Über die Darstellung von Dimethyl(mercapto)sulfonium-hexa-chloroantimonat [(CH3)2SSH]+SbCl6−

Preparation of Dimethyl(mercapto)sulfonium-hexachloroantimonate [(CH₃)₂SSH]⁺SbCl₆^? The preparation of [(CH₃)₂SSH]⁺SbCl₆^? from [(Ch₃)₂SCl]⁺SbCl₆^? and H₂S at 223 K is reported. This salt is stable below 243 K and is characterized by vibrational spectroscopy.     

Noncovalent immobilized artificial membrane chromatography, an improved method for describing peptide-lipid bilayer interactions.

A promising approach in assessing hydrophobic peptide-membrane interactions is the use of reversed-phase high-performance liquid chromatography. The present study describes the preparation and properties of a noncovalent immobilized artificial membrane (noncovalent IAM) stationary phase. The noncovalent IAM phase was prepared by coating the C18 chains of a reversed-phase HPLC column with the phospholipid ditetradecanoyl-sn-glycero-3-phosphocholine. Lipid coating was achieved by pumping a lipid solution in water-2-propanol through the column. The formation of a bilayer-like structure on the chromatographic surface was confirmed by calculating the phospholipid surface density of the stationary phase. The surface density was determined to be approximately 1.95 mumol m-2, which is close to that of lipid vesicles. The coating was found to be stable in chromatographic elution systems containing less than 35% of acetonitrile. Employing this new technique, we determined interaction parameters of a set of helical antibacterial magainin-2-amide peptides with pairwise substitutions of adjacent amino acids by their D-enatiomers. The results demonstrate that the chromatographic retention behavior of peptides on noncovalent IAM stationary phase shows an excellent correlation with lipid affinities to phospholipid vesicles.     

Hydrophilic sensor membrane based on cation-selective protic chromoionophore

The first potassium optode based on a protic chromoionophore immobilized in a hydrogel matrix is presented. The highly selective protic chromoionophore consists of a cryptohemispherand moiety and a trinitroanilino chromophore part. The acidifying power of potassium ions over sodium ions is 0.6 pH units. This correlates with the findings in solution. In contrast to several crown and aza-crown based chromophores the highly pre-organized moiety allows ion detection even in aqueous environment. The detection limit for potassium ions at ¶pH 7.7 is 5 μM.     

Internal attenuation of laser radiation in the CuCl laser

A double-pulsed neutral copper vapor laser, based on a Cu/CuCl discharge, was placed in tandem with a ZnCl₂ discharge cell in a common optical cavity. The ZnCl₂ in the separately heated discharge tube acted as a source of Cl-based plasma by- products which are also likely constituents of the Cu/CuCl laser plasma. The timing of the two discharges was varied relative to one another and the Cu laser emission at λ = 510 nm was monitored to test the optical absorption losses in the combined cavity in relation to time. The experiments provide some insight into the chemical effects in the laser plasma that may limit the energy output of a Cu/CuCl laser.     

Texture development in polyethylene. I. Uniaxial extension and uniaxial compression

Texture development of high-density polyethylene has been studied by x-ray diffraction at various strains for uniaxial extension, as achieved by uniaxial tension and extrusion, and for uniaxial compression. Pole distributions were measured for the (100), (200), (020), and (011) reflections. Textures were described by ideal single-crystal orientations with inverse pole figures. In uniaxial extension, samples were deformed up to true strains of 1.83 (reductions of up to 84%). After a strain of 0.55, the c axis oriented at 35° from the extension axis and with increasing strain approached the extension axis. This was attributed to initial (110) or (310) twinning in combination with (100) slip, followed subsequently by [001] slip. In compression, samples were deformed up to true strains of 1.83 (reductions up to 84%). The texture consisted of strong components of the compression axis near (100) and weaker components near (110). At higher strains the intensity of the near-(100) components decreased, whereas the near-(110) components became more intense. The near-(100) components are explained by slip on (100) planes. The growth of the near-(110) components at the expense of the near-(100) components can be explained by relaxation twinning of the near-(100) components.     

Minimal renormalization without ɛ-expansion: Amplitude functions in three dimensions

The minimal subtraction scheme and the Borel resummation method are used to calculate the amplitudes of renormalized correlation functions aboveT _c for then-vector model in three dimensions. Accurate representations are given for the effective amplitudes of the renormalized expressions of the correlation length, of the susceptibility and of the specific heat forn=1, 2, 3. The resummed higher-order contributions turn out to yield only small corrections to the low-order approximations. These results complement a recent calculation of renormalization-group functions and provide the basis for accurate analyses of the critical behavior in three dimensions including the amplitude functions.