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PREPARATION OF POLYETHERsULFONE ULTRAFILTRATION MEMBRANEs FOR MILK CONCENTRATION AND EFFECTs OF ADDITIVEs ON THEIR MORPHOLOGY AND PERFORMANCE

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Chinese Journal of Polymer science 2005年第5期23卷 539-548页

作者： s.s.Madaeni A.Rahimpour Department Of Chemical Engineering Razi University KermanshahIran

Polyethersulfone membranes were prepared from quaternary systems containing N,N-dimethylacetamide （DMAc） as solvent, polyvinylpyrrolidone （PVP） as constant additive and acetic acid, acetone and water as variable additives. Phase inversion via immersion precipitation was employed for manufacturing of membranes. The prepared films were immersed in the mixture of pure water and 2-propanol （30/70 vol%） as the non-solvent. Acetic acid caused an increment in the flux at high polymer concentration （16 wt%） and a decline in the flux at low polymer concentrations （10 wt% and 13 wt%）. Acetone and water as the solvent in the casting solution declined the flux at any polymer concentration tested. The morphology and performance of the prepared membranes were investigated by scanning electron microscopy and separation experiments using milk as the feed.

关键词： Membrane Ultrafiltartion Polyethersulfone Phase inversion Milk.

Field-dependent resistive transitions in YBa_2Cu_3O_(7-δ) thin films:Influence of the pseudogap on vortex dynamics

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Chinese Physics B 2015年第1期24卷 467-473页

作者： s H Naqib R s Islam Department of Physics University of RajshahiRajshahi-6205 Bangladesh

The nature of resistive transition of high-quality crystalline thin films of YBa2Cu3O7-δhas been studied under magnetic fields（H） applied along the c direction over a wide range of doped holes, p, in the Cu O2 planes. The field- and temperature-dependent in-plane resistivity, ρab（T, H）, has been analyzed within the thermally assisted flux-flow（TAFF）formalism. The flux activation energy, U（T, H）, has been extracted from this analysis. The low-T part of the ρab（T, H）data can be described by an activation energy having the functional form of U（T, H） =（1- t）m（H-0/H）β, where t = T /Tc（reduced temperature）, and H0 is a field scale that primarily determines the magnitude of U（T, H）. The temperature exponent, m, shows a systematic variation with p, whereas the field exponent, β, is insensitive to the p values and is close to unity. The H0, on the other hand, changes rapidly as p is varied. U（T, H） is linked to the pinning potential and consequently on the superconducting condensation energy. since the normal state pseudogap directly affects superconducting condensation energy, a clear correspondence between H0 and the PG energy scale, ε g, is found. Possible implications of these results are discussed.

关键词： Y123 superconductors thermally assisted flux-flow model activation energy pseudogap

Operational Tau Approximation for the Fokker-Planck Equation

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Chinese Physics Letters 2012年第4期29卷 141-144页

作者： s.s.Dehcheshmeh s.Karimi Vanani J.s.Hafshejani Department of Mathematics Islamic Azad UniversityFarsan BranchFarsanIran

An extension of the operational Tau method (OTM) is used to solve the Fokker Planck equation arising in many physical *** extension yields an algebraic equivalent representation of the desired problem using arbitrary polynomial basis functions to decrease the size of the *** structure,properties and advantages of the OTM are presented,and some illustrative linear and nonlinear experiments are given to show the capability and efficiency of the proposed algorithm.

关键词： problems Approximation polynomial

Hydroxyapatite-containing PEO-coating design for biodegradable Mg-0.8Ca alloy: Formation and corrosion behaviour

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Journal of Magnesium and Alloys 2023年第12期11卷 4468-4484页

作者： A.s.Gnedenkov s.L.sinebryukhov V.s.Filonina s.V.Gnedenkov Institute of Chemistry of FEB RAs 159 Pr.100-letiya VladivostokaVladivostok690022Russian Federation

In this study, the biocompatible protective coating was formed using plasma electrolytic oxidation(PEO) on bioresorbable Mg-0.8Ca alloy. The composition of the formed coating was studied using XRD, sEM-EDX analysis, and micro-Raman spectroscopy. The uniform distribution of hydroxyapatite over the thickness of protective PEO-layer was established. Using traditional(EIs, PDP, OCP) and local scanning electrochemical methods(sVET, sIET with H^(+)-selective microelectrode), the level of protective properties of PEO-layer in a biological environment(mammalian cell culture medium, MEM) was determined. It was established that modification of Mg-0.8Ca alloy surface by PEO contributes to a significant increase in the corrosion resistance of the surface layer, making it possible to control the process of material‘s biodegradation. The maximum local electrochemical activity was recorded after 72 h of testing, while for the uncoated sample,intense corrosion degradation was recorded in the first 12 min of exposure to the cell culture medium. Formation of the PEO-coating results in a twofold decrease in the corrosion current density(2.8·10^(-6)A cm^(-2)) and an increase in the impedance modulus measured at a low frequency(1.7·10^(4)Ω cm^(2)) in comparison with the uncoated material(9.5·10^(-6)A cm^(-2);8.1·10^(3)Ω cm^(2)). The mechanism of material bioresorption was established and a model for biodegradation process of Mg-0.8Ca alloy with hydroxyapatite-containing PEO-coating in MEM was proposed. Analysis of these results and comparing with others obtained by various scientific groups indicate the prospects for application of biocompatible PEO-coating on Mg-Ca alloy in implant surgery.

关键词： Magnesium-calcium alloy Biodegradation Implant surgery Plasma electrolytic oxidation Electrochemistry Minimum essential medium Hydroxyapatite

Oriented colloidal-crystal thin films of polystyrene spheres via spin coating

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Journal of semiconductors 2015年第2期36卷 10-17页

作者： s.s.shinde s.Park Korea Research Institute of standards and science

We developed a simple and inexpensive synthesis of a large-scale close-packed monolayer of polystyrene sphere arrays, which have a variety of applications. The influence of three step spin speeds, spinning time, solution quantity and relative humidity is studied in order to achieve a large area close-packed monolayer. A relatively high surface coverage and uniform monolayer of Ps spheres in the range of 85%-90% are achieved by appropriate control of the preparative parameters. Also the effect of the oxygen plasma etching process on the reduction of Ps spheres has been studied. We conclude that it can be useful in industrial applications, because of the fabrication speed, surface coverage, control over Ps spheres and cost of the process.

关键词： monolayer Ps spheres oxygen plasma

ＯＮＴＨＥＣＯＮＥＣＴＩＯＮＩＮＦＩＮＳＬＥＲＳＰＡＣＥ

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Chinese Annals of Mathematics,series B 2002年第2期23卷 181-186页

作者： s.s.CHERN Nankai Institute ofMathematics

A simple derivation of the Connection in Finsler space.

关键词： Finsler space Connection Riemann-Finsler geometry

Identification of differentially expressed genes of primary spermatocyte against round spermatid isolated from human testis using the laser capture microdissection technique

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Cell Research 2004年第6期14卷 507-512页

作者： s.s.KOIDE 1230 York Avenue Center for Biomedical Research Population Council NY 10021 New York UsA

The method of laser capture microdissection (LCM) combined with suppressive subtractive hybridization (ssH) was developed to isolate specific germ cells from human testis sections and to identify the genes expressed during differentiation and development. In the present study, over 10,000 primary spermatocytes and round spermatid cells were successfully isolated by LCM. Using the cDNAs from primary spermatocytes and round spermatids, ssH cDNAs library of primary spermatocyte-specific was constructed. The average insert size of the cDNA isolated from 75 randomly picked white clones was 500 bp, ranging from 250 bp to 1.7 kb. Using the dot-blot method, a total of 421 clones were examined, resulting in the identification of 390 positive clones emitting strong signals. Partial sequence of cDNAs prepared from each clone was determined with an overall success rate of 84.4%. Genes encoding cytochrome c oxidase II and the rescue factor-humanin were most frequently expressed in primary spermatocytes, suggesting th

关键词： laser capture microdissection suppressive subtractive hybridization spermatogenesis cytochrome c oxidase Ⅱ humanin.

Nanocrystallization of α-Fe Crystals in Fe_(52)Cr_(18)Mo_7B_(16)C_4Nb_3 Bulk Amorphous Alloy

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Journal of Materials science & Technology 2011年第6期27卷 497-502页

作者： s. Ahmadi H.R. shahverdi s.s. saremi Faculty of Engineering Department of Materials Science Tarbiat Modares University

Crystallization kinetics of Fe52Cr18Mo7B16C4Nb3 alloy was evaluated by X-ray diffraction（XRD）,differential scanning calorimetric（DsC） tests and transmission electron microscopy（TEM） observations in this research *** effect,crystallization and growth mechanism were investigated by using DsC tests at four different heating rates（10,20,30,40 K/min）.Results showed that a two-step crystallization process occurred in the alloy in which α-Fe and Fe3B phases were crystallized,respectively in the structure after heat *** energy for the first step of crystallization,i.e.α-Fe was measured to be 421 and 442 kJ/mol according to Kissinger-starink and Ozawa models,***,Avrami exponent calculated from DsC curves was 1.6 and a two-dimensional diffusion controlled growth mechanism with decreasing nucleation rate was observed in the ***,it was known from the TEM observations that crystalline α-Fe phase nucleated in the structure of the alloy in an average size of 10 nm and completely mottled morphology.

关键词： Bulk metallic glasses (BMGs) structural amorphous steels (sAss) Avrami exponent Crystallization and kinetic models

Effects of Nb Alloying on Nano-Crystallization Kinetics of Fe_(55-x)Cr_(18)Mo_7B_(16)C_4Nb_x(x=0, 3) Bulk Amorphous Alloys

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Journal of Materials science & Technology 2011年第8期27卷 735-740页

作者： s. Ahmadi H.R. shahverdi s.s. saremi Faculty of Engineering Department of Materials Science Tarbiat Modares University

Crystallization kinetics of Fe55-xCrzsMo7B10C4Nbx（x= 0, 3） bulk amorphous alloys were analyzed using X-ray diffraction and differential scanning; calorimetric （DsC） tests. In practice, crystallization and growth mechanism were evaluated using DsC tests at four different heating rates （10, 20, 30, and 40 K/rain） and kinetic models. Two-step crystallization behavior was observed when Fe55Cr18MOTB16C4 and Fe52Cr18MoTB16C4Nb3 bulk amorphous alloys were annealed, where Fe36Cr12M010 phase was crystallized in the first step of crystallization. Results show that Fe36Cr12Mo10 and Fe3C phases were crystallized in the structures of the alloys after further annealing： process. Activation energy for the crystallization of Fe36Cr12Mozo phase was measured to be 543 kJ/mol in Fe52Cr18MoTB16C4Nb3 alloy and 375 kJ/mol for Fe55Cr18Mo7B16C4 alloy according to Kissinger-starink model. Moreover, a two-dimensiona nucleation rate was found in Fe52Cr18Mo7B16C4Nb3 diffusion controlled growth mechanism with decreasing alloy whereas a three-dimensional diffusion controlled growth mechanism with decreasing nucleation rate was found in crystallization of Fe36Crz2Mo10 phase during annealing of Fe55Cr18MoTB16C4 alloy. TEM （transmission electron microscopy） observations reveal that crystalline Fe36Cr12M010 phase nucleated in the structures of the alloys in an average size of 10 nm with completely mottled morphology.

关键词： Avrami exponent Crystallization Kinetic models Growth mechanisms Bulk amorphous alloys