Synthesis of new triphenodithiazine- and indolocarbazolediones of biological interest

Tetrabromo-p-benzoquinone reacted with excess aromatic amines to give 2,5-dirylamino-3,6-dibromo-p-benzoquinones. The latter molecules on heating with sodium sulfide in alcohol in the presence of air gave triphenodithiazinediones. Heating with copper powder in nitrobenzene transformed these compounds into the respective indolocarbazolediones. Comparative antimicrobial and antifungal activities of the studied compounds were determined and discussed.     

Synthesis and Reactions of 5-Amino-3-(3-methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-7-phenyl-7 H -thiazolo[3,2- a ]pyrimidine-6-carbonitrile

5-Amino-3-(3-methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-7-phenyl-7H-thiazolo[3,2-a]pyrimidine-6-carbonitrile was synthesized via the reaction of 4-(2-aminothiazol-4-yl)-3-methyl-1-phenyl-2-pyrazolin-5-one with benzylidene malononitrile and was then transformed to related fused heterocyclic systems. The antifungal and antibacterial studies revealed in some cases excellent biocidal properties.     

Langmuir-Blodgett films of cellulose nanocrystals: preparation and characterization

The goal of this work is the preparation of monolayers of cellulose I nanocrystals providing flat crystalline cellulose surfaces. Suspensions of cellulose nanocrystals were prepared by hydrolyzing ramie and tunicin fibers with sulfuric acid. Due to surface grafted sulfate groups, the negatively charged, rod-like cellulose nanocrystals were found to form stable layers at the air-water interface in the presence of a cationic amphiphilic molecule such as dioctadecyldimethylammonium (DODA) used in this work. These layers were formed at different cellulose-DODA weight ratios, compressed and analyzed by tensiometry, ellipsometry and Brewster angle microscopy. At low cellulose concentrations the layers are discontinuous, becoming dense and homogeneous upon reaching a critical weight ratio, which depends on the aspect ratio of the cellulose nanocrystals. After transfer onto silicon wafers, the surface composition and morphology as well as the thickness of the films were examined by X-ray photoelectron spectroscopy, ellipsometry and atomic force microscopy. The results indicate that they are monolayer films, well structured, relatively smooth and pure. These films offer a crystalline and easily reproducible model cellulose surface.     

Polyacrylic acid/polyaniline composite as efficient adsorbent for uranium extraction from nuclear industrial effluent

Journal of Radioanalytical and Nuclear Chemistry - Polyacrylic acid/polyaniline composite (a three-dimensional cross-linked hydrophilic chelating polymeric sorbent) was improved for promoted...     

Reactions of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene and 2‐amino‐3‐cyano‐4,7‐diphenyl‐5‐methyl‐4H‐pyrano[2,3‐c] pyrazole with phenylisocyanate,carbon disulfide,and thiourea

2‐Amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene 1a or 2‐amino‐3‐cyano‐4,7‐di‐ phenyl‐5‐methyl‐4H‐pyrano[2,3‐c]pyrazole 2a reacted with phenylisocyanate in dry pyridine to give 2‐(3‐phenylureido)‐3‐cyanobenzo[b]thiophene 1b or 2‐disubstituted amino‐3‐cyanopyranopyrazole 2b derivative. However, when 1a and 2a were refluxed with carbon disulfide in 10% ethanolic sodium hydroxide solution, they afforded the thieno[2,3‐d]pyrimidin‐2,4‐dithione derivative 5 in the former case, 2,4‐dicyano‐1,3‐bis(dithio carboxamino)cyclobuta‐1,3‐ diene 6 and pyrazolopyranopyrido[2,3‐d]pyrimidin‐ 2,4‐dithione derivative 7 in the latter one. Treatment of 2a with thiourea in refluxing ethanol in the presence of potassium carbonate gave 2,2′‐dithiobispyrimidine derivative 9 (major) in addition to pyranopyrazole derivative 10 and 2,2′‐dithiobis ethoxypyrimidine derivative 11 in minor amounts. The structures of all products were evidenced by microanalytical and spectral data. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:6–11, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20070     

Two-dimensional problem of a two-temperature generalized thermoelastic half-space subjected to ramp-type heating

In this work, we will consider a half-space filled with an elastic material, which has constant elastic parameters. The governing equations are taken in the context of the theory of two-temperature generalized thermoelasticity. A linear temperature ramping function is used to more realistically model thermal loading of the half-space surface. The medium is assumed initially quiescent. Laplace and Fourier transform techniques are used to obtain the general solution for any set of boundary conditions. The general solution obtained is applied to a specific problem of a half-space subjected to ramp-type heating. The inverse Fourier transforms are obtained analytically while the inverse Laplace transforms are computed numerically using a method based on Fourier expansion techniques. Some comparisons have been shown in figures to estimate the effect of the ramping parameter of heating.     

Identities of arithmetic type between values of the theta function associated to a lattice in ℝ d and its derivatives

In this paper, we introduce a notion of similarly self dual lattice in a d-dimensional Euclidean space and a classical Jacobi theta function is associated to such a lattice. We establish identities of arithmetic type between values of this theta function and its successive derivatives. This work can be related to the spectral theory of the Landau operators.      

A second-order boundary value problem with impulsive effects on an unbounded domain

We study a second-order nonlinear differential equation on an unbounded domain with solutions subject to impulsive conditions and the Sturm–Liouville type boundary conditions. The existence results are obtained via applications of Krasnosel’ski?’s fixed point theorem for the sum of a completely continuous operator and a contraction.     

Series and integral representations of the Taylor coefficients of the Weierstrass sigma-function

We provide two kinds of representations for the Taylor coefficients of the Weierstrass σ-function σ(?;Γ) associated to an arbitrary lattice Γ in the complex plane \(\mathbb{C}=\mathbb{R}^{2}\) , the first one in terms of the so-called Hermite–Gauss series over Γ and the second one in terms of Hermite–Gauss integrals over \(\mathbb{C}\) .