Nitriding of titanium with plasma jet under reduced pressure

The nitriding of titanium with argon-nitrogen (3%) and argon-nitrogen (3%)-hydrogen (2%) plasma jets at pressures of 190 torr was studied. The reaction kinetics obeyed mainly a parabolic law. The parabolic kinetic constants were 10^–10–10^–8 g² cm^–4 s^–1, which were 2–3 orders of magnitude larger than those in R.F. discharges. From emission spectroscopy, nitrogen atoms in the excited states were observed. The nitrogen atoms can promote the nitriding reaction. The effect of the addition of hydrogen to nitrogen is also briefly discussed.     

Reactions of dichloro-bis(cyclopentadienyl)titanium(IV) with bidentate Schiff bases

A series of Cp₂Ti(SB)Cl complexes, whereSB is the anion of bidentate Schiff bases derived from salicylaldehyde and different primary aminesviz o-anisidine,m-anisidine,o-phenetidine,o-chloroaniline,m-chloroaniline,m-nitroaniline, α-naphthylamine and benzylamine, have been synthesised by the reaction of dichloro-bis(cyclopentadienyl) titanium(IV), Cp₂TiCl₂, and bidentate Schiff base (sbh) in a 1:1 molar ratio in refluxingthf in the presence of triethylamine. The new derivatives have been characterised on the basis of their elemental analyses, conductance measurements and spectral (IR,¹Hnmr and electronic) studies     

TiO2-活性白土复合光催化剂的合成与活性研究

采用溶胶法合成了TiO₂-活性白土复合光催化剂,借助XRD、XPS、SEM和UV-Vis等技术对其进行了表征,并以甲基橙为模型污染物考察了合成工艺对其光催化活性的影响规律。物相结构、扫描电镜和比表面积测试结果表明,部分纳米TiO₂粒子插入活性白土层间,使其层间距扩大,复合光催化剂因而具有较高的比表面积;紫外-可见吸收光谱分析表明,与纯纳米TiO₂相比,复合光催化剂在其吸收带内具有更强的吸收,且吸收边发生红移;光催化实验表明,当TiO₂理论负载量为66%、煅烧温度为400 ℃时,所得复合光催化剂对甲基橙的脱色及卷烟厂蒸叶废水的处理均具有较高的催化活性。     

镁合金空心螺钉内固定治疗股骨颈骨折的有限元分析研究

利用有限元分析方法探究镁合金空心螺钉内固定治疗股骨颈骨折的生物力学特性, 旨在为临床治疗股骨颈骨折提供一种新的思路. 选取一例青年健康志愿者的下肢CT数据建立股骨三维模型, 在Mimics插件3-matic中建立股骨网格并赋予网格材料属性, 利用Solidworks 17.0软件建立空心螺钉模型, 将上述2个三维模型导入Workbench 2020软件中, 分别赋予空心螺钉镁合金、钛合金材料属性, 进行对比分析, 记录股骨及空心螺钉的峰值、应力分布值和股骨位移. 结果表明, 钛合金螺钉内固定模型最大应力为357.27MPa, 最大位移为0.034mm; 镁合金螺钉内固定模型最大应力为311.27MPa, 最大位移为0.034mm; 2组不同材料的空心钉结果数值差异不大. 研究表明镁合金空心螺钉和传统钛合金空心螺钉力学性能相似, 且镁合金更加亲和人体, 在临床方面可以镁合金空心螺钉代替钛合金空心螺钉治疗股骨颈骨折.     

乙醇在碳修饰的二氧化钛纳米管负载的钯电催化剂上的催化氧化

 通过有机物分解碳化处理TiO2 纳米管制得了TiO2C, 并以其为载体制备了Pd/TiO2C电催化剂,考察了该催化剂对碱性介质中乙醇电催化氧化的活性. 结果表明,碳化导电处理的TiO2C纳米管载体能有效改善催化剂中贵金属的分散度和电极结构,从而提高催化剂的电催化活性. 对催化剂活性组分的优化实验表明, Pd/TiO2C质量比为1/1时催化剂的活性最高. 在1 mol/L KOH溶液中Pd载量均为0.3 mg/cm2的条件下, Pd/TiO2C催化剂对乙醇氧化的催化活性是Pd/C催化剂的3.8倍.     

Enantioselective synthesis of chromenes

A concise approach for the synthesis of optically active chromenes is reported. The process described herein involves, as the key steps, a Sharpless-epoxidation, a selective deoxygenation, and a ring-closing metathesis.     

Composite honeycomb monoliths

A new approach has been developed for the preparation of monoliths as composite materials preserving unique properties of such initial compounds as TiO₂, zeolites, carbon materials,etc. Preparation and investigation of a large set of composite catalytic monoliths are discussed.     

磁控溅射方法生长的氮氧锌薄膜的光学特性

氧化锌(ZnO)是一种具有六方结构的宽禁带Ⅱ--Ⅵ族半导体材料，室温下能带带隙Eg为3.37eV。由于氧化锌在室温条件下具有较高的激子束缚能(60meV)，保证了其在室温下较强的激子发光。此外氧化锌还具有较高的热稳定性和抗化学腐蚀特性，因而被认为是制作紫外半导体激光器的合适材料。自1997年首次发现ZnO室温紫外受激发射以来，ZnO已成为继GaN之后紫外发射材料的又一研究热点。但是，目前对于p型氧化锌及其发光器件的研究仍处于探索阶段，对其光电特性的研究仍需要更多投入。本文利用磁控溅射方法制备出氮氧锌薄膜样品，并通过在氧气气氛下退火处理，改变薄膜样品中氮的含量。通过X射线衍射谱、X射线光电子能谱、光致发光谱及喇曼光谱的测试，研究了氮在氧化锌薄膜中的含量变化以及氮对氧化锌薄膜的结构和光学特性的影响。     

Density functional theory study on the structure and properties of Si3N4 clusters

The hybrid density functional theory B3LYP with basis sets 6-31G＊ has been used to study on the equilibrium geometries and electronic structures of possible isomers of Si3N4 clusters. 24 possible isomers are obtained. The most stable isomer of Si3N4 is a 3D structure with 7 Si-N bonds and 2 N-N bonds that could beformed by 3 quadrangles. The bond properties of the most stable isomer was analyzed by using natural bond orbital method （NBO）, the results suggest that the charges on Si and N atoms in Si-N bonds are quite large, so theinteraction of N-Si atoms in Si3N4 cluster is of strongly electric interaction. The primary IR and Raman vibrational frequency located at 1033.40 cm^-1, 473.63 cm^-1 respectively. The polarizabilities and hyperpolarizabilities of the most stable isomer are also analyzed.     

Radiation induced luminescence processes in c-BN

Spectral properties of cubic boron nitride have been studied using methods of photoluminescence (PL), X-ray excited luminescence (XL), thermoluminescence (TL) and optically stimulated luminescence. It is found that emission of cubic boron nitride is presented by 4 subbands, their relative yield is determined by the excitation type: blue, green (dominant) and red bands are observed in PL, ultraviolet, blue (dominant), green and red bands—in XL. Three thermal peaks are found in TL curves in the 0–700°C temperature range, their presence and intensity depend on radiation type used. A tentative correspondence between thermal peaks and emission bands is found.