钙型沸石对生活污水中氨氮去除的研究

通过静态方法研究了钙型沸石对氨氮的去除效果．氨氮在钙型沸石上的吸附是吸热过程，饱和吸附容量是46．29mg／g．经过10次吸附-解析-再吸附循环过程，从吸附容量的数据可知盐酸和氯化钠可以获得很好的再生效果，吸附容量的标准偏差分别为6．34％和6．59％．对生活污水中氨氮的去除效果表明，在废水处理过程中钙型沸石将是一种实用和廉价的氨氮吸附剂。     

Synthesis of single-crystalline perovskite nanorods composed of barium titanate and strontium titanate

We report the solution-based synthesis of single-crystalline nanorods composed of barium titanate (BaTiO3) and strontium titanate (SrTiO3), which yields well-isolated nanorods with diameters ranging from 5 to 60 nm and lengths reaching up to >10 mum. Electron microscopy and diffraction measurements show that these nanorods are composed of single-crystalline cubic perovskite BaTiO3 and SrTiO3 with a principal axis of the unit cell preferentially aligned along the wire length. These BaTiO3 and SrTiO3 nanorods should provide promising materials for fundamental investigations on nanoscale ferroelectricity, piezoelectricity, and paraelectricity.     

A local property ofL-regular sets

A compact subsetK of the unit ball in ? ⁿ is said to beL-regular if the extremal function $$h_K (z) = \sup \{ f(z):f \in PSH,f< 0f \leqslant - 1 on K\} $$ is continuous. With a method from an earlier paper we prove thatL-regularity is essentially a local property of the setK. As a corollary we note that, in the special case when ? ⁿ ,L-regularity is nothing but a local property ofK.     

Long wavelength operation of a CW CO-laser up to 8.18 μm

A liquid nitrogen cooled cw CO-Laser is described, with which laser action up to 8.18 m (v=3635) has been achieved.On leave from: Dalian Institute of Technology, Dalian, People's Republic of China.     

Synthesis of trans-7-hydroxymethyl-2-(2-benz[d]isoxazol-3-yl)octahydro-2H-pyrido[1,2-a]pyrazine

An efficient synthesis of trans-7-hydroxymethyl-2-(2-benz[d]isoxazol-3-yl)octahydro-2H-pyrido[1,2-a]-pyrazine 2 is presented which relies on the equilibration of cis-dimethyl piperidinedicarboxylate followed by alkylation with phthalimidoethyl triflate.     

The reaction Ne+H 2 + (v=0, 1, 2, 3, 4)→NeH++H: 3D potential energy surface and quasiclassical trajectory calculations

A three-dimensional potential energy surface for the endoergic reaction Ne+H ₂ ⁺ →NeH⁺+H in the² A′ ground state of the system NeH ₂ ⁺ has been calculated by quantum chemical ab initio methods (CEPA approximation). The calculated points on this surface were fitted to an analytic ansatz in terms of an extended LEPS functional form augmented by a correction function. The latter was expanded in polynomials in inverse powers of the internuclear distances. This analytic form was used for quasiclassical trajectory calculations of reactive cross sections. In agreement with experimental investigations a strong vibrational enhancement is observed, i.e. the reaction is markedly favored if the necessary reaction energy is supplied as vibrational energy of H ₂ ⁺ rather than as relative translational energy. Other properties of the reaction dynamics such as the backward to forward scattering ratio, the lifetime of the collision complex NeH ₂ ⁺ , and final rotational and vibrational state distributions are also discussed on the basis of the quasiclassical trajectory calculations.     

Structures and defects of Au particles (1–3 nm) by HREM

Gold particles produced by the inert gas aggregation technique were observed in HREM. Among the smallest ones (1–3 nm), four structures were recognized: decahedra, icosahedra, cuboctahedra and body-centered tetragonal or orthorhombic structures. The observation of the latter structure for Au clusters is reported for the first time. By improved image processing, their morphologies and defects were precisely determined. Most of them contained small distortions compared to the ideal structures.     

Influence of laminar flow on preorientation of coal tar pitch structural units: Raman microspectroscopic study

In order to estimate the role of laminar flow of viscous, aromatic matter of carbonaceous precursor on microtextural preorientation in pregraphitization stage, we performed experiments with coal tar pitch (CTP). The principal hypothesis of preorientation of basic structural units (BSUs) in the case of laminar flow (pressure impregnation of CTP into porous matrix) and secondary release of volatiles during carbonization were studied. Glass microplates, planar porous medium with average distance between single microplates 5 microm were used as suitable porous matrix. Samples of CTP were carbonized up to 2500 degrees C. Optical microscopy reveals large flow domains in the sample of cokes carbonized between glass microplates. Raman microspectroscopy and high resolution transmission electron microscopy (HRTEM) show that at nanometric scale, the samples do not support the proposed hypotheses. With increasing temperature of pyrolysis, the graphitization of CTP impregnated into porous matrix proceeds to lower degree of structural ordering in comparison with single pyrolyzed CTP. This is explained by the release of volatile matter during carbonization in geometrically restricted spaces. More evident structural changes were discovered with the sample of single coke, where parts of fine grain mosaics, relicts of 'so called QI parts', reveal higher structural organization, in comparison with large and prolonged flow domains, similar to flow domains of cokes from microplates.     

Stability of Colloidal Silica Modified by Macromolecular Polyacrylic Acid (PAA) – Application of Turbidymetry Method

The effect of anionic polyacrlic acid (PAA) adsorption on fumed silica (SiO₂) surface on suspension stability was studied. The turbidymetry method was applied to monitor the changes in the suspension stability (using apparatus Turbiscan Lab^Expert with cooling module TLAb Cooler). PAA macromolecules contain dissociable carboxyl groups, therefore, all measurements were carried out at three pH values: 3, 6 and 9. Analysis of obtained transmission and backscattering curves and Turbiscan Stability Indexes (TSI) allowed determination of the most probable mechanism of the stability of the studied systems. The PAA adsorption has the greatest impact on the silica suspension stability at pH 3 (significant improvement of its stability). On the other hand, the presence of polyacrylic acid at pH 6 causes a noticeable deterioration of system stability conditions. At pH 9, polymer minimally influences the stability of SiO₂ suspension.