同步辐射白光全反射XRF在痕量元素检测的初步应用研究

叙述了同步辐射白光全反射Ｘ射线荧光分析的实验装置，给出了几种标准物质ＴＸＲＦ实验的检出限，并对实验结果进行了讨论。     

Synthesis and photoluminescence of single crystals europium ion-doped BaF2 cubic nanorods

In this work, we used the hydrothermal method to synthesize Eu³⁺ ion-doped cubic BaF₂ nanorods, which is a luminescent material. The clubbed structures were well crystallized and exhibited face-centred cubic structures, as indicated by powder X-ray diffraction, scanning electron microscopy, electron diffraction, and transmission electron microscopy. The luminescent properties were studied, and local symmetry surrounding Eu³⁺ ions and electronic transition processes included. The results indicated that Eu³⁺ occupied only one C_4ν site in nanorods.     

Phase and orientational ordering of low molecular weight rod molecules in a quenched liquid crystalline polymer matrix with mobile side chains

We study the phase diagram and orientational ordering of guest liquid crystalline (LC) rods immersed in a quenched host made of a liquid crystalline polymer (LCP) matrix with mobile side chains. The LCP matrix lies below the glass transition of the polymer backbone. The side chains are mobile and can align to the guest rod molecules in a plane normal to the local LCP chain contour. A field theoretic formulation for this system is proposed and the effects of the LCP matrix on LC ordering are determined numerically. We obtain simple analytical equations for the nematic/isotropic phase diagram boundaries. Our calculation show a nematic-nematic (N/N) first order transition from a guest stabilized to a guest-host stabilized region and the possibility of a reentrant transition from a guest stabilized nematic region to a host only stabilized regime separated by an isotropic phase. A detailed study of thermodynamic variables and interactions on orientational ordering and phases is carried out and the relevance of our predictions to experiments and computer simulations is presented.     

丙烯酸酯在胺存在下的氧化和聚合研究

胺促进丙烯酸酯氧化和聚合与胺及丙烯酸酯结构有关。芳香胺氮原子或苯环上有正性取代基时,促进作用大。带醚键的丙烯酸酯氧化和聚合快。 胺引发丙烯酸酯聚合认为先是胺促进丙烯酸酯氧化,生成单体过氧化物,与胺再形成复合物,分解产生自由基,促进更多丙烯酸酯氧化,继而引起聚合。     

Theoretical study on conformational conversion of 1,3-dioxane inside a capsular host

The conformational conversion of 1,3-dioxane guest encapsulated inside a cylindrical capsular host was investigated with PM3 method and single point energies were evaluated by B3LYP method. When entrapped in the capsule, the guest tumbles were slower than that in the free condition. The influences of the inner phase of the capsule on the guest conformational conversion were discussed in detail.     

Core/shell particles containing 3-(methacryloxypropyl)-trimethoxysilane in the shell: synthesis, characterization, and application

In comparison to the corresponding single-component counterparts, core/shell particles are widely used due to their better physical and chemical properties. The surface properties of core/shell particles evidently play an important role in the process of application. It is easy to deduce that surface properties mostly depend on the properties of the component in the shell. Therefore, desirable materials of shell are very significant for the study of composite materials, especially in core/shell field. It is well known that polysiloxane has excellent properties, such as the water repellency, high flexibility, low surface energy, and biocompatibility. Its application, however, is limited due to poor cohesiveness and poor film-forming properties. Recently, much endeavor has been made to overcome such flaws. It is found that polyacrylate is commonly considered for its good cohesiveness and excellent film-forming property. The combination of polysiloxane and polyacrylate has been shown to be important in the composite material field, especially as core/shell particles. Unfortunately, their hydrophobicity is considerably different and thus, the core/shell particles consisting of polyacrylate (PA)/polysiloxane (PSi) are hard to prepare by general seeded emulsion polymerization, and are also scarcely available in the literature. In this study, the new core/shell PA/PSi particles with poly(butyl methacrylate) (PA) as the core and poly(3-(methacryloxypropyl)-trimethoxysilane) (PSi) as the shell were prepared by dispersion polymerization under the kinetically controlled conditions. The characterization of the particles by TEM, DSC, particle size analyzer as well as static contact angle confirmed the formation of core/shell structure. The application of core/shell (PA/PSi) particles also has been considered and discussed here.TEM micrographs of core/shell (PA/PSi) particles.     

活性酚醛树脂中羟甲基含量的测定

本文提出一种酚醛树脂中羟甲基含量的化学分析法，分别以＾１３ＣＮＭＲ和化学分析法测定酚醛树脂的羟甲基含量。将两种测试结果与已知的投料量进行比较，证明所建立的化学分析法可行。     

钪—镧—对氟偶氮氯膦体系共显色效应的研究及应用

本文研究了钪－镧－对氟偶氮氯膦体系共显色效应的光度特性及测定钪的最佳条件，建立了光度法测定痕量钪的新方法。该法的表观摩尔吸光系数为８．５７×１０＾４Ｌ·ｍｏｌ＾－１·ｃｍ＾－１，Ｓｃ（Ⅲ）浓度在０．０－５．０μｇ／２５ｍｌ范围符合比尔定律。将本法用于镁基，铁基合成试样中痕量钪的测定，结果满意。     

Molecular and nanoscale materials and devices in electronics

Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules could serve as incomprehensibly tiny switch and wire one million times smaller than those on conventional silicon microchip. This has resulted very recently in the assembly and demonstration of tiny computer logic circuits built from such molecular scale devices. The purpose of this review is to provide a general introduction to molecular and nanoscale materials and devices in electronics.     

Theoretical study on intermolecular interactions in BrF/HnX adducts

Equilibrium geometries, interaction energies, and charge transfer for the intermolecular interactions between BrF and H_nX (HF, H₂O, and NH₃) were studied at the MP2/6-311++G(3d,3p) level. The halogen-bonded geometry and hydrogen-bonded geometry are observed in these interactions. The calculated interaction energies show that the halogen-bonded structures are more stable than the corresponding hydrogen-bonded structures. To study the nature of the intermolecular interactions, symmetry-adapted perturbation theory (SAPT) calculations were carried out and the results indicate that the halogen bonding interactions are dominantly inductive energy in nature, while electrostatic energy governs the hydrogen bonding interactions.