Calculation of second-order nonlinear optical coefficients of KTiOPO4 and KTiOAsO4

The second-order nonlinear optical tensor coefficients of both KTiOPO4 (KTP) and KTiOAsO4 (KTA) are calculated from the chemical bond viewpoint. All constituent chemical bonds of both crystals are considered, and contributions of each type of bond to the total linearity and nonlinearity are determined. Calculated results agree satisfactorily with experimental data in both signs and numerical values. The calculation shows that though TiO6 groups and P(1)O-4 or As(1)O-4 groups have relatively larger linear contributions, they can only produce an advantageous environment for KOx (x = 8, 9) groups and P(2)O-4 or As(2)O-4 groups in nonlinear optical contributions. The origin of nonlinearity of KTP family crystals comes from the KOx (x = 8, 9) and P(2)O-4 groups in their crystal structures. Furthermore, the difference in optical nonlinearities of KTP type crystals is analyzed, based on the detailed calculation of nonlinearities of both KTP and KTA. (C) 1999 Academic Press.

有机锡化合物的光电子能谱和质谱研究Ⅲ

本文利用光电子能谱(XPS)和质谱(MS)研究了12种有机锡化合物。通过XPS和MS讨论了化合物中取代基对锡内层电子的影响及对SnO键的影响。结果表明XPS和MS对有机锡化合物某些化学键性质的讨论具有互补性。

不同偶联剂对滑石粉表面改性填充ABS树脂的研究

本文研究了滑石粉经长链硅烷偶联剂820J,硅烷偶联剂KH—570,铝酸酯偶联剂DL—411表面改性后,对填充ABS树脂的加工行为和力学性能的影响,结果表明长链硅烷偶联剂820J对填充ABS复合体系缺口冲击强度的提高有明显的促进作用。

Generation of chiral bis(cyclopentadienyl)neodymium Schiff base complex bearing internal C-C bond formation and hydrogen transfer

NdCl3 reacts with excess CpNa (Cp=Cyclopentadienyl) in THF, followed by sequent treatment with (S)-(+)-N-(1-phenylethyl)salicylideneamine led to the formation of title compound, [GRAPHICS] The X-ray structure determination shows that it is a dimer with internal C-C bond formation and hydrogen transfer between one of Cp ring and the C=N bond of Schiff base ligand. (C) 1997 Elsevier Science S.A.

Electrochemical behavior of Nd3+ and Ho3+ in LiCl-KCl eutectic melt

The electrochemical behavior of Nd3+ and Ho3+ ions on molybdenum electrode in the LiCl-KCl eutectic melts has been studied by cyclic voltammetry and open-circuit potentiometry. The results show that the reduction process of Nd3+ and Ho3+ ions on molybdenum electrode is one-step three electron reversible reaction. The diffusion coefficients of Nd3+ and Ho3+ ions are 1.13 x 10(-6) cm(2).s(-1)(450 degrees C) and 2.142 x 10(-5) cm(2).s(-1)(450 degrees C), respectively. The measured standard electrode potential of Ho3+/Ho is 2.987 V(vs. Cl/Cl-), being more negative than the theoretical one, the reason of which is also discussed.

蛋白质分子三维结构能量优化途径的选择

NMR方法是研究溶液中蛋白质的三维结构的重要手段，本文以BUSHIIA为例，对用度量矩阵距离几何法获得的初始三维结构进行了能量优化，主要探讨了蛋白质分子三维结构能量优化途径的选择问题．本文把优化过程分为三个阶段，分别采用不同的优化方式，使分子结构得到优化，对于分子量在8000左右的蛋白质而言，本方法能够获得较好符合核磁实验约束条件的分子低能构象.

Synthesis and characterization of acetacetic derivatives of flullerene

Acetacetic derivatives of fullerene were obtained by the reaction of C-60 with acetacetic ester, after separation with silica gel column chromatography, in good yields. Fullerenols with 13-15 hydroxyl groups were-isolated as the by-products of this reaction. Detailed experimental conditions and the structural characterizations of these new compounds were discussed.

Magnetic and electric properties of Bi(La)Sr(Ca)Mn2O6

Bi1-xLaxSrMn2O6 and BiSr1-xCaxMn2O6 are prepared by solid state reaction. They are n-type semiconductors with ferromagnetism at room temperture. When Bi is substituted partly by rare earth, a negative magnetoresistance effect is observed in the pellet of Bi1-xLaxSrMn2O6. There are semiconductor-metal transitions at 820 K in BiSrMn2O6. The transitions are attributed to the magnetic transition at high temperature. The substitution of Ca for Sr makes the transition temperature increase. However, when Bi is partly substituted by La, the solid solution does not change into metal. (C) 1996 Academic Press, Inc.

Dynamic spectroelectrochemical measurement for the conformational transition of cytochrome c induced by bromopyrogal red

The conformational transition of horse heart cytochrome c induced by bromopyrogal red (BPR) in very low concentration has been firstly investigated by dynamic spectroelectrochemical technique, both at the BPR adsorbed platinum gauze electrode and at a bare platinum gauze electrode in a solution containing BPR. The effect of BPR on the structure of cytochrome c was studied by UV-visible and Fourier transform IR spectroscopy. The unfolded cytochrome c behaves simply as an electron transfer protein with a formal potential of -142 mV vs. a normal hydrogen electrode. The difference between the formal potentials of the native and unfolded cytochrome c is coupled to a difference in conformational energy of the two states of about 40 kJ mol(-1), which agrees well with the result reported. The stability and slow refolding of the unfolded cytochrome c are discussed.

聚芳醚砜薄膜的气体透过行为

研究了一系列聚芳醚砜的Ｈ２、ＣＯ２、Ｏ２、Ｎ２和ＣＨ４气体透过性能，讨论了其气体透过的温度依赖性．与双酚Ａ聚砜（ＰＳＦ）相比，几种新型聚芳醚砜的气体透过系数和气体选择系数同时有所提高．通过聚合物的分子链段活动性和自由体积数据系列变化，讨论了气体透过速率与分子结构的关系。

EBV法制备Znln_2S_4薄膜的性质研究

用电子束加热真空蒸发法（ＥＢＶ法）制备了厚度为３５０ｎｍ的ＺｎＩｎ２Ｓ４薄膜。研究了最佳成膜工艺条件和最新电子能谱分析结果；通过不同气氛处理可以控制材料的导电类型，典型膜的电阻率为２．５×１０－１Ω·ｃｍ，Ｈａｌｌ迁移率为５２ｃｍ２·Ｖ－１·ｓ－１，载流子浓度为１．４２×１０１７ｃｍ－３，禁带宽度为２．１３ｅＶ。探讨了ＺｎＩｎ２Ｓ４膜的导电机理，并制作了ＺｎＩｎ２Ｓ４－Ｓｉ太阳电池。

STUDIES ON RADIATION CROSS-LINKING OF FLUOROPOLYMERS

The research work on radiation modification of a series of fluoropolymers were performed . The radiation crosslinked fluoropolymers obtain a great improvement in high temperature resistance, high temperature mechanical properties and radiation stability.

聚合物载体-稀土金属络合物的研究 Ⅸ.聚(苯乙烯-丙烯酰胺)载体-钕络合物的合成、表征及其催化活性

本文介绍了一种新的聚合物载体-稀土金属络合物,聚(苯乙烯-丙烯酰胺)载体-钕络合物的合成,表征和讨论了络合物的IR光谱,由此络合物与烷基铝组成的二元体系对丁二烯聚合具有良好的催化活性和定向效应。不同烷基铝的催化活性顺序为Al(i-Bu)_3>Al(i-Bu)_2H>AlEt_3。

COMPARISON OF THE SULFURIZATION OF COMOK/AL2O3 CATALYST WITH H2S AND CS2

Only H2S consumption and H2O formation was found in the sulfurization of CoMoK/Al2O3 water gas shift catalyst with H2S/H-2. but CO2 was formed first, then CH4, H2O and H2S appeared in the later part of TPS with CS2/H-2. Carbon deposition on the catalyst during the sulfurization with CS2/H-2 caused a lower activity than the catalyst sulfurized with H2S but could be removed in the run of WGS reaction.

钐在小鼠肝细胞中的分布、沉积和影响的电镜与X线微区分析研究

大剂量稀土元素可致机体中毒,其中毒的原因和机制可能是多方面的,而体内沉积是稀土元素中毒与铅、金、汞等金属离子中毒的一个共同特点。如注射到鼠体内的从镧到钐的几种元素主要富集于肝与骨骼。观察揭示,铜、铁、金、铅等金属元素可在细胞内沉积形成致密小体或进入溶酶体。对稀土元素则少见此类报道,而这方面的研究不仅有助于我们了解稀土