Preparation and Dielectric Properties of Nonstoichiometric β-SiC Powder by Combustion Synthesis

The nonstoichiometric β-SIC powders were synthesized via combustion reaction of Si and C system in a 0.1 MPa nitrogen atmosphere, using Teflon as the chemical activator. The prepared powders were invistigated by XRD and Raman spectra. The results indicates that the cell parameters of all the prepared β-SIC powder are smaller than the standard value of β-SIC because of generation of CSi defects. The complex permittivity of prepared products was carried out in the frequency range of 8.2-12.4 GHz. It shows that the dielectric property of prepared β-SiC powder decrease with increasing PTFE content. The effect of CSi defects on dielectric property of β-SiC powder has been discussed.

Apparent Molar Volumes and Solvation Coefficients in Ternary-pseudo-binary Mixtures [(Styrene+Ethyl Acetate or Benzene)+(N-Methyl-2-pyrrolidone+Ethyl Acetate or Benzene)]

Over the full range of compositions, in the ternary-pseudo-binary mixtures of x[（1-y）C6H5CH=CH2＋ yCH3COOC2H5（or C6H6）]＋（1-x）[（1-y）NMP＋yCH3COOC2Hs（or C6H6）], the apparent molar volumes of each pseudo-pure component at different y values were calculated from the density data at 298.15 K and atmospheric pressure. The results show that the four parameters cubic polynomial can correlate the apparent molar volume with the molar fraction well over the full molar fraction range. The limiting partial molar volumes and the molar volumes of each pseudo-pure component were evaluated with different methods. Based on the limiting partial molar volume and molar volume at a certain y value, a new universal coefficient termed as solvation coefficient γ was defined to describe quantitatively the solvation degree of pseudo-pure solute and the interactions of solute-solvent molecules from the macroscopical thermodynamics viewpoint. The results demonstrate the solvation coefficients decrease with the amount of the third component increasing for each pseudo-pure solute, irrespective of the pseudo-pure solvent. Then the solvation degrees of each pseudo-pure component, the specific interactions between the solute molecule and the solvent one were discussed in terms of the solvation coefficient.

Sol-gel Derived TiO_2-Bioactive glass-Hydroxyapatite Bioactive Coating on Titanium Alloy Substrate

Coating the hydroxyapatite （HA） on the titanium alloy surface can obtain a bioactive implant with high mechanical properties However, the bonding force between the titanium alloy and the HA was low due to their different coefficient of thermal expansion （CET）. Preparing the multi-layer coating with alleviated thermal stress on titanium alloy substrate is few reported. Fabrication of a TiO2-bioactive glass （BG）-HA bioactive coating was proposed to solve this problem. A particular TiO2 surface was prepared on the titanium alloy substrate by micro-arc oxidation treatment. The BG and HA coating were coated onto the TiO2 surface in turn by using a sol-gel method. The microstructure, surface morphology and phase composition of the coatings were analyzed. The bonding force of coatings was investigated by the nick apparatus. In vitro dissolution was performed by soaking the TiO2-BG-HA coated samples into the simulated body fluid for various periods. Micro-structural observations indicated that no delamination and crack occurred at the interface of HA/BG and BG/TiO2. The bonding between the substrate and coating consists of the mechanical interaction and the chemical bonding. The bonding force could reach about 45 N. The TiO2-BG-HA coating displayed the excellent forming ability of bone-like apatite when it was soaked into the simulated body fluid. This work suggests an innovative way to reduce the internal stress among coatings through varying BG composition to adjust its CTE, so as to enhance the bonding force.

Longitudinal Mechanical Properties of Small-Diameter Polyurethane Vascular Graft Reinforced by Tubular Knitted Fabric

The vascular graft with 4 mm diameter was prepared by casting one layer of polyurethane (PU) film onto the knitting tubular fabric as the reinforced support. The effects of different PU content and wall thickness on the longitudinal mechanical properties of vascular graft were investigated. The breaking elongation, breaking force, initial modulus and breaking work were studied. The results showed that the longitudinal mechanical properties of vascular graft were enhanced as the content of polyurethane increased, which resulted from the combination of PU excellent elasticity and fabric preferable strength.

The SCUSUM Estimation of Variance Change Point in Linear Process

This paper considers the estimation problem of a variance change-point in linear process.Consistency of a SCUSUM type change-point estimator is proved and its rate of convergence is established.The mean-unknown case is also considered.

A Generalization of Cuccia＇s Theorem

For a finite group G, let S（G） be the set of minimal subgroups of odd order,which are complemented in G. It is proved that if every minimal subgroup X of odd orderof G which does not belong to S（G）, CG（X） is either subnormal or abnormal in G. Then Gsolvable.

Precise calculations on spectroscopic parameters of diatomic molecules using a novel potential energy function

A novel scheme for potential energy functions of diatomic molecules is derived using a function with phase factors. Six kinds of potential curves of common shapes are obtained by adjusting the phase factors. Spectroscopic parameters of the ground states for ten kinds of molecules are calculated using the potential energy functions. The results agree well with experimental data.

To sex in Ragtime

＂More than a book, it＇s an experience--startling, viscerally satisfying, and as joyous as a happy love affair--Cosmopolitan＂ （Doctorow, 19751）. E.L. Doctorow＇s masterpiece Ragtime has intrigued quite a great deal of critics＇ attention worldwide. However, ironically, hardly any attention was paid to the sex and lovemaking scenes in Ragtime which have been overshadowed by Doctorow＇s splendid and original post-modernist approaches. The author wants to take up this challenge and commit herself to the appearance and role of sex and lovemaking scenes in Ragtime and more importantly, the deeper meanings behind them. Hopefully, this paper will give new perspectives to the understanding of this novel.

Customer Asset Risk Discernment of E-commerce Enterprises Based on Case-based Reasoning

In the Internet economy of the twentieth century, the competition for customers between enterprises is stiffer so that they strive for customers by all means. As a kind of new thing in the Internet economy, E-commerce can attract customers and expand sales efficiently; therefore, E-commerce becomes a powerful means by which enterprises can improve customer asset rapidly. However, compared with customer asset of traditional commerce enterprises, E-commerce enterprises customer asset is more liable to be affected by the surroundings, which will result in risk. On the other hand, though enterprises pay close attention to the study of customer asset risk of E-commerce enterprises currently, the academic circles have made little research in this respect, which is not helpful for enterprises to improve customer asset by applying for E-commerce, nor can meet the actual requirement for the development of academic circles. Therefore, the customer asset risk discernment of E-commerce enterprises has been studied in this paper, and case-based reasoning（CBR） has been applied to the discernment of the customer asset risk of E-commerce enterprise, which provides quantitative basis for customer asset risk management of E-commerce enterprises and conduces to the prevention of customer asset risk and the efficiency improvement of E-commerce.

Research on Bilingual Instruction for Students of International Trade Major

This paper takes international trade major as an example to explore two segments of bilingual curriculum development,a good environment of bilingual instruction and the implementation of bilingual teaching,by discussing the development of a general bilingual environment on campus,curriculum design,curriculum teaching mode and teaching methods.The study also has the value of reference to other bilingual curriculum to some extent.

On professional development of college English teachers

This paper focuses on college English teachers’ self-development.First it explains its implication and significance,describes the present condition of English teaching at colleges,and then presents methods of college English teachers’ self-development.

Blind equalization and automatic modulation classification based on subspace for subcarrier MPSK optical communications

Equalization can compensate channel distortion caused by channel multipath effects, and effectively improve convergent of modulation constellation diagram in optical wireless system. In this paper, the subspace blind equalization algorithm is used to preprocess M-ary phase shift keying(MPSK) subcarrier modulation signal in receiver. Mountain clustering is adopted to get the clustering centers of MPSK modulation constellation diagram, and the modulation order is automatically identified through the k-nearest neighbor(KNN) classifier. The experiment has been done under four different weather conditions. Experimental results show that the convergent of constellation diagram is improved effectively after using the subspace blind equalization algorithm, which means that the accuracy of modulation recognition is increased. The correct recognition rate of 16 PSK can be up to 85% in any kind of weather condition which is mentioned in paper. Meanwhile, the correct recognition rate is the highest in cloudy and the lowest in heavy rain condition.