Method of most probable distribution: New solutions and results

The variational conditions implied by the most probable equilibrium distribution for a dilute gas are set up exactly in terms of the digamma function without necessarily invoking a Stirling approximation. Through a sequence of lemmas it is proved that, at any given kinetic temperature, there are three classes of self-consistent solutions characterized by the parameterβ \( \beta \bar \gtrless 0 \) 0 and by non-Maxwellian tails. These ambiguities persist even for a free ideal gas.     

Quantification of Eugenol in Cinnamomum tamala Nees and Eberm. Leaf Powder by High-Performance Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - Eugenol is used as a flavor in the food industry, has a variety of biological activity, and can serve as a biomarker. Because...     

Convergence of the inner-outer iteration scheme

In this paper, we analyse the convergence of the inner-outer iteration scheme for determining the multiplication factor and the fundamental mode neutron distribution within the finite differenced approximation to the multi-group neutron diffusion equation. We show that a set of four sufficient conditions, on the number of inner iterations to be performed, can be obtained which would guarantee the convergence of the scheme. A few special cases are analysed where we determine the minimum number of inner iterations required for convergence.

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Zusammenfassung Gegenstand der Arbeit ist die Konvergenz des inner-outer Iterationsschemas zur Berechnung des Multiplikationsfaktors und der Grundverteilung der Neutronen in der Differenzenapproximation zur eingruppigen Neutronendiffusionsgleichung. Wir erhalten vier Bedingungen für die Anzahl der auszuführenden äußeren Iterationen, die zur Erzielung der Konvergenz hinreichen. In einigen Spezialfällen bestimmen wir auch die Minimalzahl der für die Konvergenz erforderlichen inneren Iterationen.

     

Capillary Electrophoretic Determination of Gatifloxacin from Pharmaceutical Preparation

Capillary zone electrophoresis has been used for the determination of gatifloxacin from its pharmaceutical preparation (tablets), using fused silica capillary. Separation was performed after hydrodynamic injection; the separation was achieved by applying 21 Kv voltage. Phosphate buffer solution (pH 9.5) was used as separation electrolyte. Detection was at 280 nm using a UV- detector. Under these experimental conditions the analysis takes 8 min. A linearity range for gatifloxacin was between 20.0 g mL^–1 to 60.0 g mL^–1. The method was validated and was found to be specific, precise, accurate, reproducible and robust and can be applied for the routine analysis of gatifloxacin from formulation and bulk drug.     

Oxidation of tantalum metal by lead chromate

Differential thermal analysis and gravimetry techniques have been used in the investigation of the tantalum/lead chromate pyrotechnic composition for a range of fuel/oxidant mixtures. Studies include investigation of tantalum and lead chromate individually as well as co-precipitated mixtures, when heated up to approximately 900°C in air and in nitrogen. The kinetics of oxidation of metallic fuels by metal oxides is one of the most important parameters in determining the utility of any metal oxide system in pyrotechnic applications. Infrared spectroscopy has been utilised in an attempt to characterise the reaction products in air and in nitrogen atmosphere.     

Symmetry and selection rules in the Raman spectra of carbon nanotubes

The symmetry of achiral single-walled (n,0) and (n,n) carbon nanotubes (CNTs) was examined and the frequencies and types of vibrations allowed in the Raman spectra were calculated. The vibrational spectrum was evaluated as the eigenvalues of the dynamical matrix at the -point of the Brillouin zone. The selection rules for the Raman active vibrations were estimated by the values of the matrix elements responsible for the intensities of corresponding vibrational transitions. The (n,n)-CNTs with even and odd n values are characterized by five and six allowed Raman active vibrations, respectively. The number of Raman active vibrations for (n,0)-CNTs is five if n is even and eight if n is odd. Detailed analysis of the results obtained is presented for the (10,10)-CNT as an example.     

Quantitative evaluation of Lewis acidity of metal ions with different ligands and counterions in relation to the promoting effects of Lewis acids on electron transfer reduction of oxygen

The g(zz) values of ESR spectra of superoxide (O(2)(.-) complexes of metal ion salts acting as Lewis acids with different ligands and counterions were determined in acetonitrile at 143 K. The binding energies (DeltaE) of (O(2)(.-)/Lewis acid complexes have been evaluated from deviation of the g(zz) values from the free spin value. The DeltaE value is quite sensitive to the difference in the counterions and ligands of metal ion salts acting as Lewis acids. On the other hand, the fluorescence maxima of the singlet excited states of 10-methylacridone/Lewis acid complexes are red-shifted as compared with that of 10-methylacridone, and the relative emission energies (Deltahnu(f)) vary significantly depending on the Lewis acidity of metal ion salts with different counterions and ligands. The promoting effects of Lewis acids were also examined on electron transfer from cobalt(II) tetraphenylporphyrin to oxygen in acetonitrile at 298 K, which does not occur in the absence of Lewis acids under otherwise the same experimental conditions. Both DeltaE and Deltahnu(f) values are well correlated with the promoting effects of Lewis acids on the electron transfer reduction of oxygen. Such correlations indicate that DeltaE and Deltahnu(f) values can be used as quantitative measures of Lewis acidity of metal ion salts with different ligands and counterions. The Lewis acidity thus determined can also be applied to predict the promoting effects of Lewis acids on organic synthesis.     

Radiometric,potentiometric and conductometric measurements of the solubility and solubility product of europium trifluoride

The solubility and solubility product of europium trifluoride were measured by radiometric, potentiometric and conductometric methods. There are significant differences in the values of both solubility and solubility product obtained by the three different techniques. Due to reasons discussed in the text, radiometric values seem to be more acceptable than the others. The thermodynamic functions such as ΔH⁰, ΔG⁰ and ΔS⁰ for the dissolution process were also measured. The positive values of ΔH⁰ and ΔG⁰ and the negative value of ΔS⁰ are indicative of the slight solubility of EuF₃. The dependence of solubility on pH and also on the fluoride concentration has also been studied. It was confirmed that europium forms a monofoluoride complex in aqueous solution. The stability constant of this complex was estimated.     

Simultaneous HPTLC Determination of Clotrimazole and Tinidazole in a Pharmaceutical Formulation

JPC – Journal of Planar Chromatography – Modern TLC - An HPTLC method for simultaneous determination of clotrimazole and tinidazole in a pharmaceutical formulation has been developed...