A Study of Viscosity in the Extraction System Constituted by Tributyl Phosphate and Phosphoric Acid

Data on the kinematic viscosity of phosphoric acid solutions in technical-grade tributyl phosphate and in an industrial extract from a technological purification system based on tributyl phosphate, which contain 0–18% phosphoric acid in terms of P₂O₅, at 10–70°C are presented.     

Analytical and radioanalytical quality control of purity and stability of radiopharmaceutical compound [186gRe]Re-HEDP for bone metastases pain palliation

Summary The nuclear properties of ^186gRe make it a useful agent for radionuclide therapy and imaging. The coordination compound [^186gRe]Re-HEDP has proved to be a successful bone seeking agent for palliation of metastatic bone pain. Chemical, radiochemical and radionuclidic purity of commercial radiopharmaceutical [^186gRe]Re-HEDP have been checked by means by γ- and β-spectrometries, INAA and paper radio-chromatography. The results indicate a good radionuclidic purity, with levels of contamination from the short-lived ¹⁸⁸Re well below the required specifications. After injection of the radiopharmaceutical, the radiochemical measurements conducted in vivo, on biological matrices, blood, plasma and urine, have shown that, entering the systemic circulation, ^186gRe dissociates from the bis-phosphonate complex as hydrosoluble [^186gRe]ReO₄-, and the two chemical species follow different biokinetics.     

Molecular Dynamics Simulation of Surfactant Microaggregates in the Apolar Medium of <Emphasis Type="Italic">n</Emphasis>-Octane

Molecular dynamics simulation of reverse micelles of a cationic surfactant and water clusters in n-octane is performed. The main structural and thermodynamic characteristics of the systems are obtained. On average, the micelles have a spherical shape. The partial ion distribution densities virtually coincide, indicating the formation of stable ion pairs. The local profiles of the component distribution densities make it possible to establish that both water and oil slightly penetrate into the region where the hydrophobic portion of the surfactant is located. Separate cation-anion complexes dissolve in the aqueous cavity of a micelle. The hydration shells of the ions overlap; at the same time, the first hydration shell contains up to three water molecules. The energy contributions of each of the components to their force interaction are characterized in detail. The principal contribution to the internal energy for micelles is due to electrostatic interaction between the surfactant molecules. The local normal pressure is calculated, and its value is used to estimate the effective surface tension for the systems in question.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 4, 2005, pp. 500–507.Original Russian Text Copyright © 2005 by Mudzhikova, Brodskaya.     

Calculation of accurate permanent dipole moments of the lowest 1,3Sigma+ states of heteronuclear alkali dimers using extended basis sets

Obtaining ultracold samples of dipolar molecules is a current challenge which requires an accurate knowledge of their electronic properties to guide the ongoing experiments. In this paper, we systematically investigate the ground state and the lowest triplet state of mixed alkali dimers (involving Li, Na, K, Rb, Cs) using a standard quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective terms for core polarization effects. We emphasize on the convergence of the results for permanent dipole moments regarding the size of the Gaussian basis set, and we discuss their predicted accuracy by comparing to other theoretical calculations or available experimental values. We also revisit the difficulty to compare computed potential curves among published papers, due to the differences in the modelization of core-core interaction.     

Thiophene conversion in the BIMF process

Catalytic conversion of an oil distillate with the added extra amounts of thiophene over a zeolite catalyst was studied. The rate of the catalyst deactivation was found to increase with the increase in the thiophene concentration in the feed. A possible pathway of the thiophene conversion is discussed.     

Separation and identification of organic and organometallic compounds by use of a liquid chromatography-particle beam-glow discharge mass spectrometry combination

Evaluation of the particle beam glow discharge mass spectrometry (PB-GDMS) system as a detector for liquid chromatography (LC) is described for the analysis of polycyclic aromatic hydrocarbons, steroids, selenoamino acids, and alkyllead compounds. A particle beam interface is used to introduce analyte species from the LC into a glow discharge source for subsequent vaporization and ionization. Mass spectra display classic EI fragmentation patterns for the organic compounds, as well as elemental and molecular information for the organometallic compounds. Chromatographic separations display good temporal correlation between UV and PB-GDMS detection modes. Detection limits for Pb in lead nitrate, triethyllead, and triphenyllead fall in the sub-ppb (ng) range.     

The role of surface oxides in formic acid oxidation on Au

Compared to Pt or Pd electrodes, Au is a poor catalyst for the direct anodic oxidation of HCOOH, but the formation of Au surface oxides in acidic solutions is accompanied by a fast oxidation of HCOOH. This fast reaction is not simply a secondary reaction of Au surface oxides since those oxides are kinetically stable in HCOOH solutions. They do oxidize HCOOH only via a slow and purely electrochemical process which occurs on free Au sites and is “driven” by oxide reduction. The fast HCOOH oxidation is due to a highly reactive intermediate which is able either to form stable Au oxides Au_nO_m or to react with HCOOH. Our results are consistent with the model that by the charge transfer step a reactive non-equilibrium {Au…O> species is formed which converts to stable equilibrium oxides Au_nO_m after migration and rearrangement steps. Pre-equilibrium <Au…O> oxidizes HCOOH and this oxidation is of lower order with respect to <Au…O> compared with the formation of Au_nO_m.     

Reactions of heterocyclic cations with nitrogen-containing nucleophiles. 10. Synthesis of 3,5,7-triaryl-1,2-oxazepinium perchlorates by the reaction of 2,4,6-triarylpyrylium salts with nitrones and substituted hydroxylamines

2-Substituted 3,5,7-triaryl-1,2-oxazepinium perchlorates were obtained by the reaction of 2,4,6-triarylpyrylium salts in dimethylformamide with nitrones and N-arylhydroxylamines. The products are the first representatives of seven-membered cations with eight electrons.See [1] for Communication 9.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 457–460, April, 1982.     

Role of phosphates in the promotion of silver catalysts for partial oxidation: I. Structure and properties of phosphates on the surface of polycrystalline silver

The chemical composition, structure, and properties of an H₃PO₄-promoted polycrystalline silver foil are studied by XPS. The surface of the doped sample contains oxygen in two states with binding energies of 531.1 and 533.0 eV. Heat treatment results in silver clusters distributed in the polyphosphate matrix. It follows from TDS data that the surface of the promoted catalyst contains a strongly bound oxygen species that desorbs at ~900 K. It is believed that the silver clusters stabilized by the phosphate matrix are active sites on the surface of the phosphorus-promoted catalyst.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 153–160. Original Russian Text Copyright © 2005 by Knyazev, Boronin, Vodyankina, Koshcheev, Kurina.     

16-Demethoxymethyllycaconitine,a new norditerpenoid alkaloid from Delphinium cuneatum

A new norditerpenoid alkaloid has been isolated from the roots of Delphinium cuneatum. On the basis of ¹H, ¹³C NMR, IR, and mass spectra, the structure of the alkaloid was established as 1,6,14-trimethoxy-7,8-dihydroxy-18-(2-methyl)succinylanthranoyloxyaconane (16-demethoxymethyllycaconitine). The roots of Delphinium cuneatum also contain the known alkaloid methyllycaconitine and N,N"-di(methoxycarbonyl)-3,4-diaminotoluene.