Solvent extraction of scandium(III) by Cyanex 923 and Cyanex 925

The extraction equilibria of Sc(III), Zr(IV), Ti(IV), Th(IV), Fe(III) and Lu(III) from sulphuric or hydrochloric acid media by Cyanex 923 (mixture of straight chain alkylated phosphine oxides) and Cyanex 925 (mixture of branched chain alkylated phosphine oxides) were studied at various aqueous acidities. The extractant Cyanex 923 demonstrated better scandium loading and selectivity for TI(IV). Fe(III) and Lu(III) than Cyanex 925. The effects of extractant concentration on the extractions of sulphuric acid and Sc(III) by Cyanex 923 were examined. The stoichiometries of the extraction reactions were postulated based on slope analysis. The experimental results indicate that Cyanex 923 can be employed to recover scandium directly from the hydrolytic mother solution arising from TiO2 production via the sulphate process. The parameters studied were scandium loading capacity, phase ratio, concentrations of Ti(IV) scrubbing and Sc(III) stripping agents. A new solvent extraction technology of scandium recovery was developed. The purity of the final Sc(III) product is above 95% with a yield > 94%. (C) 1998 Elsevier Science B.V.

Studies on the energy band structures and chemical bond properties of LaX(X=N, P, As, Sb) crystals

The energy band structures of LaX(X=N, P, As, Sb) crystals have been studied by using LMTO-ASA method. The calculated energy gaps of these crystals are 2. 30 eV for LaN, 2. 05 eV for LaP, 1. 66 eV for LaAs and 1. 34 eV for LaSb. The results are in good agreement with experimental data, At the same time, using these calculated results of energy band structures of these crystals, the chemical bond properties have been analyzed and calculated, The covalency values of these crystals are 26.15% for LaN, 32.54% for LaP, 33.30% for LaAs and 36.49% for LaSb, which agree satisfactorily with the calculated ones by using PV (Phillips-Vechten) theory.

LaX(X=N,P,As,Sb)晶体的能带结构和化学键性质研究

用ＬＭＴＯ－ＡＳＡ能带程序计算了ＬａＸ（Ｘ＝Ｎ，Ｐ，Ａｓ，Ｓｂ）晶体的能带结构，得到的晶体能隙分别为ＬａＮ２．３０ｅＶ，ＬａＰ２．０５ｅＶ，ＬａＡｓ１．６６ｅＶ，ＬａＳｂ１．３４ｅＶ，与实验结果基本相符．利用价电子总数在阴阳离子上的分配数之比，给出计算晶体化学键性质的经验关系式，根据该式计算晶体化学键的共价性与文献结果非常吻合，说明了该关系式的合理性

Complete assignment of H-1-NMR resonances of the king cobra neurotoxin CM-11

The king cobra(Ophiophagus hannah) neurotoxin CM-11 is long-chain peptide with 72 amino acid residues. Its complete assignment of H-1-NMR resonances was obtained using various 2D-NMR technologies, including DQF-COSY, clean-TOCSY and NOESY.

眼镜王蛇神经毒素CM-11核磁共振氢谱谱峰的完全归属

眼镜王蛇抽提物ＣＭ－１１为含７２个残基的长链神经毒素，对其进行了ＤＱＦ－ＣＯＳＹ，ＴＯＣＳＹ和ＮＯＥＳＹ等一系列２Ｄ－ＮＭＲ谱测定，借助序列专一归属法完成了ＣＭ－１１ＮＭＲ氢谱的完整归属。

A new method for the preparation of fullerol

Reaction of C-60 with excessive potassium in toluene at refluxing temperature results in black precipitate KaC60 with high conversion, which can completely be hydrolyzed to prepare the fullerol. Investigations including FT-IR. H-1 NMR C-13 NMR, UV-Vis and FABMS of the product were reported.

Li_8SiN_4-Li_3N-BN体系中立方BN转化行为的研究

研究了高温高压下x·Li_8SiN_4-0.1(1-x)·Li_3N-0.9(1-x)·BN体系中立方氮化硼(cBN)的转化行为。Li_8SiN_4的存在可显著改善cBN晶体的发育,提高晶体质量。在4.2～5.5GPa,1340～1750℃范围内确定了x=4.8％时体系的cBN转化区,并对转化区内cBN转化率、平均生长速度、成核速度及破碎强度与转化温度和压力的关系进行了研究。

A STUDY OF SURFACE OXYGEN SPECIES FROM LA-ME-O (ME=MG, CA, SR, BA) CATALYSTS FOR METHANE OXIDATIVE COUPLING

CO2-TPD was used to study the surface basicity of La-Me-O mixed oxides and O-2-TPD, CH4-TPD were employed to study the surface active oxygen species. Comparing the CO2-TPD with O-2-TPD, we can see that the basicity of catalyst is in parallel with the catalystic activity. The stronger basicity is more profitable for the catalyst to adsorb oxygen to form active oxygen species and to activate CH4 by breaking a C-H bond, By comparing the catalytic activity, the results showed that La-Ba-O(La/Ba=7/3) catalyst had the strongest basicity, and it gave the highest CH4 conversion and C-2 selectivity, The results from the pulse reaction showed that the lattice oxygen participated in the OCM reaction without gas oxygen, and it was the selective oxygen species.

Study of FT-Raman Spectroscopy on the Effects of Lanthanide Ions and Their Complexes on the Fluidity of Dipalmitoylphosphatidylethanolamine Bilayer

The effects of lanthanide ions and their complexes of citrate and DTPA ligands on the fluidity of dipalmitoylphosphatidylethanolamine (DPPE) bilayers have been studied by FT-Raman spectroscopy. the results show that lanthanide ions of lower concentrationn decrease the fluidity of acyl chains of DPPE bilayers and change the conformation of C C-C backbone from gauche to the trans lanthanide ions of higher concentration, however, increase the fluidity of acyl chains and increase the gauche population of C-C-C backbone. Lanthanide complex of citrate have no effect on the fluidity of acyl chains of DPPE bilayers in the region of experimental concentration, but La-DTPA complex increase slightly the fluidity of acyl chains. the results also indicated that lanthanide ion of lower concentration changed the lattice packing of hydrocarbon chains from hexagonal form to orthorhombic form, but it is still in hexagonal or distorted hexagonal lattice cell in the gel state in the presence of metal ions and lanthanide complexes of higher concentration

甲烷氧化偶联La－Me－O（Me＝Mg，Ca，Sr，Ba）系催化剂表面氧种的研究

利用ＣＯ_２－ＴＰＤ法考察了Ｌａ－Ｍｅ－Ｏ（Ｍｅ＝Ｍｇ，Ｃａ，Ｓｒ，Ｂａ）系催化剂的表面碱性，并用Ｏ_２－ＴＰＤ、ＣＨ_４－ＴＰＤ法对该体系的表面活性氧种进行了表征，并与催化性能相关联。结果表明，Ｌａ－Ｂａ－Ｏ催化剂由于表面强碱性中心数目多，产生活性氧种的数目也多，有利于甲烷的活化，因而具有最高的甲烷转化率和Ｃ_２烃选择性。脉冲反应表明，在无气相氧存在下，表面晶格氧参与了氧化偶联，而且是选择氧化的活性氧种。

含有机硅三元多嵌段共聚物的研究──Ⅲ．不同硬段、半硬段对含有机硅三元多嵌段共聚物性能的影响

以双酚Ａ聚砜或酚酞作为硬段，聚对羟基苯乙烯、酚醛、聚羟基醚或聚羟基醚砜作为半硬段，聚二甲基硅氧烷作为软段合成了七种三元多嵌段共聚物，并对其稳定性、动态力学性能进行了比较详细的研究。结果表明这类共聚物在溶液中的稳定性及热稳定性主要与半硬段有关；它们的形态结构同属于微相分离，并在很宽的温度范围内表现出优良的弹性体性质。三元多嵌段共聚物中硬段与半硬段的相容性直接影响其力学性能，当两者的相容性好时，其强度高于对应的二元多嵌段共聚物。

偶联剂对阻燃型高抗冲聚苯乙烯性能的影响

在阻燃型高抗冲聚苯乙烯（ＨＩＰＳ）中，加入一定量的ＳｉＯ２作为填充剂。采用偶联剂对无机填料进行表面处理，改善了ＨＩＰＳ与无机填料的界面结构。用电子显微镜观察了无机填料表面处理前后的形态变化。

高效反渗透复合膜研究──高分子合金微孔底膜的制备与性能

研究了含酞基聚芳醚酮（ＰＥＫ－Ｃ）与聚砚（ＰＳｆ）的组成比例、添加剂和磺化处理对ＰＥＫＣ—ＰＳｆ合金不对称微孔底膜的成膜与性能的影响规律，其中适当的聚合物的组成、混合添加剂可使底膜水透量有一最大值；无机辅助添加剂及其膜表面非均相磺化处理可使底膜的水通量增大，从而制得了具有一定结构性能特点的新型高分子合金底膜。