The Role of Vanadia for the Selective Oxidation of Benzyl Alcohol over Heteropolymolybdate Supported on Alumina

A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption,X-ray diffraction,temperature-programmed reduction,in situ laser Raman spectroscopy,UV-Vis diffused reflectance spectroscopy,scanning electron microscopy,and temperature-programmed desorption of NH3 techniques.Their catalytic activities were evaluated for the vapor phase aerobic oxidation of benzyl alcohol.The catalysts exhibited high catalytic activity and the conversion of benzyl alcohol depended on the vanadia content while the catalyst with 15 wt％ V2O5 content showed optimum activity.The characterization results suggest the presence of well-dispersed V2O5 and partially disintegrated Keggin ions of MPA on the support.In situ Raman studies showed a reduced Mo(IV) species when the catalysts were calcined at high temperatures.The high oxidation activity of the catalysts is related to the synergistic effect between MPA and V2O5.     

Spectroscopic studies of atmospheric interest on NO and NO

In recent years, high-resolution photoelectron spectroscopy and ab initio calculations have considerably revised and enlarged the understanding of the electronic structure of the NO and NO⁺ molecules. The experimental potential energy curves for the different electronic states of atmospheric interest molecules like NO and NO⁺ are constructed by using the Rydberg-Klein-Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting technique using the five parameter Hulburt-Hirschfelder (H-H) function. The estimated dissociation energies are 6.381 and 10.693 eV for NO and NO⁺, respectively. These values are in good agreement with the literature values. The r-centroids and Franck-Condon factors (FC Factors) for the band system of B²Π_r-X²Π of NO and a³Σ⁺-X¹Σ⁺, A¹Π-X¹Σ⁺ of NO⁺ molecules have been calculated employing an approximate analytical methods of Jarmain and Fraser, and Nicholls and Jarmain. The absence of the bands in these systems is explained.     

Purification of 89Sr source obtained from 89Y(n,p) 89Sr by ion-exchange chromatography using tri-sodium tri-meta phosphate (SMP) as eluant

⁸⁹Sr was produced via ⁸⁹Y(n, p) ⁸⁹Sr using yttria as target in Fast Breeder Test Reactor (FBTR), Kalpakkam, India. A radiochemical procedure has been developed for the separation of bulk yttrium using TBP by solvent extraction followed by purification of ⁸⁹Sr source by ion exchange chromatography using the cation exchange resin Dowex 50WX8 (100–200 mesh) and nitric acid of variable molarity as eluant. The present study establishes the purification of ⁸⁹Sr source from the other radionuclidic impurities like ⁸⁸Y, ⁶⁵Zn, ⁵⁴Mn, ⁶⁰Co, ⁸⁶Rb, ¹⁹²Ir, ¹⁰³Ru, ¹¹³Sn, ¹³⁹Ce, ¹⁶⁰Tb, ¹⁵⁴Eu etc. produced during the irradiation of yttria by using the complexing agent tri-sodium tri-meta phosphate (SMP) in nitric acid medium instead of nitric acid alone as an eluant. The purification was achieved by using 0.1 M SMP as complexing agent which was optimized based on the distribution ratio data and final elution of Sr fraction was obtained in nitric acid medium. This resulted into a faster purification of ⁸⁹Sr source in a smaller volume of eluant. Purity of Sr source from the cross contamination of the complexing agent SMP was also ensured.     

Photoinduced electron transfer between anionic fluorophores and methyl viologen in homogeneous and microheterogeneous media

The rate and extent of photoinduced electron transfer change significantly as a result of confinement in nanovolumes. Study of such processes is an active area of research in physical chemistry. The effect is most interesting when the molecules that participate in PET are charged. In the present article, the modulation of PET has been studied for two anionic fluorophores: Lucifer Yellow CH and chlorin p₆ with Methylviologen dication. PET, manifested in the quenching of fluorescence of the fluorophores, has been modulated by incorporating the molecules in organized assemblies like micelles, reverse micelles and supramolecular hosts. The dynamics of the process has been monitored in the femtosecond to nanosecond timescale. The modulation of the electron transfer has been found to be occurring mainly due to the disruption of contact ion pairs formed between the fluorophores and the quencher.     

Studies directed towards the total synthesis of koshikalide: stereoselective synthesis of the macrocyclic core

The stereoselective synthesis of the macrolactone core of the natural product koshikalide is described. Starting with readily available 1,4-butanediol and malic acid as synthons, our synthetic strategy involved the reiterative application of Gilman’s reaction, Swern oxidation and Sharpless asymmetric epoxidation to establish the required stereocentres. Other key steps in the synthesis include Negishi cross coupling and Horner–Wadsworth–Emmons (HWE) reactions for construction of the main fragments. The 14-membered lactone ring was prepared by a selective Mitsunobu macrolactonization approach.     

Isobutylene‐rich macromonomers: Dynamics and yields of peroxide‐initiated crosslinking

New isobutylene‐rich elastomers bearing multiple pendant styrenic, acrylic, maleimidic, vinylic, and allylic functional groups have been prepared and examined in the context of peroxide‐initiated crosslinking. Halide displacement from brominated poly(isobutylene‐co‐isoprene) (BIIR) by the requisite carboxylate nucleophiles in homogeneous toluene solutions provide the desired esters in quantitative yield without complications from dehydrohalogenation or premature crosslinking. Heating the resulting macromonomers with dicumyl peroxide to 160 °C under solvent‐free conditions gives thermoset derivatives, with reaction rates and yields depending markedly on functional group structure. In general, high cure extents can only be achieved using highly reactive pendant functional groups, owing to the competitive balance between crosslinking through C?C oligomerization, and degradation through β‐scission of backbone macroradical intermediates. Independent control of crosslinking rates and cure extents is gained through the use of nitroxyl radical traps bearing acrylate functionality. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 123–132     

Implicit large eddy simulation using the high‐order correction procedure via reconstruction scheme

We investigate implicit large eddy simulation of the Taylor–Green vortex, Comte‐Bellot–Corrsin experiment, turbulent channel flow and transitional and turbulent flow over an SD7003 airfoil using the high‐order unstructured correction procedure via reconstruction (CPR) scheme, also known as the flux reconstruction scheme. We employ P1 (second‐order) to P5 (sixth‐order) spatial discretizations. Results show that the CPR scheme can accurately predict turbulent flows without the addition of a sub‐grid scale model. Numerical dissipation, concentrated at the smallest resolved scales, is found to filter high‐frequency content from the solution. In addition, the high‐order schemes are found to be more accurate than the low‐order schemes on a per degree of freedom basis for the canonical test cases we consider. These results motivate the further investigation and use of the CPR scheme for simulating turbulent flows. Copyright © 2016 John Wiley & Sons, Ltd.