Temperature and pressure variation of the recoilless fraction for119Sn:Pd Mössbauer system

The variation of the recoilless fraction ‘f’ as a function of temperature and pressure of¹¹⁹Sn embedded as a dilute impurity in palladium (Pd) host has been calculated after incorporating the changes in the force constant and mass at the impurity site using Debye model and phonon frequency spectrum (pfs). The comparison of the results have been made with the available experimental values.     

Synthesis and stereochemistry of 2-arylperhydrocyclopenta[b]pyridin-1-ols, 8-azaestrone fragments

Different stereoisomers of 2-arylperhydrocyclopenta[b]pyridin-1-ols, which form structural motifs of 8-azaestrone, were prepared via reductive cyclization from mono-oximes derived from 1,5-diketones, by using sodium borohydride and acetic acid in THF at reflux.     

Synthesis and electrochemical studies of charge-transfer complexes of thiazolidine-2,4-dione with σ and π acceptors

In the present work, we report the synthesis and characterization of novel charge-transfer complexes of thiazolidine-2,4-dione (TZD) with sigma acceptor (iodine) and pi acceptors (chloranil, dichlorodicyanoquinone, picric acid and duraquinone). We also evaluated their thermal and electrochemical properties and we conclude that these complexes are frequency dependent. Charge-transfer complex between thiazolidine-2,4-dione and iodine give best conductivity. In conclusion, complex with sigma acceptors are more conducting than with pi acceptors.     

Fragment angular momenta in low and medium energy fission of242Pu

Independent isomeric yield ratios of¹²⁸Sb were determined radiochemically in the thermal neutron induced fission of²⁴¹Pu and 34 MeV alpha particle induced fission of²³⁸U, both involving the same compound nucleus (²⁴²Pu). Fragment angular momenta estimated from the measured isomer ratios using the statistical model analysis showed significantly larger fragment angular momenta in the medium energy fissioning system compared to the low energy fissioning system. This has been attributed to the effect of higher excitation energy and angular momentum in the entrance channel leading to increased fragment temperature, moments of inertia and angular velocity. An attempt was made to calculate the fragment angular momentum in the medium energy fission using the Fermi gas model for the fissioning nucleus, taking into account the multichance fission, saddle shapes of the fissioning nuclei and the angular velocity components of the fissioning nuclei both along and orthogonal to the fission axis. The calculated angular momenta agree well with the experimental results.     

Search for anomalous interaction mean free paths of charge, 2≦Z≦18 projectile fragments in emulsions exposed to 1.8 A GeV40Ar ions

⁴⁰Ar-emulsion interactions are studied, to investigate the question of anomalons, in twoG- 5 emulsion stacks. In about 4600 primary interactions, projectile fragments of Z≧2 for all generations have been followed until they interact or leave the stack. After careful estimation of charges of these fragments, variation of their mean free paths is studied as a function of distance from the preceding interaction. Generation effect,N _h dependence and production angle effect are investigated. In addition multi-chain events are analysed separately. Our results do not show anomalons at the 6% level and are consistent with non-occurrence of anomalons. However, this experiment is not sensitive enough to rule out anomalons (with a mfp of the order of 2 to 3 cm) produced at about 1% (or less) level.     

Heterogeneous catalysis by new bead‐shaped polymer‐supported multisite phase transfer catalysts

Three different new insoluble bead‐shaped polymer‐supported multisite phase transfer catalysts containing two, four and six active sites have been prepared and characterized by FTIR, TGA, [chloride ion] and SEM analyses. The presence of number of active sites in each catalyst and their corresponding catalytic ability were studied by determining pseudo‐first order rate constants for C‐alkylation of phenylacetonitrile (PAN) and four different substituted PAN as the substrate using a low concentration of NaOH (25% w/w) at 50 °C. The observed rate constants were compared with rate constants of same reactions catalyzed by single‐site catalyst under identical reaction conditions. From comparative study, the efficiency of catalysts were found to be in the order six‐site>four‐site>two‐site>single‐site thus confirming number of active sites in each catalyst. Further, the detailed kinetic profile of C‐alkylation of PAN has been investigated using the superior six‐site catalyst by varying stirring speed, [substrate], [catalyst], [NaOH], and temperature. Based on the observed kinetic and activation parameters, an interfacial mechanism was proposed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 771–785, 2009     

Synthesis,characterization, DNA binding and nuclease activity of binuclear copper(II) complexes of cuminaldehyde thiosemicarbazones

Binuclear copper(II) complexes of thiosemicarbazones derived from cuminaldehyde (p-isopropyl benzaldehyde) and substituted thiosemicarbazides NH₂NHC(S)NHR, where R = H, Me, Et or Ph have been synthesized and characterized. The ESR indicates that the dissociation of dimeric complex into mononuclear [Cu(L)Cl(DMSO)₃] units in polar solvents like DMSO, where L = monoanionic thiosemicarbazone. The molecular ion peak in the LC-MS coincides with the formula weight of the complexes. The absorption titration studies revealed that each of these complexes is an avid binder to calf thymus-DNA. The apparent binding constants are in the order of 10⁷–10⁸ M⁻¹. The nucleolytic cleavage activities of the ligands and their complexes were assayed on pUC18 plasmid DNA using gel electrophoresis in the presence and absence of H₂O₂. The ligands showed increased nuclease activity when administered as copper complexes. All these copper(II) complexes behave as an efficient chemical nucleases with hydrogen peroxide activation. These studies revealed that the complexes exhibit both oxidative and hydrolytic chemistry in DNA cleavage.     

Automatic off/on-line preconcentration for ICP-OES: Powerful instrumentation for water analysis

Automated preconcentration techniques for off/on-line determination with ICP-OES have been developed for various metal ions of environmental interest. Preconcentration studies were performed on two different types of chemically bonded chelating ion-exchangers, namely EDTrA-cellulose (iminoacetate groups) and HSO₃ · oxine-cellulose. Enrichment studies were carried out at various preconcentration factors and also at different loadings.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Dye-sensitized solar cells concocted with dyes extracted from fresh and dried leaves of Henna using different solvents

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