M. Srinivasa Reddy

Spectroscopic and dielectric studies on PbO–MoO3–B2O3 glasses incorporating small concentrations of TiO2

This paper deals with the investigation of a variety of physical properties including dielectric constant (over a wide range of frequency and temperature), optical absorption, luminescence, electron spin resonance (ESR) and infrared spectra of a TiO2-doped lead molybdenum borate glass system. The composition chosen for the study is 30PbO–4MoO3–(66–x)B2O3:xTiO2 (with x ranging from 0.2 to 2.0). Quantitative analysis of the results of this study shows that, when the content of TiO2 is around 0.8 mol%, the titanium ions exist predominantly in the tetravalent state and occupy substitutional positions in the glass network. A substantial increase in the insulating strength of these glasses on TiO2 doping has also been observed. When the concentration of TiO2 is increased beyond 0.8 mol%, it is observed that titanium ions exist primarily in the Ti3+ state and molybdenum ions in the Mo5+ state; analysis of the results further suggests that both of these ions participate in the depolymerization of the glass network.

Influence of iron ions on dielectric properties of the PbO–Bi2O3–B2O3 glass system

PbO–Bi2O3–B2O3 glasses containing small concentrations of Fe2O3 (0–1 mol%) were subject to dielectric studies (dielectric constant ε′; loss tan δ; and ac conductivity σ ac) over a wide range of frequency and temperature. From spectroscopic (infrared, optical absorption and ESR spectra) and magnetic susceptibility studies, variations in these properties with dopant ion concentration were analyzed in terms of different oxidation states and iron ion environment in the glass network.

Molecular interaction studies in the binary mixture of 1-ethyl-3-methylimidazolium trifluoromethanesulphonate+1-butanol from density, speed of sound and refractive index measurements

ABSTRACT A molecular interaction study was carried out between the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulphonate and 1-butanol using the experimental values of density, speed of sound and refractive index measurements over the whole composition range as a function of temperature between 298.15 and 328.15 K at atmospheric pressure. The excess/deviation properties such as molar volumes (), partial molar volumes (), partial molar volumes at infinite dilution (), isentropic compressibility (), free length (), speeds of sound (), refractive index () and isobaric thermal expansion coefficient () obtained from the experimental data were fitted into the Redlich–Kister type equation to obtain the binary coefficients and the standard deviations. The excess values clearly indicated the existence of strong molecular interactions between the studied components. A quantitative analysis of these parameters was further supported by IR spectroscopic analysis. In addition, analysis of data of the mixture was done through the Prigogine–Flory–Patterson theory.

Efficacy and tolerability of fixed-dose combination of simvastatin plus ezetimibe in patients with primary hypercholesterolemia: Results of a multicentric trial from India

OBJECTIVE To compare the efficacy and safety of fixed-dose combination (FDC) of simvastatin and ezetimibe vs simvastatin monotherapy in Indian patients with primary hypercholesterolemia. METHODS This multicentric, double-blind, comparative, study conducted in India enrolled 230 patients with hypercholesterolemia (baseline low-density lipoprotein cholesterol [LDL-C] >120 mg/dL for patients on previous hypolipidemic drugs or >135 mg/dL for naïve subjects) were randomly assigned to receive either simvastatin (10 mg/day) or simvastatin (10 mg) plus ezetimibe (10 mg) FDC for 12 weeks. The primary efficacy endpoint was the mean percentage change in LDL-C from baseline to 12 weeks of therapy for simvastatin monotherapy vs simvastatin plus ezetimibe FDC. Secondary efficacy endpoints were mean percentage of changes in total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) from baseline to end of treatment, as well as proportion of patients achieving National Cholesterol Education Program Adult Treatment Panel III target LDL-C levels in each risk category. RESULTS At the end of 12 weeks, the mean percentage reduction from baseline in LDL-C (-33.7%) was significantly greater with simvastatin and ezetimibe FDC compared to simvastatin alone (-26.28%, P < 0.05). Significantly greater percentage of patients (88%, P < 0.001) attained National Cholesterol Education Program Adult Treatment Panel III LDL-C target levels following ezetimibe/simvastatin treatment compared to simvastatin monotherapy (71%). Reductions in TG were significantly greater with ezetimibe/simvastatin than simvastatin (P < 0.001). Increases in HDL-C, and reduction in TC were similar between treatment groups. Safety and tolerability profiles were comparable for both treatments. CONCLUSION Fixed-dose combination of simvastatin and ezetimibe provides a more effective means for reducing LDL cholesterol levels in Indian patients with hypercholesterolemia than simvastatin monotherapy without compromising the safety and tolerability profile.

Volumetric, acoustic, optical and spectroscopic studies of binary mixtures of the ionic liquid, 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide and diethyl carbonate

ABSTRACT The properties, density, speed of sound and refractive index of ‘IL’ [Bmim][NTf2], diethyl carbonate and their binary mixtures are measured over the whole composition range as a function of temperature between 303.15 and 323.15 K at atm. pressure. These values are used to calculate the excess molar volumes, excess partial molar volumes, partial molar volumes at infinite dilution, excess isentropic compressibility, free length, speeds of sound and isobaric thermal expansion coefficient for the mixture. Various rules were used to predict the refractive indices and the data have been compared with the experimental results. These excess properties are fitted to the Redlich–Kister type equation to obtain the binary coefficients and the standard deviations. A qualitative analysis of these parameters indicates strong intermolecular interactions and the interaction increases with the increase in temperature. This was further supported by IR spectroscopy. In addition, analysis of data of the mixture was done through the Prigogine–Flory–Patterson theory.

Molecular interaction studies of binary mixture formed by 2-methoxyethanol and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide-based ionic liquid

ABSTRACT Physicochemical properties such as density (ρ), speed of sound (u) and refractive index (nD) for binary mixture of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with 2-methoxyethanol (2-ME), have been investigated over the whole composition range at different temperatures (298.15–318.15) K and ambient pressure. Additionally the excess properties such as excess molar volume (), excess molar isentropic compressibility (), excess isobaric thermal expansion coefficient (), deviation in refractive index () and partial molar quantities, have been also evaluated, simultaneously these are fitted with Redlich-Kister type equation for acquiring the binary coefficients and standard deviations. The calculated data has been interpreted in terms of various interactions and structural property between organic and ionic liquid molecules upon mixing. ATR-FTIR studies also carried out to know the microscopic interactions. The experimentally obtained excess molar volumes are further analysed with the help of Prigogine-Flory-Patterson (PFP) theory.Physicochemical properties such as density (ρ), speed of sound (u) and refractive index (nD) for binary mixture of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with 2-methoxyethano...

Thermo physical, optical and spectroscopic perspectives of molecular interactions in binary mixtures of Ethyl Lactate and Dimethyl Adipate at T = 303.15–318.15 K and atmospheric pressure

ABSTRACT Molecular interactions are evaluated in the binaries of Ethyl Lactate and Dimethyl Adipate using experimental values of density, ultrasonic velocity and refractive index over entire composition range as a function of temperature from 303.15 to 318.15 K at atmospheric pressure. Excess thermodynamic properties: excess molar volume, excess isentropic compressibility, excess isothermal compressibility, excess free length, excess isobaric thermal expansion coefficient, excess ultrasonic velocity and refractive index deviations are computed and fitted with Redlich-Kister polynomial equation to obtain the binary coefficients and the standard deviations. The existence of specific interactions in the mixture is revealed by excess properties, and further supported by partial molar properties. FTIR analysis ascertains the dominance of packing effect in the studied mixtures. Prediction of refractive index for the mixtures and pure components is done by several mixing rules with the estimation of relative errors. In addition, data are analysed by the Prigogine–Flory–Patterson theoretical model.

The Study of Solute–Solvent Interactions in 1-Butyl-3-Methylimidazolium Hexafluorophosphate + 2-Pyrrolidone from Volumetric, Acoustic, Optical and Spectral Properties

The density (ρ), speed of sound (u) and refractive index (nD) of [Bmim][PF6], 2-pyrrolidone and their binary mixtures were measured over the whole composition range as a function of temperature between (303.15 and 323.15) K at atmospheric pressure. Experimental values were used to calculate the excess molar volumes

Influence of modifier oxide on spectroscopic and thermoluminescence characteristics of Sm3+ ion in antimony borate glass system

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