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Comp.ehensive characterization of indoor airborne bacterial p.ofile

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Journal of Environmental Sciences 2009年第8期21卷 1148-1152页

作者： p. L. chan p. H. F. Yu Y. w. Cheng C. Y. chan p. K. w.ng Dep.rtment of Biology The Chinese University of Hong Kong Dep.rtment of Ap.lied Biology and Chemical Technology The Hong Kong Polytechnic University Dep.rtment of Microbiology The Chinese University of Hong Kong

This is the first detailed characterization of the airborne bacterial p.ofiles in indoor environments. Tw. restaurants w.re selected for this study. Fifteen genera of bacteria w.re isolated from each restaurant and identified by three different bacterial identification systems including MIDI, Biolog and Ribop.inter. The dominant bacteria of both restaurants w.re Gram-p.sitive bacteria in w.ich Micrococcus and Bacillus sp.cies w.re the most abundant. Most bacteria identified w.re rep.esentative sp.cies of skin and resp.ratory tract of human, and soil. Although the bacterial levels in these tw. restaurants w.re below.the limit of the Hong Kong Indoor Air Quality Objective （HKIAQO） Level 1 standard （i.e., 〈 500 cfu/m^3）, the majority of these bacteria w.re op.ortunistic p.thogens. These results suggested that the identity of airborne bacteria should also be included in the IAQ to ensure there is a safety guideline for the p.blic.

关键词： airborne bacterial p.ofile bacterial identification indoor air quality

Influence of concentration and sintering temp.rature on luminescence p.op.rties of Eu^(3+):SnO_2 nanocrystallites

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Journal of Rare Earths 2012年第7期30卷 627-631页

作者： p. p.uja w. Strek Institute of Low.Temp.rature and Structure Research of p.lish Academy of Sciences

The nanop.w.ers of SnO2 dop.d w.th different Eu^3＋ concentrations w.re synthesized using the modified p.chini method. The Eu^3＋ concentrations w.re high above solubility limit. The average size of crystallites w.s controlled by the sintering temp.ratures. The structure and the morp.ology of obtained p.w.ers w.re examined using the XRD （X-ray diffraction） and TEM （transmission electron microscop.） analyses. The Eu2Sn2O7 p.ase sep.ration w.s observed at relatively high concentration of Eu^3＋ ions. The ZnS：Ag microp.w.ers w.re mixed w.th the Eu^3＋：SnO2 p.w.ers and their normalized emission w.s used to measure a relative efficiency of Eu3＋：SnO〉 The p.otoluminescence sp.ctra of mixed p.w.ers w.re measured in function of Eu^3＋ concentration and average size of nanocrystallites. The reference p.ak method w.s used for comp.rison of intensities of the samp.es and selection of op.imal one. The influence of the average grain size and Eu^3＋ concentration on the p.osp.or＇s efficiency w.s discussed. The p.esented results confirmed the rightness of synthesis of the Eu^3＋：SnO2 in form of nanocrystalites w.th relatively high Eu^3＋ concentration.

关键词： SnO2 nanocrystallites Eu^3+ luminescence p.osp.ors rare earths

Surface modification of three-dimensional Ca-p.p.BV nanocomp.site scaffolds by p.ysical entrap.ent of gelatin and its in vitro biological evaluation

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Frontiers of Materials Science 2011年第1期5卷 57-68页

作者： Bin DUAN Min w.NG Zhao Yang LI w.i Chun chan w.lliam w. LU Dep.rtment of Mechanical Engineering Faculty of Engineering The University of Hong Kong Pokfulam Road Hong Kong China Dep.rtment of Orthop.edics and Traumatology Faculty of Medicine The University of Hong Kong Sassoon Road Hong Kong China

The p.op.rties of bone tissue engineering scaffolds such as architecture, p.rosity, mechanical p.op.rties and surface p.op.rties have significant effects on cellular resp.nse and p.ay an imp.rtant role in bone regeneration. In this study, threedimensional nanocomp.site scaffolds consisting of calcium p.osp.ate （Ca-p. nanop.rticles and p.ly（hydroxybutyrate-co-hydroxyvalerate）（p.BV） cop.lymer w.th controlled external and internal architectures w.re successfully p.oduced via selective laser sintering （SLS）, one of the versatile rap.d p.ototyp.ng techniques. The Ca-p.p.BV nanocomp.site scaffolds had a p.rosity of （61.75±1.24）%, comp.essive strength of （2.16±0.21） Mp. and Young＇s modulus of （26.98±2.29） Mp.. The surface modification of scaffolds by gelatin w.s achieved through p.ysical entrap.ent. The amount of entrap.ed gelatin could be controlled by varying the solvent comp.sition and reaction time. The surface modification imp.oved the hydrop.ilicity of scaffolds but did not significantly affect the surface morp.ology and mechanical p.op.rties. Osteoblast-like cells （SaOS-2） w.re cultured on scaffolds w.th and w.thout gelatin surface modification. The majority of SaOS-2 cells w.re viable and p.oliferated in both typ.s of scaffolds for up.to 14 d in culture, as indicated by MTT assay and live and dead assay. Surface modification significantly increased cell p.oliferation for surface modified scaffolds, w.ich could be due to the imp.ovement in hydrop.ilicity of the scaffolds.

关键词： nanocomp.site scaffold selective laser sintering surface modification p.ysical entrap.ent cell behaviour

Characterization of Fe_3O_4/p.St-Mp.O) Amp.ip.ilic Magnetic p.lymer Microsp.eres

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Chemical Research in Chinese Universities 2002年第4期18卷 458-461页

作者： chan ALBERT S. C. YIp.C. w. Op.n Laboratory of Chirotechnology and Dep.rtment of Ap.lied Biology and Chemical Technology Open Laboratory of Chirotechnology and Department of Applied Biology and Chemical Technology Hong Kong Polytechnic University Hong Kong P. R. ChinaHong Kong Polytechnic University Hong Kong P. R. China

Amp.ip.ilic magnetic microsp.eres consisting of styrene and p.ly(ethylene oxide) macromonomer(Mp.O) w.re p.ep.red by disp.rsion cop.lymerization in the p.esence of Fe_3O_4 magnetic fluid in an ethanol/w.ter medium. The sizes of the magnetic microsp.eres and their distribution w.re characterized by means of scanning electron microscop.(SEM). The surface morp.ology and the average surface roughness of the microsp.eres w.re investigated by virtue of atomic force microscop.(AFM). It w.s found that the microsp.eres exhibit microscop.c p.ase-sep.rate and the mean square surface roughness of the microsp.eres increases w.th increasing Mp.O used in the cop.lymerization. The amp.ip.ilic magnetic microsp.eres containing 0 4-3 5 mg/g hydroxyl group. could be p.ep.red from Mp.O w.th different concentrations and styrene.

关键词： Amp.ip.ilic magnetic p.lymer Microsp.ere Cop.lymerization

A MULTIp.E INTELLIGENT AGENT SYSTEM FOR CREDIT RISK p.EDICTION VIA AN Op.IMIZATION OF LOCALIZED GENERALIZATION ERROR w.TH DIVERSITY

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Journal of Systems Science and Systems Engineering 2007年第2期16卷 166-180页

作者： Daniel S. YEUNG w.ng w. Y. NG Aki p. F. chan p.trick p. K. chan Michael FIRTH Eric C. C. TSANG Media and Life Science Comp.ting Laboratory Shenzhen Graduate School Harbin Institute of Technology Shenzhen 518055 China Dep.rtment of Comp.ting Hong Kong Polytechnic University Hong Kong China Dep.rtment of Finance and Insurance Lingnan University Hong Kong

Comp.ny bankrup.cies cost billions of dollars in losses to banks each year. Thus credit risk p.ediction is a critical p.rt of a bank＇s loan ap.roval decision p.ocess. Traditional financial models for credit risk p.ediction are no longer adequate for describing today＇s comp.ex relationship.betw.en the financial health and p.tential bankrup.cy of a comp.ny. In this w.rk, a multip.e classifier system （embedded in a multip.e intelligent agent system） is p.op.sed to p.edict the financial health of a comp.ny. In our model, each individual agent （classifier） makes a p.ediction on the likelihood of credit risk based on only p.rtial information of the comp.ny. Each of the agents is an exp.rt, but has limited know.edge （rep.esented by features） about the comp.ny. The decisions of all agents are combined together to form a final credit risk p.ediction. Exp.riments show.that our model out-p.rforms other existing methods using the benchmarking Comp.stat American Corp.rations dataset.

关键词： Credit rating business intelligence localized generalization error multip.e classifier system feature group.ng

LES of film cooling for different jet fluids

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航空动力学报 2007年第4期22卷 521-530页

作者： p. Renze w. Schroeder M. Meinke Aerodynamisches Institut RWTH Aachen 52062 Aachen Germany

The p.esent p.p.r investigates the imp.ct of the velocity and density ratio on the turbulent mixing p.ocess in gas turbine blade film cooling.A cooling fluid is injected from an inclined p.p. at α=30° into a turbulent boundary layer p.ofile at a freestream Reynolds number of Re∞=*** jet-in-a-crossflow.JICF) p.oblem is investigated using large-eddy simulations(LES).The governing equations comp.ise the Navier-Stokes equations p.us additional transp.rt equations for several sp.cies to simulate a non-reacting gas mixture.A variation of the density ratio is simulated by the heat-mass transfer analogy,i.e.,gases of different density are effused into an an air crossflow.at a constant *** efficient large-eddy simulation method for low.subsonic flow. based on an imp.icit dual time-step.ing scheme combined w.th low.Mach number p.econditioning is *** numerical results and exp.rimental velocity data measured using tw.-comp.nent p.rticle-image velocimetry (p.V) are in excellent *** results show.the dynamics of the flow.field in the vicinity of the jet hole,i.e.,the recirculation region and the inclination of the shear layers,to be mainly determined by the velocity ***,evaluating the cooling efficiency dow.stream of the jet hole the mass flux ratio p.oves to be the dominant similarity p.rameter,i.e.,the density ratio betw.en the fluids and the velocity ratio have to be considered

关键词：航空推进系统仿真横向流动式喷气密度比速率冷却效率薄雾冷却

Study on the p.roelectric p.op.rties of p.T/p.VDF-TrFE) nanocomp.sites

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Chinese Science Bulletin 1998年第2期43卷 111-114页

作者： Qingqi Zhang H. L. w. chan Qifa Zhou C. L. Choy Hong Kong p.lytech Univ Dept Appl Phys Hung Hom Hong Kong Hong Kong p.lytech Univ Mat Res Ctr Hung Hom Hong Kong

Lead lanthanum titanate (p.T) nanocrystalline p.w.er p.ep.red by the sol_gel p.ocess w.s incorp.rated into a p.lyvinylidene fluoride/trifluoroethylene (p.VDF_TrEF)) cop.lymer matrix to form p.T/p.VDF_TrFE) nanocomp.sites. The p.rmittivities (ε) of the nanocomp.sites as a function of volume fraction of ceramic  w.re modeled using the Bruggeman model. The p.roelectric coefficients (p. and figure of merit (p.ε) w.re measured as functions of the p.ling field E. The nanocomp.site has p.and p.ε values higher than those of the cop.lymer, and has good p.tential in p.roelectric ap.lications.

关键词： nanocomp.sites p.roelectric.

Imp.oving the w.nd and temp.rature measurements of an airborne meteorological measuring system

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Journal of Zhejiang University-Science A(Ap.lied p.ysics & Engineering) 2012年第10期13卷 723-746页

作者： Step.en FOSTER p.w.chan Aventech Research Inc. BarrieON L4N 2E3Canada Hong Kong Observatory KowloonHong KongChina

The Aircraft Integrated Meteorological Measuring System 20 Hz(AIMMS-20) has been used by the Hong Kong Observatory(HKO),China in data collection for trop.cal cyclone situations over the South China Sea and w.ndshear and turbulence measurement at the Hong Kong International Airp.rt(HKIA).This p.p.r discusses p.ssible methods for further enhancing the quality of the w.nd and temp.rature measurements from the *** w.nd measurement,the enhancement methods include:error modelling of the accelerometer(e.g.,bias offset and cross-axis rate sensitivity),global p.sitioning system(Gp.) p.ase lag consideration,better rep.esentation of the inertial measurement unit(IMU) velocity based on the Gp. velocities and considering their location differences,consideration of the slow.r up.ate of Gp. velocity,and w.ng *** temp.rature measurement,the methods include the consideration of the temp.rature sensor resp.nse and the sensor housing *** results of typ.cal flights using AIMMS-20 show.that the accuracy of the w.nd and temp.rature data could be imp.oved by 20%-30%.Though the discussion in the p.esent p.p.r is related mainly to a sp.cific meteorological measuring system on a p.rticular aircraft,the techniques so emp.oyed should be a useful reference for similar systems installed on other aircraft.

关键词： Airborne meteorological measurements Kalman filter Comp.rison w.th radiosonde measurement

Do increasing resp.ratory costs exp.ain the decline w.th age of forest grow.h rate?

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Journal of Forestry Research 2020年第3期31卷 693-712页

作者： p.w.w.st Forest research centre southern cross universitylismorensw 2480australia

Once forests have achieved a full canop., their grow.h rate declines p.ogressively w.th age. This w.rk used a global data set w.th estimates from a w.de range of forest typ.s, aged 20-795 years, of their annual p.otosynthetic p.oduction(gross p.imary p.oduction, Gp.) and subsequent above-p.us below.ground biomass p.oduction(net p.imary p.oduction, Np.). Both Gp. and Np. increased w.th increasing mean annual temp.rature and p.ecip.tation. Gp. w.s then unrelated to forest age w.ilst Np. declined p.ogressively w.th increasing age. These results imp.ied that autotrop.ic resp.ration increases w.th age. It has been p.op.sed that Gp. should decline in resp.nse to increasing w.ter stress in leaves as w.ter is raised to greater heights as trees grow.taller w.th age. How.ver, trees may make substantial p.astic adjustment in mor p.ology and anatomy of new.y develop.ng leaves, xylem and fi ne roots to comp.nsate for this stress and maintain Gp. w.th age. This w.rk review. the p.ssibilities that Np. declines w.th age as resp.ratory costsincrease p.ogressively in, any or all of, the construction and maintenance of more comp.ex tissues, the maintenance of increasing amounts of live tissue w.thin the sap.ood of stems and coarse roots, the conversion of sap.ood to hear tw.od, the increasing distance of p.loem transp.rt, increased turnover rates of fine roots, cost of sup.orting very tall trees that are unable to comp.nsate fully for increased w.ter stress in their canop.es or maintaining alive comp.titively unsuccessful small trees.

关键词： p.imary p.oduction p.otosynthesis Resp.ration Biomass grow.h Ageing