用放射性示踪法研究分离铀和铅、铋

用放射性示踪法研究了TBP -苯体系对铀和铅、铋的萃取分离。实验结果表明 ,在 6mol LHNO3 介质中用TBP -苯作为萃取剂可使铀和铅、铋达到定量分离。阴离子交换法对铀进一步纯化后 ,利用分子电镀法制得厚度为 50 0 μg cm2 的2 3 3 U同位素靶

Topological structure of the solitons solution in SU(3) Dunne-Jackiw-Pi-Trugenberger model

By using phi-mapping topological current theory and gauge potential decomposition, we discuss the self-dual equation and its solution in the SU(N) Dunne-Jackiw-Pi-Trugenberger model and obtain a new concrete self-dual equation with a 6 function. For the SU(3) case, we obtain a new self-duality solution and find the relationship between the soliton solution and topological number which is determined by the Hopf index and Brouwer degree of phi-mapping. In our solution, the flux of this soliton is naturally quantized.

缺中子奇质量数Au核高自旋态能级结构研究

利用能量为164-180MeV的35Cl束流，通过重离子核反应149Sm(35Cl,5n) 研究了179Au的高自旋态能级结构。实验进行了γ射线的激发函数、X-γ和γ-γ-t符合测量。基于实验测量结果，首次建立了179Au的1/2[660](πi13/2)转动带。结合已有的实验数据，着重讨论了奇-A Au核中1/2[660](πi13/2) 转动带的形变和带头激发能随中子数的变化。用能量为140MeV的29Si束流轰击159Tb金属靶，布居了183Au核的高自旋态。实验中要求至少有3个高纯锗和2个BGO探测器同时点火，在此符合条件下，记录高纯锗探测器探测到的γ射线的能量和相对时间、BGO探测到的γ射线的总能量和多重性。通过对实验数据的分析，扩展并更新了183Au的能级纲图。首次建立了183Au的πi13/2转动带的能量非优先带。分析并讨论了缺中子奇-A Au中πh9/2转动带的能量非优先带和πf7/2转动带间的相互作用

Pressure drops of single and two-phase flows through T-type microchannel mixers

In this paper, preliminary experimental results are presented on pressure drop characteristics of single and two-phase flows through two T-type rectangular microchannel mixers with hydraulic diameters of 528 and 333 mum, respectively. It is shown that both N-2 and water single-phase laminar flows in microchannels, with consideration of experimental uncertainties, are consistent with classic theory, if additional effects, such as entrance effects that will interfere with the interpretation of experimental results, are eliminated by carefully designing the experiments. The obtained pressure drop data of N-2-water two-phase flow in micromixers are analyzed and compared with existing flow pattern-independent models. It is found that the Lockhart-Martinelli method generally underpredicts the frictional pressure drop. Thereafter, a modified correlation of C value in the Chisholm's equation based on linear regression of experimental data is proposed to provide a better prediction of the two-phase frictional pressure drop. Also among the homogeneous flow models investigated, the viscosity correlation of McAdams indicates the best performance in correlating the frictional pressure drop data (mean deviations within +/-20% for two micromixers both). Finally it is suggested that systematic studies are still required to accurately predict two-phase frictional performance in microchannels. (C) 2004 Elsevier B.V. All rights reserved.

《景观生态学原理与方法》简介

由国际著名景观生态学家、国际生态学会秘书长、意大利Ｌｕｎｉｇｉａｎａ自然博物馆主任法瑞纳（ＡｌｍｏＦａｒｉｎａ）博士撰写的又一部景观生态学力作《景观生态学原理与方法》（Ｐｒｉｎｃｉｐｌｅａｎｄｍｅｔｈｏｄｓｉｎｌａｎｄｓｃａｐｅｅｃｏｌｏｇｙ）已于１...

不同施肥模式下作物收获物中微量元素含量及其分配研究

以下辽河平原一组18年的定位试验为平台,研究长期不同施肥处理作物收获物中Fe、Mn、Zn、Cu含量及其分布。结果表明:作物收获物中微量元素含量表现为Fe>Mn、Zn>Cu,且玉米收获物各元素含量远高于大豆;处理间微量元素含量差异显著,表现为NPK+M>NPK>M>CK;作物收获物中微量元素含量与作物籽实或秸秆产量间有显著相关性,玉米收获物中Fe、Mn、Zn、Cu含量与秸秆产量的线性回归关系中R2分别为0.99、0.94、0.92、0.87,大豆收获物中Fe、Mn含量与秸秆产量的线性回归关系中R2均为0.97,Zn、Cu与籽实产量的线性回归关系中R2分别为1.00和0.97。不同施肥处理间微量元素分配存在变异,但总体仍表现为玉米收获物中微量元素主要分配在秸秆中,而大豆籽实富集了大量的微量元素。采用秸秆还田等养分循环再利用措施,可实现农田微量元素可持续发展,因而应在农村加强秸秆还田等养分循环再利用措施的应用。

Thermodynamic study of ibuprofen by adiabatic calorimetry and thermal analysis

Molar heat capacities of ibuprofen were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 80 to 400 K. The polynomial functions of C-p,C-m (J K-1 mol(-1)) versus T were established on the heat capacity measurements by means of the least fitting square method. The functions are as follows: for solid ibuprofen, at the temperature range of 79.105 K less than or equal to T less than or equal to 333.297 K, C-p,C-m = 144.27 + 77.046X + 3.5171X(2) + 10.925X(3) + 11.224X(4), where X = (T - 206.201)/127.096; for liquid ibuprofen, at the temperature range of 353.406 K less than or equal to T less than or equal to 378.785 K, C-p,C-m = 325.79 + 8.9696X - 1.6073X(2) - 1.5145 X-3, where X = (T - 366.095)/12.690. A fusion transition at T = 348.02 K was found from the C-p-T curve. The molar enthalpy and entropy of the fusion transition were determined to be 26.65 kJ mol(-1) and 76.58 J mol(-1) K-1, respectively. The thermodynamic functions on the base of the reference temperature of 298.15 K, (H-T - H-298.15) and (S-T - S-298.15), were derived. Thermal characteristic of ibuprofen was studied by thermo-gravimetric analysis (TG-DTG) and differential scanning calorimeter (DSC). The temperature of fusion, the molar enthalpy and entropy of fusion obtained by DSC were well consistent with those obtained by adiabatic calorimeter. The evaporation process of ibuprofen was investigated further by TG and DTG, and the activation energy of the evaporation process was determined to be 80.3 +/- 1.4 kJ mol(-1). (C) 2003 Elsevier B.V. All rights reserved.

Liquid-phase hydrodechlorination of chlorinated benzenes over active carbon supported nickel catalysts under mild conditions

Liquid phase hydrodechlorination of chlorinated benzenes was studied over Ni/active carbon (Ni/AC), Ni/gamma-Al2O3, Ni/SiO2 and Raney Ni. The complete dechlorination of chlorobenzene (ClBz) was realized at 333-343 K on Ni/AC under hydrogen atmosphere of 1.0 MPa in the presence of alkaline hydroxide. Dichloro- and trichlorobenzenes were also hydrodechlorinated with 50-95% yields of benzene under the similar conditions, as above. The reaction follows zero-order to ClBz concentration and 1.9 order to hydrogen pressure. The reaction does not proceed in the absence of alkaline hydroxide, suggesting the complete coverage of active nickel surface with produced chlorine and the removal of the chlorine ion with hydroxide ion as a rate-limiting step. The active catalysts were characterized by H-2 chemisorption and transmission electron microscopy techniques. The apparent activity strongly depends on the active area of nickel on catalyst surface. (C) 2004 Published by Elsevier B.V.

Multiphoton ionization and ab initio calculation studies of pyridine-water mixed clusters using time of flight mass spectrometer

Multiphoton ionization of binary mixed clusters (C5H5N)(x)-(H2O)(y) at 532, 355 and 266 nm laser wavelengths has been investigated using TOF mass spectrometer. The experiments showed that almost all the products were protonated ions, At 532 and 355 nm, the products were mainly protonated pyridine clusters (C5H5N)(n)-H+, while at 266 nm, mixed binary cluster ions (C5H5N)(m)- (H2O)(n)-H+ appeared. It was found that the abundance of the [(C5H5N)(3)-H2O-H](+) ions was abnormally high. The calculation indicated that the ion [(C5H5N)(3)-H2O-H](+) is Of a kind of magic number structures with C-3v symmetry. A stepwise reaction mechanism is suggested that photoionization is followed by dissociation. (C) 2001 Elsevier Science B.V. All rights reserved.