On the diffusion field in the neighborhood of two identical spheres

Summary Under steady state conditions the reduction in the diffusive flux into a sphere due the presence of a neighboring, identical sphere is calculated. Taking the flux into a sphere as 1 when the particles are at infinite separation, the flux decreases to a minimum value of 0.693 when the spheres are touching.

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Zusammenfassung Unter stationären Bedingungen wird die Abnahme des Diffusionsflusses in eine Kugel, bedingt durch eine benachbarte identische Kugel, berechnet.Wird der Diffusionsfluß in eine Kugel gleich 1 gesetzt, wenn die Partikel unendlich weit voneinander entfernt sind, so nimmt der Diffusionsfluß auf einen Minimalwert von 0,693 ab, wenn sich die Kugeln berühren.

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With 2 figures     

Synthesis in the 2-mercaptobenzothiazole series

The reduction of some dihydrothiazolobenzothiazolium salts with sodium borohydride may take place in two directions: with the formation of thiazolidino[2, 3-b]benzathiazolines and with the cleavage of the C-S bond to give N-(-mercaptoethyl)benzothiazolines. The behavior of thiazolidino[2, 3-b]benzothiazoline under the conditions of acid and alkaline hydrolysis has been studied.For communication VI, see [1].     

2.6 Foods

Abstracts2 Particular products and fields of application

2.6 Foods     

Umsetzung von hydrobromiertem 1,4-Polybutadien mit lithiumorganischen Verbindungen

Ohne ZusammenfassungMit 1 Abbildung und 1 Tabelle     

THE PHOTOSENSITIZED OXIDATION OF SULPHIDES

Abstract— The rates of photosensitized oxidation of a number of sulphides were determined under standard conditions in 1, 1, 2,2-tetrachloroethane and in methanol. It was found that the ratio of the rates of reaction in the two solvents was not constant for different sulphides and that t -butyl sulphide does not react in methanol. It is inferred that the presence of an H atom in the α position is essential for reaction in polar solvents and an appropriate mechanism is suggested. The results indicate that reaction in chlorinated solvents may take place by a different mechanism which possibly involves H-abstraction by triplet sensitizer.     

Spin-spin coupling of77Se and31P nuclei in cyclic organophosphorous compounds

We have established that direct phosphorus-selenium spin-spin coupling constants in cyclic compounds with P=Se exocyclic and P-C endocyclic bonds are found in the range¹J_PSe=–708 to –859 Hz; in this case, it is greater for the axial orientation of P=Se than for the equatorial orientation.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 776–780, April, 1990.     

Oxygen uptake photosensitized by disorganized chlorophyll in model systems and thylakoids of greening barley

Light-dependent oxygen uptake was observed and studied in thylakoids from early greening barley in comparison to oxygen uptake in chlorophyll solutions and in thylakoids from fully green leaves. Substantial oxygen uptake was observed in chlorophyll solutions supplemented with tryptophan, histidine, ascorbic acid or linoleic acid. This uptake was diminished by adding azide, beta-carotene and alpha-tocopherol, which are specific singlet-oxygen quenchers. Illuminated thylakoids from greening barley also exhibited marked oxygen uptake that, likewise, was strongly quenched by azide. In comparison, azide was found not to affect oxygen uptake that is associated with the methyl viologen-catalyzed Mehler reaction. It is reasoned that in the first two cases the oxygen uptake arises from chlorophyll-photosensitized activation of oxygen to the singlet state and its consumption by exogenous or endogenous substrates. In greening, we propose that disorganized chlorophyll photo-sensitizes the oxygen uptake.     

Investigation of N-nitrohydrazines by the NMR method

Functionally substituted N-nitrohydrazines were studied by heteronuclear NMR. It was shown that all the investigated products from nitration of the trimethylsilyl derivatives of functionally substituted hydrazines contain the N-NO₂ fragment. The chemical shift of the nitrogen atoms of the hydrazine fragment in the¹⁵N NMR spectra and the spin-spin coupling constants were used as the main tests for structural identification. It was established that the number of recordable conformers decreases in the transition from the trimethylsilyl phenylhydrazine derivatives to the nitrohydrazines as a result of the conformational flexibility of the N(NO₂)CO fragment.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2024–2031, September, 1991.     

Determination of traces of palladium using radioactive zinc dithizonate as a reagent

A radioreagent method for the analysis of traces of palladium using radioactive zinc dithizonate as the reagent has been developed. The method is rapid, highly selective and palladium concentration down to 2 g present in 10 ml solution can be measured.