A note on algebraic independence criterion for Laurent series in positive characteristic

Periodica Mathematica Hungarica - We study the algebraic independence of Laurent series in positive characteristic which can be fast approximated by rational functions. This can be seen as a...     

离子液体-水双相体系悬浮聚合法制备对苯二酚分子印迹聚合物微球

通过在[Bmim]PF6离子液体-水双相体系中,以对苯二酚为模板分子,甲基丙烯酸为功能单体,二甲基丙烯酸乙二醇脂为交联剂,采用悬浮聚合法制备得到对苯二酚印迹聚合物微球(MIMs-IL),并通过FTIR等测试技术对MIMs-IL进行了表征。对不同离子液体进行了选择,[Bmim]PF6介质中制备的MIMs-IL的识别性能最好。与从氯仿介质中制备的印迹聚合物微球(MIMs-Or)相比较,MIMs-IL的产率为70.8%,明显高于MIMs-Or的48.7%。采用静态吸附法考察其印迹识别能力的结果表明,MIMs-IL对水中的对苯二酚的识别能力大大强于MIMs-Or。对MIMs-IL识别吸附的热力学和动力学研究结果表明,12h时MIMs-IL及其非印迹聚合物微球(nMIMs-IL)均达到各自饱和吸附量,对于0.50g/L对苯二酚水溶液,MIMs-IL的饱和吸附量是nMIMs-IL的2.67倍。     

Dynamic Tensile Behavior and Fracture Mechanism of Polymer Composites Embedded with Tetraneedle-Shaped ZnO Nanowhiskers

Dynamic tensile properties of glass-fiber polymer composites embedded with ZnO nanowhiskers are investigated by a split Hopkinson tensile bar. The stress-strain curves, ultimate strength, failure strain and elastic modulus are obtained and the failure mechanism of the composites is investigated by the macroscopic and microscopic observation of fractured specimens. The strain rate effect on the mechanical behavior is discussed and a constitutive model is derived by simulating the experimental data. The experimental results show that the materials have an obvious non-linear constitutive relation and strain rate strengthening effect. The composites with ZnO nanowhiskers under dynamic loading have various failure modes and better mechanical properties.     

Temperature-frequency dependence and mechanism of dielectric properties for γ-Y2Si2O7

This paper reports that single-phase γ-Y2Si2O7 is prepared via a sufficient blending and cold-pressed sintering technique from Y2O3 powder and SiO2 nanopowder. It studies the dielectric properties of γ-Y2Si2O7 as a function of the temperature and frequency. The γ-Y2Si2O7 exhibits low dielectric loss and non-Debye relaxation behaviour from 25 to 1400℃ in the range of 7.3-18 GHz. The mechanism for polarization relaxation of the as-prepared γ-Y2Si2O7 differing from that of SiO 2 is explained. Such particular dielectric properties could potentially make specific attraction for extensive practical applications.     

Modeling and Computing Example for Effective Electromagnetic Parameters of Multiphase Composite Media

A method using strong fluctuation theory （SFT） to compute the effective electromagnetic parameters of multiphase composite media, and common materials used to design radar-absorbing materials, is demonstrated. The effective electromagnetic parameters of ultrafine carbonyl-iron （DT-50） and fiber fabric, which are both multiphase composite media and represent coated and structured radar absorbing materials, respectively, are investigated, and the corresponding equations of electromagnetic parameters by using the SFT are attained. Moreover, we design a program to simplify the solutions, and the results are discussed.     

Electromagnetic Parameters Model and Microwave Absorption for Composite Coatings Containing Magnetic Particles

Considering the eddy current effect of the magnetic metal particles in a high frequency electromagnetic field, we extend the Maxwell-Garnett law by introducing the eddy-effect parameter A which is as functions of the radius, permeability and electric conductivity of the metal particle medium. It is obvious that the computational result agrees with the experiment, which indicates that the extended Maxwell-Garnett law can be used to predict the effective electromagnetic parameters of a dilute metal-insulator composite medium in a high-frequency electromagnetic field.     

Crystal Structure and High Hardness Mechanism of Orthorhomic Si2N2O

A quasi-single-phase orthorombic Si2N20 compound is obtained by hot-pressing sintering using homogeneous precursors as raw materials under nitrogen atmosphere. The bulk hardness of orthorombie Si2N20 （o-Si2N2 O） is investigated by a nanoindenter experiment; the results show that o-Si2N20 with maximal value about 19 GPa has a high hardness covalent crystal besides β-Si3N4. It is discovered that the high hardness is mainly attributed to the unique crystal structure. The bridging O atoms in the o-Si2N20 are responsible for decreasing hardness. It is found that the Si-O bonds in the open tetrahedral crystal structure are more easily broken and tilted than other bonds.     

Two new neolignans from Gymnotheca involucrata

Two new biphenyl butyl neolignan derivatives, named gymnothebutyllignans A (1) and B (2), were isolated from the whole parts of endemic medicinal plant of Gymnotheca involucrata (Saururaceae). The structures of the new compounds were elucidated by extensive NMR and MS data, and the absolutely configuration of compound 1 was confirmed by X-ray crystal diffraction analysis.     

Synthesis of novel β-propanamides to inhibit cholesteryl ester transfer protein(CETP)

A novel series of β-propanamide derivatives as inhibitors of cholesteryl ester transfer protein(CETP)were synthesized.Previously,H3(IC_(50) 2 μmol/L) was observed to inhibit CETP moderately(Xie et ah,2016).Structural modifications based on H3 led to discovery of the successful CETP inhibitor,known as 1-methyl-4-arylpyrazole.Using a similar approach,compound Q08 was identified as a highly potent CETP inhibitor with an IC_(50) of 490 nmol/L in vitro.     

Microwave Absorbing Materials： Solutions for Real Functions under Ideal Conditions of Microwave Absorption

We present general equations for metal-substrate single-layer microwave absorbing materials. The optimum electromagnetic parameters and matching thicknesses for electric-loss, magnetic-loss, and electromagnetic-loss materials are given, and possible solutions for the equations and the corresponding theoretic curves are discussed as well. The results may be helpful for designing high-performance microwave absorbing materials.