Effects of the Specific Area and the Thermal Stability of a Polymer on the Catalytic Activities of Polymer Immobilized Co-Pd Catalysts by SAMI

Co-Pd bimetallic catalysts immobilized with four kinds of resins with different specific areas were prepared by means of the solvated metal atom impregnation (SMAI) method. The results of the XRD and the magnetic measurement showed that as the specific area of the resin increased, the particle sizes of Co and Pd on the catalysts with the same metal content decreased, so the catalytic activity of the catalysts for the hydrogenation of diacetone alcohol as well as the reduction of oxygen on the fuel cell electrode increased. Below 140 , the conversion of diacetone alcohol increased as the reaction temperature increased, and above 140 , the conversion decreased because of the rupture of the resin.     

A Fluorescence Optical Fiber Sensor for Amrinon Using a New Oxazole Compound

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The Elastic Continuum Limit of the Tight Binding Model

The authors consider the simplest quantum mechanics model of solids,the tight binding model,and prove that in the continuum limit,the energy of tight binding model converges to that of the continuum elasticity model obtained using Cauchy-Born rule.The technique in this paper is based mainly on spectral perturbation theory for large matrices.     

非层状二维CdSe的制备及厚度对带隙的影响

二维半导体材料的天然带隙有望弥补石墨烯的零带隙缺陷，打破后者在场效应晶体管、开关器件、逻辑电路等领域的应用瓶颈.相较于层状半导体材料，非层状半导体材料多以较强的离子键/共价键结合，且各向同性，因此要获取其二维结构存在一定挑战.本论文通过化学气相沉积法实现了非层状Cd Se在云母衬底上的二维各向异性生长.详细表征了二维Cd Se的微观形貌、晶体结构和光学特性等.结果表明，样品具有显著的光致发光(PL)效应，说明厚度减薄至纳米级时不会破坏Cd Se的直接带隙属性.此外，随着厚度减小，样品的PL峰逐渐蓝移.为了进一步解释该现象，采用基于密度泛函理论的第一性原理计算方法，研究了不同厚度的Cd Se的能带结构，结果显示均为直接带隙，且随厚度减小，带隙值增大，与实验现象吻合.由此可知，通过生长参数调控二维Cd Se的厚度，即可实现对其带隙的有效调控，这对相关光电器件的性能提升具有指导意义.     

孔洞缺陷对二维石墨烯/氮化硼横向异质结热传导的调控

本文采用孔洞缺陷来实现对二维石墨烯/氮化硼横向异质结热导率的调控.平衡态分子动力学(EMD)计算结果表明，界面孔洞的引入会降低二维石墨烯/氮化硼横向异质结的热导率.相较于有序的孔洞分布，无序的孔洞分布能够更有效地降低异质结的热导率，这一现象可通过声子安德森局域化来解释.孔洞缺陷的存在导致声子的频率和波失发生变化，从而使声子散射变得更加频繁，孔洞随机分布时，则导致声子波在材料中发生多次反射和散射，最终形成局域振动模式.本研究揭示了孔洞缺陷降低二维石墨烯/氮化硼横向异质结热导率的物理机制，对二维热电材料的结构设计有一定的指导意义.