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81.
82.
Screen-printed silver electrodes (AgSPEs), without chemical modification, has been investigated as disposable sensors for the measurement of trace levels of Pb2+. Potential segment analysis indicates that the formation of underpotential and bulk depositions of Pb is not strongly coupled on the AgSPE. The possibility of determining Pb2+ at trace levels using the reversible underpotential deposition peak was examined by square-wave anodic stripping voltammetry without removal of oxygen. Under the optimized analytical conditions, the obtained sensitivity, linearity, and detection limit are 0.355 μA/ppb, 5-80 ppb (r=0.9992), and 0.46 ppb (S/N=3), respectively. The electrode is quite stable for repetitive measurements. The interference effect was thoroughly studied with various metals and no significant change in current was found in the determination of 5 ppb Pb2+. The practical applications were demonstrated to measure trace Pb2+ in natural waters. 相似文献
83.
B. Sivakumar K. SethuSankar U. P. Senthil Kumar R. Jeyaraman D. Velmurugan 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(3):o153-o155
The title compound, C24H19N3O, crystallizes in the centrosymmetric space group P21/a with one molecule in the asymmetric unit. The tetrahydropyridine ring has a boat conformation. The dihedral angle between the fused pyridine rings is 16.2 (1)°. The equatorial and axial orientations of the two phenyl groups with respect to the tetrahydropyridine ring are confirmed. The nitroso group is coplanar with the attached C—N—C group. The interplanar angle formed between the fused tetrahydropyridine and benzene planes is 13.4 (1)°. The crystal packing is stabilized by an intermolecular C—H⃛O hydrogen bond, which forms a C(9) graph‐set chain running along the [001] direction. 相似文献
84.
Annamalai Senthil Kumar K. Chandrasekara Pillai 《Journal of Solid State Electrochemistry》2000,4(7):408-416
Ruthenium dioxide electrodes, prepared on a Pt substrate using coatings of PVC-RuO2 mixed in THF (designated as RuO2-PVC film electrode) have been studied for their redox behaviour in 1 M NaOH using variable scan cyclic voltammetry. The various
redox transitions in the oxidation state of the central metal ion are characterized using electrochemical parameters such
as peak potential, peak current, and surface charge. The effect of oxide preparation temperature, in the range 300–700 °C,
on the redox characteristics has also been studied and correlated with the electrochemically active surface area (as measured
using small amplitude cyclic voltammetry) and the true surface area (by the BET method).
Received: 12 August 1997 / Accepted: 18 October 1999 相似文献
85.
R. Senthil Kumar S. Arunachalam V.S. Periasamy C.P. Preethy A. Riyasdeen M.A. Akbarsha 《Polyhedron》2008
The novel water-soluble polymer–cobalt(III) complex samples, cis-[Co(phen)2(BPEI)Cl]Cl2 · 4H2O (phen = 1,10-phenanthroline, BPEI = branched polyethyleneimine), with different amounts of cobalt complex content in the polymer chain, were prepared by ligand substitution method in water–ethanol medium and characterized by Infra-red, UV–Vis, 1H NMR spectral and elemental analysis methods. The interaction of these polymer–cobalt(III)-phenanthroline complex samples with calf thymus DNA has been explored using electronic absorption spectroscopy, emission spectroscopy and gel electrophoresis techniques. The presence of multiple small size molecular binding sites, namely, the cobalt(III)–phenanthroline complex moieties, and free amino groups in a single big sized polymer molecule enhanced both the electrostatic and/or van der Waals interaction and partial intercalative bindings with calf thymus DNA. The antitumor activity of a sample of polymer–cobalt(III) complex was determined using HEp-2 cell line and different cell death indicator stains and MTT assay. Many of the cultured HEp-2 cells treated with this complex suffered loss of viability and death mostly through apoptosis as evidenced by the nuclear and cytoplasmic morphology. 相似文献
86.
P. Senthil Kumar 《Tetrahedron》2005,61(23):5633-5639
The potential energy surface of sulfoximines has been searched using ab initio MO and Density Functional Calculations. The electronic structures of the isomers of sulfoximine have been studied using HF/6-31+G*, MP2(full)/6-31+G* and B3LYP/6-31+G* levels. Final energies of these molecules have been calculated at the high accuracy G2 and CBS-Q levels. Though a formal SN double bond is generally considered between sulfur and nitrogen in these systems, theoretical studies do not show any π interaction between them. S-N rotational barriers, bond dissociation energies, atomic charge analysis, and NBO analysis all indicate only a single bond across S-N with a very strong ionic interaction. 相似文献
87.
[reaction: see text] A series of peptidomimetics based on a gamma-turn motif were synthesized using a modular approach, in which N-protected piperidones were reacted with a selection of 2-hydroxyalkyl azides derived from common l-amino acids. Hydrolysis of the initially formed iminium ethers afforded the targeted series of substituted 1,4-diazepin-5-ones. 相似文献
88.
Flow injection analysis of zinc pyrithione in hair care products on a cobalt phthalocyanine modified screen-printed carbon electrode 总被引:1,自引:0,他引:1
Zinc pyrithione (ZPT) is an antibacterial and antifungal reagent that is often utilized for the antidandruff activity in hair-care shampoos with a composition level up to 1% in the formulation. It has some adverse effects to human and animal if consumed orally. A disposable type of cobalt phthalocyanide modified screen-printed carbon electrode (CoPc/SPE) in couple with flow injection analysis (FIA) was developed for easy and selective analysis of ZPT in commercial hair-care products. Under the optimized FIA conditions, the CoPc/SPE yielded a linear calibration plot in the window of 6–576 μM with sensitivity and detection limit of 1.65 nA μM−1 and 0.9 μM (i.e. 1.42 pg in 5 μl sample loop), respectively, in 0.1 M KOH solution at an applied potential of 0.3 V versus Ag/AgCl. Since the approach is simple, easy, selective, and inexpensive, it offers a potential application of daily ZPT analysis in hair-care products. 相似文献
89.
The precise theoretical characterization of a fractionalized phase in spatial dimensions higher than one is through the concept of "topological order." We describe a physical effect that is a robust and a direct consequence of this hidden order that should enable a precise experimental characterization of fractionalized phases. In particular, we propose specific "smoking-gun" experiments to unambiguously settle the issue of electron fractionalization in the underdoped cuprates. 相似文献
90.
S. Sundaram P. Subhasri T. Vasanthi T. S. Senthil R. Jayaprakasam 《Journal of Dispersion Science and Technology》2017,38(12):1811-1816
Hydrogen-bonded liquid crystal complex (HBLC) is synthesized from mesogenic 4-hexyloxy benzoic acid (6OBA) and aliphatic non-mesogenic citric acid (CA). The presence of intermolecular hydrogen bond in the HBLC complex is confirmed by FTIR spectrum. Phase transition temperature and enthalpy values are identified using different techniques. Induced highly ordered smectic G phase has been noticed in the present HBLC complex. Thermal span width and thermal stability factor of the individual mesogenic phase are discussed. The complexes are synthesized in different mole ratios, and their corresponding influence on the phase transitions is also discussed. 相似文献