1,720,999 research outputs found
Inferior pole peritonsillar abscess successfully treated by non-surgical approach in four cases.
No full textFunctionalized Ionic Liquid and Sol-Gel Composite Film for the Electrochemical Reduction and Determination of Nitrite without Interference from Dissolved Oxygen
No full text[[abstract]]This work provides an easy way to fabricate a composite film-modified electrode, and used as an electrochemical nitrite sensor. A functionalized ionic liquid, 1-butyl-3-methylimidazolium ferricyanide (BMIMFC), has been synthesized and modified onto a screen-printed carbon electrode (SPCE) by deposition methods. Poly(3-(aminopropyl) trimethoxysilane) sol-gel (SG) is then used as the second modified layer. The surface morphology of the modified electrode (SPCE/BMIMFC/SG) is characterized using scanning electron microscopy (SEM). The modified electrodes exhibit a very stable redox couple, and its redox potential is pH-dependent. In strongly acidic solutions, attractive electrocatalytic activity for the reduction of nitrite is achieved. As an amperometric nitrite sensor, the modified electrode shows a wide linear range (20-510 mu M), a suitable sensitivity (0.0040 mu A/mu M) and a low detection limit (1.3 mu M, S/N = 3). Unlike previous reports on the electrocatalytic reduction of nitrite, the present detection assays indicate insignificant interference from dissolved oxygen and common salts, promising the convenient operation of the nitrite sensor.[[note]]SC
Electrocatalysis and sensitive determination of cysteine at poly(3,4-ethylenedioxythiophene)-modified screen-printed electrodes
No full text[[abstract]]The electrocatalytic oxidation of cysteine at screen-printed electrode (SPE) modified with electrogenerated poly(3,4-ethylenedioxythiophene) film (PEDOT) was investigated. Cyclic voltammetric studies showed that the SPE/PEDOT electrode lowers the overpotentials and improves electrochemical behavior of cysteine oxidation, as compared to the bare SPE. The catalytic oxidation responses were studied and the reaction mechanisms were discussed. Excellent analytical features, including high sensitivity, low detection limit and satisfactory dynamic range, were achieved by flow-injection amperometry under optimized conditions. (c) 2008 Elsevier B.V. All rights reserved.[[note]]SC
Electrochemical Oxidation and Sensitive Determination of Acetaminophen in Pharmaceuticals at Poly(3,4-ethylenedioxythiophene)-Modified Screen-Printed Electrodes
No full text[[abstract]]The current study reports electrocatalytic oxidation of acetaminophen at screen-printed electrode (SPE) modified with electrogenerated poly(3,4-ethylenedioxythiophene) (PEDOT) film. Cyclic voltammetric studies show that the SPE/PEDOT electrode lowers overpotentials and improves electrochemical behavior of acetaminophen (ACAP) in aqueous buffer solutions, compared to the bare SPE. Excellent analytical features are achieved, including high sensitivity, low detection limit and satisfactory dynamic range, by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and flow-injection amperometry (FIA) under optimized conditions. The proposed methods obtain satisfactory results in detection of acetaminophen in two commercial tablets.[[note]]SC
Electrochemically pretreated screen-printed carbon electrodes for the simultaneous determination of aminophenol isomers
No full text[[abstract]]This study reports that disposable, electrochemically pretreated screen-printed carbon electrodes (SPCE*) can be employed for the simultaneous determination of aminophenol isomers in aqueous buffer solution. In sharp contrast to untreated SPCE, voltammetric studies indicate that the oxidation peak potential of each analyte in an aminophenol isomer mixture may be separated at the activated SPCE*. The individual oxidation peak currents are greatly increased by first-order derivative techniques. All experimental parameters were optimized to improve responses. The derivative oxidation peak currents is proportional to the concentration of isomer over the range from 0.2 to 100 mu M for 2-aminophenol (2AP), from 3.0 to 200 mu M for 3-aminophenol (3AP), and from 0.2 to 200 mu M for 4-aminophenol (4AP), with detection limits of 0.07, 0.16 and 0.05 mu M, respectively. The proposed methods have excellent analytical characteristics that include ease of handling, high sensitivity, wide linear dynamic range and low detection limits. The assay was applied to the simultaneous determination of aminophenol isomers in river water with good recovery results. (C) 2010 Elsevier B.V. All rights reserved.[[note]]SC
A simultaneous and Sensitive Determination of Hydroquinone and Catechol at Anodically Pretreated Screen-Printed Carbon Electrodes
No full text[[abstract]]Hydroquinone (HQ) and catechol (CA) are two positional isomers of dihydroxybenzene. They usually coexist in environmental samples and bring about pollution in our living environment. This research has developed a cheap, sensitive, and rapid method for the electrochemical determination of HQ and CA in aqueous pH 6.0 buffer solution without previous separation. By employing both anodically pretreated screen-printed carbon electrodes (SPCE*) and square wave voltammetric techniques, a direct and simultaneous determination of the two positional isomers was achieved. The oxidation peak potentials for HQ and CA were completely separated at the SPCE*, exhibiting well-defined and quasi-reversible redox peaks and showing greatly enhanced activity. Under optimized conditions, the linear calibration ranges for HQ and CA were in the ranges of 0.1-50 and 0.1-70 mu M, with detection limits (S/N = 3) of 0.05 and 0.05 mu M, respectively. This method was applied to the direct determination of HQ and CA in river water with satisfactory recovery results.[[note]]SC
Cloud distribution characteristics over the Tibetan Plateau
No full textWe use GMS5 satellite data and ISCCP cloud detection algorithm to study the characteristics of monthly mean cloud distribution and diurnal variation over the Tibetan Plateau. We simply classify total cloud into low, middle and high categories according to the height of cloud top. For the spatial distribution, during winter season both total and high cloud amounts of the north part of the Tibetan Plateau are larger than that of the south part of the Tibetan Plateau, but during summer season the distribution patterns are the reverse, that is, the cloud amounts of the south part of the Tibetan Plateau are larger than that of the north part of the Tibetan Plateau. For the diurnal variation, the total cloud amount begins to increase after sunrise and reaches maximum at 09GMT and 06GMT for midsummer season and other months respectively. After that total cloud amount decreases slowly. But the diurnal variation of high cloud amount is different from that of total cloud amount, high cloud amount begins to increase at noon time and reaches maximum at 09GMT and 12GMT for winter and summer season respectively. The diurnal variation of both total and high cloud amounts of the Tibetan Plateau is larger than that of the north part of the Indian Island.Meteorology & Atmospheric SciencesRemote SensingOpticsEICPCI-S(ISTP)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Electrochemical determination of cysteine based on conducting polymers/gold nanoparticles hybrid nanocomposites
No full text[[abstract]]In this study, a hybrid nanocomposite consisting of a conducting polymer and gold nanoparticles (AuNPs) is fabricated onto a screen-printed carbon electrode (SPCE). A thin layer of poly(3,4-ethylenedioxythiophene)(PEDOT) is coated electrochemically on a bare SPCE; then, the nano-sized AuNPs are embedded by electrochemical deposition. The resultant SPCE/PEDOT/AuNPs-modified electrode is characterized by electrochemical methods, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The SPCE/PEDOT/AuNPs-modified electrode possesses great catalytic activity for the oxidation of cysteine in various pH buffer solutions (pH 2.0-8.0). The selectivity of the method is demonstrated by the separation of the oxidation peaks at up to 240 mV for cysteine and glutathione in pH 6.0 buffer solutions. The effects of the oxidizable interferences are also investigated. Flow-injection amperometry is performed for 0.5-200 mu M of cysteine in pH 4.0 buffer solutions, and a linear calibration plot with a slope of 0.115 mu A/mu M is obtained. The detection limit (S/N = 3) is 0.05 mu M. Additionally, the proposed methods obtain satisfactory results in the detection of cysteine-containing medicine samples. (C) 2011 Elsevier Ltd. All rights reserved.[[note]]SC
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