Thin-Layer Chromatographic and Polarimetric Investigation of the Oscillatory In-Vitro Chiral Inversion of S-(+)-Ketoprofen

JPC – Journal of Planar Chromatography – Modern TLC - Our earlier thin-layer chromatographic and polarimetric investigations enabled discovery of the spontaneous in-vitro oscillatory...     

Measurement of the spin and magnetic moment of 31Mg: evidence for a strongly deformed intruder ground state

Unambiguous values of the spin and magnetic moment of 31Mg are obtained by combining the results of a hyperfine-structure measurement and a beta-NMR measurement, both performed with an optically polarized ion beam. With a measured nuclear g factor and spin I=1/2, the magnetic moment mu(31Mg)=-0.88355(15)mu(N) is deduced. A revised level scheme of 31Mg (Z=12, N=19) with ground state spin/parity I(pi)=1/2(+) is presented, revealing the coexistence of 1p-1h and 2p-2h intruder states below 500 keV. Advanced shell-model calculations and the Nilsson model suggest that the I(pi)=1/2(+) ground state is a strongly prolate deformed intruder state. This result plays a key role for the understanding of nuclear structure changes due to the disappearance of the N=20 shell gap in neutron-rich nuclei.     

Adsorption/partition model of liquid chromatography for chemically bonded stationary phases of the aliphatic cyano, reversed-phase C8 and reversed-phase C18 types

A novel approach was introduced to modeling solute retention in the liquid chromatography systems, employing silica-based aliphatic chemically bonded stationary phases of the cyano, reversed-phase C8 and reversed-phase C18 types, and the mixed binary eluents most frequently used in the reversed-phase and normal-phase chromatography modes (i.e. using the methanol-water and the 2-propanol-n-hexane liquid mixtures, respectively). This approach takes notice of the mixed (adsorption/partition) mechanism of solute retention, in which both, the adsorptive and the dispersive forces contribute to the overall energetics of this process. Performance of our new model was compared with that of the widely recognized and on a routine basis applied Schoenmakers approach, and it was found out that both models perform with a practically equal and outstanding accuracy.     

Investigation of the association of higher fatty alcohols on a chromatographic paper

Summary An attempt was made to apply a low-activity chromatographic layer (Whatman 2) and a non-polar mobile phase (decalin) in studying the self-association of higher fatty alcohols. The obtained results showed a satisfactory, semi-quantitative agreement with IR spectroscopic data and theoretical considerations and calculations. Usefulness of the complementary paper chromatographic investigations can be considered as complementary investigations when setudying the self-association of higher fatty alcohols.     

The effects of ultrasound on chromium gels in light of their catalytic activity and electron paramagnetic resonance

Investigations into the influence of ultrasound on the catalytical properties of chromium gels are presented. The changes of the EPR spectra and surface concentration of Cr on the sixth oxidation degree of certain preparations are described. These changes are then related to the increase in the velocity in the test reaction of H₂O₂ decomposition and the increased yield of cyclohexane dehydrogenation when the insonated preparations are used as catalysts.     

Investigation of Phase Transition inLa1–xPrxGaO3 and La1–xNdxGaO3 Crystals

The solid solution crystals, La_1–xNd_xGaO₃ and La_1–xPr_xGaO₃ have been studied by differential scanning calorimetry method; the crystals exhibit the first order phase transition, the temperature of the transition linearly increases with the concentration of Pr or Nd. The structure of the crystals has been determined by X-ray diffraction. The correlation between the phase transition temperature and crystalline structure at the temperature of the phase transition in both solid solution families is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of space charge on the mass purification in Penning traps

The influence of space charge on the mass selection of ions stored in a Penning trap was investigated with the ISOLTRAP experiment at CERN/ISOLDE. A mixture of ^85,87Rb^?+? ions has been used to probe the change of the experimental parameters, e.g. frequencies and amplitudes of the radiofrequency excitations, as a function of the number of ions present in the trap.     

Oxidative stabilities of enzymatically interesterified goose fat and rapeseed oil blend by rancimat and PDSC

Goose fat (GF) and rapeseed oil (RSO) 2:3 m m^?1 blend was enzymatically interesterified at 60 °C with and without microwaves assistance. As the catalyst, a commercial preparation of the immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) containing 2 % of water was used, and the catalyst load was 8 % in each case. The starting mixture and the interesterified products were separated by column chromatography into pure triacylglycerols fraction (TAG) and a non-triacylglycerol fraction, which contained free fatty acids (FFA), mono- and diacylglycerols (MAG and DAG). The oxidative stabilities of fats studied and TAG derived from them were assessed by Rancimat at 100 °C and by pressure differential scanning calorimetry (PDSC) under oxygen at 110–140 °C. Interesterification reduced the oxidative stability of GF and RSO blend. The main factors influenced on the oxidative stabilities of fats studied were concentrations of tocopherols and the presence of FFA, MAG and DAG. The structures of TAGs were of minor importance. From the resulting PDSC exotherms, their times to reach the onset (τ _on) and peak maximum (τ _max) were measured and used for calculations of parameters of the Arrhenius type kinetics for thermaloxidative decomposition of fats studied.