一种非晶硅膜改性弹性玻璃毛细管交联中等极性固定相色谱柱的制备

研究了非晶硅膜改性的弹性玻璃毛细管交联ＯＶ－１７０１中等极性固定相色谱柱。在适当温度下，采用过氧化二异丙苯（ＤＣＵＰ）游离基引发交联ＯＶ－１７０１固定液，成功地制备了交联ＯＶ－１７０１柱，该柱具有柱效高、惰性好、耐溶剂、抗腐蚀和耐高温等性能，是一种新型高性能的中等极性交联柱。     

Recent advances in the activation of boron and silicon reagents for stereocontrolled allylation reactions

Despite the popularity of boron and silicon allylation reagents in stereocontrolled synthesis, they suffer from a number of inherent limitations that have slowed down their development as synthetic tools for nucleophilic additions to carbonyl compounds and imine derivatives. These limitations are the low reactivity and diastereoselectivity of allyl trialkylsilane reagents, and the lack of catalytic systems for the activation and substoichiometric control of enantioselectivity in the additions of allyl boron reagents. To develop more efficient and general methods for the control of absolute stereochemistry in the resulting homoallylic alcohols, new approaches aimed at solving the problem of activation of allylic boron and silicon reagents are needed. This Minireview describes a number of recent approaches that have been devised to address this problem.     

Synthesis of Ultrafine SiC Powders from Carbon-Silica Hybridized Precursors with Carbothermic Reduction

Inorganic-organic hybrid gels were prepared by simultaneous condensation of the liquid mixture of ethyl silicate, ethyl borate and water soluble phenol resin with low molecular weight. The liquid mixtures were changed into lightly colored transparent gels after a catalyst addition and stirring. The obtained gels were crushed, dried and fired in controlled conditions to yield the inorganic precursors. Since the tailored inorganic precursors mainly consisted of SiO2 and carbon, silicon carbide was formed with the heat treatments in an Ar atmosphere beyond 1773 K with carbothermic reduction. The properties and morphology of the formed silicon carbide powders in terms of the starting precursor compositions and the conditions of the carbothermic reduction were investigated with SEM, XRD and TG-DTA analysis.     

Oxidation of Styrene with Molecular Oxygen in Supercritical CO2

The oxidation of styrene with molecular oxygen catalyzed by PdCl2 CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.     

溶剂聚合膜pH电极作内电极的气敏电极的研究

研究了以中性载体为活性物的石墨内导平头溶剂聚合膜(SPM)pH电极作内电极的二氧化碳和氨气敏电极。电极的性能取决于中性载体的特性,其中以菸酸十八酯为内电极膜活性物的二氧化碳气敏电极和以二辛基十八胺为活性物的氨气敏电极性能较佳。二氧化碳气敏电极用作丙酮酸脱羧酶酶电极的原电极,其性能院于传统的以玻璃pH电极作内电极的二氧化碳气敏电极。     

烷类特种气体分析装置的研制及其应用

研制烷类特种气体分析专用的多维气相色谱仪，特制的热导检测器，具有手动－自动功能。设计了输气－配气装置和多维气相色谱流程。以微机控制，可按编辑程序清洗系统。检查本底，自动进样，显示或打印谱图和分析结果。可检测多种烷类特种气体组份及其中氧，氮，一氧化碳和甲烷等痕量杂质。     

Synthesis of anodic silicon oxide films in water-organic solutions containing orthophosphoric acid

Variations in electrophysical properties of anodic silicon oxide at the surface of semiconductor silicon are studied as a function of the composition of electrolytic solutions containing orthophosphoric acid and the conditions of reaching the final formation potential. The optimum conditions for the formation of anodic SiO₂ coatings that include phosphorus-containing admixtures are determined, the coatings being intended for application as diffusates in nanoelectronics.     

Germanium dioxide as internal standard for simplified trace determination of bromate, bromide, iodate and iodide by on-line coupling ion chromatography-inductively coupled plasma mass spectrometry

The use of elemental mass spectrometry as detection for ion chromatography allows sensitive determination of several bromine and iodine species at a reasonable time scale. Lowest concentrations observable are 66 ng L(-1) for bromate, 45 ng L(-1) for iodate, 74 ng L(-1) for bromide and 151 ng L(-1) for iodide. A major drawback of previous IC-ICP-MS applications is the high consumption of time and thus the running costs. The use of GeO2 as internal standard not only allows improved external calibration, but also semiquantitative determination of bromate, bromide, iodate and iodide without any calibration procedure. Furthermore, GeO2 can be used for all known types of anion exchange columns regardless of their construction principles. It is shown, that the analyte-to-GeO2 ratio of four bromine and iodine species was nearly constant over 4 months and almost independent from the ICP-MS instrumental settings. The quantification by means of the analyte-to-GeO2 ratio for samples taken from a bromate round robin test shows that the values obtained are in excellent agreement with calibration curve and isotope dilution results.     

Growth of silicon thin film by LPE on porous silicon bilayers

The fabrication of solar cells based on the transfer of a thin silicon film on a foreign substrate is an attractive way to realise cheap and efficient photovoltaic devices. The aim of this work is to realise a thin mono-crystalline silicon film on a double porous silicon layer in order to detach and transfer it on mullite. The first step is the fabrication of a double porous silicon layer by electrochemical anodisation using two different current densities. The low current leads to a low porosity layer and during annealing, the recrystallisation of this layer allows epitaxial growth. The second current leads to a high porosity which permits the transfer on to a low cost substrate. Liquid Phase Epitaxy (LPE) performed with indium (or In+Ga) in the temperature range of 950–1050°C leads to almost homogeneous layers. Growth rate is about 0.35 μm min⁻¹. Crystallinity of the grown epilayer is similar on porous silicon and on single crystal silicon. In this paper, we focus on the realisation of porous silicon sacrificial layer and subsequent LPE growth. This revised version was published online in July 2006 with corrections to the Cover Date.