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81.
Rohini Mani Keka R. Chakraborty Joby E. Joy J. Gopalakrishnan A.K. Tyagi 《Journal of solid state chemistry》2010,183(6):1380-1387
We describe an investigation of the structure and dielectric properties of MM′O4 and MTiM′O6 rutile-type oxides for M=Cr, Fe, Ga and M′=Nb, Ta and Sb. All the oxides adopt a disordered rutile structure (P42/mnm) at ambient temperature. A partial ordered trirutile-type structure is confirmed for FeTaO4 from the low temperature (17 K) neutron diffraction studies. While both the MM′O4 oxides (CrTaO4 and FeTaO4) investigated show a normal dielectric property MTiM′O6 oxides for M=Fe, Cr and M′=Nb/Ta/Sb display a distinct relaxor/relaxor-like response. Significantly the corresponding gallium analogs, GaTiNbO6 and GaTiTaO6, do not show a relaxor response at T<500 K. 相似文献
82.
Joseph Glaz Marco Guerriero Rohini Sen 《Methodology and Computing in Applied Probability》2010,12(4):731-747
Let X
ijk
,1 ≤ i ≤ N
1,1 ≤ j ≤ N
2, 1 ≤ k ≤ N
3 be a sequence of independent and identically distributed 0 − 1 Bernoulli trials. X
ijk
= 1 if an event has occurred at the i,j,k
th
location in a three dimensional rectangular region and X
ijk
= 0, otherwise. For 2 ≤ m
j
≤ N
j
− 1,1 ≤ j ≤ 3, a three dimensional discrete scan statistic is defined as the maximum number of events in any m
1×m
2×m
3 rectangular sub-region in the entire N
1×N
2×N
3 rectangular region. In this article, a product-type approximation and three Poisson approximations are derived for the distribution
of this three dimensional scan statistic. Numerical results are presented to evaluate the accuracy of these approximations
and their use in testing for randomness. 相似文献
83.
The threshold enhancement in the cross section γγ → ?0?0, including the lower energy point reported by the CELLO group, and the observed angular distributions have been interpreted in terms of an isoscalar resonance with JPC = 0++, mass 1450–1550 MeV and width 100–150 MeV. 相似文献
84.
85.
Parag V. Adhyapak Prashant R. Karandikar Jagdish W. Dadge Rohini C. Aiyer Asha J. Chandwadkar 《Central European Journal of Chemistry》2006,4(2):317-328
Uniform nanowires of silver and gold inside the channels of MCM-41 were prepared by controlled reduction of their respective
metal salts with sodium borohydride (NaBH4). Presence of nanowires of silver and gold in MCM-41 were confirmed by high angle X-ray diffraction (XRD) data (peaks between
2ϑ = 30 − 60°) and transmission electron microscopy (TEM) confirmed the diameter of the nanowires. Diameter of nanowires is
found to be ∼ 2.8 nm which is coincident with channel diameter of MCM-41. Optical properties of these heterostructured materials
Ag-MCM-41 and Au-MCM-41 reveals the presence of surface plasmon absorption peaks of silver and gold respectively, and the
shift in the absorption bands are associated to agglomeration of clusters inside the channels. Room temperature photoluminescence
spectra exhibits interesting optical properties as observed for direct band gap semiconductors. Non-linear optical properties
(NLO) corresponding to second harmonic generation (SHG) values were also recorded for self supported films of these heterostructured
materials. Enhanced optical non-linearity was found to be arising from a corresponding increase of local field near the surface
plasmon resonance. Further enhancement in SHG was found with poling due to an induction of orientation order. 相似文献
86.
Pravin Chavan Sachin Bangale Dattatraya Pansare Rohini Shelke Shivaji Jadhav Shrikrushna Tupare Dhanraj Kamble Megha Rai 《Journal of heterocyclic chemistry》2020,57(9):3326-3333
A highly efficient, eco-friendly, recyclable heterogeneous ZnFe2O4 nanocatalyzed synthesis of 2-amino-4-substituted 1,4-dihydrobenzo[4,5]imidazo[1,2-a]pyrimidine-3-carbonitrile (4a-j) derivatives via one pot multicomponent reaction of benzimidazole ( 1 ), substituted aromatic aldehyde ( 2a-j ) and malononitrile ( 3 ) under ultrasonic irradiations. Significance of this synthetic approach is short reaction time, easy handling, simplicity, efficiency, high yield, and recoverable catalyst. 相似文献
87.
Polydispersed ZnO nanoparticles (ZnO1000 and ZnO600) with two different windows of particle size distributions (∼120 and 30 nm) were synthesized using citrate gel route and different annealing treatments (1000 and 600 °C, respectively). Photocatalytic efficiency of these samples was compared with TiO2 in its commercial form-P25, on two dyes, Methylene blue (MB) and Methyl orange (MO). The X-ray diffraction data showed wrutzite ZnO and anatase and rutile phases of P25. UV-visible absorbance spectra of ZnO1000 showed broad absorption range from UV-to-visible (from 382 to 700 nm), as against sharp absorption peaks in UV range for both ZnO600 and P25. The microstructural morphology as seen through scanning electron micrographs showed ZnO1000 with tetrapod-like structures while the ZnO600 showed almost spherical morphologies. Upon subjecting these catalysts to dye solutions in sunlight it was found that both the dyes were completely decolorised within 20 min by ZnO1000, as against partial decolorisation by ZnO600 and P25 ( 53% and 78% for MO and 77% and 88% for MB samples). The effect of catalyst loading (from 125 mg to 1 g) on decolorisation showed that ZnO1000 had good efficiency for all concentrations which was followed by P25 and then by ZnO600. Small perturbations are attributed to the competition between sunlight scattering-induced, reduced irradiation field and the exposed surface area offered by catalyst, which work as active sites for decolorisation. The reusability of the catalysts when studied on fresh dye samples (4 trials), the decolorisation efficiency decreased merely from 99.2% to 99.12% for ZnO1000 as compared to ZnO600 (53.3% to 19.94%) and P25 (78.3% to 31.42%), indicating the efficient reusability of ZnO1000. The effective half life of the catalysts, in terms of number of reuses, were calculated and found to be ∼3 for both ZnO600 and P25 and was >3000 for ZnO1000, which justifies its extremely high reuse. The byproduct analysis (compared with standards prescribed by World Health Organisation (WHO) and Central Pollution Control Board of India (CPCB)) showed cleavage of the chromophore and of other bonds with opening of benzene rings, indicating degradation of the dyes in concurrence with decolorisation, in the stipulated time. Further, cytotoxicity studies performed on SiHa cell lines showed non-toxicity of the byproducts with ZnO1000 as compared to ZnO600 and P25. 相似文献
88.