Organosulfur-functionalized Au, Pd, and Au-Pd nanoparticles on 1D silicon nanowire substrates: preparation and XAFS studies

A hybrid preparative method was developed to prepare organosulfur-functionalized Au nanoparticles (NPs) on silicon nanowires (SiNWs) by reacting HAuCl(4) with SiNW in the presence of thiol. A number of organosulfur molecules-dodecanethiol, hexanethiol, 1,6-hexanedithiol, and tiopronin-were used to functionalize the Au surface. Size-selected NPs ranging from 1.6 to 7.5 nm were obtained by varying the S/Au ratio and the concentration of HAuCl(4). This method was further extended to the preparation Pd and Pd-Au bimetallic NPs on SiNWs. The morphology of the metal nanostructures was examined by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The local structure and bonding of the SiNW-supported metal nanostructures were studied using X-ray absorption fine structures (XAFS) [including both X-ray near-edge structures (XANES) and extended X-ray absorption fine structures (EXAFS)] at the Au L(3)-, Pd K-, S K-, and Si K-edges. It was also found that the annealing of the thiol-capped Au NPs up to 500 degrees C transforms the surface of the thiol-capped NPs to gold sulfide, as identified using Au L(3)- and S K-edge XANES. We also illustrate that this preparative approach can be used to form size-controllable Au NPs on carbon nanotubes.     

Modeling of a counterflow plasma reactor

Modeling of a counterflow plasma reactor is presented, using liquid injection for the synthesis of fine particles. An experimental reactor has been developed in this laboratory, and feasibility has been demonstrated for synthesizing advanced ceramic powders. The flow field calculations show two major recirculating regions which are of importance for increasing the particles' residence time inside of the reactor. In addition, the temperature within these recirculation zones remains relatively uniform. For simulation, water droplet trajectories have been calculated for droplets produced by an injection probe. It is shown that the droplets in a size range below 50 m in diameter will follow the streamlines and evaporate completely within a short traveling distance. This finding suggests that this reactor configuration provides a favorable environment for the synthesis of fine particles using liquid precursors.     

Pheromones of coleoptera. Communication 6. Synthesis of R,Z-14-methyl-8-hexadecenal (cis-trogodermal)

Conclusions The simple synthesis of optically active R,Z-14-methyl-8-hexadecenal (cis-trogodermal), the principal components of the aggregation pheromone ofTrogoderma granarium, was accomplished. The synthesis was based on the use of R-1-bromo-4-methylhexane and Z-4-chloro-2-buten-1-ol as the sources of the chiral and olefin fragments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 906–910, April, 1987.     

Microwave assisted hydrothermal synthesis of tin niobates nanosheets with high cycle stability as lithium-ion battery anodes

SnNb₂O₆ and Sn₂Nb₂O₇ nanosheets were synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. Compared with Sn₂Nb₂O₇ and the previously reported pure Sn-based anode materials, the SnNb₂O₆ electrode exhibited outstanding cycling performance.     

钽硫原子簇的形成及激光裂解的初步研究

报导用激光直接溅射的方法产生了大量的钽硫原子团簇离子Ta_nS_m~+(n≤9, m≤30),并用串级飞行时间质谱仪研究了所产生团簇离子的组成及紫外激光裂解规律。实验发现, 最稳定的团簇正离子往往具有Ta_nS_(2n+7)~+(n=1,2,…9)的组成, 相应的负离子具有, Ta_nS_(2n+3)~-(n=1,2,…9)的组成。各种团簇正离子的激光裂解的主要通道是连续的S_2消除过程, 且对于n=3,4,5的团簇, 主要光解产物还有Ta_3S_4~+或Ta_4S_6~+离子。据此推测出Ta_nS_m~+团簇离子的可能结构为在Ta原子周围有6个左右的S原子配位。Ta原子之间不存在直接的化学键,而较大团簇可能是以Ta_3S_4或Ta_4S_6为核心的结构。     

Preparative isolation and purification of coumarins from Peucedanum praeruptorum Dunn by high-speed counter-current chromatography

A preparative high-speed counter-current chromatography (HSCCC) method for isolation and purification of coumarins from Peucedanum praeruptorum Dunn (Baihuaqianhu in Chinese) was successfully established by using light petroleum-ethyl acetate-methanol-water as the two-phase solvent system in gradient elution mode. The upper phase of light petroleum-ethyl acetate-methanol-water (5:5:5:5, v/v) was used as the stationary phase of HSCCC. The mobile phase used in HSCCC was the lower phase of light petroleum-ethyl acetate-methanol-water (5:5:5:5, v/v) and light petroleum-ethyl acetate-methanol-water (5:5:6.5:3.5, v/v) that was changed in gradient. Four kinds of coumarins and another unknown compound were obtained and yielded 5.3 mg of qianhucoumarin D, 7.7 mg of Pd-Ib, 35.8 mg of (+)-praeruptorin A, 31.9 mg of (+)-praeruptorin B and 6.4 mg of unknown compound with the purity of 98.6%, 92.8%, 99.5%, 99.4% and 99.8% in one-step separation, respectively. The structures of the coumarins were identified by 1H NMR and 13C NMR.     

CH2(X 3B1)自由基与O2的反应

用时间分辨富里叶红外发射谱仪（ＴＲ－ＦＴＩＲＳ）研究了ＣＨ２（Ｘ＾３Ｂ１）自由基与Ｏ２反应的通道及产物的振动动态布居，基电子态自由基ＣＨ２（Ｘ＾３Ｂ１）由３５１ｎｍ紫外激光光解ＣＨ２ＣＯ生成，观测到振动发态反应产物ＣＯ（ｖ≤１０），ＣＯ２（ｖ３≤７）ＯＨ（Ｈ２Ｏ）和Ｈ２ＣＯ的红外发射，证实存在生成Ｈ２ＣＯ的通道，由光谱拟合得到不同时刻ＣＯ（ｖ）和ＣＯ２（ｖ３）的相对振动布居，发现ｖ＝４能级的布居数     

Synthesis of 1-[3-methyl-2(3H)-benzazolon-5- or 6-yl]-4-{4-[cis-2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl-methyl)-1,3-dioxolan-4-yl]methyleneoxyphenyl}piperazines

Reactions of 3-methyl-6-[4-(4-hydroxyphenyl)-1-piperazinyl]-2(3H)-benzoxazolone, 3-methyl-6-[4-(4-hydroxy-phenyl)-1-piperazinyl]-2(3H)-benzothiazolone and 1,3-dimethyl-5-[4-(4-hydroxyphenyl)-1-piperazinyl]-2(3H)-benzimidazolone with cis-{[2-(2,4-dichlorophenyl) -2-(1H-imidazol-1-ylmethyl)]-1,3-dioxolan-4-yl}methyl meth-anesulfonate in the presence of sodium hydride furnish the title compounds.     

O(3P)原子和硅烷化学反应动力学研究

本文报道了用流动放电-化学发光技术测定O(~3P)和硅烷化学反应速率常数.在293—413K范围内, 结果为k=(1.05±0.36)×10~(-10)exp[(-3.06±0.10) kcal·mol~(-1) /RT] cm~3·molecule~(-1)·s~(-1)并用过渡态理论将上述实验结果外推到200—2000 K范围内. 计算结果以三参数公式表示为: k=7.67×10~(-19) T~(2.59) exp(-720 cal·mol~(-1)/RT) cm~3·molecule~(-1)·s~(-1).