Radiation Defects Research in Single Crystals of Lithium Niobate

An information is given on the kinetics of developing ionization defects by γ-radiation, as well as on the destroying of these defects as a result of thermal treatment in oxidizing atmosphere at different temperatures. The presence of several types of ionization defects developing by γ-radiation is found out. Values of diffusion factor for each type of defects are given.     

退火处理对DKDP晶体光学均匀性的影响研究

分别对不同生长速度的DKDP晶体进行了退火处理.结果表明,适当温度的退火处理能有效地提高晶体的光学均匀性,尤其是对快速生长的晶体质量提高更为显著.在实验温度范围内,退火温度越高,质量改善越明显.对退火机理进行了初步讨论.     

微波等离子CVD金刚石设备中基片加热材料的三维温度场型研究

在微波等离子CVD设备中,微波电磁场的不均匀分布将导致等离子球和基片的温度不均匀,从而降低CVD金刚石的质量,因而基片加热是需要的.材料的吸收微波能的能力同微波频率、电场强度、材料的介电常数和介电损耗及材料体积相关,材料的介电常数、介电损耗、导热率又同温度相关.基于热力学理论,本文用强吸收微波能的SiC材料作为了基片加热材料,放在微波等离子腔的基片下,研究三维轴对称温度场模型,该模型的基片加热材料的介电常数、介电损耗和体积随温度变化,获得了温度分布的解析式,计算结果显示该模型能得到直径76.2mm的均匀温度分布,温度变化少于10℃,因而可用于基片加热.     

Trapped Bose condensate in a gravitational field

The Bose condensation of atoms in finite 1D and 2D parabolic traps placed in a gravitational field is considered. The distortion of the trap potential in this field is modeled by a combination of two rectangular 1D and 2D traps. The change in the critical temperature T _c is found with regard to the cutoff and renormalization of the spectrum of these model potentials. The shift of the critical temperature T _c in the gravitational field is calculated. The shift sign and magnitude depend on the way of introducing the gravitational field. For a certain choice, three critical temperatures can be sequentially observed. These temperatures can be attributed to three Bose condensations that occur in the cyclic motion of the trap along the Earth (I)-space (II)-Earth (III) route.     

一种新的光催化氧化体系用于化学需氧量的测定研究

基于KMnO₄能获得光生电子从而提高半导体光催化氧化能力的原理,建立了一种用纳米ZnO-KMnO₄协同体系光催化测定化学需氧量(COD)的新方法,探讨了催化氧化测定COD的机理,考察了测定COD的最佳反应条件.COD值浓度在1.5～10mg/L范围内与信号呈良好的线性关系,检测限为0.5mg/L.用本方法测定实际水样,结果和标准高锰酸盐指数法(COD_Mn法)相符.     

Determination of Reactive Intermediates During Anodic Oxygen-transfer Reactions at Lead Dioxide

IntroductionSincethepastdecade ,electrochemicalmethodsforelectrosynthesis ,wastewatertreatmentandorgan iccompounddeterminationhavebeenwidelydevel oped[1— 6 ] .Thebasicprincipleisthatorganicsub stancesareelectrochemicallyoxidizedintothedesiredproducts.However ,inmanycasesthedirectoxida tionoforganicspeciesinanaqueoussolutionatasim plemetaloracarbonelectrodeisnotpossiblebecausethehighpotentialsrequiredfortheoxidationoforgan iccompoundsusuallyresultinoxygenevolution .Therefore ,theproperchoiceof…     

Theoretical Estimate of Hydride Affinities of Aromatic Carbonyl Compounds

Aromatic carbonyl compounds are one type of the most important organic compounds, and the reductions ofthem by hydride agents such as LiAlH4 or NaBH4 are widely used in organic synthesis. The reactivity of carbonyl compounds generally increases in the following order: ketone ＜ aldehyde, and amide ＜ acid ＜ ester ＜ acid halide, which could be related to their hydride affinities (HA). In the previous paper, Robert[1] calculated the absolute HAof a series of small non-aromatic carbonyl compounds. In this paper, we use DFT method at B3LYP/6-311 + + G (2d, 2p)∥B3LYP/6-31 + G* level to estimate hydride affinities of five groups of aromatic carbonyl compounds. The detailed results are listed in Table 1.     

不同产地积雪草中的微量元素比较研究

用火焰原子吸收分光光度法测定了７个不同产地的中药材积雪草中８种微量元素Ｆｅ、Ｃｕ、Ｃｕ、Ｚｎ、Ｍｎ、Ｃｏ、Ｃｄ、Ｓｒ、Ｃｒ的含量,并进行了比较,结果表明中药材中微量元素含量因地而异。为药材道 地性研究,药理作用探讨及临床用药提供了依据。     

TiO2纳米微粒对PPV发光性能的影响

采用溶胶凝胶法制备了一系列PPV/TiO₂纳米复合膜,探讨了TiO₂纳米微粒对PPV发光性能的影响.研究发现,这些复合膜的发光性质依赖于TiO₂/PPV的质量比,.在TiO₂/PPV的质量比为1/9时,复合膜中的TiO₂微粒对PPV的荧光具有猝灭作用;当TiO₂/PPV的质量比为1/1时,复合膜中的TiO₂对PPV的荧光具有增强作用.通过FT-IR,UV-Vis,FL光谱和TEM探讨了复合膜微结构与其发光性质的关系.