Synthesis and characterization of an Al(69)(3-) cluster with 51 naked Al atoms: analogies and differences to the previously characterized Al(77)(2-) cluster

A disproportionation process of a metastable AlCl solution with a simultaneous ligand exchange-Cl is substituted by N(SiMe(3))(2)-leads to a [Al(69)[N(SiMe(3))(2)](18)](3-) cluster compound that can be regarded as an intermediate on the way to bulk metal formation. The cluster was characterized by an X-ray crystal structural analysis. Regarding its structure and the packing within the crystal, this metalloid cluster with 4 times more Al atoms than ligands is compared to the [Al(77)N(SiMe(3))(2)](20)](2-) cluster that has been published four years ago. Although there is a similar packing density of the Al atoms in both clusters as well as in Al metal, the X-ray structural analysis shows significant differences in topology and distance proportions. The differences between these-at a first glance almost identical-Al clusters demonstrate that results of physical measuring, e.g., of nanostructured surfaces which carry supposedly identical cluster species, have to be interpreted with great caution.     

Photoelectron spectra of cyclopolysilanes

Summary He (I) PE spectra of cyclopentasilane and cyclohexasilane show excellent agreement with STO-3 G + ab initio calculations. The HOMO in both compounds is of (SiSi) 3 p character. First IP's appear at 9.4 and 9.6 eV respectively.

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Photoelektronenspektren von Cyclopolysilanen (Kurze Mitt.)

Zusammenfassung Die He (I) PE-Spektren der Cyclosilane Si₅H₁₀ und Si₆H₁₂ zeigen ausgezeichnete Übereinstimmung mit STO-3 G + ab initio Rechnungen. Beide Ringe besitzen HOMO's mit (SiSi) 3 p Charakter. Die ersten Ionisierungspotentiale liegen bei 9.4 bzw. 9.6 eV.

     

Conformational analysis 29: Preparation and1H and13C NMR,FTIR, MS,and crystallographic conformational and configurational study of 3-Oxo-1,3-oxathiane and its monomethyl derivatives

3-Oxo-1,3-oxathiane (1) and its monomethyl derivatives were prepared by oxidation of the corresponding 1,3-oxathianes. The structural analysis was carried out by¹H and¹³C NMR, FTIR, and mass spectrometry. At 298 K compound1 was a 1 1 (at 173 K a 3 1) mixture of the SO(ax) and SO(eq) chair forms. The major oxidation products of methyl 1,3-oxathianes attained exclusively the SO(ax), Me(eq) chair forms except that of the 5-methyl derivative, which consisted of 7% of the SO(eq), Me(ax) chair conformation in CDCl₃ solution. The minor products of oxidation existed in anancomeric SO(eq), Me(eq) chair conformations. The oxidation of 2-methyl- 1,3-oxathiane, however, led to 3,3-dioxo derivative (6) in addition to thetrans [SO(eq)] monoxide. The crystal structures of6 andtrans-3-oxo-5-methyl-1,3-oxathiane were solved by X-ray diffractometry.     

Eigenmobilities in background electrolytes for capillary zone electrophoresis: III. Linear theory of electromigration

A mathematical model of capillary zone electrophoresis (CZE) based on the conception of eigenmobilities, which are the eigenvalues of a matrix M tied to the linearized governing equations is presented. The model considers CZE systems, where constituents, either analytes or components of the background electrolyte (BGE), are weak electrolytes--acids, bases, or ampholytes. There is no restriction on the number of components nor on the valence of the constituents nor on pH of the BGE. An electrophoretic system with N constituents has N eigenmobilities. In most BGEs one or two eigenmobilities are very close to zero so their corresponding eigenzones move very slowly. However, there are BGEs where no eigenmobility is close to zero. The mathematical model further provides: the transfer ratio, the molar conductivity detection response, and the relative velocity slope. This allows the assessment of the indirect detection, conductivity detection and peak broadening (distortion) due to electromigration dispersion. Also, we present a spectral decomposition of the matrix M to matrices allowing the assessment of the amplitudes of system eigenpeaks (system peaks). Our model predicted the existence of BGEs having no stationary injection zone (or water zone, gap, peak, dip). A common practice of using the injection zone as a marker of the electroosmotic flow must fail in such electrolytes.     

Pfropfcopolymerisation von Cellulose mit zwei Vinylmonomeren

Zusammenfassung Die vorliegende Arbeit stellt eine Beschreibung von Experimenten dar, die die Erhöhung der Pfropfbereitschaft von trägen Komponenten durch Beimischung von aktiveren zum Ziele hatten.Das Trägermolekül war in allen Fällen Cellulose in Form von hochgradig gereinigtem Zellstoff. Durch die Verwendung von Mischsystemen aus Styrol und Methylmethacrylat gelang es, das trägere Styrol in bedeutend größerer Menge auf die Cellulose aufzupfropfen, als es bei Abwesenheit des aktiven Methylmethacrylats der Fall war.

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Grafting Polymerization of Cellulose with Two Vinyl Monomers

This paper describes experiments to increase the grafting of cellulose with components of poor reactivity by mixing them with highly reactive ones. A highly purified wood pulp was used as backbone. Using combinations of styrene and methyl methacrylate it was possible to graft considerably higher amounts of the poorly reacting styrene than in the absence of the highly reactive methyl methacrylate.

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Nach einem Vortrag, den der erstgenannte der Autoren im Rahmen der Arbeitstagung des Vereins Österreichischer Chemiker am 27. September 1968 in Wien gehalten hat.     

The characteristics of integrins expression in decidualized human endometrial stromal cell induced by 8-Br-cAMP in in vitro

Integrins are heterodimeric glycoproteins that have been found to undergo dynamic temporal and spatial changes in the endometrium during the menstrual cycle and in early pregnancy. Specificity of integrins is known to be different in human endometrial stromal cells and decidual cells. These shifts of integrins suggested to play an important role in embryo implantation and can be modulated by progesterone, cAMP derivatives, and cytokines. The mechanisms of decidualization and its precise physiological role are still not clearly understood and in vitro systems could provide an alternative that overcomes limitations of studying such complex biological phenomena in vivo at the time of implantation. This study was undertaken to establish an in vitro model system for human decidualization using 8-bromo-cAMP and to investigate the characteristics of stromal integrin expression in vitro by 8-Br-cAMP. Endometrial stromal cells were isolated and cultured, and then were induced to decidualize by 0.5 mM 8-Br-cAMP for 15 days. Immunofluorescence staining and flow cytometric analyses of the integrin subunits (alpha1, alpha4, alpha5, alpha6, beta1 and alphavbeta3) were performed at day 9. In the presence of 8-Br-cAMP, the staining intensity of alphavbeta3 was significantly higher than control and measurements for alpha1, alpha4, alpha5, alpha6, and beta1 were similar. Immunofluorescent localization of the integrins reflected the differences obtained from the flow cytometric analyses described above. In summary, the expression of alphavbeta3 integrin increased in stromal cells in vitro decidualized by 8-Br-cAMP and this up-regulation of alphavbeta3 integrin expression during decidualization might influence on human implantation.     

Data management in multi-method surface analysis

The solution of the problem of interchangeability of surface analytical data is gaining increasing importance in multi-method surface analysis. There are various surface analytical instruments in different laboratories on several automation levels. For these instruments, which are controlled by computer systems working with proprietary software under various operating systems, a standardised data format is necessary to allow an exchange of data. Therefore, a toolkit has been developed for the transfer, archiving and editing of surface analytical data in a standardised public domain format. This format contains all available and necessary information on experimental conditions and all parameters specific for a number of analytical techniques such as AES, SAM, XPS, SIMS, STM, AFM and EPMA. Additionally, all data concerning the conditions of sample-preparation and measurement history are included in order to allow a well-founded evaluation of the data and improved reproducibility of the experiment.