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61.
A carbon paste electrode (CPE) was modified with multi-wall carbon nanotubes and successfully applied to the determination of silver ion by differential pulse anodic stripping voltammetry. Compared to a conventional CPE, a remarkably improved peak current response and sensitivity is observed. The analytical procedure consisted of an open circuit accumulation step for 2?min in ?0.4?V, this followed by an anodic potential scan between +0.2 and?+?0.6?V to obtain the voltammetric peak. The oxidation peak current is proportional to the concentration of silver ion in the range from 1.0?×?10?8 to 1.0?×?10?5?mol?L?1, with a detection limit of 1.8?×?10?9?mol?L?1 after an accumulation time of 120?s. The relative standard deviation for 7 successive determinations of Ag(I) at 0.1???M concentration is 1.99%. The procedure was validated by determining Ag(I) in natural waters. Figure
Differential pulse voltammogram (DPV) of Ag+ solution at MCPE 相似文献
62.
An organic–inorganic hybrid material based on paradodecatungstate building blocks and sodium–aminoacetic acid complex subunits,{Na10(H3N–CH2–COO)2[H2W12O42]}·28H2O (1), have been synthesized under mildly acidic conditions. This compound was characterized by single-crystal X-ray diffraction, elemental analysis, IR and UV–visible spectroscopies, and cyclic voltammetry. The compound crystallizes in the triclinic space group P-1 with a = 11.879(2) Å, b = 12.706(2) Å, c = 13.067(2) Å, α = 74.11(3)°, β = 79.71(3)°, γ = 65.95(3)°, V = 1727.2(5) Å3, and Z = 1. The crystal structure consists of infinite 2D layers constructed from [H2W12O42]10? clusters and sodium–aminoacetic acid complexes; adjacent layers are further joined by the complex units and sodium cations to yield a three-dimensional network. 相似文献
63.
Janjua NK Shaheen A Yaqub A Perveen F Sabahat S Mumtaz M Jacob C Ba LA Mohammed HA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1600-1604
Interactional studies of new flavonoid derivatives (Fl) with chicken blood ds.DNA were investigated spectrophotometrically in DMSO-H2O (9:1 v/v) at various temperatures. Spectral parameters suggest considerable binding between the flavonoid derivatives studied and ds.DNA. The binding constant values lie in the enhanced-binding range. Thermodynamic parameters obtained from UV studies also point to strong spontaneous binding of Fl with ds.DNA. Viscometric studies complimented the UV results where a small linear increase in relative viscosity of the DNA solution was observed with added optimal flavonoid concentration. An overall mixed mode of interaction (intercalative plus groove binding) is proposed between DNA and flavonoids. Conclusively, investigated flavonoid derivatives are found to be strong DNA binders and seem to be promising drug candidates like their natural analogues. 相似文献
64.
Simple, isocratic and rapid RP‐HPLC method has been developed for the simultaneous analysis of gemifloxacin and H2‐receptor antagonists i.e. Cimetidine, Famotidine and Ranitidine, in bulk, pharmaceutical formulation and human serum. Separation was achieved on the RP‐Mediterranea column [C18 (250 × 4.6 mm, 5 μ)] at ambient temperature using mobile phase consisting of acetonitrile: methanol: water (20:28:52 v/v/v pH 2.8 adjusted by phosphoric acid). Flow rate was 1.0 mL/min with an average operating pressure of 180 kg/cm2. Gatifloxacin (GATI) was used as an internal standard (IS). Quantitation was achieved with UV detection at 221, 256 and 267 nm, respectively. Linear calibration curves, at concentration ranges of 0.05‐37.5 μgmL‐L with a correlation coefficient of ±0.9994. The detection and quantification limits were in the ranges of 0.023‐0.250 μgmL‐L and 0.071‐0.756 μgmL‐L, respectively. Friedman's and Student's t‐test were applied to correlate these results. Method was validated in terms of selectivity, linearity, precision, robustness, recovery, limits of detection and quantitation and is applicable to the routine analysis of GFX and H2‐receptor antagonists, alone or in combination. 相似文献
65.
Sana Asif Kenta Asawa Yuuki Inoue Kazuhiko Ishihara Bjrn Lindell Robin Holmgren Bo Nilsson Anneli Rydn Marianne Jensen‐Waern Yuji Teramura Kristina N. Ekdahl 《Macromolecular bioscience》2019,19(5)
Artificial surfaces that come into contact with blood induce an immediate activation of the cascade systems of the blood, leading to a thrombotic and/or inflammatory response that can eventually cause damage to the biomaterial or the patient, or to both. Heparin coating has been used to improve hemocompatibility, and another approach is 2‐methacryloyloxyethyl phosphorylcholine (MPC)‐based polymer coatings. Here, the aim is to evaluate the hemocompatibility of MPC polymer coating by studying the interactions with coagulation and complement systems using human blood in vitro model and pig in vivo model. The stability of the coatings is investigated in vitro and MPC polymer‐coated catheters are tested in vivo by insertion into the external jugular vein of pigs to monitor the catheters' antithrombotic properties. There is no significant activation of platelets or of the coagulation and complement systems in the MPC polymer‐coated one, which was superior in hemocompatibility to non‐coated matrix surfaces. The protective effect of the MPC polymer coat does not decline after incubation in human plasma for up to 2 weeks. With MPC polymer‐coated catheters, it is possible to easily draw blood from pig for 4 days in contrast to the case for non‐coated catheters, in which substantial clotting is seen. 相似文献
66.
New chelate bis-heterocyclic-carbene complexes of Rh(I) and Rh(III) have been obtained and fully characterized. The molecular structures of the new species have been determined. The synthesis of the compounds starts from the bisimidazolium precursors, which are deprotonated with NEt(3) under mild reaction conditions, leading to coordination to the Rh complex. The Rh(III) compounds are generated from Rh(I) and [Rh(II)](2) species, although there is no apparent oxidizing agent in the reaction media. 相似文献
67.
Summary We have determined a series of bond energy terms in compounds containing dative, single, double and/or triple boron-nitrogen bonds. We describe various interesting applications based on these bond energy terms namely the determination of enthalpies of atomization and stabilization energies. More particularly, the conventional ring strain energies of three- and four-membered small ring containing boron and nitrogen atoms could be determined and the aromaticity of borazine, reexamined.Dedicated to Professor Alberte Pullman 相似文献
68.
Abdelhak Ayadi Sana Elgasri Abderrazek Mezghani Mickaël Castro Foued Elhaouani 《ournal of non Newtonian Fluid Mechanics》2011,166(12-13):661-666
The gross melt fracture defect is related to the flow instabilities developed in the contraction region. To mitigate these upstream instabilities, a convergent radial flow in the die entrance has been created. In fact, the ultimate objective of the present work is to examine the effect of the clearance width of radial flow on the appearance and development of gross melt fracture defect. So, capillary rheometer experiments were performed with linear polydimethylsiloxane (PDMS) oil.As for the influence of radial flow width on the morphology of gross melt fracture defect, extrudate photographs show that this imperfection can be mitigated since its frequency is higher and amplitude smaller when the gap of radial flow decreases. Such results may be related both to shear and elongational components of radial flow. Actually, when gap width is very small compared to the external diameter of radial flow, shear deformations become more enhanced with respect to the elongational deformations and thus the helical gross melt fracture becomes more like a surface defect than volume defect. 相似文献
69.
Sana Boughzala 《Comptes Rendus Mathematique》2004,338(10):747-750
We prove two new relations between and some multiple polylogarithms by evaluating twice the logarithmic Mahler measure of the polynomial 1+z1+z2+z3. To cite this article: S. Boughzala, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
70.
Sana Zama Abdelmalek Bouraiou Sofiane Bouacida Thierry Roisnel Ali Belfaitah 《Tetrahedron letters》2013
A new class of thiazolo[3,2-a]imidazole derivatives is obtained in good yields, by reacting 1-methyl-2-bromoimidazolium salts bearing N+-CH2COAr, N+-CH2COMe, N+-CH2COOMe, or N+-CH2CN fragments, with carbon disulfide in the presence of Et3N at room temperature. The mesoionic structures of these compounds are established by NMR spectroscopy and by single-crystal X-ray analysis. 相似文献