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排序方式: 共有207条查询结果,搜索用时 31 毫秒
81.
82.
Murugan E Sherman RL Spivey HO Ford WT 《Langmuir : the ACS journal of surfaces and colloids》2004,20(19):8307-8312
Four different quaternary ammonium chloride-modified poly(propylenimine) (PPI) dendrimers were synthesized by alkylation of a PPI dendrimer having eight dimethylamino end groups with 1-bromooctane or 1-bromododecane. By varying the mole ratio of alkyl bromide to dendrimer, averages of 4-10 quaternary ammonium groups were formed. The new amphiphilic dendrimers are surface active and are micellar catalysts in water. The dendrimers have critical aggregation concentrations between 8.5 x 10(-4) and 9.0 x 10(-5) M. Decarboxylation of 6-nitrobenzisoxazole-3-carboxylate at 25 degrees C was 650 times faster than in water alone in the presence of a dendrimer quaternized with eight dodecyl chains at a concentration of 2.45 mM in quaternary ammonium groups. The order of the catalytic efficiency of the new dendrimers decreased with the length and number of hydrophobic alkyl groups in the order (C(12))(8) > (C(12))(4) > (C(8))(10) > (C(8))(5). The pseudo-first-order rate constants for basic hydrolysis of p-nitrophenyl hexanoate in pH 9.4 buffer at 30 degrees C using the (C(12))(8) and (C(12))(4) dendrimers were 26 and 13 times higher than those for hydrolysis with no dendrimer. The kinetic data were fit to a single-site binding model to evaluate the contributions of binding constants of reactants to the dendrimers and catalytic rate constants of the bound species to the overall catalytic activity. 相似文献
83.
Alan R. Katritzky Ramiah Murugan Kumars Sakizadeh 《Journal of heterocyclic chemistry》1984,21(5):1465-1467
Depending on the conditions, and the basicity of the amine, arylamines react with chelidonic acid to yield five different types of product: salts, N-arylchelidamic acids, N-aryl-4-pyridone-2-carboxylic acids, N-aryl-4-pyridones, or chelidamic acid itself. 相似文献
84.
Suresh Ranga Rao Rajasekaran Subbarayan Murugan Girija Dinesh Gnanamani Arumugam Selvaraj Thirupathi Kumara Raja 《Experimental & molecular medicine》2016,48(2):e209
The success of regeneration attempt is based on an ideal combination of stem cells, scaffolding and growth factors. Tissue constructs help to maintain stem cells in a required area for a desired time. There is a need for easily obtainable cells, potentially autologous stem cells and a biologically acceptable scaffold for use in humans in different difficult situations. This study aims to address these issues utilizing a unique combination of stem cells from gingiva and a hydrogel scaffold, based on a natural product for regenerative application. Human gingival mesenchymal stem cells (HGMSCs) were, with due induction, differentiated to neuronal lineages to overcome the problems associated with birth tissue-related stem cells. The differentiation potential of neuronal lineages was confirmed with suitable specific markers. The properties of mesenchymal stem cells in encapsulated form were observed to be similar to free cells. The encapsulated cells (3D) were then subjected to differentiation into neuronal lineages with suitable inducers, and the morphology and gene expression of transient cells were analyzed. HGMSCs was differentiated into neuronal lineages as both free and encapsulated forms without any significant differences. The presence of Nissl bodies and the neurite outgrowth confirm the differentiation. The advantages of this new combination appear to make it a promising tissue construct for translational application. 相似文献
85.
Arun Prasad Murthy Jayaraman Theerthagiri Jagannathan Madhavan Kadarkarai Murugan 《Journal of Solid State Electrochemistry》2018,22(2):365-374
A single-step electrochemical deposition of NiS thin films incorporating various carbon nanomaterials as support is described. Advantages of this method are as follows: It is simpler and can be easily scaled up, the precursors employed are cheaper, and the deposition method is energy effective requiring no further heat treatments. Benefits of carbon nanomaterials as catalyst support are manifold including high conductivity and stability. The carbon-supported thin films exhibit high hydrogen evolution activity, low Tafel slopes, and improved double layer capacitance. A remarkable enhancement in the stability of the thin films in the acid medium has been observed. Specifically, NiS/carbon nanofibers have shown the highest activity, lowest Tafel slope, and retained more than 90% of its initial activity after the stability tests. 相似文献
86.
Kadarkarai Murugan Anitha Jaganathan Rajapandian Rajaganesh Udaiyan Suresh Jagan Madhavan Sengottayan Senthil-Nathan Aruliah Rajasekar Akon Higuchi Suresh S. Kumar Abdullah A. Alarfaj Marcello Nicoletti Riccardo Petrelli Loredana Cappellacci Filippo Maggi Giovanni Benelli 《Journal of Cluster Science》2018,29(1):27-39
Green fabricated nanoparticles often need to be encapsulated and stabilized, to ensure uniform dispersion in the aquatic environment and relevant larvicidal activity over time. However, recent research showed that nanoencapsulation processes led to a reduction of nanoparticle larvicidal efficacy. We used an extract of Argemone mexicana to reduce TiO2 nanoparticles, which were then capped with PSS/PAH (poly(styrene sulfonate)/poly(allylamine hydrochloride)). The toxic and repellent potential of the nanoparticles were compared to elucidate their potential effects against the Zika virus vector Aedes aegypti. Nanoparticles were characterized by biophysical methods including UV–Vis, EDX and FTIR spectroscopy, SEM, TEM, XRD and DLS analyses. In larvicidal and pupicidal experiments, TiO2 nanoparticles achieved LC90 values from 41.648 (larva I), to 71.74 ppm (pupa). Nanoencapsulated TiO2 achieved LC90 values from 39.16 (I), to 69.12 ppm (pupa). In adulticidal experiments, LC90 of TiO2 nanoparticles on Ae. aegypti was 10.31 ppm, while LC90 of nanoencapsulated TiO2 was 9.54 ppm. At 10 ppm, the repellency towards Ae. aegypti was 80.43% for TiO2 nanoparticles, and 88.04% for nanoencapsulated TiO2. This research firstly highlighted the promising potential of PSS/PAH encapsulation, leading to the production of highly effective titania nanostructures, if compared to titania nanoparticles synthesized with eco-friendly routes without further stabilization. 相似文献
87.
R. Murugan 《Journal of mathematical chemistry》2018,56(2):508-556
Analytical solution to the Michaelis–Menten (MM) rate equations for single-substrate enzyme catalysed reaction is not known. Here we introduce an effective scaling scheme and identify the critical parameters which can completely characterize the entire dynamics of single substrate MM enzymes. Using this scaling framework, we reformulate the differential rate equations of MM enzymes over velocity-substrate, velocity-product, substrate-product and velocity-substrate-product spaces and obtain various approximations for both pre- and post-steady state dynamical regimes. Using this framework, under certain limiting conditions we successfully compute the timescales corresponding to steady state, pre- and post-steady states and also compute the approximate steady state values of velocity, substrate and product. We further define the dynamical efficiency of MM enzymes as the ratio between the reaction path length in the velocity-substrate-product space and the average reaction time required to convert the entire substrate into product. Here dynamical efficiency characterizes the phase-space dynamics and it would tell us how fast an enzyme can clear a harmful substrate from the environment. We finally perform a detailed error level analysis over various pre- and post-steady state approximations along with the already existing quasi steady state approximations and progress curve models and discuss the positive and negative points corresponding to various steady state and progress curve models. 相似文献
88.
Manju?Bhargavi?Gumpu Murugan?Veerapandian Uma?Maheswari?Krishnan John?Bosco?Balaguru?RayappanEmail author 《Mikrochimica acta》2018,185(6):297
The authors describe an amperometric biosensor for the determination As(III) and Cd(II) based on the inhibition of the enzyme acetylcholineesterase (AChE). A platinum electrode was modified with ruthenium(II)-tris(bipyridyl), graphene oxide and AChE and then showed redox peaks at 0.06 and 0.2 V vs Ag/AgCl in the presence of acetylthiocholine chloride (ATChCl). Amperometry unveiled a steady-state turnover rate with the release of thiocholine. In the presence of arsenic(III) and cadmium(II), AChE showed an inhibitive response at 0.214 and 0.233 V vs Ag/AgCl, respectively. The electrode exhibits a detection limit and linear range of 0.03 μM and 0.05–0.8 μM for As(III) and 0.07 μM and 0.02–0.7 μM for Cd(II), respectively. Type of inhibition and inhibition constants induced by As(III) and Cd(II) on the catalytic sites of AChE were determined from Dixon and Lineweaver-Burk plots. The modified electrode was applied to the determination of As3+ and Cd2+ in river, tap and waste water, and the results proved that the method is sensitive and can be an alternative to chromatographic and spectroscopic techniques. 相似文献
89.
90.
Murugan Dinesh Raja Ranganathan Sivasubramaniyan Archana Murugan Sathishkumar Mohamed Sulthan Roshan Banu 《合成通讯》2016,46(17):1454-1460
A new application of Staudinger’s phosphazene as an efficient esterifying reagent is reported. Staudinger’s phosphazene formed in situ by the reaction of organic mono-azide with triphenylphosphine, which is trapped by carboxylic acid, to afford amide exclusively. In contrast, interestingly the same phosphazene behaves in a different way as an efficient esterifying reagent, affording ester under a solvent-free microwave-assisted protocol wherein alcohol is added as the another component in addition to the other reactants. This discovery adds yet another new application of Staudinger’s phosphazene to synthetic chemistry. 相似文献