Mössbauer study of iron reduction in hematite containing mineral originated from Aswan area in Egypt

Mössbauer spectroscopy was used to study iron reduction in mineral originated from Aswan area in Egypt. The Mössbauer spectra of samples heat treated at 1000 °C in hydrogen atmosphere show a gradually reduction process of hematite. The main phase of sample aged for 1 h is magnetite, while alpha-iron as well as some silicates and wustite type oxide can be detected in sample aged for 3 h. Further aging of sample results in dissolution of alloying elements /Si, Al/, being present in the samples. This process starts already in samples aged at 1000 °C for 4 h, but it is more expressive in minerals heat treated at 1200 °C or 1300 °C, when all paramagnetic phases disappeared.     

A study of thin surface layers by multilayer Mössbauer spectroscopy /MMS/

A stacking Mössbauer technique, MMS has been applied for studying thin surface layers. The surface layers formed on the⁵⁷Fe film in aqueous solutions of corrosion inhibitors, such as zinc phosphate and barium metaborate, and in distilled water was studied by this method. It has been found that the corrosion is much slower in the presence of zinc phosphate and barium metaborate. XPS analysis suggests the formation of a mixed iron zinc phosphate on the surface of the⁵⁷Fe film after corrosion in a zinc phosphate solution.     

Reactions de photoaddition de benzo[b]selenophenes avec l'acetylene dicarboxylate de methyle et avec le dichloro-1,2 ethylene

Photoirradiated in presence of acetophenone, benzo[b]selenophene and its 3-methyl derivative add to dimethyl acetylenedicarboxylate. In each ease, the primary reaction product is unstable and has not been isolated. Photoexeited in its triplet state (the energy of which is in the neighbourhood of 69 $\text{kcal}\text{mole}$) benzo[b]selenophene and its 2- and 3-methyl, 2,3 dimethyl, 3 acetoxy and 2-methyl-3-acetoxy derivatives add to 1,2 dichloroethylene leading to cyclobutanes. Neither cyclo-addition occurs in absence of photosensitiser. Single-crystal X-ray analysis gave the structures of the two adducts of 3-acetoxybenzo[b]selenophene with trans-1,2-dichloroethylene. In both compounds the chlorine atoms are trans.     

Mechanism of the decomposition of cumenyl hydroperoxide under the influence of complexes of divalent copper with o-phenanthroline

Russian Chemical Bulletin -     

The investigation of critical parameters in the glycolytic response of single living cells by rapid microspectrofluorometric analysis

Summary NAD(P)H fluorescence emission spectra are recorded from single living cells, by a recently developed multichannel microspectrofluorometric technique, in correlation with the intracellular microelectrophoretic addition of substrate (i. e., glucose-6-P). These spectra may be used as a reference basis in establishing the critical parameters to be followed when the same studies are extended to a variety of cells, submitted to various drug effects or physical treatments. The sum-spectra corresponding to channel by channel (wavelength by wavelength) summation of spectra obtained from various cells within a series, before and after addition of substrate, and their difference spectrum may be normalized and evaluated comparatively. The NAD(P)H emission maximum prior to addition of substrate seems to present a mixture of dehydrogenase-bound and free coenzyme. There is a suggestion that immediately after substrate, i. e., at 5 sec, an increase in free NADH is first observed. While the overall changes in fluorescence intensity associated with substrate are quite large (50–150% increase), the counts (i. e., an expression of photons) associated with shifts in the emission maximum (free vs. bound NAD(P)H changes) are at times barely above noise. Rapid microspectrofluorometry provides in principle the most direct approach for the identification of coenzyme bound to various dehydrogenases in single living cells, but further improvements in spectral resolution and signal-to-noise ratio are required, for a better definition of the spectral shifts which may be observed.

---

Zusammenfassung Mit Hilfe einer kürzlich entwickelten Mehrkanal-Mikrospektrofluorometer-Methode wurden von einzelnen lebenden Zellen nach intrazellulär mikroelektrophoretischer Substratzugabe (z. B. Glucose-6-P) NAD(P)H Fluoreszenz-Emissionsspektren aufgenommen. Diese Spektren können als Vergleichsbasis bei der Festsetzung der entscheidenden Parameter verwendet werden, wenn die gleichen Untersuchungen auf eine Reihe von Zellen ausgedehnt werden sollen, die verschiedenen Medikamenteffekten oder physikalischer Behandlung ausgesetzt werden. Die Summenspektren, die der kanalmäßigen (wellenlängenmäßigen) Summierung der Spektren von verschiedenen Zellen innerhalb einer Serie, vor und nach Substratzugabe entsprechen, sowie ihre Differenzspektren können normalisiert und vergleichsweise ausgewertet werden. Das NAD(P)H-Emissionsmaximum vor der Substratzugabe scheint ein Gemisch von freiem und dehydrogenasegebundenem Coenzym darzustellen. Unmittelbar nach Substratzugabe (d. h. nach 5 sec) ist ein Anstieg an freiem NADH das erste Mal zu beobachten. Während die mit dem Substrat einhergehenden Gesamtveränderungen der Fluoreszenzintensität recht groß sind (50–150% Anstieg), sind die Impulse (als Effekt der Photonen), die mit einer Verschiebung im Emissionsmaximum verbunden sind (Veränderungen von freiem und gebundenem NAD(P)H) zu manchen Zeiten kaum höher als das Rauschen. Die rasche Mikrospektrofluorometrie stellt im Prinzip die direkteste Methode zur Identifizierung von Coenzymen dar, die an verschiedenen Dehydrogenasen in einzelnen lebenden Zellen gebunden sind. Weitere Verbesserungen der Spektralauflösung und der Empfindlichkeit (signal-to-noise ratio) sind notwendig, um die Spektralverschiebungen, die beobachtet werden, besser auswerten zu können.

     

Die quantitative Bestimmung von Vanadin mittels aktivierter Katalyse

Zusammenfassung Es wurden zwei Verfahren ausgearbeitet, um Vanadin mit Hilfe von aktivierter Katalyse zu bestimmen. Die Methodik ist geeignet, kleinste Spuren von Vanadin (bis herab zu 0,0006) mit ausreichender Genauigkeit zu ermitteln. Es werden Beleganalysen mitgeteilt.

---

Summary Two procedures for the determination of vanadium have been worked out, based on activated catalysis, which allow minimal traces (down to 0,0006) of vanadium to be determined with adequate accuracy. Comparison analyses are given in the paper.

---

Résumé On a élaboré deux procédés pour exécuter le dosage du vanadium à l'aide d'une catalyse activée. La méthode est apte à la détermination des plus petites traces de vanadium (jusqu'à 0,0006) avec une précision suffisante. On communique des analyses documentaires.

     

1,4 Addition to a perfluorinated cross-conjugated triene

Conclusions Perfluoro-(2-isobutenyl-1,1,4,4-tetramethyl-1,3-butadiene) yields 1,4 addition products both in nucleophilic addition and in radical chlorination.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1061–1064, May, 1979.     

Thermal degradation of copolymers of styrene and methyl-vinyl-silane by pyrolysis gas chromatography

Pyrolysis gas chromatographic investigations have been carried out on copolymers of styrene with trimethyl-vinyl-silane and of styrene with dimethyl-phenyl-vinyl-silane, in order to study the mechansims of thermal degradation and the copolymer structures. We have identified the pyrolysis products and measured their relative amounts. The experiments show that the controlling factor in the mechanism of the degradation is the nature of the side-group attached to the carbon atom at which chain scission occurs. If this side-group is phenyl, the main degradation process is depropagation; if it is if it is trimethyl-silyl or dimethyl-phenyl-silyl, intramolecular hydrogen abstraction followed by β scission becomes more important than depropagation. From the point of view of degradation mechanism, the nature of the side-group attached to the carbon atom from which the hydrogen is abstracted is of minor importance.We estimated the average copolymer block length from the amounts of products containing both comonomers as well as from the amounts of trimer composed of the same monomer.