LaC_3~n(n=-1,0,+1)分子簇的理论研究(英文)

用密度泛函方法研究了ＬａＣ３ｎ（ｎ＝－１，０，＋１）分子簇的结构和稳定性，对这个四原子体系，提出了５种可能构型，其中３种具有Ｃ２ｖ对称性，２种为Ｃ∞ｖ对称性．在Ｃ２ｖ对称性结构中，其中１个为Ｌａ接在弯曲的Ｃ３链上，第２个是Ｌａ通过２个键与Ｃ３环相链，第３个是Ｌａ通过１个键与Ｃ３环相连；在Ｃ∞ｖ对称性中，第１个Ｌａ接在Ｃ３链的一端，而在第２个构型中，Ｌａ被插入在Ｃ３链中．结果表明，环状结构当Ｌａ接在弯曲的Ｃ３链上的是局域极小值并且最稳定     

水热法制备高纯超细CeO2-ZrO2复合氧化物

Superfine composite powders of CeO₂-ZrO₂ (CZ) and CeO₂-ZrO₂-La₂O₃ (CZL) were prepared by hydrothermal method. The effects of pH、temperature and time for hydrothermal process on the performance of the resulting powders were studied. The optimized reaction parameters were on follows: the precursor′s pH≈9.0, hydrothermal temperature of 200 ℃ holding for 2 h. Thermal stable powders with average particle size smaller than 10 nm and specific surface area of 171 m²·g^-1 were obtained. A BET specific surface area was still at 44 m²·g^-1 after calcination at 1 000 ℃ for 6 hours.     

双波长K系数—标准加入吸光光度法同时测定锰和锌

研究应用双波长K系数—标准加入吸光光度法同时测定锰和锌二组分混合物.试验确定了锰和锌测定中K_(Mn)与K_(Zn)的回归方程.对合成试样、人发试样测定,结果满意.     

Analysis of thermal behaviour of high power semiconductor laser arrays by means of the finite element method (FEM)

New results of steady-state two-dimensional finite-element computations of temperature distributions of high power semiconductor laser arrays are presented. The influence of different thermal loads on the 2D temperature distribution in AlGaAs/GaAs gain-guided laser arrays is investigated. TheFEM model is tested by comparing it with analytical solutions. For numerical convenience, the latter is rewritten in a novel form, which is free of overflow problems. The maximum temperatures calculated by both methods agree within 1%. Several factors determining the thermal resistance of the device are quantitatively examined: the ratio of light emitting to non-emitting areas along the active zone, the amount of Joule losses, the current spreading, the solder thickness, and voids in the solder. This yields design rules for optimum thermal performance.     

Non-stoichiometry of YBa2Cu3O7-d Observed by Repeated Temperature Scanning

Repeated temperature scanning method was applied to observe non-stoichiometry of YBa₂Cu₃O₇-d, and interesting results were obtained. Two simultaneously occurring processes were separately observed in mass change; one is a fast process and the other is slow, so that their responses to the temperature change are quite different from each other. The fast process follows the cyclic temperature change, but the slow process is observed to be a gradual mass change. Kinetic behaviors of these two processes are also made clear by plotting the mass vs. the temperature. Furthermore, a hysteresis loop was observed in the plot of the mass vs. the temperature in a high temperature range presumably due to the third process, and it depends on the heating and cooling rates. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dynamic headspace liquid-phase microextraction of alcohols

A method was developed using dynamic headspace liquid-phase microextraction and gas chromatography-mass spectrometry for extraction and determination of 9 alcohols from water samples. Four different solvents, hexyl acetate, n-octanol, o-xylene and n-decane were studied as extractants. The analytes were extracted using 0.8 microl of n-octanol from the headspace of a 2 ml sample solution. The effect of sampling volume, solvent volume, sample temperature, syringe plunger withdrawal rate and ionic strength of the solution on the extraction performance were studied. A semiautomated system including a variable speed stirring motor was used to ensure a uniform movement of syringe plunger through the barrel. The method provided a fairly good precision for all compounds (5.5-9.3%), except methanol (16.4%). Detection limits were found to be between 1 and 97 microg/l within an extraction time of approximately 9.5 min under GC-MS in full scan mode.     

选相原位法合成立方氮化硼的关键影响因素

利用选相原位法在水溶液中成功制备出了立方氮化硼晶体，对反应条件进行了优化。结果表明，利用选相原位法合成立方氮化硼的最佳实验条件是：反应压力为10.0 MPa，在氯离子加入下利用混合氮源进行反应。在该条件下得到了纯相的立方氮化硼晶体。     

Production of micron-sized monodispersed composite polymer particles by seeded polymerization utilizing the dynamic swelling method

 In order to develop the seeded polymerization technique utilizing the dynamic swelling method (DSM) proposed by authors for the production of micron-sized mono-dispersed “composite” polymer particles consisting of two kinds of polymers, the seeded polymerization for the dispersion of ethyl methacry-late (EMA)-swollen PS particles prepared utilizing DSM was carried out. Monodispersed PS/poly(ethyl methacrylate) (PEMA) composite particles having 7 μm in diameter were produced by the addition of NaCl to lower the solubility of EMA in medium and by the addition of CuCl₂ as a water-soluble inhibitor to depress the by-production of submicron-sized PEMA particles. Received: 16 July 1996 Accepted: 10 October 1996     

Selective synthesis of di(propen-1-yl)sulfone and di(propen-1-yl)sulfoxide

Convenient selective methods of synthesis of the title compounds, based on oxidation of di(propen-1-yl)sulfide with 30% H₂O₂, have been developed.Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 675–679, March, 1992.     

微分方法在聚苯骈咪唑修饰电极溶出伏安分析研究中的应用

本文推导了聚苯骈咪唑修饰电极溶出伏安分析中电流对电位的二次方程，并以Ｆｅ（Ｃ２Ｏ４）＾２－３为研究对象，对该方程进行了实验验证，实验结果与理论相吻合。