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.     

Synchronous Luminescence Spectroscopic Characterization of Urine of Normal Subjects and Cancer Patients

Urine is one of the diagnostically potential bio fluids, as it contains many metabolites and some of them are native fluorophores. These fluorophores distribution and the physiochemical properties may vary during any metabolic change or at different pathologic conditions. Since urine is a multicomponent fluid, synchronous luminescence technique, a powerful tool has been adopted to analyse multicomponents in single spectrum and to resolve emission spectrum without much of photobleaching of fluorophores. In this study, urine samples of both normal subjects and cancer patients were characterised using synchronous luminescence spectroscopy with a Stokes shift of 20 nm. Different ratio parameters were calculated from the intensity values of the synchronous luminescence spectra and they were used as input variables for a multiple linear discriminant analysis across normal and cancer groups. The stepwise linear discriminant analysis classifies 90.3 % of the original grouped cases and 88.6 % of the cross-validated grouped cases correctly.     

Thermophoresis particle deposition effects in a free convective doubly stratified medium over a vertical plate

An analysis is performed to study the thermophoresis effects in a transient free convective flow of a viscous, incompressible fluid past an isothermal vertical plate in a doubly stratified medium. The governing boundary layer equations are solved numerically using an implicit finite difference scheme of Crank-Nicolson type. The influence of thermophoresis on particle deposition velocity and particle concentration in a doubly stratified medium are analyzed and illustrated graphically. As well the influence of thermal and mass stratification on velocity, temperature and concentration are also investigated and presented. The influence of the parameters on local as well as average skin-friction, the rate of heat and mass transfer are presented graphically and discussed. The results are compared with particular solutions available in the literature and are found to be in good agreement.     

Effect of Co substitution on the magnetic properties of BiFeO3

Bismuth ferrite is doped with a dilute concentration of cobalt, _{BiFe1−XCoXO3}${\mathrm{BiFe}}_{1-X}{\mathrm{Co}}_X{\mathrm{O}}_3$; X=0, 0.01, 0.02 is prepared by sol-gel auto combustion technique. X-ray diffraction data refined via Reitveld method shows single phase and shrinkage in cell volume for Co doped BiFeO₃. Various magnetic ground states viz. superparamagnetic, glassy antiferromagnetic and glassy ferrimagnetic behavior is observed for X=0, 0.01, 0.02, respectively. A first-order magnetic transition is observed in the Arrott plot data of cobalt doped BiFeO₃. Possibility of thermally induced magnetic transition is also seen in the magnetization data of cobalt doped BiFeO₃. A model based on the existing spinoidal cyclic arrangement of spins is proposed to explain the observed data. Finally, a very dilute concentration of Co⁺³${\mathrm{Co}}^{+3}$ in BiFeO₃ is found sufficient to tailor the magnetic properties.     

Effect of ammonium acetate addition on crystal growth,spectral, thermal and optical properties of glycine single crystals

Gamma glycine single crystal is a potential organic nonlinear optical (NLO) material. It has been grown from a mixture of aqueous solutions of glycine and ammonium acetate by slow evaporation solution growth technique at room temperature for the first time. Powder X-ray diffraction studies are carried out and the results are compared. CHN analysis confirms the non-inclusion of ammonium acetate species in to the solution. FTIR studies are performed to identify the presence of various functional groups in the grown crystal. Differential scanning calorimetry analysis (DSC) was carried out to study the thermal stability and phase transition of the grown crystal. The optical analysis shows that UV cut-off of γ-glycine is at 190 nm and it has a wide transparency window. The second harmonic generation relative efficiency of the grown crystals was observed to be 1.72 times that of potassium dihydrogen orthophosphate (KDP).     

Current–voltage characteristics of PLD grown manganite based ZnO/La0.5Pr0.2Sr0.3MnO3/SrNb0.002Ti0.998O3 thin film heterostructure

We report the results of studies on the rectifying behavior and tunneling conduction in ZnO(n)/La_0.5Pr_0.2Sr_0.3MnO₃(LPSMO)(p)/SrNb_0.002Ti_0.998O₃ (SNTO)(n) thin film heterostructure comprising of two p–n junctions fabricated using the Pulsed Laser Deposition (PLD) technique. A structural study using XRD $?$-scan depicts the single-crystalline nature and confirms the phase purity while the transport studies using $I\text{–}V$ measurements at various temperatures and fields reveal the rectifying behavior. The temperature and field dependent variation in the saturation voltage $\left(V_C\right)$ indicates that, the heterostructure exhibits negative magnetoresistance (MR) at low temperatures and positive MR at room temperature (RT) which can be understood on the basis of the interface effect at the junction. $I\text{–}V$ curves obtained at all temperatures and fields show noticeable hysteresis during the positive voltage sweeping which has been attributed to the presence of the various conduction phenomena through the junctions in the presently studied heterostructure.     

Molecular mass dependence of point-to-set correlation length scale in polymers

We use a recently proposed metric, termed the point-to-set correlation functions, to probe the molecular weight dependence of the relevant static length scales in glass-forming oligomeric chain liquids of 4, 5, 8, and 10 repeat units. In agreement with the results for simple, monatomic fluids, we find that static length scales of the oligomers increase monotonically when the temperature is lowered towards the glass transition temperature of the fluid. More interestingly, the static length scale increases with increasing chain length. Within the bounds of error in our simulations, the static length scale appears to scale as the radius of gyration of the oligomer, but with a prefactor, which is much larger than unity and which grows with the temperature. The preceding behavior contrasts with the length scales extracted from the radial distribution function of the oligomer system, which is practically independent of the chain length.     

Measurement of the neutron capture cross-section of 238U using the neutron activation technique

The ²³⁸U(n, ??)²³⁹U reaction cross-section at average neutron energy of 3.7?±?0.3?MeV from the ⁷Li(p, n)⁷Be reaction has been determined using activation and off-line ??-ray spectrometric technique. The ²³⁸U(n, ??)²³⁹U and ²³⁸U(n, 2n)²³⁷U reaction cross-sections at average neutron energy of 9.85?±?0.38?MeV from the same ⁷Li(p, n)⁷Be reaction have been also determined using the above technique. The experimentally determined ²³⁸U(n, ??)²³⁹U and ²³⁸U(n, 2n)²³⁷U reaction cross-sections were compared with the evaluated data of ENDF/B-VII, JENDL-4.0, JEFF-3.1 and CENDL-3.1. The experimental values were found to be in general agreement with the evaluated value based on ENDF/B-VII, and JENDL-4.0 but not with the JEFF-3.1 and CENDL-3.1. The present data along with literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels including fission. The ²³⁸U(n, ??)²³⁹U and ²³⁸U(n, 2n)²³⁷U reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were also found to be in agreement experimental data.