Long-time asymptotics in the one-dimensional trapping problem with large bias

The survival probability of a particle which moves according to a biased random walk in a one-dimensional lattice containing randomly distributed deep traps is studied at large times. Exact asymptotic expansions are deduced for fields exceeding a certain threshold, using the method of images. In order to cover the whole range of fields, we also derive the behavior of the survival probability below this threshold, using the eigenvalue expansion method. The connection with the continuous diffusion model is discussed.     

Kinetic isotope effects in the photochemical reaction cycle of ion transporting retinal proteins

The kinetics of the photochemical reaction cycle of the bacteriorhodopsin, pharaonis halorhodopsin and proteorhodopsin were determined in H2O and D2O at low and high pH, to get insight in the proton dependent steps of the transport process. While all the steps of the bacteriorhodopsin photocycle at normal pH exhibited a strong isotope effect, the proton uptake step of the photocycle, measured at high pH, became independent of deuterium exchange, making plausible that this step, at low proton concentration, becomes concentration dependent, not mobility dependent. The proton transporting photocycle of the proteorhodopsin at its normal pH (9.5) shows a marked deuterium effect, while at high pH (12.2) this effect almost totally disappears. It was shown earlier that the proton uptake step of the proteorhodopsin is at the rise of the N form. As the proton concentration decreases with rising pH this step becomes the rate limiting, proton concentration dependent step, hiding all the other isotope dependent components. In the case of halorhodopsin in all the chloride, nitrate and proton transporting conditions the photocycle was not strongly affected by the deuterium exchange. While in the cases of the first two ions this seems normal, the absence of the deuterium effect in the case of the proton transporting photocycle was a puzzle. The only plausible explanation is that in the presence of azide the halorhodopsin transports not the proton, but a negatively charged ion the OH-, the mass and mobility of which is only slightly influenced by the deuterium exchange.     

Neue mikrogravimetrische Methoden für die Bestimmung des Osmiums

Analytical and Bioanalytical Chemistry - In der vorliegenden Arbeit werden zur mikrogravimetrischen Bestimmung des Osmiums drei Methoden empfohlen: 1. Aus der salzsauren Lösung von...     

Contributions to the complexometric determination of cation mixtures: Simultaneous titration of iron(iii) and aluminium in the presence of ammonium thiocyanate as indicator

With thiocyanate as indicator iron(III) and aluminium(III) can be titrated simultaneously if [Fe⁺³]/[Al⁺³] ? $\text{1}\text{4}$; iron(III) is titrated directly with EDTA, and aluminium(III) is determined by back-titration of the excess of EDTA with cobalt nitrate solution in an acetone-water medium.     

Natriumchlorit als Oxydationsmittel in der quantitativen analytischen Chemie

Zusammenfassung In der vorliegenden Arbeit werden einige Möglichkeiten der Verwendung von NaClO₂ als Oxydationsmittel für 8-Hydroxychinolin untersucht. Dabei ergaben sich vorteilhafte Verfahren zur Bestimmung von Elementen, welche als Oxinate fällbar sind.Als Beispiel ist eine indirekte Bestimmungsmethode von Molybdän in Molybdänitkonzentraten entwickelt worden, bei der die Rücktitration des Oxydationsmittelüberschusses mit jodometrischer oder potentiometrischer Endpunktsindikation erfolgt.V. Mitteilung: Spacu, P., M. Brezeanu, C. Gheorghiu u. E. Cristurean: Rev. Chim. A. S. I. T. 12, 723 (1961).     

Effect of alkali pre-treatment on hydrolysis of regenerated cellulose fibers (part 1: viscose) by cellulases

Viscose fabrics were pre-treated with liquid ammonia and NaOH solutions. The pre-treatment was varied in alkali concentration, time and drying conditions. Subsequently, the samples were subjected to cellulase hydrolysis. Microscope and SEM pictures were taken; weight loss, reducing sugar and protein content in solution, water retention value and tensile strength were determined. It was found, that the activity of cellulases is increased for viscose and that short time alkali pre-treatment reduces tensile strength due to changes in the substrate. The drying and drying conditions (wet, line dry of freeze dry) have great impact on the hydrolysis rate. A connection between the rate of protein loss in solution and changed water retention value was established. Weight loss of 80% of cellulose fabric was achieved within 4 h of enzyme hydrolysis.