金属离子/胆酸钠超分子水凝胶特殊温度响应性的机理研究

研究了胆酸钠溶液与金属离子溶液混合自组装而成的水凝胶随温度升高而机械强度增强的独特温度响应性. 利用透射电镜(TEM)和X射线衍射(XRD)仪表征了水凝胶中聚集体的微观形貌及分子排列方式. 考察了其流变学行为、荧光性质随温度的变化. 结果表明,升温促进凝胶形成的速率, 并提高凝胶的机械强度. 随着温度的升高, 稀土离子的荧光强度显著增强. 表面张力测量表明, 胆酸钠溶液的临界胶束浓度随温度的升高而略有降低. 综合实验事实, 我们提出随温度升高导致的凝胶强度增强行为是由胆酸钠分子在高温下聚集能力增强的结果.     

基于原子转移自由基聚合技术的偶氮苯星形液晶聚合物的合成与表征

利用原子转移自由基聚合(ATRP)技术合成了含不同端基取代基的偶氮苯三臂星形侧链液晶聚合物. 均苯三酚与2-溴异丁酰溴通过酯化反应制备三官能团引发剂, 引发偶氮苯单体6-[4-(4-甲氧基苯基偶氮)酚氧基]己基甲基丙烯酸酯(MMAzo)或6-[4-(4-乙氧基苯基偶氮)酚氧基]己基甲基丙烯酸酯(EMAzo)的ATRP反应. 利用核磁共振氢谱(¹H NMR)、凝胶色谱(GPC)、差示扫描量热法(DSC)和偏光显微镜(POM)等手段对星形聚合物进行表征. 星形聚合物的液晶性与相应均聚物相似, 但偶氮苯端基取代基的不同导致星形聚合物的液晶性差别显著. 在紫外/可见光照射下星形聚合物呈现明显的异构化转变.     

强流回旋加速器综合试验装置的磁场测量与垫补

强流回旋加速器综合试验装置的主体是一台紧凑型回旋加速器,加速器主磁铁材料的不均匀性,磁铁加工和安装的非理想因素将引起中心平面的磁场的非理想分布,因此有必要对其中心平面的磁场进行测量和垫补.本文主要讲述该综合试验装置的霍尔感应磁场测量系统的设计和使用;通过磁场测量数据分析进行镶条的再加工,最终实现对等时性磁场和束流的纵向聚焦的垫补;研究与实践了一种对磁场一次谐波进行垫补的方法,垫补的结果满足了设计的要求.     

二极管端面抽运固体激光器晶体棒与热沉接触热导研究

二极管端面抽运固体激光器中,圆棒晶体采用金属热沉夹持并散热,晶体侧面受到的压力呈非轴对称分布.建立了此状态下晶体棒与热沉间无热界面物质、采用厚度为平均间隙厚度和远大于平均间隙厚度的热界面物质三种情况下接触热导模型.针对前两种模型,采用截断高斯模型和塑性形变模型,讨论了接触热导与装配压力、等效均方根粗糙度的关系.建立了晶体棒与热沉的接触散热模型,对高斯型热耗分布,采用有限元法得到了无热界面物质和采用铟箔作为热界面物质时晶体棒温度的空间分布.结果表明:无热界面物质时,晶体棒与热沉间接触热导随圆心角变化较大,其 关键词： 激光二极管端面抽运固体激光器 热效应 有限元法 接触热导     

Mass spectrum and strong decays of strangeonium in a constituent quark model

In this work we calculate the mass spectrum of strangeonium up to the 3D multiplet within a nonrelativistic linear potential quark model.Furthermore,using the obtained wave functions,we also evaluate the strong decays of the strangeonium states with the ^3P_0 model.Based on our successful explanations of the well established states φ(1020) , φ(1680) , h_1(1415) , f'_2(1525) ,and φ_3(1850) ,we further discuss the possible assignments of strangeonium-like states from experiments by combining our theoretical results with observations.It is found that some resonances,such as f_2(2010) and f_2(2150) ,listed by the Particle Data Group,and X(2062) and X(2500) ,newly observed by BESIII,may be interpreted as strangeonium states.The possibility of φ(2170) as a candidate for φ(3S) or φ(2D) cannot be excluded.We expect our results to provide useful references for looking for the missing s\bar{s} states in future experiments.     

Random binary brush architecture enhances both ionic conductivity and mechanical strength at room temperature

The ionic conductivity and the mechanical strength are two key factors for the performance ofpoly(ethylene oxide) (PEO) based polyelectrolytes.However,crystallized PEO suppresses ion conductivity at low temperature and melted PEO has low mechanical strength at high temperature.Here,random binary brush copolymer composed of PEO-and polystyrene (PS)-based side chains is synthesized.PEO crystallinity is suppressed by the introduction of PS brushes.Doping with lithium trifluoromethanesulfonate (LiTf) induces microphase separation.Due to a random arrangement of the brushes,the microphase segregation is incomplete even at high salt loading,which provides both high ionic conductivity and high mechanical strength at room temperature.These results provide opportunities for the design of polymeric electrolytes to be used at room temperature.     

外围含对-硝基偶氮苯介晶基团的椭球型硅碳烷树状物

Novel carbosilane liquid crystalline dendrimers based on 1,6-hexanediol were prepared. Using the precursors Gn-C1 （n = 1-3） with Si-C1 bonds on the periphery as dendritic scaffolds and 4-[4-（6-hydroxyhexyloxy）phenylazo]- nitrobenzene as mesogenic group, a series of carbosilane liquid crystalline dendrimers from the first to the third generation were synthesized. These carbosilane liquid crystalline dendrimers showed smectic phase.     

Glueball spectrum from N_f=2 lattice QCD study on anisotropic lattices

The lowest-lying glueballs are investigated in lattice QCD using N_f = 2 clover Wilson fermions on anisotropic lattices. We simulate at two different and relatively heavy quark masses, corresponding to physical pion masses of mπ～938 MeV and 650 MeV. The quark mass dependence of the glueball masses has not been investigated in the present study. Only the gluonic operators built from Wilson loops are utilized in calculating the corresponding correlation functions. In the tensor channel, we obtain the ground state mass to be 2.363(39) GeV and 2.384(67)GeV at mπ～938 MeV and 650 MeV, respectively. In the pseudoscalar channel, when using the gluonic operator whose continuum limit has the form of ∈_ijkTrB_iD_jB_k, we obtain the ground state mass to be 2.573(55) GeV and 2.585(65) GeV at the two pion masses. These results are compatible with the corresponding results in the quenched approximation. In contrast, if we use the topological charge density as field operators for the pseudoscalar, the masses of the lowest state are much lighter(around 1 GeV) and compatible with the expected masses of the flavor singlet qq meson. This indicates that the operator ∈ijk TrBiDjBk and the topological charge density couple rather differently to the glueball states and qq mesons. The observation of the light flavor singlet pseudoscalar meson can be viewed as the manifestation of effects of dynamical quarks. In the scalar channel, the ground state masses extracted from the correlation functions of gluonic operators are determined to be around 1.4-1.5 GeV, which is close to the ground state masses from the correlation functions of the quark bilinear operators. In all cases, the mixing between glueballs and conventional mesons remains to be further clarified in the future.     

Diastereoselective cycloreductions and cycloadditions catalyzed by Co(dpm)(2)-silane (dpm = 2,2,6,6-tetramethylheptane-3,5-dionate): mechanism and partitioning of hydrometallative versus anion radical pathways

In the presence of phenylsilane and 5 mol % cobalt(II) bis(2,2,6,6-tetramethylheptane-3,5-dionate), aryl-substituted monoenone monoaldehydes and bis(enones) undergo reductive cyclization to afford syn-aldol and anti-Michael products, respectively. For both aldol and Michael cycloreductions, five- and six-membered ring formation occurs in good yield with high levels of diastereoselectivity. Cycloreduction of monoenone monoaldehyde 1a in the presence of d(3)-phenylsilane reveals incorporation of a single deuterium at the enone beta-position as an equimolar mixture of epimers, inferring rapid isomerization of the kinetically formed cobalt enolate prior to cyclization. The deuterated product was characterized by single-crystal neutron diffraction analysis. For bis(enone) substrates, modulation of the silane source enables partitioning of the competitive Michael cycloreduction and [2 + 2] cycloaddition manifolds. A study of para-substituted acetophenone-derived bis(enones) reveals that substrate electronic features also direct partitioning of cycloreduction and cycloaddition manifolds. Further mechanistic insight is obtained through examination of the effects of enone geometry on product stereochemistry and electrochemical studies involving cathodic reduction of bis(enone) substrates. The collective experiments reveal competitive enone reduction pathways. Enone hydrometalation produces metallo-enolates en route to aldol and Michael cycloreduction products, that is, products derived from coupling at the alpha-position of the enone. Electron-transfer-mediated enone reduction produces metallo-oxy-pi-allyls en route to [2 + 2] cycloadducts and, under Ni catalysis, homoaldol cycloreduction products, that is, products derived from coupling at the beta-position of the enone. The convergent outcome of the metal-catalyzed and electrochemically induced transformations suggests the proposed oxy-pi-allyl intermediates embody character consistent with the mesomeric metal-complexed anion radicals.     

退火温度对Cu:ZnO薄膜绿光发射的影响

利用溶胶-凝胶法在Si衬底上制备了不同退火温度的Cu:ZnO薄膜.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜和光致发光谱研究了样品的晶格结构、表面形貌、成分及其发光特性.结果表明:所有样品均具有高度的c轴择优取向,随着退火温度的升高,样品的结晶质量变好,样品的表面都被晶粒覆盖,强而稳定的绿光发射被观察到.绿光强度随退火温度的升高先增加后减小,发光中心位置不随退火温度的变化而改变,这样的绿光发射强而稳定.XRD和XPS结果表明,随退火温度的升高Cu2+还原为Cu+,导致Cu:ZnO薄膜形成的缺陷是VZn,所以绿光发射是由VZn引起的.Cu2+还原为Cu+时,Cu:ZnO薄膜中VZn浓度增加,使绿光发射强度增大.当退火温度超过800?C时,Cu2+的还原能力变差,绿光发射强度减弱.