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61.
We report the optical investigation and analysis of both nano-sized and micrometer size Cadmium Sulphide particles which is
embedded in a transparent polyvinyl alcohol (PVOH) dielectric host material. A designed and fabricated laser based light scattering
system using a He-Ne laser of wavelength 632.8nm was used for the measurement and study of the scattering properties of the
particles as a function of the scattering angle at this wavelength. An attempt was made to experimentally determine the most
significant elements of the Mueller scattering matrix using combinations of randomly and linearly polarized incident laser
beam and subsequent analyzers in corresponding orientations. The analysis of the experimental data was done by the method
of comparison with theoretically generated data. Novel computational technique, involving single scattering for spherical
particles using Mie-theory, was developed and applied. The theoretical data was found to be in good agreement with the experimental
data within an acceptable margin of error. The results have proved that the combination of the experimental setup and associated
computational method is a highly efficient and reliable in-situ system for monitoring size growth of semiconductor particles
in the laboratory. 相似文献
62.
Verbalactone, a new macrocyclic dilactone was synthesized efficiently in a steroselective manner involving a Barbier-Grignard reaction, a Sharpless asymmetric dihydroxylation, monotosylation, epoxidation, ring opening of the epoxide, hydrolysis and lactonization. A δ-lactone, (+)-(3R,5R)-3-hydroxy-5-decanolide was also formed along with the dimeric lactone. 相似文献
63.
Aparajita Duarah Amrit Goswami Tarun C. Bora Madhumita Talukdar Binod K. Gogoi 《Applied biochemistry and biotechnology》2013,170(8):1965-1973
An effort was made to isolate biocatalysts hydrolyzing epoxides from various ecological niches of northeast India, a biodiversity hot spot zone of the world and screened for epoxide hydrolase activity to convert different racemic epoxides to the corresponding 1, 2-vicinal diols. Screening of a total of 450 microorganisms isolated was carried out using NBP colorimetric assay. One of the strains TF1, after internal transcribed spacer sequence analysis, identified as Aspergillus tubingensis, showed promising enantioconvergent epoxide hydrolase activity. The hydrolysis of unsubstituted styrene oxide (1) occurred to give 97 % ee of R-(?)-1-phenylethane-1, 2-diol (6) with more than 99 % conversion within 45 min incubation. It is shown to be a cheap and practical biocatalyst for one step asymmetric synthesis of chiral R-diol. The other representative substrates (2–5), although underwent hydrolysis with more than 99 % conversion beyond 15 h, exhibited poor enantioselectivity. 相似文献
64.
Renaud Ruamps Dr. Luke J. Batchelor Dr. Rémi Maurice Dr. Nayanmoni Gogoi Pablo Jiménez‐Lozano Prof. Nathalie Guihéry Prof. Coen de Graaf Dr. Anne‐Laure Barra Dr. Jean‐Pascal Sutter Prof. Talal Mallah 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):950-956
The nature and magnitude of the magnetic anisotropy of heptacoordinate mononuclear NiII and CoII complexes were investigated by a combination of experiment and ab initio calculations. The zero‐field splitting (ZFS) parameters D of [Ni(H2DAPBH)(H2O)2](NO3)2 ? 2 H2O ( 1 ) and [Co(H2DAPBH)(H2O)(NO3)](NO3) [ 2 ; H2DAPBH=2,6‐diacetylpyridine bis‐ (benzoyl hydrazone)] were determined by means of magnetization measurements and high‐field high‐frequency EPR spectroscopy. The negative D value, and hence an easy axis of magnetization, found for the NiII complex indicates stabilization of the highest MS value of the S=1 ground spin state, while a large and positive D value, and hence an easy plane of magnetization, found for CoII indicates stabilization of the MS=±1/2 sublevels of the S=3/2 spin state. Ab initio calculations were performed to rationalize the magnitude and the sign of D, by elucidating the chemical parameters that govern the magnitude of the anisotropy in these complexes. The negative D value for the NiII complex is due largely to a first excited triplet state that is close in energy to the ground state. This relatively small energy gap between the ground and the first excited state is the result of a small energy difference between the dxy and ${{\rm{d}}_{x^2 - y^2 } }$ orbitals owing to the pseudo‐pentagonal‐bipyramidal symmetry of the complex. For CoII, all of the excited states contribute to a positive D value, which accounts for the large magnitude of the anisotropy for this complex. 相似文献
65.
Subrata Borgohain Gogoi 《Transport in Porous Media》2011,90(2):589-604
Surfactant loss due to adsorption on the porous medium of an oil reservoir is a major concern in enhanced oil recovery. Surfactant
loss due to adsorption on the reservoir rock weakens the effectiveness of the injected surfactant in reducing oil–water interfacial
tension (IFT) and making the process uneconomical. In this study, surfactant concentrations in the effluent of the corefloods
and oil–water IFT were determined under different injection strategies. It was found that in an extended waterflood following
a surfactant slug injection, surfactant desorbed in the water phase. This desorbed surfactant lasted for a long period of
the waterflood. The concentration of the desorbed surfactant in the extended waterflood was very low but still an ultralow
IFT was obtained by using a suitable alkali. Coreflood results show an additional recovery of 13.3% of the initial oil in
place was obtained by the desorbed surfactant and alkali. Results indicate that by utilizing the desorbed surfactant during
the extended waterflood operation the efficiency and economics of the surfactant flood can be improved significantly. 相似文献
66.
D. Gogoi J. Chutia A. J. Choudhury A. R. Pal N. N. Dass D. S. Patil 《Plasma Chemistry and Plasma Processing》2012,32(6):1293-1306
Radiofrequency (RF) Ar/propylene glow discharge is utilized for grafting polypropylene onto muga silk yarn at working pressure of 1.2?×?10?1 mbar and in the of RF power range of 20?C80?W. The plasma discharge is diagnosed using self-compensated emissive probe to study the variation of ion energy impinging on the substrates with RF power. From chemical compositional analysis, a possible grafting mechanism between propylene and muga yarn is proposed by considering the charge-transfer initiation through the formation of electron-donor?Cacceptor (EDA) complex. X-ray photoelectron spectroscopy reveals that at RF power values of 60?C80?W, the ion sputtering effect becomes dominant over plasma grafting thereby leading to severe destruction in chemical structure of the polypropylene grafted (PP-grafted) muga yarns. The experimental results show that PP-grafted muga yarns exhibit improved mechanical strength and hydrophobic behavior as compared to the virgin yarn. The properties of the PP-grafted muga yarns are observed to be dependent on atomic concentration, surface morphology as well as the results obtained from plasma discharge characteristics. 相似文献
67.
Paramartha Gogoi Trimurthulu Kotipalli Kiran Indukuri Somasekhar Bondalapati Pipas Saha Anil K. Saikia 《Tetrahedron letters》2012,53(22):2726-2729
A chiral 1,3-diol with a benzyl backbone has been used for the asymmetric oxidation of sulfides to sulfoxides. Moderate to good yields and enantioselectivity (upto 87% ee) have been observed. 相似文献
68.
We have reported here the catalytic activity of a unique Cu–salen type complex in N-arylation of anilines with arylboronic acids in water. The protocol is found to be applicable for a wide range of electronically diversified arylboronic acids and anilines with excellent yields of the isolated product. Further the scope of this protocol has been extended to the synthesis of various N-aryl imidazoles in iso-propanol. 相似文献
69.
Gaurangi Gogoi Ching Thian Moi Anindya Sundar Patra Devipriya Gogoi Peela Nageswara Rao Mohammad Qureshi 《化学:亚洲杂志》2019,14(24):4607-4615
One of the major limiting factors for efficient photoelectrochemical water oxidation is the fast recombination kinetics of photogenerated charge carriers. Herein, we propose a model system that utilizes ZnIn2S4 and hierarchical VS2 microflowers for efficient charge separation through a Z‐scheme pathway, without the need for an electron mediator. An impressive 18‐fold increase in photocurrent was observed for ZnIn2S4–VS2 compared to ZnIn2S4 alone. The charge‐transfer dynamics in the composite were found to follow a Z‐scheme pathway, which resulted in decreased charge recombination and greater accumulation of the surface charge. Furthermore, slow kinetics of the surface reaction in the ZnIn2S4–VS2 composite correlated to an increased surface‐charge capacitance. This feature of the composite material facilitated partial storage of the photogenerated charge carriers (e?/h+) under illumination and dark‐current conditions, thus storing and utilizing solar energy more efficiently. 相似文献
70.
Shakya Anshul Gogoi Neelutpal Chaudhary Sushil Kumar Bhat Hans Raj Ghosh Surajit Kumar 《平面色谱法杂志一现代薄层色谱法》2019,32(5):371-377
JPC – Journal of Planar Chromatography – Modern TLC - The fruits of Benincasa hispida (Thunb.) Cogniaux, a ‘rasayana’ in ‘Ayurveda’, are enriched with several... 相似文献