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21.
Vikas Verma Kuldeep Singh Ashok Kumar Devinder Kumar 《Journal of Thermal Analysis and Calorimetry》2013,112(1):339-344
The use of unconventional synthesis methods in the formation of CaO·2Al2O3 (CA2) is justified because it reduces the formation temperature of the compound. CA2 is formed by classical method at temperatures above 1,400 °C. The polymeric precursor method allows a significant temperature decrease in CA2 synthesis reaching temperatures of 1,000 °C. This paper deals with CA2 synthesis by “citrate” method which is often presented as Pechini method, starting from a mixture of citric acid, ethylene glycol and calcium, and aluminum nitrates. A method based on the formation of a polymeric precursor was also used, starting from a mixture of acrylic acid and nitrates of calcium and aluminum. The results showed a net difference in favor of samples obtained from acrylic acid, which by annealing at 800 °C for 1 h, contain pure CA2. The samples obtained from citric acid, after annealing at 800 °C are amorphous. After annealing at 900 °C in all samples CA2 is single phase. 相似文献
22.
Epoxides are converted regioselectively to corresponding higher substituted alcohols with greater yields using diphosphorus tetraiodide (P2I4) as a reducing agent and a catalytic amount of tetraethylammonium bromide at room temperature. 相似文献
23.
Vikas N. Telvekar 《合成通讯》2013,43(21):2827-2829
tert‐Butyl hypochlorite and tert‐butyl hypobromide react with aldoximes and convert them into hydroximinoyl chloride and bromide, respectively; however, under the same reaction conditions, tert‐butyl hypoiodite deoximates aldoximes and ketoximes to give corresponding aldehydes and ketones in high yield (>94%) in a short reaction time (~20 min). 相似文献
24.
Jasneet Kaur N. S. Negi R. K. Kotnala Kuldeep Chand Verma 《Journal of Sol-Gel Science and Technology》2013,65(3):411-419
We have studied the effect of hydrothermal conditions at constant temperature of 180 °C, varying preparation time for 15, 30 and 45 h on nanostructures of diluted magnetic semiconductor Sn0.95Co0.05O2 (SC5). X-ray diffraction pattern confirm the tetragonal SnO2 rutile phase. The transmission and scanning electron microscopy shows the resulting nanostructures i.e. nanospheres and nanorods. The proposed reaction mechanism is given. The Raman spectra show the formation of tetragonal rutile structure of SC5 nanostructures. Fourier transform infrared spectrum has been used to verify the existence of Sn–O bond. The photoluminescence spectra show that the emission spectral intensity increases gradually with decreasing grains size, increasing hydrothermal heating time of SC5 samples and exhibits an intense blue luminescence centered at a wavelength of 531 nm. The optical absorbance measurements revealed that the nanometric size of the materials influences the energy band gap. All the prepared SC5 samples exhibit room temperature ferromagnetism. 相似文献
25.
A. Sudheer Kumar Vikas D. Ghule S. Subrahmanyam Prof. Dr. Akhila K. Sahoo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):509-518
Various thermally stable energetic polynitro‐aryl‐1,2,3‐triazoles have been synthesized through Cu‐catalyzed [3+2] cycloaddition reactions between their corresponding azides and alkynes, followed by nitration. These compounds were characterized by analytical and spectroscopic methods and the solid‐state structures of most of these compounds have been determined by using X‐ray diffraction techniques. Most of the polynitro‐bearing triazole derivatives decomposed within the range 142–319 °C and their heats of formation and crystal densities were determined from computational studies. By using the Kamlet–Jacobs empirical relation, their detonation velocities and pressures were calculated from their heats of formation and crystal densities. Most of these newly synthesized compounds exhibited high positive heats of formation, good thermal stabilities, reasonable densities, and acceptable detonation properties that were comparable to those of TNT. 相似文献
26.
27.
Vikas Shringi Surendra Kothari N. L. Panwar 《Journal of Thermal Analysis and Calorimetry》2014,118(1):533-539
This investigation deals with thermodynamic analysis, which offers an alternative approach to evaluate the performance of solar dryers and thin-layer drying characteristics of garlic cloves in a developed system. The garlic cloves were dried from a moisture content of 55.5 % (w.b.) to 6.5 % (w.b.) for 8 h. The drying data obtained were fitted to five different drying kinetics models. Of these, the model suggested by Midilli et al. [28] had the best fit with the drying behavior of garlic cloves. The energy efficiency without and with recirculation of the air exiting the drying chamber during the study varied from 43.06 to 83.73 %, and 3.98 to 14.95 %, respectively, while the exergy efficiency corresponding to the energy efficiency of the drying process ranged from 5.01 to 55.30 % and 67.06 to 88.24 %, respectively. 相似文献
28.
Jagjeet Kaur Ravi Shrivastava Vikas Dubey Beena Jaykumar 《Research on Chemical Intermediates》2014,40(8):2599-2604
This paper reports thermoluminescence glow curves of Eu3+, Dy3+-doped Ba2MgSi2O7 phosphor for different UV exposure times. Kinetic data were evaluated by the peak-shape method. The glow curves shift toward higher intensity with increasing exposure time to UV at 365 nm. When the heating rate was 5 °C s?1, peaks were observed at 101.76, 109.69, 102.67, and 104.05 °C, respectively, after UV exposure for 5, 10, 15, and 20 min. The glow peaks are indicative of second-order kinetics. Different kinetic data, i.e. trap depth, order of kinetics, activation energy, and frequency factor were also calculated. To evaluate the persistence characteristics of the luminescence of the phosphor, the lifetime of the charge in the trap was calculated; it was 348, 660, 368, and 428 s for UV exposure of 5, 10, 15, and 20 min, which indicates the luminescence of the phosphor is persistent. 相似文献
29.
Sharma Deepika Radha Anu Kumar Pretam Kumar Sandeep Jassal Amanpreet K. Lata Suman Vikas Pandey Sushil K. 《Transition Metal Chemistry》2020,45(8):531-544
Transition Metal Chemistry - Nickel(II) complexes with octahedral coordination stabilized by N-donor ligands corresponds to [{(ArO)2PS2}2Ni·L2] [Ar = 4-(C2H5)C6H4 (3), and... 相似文献
30.