Ueber die Trennung und Bestimmung von Nickel und Kobalt

Ohne Zusammenfassung     

A systematic study of bovine serum albumin (BSA) and sodium dodecyl sulfate (SDS) interactions by surface tension and small angle X-ray scattering

Classical parameters obtained from surface tension technique coupled to small angle X-ray scattering (SAXS) measurements gave support to investigate conformational changes in the bovine serum albumin (BSA)-sodium dodecyl sulfate (SDS) complexes, as well as the size of the micelle-like clusters distributed along the polypeptide chain. The studied systems were composed of 1 wt% of BSA in the absence and presence of increasing SDS molar concentration up to 80 mM, under experimental conditions of low ionic strength and pH 5.40. At SDS concentrations below the critical aggregation concentration (cac) of 2.2 mM, SAXS results indicate that the detergent does not modify the native protein conformation. However, the beginning of protein unfolding, evidenced by SAXS through an increase in the values of radius of gyration Rg and protein maximum dimension Dmax, is coincident with the onset of SDS cooperative binding to BSA identified by the first breakpoint in the surface tension-SDS profile. Further SDS addition leads to the formation of micelle-like aggregates randomly distributed along the unfolded polypeptide chain, consistent to a necklace and bead model. The SAXS data also demonstrate that the SDS micelles grow in size up to 50 mM detergent. At 50 mM surfactant, the micelles stop growing. This concentration is near the BSA saturation binding by SDS measured by dialyzes and indicated by the second breakpoint in surface tension-SDS profile. The SAXS and surface tension data are also consistent with the formation of free micelles in equilibrium with BSA-SDS complexes for surfactant amount above the saturation.     

Über Reaktionen von Antimonhalogeniden. II. Die Reaktion von SbCl5 mit Oxalsäure-bis-(methylamid)

Reactions of Antimony Halides. II. The Reaction of SbCl₅ with Oxalic Acid Bis(methylamide) The reaction of antimony pentachloride with the dimethylamide of oxalic acid results in the formation of a five-ring heterocyclic compound C₄H₇Cl₄N₂O₂Sb(I), in which the ring components are Sb, N, C and O. It's synthesis and properties are discussed. Results of the mass spectrum see Table 1, a fraction scheme is given.     

Elektron-Bremsstrahlungswirkungsquerschnitte von 180- und 380 keV-EIektronen

The bremsstrahlung cross sections, differential in photon energy and angle have been determined by measuring the x-rays emitted from thin targets (Al₂O₃: 56,5 and 113 μg/ cm²; Au: 9,7 and 24,4 μg/cm²) for incident electron energies of 180 and 380 keV with a 5×5 inch NaI scintillation spectrometer at angles from 0 to 150 degrees. A response matrix is used to convert the measured pulse height distribution into the spectrum of photons incident on the spectrometer. The results show that in this energy region the Bethe-Heitler-Sauter (Born approximation) theory underestimates the cross sectionsd ² σ/dk · dΩ anddσ/dk. The application of the Elwert factor gives a considerable improvement. For Al₂O₃ the Elwert corrected Born approximation gives values which are generally within the limits of error of the measurements. The experimental values of theHeitler parameter\(\Phi _{rad} /\bar \Phi \) are 5,0 (Al₂O₃) and 6,7 (Au) for 180 keV and 5,6 (A1₂O₃) and 7,3 (Au) for 380 keV. The angular distribution of the radiation has been compared with some characteristic angles predicted by the theory ofSommerfeldKulenkampff. Special consideration has been given to the high frequency limit. The cross sections at this energy have been derived from the correctedSauter-Fano theory and are in good agreement with the measurements.     

Spezifische Molekültemperaturen in Lichtbögen

By means of thermodynamic equilibrium calculations emission coefficients of molecular bands of A1O and CN are computed. For given pressure and particle concentrations the coefficients show well defined maxima at certain temperatures, usually referred to as normalized temperature of the band system. This behaviour applied to electrical arcs explains the existence of aureoles caused by molecular emission of CN and some metallic oxide bands localized at fixed distances from the centre of the arc. The local temperature of the area of maximum intensity depends not only on the dissociation energy and excitation energy of the molecule in question, but may be altered by the presence of additional components and stoichiometric conditions. Thus, the normalized temperature of band systems arising from heteronuclear molecules cannot be considered as an unchangeable quantity.