Dielectric properties of beryllia ceramics in the near-millimeter wavelength range

We report the refractive indices and absorption coefficients for four beryllia (BeO) ceramic samples. These dielectric properties have been measured over the range from 4 to 18 cm^–1 by use of a Michelson interferometer. The index n, follows the linear relationship n=0.6517 cm³/g×+0.7130 with density, , over the range 2.8<<3.0 g/cm³.     

Multifold curdlan gel formation by dialysis into aqueous solutions of metal salts

We have found that the dialysis of curdlan dissolved in alkaline solution into aqueous solutions of metal salts yielded multifold gel structures. Aqueous sodium chloride and potassium chloride as well as pure water induced isotropic gels. Aqueous calcium salts induced liquid crystalline gel with refractive index gradient/amorphous gel alternative structure. Aqueous salts of trivalent aluminum and ferric cations induced a rigid liquid crystalline gel, which shrank above a threshold concentration of each salt. On the other hand, Liesegang ring-like pattern was observed with aqueous solutions of mixed salts of calcium chloride and magnesium chloride. The patterns have been classified to discuss the mechanism of forming the variety of structures.     

分子拓扑指数在晶格能中的应用

分子拓扑指数在晶格能中的应用凌天才（重庆师范学院化学系重庆６３００４７）关键词拓扑指数，晶格能分子拓扑指数实际上是分子图的不变量。自ｗｉｅｎｅｒ￣［１］于１９４７年首次提出ｗｉｅｎｅｒ指数并用以关联烃类的沸点等数据以来，分子拓扑指数广泛用于关联与预测...     

Effect of the modification of silica on thermal properties and flammability of cross-linked butadiene-acrylonitrile rubbers

The paper presents the results of testing the thermal stability and flammability of butadiene-acrylonitrile rubber vulcanizates with different contents of combined acrylonitrile: Perbunan NT 1845 and Perbunan NT 3945 from Bayer, containing unmodified and bromine- or iodine-modified silica. The test results were obtained with the use of a derivatograph, measurements of flammability by the method of oxygen index, in air and also with the use of a cone calorimeter. The effect of the modification on the zeta potential was also examined. A considerable reduction in the flammability of nitrile rubber vulcanizates filled with silica can be obtained by the modification of filler with bromine or iodine. All the vulcanizates containing modified silica are self-extinguishing. An appropriate filling of NBR 39 vulcanizates with bromine-modified silica makes it possible to obtain non-flammable polymeric materials. They neither ignite nor glow under the action of a flame source for 30 s. The findings can be a rational basis for the synthesis of modified silica that can act as active filler and effective flame-retardant agent at the same time.     

Cumulative indices for Spectrochima Acta, Part A and Spectrochimica Acta, Part B

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), a section of Spectrochimica Acta, Part B (SAB). The hardcopy text is accompanied by an electronic archive, stored on the SAE homepage at http://www.elsevier.nl/locate/sabe. The archive contains data, index and program files. The main article discusses the bibliographical purpose of the program and data files. A collective index for Spectrochimica Acta for volumes since it was split into Parts A and B, and continuing through 1991 for SAA and 1997 for SAB, is presented in DBF format, along with rudimentary data entry and access software.     

诱导效应指数与脂肪族胺、醇和醚的气相碱性

用烷基诱导效应指数I和RX分子中质子亲合原子X所带电荷qx及元素电负性XN与 脂肪胺，醇、醚的气相质子亲合PA进行关联，结果表明，脂肪胺，醇、醚的气相碱 性可以用下式定量描述：PA(kJ.mol^-1)-2732.0333-2457.1510∑I-1492.2351qx- 732.6277XN利用上式对64种化合物的气相碱性进行预测，平均相对误差为0．34％ ，预测值和实验值的偏差均在实验误差范围内。     

Dicholorbenzyl alkyl ether homologs as retention index markers and internal standards for the analysis of environmental samples using capillary gas chromatography

A homologous series of 2,4-dichlorobenzyl alkyl ethers (DCBEs) have been synthesized and purified for use as retention index calibrants and internal standards. They are stable, sensitive to ECD and FID and ideal for GC-MS, with base peaks at m/z 159/161. The retention index calibration against the n-alkanes for a linear temperature program (LTP) series is given and recommendations made for the most suitable members of the DCBE series for use as internal standards in organochlorine (OC) residue analysis.     

固固相反应合成牛磺酸水杨醛钾与锑、铋的配合物

合成了牛磺酸水杨醛钾,并采用室温固固相反应法合成了牛磺酸水杨醛钾与三氯化锑和三氯化铋的配合物,其组成为:K2MC18H20O8N2S2 (M = Sb, Bi)。两种配合物的晶体结构均属于单斜晶系,锑配合物的晶胞参数为:a = 1.2869 nm, b = 1.7636 nm, c = 1.9917 nm, β= 93.79埃活榕浜衔锏木О问篴 = 1.4770 nm, b = 2.0334 nm, c = 2.0149 nm, β= 94.05。红外光谱表明N、Cl原子参与了配位,中心离子的配位数为5。     

Reproducibility of retention indices measurement of alkylbenzenes on crosslinked methyl silicone phase fused silica capillaries

Summary Reproducibility of the Kovats retention indices of alkylbenzenes was studied on conventional “PONA” fused-silica capillary columns coated with crosslinked dimethyl silicone phase, with a film thickness of 0.5 μm. The data were compared with those obtained on conventional OV-101 columns. The tested PONA columns showed reproducible chromatographic properties, capacity ratios and high efficiencies. Having a standard deviation of s=0.03 i.u. of the retention indices on a single column, the column-to-columns differences were found to be up to 0.3 i.u. Higher indices were determined for crosslinked columns, the difference being in most cases about one i.u.     

Estimation of stability constants of copper(II) chelates with triamines and their mixed complexes with amino acids by using topological indices and the overlapping spheres method

Our two original approaches, the first based on the topological (connectivity) index ³χ^v and the second based on the model of overlapping spheres (OS), were applied for the estimation of stability constants of copper(II) complexes (CuL) with ethylenediamines (N = 14) and diethylenetriamines (N = 8), and mixed complexes (CuLA) of amino acids and diethylenetriamines (N = 18). The stability constants of the ethylenediamine complexes were predicted “indirectly” from calibration models developed on diethylenetriamines and vice versa, and also by a more direct method using the leave-one-out procedure of cross validation (cv). By averaging all the estimates, stability constants were reproduced with a rms error of 0.56 and 0.43 log K units for diethylenetriamines and ethylenediamines, respectively.