2,222 research outputs found

    Spectrochemical Investigation of di methoxy Aniline Dithiocarbamate metal complexes-Biological activity

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    Dithiocarbomates are a class of sulfur-based metal-chelating compounds commonly used in industry, agriculture, and medicine. 2,6 di methoxy Aniline dithiocarbamate  Complexes of Copper and Ruthenium have been prepared  and Characterized by Spectroscopic methods like IR,NMR and also analysis of Biological activity. The investigation of these complexes confirmed that the stability of metal–ligands coordination through, S & S,N atoms as bidendate chelates.

    Technipion Limits from LHC Higgs Searches

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    LHC searches for the standard model Higgs Boson in di-photon or di-tau decay modes place strong constraints on the light top-pion state predicted in technicolor models that include colored technifermions. Compared with the standard Higgs Boson, the top-pions have an enhanced production rate (largely because the technipion decay constant is smaller than the weak scale) and also enhanced branching ratios into di-photon and di-tau final states (largely due to the suppression of WW decays of the technipions). These factors combine to make the technipions more visible in both channels than a standard model Higgs would be. Hence, the recent ATLAS and CMS searches for Higgs bosons exclude the presence of technipions with masses from 110 GeV to nearly twice the top-quark mass in technicolor models that (a) include colored technifermions (b) feature topcolor dynamics and (c) have technicolor groups with three or more technicolors. For certain models, the limits also apply out to higher technipion masses or down to the minimum number of technicolors. The limits may be softened somewhat in models where extended technicolor plays a significant role in producing the top quark's mass. Additional LHC data on di-tau and di-photon final states will be extremely valuable in further exploring technicolor parameter space.Comment: 15 pages, 5 figures, PDF-LaTe

    A Computational Teddqae for Heat W a r h e to a Fast Movhg Hl(lf 80urce

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    The heat transfer in the two phase region in the study of melting and solidification of a surface layer by a moving heat source is studied.The transient problem is formulated using the enthalpy and temperature model and solved in an oblate spheroidal co-ordinate system using animplicit modified upwinding scheme in terms of non-dimensional nodal enthalpy and temperature. It is observed that the temperature gradient which controls the solidification rate, increases to a maximum initiallyand then decreases to zero. It is found that the solid-liquid interface velocity which is zero initially very quickly reaches to the velocity ofthe heat source, though the gradient ahead of the interface relaxes much more slowly

    R^2 Corrections to Asymptotically Lifshitz Spacetimes

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    We study R2R^{2} corrections to five-dimensional asymptotically Lifshitz spacetimes by adding Gauss-Bonnet terms in the effective action. For the zero-temperature backgrounds we obtain exact solutions in both pure Gauss-Bonnet gravity and Gauss-Bonnet gravity with non-trivial matter. The dynamical exponent undergoes finite renormalization in the latter case. For the finite-temperature backgrounds we obtain black brane solutions perturbatively and calculate the ratio of shear viscosity to entropy density η/s\eta/s. The KSS bound is still violated but unlike the relativistic counterparts, the causality of the boundary field theory cannot be taken as a constraint.Comment: 24 pages, Latex, typos fixed, accepted by JHE

    Quantum phase transition in a Dp-Dq system

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    Using the top-down approach, we study intersecting Dp-Dq brane configuration in string theory and find examples, where there can be a quantum phase transition at zero temperature induced by the violation of the Breitenlohner-Freedman (BF) bound at IR, which is done essentially by a combination of charge density and magnetic fields. In particular, there exists a Berezinskii-Kosterlitz-Thouless (BKT) type of transition for D3-D5 and D5-D5 systems. The study of the BKT type of transition is initiated by Jensen et al. [Phys. Rev. Lett. {\bf 105}, 041601 (2010) ] for a D3-D5 system with nonzero charge density and a magnetic field. Here, we show that one can have the BKT transition for a D3-D5 system even in the absence of charge density but requires multiple magnetic fields. In this case the field theory lives in 2+1 dimensions, whereas for the D5-D5 type, the transition requires the presence of both the charge density and magnetic fields and the dual field theory lives on a 3+1 dimensional spacetime. We also study the D3-D7 system but it does not show the BKT type of transition.Comment: 1+37 pages; v2 Chern-Simon term for D3-D5 case presented, typos fixed and a reference added; v3 Minor corrections, Chern-Simon term for D2-D4, D4-D6, and D5-D7 added, also an appendix and few references added; v4 Journal versio

    Qualitative observation of reversible phase change in astrochemical ethanethiol ices using infrared spectroscopy

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    Here we report the first evidence for a reversible phase change in an ethanethiol ice prepared under astrochemical conditions. InfraRed (IR) spectroscopy was used to monitor the morphology of the ice using the Ssingle bondH stretching vibration, a characteristic vibration of thiol molecules. The deposited sample was able to switch between amorphous and crystalline phases repeatedly under temperature cycles between 10 K and 130 K with subsequent loss of molecules in every phase change. Such an effect is dependent upon the original thickness of the ice. Further work on quantitative analysis is to be carried out in due course whereas here we are reporting the first results obtained

    The Three Site Model at One-Loop

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    In this paper we compute the one-loop chiral logarithmic corrections to all O(p^4) counterterms in the three site Higgsless model. The calculation is performed using the background field method for both the chiral- and gauge-fields, and using Landau gauge for the quantum fluctuations of the gauge fields. The results agree with our previous calculations of the chiral-logarithmic corrections to the S and T parameters in 't Hooft-Feynman gauge. The work reported here includes a complete evaluation of all one-loop divergences in an SU(2) x U(1) nonlinear sigma model, corresponding to an electroweak effective Lagrangian in the absence of custodial symmetry.Comment: 40 pages, nine included eps figures. Minor corrections mad

    The Many Electron Ground State of the Adiabatic Holstein Model in Two and Three Dimensions

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    We present the complete ground state phase diagram of the Holstein model in two and three dimension considering the phonon variables to be classical. We first establish the overall structure of the phase diagram by using exact diagonalisation based Monte Carlo (ED-MC) on small lattices and then use a new ``travelling cluster'' approximation (TCA) for annealing the phonon degrees of freedom on large lattices. The phases that emerge include a Fermi liquid (FL), with no lattice distortions, an insulating polaron liquid (PL) at strong coupling, and a charge ordered insulating (COI) phase around half- filling. The COI phase is separated from the Fermi liquid by a regime of phase coexistence whose width grows with increasing electron-phonon coupling. We provide results on the electronic density of states, the COI order parameter, and the spatial organisation of polaronic states, for arbitrary density and electron-phonon coupling. The results highlight the crucial role of spatial correlations in this strong coupling problem.Comment: Final versio

    Supercapacitors Based On Patronite-reduced Graphene Oxide Hybrids: Experimental And Theoretical Insights

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    Here we report the hydrothermal synthesis and detailed study on supercapacitor applications of a patronite hybrid, VS4/reduced graphene oxide, which showed an enhanced specific capacitance of similar to 877 F g(-1) at a current density of 0.5 A g(-1). In comparison to bare vanadium sulfide and reduced graphene oxide, the hybrid showed similar to 6 times and similar to 5 times higher value of specific capacitance, respectively. The obtained energy density (117 W h kg(-1)) and power density (20.65 kW kg(-1)) are comparable to those of other reported transition metal sulfides and their graphene hybrids. Theoretical calculations using density functional theory confirm an enhanced quantum capacitance of VS4/graphene composite systems, owing primarily to the shifting of the graphene Dirac cone relative to the band gap of VS4. The results infer that the hybrid has the potential to be used as a high performance supercapacitor electrode.3371887418881DST (Government of India)DST-SERB [SB/FTP/PS-065/2013]Conselho Nacional de Desenvolvimento CientĂ­fico e TecnolĂłgico (CNPq)Ramanujan Fellowship [SR/S2/RJN-21/2012]Department of Science and Technology (DST-SERB), Govt. of India [SR/S1/IC-04/2012]Interconnect Focus Center (MARCO program)State of New YorkNational Science Foundation (NSF) Integrative Graduate Education and Research Traineeship (IGERT) program [0333314]Indo-US Science and Technology Forum (IUSSTF) through a joint INDO-US centre grantMinistry of Human Resources Development (MHRD), India through a center of excellence gran
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