New explicit approximate solution of MHD viscoelastic boundary layer flow over stretching sheet

In this paper, the study the momentum and heat transfer characteristics in an incompressible electrically conducting non‐Newtonian boundary layer flow of a viscoelastic fluid over a stretching sheet. The partial differential equations governing the flow and heat transfer characteristics are converted into highly nonlinear coupled ordinary differential equations by similarity transformations. The resultant coupled highly nonlinear ordinary differential equations are solved by means of, homotopy analysis method (HAM) for constructing an approximate solution of heat transfer in magnetohydrodynamic (MHD) viscoelastic boundary layer flow over a stretching sheet with non‐uniform heat source. The proposed method is a strong and easy to use analytic tool for nonlinear problems and does not need small parameters in the equations. The HAM solutions contain an auxiry parameter, which provides a convenient way of controlling the convergence region of series solutions. The results obtained here reveal that the proposed method is very effective and simple for solving nonlinear evolution equations. The method is straightforward and concise, and it can also be applied to other nonlinear evolution equations in physics. Copyright © 2012 John Wiley & Sons, Ltd.     

Estimating parameters of a k-factor GIGARCH process

Some crucial time series of market data, such as electricity spot prices, exhibit long-memory, in the sense of slowly-decaying correlations combined with heteroskedasticity. To be able to modelize such a behaviour, we consider in this Note the k-factor GIGARCH process and we propose two methods to address the related parameter estimation problem. For each method, we develop the asymptotic theory for the estimation. To cite this article: A.K. Diongue, D. Guégan, C. R. Acad. Sci. Paris, Ser. I 339 (2004).     

On Almost Valuation and Almost Bézout Rings

In this paper we extend the notion of almost valuation and almost Bézout domains to arbitrary commutative rings, and we investigate the transfer of these properties to trivial ring extensions and amalgamated algebras along an ideal. Our aim is to provide new classes of commutative rings satisfying these properties. As an immediate consequence, we show the failure of Anderson–Zafrullah's theorem on the integral closure of an almost valuation domain beyond the context of integral domains.     

Synthesis of Some New Thiazoles and Pyrazolo[1,5-a]pyrimidines Containing an Antipyrine Moiety

Ethyl 2-{2-[4-(2,3-dimethyl-5-oxo-1-phenyl-3-(pyrazolin-4-yl)]-2-cyano-1-(phenylamino)vinylthio}-acetate, 2-[4-(2,3-dimethyl-5-oxo-1-phenyl-(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]2-(4-oxo-3-phenyl-(1,3-thiazoilidin-2-ylidene))ethanenitrile, 2-[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]-2-(4-methyl-3-phenyl(1,3-thiazolin-2-ylidene))ethanenitrile, 2-(5-acetyl-4-methyl-3-phenyl(1,3-thiazolin-2-ylidene))-2-[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]ethanenitrile, and ethyl 2-(cyano(4-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)thiazol-2-yl)methylene)-2,3-dihydro-4-methyl-3-phenylthiazole-5-carboxylate were synthesized by treatment of 2-(4-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)thiazol-2-yl)-3-mercapto-3-(phenylamino)-acrylonitrile with appropriate halo ketones or halo esters. Also, 4-{2-[5,7-dimethyl-2-(phenylamino)(7a-hydropyrazolo[1,5-a]pyrimidin-3-yl](1,-thiazol-4-yl)}-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one derivatives were synthesized via reaction of 4-{2-[5-amino-3-(phenylamino)pyrazolin-4-yl](1,3-thiazol-2-yl)}-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one with β-diketone or β-keto ester. All synthesized compound were established by elemental analysis, spectral data, and alternative synthesis whenever possible.     

Synthesis of Some New Thieno[2,3-b]pyridines,Pyrimidino[4′,5′:4,5]thieno[2,3-b]-pyridines,and 2,3-Dihydro-1,3,4-thiadiazoles

Thieno[2,3-b]pyridines were synthesized from 6-benzofuran-2-yl-4-phenyl-2-sulfanylpyridine-3-carbonitrile and each of chloro acetone, ethyl chloroacetate, ω -bromoacetophenone, and chloroacetonitrile. These compounds were conveniently converted into novel pyrido[4′,5′:4,5]thieno[3,2-d]pyrimidines. Also, 2,3-dihydro-1,3,4-thiadiazole was synthesized from hydrazonoyl halides and 2-benzofuran-2-yl-3-(phenylamino)-3-thioxopropanenitrile. The structures of the products have been elucidated by elemental analyses, spectral data studies, and alternative syntheses whenever possible. The newly synthesized compounds were tested towards microorganisms.     

SYNTHESIS OF THE BIOLOGICALLY ACTIVE 5-(INDOLYL-3-METHYLENE)THIAZOLIDINE-2,4-DIONE DERIVATIVES

Abstract

The cycloaddition reaction of the biologically active 5-(indolyl-3-methylene) derivatives of thiazolidi-none-4-thiones 2a-c to acrylonitrile, ethyl acrylate, N-phenylmaleimides and dimethyl fumarate has been evaluated.     

REACTIONS OF HYDRAZONOYL HALIDES 391: SYNTHESIS OF SOME NEW TRIAZOLES AND 2,3-DIHYDRO-1,3,4-THIADIAZOLES

C-acyl-N-phenyllhydrazonoyl halides 1a–ghave been caused to react with 3-(aminomethylthiomethyl)-2H-chromen-2-one in the presence of triethylamine to give triazoles. Also, C-acyl-N-pyrazolylhydrazonoyl chlorides 13a, breact with alkyl carbodithioates (14or 15) a–mafforded 2,3-dihydro-1,3,4-thiadiazoles in good yields. Structures of the new compounds were elucidated on the basis of elemental analyses, spectral data, and alternative methods of synthesis whenever possible.     

REACTIONS WITH 2- (THIOCYANATOACETYL) AND 2-(SELENOCYANATOACETYL)-2′-BENZOFURAN: SYNTHESIS OF SOME NEW THIADIAZOLINE,SELENODIAZOLINE, THIA-DIAZOLO[2,3-b]QUINAZOLINE AND ARYLAZOTHIAZOLE DERIVATIVES

Abstract

Several new thiadiazoline, selenodiazoline, thiadiazolo[2, 3-b]quinazoline and arylazothiazole derivatives were synthesized via the reaction of 2- (thiocyanatoacetyl)-2′-benzofuran with arendiazonium chlorides, nitrous acid, acetic anhydride, benzoyl chloride, diazotised anthranilic acid and its methyl ester and thiourea. The structures of the newly synthesized derivatives were established on the basis of elemental analyses and spectral data studies.     

REACTIONS OF HYDRAZONOYL HALIDES 371: SYNTHESIS OF TRIAZOLO[4,3-a]PYRIMIDINES, 1,3,4-THIADIAZOLES AND 1,3,4-SELENADIAZOLES

1,2,4-Triazolo[4,3-a]pyrimidines, thiadiazolines and selenadiazolines synthesized via reactions of hydrazonoyl halides with each of ethyl 4-(3,4-dimethoxyphenyl)-6-methyl-2-methylthio-3,4-dihydropyrimidine-5-carboxylate (or ethyl 6-(3,4-dimethylphenyl)-4-methyl-2-thio1,3,6-trihydropyrimidine-5-carboxylate), ethyl 4-(2,3-dimethoxyphenyl)- 6-methyl-2-methylthio-3,4-dihydropyrimidine-5-carboxylate, potassium thiocyanate, potassium selenocyanate, and carbodithioates respectively.