Static dielectric response of icosahedral fullerenes from C60 to C2160 by an all electron density functional theory

The static dielectric response of C60, C180, C240, C540, C720, C960, C1500, and C2160 fullerenes is characterized by an all-electron density-functional method. First, the screened polarizabilities of C60, C180, C240, and C540, are determined by the finite-field method using Gaussian basis set containing 35 basis functions per atom. In the second set of calculations, the unscreened polarizabilities are calculated for fullerenes C60 through C2160 from the self-consistent Kohn-Sham orbitals and eigen-values using the sum-over-states method. The approximate screened polarizabilities, obtained by applying a correction determined within linear response theory show excellent agreement with the finite-field polarizabilities. The static dipole polarizability per atom in C2160 is (4 Angstrom^3) three times larger than that in C60 (1.344 Angstrom^3). Our results reduce the uncertainty in various theoretical models used previously to describe the dielectric response of fullerenes and show that quantum size effects in polarizability are significantly smaller than previously thought.Comment: RevTex, 3 figure

Static dipole polarizability of C70 fullerene

The electronic and vibrational contributions to the static dipole polarizability of C70 fullerene are determined using the finite-field method within the density functional formalism. Large polarized Gaussian basis sets augmented with diffuse functions are used and the exchange-correlation effects are described within the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA). The calculated polarizability of C70 is 103 Angstrom^3, in excellent agreement with the experimental value of 102 Angstrom^3, and is completely determined by the electronic part, vibrational contribution being negligible. The ratio of polarizabilities of C70 and C60 is 1.26. The comparison of polarizability calculated with only local terms (LDA) in the PBE functional to that obtained with PBE-GGA shows that LDA is sufficient to determine the static dipole polarizability of C70.Comment: IOP style, 1 figur

Antidiabetic and nephroprotective effect of tectona grandis linn. In alloxan induced diabetes

In the present study, effect of ethanolic extract of bark of Tectona grandis Linn. (TG) was evaluated using alloxan induced diabetes and associated renal complication. The diabetes was induced by administration of alloxan to the rats at the dose of 140 mg/kg, i.p. TG was administered to diabetic animals for six weeks and various biochemical parameters in blood and urine (plasma glucose, serum albumin, total protein, and creatinine, urine total protein, urine albumin), tissue parameters (cholesterol and triglyceride in kidney homogenate) and % change in body weight were evaluated along with histopathological study. In present study diabetic animals treated with TG showed significant reduction in the elevated level of plasma glucose (p<0.01) when compared with diabetic control. While considering renal parameters, diabetic animals treated with TG showed significant decrease in serum creatinine (p<0.05), urine albumin and urine total protein levels (p<0.01) and significant increase in serum albumin, total protein and % change in body weight (p<0.01) when compared with diabetic control. Diabetic control showed significant increase in total cholesterol and triglyceride accumulation in kidney, while diabetic animals treated with TG showed significant decrease in levels of total cholesterol (p<0.01) and triglyceride (p<0.05) in the kidney when compared with diabetic control. Diabetic control showed significant mark of glomerulosclerosis and hyalinization which occurs because of severe diabetic condition (diabetic nephropathy). Diabetic groups treated with TG showed absence of the sclerotic lesions produced by diabetic condition. Hence, the results obtained in the present study indicate that Tectona grandis has the potential to treat diabetes mellitus and prevent the associated renal damage

DEVELOPMENT AND VALIDATION OF A STABILITY INDICATING RP-HPLC METHOD FOR THE DETERMINATION OF POTENTIAL DEGRADATION PRODUCTS OF DIFLUPREDNATE IN OPHTHALMIC EMULSION

Objective: The objective of the current study was to develop and validate a simple, robust, precise and accurate RP-HPLC (reverse phase-high performance liquid chromatography) method for the quantitative determination of potential degradation products of Difluprednate (DIFL) in the ophthalmic emulsion.Methods: Chromatographic separation was achieved on the YMC pack ODS-AQ (150× 4.6) mm, 3μm column with a mobile phase containing a gradient mixture of mobile phase A (0.02M Ammonium formate buffer pH 4.5 adjusted with formic acid) and Acetonitrile as mobile phase B, at flow rate of 1.5 ml/min and with UV detection at 240 nm.Results: The peak retention time of DIFL was found at about 17.2 min, the RRT of degradation product-1 (DP-1), degradation product-2 (DP-2), and degradation product-3 (DP-3), were found to be about 0.49, 0.65 and 0.79 respectively (calculated with respect to Difluprednate). Stress testing was performed in accordance with an ICH (international council for harmonisation) guideline Q1A (R2) [1]. The method was validated as per ICH guideline Q2 (R1)[2]. The calibration curve was found to be linear in the concentration range of 0.1 to 0.75 µg/ml for Difluprednate, DP-1, DP-2 and DP-3. The LOD (Limit of detection) was found to be 0.1µg/ml and LOQ (Limit of quantification) of 0.15µg/ml for Difluprednate, DP-1, DP-2 and DP-3 respectively. The recovery from LOQ to 150% was within 90-110%. The forced degradation data confirms the stability indicating the nature of the method.Conclusion: A simple, robust, precise and accurate RP-HPLC method for the quantitative determination of potential degradation products of Difluprednate in the ophthalmic emulsion was developed and validated.Â

The vibrational stability and electronic structure of B80 fullerene-like cage

We investigate the vibrational stability and the electronic structure of the proposed icosahedral fullerene-like cage structure of B80 [Szwacki, Sadrzadeh, and Yakobson, Phys. Rev. Lett. {\bf 98}, 166804 (2007)] by an all electron density functional theory using polarized Gaussian basis functions containing 41 basis functions per atom. The vibrational analysis of B$_{80}$ indicates that the icosahedral structure is vibrationally unstable with 7 imaginary frequencies. The equilibrium structure has $T_h$ symmetry and a {\em smaller} gap of 0.96 eV between the highest occupied and lowest unoccupied molecular orbital energy levels compared to the icosahedral structure. The static dipole polarizability of B$_{80}$ cage is 149 \AAA and the first ionization energy is 6.4 eV. The B$_{80}$ cage has rather large electron affinity of 3 eV making it useful candidate as electron acceptor if it is synthesized. The infra-red and Raman spectra of the highly symmetric structure are characterized by a few absorption peaks.Comment: RevTex, 4 figure

Reasoning About a Service-oriented Programming Paradigm

This paper is about a new way for programming distributed applications: the service-oriented one. It is a concept paper based upon our experience in developing a theory and a language for programming services. Both the theoretical formalization and the language interpreter showed us the evidence that a new programming paradigm exists. In this paper we illustrate the basic features it is characterized by

Positron and positronium affinities in the work-formalism Hartree-Fock approximation

Positron binding to anions is investigated within the work formalism proposed by Harbola and Sahni for the halide anions and the systems Li^- through O^- excluding Be^- and N^-. The toal ground-state energies of the anion-positron bound systems are empirically found to be an upper bound to the Hartree-Fock energies. The computed expectation values as well as positron and positronium affinities are in good agreement with their restricted Hartree-Fock counterparts. Binding of a positron to neutral species is also investigated using an iterative method.Comment: 12 pages, to appear in Physical Review

Full potential LAPW calculation of electron momentum density and related properties of Li

Electron momentum density and Compton profiles in Lithium along $$,$$, and $$ directions are calculated using Full-Potential Linear Augmented Plane Wave basis within generalized gradient approximation. The profiles have been corrected for correlations with Lam-Platzman formulation using self-consistent charge density. The first and second derivatives of Compton profiles are studied to investigate the Fermi surface breaks. Decent agreement is observed between recent experimental and our calculated values. Our values for the derivatives are found to be in better agreement with experiments than earlier theoretical results. Two-photon momentum density and one- and two-dimensional angular correlation of positron annihilation radiation are also calculated within the same formalism and including the electron-positron enhancement factor.Comment: 11 pages, 7 figures TO appear in Physical Review