Photometrische Bestimmung von kleinen Mengen Chlorid in Selen, Tellur, Gallium und Wismut

Zusammenfassung Die Probe wird mit Salpetersäure in Gegenwart von Silbernitrat gelöst. Das entstandene Silberchlorid trennt man durch Zentrifugieren ab und zersetzt es anschließend mit Chromschwefelsäure in einer Bestimmungsapparatur. Dabei entstehende flüchtige Chlorverbindungen werden in einer schwefelsauren Kaliumpermanganatlösung zu Chlor oxydiert, das mit o-Tolidin ein gelbes Oxydationsprodukt bildet. Die Extinktion dieser Gelbfärbung wird photometrisch gemessen und die entsprechenden Chloridmengen an Eichgeraden ermittelt. 1–100 g Chlorid können bestimmt werden. Die Standardabweichung beträgt für den Bereich 1–10 ppm maximal ±0,6 ppm Cl und bei der Bestimmung von etwa 200 ppm maximal ± 2,8 ppm Cl.

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Photometric determination of small amounts of chloride in selenium, tellurium, gallium and bismuth

The sample is dissolved in nitric acid in presence of silver nitrate. The silver chloride is separated by centrifuge and decomposed in a glass equipment by chromosulphuric acid. Resulting volatile compounds of chlorine are oxidized by potassium permanganate in sulphuric acid solution to chlorine, which forms with o-tolidine a yellow oxidation product. The absorbance of this coloration is measured by photometry and corresponding amounts of chloride are found out by calibration curves. 1 to 100 g of chloride can be determined in the range of 1 to 10 ppm Cl with a standard deviation of ±0.6 ppm Cl and at approximately 200 ppm Cl with ± 2.8 ppm Cl.

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Wir danken Herrn Dr. G. Iwantscheff, Forschungslaboratorien der Siemens AG, für wertvolle Anregungen und Herrn Dr. v. Sturm, Forschungslaboratorien der Siemens AG, für die Überlassung von polarographisch ermittelten Chlorgehalten in Selenproben.     

INVESTIGATION INTO THE SPECTROSCOPY AND PHOTOISOMERIZATION OF A SERIES OF POLY (ETHYLENE GLYCOL) PEPTIDE SCHIFF BASES OF 11-cis RETINAL

Abstract— The 11-cis and all-trans isomers of a series of poly(ethylene glycol)-oligopeptide - Schiff bases as models for rhodopsin were synthesized and studied. Absorption data for certain of the PEG-peptide Schiff bases demonstrated that no intramolecular hydrogen-bonding (or protonation) occurs between the Schiff base and an acidic amino acid residue, as was previously thought. Photoisomerization of the 11-cis protonated and unprotonated Schiff bases were examined using both steady state and laser flash techniques. Also with 355 nm excitation (and additionally 532 nm in one case), an approximate 40% increase in quantum yield of isomerization (φ) occurred for all protonated PEG-peptide Schiff bases compared to the H⁺-n-butylamine counterparts (in methanol). In one case, a > 100% increase in φ was found in dichloromethane. These data show that PEG-oligopeptide Schiff bases are still further improved models for rhodopsin compared to their n-butylamine analogs.     

Über Mittelwerte multiplikativer zahlentheoretischer Funktionen mehrerer Variablen

In [8] the author extended the concept of neighbouring functions (cp. [9]) to the case of several variables. Using these results it is shown that under some weak conditions a multiplicative functionf in two variables has a mean-value different from zero if and only if the two multiplicative functionsf ₁(n)=f(n, 1) andf ₂(n)=f(1,n) have mean-values different from zero. Applications to theorems ofDelange [3],Elliott [6] andDaboussi [1] are given.     

Nonequilibrium fluctuations in μ space

The properties of fluctuations in space in or outside thermal equilibrium are obtained by solving hierarchies of equations derived either from the Liouville or the Master equation. In particular we study the one-, two-, etc., time correlation functions that describe the spatial and temporal behavior of the fluctuations in space. Explicit solutions are obtained for a dilute gas. The Langevin approach is briefly discussed. Our results are compared with those obtained in the extensive literature, which is reviewed in some detail.     

An invariance principle for lattices of dependent random variables

Summary It is shown that for -mixing arrays of Banach space valued random vectors the central limit theorem implies the invariance principle. Applying this result to lattices of random variables a higher dimensional invariance principle under dependence assumptions is obtained.Dedicated to Professor Leopold Schmetterer     

Die Verfeinerung der Kristallstruktur eines metamorphen Orthopyroxens

The atomic coordinates, the isotropic temperature factors and the site-occupancy factors of a metamorphic orthopyroxene Mg_1,56Fe_0,39Ca_0,05Si₂O₆ have been refined by the least-squares method using 1373 crystallographically independent reflections. Three-dimensional intensity data have been determined by integrated Weissenberg photographs. The final residual is 0.11. The site-occupancy factors M 1 = Mg_0,968 + Fe_0,032 and M 2 = Mg_0,589 + Fe_0,361 + Ca_0,050 reflect a high degree of order in the intracrystalline Mg, Fe distribution. The M 1, M 2 octahedra, the Si tetrahedra and the dependence of the means interatomic distances M  O on the Mg. Fe site occupancy are the subject of discussions.     

Die Anwendung des Quantimet zur Ätzgrubendichtebestimmung an Silizium-Einkristallen

A quantitative estimation of the structure of etched silicon crystals is possible with the microscope Quantimet by a fast counting the number of particles, i.e. etch pits on {111}-planes. Boundary conditions of the measuring technique are the requisite size of the etch pits of from > 3 … 5 μm, a plane specimen surface, the correct optical magnification, threshold and acceptance width. Sources of errors due to the structure result from the overlap of etch pits at dislocation densities > 10⁴ cm⁻² which leads to an underestimation of the number of etch pits because of the reduced signal output. An overestimation is most caused by an unwished contrast in the surface which yields additional signal outputs. The errors will be eliminated by using a calibration curved. Due to the short time which is necessary for counting, the Quantimet is well suitable for routine testings and for quantitative evaluation of the structure defects (etch pit density) in silicon, including consideration of possible errors.