Measurements of the perpendicular width of ionization-produceddouble layers

Measurements of the perpendicular (to B) double-layer widths of ionization-produced (anode) double layers are presented. These widths were determined from measurements of the double-layer charge separations. The variations of the transverse-to-B widths with plasma density and magnetic field strength are given     

Structure of the hydrated and dimethyl sulfoxide solvated rubidium ions in solution

The structure of the hydrated and the dimethyl sulfoxide solvated rubidium ions in solution has been determined by means of large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) studies. The models of the hydrated and dimethyl sulfoxide solvated rubidium ions fitting the experimental data best are square antiprisms with Rb-O bond distances of 2.98(2) and 2.98(3) A, respectively. The EXAFS data show a significant asymmetry in the Rb-O bond distance distribution with C(3) values of 0.0076 and 0.015 A(3), respectively. No second hydration sphere is observed around the hydrated rubidium ion. The dimethyl sulfoxide solvated rubidium ion displays a Rb-O-S bond angle of ca. 130 degrees, which is typical for a medium hard electron acceptor such as rubidium.     

Synthesis and properties of new glucocationic surfactants: model structures for marking cationic surfactants with carbohydrates

[reaction: see text] In this work, we report the synthesis of a new series of glucocationic surfactants, a class of surfactants we introduced very recently. The preparation of the surfactants is based on the synthesis of the 2-bromoethyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside, whose preparation was studied in order to improve yields and stereoselectivity of this key intermediate. These glucocationic amphiphiles were prepared and studied as a model of cationic surfactants marked with a carbohydrate moiety. The use of carbohydrates as markers on cationic lipids was recently introduced to induce recognition by specific receptors, present on the surface of cell membranes. The chemicophysical characterization of these model structures can give more insight on the aggregation behavior. Conductivity and surface tension measurements were performed in order to characterize the compounds from the amphiphilic point of view. The results showed a different effect of the glucosidic moiety on the cmc value with respect to the glucopyridinium cationic surfactants. The surfactants also showed the tendency to form premicellar aggregates in solution when the hydrophobicity is raised.     

Using staggered grids with characteristic boundary conditions when solving compressible reactive Navier–Stokes equations

A specific (hybrid) arrangement of variables is discussed to solve reactive compressible Navier–Stokes equations on staggered‐like grids with high‐order finite difference schemes. The objective is to improve the numerical flow solution at boundaries. Hybrid arrangement behaviour is compared with ‘pure’ colocated and staggered strategies. Classical Fourier analysis shows accuracy to be significantly improved in the hybrid case. One‐dimensional laminar flame test demonstrates increased robustness (in terms of mesh resolution), whereas computation of 1D exiting pressure wave propagation gives evidence that the method also improves accuracy in the prediction of non‐reflecting outflows, compared e.g. with the fully staggered scheme of (J. Comput. Phy. 2003). Multidimensional extension is illustrated through turbulent 2D planar and 3D expanding flames simulations. Copyright © 2011 John Wiley & Sons, Ltd.     

Ritter Reactions between Alcohols and Acetonitrile Mediated by the Conducting Polymer Poly-(3,4-ethylenedioxy Thiophene) (PEDOT)

Herein, we report new reactivity of the conducting polymer, poly-(3,4-ethylenedioxy thiophene) (PEDOT), where PEDOT mediates a Ritter reaction between alcohols and acetonitrile. The yields were variable and in most cases competitive with results obtained using sulfuric acid. Attempts at a stoichiometric reaction between benzonitrile and diphenylmethanol are also reported herein. Finally, described here are preliminary mechanistic studies that suggest PEDOT is behaving as an alcohol-selective or specific Lewis acid.

Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for full experimental and spectral details.     

A high statistics measurement of the Lambda(+)(c) lifetime

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.