Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Catalysis & Excited state. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

WMAP constraints, supersymmetric dark matter, and implications for the direct detection of supersymmetry

Abstract: Recently WMAP has measured the cosmological parameters to a much greater accuracy We analyze the implications of this more precise measurement for supersymmetric dark matter and for the direct detection of supersymmetry at accelerators We consider MSUGRA including also the hyperbolic branch (HB) in the radiative breaking of the electroweak symmetry On the part of the hyperbolic branch where the lightest neutralino is dominantly a Higgsino rather than being mostly a B-ino, the relic density constraints are satisfied by coannihilation with the next lightest neutralino and the light chargino Including this branch the lightest neutralino mass satisfies ${m}_{{\ensuremath{\chi}}_{1}^{0}}l~1200\mathrm{GeV}$ for $\mathrm{tan}\ensuremath{\beta}l~50$ Constraints of $\stackrel{\ensuremath{\rightarrow}}{b}s+\ensuremath{\gamma},$ of ${g}_{\ensuremath{\mu}}\ensuremath{-}2,$ and of ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ are also analyzed It is shown that the neutralino-proton cross section in each case will fall within the reach of dark matter experiments The possibility for the direct detection of supersymmetry is discussed in the allowed regions of the parameter space consistent with WMAP constraints A brief discussion of the hyperbolic branch and focus point region (HB/FP) is also given

Structures and chemical properties of silicene: unlike graphene.

Abstract: The discovery of graphene and its remarkable and exotic properties have aroused interest in other elements and molecules that form 2D atomic layers, such as metal chalcogenides, transition metal oxides, boron nitride, silicon, and germanium. Silicene and germanene, the Si and Ge counterparts of graphene, have interesting fundamental physical properties with potential applications in technology. For example, researchers expect that silicene will be relatively easy to incorporate within existing silicon-based electronics.In this Account, we summarize the challenges and progress in the field of silicene research. Theoretical calculations have predicted that silicene possesses graphene-like properties such as massless Dirac fermions that carry charge and the quantum spin Hall effect. Researchers are actively exploring the physical and chemical properties of silicene and tailoring it for wide variety of applications.The symmetric buckling in each of the six-membered rings of silicene differentiates it from gra...

Small-molecule inhibitors reveal multiple strategies for Hedgehog pathway blockade

Abstract: Inappropriate activation of the Hedgehog (Hh) signaling pathway has been implicated in a diverse spectrum of cancers, and its pharmacological blockade has emerged as an anti-tumor strategy. While nearly all known Hh pathway antagonists target the transmembrane protein Smoothened (Smo), small molecules that suppress downstream effectors could more comprehensively remediate Hh pathway-dependent tumors. We report here four Hh pathway antagonists that are epistatic to the nucleocytoplasmic regulator Suppressor of Fused [Su(fu)], including two that can inhibit Hh target gene expression induced by overexpression of the Gli transcription factors. Each inhibitor has a unique mechanism of action, and their phenotypes reveal that Gli processing, Gli activation, and primary cilia formation are pharmacologically targetable. We further establish the ability of certain compounds to block the proliferation of cerebellar granule neuron precursors expressing an oncogenic form of Smo, and we demonstrate that Hh pathway inhibitors can have tissue-specific activities. These antagonists therefore constitute a valuable set of chemical tools for interrogating downstream Hh signaling mechanisms and for developing chemotherapies against Hh pathway-related cancers.

Surface Defect-Related Luminescence Properties of SnO2 Nanorods and Nanoparticles

Abstract: We demonstrate the surface defect-related luminescence properties of SnO2 nanorods and nanoparticles using steady-state and time-resolved spectroscopy. Defect-related bands are identified by Raman and EPR spectroscopy. On the basis of the experimental results, we propose a schematic model for different relaxation processes in SnO2 nanocrystals upon photoexcitation. Analysis suggests that the visible emission of SnO2 nanocrystals is due to a transition of an electron from a level close to the conduction band edge to a deeply trapped hole in the bulk (V0••) of the SnO2 nanocrystals. Analysis suggests that the surface-related defects are more prominent in smaller nanocrystals than in nanorods. It is found that the PL emission and decay time strongly depend on the shape of the nanocrystals. This proposed model is further confirmed by time-resolved spectroscopy.

Supramolecular Self-Assembly of M-IDA Complexes Involving Lone-Pair···π Interactions: Crystal Structures, Hirshfeld Surface Analysis, and DFT Calculations [H2IDA = iminodiacetic acid, M = Cu(II), Ni(II)]

Abstract: Mononuclear copper(II) and nickel(II) complexes, [(C5H6N2)Cu(IDA)(H2O)] (1) and (C5H7N2)2[Ni(IDA)2(H2O)] (2) [H2IDA = iminodiacetic acid; C5H6N2 = 4-aminopyridine; C5H7N2 = protonated 2-aminopyridine], have been synthesized, and their crystal structures were solved using single crystal X-ray diffraction data. A detailed analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions, which are crucial in building different supramolecular architectures. Molecules are linked by a combination of N–H···O, O–H···O and C–H···O hydrogen bonds into two-dimensional framework, whose formation is readily analyzed in terms of substructures of lower dimensionality with zero finite zero-dimensional dimeric units as the building blocks within the structures. Moreover, the aromatic molecules that are engaged in lone pair···π interactions with the noncoordinated carbonyl moieties play a crucial role in stabilizing the self-assembly process observed for both complexes. Intricate...