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121.
Gourisankar Panda Md. Selim Rupali Pal Kalyan K. Mukherjea 《Monatshefte für Chemie / Chemical Monthly》2009,33(2):281-286
Abstract
The interaction of cobalt(II)-glutathione (CoGSH) with deoxyribonucleic acid (DNA) has been studied by UV–vis, fluorescence, circular dichroism (CD), thin-film infrared (IR), and viscometric techniques. From the UV-spectroscopic method, binding constant (K b) was determined and was found to be 2.3 × 106 M−1. In fluorimetric analysis, the quenching of fluorescence intensity of DNA bound to ethidium bromide (EB) was investigated. The Stern–Volmer quenching constant (K sv) was also estimated from this study and was found to be 2.8 × 106 M−1at 37 °C. The solution CD spectra of DNA and DNA–CoGSH indicate that in each case, DNA exists in the ‘B’ conformation and suggested an intercalative binding mode. Thin-film IR data also reveal that DNA attains the ‘B’ family of conformations after interaction with CoGSH complex. The increase in DNA viscosity in the presence of CoGSH complexes is attributed to the lengthening of DNA helix due to intercalation. 相似文献122.
Chromone-3-carbaldehyde reacts with N-methylglycine or glycine in the presence of excess formaldehyde to produce N-(chromone-3-ylmethyl)-N-methylglycine or N,N-di(chromone-3-ylmethyl)glycine, respectively, by a deformylative Mannich type reaction. Use of alanine or leucine or methionine in place of glycine produces N-(chromone-3-ylmethyl)alanine/-leucine/-methionine, respectively. 相似文献
123.
Suzuki-Miyaura coupling reaction of N-protected 4-iodopheyl alanine isoxazoles with arylboronic acids, catalyzed by palladium, efficiently produce benzyl-N-(4-bipheyl)-2-(3-methyl-5(E)-2-aryl-1-ethenyl-4- isoxazolyl)-amino-2-oxoethyl) carba-mates in good yields. This process is first of its kind to construct carbon-carbon bond formation having biaryl motif on amino acid linked isoxazole moiety. 相似文献
124.
Madhuri Mandal Debabrata Pal Kalyan Mandal 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):35-38
Snow-ball flower like Ni nanoparticles have been synthesized using negatively charged micelles. Negatively charged micelles incorporate the Ni+2 onto its head group by electrostatic attraction and again a surfactant layer is arranged on positively charged Ni and thus in a repetitive way layer-by-layer a snow-ball flower like structure is formed. After reduction of Ni+2 to Ni atom by sodium borohydride and hydrated hydrazine the Ni clusters (3 nm) are formed and confined in micelles in snow-ball flower like pattern. The sizes of these nanoflowers are of 30 nm order. The particles are superparamagnetic in nature with blocking temperature about 117 K. 相似文献
125.
Sebika Kangsha Banik Debika Kangsha Banik Kalyan Bhuyan 《General Relativity and Gravitation》2018,50(2):24
The cosmological dynamics of spatially homogeneous but anisotropic Bianchi type-III space-time is investigated in presence of a perfect fluid within the framework of Hu–Sawicki model. We use the dynamical system approach to perform a detailed analysis of the cosmological behaviour of this model for the model parameters \(n=1, c_1=1\), determining all the fixed points, their stability and corresponding cosmological evolution. We have found stable fixed points with de Sitter solution along with unstable radiation like fixed points. We have identified a matter like point which act like an unstable spiral and when the initial conditions of a trajectory are very close to this point, it stabilizes at a stable accelerating point. Thus, in this model, the universe can naturally approach to a phase of accelerated expansion following a radiation or a matter dominated phase. It is also found that the isotropisation of this model is affected by the spatial curvature and that all the isotropic fixed points are found to be spatially flat. 相似文献
126.
Rajendra Bhatia Dinesh Singh Kalyan B. Sinha 《Communications in Mathematical Physics》1998,191(3):603-611
Given a smooth real function f on the positive half line consider the induced map on the set of positive Hilbert space operators. Let f
(k<)
/E5> be the
k
th
derivative of the real function
f
and >E5>D
k
f the k
th Fréchet derivative of the operator map f. We identify large classes of functions for which , for k= 1,2,... . This reduction of a noncommutative problem to a commutative one makes it easy to obtain perturbation bounds for
several operator maps. Our techniques serve to illustrate the use of a formalism for “quantum analysis” that is like the one
recently developed by M. Suzuki.
Received: 4 April 1997 / Accepted: 28 May 1997 相似文献
127.
S B Roy Shailendra Kumar A K Pradhan P Chaddah Ram Prasad N C Soni Kalyan Adhikary 《Pramana》1993,41(1):51-60
We present measurements of harmonic generation in the magnetization of sintered pellets of YBa2Cu3O7 and Bi1.7Pb0.3Sr2Ca2Cu3O10 as a function of DC field. The DC field is applied in the field-cooled mode. Measurements are made at 77 K for various values
of the AC field amplitude. A comparison is made with calculations done within the critical state model. 相似文献
128.
Seema Varshney Pradeep K. Sharma Kalyan K. Banerji 《Journal of Chemical Sciences》1992,104(5):603-610
Oxidation of three lower oxyacids of phosphorus, viz. phosphinic, phenylphosphinic and phosphorous acids by pyridinium hydrobromide
perbromide (PHPB), is first-order with respect to both oxyacid and PHPB. There is no effect on addition of acylonitrile and pyridinium bromide.
On oxidation, deuterated phosphinic and phosphorous acids exhibit substantial kinetic isotope effects. The effect of solvent
composition on reaction rate indicates that the transition state is more polar than the reactants. Reaction rates were determined
at different temperatures and the activation parameters calculated. Alternative mechanisms, involving the two tautomeric forms
of the oxyacid, have been formulated and it has been concluded that the reaction proceeds through the pentacoordinated tautomer.
Transfer of a hydride ion from the oxyacid to PHPB, in the rate-determining step, has been proposed. 相似文献
129.
We consider the problem of finding a minimum-cost set ofk pairwise-disjoint (s, t)-cuts in a graph. For non-negative costs, this problem was solved independently by Nishihara and Inoue, and Wagner. Both solutions involve formulating the problem as a linear-programming problem. In this paper, we give new polyhedral interpretations of the problem. Relationships to the path formulation of the maximum-flow problem are also established.Corresponding author. 相似文献
130.
Gupta Kalyan K. Sen Bhattacharjee Nandini Pal Biswajit Ghosh Saktiprosad 《Transition Metal Chemistry》1999,24(3):268-273
The kinetics of oxidation of the neutralized -hydroxy acids: lactic, -hydroxyisobutyric, mandelic, benzilic and atrolactic acids by tris(pyridine-2-carboxylato)manganese(III) have been studied. The reactions were carried out in a Na(pic)-picH [Na(pic) = sodium salt of pyridine-2-carboxylic acid and picH = pyridine-2-carboxylic acid] buffer medium in the 4.89–6.10pH range. The oxidation rate was found to be independent of pH, and rate follows the order: benzilate > mandelate >atrolactate>lactate > -hydroxy isobutyrate. The oxidation products are MeCHO, Me2CO, PhCHO, Ph2CO and PhCOMe for the respective reactions. A mechanism is proposed involving intermediate formation of hepta-coordinated MnIII complexes in a fast step. The complexes then decompose to give free radicals and MnII in the rate determining step. The free radicals subsequently react with another molecule of the MnIII species to give the respective carbonyl compounds in a fast step. 相似文献