Rotational bands in79Kr

The level scheme of⁷⁹Kr has been studied through the⁷⁹Br(p,n)⁷⁹Kr reaction at proton energies from 1·7 to 5·0 MeV.γ-ray and internal conversion electron measurements were made using Ge(Li) detectors and a six gap “Orange” electron spectrometer. The level scheme was established by determining the thresholds of variousγ-rays and byγ-γ and n-γ coincidence measurements. New levels at 402, 450, 660, 676, 695, 720, 810, 836, 907 and 1038 keV not observed in earlier radioactivity studies have been established. DefiniteJ ^π assignments have been made to most of the levels below 800 keV. Many of the low-lying levels are identified as rotational levels based on the (301 ↓) 1/2^?, (301 ↑) 3/2^? and (431 ↓) 1/2⁺ Nilsson states.     

The nature of species adsorbed on platinum from SO2 solutions

The present studies have shown that at θ_S<0.9, the species adsorbed on platinum from SO₂ solutions are virtually identical with those obtained from H₂S solutions. The layer at θ_S>0.9 can be explained by the formation of a partial bilayer on top of the first layer wherein 70% of the sites are covered with S (2-site adsorption) and 30% with S (1-site adsorption). It has also been shown that the ‘difficultly reducible’ oxygen referred to by earlier workers is identical with the species formed by exposure of the electrode to SO₂ at potentials above 0.2 V. Evidence for the presence of two forms of ‘difficultly reducible’ oxygen, corresponding to the two forms of chemisorbed sulfur, is presented.     

Studies in gelation of product obtained in the metathesis of sodium silicate with chlorides of iron or chromium

Summary Like the silica gel the hydrogen ion concentration greatly influences the gelation of the product obtained in the metathesis of the chloride of iron and chromium with sodium silicate. Time of gelation is minimum at a certain p_H which shifts towards the acidic side with lowering in the concentration of the metathetic product. The gelation tendency is ascribed to free silica present in it. At high concentration of the metallic chlorides no gelation is possible due to the high peptising capacity of trivalent iron and chromium.

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Zusammenfassung Wie beim Kiesels?ure-Gel hat die Wasserstoffionenkonzentration gro?en Einflu? auf die Gelatinierung der Reaktionsprodukte von Natriumsilikat mit Eisen- und Chromchlorid. Die Erstarrungszeit besitzt für ein bestimmtes p_H ein Minimum, dessen Lage mit abnehmender Konzentration des Reaktionsproduktes nach der S?ureseite wandert. Die Gelatinierungstendenz wird der anwesenden freien Kiesels?ure zugeschrieben. Bei hohen Konzentrationen von Metallchloriden ist keine Gelatinierung m?glich infolge der hohen Peptisierungskraft von dreiwertigem Eisen und Chrom.

     

Ultrasound and microwave activated preparation of ZrO2-pillared clay composite: catalytic activity for selective, solventless acylation of 1,n-diols

We herein report for the first time, a new and efficient method using ultrasonic activation for intercalation by ion exchange and microwave heating for formation of zirconium polyoxycationic species in the preparation of ZrO₂-pillared clay composite with improved physico-chemical properties and significant reduction in processing time. Acetic anhydride under solventless conditions with microwave irradiation in the presence of ZrO₂-pillared clay was used for the mono-acylation of diols and alcohols in very good yield.     

Synthesis,characterization and structural assessment of nitrato,chloro, bromo,perchlorato, thiocyanato and sulphato mono-(benzoin thiosemicarbazonato) copper(II) complexes

Summary Some copper(II) complexes of the type Cu(HL)X·nH₂O (where H₂L = benzoin thiosemicarbazone; X=NO₃; Cl, Br, SCN, ClO₄ or 1/2SO₄; n=O–2) have been prepared and characterized. All complexes have tetragonally distorted octahedral stereochemistry except the sulphatocomplex which is square pyramidal. The i.r. spectra reveal that HL acts as a monobasic tridentate ligand coordinating through the azine group nitrogen atom, thiocarbonyl sulphur atom and hydroxylic oxygen atom while NO₃, Cl, Br and ClO₄ act as terminal monodentate ligands and SCN and SO₄ act as bidentate bridging ligands. The polycrystalline e.s.r. spectra suggest tetragonal symmetry for the copper(II) ion, involving a dx ²–y² ground state.     

Iodide catalyzed synthesis of 2-aminobenzoxazoles via oxidative cyclodesulfurization of phenolic thioureas with hydrogen peroxide

A convenient and efficient oxidative cyclodesulfurization of o-phenolic thioureas to 2-aminobenzoxazoles employing TBAI (tetrabutylammonium iodide)/H₂O₂ catalyst/reagent system is reported. The protocol utilizes and offers a number of desired features such as metal-free, base-free, simple operation, room temperature, low cost catalyst/reagent, no need for anhydrous and inert conditions. The approach is also applicable to a one-pot synthesis of 2-aminobenzoxazoles in an excellent yield starting directly from o-aminophenols and aryl isothiocyanates.     

Melt densification of radioactive plastic wastes

Summary Volume reduction studies were carried out on low level radioactive plastic wastes containing polyethylene, PVC and neoprene by melt densification. The optimized temperature for melting of plastics was between 170 and 180 °C. Based on laboratory scale studies. Plant scale studies were planned and conducted. The volume reduction factors obtained were around 30, which was 6-10 times higher than that of the conventional compaction process. Thermogravimetry and infrared spectroscopy were used to investigate the thermal and structural properties of the given materials. The effect of the presence of salts like potassium permanganate and hydrazine sulphate on the thermal properties of the materials was also evaluated. Leaching studies were also performed on melt-densified specimens in the laboratory. The average leach index was observed to be around 9, which was higher than the minimum stipulated value.