Low-spin signature inversion in the pi h(9/2)circle times nu i(13/2) oblate band

Excited states in Tl-188,Tl-190 have been studied experimentally by means of in-beam gamma spectroscopy techniques, and resulted in the identification of a strongly coupled band based on the pi h(9/2) circle times nu i(13/2) configuration with oblate deformation. The oblate band in doubly odd Tl nuclei shows low-spin signature inversion. It is the first experimental observation of low-spin signature inversion for a band associated with the oblate pi h(9/2) circle times nu i(13/2) configuration.

Photoluminescence of inert-gas ion implanted sapphire after 230-MeV Pb ion irradiation

In the present work the photoluminescence (PL) character of sapphire implanted with 110-keV He, Ar or Ne ions and subsequently irradiated with 230-MeV Pb was studied. The implantation was performed at 320 and 600 K using fluences from 5.0 x 10(16) to 2.0 x 10(17) ions/cm(2). The Pb ion irradiation was carried out at 320 K. The obtained PL spectra showed peaks at 375, 413 and 450 nm with maximum intensity at an implantation fluence of 5.0 x 10(16) ions/cm(2) and a new peak at 390 nm appeared in the He-implanted and subsequently Pb-irradiated samples. Infrared spectra showed a broadening of the absorption band between 460 and 510 nm indicating strongly damaged regions formed in the Al2O3 samples. A possible PL mechanism is discussed.

奇奇核170Re在束g谱学和176Ir EC/b+衰变研究

本论文在 166MeV 的束流能量下，利用重离子熔合蒸发反应 142 Nd（32 S， 1p3nγ ）170 Re 布居了 170 Re 的高自旋激发态，用 12 套带 BGO反康普顿抑制的高 纯锗探测器阵列进行了在束 X-γ 和γ γ − 符合测量。在 210MeV 的束流能量下， 利用重离子熔合蒸发反应 146 Nd（35 Cl，5nγ ）176 Ir 产生具有 β+ / EC 衰变性质的 核素 176 Ir, 由氦喷嘴快速带传输系统将反应产物送到低本底区，用一台小平面探 测器、一台轴对称型高纯锗探测器和一台 CLOVER 探测器进行了γ γ − 符合和 t γ − 单谱测量。基于这些测量结果，研究了 170 Re 的高自旋态和 176 Ir 的 β+ / EC 衰变性质。 本工作基于γ−γ符合关系及周围邻近核已知信息的综合分析，首次建立了包 括 16 个能级 26 条γ 跃迁的双奇核 170 Re 的转动带能级纲图，并利用推转壳模型、 粒子转子模型等对其进行了分析和讨论。根据实验提取出的准粒子顺排、 Routhian、旋称劈裂等结构信息和邻近双奇核带结构系统学知识的比较分析，指 出该带的两准粒子组态是 11/213/2 hi π ν ⊗ ，并且该带在低自旋出现旋称反转。 基于对 176 Ir 核 β+ / EC衰变实验数据的离线处理分析，对早先发表的 176 Ir 衰 变γ 跃迁进行确认的同时又发现了 4 个新能级和 13 条新的γ 射线，丰富了 176 Os 核的低位激发态能级纲图。根据典型γ 射线的衰变时间谱建议了 176 Ir核的一个长 寿命低自旋同核异能态，同时通过两准粒子耦合的半经验计算建议了其组态。

Preparation of Mn substituted La-hexaaluminate catalysts by using supercritical drying

LaMnxAl12-xO19 catalysts were prepared from NH4OH and metal nitrates solutions. Supercritical drying (SCD) and conventional oven drying (CD) methods were used to extract the water in the hydrogel. The effects of drying methods on properties of the catalysts were investigated by means of TEM, N-2-adsorption, thermogravimetry (TG)-differential thermal analysis (DTA) and X-ray diffraction. SCD method is beneficial to maintain high surface area and improving catalytic activity for methane combustion of the catalyst. The specific surface area and pore volume of LaMn1Al11O19 catalyst prepared by SCD method are 28 m(2)/g and 0.23 cm(3)/g, respectively, and the ignition of methane could be carried out at 450degreesC. However, those of the CD catalyst prepared from the same precursor are 15 m(2)/g, 0.11 cm(3)/g and 530 degreesC, respectively. Suitable Mn content (0 less than or equal to x less than or equal to 2) could promote the formation of LaMnAl11O19 hexaaluminate, while further addition of Mn (2 less than or equal to x less than or equal to 6) cause the formation of LaMnO3. (C) 2003 Elsevier B.V All rights reserved.

Analytical potential energy function and spectroscopic parameters for the ground and excited states of NaH

set of energies at different internuclear distances for the ground electronic state and two excited electronic states of NaH molecule have been calculated using valence internally contracted multireference configuration interaction(MRCI) including Davidson correction and three basis sets. Then, a potential energy curve (PEC) for each state was determined by extrapolating MRCI energies to the complete basis sets limit. Based on the PECs, accurate vibrational energy levels and rotational constants were determined. The computational PECs are were fitted to analytical potential energy functions using the Murrell-Sorbie potential function. Then, accurate spectroscopic parameters were calculated. Compared with experimental results, values obtained with the basis set extrapolation yield a potential energy curve that gives accurate vibrational energy levels, rotational constants and spectroscopic parameters for the NaH molecule. (C) 2004 Elsevier B.V. All rights reserved.

Nafion/PTFE composite membranes for fuel cell applications

Porous polytetrafluoroethylene (PTFE) membranes were used as support material for Nafion((R))/PTFE composite membranes. The composite membranes were synthesized by impregnating porous PTFE membranes with a self-made Nafion solution. The resulting composite membranes were mechanically durable and quite thin relative to traditional perfluorosulfonated ionomer membranes (PFSI); we expect the composite membranes to be of low resistance and cost. In this study, we used three kinds of porous PTFE films to prepare Nafion/PTFE composite membranes of different thickness. Scanning electron micrographs and oxygen permeabilities showed that Nafion resin is distributed uniformly in the composite membrane and completely plug the micropores, there is a continuous thin Nation film present on the PTFE surface. The variation in water content of the composite and Nafion 115 membranes with temperature was determined. At the same temperature, water content of the composite membranes was smaller than that of the Nafion 115. In both dry and wet conditions, maximum strength and break strength of C-325(#) and C-345(#) were larger than those of Nafion 112 due to the reinforcing effect of the porous PTFE films. And the PEMFC performances and the lifetime of the composite membranes were also tested on the self-made apparatus. Results showed that the bigger the porosity of the substrate PTFE films, the better the fuel cell performance; the fuel cell performances of the thin composite membranes were superior to that of Nation 115 membrane; and after 180 h stability test at 500 mA/cm(2), the cell voltage showed no obvious drop. (C) 2002 Published by Elsevier Science B.V.

干旱区地表石油污染物风蚀作用大气传输量估算研究

通过焉耆盆地石油开发区石油污染物水环境污染途径特点的分析 ,认为落地油将通过风蚀作用由大气传输以降尘的形式落入水体 ,对水环境产生影响。本文以土壤侵蚀的风洞实验求得污染源源强 ,采用高斯模式对地表风蚀作用的传输量进行估算 ,进而对石油开发区落地油通过大气传输途径对区域水环境 (博斯腾湖 )的影响进行了预测 ,建立了相应的模型。为人们了解干旱区石油污染物风蚀作用水环境污染影响提供了初步依据 ,对干旱区湖泊石油污染的全面防治提供了科学范式

Data analysis for pump-probe experiment with femtosecond pulses

Various analytical physical models are presented to extract the photodissociation dynamics information from the data obtained in the femtosecond pump-probe experiment. The single- and double-component models are employed to explain the single- and double-channel dissociation of parent molecules. Another single-component model for fragment dissociation or deexcitation is also presented. All cases are explanatorily demonstrated on the pump-probe experimental data.

坡面植物生长期内对~7Be的截留吸收及影响因素分析

对坡面植物在生长期内7Be含量的动态变化进行研究,发现随着生长植物在生长期内7Be含量增加,单位面积上植物截留吸收7Be量增加;研究区坡面7Be的植被截留吸收率为3.35%~8.44%,说明植被覆盖对土壤中7Be含量有重要的影响。同时还发现,不同采样间隔期7Be日均增量不定,在整个采样期内变异性大,变异系数为0.69,但从春季到夏季的前4个采样间隔期变异性相对较小;不同采样间隔期7Be日均增量和日均降雨量呈正比,相关系数为0.64。

人参皂苷β-葡萄糖苷酶的分离纯化及其酶学特性

通过硫酸铵分级沉淀、透析和高效液相色谱等技术分别从两株黑曲霉Aspergillusniger 4 8g和A .niger 84 8g中分离纯化出了具有水解人参皂苷葡萄糖苷键的 β 葡萄糖苷酶 ,并对其酶学特性进行了研究 .结果表明 :两株黑曲霉A .niger 4 8g和A .niger 84 8g所产的 β 葡萄糖苷酶的表观分子量不同 ,分别为 34× 10 3 和 31× 10 3 kD ;两株菌所产的 β 葡萄糖苷酶的反应特性基本相同 .图 4表 4参 15

沈阳城市森林固碳和污染物净化效益差异初探

城市森林效益是城市森林建设和规划的重要依据,为寻求城市森林效益差别的原因,采用抽样调查方法,对沈阳三环内城市森林213块样地进行实地每木调查,在基于CITYgreen模型基础之上对城市森林所产生的碳密度、固碳率以及污染物净化效益进行对比分析,结果表明:等密度等胸径条件下城市森林效益基本趋于多层林>复层林>单层林;平均树高与碳密度之间以及平均树高与污染物净化量之间基本呈现"S"曲线关系;在平均胸径相等的低密度条件下,城市森林效益随密度的增加而增大;混交林随着年龄的增长随密度的增加效益表现出先增加后降低的趋势;单株树木碳密度和污染物净化量均与单株树木三维绿量之间呈现幂函数关系;不同森林类型碳密度和污染物净化量变化趋势为附属林>风景游憩林>生态公益林>生产经营林>道路林;而固碳率为生态公益林>风景游憩林>生产经营林>附属林>道路林。

施用控释尿素后土壤尿素氮的转化及其对产量的影响

主要研究施用控释尿素后土壤中尿素氮(NH4+-N、NO3--N)的变化及其对玉米增产效率的影响。结果表明:3种控释尿素能够增加土壤中NH4+-N的含量,抑制NH4+-N向NO3-N的转化,降低了NO3--N的淋失损失,减少了对环境的污染。同时能增加玉米各生育时期氮的含量,提高了玉米的产量。图3,表1,参12。