Synthesis of pyridyl- and quinolyl-substituted 2-aminothiazoles

Five 2-amino-4-(x-pyridyl)- and 2-amino-4-(x-quinolyl)thiazoles have been synthesized by the condensation of thiourea with bromoacetylpyridines and -quinolines. The reaction of pyridyl pyridylmethyl ketones with thiourea and halogens produced four 2-aminothiazoles possessing pyridyl substituents in 4- and 5-positions on the thiazole ring. Treatment of N-(3-pyridyl)- and N-(3-quinoiyl)thiourea with α-bromoketones gave seven new 2-(3-pyridyl)amino- and 2-(3-quinolyl)aminothiazoles. The ultraviolet spectra of the pyridyl- and quinolyl- substituted 2-aminothiazoles were recorded.     

Acrylic Terpolymer-Based Blends with Improved Properties

Blending of acrylic terpolymer (AT) with vinyl acetate-vinyl chloride (VAc-VC) copolymer, polyvinyl alcohol (PVA) polymer, and polyvinyl acetate (PVAc) polymer, respectively, resulted in sealant compositions with improved properties and enhanced outdoor weathering resistance. The morphology of these blends was studied by SEM, energy-dispersive x-ray analysis (EDXA), and DSC. The blends are heterogeneous and consist of a continuous phase which is either pure or mixed AT and a particulate phase having the morphology of the added component. The particulate phase of AT and AT-(VAc-VC) copolymer blends contains mixed AT, whereas that of AT-PVA and AT-PVAc does not. The AT-based blends have generally improved mechanical properties (e.g., ultimate tensile strength, adhesive strength). The improvement in mechanical properties is particularly strong in mixtures of AT with (VAc-VC) copolymer, probably because the added component has greater specific interaction capabilities with AT than the polymers incorporated in the other blends. Whereas the unblended AT has very low outdoor durability, the AT-based blends display enhanced resistance to weathering, as evidenced by substantially higher ultimate tensile strength of weathered specimens than those of the controls (unweathered).     

Dennis supertrace and the Hochschild homology of supermatrices

In this paper, a generalization of the Dennis trace (for matrices) to the case of supermatrices over an arbitrary (not necessarily commutative) superalgebra with unit is constructed. By analogy with the ungraded case, we show how one can use this mapping to construct an isomorphism from the Hochschild homology of the superalgebra to the Hochschild homology of the supermatrix algebra.     

Surfaces Generation by Blending Interpolation on a Triangle with One Curved Side

We use some interpolation operators and some Bernstein type operators for construction of surfaces which satisfy some given conditions.     

Spectrophotometric determination of urea in dermatologic formulations and cosmetics

A rapid, relatively sensitive, and low-cost method for the determination of water-soluble urea content in dermatological therapy products and cosmetics is proposed using a new spectrophotometric assay with water as the only extraction solvent. Spectrophotometric methods involve addition of a known excess of bromate to urea in an acid medium, followed by the determination of residual bromine and chlorine reacting with methyl orange and measurement of absorbance at 505 nm. The absorbance increases linearly with urea concentration (r = 0.9998). The systems obey Beer's law for 6 - 90 microg ml(-1). The calculated apparent molar absorbance values are found to be 4.537 x 10(3) dm(3) mol(-1) cm(-1) and the Sandell's sensitivity is 0.013 microg cm(-2). The variables affecting the rate of the reaction were investigated. The relative standard deviation for five-replication determination of 60 microg ml(-1) urea was 2.1% and the detection limit of the method is 0.34 ng ml(-1).     

Polynomial Spline Functions of Even Degree Approximating the Solutions of (Delay) Differential Equations II

The natural spline functions of even degree introduced in [1] are used or the numerical solution of delay differential equations.     

Approximation by fuzzy B-spline series

We study properties concerning approximation of fuzzy-number-valued functions by fuzzy B-spline series. Error bounds in approximation by fuzzy B-spine series are obtained in terms of the modulus of continuity. Particularly simple error bounds are obtained for fuzzy splines of Schoenberg type. We compare fuzzy B-spline series with existing fuzzy concepts of splines.     

Thermal stability of acrylonitrile/chlorosulphonated polyethylene rubber blend

The properties of chlorosulphonated polyethylene (CSM) rubber, acrylonitrile rubber (NBR) and their blend (50/50 w/w) were studied. Fourier transform infrared (FTIR) studies supported that CSM/NBR rubber blend is self curable, when cross-linking takes place between acrylonitrile groups of NBR and –SO₂Cl groups or in situ generated allyl chloride moieties of CSM. The thermal stability of vulcanizates was analyzed in nitrogen by thermogravimetry. It was found that the initial degradation temperature of elastomer based on CSM rubber is lower than of pure NBR rubber. By adding NBR to CSM rubbers, the degradation temperature of crosslinked material increased, indicating higher thermal stability. The activation energy for the degradation are determined using the Arrhenius equation The activation energies for the rubber blends are higher than for elastomers based on pure rubbers. It was found that the mass loss of the blends at any temperature was between those of the pure rubbers. The differential scanning calorimetry (DSC) was used for the glass transition temperature determination. It is estimated thermodynamic immiscibility of NBR/CSM blend based on noticed two different glass transition temperatures, corresponding to CSM and NBR rubbers.