无胺合成[Fe]ZSM-5分子筛的结构鉴定及其催化性能的研究

不用有机胺为模板剂,在碱性介质中采用水热合成法成功地合成了[Fe]ZSM-5分子筛.用X射线衍射、透射电镜、红外光谱、顺磁共振谱、X射线光电子能谱和穆斯堡尔谱等对其结构进行了表征,结果表明,Fe原子进入了分子筛骨架,并处于四面体的配位环境.在由甲醇转化为汽油的过程中,以本文合成的[Fe]ZSM-5与用有机胺为模板剂合成的[Fe]ZSM-5分子筛为催化剂相比,其活性和选择性几乎相同,且都比通常的H[Al]ZSM-5好,C₅组分以上的选择性大于80%,且芳烃(包括脂环烃)和异构烃的含量达75%以上.     

三元混配络合物形成的极谱研究——Cd-Bipy-Gly体系的稳定常数测定

用般谱法研究了Cd(Ⅱ)-2,2′-联吡啶(bipy)、Cd(Ⅱ)-甘氨酸(Gly)二元体系及cd(Ⅱ)-bipy-Gly三元体系的配合物的形成条件,用极谱法测定了不同浓庹配体的E_1/2(a)、E_1/2(c)、ΔE_1/2、(i_d)_s和(i_d)_c值,利用Lrden函数作图,外推求得各级稳定常数。     

Nonlinear Stability of Shock Profiles for Non-convex Model Equations with Degenerate Shock

This paper is concerned with the stability of shock profiles for one-dimensional non-convex equations of viscous materials. The main purpose is to show that the shock profile solution is stable in an appropriate weighted norm space for the case of the degenerate shock, provided that the shock is weak and the initial disturbance is small and of integral zero. The proof is given by means of an elementary but technical weighted energy method to the integrated system of the original one. Moreover, the stability result can be applied to the equation of van der Waals fluid and viscoelascity.     

用于负压下气体分析的气相色谱仪的研制

介绍一种可同时分析负压样品中常量Ｏ２,Ｎ２,ＣＯ和微量ＣＯ２的自制专用气相色谱仪。仪器在 负压下取样,经活塞升压后进样。在流程中样品气同时进入并列的色谱柱,再分别检测。常量组分使用热导池检测,微量组分使用氦离子化检测器检测。ＣＯ２的检测灵敏度为１０＾－６量级。实验表明,仪器结构简单,操作方便稳定性好,适合于负压气样的在线分析,负压气样中全组分的分析方法具有推广价值。     

不同反荷离子的Keggin结构钼磷酸盐的热稳定性及其对异丁醛催化氧化活性的影响

用共沉淀法制备了以Keggin结构为骨架的不同反荷离子钼磷酸盐,利用FTIR、XRD等手段进行了表征。结果表明,Li、Na、K、Cs分别作为反荷离子时的杂多酸盐的热稳定性依次增强,并考察了催化剂对异丁醛一步氧化制甲基丙烯酸的催化活性,其中Cs盐的催化活性最优。     

光化学烧孔及其在频域光存储中的应用

光化学光谱烧孔是近年来发展起来的一种高新技术,在超高密度光学存储中有着光明的应用前景。本文着重从材料科学的角度介绍了其基本原理、材料特性及其在频域光存储技术中应用的最新进展情况。     

Reversible pH‐Dependent Properties of Multilayer Microcapsules Made of Weak Polyelectrolytes

Summary: We investigated microcapsules composed of the weak polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) assembled on calcium carbonate cores. These capsules are stable in the pH range from 2.5 to 11.5, undergoing reversible swelling in the pH interval from 2.7 to 2.6. Capsule swelling occurs at a protonation degree above 90%. The pH‐dependent size variation of PAH/PMA capsules is blocked after crosslinking of the polyelectrolyte layers.

Schematic of the swelling and de‐swelling of the capsules with changing pH.     

Headspace Solid-Phase Microextraction/Gas Chromatography–Mass Spectrometry for the Determination of 2-Nonenal and Its Application to Body Odor Analysis

The odors and emanations released from the human body can provide important information about the health status of individuals and the presence or absence of diseases. Since these components often emanate from the body surface in very small quantities, a simple sampling and sensitive analytical method is required. In this study, we developed a non-invasive analytical method for the measurement of the body odor component 2-nonenal by headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry by selective ion monitoring. Using a StableFlex PDMS/DVB fiber, 2-nonenal was efficiently extracted and enriched by fiber exposition at 50 °C for 45 min and was separated within 10 min using a DB−1 capillary column. Body odor sample was easily collected by gauze wiping. The limit of detection of 2-nonenal collected in gauze was 22 pg (S/N = 3), and the linearity was obtained in the range of 1–50 ng with a correlation coefficient of 0.991. The method successfully analyzed 2-nonenal in skin emissions and secretions and was applied to the analysis of body odor changes in various lifestyles, including the use of cosmetics, food intake, cigarette smoking, and stress load.     

双生子佯谬的投影诠释

在表示洛伦兹变换的复平面上,考察各边平行于坐标轴的直角三角形,以其中各边比例关系为“投影关系”,用于简明地诠释双生子佯谬的实质,并得出某种程度的一般性结论     

The viscosity cross-section for elastic electron-xenon collisions including electron spin polarization

The results of the evaluation of the viscosity cross-section for elastic electron-xenon collisions, taking into account the spin-orbit interaction of the continuum electron, in the energy interval from 0.1 eV to 50 eV are presented and discussed. The calculations are performed on the basis of three theoretically derived sets of phase shift data obtained by different authors and on the deduced relativistic expression for the viscosity cross-section in terms of phase shifts discerning the spin-up and spin-down states of the scattered electrons. Comparison with viscosity cross-sections, as evaluated from non-relativistic phase shifts extracted from experiments, strongly favours the relativistic results. The assumption of isotropic scattering is critically examined and the error induced by its use is shown to persist to the same extent as in non-relativistic calculations, at least in the energy region considered. Received: 22 April 1998 / Received in final form: 16 December 1998