Dynamical analysis of boundary behaviors of current-controlled DC–DC buck converter

Nonlinear Dynamics - In this paper, the current-controlled DC–DC buck converter from a new perspective are studied through the switching theory of flow, and the analytical conditions of the...     

化学法改性煤沥青脱除苯并芘的研究

在管式反应器中采用苯甲酸、聚乙二醇、固体古马隆树脂（S）、液体古马隆树脂（L）为添加剂来降低煤沥青中有害物质苯并芘的含量，以期使得煤沥青可绿色化应用。采用紫外-可见分光光度计分析煤沥青中苯并芘含量。考察了反应温度、反应时间、添加剂添加量、催化剂等工艺条件对添加剂脱除煤沥青中苯并芘的影响。结果表明，不同工艺条件能降低煤沥青中苯并芘的含量。在优化条件下，不同添加剂对苯并芘脱除率由高到低依次为：液体古马隆树脂、聚乙二醇、苯甲酸和固体古马隆树脂。分析其反应机理，这与催化剂的酸性相关，发生亲电取代反应。结果表明，液体古马隆树脂（L）在催化剂存在下对煤沥青中苯并芘脱除率可达73.0%，显示了良好的应用前景。     

Origins of Boosted Charge Storage on Heteroatom-Doped Carbons

Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons, none of the present studies has shown a whole landscape. Herein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in a broadened operating voltage, but also successfully promotes the specific capacitance in aqueous supercapacitors. In particular, the electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, a key step of water decomposition during the charging process, which broadens the voltage window of aqueous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore, the reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatom-doped carbon surface, thus yielding a boosted charge storage performance.     

Measurement of Residual Dipolar Couplings of Organic Molecules in Multiple Solvent Systems Using a Liquid-Crystalline-Based Medium

Residual dipolar coupling (RDC), a robust anisotropic NMR parameter for structural elucidation of organic molecules, is only accessible in an anisotropic environment. Herein, we introduce a novel alignment medium based on the molecular self-assembly of oligopeptide amphiphile (OPA). This medium is compatible with different intermediate and polar solvent systems, such as CD₃OD, [D₆]DMSO, and D₂O. The preparation of the OPA-based medium is simple and rapid, while only very weak background signals were observed from OPAs. Furthermore, we show that the purity of OPA has only a minor influence on the quality of the RDC data. These advantages allow RDC measurements of organic molecules with different polarities and solubilities with high efficiency and accuracy.     

HIRFL–CSR加速器中束流与真空中剩余气体的碰撞损失

研究了重离子加速器中束流与真空中剩余气体的碰撞损失过程和碰撞截面,在依据大量实验数据的基础上,提出了一组计算离子一原子的电荷交换截面的经验公式.以兰州重离子加速器HDRFL及冷却储存环CSR为例,给出了依据碰撞截面的公式计算束流在加速器真空中的传输效率的方法,并计算了在不同真空度下HIRFL的ECR源轴向注入束运线、注入器SFC、前束运线、主加速器SSC和后束运线等不同加速阶段及CSR的传输效率,并提出合理的真空度要求.HIRFL的真空分布测量和束流的损失测量证明了该计算方法的可靠性.     

胆绿素及其铜配合物的表面增强拉曼光谱研究

本文研究了胆绿素的表面增强拉曼光谱。结果表明，在溶液酸度不同时，拉曼光谱特征频率的变化表现出胆绿素的质子化。铜离子与胆绿素的相互作用实验结果说明金属铜离子可与胆绿素生成金属配合物。     

Yb3+掺杂KY(WO4)2激光晶体生长、结构与光谱分析

采用顶部籽晶提拉法(TSSG)生长出Yb:KY(WO₄)₂(Yb:KYW)激光晶体.对预烧后的原料及晶体进行了XRD分析，结果表明，分别在920℃和600℃预烧8h后的熔质和助熔剂基本上形成一相，抑止了实验中的挥发问题；所生长的晶体为β-Yb:KYW，计算其晶格常数为a=1.063nm，b=1.034nm，c=0.755nm，β=130.75°.测得不同厚度样品的吸收光谱，结果表明样品在933nm和981nm有较强的吸收峰，计算出主峰981nm的吸收截面σ关键词： Yb:KYW TSSG法 晶体结构 光谱参数     

CsNiCl3晶体的光谱精细结构、零场分裂参量及Jahn-Teller效应

应用不可约张量理论构造了三角对称晶场中3d²/3d⁸态离子的45阶可完全对角化的微扰哈密顿矩阵，研究了CsNiCl₃晶体的光谱精细结构、晶体结构、零场分裂参量、Jahn-Telller效应以及自旋单重态对Ni²⁺离子基态能级的影响，理论与实验相符合.在此基础上，进一步研究了以前工作中被忽略的自旋-自旋耦合作用和Trees修正对CsNiCl₃晶体的光谱精细结构和零场分裂参量的影响，发现有四种机理会影响零场分裂参量：1)自旋-轨道耦合机理，2)自旋-自旋耦合机理；3)自旋-轨道与自旋-自旋联合耦合机理；4)自旋-轨道与Trees修正联合耦合机理，其中自旋-轨道耦合机理是最主要的，其他三种机理也是不可忽略的. 关键词： 基态能级 精细结构 零场分裂 自旋-自旋耦合