Die Verteilung eines l?slichen Stoffes zwischen zwei L?sungsmitteln

Ohne Zusammenfassung     

A simple route to 6- and 7-fluoro-substituted naphthalene-1-carboxylic acids

A simple one-pot method for the synthesis of 6-fluoro- and 6,7-difluoro-1-naphthoic acid is described. 6-Fluoro-1-naphthoic acid can be converted into 7-fluoro-1-naphthoic acid in three straightforward steps.     

Hierarchical models of interacting diffusions: Multiple time scale phenomena,phase transition and pattern of cluster-formation

Summary The purpose of this paper is to explore the connection between multiple space-time scale behaviour for block averages and phase transitions, respectively formation of clusters, in infinite systems with locally interacting components. The essential object is the associated Markov chain which describes the joint distribution of the block averages at different time scales. A fixed-point and stability property of a particular dynamical system under a renormalisation procedure is used to explain this pattern of cluster formation and the fact that the longtime behaviour is universal in entire classes of evolutions.     

Effects of cycloheximide on liquid-holding recovery from ultraviolet radiation damage in yeast cells

Abstract. The role of protein synthesis in liquid-holding recovery from ultra-violet radiation damage in synchronized Saccharomyces cerevisiae cells has been studied using cycloheximide as a specific inhibitor of cytoplasmic protein synthesis. Liquid-holding recovery from UV-induced budding delay is completed within a few hours and is not inhibited by the presence of cycloheximide. Liquid-holding recovery from lethal UV damage is unaffected by cycloheximide for liquid-holding times less than about 12 h. For longer times recovery is inhibited, with survival enhancement eliminated after about 48 h. Periods greater than 48 h of liquid-holding in the presence of cycloheximide result in survival less than that obtained with immediate plating, but the same concentration of cycloheximide is not toxic to unirradiated cells.     

The lifetime of positive streamers in a pulsed point-to-plane gap in atmospheric air

A determination has been made of the lifetime of positive streamers produced in atmospheric air in a positive point-to-plane gap to which was applied a 40 nsec, 40 kV voltage pulse. The streamer tips have been detected at a given plane in the gap by means of a photomultiplier and high speed oscilloscope. It was found that the streamer tips continued to propagate in the gap, long (up to 35 nsec) after the voltage pulse was removed, in accordance with the predictions of a recently presented model of streamer propagation. Association of this long lifetime with the properties of an isolated tip was made possible by the detection of a new phenomenon at the anode. At the end of the voltage pulse a second luminosity was observed to leave the anode and to extend along the paths of the primary streamers for about one third of their length. This is shown to be the maximum extent of a more highly conducting trunk, behind and separated from the streamer tip, affecting both the propagation of the tip and the eventual transition of a streamer to a breakdown spark.     

Preparation of ion-selective membranes from crosslinked copolymers of styrene and p-vinylbenzenesulfonic acid

Ion-selective membranes similar to those described by Graydon and Stewart [J. Phys. Chem. 59 , 86 (1955)] were prepared by improved methods involving copolymerization of styrene, n-propyl-p-vinylbenzenesulfonate, and divinylbenzene (DVB) with subsequent hydrolysis of the ester. Both the highly reactive ester and DVB were purified by column chromatography and were well characterized by their infrared and proton magnetic resonance spectra. For preparation of membranes about 25% by weight of N,N-dimethylformamide (DMF) was included with the vinyl monomers in the polymerization mixture. Thermal polymerization was initiated by benzoyl peroxide, and membranes were formed in special molds of two types. In one type a free surface of the mixture was exposed, while in the other the mixture filled the mold. The DMF in the fresh membranes was replaced with aqueous KOH by diffusion, and hydrolysis was then carried out. By this method hydrolysis times were decreased from several days to a few hours. Capacity, water content, and thickness were determined for all membranes, and density, swelling in salt solutions, and Young's modulus were measured for selected membranes. The Vermaas-Hermans-Flory theory of polyelectrolyte gels was found to account satisfactorily for the swelling properties and water content of these membranes, the solvent interaction parameter χ1 increasing with increasing volume fraction of polymer from 0.7 to 1.0 at zero external salt concentration and up to 1.8 for membranes deswollen in 1M KCl. No differences in average water contents for given densities of fixed charge and crosslinking were observed with (1) different molds, (2) commercial or pure DVB, and (3) a swelling agent (DMF) or no swelling agent. The results in general indicate that the state of the membrane at a given temperature and pressure can be specified by any two of the parameters: degree of ionization per unit volume of an average structural unit, concentration of crosslinking agent, and degree of swelling. Young's modulus decreased markedly with increasing water content, but data were not sufficiently extensive or precise to permit a quantitative treatment.     

Overlap of He atom and He+ ground-state wave functions and calculation of ionization potential

The one-body equation proposed earlier for determining the overlap of He atom and He⁺ wave functions can be given a fundamental justification. This equation with an approximate form of one-body potential can be solved, and an excellent ionization potential results. The helium atom ground-state wave function can thereby be refined.