Über einige neue Bispirane

We have obtained four new bispirane systems in which both spiroatoms are vicinal atoms in cyclopropane or cyclobutane rings and in which the heterocyclic component has the basic structure of 1,4-dioxep-2-ene. We have shown that from two possibilities (bispiran, propellan) the general reaction leads only to a bispiran system. To the bispiran2 exhibiting the highest hyperchromism we ascribed the bispirocoplanar conformation (Fig. 1).

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Mit 3 Abbildungen     

A modification of the heteropoly blue method for the microgram determination of arsenic in biological materials

Summary A sensitive method has been developed for analysis of trace amounts of arsenic in biological materials using the heteropoly blue method. The method employs a closed apparatus and a nitrogen atmosphere, and allows the detection of arsenic in ppm concentration using samples of 100 mg.

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Zusammenfassung Eine empfindliche Methode zur Bestimmung von Arsenspuren in biologischem Material im Wege der Molybdänblaumethode wurde ausgearbeitet. Man arbeitet dabei in einer geschlossenen Apparatur in Stickstoffatmosphäre und kann so in 100-mg-Proben Arsenkonzentrationen in der Größenordnung von ppm bestimmen.

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Presented at the 6th Annual Northeast Regional Meeting of the American Chemical Society, Burlington, Vermont, August 19, 1974.     

Die kathodische Sauerstoffreduktion an pyrolytisch abgeschiedenem Kohlenstoff in peroxidhältigen alkalischen Elektrolyten

The kinetics of the system O₂/HO₂ ^?, OH^? were studied at pyrolytic carbon in alkaline electrolytes. The rest potentials are close to the reversible values. They decrease by 30 mV when the HO₂ ^?-concentration is increased by a factor 10. CathodicTafel lines displayb-values between 70 and 95 mV. The exchange current densities are evaluated by extrapolation ofTafel lines to zero overvoltage and from the charge transfer resistance. Two different succeeding charge transfer reactions occur in course of the overall process, the first of which is the rate-determining step. A cathodic reaction order of zero is obtained with respect to HO₂ ^?. Theb values of anodicTafel lines are between 60 and 80 mV, the corresponding reaction order concerning the HO₂ ^? concentration is found to be +0.5. The kinetic studies prove the reversibility of the system O₂/HO₂ ^?, OH^? at carbon electrodes. The reaction mechanism is: $$\begin{array}{*{20}c} {O_2 + e^ - \rightleftarrows O_2 } \\ {O_{2^ - } + H_2 O \rightleftarrows HO_2 + OH - } \\ {HO_2 + e^ - \rightleftarrows HO_{2^ - } } \\ \end{array} $$ .     

Beitrag zum Stabilisierungsmechanismus des Wollkeratins durch einige Metalle

Zusammenfassung Das Verhalten des Wollkeratins ist im kochenden Wasser nach Behandlung mit Kupfer-, Kadmium-, Silber- und Quecksilbersalzen unnormal, nicht nur verglichen mit dem Verhalten des metallfreien Proteins, sondern auch gegenüber des unter gleichen Bedingungen mit anderen Metallen behandelten Keratins. Die beobachteten Phänomene werden in einigen Fällen entweder mit der Annahme der Bildung von Vernetzungen zwischen benachbarten Polypeptidketten durch Komplexbildung des Metalls mit einigen Gruppen des Keratins oder durch Blockieren des Cysteins und der Verhinderung des Disulfidaustausches erklärt. In anderen Fällen jedoch, besonders bei Silber, ist die Erklärung der eintretenden Veränderung mit Hilfe dieser zwei Mechanismen nicht möglich, und es wird die direkte Reaktion des Metalls mit dem Schwefel des Cystins vorgeschlagen. Hierbei wird das Cystin und damit die Disulfidbindung gespalten. Die Spaltung dieser Bindung und die Verhinderung ihrer Rückbildung, entweder in derselben oder in anderer Lage, senkt die Zahl der Quervernetzungen im Keratin herab und damit die Fixierung der Polypeptidketten in ihrer ursprünglichen Lage. Hieraus resultiert eine Schrumpfung der Ketten und die Kontraktion der Faser.

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Summary Wool fibres containing cadmium, copper, mercury or silver set in a different way than the untreated ones or the fibres which contain other metals. This behaviour is explained in some cases by assuming the formation of complexes between the metal and the protein or by the disulphide exchange mechanism. In other cases, however, and particularly with silver this is not possible, and therefore the direct reaction between the metal and the sulphur of cystine is proposed. According to this mechanism the contraction of the fibre is due to the breakdown of the disulphide bond and the inability of its reformation.

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Mit 10 Abbildungen und 2 Tabellen     

The Tolman length: is it positive or negative?

By means of a large-scale molecular dynamics simulation, we show that the Tolman length, although positive, is much smaller in magnitude than previously reported. We found that the range of interparticle interaction can significantly affect the magnitude of the Tolman length. When the range of interaction is longer than five molecular diameters, the Tolman length is on the order of a few hundredths of the molecular diameter, rather than a few tenths known previously.     

An approach to comparative analysis of chromatographic fingerprints for assuring the quality of botanical drugs

The present study was focused on developing the chemometric methods for analysis of the chromatographic fingerprint to control the quality of botanical drugs, which has gained attention in Asia and other countries. We developed a novel approach to generate a set of fingerprint features, called Fisher components (FCs) that were extracted from the chromatographic fingerprint. The method greatly reduces the dimensionality of the fingerprint vector, and the resulting FCs still retain most discriminatory information of the original fingerprint. Choosing an example of relevance to contemporary botanical drugs, we applied the FCs to a set of Shenmai injection samples. We successfully identified the manufacturers of the samples using two classifiers, linear discriminant analysis (LDA) and k-Nearest Neighbor (k-NN) based on the FCs. We also applied a similarity assessment together with the visual analysis using the FCs to exam the products from different manufacturers. We found that the lot-to-lot consistency of products can be accurately determined using the FCs. Finally, we demonstrated that the application of chemometric methods for chromatographic fingerprinting offers reliability to detect suspected fraud samples. In summary, we demonstrated that the presented approaches could be useful to determine the identity, consistency, and authenticity of Shenmai injection through chromatographic fingerprinting. The methods are equally applicable to other botanical drugs.     

Tast polarography of europium(III)-l-histidine complex

Study of europium(III)-l-histidine complex has been made in sodium perchlorate at μ=0.1 by tast polarography. The reduction process appears to be quasi irreversible. The apparent rate constants have been determined byGellings method¹. With the knowledge ofE ₁ ^2/r and use ofLingane's method, one complex Eu(Histd)²⁺ with the instability constant 6.77×10^?5 is reported.     

Kinetik der Diazotierung der Chloraniline in methanolischer Chlorwasserstofflösung

The kinetics of the diazotization of o-, m-, p-chloroaniline in 0.005n- to 0.4n-methanolic HCl-solution at 25, 15, 0, ?10 ?20, and ?30°C was invertigated. It was found that the nitrosation reaction (the same as in¹) $$C_6 H_4 ClNH_2 + NOCl \mathop \rightleftharpoons \limits^k C_6 H_4 ClNH_2 NO^ + + Cl^ - $$ is a proceeding advance-back-reaction. The decomposition of C₆H₄ClNH₂NO⁺ by splitting off a proton is the rate determining step. The free activation enthalpies ΔG ^* for the nitrosation reaction, the activation entropies ΔS ^*, the activation enthalpies ΔH ^* and the activation energiesE _a at the given temperatures are calculated. The experimentally found and the calculated velocities are given in Tables 1–6. The equilibrium constants of the o-, m-, p-chloroanilinium ions, and nitrosyl-chloride in methanol are indicated in Table 7, diagram 1. TheK _M values (the ionic products of methanol, extrapolated at infinite dilution) together with theK _A values of Table 7 give theK _B values (p. 2) using the table¹⁰. The ΔG _B values can be calculated using equation ΔG _B = ?RTlnK _B Fig 2 shows the linear dependance of the logarithmus of the ΔG ^* values from the logarithmus of theK _B values.     

Polarisabilites moléculaires et effet diélectrique de milieu à l'état liquide. Étude théorique de la molécule d'eau et de ses diméres

The model of Onsager in which a polar molecule undergoes a reaction field due to the polarization of the molecular surroundings is used to evaluate by a S.C.F. calculation (CNDO/2 approximation) the modifications of a molecular structure in the liquid state.Application to water molecule and to three polar dimers for values of the dielectric constant varying between 3 and 78, shows that most of geometric parameters and dipoles moments vary of few per cent when the molecule is inserted in a liquid. In the liquid state dipole moments do not depend very much on the dielectric constant but energies and relative stabilities of isomers are strongly dependent on the medium.[/p]