Fe-spin reorientation in PrFeAsO : Evidences from resistivity and specific heat studies

We report the magnetic field dependence of resistivity ($\rho$) and specific heat ($C$) for the non-superconducting PrFeAsO compound. Our study shows a hitherto unobserved anomaly at $T_{SR}$ in the resistivity and specific heat data which arises as a result of the interplay of antiferromagnetic (AFM) Pr and Fe sublattices. Below the AFM transition temperature ($T_N^{\rm{Pr}}$), Pr moment orders along the crystallographic c axis and its effect on the iron subsystem causes a reorientation of the ordered inplane Fe moments in a direction out of the $ab$ plane. Application of magnetic field introduces disorder in the AFM Pr sublattice, which, in turn, reduces the out-of-plane Pr-Fe exchange interaction responsible for Fe spin reorientation. Both in $\rho$($T$) and $d(C/T)/dT$ curves, the peak at $T_{SR}$ broadens with the increase of $H$ due to the introduction of the disorder in the AFM Pr sublattice by magnetic field. In $\rho$($T$) curve, the peak shifts towards lower temperature with $H$ and disappears above 6 T while in $d(C/T)/dT$ curve the peak remains visible up to 14 T. The broadening of the anomaly at $T_N^{\rm{Pr}}$ in $C(T)$ with increasing $H$ further confirms that magnetic field induces disorder in the AFM Pr sublattice.Comment: 8 pages, 10 Figure

Model for the free-volume distributions of equilibrium fluids

We introduce and test via molecular simulation a simple model for predicting the manner in which interparticle interactions and thermodynamic conditions impact the single-particle free-volume distributions of equilibrium fluids. The model suggests a scaling relationship for the density-dependent behavior of the hard-sphere system. It also predicts how the second virial coefficients of fluids with short-range attractions affect their free-volume distributions.Comment: 7 pages, 5 figure

SOCIAL STATUS OF DEVADASIS DURING THE 7TH AND 8TH CENTURIES IN TAMILNADU

Religions are not just systems of belief; they are also organizations, or parts of organizations. They have a communal and social significance, which goes by the name of social dimension. The social shape of a religion is of course, to some extent determined by the religious and ethical ideals and practices that it harbors. Conversely, it often happens that the religious and ethical ideals are adapted to existing social conditions and attitudes. It is incidentally, clear that the ongoing patterns of ritual are an important element in the institutionalization of religion, if it is believed that certain ceremonies and sacraments can be properly performed only by a priest, then the religious institution will be partly determined to the need to maintain and protect a professional priesthood and the institution of the devadasis in the temples. The devadasi system was a popular institution in the history of early India. Were serving the gods in the temples throughout India. M. S. Aiyangar says that the aesthetic arts were given a religious tone from about the 7th century CEwhen dancing and playing dramas were encourage to draw large crowds of devotees to the temples. Thus, hundreds of dancing girls or gandharvirs was attached to every important temple. According to K. K. Pillay the system became common in South Indian temples only after the 7th century CE The creation of the institution of devadasis, the carving of the Maithuna sculpture in temples, and the exhibition of sex influence in religious rituals in India. These, raised their ugly heads only after the 8th century CE, a period of decadence in Indian culture

Structural anomalies of fluids: Origins in second and higher coordination shells

Compressing or cooling a fluid typically enhances its static interparticle correlations. However, there are notable exceptions. Isothermal compression can reduce the translational order of fluids that exhibit anomalous waterlike trends in their thermodynamic and transport properties, while isochoric cooling (or strengthening of attractive interactions) can have a similar effect on fluids of particles with short-range attractions. Recent simulation studies by Yan [Phys. Rev. E 76, 051201 (2007)] on the former type of system and Krekelberg [J. Chem. Phys. 127, 044502 (2007)] on the latter provide examples where such structural anomalies can be related to specific changes in second and more distant coordination shells of the radial distribution function. Here, we confirm the generality of this microscopic picture through analysis, via molecular simulation and integral equation theory, of coordination shell contributions to the two-body excess entropy for several related model fluids which incorporate different levels of molecular resolution. The results suggest that integral equation theory can be an effective and computationally inexpensive tool for assessing, based on the pair potential alone, whether new model systems are good candidates for exhibiting structural (and hence thermodynamic and transport) anomalies.Chemical Engineerin

Copper chloride cathode for a secondary battery

Higher energy and power densities are achieved in a secondary battery based on molten sodium and a solid, ceramic separator such as a beta alumina and a molten catholyte such as sodium tetrachloroaluminate and a copper chloride cathode. The higher cell voltage of copper chloride provides higher energy densities and the higher power density results from increased conductivity resulting from formation of copper as discharge proceeds

Development and characterisation of biodegradable film from natural polymers

This study is focused on the preparation of silk fibroin based bio degradable films with the combination of variousconcentrations of chitosan (1:1 and 2:1), which is used as a drug releasing model. Scanning electronic microscope has beenused to observe the morphology of prepared films and the chemical compounds are studied by Fourier transform infrared.Required properties for successful wound dressing such as water uptake %, thickness, folding endurance and waterabsorption capacity are examined. Also, the mechanical strength (tensile strength and elasticity), liquid culture test,% degradation, folding endurance and water uptakes of the films are analysed gravimetrically. Antimicrobial activity againstEscherichia coli is evaluated quantitatively using Agar diffusion test (AATCC 100) and liquid culture test (BS EN ISO-14119, 2003). The obtained films are found homogenous without phase separation. The traces of both silk fibroin andchitosan are found evenly distributed in the film. Blend proportion of 2:1 shows rougher surface, and better results in term ofantibacterial property are obtained against Gram negative bacteria Escherichia coli

Quantm Magnetoresistance of the PrFeAsO oxypnictides

We report the observation of an unusual $B$ dependence of transverse magnetoresistance (MR) in the PrFeAsO, one of the parent compound of pnictide superconductors. Below the spin density wave transition, MR is large, positive and increases with decreasing temperature. At low temperatures, MR increases linearly with $B$ up to 14 T. For $T$$\geq$40 K, MR vs $B$ curve develops a weak curvature in the low-field region which indicates a crossover from $B$ linear to $B^2$ dependence as $B$$\rightarrow$0. The $B$ linear MR originates from the Dirac cone states and has been explained by the quantum mechanical model proposed by Abrikosov.Comment: accepted for publication in Appl. Phys. Let

Tensor Minkowski Functionals for random fields on the sphere

We generalize the translation invariant tensor-valued Minkowski Functionals which are defined on two-dimensional flat space to the unit sphere. We apply them to level sets of random fields. The contours enclosing boundaries of level sets of random fields give a spatial distribution of random smooth closed curves. We obtain analytic expressions for the ensemble expectation values for the matrix elements of the tensor-valued Minkowski Functionals for isotropic Gaussian and Rayleigh fields. We elucidate the way in which the elements of the tensor Minkowski Functionals encode information about the nature and statistical isotropy (or departure from isotropy) of the field. We then implement our method to compute the tensor-valued Minkowski Functionals numerically and demonstrate how they encode statistical anisotropy and departure from Gaussianity by applying the method to maps of the Galactic foreground emissions from the PLANCK data.Comment: 1+23 pages, 5 figures, Significantly expanded from version 1. To appear in JCA