Experimental Simulation on Separation of Alpha-Particle Induced Rhenium Isotopes from Bulk Tantalum

Trace level tantalum and rhenium, ¹⁸²Ta and ^186,188Re, have been separated with liquid anion exchanger, TOA from HNO₃ medium. The feasibility of the separation process has also been verified for the separation of trace level rhenium from bulk or macro quantity of tantalum. The developed radiochemical scheme will be useful for the separation of carrier-free rhenium radionuclides produced in -particle activated matrix target.     

Nafion perfluorinated membranes in fuel cells

Increasing global energy requirements, localized power issues and the need for less environmental impact are now providing even more incentive to make fuel cells a reality. A number of technologies have been demonstrated to be feasible for generation of power from fuel cells over the last several years. Proton exchange membranes (PEM) have emerged as an essential factor in the technology race. DuPont has supplied Nafion^® perfluorinated membranes in fuel cells for space travel for more than 35 years and they have played an integral part in the success of recent work in portable, stationary and transportation applications. The basis for PEM fuel cell emergence and DuPont technology utilization will be discussed.     

Construction of characteristic polynomial of reciprocal graphs from the number of pendant vertices

A method for construction of the characteristic polynomial (CP) coefficients of the three classes of reciprocal graphs, viz., L_n + n(p), C_n + n(p), and K_1,n?1 + n(p), has been developed that requires only the value of n. The working formulas have been expressed in matrix product form, computer programs for which can easily be developed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Comparison of <Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis> isocitrate dehydrogenases (ICD-1 and ICD-2) reveals differences in coenzyme affinity,oligomeric state,pH tolerance and phylogenetic affiliation

Background  

M.tb icd-1 and M.tb icd-2, have been identified in the Mycobacterium tuberculosis genome as probable isocitrate dehydrogenase (ICD) genes. Earlier we demonstrated that the two isoforms can elicit B cell response in TB patients and significantly differentiate TB infected population from healthy, BCG-vaccinated controls. Even though immunoassays suggest that these proteins are closely related in terms of antigenic determinants, we now show that M.tb icd-1 and M.tb icd-2 code for functional energy cycle enzymes and document the differences in their biochemical properties, oligomeric assembly and phylogenetic affiliation.     

Diphenic acid as an analytical reagent

Summary Diphenic acid behaves as a selective reagent for the estimation of thorium in presence of phosphate, arsenate, molybdate, alkaline, earths, copper, cadmium, lead, bismuth, tin, aluminium, chromium, nickel, cobalt, zinc, manganese, magnesium and palladium. Thorium can be successfully separated from the cerite earths by the reagent from solutions having thoria: earth oxide ratio 126 by single precipitation and by double precipitation when the above ratio is 144. The reagent can separate thorium from solutions having ThO₂U₃O₈ ratio upto 180 by double precipitation. The metal can also be recovered from monazite sands.Thanks are expressed hereby to Dr. A. K. Ghosal, Principal, Darjeeling Government College and Dr. A. K. Mukherjee of Indian Association for the Cultivation of Science, Calcutta, for their kind encouragement and to the Government of India, Ministry of Natural Resources and Scientific Research for a gift of Indian Monazite for analysis.     

Re(III)Cl(3)] core complexes with bifunctional single amino acid chelates

The reactions of the Re(V) starting material [ReO(PPh(3))(2)Cl(3)] with ligands of the type XN(Y)Z [X = Y = 2-pyridylmethyl, Z = -CH(2)CO(2)Et (L(1)Et), -CH(2)CH(2)CO(2)Et (L(2)Et), -CH(2)CH(2)CH(2)CH(2)CH(NHCO(2)Bu(t))CO(2)H (L(3)H); X = 2-pyridylmethyl, Y = 2-(1-methylimidazolyl)methyl, Z = -CH(2)CO(2)Et (L(4)Et)] yielded the Re(III) trichloride complexes of the type [ReCl(3)(L(n)R)]. The complexes are mononuclear, paramagnetic species with a facial geometry of the chloride ligands. The nitrogen donors of the tridentate L(n)()R ligands complete the distorted octahedral coordination spheres of the complexes. Crystal data: [ReCl(3)(L(1)Et)] (1), monoclinic, C2/m, a = 16.088(3) A, b = 9.980(2) A, c = 12.829(2) A, beta = 91.384(3) degrees, Z = 4, D(calc) = 1.967 g/cm(-)(3); [ReCl(3)(L(4)Et)] (4), monoclinic, C2/c, a = 22.880(1) A, b = 7.4926(4) A, c = 22.560(1) A, beta = 94.186(1) degrees, Z = 8, D(calc) = 2.001 g/cm(-3).     

Synthesis of 4'-(2,6,6-trimethyl -2-cyclohexen-1-yl) -3'-buten-2'-ketoxime-N-O-alkyl ethers

4'-(2,6,6-Trimethyl-2-cyclohexen-1-yl)-3'-buten-2'-ketoxime-N-O-alkyl ethers have been synthesized starting from alpha-ionone, separated into their E and Z isomers and characterized on the basis of (1)H-NMR and mass spectra.     

Direct spectrophotometric determination of zirconium with spadns

A method has been developed for the spcctrophotometric determination of microgram amounts of zirconium using SPADNS as the colour-forming agent. The method is sensitive and quantities as small as 0.07 γ zirconium can be estimated in 25 ml of final volume. A standard calibration curve lias been prepared; it conforms to Beer's law. The stoichiometric composition of the coloured complex has been determined spcctrophotomctrically by adopting the 'slope ratio method'.     

Electronic spectra of paramethoxy benzyl alcohol and parachloro benzyl cyanide

The electronic absorption spectra of paramethoxy benzyl alcohol (pmba) and parachloro benzyl cyanide (pcbc) are described. The broad features of the spectra of the molecules are consistent with allowed transition forC _2v symmetry. However, the solid state and glass matrix spectra of pmba at 77K indicate possible deviation from planarity in the structure of the molecule. In pcbc, it is pointed out that intensity borrowing may be responsible for the large intensity of the vibrationally-induced part of the spectra, in which non-totally symmetric vibrations are excited.     

Proton transfer reaction of a new orthohydroxy Schiff base in some protic and aprotic solvents at room temperature and 77 K

The ground and excited state proton transfer reactions of a new orthohydroxy Schiff base, salicylidine-3,4,7-methyl amine (SMA) has been studied by means of absorption, emission and time resolved fluorescence spectroscopy in some polar protic and aprotic solvents at room temperature and 77K. The spectral behavior of SMA has been investigated both in neutral and basic conditions. The intramolecularly hydrogen bonded enol and zwitterion have been detected in pure methanol and ethanol, the anion is detected in basic condition. At 77K, SMA shows phosphorescence in pure methanol and ethanol. From nanosecond measurements and quantum yields of fluorescence, we have estimated the decay rates of proton transfer reaction in methanol and ethanol.