https://idr.niser.ac.in/jspui/handle/123456789/22 Mon, 06 Apr 2026 19:30:49 GMT 2026-04-06T19:30:49Z https://idr.niser.ac.in/jspui/handle/123456789/1271 Title: Guanidinate stabilized germanium(II) and tin(II) amide complexes and their catalytic activity for aryl isocyanate cyclization Authors: Barman, Milan Kr; Baishya, Ashim; Peddarao, Thota; Nembenna, Sharanappa Abstract: Two different synthetic routes for the preparation of guanidinate stabilized germanium(II) and tin(II) amide complexes have been established. First, the reaction of one equiv of bulky guanidine ligand either L1H or L2H [L1 = {ArNC (NiPr2)NAr} (Ar = 2,6-Me2–C6H3) and L2 = {Ar′NC (NiPr2) NAr′}(Ar′ = 2,6-iPr2-C6H3)] with two equiv of KN(SiMe3)2 and one equiv of metal dihalide i.e., MCl2{M = Ge(dioxane) and Sn} led to the formation of guanidinate supported germanium(II) amide, i.e., L1GeN(SiMe3)2 (1) and tin amide, i.e., L1SnN(SiMe3)2 (2) and L2SnN(SiMe3)2 (3) complexes, respectively. Second, deprotonation of L1H upon treatment with M[N(SiMe3)2]2 (M = Ge and Sn) in C6D6 at 80 °C for 12 h, afforded the compounds L1MN(SiMe3)2 M = Ge(1) and Sn(2), respectively. X-ray crystal structures of 1 and 2 revealed that both are in monomeric and metal centers in distorted tetrahedral environments with one vertex occupied by a stereo chemically active lone pair of electrons. Furthermore, compounds 1, 2 and 3 were tested for the catalytic activity in the cyclotrimerization of arylisocyanates, which are exhibiting as excellent catalysts. Mon, 01 Dec 2014 00:00:00 GMT https://idr.niser.ac.in/jspui/handle/123456789/1271 2014-12-01T00:00:00Z https://idr.niser.ac.in/jspui/handle/123456789/1270 Title: Search for supersymmetry with razor variables in pp collisions at √s=7TeV Authors: Swain, Sanjay Kumar Abstract: The razor approach to search for 𝑅–parity conserving supersymmetric particles is described in detail. Two analyses are considered: an inclusive search for new heavy particle pairs decaying to final states with at least two jets and missing transverse energy, and a dedicated search for final states with at least one jet originating from a bottom quark. For both the inclusive study and the study requiring a bottom-quark jet, the data are examined in exclusive final states corresponding to all-hadronic, single-lepton, and dilepton events. The study is based on the data set of proton-proton collisions at √𝑠=7  TeV collected with the CMS detector at the LHC in 2011, corresponding to an integrated luminosity of 4.7  fb−1. The study consists of a shape analysis performed in the plane of two kinematic variables, denoted 𝑀𝑅 and 𝑅2, that correspond to the mass and transverse energy flow, respectively, of pair-produced, heavy, new-physics particles. The data are found to be compatible with the background model, defined by studying event simulations and data control samples. Exclusion limits for squark and gluino production are derived in the context of the constrained minimal supersymmetric standard model (CMSSM) and also for simplified-model spectra (SMS). Within the CMSSM parameter space considered, squark and gluino masses up to 1350 GeV are excluded at 95% confidence level, depending on the model parameters. For SMS scenarios, the direct production of pairs of top or bottom squarks is excluded for masses as high as 400 GeV. Mon, 01 Dec 2014 00:00:00 GMT https://idr.niser.ac.in/jspui/handle/123456789/1270 2014-12-01T00:00:00Z https://idr.niser.ac.in/jspui/handle/123456789/1267 Title: Measurement of nonlinear refractive index in open-aperture Z-scan experiments Authors: Das, Ritwick; Shukla, Mukesh Kumar Abstract: We present an experimental study on measurement of nonlinear refractive index (n 2) of organic liquids when the thermo-optic effects manifest into large nonlinear phase shifts (Δϕ 0) in an open-aperture Z-scan configuration. Although we do not obtain the familiar peak–valley normalized transmittance curve as in the case of closed-aperture Z-scan technique, we use a theoretical model using Gaussian beam decomposition (GD) technique to estimate the value of n 2. Using this recipe, we obtain the nonlinear refractive index n 2 = −(4.90 ± 1.20) × 10−15 cm2/W for toluene (organic solvent) and n 2 = −(10.60 ± 2.10) × 10−15 cm2/W for an organic polymer solution (10−4 M in toluene). By carrying out absorption measurements directly with an unfocussed Gaussian beam, we found nonlinear absorptions β tol = (2.42 ± 0.20) × 10−13 m/W and β poly = (2.79 ± 0.24) × 10−13 m/W which are close to the expected results. Sun, 28 Sep 2014 00:00:00 GMT https://idr.niser.ac.in/jspui/handle/123456789/1267 2014-09-28T00:00:00Z https://idr.niser.ac.in/jspui/handle/123456789/1265 Title: Curcumin's neuroprotective efficacy in Drosophila model of idiopathic parkinson's disease is phase specific : Implication of its therapeutic effectiveness Authors: Alone, Debasmita Pankaj Abstract: Selective degeneration of dopaminergic neurons in the substantia nigra underlies the basic motor impairments of Parkinson's disease (PD). Curcumin has been used for centuries in traditional medicines in India. Our aim is to understand the efficacy of genotropic drug curcumin as a neuroprotective agent in PD. Analysis of different developmental stages in model organisms revealed that they are characterized by different patterns of gene expression which is similar to that of developmental stages of human. Genotropic drugs would be effective only during those life cycle stages for which their target molecules are available. Hence there exists a possibility that targets of genotropic compounds such as curcumin may not be present in all life stages. However, no reports are available in PD models illustrating the efficacy of curcumin in later phases of adult life. This is important because this is the period during which late-onset disorders such as idiopathic PD set in. To understand this paradigm, we tested the protective efficacy of curcumin in different growth stages (early, late health stage, and transition phase) in adult Drosophila flies. Results showed that it can rescue the motor defects during early stages of life but is ineffective at later phases. This observation was substantiated with the finding that curcumin treatment could replenish depleted brain dopamine levels in the PD model only during early stages of life cycle, clearly suggesting its limitation as a therapeutic agent in late-onset neurodegenerative disorders such as PD. Wed, 17 Dec 2014 00:00:00 GMT https://idr.niser.ac.in/jspui/handle/123456789/1265 2014-12-17T00:00:00Z