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131.
Na2Ti3O7 and Na2Ti6O13 were synthesized by sol-gel method in order to obtain pure phases. Different heat-treatments were applied on powders and pellets of these materials. The effects were studied by XRD, dilatometry, TGA-DTA, SEM and electrochemical impedance spectroscopy. Pure Na2Ti3O7 was obtained at 973 K. Sintering at 1373 K caused a partial decomposition into Na2Ti6O13. The Na2Ti3O7 powder sintered at 1273 K showed polygonal microstructure. Na2Ti3O7 pellets sintered at 1323 K for 10 h exhibited large structures. This latter microstructure decreased the electrical conductivity of Na2Ti3O7. Pure Na2Ti6O13 was obtained at 873 K. Sintering at 1073 K caused a partial decomposition into TiO2 (rutile). Na2Ti6O13 pellets sintered at 1323 K for 10 h exhibited common shrinkage behavior. This shrinkage process increased the electrical conductivity of this material. The presence of TiO2 resulted in a oxygen partial pressure dependence of the electrical conductivity. 相似文献
132.
Various types of sodium cellulose sulfate (SCS), dissolved in a 1M LiCl solution, were investigated by alternating current (AC)polarography. The SCS samples differed in the degree of substitution (DS), thedistribution of substituents within the anhydroglucose unit (AGU), and alongthechain, due to the method of synthesis. The goal was to study theelectrosorptionbehavior, characterized by the shape of the desorption wave in the polarogram,as a function of the chemical structure of the SCS samples. The shape of thedesorption wave reflects domains of different substitution. A superimpositionofparameters like DS and pattern of substitution on the electrosorption behaviorwas observed. The AC polarography method described can be used as a tool todistinguish between an even or uneven distribution of substituents along thecellulose chain. 相似文献
133.
一阶导数光谱K系数法同时测定硝基酚钠三组分 总被引:2,自引:0,他引:2
研究和建立了同时测定硝基酚钠混合三组份的新方法——一阶导数光谱K系数法。确定了最佳实验条件和测定波长,方法简便、快速、准确。通过对动植物细胞赋活增进剂中邻硝基酚钠、对硝基酚钠、5-硝基愈创木酚钠三组份的直接测定,其相对误差小于2%,相对标准偏差小于3%,回收率为99~103%。 相似文献
134.
135.
Abhimanyu S. Paraskar 《Tetrahedron》2006,62(20):4907-4916
Sodium borohydride in combination with a catalytic amount of CoCl2 has been found to be an excellent catalytic system in reductive cyclizations of suitably substituted azido and cyano groups of α,β-unsaturated esters to afford γ and δ-lactams in high yields. The process has been demonstrated for the enantioselective synthesis of (R)-baclofen, (R)-rolipram, and (R)-4-fluorophenylpiperidinone, a key intermediate for (−)-paroxetine. 相似文献
136.
137.
Ipsita Devi 《Tetrahedron letters》2004,45(47):8625-8627
Sodium bromide catalysed three-component cyclocondensation of aryl aldehydes, alkyl nitriles and dimedone proceeds under microwave irradiation in solvent free conditions to give highly functionalised tetrahydrobenzo[b]pyrans in excellent yields. 相似文献
138.
N. Suryakiran 《Tetrahedron letters》2006,47(23):3853-3856
An efficient and convenient synthesis of β-ketosulfones is described. Reaction of an α-haloketone with sodium alkyl/aryl sulphinate yields the corresponding β-ketosulfone promoted by polyethylene glycol (PEG-400) as an efficient reaction medium. 相似文献
139.
A.?González-Pérez J.?M.?RusoEmail author G.?Prieto F.?Sarmiento 《Colloid and polymer science》2004,282(4):351-356
The interactions of sodium dodecyl sulphate with ovalbumin in aqueous solution at room temperature are described for a wide concentration range of both substances. A phase diagram covering a wide range of concentrations shows a total of five different morphologies. Dynamic light scattering of the samples from each morphology offered better understanding of the different structures (between three and four) present in the solution. The amount of ovalbumin present in the solution was confirmed with differential scanning spectroscopy, while the interactions between sodium dodecyl sulphate and ovalbumin were interpreted by zeta potential and electrical conductivity measurements. 相似文献
140.
Methyl methacrylate and butyl methacrylate were polymerized in oil-in-water microemulsions that were stabilized by sodium dodecyl sulphate (SDS). A poly(N-acetylethylenimine) (PNAEI) macromer was also included in the recipe, as a cosurfactant and a comonomer. Polymerizations were initiated by UV-irradiation. The average diameters of latex particles, obtained by STM, were in the range of 17-200 nm. The experimental data evidenced that the particle size was mainly dependent on the SDS/PNAEI ratio. Polymerization yields were around 75-85%. The synthesized copolymers have viscosity average molecular weights in the range of 2.1-2.4×106 and glass transition temperatures of 38.0-43.5°C, lower than those obtained without using PNAEI. The investigation by means of FTIR and 1H-NMR techniques revealed that PNAEI was incorporated into the nanoparticles. 相似文献