溶剂热制备条件对镍晶体结构的影响

Nickel powders were obtained after chemical reduction of nickel chloride by KBH₄ using absolute ethylenediamine as solvent in a stainless autoclave. The product was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results show that the as-prepared sample have different crystal structures at different reaction temperatures. It was face-centered cubic (fcc) nickel under 200 ℃, and there was only hexagonal close-packed (hcp) Ni above 300 ℃. At 250 ℃, the patterns indicate that both fcc and hcp phases of Ni coexist in the as-prepared sample. When the ethylenediamine was respectively substituted by benzene and toluene, only fcc phase nickel was obtained. SEM and TEM indicate that the fcc Ni is nano-particles with about 100 nm in diameter, and hcp nickel is nano-crystalline clusters.     

配位聚合物的三阶非线性光学性质

本文概括了配位聚合物的三阶非线性光学性质，并总结了其结构与三阶非线性光学性质之间的关系。对于一维结构的配位聚合物，因配体不同或者中心金属离子的价层电子构型不同可呈现自聚焦或自散焦效应;二维结构配位聚合物的三阶非线性光学性质则与配体和中心金属离子无关，均呈现自聚焦效应;三维结构配位聚合物的自聚焦或自散焦效应主要受中心金属离子价层电子构型的影响。     

氨水共沉淀法制备Nd∶Y2O3透明陶瓷纳米粉体

以Y2O3粗粉、Nd2O3、硝酸和氨水为原料,通过共沉淀法制备了Nd:Y2O3透明陶瓷纳米粉体,利用热重/差热分析(TG/DTA)、红外光谱(FTIR)、粉末X射线衍射(XRD)、透射电镜(TEM)以及能谱分析(EDS)等方法对合成的Nd:Y2O3纳米粉体进行了表征.结果表明,在前驱物中添加适量SO42-离子能减轻煅烧得到的Nd:Y2O3纳米粉体粒子的团聚,使Nd:Y2O3纳米粒子的粒度均匀并呈球形分布.在600～1000℃煅烧3 h所得粉体粒子的粒径在20～40 nm之间,具有较好的分散性.     

Weak localization in ferromagnetic (Ga,Mn)as nanostructures

We report on the observation of weak localization in arrays of (Ga,Mn)As nanowires at millikelvin temperatures. The corresponding phase coherence length L phi is typically between 100 and 200 nm at 20 mK. Strong spin-orbit interaction in the material is manifested by a weak antilocalization correction around zero magnetic field.     

Single-nucleus polycrystallization in thin film epitaxial growth

We have observed, by use of low-energy electron microscopy, the first direct evidence of self-driven polycrystallization evolved from a single nucleus in the case of epitaxial pentacene growth on the Si(111)-H terminated surface. In this Letter we demonstrate that such polycrystallization can develop in anisotropic systems (in terms of crystal structure and/or the intermolecular interactions) when kinetic growth conditions force the alignment of the intrinsic preferential growth directions along the density gradient of diffusing molecules. This finding gives new insight into the crystallization of complex molecular systems, elucidating the importance of nanoscale control of the growth conditions.     

新型喹喔啉衍生物的合成、光物理性质及理论分析

合成了新型质子给体的荧光探针化合物2,3-双(4-二甲胺基苯基)喹喔啉( QBDMA).利用紫外-可见(UV-Vis)吸收、红外吸收和氧核磁共振等光谱手段对该化合物进行了分子结构表征,同时分析其电化学性质和光致发光性质.研究了该化合物在不同条件下的光致发光光谱.最后在B3LYP1/6-31G*水平上优化其基态结构,并对...     

紫外分光光度法测定普卢利沙星胶囊的含量

建立紫外分光光度法测定普卢利沙星胶囊含量的方法。采用紫外分光光度法,以0.1mol.L-1盐酸溶液为溶剂,测定波长为274nm。在1.2—12μg.mL-1浓度范围内,吸光度与相应的浓度呈良好的线性关系（r=0.9999）;重复性实验中,吸光度测定平均值为0.5825（n=6）,相对标准偏差为0.1%;回收率实验中,平均回收率为99.6%（n=9）,相对标准偏差为0.2%。本方法结果稳定,重复性好,为普卢利沙星胶囊提供了一个简单方便的含量测定方法。     

Direct correlation analysis improves fold recognition

The extraction of correlated mutations through the method of direct information (DI) provides predicted contact residue pairs that can be used to constrain the three dimensional structures of proteins. We apply this method to a large set of decoy protein folds consisting of many thousand well-constructed models, only tens of which have the correct fold. We find that DI is able to greatly improve the ranking of the true (native) fold but others still remain high scoring that would be difficult to discard due to small shifts in the core beta sheets.     

Synthesis,Crystal Structure,and Biological Activity of Naphthalen-2-yl4-methyl-1,2,3-thiadiazole-5-carboxylate

The title compound naphthalen-2-yl-4-methyl-1,2,3-thiadiazole-5-carboxylate (C 14 H 10 N 2 O 2 S,M r=270.31) was synthesized by the reaction of 4-methyl-1,2,3-thiadiazole-5-carbonyl chloride with 2-naphthol,and its structure was characterized by IR,1 H NMR,high-resolution mass spectrometry and single-crystal X-ray diffraction.The crystal belongs to orthorhombic,space group Pbcn with a=23.475(5),b=9.6640(19),c=10.814(2),β=90.00°,Z=8,V=2453.2(9) 3,M r=270.30,D c=1.464 g/cm 3,μ=0.262 mm-1,F(000)=1120,R=0.0444 and wR=0.1099.X-ray analysis revealed that the thiadiazole and naphthalene rings were non-planar,while the thiadiazole ring and the ester group were essentially planar,and two intermolecular hydrogen bonds C(6) H(6)···O(1) and C(14) H(14)···O(1) were observed.The preliminary biological test showed that the title compound had antifungal and antivirus activities against tobacco mosaic virus.