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51.
Y. Lakshman Kumar R. Venkata Nadh P. S. Radhakrishnamurti 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(3):552-559
Role of added chloride ions on the shift of reaction pathway of oxidation of aromatic ketones (acetophenone, desoxybenzoin) by dichloroisocyanuric acid (DCICA) was studied in aqueous acetic acid—perchloric acid medium. Participation of enolic and protonated forms of ketones in the rate determining steps is manifested from zero and first orders with respect to the oxidant in absence and presence of added chloride ions, respectively. Positive and negative effects of acid and dielectric constant on the reaction rate were observed. The observations deduce plausible mechanisms involving (i) rate-determining formation of enol from the conjugate acid of the ketone (SH+) in the absence of added chloride ions and (ii) rapid formation of molecular chlorine species from HOCl (hydrolytic species of DCICA) in the presence of added chloride ions, which then interacts with SH+ in a rate-determining step prior to the rapid steps of product formation. The order of Arrhenius parameters substantiate the proposed plausible mechanisms based on order of reactants both in presence and absence of added chloride ions. 相似文献
52.
The absorption spectrum of manganese formate dihy-drate has been studied at liquid nitrogen temperature (80 K) in the region λ 650 nm to 300 nm. Three bands of the spectrum resolved themselves exhibiting fine structure. The splitting of the 4Eg (G) band is explained as due to exciton-magnon interaction. Weak bands on either side of 4A1g (G) band are assigned to phonon progressions with = 0.12 kK. The fine structure of the 4T2g (D) band is explained as due to spin-orbit interaction. The observed band positions are fitted to four parameters B, C, ηq and α the best fit being obtained with B = 0.82 kK; C = 3.02 kK; Dq = 0.81 kK; α = 0.076 kK. 相似文献
53.
Lakshmi R. Lakshman K. T. Shalumon Sreeja V. Nair R. Jayakumar S. V. Nair 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1012-1018
Polyurethane foam is currently used as an exudate absorptive wound dressing material. In this study silver (Ag) nanoparticles were incorporated into electrospun polyurethane (PU) nanofiber to enhance the antibacterial as well as wound healing properties. The electrospinning parameters were optimized for PU with and without silver nanoparticles. Silver nanoparticles were synthesized by aqueous and organic methods. The water absorption, antibacterial and cytocompatibility of the PU-Ag nanofibers were studied and compared to that of conventional PU foam. The results indicated that the PU-Ag nanofibers could be used for wound dressing applications. 相似文献
54.
A stochastic model to study the solidifcation process developed in part I is applied to various binary alloys having different
values of interaction energies. The results obtained for the time evolution of temperature and concentration, rate of growth
and shape of the solid-liquid interface are presented. 相似文献
55.
56.
Santosh S. Katkar Pravinkumar H. Mohite Lakshman S. Gadekar Balasaheb R. Arbad Machhindra K. Lande 《Central European Journal of Chemistry》2010,8(2):320-325
A rapid and an efficient one-pot method for the synthesis of quinoxalines catalysed by ZnO-beta zeolite at room temperature
is described. This environmentally benign method provides several advantages over methods that are currently employed such
as a simple work-up, mild reaction conditions, good to excellent yields, and a process to recover and reuse the catalyst for
several cycles with consistent activity.
相似文献
57.
58.
The results obtained in the study of the absorption spectrum of Ni2+ in two samples of Garnierite are described. Both the samples of Garnierite have been studied by preparing their mineral oil mulls. One of these samples could however be studied in its crystal form as well. From the observed features, the absorption bands in both the samples of Garnierite have been attributed to an ion of Ni2+ in tetrahedral symmetry. The observed and calculated energies for the bands are found to be in close agreement with one another justifying the assumption that the site symmetry of Ni2+ ion is tetrahedral. For one of the Garnierite samples both the crystal and mineral oil mull spectra could be recorded and it is interesting to find that they are identical with one another. It has therefore been suggested that the absorption spectrum of any mineral can be studied by preparing its mineral oil mull in case it cannot be cut and polished into a thin crystal suitable for absorption work. The crystal field parameters derived for the two samples of Garnierite are identical and they are B = 845 cm?1, C = 3.9 B, Dq = 422 cm?1 and λ = ? 275 cm?1. 相似文献
59.
M. Venkataramanaiah S.V.J. Lakshman 《Journal of Quantitative Spectroscopy & Radiative Transfer》1981,26(1):11-13
The true potential energy curves have been constructed for the ground and excited electronic states of SiCl by the method of Lakshman and Rao. The dissociation energy of the ground state has been estimated by fitting the Hulburt-Hirschfelder function to the true potential energy curves. The dissociation energy thus obtained is 33,500 cm-1 (4.15 eV), which is in good agreement with the value of 4.5±0.5 eV reported by Gaydon. 相似文献
60.
Palladium-catalyzed C-N bond formation has been utilized to synthesize covalent 2'-deoxyadenosine (dA) and 2'-deoxyguanosine (dG) adducts of benzo[a]pyrene (BaP) series 1 (syn) and benzo[c]phenanthrene (BcPh) series 2 (anti) diol epoxides. For this, (+/-)-10 alpha-amino-7 beta,8 alpha,9 beta-trisbenzoyloxy-7,8,9,10-tetrahydro BaP and (+/-)-1 beta-amino-2 alpha,3 alpha,4 beta-trisbenzoyloxy-1,2,3,4-tetrahydro BcPh were coupled with 6-halo-9-[3,5-bis-O-(tert-butyldimethylsilyl)-beta-D-erythro-pentofuranosyl]purine and O6-benzyl-3',5'-bis-O-(tert-butyldimethylsilyl)-2-bromo-2'-deoxyinosine, using a (+/-)-BINAP-Pd complex and Cs2CO3. For the synthesis of the dA adducts, both the 6-chloro- as well as the 6-bromopurine nucleoside derivatives were analyzed for the C-N coupling reaction with the hydrocarbon amino tribenzoates. With the BaP amino tribenzoate, the 6-chloronucleoside provided satisfactory results, whereas the 6-bromo analogue proved to be superior with the BcPh amino tribenzoate. Overall, lower yields of the dA adducts were obtained with the more hindered fjord-region BcPh amino tribenzoate as compared to the bay-region BaP amino tribenzoate. In contrast to reactions leading to the dA adducts, the C-N reactions of both BaP and BcPh amino tribenzoates with the 2-bromo-2'-deoxyinosine derivative proceeded in comparable yields. This seems to indicate that such Pd-catalyzed adduct forming reactions at the C-6 position may be influenced by steric constraints of the amine component, whereas those at the C-2 position are less sensitive. Diastereomeric adduct pairs were separated and characterized by spectral methods and by comparisons to adducts produced by direct displacement reactions as well as those formed from DNA alkylation by diol epoxides. 相似文献