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Development and characterization of a microflu.dic glu.ose sensing system b.sed on an enzymatic microreactor and chemilu.inescence detection

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Science China Chemistry 2012年第4期55卷 515-523页

作者： moon b.-u. de VRIES M.G. WESTERINK b.H.C. VERPOORTE E. b.omonitoring and Sensoring Department of Pharmacy University of Groningen Antonius Deusinglaan 1 9713AV Groningen The Netherlands Pharmaceu.ical Analysis Department of Pharmacy University of Groningen Antonius Deusinglaan 1 9713AV Groningen The Netherlands b.ains-on-Line PO Box 4030 9713AV Groningen The Netherlands

Chemilu.inescence detection was developed as an alternative to amperometric detection for glu.ose analysis in a portab.e, microflu.dicsb.sed continu.u. glu.ose monitoring system. Amperometric detection allows easy determination of hydrogen peroxide, a produ.t of the glu.ose oxidasecatalyzed reaction of glu.ose with oxygen, b. oxidation at a microelectrode. However, （micro）electrodes in direct contact with physiological sample are su.0}ect to electrode fou.ing, which leads to signal drift, decreased reprodu.ib.lity and shortened detector lifetimes. Moreover, there are a few species present in the b.dy （e.g. ascorb.c acid, u.ic acid） which can u.dergo oxidation at the same applied potential as hydrogen peroxide. These species can thu. inter- fere with the glu.ose measu.ement, redu.ing detection specificity. The rationale for exploring chemilu.inescence as opposed to amperometric detection is thu. to attempt to improve the lifetime and reprodu.ib.lity of glu.ose analysis for monitoring pu.poses, while redu.ing interference cau.ed b. other chemicals in the b.dy. The stu.y reported here represents a first step in this direction, namely the realization of a microflu.dic device with integrated silicon photodiode for chemilu.inescence detection of glu.ose. This microflow device u.es a chaotic mixing approach to perform enzymatic conversion of glu.ose, followed b. reaction of the hydrogen peroxide produ.ed with lu.inol to produ.e light at 425 nm. The chemil reaction is catalyzed b. horseradish peroxidase in the presence of iodophenol. The performance of the fab.icated chip was characterized to estab.ish optimal reaction conditions with respect to sample and reagent flow rates, pH, and concentrations. A linear calib.a- tion cu.ve was ob.ained for cu.rent response as a fu.ction of glu.ose concentration in the clinically relevant range b.tween 2 and 10 mM, with a sensitivity of 39 pA/mM （R = 0.9963, one device, n = 3） and a limit of detection of 230 ktM （S/N - 3）.

关键词： microflu.dic chip – glu.ose sensing system – enzymatic microreactor – chemilu.inescence – chaotic mixing

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Indentation Size Effect and Microhardness Stu.y of β-Sn Single Crystals

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Chinese Physics Letters 2005年第12期22卷 3137-3140页

作者： O. SAHIN O. u.u. u. KOLEMEN b. Du.Gu. N. u.AR Department of Physics Art and Science Faculty Suleyman Demirel University Isparta Turkey Department of Physics Art and Science Faculty Gaziosmanpasa University Tokat Turkey Department of Physics K. K. Education Faculty Ataturk-University Erzurum Turkey

The load dependence of apparent microhardness of β-Sn single crystals having different growth directions is investigated. The measu.ements are performed on （110） planes of these crystals in the load range from 10 to 50 mN. It is fou.d that the degree of the microhardness anisotropy decreases for higher indentation test loads. The examined materials exhib.t the b.haviou. of indentation size effect （ISE）, i.e., the apparent hardness increases with decreasing indentation load. Neither Meyer＇s law nor the proportional specimen resistance （PSR） model can fu.ly explain the nonlinear variation of microhardness with load. Instead, preference is given to modified the PSR model b.sed on the consideration of the effect of machining-indu.ed residu.lly stressed su.face on the hardness measu.ement.

关键词： Microhardness

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Nu.erical investigations of arc b.haviou. in gas metal arc welding u.ing ANSYS CFX

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Frontiers of Materials Science 2011年第2期5卷 98-108页

作者： M. SCHNICK u. Fu.SSEL M. HERTEL A. SPILLE-KOHOFF A. b. Mu.PHY Institu.e of Su.face and Manu.actu.ing Technology Technische Universitat Dresden Dresden Germany CFX b.rlin Software Gmb. Berlin Germany CSIRO Materials Science and Engineering Lindfield NSW 2070 Australia

Cu.rent nu.erical models of gas metal arc welding（GMAW）are trying to comb.ne magnetohydrodynamics （MRD） models of the arc and voiu.e of flu.d （VoF） models of metal transfer They neglect vaporization and assu.e an argon atmosphere for the arc region, as it is common practice for models of gas tu.gsten arc welding, These models predict temperatu.es ab.ve 20 000K anda temperatu.e distrib.tion similar to tu.gsten inert gas （TIG） arcs： However. cu.rent spectroscopic temperatu.e measu.etemperatu.es. In contrast to TIG arcs temperatu.e distrb.tion. The paper vapou. and which is in a yery good res, Fu.hermore; the model is ab.le to predict the local central minimu. in the radial temperatu.e and the radial electric cu.rent density distrib.tions for the first time. The axially symmetric model of the welding torch, the work piece, the wire and the arc （flu.d domain） implements MHD as well as tu.b.lent mixing and thermal demixing of metal vapou. in argon. The mass fraction of iron vapou. ob.ained from the simu.ation shows an accu.u.ation in the arc core and another accu.u.ation on the fringes of the arc at 2000 to 5000 K. The demixing effects lead to very low concentrations of iron b.tween these two regions. Sensitive analyses demonstrate the influ.nce of the transport and radiation properties of metal vapou., and the evaporation rate relative to the wire feed. Finally the model predictions are compared with the measu.ing resu.ts of Zielihska et al.

关键词： arc welding nu.ericai simu.ation GMAW, ANSYS CFX

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Wave scattering b. u.du.ating b.d topography in a two-layer ocean

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Jou.nal of Marine Science and Application 2009年第3期8卷 183-195页

作者： P. MAITI b. N. MANDAL u. b.Su Department of Mathematics Jadavpur University Physics and Applied Mathematics u.it Indian Statistical Institute Department of Applied Mathematics Calcutta University

The prob.em of wave scattering b. u.du.ating b.d topography in a two-layer ocean is investigated on the b.sis of linear theory. In a two-layer flu.d with the u.per layer having a free su.face, there exist two modes of waves propagating at b.th the free su.face of the u.per layer and the interface b.tween the two layers. Du. to a wave train of a particu.ar mode incident on an ob.tacle which is b.ttom-standing on the lower layer, reflected and transmitted waves of b.th modes are created b. the ob.tacle. For small u.du.ations on the b.ttom of the lower layer, a pertu.b.tion method is employed to ob.ain first-order reflection and transmission coefficients of b.th modes for incident wave trains of again b.th modes in terms of integrals involving the b.d-shape fimction. For sinu.oidal u.du.ations, nu.erical resu.ts are presented graphically to illu.trate the energy transfer b.tween the waves of different modes b. the u.du.ating b.d.

关键词： two-layer ocean wave scattering b.ttom u.du.ations reflection and transmission coefficients

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Scenario Analysis of Tillage, Residu. and Fertilization Management Effects on Soil Organic Carb.n Dynamics

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Pedosphere 2005年第4期15卷 473-483页

作者： WANG Xiao-b.n CAI Dian-Xiong W. b. HOOGMOED O. OENEMA u. D. PERDOK Soil and Fertilizer Institu.e Chinese Academy of Agricultural Sciences Beijing 100081 （China） Soil Technology Grou. Wageningen University P. O. Box 17 6700 AA Wageningen （The Netherlands） Soil Qu.lity Grou. Wageningen University P. O. Box 8005 6700 EC Wageningen （The Netherlands）

b.sed on data from 10-year field experiments on residu./fertilizer management in the dryland farming region of northern China, Centu.y model was u.ed to simu.ate the site-specific ecosystem dynamics throu.h adju.tment of the model＇s parameters, and the applicab.lity of the model to propose soil organic carb.n （SOC） management temporally and spatially, in cases su.h as of tillage/residu./fertilization management options, was identified v/a scenario *** b.tween simu.ations and actu.l measu.ements were in close agreement when appropriate applications of stover,manu.e and inorganic fertilizer were comb.ned. Simu.ations of extreme C/N ratios with added organic materials tended to u.derestimate the measu.ed effects. Scenarios of changed tillage methods, residu. practices and fertilization options showed potential to maintain and enhance SOC in the long ru., while increasing inorganic N slowed down the SOC tu.nover rate b.t did not create a net C sink withou. any organic C inpu.. The Centu.y model simu.ation showed a good relationship b.tween annu.l C inpu.s to the soil and the rate of C sequ.stration in the top 20 cm layer and provided qu.ntitative estimations of changes in parameters cru.ial for su.tainab.e land u.e and management. Conservation tillage practices for su.tainab.e land u.e shou.d b. integrated with residu. management and appreciab.e organic and inorganic fertilizer application, adapted according to the local residu. resou.ce, soil fertility and produ.tion conditions. At least 50% residu. retu.n into the soil was needed annu.lly for maintenance of SOC b.lance, and manu.e amendment was important for enhancement of SOC in small crop-livestock systems in which crop residu. land application was limited.

关键词： Centu.y model conservation tillage crop residu. dryland soil organic carb.n

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