PVP-Pd催化剂六氯苯加氢脱氯中两种氢源的贡献

近年来,随着环境问题的日益突出,含卤有机化合物作为一类主要的环境污染物,其加氢脱卤反应的研究越来越多地受到人们的关注.     

检索CAS化学物质数据库的必要性和方法

以ＤＩＡＬＯＧ系统为例,讨论了检索ＣＡＳ化学物质数据库的必要性和方法。     

一种新的De Novo生物活性分子设计方法

由药效团进行虚拟活性结构生成与3D-QSAR模型相结合,筛选出有前途的结构多样性的化合物,并从中寻找活性先导化合物,是一种新的分子设计方法。采用这种方法对抗小麦赤霉病类含氟农药进行了研究,共生成了53个虚拟活性结构,通过3D-QSAR模型筛选出其中10个活性较高的结构,在活性最高的化合物基础上进行了结构修饰,得到了活性更高且毒性较低的理想化合物。研究结果表明这种方法能突破原模型化合物结构模式的局限,可以找到结构新颖的活性先导化合物,是一种非常有前途的分子设计方法,而且具有较高的筛选效率。     

铜与苯并-1,3-噻唑-2-硫酮配合物的电化学合成与 晶体结构

在苯并-1,3-噻唑-2-硫酮(Hbztzt,HL)和三苯膦(PPh~3)的乙腈溶液中,用牺牲铜阳极的电化学方法一步合成了Cu(Ⅰ)的相应配合物,电化学效率(E~f)、元素分析和IR光谱表明：产物为同时含有硫醇阴离子(L)和中性硫酮(HL)两种配体及三苯膦的多元混合配体配合物[Cu(L)(HL)(PPh~3)]。配合物在CS~2中重结晶得淡黄色晶体,X射线单晶衍射法测定其结构为[Cu(L)(HL)(PPh~3)~2]·CS~2。晶体属三斜晶系,空间群：P1.a=1.0159(2)nm,b=1.4200(2)nm,c=1.8072(3)nm,α=78.12(1)°,β=86.56(1)°,γ=67.65(1)°,Z=2,V=2.3929(6)nm^3,D~c=1.41g·cm^-^3,R=0.0348,R~w=0.0316。Cu原子以变形四面体与两个PPh~3的两个P原子、被氢键(N－H…N)平均化的硫醇阴离子(L)和中性硫酮分子(HL)上的两个环外S原子配位(两个Cu－S键的键长为0.2372nm和0.2410nm)。     

Vapor Phase Epitaxy of Nitride Films

GaN and related compounds are very promising materials for developing short wavelength light emitting devices, such as laser diode (LD) and light emitting diode (LED), high temperature and high power electronics. Commercially used nitride materials have been made by vapor phase epitaxy (VPE), including metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE). MOVPE is a widely used technique to fabricate semiconductor films. Its precise control of growth process, ability of handling multi large area wafers, and excellent reproducibility make it valuable in large-scale production of electronic and optoelectronic devices. VPE of nitrides has met several critical materials issues. Firstly, a high vapor pressure of nitrogen leads to the lack of bulk crystal of GaN. People have to use heteroepitaxy technique to produce GaN materials and devices, which makes high-density defects in GaN epilayers. Secondly, the high bonding energy of GaN and high stability of NH₃ require a high growth temperature. The high nitrogen vapor pressure at high growth temperature requires enhanced local precursor densities. Additionally, the growth chemistry of VPE of nitride materials is very complicated. Parasitic chemical reactions take place during the VPE growth and degrade the material quality. Finally, the physical process of VPE growth has not been well understood. Optimized production of nitride material is predicated on an understanding of how the film properties are affected by the initial processing sequence. Heteroepitaxy of nitrides is strongly influenced by the initial nucleation and growth sequence.     

Electrocatalytic Oxidation of HCOOH on Pt(331)/Sb Electrode

Single crystal planes provide surface models of well defined atomic arrangement. Using the method of UPD and irreversibly adsorption (IRA) to modify electrode with adatoms can change the composition,the symmetry of atomic arrangement and the electronic structure of electrode surface^[1]. We have studied in this paper the electrochemical behavior of irreversibly adsorbed antimony on Pt(331) (Pt(331)/Sb) and HCOOH oxidation on R(331)/Sb. The result demonstrated that the IRD Sb adatoms on Pt (331) was stable at potentials below 0.30 V (SCE). We illustrated that various coverage of Sb_ad can be easily obtained by controlling the number of potential cycling and the upper limit of potential scan (Eu). The coadsorption of Sb with H on Pt(331) surface was characterized by relation between the coverage of Sb (θ_Sb) and that of H_ad (θ_H). Two domains were determined:(1) when θ_Sb is small than 0.10, dramatic decrease of θ_H with θ_Sb is manifested, meaning that hydrogen adsorption can be inhibited significantly by a small quantity of Sb_ad; (2) when θ_Sb is large than 0.10, θ_H maintains almost a constant value near 0.025.     

Hyphenation of FI Solid Phase Extraction (SPE) Micro-column with ICP-MS for On-line Separation and Determination of Trace Amount of Lead in High Salt Samples

The determination and monitoring of lead in the field of environmental science and life science are very important due to its high toxicity/ecotoxicity and bioavailability. The accurate and precise determination of Pb in the samples related to environmental and life sciences is still a great challenge to analytical chemists because of its extremely low concentration and complicate matrices in the samples.     

利用四氯乙烷胺化反应合成联氢化嘧啶衍生物的研究

利用均四氯乙及二氯甲烷的胺化反应,合成了联氢化嘧啶衍生物1～5,4a,8b-反-4,5,8a,9a-四氮杂全氢芴(6)和8b,8c-顺-3a,4a,7a,8a-四氮杂环戊并全氢芴(7)。化合物(6)和(7)的顺反异构体在酸催化下开环,异构生成较稳定的6b和7a。     

车床管理优化模型

本文讨论了自动化车床连续加工零件工序定期检查和刀具更换的最优策略 .针对问题一 ,应用管理成本理论结合概率统计方法 ,建立定期检查调节零件的平均管理成本的优化设计模型 ,通过计算机求解、模拟 ,得到工序设计效益最好的检查间隔和刀具更换间隔 .针对问题二 ,在问题一的基础上 ,利用概率知识调整了检查间隔中的不合格品数带来的平均损失 ,同时加上了因工序正常而误认为有故障停机产生的平均损失 ,然后建立起目标函数 ,得到工序设计效益最好的检查间隔和刀具更换策略 .对于工序故障采用自动检查装置 ,设计出了自动检查调节系统 ,并给出了算法框图 ,有效地避免工序正常而误认为有故障停机损失 ,提高工序效益     

Synthesis and characterization of C3N4 hard films

C3N4 films have been synthesized on both Si and Pt substrates by microwave plasma chemical vapor deposition (MPCVD) method. X-ray spectra were calculated for single phase α-C3N4 and β-C3N4 respectively. The experimental X-ray spectra of films deposited on both Si and Pt substrates showed all the strong peaks of α-C3N4 and β-C3N4, so the films are mixtures of α-C3N4 and β-C3N4. The N/C atomic ratio is in the range of 1.0-2.0. X-ray photoelectron spectroscopy (XPS) analysis indicated that the binding energy of C 1s and N 1s are 286.2 eV and 399.5 eV respectively, corresponding to polarized C-N bond. Fourier transform infrared absorption (FT-IR) and Raman spectra support the existence of C-N covalent bond in the films. Nano-indentation hardness tests showed that the bulk modulus of a film deposited on Pt is up to 349 GPa.