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排序方式: 共有237条查询结果,搜索用时 437 毫秒
31.
N. Venugopalan Pillai R. Vinodkumar V. Ganesan Peter Koshy V. P. Mahadevan Pillai 《Pramana》2010,75(6):1157-1161
BaWO4 doped with ZnO (2, 3, 5, 7 and 10 wt%) nanostructured films are prepared on quartz substrates by pulsed laser ablation. The
films are post annealed at 900°C. GIXRD analysis of the post-annealed films reveal the change of orientation of scheelite
tetragonal crystal growth from 1 1 2 reflection plane to 0 0 4 planes when doping concentration is more than 3 wt%. The AFM
images show that film with 7 wt% ZnO doping concentration has good ceramic pattern with surface features giving a minimum
value of rms surface roughness suitable for optoelectronic device applications. The optical transmittance and band-gap energy
of the films are found to decrease considerably on postannealing which can be due to the increase in grain size of the crystallites
on annealing. Thus doping with ZnO improves the surface features of the films and increases the optical band-gap energy. 相似文献
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Quantum dots (3–4?nm) of Zn1? x Cd x S (both free of Mn2+ and with Mn2+ incorporated) were synthesized through a novel solvothermal-microwave irradiation technique. Detailed structural analysis of the Zn1? x Cd x S and Zn1? x Cd x S:Mn2+ (x?=?0, 0.25, 0.5, 0.75 and 1) materials was carried out using powder X-ray diffraction technique. For all the compositions, the crystallite size was controlled to less than 1.5?nm. The optical energy gap for Zn1? x Cd x S was found to vary from 3.878 to 2.519?eV and for Zn1?x Cd x S:Mn2+ it varies from 3.830 to 2.442?eV when x is increased from 0 to 1. Overall, the optical energy gap could be tuned from a minimum of 2.442?eV to a maximum of 3.878?eV. DC conductivity analysis (from 40°C to 150°C) and electrical energy gap analysis for all the compositions were also performed. The dc conductivity for Zn1? x Cd x S solid solutions varies from 0.3840?×?10?10 to 8.7782?×?10?10?mho/m at 150°C and for Zn1? x Cd x S:Mn2+ it varies from 0.5751?×?10?10 to 9.8078?×?10?10 mho /m at 150°C (for x?=?0 to x?=?1). The method of synthesis and the results observed in this investigation may assist in the fabrication of optical devices when the required operational performance falls under the range observed in the study. 相似文献
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36.
P. Kuppusamy P. T. Manoharan C. Mahadevan M. Seshasayee 《Journal of chemical crystallography》1985,15(4):359-376
The crystal and molecular structure of the title compound, C21H11N6S4Ni, is reported. The crystals are triclinic:P¯1 (No. 2),Z=4,a=8.768(1),b=11.817(3),c=22.131(3) Å,=97.44(1),=91.90(1), and =94.04(1)°. The structure was solved by the heavy-atom method, and refined by full-matrix least squares toR=0.039 for 3213 unique reflections. The Ni atoms of both anions in the asymmetric unit have an approximately square-planar configuration. Anions and cations form segregated stacks alonga. The stacking of the anions along this direction is dimeric, with alternating Ni-Ni distances 4.111(2) and 7.593(2) Å for molecule I and 4.208(1) and 8.155(2) Å for molecule II. Static susceptibility measurements show strong antiferromagnetic coupling (2J=-241 cm–1) between the two anions of the dimers. 相似文献
37.
Results are reported of measurements of the glass transition temperature (Tg), conductivity and density (d) for glasses of the AsSbSe system, with compositions (As, Sb)40Se60 and AsxSb15Se85?x. The results are compared with glasses of similar compositions of the AsxSe100?x about compositions in the GexSb15Se85?x and AsxSe100?x glasses, in the case of AsxSb15Se85?x glasses, the As-rich compositions exhibit higher values of Tg and d compared to the stoichiometric composition As25Sb15Se60. These results are discussed in the light of a chemically ordered structural arrangement in these glasses. 相似文献
38.
Aswathanarayana Srinivasa Kittappa Malavalli Mahadevan Kallappa Mahadevappa Hosamani Vijaykumar Hulikal 《Monatshefte für Chemie / Chemical Monthly》2008,139(2):141-145
Summary. 4-Nitrophthalic acid was found to be an effective catalyst for the imino Diels-Alder reaction of N-benzylideneanilines with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran to afford pyrano- and furanoquinolines in good yields. It was also found that aryl amines react
smoothly with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran under the same condition to afford the corresponding pyrano- and furanoquinolines in high yields.
This catalyst is inexpensive, easily available, water soluble, and stable to aqueous reaction conditions. 相似文献
39.
Aswathanarayana Srinivasa Kittappa M. Mahadevan Vijaykumar Hulikal 《Monatshefte für Chemie / Chemical Monthly》2008,10(1):255-259
Antimony(III) sulfate is found to catalyze the imino Diels-Alder reaction of Schiff’s bases with N-vinylpyrrolidin-2-one to afford 2-aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines. One-pot synthesis of 1,2,3,4-tetrahydroquinolines
from 3-nitro benzaldehyde and aromatic amines with N-vinylpyrrolidin-2-one catalyzed by antimony(III) sulfate is also reported. This catalyst is inexpensive, easily available,
and it was also found that catalyst could be recovered quantitatively and reused without much loss of catalytic activity. 相似文献
40.
Subramanian?Mohanakrishnan?Anusha Santharam?Leelaram Mahadevan?SurianarayananEmail author 《Applied biochemistry and biotechnology》2016,179(6):1041-1059
Bioplastic production from microbial sources is an emerging area which provides opportunities even to convert the wastes into bioplastics. Poly (3-hydroxybutyric acid), commonly called as PHB, is a bioplastic, which is stored as intracellular cytoplasmic inclusions in microorganisms. The objectives of this study are to calorimetrically monitor the PHB production and evaluate the thermokinetic data in a bioreaction calorimeter (BioRC1e). Thus, a well-known PHB-producing bacteria Ralstonia eutropha was selected for batch process in a bioreaction calorimeter. The metabolic heat generated was found to be correlated with the biomass, substrate consumption, oxygen uptake rate (OUR), carbon dioxide evolution rate (CER) and PHB production. The OUR pattern explained the oxidative metabolism of the strain R. eutropha. The heat yields due to biomass and glucose consumption during PHB production were found to be 12.56 and 13.56 kJ/g, respectively. The oxycalorific value obtained for the PHB production was 443.80 kJ/mol of O2. The concentration of PHB obtained in BioRC1e was 4.33 g/L with a production rate of 0.09 g/L/h. The chemical structure of the extracted PHB by R. eutropha was confirmed using fourier transform infrared spectroscopy (FT-IR) and 1H and 13C nuclear magnetic resonance (NMR) analysis. 相似文献