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521.
Sudip?Biswas Susmita?Pradhan Hemanta?Naskar Rajib?Bandyopadhyay Panchanan?PramanikEmail author 《Mikrochimica acta》2018,185(11):513
Titanium dioxide nanoparticles (NPs) were synthesized by a sol-gel method from hexafluorotitanic acid using poly(ethylene glycol) as a capping agent. The crystal structure and morphology of the NPs were characterized by X-ray diffraction, FESEM, and TEM. The NPs were used to modify a graphite paste electrode for simultaneous determination of uric acid (UA) and guanine (GU). The effect of calcination temperature on crystal structure and electrocatalytic activity was investigated. The electrochemical responses to UA and GU at bare GP, TiO2–350/GP, and TiO2–600/GP electrodes were compared. The DPV oxidation peaks of UA and GU were found to be strongest at around 304 and 673 mV, respectively, against Ag/AgCl reference electrode, and this are well separated for effective simultaneous determination. UA and GU can be simultaneously determined by this method. Response is linear within the range 0.1–500 μM and 0.1–40 μM for UA and GU, respectively. The detection limits are 70 nM for UA and 50 nM for GU (at an S/N? ratio of?3). The TiO2–600/GP electrode showed excellent analytical performance when analyzing spiked urine and serum samples. 相似文献
522.
Racemic and scalemic PTC-protected alpha-hydroxystannanes cross-couple with alkenyl/aryl/heteroaryl iodides in moderate to good yields using copper(I) thiophene-2-carboxylate (CuTC) in THF at or below room temperature. Simple aryl iodides and 1-iodocyclohexene, two classes of electrophiles that typically react sluggishly, are also good substrates. Cross-couplings proceed with retention of configuration at the alkenyl- and stannyl-substituted stereocenters. 相似文献
523.
We calculate the Wigner quasiprobability distribution function of the quantum elliptical vortex in elliptical beam (EEV), produced by coupling squeezed coherent states of two modes. The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to the coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. 相似文献
524.
Finlay P Ettenauer S Ball GC Leslie JR Svensson CE Andreoiu C Austin RA Bandyopadhyay D Cross DS Demand G Djongolov M Garrett PE Green KL Grinyer GF Hackman G Leach KG Pearson CJ Phillips AA Sumithrarachchi CS Triambak S Williams SJ 《Physical review letters》2011,106(3):032501
A high-precision half-life measurement for the superallowed β+ emitter 26Al(m) was performed at the TRIUMF-ISAC radioactive ion beam facility yielding T 1/2 6346.54 ± 0.46(stat) ± 0.60 (syst) ms, consistent with, but 2.5 times more precise than, the previous world average. The 26Al(m) half-life and ft value, 3037.53(61) s, are now the most precisely determined for any superallowed β decay. Combined with recent theoretical corrections for isospin-symmetry-breaking and radiative effects, the corrected Ft value for (26)Al(m), 3073.0(12) s, sets a new benchmark for the high-precision superallowed Fermi β-decay studies used to test the conserved vector current hypothesis and determine the V(ud) element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. 相似文献
525.
Chemical investigation of the gum resin of Ferula assa-foetida L. resulted in the isolation of a new sesquiterpenoid coumarin, 7-(((E)-5-((1S,3S,6S)-3,6-dihydroxy-2,2,6-trimethylcyclohexyl)-3-methylpent-2-en-1-yl)oxy)-2H-chromen-2-one (asimafoetidnol), together with several other known compounds. The structure of asimafoetidnol was established on the basis of spectroscopic analyses. Geometry optimization of the compound has been carried out using a DFT/B3LYP/3-21G* method. 相似文献
526.
Cyclophostin, a structurally unique and potent naturally occurring acetyl cholinesterase (AChE) inhibitor, and its unnatural diastereomer were prepared in 6 steps and 15% overall yield from hydroxymethyl butyrolactone. The unnatural diastereomer of cyclophostin was converted into cyclipostin P, a potent naturally occurring hormone sensitive lipase (HSL) inhibitor, using a one pot dealkylation-alkylation process. The inhibition [IC(50)] of human AChE by cyclophostin and its diastereomer are reported, as well as constituent binding (K(I)) and reactivity (k(2)) constants. 相似文献
527.
Premamoy Ghosh Dilip Kumar Chowdhury Arup Rat Bandyopadhyay 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5-6):549-555
Preliminary studies on the suitability of some organic acids and amines, separately and in combination with each other, as photo-initiators for the polymerization of methyl methacrylate were made. Combinations of maleic acid or phthalic acid with any of the tertiary amines–triethyl amine, demethyl aniline, and diethylaniline-proved to be interesting photoinitiator systems in view of the fact that the initiator components in each combination were ineffective as initiators when used separately. The rate of photopolymerization in each of the above acid-amine combination system was much enhanced and the respective inhibition period largely reduced when benzophenone was used as the photoinitiator. Aliphatic diamine or polyamines such as ethylene diamine, diethylene triamine, and tri-ethylene tetramine, were ineffective as photoinitiators when used alone or in combination with maleic acid, but became effective 相似文献
528.
Deepak Bandyopadhyay Jun Huan Jan Prins Jack Snoeyink Wei Wang Alexander Tropsha 《Journal of computer-aided molecular design》2009,23(11):773-784
Protein function prediction is one of the central problems in computational biology. We present a novel automated protein structure-based function prediction method using libraries of local residue packing patterns that are common to most proteins in a known functional family. Critical to this approach is the representation of a protein structure as a graph where residue vertices (residue name used as a vertex label) are connected by geometrical proximity edges. The approach employs two steps. First, it uses a fast subgraph mining algorithm to find all occurrences of family-specific labeled subgraphs for all well characterized protein structural and functional families. Second, it queries a new structure for occurrences of a set of motifs characteristic of a known family, using a graph index to speed up Ullman’s subgraph isomorphism algorithm. The confidence of function inference from structure depends on the number of family-specific motifs found in the query structure compared with their distribution in a large non-redundant database of proteins. This method can assign a new structure to a specific functional family in cases where sequence alignments, sequence patterns, structural superposition and active site templates fail to provide accurate annotation. 相似文献
529.
An atomistic molecular dynamics simulation of the protein villin headpiece subdomain or HP-36 has been carried out with explicit water to explore the microscopic inhomogeneity of local density reorganization of the hydration layers of the three alpha-helical segments of the protein. The density reorganization of the hydration layer of helix-3 is found to occur faster than that for the hydration layers of the other two helices. It is noticed that such inhomogeneous density reorganization at the surface of different secondary structures exhibits excellent correlation with the microscopic dynamics of hydrogen bonds between the protein residues and the hydration water. Further, it is observed that the reorientation of water molecules involved in the formation and breaking of protein-water or water-water hydrogen bonds plays an important role in determining the dynamics of local density of the hydration layer. The faster density reorganization of the hydration layer of helix-3 is also consistent with the functionality of HP-36, as helix-3 contains several active site residues. 相似文献
530.
Deb K. Barma Anish Bandyopadhyay Bhavani Sangras Charles Mioskowski J.R. Falck 《Tetrahedron letters》2004,45(30):5917-5920
CrCl2-induced olefination of aldehydes using methyl dichloroacetate exclusively generates (E)-α,β-unsaturated esters in excellent yields. The intermediate α-chloro-β-hydroxy adducts could also be isolated in good yields under conditions of limited reagent. 相似文献