Role of Ti in the luminescence process of Al2O3:Si,Ti

Al₂O₃:Si,Ti, prepared under oxidizing condition at high temperature, gives PL emission around 430 nm when excited with 240 nm. The Al₂O₃:C, TL/OSL phosphor, also shows emission around 430 nm, which corresponds to characteristic emission of F-center. Thus, to identify the exact nature of luminescent center in Al₂O₃:Si,Ti, fluorescence lifetime measurement studies were carried out along with the PL,TL and OSL studies. The PL and TL in Al₂O₃:Si,Ti show emission around 430 nm and the time-resolved fluorescence studies show lifetime of about 43 μs for the 430 nm emission, which is much smaller than the reported lifetime of ∼35 ms for the 430 nm emission (F-center emission) in Al₂O₃:C phosphor. Therefore, the emission observed in Al₂O₃:Si,Ti phosphor was assigned to Ti⁴⁺ charge transfer transition. Fluorescence studies of Al₂O₃:Si,Ti do not show any traces of F and F⁺ centers. Also, Ti⁴⁺ does not show any change in the charge state after gamma-irradiation. On the basis of the above studies, a mechanism for TSL/OSL process in Al₂O₃:Si,Ti is proposed.     

Spin nematics and magnetization plateau transition in anisotropic kagome magnets

We study S=1 kagome antiferromagnets with an isotropic Heisenberg exchange J and strong easy-axis single-ion anisotropy D. For D>J, the low-energy physics can be described by an effective S=1/2 XXZ model with antiferromagnetic Jz approximately J and ferromagnetic J perpendicular approximately J2/D. Exploiting this connection, we argue that nontrivial ordering into a "spin-nematic" occurs whenever D dominates over J, and discuss its experimental signatures. We also study a magnetic field induced transition to a magnetization plateau state at magnetization 1/3 which breaks lattice translation symmetry due to ordering of the Sz and occupies a lobe in the B/Jz-Jz/J perpendicular phase diagram.     

Formulation,Rheology, and Hypolepidemic Activity of Vegetable Oil-Based Eggless and Low-Fat Food Emulsions

Common edible oils such as almond, safflower, soybean, and mustard oil were formulated in the form of eggless and low-fat oil-in-water emulsions using a blend of nonionic emulsifier Glycerol monostearate and amphoteric emulsifier soy lecithin. The emulsion parameters such as vegetable oil, emulsifier, additive content and hydrophilic-lipophilic balance number of emulsifier were optimized. The storage stability of formulated emulsions was monitored under accelerated storage stability conditions for six months. Rheological characterization of stable emulsion revealed pseudoplastic flow behavior. In vivo hypolepidemic activity of formulated emulsions in rats showed considerable reduction in total cholesterol and triglyceride level after 14 days as compared with the marketed product. The almond oil emulsion is found superior than safflower oil emulsion.     

EPR evidence for the restricted mobility of NO2 in gamma irradiated thorium nitrate pentahydrate Th(NO3)4·5H2O

Electron paramagnetic resonance (EPR) studies were conducted on gamma irradiated polycrystalline sample of thorium nitrate pentahydrate, Th(NO(3))(4)·5H(2)O, in the temperature range of 100-300 K. The most prominent species with triplet hyperfine structure in the EPR spectrum was identified as NO(2). The EPR spectrum gave evidence for the stabilization of NO(2) in at least three different sites slightly differing in spin Hamiltonian parameters (Site(1): g(x)=2.0042, g(y)=1.9911, g(z)=2.0020, A(x)=54.20 G, A(y)=48.50 G and A(z)=65.25 G; Site(2): g(x)=2.0042, g(y)=1.9911, g(z)=2.0020, A(x)=54.20 G, A(y)=48.50 G and A(z)=67.85 G; Site(3): g(x)=2.0045, g(y)=1.9911, g(z)=2.0015, A(x)=54.20 G, A(y)=49.05 G and A(z)=72.45 G). The EPR spectra for Site(1) revealed molecular dynamics of NO(2) from a slow motion region to fast motion region as the sample temperature was varied from 100 to 300 K. This led to a change in EPR spectrum from orthorhombic to axial, indicating preferred rotation of NO(2) molecule about the O-O bond direction. However, the NO(2) molecule at Site(2) was found to be rigid throughout the entire temperature range. The differences in the mobility of NO(2) molecules occupying the two sites could be attributed to the fact that in one case NO(2) was bonded to thorium or water and in the other case it was weakly bound. The NO(2) bound to thorium through two oxygen atoms or bound to thorium on one side through one oxygen atom and hydrogen bonded to water on the other side remains rigid throughout the entire temperature range, while NO(2) situated at interstitial sites or adsorbed on the surface exhibits mobility with increase in temperature above 100K.     

Model-independent analysis of Higgs spin and CP properties in the process \boldsymbol{e}^{+} \boldsymbol{e}^{-} \to\boldsymbol{t}\bar{\boldsymbol{t}} \boldsymbol{\Phi}

In this paper we investigate methods to study the $t\bar{t}$ Higgs coupling. The spin and CP properties of a Higgs boson are analysed in a model-independent way in its associated production with a $t\bar{t}$ pair in high-energy e ⁺ e ^? collisions. We study the prospects of establishing the CP quantum numbers of the Higgs boson in the CP-conserving case as well as those of determining the CP-mixing if CP is violated. We explore in this analysis the combined use of the total cross section and its energy dependence, the polarisation asymmetry of the top quark and the up-down asymmetry of the antitop with respect to the top–electron plane. We find that combining all three observables remarkably reduces the error on the determination of the CP properties of the Higgs Yukawa coupling. Furthermore, the top polarisation asymmetry and the ratio of cross sections at different collider energies are shown to be sensitive to the spin of the particle produced in association with the top-quark pair.     

Composition dependence of effective thermal conductivity and effective thermal diffusivity of Se100−xInx (x=0, 5, 10, 15 and 20) chalcogenide glasses

Simultaneous measurement of effective thermal conductivity (λ_e) and effective thermal diffusivity (χ_e) of twin pallets of Se_100−xIn_x (x=0,5, 10, 15, and 20) glasses, prepared under a load of 5 tons, have been made at room temperature using the Transient Plane Source (TPS) technique. The values of λ_e and χ_e were found to increase initially with the increase of concentration of In in Se-In alloy and had their maximum at 10 at.wt% of indium. For indium concentration beyond 10 at.wt% of the values of effective thermal conductivity and effective thermal diffusivity decrease linearly. This is suggestive of fact that 10 at.wt% of indium can be considered as a critical composition at which the alloy becomes, chemically ordered and maximum thermally stable than other composition. Further addition of indium in selenium decreases the values of λ_e and χ_e. The behaviour is explained on the basis of decrease of localized states and increase in disorderness for higher composition indium.     

The adsorption of phosphate from an aquatic environment using metal-loaded orange waste

Phosphate removal from an aquatic environment was investigated using La(III)-, Ce(III)- and Fe(III)-loaded orange waste. The adsorption isotherm, the kinetics of adsorption and the effect of pH on the removal of phosphate have been examined. The % removal of phosphate using La(III)- and Ce(III)-loaded orange waste gel increases with increasing pH within the range of 5-7 but decreases when the pH is increased beyond this range. The equilibrium sorption was observed to be in accordance with Langmuir type adsorption and the maximum adsorption capacity was evaluated as 13.94 mg P/g of dry gel for all the three types of gels. Kinetic studies revealed that 15 h is enough to reach equilibrium in batch experiments. Fixed bed sorption experiments confirmed the continuous phosphate adsorption and elution capability of such simply modified gels. Due to their low cost, availability and significantly high adsorption capability, metal-loaded SOW gels can be effectively employed for the removal of phosphate from water.     

Algorithms for integrated photoelasticity —Axisymmetric cases

The method of integrated photoelasticity can be very elegantly used to determine the stress distribution in the case of torsionless axisymmetry. The mathematical formulation of such problems often yields Abel's integral equation. One of the ways to solve these equations is by approximating either the known (experimentally determined) or the unknown function by polynomials. The integral equation is thus converted to a system of linear, simultaneous algebraic equations with the coefficients of the approximating polynomial as unknowns. The degree of the approximating polynomial cannot be fixeda priori. The present paper postulates a scheme in which the degree of the approximating polynomial is increased in steps of one, starting from one. Solutions are computed for each degree of the polynomial. It is then possible to pick the solution from the available family of solutions. The computational aspect of the exercise can be very easily taken care of by the algorithms proposed and validated in this paper. The over-determined system of simultaneous equations is solved by the method of singular value decomposition (SVD). The proposed method is validated by first applying it to a test problem. Two cases, which are solved earlier, are then analyzed and the results are compared.