Microstructures and properties of Mg-7Gd alloy containing Y

Mg-7 mass%Gd-x mass%Y (x = 0, 1, 3 and 5) alloys were prepared by casting method, and the microstructures, age hardening behavior and mechanical properties have been investigated. The results show that the addition of Y to the binary Mg-7Gd alloy could reduce the grain size of the as-cast alloys, and enhance the age hardening response and improve mechanical properties during the investigated temperature range. The Mg-7Gd-5Y alloy exhibits maximum ultimate tensile strength and yield strength at peak hardness, and the values are 258 and 167 MPa at room temperature, and 212 and 140 MPa at 250 degrees C, respectively, which is about 1.8 times as high as the Mg-7Gd binary alloy. When x is more than 3, the amount of Mg-5 (Gd,Y) phase is observed at the peak hardness of aged alloys. The significant improvement of the tensile strength at peak hardness is mainly attributed to the fine dispersion of the beta-Mg-5(Gd,Y) precipitate.

Preparation of W-Al-Mo ternary alloys by mechanical alloying

Single phase WxAl(50)Mo(50)-X (X=40, 30, 20 and 10) powders have been synthesized directly by mechanical alloying (MA). The structural evolutions during MA and subsequent as-milled powders by annealing at 1400 degrees C have been analyzed using X-ray diffraction (XRD). Different from the Mo50Al50 alloy, W40Al50Mo10 and W30Al50Mo20 alloys were stable at 1400 degrees C under vacuum. The results of high-pressure sintering indicated that the microhardnesses of two compositions, namely W40Al50Mo10 and W30Al50Mo20 alloys have higher values compared with W50Al50 alloy.

用电化学方法研究微过氧化物酶-8与Eu~(3+)作用位点

稀土作为微量元素肥料已广泛用于农业生产。生物机制研究表明,稀土微肥在一定浓度范围内能增强植物细胞保护酶,如过氧化物酶(POD)等的生物活性。但稀土与植物酶作用的化学机制尚不明白。由于酶的结构和性能的复杂性,稀土离子与它们相互作用的过程也是相当复杂的。因此,可选用一些在结构、性质、生物活性和功能相似的小分子酶为模型化合物来研究与稀土离子的相互作用,进而为

White organic light-emitting devices with a phosphorescent multiple emissive layer

A phosphorescent multiple emissive layer, in which a blue emissive layer is sandwiched between red and green ones, is employed in a white organic light-emitting device (OLED). This OLED has a maximum luminance of 48 000 cd/m(2) at 17 V, a maximum power efficiency of 9.9 lm/W at 4 V, and a color rendering index of 82. In addition, the emission color of this device is fairly stable at high luminances: its Commission Internationale de l(')Eclairage coordinate slightly changes from (0.431, 0.436) to (0.400, 0.430) when the luminance ranges from 2000 to 40 000 cd/m(2).

低分子量聚合物电解质的合成与性能

研究了低分子量梳状聚合物电解质的合成方法及结构、性能。首先合成了不同分子量的甲基丙烯酸聚乙二醇单甲醚酯。并进一步合成了分子量一万左右的梳状聚合物电解质。结果表明:反应严格按照反应方程进行,精制产物是非晶的梳状聚合物。本聚合物体系均存在两个玻璃化转变温度,一个在100℃左右,归属为梳状聚合物主链的玻璃化转变,另一个在-20℃以下,归属于侧链玻璃化转变。在室温下侧链可以运动,有利于电活性物质的迁移和扩散。并用超微电极研究了该电解质的行为。

Synthesis and thermal polymerization of a novel stilbene-maleimide AB-monomer

A novel AB-monomer, 3-maleimidostilbene (ST-MAI), was synthesized. DSC investigation indicated that the ST-MAI monomer melted at 127 degrees C and thermally polymerized in the temperature range of 180 similar to 300 degrees C. LR investigation on the thermal polymerization processes proved that the thermal polymerization included not only copolymerizaiton between stilbene and maleimide, but also homopolymerization of maleimide. The largest reaction conversion of maleimide and stilbene unit in a ST-MAI monomer was about 82% and 50% respectively. The glass transition temperature of cured ST-MAI resin was 234 degrees C, determined by DSC. The decomposition temperatures for 10% weight loss was above 430 degrees C in both air and nitrogen atmospheres.

Preparation of the phosphor BaMgAl10O17 : Eu2+ by the surface diffusion method

A surface diffusion method was proposed and applied to prepare blue phosphor BaMgAl10O17:Eu2+. The results show that, compared with the direct synthesis method by common high temperature solid state, the concentration of Eu2+ in the phosphor BaMgAl10O17:Eu2+ prepared by the surface diffusion method can be greatly reduced owing to the activator Eu2+ ions distributed mainly over the surface of the phosphor. It is possible to reduce the cost of this kind of the luminescent materials with the aid of the surface diffusion method.

Valence stability and change of Eu(II)in oxides

Valence stability and change of Eu(II) in oxides have been studied by luminescence spect a. The results show that the valence stability and change of Eu(II)in oxides is closely related to the radius and electric charge of positive ions substituted by Eu(II) and crystal structure of the host such as Al2O3 which can form alpha-Al2O3 single phase and alpha-Al2O3 and gamma-Al2O3 mixed phases under different reaction temperatures. A, fairly good explanation is made by the proposed relation between energy coefficient and crystal structure for the first time to the observed experiment results. if the energy coefficients of substitution ions is more than that of Eu(II), the lattice substitution of Eu(II)for these ions is not occured generally and valence stare of Eu(II)is not stable and be easily changed into Eu(III). The lattice of gamma-Al2O3 can stablize the valence state of Eu(II)within certain coped concentration and in alpha-Al2O3 crystal lattice Eu(II)can be easily changed into Eu(III).

表面扩散法制备BaMgAl_(10)O_(17):Eu~(2+)荧光体

本文提出表面扩散法的思想并应用于稀土三基色发光材料中蓝色组份BaMgAl10O17:Eu2＋的制备．结果表明，同直接高温因相法制得的荧光体相比，利用表面扩散法制备的蓝色荧光体BuMgAl10O17：Eu2＋,在相同的发光亮度条件下，激活剂Eu2＋的浓度可以大为降低，从而为降低这类材料的成本提出了依据和可能.

氧化物体系中Eu~(2+)的价态稳定和转换

采用光谱方法研究了氧化物体系中Eu2+的价态稳定和转换问题．研究表明体系中Eu2+的价态稳定与取代离子的半径、电荷及基质晶相等密切相关．运用晶格能理论和晶体结构变化对实验结果进行了计算和讨论.

新型有机二硫化物电池正极材料的研究进展

综述了有机二硫化物正极材料的发展过程。有机二硫化物可以用作锂二次电池的正极活性材料，在充电过程中，－ＳＨ氧化而生成Ｓ－Ｓ作为储能官能团；在放电过程中，Ｓ－Ｓ断裂还原成－ＳＨ，完成化学能向电能的转化。有机二硫化物正极活性材料具有非常高的比能量，但必须在高温下工作。用聚苯胺与有机二硫化物复合，形成新的复合正极活性材料，在常温下即获得良好的性能，以０．１ｍＡ／ｃｍ２的电流密度放电，正极的比能量达到６００Ｗｈ／ｋｇ以上。其中，聚苯胺不仅作为活性材料，而且起到电化学催化剂的作用。

Electrochemical quartz crystal microbalance study for vanadium hexacyanoferrates: monitoring of film growth and ion effects during redox reactions

An electrochemical quartz crystal microbalance was employed to monitor directly the growth of vanadium hexacyanoferrate (VHF) films on platinum substrates during electrodeposition and interfacial coagulation in the solution containing sulfuric acid electrolyte, vanadium(IV) and hexacyanoferrate(III). Mass changes of the gold/crystal working electrode were correlated with cyclic voltammetry data. Effects of cations (NH4+, Li+, Na+ and K+), anions (SO42- and NO3-) and solvent during redox reactions of the films were studied. The results show that cations were incorporated into the film during reduction and expelled from the film during oxidation. Solvent also participates in VHF electrochemistry, and its role cannot be neglected. Anions play no role in VHF electrochemistry. (C) 1997 Elsevier Science S.A.

The synthesis and thermotropic liquid crystalline behavior of the novel poly(aryl ether ketone)s containing chloro-side group

The novel poly(aryl ether ketone)s containing chloro-side group were synthesized by nucleophilic substitution reactions of 4,4'-biphenol and chlorohydroquinone with either 4,4'-difluorobenzophenone(BP/CH/DF) or 1,4-bis(p-fluorobenzoyl)benzene (BP/CH/BF) and their thermotropic liquid crystalline properties were characterized by a variety of experimental techniques. The thermotropic liquid crystalline behavior was observed in the copolymers containing 50 and 70% biphenol. Melting transition (Tm) and isotropization transition (Ti) both appeared in the DSC thermograms. A banded texture was formed after shearing the sample in the liquid crystalline state. The novel poly(aryl ether ketone)s had relatively higher glass transition temperature (Tg) in the range of 168 similar to 200 degrees C and lower melting temperature (Tm) in the range of 290 similar to 340 degrees C. The thermal stability (Td) was in the range of 430 similar to 490 degrees C.

聚氨酯反应体系中的相互作用

采用高分辨核磁共振方法（１ＨＮＭＲ、１３ＣＮＭＲ）研究聚醚聚氨酯脲反应体系中聚醚多元醇（环氧乙烷／四氢呋喃共聚醚（ＰＥＴ）、聚乙二醇（ＰＥＧ））和固化剂Ｎ－１００及催化剂之间的相互作用和络合物形成．结果表明共聚醚的羟基和Ｎ－１００的异氰酸酯基团之间存在相互作用，能形成一种相对稳定的络合物．催化剂二月桂酸二丁基锡（ＤＢＴＤＬ）能与聚醚多元醇中的羟基氧络合，而使羟基质子变得十分活泼．三苯基铋（ＴＰＢ）及其乙氧基取代的衍生物与羟基质子之间存在氢键式络合作用，其作用强度随ＴＰＢ碱性增强而增强，三种乙氧基取代的ＴＰＢ中此类作用依间位＜对位＜邻位的顺序增强.

On highly discriminating molecular topological index

A highly discriminating molecular topological index, EAID, is proposed based on the extended adjacency matrix. A systematic search for degeneracy was performed for 3 807 434 alkane trees, 202 558 complex cyclic or polycyclic graphs, and 430 472 structures containing heteroatoms. No counterexamples (two or more nonisomorphic structures with the same EAID number) were found. This is a hitherto unheard of power of discrimination. Thus EAID might be possibly used as supplementary reference for CAS Registry Numbers for structure documentation.