Study of the Reactivity of 6,8‐Dimethyl‐4‐oxo‐4H‐1‐benzopyran‐3‐carboxaldehyde Towards Amino‐6‐oxopyridine‐3‐carboxylate Derivatives

The condensation reactions of 6,8‐dimethyl‐4‐oxo‐4H‐1‐benzopyran‐3‐carboxaldehyde ( 1 ) with equimolar amounts of ethyl 2‐amino‐4‐(4‐chlorophenyl)‐5‐cyano‐1‐[(5,6‐diphenyl‐1,2,4‐triazin‐3‐yl)amino]‐6‐oxo‐1,6‐dihydropyridine‐3‐carboxylate ( 2 ) at different reaction conditions gave different chromanone and chromenone products 3 , 4 , 5 . Also, the condensation reactions of compound 1 with ethyl 5‐cyano‐1,2‐diamino‐4‐(3‐nitrophenyl)‐6‐oxo‐1,6‐dihydropyridine‐3‐carboxylate ( 6 ) in absolute ethanol, dry benzene, acetic acid, and/or dry xylene gave a variety of products 7 , 8 , 9 , 10 depending on the solvent used.     

A highly accurate Jacobi collocation algorithm for systems of high‐order linear differential–difference equations with mixed initial conditions

In this paper, a shifted Jacobi–Gauss collocation spectral algorithm is developed for solving numerically systems of high‐order linear retarded and advanced differential–difference equations with variable coefficients subject to mixed initial conditions. The spatial collocation approximation is based upon the use of shifted Jacobi–Gauss interpolation nodes as collocation nodes. The system of differential–difference equations is reduced to a system of algebraic equations in the unknown expansion coefficients of the sought‐for spectral approximations. The convergence is discussed graphically. The proposed method has an exponential convergence rate. The validity and effectiveness of the method are demonstrated by solving several numerical examples. Numerical examples are presented in the form of tables and graphs to make comparisons with the results obtained by other methods and with the exact solutions more easier. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and Antioxidant,Anti-Inflammatory,and Analgesic Activity of Novel Polycyclic Pyrimido[4,5-b]quinolines

The behavior of the 2-methylthio-pyrimido[4,5-b]quinolin-4-one towards differently substituted amines is reported. Also, the reactivity of 3-aminothiazolo[3′,2′ :1,2]-pyrimido[4,5-b]quinoline-2-carbonitrile towards formic acid, urea, thiourea, formamide, and carbon disulfide is discussed. Some of the synthesized derivatives possess biological activities as anti-inflammatory and analgesic agents. Some of these selective biologically active compounds were screened for antioxidant properties.     

ZnTe/GaAs(2 1 1)B heterojunction valence band discontinuity measured by X-ray photoelectron spectroscopy

Thin ZnTe layers were grown by molecular beam epitaxy on single crystal GaAs(2 1 1)B substrates. Reflection high energy electron diffraction monitored the deoxidation of substrate and entire growth process. Valence band offset was calculated with X-ray photoelectron spectroscopy. Also interface formation of the ZnTe/GaAs was studied. Analysis shows that interface is abrupt and calculated valance band offset is 0.25 ± 0.1 eV and indicates type I alignment. The experimental result agrees well with the theoretical predictions involving interface dipole effect as well as electron affinity rule.     

An interface study of crystalline Fe/Ge multilayers grown by molecular beam epitaxy

Fe/Ge multilayers were grown on single crystal Ge(0 0 1) substrates by molecular beam epitaxy. The structural, electronic and magnetic properties of Fe/Ge have been studied. The analysis shows that Fe grows in a layer-by-layer epitaxial growth mode on Ge(0 0 1) substrates at 150 °C and no intermixing has been observed. Growth of a crystalline Ge film at 150 °C on a single crystal Fe film has been observed. At this temperature Ge films grow by means of the island growth mode according to reflection of high energy electron diffraction patterns. Fe layers of 36 nm thickness, deposited at 150 °C on Ge(0 0 1) substrates, show two magnetization reversal values indicating the growth of Fe in two different crystal orientations. 36 nm thick Fe and Ge layers grown at 150 °C in Ge/Fe/Ge/Fe/Ge(0 0 1) sequence shows ferromagnetic behavior, however, the same structure grown at 200 °C shows paramagnetic behavior.     

Incorporation of Radioactive Wastes in Cement 1. Effect of some Chemicals on Cement Properties

Effects of some chemicals on the cement hardness were examined. Density, water absorption and porosity of cement mixed with some chemicals were determined. Differential thermal analysis, thermogravimetric and infra-red measurements were carried out. Effects on the hardness of cement by the interaction of chemicals were explained. A modification of the cement containers in Egypt is proposed to overcome the chemical effects investigated.     

Estimation of Ra-224 Content in Egyptian Black Sand by the Can- and Alpha-Autoradiography Techniques using LR-115 Plastic Detectors

Sealed can- and alpha-autoradiography techniques were used to estimate the effective and real contents of Ra-224 respectively in Egyptian black sand samples collected from Rosetta City in the Nile Delta at the North Coast of Egypt. The effective Ra-224 content was found to be 15 ± 3 Bq · kg^?1. From the average chemical composition of the black sand samples, the range-energy relation for the alpha-particles of the thorium series was calculated. Assuming radioactive equilibrium, the real Ra-224 content for samples collected from different regions were found to range from 90 to 900 Bq · kg^?1. As a result, the total emanation power was measured and then used to estimate grain diameter of the black sand. The average mass exhalation rate of the different locations in Rosetta City was also estimated.     

Critical Exponents of Kappa Carrageenan in the Coil-Helix and Helix-Coil Hysteresis Loops

The steady-state fluorescence technique was used to study coil-helix (sol-gel) and helix-coil (gel-sol) transitions of the kappa carrageenan-water system with various carrageenan contents. Fluorescence (I) and scattered light (I_sc ) intensities were measured against temperature to determine critical phase transition temperatures and exponents. It was observed that the coil-helix transition temperatures, T_ch were much lower than the helix-coil (T_hc ) transition temperatures due to the hysteresis of the phase transition loops. The gel fraction exponent (β) was measured and found to be in accord with the classical Flory-Stockmayer model.