Ultrasonic measurements and other allied parameters of praseodymium and neodymium palmitates in mixed organic solvents

Ultrasonic measurements on praseodymium and neodymium palmitates were made in a mixture of 60% benzene and 40% dimethyl sulfoxide (V/V), to determine the critical micelle concentration (CMC), soap-solvent interaction, and various acoustic and thermodynamic parameters. The values of the CMC increase with the increase in the size of the cation in the soap molecules. The ultrasonic velocity, specific acoustic impedance, apparent molar compressibility, apparent molar volume and relative association increase while the adiabatic compressibility, intermolecular free length, solvation number, molar sound velocity and available volume decrease with increasing soap concentration.     

Studies in bivalent chromium salts

Summary It has been shown in these investigations that the titrations of methylene blue, indigo, crystal violet, eosin, malachite green, magenta and orange G can be carried out successfully with chromous sulphate solution. Comparative results with titanous chloride and chromous sulphate indicate a fair degree of agreement. However, the reduction is found to be more facile with chromous sulphate.Part I: See Z. analyt. Chem. 158, 20 (1957).The authors' thanks are due to Dr. R. N. Singh, Professor of Chemistry, B. R. College, Agra, for providing laboratory facility and encouragement.     

Bestimmung der Hydratation eines Proteins durch Lichtstreuung

Zusammenfassung Aus der Theorie der Lichtstreuung für Mehrkomponentensysteme nachZernike lassen sich Beziehungen ableiten, in welchen die durch gelöste Substanzen hervorgerufene Änderung der Zusammensetzung eines Lösungsmittelgemischs durch Größen ausgedrückt wird, die durch Messungen der Streulichtintensität, des Brechungsindex und des Brechungsinkrements erhalten werden können. Zur Bestimmung der Solvatation von Proteinen in wäßriger Lösung mußte in einem System aus 4 Komponenten (Protein, Wasser, Puffer, organ. Lösungsmittel) gearbeitet werden, doch konnte es durch Extrapolation der Werte einer Komponente (Puffer) auf Null zu einem 3-Komponenten-System reduziert werden.Auf diese Weise wurde von 2 untersuchten Lösungsmittelgemischen (Wasser-Glycerin und Wasser-Chloräthanol) die Änderung des Wassergehalts bei Zugabe von 1 g Rinderserumalbumin ermittelt. Da diese Änderung nur scheinbar der Solvatation des Proteins entspricht, mußte die wahre Solvatation durch eine Umrechnung, die der Theorie scheinbarer Adsorption analog ist, gewonnen werden.Das Gewicht der Hydrathülle des Rinderserumalbumins in wäßriger Lösung ergab sich sowohl im Glycerin als auch im Chloräthanol-Wasser-System zu 0,38 g Wasser/g Protein.Außerdem wurde die Zusammensetzung der Solvathülle in Abhängigkeit vom Glycerin- bzw. Chloräthanolgehalt ermittelt und gefunden, daß bei letzterem zwischen 40 und 50 Vol.-% ein Umschlag von einer reinen Wasserhülle in eine reine Chloräthanolhülle auftritt.     

Studies on molar volume and rheology of terbium soaps in a benzene-DMF mixture

Summary Molar volume (V), apparent molar volume (_v), and fluidity () of terbium soaps in benzene-DMF (7:3 v/v) were evaluated at constant temperature from density and viscosity measurements. The results were used to determine the critical micelle concentration (CMC), soap-solvent and soap-soap interactions, and the effect of the chain length of soap molecules on various parameters. The molar volume and viscosity results are discussed in terms of known relations.

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Untersuchungen zum Molvolumen und zur Rheologie von Terbiumseifen in Benzol-DMF

Zusammenfassung Molvolumen (V), scheinbares Molvolumen (_v) und Fluidität () von Terbiumseifen in einer Mischung aus Benzol undDMF (7:3 v/v) wurden bei konstanter Temperatur aus Dichte-und Viskositätsmessungen ermittelt. Aus den Ergebnissen wurden die kritische Micellenkonzentration (CMC), Seifen-Lösungsmittel- und Seifen-Seifen-Wechselwirkungen sowie der Effekt der Kettenlänge der Seifenmoleküle auf verschiedene Parameter bestimmt. Die Resultate bezüglich Molvolumen und Viskosität werden anhand bekannter Beziehungen diskutiert.

     

Organic Compounds of Vth group Elements. I. Reactions of tantalum penta-ethoxide with oximes and diethyl-hydroxylamine

Complexes of the formula (EtO)_5?nTa(lig)_n (where n = 1–5; lig = diethylhydroxylamine or oximes) have been synthesized by the reactions of tantalum pentaethoxide with diethylhydroxylamine and oximes. A few isopropoxy and butoxy derivatives have also been synthesised by alcoholysis. I.R. spectra have been recorded and molecular weights determined in boiling benzene.     

Physico-chemical behaviour of the carbonate rocks of Western Son Valley Region,India

The techniques of DTA and TG were employed to study the thermal characteristics of unfossiliferous carbonate litho-units, viz. Fawn dolomitic limestone (microdolsparite) and Rohtas limestone (micrite) belonging to the Vindhyan Supergroup (PreCambrian) of India. The DTA of Fawn dolomitic limestone displayed two successive endothermic peaks at 725° and 860° whereas only one endothermic change at 910° was recorded in the DTA curve of Rohtas limestone. It was confirmed by chemical analyses, TG, IR and X-ray diffraction studies that the two peaks in the first case are due to dissociation of CO₂ from magnesium and calcium lattice positions, while the sole peak in the second case is due to complete decarbonation. A tentative correlation between the thermal characteristics and structural changes of these carbonate rocks at various transition temperatures is presented.     

Experimental Results on Using General Disjunctions in Branch-and-Bound for General-Integer Linear Programs

Typical implementations of branch-and-bound for integer linear programs choose to branch on single variables. In this paper we explore the use of general disjunctions for branching when solving linear programs with general-integer variables. We give computational results that show that the size of the enumeration tree can be greatly reduced by branching on such disjunctions rather than on single variables.     

Staffing call centers under arrival-rate uncertainty with Bayesian updates

We consider the problem of staffing service centers with quality-of-service constraints. We focus on the case where the arrival rates are uncertain. We introduce formulations that handle staffing decisions made over two decision periods, minimizing the staffing costs over the stages while satisfying a service quality constraint on the second stage operation. A Bayesian update is used to obtain the second-stage arrival-rate distribution based on the first stage prior arrival-rate distribution and the observations in the first stage.