惰性气体离子注入铝镁尖晶石合成金属纳米颗粒的探索

实验在表面蒸镀了金属(Cu,Au)薄膜的尖晶石(MgAl2O4)样品中注入惰性气体离子(Ar,He),随后对注入样品进行了退火处理.在紫外可见光谱上观察到了由于金属纳米颗粒存在引起的较强的表面等离子体共振吸收峰,提供了材料中金属纳米颗粒形成的证据.采用这种方法在材料中引入金属纳米颗粒,发现影响金属纳米颗粒形成的因素除了退火温度外,金属薄膜厚度的影响不可忽略.

An 8.1 Ma calcite record of Asian summer monsoon evolution on the Chinese central Loess Plateau

IEECAS SKLLQG

中能重离子碰撞中同位旋分馏的同位旋效应

基于改进的同位旋相关量子分子动力学模型 ,研究了中能重离子碰撞中同位旋分馏强度(N Z) 气 (N Z) 液 随着碰撞系统中子 -质子比和碰撞参数的变化所呈现出的同位旋效应 ,得到了一些有兴趣的结果 .如在碰撞系统质量、入射能量和碰撞参数固定的条件下 ,(N Z) 气 (N Z) 液 随碰撞系统中子 -质子比的增加而增加 .对于丰中子系统而言 ,(N Z) 气 (N Z) 液 灵敏地依赖于对称势而较弱地依赖于核子 -核子碰撞截面 ;而缺中子系统 ,(N Z) 气 (N Z) 液 对于对称势和介质中核子 -核子碰撞截面都不灵敏 .对于造成这种现象的物理机制进行了分析和讨论 .一般核反应中 ,碰撞参数是各种物理观测量的灵敏函数 ,但计算结果表明同位旋分馏强度对于碰撞参数并不灵敏 ,故对于丰中子系统而言 ,同位旋分馏强度是提取对称势知识的灵敏物理观测量 .

锇的一个重同位素:~(197)Os

利用14 MeV中子轰击天然铂靶,通过~(198)Pt(n,2p)~(197)Os反应产生锇的一种同位素~(197)Os,以γ(X)谱学方法鉴别了它,同时研究了它的衰变性质。观测到了能量为41.2、50.7、196.8、199.6、223.9、233.1、250.2、342.1、403.6和406.4keV的10条新γ射线,并指定为~(197)Os的衰变。测定它的半衰期为2.8±0.6 min。

加速器自动调束系统的研究

描述了加速器自动调束系统的设计方法,介绍了加速器调束工作的现状和实现自动调束的意义,阐述了基于遗传算法进行加速器自动调束的原理和加速器自动调束系统的设计方法,给出了计算机仿真实验结果,并指出了自动调束研究的发展方向.

不同初始温度时Na_8+Na_8团簇碰撞动力学研究

采用距离相关紧束缚的分子动力学模型 ,在不同初始温度T0 =0 .0 2K、50K、10 0K、2 0 0K、30 0K、4 0 0K时 ,对Na8+Na8在质心系轰击能量为 0 .0 12 5eV/n的中心碰撞时的反应动力学进行了研究。发现团簇碰撞动力学与初始温度密切相关。在T0 <10 0K时 ,初始温度不影响反应动力学 ,而在T0 =4 0 0K时将对反应动力学有强烈影响。

Systematic study of properties of Hs nuclei

The ground-state properties of Hs nuclei are studied in the framework of the relativistic meanfield theory. We find that the more relatively stable isotopes are located on the proton abundant side of the isotopic chain. The last stable nucleus near the proton drip line is probably the (255)Hs nucleus. The alpha-decay half-lives of Hs nuclei are predicted, and together with the evaluation of the spontaneous-fission half-lives it is shown that the nuclei, which are possibly stable against spontaneous fission are (263-274)Hs. This is in coincidence with the larger binding energies per nucleon. If (271-274)Hs can be synthesized and identified, only those nuclei from the upper Z = 118 isotopic chain, which are lighter than the nucleus (294)118, and those nuclei in the corresponding alpha-decay chain lead to Hs nuclei. The most stable unknown Hs nucleus is (268)Hs. The density-dependent delta interaction pairing is used to improve the BCS pairing correction, which results in more reasonable single-particle energy level distributions and nucleon occupation probabilities. It is shown that the properties of nuclei in the superheavy region can be described with this interaction.

Ar16+ 离子与Au和Mo靶相互作用产生的X射线截面随入射角度的变化

本实验工作是在兰州重离子加速器国家实验室ECR离子源完成。实验采用能量为336keV的低能高电荷态Ar16+离子轰击Au、Mo金属靶，入射离子与靶表面之间的夹角分别是20°，25°，……，80°，入射角与出射角之和为90°。测量了不同角度下Mo的Lα、Lβ，Au的Mα和Ar的Kα特征X射线谱，对实验谱进行了高斯拟合，计算了不同入射角下的各条X射线的产额和产生截面，并将靶原子发射出的X射线截面与ECPSSR和带结合能修正的BEA理论计算的结果进行了比较。发现当入射角较小时，Ar16+与金属靶相互作用时所产生出的各条特征X射线截面随入射角的增加而增加，当入射角达到40°左右后X射线截面基本上保持不变。与ECPSSR计算值相比，本实验中Au的X射线截面比较接近，实验值比ECPSSR计算值小不到一个量级；而Mo的X射线截面实验值比ECPSSR计算值大3-4个量级，但产额与带结合能修正的BEA计算值很接近

Template-assisted syntheses of two novel porous zirconium methylphosphonates

Two porous zirconium methylphosphonates (designated as ZMPmi and ZMPme respectively) were synthesized by using dibutyl methylphosphonate (DBMP) as a template. Two efficient post-synthetic treatments were developed to remove the incorporated template without destroying the hybrid structures. The materials were characterized by SEM, EPMA, TG, DTA, FTIR, and NMR. Specific surface area and porosity were evaluated by BET, alpha(s)-plots and DFT methods based on N-2 adsorption-desorption isotherms. The specific surface areas of ZMPmi and ZMPme are determined to be 279 and 403 m(2) g(-1) and the maxima of pore size distributions are at 0.7 and 1.3 nm respectively. (c) 2005 Elsevier Inc. All rights reserved.

Polymeric fullerene oxide films produced by decomposition of hexanitro[60]fullerene

A new poly(fullerene oxide) thin film material has been fabricated by thermal activation and electron bombardment on hexanitro[60]fullerene (HNF) film deposited on a An substrate, all under vacuum conditions. The reaction products in the polymerization process are analyzed by XPS, UPS, IR, TGA-MS and LDI-MS techniques. It is found that the main effect of thermal and radiation treatments is to induce cleavage of -NO bonds from HNF molecules resulted in the release of nitric oxide gas and the formation of fullerene-bound oxyradicals, C-60-C-6. Spectroscopic evidence strongly suggests that rearrangement of fullerenic nitro moieties into nitrito groups is involved in the HNF decomposition process prior to the generation of reactive oxyradical intermediates. Consequently, the intermolecular coupling reaction of these oxyradicals leads to carbon polymer networks containing oxygen-bridged fullerenes. The thermally generated polymeric thin film is stable up to 900 K. Electron bombardment is also effective in both the decomposition of -NO2 groups and the removal of -OH groups present in HNF films. UV irradiation at 365 nm alone is shown to be not as efficient for the polymer formation. (C) 2003 Elsevier Ltd. All rights reserved.

Characterization of metal-containing molecular sieves and their catalytic properties in the selective oxidation of cyclohexane

Three types of metal-containing molecular sieves with AFI, AEL and CHA structures (Me = Co, Mn, Cr and V) were synthesized hydrothermally and characterized by XRD, XRF, TG, TPR, NH3-TPD and FT-IR. It was revealed that metals were incorporated into the framework of molecular sieves and induced the presence of charge centers. Both cobalt and manganese in the framework of AIPO-5, AlPO-11 and SAPO-34 were not reducible before the structure collapse. The redox behaviours of these catalysts in cyclohexane oxidation at 403 K using O-2 as oxidant were examined. CoAPO-11 exhibited best activity and good selectivities for the monofunctional oxidation products (88.5%). Cyclohexanol was the major product over most catalysts, whereas for Cr-containing molecular sieves, high selectivity of cyclohexanone was observed. Investigation of reaction mechanism based on CoAPO-11 and CrAPO-5 catalysts indicated that the decomposition of cyclohexyl hydroperoxide (CHHP), the intermediate in cyclohexane oxidation, followed the pathway: cyclohexanone <-- CHHP --> cyclohexanol -->cyclohexanone. (C) 2004 Elsevier B.V. All rights reserved.

耕地土壤交换性钙镁比值的研究

对沈阳市郊区1994个耕地表土(0～20cm)样点和4个典型剖面中交换性Ca/Mg的比值进行了对比研究。结果表明:不同土属耕层土壤中Ca、Mg交换量有较大差别,交换性Ca/Mg的比值主要受母质等成土因素的影响;棕壤的各个土属的Ca/Mg在4左右,石灰性草甸土和草甸沼泽土的Ca/Mg则在8以上。棕壤和草甸土典型剖面不同层次中的Ca/Mg比值有着随深度加深而降低的趋势;由于Ca的植物返还率较Mg高,同一土壤类型中Ca/Mg比值的最大值出现在表土层,母质层中的Ca/Mg则相对稳定。对土壤Ca/Mg进行研究可以丰富土壤离子交换性能研究和土壤发生学特性研究的内容。

黄孢原毛平革菌合成木素过氧化物酶的营养调控

本文研究了营养条件对黄孢原毛平革茵(Phanerochale chrysosporium)ME-116合成木素过氧化物酶及其同工酶组分的影响.在最适培养条件下获得1500U/L的酶活.高效液相色谱分离的5个同工酶组分中以P_2组分含量最高.低碳高氮培养基最适于酶的合成.降低氮和KH_2PO_4含量致使各组分含量下降,而改变MgSO_4和CaCl_2浓度对P_2组分无影响.表面活性剂吐温80主要通过提高细胞膜透性而增加酶的合成.黎芦醇对5种同工酶组分的合成均有诱导作用.培养基中各营养因子对木素过氧化物酶的合成存在着复杂的交互作用.