contact with the presence of a rigid wall is to break the symmetry compared with a bubble in an infinite liquid, and eccentricities of bubbles in the vicinity of a capillary wall have been reported to be close to 0.7 [24]. The pres-ent experiments employed low acoustic pressures to en-sure that the oscillations were small and asymmetries were minimized. The optical data of microbubble oscillations inboth acoustic pressure and frequency experiments demon-strated highly reproducible observations. The radius–time curves of microbubbles in 25-μm tubes observed here sug-gest that the vicinity of the surrounding tube suppresses the amplitude of oscillation. Maximum amplitude of oscil-lation, relating to a microbubble driven at resonance [23], was observed for microbubbles with diameters between 4 and 6 μm in both tubes in response to 1.7-MHz pulses, which agrees with previously published data on definity and similar lipid shelled microbubbles [16], [25].The increase in the number of microbubbles in the 25-μm tube that do not give a response at low pressure sug-gests that the presence of a surrounding tube increases the threshold necessary for oscillation. Because the ob-servation of the microbubble response was limited by the resolution of 150 nm, it is not known if the microbubbles oscillate below this, but the data in the 160-μm tube are similar to previous results [16]. The data in response to a 50-kPa incident pulse here indicates that in the 25-μm tube, the incidence of bubbles below 4 μm for which oscil-lations will not occur is increased when compared with the 160-μm tube. However, the size of the data sets in this range is limited, and large variation between individual microbubbles exists. In the 25-μm tube, several micro-bubbles below D 0 = 4 μm were observed to oscillate in response to the same 50-kPa incident pulse, suggesting large variations in shell parameters [16], [19]. Emmer et al . [16] suggest that a minimum pressure required to initiate microbubble oscillation indicates that a threshold must be overcome before substantial oscillations can occur, and relate this to size-dependent mechanical properties of the phospholipid shells, which may differ in individual microbubbles because of inconsistencies in composition. although the influence of the presence of a rigid wall on the onset of microbubble oscillation has yet to be estab-lished, similar thresholding behavior has been observed in microbubbles floating against a rigid wall [16] and at a dis-tance of 150 μm from a rigid wall [18]. Both Emmer et al . [16] and overvelde et al . [18] show that only a very small change in the incident pressure (<2 kPa for microbubbles with D 0 = 3.0 μm) or resonance characteristics of a mi-crobubble can cause the onset of oscillation, and that the amplitude of oscillation with respect to incident pressure has a large discontinuity above the threshold pressure. The presence of the rigid wall, against which the bubbles rest because of buoyancy, has been shown to suppress the amplitude of microbubble oscillation by more than 50% [26] compared with microbubble oscillation in free space, and a decrease in amplitude of response has been observed at a maximum distance of 25 times the microbubble diam-eter (25 × D 0) [18]. In both tubes here, the microbubbles rest against the top wall (Fig. 1), and Fig. 6 shows how the relative distance to the opposite wall (d 1/D 0) varies with microbubble diameter D 0 in each of the tubes. In the larger tubes, all bubbles with D 0 < 8 μm are at a relative distance of d 1/D 0 > 25 from the opposite wall. In the 25-μm tube, this is only the case for microbubbles less thanFig. 5. resonance frequencies as calculated using microbubble spectros-copy. Error bars correspond to the frequency resolution of individual measurements (0.1 to 0.2 MHz). no significant difference can be deter-mined between the two microvessel phantoms. The figure insert shows the resonance frequency curve of a D 0 = 2.54-μm microbubble in a 25-μm tube. Frequency of maximum response as calculated by maximum value of A fun is 3.6 MHz.IEEE TransacTIons on UlTrasonIcs, FErroElEcTrIcs, and FrEqUEncy conTrol , vol. 60, no. 1, JanUary 2013112D 0 = 1 μm, and microbubbles of diameter D 0 > 4 μm are all less than d 1/D 0 < 5 from the opposite wall, which may account for the increased restriction of oscillation observed in this smaller tube. a damping based on relative distance to the opposite wall may also go some way to explain-ing the parity of responses at smaller diameters, because these bubbles are relatively further away. The oscillations of these smaller microbubbless may be at the limit of the influence of the opposite wall in the smaller tube, and thus behave as if in an infinite space once above an oscillation threshold. Further theoretical analysis is needed to inves-tigate this effect.The equivalence in amplitude of oscillation at off-res-onance microbubble diameters has not been observed in previous experimental tube studies, which use much higher insonating pressures. comparison is difficult however, as at higher acoustic pressure oscillations become extremely asymmetric and microbubbles are more likely to behave as free gas bubbles due to destruction of the shell. caskey et al . [12] show oscillations in a 25-μm tube are reduced 3-fold for microbubbles which are less than D 0 = 3 μm compared with similarly sized microbubbles in a 160-μm tube, when insonated at 1.4 MPa peak negative pressure. The relative amplitude of oscillations at such high pressures is up to 20 times greater than those observed here, and the deviation in the results may suggest that damping caused by the opposite wall increases with amplitude of oscillation, as well as proximity to a rigid wall. although it has not been possible here to measure the oscillation of the exact same microbubble in both tubes, the results shown here suggest that the restriction of oscillation is also strongly related toamplitude of oscillation. The amount of compression-only behavior, which has been previously related to buckling of the phospholipid shell [27], appears to be unaffected by the surrounding tube, as shown in overlap of expansion-to-compression ratio curves in Fig. 4. Maximum expansion is correlated with resonance behavior in both tubes, and microbubbles with largest E /C ratio have maximum am-plitude of oscillation, which agrees with previous observa-tions [15]. compression-dominated behavior is observed for the majority of microbubbles smaller than D 0 = 4.0 μm in both tubes, although this is masked slightly in the data from 25 μm at 50 kPa [Fig. 5(a)] because of the increased threshold for oscillation. The influence of the presence of a rigid wall on the expansion-to-compression ratio of mi-crobubble oscillations has yet to be fully established, but overvelde et al . [18] have shown similar compression-only behavior both in microbubbles in contact with and away from a rigid wall. This would suggest that the proximity of a surrounding tube has little effect on the expansion-to-compression ratio, as observed here, and compression-only behavior arises mainly from decreased surface tension in the phospholipid shell [27].although a clear difference in the amplitude of oscil-lation has been observed for individual microbubbles in both the 25-μm and 160-μm tubes, Fig. 5 shows that the resonance frequency of such microbubbles are similar at all diameters measured, although this may not be the case for bubbles smaller than those measured here (D 0 < 2.5 μm). Theoretical predictions of the resonance fre-quency of shelled microbubble oscillations in tubes are sparse, and most assume bubbles are not in contact with the tube wall, as is the case here. Previous theoretical work [8], [28], [29] modeling free gas bubbles has predicted that the damping coefficient caused by the presence of a surrounding capillary is dominated by viscous losses, lead-ing to both a reduction in amplitude of oscillation and also frequency of resonance. sassaroli and Hynynen [8] predict that the resonance frequency of a D 0 = 4 μm free gas mi-crobubble will be reduced by 40% in a rigid 25-μm tube compared with a rigid 50-μm tube, because of increased liquid flow along the surface of the tube surrounding the bubble. However, as well as ignoring the effects of the phospholipid shell, these works treat the microbubble as being in the center of the tube. It has been observed ex-perimentally that the frequency of maximum response of an individual microbubble will decrease by 20% at a rigid wall with respect to a microbubble in free space [18], but this has only been observed at very small distances, less than 2.5 × D 0. With microbubbles floating against the top wall in the 25-μm tube, the opposite wall is less than 2.5 × D 0 only for microbubbles with diameters larger than D 0 = 7 μm (Fig. 6), for which the data on resonance frequency presented here are sparse (Fig. 5). any changes in reso-nance frequency less than 20% are difficult to determine in the data shown here because of the variation in response of microbubbles of similar sizes.Both of the microvessels used here—the 25-μm diam-eter PMMa tube and the 160-μm cellulose tube—can beFig. 6. Microbubble relative distance to the opposite wall (d 1/D 0) plotted against microbubble diameter D 0, for the two tubes. The larger tube of diameter ϕ = 160 μm has a relative distance greater than d 1/D 0 > 20 for bubbles up to D 0 = 10 μm as measured here. In the small tube of ϕ = 25 μm inner diameter, this is only the case for bubbles with diameters less than 1 μm, and the relative distance decreases rapidly to less than d 1/D 0 < 5 for bubbles of D 0 = 4 μm at resonance and above.。

有机溶剂挥发量之估算方法

有机溶剂挥发量之估算方法宇文皓月赵焕平中原大学生物环境工程学系32023桃园县中坜市中北路200号Tel: 03-2654914， Fax: 03-2654949， E-mail: hpchao@.tw 有机溶剂常具有高挥发性与毒性，当它们挥发至大气中，往往会对工厂操纵人员或附近居民健康造成威胁，许多工厂考虑以排放系数计算挥发性有机物(VOCs)之挥发量，虽然使用排放系数可以概略的估算出工厂整体挥发性有机物的排放量，但若要考虑有机溶剂挥发对人体健康可能发生之影响，则需要针对分歧有机溶剂的个别挥发量进行估算。

可惜的是，目前所有对于有机溶剂挥发所发展出的方法均为经验方程式，虽然可以在特定条件下估算有机溶剂的挥发量，但往往因为环境条件改变或工作地点变动而造成估算误差，本文的主要目的在提供一个估算有机溶剂挥发量的方法，希望藉由此方法能够估算工厂内有机溶剂之挥发量，以减少有机溶剂周遭工作劳工可能发生之危害。

一、影响有机溶剂挥发之参数有机溶剂的挥发主要受到其自己性质的影响，其中最主要的影响因子为有机物自己的饱和蒸气压，罕见有机化合物的蒸气压可以由一般物理化学的工具书查到[1]，若是针对同一类型的有机物，如烷类、醇类、烯类等，饱和蒸气压将会随有机物分子量增加而减少。

若是针对分歧类型的有机物如烷类与醇类，尽管分子量接近，但醇类分子间有氢键，因此戊醇的蒸气压将远低于戊烷，除了有机溶剂自己的性质外，环境因子也会影响有机溶剂的挥发量，其中最明显者为温度与风速[2,3]，温度改变有机物的饱和蒸气压也会改变，通常温度增加有机物的饱和蒸气压会增加，特别是高蒸气压的化合物，温度增加时，蒸气压增加的趋势更为明显。

另外液面上方风速也是一个非常重要的影响因子，有风与无风的条件下有机物的挥发量相差常超出10倍，因此当有风通过液面上方，将使有机溶剂的挥发量明显增加[4]。

除上述影响因子外，尚有一些因子可能会影响挥发量，但却经常被忽略不计，如液体搅拌就是一个明显的例子，一般观念认为纯的有机溶剂进行搅拌，其实不会增加它们的挥发量，但实际上，搅拌可使有机溶剂概况发生扰动，仍然会使有机溶剂的挥发量增加，只是此挥发增加有限，因此除非是非常迅速搅拌，否则可以忽略不计。

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a r X i v :a s t r o -p h /0411251v 1 10 N o v 2004Astrophysical Journal Letters,submitted 2004March 19,accepted 2004May 5,scheduled for GALEX special issuePreprint typeset using L A T E X style emulateapj v.6/22/04LARGE-AMPLITUDE ULTRAVIOLET VARIATIONS IN THE RR LYRAE STAR ROTSE-I J143753.84+345924.8Jonathan M.Wheatley,1Barry Y.Welsh,1Oswald H.W.Siegmund,1Yong-Ik Byun,2Sukyoung Yi,3Young-Wook Lee,2Barry F.Madore,4,5Maurice Viton,6R.Michael Rich,7Luciana Bianchi,8Tom A.Barlow,9Jose Donas,6Karl Forster,9Peter G.Friedman,9Timothy M.Heckman,8Patrick N.Jelinsky,1Roger F.Malina,6D.Christopher Martin,9Bruno Milliard,6Patrick Morrissey,9Susan G.Neff,10David Schiminovich,9Todd Small,9Alex S.Szalay,8and Ted K.Wyder 9Astrophysical Journal Letters,submitted 2004March 19,accepted 2004May 5,scheduled for GALEX special issueABSTRACTThe NASA Galaxy Evolution Explorer (GALEX )satellite has obtained simultaneous near and far ultraviolet light curves of the ROTSE-I Catalog RR Lyrae type ab variable star J143753.84+345924.8.A series of 38GALEX Deep Imaging Survey observations well distributed in phase within the star’s 0.56432d period shows an AB =4.9mag variation in the far UV (1350-1750˚A )band and an AB =1.8mag variation in the near UV (1750-2750˚A )band,compared with only a 0.8mag variation in the broad,unﬁltered ROTSE-I (≈4500-10000˚A )band.These GALEX UV obser-vations are the ﬁrst to reveal a large RR Lyrae amplitude variation at wavelengths below 1800˚A .We compare the GALEX and ROTSE-I observations to predictions made by recent Kurucz stellar atmosphere models.We use published physical parameters for the comparable period (0.57433d),well-observed RR Lyrae star WY Antliae to compute predicted FUV,NUV,and ROTSE-I light curves for J143753.84+345924.8.The observed light curves agree with the Kurucz predictions for [Fe/H]=-1.25to within AB =0.2mag in the GALEX NUV and ROTSE-I bands,and within 0.5mag in the FUV.At all metallicities between solar and one hundredth solar,the Kurucz models predict 6-8mag of variation at wavelengths between 1000-1700˚A .Other variable stars with similar temperature variations,such as Cepheids,should also have large-amplitude FUV light curves,observable during the ongoing GALEX imaging surveys.Subject headings:stars:atmospheres —stars:individual (ROTSE-I J143753.84+345924.8)—stars:variables:other (RR Lyrae)—ultraviolet:stars1.INTRODUCTIONRR Lyrae stars vary in brightness primarily due to radial pulsations,such that contraction and expansion of their stellar surface produces a temperature variation that is observed as a change in their apparent stellar mag-1Experimental Astrophysics Group,Space SciencesLaboratory,University of California,Berkeley,CA 94720;wheat@,bwelsh@,ossy@,patj@.2Center for Space Astrophysics,Yonsei University,Seoul 120-749,Korea;byun@obs.yonsei.ac.kr,ywlee@csa.yonsei.ac.kr.3Department of Physics,Oxford University,Keble Road,Oxford OX13RH,UK;yi@.4Observatories of the Carnegie Institution of Washington,813Santa Barbara St.,Pasadena,CA 911015NASA/IPAC Extragalactic Database,California Institute of Technology,Mail Code 100-22,770S.Wilson Ave.,Pasadena,CA 91125;barry@.6Laboratoire d’Astrophysique de Marseille,BP 8,Tra-verse du Siphon,13376Marseille Cedex 12,France;mau-rice.viton@free.fr,jose.donas@oamp.fr,roger.malina@oamp.fr,liard@oamp.fr.7Department of Physics and Astronomy,University of Califor-nia,Los Angeles,CA 90095;rmr@.8Department of Physics and Astronomy,The Johns Hop-kins University,Homewood Campus,Baltimore,MD 21218;bianchi@,heckman@,sza-lay@.9California Institute of Technology,MC 405-47,1200East California Boulevard,Pasadena,CA 91125;tab@,krl@,friedman@,cmartin@,patrick@,ds@,tas@,wyder@.10Laboratory for Astronomy and Solar Physics,NASA Goddard Space Flight Center,Greenbelt,MD 20771;neﬀ@.nitude.This cyclic behavior has been well-observed for many thousands of these Population II stars,with an ap-parent magnitude variation of ∼0.3mag when observed at near infrared wavelengths and a variation of ∼1.0mag at visible wavelengths (Skillen et al.1993).Since the physical mechanism causing the brightness variation is the same for each RR Lyrae star,it follows that their absolute magnitudes are also similar and thus they pro-vide a useful tool for determining stellar distances.In addition,observation of their periodic variability can also provide important empirical tests of stellar pulsation and stellar atmosphere theory (Kurucz 2002;Mihalas 2003).Although the variation in apparent magnitude in the ultraviolet (UV)regime is far more pronounced (i.e.>2mag),observations of RR Lyrae stars for wavelengths <3000˚A are surprisingly sparse.The ﬁrst observa-tion of the UV light curve of an RR Lyrae star was reported by (Hutchinson,Hill,&Lillie 1977)using pho-tometry at 1550˚A gained with the OAO −2satel-lite.Since then,similar observations in the UV have been reported for RR Lyrae,X Arietis,W Virginis and several other bright variables using the ANS and IUE satellites (Bonnell et al.1982;Bonnell &Bell 1985;Bohm-Vitense,Proﬃtt,&Wallerstein 1984).In general,most of these data have been recorded at λ>1750˚A with an incomplete sampling over the whole phase of the stel-lar light curves.In this Letter we present observations well distributed in phase of the UV light curve of an RR Lyrae star,catalogued by the Robotic Optical Transient Search Experiment (ROTSE-I)as J143753.84+345924.82WHEATLEY et al.(Akerlof et al.2000).The Galaxy Evolution Explorer (GALEX)(Martin et al.2004)obtained simultaneous light curves in the wavelength ranges(1350-1750˚A) and(1750-2750˚A).2.OBSERVATIONS AND DATA REDUCTION GALEX observations of the star ROTSE-I J143753.84+345924.8(hereafter named R-J14+34.5), were obtained serendipitously during a15d interval in 2003July.The38exposures,most between1000-1700s duration,were part of the mission’s Deep Imaging Sur-vey program to map a region named NGP00near the north galactic pole.Data were collected in the form of time-tagged photon events in the far(1350-1750˚A) and near(1750-2750˚A)ultraviolet channels.These photons were then processed by the GALEX science data analysis pipeline(Morrissey,et al.2004)to produce a3840px square image(1.5arc sec px−1)for each of the UV detectors.Automated Source Extractor software (Bertin&Arnouts1996)subsequently detected sources and computed aperture photometry on them,resulting in an AB magnitude(Oke1974)in both the GALEX far (FUV)and near(NUV)ultraviolet wavebands.Table1 details the date,exposure time and GALEX magnitude for each observation.The ROTSE-I visible light curve consists of76obser-vations recorded over a95d interval,in1999March-June(Akerlof et al.2000).ROTSE magnitudes are de-rived from unﬁltered CCD images with a broad4500-10000˚A bandpass(Wozniak et al.2004),and we note that Blazhko amplitude modulation is not evident in the ROTSE-I data.To estimate the distance to R-J14+34.5,weﬁrst con-vert the mean m ROT SE to an m V,using the conversion factors of Amrose&McKay(2001).The distance to R-J14+34.5is estimated to be3.6±0.5kpc,derived using m ROT SE=13.78,m V=13.64,an absolute magnitude of M V=0.6and E(B-V)=0.09,taken from the reddening maps of Schlegel,Finkbeiner,&Davis(1998).3.DISCUSSIONIn Figure1we compare ROTSE-I and GALEX NUV and FUV observed light curves,phased using the Akerlof et al.(2000)period of0.564323±0.000058d. In the NUV,a variation of AB=1.8mag is observed, whereas in the FUV this variation is much more pro-nounced and reaches∼5mag.Measurement errors for these magnitudes are given in Table1and are typ-icallyσ≤0.01mag at NUV wavelengths and rise to σ=0.3mag at AB=23mag in the FUV.In order to model these observed light curves,we re-quire values of the stellar temperature and radius as a function of phase,together with values for stellar metallicity and surface gravity(g).Here we assume a mean log g=2.80,which Skillen et al.(1993)has de-rived for WY Antliae.Instrument response functions of both the GALEX(Morrissey,et al.2004)and ROTSE-I(Wozniak et al.2004;Apogee,Inc.2004)instruments are required to convert the calculated light curves to ob-served magnitudes.The values of stellar temperature and radius are nor-mally derived using visible and infrared photometry and spectroscopy using the Baade-Wesselink method.Such empirical data are unfortunately not available for R-J14+34.Instead,we use temperature and radius curves derived for the well-observed RR Lyrae star WY Antliae (Skillen et al.1993),which has a period of0.574330d, very close to that of R-J14+34.Furthermore,the Two Micron All Sky Survey(2MASS)(Cutri,et al.2003)ob-served the ROTSE star near maximum light,when the V-K color of0.62was very close to the V-K of0.59mea-sured by Skillen et al.(1993)for WY Antliae at maxi-mum light,a conﬁrmation that the two stars are physi-cally similar.We used the model atmosphere grid of Kurucz(2003) to compute the theoretical UV and visible light curves shown in Figure 1.These models use the updated OPAL opacities of Iglesias&Rogers(1996),and in-clude the eﬀects of quasi-molecular absorption by hy-drogen(Castelli&Kurucz2001)that occur near the the center of the GALEX FUV band.The mod-els,designated ODFNEW on the Kurucz web-site,in-corporate the“non-overshoot”convective treatment of Castelli,Gratton,&Kurucz(1997).In Figure2(top panel)we show the Kurucz pre-dicted UV and visible spectra at minimum and maximum brightness(i.e.T min=5900K and T max=7300K).We use Skillen’s(1993)WY Antliae metallicity of[Fe/H]=-1.25for the model atmosphere.In Figure2(bottom panel)we show the predicted diﬀerence between max-imum and minimum brightness for the1000-9000˚A region.We note a dramatic increase in amplitude in the UV region shortward of1700˚A that rises to AB>7mag. The steep increase inﬂux between1500-1800˚A is due to the photoionization edge of silicon at1656˚A and means that GALEX FUV observations of RR Lyrae stars are dominated by1750˚A photons where the amplitude is AB∼5mag.The GALEX NUV band is dominated by photons at wavelengths longer than2700˚A.In Figure2(bottom panel)we also show the eﬀect of metallicity on the amplitude of the predicted light curve. It is immediately noticeable that the GALEX NUV and FUV bands are a far more sensitive indicator of metal-licity than either the ROTSE-I visible orλ<1300˚A observations.This eﬀect can also be seen in Figure1 in which we have compared the observed ROTSE-I and GALEX light curve magnitudes with those derived from Kurucz model atmospheres using three values of metal-licity.We see that the bestﬁt to the far UV light curve occurs for[Fe/H]=-1.25,which is the value chosen by Skillen et al.(1993)for the star WY Antliae.The small residual diﬀerences between the observed and predicted UV light curves are probably due to temperature diﬀer-ences between R-J14+34.5and WY Antliae.We emphasize that the derived FUVﬂux is highly sen-sitive to a change in the Kurucz model atmosphere tem-perature of only100-200K,particularly around6000K at minimum brightness.A smaller temperature range ex-perienced during the star’s oscillation cycle would require a larger value of metallicity toﬁt the observed UV light curves.Our assumption of a constant surface gravity in-troduces far smaller errors:varying log g from2.5to3.0 makes a diﬀerence of less than0.1mag in the ROTSE-I and GALEX NUV light curves.The largest eﬀect is in the FUV,where the diﬀerence is less than0.25mag,com-pared with the amplitude of≈5mag,which is largelyRR Lyrae stars in the UV3caused by the temperature variation.Other potential sources of error in this analysis are the uncertainty in the GALEX FUV magnitudes at AB >22.0mag andthe uncertainty in the physical parameters derived by Skillen et al.(1993).Finally,we note that the high sensitivity and wide ﬁeld of view of the GALEX instrument will result in many more detections of variable sources during its UV imag-ing survey of the sky.In fact,preliminary detections have already been made for the RR Lyrae stars UU Indi and HL Herculis,in which respective variations in the NUV magnitude of AB =2.5mag and AB =1.8mag have been recorded.Kurucz model spectra suggest that Cepheids and other instability strip (T =6000-8000K)vari-able stars should also have large magnitude variations in the FUV.However,the advantage of observing this large ﬂux variation in the FUV is unfortunately oﬀset by the corresponding faintness in the FUV magnitude of these stars.Hence,their potential use as cosmic distance scale indicators may well be of limited practical value.GALEX is a NASA Small Explorer,launched in April 2003.We gratefully acknowledge NASA’s support for construction,operation,and science analysis for the GALEX mission,developed in cooperation with the Cen-tre National d’Etudes Spatiales of France and the Ko-rean Ministry of Science and Technology.The grat-ing,freedom window,and aspheric corrector were sup-plied by France.We acknowledge the dedicated team of engineers,technicians,and administrative staﬀfrom JPL/Caltech,Orbital Sciences Corporation,University of California,Berkeley,Laboratoire d’Astrophysique de Marseille,and the other institutions who made this mis-sion possible.Financial support for this research was provided by NASA grant NAS5-98034.This publication makes use of data products from the Two Micron All Sky Survey,which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology,funded by the National Aeronautics and Space Administration and the National Science Foundation.We are particularly grate-ful for the clariﬁcations and improvements suggested by an anonymous referee.Fig. 1.—Observed ROTSE-I and GALEX light curves of J143753.84+345924.8(ﬁlled circles).The vertical bars show 2σerrors.Predicted light curves are overlayed for [Fe/H]=-2.0(solid line);[Fe/H]=-1.25(dot-dash);[Fe/H]=-1.0(long dash);[Fe/H]=0.0(short dash).All four curves are nearly coincident in the ROTSE-I waveband.Fig. 2.—Top panel:Kurucz model spectra at maximum light (7300K)and minimum light (5900K),for [Fe/H]=-1.25and log g =2.80.The vertical axis is logarithmic.Bottom panel:Predicted amplitude of RR Lyrae light curve as a function of wavelength,for [Fe/H]=-2.0(thick line);[Fe/H]=-1.0(medium line);[Fe/H]=0.0(thin line).4WHEATLEY et al.REFERENCESAmrose,S.,&McKay,T.2001,ApJ,560,L151Akerlof,C.,Amrose,S.,Balsano,R.et al.2000,AJ,119,1901 Apogee,Inc.2004,/AP10.PDFBertin,E.,&Arnouts,S.1996,A&AS,117,393Bohm-Vitense,Proﬃtt,C.,&Wallerstein,G.1984,in Future ofUV Astronomy based on Six Years of IUE Research,NASA Conf. 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