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Liquid crystal parameters through image analysis
No full textRestricted Access.A technique which combines image analysis and polarising optical microscope (POM) is a useful tool for the physical investigation of discotic liquid crystals, such as hexabutoxytriphenylene and hexahexyloxytriphenylene. This investigation includes the phase transitions, optical properties and order parameter as a function of temperature. Textures of discotic liquid crystals are captured as a function of temperature using POM. These microscopic textures are analysed using MATLAB software to compute statistical parameters, Legendre moments, optical parameters and order parameters of discotic liquid crystal samples. Compared with other techniques in the literature, the proposed methodology is a reliable and very simple technique for the physical investigation of liquid crystals
Effect of ring-substituted oxysterols on the phase behavior of dipalmitoylphosphatidylcholine membranes
No full textRestricted Access.Oxysterols are oxygenated derivatives of cholesterol that form a class of potent regulatory molecules with diverse biological activity. Given the implications of oxysterols in several physiological/pathophysiological pathways of human diseases, it is important to identify how their presence affects the biophysical properties of cell membranes. In this article we first describe the structure, formation, and biological functions of oxysterols, and previous work on the effect of these molecules on the structure and phase behavior of lipid membranes. We then present results of our X-ray diffraction experiments on aligned multilayers of dipalmitoylphosphatidylcholine (DPPC) membranes containing ring-substituted oxysterols. The effect of these molecules on the phase behavior of DPPC membranes is found to be very similar to that of cholesterol. All the oxysterols studied induce a modulated phase in DPPC membranes, similar to that reported in DPPC-cholesterol membranes. However, some differences are observed in the ability of these molecules to suppress the main transition of the lipid and to induce chain ordering, which might be related to differences in their orientation in the bilayer
Bangalore instrument figures in new radio telescope in Oz
No full textOpen AccessA brand new telescope located in western Australia, which could potentially save the world billions of dollars in future, will have a crucial made-in-Bangalore instrument in its core.....N Udayshankar, a RRI physicist closely associated with MWA project who attended the unveiling
Generation and distillation of non-Gaussian entanglement from nonclassical photon statistics
No full textRestricted Access.With a product state of the form ρin = ρa⊗ |0 ›bb ‹ 0| as input to a beam splitter, the output two-mode state ρ out is shown to be negative under partial transpose (NPT) whenever the photon number distribution (PND) statistics { ρ (n a ) } associated with the possibly mixed state ρ a of the input a-mode is antibunched or otherwise nonclassical, i.e., whenever { ρ (n a ) } fails to respect any one of an infinite sequence of necessary and sufficient classicality conditions. Negativity under partial transpose turns out to be a necessary and sufficient test for entanglement of ρ out which is generically non-Gaussian. The output of a PND distribution is further shown to be distillable if any one of an infinite sequence of three term classicality conditions is violated
Simulation of radiation-driven winds from disc galaxies
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We present 2-D hydrodynamic simulation of rotating galactic winds driven by radiation. We study the structure and dynamics of the cool and/or warm component( K) which is mixed with dust. We have taken into account the total gravity of a galactic system that consists of a disc, a bulge and a dark matter halo. We find that the combined effect of gravity and radiation pressure from a realistic disc drives the gas away to a distance of kpc in Myr for typical galactic parameters. The outflow speed increases rapidly with the disc Eddington parameter ) for . We find that the rotation speed of the outflowing gas is km s. The wind is confined in a cone which mostly consist of low angular momentum gas lifted from the central region
Photoconductivity of dopedhexa-alkoxy triphenylene nano composite structures
No full textRestricted Access.The photoconductivity of undoped as well as nanostructures of gold chloride dopedhexa-alkoxytriphenylene series (HAT4, HAT5 and HAT6) has been studied. After doping with gold chloride, the photoconductivity increased by more than ten times for HAT4 and HAT5 and not for HAT6. The high photoconductivity can be explained in terms of the transition temperatures, the core-core distances and their length of side chains. Photoconductivity of the gold chloride dopedhexa-alkoxytriphenylene derivatives are in the region 10−4–10−5 S m−1, which are five orders of magnitude higher than that of undoped compounds. The high NIR absorbance combined with the photoconductivity makes this nanocomposite a potential candidate for organic solar cell applications
Gravitational radiation for extreme mass ratio inspirals to the 14th post-Newtonian order
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We derive gravitational waveforms needed to compute the 14th post-Newtonian (14PN) order energy flux for a particle in circular orbit around a Schwarzschild black hole, i.e. v28 beyond the leading Newtonian approximation where v is the orbital velocity of a test particle. We investigate the convergence of the energy flux in the PN expansion and suggest a fitting formula which can be used to extract unknown higher order PN coefficients from accurate numerical data for more general orbits around a Kerr black hole. The phase difference between the 14PN waveforms and numerical waveforms after two years inspiral is shown to be about 10-7 for µ/M = 10-4 and 10-3 for µ/M = 10-5 where µ is the mass of a compact object and M the mass of the central supermassive black hole. In first order black hole perturbation theory, for extreme mass ratio inspirals which are one of the main targets of Laser Interferometer Space Antenna, the 14PN expressions will lead to the data analysis accuracies comparable to the ones resulting from high precision numerical waveforms