Etude par diffraction des rayons X des gels de polysavons derivant du copolymere alterne anhydride maleique-hexadecylvinylether

Low and wide angle X-ray diffraction was used to study the structural behaviour at low temperature of aqueous gels of an alternating copolymer of maleic anhydride with hexadecyl vinyl ether characterized at high temperatures by either a lamellar structure or a cylindrical structure. This study has shown the importance at low temperature of the crystallization of the paraffin chains. Only the lamellar structure can be observed. In this structure, both polymer skeletons and paraffin chains are assigned to be regularly arranged in space, the former at the interfaces, the latter inside the lamella.     

Die Kristallstruktur von RhHg2

Zusammenfassung RhHg₂ kristallisiert tetragonal mita=4,55₁ Å,c=2,99₈ Å,c/a=0.658₈ in der Raumgruppe P 4/mmm. Die Phase ist isotyp mit -PtHg₂.

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The structure of RhHg₂ was found to be tetragonal; the unit cell ofa=4,55₁ Å,c=2,99₈ Å,c/a=0,658₈ belongs to the space group P 4/mmm. RhHg₂ is isostructural with -PtHg₂.

     

Etude cristallographique de membranes obtenues a partir d'alcools polyvinyliques alcoyles

Low and wide angle X-ray diffraction was used to study the structure of paraffin grafted polyvinylalcohol membranes as a function of water content. The structure was found to be lamellar resulting in the pile-up of crystalline paraffin double layers, covered with polymer chains. Such an organization would be impossible if grafting of paraffin chains upon polyvinylalcohol were random. The membranes must be considered as two phase systems, consisting of amorphous and crystalline regions.     

Ex-vivo determination of blood glucose by microdialysis in combination with infrared attenuated total reflection spectroscopy

Several biosensors have been developed for continuous monitoring of human blood glucose, which is desirable for insulin-dependent diabetic patients. Developments in the field of quantitative assays using infrared attenuated total reflection spectroscopy allow the determination of metabolites at low concentrations. The microdialysis technique can provide a continuous sampling of extracellular body fluids. As only compounds of low molecular weight are passed on, infrared spectrometric quantitation is eased considerably. Samples were obtained by microdialysis of human blood plasma and aqueous glucose solutions. Multivariate calibration by partial least-squares was evaluated for its analytical performance in ex-vivo blood glucose monitoring. Mean squared prediction errors obtained by cross validation were 5.4 mg/dL for dialysate samples from different patients and 1.3 mg/ dL for dialysates from glucose solutions. Further investigations were carried out to achieve miniaturization of the measuring and detection device. Received: 5 December 1996 / Revised: 20 March 1997 / Accepted: 29 March 1997     

The effect of carbonaceous contamination on the investigation of the surface oxide on silicon by angle-resolved XPS

The carbon-contaminated native oxide layer on a standard silicon wafer was investigated by angle-resolved signal ratio X-ray photoelectron spectroscopy (AR/SR/XPS). The results, based on intensity measurements of C_1s , O_1s , Si _2p ⁴⁺ and Si^elemental _2p showed the carbon to be ingested into the oxide to a mean depth of 0.4 nm, and the oxide to consist of a fully oxidized layer ( 1 nm) on top, followed by a suboxidic layer (0.8 nm). The conclusions are that the depth location of the carbonaceous contamination is of cardinal importance for the correct interpretation of the oxidic data, and that for well studied systems routine measurements at two take-off angles suffice for quantitative results.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Über zwei Autoxidationsprodukte des Apomorphins

Zusammenfassung Wie bereits früher¹ mitgeteilt, lassen sich aus autoxidierten wäßrigen Lösungen von Apomorphin-Hydrochlorid zwei Oxidationsprodukte isolieren. Diese beiden Substazen (im folgenden als Substanz A und Substanz B bezeichnet) werden näher charakterisiert.Mit 2 Abbildungen     

The angle-resolved self-ratio technique for surface depth profile investigations by XFS,EMA, XPS and AES

The angle-resolved self-ratio (AR/SR) technique is a non-destructive, low-damage measuring technique in which the intensity I of an excited, analyte-characteristic radiation is measured as a function of the take-off angle from the surface plane for the purpose of obtaining quantitative depth information about the chosen analyte from the gradient dI/d. The depth information may be any of the following: the type of depth profile, the centroid depth of this profile, the thickness of a uniform overlayer, the stoichiometry of a uniform overlayer, the thickness of a uniform buried layer, and others. The AR/SR technique is one of a number of variants of the angle-resolved technique which is particularly suited for practical application because this mode combines an acceptable measuring effort with a simplicity and transparency of evaluation (by use of analytical formulae) not available with other procedures. The capabilities and limitations of the AR/SR technique in particular are reviewed, with special reference to four methods with which the technique has found application, viz. X-ray fluorescence spectrometry (XFS), electron microbeam analysis (EMA), X-ray photoelectron spectrometry (XPS) and Auger electron spectrometry (AES). Emphasis is placed on the role assigned to AR/SR/XFS and AR/SR/EMA in certification of ion-implanted reference materials.Invited lecture at 15th Colloquium on Materials Analysis, Wien, May 27–29, 1991