Theoretical investigation of dielectric corona pre-ionization TEA nitrogen laser based on transmission line method

This paper models the dielectric corona pre-ionization, capacitor transfer type of flat-plane transmission line traveling wave transverse excited atmospheric pressure nitrogen laser by a non-linear lumped RLC electric circuit. The flat-plane transmission line and the pre-ionizer dielectric are modeled by a lumped linear RLC and time-dependent non-linear RC circuit, respectively. The main discharge region is considered as a time-dependent non-linear RLC circuit where its resistance value is also depends on the radiated pre-ionization ultra violet (UV) intensity. The UV radiation is radiated by the resistance due to the surface plasma on the pre-ionizer dielectric. The theoretical predictions are in a very good agreement with the experimental observations. The electric circuit equations (including the ionization rate equations), the equations of laser levels population densities and propagation equation of laser intensities, are solved numerically. As a result, the effects of pre-ionizer dielectric parameters on the electrical behavior and output laser intensity are obtained.     

Heat and mass transfer and thermodynamic analysis of power-law fluid flow in a porous microchannel

Journal of Thermal Analysis and Calorimetry - Transfer of heat and mass and thermodynamic irreversibilities are investigated in a porous, parallel-plate microreactor in which the working fluid is...     

Reply to “Comments on “Fuzzy fractional order sliding mode controller for nonlinear systems,Commun Nonlinear Sci Numer Simulat 15 (2010) 963–978” ”

The aim of this letter is to confirm the achievements in [1] and answer all the mentioned comments in [2]. Meanwhile some other drawbacks in the comment paper [2] are also presented in this paper.     

Electrocatalytic determination of sumatriptan on the surface of carbon-paste electrode modified with a composite of cobalt/Schiff-base complex and carbon nanotube

The electrochemical oxidation of sumatriptan on the surface of carbon paste electrode modified with multi-walled carbon nanotube and cobalt methyl-salophen complex is studied by using cyclic voltammetry and polarization studies. The results indicate that the drug is irreversibly oxidized in a one electron oxidation mechanism. It was found that the peak potential shifted negatively with increasing pH, confirms that H(+) participate in the oxidation process. The electrode is shown to be very effective for the detection of sumatriptan in the presence of other biological reductant compounds. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of sumatriptan, ascorbic acid and uric acid, which makes it suitable for the simultaneous detection of sumatriptan in the presence of these compounds in clinical and pharmaceutical preparations. It can be concluded that multi-walled carbon nanotube and Shiff base complex have synergic effect on electroacatalytic oxidation of sumatriptan. A linear range of 1-1000μM and detection limit of 0.3μM was obtained for sumatriptan from DPV measurements using this electrode in 0.1M acetate buffered solution of pH 5.0. The electrode has been applied successfully for the determination of sumatriptan in synthetic serum and commercial tablets.     

Efficient iodination of aromatic compounds using potassium ferrate supported on montmorillonite

Potassium ferrate impregnated on montmorillonite is a mild,cheap,and non-toxic reagent for the iodination of phenols, including naphthol,aromatic amines,and heterocyclic substrates in fair to excellent yields by a simple isolation procedure.     

Engineering and Kinetic Stabilization of the Therapeutic Enzyme Anabeana variabilis Phenylalanine Ammonia Lyase

Anabeana variabilis phenylalanine ammonia lyase has just recently been discovered and introduced in clinical trials of phenylketonuria enzyme replacement therapy for its outstanding kinetic properties. In the present study, kinetic stabilization of this therapeutically important enzyme has been explored by introduction of a disulfide bond into the structure. Site-directed mutagenesis was performed with quick-change PCR method. Recombinant wild-type and mutated enzymes were expressed in Escherichia coli, and his-tagged proteins were affinity purified. Formation of disulfide bond was confirmed by Ellman’s method, and then chemical unfolding, kinetic behavior, and thermal inactivation of mutated enzyme were compared with the wild type. Based on our results, the Q292C mutation resulted in a significant improvement in kinetic stability and resistance against chemical unfolding of the enzyme while kinetic parameters and pH profile of enzyme activity were remained unaffected. The results of the present study provided an insight towards designing phenylalanine ammonia lyases with higher stability.     

Ab Initio Study of the Dehydrogenation of 3-Pyrroline, 2,5-Dihydrofuran and 2,5-Dihydrothiophene

Abstract

The nature of the transition state structures of the decomposition of 3-pyrroline (1), 2,5-dihydrofuran (2) and 2,5-dihydrothiophene (3) were investigated usingab initio Molecular Orbital (MO) and Density Factional Theory (DFT) methods. The energy barrierof the decomposition of compound 1 is smaller than compound 2 and compound 2 is smaller than compound 3. The energy barriers for the decomposition of compounds 1–3 are 46.20, 50.17, and 61.34 kcal mol^?1, respectively, which is calculated by B3LYP/6-31G^*//HF/6-31G^* level of theory. Which is ingood agreement with reported experimental data. Contrary to the previously reported data, the distance between the cis-2-and-5-hydrogen atoms in compound 1 is greater than compound 2. The transition-state structures of the decomposition of compounds 1–3 are formed by interaction of the cis-2-and-5-hydrogen atoms. Also, the rings of compounds 1–3 in the transition state structures are puckered.