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31.
32.
The rate constants of O2(1Δg) with aliphatic alcohols, terpenes, unsaturated hydrocarbons, chlorinated hydrocarbons, oxygen, and diamines have been studied in thepresence of NO2. The rate constants for oxygen, 1,2-ethane diamine, and 1,2-propane diamine are (9.9 ± 0.4) × 102, (8.7 ± 0.7) × 104, and (1.4 ± 0.3) × 104 1/mol/s, respectively. The rate constants for all other compounds are less than the oxygen rate constant. 相似文献
33.
S. L. Arora P. Palffy-Muhoray R. A. Vora D. J. David A. M. Dasgupta 《Liquid crystals》1989,5(1):133-140
A number of 4'-substituted phenyl 4-(4'-cyano-4-oxybiphenyl)butanoates have been synthesized to study the effects of the -O-(CH2)3COO- inter-ring linkage on mesomorphic behaviour. Transition temperatures have been determined and are compared with those of the phenyl cyanobiphenylmethanoate analogues. In general, the butanoates exhibit lower melting points but in all cases, a lower nematic-isotropic transition is observed. An interesting feature of some members of the butanoate series is the presence of several reentrant mesophases. A unique phenomenon observed while studying the behaviour of one of the butanoates was the appearance of smectic filaments from the isotropic liquid on cooling. These filaments, through an unusual process, eventually form the typical smectic A texture. Formation of an SA phase from the isotropic liquid or the nematic phase in this fashion has not been reported previously. 相似文献
34.
Sanjiv Arora Rajeev Bagoria Mahender Kumar 《Journal of Thermal Analysis and Calorimetry》2010,102(1):375-381
Alpha-tocopherol (vitamin E) is the most widely used antioxidant for edible oils. The present investigation presents its effect
on the thermal degradation behavior of edible oils (sunflower, soybean, and their blend) through the use of dynamic thermogravimetry.
The study is based on the comparison of activation energies of decomposition process which were subsequently calculated using
preferred and reliable multiple-heating rate methods viz. Kissinger, Friedman, Ozawa–Flynn–Wall, and Coats–Redfern (modified).
It is concluded that the role of alpha-tocopherol as antioxidant at higher temperature is nearly accomplished. 相似文献
35.
An experimental investigation is made to study the flow characteristics of slot jet impingement on a cylinder. The velocity profiles and pressure distribution around the cylinder are reported for various parameters namely, the flow rate, width of the nozzle, distance of the cylinder from the jet exit and eccentricity of the cylinder to the jet axis.
Nomenclature B breadth of the nozzle at the exit - D diameter of the cylinder - C p pressure coefficient - g acceleration due to gravity - L distance of the cylinder from jet exit - P a atmospheric pressure - P c static pressure along the jet center-line - P 0 stagnation pressure - P W wall static pressure - Re D Reynolds numberu j D/ a - Re W Reynolds numberu j W/ a - r distance measured from cylinder surface in radial direction - r m position of maximum velocity from cylinder surface - r 0.5 half width of the jet - u mean velocity - u j mean velocity at the jet exit - u m maximum velocity - W width of the nozzle - a density of air - m density of mercury - w density of water - absolute viscosity - kinematic viscosity 相似文献
Experimentelle Untersuchung über die Strömungseigenschaften eines Düsenstrahls, der auf einen Zylinder aufprallt
Zusammenfassung Es wurde eine experimentelle Untersuchung gemacht, um die Strömungseigenschaften eines Düsenstrahls zu unterschen, der auf einen Zylinder prallt. Die Geschwindigkeitsprofile und die Druckverteilungen an dem Zylinder wurden für unterschiedliche Parameter dokumentiert. Die Parameter sind die Strömungsgeschwindigkeit, Düsengröße, Abstand zwischen Zylinder und Strahlaustritt und die Exzentrizität von Zylinder und Strahlachse.
Nomenclature B breadth of the nozzle at the exit - D diameter of the cylinder - C p pressure coefficient - g acceleration due to gravity - L distance of the cylinder from jet exit - P a atmospheric pressure - P c static pressure along the jet center-line - P 0 stagnation pressure - P W wall static pressure - Re D Reynolds numberu j D/ a - Re W Reynolds numberu j W/ a - r distance measured from cylinder surface in radial direction - r m position of maximum velocity from cylinder surface - r 0.5 half width of the jet - u mean velocity - u j mean velocity at the jet exit - u m maximum velocity - W width of the nozzle - a density of air - m density of mercury - w density of water - absolute viscosity - kinematic viscosity 相似文献
36.
Multifunctionalized tetrahydropyrimidines derivatives have been synthesized from Biginelli 3,4-dihydropyrimidin-2-(1H)-thiones (DHPMs) efficiently. The transformation includes desulfurization of DHPMs with Raney-Ni and subsequent regioselective C-2 functionalization using a variety of C-nucleophiles with simultaneous activation with ethyl chloroformate. Functionalized pyrimidine derivatives containing bulky substituents at C-2 of the pyrimidine ring are cytostatic. 相似文献
37.
38.
A. SheoranA. Agarwal S. Sanghi V.P. SethS.K. Gupta M. Arora 《Physica B: Condensed Matter》2011,406(23):4505-4511
Glasses with composition xWO3·(30−x)M2O·70B2O3 (M=Li, Na; 0≤x≤15) doped with 2 mol% V2O5 have been prepared using the melt-quench technique. The electron paramagnetic resonance spectra have been recorded in X-band (ν≈9.14 GHz) at room temperature (RT). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that the resultant resonance spectra contain hyperfine structures (hfs) only due to V4+ ions, which exist as VO2+ ions in octahedral coordination with a tetragonal compression in the present glass system. The tetragonality increases with WO3:M2O ratio and also there is an expansion of 3dxy orbit of unpaired electron in the vanadium ion. The study of IR transmission spectra over a range 400-4000 cm−1 depicts the presence of WO6 group. The DC conductivity (σ) has been measured in the temperature range 423-623 K and is found to be predominantly ionic. 相似文献
39.
JPC – Journal of Planar Chromatography – Modern TLC - The normal-phase (NP) and reversed-phase (RP) thin-layer chromatographic separations of aminoglycosides (streptomycin, kanamycin,... 相似文献
40.
Cavitation cluster dynamics after the passage of a single pressure wave is studied for different concentrations of artificial cavitation nuclei (30 to 3x10(5) nuclei/ml). With increasing concentration of cavitation nuclei the lifetime of the cavitation cluster is prolonged. Additionally, it is found that the spatial extent of the cluster decreases with higher nuclei concentration. The experimental data for concentrations less than 400 nuclei/ml are compared to simulations with a Rayleigh-Plesset-type equation, taking into account bubble-bubble interaction. For higher concentrations (more than 1000 nuclei/ml) the observed radial cluster dynamics is compared with calculations from an axisymmetric cavity-collapse model. 相似文献