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41.
2‐Amino‐5‐arylazo‐4‐(2‐chlorophenyl)thiazoles ( 2a‐e ) were prepared by the coupling of aryldiazonium chlorides with 2‐amino‐4‐(2‐chlorophenyl) thiazole ( 1 ). The thioureas 3a‐e were obtained by condensing the arylazothiazoles 2a‐c with the appropriate isothiocyanates. Reaction of 2d with aromatic aldehydes afforded the chalcone analogues 4a‐c . The pyridone derivatives 5a,b were synthesized by reacting the ketone 2d with different aromatic aldehydes, ethyl cyanoacetate and ammonium acetate. On the other hand, 5b was also prepared by cyclizing 4c with ethyl cyanoacetate and ammonium acetate. Furthermore, 6‐chloroimidazo[2,l‐b]‐thiazole 7 was obtained from the acid derivative 6b by treatment with POC13. While, the imidazo[2,l‐b]‐thiazolones 9a‐d were produced by the cyclization of the chloroacetyl derivatives 8a‐d with DMAP/pyri‐dine. Representative examples of the prepared compounds were tested for in vitro antitumor activity against two human tumor cell lines. Some compounds showed activity against brain tumor cell lines. 相似文献
42.
The CMRH method [H. Sadok, Méthodes de projections pour les systèmes linéaires et non linéaires, Habilitation thesis, University of Lille1, Lille, France, 1994; H. Sadok, CMRH: A new method for solving nonsymmetric linear systems based on the Hessenberg reduction algorithm, Numer. Algorithms 20 (1999) 303–321] is an algorithm for solving nonsymmetric linear systems in which the Arnoldi component of GMRES is replaced by the Hessenberg process, which generates Krylov basis vectors which are orthogonal to standard unit basis vectors rather than mutually orthogonal. The iterate is formed from these vectors by solving a small least squares problem involving a Hessenberg matrix. Like GMRES, this method requires one matrix–vector product per iteration. However, it can be implemented to require half as much arithmetic work and less storage. Moreover, numerical experiments show that this method performs accurately and reduces the residual about as fast as GMRES. With this new implementation, we show that the CMRH method is the only method with long-term recurrence which requires not storing at the same time the entire Krylov vectors basis and the original matrix as in the GMRES algorithm. A comparison with Gaussian elimination is provided. 相似文献
43.
Céline Cohen Denis Damiron Sadok Ben Dkhil Eric Drockenmuller Frédéric Restagno Liliane Léger 《Journal of polymer science. Part A, Polymer chemistry》2012,50(9):1827-1833
Well‐defined PDMS telechelics having nitrobenzoxadiazole (NBD) fluorescent probes covalently attached at both chain‐ends were prepared in two steps and a series of fractionation procedures starting from commercially available divinyl‐terminated PDMS having a broad molar mass dispersity. First, thiol‐ene coupling between 6‐mercapto‐1‐hexanol and vinyl chain‐ends allowed the formation of dihydroxy‐terminated PDMS telechelics through the formation of a thioether linkage. The resulting material was then sequentially fractionated using dichloromethane/methanol mixtures to afford several well‐defined dihydroxy‐terminated PDMS fractions having sharp distributions of molar masses (Mn = 99.5–158 kDa and ? < 1.2). The NBD fluorescent probes were then attached at both chain‐ends by N,N′‐dicyclohexylcarbodiimide/4‐(dimethylamino)pyridine esterification coupling between the hydroxyl groups and 6‐(7‐nitrobenzofurazan‐4‐ylamino)hexanoic acid. The resulting fluorescent PDMS telechelics were characterized by SEC, 1H NMR, UV–visible, and fluorescence spectroscopies. These materials are suitable probes to investigate the dynamics of polymer chains in bulk or at interfaces by the fringe pattern fluorescent recovery after photobleaching technique. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
44.
Polybutylcyanoacrylate nanoparticles (PBCA NPs) are candidates for a drug delivery system, which can cross the blood–brain barrier (BBB). Because little is known about their toxicity, we exposed cells to PBCA NPs in vitro and in vivo and monitored their life and death assays. PBCA NPs were fabricated with different surfactants according to the mini-emulsion technique. Viabilities of HeLa and HEK293 cells after NP incubation were quantified by analysing cellular metabolic activity (MTT-test). We then repetitively injected i.v. rhodamine-labelled PBCA NP variations into rats and monitored the survival and morphology of retrogradely labelled neurons by in vivo confocal neuroimaging (ICON) for five weeks. To test for carrier-efficacy and safety, PBCA NPs loaded with Kyotorphin were injected in rats, and a hot plate test was used to quantify analgesic effects. In vitro, we found dose-dependent cell death which was, however, only detectable at very high doses and mainly seen in the cultures incubated with NPs fabricated with the tensids SDS and Tween. However, the in vivo experiments did not show any NP-induced neuronal death, even with particles which were toxic at high dose in vitro, i.e. NPs with Tween and SDS. The increased pain threshold at the hot plate test demonstrated that PBCA NPs are able to cross the BBB and thus comprise a useful tool for drug delivery into the central nervous system (CNS). Our findings showing that different nanoparticle formulations are non-toxic have important implications for the value of NP engineering approaches in medicine. 相似文献
45.
Ezzat M. Soliman Mohamed E. Mahmoud Salwa A. Ahmed 《International journal of environmental analytical chemistry》2013,93(6):403-413
A method is presented for the immobilization of thioglycolic acid moiety on the surface of active silica gel via a simple and direct synthetic route and based on one step reaction procedure. Two-product solid phase extractors were successfully synthesized according to physical adsorption and chemical immobilization binding techniques, phases (I) and (II), respectively. The mode of interaction between the silanol group and the thioglycolic moiety was also discussed for both phases based on the infrared analysis studies. The thermal stability properties as well as the effect of buffer solutions on the percentage hydrolysis of the two silica gel phases were examined and revealed the high stability and superiority of silica phase (II) in these respects. The evaluation of the selectivity and metal uptake properties incorporated in these two silica gel phases were also studied and discussed for a series of divalent heavy metal ions under different controlling factors. The mmol/g values were found to be higher in case of phase (I). The selective removal and extraction of some heavy metal ions, viz . Cu(II), Zn(II), and Hg(II) from natural seawater samples was successfully accomplished with the percentage recovery values for the three tested metal ions in the range of 96.5-98.4 - 0.2-0.6%. The presence of higher concentrations of Na(I), K(I), Mg(II) and Ca(II) showed insignificant role or no matrix effect on such selective extraction process due to their 0% values of removal by these silica gel phases (I) and (II). 相似文献
46.
Asmaa A. Magd El-Din Salwa A. Elsharabasy Aisha Y. Hassan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):407-412
Abstract Several new imidazo[2,1-b]-1,3-thiazine derivatives 4a–c, 8a–c, and 11a–c were synthesised via the reaction of 5,5-diphenyl-2-thiohydantoin (1) with αβ -unsaturated nitriles 2a–c, 5a–c, and 9a–c. The structures of the products were established on the basis of elemental analyses, IR, and 1H-NMR spectral data. 相似文献
47.
Abdel-Nasser M. A. Alaghaz Badr A. El-Sayad Salwa A. H. Albohy 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):799-807
Abstract A series of title compounds 2 and 3 were efficiently synthesized via the condensation of 10–hydroxycamptothecin with various symmetric (O,O′-monoaryl)-thiophosphoryl chlorides and asymmetric (O-ethyl-O′-aryl)-thiophosphoryl chlorides in sodium hydroxide powder and acetonitrile system. The structures of title compounds 2 and 3 were confirmed by elemental analysis, IR, 1H NMR, 13C NMR, 31P[1H] NMR,and mass spectral data. These symmetric [(O,O′-monoaryl)-thiophosphoryl)]-(20S)-camptothecin (2a–f) and asymmetric [(O-ethyl-O′-aryl)-thiophosphoryl)]-(20S)-camptothecin (3a–f) compounds were also tested for their in vitro antimicrobial activities against some bacterial strains, namely, S. aureus, B. Simplex, E. acetylicum, E. coli, P. aeruginosa, S. flexenari, S. aureus, S. typhi, and some fungal strains Aspergillus niger, Aspergillus flavus (molds), S. cerevisiae, C. albicans, T. longifucus, A. flavus, M. canis, F. solani, and C. glaberata (yeasts). Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the related elements to view the free supplemental file. 相似文献
48.
Messaoudi Abderrahim Errachid Mohammed Jbilou Khalide Sadok Hassane 《Numerical Algorithms》2019,80(1):253-278
Numerical Algorithms - Let x0,x1, ? , xn, be a set of n + 1 distinct real numbers (i.e., xm ≠ xj, for m ≠ j) and let ym,k, for m = 0, 1, ? , n, and k = 0, 1, ? , rm,... 相似文献
49.
An account of the state of the art in the contemporary practice of gas, liquid, supercritical-fluid, and thin-layer chromatography is presented with an emphasis on column technology, kinetic optimization of column variables, and multidimensional and multimodal chromatographic techniques. Future trends and the need for further research in the above areas are identified. 相似文献
50.
Poly(vinylalcohol)/poly(ethyleneglycol)/poly(ethyleneimine) blend membranes were prepared by solution casting followed by
solvent evaporation. The chemical structure of the prepared membranes was analyzed by FTIR and DSC. The sorption behavior
as well as the permeabilities of the membranes for pure CO2 and N2 were investigated. The results show that the PVA/PEI/PEG membranes possess a higher permeability of CO2 and a lower permeability of N2. The membrane displays a CO2 permeability of 27 Barrer, and a N2 permeability of 3 Barrer at 25°C and 1 bar. CO2 sorption behavior of the composite membrane, which can be classified as a dual-mode sorption model, and N2 sorption behavior of the copolymeric membrane is in agreement with the Fickian diffusion model.
相似文献