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41.
Boudjahem AG Monteverdi S Mercy M Bettahar MM 《Langmuir : the ACS journal of surfaces and colloids》2004,20(1):208-213
We have studied the effect of silica of quartz-type on the reducibility of nickel acetate in aqueous hydrazine (80 degrees C, pH = 10-12) and metal particle formation. The obtained materials were characterized by X-ray diffraction, transmission electron microscopy, and thermodesorption experiments. With nickel acetate alone, the reduction was partial (45%) and a metal film at the liquid-gas interface or a powdered metal precipitate with an average particle size of 120 nm was obtained. In the presence of silica as the surfactant, the reduction of nickel acetate was total and the nickel phase deposited as a film on the support with an average particle size of 25 nm. Supported nickel acetate was also totally reduced. Crystallites of a mean particle size of about 3 nm were obtained. Decreasing the nickel content or increasing the hydrazine/nickel ratio decreased the metal particle size. Whiskers were formed for low nickel loadings. Hydrogen thermal treatment of the reduced phase showed that the organic acetate fragment, belonging to the precursor salt, still remained strongly attached to the nickel phase. The amount of the retained organic matrix depended on the metal particle size. Surface defects are suggested as active sites, which enhanced nickel ion reduction in the presence of silica as the surfactant or support. Metal-support interactions and the nucleation/ growth rate were the main factors determining the size and morphology of the supported metal particles formed. The organic matrix covered the reduced nickel phase. 相似文献
42.
A new simple rapid method for the spectrophotometric determination of palladium using arsenazo I is given. The optimum conditions favoring the formation of the complex are extensively investigated; the molecular structure was found to be 1:1. Beer's law is obeyed for the ranges 1.0–10.6 or 0.64–6.39 ppm of Pd. 相似文献
43.
A carbon paste electrode for drotaverine hydrochloride (DvCl) was prepared and fully characterized in terms of composition, life span, usable pH range, response time and temperature. The electrode was applied to the potentiometric determination of drotaverinium ions in pharmaceutical preparations and biological fluids in steady state and flow injection conditions (FIA). The electrode is based on a mixture of two ion exchangers, namely, drotaverinium-silicotungestate and drotaverinium-tetraphenylborate dissolved in tricresyl phosphate as pasting liquid. The modified electrode showed a near-Nernstian slope of 59.34±2mV over the concentration range of 5.0×10–7–1.0 × 10–2M. The electrode exhibits good selectivity for DvCl with respect to a large number of inorganic cations, organic cations, sugars and amino acids. Potentiometric titrations of DvCl with several titrants have been monitored using this modified carbon paste electrode as an end-point indicator electrode. The proposed electrode offers the advantages of simplicity, accuracy, automation feasibility and applicability to turbid and colored samples. 相似文献
44.
A spectrophotometric procedure for the determination of six pharmaceutical sulfonamides containing a primary aromatic amino group using alizarine (I), alizarine blue (II), alizarine red (III), and quinalizarine (IV), that offers advantages of simplicity, rapidity, sensitivity, precision, and stability, has been developed. The proposed method is based on the formation of colored products with the chromogenic reagents (I-IV). A linear correlation was found between absorbance at λmax and the concentration. For more accurate results, Ringbom optimum concentration ranges are evaluated. The molar absorptivities (ε), absorptivities (a), and Sandell sensitivities for all sulfonamides derivatives with the chromogenic reagents tested were calculated. The procedures developed are applied for bulk sulfa drugs and some of their dosage forms. 相似文献
45.
El-Said Asma I. Zidan Amna S. A. El-Meligy Mahmoud S. Aly Aref A. M. Mohammed Omar F. 《Transition Metal Chemistry》2001,26(1-2):13-19
Complexes of 1,10-o-phenanthroline (o-phen)-NiII and CuII with dithiocarbamates derived from -amino acids (glycine, phenylalanine, alanine, methionine and tryptophan) were synthesized and characterized by chemical analysis, spectral and thermal studies and by biological screening; the complexes are non-electrolytes. The empirical formula are [Ni(o-phen)2(aadtc)] and [Cu2(o-phen)2(phaladtc)(H2O)2Br2] where, aadtc = glycinyl-, phenylalaninyl-, alaninyl-, methioninyl- and tryptophanyldithiocarbamate and phaladtc = phenylalaninyldithiocarbamate. The structure of these complexes is probably octahedral. Molecular association through hydrogen bonding between the —NH and the carboxylate groups is proposed for the NiII complexes. The CuII complex is dimeric with the phenylalaninyldithiocarbamate acting as a bridge. 相似文献
46.
Mohammed Ejaz 《Mikrochimica acta》1976,65(6):643-650
Summary Radiochemical procedures have been worked out to prepare234Th(UX1) with and without carrier from uranium using N-oxide of 4-(5-nonyl)pyridine in sulphuric acid media. This reagent has also been employed in the development of a combined solvent extraction-ion exchange-spectrophotometric method for the determination of thorium in various samples.
Zusammenfassung Radiochemische Methoden zur Herstellung von234Th(UX1) aus Uran mit und ohne Träger und unter Verwendung von 4-(5-Nonyl)pyridin-N-oxid in schwefelsaurer Lösung wurden ausgearbeitet. Dieses Reagens wurde auch für die Ausarbeitung einer Thoriumbestimmung in verschiedenartigen Proben auf der Grundlage von Extraktion, Ionenaustausch und Spektro-photometrie verwendet.相似文献
47.
Isoquinoline reacts with ethyl bromopyruvate in the presence of dialkyl acetylenedicarboxylates or diaryloylacetylenes to produce dialkyl 1-(2-ethoxy-2-oxoacetyl)pyrrolo[2,1-a]isoquinoline-2,3-dicarboxylates or ethyl 2-[2,3-diaryloylpyrrolo[2,1-a]isoquinoline-1-yl]-2-oxoacetates in good yields. 相似文献
48.
Iodate, iodide, iodine and ferrocyanide can be estimated by oxidation with KmnO4 in alkaline media; the excess is back-titrated with TI7. I- and I2 are oxidized to IO4- in the presence of Ba+2 ions but only to IO3- in absence of such ions. The direct titration of IO3-, I- with KmnO4 proved valueless.Ferrocyanide is oxidized by KmnO4 in alkaline solutions and MnO2 is formed. In the presence of telluric acid and 0.025–0.1 N NaOH satisfactory results are obtained. Reduction of MnO4- with ferrocyanide gives MnO4-2 and the results are variable, depending on the rate of adding the ferrocyanide. 相似文献
49.
el-Daly SA Abdel-Kader MH Issa RM el-Sherbini el-SA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(2):405-411
Electronic absorption, and excitation spectra of 1-methyl-4-[4-aminostyryl] pyridinum iodide (M-NH2) were measured in solvents of different polarity. The (M-NH2) dye exhibits negative solvatochromism, i.e. a hypsochromic band shift as the solvent polarity increases. The fluorescence quantum yield is also sensitive to the polarity and viscosity of the medium. The ground and excited state protonation constants were calculated and amount to 3.35 and 0.62, respectively. The effect of micellization on the emission spectrum of (M-NH2) are also studied in sodium dodecyl sulphate (SDS). The fluorescence intensity increases as the concentration of SDS increases with an abrupt change at cmc. The quantum yield of the cis trans photoisomerization is also determined in aqueous buffer solution of pH 1.1. 相似文献
50.
Kamel Guedri Tahmoor Bashir A. Abbasi Waseh Farooq Sami Ullah Khan M. Ijaz Khan Mohammed Jameel Ahmed M. Galal 《印度化学会志》2022,99(9):100614
The electroosmotic peristaltic flow of modified hybrid nanofluid in presence of entropy generation has been presented in this thermal model. The Hall impact and thermal radiation with help of nonlinear relations has also been used to modify the analysis. The assumed flow is considered due to a non-uniform trapped channel. The properties of modified hybrid nanofluid model are focused with interaction of three distinct types of nanoparticles namely copper (, silver () and aluminum oxide ( The mathematical modeling and significances of entropy generation and Bejan number are identified. With certain flow assumptions, the governing equations are attained for optimized peristaltic electroosmotic problem. Widely used assumptions of long wave length and low Reynolds number reduced the governing equations in ordinary differential equations. The ND solver is flowed for the solution process. The physical significant of results is observed by assigning the numerical values to parameters. 相似文献