30 MeV/u~(40)Ar+~(nat)Ag反应中类弹碎片发射的时-空演化

报道了 ３０ＭｅＶ／ ｕ(４０)Ａｒ＋(ｎａｔ)Ａｇ反应中中等质量碎片（ＩＭＦ）发射时间（τ）随发射源空间大小的演化规律，并对类弹碎片的发射时空进行了讨论．结果表明，ＩＭＦ的发射时标与中等质量碎片关联函数以及发射源的核物质密度（ρ）有关，而与发射源的质量数的关系不大．对于能量较高的类弹碎片来说，在较小的核物质密度下提取的发射时间也较小，因此，在正常核物质密度参数下提取出的发射时间值可作为碎片实际发射时间的上限值．中速碎片的发射时间随密度大小的变化非常缓慢，提取出的发射时间值即可作为实际的发射时间。

Guiding of 150 keV O6+ ions through nanocapillaries in an uncoated Al2O3 membrane: special time dependence of the transmission profile width

This paper reports that the transmission of O6+ ions with energy of 150keV through capillaries in an uncoated Al2O3 membrane was measured, and agreements with previously reported results in general angular distribution of the transmitted ions and the transmission fractions as a function of the tilt angle well fitted to Gaussian-like functions were observed. Due to using an uncoated capillary membrane, our c is larger than that using a gold-coated one with a smaller value of E-p/q, which suggests a larger equilibrium charge Q(infinity) in our experiment. The observed special width variation with time and a larger width than that using a smaller E-p/q were qualitatively explained by using mean-field classical transport theory based on a classical-trajectory Monte Carlo simulation.

Structure of upper-g(9/2)-shell nuclei and shape effect in the Ag-94 isomeric states

Using a shell model which is capable of describing the spectra of upper g(9/2)-shell nuclei close to the N = Z line, we study the structure of two isomeric states 7(+) and 21(+) in the odd-odd N = Z nucleus Ag-94. It is found that both isomeric states exhibit a large collectivity. The 7(+) state is oblately deformed, and is suggested to be a shape isomer in nature. The 21(+) state becomes isomeric because of level inversion of the 19(+) and 21(+) states due to core excitations across the N = Z = 50 shell gap. Calculation of spectroscopic quadrupole moment indicates clearly an enhancement in these states due to the core excitations. However, the present shell model calculation that produces the 19(+)-21(+) level inversion cannot accept the large-deformation picture of Mukha et al.

Enhanced nucleation of Ag nanoparticles by vacancy-type defects in Ar-ions implanted spinel

Vacancy-type defects are introduced into magnesium aluminate spine] (MgAl2O4 (1 1 0)) by Ar-ions implantation, and then Ag-ions are implanted into the depth rich in vacancy-type defects. The ultraviolet-visible spectrometry (UV-VIS) and positron annihilation spectroscopy (PAS) are used to study the influence of vacancy-type defects on nucleation of Ag nanoparticles. After introduction of vacancy-type defects the pronounced increase of surface plasmon resonance (SPR) absorbance intensity indicates that defects enhance the nucleation of Ag nanoparticles. The PAS results reveal that vacancy-type defects provide pre-nucleating centers for Ag nanoparticles nucleation and growth. (C) 2010 Elsevier B.V. All rights reserved.

Structure evolution along the yrast-line in Pd-101

High-spin states in Pd-101 have been investigated experimentally via the Ge-76(Si-28, 3n gamma)Pd-101 reaction. The previously known bands based on the d(5/2) and h(11/2) neutron orbitals have been extended to higher-spin states, and two new structures have been observed. Spin and parity were assigned to the levels on the basis of the experimental results of the angular distribution of gamma rays deexciting the oriented states. For the ground-state band, the E-GOS (E-Gamma Over Spin) curve strongly suggests a structure transition from vibration to rotation while increasing spin.

30MeV/u~(40)Ar+~(nat)Ag反应中中等质量碎片的发射机制及其发射时间测量

中等质量碎片（IMF）的发射是中能重离子碰撞的一大特点，且随着轰击能量的升高其产额迅速增加。通过测量30MeV/u 40Ar+natAg反应中出射的中等质量碎片，研究了高激发热核的发射机制、发射时标和时空演化规律。 对反应中发射碎片能谱的运动源拟合表明，前角区（11°—22°）中等质量碎片（IMF）来自于三种成分：类靶源、类弹源和中速源成分，其中类弹和中速成分占主导，关联测量的IMF能谱拟合得到，一个来自于类弹源而另一个来自于中速源成分的事件占有相当大的比例。 利用小相对角度内的两碎片关联测量，研究高激发核衰变中中等质量碎片的发射时标和寿命。IMF发射时间随能量的变化很大，从低能碎片的250 fm/c到高能粒子的100 fm/c，表明在此能量下，反应中出射的IMF主要来自于相继两体衰变。通过与其它实验的比较可知，随着束流能量的升高，IMF发射时间由相继两体衰变向多重碎裂过渡。 IMF时空演化研究表明，发射空间的大小对IMF关联函数的影响主要来自于发射源的核物质密度而几乎不依赖于发射源的质量数。

中能区~(40)Ar + ~(197)Au/~(159)Tb/~(nat)Ag反应中高激发热核性质研究

通过对中能区Ar+Au/Tb/Ag反应中高激发核的发射时标、发射次序、发射机制、核温度、集体运动等衰变特性的研究，提取了轻粒子和中等质量碎片（IMF）的发射时间，IMF发射时间随束流能的升高而变短，发射机制逐渐由相继衰变过渡至多重碎裂。研究了轻粒子和碎片间的发射次序，对高能粒子和碎片，轻粒子先于碎片发射，而低能时，则为碎片先于轻粒子发射。IMF发射成分与角度和碰撞参数有关，前角区来自于弹核碎裂，后角区来自于类靶热核的蒸发。在平面和出平面研究表明，中速粒子和碎片为在平面发射占主导，即存在类转动效应；对轻粒子，转动效应随粒子质量增加而增加；对中速产物均观测到该效应随碰撞参数饿增大而增大。采用几种不同的方法提取了热核的核温度，研究了不同方法之间的区别。

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.

Pd/sulfated alumina - a new effective catalyst for the selective catalytic reduction of NO with CH4

Sulfated alumina (SA) is firstly found to be an effective support for Pd catalyst used in the SCR of NO with methane. The sulfation is important to increase support's acidity which is essential for the reduction of NO over Pd catalysts. On consideration of the lower cost and easier availability of SA, we believe that SA is more promising to act as the commercial support for Pd catalyst used in the SCR of NO with methane.

Synthesis of NaA zeolite membrane on a ceramic hollow fiber

NaA zeolite membrane was successfully synthesized on a ceramic hollow fiber with an outer diameter of 400 mum, a thickness of 100 mum and an average pore radius of 0.1 mum. The as-synthesized membranes were characterized by XRD, SEM as well as gas permeation. A continuous C NaA zeolite membrane formed after a three-stage synthesis. The membrane thickness was similar to5 mum. Gas permeation data indicated that a relatively high quality NaA zeolite membrane formed on the ceramic hollow fiber support. (C) 2003 Elsevier B.V. All rights reserved.