Convergence analysis of a discontinuous Galerkin method for a sub-diffusion equation

We employ a piecewise-constant, discontinuous Galerkin method for the time discretization of a sub-diffusion equation. Denoting the maximum time step by k, we prove an a priori error bound of order k under realistic assumptions on the regularity of the solution. We also show that a spatial discretization using continuous, piecewise-linear finite elements leads to an additional error term of order h ² max (1,logk ^− 1). Some simple numerical examples illustrate this convergence behaviour in practice. We thank the University of New South Wales for financial support provided by a Faculty Research Grant.     

Specific heat and electrical conductivity of deuterated triglycine selenate single crystals

Measurements of the specific heat were carried out on deuterated trigylcine selenate (DTGSe) single crystals to clarify its critical nature near the ferroelectric transition point (T_c ). The results obtained have indicated that DTGSe crystals deuterated by 90% exhibit a first-order phase transition.

This paper presents also the electrical conductivity (δ) of DTGSe crystals. The deuterium substitution induces an increase in the Curie point T_c , and a decrease in the conductivity in the para- and ferroelectric phases accompanied by an increase in the activation energy (W) in both phases.     

Synthesis and alkylation of 5‐(3‐chlorobenzo[b]thien‐2‐yl)‐4H‐1,2,4‐triazole‐3‐thiol under classical and microwave conditions. AM1 semiemperical calculations for investigating the regioselectivity of alkylation

Under microwave irradiation (MWI), 5‐(3‐chlorobenzo[b]thien‐2‐yl)‐4H‐1,2,4‐triazole‐3‐thiol ( 3 ) was synthesized in a good yield by intramolecular cyclization of the carbonyl thiosemicarbazide 2. A regioselective S‐alkylation of 3 with benzyl chloride or allyl bromide has been achieved by using triethylamine as a base, while other different basic conditions led to a mixture of bis(alkylated) derivatives N⁴, S‐ and S, N²‐, under both of classical and MWI conditions. The relative stabilities, charge densities, dipole moments and electronic energies of reactants, transition states and intermediates were calculated by the AM1 method and used for investigating the regioselectivity.     

Computational study of decaying annular vortex flow using the Rε/k − ε turbulence model

In this article, we present three dimensional CFD study of turbulent vortex flow in an annular passage using OpenFOAM 1.6. The vortex flow is generated by introducing the flow through a tangential entry to the passage. For the analysis presented in this article, turbulence was modeled using the R_ε/k − ε model, in addition, a comparison between such model with the standard k − ε model was conducted and discussed. The main characteristics of the flow such as vortex structure and recirculation zone were investigated. It was found that flow is subjected to Rankine vortex structure with three forced vortex regimes and a free vortex region near to the outer wall. The phenomenon of vortex decay was investigated by depicting the swirl number trend along the axial direction of the flow domain. It was found that the vortex decay is subjected to an exponential decay behavior. New coefficients for the exponential decay correlation were derived based on local values of velocity components in different radial planes.     

Some spectrophotometric methods for determination of certain antipyretic and antirheumatic drugs

Heating paracetamol in strongly alkaline medium with 4-nitrosoantipyrine gives a red colour with maximum absorption at 515 nm. Mefenamic and flufenamic acids can be determined colorimetrically after extraction as ion-pairs with Methylene Blue.     

Biphenyl esters and biflavonoids from the fruits of <Emphasis Type="Italic">Schinus terebenthefolus</Emphasis>

Two new biphenyl esters and three biflavonoids were isolated from the aqueous methanol extract of the fruits of Schinus terebenthefolus. The spectral data of tetrahydrorobustaflavone have been recorded and assigned for the first time. Characterization of the structures was achieved by various spectroscopic methods.Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 369–371, September–October, 2004.     

Determination of trace elements in soil and plants in the Orontes basin of Syria by using instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) have been used for the determination of some major, minor and trace elements (As, Cr, Co, Ni, Zn, Sb, Sc, Ce, Ti, Fe, Mn and V) in various plant leaves together with their soil. The accuracy of the measurements have been evaluated by analyzing a number of plant and soil reference materials, precision have been estimated by triplicate analysis of the sample as well as that of the reference material. The obtained accurate and reliable data of some trace elements on microgram level for plants and soil will serve as baseline values and will be helpful to monitor the changes in the trace element content of soil and plant leaves.The authors are thankful to Prof. I. Othman General Director of AECS for his encouragement and his support.     

Molecular Docking Study of Newly Synthesized Thiopyrimidines as Antimicrobial Agents Targeting DNA Gyrase Enzyme

A new series of thiopyrimidine‐5‐carbonitrile derivatives were synthesized and the chemical identity of them was established on the basis of spectral methods. The antimicrobial properties of all derivatives were investigated against Gram‐positive and Gram‐negative bacteria as well as fungal strains. The results of the antimicrobial screening showed that compounds 4 , 11 , and 12 have a higher and broad spectrum efficacy against all the tested organisms in comparison with the reference drugs. Interestingly, the most active compounds 4 and 12 showed good binding assay results with Escherichia coli DNA gyrase comparable to that of the reference, methotrexate. Furthermore, a molecular docking study of these compounds was carried out to investigate their binding pattern with the target, DNA gyrase.     

Determination of trace elements in soil and plants in the Orontes basin of Syria by using instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) have been used for the determination of some major, minor and trace elements (As, Cr, Co, Ni, Zn, Sb, Sc, Ce, Ti, Fe, Mn and V) in various plant leaves together with their soil. The accuracy of the measurements have been evaluated by analyzing a number of plant and soil reference materials, precision have been estimated by triplicate analysis of the sample as well as that of the reference material. The obtained accurate and reliable data of some trace elements on microgram level for plants and soil will serve as baseline values and will be helpful to monitor the changes in the trace element content of soil and plant leaves.The authors are thankful to Prof. I. Othman General Director of AECS for his encouragement and his support.     

Effects of an admixture and fast neutron irradiation on thermal properties of sodium potassium sulphate crystals

The differential thermal analysis curves and the specific heat at constant pressure,C _p, of pure and Cu²⁺-doped sodium potassium sulphate crystals were studied. Different neutron fluences were used up to 2.6×10¹⁰ n/cm², in the temperature range 300–500 K. Impurity incorporation generally increased the specific heat up to a maximum at 5% Cu²⁺ content. The peaks for the doped crystals were shifted to lower temperature as a result of neutron irradiation. This behaviour is discussed on the basis of defects induced by irradiation.

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Zusammenfassung Es wurden die DTA-Kurven und die spezifische Wärme bei konstantem DruckC _p von reinen, mit Cu²⁺ versetzten Natriumkaliumsulfatkristallen untersucht. Im Temperaturbereich 300–500 K wurden verschiedene Neutronenströme bis zu 2,6×10¹⁰ n/cm² verwendet. Der Einbau von Verunreinigungen erhöht im allgemeinen die spezifische Wärme bis zu einem Maximum bei einem Cu²⁺ Gehalt von 5%. Im Ergebnis der Neutronenbestrahlung verschieben sich die Peaks für die versetzten Kristalle in Richtung niedrigerer Temperaturen. Dieses Verhalten wird auf der Basis strahlungsinduzierter Defekte besprochen.

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_p . 300–500 2,6 · 10¹⁰ n/². 5%. , . , .

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It is a great pleasure for us to express our deepest gratitude to Prof. Dr. Younis S. Selim for his guidance throughout this work and for providing the irradiation facilities.