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Tagged particle diffusion in one-dimensional gas with Hamiltonian dynamics
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We consider a one-dimensional gas of hard point particles in a finite box that are in thermal equilibrium and evolving under Hamiltonian dynamics. Tagged particle correlation functions of the middle particle are studied. For the special case where all particles have the same mass, we obtain analytic results for the velocity auto-correlation function in the short time diffusive regime and the long time approach to the saturation value when finite-size effects become relevant. In the case where the masses are unequal, numerical simulations indicate sub-diffusive behaviour with mean square displacement of the tagged particle growing as t/ln( t) with time t. Also various correlation functions, involving the velocity and position of the tagged particle, show damped oscillations at long times that are absent for the equal mass case
Partitioning of ethanol in multi-component membranes: Effects on membrane structure
No full textRestricted Access.The molecular mechanism of ethanol and its effects on neurological function is far from clear. In this study, we investigate the effects of ethanol on various structural and dynamical properties of mixed bilayers consisting of different ratios of dipalmitoylphosphatidylcholine (DPPC), sphingomyelin (SM) and cholesterol that are typical constituents of neural cell membranes (Calderon et al., 1995) using molecular dynamics (MD) simulations. The bilayer properties such as thickness, hydrophobic chain order, and diffusive motion of individual lipids as well collective properties like lateral pressure profiles are affected by the presence of ethanol molecules. The simulations show that the percentage of cholesterol present in the bilayers significantly affects the depth of penetration of ethanol molecules. In particular, presence of very high concentration of cholesterol molecules enhances the rigidity of the bilayer and renders them resistant to the penetration of the ethanol molecules, consistent with experiments. Ethanol molecules compete with cholesterol molecules for hydrogen bonding and disrupt cholesterol–lipid interactions, especially those between SM and cholesterol. Ethanol molecules also affect the lateral pressure profiles in the bilayer systems. These results may have implications in understanding the general anesthetic mechanism and role played by cholesterol on partitioning of such anesthetic/alcohol molecules into cell membrane
Science with the Murchison widefield array
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objective
Nakshatra manthanadalli Bengalurina vijnanigalu: vishwakiran aitihyavannu bayalu maduva nirikshe
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ZnO-Modi ed MoO3 nano-rods, -wires, -belts and -tubes : Photophysical and nonlinear optical properties
No full textRestricted Access.We report a versatile approach to obtain MoO3 nanostructures such as nanorods, nanowires, nanobelts, and nanotubes in thin film form on glass substrates, by incorporating ZnO, via RF magnetron sputtering and controlled subsequent oxidation. The nanostructures growth mechanism has been elucidated on the basis of strain field associated with defect-oriented partial screw dislocation induced by ZnO for the drastic variation of the morphology with respect to ZnO incorporating levels from initial tiny nanorods (pure MoO3) to larger nanorods (at 1%), then to aligned and tilted nanowire arrays (at 3 and 5% respectively), afterward to nanobelts (at 7%), and finally to nanotubes (at 10%). Novel properties of ZnO-incorporated MoO3 nanostructures like enhanced photoluminescence and optical limiting have been brought out. This study opens the door to the potentiality of ZnO-added MoO3 nanostructures to be used as luminescent transparent conducting materials, saturable absorbers, and optical limiters
Ultrafast optical nonlinearity, electronic absorption, vibrational spectra and solvent e ect studies of ninhydrin
No full textRestricted Access.FT-IR, FT-Raman and UV–Vis spectra of the nonlinear optical molecule ninhydrin have been recorded and analyzed. The equilibrium geometry, bonding features, and harmonic vibrational wavenumbers have been investigated with the help of B3LYP density functional theory method. A detailed interpretation of the vibrational spectra is carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology. Solvent effects have been calculated using time-dependent density functional theory in combination with the polarized continuum model. Natural bond orbital analysis confirms the occurrence of strong intermolecular hydrogen bonding in the molecule. Employing the open-aperture z-scan technique, nonlinear optical absorption of the sample has been studied in the ultrafast and short-pulse excitation regimes, using 100 fs and 5 ns laser pulses respectively. It is found that ninhydrin exhibits optical limiting for both excitations, indicating potential photonic application
