质子滴线区新核素~(25)P的鉴别

在兰州放射性束流装置 RIBLL上 ,利用磁刚度 Bρ、飞行时间 t TOF和多重望远镜ΔE- E联合探测方法测量了 69Me V/u36Ar轰击 Be靶产生的 P同位素碎片的同位素分布 ,并与 EPAX经验公式的计算结果进行了比较 ,在质子滴线区首次鉴别出了新核素 2 5P.

Kinetic energy and charge state effects in the X-ray emission of Mo surface induced by Xeq+ (q=25, 29) ions

L-shell X-ray spectra of Mo surface induced by Xe25+ and Xe29+ were measured. The X-ray intensity was obtained in the kinetic energy range of the incident ions from 350 to 600 keV. The relationship of X-ray intensity with kinetic energy of the projectile and its charge state were studied, and the simple explanation was given.

Molybdenum L-shell X-ray production by 350-600 keV Xeq+ (q=25-30) ions

Molybdenum L-shell X-rays were produced by Xeq+ (q = 25-30) bombardment at low energies from 2.65 to 4.55 keV/amu (350-600 keV). We observed a kinetic energy threshold of Mo L-shell ionization down to 2.65-3.03 keV/amu (350-400 keV). The charge state effect of the incident ions was not observed which shows that the ions were neutralized, reaching an equilibrium charge state and losing their initial charge state memory before production of L-shell vacancies resulted in X-ray production. The experimental ionization cross sections were compared with those from Binary Encounter Approximation theory. Taking into account projectile deflection in the target nuclear Coulomb field, the ionization cross section of Mo L-shell near the kinetic energy threshold was well described. (C) 2010 Published by Elsevier B.V.

25MeV/u Kr辐照下PET薄膜的损伤机制研究；Damage Mechanism of PET Irradiated by 25 MeV/u Kr Ions

通过25MeV/u86Kr离子辐照叠层结晶聚对苯二甲酸乙二醇酯膜(PET),在不同的电子能损(3.407.25keV/nm)和离子注量(5×10113×1012ions/cm2)辐照条件下,对Kr离子在PET中引起的辐照损伤效应进行了研究。借助傅里叶变换红外光谱分析,通过对样品的红外吸收峰进行扣除基底后的Lorentz拟合,分析了与主要官能团对应的吸收峰强度的变化趋势,研究了化学结构与组分在重离子辐照下的变化规律;利用X射线衍射光谱仪测量,研究了Kr离子在PET潜径迹中引起的非晶化过程,并通过对吸光度和非晶化强度随离子注量的指数衰减规律的分析,获得了不同电子能损离子辐照PET时主要官能团的损伤截面和非晶化截面及对应的潜径迹半径。

多丝正比室的研制与25 MeV/u 40Ar + 93Nb反应中轻粒子的发射时间测量

本论文共由两部分组成。第一部分描述了多丝正比室的研制过程。第二部分研究了中能区25MeV/u ~(40)Ar + ~(93)Nb反应中轻粒子发射时间的测量。本论文所研制的多丝正比室灵敏面积为5cm * 5cm。阳极丝由10μm的镀金钨丝组成，丝与丝之间的间距为0.5mm。工作气体为正庚烷，采用感应信号重心读出方法。调试了工作气压在25Torr左右、工作电压～1400v条件下多丝室的工作状态，结果表明该工作条件下，多丝正比室并未工作于正比状态下，须适当增加工作电压和工作气压才能得到较好的位置分辨。并且提出进一步的改进建议。第二部分利用小相对角度内的两粒子关联测量，研究了中能区25MeV/u ~(40)Ar + ~(93)Nb反应中高激发核衰变产生的轻粒子的发射时标。轻粒子发射时间随能量的变化很大，从低能粒子的约500fm/c变化至高能粒子的50fm/c，表明高能粒子来自于热核的早期发射，包含有前平衡发射的粒子，而低能粒子来自于平衡热核的发射。随着入射能的升高和激发能的增加，热核的寿命及其发射时标变短。轻粒子时空演化表明，发射源的核物质密度对轻粒子关联函数的影响较大，尤其是对于发射时间较(τ ≤ 100fm/c)的高能粒子的关联函数，这一影响随着粒子能量降低而减弱。在发射时间较长(τ ≤ 200fm/c)时，这种影响几乎消失。另外随着实验室系角度的增加，平衡发射成分增加，相应地提取的轻粒子的发射时间变长。

Methanol synthesis from CO2 using a silicone rubber/ceramic composite membrane reactor

A one-dimensional isothermal pseudo-homogeneous parallel flow model was developed for the methanol synthesis from CO2 in a silicone rubber/ceramic composite membrane reactor. The fourth-order Runge-Kutta method was adopted to simulate the process behaviors in the membrane reactor. How those parameters affect the reaction behaviors in the membrane reactor, such as Damkohler number Da, pressure ratio p(r), reaction temperature T, membrane separation factor alpha, membrane permeation parameter phi , as well as the non-uniform parameter of membrane permeation L-1, were discussed in detail. Parts of the theoretical results were tested and verified; the experimental results showed that the conversion of the main reaction in the membrane reactor increased by 22% against traditional fixed bed reactor, and the optimal non-uniform parameter of membrane permeation rate, L-1.opt ,does exist. (C) 2003 Elsevier B.V All rights reserved.

CO selective oxidation in a microchannel reactor for PEM fuel cell

It is indispensable to remove CO at the level of less than 50ppm in H-2-rich feed gas for the proton exchange membrane (PEM) fuel cells. In this paper, catalyst with high activity and selectivity, and a microchannel reactor for CO preferential oxidation (PROX) have been developed. The results indicated that potassium on supported Rh metal catalysts had a promoting effect in the CO selective catalytic oxidation under H-2-rich stream, and microchannel reactor has an excellent ability to use in on-board hydrogen generation system. CO conversion keeps at high levels even at a very high GHSV as 500 000 h(-1), so, miniaturization of hydrogen generation system can be achieved by using the microchannel reactor. (C) 2004 Elsevier B.V. All rights reserved.

Novel cobalt-free oxygen permeable membrane

A series of cobalt-free and low cost perovskite oxygen permeable membranes based on BaCexFe1-xO3-delta (BCF) oxides was successfully synthesized and the membrane showed both high oxygen permeability and high stability under reductive atmosphere, which will be most suitable for constructing a membrane reactor for selective oxidation of light hydrocarbons to syngas or high value corresponding oxygenates.

Catalytic partial oxidation of gasoline to syngas in a dense membrane reactor

In our previous work, it was shown that LiLaNiO/gamma-Al2O3 was an excellent catalyst for partial oxidation of heptane to syngas in a fixed-bed reactor at high temperature and the selectivity of CO was about 93%. However, pure oxygen was used as the oxidant. We have developed a dense oxygen permeation membrane Ba0.5Sr0.5Co0.8Fe0.2O3 that can supply pure oxygen for the reaction. In this work, the membrane was combined with the catalyst LiLaNiO/gamma-Al2O3 in one rector for the partial oxidation of heptane that is typical component of gasoline. A good performance of the membrane reactor has been obtained, with 100% n-heptane conversion and >94% hydrogen selectivity at the optimized reaction conditions. (C) 2004 Elsevier B.V. All rights reserved.