Class Numbers of CM-Fields with Solvable Normal Closure

Stark conjectured that given a positive integer h, there are only a finite number of CM-fields L with class number equal to h. We prove this conjecture for fields L of degree 6 whose normal closure is solvable.     

Spectrophotometric determination of the oxygen to uranium ratio in uranium oxides based on dissolution in sulphuric acid

The oxygen to uranium ratio in uranium oxides such as U(3)O(8), UO(2+x) powders and UO(2) fuel pellets has been determined by a new spectrophotometric method. The method can be used for determination of O/U ratio in UO(2) pellets and powders on a routine basis. In the described method, uranium oxides in the powder form are dissolved in 2M sulphuric acid containing a few drops of HF. The concentrations of U(IV) and U(VI) are directly determined by means of the absorbances of these species at different wavelengths. For determination of the O/U ratio in U(3)O(8) powder samples, 630 and 310 nm are the wavelengths chosen for U(IV) and U(VI), respectively. For UO(2+x) powder, where the O/U ratio lies between 2.04 to 2.15, U(IV) and U(VI) are determined at 630 and 300 nm respectively, whereas for UO(2) fuel pellets, where the O/U ratio is less than 2.01, 535 and 285 nm are used. The molar absorptivity of U(IV) at 630 and 535 nm is 21.4 and 6.8 l.mole(-1).cm(-1) and that of U(VI) at 310, 300 and 285 nm is 178.1, 278.6 and 585 l.mole(-1).cm(-1), respectively. Standard deviations of +/-0.002 O/U ratio units for pellets and +/-0.004 O/U ratio units for powders have been achieved.     

Alignment studies on p-ethoxy phenyl azophenyl butyrate in the presence of electric and magnetic fields

Dielectric permittivity studies on the nematic liquid crystal p-(ethoxy phenyl azophenyl) butyrate were carried out at 1 MHz. The effect of parallel and perpendicular magnetic fields on the alignment of the molecules was studied. The threshold voltage for domain formation in the presence of a magnetic field is estimated.     

In situ nucleophilic substitution reaction of N,N-dialkylaminoethyl-2-chlorides monitored by gas chromatography/mass spectrometry

The detection and identification of degradation products of scheduled chemicals, which are characteristic markers of Chemical Warfare agents (CWAs), plays a key role in verification analysis. Identification of such non-scheduled but specific markers of CWAs helps in deciphering the kind of agent that was present in the sample submitted for off-site analysis. This paper describes the stability of N,N-dialkylaminoethyl-2-chlorides, which are precursors for highly toxic chemicals like VX, in different solvents. These compounds are stable in chloroform, acetonitrile, hexane and dichloromethane but tend to undergo in situ nucleophilic substitution reaction in the presence of alcohols giving the corresponding alkyl ether. The study shows that N,N-dialkylaminoethyl alkyl ethers can be used as markers of N,N-dialkylaminoethyl-2-chlorides. A detailed degradation study of these compounds in the presence of alcohols was carried out and it was found that the reaction follows pseudo-first order kinetics. Electron ionization mass spectral data for the methyl ethers of all the compounds are briefly discussed.     

Magnetically Recyclable Nano-Fe2O3-Catalyzed Chemoselective Synthesis and Antioxidant Activity of Diethyl (3-((5-Aryl-1H-1,2,4-triazol-3-yl)thio)propyl)phosphonates

An efficient, green, and chemoselective S-alkylation of 5-aryl-1H-1,2,4-triazole-3-thiones with diethyl (3-bromopropyl)phosphonate in water, catalyzed by nano-Fe₂O₃ under ligand- and base-free conditions, is reported. Clean reaction, less expensive catalyst, excellent yields, and easy workup are the advantages of the present method. The catalyst can be easily collected by a magnet and recycled without significant loss in catalytic activity. The newly synthesized compounds were screened for their antioxidant property by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay. The majority of the compounds exhibited good antioxidant activity.     

Synthesis of 6-vinyl and 5-vinylproline analogues of ascomycin

6-Vinyl (12) and (5R)- and (5S)-vinylproline (18, 19) analogues of ascomycin are synthesised starting from the known suitably protected (6S)-methoxy-9-hydroxy derivative (4) of ascomycin. The strategy involves hydrolytic cleavage of the C_ε-N bond of the pipecolic acid moiety, extension of the amino acid side chain by two or one carbon units, functional group manipulations, Pd-catalysed reinstallation of the C_ε-N or C_δ-N bonds, followed by deprotection and oxidation.     

Determination of carbonate, bicarbonate and phosphate in uranium leach liquors containing KMnO(4) as oxidant

A simple, rapid and economic method has been developed for the reduction of potassium permanganate in alkaline carbonate uranium leach liquors to a colourless solution. The pink colour of permanganate, if not reduced, seriously impedes the determination of carbonate, bicarbonate and phosphate by titrimetry and spectrophotometry. Out of 17 reductants investigated, commercial sugar has been found to be the most effective, rapid, simple and interference free for further estimations. To the best of the authors' knowledge, this is the first time that sugar as a reductant has been made use of in analytical investigations.     

Spectrophotometric determination of ascorbic acid in pharmaceutical preparations and fruit juices

Conditions were established for the determination of ascorbic acid using phsophovanadotungstic acid as reagent. The method was applied to the determination of ascorbic acid in pure form, pharmaceutical preparations and fruit juices. The method is sensitive (2-24 micrograms ml-1 of ascorbic acid) and rapid and tolerates the presence of common ingredients usually found in fruit juices. The results obtained with the proposed method showed good agreement with those given by the standard method.     

Surfactant immobilized interlayer species bonded to montmorillonite as recyclable adsorbent for lead ions

Removal of lead ( Pb2+ ) ions from aqueous solution by adsorption onto surfactant-immobilized interlayer species bonded to montmorillonite clay (SIIS-clay) was investigated. Surfactant-immobilized interlayer chromate bound to clay (SIICr-clay) was prepared by treatment of montmorillonite clay with hexadecyltrimethylammonium (HDTMA) bromide followed by chromate adsorption at the intergallery framework of the clay. Experiments were carried out as a function of solution pH, solute concentration, and temperature (5-45 degrees C). The Dubinin-Kaganer-Radushkevich (DKR) model was adopted to describe the single-solute adsorption isotherms. Adsorption energy for lead ions on SIICr-clay computed from the DKR equation shows that a precipitation mechanism was operative. The thermodynamic parameters ( Delta G 0, Delta H 0, and Delta S 0) for lead ion adsorption on SIICr-clay were also determined from the temperature dependence. The kinetics of metal ion adsorption was examined and the first-order rate constant was finally evaluated. Adsorbed lead ions could be recovered completely on leaching with the disodium salt of ethylenediamine tetraacetic acid (EDTA) solution and the adsorbent was found to readsorb lead ions repeatedly after leaching. Thus, surfactant-modified smectite clays offer an effective method for designing a recyclable adsorbent for lead ions.     

Two new macrocyclic diaryl ether heptanoids from Boswellia ovalifoliolata

The stems of Boswellia ovalifoliolata BAL. & HENRY (Burseraceae) afforded two new macrocyclic diaryl ether heptanoids, ovalifoliolatin A (1) and B (2) together with three known compounds; acerogenin C (3), 3 alpha-hydroxyurs-12-ene (4), and sitost-4-en-3-one (5). The structures were established by means of spectroscopic analysis and compounds 1, 3-5 were evaluated for their antibacterial activity.