Indian Institutes of Science Education and Research

About: Indian Institutes of Science Education and Research is a based out in . It is known for research contribution in the topics: Gravitational wave & LIGO. The organization has 584 authors who have published 731 publications receiving 40599 citations. The organization is also known as: IISERs.

Observation of a large magnetocaloric effect in a 2D Gd(III)-based coordination polymer

Abstract: A new 2D Gd(III)-based coordination polymer has close to the highest cryogenic magnetocaloric effect of any MOF reported so far. The experimental results reveal its structural features and magnetic properties.

A combined low-radio frequency/X-ray study of galaxy groups I. Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz

Abstract: We present new Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz of 18 X-ray bright galaxy groups. These observations are part of an extended project, presented here and in future papers, which combines low-frequency radio and X-ray data to investigate the interaction between central active galactic nuclei (AGN) and the intra-group medium (IGM). The radio images show a very diverse population of group-central radio sources, varying widely in size, power, morphology and spectral index. Comparison of the radio images with Chandra and XMM-Newton X-ray images shows that groups with significant substructure in the X-ray band and marginal radio emission at >= 1 GHz host low-frequency radio structures that correlate with substructures in IGM. Radio-filled X-ray cavities, the most evident form of AGN/IGM interaction in our sample, are found in half of the systems, and are typically associated with small, low- or mid-power double radio sources. Two systems, NGC5044 and NGC4636, possess multiple cavities, which are isotropically distributed around the group center, possibly due to group weather. In other systems the radio/X-ray correlations are less evident. However, the AGN/IGM interaction can manifest itself through the effects of the high-pressure medium on the morphology, spectral properties and evolution of the radio-emitting plasma. In particular, the IGM can confine fading radio lobes in old/dying radio galaxies and prevent them from dissipating quickly. Evidence for radio emission produced by former outbursts that coexist with current activity is found in six groups of the sample.

Directed search for continuous gravitational waves from the Galactic center

Abstract: We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic Center region, performed on two years of data from LIGO's fifth science run from two LIGO detectors. The search uses a semi-coherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first order spindown values down to -7.86 x 10^-8 Hz/s at the highest frequency. No gravitational waves were detected. We place 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic Center. Placing 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic Center, we reach ~3.35x10^-25 for frequencies near 150 Hz. These upper limits are the most constraining to date for a large-parameter-space search for continuous gravitational wave signals.

Activated Graphene-Derived Porous Carbon with Exceptional Gas Adsorption Properties

Abstract: Designing nanoporous materials with high surface area, large porosity, superior structural stability and amenability to various processing conditions, is important to meet the commercial demands of large-scale reversible gas storage systems. Here, we demonstrate a simple approach to synthesize highly porous activated graphene-derived carbon (a-GDC), with ultra-high surface area (∼3240 m 2 g −1 ) and enhanced porosity characteristics, from thermally exfoliated graphite oxide (TEGO), through an efficient and finely controlled KOH chemical activation process. a-GDCs with highly interconnected network of micro- and mesopores show excellent gas storage properties for CO 2 , CH 4 and H 2 , with exceptionally high adsorption capacities and fast sorption kinetics, superior to other high surface area nanoporous carbons. The results show great promise for the development of efficient carbon based sorbents for effective CO 2 capture and energy storage applications.

Tune-out wavelengths of alkali-metal atoms and their applications

Abstract: Using first-principles calculations, we identify ``tune-out'' optical wavelengths, ${\ensuremath{\lambda}}_{\mathrm{zero}}$, for which the ground-state frequency-dependent polarizabilities of alkali-metal atoms vanish. Our approach uses high-precision, relativistic all-order method in which all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. We discuss the use of tune-out wavelengths for sympathetic cooling in two-species mixtures of alkali metals with group II and other elements of interest. Special cases in which these wavelengths coincide with strong resonance transitions in a target system are identified.