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Negative Temperature Coefficient of Resistivity in Bulk Nanostructured Ag

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Journal of Materials science & technology 2000年第5期16卷 521-524页

作者： Yushuang LIU, Chimei MO+ and Weili CAI (department of Materials science and {2., university of science and technology of china, hefei 2.002., china) department of Materials science and {2. University of Science and Technology of China Hefei 230026 China

The change of the temperature coefficient of resistivity (a) with the particle size, dp, and the grain size, dc, in the nanostructured Ag bulk samples was investigated. dp and dc were controlled by heating the nano-Ag powders over the temperature range from 393 to 453 K. The electrical resistance measurements of the nanostructured Ag bulk samples obtained by compacting the Ag powders after heat treatments showed a change in the sign of a with dP and dc. When dp and dc are smaller or equal to 18 and 11 nm below room temperature or 2. and 12.nm above room temperature, respectively, the sign of the temperature coefficient of resistivity changes from positive to negative. The negative a arises mainly from the high resistivity induced by the particle interfaces with very lowly ordered or even disordered structure, a large volume fraction of interfaces and impurities existing in the interfaces, and the quantum size effect appearing in the nano-Ag grains.

关键词： Negative Temperature Coefficient of Resistivity in Bulk Nanostructured Ag

Optimization of the inhibition of atmospheric window emission using photonic crystals

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science china(Technological sciences) 2010年第5期53卷 1315-1319页

作者： LI Jin & YE Hong department of Thermal science and Energy and {2.,university of science and technology of china,hefei 2.002.,china 1. department of Thermal science and Energy and {2. University of Science and Technology of China Hefei 230026 China

Transfer matrix method is used to discuss the effect inhibition of photonic crystals on atmospheric window emission(ε-14 μm).According to the optical characteristics of the materials,germanium and zinc sulfide are used as the composing *** structure of the photonic crystals is optimized,and the optimal thickness values of the germanium and zinc sulfide are 0.63 and 1.11μm respectively while the ratio of optical thickness is 1:1 and the period is *** photonic crystals are prepared by evaporation coating method,and the optical properties of the photonic crystals are measured,the inhibition of the photonic crystals to atmospheric window emission is verified.

关键词： photonic crystals emission at atmospheric window inhibition

CONTROLLED RADICAL COPOLYMERIZATION OF STYRENE AND MALEIC ANHYDRIDE UNDER GAMMA RADIATION IN THE PRESENCE OF BENZYL DITHIOBENZOATE

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Chinese Journal of Polymer science 2002年第6期20卷 525-530页

作者： De-cheng Wu Ying-fang Zou Cai-yuan Pan department of Polymer science and {2. university of science and technology of china, hefei 2.002., china Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The copolymerization of styrene (St) with maleic anhydride (MAh) under gamma radiation at room temperature in the presence of benzyl dithiobenzoate (BDTB) was found to display 'living' nature evidenced by constant concentration of chain radicals during the copolymerization, linear evolution of molecular weights with conversion and narrow molecular weight distribution (M-w/M-n = 1.2.-1.35). The compositional analysis and the sequence structural information of the copolymers obtained from DEPT (Distortionless Enhancement by Polarization Transfer) experiments demonstrate that the copolymers obtained also possess strictly alternating structure.

关键词： controlled radical polymerization alternating copolymer maleic anhydride styrene

Effective temperature and exergy of monochromic blackbody radiation

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Progress in Natural science:Materials International 2007年第10期17卷 1250-1254页

作者： Chen Zeshao and Mo Songping(department of Thermal science and Energy {2., university of science and technology of china, hefei 2.002., china) department of Thermal science and Energy {2. University of Science and Technology of China Hefei 230027 China

A new parameter named monochromic effective temperature Tλ is proposed, which represents the thermodynamic quality of monochromic blackbody radiation. The exergy of the monochromic blackbody radiation is expressed by Tλ. The monochromic effective temperature equation is developed, which shows that the product of Tλ and the wavelength is constant, which equals 5.33016×10-3 m·K. The exergy function of monochromic blackbody radiation is presented. The cause of the view that there is negative entropy production in photosynthesis can be explained by the results of this work.

关键词： photon monochromic effective temperature exergy of monochromic radiation.

A NEW SYNERGIST FOR INTUMESCENT FLAME RETARDANT POLYPROPYLENE

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Chinese Journal of Polymer science 2002年第4期20卷 377-380页

作者： Qiang Wu Bao-jun Qu State Key Laboratory of Fire science and department of Polymer science and engineering university of science and technology of china, hefei 2.002. china Univ Sci & Technol china State Key Lab Fire Sci Hefei 230026 Peoples R China Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The synergistic effects of silicotungstic acid (SiW12. as a catalyst in the phosphorus-nitrogen compounds AM-based intumescent flame-retardant (IFR) polypropylene (PP) were studied using the limiting oxygen index (LOI), the UL-94 test, thermogravimetric analysis (TGA), real time Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS). The LOI data show that SiW12.added to PP/IFR systems has a synergistic FR effect with an IFR additive named AM. The TGA data show that SiW12.apparently increases the thermal stability of the PP/IFR systems at high temperature (T > 500degreesC). The FTIR results provide the positive evidence that IFR can improve the thermal stability of PP and SiW12.can induce a higher rate of formation of phosphoric acid and its derivatives. The LRS measurements provide useful information on the carbonaceous microstructures. In short, a suitable amount of SiW12.(1.5 wt%) exerts synergistic effects with the IFR by increasing the LOI value and the thermal stability at high temperature and promoting the formation of charred structures on the burning PP surface.

关键词： silicotungistic acid synergistic effect intumescent flame retardant polypropylene

TYPE X MONOTONE SYSTEMS WITH AN ORDER-INCREASING INVARIANT FUNCTION

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Chinese Annals of Mathematics,Series B 1996年第3期17卷 335-342页

作者： JIANG JIFA(department of Mathematics, The university of science and technology of china, {2. 2.0036, china.) department of Mathematics University of Science and Technology of China Hefei 230036 China

The author considers the asymptotic behavior of solutions of a class of ordinary dmerentialequations x = F(x) in the nonnegative orthant R7. Suppose that F(o) = o, Fi(x1,..., xn) isnondecreasing in xk for all k≠ i and that F possesses an order-increasing invarian *** it is shown that every bounded solution to such a system converges to a single equilibrium.

关键词： Type K monotone system Monotone flow Invariant function Equilibrium Convergence

COMPOSITIONAL HETEROGENEITY OF ETHYLENE OXIDE-BUTYLENE TEREPHTHALATE SEGMENTED COPOLYMER

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Chinese Journal of Polymer science 1999年第3期17卷 271-280页

作者： De-zhu Ma Dong-sheng Li Ming-chuan Zhao Mo-zhen Wang Ran Ye xiao-lie {2. department of Polymer science and engineering, university of science and technology of china, hefei 2.002., china Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

A series of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with different soft segment length and hard segment content were synthesized. The compositional heterogeneity was studied by solvent extraction. The results show that the compositional heterogeneity increases when soft segment length and hard segment content increase. The compositional heterogeneity is also reflected in the crystallization behavior and morphology of soft and hard segment in EOBT segmented copolymer. The more compositional heterogeneous the EOBT segmented copolymer is, the more different the morphology and the crystallization behavior between separated fractions. Compared with ethylene oxide-ethylene terephthalate (EOET) segmented copolymer, compositional heterogeneity in EOBT segmented copolymer is weaker. But the compositional heterogeneity in EOBT segmented copolymer with long soft segment and high hard segment content is still obvious.

关键词： ethylene oxide-butylene terephthalate segmented copolymer compositional heterogeneity crystallizability morphology

ON THE FILTRATION OF NON-NEWTONIAN FLUID IN POROUS MEDIA WITH A MULTIPLE PARAMETER MODEL

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Journal of Hydrodynamics 2001年第1期13卷 39-46页

作者： Zhu Zuo-jin department of Thermal science and Energy {2.. university of science and technology of china, hefei 2.002., china[WT5”HZ] department of Thermal science and Energy {2.. university of science and technology of china

A multiple parameter model to describe the Non-Newtonian properties of fluid filtration in porous media is presented with regard to the pressure gradient expression in terms of the velocity of filtration, where the multiple parameters should be determined by measurements. Based on such a model, an analysis was furnished to deduce the formula for the rate of production of an oil well, and the governing equations for single phase Non-Newtonian fluid filtration. In order to examine the effects of model parameters, the governing equations were numerically solved with the method of cross-diagonal decomposition ZG method. It is found that, for constant rate of production, the power index n of the model influences the pressure distribution considerably, particularly in the vicinity of a single well. The well-bore pressure of Leibenzonian fluid is lower than that of the power-law fluid in the case of the same parameter B and the power index n=0.5.

关键词： Computer simulation Mathematical models Non Newtonian liquids Oil well production

Synthesis and Structure of Butylene Terephthalate-ε-Caprolactone Copolyesters

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Chinese Chemical Letters 1999年第7期10卷 593-596页

作者： xiao Min CHENG xiao {2. luo Zhi Bo LI De Zhu MA(department of Polymer science and engineering. university of science and technology of china.hefei. Anhui 2.002.) Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Anhui Peoples R China

A series of butylene terephthalate-E-caprolactone copolyesters (BCL) with different hard segment content were successfully synthesized and characterized by 1H-NMR. DSC. PLM and U viscometer, The sequence structure and... 详细信息

关键词： BCL copolyesters polycondensation hard segment soft segment sequence structure crystallization behavior spherulite morphology