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31.
Cobalt(II)–metformin complexes containing α‐diimine/α‐diamine as auxiliary ligand: DNA binding properties 下载免费PDF全文
The cobalt(II) complexes [Co(Cl)2(met)(o‐phen)] ( 1 ), [Co(Cl)2(en)(met)] ( 2 ) and [Co(Cl)2(met)(opda)] ( 3 ) (met = metformin, o‐phen = ortho‐phenanthroline, en = ethylenediamine, opda = ortho‐phenylenediamine) were synthesized and characterized using liquid chromatography–mass spectrometry, elemental analysis, molar conductance measurements, thermal analysis, infrared spectroscopy, magnetic moment measurements, electronic spectroscopy and X‐ray diffraction. The metal centre was found to be in an octahedral geometry. UV–visible absorption, fluorescence and viscosity measurements were conducted to assess the interaction of the complexes with calf thymus DNA. The complexes showed absorption hyperchromism in UV–visible spectra with DNA. The binding constants from UV–visible absorption studies were 1.38 × 105, 2.1 × 105 and 3.1 × 105 M?1 for 1 , 2 and 3 , respectively, and Stern–Volmer quenching constants from fluorescence studies were 0.146, 0.176 and 0.475, respectively. Viscosity measurements revealed that the binding of the complexes with DNA could be surface binding, mainly due to groove binding. The activities of the complexes in DNA cleavage decrease in the order 3 > 2 > 1 . The complexes were docked into DNA topoisomerase II using Discovery Studio 2.1 software. 相似文献
32.
Nickel-Impregnated Silica Nanoparticle Synthesis and Their Evaluation for Biocatalyst Immobilization
Reddy Shetty Prakasham G. Sarala Devi Chaganti Subba Rao V. S. S. Sivakumar T. Sathish P. N. Sarma 《Applied biochemistry and biotechnology》2010,160(7):1888-1895
In the present investigation, impact of nickel-impregnated silica paramagnetic particles (NSP) as biocatalyst immobilization
matrices was investigated. These nanoparticles were synthesized by sol–gel route using a nonionic surfactant block co polymer
[poly (ethylene glycol)-block-poly-(propylene glycol)-block-poly (ethylene glycol)]. Diastase enzyme was immobilized on these particles (enzyme-impregnated NSP) as model enzyme and
characterized using Fourier-transform infrared spectroscopy and X-ray crystallography. Analysis of enzyme-binding nature with
these nanoparticles at different physiological conditions revealed that binding pattern and activity profile varied with the
pH of the reaction mixture. The immobilized enzyme was further characterized for its biocatalytic activity with respect to
kinetic properties such as Km and Vmax and compared with free enzyme. Paramagnetic nanoparticle-immobilized enzyme showed
more affinity for substrate compared to free one. The nature of silica and nickel varied from amorphous to crystalline nature
and vice versa upon immobilization of enzyme. To the best of our knowledge, this is the first report of its kind for change
of nature from one form to other under normal temperatures upon diastase interaction with NSP. 相似文献
33.
Mandal S Sathish M Saravanan G Datta KK Ji Q Hill JP Abe H Honma I Ariga K 《Journal of the American Chemical Society》2010,132(41):14415-14417
Although artificial capsule structures have been thoroughly investigated, functionality at the surfaces of their interiors has been surprisingly overlooked. In order to exploit this aspect of capsular structure, we here report the breakthrough fabrication of metallic (platinum) microcapsules with sufficient accessibility and electroactivity at both interior and exterior surfaces (open-mouthed platinum microcapsules), and also we demonstrate improvements in electrochemical and catalytic functions to emphasize the practical importance of our concept. The open-mouthed platinum microcapsules were prepared by template synthesis using polystyrene spheres, where surface-fused crystalline nanoparticles formed a capsule shell. Subsequent removal of the polystyrene spheres induced formation of mouth-like openings. The open-mouthed platinum microcapsules exhibit a substantial increase of their electrode capability for methanol oxidation and catalytic activities for carbon monoxide (CO) oxidation. Notably, activity loss during CO oxidation due to undesirable particle agglomeration can be drastically suppressed using the open-mouthed microcapsules. 相似文献
34.
Thermo-acoustic fatigue characterization 总被引:1,自引:0,他引:1
The nondestructive detection of early fatigue damage states is of high importance for safety in aircraft, automobiles, railways, nuclear energy industries and chemical industries. Titanium alloys commonly used in aerospace for structures and engine components are subject to fatigue damage during service. In the current study fatigue damage progression in a titanium alloy (Ti-6Al-4V) was investigated using thermographic detection of the heat dissipated during short-term mechanical loading. The initial rate of temperature increase induced by the short-term mechanical loading was used to indicate the current microstructural state and presence of prior fatigue damage. Two methods for thermal excitation were investigated (a) high amplitude mechanical loading and (b) small amplitude ultrasonic loading. A formula that describes the temperature enhancement due to heat generation during one loading cycle is derived from high amplitude loading data. A correlation between the temperature increase during short-term ultrasonic loading and accumulated fatigue cycles is used to suggest a methodology for in-field assessment of fatigue condition. 相似文献
35.
Rao G. Padma Mohan B. Sathish Siddaiah V. 《Russian Journal of Organic Chemistry》2020,56(11):2028-2031
Russian Journal of Organic Chemistry - The first stereoselective total synthesis of the linear pentaketide Modiolin has been performed via Jacobsen’ hydrolytic kinetic resolution and... 相似文献
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Reactions of [MoO2(acetylacetonate)2], 2‐((2‐(2‐hydroxyethylamino)ethylamino)methyl)‐4‐R‐phenols (H2Ln, n = 1–5 for R = H, Me, OMe, Cl and Br, respectively) and KOH in 1:1:2 mole ratio in methanol afford a series of complexes having the general formula cis‐[MoO2(Ln)] ( 1 , 2 , 3 , 4 , 5 ) in 81–86% yields. The complexes have been characterized using elemental analysis, spectroscopy (infrared, UV–visible, and 1H NMR, 13C NMR and 13C‐DEPT NMR) and electrochemical measurements. The molecular structures of 1 , 2 , 3 , 4 have been determined using single‐crystal X‐ray crystallography. In each of 1 , 2 , 3 , 4 , the ONNO‐donor 6,5,5‐membered fused chelate rings forming (Ln)2− and the two mutually cis oxo groups assemble a distorted octahedral N2O4 coordination sphere around the metal centre. In the crystal lattice, each of 1 , 2 , 3 , 4 forms a one‐dimensional infinite chain structure via intermolecular N H⋅⋅⋅O hydrogen bonding interactions. In cyclic voltammograms, the diamagnetic complexes display an irreversible metal‐centred reduction in the potential range −0.73 to −0.88 V (vs Ag/AgCl). The physicochemical data are consistent with a very similar gross molecular structure for all of 1 , 2 , 3 , 4 , 5 . All the complexes exhibit decent bromoperoxidase activities and are also able to effectively catalyse benzoin and methyl(phenyl)sulfide oxidation reactions. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
38.
P. N. Agrawal Vijay Gupta A. Sathish Kumar 《Rendiconti del Circolo Matematico di Palermo》2014,63(2):193-209
In the present paper, we study some approximation properties of the Durrmeyer type modification of generalized Baskakov operators introduced by Erencin (Appl Math Comput 218(3):4384–4390, 2011). First, we establish a Lorentz-type lemma for the derivatives of the kernel of the generalized Baskakov operators and then obtain a recurrence relation for the moments of their Durrmeyer type modification. Next, we discuss some direct results in simultaneous approximation by these operators e.g. pointwise convergence theorem, Voronovskaja-type theorem and an estimate of error in terms of the modulus of continuity. Finally, we estimate the error in the approximation of functions having derivatives of bounded variation. 相似文献
39.
The first total synthesis of the natural product (+)-oploxyne B is achieved. The synthesis has led to the confirmation of absolute stereochemistry of the natural product. The natural product displayed cytotoxic activity with IC50 values varying from 16 to 53 μM in four cancer cell lines tested. 相似文献
40.
Muthulingam Seenuvasan Kannaiyan Sathish Kumar Carlin Geor Malar Sridhar Preethi Madhava Anil Kumar Nagarajan Balaji 《Applied biochemistry and biotechnology》2014,172(5):2706-2719
The investigation on fabrication of Fe3O4-chitosan-pectinase nanobiocatalyst was performed by covalently binding the pectinase onto carboxyl group activated chitosan-coated magnetic nanoparticles (CMNPs). The morphological and size distribution analysis of the different magnetic nanoparticles (MNPs) was done using transmission electron microscopy (TEM), and the average diameter was 11.07?±?3.04, 11.55?±?3.16, and 11.59?±?3.16 nm for MNPs, CMNPs, and fabricated nanobiocatalyst, respectively, suggesting that there was no significant change in the size of MNPs after coating and binding. The characteristic peaks occurred at 2θ of 30.39, 35.43, 43.37, 57.22, and 62.9, and their corresponding indices 220, 311, 400, 520, and 441 for different MNPs from the X-ray diffraction (XRD) studies confirmed the presence of Fe3O4 with the spinel structure, and there was no phase change even after coating and binding. The various required characteristic absorption peaks (575, 585, 1,563, 1,614, 1,651, and 1,653 cm?1) from Fourier transform infrared (FT-IR) spectroscopy confirmed the surface modifications and binding of pectinase onto the MNPs. At the weight ratio of about 19.8?×?10?3 mg bound pectinase/mg activated CMNPs, the activity of fabricated nanobiocatalyst was found to be maximum. In order to monitor their improved activity, the pH, temperature, reusability, storage ability, and kinetic studies were established. 相似文献