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61.
Virendra Singh Anita Rampal S. N. Biswas K. Datta 《Letters in Mathematical Physics》1980,4(2):131-134
The solution of a difference equation in the form of an infinite continued fraction is used to obtain a class of exact solutions for the eigenfunctions and eigenvalues of doubly anharmonic oscillators described by potentials of the type (1/2)2x2+(1/4)x4+(1/6)x6, n>0, provided certain constraints on the couplings are satisfied. The class is denumerably infinite but not complete. 相似文献
62.
M. M. Charyulu K. Venugopal Chetty D. G. Phal Veena Sagar SagarD. M. Sagar S. M. Pawar R. Swarup V. V. Ramakrishna V. Venugopal 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(1):153-154
Recovery of americium from nitric acid solutions was studied by co-precipitation as hydroxide with various ions like calcium, ferric, nickel using sodium hydroxide and ammonium hydroxide. Studies were also carried out to recover americium using lanthanum fluoride and bismuth phosphate co-precipitation. All the methods are able to co-precipitate Am quantitatively. However, co-precipitation of Am with optimum concentration iron using ammonia is found to be better from nitric acid solutions containing large concentrations of calcium ions. Approximately 2 g of Am was recovered from 150 litres of solution batch wise using iron. 相似文献
63.
The polymerization of N-vinylcarbazole (NVC) initiated by PhMgBr in benzene was studied at 32°C. Rp is second order with respect to PhMgBr concentration but increases with NVC concentration (up to 0.06 M) and falls thereafter. Rp and P n are depressed by the addition of thiophene and water. Modifiers such as benzaldehyde, butanone, and ethylene glycol practically inhibit the polymerization. Carbon tetrachloride and carbon dioxide, when passed through the NVC solution first, enhance the Rp and P n increases with increasing PhMgBr and NVC concentrations, respectively. Rp increases with temperature, but P n shows a maxium at a certain temperature. A cationic mechanism has been proposed where the polymerization is initiated by RMg+ cations produced from the ionization of PhMgBr by the Ashby and Smith mechanism. 相似文献
64.
Chary KV Sagar GV Naresh D Seela KK Sridhar B 《The journal of physical chemistry. B》2005,109(19):9437-9444
A series of copper catalysts supported on TiO2-ZrO2 with copper loading varying from 1.0 to 21.6 wt % were prepared by a wet impregnation method. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy, electron spin resonance (ESR), temperature programmed reduction (TPR), and Brunauer-Emmett-Teller specific surface area measurements. Copper dispersion and metal area were determined by N2O decomposition by the passivation method. XRD results suggest that the copper oxide is present in a highly dispersed amorphous state at copper loadings <16.8 wt % in the sample and as a crystalline CuO phase at higher Cu loadings. Copper dispersion increases with Cu loading up to 5.1 wt % and levels off at higher loadings. The XPS peak intensity ratios of Cu 2p(3/2)/Ti 2p(3/2) and Cu 2p(3/2)/Zr 3d(5/2) were compared with the copper dispersion calculated from N2O decomposition. ESR results suggest the presence of two types of copper species on the TiO2-ZrO2 support. TPR profiles reveal the presence of highly dispersed copper oxide at lower temperatures and bulk CuO at higher temperatures. The catalytic properties were evaluated for the vapor-phase dehydrogenation of cyclohexanol to cyclohexanone and related to the dispersion of Cu on TiO2-ZrO2. 相似文献
65.
A highly atom-efficient synthetic protocol for hydroarylation of terminal-aryl alkynes and styrene through the regioselective CC bond formation via the electrophilic addition of naphthols and substituted phenols has been developed using alumina-sulfuric acid as a heterogeneous supported solid acid catalyst. This methodology shows excellent regioselectivity and affords the desired product in good to excellent yield. The heterogeneous catalyst can also be recycled efficiently without much loss of activity. 相似文献
66.
Njardarson JT Biswas K Danishefsky SJ 《Chemical communications (Cambridge, England)》2002,(23):2759-2761
A total synthesis of Epothilone 490 and a synthesis of 11-hydroxy dEpoB utilizing a vinyl-boronate cross-metathesis followed by a Suzuki macrocyclization. A mild route to reach aldehydes from terminal olefins, anticipating Nozaki-Kishi macrocyclization is described. 相似文献
67.
A Sarkar N Biswas S Kapoor H S Mahal C K K Nair T Mukherjee 《Research on Chemical Intermediates》2005,31(9):857-866
The oxidation of flavonoids is of great interest because of their action as antioxidants with the ability to scavenge radicals
by means of electron-transfer processes. The redox reactions of the flavonoid derivative troxerutin, (2-[3,4-bis-(2-hydroxyethoxy)
phenyl]-3[[6-deoxy-α-L-manno-pyranosyl)-β-(D-glucopyranosyl]-oxy]-5-hydroxy-7-(2-hydroxyethoxy)-4H-1-benzo-pyran-4-one), were investigated over a wide range of conditions,
using pulse radiolysis and cyclic voltammetry. The oxidation mechanism proceeds in sequential steps. One-electron redox potentials
for troxerutin were found to be +1.196, +0.846 and −0.634 V vs. NHE. 相似文献
68.
Hussain SA Deb S Biswas S Bhattacharjee D 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2448-2454
This communication reports the surface pressure (pi) versus area per molecule (A) isotherm characteristics of the mixed films of 9-phenyl anthracene (PA) in stearic acid (SA) and polymethyl methacrylate (PMMA) matrices, at the air-water interface. The mixed Langmuir films at the air-water interface have been observed to be easily transferred onto solid substrates to form uniform Langmuir-Blodgett films. By changing various parameters, namely molefraction, surface pressure of lifting and number of layers, the mixed Langmuir-Blodgett (LB) films of various types have been fabricated successfully and their spectroscopic characteristics have been reported. From the isotherm characteristics and the area per molecule versus molefraction plot, it is evident that the PA molecules are successfully incorporated into mixed Langmuir-Blodgett films. UV-vis absorption spectroscopic study of the mixed LB films at various molefractions of PA in two different matrices reveal that formation of I-type aggregate in PMMA matrix whereas both I- and H-type aggregates are playing their dominant role in SA matrix. Moreover, fluorescence spectroscopic study reveals reabsorption effect. Molecular movement persists in the freshly prepared LB films, as is evident from the time dependent changes in both UV-vis absorption and fluorescence spectra of the mixed LB films in both matrices. From our observation it is evident that about 200 h is required to get the LB films in a stable condition. Dimers and higher order n-mers are formed at a higher surface pressure of 30 mNm(-1). 相似文献
69.
Sarmiento M Mooney P Bishop JM Biswas N Cason NM Dauwe L Godfrey J Kenney VP Pemper R Rojek E Ruchti RC Shephard WD Edelstein RM Forsyth CP Gamarnik K Ginther G Kreymer AE Lipton R McQuade JM Potter DM Russ JS Spiegel L Johnson DE Buchholz D Cremaldi L Delchamps SW Mao HS Rosen JL Sakumoto W Schluter RA Sontz SB Winter C 《Physical review D: Particles and fields》1992,45(7):2244-2248
70.
Swadesh Kumar Gupta Dharmendra Pratap Singh Pankaj Kumar Tripathi Mahesh Varia Laxmi K. Sagar 《Liquid crystals》2013,40(4):528-533
Cadmium selenide quantum dot (CdSe QD) has been used as a dopant in ferroelectric liquid crystal (FLC) 2-methylbutyl 4-(4-decyloxybenzylideneamino) cinnamate (DOBAMBC). Effect of CdSe QD in DOBAMBC on its different electro-optical (E-O) properties has been studied in the SmC* phase. The optical micrographs recorded for the pure and composite material are showing good dispersion of QDs in the FLC matrix. Micrographs of unaligned sample cell revealed that CdSe QDs induce homeotropic alignment of FLC molecules. An appreciable change in the value of E-O parameters like tilt angle, spontaneous polarisation and response time with shifting of SmA–SmC* phase transition temperature has been observed for CdSe QD–DOBAMBC composite. The observed properties of composite system have been discussed on the basis of surface properties of QDs in FLC system. 相似文献