Synthesis of 3,4,5-substituted furan-2(5<Emphasis Type="Italic">H</Emphasis>)-ones using Al-doped ZnO nanostructure

Al-doped ZnO nanostructures were prepared via a simple precipitation method and were characterized by several techniques including XRD, TEM, EDX, UV–Vis, and DLS. All XRD patterns show the hexagonal single-phase structure of pure and Al-doped ZnO nanopowders without impurity. The samples consist of particles with average sizes ranging from 53 to 60 nm measured by DLS technique. Next, the catalytic activity of pure and Al-doped ZnO nanopowders was investigated in terms of synthesis of 3,4,5-substituted furan-2(5H)-one derivatives using the three-component reaction of aldehydes, aromatic amines, and acetylenic esters. This procedure has advantages such as high yields, simple methodology, and easy work-up.     

Gallium-complex of anguibactin, a siderophore from fish pathogen Vibrio anguillarum

The crystal structure determination of the Ga(III) complex of racemized anguibactin (C₁₅H₁₆N₄O₄S) confirms the previously predicted chemical structure of this novel siderophore isolated from the fish pathogenic bacterium, Vibrio anguillarum 775. The structure of the complex consists of a dimeric binuclear unit, (C₁₅H₁₄N₄O₄S·CH₃O)₂Ga₂ which possesses a crystallographic center of symmetry. Each Ga ion forms a distorted octahedral coordination using one of the dihydroxy catechol O atoms, the thiazoline nitrogen, the hydroxamate (N–O) group and the nonprotonated nitrogen atom of the imidazole ring. The coordination sphere is completed by two bridging methoxide oxygen atoms. The dimer is further stabilized by a pair of hydrogen bonds between the second benzohydroxy group and the nitroso oxygen of the hydroxamate group. Crystal data: C₁₅H₁₄N₄O₄SGa·(CH₃O)·(1.5) (CH₃OH), monoclinic, P2₁/n, a = 16.890(4), b = 11.680(3), c = 11.227(3)Å, = 110.29(4)°, V = 2077.4(9)ų, Z = 4, D _calc = 1.583 g cm^–3, = 1.54178Å.     

Geometry and a priori estimates for free boundary problems of the Euler's equation

In this paper we derive estimates to the free boundary problem for the Euler equation with surface tension, and without surface tension provided the Rayleigh‐Taylor sign condition holds. We prove that as the surface tension tends to 0, when the Rayleigh‐Taylor condition is satisfied, solutions converge to the Euler flow with zero surface tension. © 2007 Wiley Periodicals, Inc.     

Effect of pulse duration on KrF laser treatment of a polyethersulfone film: cell culture study

KrF laser processing of polyethersulfone (PES) films at three different pulse durations regarding to the change in biocompatibility is presented with cell culture study. Various microstructure and chemistry results were obtained on the surface upon laser irradiation. It is shown that nanoscale hydrophilic ripples significantly affect the adhesion of L929 cells on the surface.     

Melamine trisulfonic acid:A new,efficient and recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones in the absence of solvent

Melamine trisulfonic acid(MTSA) can be used as an efficient and recyclable catalyst for the promotion of the synthesis of 3,4- dihydropyrimidin-2(1H)-ones/thiones(DHPMs) in the absence of solvent.All reactions were performed at 80℃in good to high yields.     

Regioselective iodination of aromatic compounds with potassium iodide in the presence of benzyltriphenylphosphonium perchlorate

A simple and efficient method for the selective iodination of various aromatic compounds by using potassium iodide in the presence of benzyltnphenylphosphonium perchlorate,is reported.This method provides several advantages such as good selectivity between ortho and para positions of aromatic compounds and high yields of the products.     

Microelectrodes modification through the reduction of aryl diazonium and their use in scanning electrochemical microscopy (SECM)

This work is devoted to the study of the electrochemical grafting of nitrophenyl groups onto platinum ultramicroelectrode (UME). The grafting was made using the electrochemical reduction of nitrophenyldiazonium. Our results demonstrate the possibility to reduce the diazonium onto Pt UME. As consequence the electrochemical reduction leads to the attachment of nitrophenyl groups onto the UME surface. Following that, the modified UME was characterized using electrochemical techniques. In addition, the electrochemical response of the modified UME in the presence of reversible redox couple, ferrocene, has been studied. The main remark is that the steady state current observed at the UME is not affected by the presence of the nitrophenyl layers. Finally, from this last point we demonstrate the possibility to achieve scanning electrochemical microscopy (SECM) using modified platinum UME.