Study of The Thermal Decomposition of Some New Cyanine Dispersed Dyes

The structure of the studied compounds was confirmed by elemental analysis, IR and NMR. TG and DTG data were used to study the kinetics of the thermal decomposition process of some new cyanine dispersed dyes derived from 2-[(p-chloro)-styryl]-6-[5-(3-aryl-rhodanine)]-1,2-dihydropyridine. The reaction was found to follow first order mechanism. The activation energy E_a was calculated and used to calculate the thermodynamic parameters enthalpy change (H^*), entropy change (S^*), and free energy change (G^*), related to the thermal decomposition process. Two different calculation methods including Coats—Redfern and Chatterjee were applied to evaluate thekinetic and thermodynamic parameters. Quantum study was performed to support both the structure and the thermal data.This revised version was published online in November 2005 with corrections to the Cover Date.     

Sequential column asymmetric catalysis

Since the introduction of catalysts and reagents on solid-support, researchers have developed new reaction systems to take advantage of their insoluble nature by designing multistep reaction sequences, high-throughput purification techniques, and combinatorial synthesis methods. The continuous flow system is one of these advancements and represents the foundation of a new technique termed sequential column asymmetric catalysis (CAC). In this strategy, reagents and catalysts are attached to a solid-phase support and loaded onto sequentially-linked columns. The substrates are present in the liquid phase that flows through the column. As a substrate encounters each successive column, it grows in complexity. Consequently, one can imagine a number of flow systems that consist of columns attached in series and/or in parallel that synthesize a fairly complex molecule. Herein, we discuss the development of the sequential CAC technique, beginning with the most relevant antecedents.     

Modified variational iteration method

In this Letter, we introduce a modified variational iteration method by inserting some unknown parameters into the correctional functional. The main advantage of this method is that one can avoid the uncontrollability problems, of the nonzero endpoint conditions, encountered in the traditional variational iteration method. Moreover, the method is applied to some nonlinear equations and the numerical solutions reveal that the modified method is accurate and efficient to solve a large class of nonlinear differential equations. Furthermore, the method does not share the drawbacks of the conventional variational iteration method, namely the restriction of the order of the nonlinearity term or even the form of the boundary conditions.     

A modified least squares formulation for a system of first-order equations

Second-order equations in terms of auxiliary variables similar to potential and stream functions are obtained by applying a weighted least squares formulation to a first-order system. The additional boundary conditions which are necessary to solve the higher order equations are determined and numerical results are presented for the Cauchy-Riemann equations.     

Nitriles in heterocyclic synthesis. A novel synthesis of spiropyran-4-ylindolidene derivatives

The structure of the products of reaction of 2-oxo-3-dicyanomethylidene-2,3-dihydroindole ( 1a ) and 2-oxo-3-cyanoethoxycarbonylmethylidene-2,3-dihydroindole ( 1b ) with the pyrazolin-5-one derivatives 2a,b could be established via ¹³C nmr and high resolution ¹H nmr to be the spiropyranylindolone derivatives 5a-d .     

Radiolyse des solutions aqueuses du complexe cerium(III)-acide triethylene tetraaminehexaacetique

Irradiation of cerium III-triethylenetetraaminehexaacetic acid (TTHA) solutions was done. The degradation of the metal chelate was determined. A radiolytic mechanism has been proposed where it has been showed that the degradation is due to the OH radical, while oxidation of trivalent cerium to tetravalent cerium is due to the hydrogen peroxide molecule.      

Separation of cerium,uranium and plutonium using sephadex gel

Adsorption of some fission product elements on sephadex was attained at pH 5.5±0.2. Individual separation of adsorbed radioactive cerium, uranium and plutonium on sephadex was performed using 25 ml of 10^–4M triethylenetetraaminehexaacetic acid (TTHA) at different pH values.