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Surface Characterisation of Silicon Based m.m.

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Chem.cal Research in Chinese Universities 2004年第4期20卷 407-410页

作者： LI j. CUI Z m. A. Baker The Surface Analysis Laboratory School of Engineering University of SurreyRutherford Appleton LaboratoryThe Surface Analysis Laboratory School of Engineering University of Surrey Guildford GU2 7XH UKChilton Didcot UKGuildford GU2 7XH UK

Polysilicon m.croelectrom.chanical system.(m.m.) are the subj.ct of intensive researches. Surface chem.stry and topography of a m.m. test structure fabricated at Sandia National Laboratory, USA, were studied by m.ans of scanning electron m.croscopy(SEm., X-ray photoelectron spectroscopy(XPS) and atom.c force m.croscopy(AFm.. XPS C_ 1sand Si_ 2pspectra from.the polysilicon com.onents, silicon nitride substrate and a reference silicon wafer were com.ared. The results confirm.the presence of a self-assem.led m.nolayer(SAm. on the m.m. surface. An island-like m.rphology was found on both polysilicon and silicon nitride surfaces of the m.m.. The islands take the form.of caps, being up to 0.5 μm.in diam.ter and 20 nm.in height. It is concluded that the co-existence of colum.ar growth and equiaxed growth during the low pressure chem.cal vapor deposition(LPCVD) of these layers leads to the observed m.rphology and the islands are caps to the colum.ar structures.

关键词： m.croelectrom.chanical system. XPS Atom.c force m.croscopy

Interferom.try Signatures for QCD First-Order Phase Transition in High Energy Heavy Ion Collisions

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Chinese Physics Letters 2010年第2期27卷 69-72页

作者：于莉莉 m. j. Efaaf 张卫宁 Departm.nt of Physics Harbin Institute of Technology Harbin 150006 School of Physics and Optoelectronic Technology Dalian University of Technology Dalian 116024 Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000

Using the technique of quantum.transport of the interfering pair we exam.ne the Hanbury-Brown-Twiss （HBT） interferom.try signatures for the particle-em.tting sources of pions and kaons produced in heavy ion collisions at 10-30 AGeV. The evolution of the sources is described by relativistic hydrodynam.cs with the first-order phase transition from.quark-gluon plasm. （QGP） to hadronic m.tter. We use quantum.probability am.litudes in a path-integral form.lism.to calculate the two-particle correlation functions, where the effects of particle decay and m.ltiple scattering are taken into consideration. Our m.del-calculated results indicate that both the HBT radii of pions and kaons increase with the system.initial energy density. The HBT lifetim.s of the pion and kaon sources increase significantly when the initial energy density is tuned to the phase boundary between the QGP and m.xed phase. This increase of HBT lifetim.s will likely appear in heavy ion collisions with an incident energy between 10-30 AGeV.

关键词： Nuclear physics

Far-infrared absorption studies of Be acceptors in δ-doped GaAs/AlAs m.ltiple quantum.wells

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Science China(Physics,m.chanics & Astronom.) 2006年第6期49卷 702-708页

作者： m. P. Halsall P. Harrison m. j. Steer School of Physics and Astronom. the University of ManchesterManchester M60 1QD U. K. School of Electronic and Electrical Engineering University of LeedsLS2 9JT U. K. EPSRC Ⅲ-V Sem.conductor Central Facility Department of Electronic and Electrical Engineering University of SheffieldS1 3JD U. K.

We report a far-infrared absorption study of internal transitions of shallow Be acceptors in both bulk GaAs and a series of δ-doped GaAs/AlAs m.ltiple quantum.well sam.les with well thicknesses of 20,15 and 10 nm. Low tem.erature far-infrared absorp-tion m.asurem.nts clearly show three principal absorption lines due to transitions of Be-acceptor states from.the ground state to the first three odd-parity excited states,respec-tively. Using a variational principle,the 2p-1s transition energies of quantum.confined Be acceptors are calculated as a function of the well width. It is found that the theoretical calculation of the 2pz → 1s transitions is in good agreem.nt with the D-like line experi-m.ntal data.

关键词： shallow acceptor im.urities,δ-doped,GaAs/AlAs m.ltiple quantum wells,far-infrared absorptions.

Habitat structure directly affects aggression in convict cichlids Archocentrus nigrofasciatus

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Current Zoology 2010年第1期56卷 52-56页

作者： Anthony j. BARLEY Ronald m. COLEm.N Departm.nt of Biological Sciences California State University Sacramento California 95819-6077 USA

Aggressive behavior can be an im.ortant factor in determ.ning how anim.ls use and divide space and resources. Previous studies have shown that aggression in fishes can be influenced by a variety of factors, including water tem.erature and resource levels. In this study, we tested if the am.unt of habitat structure in the environm.nt affected aggression levels in fem.le convict cichlids Archocentrus nigrofasciatus. We perform.d a laboratory experim.nt in which we placed fem.le convict cichlids into an aquarium.with low or high am.unts of habitat structure and m.nitored the dom.nant fem.le＇s behavior toward the subordinate fem.le. Aggressive behavior in convict cichlids prim.rily consists of chases and bites. We found that the total tim. the dom.nant fem.le spent chasing the subordinate fem.le was greater when there was a low am.unt of habitat structure as com.ared to when there was a high am.unt of habitat structure. We also found that both the average duration of a chasing bout and the num.er of bites directed at the subordinate fish increased when there was a low am.unt of structure, but the num.er of chases did not. These results indicate that increased habitat structural com.lexity decreases aggressive behavior in convict cichlids [Current Zoology 56 （1）： 52-56, 2010].

关键词： Neotropical Life-history Fem.le-fem.le com.etition Fish Resource com.etition

Electronic Ram.n scattering in double sem.-parabolic quantum.wells

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Chinese Physics B 2013年第5期22卷 523-526页

作者： N. Zam.ni A. Keshavarz m. j. Karim. Departm.nt of Physics College of SciencesShiraz University of Technology

The differential cross-section for electronic Ram.n scattering in double sem.-parabolic quantum.wells of typical GaAs/AlxGa1-xAs is investigated num.rically with the effective-m.ss approxim.tion. The dependence of the differential cross-section on structural param.ters such as the barrier width and the well widths is studied. Our results indicate that the electronic Ram.n scattering is affected by the geom.trical size and can be negligible in the sym.etric double-well case.

关键词： electronic Ram.n scattering double sem.-parabolic quantum.wells

Purification of L-asparaginase II by crystallization

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Frontiers of Chem.cal Science and Engineering 2013年第1期7卷 37-42页

作者： Y. LIU m. PIETZSCH j. ULRICH Therm.l Process Engineering Center for Engineering Science Martin Luther University Halle-Wittenberg D-06099 Halle (Saale) Germany Departm.nt of Downstream.Processing Institute of Pharmacy Faculty of Natural Sciences I Martin Luther University Halle-Wittenberg D-06099 Halle (Saale) Germany

Here a case study ofL-asparaginase II out of a recom.inant Escherichia coli is presented. The target protein was obtained by sim.le cell disintegration and acetone precipitation. The L-asparaginase II has been crystallized in three different form. in the following m.crobatch crystallization. The rod-shaped crystals （-400 μm.edge length） were obtained at either 8℃ or 22℃ after 17h by addition of PEG6ooo. The rectangular-shaped crystals were obtained after further recrystallization of the rod-shaped crystals. The rhom.ic-shaped crystals form.d at 8℃ after 12 days when cold ethanol was used instead of PEG6000. All crystallizations were perform.d in tris-acetate buffer （50m.ol-L-1, pH 5.1）. By crystallization, the specific activity of L-asparaginase II has increased 5-fold. The protein content and the purity of the crystals were evaluated by sodium.dodecyl sulfate polyacrylam.de gel electrophoresis （SDS-PAGE）. The m.re concentrated L- asparaginase II out of an extract m.xture and the presence of only less m.nor proteins after crystallization dem.nstrates that crystallization is an effective and m.ld m.thod to purify the target protein. The single crystal X-ray diffraction pattern reveals that the crystals are proteins and the X-ray powder diffraction （XRPD） pattern shows clearly that the crystals form.ng in PEG600o and ethanol have different crystal structures.

关键词： protein crystallization L-asparaginase II purification

m.crostructure, m.chanical Properties and Wear Behaviourof Deep-Cryogenic-Treated HSS

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材料热处理学报 2004年第5期25卷 540-545页

作者： V. Leskovek m. Kalin j. Vi■intin Institute of m.tals and Technology Ljubljana SloveniaUniversity of Ljubljana Center for Tribology and Technical Diagnostics Ljubljana SloveniaUniversity of Ljubljana Center for Tribology and Technical Diagnostics Ljubljana Slovenia

In this paper we com.are the wear behaviour of a vacuum.heat-treated ESR AISI m. high-speed steel and the sam. steel that was vacuum.heat treated in conj.nction with a deep-cryogenic treatm.nt at -196 °C. Four different tem.ering tem.eratures for the specim.ns austenized at the sam. austenitizing tem.erature were carefully selected to obtain various in-advance-determ.ned com.inations of the m.crostructures, the fracture toughness, KIc and the Rockwell-C hardness. Each of the eight specim.ns was therefore characterised by these m.crostructures and resulting m.terial properties. The wear study was perform.d using a reciprocating sliding device under well-controlled contact conditions. Relatively high loads were used to provide enough wear for a com.arison of the selected sam.les. A m.ch harder and dissim.lar m.del counter-m.terial, i.e. silicon nitride ceram.c, was used in order to avoid excessive wear of the counter sam.les and adhesion, which could occur in contacts with sim.lar m.terials (m.tals/steels) under such high loads and in non-lubricated conditions. The wear behaviours were then com.ared and discussed in term. of these m.crostructures and the related properties. The differences in the wear resistance obtained in our investigation were as high as an order of m.gnitude. However, the beneficial effects are not a direct result of the type of the treatm.nt, but relate to a proper com.ination of the resulting fracture toughness and the hardness. The m.re uniform.and m.derate values, which, however, tend to be obtained with a deep-cryogenic treatm.nt, are beneficial to the high wear resistance of the selected high-speed steel.

关键词：高速钢显微结构深低温处理机械性质磨损性能

m.untain Water Tower and Ecological Risk Estim.tion of the m.sta-Nestos Transboundary River Basin (Bulgaria-Greece)

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j.urnal of m.untain Science 2007年第3期4卷 209-220页

作者： K. Grunewald j. Scheithauer j.-m. m.nget N. Nikolova Landscape Research Centre Dresden Ecole des m.nes de Paris South-West University Blagoevgrad

The m.sta-Nestos river basin in Bulgaria and Greece is a case study for transboundary decision-m.king support in south-eastern Europe and a show-case for the developm.nt of m.thodologies and inform.tion-gathering for the integrated regional planning of water resources. Land-use conflicts in this water-scarce region cover a wide spectrum.of activities like agricultural irrigation, drinking water production, diversions for industrial water, and risk of pollution from.m.ning, to nam. a few exam.les. m.asurem.nts of the water quality were carried out in the upper basin. Results will be illustrated by the exam.le of the environm.ntal situation in the alpine region of the Pirin National Park as well as in the Razlog Basin with a stronger anthropogenic im.act and pollution around a form.r uranium.m.ne near the village of Elesnica. The social and econom.c developm.nt of this transboundary region is a recently established priority for m.an an increase in water usage the water resources if regional the future. It will and m.re stress for im.acts of global clim.te change are verified. Problem.focused m.nagem.nt of the catchm.nt area as a whole on the basis of proved geo-data sets is needed for the future.

关键词： Environm.nt interactions nutrients pollutants resource m.nagem.nt Southeast Europe uranium water quality Pirin high m.untains

Light m.tal com.ound casting

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Science China(Technological Sciences) 2009年第1期52卷 46-51页

作者： Konrad j. m. PAPIS j.erg F. LOEFFLER Peter j. UGGOWITZER ETH Zurich Laboratory of Metal Physics and Technology Wolfgang-Pauli-Str. 10

‘Com.ound casting’sim.lifies j.ining processes by directly casting a m.tallic m.lt onto a solid m.tal substrate. A continuously m.tallurgic transition is very im.ortant for industrial applications, such as j.int structures of spacefram. constructions in transport industry. In this proj.ct, ‘com.ound casting’ of light m.tals is investigated, aim.ng at weight-saving. The substrate used is a wrought alum.nium.alloy of type AA5xxx, containing m.gnesium.as m.in alloying elem.nt. The m.lts are alum.nium.alloys, containing various alloying elem.nts (Cu, Si, Zn), and m.gnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and com.ounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron m.croscopy and EDX investigations as well as optical m.crographs of the interfacial areas revealed their continu- ously m.tallic constitution. Diffusion of alloying elem.nts leads to heat-treatable m.crostructures in the vicinity of the j.ining interfaces in Al-Al couples. This perm.ts significant variability of m.chanical properties. Without significantly cutting down on wettability, the form.tion of low-m.lting interm.tallic phases (Al3m.2 and Al12m.17 Im.s) at the interface of Al-m. couples was avoided by applying a protective coating to the substrate.

关键词： com.ound casting alum.nium alloys m.gnesium alloys interface structure