Selective oxidation of styrene to benzaldehyde using soft BaFe2O4 synthesized by citrate gel combustion method

BaFe2O4 spinel type catalyst is synthesized by a simple and inexpensive one-step citrate gel combustion method, the only method to synthesize soft ferrite other than the Pechini method reported earlier. The precursor and oxide are well characterized by various techniques such as thermogravimetry–differential thermal analysis, Fourier transform IR, X-ray diffraction, X-ray florescence and scanning electron microscopy. The SEM images confirm coralloid morphology of BaFe2O4 catalyst. BaFe2O4 catalyst shows high activity for styrene oxidation in the presence of H2O2 (30%) as an oxidant in acetone as solvent. Gas chromatography and mass spectroscopy analysis revealed that, conversion of styrene takes place selectively to benzaldehyde up to 88.5 mol% as major product with 39.9% yield. The optimization and effect of various reaction conditions on styrene conversion and product distribution were also studied. Ultrasonication exposes active sites on the surface of catalyst and breaks the hydrophobic cluster to make the reagent available. Better catalytic activity of BaFe2O4 is due to different site preference energies of individual ions which depend on the ionic size of barium (1.35 Å) and iron (0.67 Å), the size of interstices and temperature. The catalyst can be reused with marginal loss in activity

Spin Transport and Magnetic Correlation Parameters for Graphene-like Nanocarbon Sheets Doped with Nitrogen

Globally, graphene magnetism has captivated the attention of researchers in recent years. To obtain magnetic ordering, irregularities in the carbon network, like defects, adatoms, etc., are essential. Herein, we report on spin transport and magnetic correlations in graphene-like nanocarbon sheets (GNCs) that were doped with nitrogen by use of tetrakis­(dimethylamino)­ethylene (TDAE). The spin transport measurements, performed by electron spin resonance technique, showed that both spin–spin and spin–lattice relaxation times are increased by nitrogen doping. The magnetic correlations, measured on a vibrating sample magnetometer, showed that ordering parameters are reduced for nitrogen-loaded GNCs. Chemical analysis, carried out via electron spectroscopy, revealed that nitrogen atoms exchange couples electron-to-hole with the carbon network. Analysis of <i>I</i>–<i>V</i> measurements showed that higher-order resistance is appreciably decreased for nitrogen-doped GNCs. The observed decrease is due to an increase in nonbonding states having small local density. After doping, states in this region may be localized π spin populated around the doped region. By and large, the approximately 20% magnetization that exists in GNCs is found to be reduced to 5% by introduction of nitrogen

Development of Decadal (1985–1995–2005) Land Use and Land Cover Database for India

India has experienced significant Land-Use and Land-Cover Change (LULCC) over the past few decades. In this context, careful observation and mapping of LULCC using satellite data of high to medium spatial resolution is crucial for understanding the long-term usage patterns of natural resources and facilitating sustainable management to plan, monitor and evaluate development. The present study utilizes the satellite images to generate national level LULC maps at decadal intervals for 1985, 1995 and 2005 using onscreen visual interpretation techniques with minimum mapping unit of 2.5 hectares. These maps follow the classification scheme of the International Geosphere Biosphere Programme (IGBP) to ensure compatibility with other global/regional LULC datasets for comparison and integration. Our LULC maps with more than 90% overall accuracy highlight the changes prominent at regional level, i.e., loss of forest cover in central and northeast India, increase of cropland area in Western India, growth of peri-urban area, and relative increase in plantations. We also found spatial correlation between the cropping area and precipitation, which in turn confirms the monsoon dependent agriculture system in the country. On comparison with the existing global LULC products (GlobCover and MODIS), it can be concluded that our dataset has captured the maximum cumulative patch diversity frequency indicating the detailed representation that can be attributed to the on-screen visual interpretation technique. Comparisons with global LULC products (GlobCover and MODIS) show that our dataset captures maximum landscape diversity, which is partly attributable to the on-screen visual interpretation techniques. We advocate the utility of this database for national and regional studies on land dynamics and climate change research. The database would be updated to 2015 as a continuing effort of this study