Optical phonons in new ordered perovskite Sr2Cu(Re0.69Ca0.31) Oy system observed by infrared reflectance spectroscopy

We report infrared reflectivity spectra for a new correlated cupric oxide system Sr2Cu(Re0.69Ca0.31)Oy with y ~ 0.6 at several temperatures ranging between 8 and 380 K. The reflectivity spectrum at 300 K comprises of several optical phonons. A couple of residual bands located around 315 and 653 cm-1 exhibit exceptionally large intensity as compared to the other ones. The overall reflectivity spectrum lifts up slightly with increasing temperature. The energy and damping factor of transverse-optical phonons are determined by fitting the imaginary dielectric constant by Lorentz oscillator model and discussed as a function of temperature in terms of lattice anharmonicity.Comment: 9 pages, 3 figures, presented at ISS2005, to appear in Physica

FDM preparation of bio-compatible UHMWPE polymer for artificial implant

Due to its properties of high wear, creep resistance, high stiffness and strength, Ultra-High Molecular Weight Polyethylene (UHMWPE) was developed to eliminate most metallic wear in artificial implant, which conventionally found in stainless steel, Cobalt Chromium (Co-Cr) and Titanium (Ti) alloys. UHMWPE has an ultra-high viscosity that renders continuous melt-state processes including one of the additive manufacturing processes, Fused Deposition Modeling (FDM) ineffective for making UHMWPE implant. Attempt to overcome this problem and adapting this material to FDM is by blending UHMWPE with other polyethylene including High Density Polyethylene (HDPE) and Polyethylene-Glycol (PEG) which provide adequate mechanical properties for biomedical application along with the improvement in extrudability. It was demonstrated that the inclusion of 60% HDPE fraction has improved the flowability of UHMWPE in MFI test and showing adequate thermal stability in TGA

Higher Dimensional Inhomogeneous Perfect Fluid Collapse in \emph{f(R)} Gravity

This paper is about the $n+2$-dimensional gravitational contraction of inhomogeneous fluid without heat flux in the framework of $f(R)$ metric theory of gravity. Matching conditions for two regions of a star has been derived by using the Darmois junction conditions. For the analytic solution of equations of motion in modified $f(R)$ theory of gravity, we have taken scalar curvature as constant. Hence final result of gravitational collapse in this frame work is the existence of black hole and cosmological horizons, both of these form earlier than singularity. It has been shown that constant curvature term $f(R_{0})$ ($R_0$ is constant scalar curvature) slows down the collapsing process.Comment: 17 Pages, to appear in European Physical Journal

Event by Event Analysis of High Multiplicity Events Produced in 158 A GeV/c 208 Pb- 208 Pb Collisions

An extensive analysis of individual high multiplicity events produced in 158 A GeV /c 208Pb- 208Pb collisions is carried by adopting different methods to examine the anomalous behavior of these rare events. A method of selecting the events with densely populated narrow regions or spikes out of a given sample of collision events is discussed.Employing this approach two events with large spikes in their eta- and phi- distributions are selected for further analysis. For the sake of comparison, another two events which do not exhibit such spikes are simultaneously analyzed. The findings suggest that the systematic studies of particle density fluctuations in one- and two-dimensional phase-spaces and comparison with those obtained from the studies of correlation free Monte Carlo events, would be useful for identifying the events with large dynamical fluctuations. Formation of clusters or jet like phenomena in multihadronic final states in individual events is also discussed and the experimental findings are compared with the independent particle emission hypothesis by carrying out Monte Carlo simulations