Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Population & Thin film. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Efficient and Stereoselective Nitration of Mono- and Disubstituted Olefins with AgNO2 and TEMPO

Abstract: Nitroolefin is a common and versatile reagent Its synthesis from olefin is generally limited by the formation of mixture of cis and trans compounds Here we report that silver nitrite (AgNO2) along with TEMPO can promote the regio- and stereoselective nitration of a broad range of olefins This work discloses a new and efficient approach wherein starting from olefin, nitroalkane radical formation and subsequent transformations lead to the desired nitroolefin in a stereoselective manner

Weakening of Indian Summer Monsoon Rainfall due to Changes in Land Use Land Cover.

Abstract: Weakening of Indian summer monsoon rainfall (ISMR) is traditionally linked with large-scale perturbations and circulations. However, the impacts of local changes in land use and land cover (LULC) on ISMR have yet to be explored. Here, we analyzed this topic using the regional Weather Research and Forecasting model with European Center for Medium range Weather Forecast (ECMWF) reanalysis data for the years 2000–2010 as a boundary condition and with LULC data from 1987 and 2005. The differences in LULC between 1987 and 2005 showed deforestation with conversion of forest land to crop land, though the magnitude of such conversion is uncertain because of the coarse resolution of satellite images and use of differential sources and methods for data extraction. We performed a sensitivity analysis to understand the impacts of large-scale deforestation in India on monsoon precipitation and found such impacts are similar to the observed changes in terms of spatial patterns and magnitude. We found that deforestation results in weakening of the ISMR because of the decrease in evapotranspiration and subsequent decrease in the recycled component of precipitation.

Spin gapless semiconducting behavior in equiatomic quaternary CoFeMnSi Heusler alloy

Abstract: In this paper, we report the signature of spin gapless semiconductor (SGS) in CoFeMnSi that belongs to the Heusler family. SGS is a new class of magnetic semiconductors which have a band gap for one spin subband and zero band gap for the other, and thus are useful for tunable spin transport based applications. We show various experimental evidences for SGS behavior in CoFeMnSi by carefully carrying out the transport and spin-polarization measurements. SGS behavior is also confirmed by first-principles band-structure calculations. The most stable configuration obtained by the theoretical calculation is verified by experiment. The alloy is found to crystallize in the cubic Heusler structure (LiMgPdSn type) with some amount of disorder and has a saturation magnetization of $3.7\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{B}/\mathrm{f}.\mathrm{u}.$ and Curie temperature of \ensuremath{\sim}620 K. The saturation magnetization is found to follow the Slater-Pauling behavior, one of the prerequisites for SGS. Nearly-temperature-independent carrier concentration and electrical conductivity are observed from 5 to 300 K. An anomalous Hall coefficient of 162 S/cm is obtained at 5 K. Point contact Andreev reflection data have yielded the current spin-polarization value of 0.64, which is found to be robust against the structural disorder. All these properties strongly suggest SGS nature of the alloy, which is quite promising for the spintronic applications such as spin injection as it can bridge the gap between the contrasting behaviors of half-metallic ferromagnets and semiconductors.