生物高分子-氧化石墨烯三维多功能复合凝胶的制备及其血液净化性能

以生物高分子(壳聚糖、白蛋白、脱氧核糖核酸)为交联剂与氧化石墨烯片层进行三维自组装,冻干后得到生物高分子-氧化石墨烯复合凝胶。通过扫描电镜、原子力显微镜、纳米粒度分析仪等分析其物化性能。结果表明:生物高分子成功组装到氧化石墨烯片层上,并形成三维多孔结构,制备的凝胶显示出极好的血液相容性,有效抑制了红细胞的溶血现象,对阳离子毒性分子及重金属离子有较高的吸附量。     

晶态Li_4Ti_5O_(12)负极材料的制备及其与电解液的兼容性研究

本文以醋酸锂和钛酸丁酯为原料,以冰醋酸为抑制剂,采用溶胶-凝胶法制备了晶态Li4Ti5O12负极材料。与自制的3种电解液和实验室常用的电解液分别组装成锂/钛酸锂半电池。采用恒流充放电测试、循环伏安法(CV)及交流阻抗法(EIS)对其电化学性能进行研究。研究结果发现:在以环状碳酸酯类(EC、PC)和线性碳酸酯类(MEC)为溶剂、以六氟磷酸锂(LiPF6)为电解质的电解液中添加双乙二酸硼酸锂(LiBOB),有利于提高半电池的性能,首次放电比电容达到了198mA.h.g-1,且放电比电容经多次充放电后衰减得较小。而在电解液中加入碳酸亚乙烯酯(VC),半电池的性能有所下降。Li4Ti5O12对电解液表现出较明显的兼容性。     

Construction of rectangular displacement-based element for thick/thin plates

In this paper, a method of constructing displacement-based element for thick/thin plates is developed by using the technique of generalized compatibility, and a rectangular displacement based element with 12 degrees of freedom for thick/thin plates is presented. This method enjoys a good accuracy with simple formulation and is free of shear locking as the thickness of the plate approaches zero. The project supported by National Natural Science Foundation of China through Grant No. 59208075     

Some Properties of the Boundary Value Problem of Linear Elasticity in Terms of Stresses

The relation between the classical formulation of linear elastic problems in displacements and the stress formulation proposed by Pobedria is studied. It is shown that if the Navier and Pobedria differential operators are elliptic then corresponding boundary value problems are equivalent. The values of parameters for which Pobedria's boundary value problem has the Fredholm property are found. The homogeneous Pobedria's system is considered as a spectral problem with Poisson's ratio as a spectral parameter. The points of the essential spectrum are found and classified. The example of solving Pobedria's system for the Lamé problem for a spherical shell is presented.     

Thermoelastic Solution for Stresses

A new solution to the three-dimensional thermoelastic problem for stresses is proposed. It satisfies the static equation and compatibility condition. The stress tensor is expressed in terms of a harmonic vector. With such a solution, the boundary conditions for some elastic bodies can be satisfied quite easily__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 3, pp. 46–54, March 2005.     

Constitutive modeling of biodegradable polymers: Hydrolytic degradation and time-dependent behavior

A large range of biodegradable polymers has been used to produce implantable medical devices. Apart from biological compatibility, these devices shall be also functional compatible and perform adequate mechanical temporary support during the healing process. However, the mechanical behavior of biodegradable materials during its degradation, which is an important aspect of the design of these biodegradable devices, is still an unexplored subject. Based on the literature, the mechanical behavior of biodegradable polymers is strain rate dependent and exhibits hysteresis upon cyclic loading. On the other hand, ductility, toughness and strength of the material decay during hydrolytic degradation. In this work, it is considered a three-dimensional time-dependent model adapted from the one developed by Bergström and Boyce to simulate the performance of biodegradable structures undergoing large deformations incorporating the hydrolysis degradation. Since this model assumes that the mechanical behavior is divided into a time independent network and a non-linear time-dependent network, it enables to simulate the monotonic tests of a biodegradable structure loaded under different strain rates. The hysteresis effects during unloading–reloading cycles at different strain levels can be predicted by the model. A parametric study of the material model parameters evolution during the hydrolytic degradation was conducted to identify which parameters are more sensible to this degradation process. The investigated model could predict very well the experimental results of a blend of polylactic acid and polycaprolactone (PLA–PCL) in the full range of strains until rupture during hydrolytic degradation. From these results and analyses, a method is proposed to simulate the three-dimensional mechanical behavior during hydrolytic degradation.     

Novel cellulose acetate membrane blended with phospholipid polymer for hemocompatible filtration system

To improve the blood compatibility of cellulose acetate (CA) membranes for hemofiltration, a novel CA membrane blended with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer was designed for a hemocompatible filtration system. The MPC copolymer (PMB30) was synthesized from MPC and n-butyl methacrylate. The polymer solution for making the membrane was prepared from a solvent mixture composed of N,N-dimethylformamide, acetone, and 2-propanol. The CA and CA/PMB30 blended membranes with an asymmetric and porous structure were prepared by a phase inversion process. The mechanical properties and solute permeability of the CA/PMB30 blended membrane could be controlled by preparation conditions such as the composition of the solvents and the solvent evaporation time. The CA/PMB30 blended membrane showed both good water and solute permeabilities in comparison with the CA membrane. Also, the molecular weight of the solute passed through the membrane was changed by the addition of PMB30, and good permselectivity could be obtained. Moreover, the CA/PMB30 blended membranes had excellent blood compatibility such as protein adsorption resistivity compared to the CA membrane due to location of the MPC units in the PMB30 at the surface.     

Compatibility constraint at interfaces with elastic,crystalline solids–I: Theory

Starting with an extended Gibbs–Duhem equation and an expression for stress-deformation behavior derived by Oh and Slattery for elastic crystalline solids, we derive a new compatibility constraint on stress at coherent interfaces. Its use is demonstrated in determining the residual stresses developed during oxidation on the surface of a cylinder.     

The role of thiophosphoryl disulfide on the co‐cure of CR‐EPDM blends

Bis(diisopropyl)thiophosphoryl disulfide (DIPDIS) has been used as a coupling cum curing agent for the compatibilization of blends of ethylene propylene diene monomer rubber (EPDM) with chloroprene rubber (CR). Electrical and mechanical properties of the blend vulcanizates have been studied to find the efficiency of the vulcanizing cum coupling activity of DIPDIS. The study reveals that CR in the presence of DIPDIS greatly improves the physical properties of EPDM. It is noted that the physical properties of the vulcanizates obtained from CR‐EPDM blend depend upon CR:EPDM ratio. The scanning electron microscopy (SEM) study reveals that it is possible to form a coherent blend of CR and EPDM in the presence of DIPDIS. Copyright © 2004 John Wiley & Sons, Ltd.     

Study on liquid oxygen compatibility of bromine‐containing epoxy resins for the application in liquid oxygen tank

The liquid oxygen compatible epoxy resin was obtained by the polycondensation between tetrabromobisphenol A and neat epoxy resins. The results of liquid oxygen impact test indicated that the synthetic epoxy resins were compatible with liquid oxygen. The relationship between impact reaction sensitivity (IRS) and flame retardancy were studied by liquid oxygen impact test and limiting oxygen index test. The results showed that the flame‐retardant modification of epoxy resin was valuable to reduce the IRS. The thermal gravimetric analysis results indicated that the Br · radical was quickly released in relatively low temperature (approximately 370°C) for compatible epoxy resin. The Br · radical was a key factor to promote the epoxy resin compatible with the liquid oxygen. The X‐ray photoelectron spectroscopy was used to survey the distribution of functional groups on the surface of samples before and after impact. The results showed that the oxidation reaction and carbonization process may occur on the surface of samples after impact. The liquid oxygen compatibility mechanism is proposed in this paper. The bromine‐containing epoxy resin has the potential to be the material used in liquid oxygen tank. Copyright © 2015 John Wiley & Sons, Ltd.