| 1 | CaMoO_4:Dy^(3+),K^+ near White Light Emitting Phosphor:Structural,Optical and Dielectric Properties显示文摘Undoped,Dy^(3+) doped and Dy^(3+),K^+ codoped calcium molybdate phosphors have been synthesized by solid-state reaction method.X-ray diffraction studies reveal the tetragonal structure of the prepared phosphors having crystallite size 15-50 nm.Scanning electron microscopy(SEM) studies reveal the morphology and crystallite size of the prepared phosphors.Photoluminescence studies indicate that there are blue and yellow emissions at 489 and 576 nm,respectively corresponding to Dy^(3+) ion.The introduction of K^+ ion significantly influences the blue and yellow emissions which causes the near white light emission from this codoped phosphor.The intense absorption peak of the codoped phosphor at 210 nm is attributed to the band gap and a shoulder at 240 nm appears due to charge transfer from oxygen ions to neighbouring molybdenum ions. The band gap of the codoped phosphor is calculated as 5.5 eV from the absorption studies.The dielectric properties such as permittivity and dielectric loss are studied as a function of frequency. | S.K.Sharma S.Dutta S.Som P.S.Mandal | 2013 | Journal of Materials Science & Technology2013，29，7： | 2 |
| 2 | A MATHEMATICAL THEORY FOR LES CONVERGENCE显示文摘Practical simulations of turbulent processes are generally cutoff,with a grid resolution that stops within the inertial range,meaning that multiple active regions and length scales occur below the grid level and are not resolved.This is the regime of large eddy simulations(LES),in which the larger but not the smaller of the turbulent length scales are resolved.Solutions of the fluid Navier-Stokes equations,when considered in the inertial regime,are conventionally regarded as solutions of the Euler equations.In other words,the viscous and diffusive transport terms in the Navier-Stokes equations can be neglected in the inertial regime and in LES simulations,while the Euler equation becomes fundamental.For such simulations,significant new solution details emerge as the grid is refined.It follows that conventional notions of grid convergence are at risk of failure,and that a new,and weaker notion of convergence may be appropriate.It is generally understood that the LES or inertial regime is inherently fluctuating and its description must be statistical in nature.Here we develop such a point of view systematically,based on Young measures,which are measures depending on or indexed by space time points.In the Young measure dν(ξ) x,t,the random variable ξ of the measure is a solution state variable,i.e.,a solution dependent variable,representing momentum,density,energy and species concentrations,while the space time coordinates,x,t,serve to index the measure.Theoretical evidence suggests that convergence via Young measures is sufficiently weak to encompass the LES/inertial regime;numerical and theoretical evidence suggests that this notion may be required for passive scalar concentration and thermal degrees of freedom.Our objective in this research is twofold:turbulent simulations without recourse to adjustable parameters(calibration) and extension to more complex physics,without use of additional models or parameters,in both cases with validation through comparison to experimental data. | H.Lim T.Kaman V.Mahadeo J.Glimm S.Dutta D.H.Sharp B.Plohr | 2012 | Acta Mathematica Scientia2012，32，1： | 0 |
| 3 | 不同来源的芦荟对酪氨酸酶的抑制作用(英文)显示文摘In this study, lyophilized and methanolic extracts of aloe gel from different germplasms were evaluated for their potential to inhibit mushroom tyrosinase activity. The results showed potent inhibitory effect of Aloe vera gel extracts on L-dihydroxyphenylalanine(L-DOPA) oxidation catalyzed by tyrosinase in a dose-dependent manner. Significant differences in % inhibition of tyrosinase among the extraction methods and the germplasms were observed. The relative performance of the germplasms was evaluated with the help of posthoc multicomparison test. The methanolic extract was more effective than the lyophilized crude gel in all the germplasms. The inhibitory effect of the lyophilized gel and methanolic extract tested from five germplasms followed the order: RM > TN > S24 > OR > RJN. The germplasm RM showed the highest tyrosinase inhibition, and the maximum % inhibition noted was 26.04% and 41.18%, respectively for the lyophilized and methanolic extracts at 6 mg·mL–1concentration. Lineweaver-Burk plots of the different concentrations of L-DOPA in the absence and presence of lyophilized gel extract showed competitive inhibition of mushroom tyrosinase in all the germplasms. This study suggests that the germplasm RM could potentially be used for the isolation and identification of the effective tyrosinase inhibitory component, and ascertains the critical role of selecting the best source of germplasm for natural product isolation and characterization. | S.Dutta Gupta S.K.Masakapalli | 2013 | 中国天然药物2013，11，6： | 0 |
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