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121.
122.
Kumar PM Kumar KS Mohakhud PK Mukkanti K Kapavarapu R Parsa KV Pal M 《Chemical communications (Cambridge, England)》2012,48(3):431-433
A conceptually new three-component reaction was developed to construct a six-membered fused N-heterocyclic ring affording (pyrazolo)pyrimidines/pyridines as potential inhibitors of PDE4. The reaction is catalyzed by triflic acid in acetic acid in the presence of aerial oxygen. 相似文献
123.
A new method involving pre-concentration on modified silica fiber is described for the speciation of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] in aqueous media. This method is based on the different chelating behavior of Cr(III) and Cr(VI) with morpholine-4-carbodithioate (MDTC). Both complexes are extracted on silica fiber modified by sol-gel technology by using 3-aminopropyltriethoxysilane (APS) as a precursor. All extracted samples are directly injected into an high-performance liquid chromatography injector for the simultaneous determination of Cr(III) and Cr(VI). Cr(VI) forms two different complexes, and Cr(III) forms a single complex with MDTC. Therefore, the concentration of Cr(VI) is determined directly from the peak area obtained at 5.4 min; whereas, the assay of Cr(III) is based on subtracting the peak area of Cr(VI) from the total peak area obtained at 4.3 min. Under the optimized conditions, the limits of detection for Cr(III) and Cr(VI) are found to be 0.7 ng/mL and 0.2 ng/mL, respectively. 相似文献
124.
Sridhar Madabhushi Raveendra JillellaKondal Reddy Godala Kishore Kumar Reddy MalluChina Ramanaiah Beeram Narsaiah Chinthala 《Tetrahedron letters》2012,53(39):5275-5279
An efficient and simple method for the synthesis of 2,2-disubstituted-2H-chromenes by one-step cyclocondensation of a phenol with a variety of 1,1-disubstituted propargyl alcohols using BF3·Et2O as the catalyst is described. 相似文献
125.
The specific conductance of Thiamine hydrochloride in water and water-ethanol mixtures was measured at different temperatures 283, 293, 303 and 313 K. Kraus-Bray and Shedlovsky models of conductivity were used for analyzing conductance data. The limiting molar conductance, association constant K a, energy of activation of the rate process E a, and related thermodynamic parameters have been determined. Based on viscosity of the solvent, Walden product and Stokes molecular radius were also been determined. Born model of ion solvation was proved. Standard thermodynamic parameters of association (G a, H a and S a) were calculated and discussed. The results show the decrease in limiting molar conductance and increase in K a with decrease in relative permittivity. Such computed values have been used to discuss the solvation behaviour of Thiamine hydrochloride in water-ethanol mixtures. 相似文献
126.
Escobar Jose M. Rane Kishore D. Cheryan Munir 《Applied biochemistry and biotechnology》2001,91(1-9):283-296
Pilot plant trials were conducted in a corn wet mill with a 7000-L membrane recycle bioreactor (MRB) that integrated ceramic
microfiltration membranes in a semi-closed loop configuration with a stirred-tank reactor. Residence times of 7.5–10 h with
ethanol outputs of 10–11.5% (v/v) were obtained when the cell concentration was 60–100 g/L drywt of yeast, equivalent to about
109−1010 cells/mL. The performance of the membrane was dependent on the startup mode and pressure management techniques. A steady
flux of 70 L/(m2·h) could be maintained for several days before cleaning was necessary. The benefits of the MRB include better productivity;
a clear productstream containing no particulates or yeast cells, which should improve subsequent stripping and distillation
operations; and substantially reduced stillage handling. The capital cost of the MRB is $21–$34/(m3·yr) ($0.08–$0.13/[gal·yr]) of ethanol capacity. Operating cost, including depreciation, energy, membrane replacement, maintenance,
labor, and cleaning, is $4.5–9/m3 ($0.017–$0.034/gal) of ethanol. 相似文献
127.
V.P. Rama Kishore Putta Raghuram Gujjarappa Nagaraju Vodnala Richa Gupta Prasad P. Pujar Chandi C. Malakar 《Tetrahedron letters》2018,59(10):904-908
The first organocatalytic approach towards synthesis of rarely explored 1,2,4-selenadiazole and thiadiazole scaffolds have been devised using corresponding carboxamides as substrates. The transformations were realized using two distinct conditions in the presence of catalytic vitamin B3 or thiourea under aerobic conditions. Developed methods overcome the associated limitations of previous reported approaches and the desired products were obtained in high yields and selectivity without the formation of toxic side-products. 相似文献
128.
Experimental Mechanics - An experimental investigation is conducted to study the mechanics of underwater implosion of cylindrical bonded sandwich composite shells. Sandwich structures comprised of... 相似文献
129.
130.
In recent years, angular and linear phenoxazines and their derivatives and polymers have attracted much attention due to their great pharmacological and industrial utility. So it becomes imperative to review the work done in this area more frequently. Therefore, various synthetic routes for phenoxazines are reviewed here comprehensively. 相似文献