A new sol-gel derived ceramic-carbon composite electrode was fabricated by the use of CuI as modifier. The electrocatalytic activity of the copper iodide modified sol-gel derived ceramic-carbon composite (CIM-SGD-CCC) electrode was examined for the oxidation of hydrazine. Cyclic voltammetry was employed to study the electrochemical and electrocatalytic properties of the modified electrode. Results showed that the CIM-SGD-CCC electrode has very high catalytic activity for electrooxidation of hydrazine. This proves that the copper iodide bears the main role in electro-catalytic oxidation of hydrazine. This modified electrode shows fast amperometric response with the range from 1 ? mol L-1 to 40 ? mol L-1 and the limit of detection (LOD) of 0.524 ? mol L-1 for hydrazine. The relative standard deviation (R.S.D.) was 0.72 % for 5 successive assays. High stability, good reproducibility, rapid response, easy surface regeneration and fabrication are the important characteristics of the proposed electrode.
In this work, we report on the synthesis of SiO2 hollow spheres using carbon nanospheres as the sacrificial template by hydrothermal method. The synthesized substrates are in a spherical morphology and uniform size distribution. The effects of hydrothermal process, concentration and the reaction temperature were optimized during synthesis of carbon nanospheres. Infrared spectroscopy (IR), and scanning electronic microscopy (SEM) methods were used for identification of the synthesized products. The synthesized SiO2 nanospheres were used as drug carrier to investigate in vitro release behavior of monoterpenic phenol isomers, carvacrol and thymol, in simulated body fluid (SBF). Ultraviolet-visible spectroscopy (UV-vis) method was carried out to determine the amount of the drugs entrapped in the carrier. The results indicated that SiO2 nanospheres have high ability to adsorb the drugs and there is no need for adjusting the pH during the adsorption process. The drug release profile shows a three stages pattern and indicates a delayed release action.
Chemically attachment of Schiff base complexes on multiwalled carbon nanotubes (MWCNTs) surfaces through a convenient and simple method was studied. In the first step of this method, we present a new method for preparation of aminated MWCNTs in order to attachment of (new) chlorinated salen Schiff bases. Amination of multiwalled carbon nanotubes performed under microwave (MW) irradiation through a one pot two step reaction. The chemically attachment of salen Schiff bases on functionalized MWCNTs (salen@MWCNTs) performed under a facile simple nucleophilic substitution reaction and complexation of attached salen Schiff bases (salen complex@MWCNTs) in last step, have been occurred with reaction of transition metal salts and salen@MWCNTs. The obtained products were characterized in detail, using FTIR, XRD, UV-Vis absorption, SEM and EDX methods.
The present paper deals with the characterization of ion exchange resins Dowex 550A LC and Indion-930A based on kinetics of ion-isotopic exchange reactions for which the short lived radioactive isotopes 131I and 82Br were used as a tracers. The study was performed for different concentration of ionic solution varying from 0.001 mol/L to 0.004 mol/L and temperature in the range of 30.0 °C to 45.0 °C. The results indicate that as compared to bromide ion-isotopic exchange reaction, iodide exchange reaction take place at the faster rate. For both the ion-isotopic exchange reactions, under identical experimental conditions, the values of specific reaction rate increases with increase in the ionic concentration and decreases with rise in temperature. It was observed that at 35.00C, 1.000 g of ion exchange resins and 0.002 mol/L labeled iodide ion solution for iodide ion-isotopic exchange reaction, the values of specific reaction rate (min-1), amount of ion exchanged (mmol), initial rate of ion exchange (mmol/min) and log Kd were 0.270, 0.342, 0.092 and 11.8 respectively for Dowex 550A LC resin, which was higher than the respective values of 0.156, 0.241, 0.038 and 7.4 as that obtained for Indion-930A resins. From the results, it appears that Dowex 550A LC resins show superior performance over Indion-930A resins under identical experimental conditions.
New silica-supported yttrium trinitrate was prepared, characterized, and used as a reusable catalyst for the three-component synthesis of quinazolinones/thiones via the Biginelli condensation under solvent-free conditions. Non-toxic reagent, short reaction times, simple work-up procedure, and high yield of the products are some of the important advantages of present method.
Evaluating the capability of electrospinning method as an efficient versatile approach for fabrication of fibers, a central composite design (CCD) model was used to design an experimental program for investigation of effective in production of poly (vinyl alcohol) (PVA) fibers fabricated from aqueous solutions of PVA. The studied variables were polymer solution concentration, applied voltage, distance between nozzle and collector plate and flow rate of solution injection. The influence of these parameters on diameter and morphology of obtained PVA fibers was studied by SEM analysis. Among all factors, concentration would strongly affect the fiber diameter.
Optimal method were developed for the green synthesis of quinoxaline derivatives based on the highly efficient and simple condensation reaction of various aromatic 1,2-diketones and 1,2-diamines in nearly quantitative yields in water. In this method we did not use any catalyst. The very mild reaction conditions, the high yields of the products, and the absence of any catalyst make this methodology an efficient and green route for synthesis of quinoxalines.
A tautomeric equilibrium exists for quinoline-2-thiol and quinoline-2(1H)-thione. Quantum mechanical calculations predict the thione is the major tautomer and this is confirmed by the absorption spectra. The utility of quinolone-2-thiol/quinoline-2(1H)-thione as a chromophore for developing fluorescent sensors is explored. No fluorescence is observed when excited at absorption maxima, however a fluorescence increase is observed when exposed to HNO, a molecule of import as a cardiovascular therapeutic. Alkylated quinoline-2-thiol derivatives are found to be fluorescent and show a reduction in fluorescence when exposed to metals and changes in pH.