Rapid qualitative analysis of metallic alloys by electrospot chromatography

Summary Electrography and paper chromatography were combined to analyse rapidly metallic alloys in an almost non destructive technique. Using anodic dissolution the sample is applied on the start point of the chromatographic paper. Known ketones-HCl-water mixtures are usually used as solvents to analyse electrospots of different alloys and metal coatings and a separate electrospottest is recommended for Cr. Results of qualitative analysis of some steels, Cu–Ni, and Pb alloys are presented.     

Correlation between excess adsorption data measured for solvent mixture/adsorbent systems and RM values obtained for different solutes chromatographed in binary mobile phases

This paper concerns the application of excess adsorption isotherms, measured for solvent mixture/adsorbent systems, to the characterization of TLC data. For this purpose the excess adsorption isotherms for three liquid mixtures: cyclohexane/ benzene, benzene/acetone, and carbon tetrachloride/ethyl acetate on silica gel at 20°C have been measured. These mixtures have been used as binary mobile phases in TLC measurements. It has been shown for a given solute in binary mobile phase that the quantity R_M is a simple function of the excess adsorption. Parameters of this function have been used to characterize chromatographic systems with binary mobile phases.     

Sorption and desorption of molybdenum in alumina microspheres

The behavior of minor amount of molybdenum(VI) in the presence of large quantity of aluminum nitrate and separation of Mo(VI) from Al(III) with the aid of a chromatographic process onto an alumina column has been studied. The separation of both elements is in favor of the selective uptake of molybdenum by the alumina. The solution containing both elements is an acidified aluminum nitrate of high concentration in aluminum. The work envisage a future separation and purification of radiomolybdenum for the milking of tecnetium-99m.     

Nuclear magnetic resonance studies of sulfur inversion in bis(cyclopentadienyl)-molybdenum and -tungsten complexes with dithioethers

The metallocene thioether derivatives [Cp₂M(MeSCH₂CH₂SMe)][PF₆]₂ (1, M = MO; 2, M = W), [Cp₂Mo(SCH₂CH₂SMe)][PF₆] (3) and [Cp₂M(SCH₂CH₂S)] (4, M = Mo; 5, M = W) exhibit temperature-dependent fluxional behavior in solution, owing to the pyramidal sulfur inversion process. The activation energies for this process were determined from proton band-shape analysis in the cases of 1 (54.9 ± 2 kJ mol⁻¹), 2 (51.2 ± 4.6 kJ mol⁻¹) and 3 (30.0 ± 3.1 kJ mol⁻¹). Extended Hückel calculations on related model complexes suggest that local inversion at the sulfur atoms, rather that an inversion of the complete S---C---C---S chain, is responsible for the observed fluxional behaviour.     

Direct versus resonances mediated F+OH collisions on a new 3A" potential energy surface

A theoretical study of the F(2P) + OH(2Pi) --> HF(1Sigma+) + O(3P) reactive collisions is carried out on a new global potential energy surface (PES) of the ground 3A" adiabatic electronic state. The ab initio calculations are based on multireference configuration interaction calculations, using the aug-cc-pVTZ extended basis sets of Dunning et al. A functional representation of the PES shows no nominal barrier to reaction, contrary to previous results by others. Wave packet and quasiclassical trajectory calculations have been performed for this PES to study the F + OH(v = 0,j) reactive collision. The comparison was performed at fixed and constant values of the total angular momentum from 0 to 110 and relative translational energy up to 0.8 eV. The reaction presents a dynamical barrier, essentially due to the zero-point energy for the bending vibration near the saddle point. This determines two different reaction mechanisms. At energies higher than approximately 0.125 eV the reaction is direct, while below that value it is indirect and mediated by heavy-light-heavy resonances. Such resonances, also found in the simulations of the photodetachment spectrum of the triatomic anion, manifest themselves in the quasiclassical simulations, too, where they are associated to periodic orbits.     

Differential calculus on quantized simple lie groups

Differential calculi, generalizations of Woronowicz's four-dimensional calculus on SU _q (2), are introduced for quantized classical simple Lie groups in a constructive way. For this purpose, the approach of Faddeev and his collaborators to quantum groups was used. An equivalence of Woronowicz's enveloping algebra generated by the dual space to the left-invariant differential forms and the corresponding quantized universal enveloping algebra, is obtained for our differential calculi. Real forms for q are also discussed.     

Magnetic properties of Fe−Mn−Al alloy system in the FCC disordered phase

In this work we report the experimental studies of Fe?Mn?Al alloys in the FCC disordered phase at room temperature by Mössbauer spectroscopy and X-ray diffraction. In this phase the alloys are antiferromagnetic with a constant mean hyperfine field ( \(\bar H\) ) near 26 kOe in the composition range from 0 to 7.5 at.% Al and 50 to 65 at.% Fe. When the Al or Fe concentration increases, the \(\bar H\) value gradually decreases to zero and the alloy becomes paramagnetic. In the same way when the Al concentration increases the lattice parameter increases linearly but when the Fe concentration increases the lattice parameter remains nearly constant for alloys with 5 at.% Al and decreases for alloys with 10 at.% Al.