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61.
We have developed a kinematical theory for the asteroidal belt and Kirkwood gaps from the point of view of stellar dynamics.
We have generated the potential that would produce these gaps and have made a spectral analysis study. We have shown that
these gaps could be due to spiral tubes of matter in the ecliptic plane as a consequence of differential rotation and spatial
interference of density waves. We have also shown that this mechanism could account for depletion of matter from this region. 相似文献
62.
Different samples of calcium sulphide (CaS):CaS(Sm) and CaS(Sm,Ce) phosphors have been prepared. To study the phosphorescence decay systematically, the samples were excited to a saturation using 259 nm line of xenon lamp and phosphorescence emission was monitored for a wavelength 569 nm of samarium. The trap depth has been evaluated by analyzing the decay curves. The observed decay could be explained satisfactorily by assuming a superposition scheme. The thermoluminescence properties of the doped CaS phosphors are also investigated in detail by computerized deconvolution technique of the glow curves obtained by UV irradiation. 相似文献
63.
Hard sphere diameters of liquid alkali metal alloys (Na-Cs and K-Rb) are calculated at 373 K ensuring the minimum Helmholtz
free energy of the system. These diameters are then used to fix the packing density of the alloy. On alloying, the hard sphere
diameters of Na in Na-Cs and K in K-Rb alloys expand whereas those of Cs and Rb contract. 相似文献
64.
G. Pratap S. A. Mustafa J. P. Heller 《Journal of polymer science. Part A, Polymer chemistry》1993,31(9):2387-2391
65.
Transition Metal Chemistry - The kinetics and mechanism of the base hydrolysis ofO-bonded pentaammineglycinatocobalt(III) and pentaammine-β-alaninatocobalt(III) ions have been studied... 相似文献
66.
Levy E Tsukernik A Karpovski M Palevski A Dwir B Pelucchi E Rudra A Kapon E Oreg Y 《Physical review letters》2006,97(19):196802
We have measured the temperature dependence of the conductance in long V-groove quantum wires fabricated in GaAs/AlGaAs heterostructures. Our data are consistent with recent theories developed within the framework of the Luttinger-liquid model, in the limit of weakly disordered wires. We show that, for the relatively low level of disorder in our quantum wires, the value of the interaction parameter g congruent with 0.66, which is the expected value for GaAs. However, samples with a higher level of disorder show conductance with stronger temperature dependence, which does not allow their treatment in the framework of perturbation theory. Fitting such data with perturbation-theory models leads inevitably to wrong (lower) values of g. 相似文献
67.
Sharma A Verma SC Saxena N Chadda N Singh NP Sinha AK 《Journal of separation science》2006,29(5):613-619
Microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and conventional extraction of vanillin and its quantification by HPLC in pods of Vanilla planifolia is described. A range of nonpolar to polar solvents were used for the extraction of vanillin employing MAE, UAE and conventional methods. Various extraction parameters such as nature of the solvent, solvent volume, time of irradiation, microwave and ultrasound energy inputs were optimized. HPLC was performed on RP ODS column (4.6 mm ID x 250 mm, 5 microm, Waters), a photodiode array detector (Waters 2996) using gradient solvent system of ACN and ortho-phosphoric acid in water (0.001:99.999 v/v) at 25 degrees C. Regression equation revealed a linear relationship (r2 > 0.9998) between the mass of vanillin injected and the peak areas. The detection limit (S/N = 3) and limit of quantification (S/N = 10) were 0.65 and 1.2 microg/g, respectively. Recovery was achieved in the range 98.5-99.6% for vanillin. Maximum yield of vanilla extract (29.81, 29.068 and 14.31% by conventional extraction, MAE and UAE, respectively) was found in a mixture of ethanol/water (40:60 v/v). Dehydrated ethanolic extract showed the highest amount of vanillin (1.8, 1.25 and 0.99% by MAE, conventional extraction and UAE, respectively). 相似文献
68.
Sunetra L. Dhere Charles Kappenstein V. Ganesan Pratap B. Wagh 《Applied Surface Science》2010,256(11):3624-7489
Non-wettable surfaces with high contact angles and facile sliding angle of water droplets have received tremendous attention in recent years. The present paper describes the room temperature (∼27 °C) synthesis of dip coated water repellent silica coatings on glass substrates using iso-butyltrimethoxysilane (iso-BTMS) as a co-precursor. Emphasis is given to the influence of the hydrophobic reagent (iso-BTMS) on the water repellent properties of the silica films. Silica sol was prepared by keeping the molar ratio of tetraethoxysilane (TEOS) precursor, methanol (MeOH) solvent, water (H2O) constant at 1:16.53:8.26 respectively, with 0.01 M NH4F throughout the experiment and the molar ratio of iso-BTMS/TEOS (M) was varied from 0 to 0.965. The effect of M on the surface structure and hydrophobicity has been researched. The static water contact angle values of the silica films increased from 65° to 140° and water sliding angle values decreased from 42° to 16° with an increase in the M value from 0 to 0.965. The water repellent silica films are thermally stable up to a temperature of 280 °C and above this temperature the film shows hydrophilic behavior. The water repellent silica films were characterized by the Fourier Transform Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), % of optical transmission, thermal and chemical aging tests, humidity tests, static and dynamic water contact angle measurements. 相似文献
69.
Nisha Bansal Sarvesh Kumar Deepti Pratap Saif Ahmad Khan R.S. Chauhan 《辐射效应与固体损伤》2013,168(10):855-861
The present study is carried out for the investigation of energetic ion beam mixing in the Bi/Ge system, induced by electronic excitation. The system Ge/Bi/C was deposited on Si substrate at room temperature in the high vacuum deposition system and irradiated using Au ions of 120?MeV at the fluences 1?×?1013, 5?×?1013 and 1?×?1014?ions/cm2. The top layer of carbon was deposited as the protecting layer to avoid oxidation. The swift heavy ions (SHI)-induced interface mixing was studied by Rutherford backscattering spectroscopy (RBS) for depth profiles and compositions, grazing incidence X-ray diffraction (GIXRD) for phase identification and atomic force microscopy (AFM) for surface roughness. We have calculated the mixing rate, mixing efficiency and inter-diffusion coefficient for the Bi/Ge system. We observed that the thickness of the mixed region increased with increasing fluence. In the GIXRD pattern, no new crystalline phase formation was observed after irradiation, the mixed region may be in an amorphous form. The mixing effect is explained in the framework of the thermal spike model. 相似文献
70.
Amit Pratap Singh 《辐射效应与固体损伤》2013,168(1):44-49
In this work, the thermal conductivity variation due to pit formation and surface roughness in nanometer-thick semiconducting films has been studied. It is shown that the thermal conductivity of thin films is reduced due to the presence of these effects in the films. This reduction in thermal conductivity is dependent on film thickness. The present analysis has been done on GaAs nanometer-thick films using the available experimental data. 相似文献