Derived tubular strongly simply connected algebras

Let be a finite dimensional algebra over an algebraically closed field . Assume for a connected quiver and an admissible ideal of . We study algebras which are derived equivalent to tubular algebras. If is strongly simply connected and has more than six vertices, then is derived tubular if and only if (i) the homological quadratic form is a non-negative of corank two and (ii) no vector of is orthogonal (with respect tho the homological bilinear form) to the radical of .

     

Fluorescent properties of antioxidant cysteine ABZ analogue

The antioxidant properties of aminobenzamide cysteine (ABZ Cys) makes it a molecule that can potentially be used as a drug in oxidative stress related diseases and delivered in the form of a nanoparticles. Here we have studied the photo-physical properties of ABZ Cys, a fluorescent analogue of a popular antioxidant N-acetyl cysteine (NAC). We have compared ABZ Cys steady state and time-resolved fluorescence properties with its parent compounds anthranilic acid and anthranilamide in solution as well as in poly-vinyl alcohol (PVA) polymer films. ABZ Cys did not show any significant shift in absorption after entrapment in PVA film, but there was a shift towards shorter wavelengths in the emission peak compared to the phosphate buffer solution. Fluorescence lifetimes and quantum yields indicated a slight quenching of ABZ Cys fluorescence in comparison to the cysteine-less parent compounds. We also demonstrated that very low concentrations of ABZ Cys, such as 100 nM, are readily detected by a commercial spectrofluorometer. Hence we have established the possible use of ABZ Cys in biomedical applications.     

Constitutive modeling of the mechanics associated with crystallizable shape memory polymers

Shape memory polymers are novel materials that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. The temporary shape is stable and return to the original shape is triggered by a suitable mechanism such as heating. In this paper, we develop constitutive equations to model the mechanical behavior of crystallizable shape memory polymers. Crystallizable shape memory polymers are called crystallizable because the temporary shape is fixed by a crystalline phase, while return to the original shape is due to the melting of this crystalline phase. The modeling is done using a framework that was developed recently for studying crystallization in polymers ([28], [25], [27], [31]) and is based on the theory of multiple natural configurations. In this paper we formulate constitutive equations for the original amorphous phase and the semi-crystalline phase that is formed after the onset of crystallization. In addition we model the melting of the crystalline phase to capture the return of the polymer to its original shape. The model has been used to simulate a typical uni-axial cycle of deformation, the results of this simulation compare very well with experimental data. In addition to this we also simulate circular shear of a hollow cylinder and present results for different cases in this geometry.     

Constitutive modeling of the mechanics associated with crystallizable shape memory polymers

Shape memory polymers are novel materials that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. The temporary shape is stable and return to the original shape is triggered by a suitable mechanism such as heating. In this paper, we develop constitutive equations to model the mechanical behavior of crystallizable shape memory polymers. Crystallizable shape memory polymers are called crystallizable because the temporary shape is fixed by a crystalline phase, while return to the original shape is due to the melting of this crystalline phase. The modeling is done using a framework that was developed recently for studying crystallization in polymers ([28], [25], [27], [31]) and is based on the theory of multiple natural configurations. In this paper we formulate constitutive equations for the original amorphous phase and the semi-crystalline phase that is formed after the onset of crystallization. In addition we model the melting of the crystalline phase to capture the return of the polymer to its original shape. The model has been used to simulate a typical uni-axial cycle of deformation, the results of this simulation compare very well with experimental data. In addition to this we also simulate circular shear of a hollow cylinder and present results for different cases in this geometry. Received: January 5, 2005     

Mesomorphism in chloro substituted isomeric series including chalconyl central bridge

A novel homologous series of thermotropic liquid crystals α-4-(4′-n-alkoxy benzoyloxy phenyl) β-2″-chloro benzoyl ethylenes have been synthesized and studied with a view to understand and establish the effect of molecular structure on liquid crystal (LC) properties with reference to molecular flexibility in isomeric series with differing positional status of same functional group. Novel homologues series consist of 12 homologues C₁ to C_16. C₁, C₂, and C₃ homologues are nonliquid crystals (NLC) and rest of the homologues are liquid crystals. C₁₀ to C₁₆ homologues are enantiotropically smectogenic plus nematogenic and C₄ to C₈ homologues are enantiotropic nematic. The texture of nematogenic derivatives is threaded or schlieren and that of the smectic mesophase are focal conic of the type smectic A or C. Analytical, thermal and spectral data supported molecular structures of novel homologues. Transition temperatures as determine by a hot stage polarizing optical microscopy (POM) were plotted against number of carbon atom present in n-alkyl chain ‘R’ of left n-alkoxy (-OR) group and the phase transition curves Cr–I/M, Sm–N, N–I were obtained on linking like or related points. The odd–even effect is observed for the N–I transition curve and thus transition curves behaved in normal manner. The even-membered nematic transition curve occupied higher position than the odd-membered transition curve. Present series is predominantly nematogenic and partly smectogenic with middle-ordered melting type.     

Scattering of N(2)O on electron impact over an extensive energy range (0.1 eV-2000 eV)

We report electron impact total cross sections, Q(T), for e-N(2)O scattering over an extensive range of impact energies approximately from 0.1 eV to 2000 eV. We employ an ab initio calculation using R-matrix formalism below the ionization threshold of the target and above it we use the well established spherical complex optical potential to compute the cross sections. Total cross section is obtained as a sum of total elastic and total electronic excitation cross sections below the ionization threshold and above the ionization threshold as a sum of total elastic and total inelastic cross sections. Ample cross section data for e-N(2)O scattering are available at low impact energies and hence meaningful comparisons are made. Good agreement is observed with the available theoretical as well as experimental results over the entire energy range studied here.     

Ultrasonic Agitation in Basic Alumina Catalyzed Aldol Condensation of Ketones

The use of ultrasonic irradiation to improve the yield and to shorten the reaction time of aldol dimerization of ketones catalyzed with basic alumina is described.     

Estimating the size of a union of random subsets of fixed cardinality

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Estimating the size of a union of random subsets of fixed cardinality

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Mesomorphism dependence on central bridge and tail ended polar group

Abstract

Severe operation conditions in the agriculture industry and numerous influencing factors complicate the selection of a contact material for switching devices. Attempts have been made to change the Ag-CdO contact material to a less toxic one. Environmentally friendly copper-base contact materials have been created for devices, which operate in agricultural electric systems, meanwhile being low-cost and with pre-set level of reliability in terms of transient resistance.