Accurate fast neutron activation analysis for oxygen in geological materials

Sources of error in the fast neutron activation analysis determination of oxygen have been investigated and minimised. The oxygen contents of eighteen international rock standards and a sulphide ore standard have been determined, and compared with the values calculated by difference using the reported full analyses. Accuracies of 0.3% average deviation and reproducibilities of ±0.2% standard deviation have been obtained, where oxygen contents exceeded 1.0 g.     

Analyse de couches minces de verres chalcogenures par diffusion elastique de protons et mesure de gammas prompts

Résumé Une méthode d'étude de la composition stoéchiométrique de couches minces (10 à 500 μg/cm²) de verres chalcogénures est développée. L'étude des réactions nucléaire; induites par bombardement de protons de basse énergie (<4 MeV) sur les éléments constitutifs Ge, As, Te et S, conduit à choisir la diffusion élastique et la détection de gammas prompts pour le dosage simulatené. La précision et la sensibilité de la méthode sont discutées à partir des résultats obtenus. L'utilisation de la résonance fine sur le soufre (p, p'γ) est appliquée à l'étude de l'homogénéité des cibles.     

THE SYNERGISTIC ACTION OF ULTRAVIOLET AND X RADIATION ON MUTANTS OF ESCHERICHIA COLI K-12

Abstract— Prior UV irradiation increased the X-ray sensitivity of wild-type E. coli K-12. This synergistic effect of combined UV and X irradiation was also observed, but to a reduced extent, in uvrA, uvrB, uvrC , and polA mutants, but was absent in exrA, recA, recB , or recC mutants of E. coli K-12. Alkaline sucrose gradient studies demonstrated that the wand err gene-controlled, growth-medium-dependent (Type III) repair of X-ray-induced DNA single-strand breaks was inhibited by prior UV irradiation. This inhibition probably explains the synergistic effect of these two radiations on survival.     

Investigation of the reduction of methylenequinones by methods of polarography and EPR spectroscopy

Conclusions The polarographic reduction of certain methylenequinones was studied, and the mechanism of the reduction was investigated by the method of EPR spectroscopy.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1656–1658, July, 1970.     

Über Blei (II)-oxidhydrat der Zusammensetzung 3PbO·H2O

Lead oxide hydrate mentioned in the earlier literature with several formulas between PbO · H₂O and PbO · 0.33 H₂O has been synthesized and investigated by high resolution X-ray powder methods, thermogravimetry and infrared spectroscopy. The unit cell was found from 62 powder reflections to be tetragonal with a = 8.009 ± 0.003 Å, c = 9.312 ± 0.005 Å, Z = 12 [PbO · 0.33 H₂O]. These data were confirmed by WEISSENBERG and Precession photographs of single crystals grown as a corrosion product on metallic lead. The space group is D–P4/mnc or C–P4 nc. Thermogravimetric measurements, corrected for a slight content of superficially bound carbon dioxide detected by infrared spectroscopy, lead to the most probable formula 3 PbO · H₂O or PbO · 0.33 H₂O. As infrared spectra show the presence of a HOH deformation vibration, the compound is considered to be an oxide hydrate and not an oxide hydroxide of lead.     

Synthesis of 1,2-Divinyloxypropenes from Glycerol and Acetylene in the Superbasic System CsF-NaOH-DMSO

Russian Journal of Organic Chemistry -     

Determination of enthalpies of formation of organic free radicals from bond dissociation energies 2. Halosubstituted radicals

The enthalpies of formation (ΔH _f ^o) for 23 halosubstituted radicals were determined from the published data on bond dissociation energies. The ΔH _f ^o values of the corresponding molecules necessary for the calculation of ΔH _f ^o of the radicals were taken from handbooks or calculated by the additive-group method. The conjugation energies of the radicals are calculated, and the effect of substituents at the π-system on these values was shown. Errors of determination of the ΔH _f ^o values of the radicals were estimated. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 643–646, April, 1998.     

Ion-chromatographic study of the possible absorption of copper and zinc by the skin of Rana pipiens

Frogs are known to obtain some of their nutrients (e.g., glucose and sodium) through their skin. However, no studies have been made of the possible absorption of transition metals, which exist in most river water at low-ppb (w/w) levels. Therefore, this research was undertaken to evaluate the use of ion chromatography for such an investigation. Solutions of copper and zinc (20 ppb in each) were chosen for use in a small-scale screening study. Ten live frogs were each placed in individual baths for approximately 50 h. Of interest were the net changes in the concentrations of the metals. These differences were the result of any absorption and/or excretion processes that took place. A Dionex IonPac CS5 column was used to analyze this simulated river water, both before and after frogs had been placed in the solution. Included in this paper are: (1) methodology and calculation formulas; (2) precautions needed to ensure sample integrity; (3) statistical analyses, which indicated that ion chromatography is an accurate, precise technique for quantifying Cu and Zn in these samples; and (4) screening-study results, which were used to test the null hypothesis that frogs do not absorb copper and zinc either onto or through their skin.