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Sample records for cathodic stripping voltammetric

  1. Voltammetric characteristics of miconazole and its cathodic stripping voltammetric determination

    Directory of Open Access Journals (Sweden)

    FRANCISCO C. PEREIRA

    2002-09-01

    Full Text Available Miconazole is reduced at mercury electrode above pH 6 involving organometallic compound formation, responsible for an anomalous polarographic behavior. The electrodic process presents a large contribution of the adsorption effects. The drug can be determined by cathodic stripping voltammetry from 8.0 x 10-8 to 1, 5 x 10-6 molL-1 in Britton-Robinson buffer pH 8.0, when pre-accumulated for 30s at an accumulation potential of 0V. A relative standard deviation of 3.8% was obtained for ten measurements of 1.0 x 10-7 molL-1 miconazole in B-R buffer pH 8.0 and a limit detection of 1, 7 x 10-8 molL-1 was determined using 60s of deposition time and scan rate of 100 mVs-1. The proposed method is simple, precise and it was applied successfully for the determination of the miconazole in pure form and in commercial formulations, showing mean recoveries of 99.7-98.4%.Miconazol é reduzido no eletrodo de mercúrio em valor de pH acima de 6,0 envolvendo formação de composto organometálico, responsável por um comportamento polarográfico anômalo. O processo eletródico apresenta uma larga contribuição de efeitos de adsorção. A droga pode ser determinada por voltametria de redissolução catódica de 8, 0 x 10-8 a 1, 5 x 10-6 mol L-1 em tampão Britton-Robinson pH 8,0 quando pré-acumulada por 30s em potencial de acúmulo de 0V. Um desvio padrão relativo de 3,8% foi obtido de 10 medidas de 1, 0 x 10-7 mol L-1 de miconazol em tampão B-R pH 8,0 e um limite de detecção de 1, 7 x 10-8 mol L-1 foi determinado usando 60s de tempo de deposição e velocidade de varredura de 100 mV s-1. O método proposto é simples, preciso e foi aplicado com sucesso para a determinação de miconazol na forma pura e em formulações comerciais, mostrando médias de recuperação de 99, 7 - 98, 4%.

  2. Adsorptive Cathodic Stripping Voltammetric Determination of Cefoperazone in Bulk Powder, Pharmaceutical Dosage Forms, and Human Urine

    Science.gov (United States)

    Hoang, Vu Dang; Huyen, Dao Thi; Phuc, Phan Hong

    2013-01-01

    The electroreduction behaviour and determination of cefoperazone using a hanging mercury drop electrode were investigated. Cyclic voltammograms of cefoperazone recorded in universal Britton-Robinson buffers pH 3–6 exhibited a single irreversible cathodic peak. The process was adsorption-controlled. Britton-Robinson buffer 0.04 M pH 4.0 was selected as a supporting electrolyte for quantitative purposes by differential pulse and square wave adsorptive cathodic stripping voltammetry. The experimental voltammetric conditions were optimized using Central Composite Face design. A reduction wave was seen in the range from −0.7 to −0.8 V. These voltammetric techniques were successfully validated as per ICH guidelines and applied for the determination of cefoperazone in its single and sulbactam containing powders for injection and statistically comparable to USP-HPLC. They were further extended to determine cefoperazone in spiked human urine with no matrix effect. PMID:24109542

  3. Adsorptive Cathodic Stripping Voltammetric Determination of Cefoperazone in Bulk Powder, Pharmaceutical Dosage Forms, and Human Urine

    Directory of Open Access Journals (Sweden)

    Vu Dang Hoang

    2013-01-01

    Full Text Available The electroreduction behaviour and determination of cefoperazone using a hanging mercury drop electrode were investigated. Cyclic voltammograms of cefoperazone recorded in universal Britton-Robinson buffers pH 3–6 exhibited a single irreversible cathodic peak. The process was adsorption-controlled. Britton-Robinson buffer 0.04 M pH 4.0 was selected as a supporting electrolyte for quantitative purposes by differential pulse and square wave adsorptive cathodic stripping voltammetry. The experimental voltammetric conditions were optimized using Central Composite Face design. A reduction wave was seen in the range from −0.7 to −0.8 V. These voltammetric techniques were successfully validated as per ICH guidelines and applied for the determination of cefoperazone in its single and sulbactam containing powders for injection and statistically comparable to USP-HPLC. They were further extended to determine cefoperazone in spiked human urine with no matrix effect.

  4. Cathodic stripping voltammetric determination of arsenic in sugarcane brandy at a modified carbon nanotube paste electrode.

    Science.gov (United States)

    Teixeira, Meryene C; Tavares, Elisângela de F L; Saczk, Adelir A; Okumura, Leonardo L; Cardoso, Maria das Graças; Magriotis, Zuy M; de Oliveira, Marcelo F

    2014-07-01

    We have developed an eletroanalytical method that employs Cu(2+) solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110μgL(-1) and from 10 to 110μgL(-1) for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5μgL(-1) for mineral oil and 3.4 and 11.2μgL(-1) for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS).

  5. Copper-mercury film electrode for cathodic stripping voltammetric determination of Se(IV).

    Science.gov (United States)

    Sladkov, Vladimir; David, François; Fourest, Blandine

    2003-01-01

    The copper-mercury film electrode has been suggested for the determination of Se(IV) in a wide range of concentration from 1x10(-9) to 1x10(-6) mol L(-1)by square-wave cathodic stripping voltammetry. Insufficient reproducibility and sensitivity of the mercury film electrode have been overcome by using copper(II) ions during the plating procedure. Copper(II) has been found to be reduced and form a reproducible copper-mercury film on a glassy carbon electrode surface. The plating potential and time, the concentration of copper(II) and the concentration of the supporting electrolyte have been optimised. Microscopy has been used for a study of the morphology of the copper-mercury film. It has been found that it is the same as for the mercury one. The preconcentration step consists in electrodeposition of copper selenide on the copper-mercury film. The relative standard deviation is 4.3% for 1x10(-6) mol L(-1) of Se(IV). The limit of detection is 8x10(-10) mol L(-1) for 5 min of accumulation.

  6. Adsorptive Cathodic Stripping Voltammetric Method with Alizarin for the Simultaneous Determination of Cadmium, and Zinc in Water Samples

    Directory of Open Access Journals (Sweden)

    Deswati

    2016-12-01

    Full Text Available This paper reports on the development of adsorptive cathodic stripping voltammetric (AdCSV method with 1,2-dihydroxyanthraquinone or Alizarin (AZ as a complexing agent used in the simultaneous determination of ultra trace of Cd and Zn because it has a good sensitivity, and selectivity. The influence of several parameters was studied: the effects of 1,2-dihydroxyanthraquinone or Alizarin (AZ concentration, pH, accumulation potential, and accumulation time. The relative standard deviation (RSD, and recovery is determined to get the accuracy and precision method. It also determined the limit of detection (LOD of the method to get the sensitivity. In this case, the optimum conditions were AZ concentration of 0.5 mM, pH 5, step deposition (70 s, -0.5 V. This method has been applied in water samples successfully, was obtained (Cd 23, and Zn 124 µg/L, LOD (Cd 0.006, and Zn 0.004 µg/L, RSD (Cd 0.4, and Zn 1.4 % (n = 10, recovery (Cd 99.36, and Zn 99.28%. The Atomic absorption spectrometric (AAS method is used as a comparison AdCSV optimum, was obtained (Cd 16, and Zn 115 µg/L.

  7. Cathodic stripping voltammetric determination of chromium in coastal waters on cubic Nano-titanium carbide loaded gold nanoparticles modified electrode

    Directory of Open Access Journals (Sweden)

    Haitao eHan

    2015-09-01

    Full Text Available The novel cubical nano-titanium carbide loaded gold nanoparticles modified electrode for selective and sensitive detection of trace chromium (Cr in coastal water was established based on a simple approach. Nano-titanium carbide is used as the typical cubical nanomaterial with wonderful catalytic activity towards the reduction of Cr(VI. Gold nanoparticles with excellent physical and chemical properties can facilitate electron transfer and enhance the catalytic activity of the modified electrode. Taking advantage of the synergistic effects of nano-titanium carbide and gold nanoparticles, the excellent cathodic signal responses for the stripping determination of Cr(VI can be obtained. The detection limit of this method is calculated as 2.08 μg L-1 with the linear calibration curve ranged from 5.2 to 1040 μg L-1. This analytical method can be used to detect Cr(VI effectively without using any complexing agent. The fabricated electrode was successfully applied for the detection of chromium in coastal waters collected from the estuary giving Cr concentrations between 12.48 and 22.88 μg L-1 with the recovery between 96% and 105%.

  8. Nanogold-penetrated poly(amidoamine) dendrimer for enzyme-free electrochemical immunoassay of cardiac biomarker using cathodic stripping voltammetric method.

    Science.gov (United States)

    Zhang, Bo; Zhang, Yi; Liang, Wenbin; Cui, Bin; Li, Jiabei; Yu, Xuejun; Huang, Lan

    2016-01-21

    Methods based on immunoassays have been developed for cardiac biomarkers, but most involve the low sensitivity and are unsuitable for early disease diagnosis. Herein we design an electrochemical immunoassay for sensitive detection of myoglobin (a cardiac biomarker for acute myocardial infarction) by using nanogold-penetrated poly(amidoamine) dendrimer (AuNP-PAMAM) for signal amplification without the need of natural enzymes. The assay was carried out on the monoclonal mouse anti-myoglobin (capture) antibody-anchored glassy carbon electrode using polyclonal rabbit anti-myoglobin (detection) antibody-labeled AuNP-PAMAM as the signal tag. In the presence of target myoglobin, the sandwiched immunocomplex could be formed between capture antibody and detection antibody. Accompanying AuNP-PAMAM, the carried gold nanoparticles could be directly determined via stripping voltammetric method under acidic conditions. Under optimal conditions, the detectable electrochemical signal increased with the increasing target myoglobin in the sample within a dynamic working range from 0.01 to 500 ng mL(-1) with a detection limit of 3.8 pg mL(-1). The electrochemical immunoassay also exhibited high specificity and good precision toward target myoglobin. Importantly, our strategy could be applied for quantitative monitoring of myoglobin in human serum specimens, giving well matched results with those obtained from commercialized enzyme-linked immunosorbent assay (ELISA) method.

  9. Sensitive Bioanalysis Based on in-Situ Droplet Anodic Stripping Voltammetric Detection of CdS Quantum Dots Label after Enhanced Cathodic Preconcentration.

    Science.gov (United States)

    Qin, Xiaoli; Wang, Linchun; Xie, Qingji

    2016-08-23

    We report a protocol of CdS-labeled sandwich-type amperometric bioanalysis with high sensitivity, on the basis of simultaneous chemical-dissolution/cathodic-enrichment of the CdS quantum dot biolabel and anodic stripping voltammetry (ASV) detection of Cd directly on the bioelectrode. We added a microliter droplet of 0.1 M aqueous HNO₃ to dissolve CdS on the bioelectrode and simultaneously achieved the potentiostatic cathodic preconcentration of Cd by starting the potentiostatic operation before HNO₃ addition, which can largely increase the ASV signal. Our protocol was used for immunoanalysis and aptamer-based bioanalysis of several proteins, giving limits of detection of 4.5 fg·mL(-1) for human immunoglobulin G, 3.0 fg·mL(-1) for human carcinoembryonic antigen (CEA), 4.9 fg·mL(-1) for human α-fetoprotein (AFP), and 0.9 fM for thrombin, which are better than many reported results. The simultaneous and sensitive analysis of CEA and AFP at two screen-printed carbon electrodes was also conducted by our protocol.

  10. Sensitive Bioanalysis Based on in-Situ Droplet Anodic Stripping Voltammetric Detection of CdS Quantum Dots Label after Enhanced Cathodic Preconcentration

    Directory of Open Access Journals (Sweden)

    Xiaoli Qin

    2016-08-01

    Full Text Available We report a protocol of CdS-labeled sandwich-type amperometric bioanalysis with high sensitivity, on the basis of simultaneous chemical-dissolution/cathodic-enrichment of the CdS quantum dot biolabel and anodic stripping voltammetry (ASV detection of Cd directly on the bioelectrode. We added a microliter droplet of 0.1 M aqueous HNO3 to dissolve CdS on the bioelectrode and simultaneously achieved the potentiostatic cathodic preconcentration of Cd by starting the potentiostatic operation before HNO3 addition, which can largely increase the ASV signal. Our protocol was used for immunoanalysis and aptamer-based bioanalysis of several proteins, giving limits of detection of 4.5 fg·mL−1 for human immunoglobulin G, 3.0 fg·mL−1 for human carcinoembryonic antigen (CEA, 4.9 fg·mL−1 for human α-fetoprotein (AFP, and 0.9 fM for thrombin, which are better than many reported results. The simultaneous and sensitive analysis of CEA and AFP at two screen-printed carbon electrodes was also conducted by our protocol.

  11. Cathodic stripping voltammetry of trace Mn(II) at carbon film electrodes

    OpenAIRE

    Filipe, Olga M. S.; Brett,Christopher M.A.

    2003-01-01

    A sensitive voltammetric method is presented for the determination of tract levels of Mn (II) using carbon film electrodes fabricated from carbon resistors of 2 [Omega]. Determination of manganese was made by square wave cathodic stripping voltammetry (CSV), with deposition of manganese as manganese dioxide. Chronoamperometric experiments were made to study MnO2 nucleation and growth. As a result, it was found to be necessary to perform electrode conditioning at a more positive potential to i...

  12. ME1/1 Cathode Strip Chambers

    CERN Document Server

    Erchov, Yu V; Kamenev, Alexey; Karjavin, Vladimir; Khabarov, Serguei; Moissenz, P V; Moissenz, K P; Movchan, Sergey; Perelygin, Victor; Vassiliev, S E; Zarubin, Anatoli; Tchekhovski, V A

    2008-01-01

    The 76 innermost ME1/1 cathode strip chambers (CSC) of the CMS Experiment were designed and produced in Dubna. The chambers have been installed in the detector and commissioning has been completed. This paper describes the design of the CSCs, their main mechanical parameters and read-out electronics, and the results of tests with cosmic-ray muons.

  13. Adsorptive stripping voltammetric determination of chromium in gallium.

    Science.gov (United States)

    Palrecha, M M; Mathur, P K

    1997-12-19

    The electroanalytical chemistry of trace metals has progressed strongly with the development of cathodic stripping voltammetry (CSV) preceded by adsorption collection of organic metal complexes. A sensitive method for the determination of trace amount of chromium in gallium is described. Gallium is dissolved in sodium hydroxide containing hydrogen peroxide. The method is based on the catalytic activity of nitrate ions on the reduction of Cr(III)TTHA (triethylene tetramine-N,N,N',N'',N''',N'''-hexaacetic acid) complex. The sensitivity of this method is further improved by adsorption preconcentration of Cr(III)TTHA complex at a hanging mercury drop electrode (HMDE). The Cr(III) formed at the electrode surface by the reduction of Cr(VI), which is present in the bulk solution, is immediately complexed by TTHA. The adsorbed complex is then reduced at a peak potential of - 1.26 V, and the peak height of Cr(III) reduction is measured. The determination limit was restricted by the amount of chromium present in the reagent blank solution. The method is suitable for the determination of chromium at level as low as 0.2 mug g(-1) (with about 50 mg of sample) and a relative standard deviation of 15%.

  14. Adsorptive stripping voltammetric determination of the antidepressant drug sulpiride.

    Science.gov (United States)

    Farghaly, O A

    2000-10-01

    The electrochemical behaviour of the antidepressant drug sulpiride (SP) at a hanging mercury drop electrode (HMDE) is investigated. Linear sweep cathodic stripping voltammetry (LSCSV) was used to determine sulpiride in the presence of 0.01 M sodium acetate medium pH 10.5 and 25 +/- 1 degrees C. Different parameters such as, supporting electrolyte, pH, accumulation potential, scan rate, accumulation time and ionic strength, were tested to optimize the conditions for the determination of SP. The adsorbed form is reduced irreversibly. The linear concentration range is from 2 x 10(-9) to 5 x 10(-8) M SP. Experimentally, 2 x 10(-9) M (0.68 ppb) with accumulation time 60 s can be determined successfully. Furthermore, a theoretical detection limit of 2 x 10(-10) M (0.068 ppb) Sp was calculated. The interferences of some metal ions, ascorbic acid and some amino acids were studied. The method was applied to the analysis of tablets and spiked urine, with recoveries of 104 +/- 3 and 101 + 3, and the relative standard deviation of 3.3 and 3.4%, respectively.

  15. Adsorptive stripping voltammetric determination of netilmicin in the presence of formaldehyde.

    Science.gov (United States)

    Sun, Nan; Mo, Weimin; Hu, Baoxiang; Shen, Zhenlu

    2006-05-01

    A linear sweep adsorptive stripping voltammetric method for the determination of netilmicin in the presence of formaldehyde has been proposed for the first time. In the presence of 3.0 x 10(-3) g ml(-1) formaldehyde, netilmicin exhibits a sensitive cathodic peak at -1.30 V (vs. the saturated calomel electrode, SCE) in a medium of Britton-Robinson buffer (pH 8.7) with a scan rate of 100 mV s(-1) after a preconcentration period of 120 s at -1.10 V (vs. SCE). The peak current showed a linear dependence on the netilmicin concentration over the range 4.2 x 10(-9)-1.0 x 10(-7) g ml(-1). The achieved limits of detection and quantitation were 1.0 x 10(-10) and 3.3 x 10(-10) g ml(-1) netilmicin, respectively. It was deduced from the experiments that the amine-aldehyde condensation product formed between netilmicin and formaldehyde is mainly responsible for the appearance of the peak. The electrochemical behavior of netilmicin in the presence of formaldehyde has been studied. The method was applied to the direct determination of netilmicin in injectable formulations and spiked human urine and serum samples.

  16. Adsorptive stripping voltammetric determination of trace amounts of lead in environmental water samples with complicated matrix

    Directory of Open Access Journals (Sweden)

    Grabarczyk M.

    2013-04-01

    Full Text Available A sensitive, simple and fast adsorptive stripping voltammetric procedure for trace determination of lead in environmental water samples has been developed. The method is based on adsorptive accumulation of the Pb(II-cupferron complex onto a hanging mercury drop electrode, followed by the reduction of the adsorbed species by a voltammetric scan using differential pulse modulation. The interference from surface active substances was eliminated by adsorption of interferents onto an Amberlite XAD-16 resin. Optimumconditions for removing the surfactants by mixing the analysed sample with resin were evaluated. The accuracy of the method was tested by analyzing certified reference material (SPS-WW1 Waste Water.

  17. Synchronization of the CMS Cathode Strip Chambers

    CERN Document Server

    Raknessa, G; Wang, D

    2007-01-01

    The synchronization of the trigger and data acquisition systems for the Cathode Strip Chambers (CSCs) in the Compact Muon Solenoid (CMS) detector at CERN is described. The CSC trigger system is designed to trigger CMS on muons with high efficiency (~99% per chamber) and is able to accurately identify its 25ns proton bunch crossing. To date, asynchronous cosmic ray data have been used to define the protocol and to refine timing algorithms, allowing synchronization to be realized within and between chambers to within ±10 ns. Final synchronization of the CSCs requires timing parameters to be accurate to 2 ns. This goal will be readily achieved from the cosmic ray baseline using data taken with the synchronous beam structure of the Large Hadron Collider.

  18. Anodic stripping voltammetric determination of Zn, Pb and Cu traces in whisky samples

    Energy Technology Data Exchange (ETDEWEB)

    Barbeira, P.J.S. [Departamento de Quimica - ICEx - UFMG, Belo Horizonte, MG (Brazil); Stradiotto, N.R. [Departamento de Quimica - FFCLRP - USP, Ribeirao Preto, SP (Brazil)

    1998-07-01

    The simultaneous ``in natura`` determination of trace Zn, Pb and Cu in whisky samples by anodic stripping voltammetry (ASV), using a hanging mercury drop electrode, without previous treatment or addition of supporting electrolyte is described. The choice of an appropriate stripping voltammetric method and deposition potential minimizes the influence of the organic content and ensures a good reproducibility of the measurements. The reliability of the method was tested comparing the results with those of atomic absorption spectroscopy (AAS), with differences of about 10%. The method allows the determination of heavy metal ions in the {mu}g L{sup -1} range. (orig.) With 3 figs., 1 tab., 18 refs.

  19. Installation of some Cathode Strip Chambers on March 2004

    CERN Multimedia

    Richard Breedon

    2004-01-01

    Installation on the Disk of some Cathode Strip Chambers, type ME3/1, produced in the US. The installation has been performed on March 2004 at the CMS experimental site SX5 (P5) in Cessy, neighbouring France.

  20. Electrochemical reduction and cathodic stripping voltammetric determination of clotrimazole

    OpenAIRE

    Pereira, Francisco C.; Stradiotto,Nelson R.; Zanoni,Maria Valnice B.

    2001-01-01

    Clotrimazol é reduzido em eletrodo de mercúrio em tampão fosfato pH > 6 através de um processo reversível de um elétron. O processo eletródico apresenta forte efeito de adsorção, o qual pode ser minimizado na presença de Triton X-100. Clotrimazol pode ser determinado em níveis de 50 ng mL-1 quando pré-acumulado durante 3 min à -0,20 V. O método proposto foi aplicado para determinação do fármaco em formulação comercial. The reduction of clotrimazole at a mercury electrode, in phosphate buff...

  1. Stripping voltammetric determination of mercury(II) at antimony-coated carbon paste electrode.

    Science.gov (United States)

    Ashrafi, Amir M; Vytřas, Karel

    2011-10-15

    A new procedure was elaborated to determine mercury(II) using an anodic stripping square-wave voltammetry at the antimony film carbon paste electrode (SbF-CPE). In highly acidic medium of 1M hydrochloric acid, voltammetric measurements can be realized in a wide potential window. Presence of cadmium(II) allows to separate peaks of Hg(II) and Sb(III) and apparently catalyses reoxidation of electrolytically accumulated mercury, thus allowing its determination at ppb levels. Calibration dependence was linear up to 100 ppb Hg with a detection limit of 1.3 ppb. Applicability of the method was tested on the real river water sample.

  2. Cathodic stripping voltammetry of trace Mn(II) at carbon film electrodes.

    Science.gov (United States)

    Filipe, Olga M S; Brett, Christopher M A

    2003-12-04

    A sensitive voltammetric method is presented for the determination of tract levels of Mn (II) using carbon film electrodes fabricated from carbon resistors of 2 Omega. Determination of manganese was made by square wave cathodic stripping voltammetry (CSV), with deposition of manganese as manganese dioxide. Chronoamperometric experiments were made to study MnO(2) nucleation and growth. As a result, it was found to be necessary to perform electrode conditioning at a more positive potential to initiate MnO(2) nucleation. Under optimised conditions the detection limit obtained was 4 nM and the relative standard deviation for eight measurements of 0.22 nM was 5.3%. Interferences from various metal ions on the response CSV of Mn(II) were investigated, namely Cd(II), Ni(II), Cu(II), Cr(VI), Pb(II), Zn(II) and Fe(II). Application to environmental samples was demonstrated.

  3. Cathode Strip Chambers (CSC) Sag Measurements and Predictions

    CERN Document Server

    Kriesel, K; Loveless, D

    1997-01-01

    We describe the measurements of sag on P1A 2 layer prototype Cathode Strip Chamber and compare the results with calculated values. Using this information we predict the sag of P1 6-layer chamber with the present design for the aluminium frame, and compare this value to measured sag.

  4. Readout Electronics of the ATLAS Muon Cathode Strip Chambers

    CERN Document Server

    Gough Eschrich, I

    2008-01-01

    The ATLAS muon spectrometer employs cathode strip chambers (CSC) to measure high momentum muons in the forward regions (2.0 < | | < 2.7). Due to the severe radiation levels expected in this environment, the on-detector electronics are limited to amplifying and digitizing the signal while sparsification, event building and other tasks are performed off-detector.

  5. Readout Electronics of the ATLAS Muon Cathode Strip Chambers

    CERN Document Server

    Gough Eschrich, I

    2008-01-01

    The ATLAS muon spectrometer employs cathode strip chambers (CSC) to measure high momentum muons in the forward regions $(2.0 < |eta| < 2.7)$. Due to the severe radiation levels expected in this environment, the on-detector electronics are limited to amplifying and digitizing the signal while sparsification, event building and other tasks are performed off-detector.

  6. Engineering analyses of large precision cathode strip chambers for GEM

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, J.A.; Belser, F.C.; Pratuch, S.M.; Wuest, C.R. [Lawrence Livermore National Lab., CA (United States); Mitselmakher, G. [Superconducting Super Collider Lab., Dallas, TX (United States); Gordeev, A. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Johnson, C.V. [Lawrence Livermore National Lab., CA (United States)]|[Superconducting Super Collider Lab., Dallas, TX (United States); Polychronakos, V.A. [Brookhaven National Lab., Upton, NY (United States); Golutvin, I.A. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    1993-10-21

    Structural analyses of large precision cathode strip chambers performed up to the date of this publication are documented. Mechanical property data for typical chamber materials are included. This information, originally intended to be an appendix to the {open_quotes}CSC Structural Design Bible,{close_quotes} is presented as a guide for future designers of large chambers.

  7. Cathodic Voltammetric Behavior of Pillar[5]quinone in Nonaqueous Media. Symmetry Effects on the Electron Uptake Sequence.

    Science.gov (United States)

    Cheng, Beijun; Kaifer, Angel E

    2015-08-12

    The cathodic voltammetric behavior of pillar[5]quinone was investigated in dichloromethane solution. Our data show that the symmetry of the macrocycle has a pronounced effect on the electron uptake sequence. The uptake of the first five electrons follows a 2-1-2 pattern, and only a total of eight electrons could be injected into the macrocycle under our experimental conditions.

  8. Web-Based Cathode Strip Chamber Data Display

    CERN Multimedia

    Firmansyah, M

    2013-01-01

    Cathode Strip Chamber (CSC) is a detector that uses gas and high electric field to detect particles. When a particle goes through CSC, it will ionize gas particles and generate electric signal in the anode and cathode of the detector. Analysis of the electric signal data can help physicists to reconstruct path of the particles and determine what happen inside the detector. Using data display, analysis of CSC data becomes easier. One can determine which data is interesting, unusual, or maybe only contain noise.\

  9. Adsorptive Stripping Voltammetric Determination of Hydroquinone using an Electrochemically Pretreated Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Abdul Niaz1,

    2008-12-01

    Full Text Available A simple and efficient adsorptive stripping voltammetric (AdSV method was developed for the determination of hydroquinone at an electrochemically pretreated glassy carbon (GC electrode in waste water. Various parameters such as solvent system, accumulation potential, accumulation time and scan rate were optimized. The electrochemically pretreated GC electrode showed good response towards hydroquinone determination by using AdSV. Under the optimized conditions the peak current showed good linear relationship with the hydroquinone concentration in the range of 0.5-4.0mg L-1 and 5-30mg L-1. The 60/40 methanol/water composition was found to be the best solvent system and 0.05mol L-1 H2SO4 was found as useful supporting electrolyte concentration. The accumulation time was 60 s and the detection limit was 50µg L-1. The developed method was successfully applied for the determination of hydroquinone in polymeric industrial discharge samples waste photographic developer solution and cream sample without any significant effect of surface fouling.

  10. Dual-nanomaterial based electrode for voltammetric stripping of trace Fe(II) in coastal waters.

    Science.gov (United States)

    Lin, Mingyue; Pan, Dawei; Zhu, Yun; Hu, Xueping; Han, Haitao; Wang, ChenChen

    2016-07-01

    In this work, a dual-nanomaterial based electrode was established for selective and sensitive detection of trace Fe(II) in the presence of complexing agent (2,2'-bipyridyl). Titanium carbide nanoparticles (TiCNPs) were used as the growth-template for the formation of three-dimensional platinum nanoflowers (PtNFs) due to their unique cubic structures. Nafion was employed as the conducting matrix to help TiCNPs better attached onto the surface of the electrode and slow down the crystal rate of PtNFs during electrodeposition, which resulted in flower structure and more active surface of PtNFs. Taking advantage of synergistic effects of TiCNPs and Nafion as well as the catalytic amplifying effect of PtNFs, the excellent anodic signal responses for the voltammetric stripping determination of Fe(II) were obtained. The linear range of Fe(II) on this dual-nanomaterial based electrode was from 1nmolL(-1) to 6μmolL(-1) with the lowest detectable concentration of 0.1nmolL(-1) and a detection limit of 0.03nmolL(-1). Additionally, the effect of several experimental parameters, such as concentration and pH value of buffer solution, concentration of modifier and ligand, deposition potential and time of electrochemical determination, and scan rate were studied for analytical applications. The fabricated sensor had been successfully applied for the sensitive determination of trace Fe(II) in coastal waters.

  11. A validated stripping voltammetric procedure for quantification of the anti-hypertensive and benign prostatic hyperplasia drug terazosin in tablets and human serum.

    Science.gov (United States)

    Ghoneim, M M; El Ries, M A; Hammam, E; Beltagi, A M

    2004-10-20

    The electrochemical behavior of terazosin at the hanging mercury drop electrode was studied in Britton-Robinson buffer (pH 2-11), acetate buffer (4.5-5.5), and in 0.1M solution of each of sodium sulfate, sodium nitrate, sodium perchlorate and potassium chloride as supporting electrolytes. The square-wave adsorptive cathodic stripping voltammogram of terazosin exhibited a single well-defined two-electron irreversible cathodic peak which may be attributed to the reduction of CO double bond of the drug molecule. A fully validated, simple, high sensitive, precise and inexpensive square-wave adsorptive cathodic stripping voltammetric procedure was described for determination of terazosin in bulk form, tablets and human serum. A mean recovery for 1x10(-8)M terazosin in bulk form, following preconcentration onto the hanging mercury drop electrode for 60s at a -1.0V (versus Ag/AgCl/KCl(s)), of 99+/-0.7% (n=5) was obtained. Limits of detection (LOD) and quantitation (LOQ) of 1.5x10(-11) and 5x10(-11)M bulk terazosin were achieved, respectively. The proposed procedure was successfully applied to determination of the drug in its Itrin((R)) tablets and human serum samples. The achieved LOD and LOQ of the drug in human serum samples were 5.3x10(-11) and 1.8x10(-10)M THD, respectively. The pharmacokinetic parameters of the drug in human plasma were estimated as: C(max)=77.5ngml(-1), t(max)=1.75h, AUC(0-t)=602.3nghml(-1), K(e)=0.088h(-1) and t(1/2)=11.32h) which are favorably compared with those reported in literature.

  12. The Cathode Strip Chamber Data Acquisition System for CMS

    CERN Document Server

    Bylsma, B G; Gilmore, J R; Gu, J H; Ling, T Y

    2007-01-01

    The Cathode Strip Chamber (CSC) [1] Data Acquisition (DAQ) system for the CMS [2] experiment at the LHC [3] will be described. The CSC system is large, consisting of 218K cathode channels and 183K anode channels. This leads to a substantial data rate of ~1.5GByte/s at LHC design luminosity (1034cm-2s-1) and the CMS first level trigger (L1A) rate of 100KHz. The DAQ system consists of three parts. The first part is on-chamber Cathode Front End Boards (CFEB)[4], which amplify, shape, store, and digitise chamber cathode signals, and Anode Front End Boards (AFEB)[5], which amplify, shape and discriminate chamber anode signals. The second part is the Peripheral Crate Data Acquisition Motherboards (DAQMB), which control the onchamber electronics and the readout of the chamber. The third part is the off-detector DAQ interface boards, which perform real time error checking, electronics reset requests and data concentration. It passes the resulting data to a CSC local DAQ farm, as well as CMS main DAQ [6]. All electron...

  13. Performance Testing of the CMS Cathode Strip Chambers

    CERN Document Server

    Breedon, Richard; Andreev, M. Tripathi V; Arisaka, Katsushi; Cline, David; Hauser, Jay; Ignatenko, Mikhail; Lisowsky, B; Matthey, Christina; Rakness, Gregory; Wenman, Daniel

    2009-01-01

    The production, installation, and testing of 468 cathode strip chambers for the endcap muon system of the CMS experiment played a critical role in the preparation of the endcap muon system for the final commissioning. Common testing procedures and sets of standard equipment were used at 5 international assembly centers. The chambers were then thoroughly retested after shipment to CERN. Final testing was performed after chamber installation on the steel disks in the CMS detector assembly building. The structure of the detector quality control procedure is presented along with the results of chamber performance validation tests.

  14. Central tracking chamber with inflated cathode-strip foils

    Energy Technology Data Exchange (ETDEWEB)

    Blackmore, E.W.; Bryman, D.A.; Kuno, Y.; Lim, C.; Numao, T.; Padley, P.; Redlinger, G.; Soluk, R. [TRIUMF, Vancouver, BC (Canada); McPherson, R.A. [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States)

    1998-02-21

    A new cylindrical low-mass central drift chamber has been constructed for the K{sup +}{yields}{pi}{sup +}{nu} anti {nu} experiment at BNL (E787). The chamber consists of twelve layers of axial wire cells and six layers of thin cathode-strip foils, four of which are supported by differential gas pressure. The momentum resolution (RMS) for muons and pions in the range 150-250 MeV/c is found to be about 0.9%. (orig.). 16 refs.

  15. Performance of the CMS Cathode Strip Chambers with Cosmic Rays

    CERN Document Server

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Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns.

  16. Detecting Naturally-Produced Sulfide Nanoparticles by Adsorptive, Cathodic Stripping Voltammetry.

    Science.gov (United States)

    Helz, G. R.; Krznaric, D.; Bura-Nakic, E.; Ciglenecki, I.

    2007-12-01

    Growing evidence implies that metal sulfide nanoparticles of natural origin exist in some aquatic environments. These nanoparticles could play important roles as mediators of trace metal nutrition and toxicity. Thermodynamics suggests that in sulfidic environments (total transition metaltotal sulfide) the most insoluble metal sulfide (usually Hg or Cu) will form the predominant sulfide nanoparticle. New experimental methods for detecting and distinguishing between such nanoparticles are needed. We report that mercury electrodes effectively preconcentrate a number of different metal sulfide nanoparticles, enabling their detection by adsorptive cathodic stripping voltammetry. Voltammetrically, nanoparticulate analytes differ fundamentally from dissolved analytes; e.g. analyte accumulation is very sensitive to electrolyte composition and concentration in accord with the Schulze-Hardy Rule. EDTA or acid treatment of samples is useful for distinguishing highly insoluble nanoparticles (HgS, CuS) from FeS. Nanoparticulate sulfur potentially interferes. Supersaturated solutions can generate artifactual analyte on Hg electrode surfaces. Despite such potential pitfalls, progress is encouraging. Preliminary, qualitative results from natural waters will be reported.

  17. Web-Based Cathode Strip Chamber Data Display

    CERN Document Server

    Firmansyah, Muhammad; CERN. Geneva. PH Department

    2013-01-01

    Cathode Strip Chambers (CSC) are gas detectors in Compact Muon Solenoid (CMS) experiment that can determine paths of muons accurately. The data taken from the chambers are digital data and usually saved to files. Sometimes we need graphical representation of the data to analyze some files. A software had been developed to comply the needs, but it had limitations, didn't meet some specifications, and few major drawbacks. Hence, a new version of the software is developed to overcome its limitations, drawbacks, and also to meet the all specifications. Besides that, there are also additional features added to the new version software to help users analyze data. The new version software is a web-based application, which is different from the desktop-based application of the old version software. In the end, response in CSC Online Systems weekly meeting (12/08/13) for this application was positive, so this application should be maintained and developed in future.

  18. Solar UV-treatment of water samples for stripping-voltammetric determination of trace heavy metals in Awash river, Ethiopia

    Directory of Open Access Journals (Sweden)

    Gelaneh Woldemichael

    2016-03-01

    Full Text Available We report about testing a new mobile and sustainable water sample digestion method in a preliminary field trial in Ethiopia. In order to determine heavy metals at the ultra-trace level by stripping voltammetric techniques in water samples from Awash River, we applied our new method of solar UV-assisted sample pretreatment to destroy the relevant interfering dissolved organic matter. The field tests revealed that 24 h of solar UV irradiation were sufficient to achieve the same sample pretreatment results as with classic digestion method based on intense and hard UV. Analytical results of this study suggest that both a hydroelectric power station and agrichemical applications at Koka Lake have increased the levels of the investigated metals zinc, cadmium, lead, copper, cobalt, nickel, and uranium.

  19. Stripping voltammetric determination of Cd(Ⅱ) based on multiwalled carbon nanotube functionalized with 1-(2-pyridylazo)-2-naphthol

    Institute of Scientific and Technical Information of China (English)

    Alireza Mohadesi; Hadi Beitollahi; Mohammad Ali Karimi

    2011-01-01

    The present work has focused on the modification of multiwalled carbon nanotube with a ligand, l-(2-pyridylazo)-2-naphthol, and its potential application for the development of a new, simple and selective modified glassy carbon electrode for stripping voltammetric determination of Cd(Ⅱ). The analytical curve for Cd(Ⅱ) ions covered the linear range varying from 0.8 up to 220.4 μg L-1. The limit of detection was found to be 0.1 μg L-1, while the relative standard deviation (RSD) at 50.0 μg L-1 was 1.8% (n = 5). This modified electrode was successfully applied for determination of Cd(Ⅱ) in some water samples.

  20. Determination of selenium in nuts by cathodic stripping potentiometry (CSP).

    Science.gov (United States)

    Dugo, Giacomo; La Pera, Lara; Lo Turco, Vincenzo; Mavrogeni, Ekaterini; Alfa, Maria

    2003-06-18

    The aim of this work was to determine the selenium content in nut samples by cathodic stripping potentiometry. Dry-powdered nuts were digested by HNO(3) and dissolved with concentrated hydrochloric acid. To avoid the interference of natural oxygen, the potentiometric determination of selenium was carried out in an electrolyte solution consisting of 2 M CaCl(2) and 4 M HCl. The analysis was executed applying an electrolysis potential of -150 mV for 60 s and a constant current of -30 microA. Under these conditions, detection limits lower than 1.0 ng g(-)(1) were obtained for selenium analysis in nuts. The relative standard deviation of these measurements (expressed as rsd %) ranged from 0.44 to 0.88% while recoveries ranged from 90.2 to 95.3%. The results obtained with the proposed method were compared with those obtained via hydride vapor generation atomic absorption spectroscopy, a common method for determining selenium. The results of the two methods agreed within 5% for almond, hazelnut, and pistachio samples. The mean concentrations of selenium determined in Sicilian samples of almond, hazelnut, and pistachio were 531 +/- 1, 865 +/- 1, and 893 +/- 4 microg/kg, respectively.

  1. Construction and evaluation of a carbon paste electrode modified with polyaniline-co-poly(dithiodianiline) for enhanced stripping voltammetric determination of metal ions

    OpenAIRE

    Somerset, Vernon; Silwana, Bongiwe; Horst, Charlton van der; Iwuoha, Emmanuel

    2014-01-01

    A modified carbon paste electrodes (MCPE) have been prepared in this study as an alternative “mercury-free” electrochemical sensor for the determination of Pb2+ and Cd2+ metal ions in aqueous solutions. CPE containing a conducting copolymer of polyaniline-co-poly(2,2'- dithiodianiline) (PANI-co-PDTDA) was used as a modified substrate transducer to achieve enhanced selectivity in stripping voltammetric analysis. The experimental conditions optimised included the supporting electrolyte pH, d...

  2. Detector with a profile-based cathode and a two-coordinate pad-strip readout system

    CERN Document Server

    Kuchinskiy, N A; Kravchuk, N P; Korenchenko, A S; Khomutov, N V; Smirnov, V S; Chekhovskii, V A; Movchan, S A; Zyazyulya, F E

    2011-01-01

    A detector with a profile-based cathode and a pad-strip cathode readout system is experimentally investigated. Cathode pads arranged along each anode wire are diagonally interconnected and form strips that cross the detector at an angle with respect to the anode wire. Two coordinates from the cathodes and one from the anode wire allow identification of tracks in high multiplicity events with a single detector plane.

  3. Stripping Voltammetric Determination of Analgesics in Their Pharmaceuticals Using Nano-Riboflavin-Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Gopalakrishnan Gopu

    2011-01-01

    Full Text Available Cyclic voltammetric behaviors of three analgesics, acetaminophen (AAP, acetylsalicylic acid (ASA, and dipyrone (DP, were studied using nano-riboflavin-modified glassy carbon electrode. One well-defined oxidation peak each for AAP and ASA and three oxidation peaks for DP were observed. The influence of pH, scan rate, and concentration reveals irreversible diffusion controlled reaction. The SEM analysis confirmed good accumulation of the drugs on the electrode surface. Calibration was made under the maximum peak current conditions. The concentration range studied for the determination of drugs was 0.02 to 0.4 μg mL−1 for AAP and ASA and 0.025 to 0.4 μg mL−1 for DP. The lower limit of detection observed for AAP, ASA, and DP was 0.016, 0.007 μg mL−1, and 0.013 μg mL−1, respectively. The suitability of the method for the determination of these analgesics in pharmaceutical preparations and urine samples was also ascertained.

  4. Simultaneous voltammetric determination of morphine and noscapine by adsorptive differential pulse stripping method and least-squares support vector machines.

    Science.gov (United States)

    Niazi, Ali; Ghasemi, Jahanbakhsh; Zendehdel, Mojgan

    2007-11-30

    An adsorptive differential pulse stripping method for the simultaneous determination of morphine and noscapine is proposed. The procedure involves an adsorptive accumulation of morphine and noscapine on a hanging mercury drop electrode (HMDE), followed by oxidation of adsorbed morphine and noscapine by voltammetric scan using differential pulse modulation. The optimum experimental conditions are: pH 10.0, accumulation potential of -100 mV versus Ag/AgCl, accumulation time of 150 s, scan rate of 40 mV s(-1) and pulse height of 100 mV. Morphine and noscapine peak currents were observed in same potential region at about +0.25 V. The simultaneous determination of morphine and noscapine by using voltammetry is a difficult problem in analytical chemistry, due to voltammogram interferences. The resolution of mixture of morphine and noscapine by the application of least-squares support vector machines (LS-SVM) was performed. The linear dynamic ranges were 0.01-3.10 and 0.015-2.75 microg mL(-1) and detection limits were 3 and 7 ng mL(-1) for morphine and noscapine, respectively. The capability of the method for the analysis of real samples was evaluated by the determination of morphine and noscapine in addict's human plasma with satisfactory results.

  5. Adsorptive stripping voltammetric determination of nitroimidazole derivative on multiwalled carbon nanotube modified electrodes: influence of size and functionalization of nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jara-Ulloa, Paola; Canete-Rosales, Paulina; Nunez-Vergara, Luis J; Squella, Juan A., E-mail: asquella@ciq.uchile.c [University of Chile, Santiago (Chile). Chemical and Pharmaceutical Sciences Faculty. Bioelectrochemistry Lab.

    2011-07-01

    1-Methyl-4-nitro-2-bromine methylimidazole (4-NimMeBr), was electrochemically reduced on mercury, glassy carbon and multiwalled carbon nanotubes (MWCNT) modified electrodes. 4-NimMeBr was adsorbed on the MWCNT modified electrode thus permitting the implementation of an adsorptive stripping voltammetric (ASV) method. We have used 4-NimMeBr as a prototype electroactive nitro compound to study the effect of both the size of the nanotubes and its functionalization by oxidation. The oxidized MWCNT forms better dispersions than the non-oxidized, producing electrode surface with higher density of MWCNT as was determined by electrochemical mapping using scanning electrochemical microscopy (SECM). Under the optimized conditions, the peak current was proportional to the concentration of 4-NimMeBr in the range of 10{sup -6} mol L{sup -1} to 10{sup -4} mol L{sup -1} with detection and quantification limits of 4.41 x 10{sup -6} mol L{sup -1} and 6.21 x 10{sup -6} mol L{sup -1}, respectively. The sensibility of bare electrode was 0.01 {mu}A per mmol L{sup -1}, which was lower than the value of 5.34 and 6.97 mA per mmol L{sup -1} obtained using short and large oxidized MWCNT, respectively. (author)

  6. Note: Design and development of improved indirectly heated cathode based strip electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Namita; Patil, D. S.; Dasgupta, K. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Bade, Abhijeet; Tembhare, G. U. [Department of Mechanical Engineering, Veermata Jijabai Technological Institute, Matunga, Mumbai 400 019 (India)

    2015-02-15

    An improved design of indirectly heated solid cathode based electron gun (200 kW, 45 kV, 270° bent strip type electron gun) has been presented. The solid cathode is made of thoriated tungsten, which acts as an improved source of electron at lower temperature. So, high power operation is possible without affecting structural integrity of the electron gun. The design issues are addressed based on the uniformity of temperature on the solid cathode and the single long filament based design. The design approach consists of simulation followed by extensive experimentation. In the design, the effort has been put to tailor the non-uniformity of the heat flux from the filament to the solid cathode to obtain better uniformity of temperature on the solid cathode. Trial beam experiments have been carried out and it is seen that the modified design achieves one to one correspondence of the solid cathode length and the electron beam length.

  7. Calibration of cathode strip gains in multiwire drift chambers of the GlueX experiment

    Energy Technology Data Exchange (ETDEWEB)

    Berdnikov, V. V.; Somov, S. V.; Pentchev, L.; Somov, A.

    2016-07-01

    A technique for calibrating cathode strip gains in multiwire drift chambers of the GlueX experiment is described. The accuracy of the technique is estimated based on Monte Carlo generated data with known gain coefficients in the strip signal channels. One of the four detector sections has been calibrated using cosmic rays. Results of drift chamber calibration on the accelerator beam upon inclusion in the GlueX experimental setup are presented.

  8. Trace and selective determination of cobalt(II in water and salt samples using cathodic adsorptive stripping voltammetry in the presence of pyrogallol red

    Directory of Open Access Journals (Sweden)

    Hasanpour Foroozan

    2013-01-01

    Full Text Available A sensitive and selective procedure is presented for voltammetric determination of cobalt. The procedure involves an adsorptive accumulation of cobalt pyrogallol red (PGR complex on stationary mercury drop electrode, followed by cathodic stripping voltammetry measurement of reduction current of adsorbed complex at -1.17 V (vs. Ag/AgCl. The optimum conditions for determination of cobalt include pH 11.0, 35 μM pyrogallol red, an accumulation potential of -0.9 V (vs. Ag/AgCl and scan rate 80 mVs-1. The peak current is proportional to the concentration of cobalt over the concentration range of 5.0 to 280 ng mL-1 with a detection limit of 1 ng mL-1 with an accumulation time of 140 s. The method was applied for the determination of cobalt in analytical grade NaCl and water samples.

  9. Manganese Detection with a Metal Catalyst Free Carbon Nanotube Electrode: Anodic versus Cathodic Stripping Voltammetry.

    Science.gov (United States)

    Yue, Wei; Bange, Adam; Riehl, Bill L; Riehl, Bonnie D; Johnson, Jay M; Papautsky, Ian; Heineman, William R

    2012-10-01

    Anodic stripping voltammetry (ASV) and cathodic stripping voltammetry (CSV) were used to determine Mn concentration using metal catalyst free carbon nanotube (MCFCNT) electrodes and square wave stripping voltammetry (SWSV). The MCFCNTs are synthesized using a Carbo Thermal Carbide Conversion method which results in a material that does not contain residual transition metals. Detection limits of 120 nM and 93 nM were achieved for ASV and CSV, respectively, with a deposition time of 60 s. CSV was found to be better than ASV in Mn detection in many aspects, such as limit of detection and sensitivity. The CSV method was used in pond water matrix addition measurements.

  10. Manganese Detection with a Metal Catalyst Free Carbon Nanotube Electrode: Anodic versus Cathodic Stripping Voltammetry

    Science.gov (United States)

    Yue, Wei; Bange, Adam; Riehl, Bill L.; Riehl, Bonnie D.; Johnson, Jay M.; Papautsky, Ian; Heineman, William R.

    2013-01-01

    Anodic stripping voltammetry (ASV) and cathodic stripping voltammetry (CSV) were used to determine Mn concentration using metal catalyst free carbon nanotube (MCFCNT) electrodes and square wave stripping voltammetry (SWSV). The MCFCNTs are synthesized using a Carbo Thermal Carbide Conversion method which results in a material that does not contain residual transition metals. Detection limits of 120 nM and 93 nM were achieved for ASV and CSV, respectively, with a deposition time of 60 s. CSV was found to be better than ASV in Mn detection in many aspects, such as limit of detection and sensitivity. The CSV method was used in pond water matrix addition measurements. PMID:24235806

  11. A square-wave adsorptive stripping voltammetric method for the determination of Amaranth, a food additive dye.

    Science.gov (United States)

    Alghamdi, Ahmad H

    2005-01-01

    Square-wave adsorptive stripping voltammetric (AdSV) determinations of trace concentrations of the azo coloring agent Amaranth are described. The analytical methodology used was based on the adsorptive preconcentration of the dye on the hanging mercury drop electrode, followed by initiation of a negative sweep. In a pH 10 carbonate supporting electrolyte, Amaranth gave a well-defined and sensitive AdSV peak at -518 mV. The electroanalytical determination of this azo dye was found to be optimal in carbonate buffer (pH 10) under the following experimental conditions: accumulation time, 120 s; accumulation potential, 0.0 V; scan rate, 600 mV/s; pulse amplitude, 90 mV; and frequency, 50 Hz. Under these optimized conditions the AdSV peak current was proportional over the concentration range 1 x 10(-8)-1.1 x 10(-7) mol/L (r = 0.999) with a detection limit of 1.7 x 10(-9) mol/L (1.03 ppb). This analytical approach possessed enhanced sensitivity, compared with conventional liquid chromatography or spectrophotometry and it was simple and fast. The precision of the method, expressed as the relative standard deviation, was 0.23%, whereas the accuracy, expressed as the mean recovery, was 104%. Possible interferences by several substances usually present as food additive azo dyes (E110, E102), gelatin, natural and artificial sweeteners, preservatives, and antioxidants were also investigated. The developed electroanalyticals method was applied to the determination of Amaranth in soft drink samples, and the results were compared with those obtained by a reference spectrophotometric method. Statistical analysis (paired t-test) of these data showed that the results of the 2 methods compared favorably.

  12. Differential Pulse Anodic Stripping Voltammetric Determination of Lead with Heparin Modified Electrode

    Institute of Scientific and Technical Information of China (English)

    LI,Nian-Bing(李念兵); DUAN,Jian-Ping(段建平); CHEN,Guo-Nan(陈国南)

    2004-01-01

    A novel differential pulse anodic stripping voltammetry for the determination of trace amounts of lead, using a biomacromolecule heparin drop-coated modified glassy carbon electrode, has been described. Pb2+ was deposited on the surface of a heparin-modified electrode at - 1.0 V (vs. SCE) via forming Pb2+-heparin and subsequent reduction at the electrode. In the following step, Pb-heparin was oxidized, and voltammograms were recorded by scanning the potential in a positive direction. Conditions were optimized with respect to the pH of the medium, the mass of drop-coated heparin, accumulation potential and accumulation time. The peak current was proportional to the Pb2+ concentration in the range of 2.0× 10-9 to 7.0× 10-7 mol/L, The detection limit was 3.0× 10-10 mol/L.The relative standard deviation was 4.83% for 1.0× 10-8mol/L Pb2- (n= 10). The developed method has been applied to the determination of Pb2- in water samples with satisfactory results.

  13. Upgrades to the CSC Cathode Strip Chamber Electronics for HL-LHC

    CERN Document Server

    Bravo, Cameron Bily

    2016-01-01

    The luminosity, latency, and trigger rate foreseen at the High Luminosity LHC (HL-LHC) present challenges to efficient readout of the Cathode Strip Chambers (CSCs) of the CMS end cap muon detector. Upgrades to the electronics are targeted for the inner rings of CSCs in each station, which have the highest flux of particles. The upgrades comprise digital cathode front end boards for nearly deadtimeless and long trigger latency operating capability, new DAQ boards that transmit data from the detectors with higher-bandwidth links, and a new data concentrator/interface to the central DAQ system that can receive the higher input rates.

  14. Monte Carlo studies on Cathode Strip/Pad Chambers for the ALICE Di-Muon Arm

    Energy Technology Data Exchange (ETDEWEB)

    Wurzinger, R.; Le Bornec, Y.; Willis, N.

    1996-04-01

    A general overview about the properties of Cathode Strip and Pad Chambers is given. Position finding methods are discussed and compared within Monte Carlo studies. Noise contributions and their minimization are discussed. Pad chambers allow a two-dimensional readout with spatial resolution of {sigma} < 100 {mu}m in direction parallel to the anode wire. The resolution normal to the anode wire depends mainly on the wire spacing. Special attention is paid on the double-hit resolution capability of the pad chamber. An outlook is given on the possible utilisation of Cathode Pad Chambers in the Di-Muon Arm of the ALICE detector at LHC. (author). 44 refs.

  15. Upgrades to the CSC Cathode Strip Chamber electronics for HL-LHC

    Science.gov (United States)

    Bravo, C.

    2017-01-01

    The luminosity, latency, and trigger rate foreseen at the High Luminosity LHC (HL-LHC) present challenges to efficient readout of the Cathode Strip Chambers (CSCs, [1]) of the CMS end cap muon detector. Upgrades to the electronics are targeted for the inner rings of CSCs in each station, which have the highest flux of particles. The upgrades comprise digital cathode front end boards for nearly deadtimeless and long trigger latency operating capability, new DAQ boards that transmit data from the detectors with higher-bandwidth links, and a new data concentrator/interface to the central DAQ system that can receive the higher input rates.

  16. Performance of the CMS Cathode Strip Chamber endcap muon detectors in Run 2 and first results with 2015 data

    CERN Document Server

    CMS Collaboration

    2015-01-01

    The Cathode Strip Chambers (CSC's) are located in the CMS endcap and record muons in the region of absolute pseudorapidity between 0.9 and 2.4. The first performance results of the CSC's in Run 2 are shown.

  17. A New Segment Building Algorithm for the Cathode Strip Chambers in the CMS Experiment

    Directory of Open Access Journals (Sweden)

    Golutvin I.

    2016-01-01

    Full Text Available A new segment building algorithm for the Cathode Strip Chambers in the CMS experiment is presented. A detailed description of the new algorithm is given along with a comparison with the algorithm used in the CMS software. The new segment builder was tested with different Monte-Carlo data samples. The new algorithm is meant to be robust and effective for hard muons and the higher luminosity that is expected in the future at the LHC.

  18. Upgrades to the CMS Cathode Strip Chambers for 2017 and the High Luminosity LHC

    Science.gov (United States)

    Morse, David; CMS Collaboration

    2017-01-01

    An overview will be given of upgrades to the CMS Cathode Strip Chambers (CSC) during the extended technical stop 2016-2017 and plans for future upgrades targeting the HL-LHC. HL-LHC conditions will surpass the physical capabilities of the present detector, and require novel hardware to cope with increased rates and maintain the high performance of the CSC achieved up to now.

  19. Completion of cathode strip chamber (CSC) installation on the "plus" endcap of CMS

    CERN Multimedia

    Richard Breedon, UC Davis

    2006-01-01

    A set of 16 pictures of the completion of installation of the cathode strip chambers (CSC) on the "plus" side endcap. Here a CSC destined for placement under the "nose" on the front of the innermost endcap disk ("YE+1") is being lifted over the endcap hadron calorimeter (HCAL, within the black section). The CSC to be installed is attached to the installation fixture using the special extension arm required to reach chamber locations beneath the nose.

  20. The new segment building algorithm for the cathode strip chambers in the CMS experiment

    CERN Document Server

    Golutvin, Igor; Pal'Chik, Vladimir; Voytishin, Nikolay; Zarubin, Anatoly

    2015-01-01

    A new segment building algorithm for the Cathode Strip Chambers in the CMS experiment is presented. A detailed description of the new algorithm is given along with a comparison with the standard algorithm. The new segment builder was tested with different Monte-Carlo data samples. The new algorithm is meant to be robust and effective fot the higher luminosity and hard muons that are expected in the future at LHC.

  1. Cathodic adsorptive stripping voltammetry of drotaverine hydrochloride and its determination in tablets and human urine by differential pulse voltammetry.

    Science.gov (United States)

    Zayed, S I M; Issa, Y M

    2009-04-01

    The stripping voltammetric behaviour of drotaverine hydrochloride (DvCl) was studied using a hanging mercury drop electrode (HMDE). The adsorptive stripping response has been evaluated with respect to pH, accumulation time, accumulation potential, scan rate and other variables. Differential pulse DP mode; over the potential range -400 to -1200 mV, is used in the presence of 0.04 M Britton-Robinson buffer pH 2. Cyclic voltammetric study indicates that the reduction process is irreversible and controlled by adsorption. The response of DP technique is linear over the concentration range 21.70-257.34 ng/ml. Limit of detection and limit of quantification were 3.15 and 10.50 ng/ml, respectively. The proposed method was successfully applied for the determination of the drug in commercial tablets and spiked human urine samples.

  2. Determination of Total Germanium in Chinese Herbal Remedies by Square-Wave Catalytic Adsorptive Cathodic Stripping Voltammetry at an Improved Bismuth Film Electrode

    Directory of Open Access Journals (Sweden)

    Shangwei Zhong

    2013-01-01

    Full Text Available A catalytic adsorptive cathodic stripping voltammetric method on an improved bismuth film electrode (BiFE for the determination of trace germanium in the presence of pyrogallol has been investigated. A well-defined and sensitive stripping peak of Ge(IV-pyrogallol complex was observed at −0.79 V (versus SCE in a 0.1 M acetate buffer solution (pH 4.8 at a deposition potential of −0.34 V. The reduction current is catalytically enhanced by adding KBrO3. The experimental variables and potential interference were studied. Compared with the BiFE plated in the solution prepared based on HAc-NaAc without trisodium citrate, the improved BiFE electrodeposited in the solution of HAc-NaAc containing trisodium citrate displayed a better electroanalytical performance for the determination of germanium(IV. Under the optimized conditions, the detection limit of Ge(IV was 60 ng L−1, and the relative standard deviation (RSD was 3.73% at 5 μg L−1 level (n=9. This method was successfully applied to determine the total germanium in several Chinese herbal remedies.

  3. Aging tests of full-scale CMS muon cathode strip chambers

    CERN Document Server

    Acosta, D; Arisaka, K; Bondar, N; Breedon, R; Bujak, A; Bylsma, B; Chester, N; Clare, R; Cline, D; Cousins, R; Cox, T; Dolinski, S I; Durkin, S; Eartly, D; Ivanov, Yu; Ferguson, T; Gavrilov, G; Gilmore, J; Gu, J; Gutay, L; Hann, F; Hartmut, R; Hauser, J; He, K; Ignatenko, M A; Ilie, S; Jiang, C; Ko, W; Korytov, A; Krivshich, A G; Kuznetsova, K; Layter, J; Lee, R; Levchenko, P M; Ling, T Y; Loveless, D; Lusin, S; Maeshima, K; Madorsky, A; Matthey, C; Matveev, M; Von der Mey, M; Mitselmakher, G; Otwinowski, S; Padley, P; Pal, I; Pischalnikov, Y; Prokofiev, O E; Razmyslovich, B V; Reeder, D; Roberts, J; Schipunov, L; Smirnov, I; Souvorov, V; Stasko, J T; Sun, H; Sytnik, V V; Terentyev, N K; Tripathi, M; Vavilov, S; Volkov, S; Vorobyov, A; Vorobyov, I A; Wang, L; Yarba, V A; Zhou, L; Zhu, Z

    2003-01-01

    Two CMS production Cathode Strip Chambers were tested for aging effects in a high-radiation environment at the Gamma Irradiation Facility at CERN. The chambers were irradiated over a large area: in total, about 2.1m**2 or 700m of wire in each chamber. The 40% Ar+50% CO//2+10% CF//4 gas mixture was provided by an open-loop gas system for one of the chambers and by a closed-loop re-circulating gas system for the other. After an accumulation of 0.3-0.4C/cm of a wire, equivalent to about 30-50 years of operation at peak LHC luminosity, no significant changes in gas gain, chamber efficiency and wire signal noise were observed for either of the two chambers. The only consistent signs of aging were a small increase in dark current from 2 to 10nA per plane of 600 wires and a decrease of strip-to-strip resistance from 1000 to 10-100GOmega. Disassembly of the chambers revealed deposits on the cathode planes, while the anode wires remained fairly clean.

  4. Determination of water in room temperature ionic liquids by cathodic stripping voltammetry at a gold electrode.

    Science.gov (United States)

    Zhao, Chuan; Bond, Alan M; Lu, Xunyu

    2012-03-20

    An electrochemical method based on cathodic stripping voltammetry at a gold electrode has been developed for the determination of water in ionic liquids. The technique has been applied to two aprotic ionic liquids, (1-butyl-3-ethylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate), and two protic ionic liquids, (bis(2-hydroxyethyl)ammonium acetate and triethylammonium acetate). When water is present in an ionic liquid, electrooxidation of a gold electrode forms gold oxides. Thus, application of an anodic potential scan or holding the potential of the electrode at a very positive value leads to accumulation of an oxide film. On applying a cathodic potential scan, a sensitive stripping peak is produced as a result of the reduction of gold oxide back to gold. The magnitude of the peak current generated from the stripping process is a function of the water concentration in an ionic liquid. The method requires no addition of reagents and can be used for the sensitive and in situ determination of water present in small volumes of ionic liquids. Importantly, the method allows the determination of water in the carboxylic acid-based ionic liquids, such as acetate-based protic ionic liquids, where the widely used Karl Fischer titration method suffering from an esterification side reaction which generates water as a side product.

  5. Circulating cathodic antigen cassette test versus haematuria strip test in diagnosis of urinary schistosomiasis.

    Science.gov (United States)

    El-Ghareeb, Azza S; Abd El Motaleb, Ghada S; Waked, Nevien Maher; Osman Hany Kamel, Nancy; Aly, Nagwa Shaban

    2016-12-01

    Urinary schistosomiasis caused by Schistosoma haematobium constitutes a major public health problem in many tropical and sub-tropical countries. This study was conducted to evaluate circulating cathodic antigen cassette test and haematuria strip test for detection of S. haematobium in urine samples and to evaluate their screening performance among the study population. Microscopy was used as a gold standard. A total of 600 urine samples were examined by microscopy for detection of S. haematobium eggs, screened for microhaematuria using Self-Stik reagent strips and screened for circulating cathodic antigen (CCA) using the urine-CCA cassette test. The specificity of CCA, microhaematuria and macrohaematuria was 96.4, 40.6 and 31.2 % respectively while the sensitivity was 88.2, 99.3 and 100 % respectively which was statistically significant (P < 0.001). These findings suggest that using of urine-CCA cassette test in diagnosis of urinary schistosomiasis is highly specific (96.4 %) compared with the highly sensitive haematuria strip test (100 %). The degree of agreement between microscopic examination and CCA detection was 99.3 % with highly statistically significant difference (P < 0.001). The combination of two techniques could potentially use for screening and mapping of S. haematobium infection.

  6. Expert System for the LHC CMS Cathode Strip Chambers (CSC) detector

    Science.gov (United States)

    Rapsevicius, Valdas; Juska, Evaldas

    2014-02-01

    Modern High Energy Physics experiments are of high demand for a generic and consolidated solution to integrate and process high frequency data streams by applying experts' knowledge and inventory configurations. In this paper we present the Expert System application that was built for the Compact Muon Solenoid (CMS) Cathode Strip Chambers (CSC) detector at the Large Hadron Collider (LHC) aiming to support the detector operations and to provide integrated monitoring. The main building blocks are the integration platform, rule-based complex event processing engine, ontology-based knowledge base, persistent storage and user interfaces for results and control.

  7. Expert System for the LHC CMS Cathode Strip Chambers (CSC) detector

    Energy Technology Data Exchange (ETDEWEB)

    Rapsevicius, Valdas, E-mail: valdas.rapsevicius@cern.ch [Fermi National Accelerator Laboratory, Batavia, IL (United States); Vilnius University, Didlaukio g. 47-325, LT-08303 Vilnius (Lithuania); Juska, Evaldas, E-mail: evaldas.juska@cern.ch [Fermi National Accelerator Laboratory, Batavia, IL (United States)

    2014-02-21

    Modern High Energy Physics experiments are of high demand for a generic and consolidated solution to integrate and process high frequency data streams by applying experts' knowledge and inventory configurations. In this paper we present the Expert System application that was built for the Compact Muon Solenoid (CMS) Cathode Strip Chambers (CSC) detector at the Large Hadron Collider (LHC) aiming to support the detector operations and to provide integrated monitoring. The main building blocks are the integration platform, rule-based complex event processing engine, ontology-based knowledge base, persistent storage and user interfaces for results and control.

  8. Misura delle caratteristiche del rivelatore a Cathode Strip Chambers per l’esperimento Totem

    CERN Document Server

    Boccone, Vittorio

    2004-01-01

    The aim of my thesis was to characterize the Cathode Strip Chamber (CSC) detector of the T1 inelastic detector of the TOTEM experiment. In the first two chapters I briefly introduce the TOTEM physics and the TOTEM experiment. In the third chapter I describe the basic principles of the ionizing detectors relevant to the TOTEM CSCs. Here I show also the results of few simulations done to determine the construction and operating parameters of the detector. The last two chapter are dedicated to the description of the experimental apparatus I build and the discussion of the TOTEM test beam results.

  9. Performance of the Cathode Strip Chamber endcap muon detectors in Run 2

    CERN Document Server

    Wulsin, H Wells

    2015-01-01

    Since the end of Run 1 of the LHC in 2012, the outermost ring has been added to the CMS Cathode Strip Chambers (CSC) endcap muon detector, and the readout electronics of the innermost ring of CSCs have been upgraded to accommodate the larger luminosity and collision energy anticipated in Run 2. A major effort was required to build, install, and commission these new chambers and electronics. This talk summarizes the improvements made during this upgrade and presents the performance of the CSC detector during the early stages of Run 2.

  10. Optimization of Stripping Voltammetric Sensor by a Back Propagation Artificial Neural Network for the Accurate Determination of Pb(II) in the Presence of Cd(II).

    Science.gov (United States)

    Zhao, Guo; Wang, Hui; Liu, Gang; Wang, Zhiqiang

    2016-09-21

    An easy, but effective, method has been proposed to detect and quantify the Pb(II) in the presence of Cd(II) based on a Bi/glassy carbon electrode (Bi/GCE) with the combination of a back propagation artificial neural network (BP-ANN) and square wave anodic stripping voltammetry (SWASV) without further electrode modification. The effects of Cd(II) in different concentrations on stripping responses of Pb(II) was studied. The results indicate that the presence of Cd(II) will reduce the prediction precision of a direct calibration model. Therefore, a two-input and one-output BP-ANN was built for the optimization of a stripping voltammetric sensor, which considering the combined effects of Cd(II) and Pb(II) on the SWASV detection of Pb(II) and establishing the nonlinear relationship between the stripping peak currents of Pb(II) and Cd(II) and the concentration of Pb(II). The key parameters of the BP-ANN and the factors affecting the SWASV detection of Pb(II) were optimized. The prediction performance of direct calibration model and BP-ANN model were tested with regard to the mean absolute error (MAE), root mean square error (RMSE), average relative error (ARE), and correlation coefficient. The results proved that the BP-ANN model exhibited higher prediction accuracy than the direct calibration model. Finally, a real samples analysis was performed to determine trace Pb(II) in some soil specimens with satisfactory results.

  11. Copper-based electrochemical sensor with palladium electrode for cathodic stripping voltammetry of manganese.

    Science.gov (United States)

    Kang, Wenjing; Pei, Xing; Bange, Adam; Haynes, Erin N; Heineman, William R; Papautsky, Ian

    2014-12-16

    In this work, we report on the development of a palladium-based, microfabricated point-of-care electrochemical sensor for the determination of manganese using square wave cathodic stripping voltammetry. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Voltammetry offers an attractive approach to metal detection on the microscale, but traditional carbon, gold, or platinum electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor uses palladium working and auxiliary electrodes and integrates them with a copper-based reference electrode for simple fabrication and compatibility with microfabrication and printed circuit board processing, while maintaining competitive performance in electrochemical detection. Copper electrodes were prepared on glass substrate using a combination of microfabrication procedures followed by electrodeposition of palladium. The disposable sensor system was formed by bonding a poly(dimethylsiloxane) (PDMS) well to the glass substrate. Cathodic stripping voltammetry of manganese using our new disposable palladium-based sensors exhibited 334 nM (18.3 ppb) limit of detection in borate buffer. The sensor was used to demonstrate manganese determination in natural water samples from a pond in Burnet Woods, located in Cincinnati, OH, and the Ohio River.

  12. Cathodic protection of reinforced concrete structure using discrete anode strips -- case history

    Energy Technology Data Exchange (ETDEWEB)

    Gulikers, J. [Ministry of Transport, Public Works and Water Management (Netherlands)

    2000-07-01

    Cathodic protection of reinforcing steel suffering from chloride-induced corrosion has been used for at least the last decade. It has been demonstrated to be the most appropriate, cost-effective and reliable repair option when compared to conventional repair methods. This case study describes the actions taken on a bridge substructure in the Netherlands, built in 1938 as the major structural support for a balance bridge, where a condition assessment revealed that reinforcement corrosion had been initiated by chloride penetration and carbonation. Cathodic protection with impressed current was proposed to protect the reinforcing steel. The system was based on discrete titanium anode strips, inserted perpendicular to the concrete surface. In order to achieve a uniform distribution of protective current, a system of an average of 10 strips per square meter of concrete surface was placed in holes drilled to a depth of 35 cm. In view of the innovative nature of the design and the heightened risk of non-uniform current distribution, provisions were made for additional monitoring of the performance of the cathodic system. Measurements included concrete resistance, current distribution over the concrete surface and frequent depolarization. Monitoring results revealed a pronounced non-uniform current distribution over the concrete surface and a high current demand in one particular zone. The pronounced differences encountered in this instance were attributed to delaminations and macroscopic cracks in the concrete cover, severely limiting the flow of protective current to the reinforcement. It is suggested that repair of the delaminations by injecting a low resistivity cementitious grout, thereby allowing the use of a more cost-effective surface-mounted anode system might have been a more appropriate option than the one chosen. The principal lesson learned from this particular case is the strong need for quantitative information regarding anodic and cathodic current

  13. Completion of cathode strip chamber (CSC) installation on the so-called YE+2 wheel of CMS on March 2005.

    CERN Multimedia

    Tejinder S. Virdee

    2005-01-01

    The pictures have been taken in the CMS construction hall in Cessy (neighbouring France), called SX5, in March 2005 and show the status of cathode strip chamber (CSC) assembly on the yoke disk YE+2. The chambers are labelled ME+3 and their installation has been completed on March 16th, 2005.

  14. Hough Transform Track Reconstruction in the Cathode Strip Chambers in ATLAS

    CERN Document Server

    Amram, Nir

    2008-01-01

    The world's largest and highest energy particle accelerator, the Large Hadron Collider (LHC), will collide two highly energetic proton beams in an attempt to discover a wide range of new physics. Among which, the primary ambitions are the discovery of the Higgs boson and suppersymmetric particles. ATLAS, one of its primary particle detectors, was designed as a general-purpose detector covering a broad range of energies and physical processes. A special emphasis on accurate muon tracking has led the ATLAS collaboration to design a stand-alone Muon Spectrometer, an extremely large tracking system extending all the way around the detector. Due to its immense size and range, parts of the spectrometer were designed to withstand a high rate of radiation, sifting the muon signals from the rest of the signals (primarily neutrons and photons). The Cathode Strip Chambers (CSCs) are special multiwire proportional chambers placed in the high $\\eta$ region on of the Muon Spectrometer, where flux of background particles is...

  15. The renewable bismuth bulk annular band working electrode: fabrication and application in the adsorptive stripping voltammetric determination of nickel(II) and cobalt(II).

    Science.gov (United States)

    Baś, Bogusław; Węgiel, Krystian; Jedlińska, Katarzyna

    2015-06-30

    The paper presents the first report on fabrication and application of a user friendly and mercury free electrochemical sensor, with the renewable bismuth bulk annular band working electrode (RBiABE), in stripping voltammetry (SV). The sensor body is partly filled with the internal electrolyte solution, in which the RBiABE is cleaned and activated before each measurement. Time of the RBiABE contact with the sample solution is precisely controlled. The usefulness of this sensor was tested by Ni(II) and Co(II) traces determination by means of differential pulse adsorptive stripping voltammetry (DP AdSV), after complexation with dimethylglyoxime (DMG) in ammonia buffer (pH 8.2). The experimental variables (composition of the supporting electrolyte, pre-concentration potential and time, potential of the RBiABE activation, and DP parameters), as well as possible interferences, were investigated. The linear calibration graphs for Ni(II) and Co(II), determined individually and together, in the range from 1×10(-8) to 70×10(-8)molL(-1) and from 1×10(-9) to 70×10(-9)molL(-1) respectively, were obtained. The calculated limit of detection (LOD), for 30s of the accumulation time, was 3×10(-9)molL(-1) for Ni(II) in case of a single element's analysis, whereas the LOD was 5×10(-9)molL(-1) for Ni(II) and 3×10(-10)molL(-1) for Co(II), when both metal ions were measured together. The repeatability of the Ni(II) and Co(II) adsorptive stripping voltammetric signals obtained at the RBiABE were equal to 5.4% and 2.5%, respectively (n=5). Finally, the proposed method was validated by determining Ni(II) and Co(II) in the certified reference waters (SPS-SW1 and SPS-SW2) with satisfactory results.

  16. Bare and Polymer-Coated Indium Tin Oxide as Working Electrodes for Manganese Cathodic Stripping Voltammetry.

    Science.gov (United States)

    Rusinek, Cory A; Bange, Adam; Warren, Mercedes; Kang, Wenjing; Nahan, Keaton; Papautsky, Ian; Heineman, William R

    2016-04-19

    Though an essential metal in the body, manganese (Mn) has a number of health implications when found in excess that are magnified by chronic exposure. These health complications include neurotoxicity, memory loss, infertility in males, and development of a neurologic psychiatric disorder, manganism. Thus, trace detection in environmental samples is increasingly important. Few electrode materials are able to reach the negative reductive potential of Mn required for anodic stripping voltammetry (ASV), so cathodic stripping voltammetry (CSV) has been shown to be a viable alternative. We demonstrate Mn CSV using an indium tin oxide (ITO) working electrode both bare and coated with a sulfonated charge selective polymer film, polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-sulfonate (SSEBS). ITO itself proved to be an excellent electrode material for Mn CSV, achieving a calculated detection limit of 5 nM (0.3 ppb) with a deposition time of 3 min. Coating the ITO with the SSEBS polymer was found to increase the sensitivity and lower the detection limit to 1 nM (0.06 ppb). This polymer modified electrode offers excellent selectivity for Mn as no interferences were observed from other metal ions tested (Zn(2+), Cd(2+), Pb(2+), In(3+), Sb(3+), Al(3+), Ba(2+), Co(2+), Cu(2+), Ni(3+), Bi(3+), and Sn(2+)) except Fe(2+), which was found to interfere with the analytical signal for Mn(2+) at a ratio 20:1 (Fe(2+)/Mn(2+)). The applicability of this procedure to the analysis of tap, river, and pond water samples was demonstrated. This simple, sensitive analytical method using ITO and SSEBS-ITO could be applied to a number of electroactive transition metals detectable by CSV.

  17. Voltammetric and electrochemical impedance spectroscopy characterization of a cathodic and anodic pre-treated boron doped diamond electrode

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, S. Carlos B. [Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra (Portugal); Oliveira-Brett, Ana Maria, E-mail: brett@ci.uc.p [Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra (Portugal)

    2010-06-01

    The effect of boron doped diamond (BDD) surface termination, immediately after cathodic and anodic electrochemical pre-treatments, on the electrochemical response of a BDD electrode in aqueous media and the influence of the different supporting electrolytes utilized in these pre-treatments on the final surface termination was investigated with [Fe(CN){sub 6}]{sup 4-/3-}, as redox probe, by cyclic and differential pulse voltammetry and electrochemical impedance spectroscopy. The cyclic voltammetry results indicate that the electrochemical behavior for the redox couple [Fe(CN){sub 6}]{sup 4-/3-} is very dependent on the state of the BDD surface, and a reversible response was observed after the cathodic electrochemical pre-treatment, whereas a quasi-reversible response occurred after anodic electrochemical pre-treatment. Differential pulse voltammetry in acetate buffer also showed that the potential window is very much influenced by the electrochemical pre-treatment of the BDD surface. Electroactivity of non-diamond carbon surface species (sp{sup 2} inclusions) incorporated into the diamond structure was observed after cathodic and anodic pre-treatments. Electrochemical impedance spectroscopy confirmed the cyclic voltammetry results and indicates that the BDD surface resistance and capacitance vary significantly with the electrolyte and with the electrochemical pre-treatment, caused by different surface terminations of the BDD electrode surface.

  18. Distribution of the Timing, Trigger and Control Signals in the Endcap Cathode Strip Chamber System at CMS

    CERN Document Server

    Geurts, F; Padley, P

    2007-01-01

    This paper presents the implementation of the Timing, Trigger and Control (TTC) signal distribution tree in the Cathode Strip Chamber (CSC) sub-detector of the CMS Experiment at CERN. The key electronic component, the Clock and Control Board (CCB) is described in detail, as well as the transmission of TTC signals from the top of the system down to the front-end boards.

  19. Adsorptive stripping differential pulse voltammetric determination of venlafaxine and desvenlafaxine employing Nafion-carbon nanotube composite glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Sanghavi, Bankim J. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098, Maharashtra (India); Srivastava, Ashwini K., E-mail: aksrivastava@chem.mu.ac.i [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098, Maharashtra (India)

    2011-04-15

    A Nafion-carbon nanotube-modified glassy carbon electrode (NAF-CNT-GCE) was developed for the determination of venlafaxine (VF) and desvenlafaxine (DVF). The electrochemical behavior of both these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and adsorptive stripping differential pulse voltammetry (AdSDPV). The surface morphology of the electrodes has been studied by means of scanning electron microscopy (SEM). These studies revealed that the oxidation of VF and DVF is facilitated at NAF-CNT-GCE. After optimization of analytical conditions employing this electrode at pH 7.0 in Britton-Robinson buffer (0.05 M) for VF and pH 5.0 in acetate buffer (0.1 M) for DVF, the peak currents for both the molecules were found to vary linearly with their concentrations in the range of 3.81 x 10{sup -8}-6.22 x 10{sup -5} M for VF and 5.33 x 10{sup -8}-3.58 x 10{sup -5} M for DVF. The detection limits (S/N = 3) of 1.24 x 10{sup -8} and 2.11 x 10{sup -8} M were obtained for VF and DVF, respectively, using AdSDPV. The prepared modified electrode showed several advantages, such as simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of VF and DVF in pharmaceutical formulations, urine and blood serum samples.

  20. Determination of Selenium in infant formula by differential pulse cathodic stripping voltammetry

    Directory of Open Access Journals (Sweden)

    "Oveisi MR

    2002-07-01

    Full Text Available Selenium as a nonmetallic chemical element has received high attention of biologists because of its dual role as an essential trace nutrient and a toxic element. This interest has created a need for reliable analytical methods for determination of selenium. In this investigation determination of selenium by differential pulse cathodic stripping voltammetry and the influence of various parameters such as deposition potentials, deposition time. Cu concentration pH, etc. on selenium peak in voltammogram are described. Determination of selenium was accomplished in mixture of acetic acid, hydrochloric acid and sodium chloride buffer (pH=1 with a scan rate of 60 mv/s and a pulse height of 100 my by hanging mercury drop electrode (HMDE as working electrode. The solution was stirred during pre-electrolysis at - 350 mv (vs SCE for 30 s and the potential was scanned between - 350 mv and - 800 mv. The determination limit of the method was 0.005 mg/kg for the sample. The calibration curves were linear in the range of 0-30 μg/L (R2=0.996, p<0.001. Repeatability of the method at concentrations of 30 and 0.5 μg/L were 2.5 and 10.5% respectively.

  1. Efficiency of Finding Muon Track Trigger Primitives in CMS Cathode Strip Chambers

    CERN Document Server

    Acosta, Darin; Andreev, Valeri; Apollinari, Giorgio; Baek, Yong Wook; Banicz, Karoly; Barashko, Victor; Barberis, Emanuela; Bartalini, Paolo; Bloch, Ingo; Boeriu, Oana; Bondar, Nikolai; Breedon, Richard; Bujak, Adam; Bylsma, Ben; Chen, Mingshui; Clare, Robert; Cline, David; Cousins, Robert; Cox, Peter Timothy; Denisov, Alexander; Drozdetskiy, Alexey; Durkin, S; Eartly, David P; Ershov, Yuri; Ferguson, Thomas; Fortin, Dominique; Geurts, Frank J M; Gilmore, Jason; Golovtsov, Victor; Golutvin, Igor; Golyash, Alexander; Gu, Jianhui; Gutay, Laszlo; Hauser, Jay; He, Kang-Lin; Holbrook, Britt; Holmes, Daniel; Ignatenko, Mikhail; Ippolito, Nicole; Ivanov, Yasen; Jiang, Chun-Hua; Kao, Shih-Chuan; Karjavin, Vladimir; Khabarov, Serguei; Killewald, Phillip; Ko, Winston; Kotov, Khristian; Korytov, Andrey; Kozhevnikov, Yuri; Lanaro, Armando; Levchenko, Petr; Ling, Ta-Yung; Liu, Jie; Loveless, Richard; Lusin, Sergei; Madorsky, Alexander; Matveev, Mikhail; Medved, Serguei; Mitselmakher, Guenakh; Moisenz, Petr; Padley, Brian Paul; Pakhotin, Yuriy; Pal, Imre; Perelygin, Victor; Petrunin, Anatoly; Pischalnikov, Yuriy; Pivarsky, J; Prokofiev, O; Rakness, Gregory; Roberts, Jay; Roe, Adam; Safonov, Alexei; Schetkovsky, A; Schipunov, L; Schmitt, Michael; Sknar, Vladimir; Stoynev, Stoyan; Sulimov, Valentin; Sun, Han-Sheng; Sytnik, Valeri; Tchekhovski, V; Terentyev, Nikolay; Tripathi, Mani; Tucker, Jordan; Tumanov, Alexander; Uvarov, Lev; Valuev, Vyacheslav; Vasilev, S; Vavilov, Sergey; Velichko, Georgy; Volkov, Serguei; Von der Mey, Martin; Vorobev, I; Vorobyev, Alexey; Vorobyev, Alexey; Wang, Dayong; Williams, Grayson; Yatsura, V; Zarubin, Anatoli; Zhao, Wei-Ren; Zheng, Yangheng; Zhmakin, G; Zhu, Zian; Zilizi, Gyula

    2007-01-01

    In the CMS Experiment, muon detection in the forward direction is accomplished by cathode strip chambers~(CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using~36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge~(MTCC) exercise conducted by the~CMS experiment in~2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area ($< \\! 0.01$~m$^2$), results presented in this paper were obtained by many installed CSCs operating {\\em in situ} over an area of $\\approx \\! 23$~m$^2$ as a part of the~CMS experiment. The efficiency of finding 2-dimensional trigger primitives within 6-layer chambers was found to be~$99.93 \\pm 0.03\\%$. These segments, found by the CSC electronics within $800$~ns after the passing of a muon through the chambers, are the input info...

  2. Upgrades to the CMS Cathode Strip Chamber Electronics for HL-LHC

    CERN Document Server

    Morse, David Michael

    2016-01-01

    Cathode strip chambers (CSCs) are used to detect muons in theend cap region of the CMS detector. The chambers are arrangedin rings in four planes on each end of the detector. The innerrings of CSCs in each station have the highest flux ofparticles and this presents challenges to efficient readout atthe luminosity, latency, and trigger rate foreseen at theHL-LHC.The existing front end electronics in Stations 2, 3, and 4 arebased on switched capacitor arrays with limited bufferingcapability. Queuing models have shown that significantsaturation of the buffers would occur for the luminosity, Level1 trigger rates, and required Level 1 latency for running atthe HL-LHC. In addition, the expected output rate of data isexpected to exceed the 1 Gbps bandwidth of the optical linksthat carry data to the back end, resulting in loss of eventsynchronization.The upgrade of the inner ring of CSCs addresses these problemsby replacing some types of electronics boards in these ringswith upgraded boards. In particular, the existi...

  3. Cathodic adsorptive stripping voltammetry of an anti-emetic agent Granisetron in pharmaceutical formulation and biological matrix

    Institute of Scientific and Technical Information of China (English)

    Rajeev Jain; Ramkishor Sharma

    2012-01-01

    Granisetron showed one well-defined reduction peak at Hanging Mercury Drop Electrode (HMDE) in the potential range from -1.3 to -1.5 V due to reduction of C=N bond. Solid-phase extraction technique was employed for extraction of Granisetron from spiked human plasma. Granisetron showed peak current enhancement of 4.45% at square-wave voltammetry and 5.33% at cyclic voltammetry as compared with the non stripping techniques. The proposed voltammetric method allowed quantification of Granisetron in pharmaceutical formulation over the target concentration range of 5-200 ng/mL with detection limit 13.63 ng/mL, whereas in human plasma 50-225 ng/mL with detection limit 11.75 ng/mL.

  4. Determination of selenium content in different types of seed oils by cathodic stripping potentiometry (CSP).

    Science.gov (United States)

    Dugo, Giacomo; La Pera, Lara; Pollicino, Donatella; Saitta, Marcello

    2003-09-10

    Seed oils are consumed worldwide; moreover, they are used in the alimentary, cosmetic, pharmaceutical, and chemical industries. Due to their diffusion, it is interesting to investigate the presence of important micronutrients such as selenium in seed oils. The aim of this work was to develop a rapid, precise, and sensitive cathodic stripping potentiometry (CSP) method to determine the concentration of selenium in different types of seed oils. Selenium was extracted from the oily matrix by concentrated hydrochloric acid treatment at 90 degrees C. The analysis was executed by applying an electrolysis potential of -150 mV for 60 s and a constant current of -30 microA. Under these conditions, detection limits of <0.5 ng g(-1) were obtained. The method reproducibility (expressed as total RSD %) spanned from 0.2 to 0.8%. Recoveries ranged from 92.1 to 97.5%, providing evidence that selenium quantification remained unaffected by the extraction procedure described. The results obtained with the proposed method were compared with those obtained via graphite furnace atomic absorption spectroscopy (GFAAS), a common method for determining selenium. The results of the two methods agreed within 93.5-107.7%. The mean amounts of selenium found were 313.0 +/- 2.0, 458.3 +/- 1.3, 224.6 +/- 0.9, 99.5 +/- 0.8, 332.2 +/- 0.5, 144.0 +/- 0.7, and 295.5 +/- 1.2 ng g(-1), respectively, in peanut, soybean, sunflower, rice, corn, grapestone, and seed oils.

  5. Diagnosis of Schistosomiasis by reagent strip test for detection of circulating cathodic antigen

    NARCIS (Netherlands)

    Dam, van G.J.; Wichers, J.H.; Falcao Ferreira, T.M.; Ghati, D.; Amerongen, van A.; Deelder, A.M.

    2004-01-01

    A newly developed reagent strip assay for the diagnosis of schistosomiasis based on parasite antigen detection in urine of infected individuals was evaluated. The test uses the principle of lateral flow through a nitrocellulose strip of the sample mixed with a colloidal carbon conjugate of a monoclo

  6. Study of a multi-wire proportional chamber with a cathode strip and delay-line readout

    Institute of Scientific and Technical Information of China (English)

    HAN Li-Ying; LI Qi-Te; Q. Faisal; GE Yu-Cheng; IU Hong-Tao; YE Yan-Lin

    2009-01-01

    The design principle for a multi-wire proportional chamber with a cathode strip and delay-line readout is described. A prototype chamber of a size of 10 cm ~ l0 cm was made together with the readout electronics circuit. A very clean signal with very low background noise was obtained by applying a transformer between the delay-line and the pre-amplifier in order to match the resistance. Along the anode wire direction a position resolution of less than 0.5 mm was achieved with a 55Fe-5.9 keV X ray source. The simple structure, large effective area and high position resolution allow the application of a gas chamber of this kind to many purposes.

  7. Effect of Gas Composition on the Performance of Cathode Strip Chambers for the CMS Endcap Muon System

    CERN Document Server

    Anderson, C; Korenblit, S; Korytov, Andrey; Mitselmakher, Guenakh

    2004-01-01

    The composition of the gas inside the cathode strip chambers (CSCs) defines many important performance parameters, including the gas gain and operational voltage range. Differences in these parameters were examined under variations in concentration of argon, carbon dioxide, and carbon tetrafluoride around the baseline mixture of Ar+CO2+CF4 = 40+50+10. The gas gain was found to be dependent primarily on the Ar concentration and nearly insensitive of the CF4/CO2 relative concentrations. The operational voltage range of ~370V had only a weak dependence on Ar concentration in the range of 40%-60% (-30 V for +20% change) at fixed amount of CF4, but showed about 3 times stronger dependence on the concentration of CF4 (+90 V for the concentration change from 0% to 20%) at fixed amount of Ar. We discuss 2 alternative gas mixtures Ar+CO2+CF4 = 60+30+10 and 60+35+5, which both offer performance (gas gain and plateau) very similar to that of the baseline mixture, but at 400 V lower absolute voltages.

  8. Field-based evaluation of a reagent strip test for diagnosis of Schistosomiasis mansoni by detecting circulating cathodic antigen (CCA in urine in low endemic area in Ethiopia

    Directory of Open Access Journals (Sweden)

    Legesse M.

    2008-06-01

    Full Text Available The sensitivity, specificity, positive and negative predictive values of a reagent strip test for the diagnosis of schistosomiasis mansoni by detecting circulating cathodic antigen (CCA in urine were evaluated using 184 stool and urine samples collected from schoolchildren living in relatively low endemic area of schistosomiasis mansoni in Ethiopia. A combined result of stool samples processed by Kato and formol-ether concentration methods was used as gold standard. The results showed that detection of CCA in urine using reagent strip test was slightly higher than the combined results of the stool techniques (65.2% vs 42.4%, p > 0.05 in suggesting the prevalence of the disease. The sensitivity, specificity, positive and negative predictive values of the reagent strip test were 76.9%, 43.4%, 50% and 71.9%, respectively. The result of egg counts using Kato method suggested that detection of urine CCA could be used to indicate the intensity of infection. Nevertheless, like that of stool examination, the reagent strip test was found to be less sensitive in case of light to moderate infections. About 23.1% of the study children who were excreting the eggs of the parasite were found negative by the reagent strip test. The relative insensitivity of a reagent strip test in low intensity of infection necessitates for the development of more sensitive assay that can truly discriminate schistosome-infected from non-infected individuals.

  9. Increased sensitivity of anodic stripping voltammetry at the hanging mercury drop electrode by ultracathodic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Jose A.; Rodrigues, Carlos M.; Almeida, Paulo J.; Valente, Ines M.; Goncalves, Luis M. [Requimte - Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, no. 687, 4169-007 Porto (Portugal); Compton, Richard G. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Barros, Aquiles A., E-mail: ajbarros@fc.up.pt [Requimte - Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, no. 687, 4169-007 Porto (Portugal)

    2011-09-09

    Highlights: {yields} At very cathodic accumulation potentials (overpotential deposition) the voltammetric signals of Zn{sup 2+}, Cd{sup 2+}, Pb{sup 2+} and Cu{sup 2+} increase. {yields} 5 to 10-fold signal increase is obtained. {yields} This effect is likely due to mercury drop oscillation at such cathodic potentials. {yields} This effect is also likely due to added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles. - Abstract: An improved approach to the anodic stripping voltammetric (ASV) determination of heavy metals, using the hanging mercury drop electrode (HMDE), is reported. It was discovered that using very cathodic accumulation potentials, at which the solvent reduction occurs (overpotential deposition), the voltammetric signals of zinc(II), cadmium(II), lead(II) and copper(II) increase. When compared with the classical methodology a 5 to 10-fold signal increase is obtained. This effect is likely due to both mercury drop oscillation at such cathodic potentials and added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles.

  10. Determination of para-arsanilic acid with improved diazotization reaction using differential pulse cathodic stripping voltammetry in aqueous system.

    Science.gov (United States)

    Misni, Marpongahtun; Sathishkumar, Palanivel; Ahamad, Rahmalan; MohdYusoff, Abdull Rahim

    2015-01-01

    Para-arsanilic acid (p-ASA) has been widely used in the poultry industry to promote growth and prevent dysentery. It is excreted unchanged in the manure and released into non-target sites causing organoarsenic pollution risk to the environment and living system. Therefore, simple and effective analytical strategies are demanded for determining the samples that contain p-ASA. However, direct determination of both p-ASA and ortho-arsanilic acid (o-ASA) using differential pulse cathodic stripping voltammetry (DPCSV) gives the similar voltammograms that directly hamper the analysis used by the DPCSV technique. In this study, a method to determine and differentiate p-ASA from o-ASA via diazotization and coupling reaction of the amine groups followed by the direct DPCSV determination of diazo compounds is presented. The diazotization reaction carried out at pH 1.5 and 0 ± 1°C for 10 min showed two reduction peaks in DPCSV at-70 mV and -440 mV vs. Ag/AgCl (KCl 3 M). However, when the diazotization reaction was performed at pH 12.5 and 0 ± 1°C for 40 min, a coloured azo compound was produced and the DPCSV showed only one reduction peak that appeared at -600 mV vs. Ag/AgCl (3 M of KCl). The results of this study show that only p-ASA compound gave a reduction peak, whereas o-ASA compound did not give any peak. The detection limit of p-ASA was found to be 4 × 10(-8 )M. As a result, the proposed electro-analytical technique might be a good candidate to determine and differentiate the p-ASA present in the poultry and environmental samples.

  11. Adsorptive stripping voltammetric determination of imipramine, trimipramine and desipramine employing titanium dioxide nanoparticles and an Amberlite XAD-2 modified glassy carbon paste electrode.

    Science.gov (United States)

    Sanghavi, Bankim J; Srivastava, Ashwini K

    2013-03-07

    An Amberlite XAD-2 (XAD2) and titanium dioxide nanoparticles (TNPs) modified glassy carbon paste electrode (XAD2-TNP-GCPE) was developed for the determination of imipramine (IMI), trimipramine (TRI) and desipramine (DES). The electrochemical behavior of these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and adsorptive stripping differential pulse voltammetry (AdSDPV). After optimization of analytical conditions using a XAD2-TNP-GCPE electrode at pH 6.0 phosphate buffer (0.1 M), the peak currents were found to vary linearly with its concentration in the range of 1.30 × 10(-9) to 6.23 × 10(-6) M for IMI, 1.16 × 10(-9) to 6.87 × 10(-6) M for TRI and 1.43 × 10(-9) to 5.68 × 10(-6) M for DES. The detection limits (S/N = 3) of 3.93 × 10(-10), 3.51 × 10(-10) and 4.35 × 10(-10) M were obtained for IMI, TRI and DES respectively using AdSDPV. The prepared modified electrode showed several advantages such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of IMI, TRI and DES in pharmaceutical formulations, blood serum and urine samples.

  12. Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Nedeltcheva, T. [Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsi Blvd., 1756 Sofia (Bulgaria)]. E-mail: nedel@uctm.edu; Atanassova, M. [Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsi Blvd., 1756 Sofia (Bulgaria); Dimitrov, J. [N. Pushkarov Institute of Soil Science and Agroecology, 7 Shosse Bankya St., 1080 Sofia (Bulgaria); Stanislavova, L. [N. Pushkarov Institute of Soil Science and Agroecology, 7 Shosse Bankya St., 1080 Sofia (Bulgaria)

    2005-01-10

    The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary.

  13. Regeneration of poly-L-lysine modified carbon electrodes in the accumulation and cathodic stripping voltammetric determination of the cromoglycate anion.

    Science.gov (United States)

    Pereira, F C; Fogg, A G; Zanoni, M V B

    2003-07-27

    Cromoglycate is accumulated on a poly-L-lysine (PLL) modified carbon electrode best from pH 4 solution, where it is anionic and the PLL is cationic, and at which pH the cromoglycate gives a good reduction peak at -0.82 V. The PLL film can be regenerated readily by washing the electrode with 3 M sodium hydroxide solution, in which the PLL is deprotonated. Regeneration of the film is not required as frequently when larger amounts of PLL are incorporated into it. This allows standard addition procedures to be carried out without regenerating the electrode. Linear calibration graphs have been obtained typically in the range 0.1-1.5 microg ml(-1). Detection limits have been calculated to be 10 ng ml(-1). The standard addition method has been applied satisfactorily to diluted urine solutions.

  14. Evaluation of circulating cathodic antigen (CCA strip for diagnosis of urinary schistosomiasis in Hassoba school children, Afar, Ethiopia

    Directory of Open Access Journals (Sweden)

    Ayele B.

    2008-03-01

    Full Text Available A total of 206 urine samples collected from Hassoba Elementary schoolchildren, Afar, Ethiopia, a low Schistosoma haematobium endemic setting, was diagnosed to evaluate the performance of CCA strip using double references, urine filtration technique and urinalysis dipstick (Combur 10 Test® that detect schistosome eggs and blood in urine, respectively. The former was used as a gold standard reference method. Sensitivity, specificity, positive and negative predictive values for the CCA were 52%, 63.8%, 56.7% and 59% respectively, with reference to urine filtration technique whereas these parameters were 50.4%, 62.4%, 55.6% and 57.5% respectively, with reference to Combur 10 Test®. 47 S. haematobium egg-positive children were found negative by CCA strip while 38 egg-negative children were found positive by CCA strip. Moreover, among the pre-tests done in duplicate, inconsistent results were also recorded. Assays were also compared with regard to the cost of equipment and reagents, speed and simplicity of use. Though CCA strip was found to be rapid and could be performed with minimal training, it was found to be expensive (US $ 4.95 per test to use it for large-scale field use even if its diagnostic value would have been satisfactory. Further development and standardization of the CCA strip are required for its applicability for field use. It is also recommended that its cost per strip should be substantially cut down if it is to be used in poor schistosomiasis endemic countries.

  15. Simultaneous determination of textile dyes by Adsorptive Cathodic Stripping Voltammetry - doi: 10.4025/actascitechnol.v35i2.16595

    Directory of Open Access Journals (Sweden)

    Lidia Brizola Santos

    2013-04-01

    Full Text Available The Adsorptive Cathodic Stripping Voltammetry (ACSV - differential pulse proved to be an efficient method in the separation and quantification of two reactive textile dyes, Procion Yellow (PY and Procion Red (PR, each containing two azo groups as chromophores and two monochlorotriazine reactive groups, at nanomolar level. The linearity of the method obtained for each reactive dye was 30.15 – 633.15 nmol L-1 for PY in B-R buffer pH 8.0, and 62.56 – 982.291 nmol L-1 for PR in B-R buffer pH 8.0, using preconcentration at -0.1 V during 60 s.   

  16. Avaliação da influência de sulfetos solúveis na complexação do cobre em águas superficiais empregando métodos voltamétricos Influence of dissolved sulfides on copper complexation in surface waters using voltammetric methods

    Directory of Open Access Journals (Sweden)

    Elizabeth W. O. Scheffer

    2010-01-01

    Full Text Available In this work a sulfide quantification protocol using voltammetric methods was developed to evaluate the effect of dissolved sulfides on copper complexation. On the basis of pH, sulfide release from the dissociation of specific metal sulfide complexes can be electrochemically measured and then removed (as H2S by a N2 purge. Cathodic stripping square wave voltammetry (CSSWV was conducted to quantify Cu sulfides complexes which dissociate at pH < 5.0 during the process of acid titration.

  17. Especiação analítica de compostos de arsênio empregando métodos voltamétricos e polarográficos: uma revisão comparativa de suas principais vantagens e aplicações Speciation analysis of arsenic compounds by voltammetric and polarographic methods: a comparative review of their main advantages and applications

    Directory of Open Access Journals (Sweden)

    Leandro Machado de Carvalho

    2004-04-01

    Full Text Available This paper provides a review on voltammetric and polarographic methods for the speciation analysis of inorganic and organic arsenic compounds in different matrices. A discussion on the main advantages of electroanalytical methods in comparison with other analytical methods employed for arsenic speciation is presented. The mechanistic aspects of the most relevant techniques employing cathodic and anodic stripping voltammetry as well as polarographic methods published in the last twenty five years are summarized and discussed. The bibliographic references cited in this work were selected from the Web of Science (published by the ISI and the main journals of analytical chemistry.

  18. Depletive stripping chronopotentiometry : a major step forward in electrochemical stripping techniques for metal ion speciation analysis

    NARCIS (Netherlands)

    Town, R.M.; Leeuwen, van H.P.

    2004-01-01

    A comparative evaluation of the utility of the various modes of stripping chronopotentiometry (SCP) for trace metal speciation analysis is presented in the broad context of stripping voltammetric techniques. The remarkable fundamental advantages of depletive SCP at scanned deposition potential (SSCP

  19. Modification of carbon screen-printed electrodes by adsorption of chemically synthesized Bi nanoparticles for the voltammetric stripping detection of Zn(II), Cd(II) and Pb(II).

    Science.gov (United States)

    Rico, Ma Angeles Granado; Olivares-Marín, Mara; Gil, Eduardo Pinilla

    2009-12-15

    A simple procedure for the chemical synthesis of bismuth nanoparticles and subsequent adsorption on commercial screen-printed carbon electrodes offer reliable quantitation of trace zinc, cadmium and lead by anodic stripping square-wave voltammetry in nondeareated water samples. The influence of two hydrodynamic configurations (convective cell and flow cell) and the effect of various experimental variables upon the stripping signals at the bismuth-coated sensor are explored. The square-wave peak current signal is linear over the low ng mL(-1) range (120 s deposition), with detections limits ranging from 0.9 to 4.9 ng mL(-1) and good precision. Applicability to waste water certified reference material and drinking water samples is demonstrated. The attractive behaviour of the new disposable Bi nanoparticles modified carbon strip electrodes, coupled with the negligible toxicity of bismuth, hold great promise for decentralized heavy metal testing in environmental and industrial effluents waters.

  20. Aptasensors Based on Stripping Voltammetry

    Directory of Open Access Journals (Sweden)

    Wenjing Qi

    2016-07-01

    Full Text Available Aptasensors based on stripping voltammetry exhibit several advantages, such as high sensitivity and multi-target detection from stripping voltammetric technology, and high selectivity from the specific binding of apamers with targets. This review comprehensively discusses the recent accomplishments in signal amplification strategies based on nanomaterials, such as metal nanoparticles, semiconductor nanoparticles, and nanocomposite materials, which are detected by stripping voltammetry after suitable dissolution. Focus will be put in discussing multiple amplification strategies that are widely applied in aptasensors for small biomolecules, proteins, disease markers, and cancer cells.

  1. Direct determination of tellurium and its redox speciation at the low nanogram level in natural waters by catalytic cathodic stripping voltammetry.

    Science.gov (United States)

    Biver, Marc; Quentel, François; Filella, Montserrat

    2015-11-01

    Tellurium is one of the elements recently identified as technologically critical and is becoming a new emergent contaminant. No reliable method exists for its determination in environmental samples such as natural waters. This gap is filled by the method described here; it allows the rapid detection of trace concentrations of Te(IV) and Te(VI) in surface waters by differential pulse cathodic stripping voltammetry. It is based on the proton reduction catalysed by the absorption of Te(IV) on the mercury electrode. Under our conditions (0.1 mol L(-1) HCl) a detection limit of about 5 ng L(-1) for a deposition time of 300 s is achieved. Organic matter does not represent a problem at low concentrations; higher concentrations are eliminated by adsorptive purification. Tellurium occurs primarily as Te(IV) and Te(VI) in natural waters. Thus, determining total Te requires the reduction of Te(VI) that it is not electroactive. A number of reduction procedures have been carefully evaluated and a method based on the addition of TiCl3 to the acidified samples has been proven to reduce Te(VI) at the trace level to Te(IV) reliably and quantitatively. Therefore, the procedure described allows the direct determination of total Te and its redox speciation. It is flexible, reliable and cost effective compared to any possible alternative method based on the common preconcentration-ICPMS approach. It is readily implementable as a routine method and can be deployed in the field with relative ease.

  2. Application of disorganized monolayer films on gold electrodes to the prevention of surfactant inhibition of the voltammetric detection of trace metals via anodic stripping of underpotential deposits: detection of copper.

    Science.gov (United States)

    Herzog, Grégoire; Arrigan, Damien W M

    2003-01-15

    Development of an approach to prevention of electrode surface fouling by surfactants in samples is demonstrated. Spontaneously adsorbed monolayer systems employing short alkyl chains and bulky end groups are used to form porous disorganized monolayers on gold electrodes. Detection of copper by stripping of underpotential deposits formed at electrodes modified with disorganized films of mercaptoethanesulfonate (MES), mercaptopropanesulfonate, mercaptoacetic acid, and mercaptopropanoic acid was possible, and to a much lesser extent at aminoethanethiol and L-cysteine films. Use of short deposition times in conjunction with linear sweep anodic stripping voltammetry allowed detection of Cu2+ ions down to 1 x 10(-6) M in sulfuric acid solution, using underpotential deposition as the deposition step of the procedure. Calibration graphs were linear in the concentration range (1-80) x 10(-6) M Cu2+ using 15-s deposition at 0.00 V versus Ag/AgCl. The surfactants Tween 20, Tween 80, and Triton X-100 were found to have no affect on detection of Cu2+ ions in the calibration curve concentration range using MES-modified gold electrodes, whereas at unmodified gold electrodes very severe attenuation of the detection capability was manifested. The average slope for all calibration curves at the MES-modified electrode in the absence and presence of the surfactants at two different concentration levels was 0.0710 +/- 0.0024 microA microM(-1); in contrast, the slope of the calibration line at uncoated gold electrodes in the presence of surfactant was 0.0268 microA microM(-1). These results indicate the excellent ability of a disorganized, porous monolayer for prevention of fouling of the electrode surface by the surfactants.

  3. Square wave anodic stripping voltammetric determination of Cd²⁺ and Pb²⁺ at bismuth-film electrode modified with electroreduced graphene oxide-supported thiolated thionine.

    Science.gov (United States)

    Li, Zou; Chen, Li; He, Fang; Bu, Lijuan; Qin, Xiaoli; Xie, Qingji; Yao, Shouzhuo; Tu, Xinman; Luo, Xubiao; Luo, Shenglian

    2014-05-01

    Graphene oxide (GO)-thionine (TH) nanocomposite was prepared by π-π stacking. The nanocomposite was cast-coated on a glassy carbon electrode (GCE) to prepare an electroreduced GO (ERGO)-TH/GCE, then 2-mercaptoethanesulfonate (MES) was covalently tethered to ERGO-TH by potentiostatic anodization to form an ERGO-TH-MES/GCE. The thiolation reaction was monitored by electrochemical quartz crystal microbalance (EQCM). Square wave anodic stripping voltammetry (SWASV) was used to determine Cd(2+) and Pb(2+) at the ERGO-TH-MES/GCE further modified with Nafion and Bi. Under the optimal conditions, the linear calibration curves for Cd(2+) and Pb(2+) are from 1 to 40 μg L(-1), with limits of detection (S/N=3) of 0.1 μg L(-1) for Cd(2+) and 0.05 μg L(-1) for Pb(2+), respectively. The electrode was used for the simultaneous analysis of Cd(2+) and Pb(2+) in water samples with satisfactory recovery.

  4. New approach to the determination of contaminants of emerging concern in natural water: study of alprazolam employing adsorptive cathodic stripping voltammetry.

    Science.gov (United States)

    Nunes, Chalder Nogueira; Pauluk, Lucas Ely; Dos Anjos, Vanessa Egéa; Lopes, Mauro Chierici; Quináia, Sueli Pércio

    2015-08-01

    Contaminants of emerging concern (CECs) are chemicals, including pharmaceutical and personal care products, not commonly monitored in the aquatic environment. Pharmaceuticals are nowadays considered as an important environmental contaminant. Chromatography methods which require expensive equipment and complicated sample pretreatment are used for detection of CECs in natural water. Thus, in this study we proposed a simple, fast, and low-cost voltammetric method as a screening tool for the determination of CECs in natural water prior to chromatography. A case study was conducted with alprazolam (benzodiazepine). The method was optimized and validated in-house. The limit of quantification was 0.4 μg L(-1) for a 120 s preconcentration time. The recoveries ranged from 93 to 120 % for accuracy tests. A further proposal aim was to determine for the first time the occurrence of alprazolam in Brazilian river water and to evaluate its potential use as a marker of contamination by wastewater.

  5. Square-wave anodic-stripping voltammetric determination of Cd, Pb, and Cu in a hydrofluoric acid solution of siliceous spicules of marine sponges (from the Ligurian Sea, Italy, and the Ross Sea, Antarctica)

    Energy Technology Data Exchange (ETDEWEB)

    Truzzi, C.; Annibaldi, A.; Illuminati, S.; Bassotti, E.; Scarponi, G. [Polytechnic University of Marche, Ancona (Italy). Department of Marine Science

    2008-09-15

    Square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for simultaneous determination of cadmium, lead, and copper in siliceous spicules of marine sponges, directly in the hydrofluoric acid solution ({proportional_to}0.55 mol L{sup -1} HF, pH {proportional_to}1.9). A thin mercury-film electrode (TMFE) plated on to an HF-resistant epoxy-impregnated graphite rotating-disc support was used. The optimum experimental conditions, evaluated also in terms of the signal-to-noise ratio, were as follows: deposition potential -1100 mV vs. Ag/AgCl, KCl 3 mol L{sup -1}, deposition time 3-10 min, electrode rotation 3000 rpm, SW scan from -1100 mV to +100 mV, SW pulse amplitude 25 mV, frequency 100 Hz, {delta}E{sub step} 8 mV, t{sub step} 100 ms, t{sub wait} 60 ms, t{sub delay} 2 ms, t{sub meas} 3 ms. Under these conditions the metal peak potentials were Cd -654{+-}1 mV, Pb -458 {+-} 1 mV, Cu -198{+-}1 mV. The electrochemical behaviour was reversible for Pb, quasi-reversible for Cd, and kinetically controlled (possibly following chemical reaction) for Cu. The linearity of the response with concentration was verified up to {proportional_to}4 {mu}g L{sup -1} for Cd and Pb and {proportional_to}20 {mu}g L{sup -1} for Cu. The detection limits were 5.8 ng L{sup -1}, 3.6 ng L{sup -1}, and 4.3 ng L{sup -1} for Cd, Pb, and Cu, respectively, with t{sub d}=5 min. The method was applied for determination of the metals in spicules of two specimens of marine sponges (Demosponges) from the Portofino natural reserve (Ligurian Sea, Italy, Petrosia ficiformis) and Terra Nova Bay (Ross Sea, Antarctica, Sphaerotylus antarcticus). The metal contents varied from tens of ng g{sup -1} to {proportional_to}1 {mu}g g{sup -1}, depending on the metal considered and with significant differences between the two sponge species. (orig.)

  6. A Latent Markov Modelling approach to the evaluation of Circulating Cathodic Antigen strips for Schistosomiasis diagnosis pre- and post-praziquantel treatment in Uganda

    DEFF Research Database (Denmark)

    Koukounari, Artemis; Donnelly, Christl A.; Moustaki, Irini

    2013-01-01

    Markov Models (LMMs). The aim was to evaluate the diagnostic accuracy of Circulating Cathodic Antigen (CCA) and of double Kato-Katz (KK) faecal slides over three consecutive days for Schistosoma mansoni infection simultaneously by age group at baseline and at two follow-up times post treatment...

  7. 基于表面活性剂存在下电化学结合化学计量学同时测定3种着色剂%Simultaneous differential pulse stripping voltammetric determination of three food colorants in presence of CTAB with aid of chemometrics

    Institute of Scientific and Technical Information of China (English)

    钟永生; 桂怿; 倪永年

    2012-01-01

    利用微分脉冲伏安法研究了日落黄、苋菜红和柠檬黄等3种着色剂在裸玻碳电极上的电化学行为及定量分析测定的可行性.实验发现,在表面活性剂溴化十六烷基三甲铵(CTAB,浓度为40.0×10-6 mol·L-1)存在下,3种着色剂日落黄、苋菜红和柠檬黄均具有较高的电化学测定灵敏度,它们的线性范围分别为4.0~40.0,5.0~60.0和2.5~35.0 nmol·L-1,对应的最低检测线分别为1.54,2.38和1.10 nmol·L-1.但这3种被测物质中日落黄和苋菜红的伏安波谱相互重叠,因此在不进行化学分离预处理的情况下很难对这3种着色剂同时进行测定.采用偏最小二乘法、主成分分析以及它们的一阶导数等化学计量学方法对它们的重叠伏安谱图进行解析和定量分析,结果表明,导数偏最小二乘法的计算结果最好,总相对预测误差(RPET)为6.18%.利用提出的方法对冰激凌、汽水和糖果等实际样中的3种着色剂进行直接测定,获得了较好的定量分析结果.%The differential pulse stripping voltammetric (DPSV) method was developed, to determine hree colorants,sunset yellow,amaranth and tartrazine. The method proposed was based on the adsorptive accumulation of the colorants on the carbon electrode,and the oxidation of the absorptive species by the voltam-metry. The 40. 0×10-6 mol · L-1 of cetyltrimethyl ammonium bromide (CTAB) was used as the optimal for the experiment. The linear concentration ranges were found to be 4. 0-40. 0.5. 0-60. 0 and 2. 5-35. 0 nmol · L-1 ,for sunset yellow, amaranth and tartrazine, respectively. Their corresponding detection limits were 1. 54,2. 38 and 1. 10 nmol · L-1. Since the voltammograms of these colorants were seriously overlapped, it was difficult to determine them individually from the voltammetric signals of the mixtures. Thus, some chemometrics methods,such as partial least squares (PLS),principle component regression (PCR) and their first-order derivative

  8. Modified solid electrodes for stripping voltammetric determination of tin

    Energy Technology Data Exchange (ETDEWEB)

    Faller, C. [Kaiserslautern Univ. (Germany). Fachbereich Chemie]|[Univ. Trier (Germany). Abt. Anorganische und Analytische Chemie; Henze, G. [Kaiserslautern Univ. (Germany). Fachbereich Chemie]|[Univ. Trier (Germany). Abt. Anorganische und Analytische Chemie; Stojko, N. [Ural State Economic University, 8th of March Street 62, 620219 Ekaterinburg (Russian Federation); Saraeva, S. [Ural State Economic University, 8th of March Street 62, 620219 Ekaterinburg (Russian Federation); Brainina, K. [Ural State Economic University, 8th of March Street 62, 620219 Ekaterinburg (Russian Federation)

    1997-07-01

    The paper describes the determination of tin by ASV using modified thick film electrodes. Three different types of electrodes were developed: One modified with a mixture of Nafion and mercury(II)acetate, one modified with diethyldithiocarbamate (DDC) or pyrrolidinedithiocarbamate (PDC) and mercury(II)acetate, and one modified with calomel. The analyte was accumulated on the electrode surface after special electrochemical pretreatment of the modified electrode. After recording the voltammogram the electrodes were electrochemically regenerated. By virtue of their lifetime and their measurement reproducibility, we preferred the DDC and PDC modified electrodes. They can be used for months without changing their chemical characteristics. The linear range for tin determination with these electrodes is between 1 and 100 {mu}g/L; the detection limit was calculated as 0.9 {mu}g/L. The electrodes were applied to the direct determination of tin in different canned fruit juices without special sample pretreatment. (orig.). With 10 figs., 4 tabs.

  9. A Latent Markov Modelling Approach to the Evaluation of Circulating Cathodic Antigen Strips for Schistosomiasis Diagnosis Pre- and Post-Praziquantel Treatment in Uganda

    Science.gov (United States)

    Koukounari, Artemis; Donnelly, Christl A.; Moustaki, Irini; Tukahebwa, Edridah M.; Kabatereine, Narcis B.; Wilson, Shona; Webster, Joanne P.; Deelder, André M.; Vennervald, Birgitte J.; van Dam, Govert J.

    2013-01-01

    Regular treatment with praziquantel (PZQ) is the strategy for human schistosomiasis control aiming to prevent morbidity in later life. With the recent resolution on schistosomiasis elimination by the 65th World Health Assembly, appropriate diagnostic tools to inform interventions are keys to their success. We present a discrete Markov chains modelling framework that deals with the longitudinal study design and the measurement error in the diagnostic methods under study. A longitudinal detailed dataset from Uganda, in which one or two doses of PZQ treatment were provided, was analyzed through Latent Markov Models (LMMs). The aim was to evaluate the diagnostic accuracy of Circulating Cathodic Antigen (CCA) and of double Kato-Katz (KK) faecal slides over three consecutive days for Schistosoma mansoni infection simultaneously by age group at baseline and at two follow-up times post treatment. Diagnostic test sensitivities and specificities and the true underlying infection prevalence over time as well as the probabilities of transitions between infected and uninfected states are provided. The estimated transition probability matrices provide parsimonious yet important insights into the re-infection and cure rates in the two age groups. We show that the CCA diagnostic performance remained constant after PZQ treatment and that this test was overall more sensitive but less specific than single-day double KK for the diagnosis of S. mansoni infection. The probability of clearing infection from baseline to 9 weeks was higher among those who received two PZQ doses compared to one PZQ dose for both age groups, with much higher re-infection rates among children compared to adolescents and adults. We recommend LMMs as a useful methodology for monitoring and evaluation and treatment decision research as well as CCA for mapping surveys of S. mansoni infection, although additional diagnostic tools should be incorporated in schistosomiasis elimination programs. PMID:24367250

  10. A latent Markov modelling approach to the evaluation of circulating cathodic antigen strips for schistosomiasis diagnosis pre- and post-praziquantel treatment in Uganda.

    Directory of Open Access Journals (Sweden)

    Artemis Koukounari

    Full Text Available Regular treatment with praziquantel (PZQ is the strategy for human schistosomiasis control aiming to prevent morbidity in later life. With the recent resolution on schistosomiasis elimination by the 65th World Health Assembly, appropriate diagnostic tools to inform interventions are keys to their success. We present a discrete Markov chains modelling framework that deals with the longitudinal study design and the measurement error in the diagnostic methods under study. A longitudinal detailed dataset from Uganda, in which one or two doses of PZQ treatment were provided, was analyzed through Latent Markov Models (LMMs. The aim was to evaluate the diagnostic accuracy of Circulating Cathodic Antigen (CCA and of double Kato-Katz (KK faecal slides over three consecutive days for Schistosoma mansoni infection simultaneously by age group at baseline and at two follow-up times post treatment. Diagnostic test sensitivities and specificities and the true underlying infection prevalence over time as well as the probabilities of transitions between infected and uninfected states are provided. The estimated transition probability matrices provide parsimonious yet important insights into the re-infection and cure rates in the two age groups. We show that the CCA diagnostic performance remained constant after PZQ treatment and that this test was overall more sensitive but less specific than single-day double KK for the diagnosis of S. mansoni infection. The probability of clearing infection from baseline to 9 weeks was higher among those who received two PZQ doses compared to one PZQ dose for both age groups, with much higher re-infection rates among children compared to adolescents and adults. We recommend LMMs as a useful methodology for monitoring and evaluation and treatment decision research as well as CCA for mapping surveys of S. mansoni infection, although additional diagnostic tools should be incorporated in schistosomiasis elimination programs.

  11. High current density cathode for electrorefining in molten electrolyte

    Science.gov (United States)

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  12. Voltammetric determination of Se(IV) and Se(VI) in saline samples-Studies with seawater, hydrothermal and hemodialysis fluids

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Paulo C. do, E-mail: npaulo@quimica.ufsm.br [Departamento de Quimica, Universidade Federal de Santa Maria, C.P. 5051, 97105-970 Santa Maria, RS (Brazil); Jost, Cristiane L.; Carvalho, Leandro M. de; Bohrer, Denise [Departamento de Quimica, Universidade Federal de Santa Maria, C.P. 5051, 97105-970 Santa Maria, RS (Brazil); Koschinsky, Andrea [School of Engineering and Science, Geosciences and Astrophysics, Jacobs University Bremen GmbH, P.O. Box 750561, D-28725 Bremen (Germany)

    2009-08-26

    Determination of Se(IV) and Se(VI) in high saline media was investigated by cathodic stripping voltammetry (CSV). The voltammetric method was applied to assay selenium in seawater, hydrothermal and hemodialysis fluids. The influence of ionic strength on selenium determination is discussed. The CSV method was based on the co-electrodeposition of Se(IV) with Cu(II) ions and Se(VI) determined by difference after sample UV-irradiation for photolytic selenium reduction. UV-irradiation was also used as sample pre-treatment for organic matter decomposition. Detection limit of 0.030 {mu}g L{sup -1} (240 s deposition time) and relative standard deviation (RSD) of 6.19% (n = 5) for 5.0 {mu}g L{sup -1} of Se(IV) were calculated. Linear calibration range for selenium was observed from 1.0 to 100.0 {mu}g L{sup -1}. Concerning the pre-treatment step, best results were obtained by using 60 min UV-irradiation interval in H{sub 2}O{sub 2}/HCl medium. Se(VI) was reduced to the Se(IV) electroactive species with recoveries between 91.7% and 112.9%. Interferents were also investigated.

  13. Square-Wave Voltammetric Determination of Sulpiride

    OpenAIRE

    1999-01-01

    The basic redox properties of sulpiride are investigated by means of cyclic voltammetry and square-wave voltammetryat a hanging mercury drop electrode. Sulpiride undergoes electrochemical reaction in basic media. The voltammetric response of sulpiride strongly depends on pH of the medium. A square-wave method for quantitative determination of sukpiride was developed.

  14. Cathodic arcs

    OpenAIRE

    Anders, Andre

    2003-01-01

    Cathodic arc plasma deposition has become the technology of choice for hard, wear and corrosion resistant coatings for a variety of applications. The history, basic physics of cathodic arc operation, the infamous macroparticle problem and common filter solutions, and emerging high-tech applications are briefly reviewed. Cathodic arc plasmas stand out due to their high degree of ionization, with important consequences for film nucleation, growth, and efficient utilization of substrate bia...

  15. Voltammetric Investigation Of Hydrothermal Iron Speciation

    Directory of Open Access Journals (Sweden)

    Charlotte eKleint

    2016-05-01

    Full Text Available Hydrothermal vent fluids are highly enriched in iron (Fe compared to ambient seawater, and organic ligands may play a role in facilitating the transport of some hydrothermal Fe into the open ocean. This is important since Fe is a limiting micronutrient for primary production in large parts of the world`s surface ocean. We have investigated the concentration and speciation of Fe in several vent fluid and plume samples from the Nifonea vent field, Coriolis Troughs, New Hebrides Island Arc, South Pacific Ocean using competitive ligand exchange - adsorptive cathodic stripping voltammetry (CLE - AdCSV with salicylaldoxime (SA as the artificial ligand. Our results for total dissolved Fe (dFe in the buoyant hydrothermal plume samples showed concentrations up to 3.86 µM dFe with only a small fraction between 1.1% and 11.8% being chemically labile. Iron binding ligand concentrations ([L] were found in µM level with strong conditional stability constants up to log K[L],Fe3+ of 22.9. Within the non-buoyant hydrothermal plume above the Nifonea vent field, up to 84.7% of the available Fe is chemically labile and [L] concentrations up to 97 nM were measured. [L] was consistently in excess of Felab, indicating that all available Fe is being complexed, which in combination with high Felab values in the non-buoyant plume, signifies that a high fraction of hydrothermal dFe is potentially being transported away from the plume into the surrounding waters, contributing to the global oceanic Fe budget.

  16. Ion-transfer voltammetric determination of folic acid at meso-liquid-liquid interface arrays.

    Science.gov (United States)

    Jiang, Xuheng; Gao, Kui; Hu, Daopan; Wang, Huanhuan; Bian, Shujuan; Chen, Yong

    2015-04-21

    Voltammetric studies on the simple ion transfer (IT) behaviors of an important water-soluble B-vitamin, folic acid (FA), at the liquid-liquid (L-L) interface were firstly performed and then applied as a novel detection method for FA under physiological conditions. Meso-water-1,6-dichlorohexane (W-DCH) and meso-water-organogel interface arrays were built by using a hybrid mesoporous silica membrane (HMSM) with a unique structure of pores-in-pores and employed as the new platforms for the IT voltammetric study. In view of the unique structure of the HMSM, the impact of the ionic surfactant cetyltrimethylammonium bromide (CTAB), self-assembled within the silica nanochannels of the HMSM, was investigated. In particular, its effect on the IT voltammetric behavior and detection of FA at meso-L-L interface arrays was systematically examined by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and differential pulse stripping voltammetry (DPSV). It was found that all the voltammetric responses of CV, DPV, and DPSV and the corresponding detection limit of FA at such meso-L-L interface arrays are closely related to the CTAB in the HMSM. Significantly, the calculated detection limit of FA could be improved to 80 nM after the combination of the DPSV technique with the additional preconcentration of FA in the silica-CTAB nanochannels, achieved through an anion-exchange process between FA(-) and the bromide of CTAB in HMSM. This provides a new and attractive strategy for the detection of those biological anions.

  17. Voltammetric method for the determination of sildenafil citrate (Viagra) in pure form and in pharmaceutical formulations.

    Science.gov (United States)

    Tyszczuk, Katarzyna; Korolczuk, Mieczyslaw

    2010-06-01

    A highly sensitive and simple voltammetric method for the determination of sildenafil citrate (SC) was developed. The method is based on the accumulation by adsorption of SC on a lead film modified glassy carbon electrode (LF/GCE) and then the reduction of SC throughout the stripping step. During the determinations of SC at the lead film electrode three adsorptive stripping voltammetric peaks at -1.2, -1.33 and -1.45V were observed. The respective response selected for identification and quantification has been evaluated with respect to the composition and pH of the supporting electrolyte, the potential and the time of the lead film formation, the potential and the time of the SC accumulation and other variables. Experimental results indicate an excellent linear correlation between the peak current and concentration in the range of 2x10(-9)-1.5x10(-7)mol/L (for peaks 1 and 2) and 1x10(-8)-1.5x10(-7)mol/L (for the peak 3). The detection limits (LOD) for SC following 30s of accumulation time were equal to 9x10(-10)mol/L (for peaks 1 and 2) and 4.5x10(-9)mol/L (for the peak 3). The method was successfully applied to the determination of SC in the tablets (Viagra 25 and Viagra 50) and average the contents were in close agreement with those quoted by the manufacturer and with those obtained by the reported spectrophotometric method and voltammetric method using a hanging mercury drop electrode.

  18. Cathodic pseudopolarography: a new tool for the identification and quantification of cysteine, cystine and other low molecular weight thiols in seawater.

    Science.gov (United States)

    Laglera, Luis M; Downes, Javier; Tovar-Sánchez, Antonio; Monticelli, Damiano

    2014-07-11

    Thiols are compounds of paramount importance in the cellular metabolism due to their double detoxifying role as radical scavengers and trace metal ligands. However, we have scarce information about their extracellular cycling as limited data are available about their concentration, stability and speciation in the aquatic medium. In natural waters, they form part of the pool of reduced sulfur substance (RSS) whose presence has been documented by voltammetric and chromatographic methods. Traditional use of cathodic stripping voltammetry (CSV) for the analysis of RSS could only give an overall concentration due to the coalescence of their CSV peaks. Recently, it has been shown that the use of multiple deposition potentials could take voltammetry of RSS to a higher level, permitting the identification and quantification of the mixtures of RSS despite showing as a single coalescent peak. Here, due to its similarity with classical pseudopolarography, we propose to rename this analytical strategy as cathodic pseudopolarography (CP) and we present for the first time its use for the analysis of mixes of low molecular weight thiols (LMWT) at the nanomolar level. Despite limitations caused by the identical behavior of some LMWT, the CP allowed to isolate the contribution of cysteine and cystine from a coalescent signal in LMWT mixtures. Sample handling with clean protocols allowed the direct determination of the cystine:cysteine ratio without sample modification. Finally, we show the application of CP to identify LMWT in seawater samples extracted from benthic chambers and suggest future applications in other areas of environmental electroanalysis.

  19. Voltammetric Detection of Diquat at the Carbon Paste Electrode Containing a Ca10(PO46(OH2

    Directory of Open Access Journals (Sweden)

    Moulay Abderrahim EL MHAMMEDI

    2007-01-01

    Full Text Available We report a sensitive electrochemical voltammetric method for analyzing diquat (DQ ions using a carbon paste electrochemical (CPE modified by porous material, such as hydroxyapatite (HAP. Diquat strongly adsorbed on a HAP-CPE surface and provides facile electrochemical quantitative methods for electroactive DQ ions. Operational parameters have been optimized, and the stripping voltammetric performance has been studied using square wave voltammetry. The peaks current intensity are highly linear over the 7×10-7–3×10-4 mol L-1 diquat range examined (10-min accumulation time, with a good sensitivity. These findings can lead to a widespread use of electrochemical sensors to detect DQ contaminates.Scanning electron microscopy was used for morphology observation and in particular the X-ray diffraction analysis (XRD and Fourier transformed infrared spectroscopy (FTIR analysis for characterization of synthesis powder.

  20. Cathodic arcs

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2003-10-29

    Cathodic arc plasma deposition has become the technology of choice for hard, wear and corrosion resistant coatings for a variety of applications. The history, basic physics of cathodic arc operation, the infamous macroparticle problem and common filter solutions, and emerging high-tech applications are briefly reviewed. Cathodic arc plasmas standout due to their high degree of ionization, with important consequences for film nucleation, growth, and efficient utilization of substrate bias. Industrial processes often use cathodic arc plasma in reactive mode. In contrast, the science of arcs has focused on the case of vacuum arcs. Future research directions include closing the knowledge gap for reactive mode, large area coating, linear sources and filters, metal plasma immersion process, with application in high-tech and biomedical fields.

  1. Anisotropic etching of platinum electrodes at the onset of cathodic corrosion.

    Science.gov (United States)

    Hersbach, Thomas J P; Yanson, Alexei I; Koper, Marc T M

    2016-08-24

    Cathodic corrosion is a process that etches metal electrodes under cathodic polarization. This process is presumed to occur through anionic metallic reaction intermediates, but the exact nature of these intermediates and the onset potential of their formation is unknown. Here we determine the onset potential of cathodic corrosion on platinum electrodes. Electrodes are characterized electrochemically before and after cathodic polarization in 10 M sodium hydroxide, revealing that changes in the electrode surface start at an electrode potential of -1.3 V versus the normal hydrogen electrode. The value of this onset potential rules out previous hypotheses regarding the nature of cathodic corrosion. Scanning electron microscopy shows the formation of well-defined etch pits with a specific orientation, which match the voltammetric data and indicate a remarkable anisotropy in the cathodic etching process, favouring the creation of (100) sites. Such anisotropy is hypothesized to be due to surface charge-induced adsorption of electrolyte cations.

  2. Penicillamine-modified sensor for the voltammetric determination of Cd(II) and Pb(II) ions in natural samples.

    Science.gov (United States)

    Pérez-Ràfols, Clara; Serrano, Núria; Díaz-Cruz, José Manuel; Ariño, Cristina; Esteban, Miquel

    2015-11-01

    A new penicillamine-GCE was developed based on the immobilization of d-penicillamine on aryl diazonium salt monolayers anchored to the glassy carbon electrode (GCE) surface and it was applied for the first time to the simultaneous determination of Cd(II) and Pb(II) ions by stripping voltammetric techniques. The detection and quantification limits at levels of µg L(-1) suggest that the penicillamine-GCE could be fully suitable for the determination of the considered ions in natural samples.

  3. Microconcentric ring electrode/injector assembly for sensitive voltammetric analysis in single droplets of ultrasmall volumes.

    Science.gov (United States)

    Kai, Tianhan; Chen, Shu; Monterroso, Estuardo; Hailu, Amanuel; Zhou, Feimeng

    2014-08-19

    This paper describes the construction of a microring electrode concentric to an inner injection capillary for voltammetric determination of trace analytes in nanoliter- to picoliter-sized droplets. The gold microring is sandwiched between a pulled fused-silica capillary and borosilicate glass tubing. Compared to polymer-coated microring electrodes, the glass-encapsulated electrode is more robust and does not swell in organic solvents. Consequently, the microring electrode is suitable for voltammetric studies of redox-active species and their accompanying ion transfers between two immiscible solvents. Droplets of variable sizes can be conveniently dispensed from front-loaded sample plugs into an immiscible liquid, greatly simplifying the experimental procedure and facilitating analysis of samples of limited availability. The size of the microring and the volume of the droplet deduced from well-defined voltammograms correlate well with those estimated from their geometric dimensions. The thin-layer cell behavior can be attained with well-defined voltammetric peaks and small capacitive current. Exhaustive electrolysis in single droplets can be accomplished in short times (e.g., ∼85 s in a droplet of 1.42 nL at a microring of 11.4 μm in radius). Anodic stripping voltammetry of Ag deposited onto the microring electrode resulted in a detection limit of 0.13 fmol (14 fg) of Ag(+). The microring electrode/injector assembly can be polished repeatedly and is versatile for various applications (e.g., sample plugs can also be back-loaded via a rotary injection valve and an HPLC pump for flow injection analysis).

  4. Voltammetric determination of imidacloprid and thiamethoxam

    Directory of Open Access Journals (Sweden)

    SZILVIA N. ÖKRÉSZ

    2005-05-01

    Full Text Available A simple voltammetric method using a glassy carbon working electrode was developed for the determination of two members from the neonicotinoid group of insecticides: imidacloprid and thiamethoxam. The experiments showed that the voltammetric response depends on the mode of electrode surface pretreatment and the polarization mode. The response appeared to be linear in the range from 0.028 to 0.50 mg/cm3 for both analytes. The limit of detection was 0.0077 mg/cm3 for imidacloprid and 0.0085 mg/cm3 for thiamethoxam, the limit of quantitation was 0.026 mg/cm3 and 0.028 mg/cm3, respectively. The developed method was applied for the determination of these insecticides in potato samples sprayed with Confidor 200-SL or Actara 25-WG as well as commercial formulations of imidacloprid and thiamethoxam. Arecovery trial was performed to assess the accuracy of the results, the recovery values being between 95–102 % for both of neonicotinoids.

  5. TRACE LEVEL VOLTAMMETRIC DETERMINATION OF HEAVY METALS AND TOTAL MERCURY IN TEA MATRICES (Camellia sinensis).

    Science.gov (United States)

    Melucci, Dora; Locatelli, Marcello; Locatelli, Clinio

    2013-10-24

    An analytical procedure regarding the voltammetric determination of mercury(II), copper(II), lead(II), cadmium(II) and zinc(II) by square wave anodic stripping voltammetry (SWASV) in matrices involved in food chain is proposed. In particular, tea leaves were analysed as real samples. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture; 0.01 mol L(-1) EDTA-Na2 + 0.15 mol L(-1) NaCl + 0.5 mol L(-1) HCl was employed as the supporting electrolyte. The voltammetric measurements were carried out using a conventional three electrode cell, employing, as working electrodes, a gold electrode (GE) and a stationary hanging mercury drop electrode (HMDE). The analytical procedure has been verified on the standard reference materials Spinach Leaves NIST-SRM 1570a, Tomato Leaves NIST-SRM 1573a and Apple Leaves NIST-SRM 1515. For all the elements, the precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3-5 %, while the trueness, expressed as relative error (e) was of the order of 3-7 %. Once set up on the standard reference materials, the analytical procedure was applied to commercial tea leaves samples. A critical comparison with spectroscopic measurements is also discussed.

  6. Evaluation of antimony microparticles supported on biochar for application in the voltammetric determination of paraquat.

    Science.gov (United States)

    Gevaerd, Ava; de Oliveira, Paulo R; Mangrich, Antonio S; Bergamini, Márcio F; Marcolino-Junior, Luiz H

    2016-05-01

    This work describes the construction and application of carbon paste electrodes modified with biochar and antimony microparticles (SbBCPE) for voltammetric determination of paraquat using a simple and sensitive procedure based on voltammetric stripping analysis. Some parameters such as amount of biochar and antimony used in the composition of the carbon paste and instrumental parameters were examined in detail. Under optimized conditions, an analytical curve was obtained for paraquat determination employing SbBCPE, which showed a linear response ranging from 0.2 to 2.9 μmol L(-1), with limit of detection and quantification of 34 nmol L(-1) and 113 nmol L(-1), respectively, after paraquat pre-concentration of 120 s. The repeatability study presented a RSD=2.0% for 10 consecutive measurements using the same electrode surface and the reproducibility study showed a RSD=2.7% for measurements with 10 different electrode surfaces. The proposed sensor was successfully applied for paraquat determination in tap water and citric fruit juice spiked samples and good recoveries were obtained without any sample pre-treatment, showing its promising analytical performance.

  7. Electrochemistry and determination of cefdinir by voltammetric and computational approaches

    Directory of Open Access Journals (Sweden)

    İbrahim Hüdai Taşdemir

    2014-12-01

    Full Text Available The oxidation and reduction behavior of cefdinir (CEF was studied by experimental methods and computational calculations at B3LYP/6-31+G (d//AM1. Voltammetric studies were carried out based on two irreversible reduction peaks at approximately −0.5 and −1.2 V on a hanging mercury drop electrode (HMDE and on one irreversible oxidation peak at approximately 1.0 V on a glassy carbon electrode (GCE versus Ag/AgCl, KCl (3.0M in Britton–Robinson (BR buffer at pH 4.2 and 5.0, respectively. Differential pulse adsorptive stripping voltammetric methods have been developed and validated for determination of CEF in different samples. The linear range was established as 0.25–40.0 μM for HMDE and 0.40–10.0 μM for GCE. Limit of quantification was calculated to be 0.20 and 0.26 μM for HMDE and GCE, respectively. These methods were successfully applied to assay the drug in tablets and human serum with good recoveries between 92.7% and 107.3% having relative standard deviation less than 10%.

  8. Voltammetric copper(II) determination with a montmorillonite-modified carbon paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kula, P. [Institute of Geonics, Academy of Sciences of Czech Republic, Studertska 1768, 708 00 Ostrava (Czech Republic); Navratilova, Z. [Institute of Geonics, Academy of Sciences of Czech Republic, Studertska 1768, 708 00 Ostrava (Czech Republic)

    1996-03-01

    The clay mineral montmorillonite has been tested as modifier for the carbon paste electrode with a novel electrode modification technique. The differential pulse voltammetric determination of copper(II) by means of this modified carbon paste electrode has been studied. A detection limit of 4 x 10{sup -8} mol/l has been achieved after 10 min preconcentration under open circuit conditions with subsequent anodic stripping voltammetry. The calibration curve for Cu(II) is linear in the range of 4 x 10{sup -8}-8 x 10{sup -7} mol/l. Pb interferes in a 10-fold molar and Cd and Hg in a 100-fold molar excess. The interference by humic ligands is significant. (orig.). With 5 figs., 1 tab.

  9. Use of a modified, high-sensitivity, anodic stripping voltammetry method for determination of zinc speciation in the North Atlantic Ocean.

    Science.gov (United States)

    Jakuba, Rachel Wisniewski; Moffett, James W; Saito, Mak A

    2008-05-05

    Zinc speciation is considered to be an important determinant of the biological availability of zinc. Yet in oceanic surface waters, characterization of zinc speciation is difficult due to the low concentrations of this essential micronutrient. In this study, an anodic stripping voltammetry method previously developed for the total determination of cadmium and lead was successfully adapted to the measurement of zinc speciation. The method differs from previous zinc speciation anodic stripping voltammetry methods in that a fresh mercury film is plated with each sample aliquot. The fresh film anodic stripping voltammetry method was compared to competitive ligand exchange cathodic stripping voltammetry in a profile from the North Atlantic Ocean. Results using the fresh film anodic stripping voltammetry method were similar to those determined using the cathodic stripping voltammetry method, though ligand concentrations determined by fresh film anodic stripping voltammetry were generally slightly higher than those determined by cathodic stripping voltammetry. There did not seem to be a systematic difference between methods for the estimates of conditional stability constants. The ligand concentration in the North Atlantic profile ranged from 0.9 to 1.5 nmol L(-1) as determined by fresh film anodic stripping voltammetry and 0.6 to 1.3 nmol L(-1) as determined by cathodic stripping voltammetry. The conditional stability constants determined by fresh film anodic stripping voltammetry were 10(9.8)-10(10.5) and by cathodic stripping voltammetry were 10(9.8)-10(11.3).

  10. Cyclic Voltammetric Responses of Nitrate Reductase on Chemical Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    YaRuSONG; HuiBoSHAO; 等

    2002-01-01

    Electrochemistry of nitrate reductases (NR) incorporated into 2-aminoethanethiol self-assembled on the gold electrode and polyacrylamide cast on the pyrolytic graphite electrode was examined. NR on chemical modified electrode showed electrochemical cyclic voltammetric responses in phosphate buffers.

  11. Overlapping voltammetric peaks - an analytical procedure for simultaneous determination of trace metals. Application to food and environmental matrices

    Energy Technology Data Exchange (ETDEWEB)

    Locatelli, Clinio [University of Bologna, Department of Chemistry, G. Ciamician, Bologna (Italy); University of Bologna, CIRSA (Centro Interdipartimentale di Ricerca per le Scienze Ambientali - Interdepartment Centre for Research in Environmental Sciences), Laboratory of Environmental Analytical Chemistry, Ravenna (Italy)

    2005-03-01

    Voltammetric methods are very suitable, versatile and rapid techniques for simultaneous determination of metals in complex matrices. The present work, determination of Cu(II), Sn(II), Sb(III), Tl(I), and Pb(II) by square-wave anodic-stripping voltammetry and Cr(VI) by square-wave adsorptive-stripping voltammetry, is an interesting example of the possibility of simultaneous determination of each single element in food and environmental samples, even in the presence of reciprocal interference. Dibasic ammonium citrate, pH 6.3 or 8.2, was employed as supporting electrolyte. The voltammetric measurements were carried out using a stationary hanging mercury drop electrode as working electrode and a platinum electrode and an AgAgClKCl{sub sat} electrode as auxiliary and reference electrodes, respectively. The analytical procedure was verified by analysis of standard reference materials - wholemeal BCR-CRM 189, wheat flour NIST-SRM 1567a, rice flour NIST-SRM 1568a, estuarine sediment BCR-CRM 277, river sediment BCR-CRM 320, and Montana soil with moderately elevated traces NIST-SRM 2711. Precision and accuracy, expressed as relative standard deviation and relative error, respectively, were generally below 6% whereas limits of detection for each element were below 0.069 {mu}g g{sup -1}. In the presence of reciprocal interference the standard addition method considerably improved the resolution of the voltammetric technique, even for very high element concentration ratios. After being set up on the standard reference materials the analytical procedure was transferred and applied to commercial samples of meal and soil samples taken from sites devoted to agricultural practice. A critical comparison with graphite furnace atomic-absorption spectroscopy is also discussed. (orig.)

  12. Voltammetric behaviour of oligonucleotide lipoplexes adsorbed onto glassy carbon electrodes

    OpenAIRE

    Piedade, J. A. P.; M. Mano; Lima, M. C. Pedroso de; Oretskaya, T S; Oliveira-Brett, A. M.

    2004-01-01

    The voltammetric behaviour of oligonucleotide lipoplexes (ODN-lipoplexes) prepared from short oligodeoxynucleotides (ODN), with different base compositions, and liposomes of the cationic lipid DOTAP, was studied by differential pulse voltammetry with a glassy carbon mini-electrode. It was found that the ODN base composition influences the ODN-lipoplex voltammetric response. Differential pulse voltammograms for ODN-lipoplexes of the ODN adenosine nucleotides present two different features when...

  13. Determination of cobalt and nickel in biological materials using catalytic adsorptive stripping voltammetry

    OpenAIRE

    Bobrowski, Andrzej; Zarębski, Jerzy; Królicka, Agnieszka

    2012-01-01

    The paper discusses the utilisation of the catalytic adsorptive stripping voltammetric method for the simultaneous determination of Co and Ni in biological materials such as hair, oyster tissue, bovine liver and oriental tobacco leaves. For this purpose the most sensitive and selective catalytic-adsorptive system with nioxime and nitrite has been selected. The optimal parameters, including concentration of the supporting electrolyte, pH and accumulation time and potential, have be...

  14. Adsorption of pyrantel pamoate on mercury from aqueous solutions: studies by stripping voltammetry.

    Science.gov (United States)

    Gupta, Vinod K; Jain, Rajeev; Jadon, N; Radhapyari, K

    2010-10-01

    Adsorption and electrochemical reduction of pyrantel pamoate are studied in Britton Robinson buffer medium at hanging mercury drop electrode (HMDE) by Adsorptive Stripping Voltammetric technique. The peak current shows a linear dependence with the drug concentration over the range 250 ng mL(-1) to 64 microg mL(-1). Applicability to assay the drug in urine samples is illustrated in the concentration range 5-20 microg mL(-1).

  15. Varicose vein stripping

    Science.gov (United States)

    ... vein stripping; Venous reflux - vein stripping; Venous ulcer - veins Images Circulatory system References American Family Physician. Management of varicose veins. www.aafp.org/afp/2008/1201/p1289.html . ...

  16. Effect of concentration of lithium ions on the voltammetric responses of nitro-substituted aromatic sulfides in dimethylformamide on glassy carbon electrodes

    Science.gov (United States)

    Chellammal, S.; Noel, M.; Anantharaman, P. N.

    Lithium salts are used as supporting electrolytes and ion-pair forming reagents during voltammetric investigations in aprotic solvents. In the present work, these ions are found to have a significant influence on the voltammetric responses of aromatic sulfides in dimethylformamide given their concentration and the cathodic potential limits applied. At very low concentrations (reduction of nitro groups on the electrode surface. This is the conventional lithium ion-pair formation effect reported in the literature. With increasing lithium ion concentration and increasing cathodic limit, the ion-pairs tend to form an insoluble salt film on the electrode surface. This leads to inhibition of further electron transfer. The inhibiting effect does not seem to correlate with the size of the reactant organic molecule involved. At cathodic potential limits exceeding - 2 V, lithium ions appear to undergo direct reduction and subsequent reaction with trace levels of water in the solvent to produce a passive LiOH layer. This inhibits all further electron transfer.

  17. The Voltammetric Analysis of Selenium Electrodeposition from H2SeO3 Solution on Gold Electrode

    Directory of Open Access Journals (Sweden)

    Kowalik R.

    2015-04-01

    Full Text Available The different voltammetry techniques were applied to understand the process of selenium deposition from sulfate solution on gold polycrystalline electrode. By applying the cycling voltammetry with different scan limits as well as the chronoamper-ometry combined with the cathodic and anodic linear stripping voltammetry, the different stages of the deposition of selenium were revealed. It was found that the process of reduction of selenous acid on gold surface exhibits a multistage character. The cyclic voltammetry results showed four cathodic peaks which are related to the surface limited phenomena and which coincide with the bulk deposition process. The fifth cathodic peak is related to the reduction of bulk deposited Se0 to Se-2 ions. Furthermore, the connection of anodic peaks with cathodic ones confirmed the surface limited process of selenium deposition, bulk deposition and reduction to Se-2. Additionally, the cathodic linear stripping voltammetry confirms the process of H2SeO3 adsorption on gold surface. The experiments confirmed that classical voltammetry technique proved to be a very powerful tool for analyzing the electrochemical processes related with interfacial phenomena and electrodeposition.

  18. Voltammetric detection of As(III) with Porphyridium cruentum based modified carbon paste electrode biosensor.

    Science.gov (United States)

    Zaib, M; Saeed, A; Hussain, I; Athar, M M; Iqbal, M

    2014-12-15

    A novel biosensor based on carbon paste electrode modified with Porphyridium cruentum biomass was developed for the determination of As(III) in contaminated water. As(III) was first biosorbed-accumulated on the electrode surface at open circuit potential and then stripped off by applying anodic scan range of -0.8 to +0.8 V using differential pulse anodic stripping voltammetric technique. The best result was obtained at pH 6.0 with 0.1M HNO3 solution as stripping medium, allowing biosorption-accumulation time of 8 min using 5% P. cruentum biomass in graphite-mineral oil paste. Linear range for As(III) detection with the modified electrode-biosensor was observed between 2.5 and 20 µg L(-1). The FTIR spectrum of P. cruentum biomass confirmed the presence of active functional groups that participate in the binding of As(III). Scanning Electron Microscopy (SEM) indulged the surface morphology of modified electrode-biosensor before and after As(III) adsorption. Similarly, Atomic Force Microscopy (AFM) showed that the average roughness of the modified electrode decreased indicating the successful incorporation of P. cruentum biomass. Efficiency of the biosensor in the presence of different interfering metal (Na(+), K(+), Ca(2+), and Mg(2+)) ions were also evaluated. The application of P. cruentum modified biosensor was successfully used for the detection of As(III) in the binary metal (Fe(3+), Mn(2+), Cd(2+), Cu(2+), Ni(2+), Hg(2+), and Pb(2+)) contaminated system. The accuracy of application of biosorption based biosensor for the detection of As(III) is as low as 2.5 µg L(-1).

  19. Adsorptive stripping voltammetric study of vitamin B1 at multi-walled carbon nanotube paste electrode

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar Brahman

    2016-11-01

    The reduction peak current varies linearly with the concentration of vitamin B1 over the range of 1.0 × 10−7–1.0 × 10−6 M. The limits of detection and quantification of the pure drug are 1.1 × 10−10 M and 2.0 × 10−9 M, with the correlation coefficient, r = 0.997 and the relative standard deviation, RSD = 1.2% (n = 5. Experimental results reveal that the MWCNTPE has advantages of small background current, high signal to background current ratio and good reproducibility.

  20. Microscopic and voltammetric properties of lustrous bismuth deposits

    OpenAIRE

    Krolicka, Agnieszka; Bobrowski, Andrzej; Pamuła, Elżbieta

    2010-01-01

    A comparison of lustrous bismuth films, plated at glassy carbon, platinum and gold supports, is presented. The voltammetric performance of preplated bismuth film electrodes was tested using 50 μg/L In(III) and 50 μg/L Pb(II) solutions in 0.1 M acetic buffer in square wave and differential pulse modes. The influence of support material, plating solution concentration and storing conditions on the voltammetric response of BiFEs is discussed. The results of microscopic examination...

  1. A novel voltammetric sensor for citalopram based on multiwall carbon nanotube/(poly(p-aminobenzene sulfonic acid)/β-cyclodextrin)

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad-Bagher, E-mail: mbgholivand2013@gmail.com; Akbari, Arezoo

    2016-05-01

    Multi-walled carbon nanotube (MWCNTS) coated with poly p-aminobenzene sulfonic acid/β-cyclodextrin (p-ABSA/β-CD) film was used as an effective strategy for modification of the surface of glassy carbon electrode (GCE). Electrochemical study and determination of citalopram (CT) were investigated at the p (p-ABSA)/β-CD/MWCNT/GC using cyclic and differential pulse anodic stripping voltammetric techniques. The results indicate that the p (p-ABSA)/β-CD/MWCNT/GC significantly enhanced the oxidation peak current of CT. The modified electrode was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy(SEM) and cyclic voltammetry (CV).The fabricated electrochemical sensor exhibits a fast and reversible linear response toward CT within the concentration ranges of 90 nM–1 μM, 1–11 μM and 11–100 μM with correlation coefficients greater than 0.99 and detection limit of 44 nM. The resulting functionalized polymer film features interesting electrochemical properties such good recovery, reproducibility and selectivity toward CT. The applicability of the proposed sensor was tested by determination of CT in pharmaceutical combinations and human body fluids. - Highlights: • A novel voltammetric sensor for CT based on p (p-ABSA)/β-CD/MWCNT/GC • Electrochemical study of CT was investigated using CV and DPASV techniques. • This sensor is made easy with good sensitivity and reproducibility. • The method was developed in real sample in the presence of matrix effect.

  2. Anatomy Comic Strips

    Science.gov (United States)

    Park, Jin Seo; Kim, Dae Hyun; Chung, Min Suk

    2011-01-01

    Comics are powerful visual messages that convey immediate visceral meaning in ways that conventional texts often cannot. This article's authors created comic strips to teach anatomy more interestingly and effectively. Four-frame comic strips were conceptualized from a set of anatomy-related humorous stories gathered from the authors' collective…

  3. Science Comic Strips

    Science.gov (United States)

    Kim, Dae Hyun; Jang, Hae Gwon; Shin, Dong Sun; Kim, Sun-Ja; Yoo, Chang Young; Chung, Min Suk

    2012-01-01

    Science comic strips entitled Dr. Scifun were planned to promote science jobs and studies among professionals (scientists, graduate and undergraduate students) and children. To this end, the authors collected intriguing science stories as the basis of scenarios, and drew four-cut comic strips, first on paper and subsequently as computer files.…

  4. Determination of platinum-group metals and lead in vegetable environmental bio-monitors by voltammetric and spectroscopic techniques: critical comparison.

    Science.gov (United States)

    Locatelli, Clinio; Melucci, Dora; Torsi, Giancarlo

    2005-08-01

    This paper reports voltammetric sequential determination of Pt(II), Pd(II), and Rh(III), by square-wave adsorption stripping voltammetry (SWAdSV), and Pb(II), by square-wave anodic stripping voltammetry (SWASV), in vegetable environmental matrices. Analytical procedures were verified by the analysis of the standard reference materials: Olive Leaves BCR-CRM 062 and Tomato Leaves NIST-SRM 1573a. Precision and accuracy, expressed as relative standard deviation and relative error, respectively, were always less than 6% and the limits of detection (LOD) for each element were below 0.096 mug g(-1). Once set up on the standard reference materials, the analytical procedure was transferred and applied to laurel leaves sampled in proximity to a superhighway and in the Po river mouth area. A critical comparison with spectroscopic measurements is discussed.

  5. The Strip Module

    DEFF Research Database (Denmark)

    Pedersen, Tommy

    1996-01-01

    When the behaviour of a ship in waves is to be predicted it is convenient to have a tool which includes different approaches to the problem.The aim of this project is to develop such a tool named the strip theory module. The strip theory module will consist of submodules dependent on the I....... At last a postprocessor will be included with facilities for statistical calculations and for plots and prints of the results.The project is divided into 7 tasks where the third is to be completed.This report has two aims. To give an introduction to the project of developing a strip theory module...

  6. Stripping with dry ice

    Science.gov (United States)

    Malavallon, Olivier

    1995-04-01

    Mechanical-type stripping using dry ice (solid CO2) consists in blasting particles of dry ice onto the painted surface. This surface can be used alone or in duplex according to type of substrate to be treated. According to operating conditions, three physical mechanisms may be involved when blasting dry ice particles onto a paint system: thermal shock, differential thermal contraction, and mechanical shock. The blast nozzle, nozzle travel speed, blast angle, stripping distance, and compressed air pressure and media flow rate influence the stripping quality and the uniformity and efficiency obtained.

  7. Centri-voltammetric study with amberlite XAD-7 resin as a carrier system.

    Science.gov (United States)

    Anik Kirgöz, Ulkü; Tural, Hüseyin; Nil Ertaş, F

    2005-01-15

    Centri-voltammetry is a novel method, which allows combining the advantages of centrifugation and voltammetry. The method offers a practical way for application of coprecipitation in trace analysis allowing direct voltammetric scan hence prevents the loss of the analyte, which usually is the case for other preconcentration techniques. The performance of the method was successfully tested using trace amounts of Pb(2+) ions in aqueous solution in a vessel specially designed to be compatible to both centrifugation and voltammetry. XAD-7 resin was used as the carrier material and the parameters related to the carrier material and medium characteristics as well as the centrifugation settings were investigated. The sensitivity of the method was found comparable to that of stripping techniques and the detection limit for lead ions was calculated as 5.2 x 10(-9)M with mercury coated gold sphere electrode. The precision of the method depends on the configuration of the working electrode and better reproducibility was obtained with mercury coated plate electrodes (R.S.D. 3.3%, n = 6).

  8. Voltammetric estimation of the content of antibiotics in veterinary preparations

    Directory of Open Access Journals (Sweden)

    Slepchenko Galina

    2016-01-01

    Full Text Available The voltammetric method for determination of tylosin tartrate, gentamicin sulfate, and cefalexin in veterinary preparations was for the first time developed. Electrochemical behavior of these antibiotics on the mercury film electrode was studied, and the working conditions (background electrolyte, deposition potential were defined for getting analytical signals using the voltammetry. The methods of real objects preparation for determination of tylosin tartrate, gentamicin sulfate, and cefalexin were offered. The techniques for the voltammetric determination of antibiotics in the veterinary preparations may be used in cefalexin ranging from 0.1 to 2.0 g/dm3, tylosin tartrate in the range from 0.1 to 1.7 g/dm3, and gentamicin sulfate from 0.1 to 1.5 g/dm3 (Sr is not more than 25 %

  9. Anodic stripping voltammetry enhancement by redox magnetohydrodynamics.

    Science.gov (United States)

    Clark, Emily A; Fritsch, Ingrid

    2004-04-15

    The effect of an external magnetic field on linear scan anodic stripping voltammetry (ASV) in solutions of 10(-6)-10(-7) M concentrations of lead, cadmium, and copper at mercury films on glassy carbon electrodes has been investigated. A high concentration of Hg(2+) was added to the analyte solution to induce a large cathodic current during the deposition step. Therefore, a large Lorentz force from the net flux of charge through the magnetic field resulted in convection due to magnetohydrodynamics. The faster delivery of analytes to the mercury film electrode during deposition caused an increase in the anodic stripping peaks. The effect of varying Hg(2+) concentrations (0-60 mM) and magnetic field strengths (0-1.77 T) on the enhancement of the stripping peaks was investigated. Enhancements as large as 129% for peak currents and 167% for peak areas were observed. An enhancement of approximately 100% was observed when 60 mM Fe(3+) replaced high concentrations of Hg(2+). This method of convection exhibits promise for small-volume ASV analysis with possible improved limits of detection and decreased preconcentration times.

  10. Cyclopentanone thiosemicarbazone, a new complexing agent for copper determination in biological samples by adsorptive stripping voltammetry.

    Science.gov (United States)

    Mahajan, Rakesh Kumar; Walia, T P S; Sumanjit; Lobana, T S

    2006-03-01

    A selective and sensitive stripping voltammetric method for the determination of trace amounts of copper(II) with cyclopentanone thiosemicarbazone (CPTSC) is presented. The method is based on the adsorptive accumulation of the resulting copper-CPTSC complex on a hanging mercury drop electrode, followed by the stripping voltammetric measurements at the reduction current of the adsorbed complex at -0.37 V vs. Ag/AgCl. The optimal conditions for the stripping analysis of copper include pH 9.3, deposition time of 120 s, and a deposition potential of -0.1 V (vs. Ag/AgCl). The peak current is linearly proportional to the copper concentration over a range 3.14 x 10(-9) M to 1.57 x 10(-6) M with a limit of detection of 1.57 x 10(-9) M. The technique has been applied to the determination of copper in biological samples, like urine and whole blood.

  11. Voltammetric estimation of the content of antibiotics in veterinary preparations

    OpenAIRE

    2016-01-01

    The voltammetric method for determination of tylosin tartrate, gentamicin sulfate, and cefalexin in veterinary preparations was for the first time developed. Electrochemical behavior of these antibiotics on the mercury film electrode was studied, and the working conditions (background electrolyte, deposition potential) were defined for getting analytical signals using the voltammetry. The methods of real objects preparation for determination of tylosin tartrate, gentamicin sulfate, and cefale...

  12. Technical updates to basic proteins focalization using IPG strips

    Directory of Open Access Journals (Sweden)

    Dépagne Jordane

    2012-09-01

    Full Text Available Abstract Background Gel-based proteomic is a popular and versatile method of global protein separation and quantification. However, separation of basic protein still represents technical challenges with recurrent problems of resolution and reproducibility. Results Three different protocols of protein loading were compared using MCF7 cells proteins. In-gel rehydration, cup-loading and paper-bridge loading were first compared using 6–11 IPG strips, as attempted, in-gel rehydration gave large horizontal steaking; paper-bridge loading displayed an interesting spot resolution, but with a predominant loss of material; cup-loading was selected as the most relevant method, but still needing improvement. Twelve cup-loading protocols were compared with various strip rehydration, and cathodic wick solutions. Destreak appeared as better than DTT for strip rehydration; the use of isopropanol gave no improvement. The best 2DE separation was observed with cathodic wicks filled with rehydration solution complemented with DTT. Paper-bridge loading was finally analyzed using non-limited samples, such as bovine milk. In this case, new spots of basic milk proteins were observed, with or without paper wicks. Conclusion According to this technical study of basic protein focalization with IPG strips, the cup-loading protocol clearly displayed the best resolution and reproducibility: strips were first rehydrated with standard solution, then proteins were cup-loaded with destreak reagent, and focalisation was performed with cathodic wicks filled with rehydration solution and DTT. Paper-bridge loading could be as well used, but preferentially with non-limited samples.

  13. Planar-Focusing Cathodes

    CERN Document Server

    Lewellen, J W

    2005-01-01

    Conventional pi-mode rf photoinjectors typically use magnetic solenoids for emittance compensation. This provides independent focusing strength, but can complicate rf power feed placement, introduce asymmetries (due to coil crossovers), and greatly increase the cost of the photoinjector. Cathode-region focusing can also provide for a form of emittance compensation. Typically this method strongly couples focusing strength to the field gradient on the cathode, however, and also requires altering the longitudinal position of the cathode to change the focusing. We propose a new method for achieving cathode-region variable-strength focusing for emittance compensation. The new method reduces the coupling to the gradient on the cathode, and does not require a change in the longitudinal position of the cathode. Expected performance for an S-band system is similar to conventional solenoid-based designs. This paper presents the results of rf cavity and beam dynamics simulations of the new design.

  14. Cathodic Protection Model Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Performs Navy design and engineering of ship and submarine impressed current cathodic protection (ICCP) systems for underwater hull corrosion control and...

  15. micro strip gas chamber

    CERN Multimedia

    1998-01-01

    About 16 000 Micro Strip Gas Chambers like this one will be used in the CMS tracking detector. They will measure the tracks of charged particles to a hundredth of a millimetre precision in the region near the collision point where the density of particles is very high. Each chamber is filled with a gas mixture of argon and dimethyl ether. Charged particles passing through ionise the gas, knocking out electrons which are collected on the aluminium strips visible under the microscope. Such detectors are being used in radiography. They give higher resolution imaging and reduce the required dose of radiation.

  16. [Post-stripping telangiectasis].

    Science.gov (United States)

    Hutinel, B; Maraval, M

    1985-01-01

    These telangiectasia appear between one and six months after the operation, especially in cases of capillary fragility. The most common localizations are the antero-internal and external sides of the thighs and knees. Unnecessary strippings, of continent saphenous veins, are the most frequent cause of these. Their prevention consists of the least possible traumatising stripping, using a fine stripper, a very rigorous post-operative support, and the wearing of light varicose stockings or tights for between one and three months. The treatment using microsclerosis, often delicate, should not be undertaken before six months.

  17. Electrochemical Quartz Crystal Microbalance Monitoring of the Cyclic Voltammetric Deposition of Polyaniline

    Science.gov (United States)

    Xie, Qingji; Li, Zhili; Deng, Chunyan; Liu, Meiling; Zhang, Youyu; Ma, Ming; Xia, Shaoxi; Xiao, Xiaoming; Yin, Dulin; Yao, Shouzhuo

    2007-01-01

    A real-time, labeled-free and nanogram-sensitive mass sensor, electrochemical quartz crystal microbalance (EQCM) is used to monitor a cyclic voltammetric deposition of polyaniline (PANI). The results determined that the efficiency for PANI deposition and the anion-doping ratio is calculated in one single cyclic voltammetric.

  18. ALICE Silicon Strip Detector

    CERN Multimedia

    Nooren, G

    2013-01-01

    The Silicon Strip Detector (SSD) constitutes the two outermost layers of the Inner Tracking System (ITS) of the ALICE Experiment. The SSD plays a crucial role in the tracking of the particles produced in the collisions connecting the tracks from the external detectors (Time Projection Chamber) to the ITS. The SSD also contributes to the particle identification through the measurement of their energy loss.

  19. Voltammetric detection of biological molecules using chopped carbon fiber.

    Science.gov (United States)

    Sugawara, Kazuharu; Yugami, Asako; Kojima, Akira

    2010-01-01

    Voltammetric detection of biological molecules was carried out using chopped carbon fibers produced from carbon fiber reinforced plastics that are biocompatible and inexpensive. Because chopped carbon fibers normally are covered with a sizing agent, they are difficult to use as an electrode. However, when the surface of a chopped carbon fiber was treated with ethanol and hydrochloric acid, it became conductive. To evaluate the functioning of chopped carbon fibers, voltammetric measurements of [Fe(CN)(6)](3-) were carried out. Redoxes of FAD, ascorbic acid and NADH as biomolecules were recorded using cyclic voltammetry. The sizing agents used to bundle the fibers were epoxy, polyamide and polyurethane resins. The peak currents were the greatest when using the chopped carbon fibers that were created with epoxy resins. When the electrode response of the chopped carbon fibers was compared with that of a glassy carbon electrode, the peak currents and the reversibility of the electrode reaction were sufficient. Therefore, the chopped carbon fibers will be useful as disposable electrodes for the sensing of biomolecules.

  20. Parabolic Strip Telescope

    CERN Document Server

    Chadzitaskos, Goce

    2013-01-01

    We present a proposal of a new type of telescopes using a rotating parabolic strip as the primary mirror. It is the most principal modification of the design of telescopes from the times of Galileo and Newton. In order to demonstrate the basic idea, the image of an artificial constellation observed by this kind of telescope was reconstructed using the techniques described in this article. As a working model of this new telescope, we have used an assembly of the primary mirror---a strip of acrylic glass parabolic mirror 40 cm long and 10 cm wid shaped as a parabolic cylinder of focal length 1 m---and an artificial constellation, a set of 5 apertures in a distance of 5 m illuminated from behind. In order to reconstruct the image, we made a series of snaps, each after a rotation of the constellation by 15 degrees. Using Matlab we reconstructed the image of the artificial constellation.

  1. Nanostructured sulfur cathodes

    KAUST Repository

    Yang, Yuan

    2013-01-01

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. © 2013 The Royal Society of Chemistry.

  2. Cathodic hydrodimerization of nitroolefins

    OpenAIRE

    Michael Weßling; Hans J. Schäfer

    2015-01-01

    Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C–C bond formation...

  3. Spray Rolling Aluminum Strip

    Energy Technology Data Exchange (ETDEWEB)

    Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

    2006-05-10

    Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

  4. Cathode materials review

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Claus, E-mail: danielc@ornl.gov; Mohanty, Debasish, E-mail: danielc@ornl.gov; Li, Jianlin, E-mail: danielc@ornl.gov; Wood, David L., E-mail: danielc@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS6472 Oak Ridge, TN 37831-6472 (United States)

    2014-06-16

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO{sub 2} cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  5. Cathode materials review

    Science.gov (United States)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-06-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  6. Investigation on Voltammetric Behavior of Camptothecin and Its Analytical Application

    Institute of Scientific and Technical Information of China (English)

    ZHENG, Jian-Bin; MENG, Zu-Chao; LIU, Bo; ZHANG, Hong-Fang

    2006-01-01

    The voltammetric behavior of camptothecin (CPT) in Britton-Robinson (B-R) buffer solutions (pH 2.09-9.07)was studied by the means of linear sweep voltammetry (LSV), cyclic voltammetry (CV) and normal pulse voltammetry (NPV) at a hanging mercury drop electrode. In different pH range of B-R buffer solutions, CPT could cause three reduction waves. In B-R buffer solutions (pH 2.09-5.46), wave P1 yielded by CPT was a two-electron wave.Between pH 6.01 and 9.07, CPT could yield two reduction waves P2 and P3. In addition, the pure CPT obtained from camptotheca acumina grown only in China was determined by NPV, and a linear response was observed in the tion limit for CPT.

  7. XCII. A Low-Cost Voltammetric Signal Generator for the Electroanalytical Chemistry Laboratory

    Science.gov (United States)

    Ewing, Galen W., Ed

    1977-01-01

    Describes the construction of a versatile signal generator suitable for use in cyclic voltammetric experiments, which can also be adapted to a conventional dc polarograph by replacing its ramp source. (MLH)

  8. Voltammetric scanning electrochemical cell microscopy: dynamic imaging of hydrazine electro-oxidation on platinum electrodes

    NARCIS (Netherlands)

    Chen, C.-H.; Jacobse, L.; McKelvey, K.; Lai, S.C.S.; Koper, M.T.M.; Unwin, P.R.

    2015-01-01

    Voltammetric scanning electrochemical cell microscopy (SECCM) incorporates cyclic voltammetry measurements in the SECCM imaging protocol, by recording electrochemical currents in a wide potential window at each pixel in a map. This provides much more information compared to traditional fixed potenti

  9. Mesoporous film of WO3-the "sunlight" assisted decomposition of surfactant in wastewater for voltammetric determination of Pb

    Science.gov (United States)

    Krasnodębska-Ostręga, Beata; Bielecka, Agnieszka; Biaduń, Ewa; Miecznikowski, Krzysztof

    2016-12-01

    In this paper we present the application of "sunlight" assisted digestion in the presence of WO3 to the decomposition of dissolved organic matter, using the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant (1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton™X-114) in natural water samples, prior to the determination of traces residues of lead by stripping voltammetry methods. The results of the study showed firstly that the preparation of reproducible WO3 layers characterized by high mechanical and chemical resistance was possible, and secondly that it was also possible to obtain a high efficiency of decomposition, equal in efficiency to that of the reference method, which was the hydrogen peroxide oxidation assisted by UV, with evaporation nearly to dryness. The developed procedure is suggested to be a no-reagents method for the decomposition of added SDS, leading to 100% recovery of added Pb (II). The anodic stripping voltammetric curves recorded in solution after 4 h irradiation with UV assisted by WO3 were repeatable and increased linearly with standard additions, but the data finally obtained were incorrect. The curves recorded in solution after "sunlight" assisted digestion in the presence of WO3 were repeatable, and increased linearly with an increasing of concentration of standard additions (100% recovery of Pb). In the case of a nonionic surfactant, the decomposition time is at least 6 h. The advantage of the proposed method is the fact that the digestion process does not need the addition of any chemicals for the complete decomposition of organic matter.

  10. Discrimination of Rice with Different Pretreatment Methods by Using a Voltammetric Electronic Tongue

    OpenAIRE

    2015-01-01

    In this study, an application of a voltammetric electronic tongue for discrimination and prediction of different varieties of rice was investigated. Different pretreatment methods were selected, which were subsequently used for the discrimination of different varieties of rice and prediction of unknown rice samples. To this aim, a voltammetric array of sensors based on metallic electrodes was used as the sensing part. The different samples were analyzed by cyclic voltammetry with two sample-p...

  11. Strip shape control capability of hot wide strip rolling mills

    Institute of Scientific and Technical Information of China (English)

    Renzhong Wang; Quan Yang; Anrui He; Jian Shao; Haitao Bian

    2008-01-01

    The elasticity deformation of rolls was analyzed by means of two-dimensional f'mite element method (FEM) with vari-able thickness. Three typical mills were used as objects for analysis. A thorough study was done on the control capabilities of these mills on the strip shape. Then the strip shape control capabilities of the three mills was compared synthetically.

  12. Simultaneous determination of cefotaxime and desacetylcefotaxime in real urine sample using voltammetric and high-performance liquid chromatographic methods.

    Science.gov (United States)

    Aleksić, Mara M; Kapetanović, Vera; Atanacković, Jasmina; Jocić, Biljana; Zecević, Mira

    2008-10-19

    Two rapid, accurate and sensitive methods are developed and validated for the quantitative simultaneous determination of cefotaxime (CFX) and its active metabolite desacetylcefotaxime (DCFX) in urine. Based on the previous results which showed the four electron reduction of CFX at approximately -0.5 V, and the new findings that DCFX reduction occurred at more positive potential (-0.23 V), the new adsorptive stripping differential pulse voltammetric (AdSDPV) method was developed for determination of CFX in the presence of DCFX. Linear responses were observed over a wide concentration range (0.07-0.52 microg/ml for CFX and 0.22-1.3 microg/ml for DCFX) in urine. The second assay involves subsequent separation on a reversed-phase HPLC column, with ultraviolet detection at 262 nm. Retention times were 4.057 and 1.960 min for CFX and DCFX, respectively. Linear responses were observed over a wide range, 0.55-6.60 microg/ml for CFX and 1.10-11.00 microg/ml for DCFX, in urine. The statistical evaluation for both methods was examined by means of within-day repeatability (n=5) and day-to-day precision (n=3) and was found to be satisfactory with high accuracy and precision.

  13. Voltammetric behavior, biocidal effect and synthesis of some new nanomeric fused cyclic thiosemicarbazones and their mercuric(II salts

    Directory of Open Access Journals (Sweden)

    M.S.T. Makki

    2014-11-01

    Full Text Available New nanomeric 3-thioxo-5-methoxy-4,5-dihydro-6-methyl-9-unsubstituted/substituted-1,2,4-triazino[5,6-b]indoles (2a–c and 3-thioxo-5-methoxy-4,5-dihydro-6,7-dihydroxy-1,2,4-triaino[5,6]-cyclobut-6-ene (3 were prepared via reaction of thiosemicarbazide with 5-unsubstitutedand/substituted-indol-2,3-diones and/or 3,4-dihydroxycyclobutane-1,2-dione in methanol–concentrated HCl at room temperature. A series of mercury(II–ligand salts e.g. compound 4b and Hg(II complexes 5a,b and 6 of cyclic Schiff base were prepared. Structures of these compounds were established by elemental analysis and spectral measurements. The redox characteristics of selected compounds were studied for use as chelating agents for stripping voltammetric determination of mercuric(II ions in aqueous media. The compounds were also screened for their use as molluscicidal agents against Biomophalaria Alexandrina Snails responsible for Bilhariziasis.

  14. Sensitive voltammetric determination of tryptophan using an acetylene black paste electrode modified with a Schiff's base derivative of chitosan.

    Science.gov (United States)

    Deng, Peihong; Fei, Junjie; Feng, Yonglan

    2011-12-21

    Chitosan was modified by salicylaldehyde via Schiff's base reaction and the resulting product was modified on the surface of an acetylene black paste electrode (ABPE) by the drop-coating method. In 0.5 mol L(-1) acetate buffer (pH 4.2), a substantial increase in the anodic stripping peak current of tryptophan (Trp) (compared to conventional bare carbon paste electrode (CPE) and bare ABPE) is observed at the Schiff's base chitosan-modified electrode. The parameters influencing voltammetric determination of Trp have been optimized. Under the selected conditions, the linearity between the anodic peak currents and concentrations of Trp demonstrated a wide range of 6.0 × 10(-8) mol L(-1) to 2.0 × 10(-6) mol L(-1), 2.0 × 10(-6) mol L(-1) to 4.0 × 10(-5) mol L(-1) and 4.0 × 10(-5) mol L(-1) to 1.0 × 10(-4) mol L(-1), a low detection limit of 2.0 × 10(-9) mol L(-1) was obtained after a 60 s accumulation. In addition, the developed electrochemical sensor has been successfully applied for the determination of Trp in pharmaceutical and biological samples with satisfactory assay results.

  15. Filtered cathodic arc source

    Science.gov (United States)

    Falabella, Steven; Sanders, David M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45.degree. to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  16. Highly Efficient Micro Cathode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek Company, Inc. proposes to develop a micro thermionic cathode that requires extremely low power and provides long lifetime. The basis for the cathode is a...

  17. Advanced Cathode Electrolyzer (ACE) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a static, cathode-fed, 2000 psi, balanced-pressure Advanced Cathode Electrolyzer (ACE) based on PEM electrolysis technology. It...

  18. Miniaturized cathodic arc plasma source

    Science.gov (United States)

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  19. Cathode material for lithium batteries

    Science.gov (United States)

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  20. Smart cathodic protection systems

    NARCIS (Netherlands)

    Polder, R.B.; Leggedoor, J.; Schuten, G.; Sajna, S.; Kranjc, A.

    2010-01-01

    Cathodic protection delivers corrosion protection in concrete structures exposed to aggressive environments, e.g. in de-icing salt and marine climates. Working lives of a large number of CP systems are at least more than 13 years and probably more than 25 years, provided a minimum level of maintenan

  1. SOFC Cathode Mechanisms

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Zachau-Christiansen, Birgit; Bay, Lasse

    1996-01-01

    The transient response of SOFC oxygen cathodes shows a characteristic inductive hysteresis and correspondingly the impedance diagram combines one or two capacitive arcs with a low frequency inductive arc. These features are discussed on the basis of a three step reaction sequence taken from...

  2. Anodic stripping voltammetry at in situ bismuth-plated carbon and gold microdisc electrodes in variable electrolyte content unstirred solutions.

    Science.gov (United States)

    Baldrianova, L; Svancara, I; Economou, A; Sotiropoulos, S

    2006-10-27

    Carbon and gold microdisc electrodes (30 and 10 microm, respectively) have been tested as substrates for in situ bismuth film plating from unstirred solutions of variable acetate buffer content and were subsequently used in the anodic stripping voltammetry determination of Pb(II) and Cd(II) ions. The effects of Bi(III) concentration, analyte accumulation time, stirring as well as supporting electrolyte content have been studied. Under optimal conditions good voltammetric responses were obtained by means of square wave anodic stripping voltammetry in unstirred analyte solutions of 5 x 10(-8) to 10(-6)M, even in the absence of added buffer. In an indicative application, Pb(II) ion levels were determined in tap water using bismuth-plated carbon microdisc electrodes.

  3. Electrochemical studies of 1,5-dihydroxynaphthalene as substrate for voltammetric enzyme immunoassay

    Institute of Scientific and Technical Information of China (English)

    JIAO Kui; YAO Hong; XU Jin; ZHANG Shusheng

    2004-01-01

    A sensitive voltammetric enzyme immunoanalytical method is described for assay of horseradish peroxidase (HRP), labelled-HRP and antigen:antibody:labelled-HRP conjugate (Ag︰AB︰IgG-HRP) using 1,5-dihydroxynaphthalene (1,5-DHN) as substrate. 1,5-DHN is an electrochemical inactive substance, but it may be oxidized by O2 in air to 5-hydroxy-1,4-naphtho- quinone in basic solution, which produces a well-defined voltammetric reduction peak. After adding H2O2 and HRP, HRP catalyzes H2O2 oxidizing 5-hydroxy-1,4-naphthoquinone to 3-hydroxyphthalic acid, leading to the decrease of the voltammetric reduction peak, with which the activity of HRP and the labelled-HRP, further the antigen and antibody may be determined. The mechanism of this voltammetric enzyme-linked immunoassay system is different from the previous reports, in which there are no voltammetric reduction peaks before the addition of H2O2 and HRP, and the reduction peaks appear after the addition of H2O2 and HRP. The height of the voltammetric peak is directly proportional to the concentration of HRP in the previous systems, while the decrease of the voltammetric peak is linear with the concentration of HRP in this system. This new electrochemical method is combined with an indirect enzyme immunoassay using direct antigen-coating format for the detection of the purified tobacco mosaic virus (TMV) with a linear range from 25.0 to 340.0 ng/mL, and a detection limit 25.0 ng/mL.

  4. Analysis/design of strip reinforced random composites (strip hybrids)

    Science.gov (United States)

    Chamis, C. C.; Sinclair, J. H.

    1978-01-01

    Advanced analysis methods and composite mechanics were applied to a strip-reinforced random composite square panel with fixed ends to illustrate the use of these methods for the a priori assessment of the composite panel when subjected to complex loading conditions. The panel was assumed to be of E-glass random composite. The strips were assumed to be of three advanced unidirectional composites to cover a range of low, intermediate, and high modulus stiffness. The panels were assumed to be subjected to complex loadings to assess their adequacy as load-carrying members in auto body, aircraft engine nacelle and windmill blade applications. The results show that strip hybrid panels can be several times more structurally efficient than the random composite base materials. Some of the results are presented in graphical form and procedures are described for use of these graphs as guides for preliminary design of strip hybrids.

  5. Analysis/design of strip reinforced random composites /strip hybrids/

    Science.gov (United States)

    Chamis, C. C.; Sinclair, J. H.

    1978-01-01

    Results are described which were obtained by applying advanced analysis methods and composite mechanics to a strip-reinforced random composite square panel with fixed ends. This was done in order to illustrate the use of these methods for the apriori assessment of the composite panel when subjected to complex loading conditions. The panel was assumed to be of E-Glass/Random Composite. The strips were assumed to be of three advanced unidirectional composites to cover a range of low, intermediate, and high modulus stiffness. The panels were assumed to be subjected to complex loadings to assess their adequacy as load-carrying members in auto body, aircraft engine nacelle, and windmill blade applications. The results show that strip hybrid panels can be several times more structurally efficient than the random composite base materials. Some of the results are presented in graphical form and procedures are described for use of these graphs as guides for preliminary design of strip hybrids.

  6. Electropolymerized supramolecular tetraruthenated porphyrins applied as a voltammetric sensor

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Monize M. da; Ribeiro, Gabriel H.; Faria, Anizio M. de; Bogado, Andre L.; Dinelli, Luis R., E-mail: dinelli@pontal.ufu.br [Universidade Federal de Uberlandia (UFU), Ituiutaba, MG (Brazil). Faculdade de Ciencias Integradas do Pontal; Batista, Alzir A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Quimica

    2013-11-15

    Porphyrin 5,10,15,20-Tetra(4-pyridyl)manganese(III), [Mn-TPyP(H{sub 2}O){sub 2}]PF{sub 6}, and electropolymerized supramolecular porphyrins (ESP), {l_brace}Mn-TPyP(H{sub 2}O){sub 2}[RuCl{sub 3}(dppb)]{sub 4}{r_brace}PF{sub 6} (dppb = 1,4-bis(diphenylphosphine)butane), were synthesized and characterized. A thin solid film of ESP was obtained on a glass carbon electrode surface by a cyclic voltammetry method. The peak current increased with the number of voltammetric cycles, which shows a typical behavior of the species being adsorbed on the surface of the electrode. Cyclic voltammetry was also employed for acetaminophen quantification using an ESP modified electrode. The modified electrode shows a linear relationship between the anodic peak current and the concentration of acetaminophen (in the rage 0.05 to 0.7 mmol L{sup -1}. The performance of the modified electrode was verified by the determination of acetaminophen in a commercial pharmaceutical product and the results were in good agreement with those obtained by a control HPLC method. (author)

  7. Thrombin-Binding Aptamer Quadruplex Formation: AFM and Voltammetric Characterization

    Directory of Open Access Journals (Sweden)

    Victor Constantin Diculescu

    2010-01-01

    Full Text Available The adsorption and the redox behaviour of thrombin-binding aptamer (TBA and extended TBA (eTBA were studied using atomic force microscopy and voltammetry at highly oriented pyrolytic graphite and glassy carbon. The different adsorption patterns and degree of surface coverage were correlated with the sequence base composition, presence/absence of K+, and voltammetric behaviour of TBA and eTBA. In the presence of K+, only a few single-stranded sequences present adsorption, while the majority of the molecules forms stable and rigid quadruplexes with no adsorption. Both TBA and eTBA are oxidized and the only anodic peak corresponds to guanine oxidation. Upon addition of K+ ions, TBA and eTBA fold into a quadruplex, causing the decrease of guanine oxidation peak and occurrence of a new peak at a higher potential due to the oxidation of G-quartets. The higher oxidation potential of G-quartets is due to the greater difficulty of electron transfer from the inside of the quadruplex to the electrode surface than electron transfer from the more flexible single strands.

  8. Microtube strip heat exchanger

    Science.gov (United States)

    Doty, F. D.

    1991-04-01

    During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchangers. The team has begun a heat exchanger stress analysis; however, they have been concentrating the bulk of their analytical energies on a computational fluid dynmaics (CFD) model to determine the location and magnitude of shell-side flow maldistribution which decreases heat exchanger effectiveness. DSI received 120 fineblanked tubestrips from Southern Fineblanking (SFB) for manufacturing process development. Both SFB and NIST provided inspection reports of the tubestrips. DSI completed the tooling required to encapsulate a tube array and press tubestrips on the array. Pressing the tubestrips on tube arrays showed design deficiencies both in the tubestrip design and the tooling design. DSI has a number of revisions in process to correct these deficiencies. The research effort has identified a more economical fusible alloy for encapsulating the tube array, and determined the parameters required to successfully encapsulate the tube array with the new alloy. A more compact MTS heat exchanger bank was designed.

  9. Differential Pulse Anodic Stripping Voltammetry for Mercury Determination

    Directory of Open Access Journals (Sweden)

    Vereștiuc Paul C.

    2015-07-01

    Full Text Available In the present work voltammetric investigations have been performed on HgCl2 aqueous solutions prepared from a Cz 9024 reagent. Carbon paste electrode (CPE, eriochrome black T modified carbon paste electrode (MCPE/EBT and KCl 1M as background electrolyte, were involved within the experimental procedures. Cyclic voltammetry (CV has been performed in order to compare the behaviour of the two electrodes in both K3[Fe(CN6] and mercury calibration aqueous solution. Differential pulse anodic stripping voltammetry (DPASV was used to determine the most suitable parameters for mercury determination. All experiments were performed at 25 ± 1 ℃, using an electrochemical cell with three-electrodes connected to an Autolab PG STAT 302N (Metrohm-Autolab potentiostat that is equipped with Nova 1.11 software. The measured potential values were generated by using the silver chloride electrode (AgClE as reference and a platinum wire electrode as auxiliary. A series of time depending equations for the pre-concentration and concentration steps were established, with the observation that a higher sensitivity can be obtained while increasing the pre-concentration time. DPASV were drawn using the CPE in 11.16 % coriander, as mercury complex, the voltamograms signals indicating mercury oxidation, with signal intensity increasing in time.

  10. The versatility of salicylaldehyde thiosemicarbazone in the determination of copper in blood using adsorptive stripping voltammetry.

    Science.gov (United States)

    Mahajan, Rakesh Kumar; Walia, T P S; Sumanjit; Lobana, T S

    2005-10-15

    The adsorptive cathodic stripping voltammetry technique (AdCSV) is used to determine copper(II) using salicylaldehyde thiosemicarbazone (N, S- donor) as a complexing agent on hanging mercury drop electrode at pH 9.3. Variable factors affecting the response, i.e. the concentration of ligand, pH, adsorption potential and adsorption time are assessed and optimized. The adsorbed complex of copper(II) and salicylaldehyde thiosemicarbazone gives a well defined cathodic stripping peak current at -0.35 V, which has been used for the determination of copper in the concentration range of 7.85 x 10(-9) to 8.00 x 10(-6)M with accumulation time of 360 s at -0.1 V versus Ag/AgCl. This technique has been applied for the determination of copper in various digested samples of whole blood at trace levels.

  11. Magnetic stripping studies for SPL

    CERN Document Server

    Posocco, P; CERN. Geneva. BE Department

    2010-01-01

    Magnetic stripping of H- can seriously enhance the beam losses along the SPL machine. These losses depend on the beam energy, on the beam transverse distribution and on the intensity of the magnetic field. For radioprotection issues the losses must be limited to 1 W/m. In this paper we will concentrate on the stripping phenomena inside the quadrupole magnets with the aim of defining the quadrupole range for the design phase of SPL.

  12. Nanocomposite electrodes made of carbon nanofibers and black wax. Anodic stripping voltammetry of zinc and lead.

    Science.gov (United States)

    van Dijk, N; Fletcher, S; Madden, C E; Marken, F

    2001-11-01

    Nanocomposite electrodes offer exciting new possibilities in electroanalytical chemistry. In this preliminary study, nanocomposite electrodes made of carbon nanofibers and black wax were characterized and investigated as novel substrates for metal deposition and stripping processes. Carbon nanofibers were grown from ethylene-hydrogen gas mixtures over Fe-Ni-Cu (85:10:5) nanoparticle catalysts at 600 degrees C and then embedded in Apiezon black wax under vacuum at 140 degrees C. The resulting nanocomposite electrodes showed (i) good conductivity, (ii) a wide potential window in aqueous solutions, (iii) low background currents, (iv) near steady state voltammetric responses with substantial Faradaic currents and (v) sharply peaked fast scan metal stripping responses. Zinc is a notoriously difficult metal to determine in aqueous solutions, because its deposition and stripping are accompanied by hydrogen evolution at extreme negative potentials. It therefore provided a challenging test for our new nanocomposite electrode. Although numerous complications associated with the hydrogen evolution process could not be eliminated, remarkably clear voltammograms could be obtained even at scan rates of 40 V s(-1).

  13. Lead migration from toys by anodic stripping voltammetry using a bismuth film electrode.

    Science.gov (United States)

    Leal, M Fernanda C; Catarino, Rita I L; Pimenta, Adriana M; Souto, M Renata S; Afonso, Christelle S; Fernandes, Ana F Q

    2016-09-02

    Metals may be released from toys via saliva during mouthing, via sweat during dermal contact, or via gastric and intestinal fluids after partial or whole ingestion. In this study, we determined the lead migration from toys bought on the Portuguese market for children below 3 years of age. The lead migration was performed according to the European Committee for Standardization EN 71-3, which proposes a 2-hour migration test that simulates human gastric conditions. The voltammetric determination of migrated lead was performed by anodic stripping voltammetry (ASV) at a bismuth film electrode (BiFE). For all the analyzed toys, the values of migrated lead did not exceed the limits imposed by the European Committee for Standardization EN 71-3 (90 mg kg(-1)) and by the EU Directive 2009/48/EC (13.5 mg kg(-1)) on the safety of toys.

  14. Inorganic arsenic speciation by differential pulse anodic stripping voltammetry using thoria nanoparticles-carbon paste electrodes.

    Science.gov (United States)

    Pereira, F J; Vázquez, M D; Debán, L; Aller, A J

    2016-05-15

    Two novel thoria (ThO2) nanoparticles-carbon paste electrodes were used to evaluate an anodic stripping voltammetric method for the direct determination of arsenite and total inorganic arsenic (arsenite plus arsenate) in water samples. The effect of Ag((I)), Cu((II)), Hg((II)), Sb((III)) and Se((IV)) ions on the electrochemical response of arsenic was assayed. The developed electroanalytical method offers a rapid procedure with improved analytical characteristics including good repeatability (3.4%) at low As((III)) concentrations, high selectivity, lower detection limit (0.1 μg L(-1)) and high sensitivity (0.54 μA μg(-1) L). The analytical capability of the optimized method was demonstrated by the determination of arsenic in certified reference materials (trace elements in natural water, trace elements in water and coal fly ash).

  15. Thick-film voltammetric pH-sensors with internal indicator and reference species

    DEFF Research Database (Denmark)

    Musa, Arnaud Emmanuel; Alonso-Lomillo, María Asunción; del Campo, Francisco Javier

    2012-01-01

    The following paper describes the development of a screen-printed voltammetric pH-sensor based on graphite electrodes incorporating both internal indicator (i.e., phenanthraquinone) and reference species (i.e., dimethylferrocene). The key advantages of this type of system stem from its simplicity......, low cost and ease of fabrication. More importantly, as opposed to conventional voltammetric systems where the height of the voltammetric peaks is taken into account to quantify the amount of a species of interest, here, the difference between the peak potential of the indicator species and the peak...... potential of the reference species is used. Thus, this measurement principle makes the electrochemical system presented here less dependent on the potential of the reference electrode (RE), as is often the case in other electrochemical systems. The developed system displays very promising performances...

  16. Novel one-step synthesis of wool-ball-like Ni-carbon nanotubes composite cathodes with favorable electrocatalytic activity for hydrogen evolution reaction in alkaline solution

    Science.gov (United States)

    Chen, Zhouhao; Ma, Zhipeng; Song, Jianjun; Wang, Lixin; Shao, Guangjie

    2016-08-01

    In this work, supergravity fields are performed to prepare Ni-CNTs composite cathodes with wool-ball-like morphology from the Watts bath containing well-distributed functionalized CNTs. The prepared Ni-CNTs composite cathodes are used as noble metal-free electrocatalyst with favorable electrocatalytic activity for hydrogen evolution reaction (HER) in alkaline solutions. The crystal structure and morphology of the composite cathodes are characterized by XRD and SEM measurements. The electrochemical activities of the cathodes are characterized through Tafel polarization measurement, electrochemical impedance spectroscopy and cyclic voltammetric study in 1.0 M NaOH solution. The results indicate that catalytic activities of the Ni-CNTs cathodes prepared under supergravity fields are enhanced significantly, and the sample prepared at rotating speed 3000 rpm from the bath containing 1 g dm-3 CNTs exhibits the highest HER activity with smallest Tafel slope and largest exchange current density of 823.9 μA cm-2. Furthermore, the effects of both the CNTs concentrations and the intensities of supergravity fields on the properties of the Ni-CNTs cathodes are investigated.

  17. Restitution of enamel after interdental stripping.

    Science.gov (United States)

    Lundgren, T; Milleding, P; Mohlin, B; Nannmark, U

    1993-01-01

    This paper studies the effect of interdental stripping on the enamel surface and evaluates methods to restitute the treated surface. Extracted teeth mounted in a semielastic material were subjected to stripping by different kinds of steel strips. The treated enamel surfaces were then polished in several different ways. The effects were studied by SEM and profilometry. It was concluded that the coarsest strips produced irregularities of such a magnitude that polishing had very limited effect. Polishing starting with coarse polishing strips followed by gradually finer gave the best result. An increase in number of strokes and use of all grades of polishing strips slightly improved the result.

  18. Cathodic hydrodimerization of nitroolefins

    Directory of Open Access Journals (Sweden)

    Michael Weßling

    2015-07-01

    Full Text Available Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C–C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products.

  19. Cathodic hydrodimerization of nitroolefins.

    Science.gov (United States)

    Weßling, Michael; Schäfer, Hans J

    2015-01-01

    Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C-C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products.

  20. Studies with cathode drift chambers for the GlueX experiment at Jefferson Lab

    Science.gov (United States)

    Pentchev, L.; Barbosa, F.; Berdnikov, V.; Butler, D.; Furletov, S.; Robison, L.; Zihlmann, B.

    2017-02-01

    A drift chamber system consisting of 24 1 m-diameter chambers with both cathode and wire readout (total of 12,672 channels) is operational in Hall D at Jefferson Lab (Virginia). Two cathode strip planes and one wire plane in each chamber register the same avalanche allowing the study of avalanche development, charge induction process, and strip resolution. We demonstrate a method for reconstructing the two-dimensional distribution of the avalanche ;center-of-gravity; position around the wire from an 55Fe source with resolutions down to 30 μm. We estimate the azimuthal extent of the avalanche around the wire as a function of the total charge for an Ar/CO2 gas mixture. By means of cluster counting using a modified 3 cm-gap chamber, we observe significant space charge effects within the same track, resulting in an extent of the avalanche along the wire.

  1. VOLTAMMETRIC BEHAVIOR OF SOME STEELS IN AQUEOUS SOLUTIONS OF HNO3

    Directory of Open Access Journals (Sweden)

    Gheorghe Nemtoi

    2011-06-01

    Full Text Available The corrosion process of some steels immersed in HNO3 solutions of different concentrations by means of voltammetric measurements was investigated. For different values of the corrosion potential, or of the contact time: solid steel-aggressive medium, several equations of the type: I = f (E were proposed, only for linear domains of the voltammograms.

  2. Discrimination of Rice with Different Pretreatment Methods by Using a Voltammetric Electronic Tongue.

    Science.gov (United States)

    Wang, Li; Niu, Qunfeng; Hui, Yanbo; Jin, Huali

    2015-07-22

    In this study, an application of a voltammetric electronic tongue for discrimination and prediction of different varieties of rice was investigated. Different pretreatment methods were selected, which were subsequently used for the discrimination of different varieties of rice and prediction of unknown rice samples. To this aim, a voltammetric array of sensors based on metallic electrodes was used as the sensing part. The different samples were analyzed by cyclic voltammetry with two sample-pretreatment methods. Discriminant Factorial Analysis was used to visualize the different categories of rice samples; however, radial basis function (RBF) artificial neural network with leave-one-out cross-validation method was employed for prediction modeling. The collected signal data were first compressed employing fast Fourier transform (FFT) and then significant features were extracted from the voltammetric signals. The experimental results indicated that the sample solutions obtained by the non-crushed pretreatment method could efficiently meet the effect of discrimination and recognition. The satisfactory prediction results of voltammetric electronic tongue based on RBF artificial neural network were obtained with less than five-fold dilution of the sample solution. The main objective of this study was to develop primary research on the application of an electronic tongue system for the discrimination and prediction of solid foods and provide an objective assessment tool for the food industry.

  3. Discrimination of Rice with Different Pretreatment Methods by Using a Voltammetric Electronic Tongue

    Directory of Open Access Journals (Sweden)

    Li Wang

    2015-07-01

    Full Text Available In this study, an application of a voltammetric electronic tongue for discrimination and prediction of different varieties of rice was investigated. Different pretreatment methods were selected, which were subsequently used for the discrimination of different varieties of rice and prediction of unknown rice samples. To this aim, a voltammetric array of sensors based on metallic electrodes was used as the sensing part. The different samples were analyzed by cyclic voltammetry with two sample-pretreatment methods. Discriminant Factorial Analysis was used to visualize the different categories of rice samples; however, radial basis function (RBF artificial neural network with leave-one-out cross-validation method was employed for prediction modeling. The collected signal data were first compressed employing fast Fourier transform (FFT and then significant features were extracted from the voltammetric signals. The experimental results indicated that the sample solutions obtained by the non-crushed pretreatment method could efficiently meet the effect of discrimination and recognition. The satisfactory prediction results of voltammetric electronic tongue based on RBF artificial neural network were obtained with less than five-fold dilution of the sample solution. The main objective of this study was to develop primary research on the application of an electronic tongue system for the discrimination and prediction of solid foods and provide an objective assessment tool for the food industry.

  4. Development of a rapid and simple voltammetric method to determine total antioxidative capacity of edible oils.

    Science.gov (United States)

    Gulaboski, Rubin; Mirčeski, Valentin; Mitrev, Saša

    2013-05-01

    In this work we report on a new, rapid and simple voltammetric method to determine the total antioxidant capacity (TAC) of the edible oils. The method explores the ABTS radical (2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)) assay as a redox probe and it relays on measuring catalytic voltammetric currents. The electrocatalysis comprises redox regeneration of the electrochemically created ABTS(+) radical either by Trolox (6-hydroxy-2,5,7,8-tetramethychroman-2-carboxylic acid) or by antioxidants present in studied oils. The detection limit of the method is determined to be 0.5 mg/L of Trolox equivalent, being a slightly lower than the corresponding UV-VIS spectrophotometric method. Applying the proposed voltammetric method the total antioxidant capacity of three types of commercially available cold-pressed edible oils are determined, and the results are found to be in a very good agreement with those obtained by UV-VIS spectrophotometry. The reported voltammetric method is cheap, rapid and simple, and it can be used as a sustainable alternative to the UV-VIS methods for the determination of total antioxidant capacitance of oils and other liquid lipophilic nutrients. Potent antioxidant capacity of studied oils was also confirmed by electron paramagnetic resonance spectroscopy of superoxide anion produced by macrophages.

  5. Intraply Hybrid Composites Would Contain Control Strips

    Science.gov (United States)

    Chamis, Christos C.; Shiao, Chi-Yu

    1996-01-01

    "Smart" structural components with sensors and/or actuators distributed throughout their volumes made of intraply hybrid composite materials, according to proposal. Strips of hybrid control material interspersed with strips of ordinary (passive) composite material in some layers, providing distributed control capability. For example, near and far edges of plate bent upward by commanding bottom control strips to expand and simultaneously commanding upper control strips to contract.

  6. Innovative ammonia stripping with an electrolyzed water system as pretreatment of thermally hydrolyzed wasted sludge for anaerobic digestion.

    Science.gov (United States)

    Park, Seyong; Kim, Moonil

    2015-01-01

    In this study, the anaerobic digestion of thermally hydrolyzed wasted sludge (THWS) with a high concentration of ammonia was carried out through combining with an ammonia stripping and an electrolyzed water system (EWS). The EWS produced acidic water (pH 2-3) at the anode and alkaline water (pH 11-12) at the cathode with an electro-diaphragm between the electrodes that could be applied to ammonia stripping. The ammonia stripping efficiency was strongly dependent on the pH and aeration rate, and the ammonium ion removal rate followed pseudo-first-order kinetics. From the BMP test, the methane yield of THWS after ammonia stripping using the EWS was 2.8 times higher than that of the control process (raw THWS without ammonia stripping). Furthermore, both methane yield and ammonium removal efficiency were higher in this study than in previous studies. Since ammonia stripping with the EWS does not require any chemicals for pH control, no precipitated sludge is produced and anaerobic microorganisms are not inhibited by cations. Therefore, ammonia stripping using the EWS could be an effective method for digestion of wastewater with a high concentration of ammonium nitrogen.

  7. Using Comic Strips in Language Classes

    Science.gov (United States)

    Csabay, Noémi

    2006-01-01

    The author believes that using comic strips in language-learning classes has three main benefits. First, comic strips motivate younger learners. Second, they provide a context and logically connected sentences to help language learning. Third, their visual information is helpful for comprehension. The author argues that comic strips can be used in…

  8. Cheap in situ voltammetric copper determination from freshwater samples

    Directory of Open Access Journals (Sweden)

    David I. G.

    2013-04-01

    Full Text Available Detection of low concentrations of heavy metals in environmental samples is of particular interest because most of them represent persistent, highly toxic pollutants. Cu2+ detection in environmental samples is important because it is typical heavy metal, being an essential element for human beings but at higher concentrations it can create health risks. Due to the accumulation steps involved, anodic stripping voltammetry (ASV is one of the most sensitive techniques used for the detection of low concentrations of metal ions form different environmental samples. In order to minimize sample loss during sample collection, storage and transportation it is of particular interest to perform in situ rapid and reliable routine analysis. In the present paper we describe the use of a simple, disposable pencil graphite electrode (PGE for the determination of Cu from river water samples by mercury film anodic stripping voltammetry. The investigated water samples were collected during a period of 3 years (2009-2011, from six sampling points situated along the lower part of the Prut River (Romania. ASV measurements were performed in the presence of Hg2+ in 0.1 M HNO3 at a carbon pencil graphite working electrode. Standard addition method was applied for the quantification of Cu2+. The Cu2+ content of the most river water samples analysed exceeded 2 ⎧g/L (MEWM, 2006, the maximum admitted concentration for surface waters, and these could be due to the anthropogenic activities in the region (e.g. the largest steel factory in Romania is located in the vicinity of the sampling area. Samples show an additional importance as the region is included in a protected area, Lower Prut Floodplain Natural Park, and trace elements transfer along the aquatic food chain has been previously documented (Matache et. al, 2012. The results obtained by ASV on PGE agreed well with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES using the Romanian

  9. Metrological characteristics of the flat voltammetric electrode in time domain with a reversible electrochemical reaction running on the surface

    Science.gov (United States)

    Suchocki, Krzysztof

    2016-11-01

    The study deals with metrological characteristics of the flat voltammetric electrode used for determination of ions concentration by the DC voltammetric method, where a reversible reaction of electrochemical oxidation/reduction takes place on the surface. The analysis shows that such voltammetric electrode acts as a transducer of the first order, where the input signal is a concentration of marked ions in tested solution and the output signal is the current associated with a reversible reaction of oxidation / reduction. Metrological characteristics of such electrode in the time domain are determined by its sensitivity and time constant. The values of these parameters are defined by measurements of characteristics of the voltammetric electrode, polarization voltage and marked ions. To determine the effect of a particular volume of each of these parameters several numerical simulations are presented.

  10. Hollow Cathode With Multiple Radial Orifices

    Science.gov (United States)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  11. Voltammetric behaviour of levodopa and its quantification in pharmaceuticals using a -cyclodextrine doped poly (2,5-diaminobenzenesulfonic acid) modified electrode

    Indian Academy of Sciences (India)

    Mehmet Aslanoglu; Aysegul Kutluay; Sultan Goktas; Serpil Karabulut

    2009-03-01

    A cyclic voltammetric method based on a -cyclodextrine doped poly(2,5-diaminobenzenesulfonic acid) modified glassy carbon electrode (GCE) was developed for the determination of levodopa. Compared with bare GCE and poly(2,5-diaminobenzenesulfonic acid)/GCE, the poly(2,5-diaminobenzenesulfonic acid)--cyclodextrine/GCE exhibits a remarkable shift of the oxidation potentials of levodopa in the cathodic direction and a drastic enhancement of the anodic current response. The incorporation of -cyclodextrine into the polymer film exhibited that the electrode provides more stable and sensitive current responses for levodopa. Levodopa exhibited a single broad peak at about 0.6 V at bare GCE. However, at the -cyclodextrine doped poly(2,5-diaminobenzenesulfonic acid)/GCE, a well-defined redox wave of levodopa was obtained, with the oxidation and the reduction peak potential at 0.193 and 0.164 V, respectively. The separation of peak potentials was 29 mV. The linear current response was obtained in the range of 1.0 × 10-6 ∼ 2.0 ∼ 10-4 M with a detection limit of 4.18 ∼ 10-7 M for levodopa, The poly(2,5-diaminobenzenesulfonic acid)--cyclodextrine/GCE was also effective to simultaneously detect levodopa and ascorbic acid. The modified electrode has been successfully applied for the determination of levodopa in pharmaceuticals. The poly(2,5-diaminobenzenesulfonic acid)--cyclodextrine/GCE showed excellent stability and reproducibility.

  12. Fast variation method for elastic strip calculation.

    Science.gov (United States)

    Biryukov, Sergey V

    2002-05-01

    A new, fast, variation method (FVM) for determining an elastic strip response to stresses arbitrarily distributed on the flat side of the strip is proposed. The remaining surface of the strip may have an arbitrary form, and it is free of stresses. The FVM, as well as the well-known finite element method (FEM), starts with the variational principle. However, it does not use the meshing of the strip. A comparison of FVM results with the exact analytical solution in the special case of shear stresses and a rectangular strip demonstrates an excellent agreement.

  13. Ion-transfer voltammetric determination of the beta-blocker propranolol in a physiological matrix at silicon membrane-based liquid|liquid microinterface arrays.

    Science.gov (United States)

    Collins, Courtney J; Arrigan, Damien W M

    2009-03-15

    In this work, the ion-transfer voltammetric detection of the protonated beta-blocker propranolol in artificial saliva is presented. Cyclic voltammetry, differential pulse voltammetry, and differential pulse stripping voltammetry (DPSV) were employed in the detection of the cationic drug based on ion-transfer voltammetry across arrays of microinterfaces between artificial saliva and an organogel phase. It was found that the artificial saliva matrix decreased the available potential window for ion-transfer voltammetry at this liquid|liquid interface but transfer of protonated propranolol was still achieved. The DPSV method employed a preconditioning step as well as a preconcentration step followed by analytical signal generation based on the back-transfer of the drug across the array of microinterfaces. The DPSV peak current response was linear with drug concentration in the artificial saliva matrix over the concentration range of 0.05-1 microM (i(p) = -8.13 (nA microM(-1))(concentration) + 0.07 (nA), R = 0.9929, n = 7), and the calculated detection limit (3s(b)) was 0.02 microM. These results demonstrate that DPSV at arrays of liquid|liquid microinterfaces is a viable analytical approach for pharmaceutical determinations in biomimetic matrixes.

  14. Development of a voltammetric procedure for assay of the antihistamine drug hydroxyzine at a glassy carbon electrode: Quantification and pharmacokinetic studies.

    Science.gov (United States)

    Beltagi, A M; Abdallah, O M; Ghoneim, M M

    2008-01-15

    An electrochemical study of hydroxyzine at a glassy carbon electrode was carried out in the Britton-Robinson universal buffer of pH 2-11. Hydroxyzine was oxidized in a single two-electron irreversible process controlled mainly by adsorption. A simple, sensitive and time-saving square-wave adsorptive anodic stripping voltammetric procedure has been developed for determination of hydroxyzine in its commercial tablets and human serum without prior extraction. The optimized procedural conditions were: frequency=120Hz, scan increment=10mV, pulse-amplitude=25mV, accumulation potential=-0.3V, accumulation time=90-300s and a Britton-Robinson universal buffer of pH 4 as a supporting electrolyte. Mean recoveries of 100.5+/-0.71 and 98.6+/-1.12% (n=5) were achieved for assay of hydroxyzine in Atarax 10 and 25mg dosage forms, respectively. Limit of detection of 1.5x10(-8)molL(-1) (5.624ngmL(-1)) and limit of quantitation of 5.0x10(-8)molL(-1) (18.746ngmL(-1)) were achieved in human serum with a mean recovery of 98.4+/-1.22%, without prior extraction of the drug. Moreover, the described procedure was applied for evaluating the pharmacokinetic parameters of hydroxyzine in plasma of two healthy volunteers after administration of a single oral dose (Atarax)-25mg).

  15. Simultaneous voltammetric determination of paracetamol and ascorbic acid using a boron-doped diamond electrode modified with Nafion and lead films.

    Science.gov (United States)

    Tyszczuk-Rotko, Katarzyna; Bęczkowska, Ilona; Wójciak-Kosior, Magdalena; Sowa, Ireneusz

    2014-11-01

    The paper describes the fabrication and application of a novel sensor (a boron-doped diamond electrode modified with Nafion and lead films) for the simultaneous determination of paracetamol and ascorbic acid by differential pulse voltammetry. The main advantage of the lead film and polymer covered boron-doped diamond electrode is that the sensitivity of the stripping responses is increased and the separation of paracetamol and ascorbic acid signals is improved due to the modification of the boron-doped diamond surface by the lead layer. Additionally, the repeatability of paracetamol and ascorbic acid signals is improved by the application of the Nafion film coating. In the presence of oxygen, linear calibration curves were obtained in a wide concentration range from 5×10(-7) to 2×10(-4) mol L(-1) for paracetamol and from 1×10(-6) to 5×10(-4) mol L(-1) for ascorbic acid. The analytical utility of the differential pulse voltammetric method elaborated was tested in the assay of paracetamol and ascorbic acid in commercially available pharmaceutical formulations and the method was validated by high performance liquid chromatography coupled with diode array detector.

  16. Antenna structure with distributed strip

    Science.gov (United States)

    Rodenbeck, Christopher T.

    2008-03-18

    An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

  17. Electrochemical behavior of folic acid at calixarene based chemically modified electrodes and its determination by adsorptive stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Vaze, Vishwanath D. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India); Srivastava, Ashwini K. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India)], E-mail: aksrivastava@chem.mu.ac.in

    2007-12-31

    Voltammetric behavior of folic acid at plain carbon paste electrode and electrode modified with calixarenes has been studied. Two peaks for irreversible oxidation were observed. Out of the three calixarenes chosen for modification of the electrodes, p-tert-butyl-calix[6]arene modified electrode (CME-6) was found to have better sensitivity for folic acid. Chronocoulometric and differential pulse voltammetric studies reveal that folic acid can assemble at CME-6 to form a monolayer whose electron transfer rate is 0.00273 s{sup -1} with 2-electron/2-proton transfer for the peak at +0.71 V against SCE. An adsorption equilibrium constant of 5 x 10{sup 3} l/mol for maximum surface coverage of 2.89 x 10{sup -10} mol/cm{sup 2} was obtained. The current is found to be rectilinear with concentration by differential pulse voltammetry. However, linearity in the lower range of concentration 8.79 x 10{sup -12} M to 1.93 x 10{sup -9} M with correlation coefficient of 0.9920 was achieved by adsorptive stripping voltammetry. The limit of detection obtained was found to be 1.24 x 10{sup -12} M. This method was used for the determination of folic acid in a variety of samples, viz. serum, asparagus, spinach, oranges and multivitamin preparations.

  18. Application of anodic stripping voltammetry for zinc, copper, and cadmium quantification in the aqueous humor: implications of pseudoexfoliation syndrome.

    Science.gov (United States)

    Panteli, Vassiliki S; Kanellopoulou, Dimitra G; Gartaganis, Sotirios P; Koutsoukos, Petros G

    2009-12-01

    Anodic stripping voltammetric (ASV) procedure, using mercury film electrode, was optimized and applied to determine the concentrations of zinc, cadmium, and copper in the aqueous humor. Concentration levels as low as 1 ppb of the test metals was possible to be detected using short electrolysis times (120 s) and microquantities of aqueous humor (up to 35 μL). As a first application of the voltammetric analysis of trace metals in the aqueous humor, the role of the three selected trace elements in the pseudoexfoliation (PEX) syndrome was examined. Samples from aqueous humor were collected during cataract extraction from patients with and without PEX. The zinc and copper concentration levels in the aqueous humor did not show statistically significant difference in the study and control group. Cadmium was detected in a small number of samples, without however statistical differences between the two groups. ASV proved to be a highly precise and sensitive tool for the quantification of heavy metal ions in aqueous humor. Further studies may lead to useful conclusions for the role of zinc, copper, or cadmium in PEX syndrome.

  19. Liquid cathode primary batteries

    Science.gov (United States)

    Schlaikjer, Carl R.

    1985-03-01

    Lithium/liquid cathode/carbon primary batteries offer from 3 to 6 times the volumetric energy density of zinc/alkaline manganese cells, improved stability during elevated temperature storage, satisfactory operation at temperatures from -40 to +150 °C, and efficient discharge at moderate rates. he lithium/sulfur dioxide cell is the most efficient system at temperatures below 0 °C. Although chemical reactions leading to electrolyte degradation and lithium corrosion are known, the rates of these reactions are slow. While the normal temperature cell reaction produces lithium dithionite, discharge at 60 °C leads to a reduction in capacity due to side reactions involving sulfur dioxide and discharge intermediates. Lithium/thionyl chloride and lithium/sulfuryl chloride cells have the highest practical gravimetric and volumetric energy densities when compared with aqueous and most other nonaqueous systems. For thionyl chloride, discharge proceeds through a series of intermediates to sulfur, sulfur dioxide and lithium chloride. Catalysis, leading to improved rate capability and capacity, has been achieved. The causes of rapid reactions leading to thermal runaway are thought to be chemical in nature. Lithium/sulfuryl chloride cells, which produce sulfur dioxide and lithium chloride on discharge, experience more extensive anode corrosion. An inorganic cosolvent and suitable salt are capable of alleviating this corrosion. Calcium/oxyhalide cells have been studied because of their promise of increased safety without substantial sacrifice of energy density relative to lithium cells. Anode corrosion, particularly during discharge, has delayed practical development.

  20. Microhollow cathode discharges

    Science.gov (United States)

    Schoenbach, K. H.; Moselhy, M.; Shi, W.; Bentley, R.

    2003-07-01

    By reducing the dimensions of hollow cathodes into the hundred micrometer range, stable, direct current, high (atmospheric) pressure glow discharges in rare gases, rare gas-halide mixtures and in air could be generated. The electron energy distribution in these microdischarges is non-Maxwellian, with a pronounced high-energy tail. The high electron energy together with the high gas density, which favors three-body collisions, is the reason for an efficient excimer generation in these microplasmas. Excimer efficiencies from 1% to 9% have been measured for argon, xenon, argon fluoride, and xenon chloride direct current excimer emitters, with a radiant excimer emittance of up to 2 W/cm2 for xenon. Adding small amounts of oxygen to argon has allowed us to generate vacuum ultraviolet line radiation at 130.5 nm with an efficiency approaching 1%. Pulsing xenon discharges with nanosecond electrical pulses has led to an increase in intensity to 15 W/cm2 and to a simultaneous increase in efficiency to more than 20%. Operating the discharges in an abnormal glow mode has allowed us to generate microdischarge arrays without individual ballast. Applications of these plasma arrays are excimer lamps and plasma reactors.

  1. Liquid cathode primary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Schlaikjer, C.R.

    1985-01-15

    Lithium/liquid cathode/carbon primary batteries offer from 3 to 6 times the volumetric energy density of zinc/alkaline manganese cells, improved stability during elevated temperature storage, satisfactory operation at temperatures from -40 to +150/sup 0/C, and efficient discharge at moderate rates. The lithium/sulfur dioxide cell is the most efficient system at temperatures below 0/sup 0/C. Although chemical reactions leading to electrolyte degradation and lithium corrosion are known, the rates of these reactions are slow. While the normal temperature cell reaction produces lithium dithionite, discharge at 60/sup 0/C leads to a reduction in capacity due to side reactions involving sulfur dioxide and discharge intermediates. Lithium/thionyl chloride and lithium/sulfuryl chloride cells have the highest practical gravimetric and volumetric energy densities when compared with aqueous and most other nonaqueous systems. For thionyl chloride, discharge proceeds through a series of intermediates to sulfur, sulfur dioxide and lithium chloride. Catalysis, leading to improved rate capability and capacity, has been achieved. The causes of rapid reactions leading to thermal runaway are thought to be chemical in nature. Lithium/sulfuryl chloride cells, which produce sulfur dioxide and lithium chloride on discharge, experience more extensive anode corrosion. An inorganic cosolvent and suitable salt are capable of alleviating this corrosion. Calcium/oxyhalide cells have been studied because of their promise of increased safety without substantial sacrifice of energy density relative to lithium cells. Anode corrosion, particularly during discharge, has delayed practical development.

  2. A zeolite modified carbon paste electrode as useful sensor for voltammetric determination of acetaminophen.

    Science.gov (United States)

    Ahmadpour-Mobarakeh, Leila; Nezamzadeh-Ejhieh, Alireza

    2015-04-01

    The voltammetric behavior of a carbon paste electrode modified with Co(II)-exchanged zeolite A (Co(II)-A/ZMCPE) for determination of acetaminophen was studied. The proposed electrode showed a diffusion controlled reaction with the electron transfer rate constant (Ks) of 0.44s(-1) and charge transfer coefficient of 0.73 in the absence of acetaminophen. A linear voltammetric response was obtained in the range of 0.1 to 190μmolL(-1) of acetaminophen [r(2)=0.9979, r=0.9989 (n=10)] with a detection limit of 0.04μmolL(-1). The method was successfully applied to the analysis of acetaminophen in some drugs.

  3. A rapid cyclic voltammetric method for studying cement factors affecting the corrosion of reinforced concrete

    Energy Technology Data Exchange (ETDEWEB)

    Foulkes, F.R.; McGrath, P. (Univ. of Toronto, Ontario (Canada))

    1999-06-01

    A rapid cyclic voltammetric method for studying the influence of cement factors on the corrosion of embedded iron and steel in hardened cement paste is described. The technique employs a cement electrode'' consisting of an iron or steel wire embedded in a miniature cylinder of hardened cement paste. The rapid cyclic voltammetric method is fast, reproducible, and provides information on the corrosiveness of the pore solution environment surrounding the embedded metal. The usefulness of the method is demonstrated by showing how it can be used to evaluate the threshold chloride content of hardened ordinary portland cement paste at which corrosion begins and by using it to evaluate the relative efficacy of several admixed corrosion inhibitors.

  4. Voltammetric Studies of the Interaction of Tris (1, 10-phenanthroline) Cobalt (Ⅲ) with Bovine Serum Albumin

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The voltammetric methods were used to prove the interaction of metal complex Co(phen)33+ with bovine serum albumin (BSA). The interaction of BSA with Co(phen)33+ molecules using BSA-modified electrode is described. Information of the binding ratio and interaction mode can be obtained from their electrochemical behavior and electrochemical data. Furthermore, attenuated total reflection infrared experiment was performed to prove the interaction between complexes and BSA.

  5. Mesoporous carbon-containing voltammetric biosensor for determination of tyramine in food products

    OpenAIRE

    Kochana, Jolanta; Wapiennik, Karolina; Knihnicki, Paweł; Pollap, Aleksandra; Janus, Paula; Oszajca, Marcin; Kuśtrowski, Piotr

    2016-01-01

    A voltammetric biosensor based on tyrosinase (TYR) was developed for determination of tyramine. Carbon material (multi-walled carbon nanotubes or mesoporous carbon CMK-3-type), polycationic polymer—i.e., poly(diallyldimethylammonium chloride) (PDDA), and Nafion were incorporated into titania dioxide sol (TiO2) to create an immobilization matrix. The features of the formed matrix were studied by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The analytical performance of the d...

  6. A voltammetric and mathematical analysis of histaminergic modulation of serotonin in the mouse hypothalamus.

    Science.gov (United States)

    Samaranayake, Srimal; Abdalla, Aya; Robke, Rhiannon; Nijhout, H Frederik; Reed, Michael C; Best, Janet; Hashemi, Parastoo

    2016-08-01

    Histamine and serotonin are neuromodulators which facilitate numerous, diverse neurological functions. Being co-localized in many brain regions, these two neurotransmitters are thought to modulate one another's chemistry and are often implicated in the etiology of disease. Thus, it is desirable to interpret the in vivo chemistry underlying neurotransmission of these two molecules to better define their roles in health and disease. In this work, we describe a voltammetric approach to monitoring serotonin and histamine simultaneously in real time. Via electrical stimulation of the axonal bundles in the medial forebrain bundle, histamine release was evoked in the mouse premammillary nucleus. We found that histamine release was accompanied by a rapid, potent inhibition of serotonin in a concentration-dependent manner. We developed mathematical models to capture the experimental time courses of histamine and serotonin, which necessitated incorporation of an inhibitory receptor on serotonin neurons. We employed pharmacological experiments to verify that this serotonin inhibition was mediated by H3 receptors. Our novel approach provides fundamental mechanistic insights that can be used to examine the full extent of interconnectivity between histamine and serotonin in the brain. Histamine and serotonin are co-implicated in many of the brain's functions. In this paper, we develop a novel voltammetric method for simultaneous real-time monitoring of histamine and serotonin in the mouse premammillary nucleus. Electrical stimulation of the medial forebrain bundle evokes histamine and inhibits serotonin release. We show voltammetrically, mathematically, and pharmacologically that this serotonin inhibition is H3 receptor mediated.

  7. Voltammetric determination of Δ9-THC in glassy carbon electrode: An important contribution to forensic electroanalysis.

    Science.gov (United States)

    Balbino, Marco Antonio; de Menezes, Matheus Manoel Teles; Eleotério, Izabel Cristina; Saczk, Adelir Aparecida; Okumura, Leonardo Luiz; Tristão, Heloísa Maria; de Oliveira, Marcelo Firmino

    2012-09-10

    A new voltammetric method for the determination of Δ(9)-tetrahydrocannabinol (Δ(9)-THC) is described. The voltammetric experiments were accomplished in N-N dimethylformamide/water (9:1, v/v), using tetrabutylammonium tetrafluoroborate (TBATFB) 0.1mol/L as supporting electrolyte and a glassy carbon disk electrode as the working electrode. The anodic peak current was observed at 0.0V (vs. Ag/AgCl) after a 30s pre-concentration step under an applied potential of -1.2V (vs. Ag/AgCl). A linear dependence of Δ(9)-THC detection was obtained in the concentration range 2.4-11.3ng/mL, with a linear correlation coefficient of 0.999 and a detection limit of 0.34ng/mL. The voltammetric method was used to measure the content of Δ(9)-THC in samples (hemp and hashish) confiscated by the police. The elimination of chemical interferences from the samples was promptly achieved through prior purification using the TLC technique, by employing methanol/water (4:1, v/v) as the mobile phase. The results showed excellent correlation with results attained by HPLC.

  8. A zeolite modified carbon paste electrode as useful sensor for voltammetric determination of acetaminophen

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadpour-Mobarakeh, Leila; Nezamzadeh-Ejhieh, Alireza, E-mail: arnezamzadeh@iaush.ac.ir

    2015-04-01

    The voltammetric behavior of a carbon paste electrode modified with Co(II)-exchanged zeolite A (Co(II)-A/ZMCPE) for determination of acetaminophen was studied. The proposed electrode showed a diffusion controlled reaction with the electron transfer rate constant (K{sub s}) of 0.44 s{sup −1} and charge transfer coefficient of 0.73 in the absence of acetaminophen. A linear voltammetric response was obtained in the range of 0.1 to 190 μmol L{sup −1} of acetaminophen [r{sup 2} = 0.9979, r = 0.9989 (n = 10)] with a detection limit of 0.04 μmol L{sup −1}. The method was successfully applied to the analysis of acetaminophen in some drugs. - Highlights: • Modified carbon paste electrode with Co(II)-zeolite A improved the voltammetric current in determination of acetaminophen. • Modified electrode is applicable for acetaminophen in real samples. • The proposed method has good reproducibility and repeatability.

  9. Buffer strips in composites at elevated temperature

    Science.gov (United States)

    Bigelow, C. A.

    1983-01-01

    The composite material 'buffer strip' concept is presently investigated at elevated temperatures for the case of graphite/polyimide buffer strip panels using a (45/0/45/90)2S layup, where the buffer strip material was 0-deg S-glass/polyimide. Each panel was loaded in tension until it failed, and radiographs and crack opening displacements were recorded during the tests to determine fracture onset, fracture arrest, and the extent of damage in the buffer strip after crack arrest. At 177 + or - 3 C, the buffer strips increased the panel strength by at least 40 percent in comparison with panels without buffer strips. Compared to similar panels tested at room temperature, those tested at elevated temperature had lower residual strengths, but higher failure strains.

  10. 3D silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Parzefall, Ulrich [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany)], E-mail: ulrich.parzefall@physik.uni-freiburg.de; Bates, Richard [University of Glasgow, Department of Physics and Astronomy, Glasgow G12 8QQ (United Kingdom); Boscardin, Maurizio [FBK-irst, Center for Materials and Microsystems, via Sommarive 18, 38050 Povo di Trento (Italy); Dalla Betta, Gian-Franco [INFN and Universita' di Trento, via Sommarive 14, 38050 Povo di Trento (Italy); Eckert, Simon [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); Eklund, Lars; Fleta, Celeste [University of Glasgow, Department of Physics and Astronomy, Glasgow G12 8QQ (United Kingdom); Jakobs, Karl; Kuehn, Susanne [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); Lozano, Manuel [Instituto de Microelectronica de Barcelona, IMB-CNM, CSIC, Barcelona (Spain); Pahn, Gregor [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); Parkes, Chris [University of Glasgow, Department of Physics and Astronomy, Glasgow G12 8QQ (United Kingdom); Pellegrini, Giulio [Instituto de Microelectronica de Barcelona, IMB-CNM, CSIC, Barcelona (Spain); Pennicard, David [University of Glasgow, Department of Physics and Astronomy, Glasgow G12 8QQ (United Kingdom); Piemonte, Claudio; Ronchin, Sabina [FBK-irst, Center for Materials and Microsystems, via Sommarive 18, 38050 Povo di Trento (Italy); Szumlak, Tomasz [University of Glasgow, Department of Physics and Astronomy, Glasgow G12 8QQ (United Kingdom); Zoboli, Andrea [INFN and Universita' di Trento, via Sommarive 14, 38050 Povo di Trento (Italy); Zorzi, Nicola [FBK-irst, Center for Materials and Microsystems, via Sommarive 18, 38050 Povo di Trento (Italy)

    2009-06-01

    While the Large Hadron Collider (LHC) at CERN has started operation in autumn 2008, plans for a luminosity upgrade to the Super-LHC (sLHC) have already been developed for several years. This projected luminosity increase by an order of magnitude gives rise to a challenging radiation environment for tracking detectors at the LHC experiments. Significant improvements in radiation hardness are required with respect to the LHC. Using a strawman layout for the new tracker of the ATLAS experiment as an example, silicon strip detectors (SSDs) with short strips of 2-3 cm length are foreseen to cover the region from 28 to 60 cm distance to the beam. These SSD will be exposed to radiation levels up to 10{sup 15}N{sub eq}/cm{sup 2}, which makes radiation resistance a major concern for the upgraded ATLAS tracker. Several approaches to increasing the radiation hardness of silicon detectors exist. In this article, it is proposed to combine the radiation hard 3D-design originally conceived for pixel-style applications with the benefits of the established planar technology for strip detectors by using SSDs that have regularly spaced doped columns extending into the silicon bulk under the detector strips. The first 3D SSDs to become available for testing were made in the Single Type Column (STC) design, a technological simplification of the original 3D design. With such 3D SSDs, a small number of prototype sLHC detector modules with LHC-speed front-end electronics as used in the semiconductor tracking systems of present LHC experiments were built. Modules were tested before and after irradiation to fluences of 10{sup 15}N{sub eq}/cm{sup 2}. The tests were performed with three systems: a highly focused IR-laser with 5{mu}m spot size to make position-resolved scans of the charge collection efficiency, an Sr{sup 90}{beta}-source set-up to measure the signal levels for a minimum ionizing particle (MIP), and a beam test with 180 GeV pions at CERN. This article gives a brief overview of

  11. Stripping, Sex, and Popular Culture

    OpenAIRE

    Roach, Catherine M.

    2007-01-01

    At the heart of Stripping, Sex, and Popular Culture lies a very personal story, of author Catherine Roach's response to the decision of her life-long best friend to become an exotic dancer. Catherine and Marie grew up together in Canada and moved to the USA to enroll in PhD programs at prestigious universities. For various reasons, Marie left her program and instead chose to work as a stripper. The author, at first troubled and yet fascinated by her friend's decision, follows Marie's journey ...

  12. A new multi-strip ionization chamber used as online beam monitor for heavy ion therapy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhiguo [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Mao, Ruishi [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China); Duan, Limin, E-mail: lmduan@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China); She, Qianshun; Hu, Zhengguo; Li, He; Lu, Ziwei; Zhao, Qiecheng; Yang, Herun; Su, Hong; Lu, Chengui; Hu, Rongjiang; Zhang, Junwei [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China)

    2013-11-21

    A multi-strip ionization chamber has been built for precise and fast monitoring of the carbon beam spatial distribution at Heavy Ion Researched Facility of Lanzhou Cooling Storing Ring (HIRFL-CSR). All the detector's anode, cathode and sealed windows are made by 2μm aluminized Mylar film in order to minimize the beam lateral deflection. The sensitive area of the detector is (100×100)mm{sup 2}, with the anode segmented in 100 strips, and specialized front-end electronics has been developed for simplifying the data acquisition and quick feedback of the relevant parameters to beam control system. It can complete one single beam profile in 200μs.

  13. Nanostructured lanthanum manganate composite cathode

    DEFF Research Database (Denmark)

    Wang, Wei Guo; Liu, Yi-Lin; Barfod, Rasmus

    2005-01-01

    Anode-supported cells were fabricated with optimized cathodes showing high power density of 1.2 W/cm(2) at 800 C under a cell voltage of 0.7 V and an active area of 4 x 4 cm. A microstructure study was performed on such cell using a field-emission gun scanning electron microscope, which revealed...... that the (La1-xSrx)(y)MnO3 +/-delta (LSM) composite cathodes consist of a network of homogenously distributed LSM, yttria-stabilized zirconia (YSZ), and pores. The individual grain size of LSM or YSZ is approximately 100 nm. The degree of contact between cathode and electrolyte is 39% on average. (c) 2005...

  14. Differential pulse anodic stripping voltammetry for detection of As (III) by Chitosan-Fe(OH)3 modified glassy carbon electrode: A new approach towards speciation of arsenic.

    Science.gov (United States)

    Saha, Suparna; Sarkar, Priyabrata

    2016-09-01

    An efficient electrochemical sensor for As(III) was developed based on adsorption of arsenic on a specially modified electrodes at some applied potential and subsequent i) stripping at a fixed potential by anodic stripping voltammetry ii) analysis by generating surface plasmon resonance (SPR). The working glassy carbon electrode was modified by Chitosan-Fe(OH)3 composite and a reducing agent L-cysteine. The composite enhanced adsorption of As(III) and subsequent reduction to As(O) moieties and measurement by anodic stripping. The surface property of modified electrode was characterized by SEM, AFM, FTIR, XPS and electrochemistry was analyzed by impedance spectroscopy (EIS). Surface Plasmon resonance (SPR) was also employed to investigate the As(III) binding capability of polymer matrix. Several optimum voltammetric parameters e.g supporting electrolyte; 0.1M acetate buffer (pH 5.2) deposition potential, -0.9V; deposition time, 100s were established for anodic stripping voltammetry (ASV). A linear correlation was obtained in the range of 2-100ppb for ASV (R(2) 0.974) with limit of detection 0.072ppb. A variety of common coexistent ions such as Mn, Zn, Pb, Cu, Cd in water samples showed no interferences on the As (III) determination. The method was applied successfully to real samples collected from arsenic affected areas of West Bengal, India.

  15. Reservoir Cathode for Electric Space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a reservoir cathode to improve performance in both ion and Hall-effect thrusters. We propose to adapt our existing reservoir cathode technology to this...

  16. Reservoir Cathode for Electric Space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a hollow reservoir cathode to improve performance in ion and Hall thrusters. We will adapt our existing reservoir cathode technology to this purpose....

  17. High-current-density, high brightness cathodes for free electron laser applications

    Energy Technology Data Exchange (ETDEWEB)

    Green, M.C. (Varian Associates, Palo Alto, CA (USA). Palo Alto Microwave Tube Div.)

    1987-06-01

    This report discusses the following topics: brightness and emittance of electron beams and cathodes; general requirements for cathodes in high brightness electron guns; candidate cathode types; plasma and field emission cathodes; true field emission cathodes; oxide cathodes; lanthanum hexaborides cathodes; laser driven thermionic cathodes; laser driven photocathodes; impregnated porous tungsten dispenser cathodes; and choice of best performing cathode types.

  18. Mechanistic Enhancement of SOFC Cathode Durability

    Energy Technology Data Exchange (ETDEWEB)

    Wachsman, Eric [Univ. of Maryland, College Park, MD (United States)

    2016-02-01

    Durability of solid oxide fuel cells (SOFC) under “real world” conditions is an issue for commercial deployment. In particular cathode exposure to moisture, CO2, Cr vapor (from interconnects and BOP), and particulates results in long-term performance degradation issues. Here, we have conducted a multi-faceted fundamental investigation of the effect of these contaminants on cathode performance degradation mechanisms in order to establish cathode composition/structures and operational conditions to enhance cathode durability.

  19. Solidification Structure of Low Carbon Steel Strips with Different Phosphorus Contents Produced by Strip Casting

    Institute of Scientific and Technical Information of China (English)

    Na LI; Zhenyu LIU; Yiqing QIU; Zhaosen LIN; Xianghua LIU; Guodong WANG

    2006-01-01

    In the present paper, low carbon steel strips with different phosphorus contents were produced using a twin roll strip casting process. The solidification structure was studied and its features were analyzed in detail. It was found that the strips possessed a fine microstructure compared with the mould cast steels. With increasing phosphorus content more ferrite has been formed with finer grains.

  20. Novel Cathodes Prepared by Impregnation Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Eduardo Paz

    2006-09-30

    (1) We showed that similar results were obtained when using various LSM precursors to produce LSM-YSZ cathodes. (2) We showed that enhanced performance could be achieved by adding LSCo to LSMYSZ cathodes. (3) We have preliminary results showing that there is a slow deactivation with LSFYSZ cathodes.

  1. 7 CFR 29.6041 - Strips.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strips. 29.6041 Section 29.6041 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6041 Strips. The sides of a tobacco leaf from which the stem has...

  2. 33 CFR 157.128 - Stripping system.

    Science.gov (United States)

    2010-07-01

    ... of the following devices for stripping oil from each cargo tank: (1) A positive displacement pump. (2) A self-priming centrifugal pump. (3) An eductor (4) Any other device accepted by the Commandant. (d... positive displacement pump or a self-priming centrifugal pump, the stripping system must have the...

  3. Hardy inequalities in strips on ruled surfaces

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available We consider the Dirichlet Laplacian in infinite two-dimensional strips defined as uniform tubular neighbourhoods of curves on ruled surfaces. We show that the negative Gauss curvature of the ambient surface gives rise to a Hardy inequality and we use this to prove certain stability of spectrum in the case of asymptotically straight strips about mildly perturbed geodesics.

  4. Water problems in Gaza Strip,Palestine

    Institute of Scientific and Technical Information of China (English)

    Ismail ALGHALBAN

    2001-01-01

    The only source for water in Gaza strip, southern Palestine, is the groundwater aquifer. The Pliocene - Pleistocene aquifer has two serious problems: quantity and quality. This study is an attempt to identify the problems and to suggest solutions for water problems in Gaza strip. In addition, some rules for rehabilitation of the aquifers were suggested.

  5. Tactual Strip Maps as Navigational Aids.

    Science.gov (United States)

    Golledge, R. G.

    1991-01-01

    This article reviews the history and use of tactual maps by blind and visually impaired travelers. It discusses textual patterns, symbols, and graphics; differences between conventional geographic-cartographic maps and strip maps used as navigational aids; and current advances, including disposable, quick-to-produce, and easy-to-update strip maps.…

  6. Microhollow Cathode Discharge Excimer Lamps

    Science.gov (United States)

    Schoenbach, K. H.

    1999-11-01

    character. Reducing the diameter of the cathode hole in a hollow cathode discharge geometry to values on the order of 100 μm has allowed us to extend the pressure range of stable, direct current hollow cathode gas discharges up to atmospheric pressure. The large concentration of high-energy electrons generated in the cathode fall, in combination with the high neutral gas density favors three-body processes such as excimer formation. Excimer emission in xenon discharges peaking at 172 nm, was observed with efficiencies between 6% and 9% at pressures of several hundred Torr. Typical forward voltages are 200 V at dc currents up to 8 mA. Pulsed operation allowed us to extend the current range to 80 mA with corresponding linear increase in optical power. Spatially resolved measurements showed that the source of the excimer radiation at atmospheric pressure and currents of less than 8 mA is confined to the cathode opening. The radiative emittance at 8 mA and atmospheric pressure is approximately 20 W/cm^2. With reduced pressure and increased current, respectively, the excimer source extends into the area outside the cathode hole. Besides in xenon, excimer emission in argon at a peak wavelength of 128 nm has been recorded. In addition to operating the discharge in rare gases, we have also explored its use as rare gas-halide excimer source. In a gas mixture containing 1% ArF we were able to generate stable dc discharges in flowing gas at pressures ranging from 100 Torr to atmospheric pressure. The spectra of the high-pressure ArF discharges are dominated by excimer radiation peaking at 193 nm. The excimer emission of a single ArF discharge at 700 Torr was measured as 150 mW at an efficiency of 3%. Parallel operation of these discharges by means of a resistive anode, which has recently been demonstrated for argon discharges, offers the possibility to use microhollow cathode discharge arrays as dc-excimer lamps, with estimated power densities exceeding 10 W/cm^2. abstract

  7. Spectroscopic studies of cathode materials for lithium-ion batteries

    Science.gov (United States)

    Totir, Dana Alexa

    2000-10-01

    Structural changes that occur during electrochemical cycling of lithium-ion battery cathode materials have been investigated using in situ spectroscopic techniques. A new method was developed for the preparation of carbon and binder free cathodes utilizing powder materials of interest for commercial batteries. The extraordinary quality of the cyclic voltammetric curves recorded for this type of electrodes during the in situ measurements allows direct correlations to be made between the state of charge of the material and its structural and electronic characteristics. LiCoO2, LiMn2O4 and LiCo0.15Ni 0.85O2 electrodes were evaluated using cycling voltammetry and the mean diffusion coefficient for Li-ions in the lattice (DLi) was calculated for LiMn2O4. LiMn2O4 electrodes prepared by this technique have been studied in situ using Mn K-edge XAS. Data analysis for the species formed at different potentials indicated a contraction of the lattice associated with the increase in the oxidation state of manganese. In situ Raman spectra of particles of LiMn2O 4, and LiCoO2 embedded in Au and also of KS-44 graphite and carbon microfibers MCF28 embedded in thermally annealed Ni have been recorded as a function of the applied potential. Fe K-edge XAFS of pyrite electrodes in a Li/PEO(LiClO4)/FeS 2 cell and S K-edge XANES measurements of a FeS2 electrode in a non-aqueous electrolyte have been acquired as a function of the state of charge. The studies have clearly evidenced the formation of metallic Fe and Li2S as intermediates after 4 e- discharge and the formation of Li2FeS2 after 2 e- recharge. While Fe K-edge studies have indicated that there is no change in the Fe environment and oxidation state upon 4 e- recharge, the results obtained from S K-edge studies are inconclusive for this stage. Finally, in situ Co K-edge XAFS data were obtained for the first time during the electrochemical cycling of electrodeposited Co(OH) 2 films in alkaline solutions. The results support

  8. A direct in situ fingerprinting method for acid rock drainage using voltammetric techniques with a single renewable gold microelectrode.

    Science.gov (United States)

    Nuzzio, Donald B; Zettler, Erik R; Aguilera, Angeles; Amaral-Zettler, Linda A

    2011-04-15

    Electrochemistry allows for rapid identification of multiple metals and other chemical complexes common in acid rock drainage (ARD) systems. Voltammetric scans using a single gold microelectrode of water samples from geochemically distinct areas of the Río Tinto (RT) in southwestern Spain were clearly recognizable in the field and in samples stored at room temperature for over 6 months. Major voltammetric peaks of iron(III) and copper(II) were identified on a single constantly renewable gold microelectrode. Confirmation of these peaks was performed by spiking with standard metal solutions in the laboratory. This voltammetric technique is a rapid, direct and inexpensive in situ method for identification of water sources and their chemical characteristics, as well as an economical way to monitor environmental changes and remediation efforts.

  9. Fusion of Potentiometric & Voltammetric Electronic Tongue for Classification of Black Tea Taste based on Theaflavins (TF) Content

    Science.gov (United States)

    Bhattacharyya, Nabarun; Legin, Andrey; Papieva, Irina; Sarkar, Subrata; Kirsanov, Dmitry; Kartsova, Anna; Ghosh, Arunangshu; Bandyopadhyay, Rajib

    2011-09-01

    Black tea is an extensively consumed beverage worldwide with an expanding market. The final quality of black tea depends upon number of chemical compounds present in the tea. Out of these compounds, theaflavins (TF), which is responsible for astringency in black tea, plays an important role in determining the final taste of the finished black tea. The present paper reports our effort to correlate the theaflavins contents with the voltammetric and potentiometric electronic tongue (e-tongue) data. Noble metal-based electrode array has been used for collecting data though voltammetric electronic tongue where as liquid filled membrane based electrodes have been used for potentiometric electronic tongue. Black tea samples with tea taster score and biochemical results have been collected from Tea Research Association, Tocklai, India for the analysis purpose. In this paper, voltammetric and potentiometric e-tongue responses are combined to demonstrate improvement of cluster formation among tea samples with different ranges of TF values.

  10. Thin film passivation of laser generated 3D micro patterns in lithium manganese oxide cathodes

    Science.gov (United States)

    Pröll, J.; Kohler, R.; Bruns, M.; Oberst, V.; Weidler, P. G.; Heißler, S.; Kübel, C.; Scherer, T.; Prang, R.; Seifert, H. J.; Pfleging, W.

    2013-03-01

    The increasing need for long-life lithium-ion batteries requires the further development of electrode materials. Especially on the cathode side new materials or material composites are needed to increase the cycle lifetime. On the one hand, spinel-type lithium manganese oxide is a promising candidate to be used as cathode material due to its non-toxicity, low cost and good thermal stability. On the other hand, the spinel structure suffers from change in the oxidation state of manganese during cycling which is also accompanied by loss of active material into the liquid electrolyte. The general trend is to enhance the active surface area of the cathode in order to increase lithium-ion mobility through the electrode/electrolyte interface, while an enhanced surface area will also promote chemical degradation. In this work, laser microstructuring of lithium manganese oxide thin films was applied in a first step to increase the active surface area. This was done by using 248 nm excimer laser radiation and chromium/quartz mask imaging techniques. In a second step, high power diode laser-annealing operating at a wavelength of 940 nm was used for forming a cubic spinel-like battery phase. This was verified by means of Raman spectroscopy and cyclic voltammetric measurements. In a last step, the laser patterned thin films were coated with indium tin oxide (ITO) layers with a thickness of 10 nm to 50 nm. The influence of the 3D surface topography as well as the ITO thickness on the electrochemical performance was studied by cyclic voltammetry. Post-mortem studies were carried out by using scanning electron microscopy and focused ion beam analysis.

  11. Determination of total polyphenol index in wines employing a voltammetric electronic tongue

    Energy Technology Data Exchange (ETDEWEB)

    Ceto, Xavier [Sensors and Biosensors Group, Department of Chemistry, Universitat Autonoma de Barcelona, Edifici Cn, 08193 Bellaterra (Spain); Gutierrez, Juan Manuel [Bioelectronics Section, Department of Electrical Engineering, CINVESTAV, 07360 Mexico D.F. (Mexico); Gutierrez, Manuel [Instituto de Microelectronica de Barcelona (IMB-CNM), CSIC, 08193 Bellaterra (Spain); Cespedes, Francisco [Sensors and Biosensors Group, Department of Chemistry, Universitat Autonoma de Barcelona, Edifici Cn, 08193 Bellaterra (Spain); Capdevila, Josefina; Minguez, Santiago [Estacio de Viticultura i Enologia, INCAVI, Vilafranca del Penedes (Spain); Jimenez-Jorquera, Cecilia [Instituto de Microelectronica de Barcelona (IMB-CNM), CSIC, 08193 Bellaterra (Spain); Valle, Manel del, E-mail: manel.delvalle@uab.cat [Sensors and Biosensors Group, Department of Chemistry, Universitat Autonoma de Barcelona, Edifici Cn, 08193 Bellaterra (Spain)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Array of voltammetric sensors modified with nanoparticles or conducting polymers. Black-Right-Pointing-Pointer It has been applied in wine analysis to predict polyphenol content index. Black-Right-Pointing-Pointer Uses data processing tools such as discrete wavelet transform and artificial neural network. Black-Right-Pointing-Pointer Identification of phenolics like gallic acid, catechin, caffeic acid, catechol. Black-Right-Pointing-Pointer Predicted polyphenol index agrees with Folin-Ciocalteau method and I{sub 280} index. - Abstract: This work reports the application of a voltammetric electronic tongue system (ET) made from an array of modified graphite-epoxy composites plus a gold microelectrode in the qualitative and quantitative analysis of polyphenols found in wine. Wine samples were analyzed using cyclic voltammetry without any sample pretreatment. The obtained responses were preprocessed employing discrete wavelet transform (DWT) in order to compress and extract significant features from the voltammetric signals, and the obtained approximation coefficients fed a multivariate calibration method (artificial neural network-ANN-or partial least squares-PLS-) which accomplished the quantification of total polyphenol content. External test subset samples results were compared with the ones obtained with the Folin-Ciocalteu (FC) method and UV absorbance polyphenol index (I{sub 280}) as reference values, with highly significant correlation coefficients of 0.979 and 0.963 in the range from 50 to 2400 mg L{sup -1} gallic acid equivalents, respectively. In a separate experiment, qualitative discrimination of different polyphenols found in wine was also assessed by principal component analysis (PCA).

  12. Voltammetric sensor for vanillylmandelic acid based on molecularly imprinted polymer-modified electrodes.

    Science.gov (United States)

    Blanco-López, M C; Lobo-Castañón, M J; Miranda-Ordieres, A J; Tuñón-Blanco, P

    2003-04-01

    Despite the increasing number of applications of molecularly imprinted polymers (MIPs) in analytical chemistry, the construction of a biomimetic voltammetric sensor remains still challenging. This work investigates the development of a voltammetric sensor for vanillylmandelic acid (VMA) based on acrylic MIP-modified electrodes. Thin layers of MIPs for VMA have been prepared by spin coating the surface of a glassy carbon electrode with the monomers mixture (template, methacrylic acid, a cross-linking agent and solvent), followed by in situ photopolymerisation. After extraction of the template molecule, the peak current recorded with the imprinted sensor after rebinding was linear with VMA concentration in the range 19-350 microg ml(-1), whereas the response of the control electrode is independent of incubation concentration, and was about one-tenth of the value recorded with the imprinted sensor at the maximum concentration tested. Under the conditions used, the sensor is able to differentiate between VMA and other closely structural-related compounds, such as 3-methoxy-4-hydroxyphenylethylene glycol (not detected), or 3,4- and 2,5-dihydroxyphenilacetic acids, which are adsorbed on the bare electrode surface but not at the polymer layer. Homovanillic acid was detected with the imprinted sensors after incubation, indicating that the presence of both methoxy and carboxylic groups in the same position as in VMA is necessary for effective binding in the imprinted sites. Nevertheless, both species can be differentiated by the oxidation potential. It can be concluded that MIP-based voltammetric electrodes are very promising analytical tool for the development of highly selective analytical sensors.

  13. A New Voltammetric Enzyme Immunoassay System for the Detection of Alkaline Phosphatase

    Institute of Scientific and Technical Information of China (English)

    KuiJIAO; WeiSUN; 等

    2002-01-01

    A new voltammetric enzyme immunoassay system was invesigated based on p-nitrophenyl phosphate (PNPP) as the subsrate for alkaline phosphatase (ALP). PNPP is enzymatically hydrolyzed and the product p-nitrophenol (PNP) is detected by differential pulse voltammetry (DPV), which can be oxidized at +1.02 V(vs.Ag/AgCl) on bare glass carbon electrode (GCE). The conditions for enzymatic reaction and electrochemical detection were studied. According to this method,ALP can be detected with a detection limit of 2.8×102 mU/L and a linear range of 4.0×102-1.0×106mU/L.

  14. A New Voltammetric Enzyme Immunoassay System for the Detection of Alkaline Phosphatase

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new voltammetric enzyme immunoassay system was investigated based on p-nitrophenyl phosphate (PNPP) as the substrate for alkaline phosphatase (ALP). PNPP is enzymatically hydrolyzed and the product p-nitrophenol (PNP) is detected by differential pulse voltammetry (DPV), which can be oxidized at +1.02 V (vs. Ag/AgCl) on bare glass carbon electrode (GCE). The conditions for enzymatic reaction and electrochemical detection were studied. According to this method, ALP can be detected with a detection limit of 2.8′102 mU/L and a linear range of 4.0′102 ~ 1.0′106 mU/L.

  15. Circuit realization microwave antennas-oscillator on strip antennas

    OpenAIRE

    Golynskyy, V. D.; Prudyus, I. N.

    2009-01-01

    Showing special feature of development circuitries microwave transistors antennasoscillator on strip dielectric-resonator-antennas. Showing circuitries and technical characteristics of developed microwave antennasoscillator on strip.

  16. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

    2002-03-31

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. This period has continued to address the problem of making dense 1/2 to 5 {micro}m thick dense layers on porous substrates (the cathode LSM). Our current status is that we are making structures of 2-5 cm{sup 2} in area, which consist of either dense YSZ or CGO infiltrated into a 2-5 {micro}m thick 50% porous layer made of either nanoncrystalline CGO or YSZ powder. This composite structure coats a macroporous cathode or anode; which serves as the structural element of the bi-layer structure. These structures are being tested as SOFC elements. A number of structures have been evaluated both as symmetrical and as button cell configuration. Results of this testing indicates that the cathodes contribute the most to cell losses for temperatures below 750 C. In this investigation different cathode materials were studied using impedance spectroscopy of symmetric cells and IV characteristics of anode supported fuel cells. Cathode materials studied included La{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF), La{sub 0.7}Sr{sub 0.2}MnO{sub 3} (LSM), Pr{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}O{sub 3} (PSCF), Sm{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF), and Yb{sub .8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF). A new technique for filtering the Fourier transform of impedance data was used to increase the sensitivity of impedance analysis. By creating a filter specifically for impedance spectroscopy the resolution was increased. The filter was tailored to look for specific circuit elements like R//C, Warburg, or constant phase elements. As many as four peaks can be resolved using the filtering technique on symmetric cells. It may be possible to relate the different peaks to material parameters, like the oxygen exchange coefficient. The cathode grouped in order from lowest to highest ASR is

  17. Cathodic Stripping Voltammetry of Thioamides on a Rotating Silver Disk Electrode.

    Science.gov (United States)

    1984-01-01

    MAR 2 1 ൒34 18 SUPPLEMENTARY NOTES Prepared for publication in the Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 19 KEY...Publication in Journal Electroanalytical Chemistry And Interfacial Electrochemistry Department of Chemistry State University of New York at Buffalo

  18. Large amplitude Fourier transformed AC voltammetric investigation of the active state electrochemistry of a copper/aqueous base interface and implications for electrocatalysis.

    Science.gov (United States)

    Shiddiky, Muhammad J A; O'Mullane, Anthony P; Zhang, Jie; Burke, L Declan; Bond, Alan M

    2011-08-16

    The higher harmonic components available from large-amplitude Fourier-transformed alternating current (FT-ac) voltammetry enable the surface active state of a copper electrode in basic media to be probed in much more detail than possible with previously used dc methods. In particular, the absence of capacitance background current allows low-level Faradaic current contributions of fast electron-transfer processes to be detected; these are usually completely undetectable under conditions of dc cyclic voltammetry. Under high harmonic FT-ac voltammetric conditions, copper electrodes exhibit well-defined and reversible premonolayer oxidation responses at potentials within the double layer region in basic 1.0 M NaOH media. This process is attributed to oxidation of copper adatoms (Cu*) of low bulk metal lattice coordination numbers to surface-bonded, reactive hydrated oxide species. Of further interest is the observation that cathodic polarization in 1.0 M NaOH significantly enhances the current detected in each of the fundamental to sixth FT-ac harmonic components in the Cu*/Cu hydrous oxide electron-transfer process which enables the underlying electron transfer processes in the higher harmonics to be studied under conditions where the dc capacitance response is suppressed; the results support the incipient hydrous oxide adatom mediator (IHOAM) model of electrocatalysis. The underlying quasi-reversible interfacial Cu*/Cu hydrous oxide process present under these conditions is shown to mediate the reduction of nitrate at a copper electrode, while the mediator for the hydrazine oxidation reaction appears to involve a different mediator or active state redox couple. Use of FT-ac voltammetry offers prospects for new insights into the nature of active sites and electrocatalysis at the electrode/solution interface of Group 11 metals in aqueous media.

  19. A Strip Cell in Pyroelectric Devices

    Directory of Open Access Journals (Sweden)

    An-Shen Siao

    2016-03-01

    Full Text Available The pyroelectric effect affords the opportunity to convert temporal temperature fluctuations into usable electrical energy in order to develop abundantly available waste heat. A strip pyroelectric cell, used to enhance temperature variation rates by lateral temperature gradients and to reduce cell capacitance to further promote the induced voltage, is described as a means of improving pyroelectric energy transformation. A precision dicing saw was successfully applied in fabricating the pyroelectric cell with a strip form. The strip pyroelectric cell with a high-narrow cross section is able to greatly absorb thermal energy via the side walls of the strips, thereby inducing lateral temperature gradients and increasing temperature variation rates in a thicker pyroelectric cell. Both simulation and experimentation show that the strip pyroelectric cell improves the electrical outputs of pyroelectric cells and enhances the efficiency of pyroelectric harvesters. The strip-type pyroelectric cell has a larger temperature variation when compared to the trenched electrode and the original type, by about 1.9 and 2.4 times, respectively. The measured electrical output of the strip type demonstrates a conspicuous increase in stored energy as compared to the trenched electrode and the original type, by of about 15.6 and 19.8 times, respectively.

  20. Transfusion and blood donation in comic strips.

    Science.gov (United States)

    Lefrère, Jean-Jacques; Danic, Bruno

    2013-07-01

    The representation of blood transfusion and donation of blood in the comic strip has never been studied. The comic strip, which is a relatively recent art, emerged in the 19th century before becoming a mass medium during the 20th century. We have sought, by calling on collectors and using the resources of Internet, comic strips devoted, wholly or in part, to the themes of transfusion and blood donation. We present some of them here in chronologic order, indicating the title, country of origin, year of publication, and names of authors. The theme of the superhero using transfusion to transmit his virtues or his powers is repeated throughout the 20th century in North American comic strips. More recently, comic strips have been conceived from the outset with a promotional aim. They perpetuate positive images and are directed toward a young readership, wielding humor to reduce the fear of venipuncture. Few comic strips denounce the abuse of the commercialization of products derived from the human body. The image of transfusion and blood donation given by the comic strips is not to be underestimated because their readership is primarily children, some of whom will become blood donors. Furthermore, if some readers are transfused during their lives, the impact of a memory more or less conscious of these childhood readings may resurface, both in hopes and in fears.

  1. Determination of copper in whole blood by differential pulse adsorptive stripping voltammetry

    Directory of Open Access Journals (Sweden)

    Tarik Attar

    2014-02-01

    Full Text Available A selective and sensitive method for determination of copper in blood by adsorptive differential pulse cathodic stripping voltammetry is presented. The method is based on adsorptive accumulation of the complexes of Cu (II ions with benzenesulfonyl hydrazide onto hanging mercury drop electrode (HMDE, followed by the reduction of the adsorbed species by differential pulse cathodic stripping voltammetry. The effect of various parameters such as supporting electrolyte, concentration of benzenesulfonyl hydrazide, accumulation potential, accumulation time and stirring rate on the selectivity and sensitivity were studied. The optimum conditions for determination of copper include perchloric acid 0.03 M, concentration of benzenesulfonyl hydrazide 7.5×10-5 M, the accumulation potential of -350 mV (vs. Ag/AgCl, the accumulation time of 50 s, and the scan rate of 50 mV s-1. Under optimized conditions, linear calibration curves were established for the concentration of Cu (II in the range of 0.62-275 ng mL-1, with detection limit of 0.186 ng mL-1 for Cu (II. The procedure was successfully applied to the determination of copper ion in whole blood samples.

  2. Small-Strip Thin Gap Chambers for the Muon Spectrometer Upgrade of the ATLAS Experiment

    CERN Document Server

    Perez Codina, Estel; The ATLAS collaboration

    2015-01-01

    For the forthcoming Phase-I upgrade to the LHC (2018/19), the first station of the ATLAS muon end-cap system, Small Wheel, needs to be replaced. The New Small Wheel (NSW) will have to operate in a high background radiation region while reconstructing muon tracks with high precision and providing information for the Level-1 trigger. In particular, the precision reconstruction of tracks requires a spatial resolution of about 100 μm, and the Level-1 trigger track segments have to be reconstructed with an angular resolution of approximately 1 mrad. The NSWs consist of eight layers each of Micromegas and small-strip Thin Gap Chambers (sTGC), both providing trigger and tracking capabilities. The single sTGC planes of a quadruplet consists of an anode layer of 50μm gold plated tungsten wire sandwiched between two resistive cathode layers. Behind one of the resistive cathode layers, a PCB with precise machined strips (thus the name sTGC) spaced every 3.2mm allows to achieve a position resolution that ranges from 70...

  3. Analytical procedure for the simultaneous voltammetric determination of trace metals in food and environmental matrices. Critical comparison with atomic absorption spectroscopic measurements.

    Science.gov (United States)

    Melucci, Dora; Torsi, Giancarlo; Locatelli, Clinio

    2007-01-01

    An analytical procedure fit for the simultaneous determination of copper (II), chromium(VI), thallium(I), lead(II), tin(II), antimony(III), and zinc(II) by square wave anodic stripping voltammetry (SWASV) in three interdependent environmental matrices involved in foods and food chain as meals, cereal plants and soils is described. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 (meals and cereal plants) and HCl-HNO3 (soils) acidic attack mixtures. 0.1 mol/L dibasic ammonium citrate pH 8.5 was employed as the supporting electrolyte. The voltammetric measurements were carried out using, as working electrode, a stationary hanging mercury drop electrode (HMDE) and a platinum electrode and an Ag/AgCl/KClsat electrode as auxiliary and reference electrodes, respectively. The analytical procedure was verified by the analyses of the standard reference materials: Wholemeal BCR-CRM 189, Tomato Leaves NIST-SRM 1573a and Montana Soil Moderately Elevated Traces NIST-SRM 2711. For all the elements in the certified matrix, the precision as repeatability, expressed as relative standard deviation (Sr %) was lower than 5%. The accuracy, expressed as percentage relative error (e %) was of the order of 3-7%, while the detection limits were in the range 0.015-0.103 microg/g. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meal samples, cereal plants and soils samples drawn in sites devoted to agricultural practice. A critical comparison with spectroscopic measurements is also discussed.

  4. Characterization of multicapillary dielectric cathodes

    Science.gov (United States)

    Gleizer, J. Z.; Hadas, Y.; Yarmolich, D.; Felsteiner, J.; Krasik, Ya. E.

    2007-04-01

    Parameters of the plasma and electron beam produced by a multicapillary cathode in a diode powered by a ˜200kV, ˜300ns pulse are presented. It was found that the source of electrons is the plasma ejected from the capillaries. Inside the capillaries this plasma obtains electron density and temperature of ˜8×1015cm-3 and ˜5eV, respectively. In the vicinity of the cathode, the density and temperature of the plasma electrons were found to be 2×1014cm-3 and 4.5eV, respectively, for electron current density of ˜40A/cm2. It was shown that the plasma expansion velocity is in the range of (1-2)×106cm/s for current density of >12A/cm2.

  5. Microhollow cathode discharge excimer lamps

    Science.gov (United States)

    Schoenbach, Karl H.; El-Habachi, Ahmed; Moselhy, Mohamed M.; Shi, Wenhui; Stark, Robert H.

    2000-05-01

    Microhollow cathode discharges are high-pressure, nonequilibrium gas discharges between a hollow cathode and a planar or hollow anode with electrode dimensions in the 100 μm range. The large concentration of high-energy electrons, in combination with the high-gas density favors excimer formation. Excimer emission was observed in xenon and argon, at wavelengths of 128 and 172 nm, respectively, and in argon fluoride and xenon chloride, at 193 and 308 nm. The radiant emittance of the excimer radiation was found to increase monotonically with pressure. However, due to the decrease in source size with pressure, the efficiency (ratio of excimer radiant power to input electrical power), has for xenon and argon fluoride a maximum at ˜400 Torr. The maximum efficiency is between 6% and 9% for xenon, and ˜2% for argon fluoride.

  6. Saving Energy Through Advanced Power Strips (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, D.

    2013-10-01

    Advanced Power Strips (APS) look just like ordinary power strips, except that they have built-in features that are designed to reduce the amount of energy used by many consumer electronics. There are several different types of APSs on the market, but they all operate on the same basic principle of shutting off the supply power to devices that are not in use. By replacing your standard power strip with an APS, you can signifcantly cut the amount of electricity used by your home office and entertainment center devices, and save money on your electric bill. This illustration summarizes the different options.

  7. High energy H- ion transport and stripping

    Energy Technology Data Exchange (ETDEWEB)

    Chou, W.; /Fermilab

    2005-05-01

    During the Proton Driver design study based on an 8 GeV superconducting RF H{sup -} linac, a major concern is the feasibility of transport and injection of high energy H{sup -} ions because the energy of H{sup -} beam would be an order of magnitude higher than the existing ones. This paper will focus on two key technical issues: (1) stripping losses during transport (including stripping by blackbody radiation, magnetic field and residual gases); (2) stripping efficiency of carbon foil during injection.

  8. THE DEVELOPMENT OF FCC STRIPPING TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    ZHANGZhen-qian

    2003-01-01

    This article briefly describes the major patents domestic and the abroad,and the current situation and achievements of FCC stripping technology in China.The develping trend of FCC stripping technology is presented,including further developments of FCC stripper to improve unit performance,combination of the stripper and pre-stripper within disengager to from a complete high-efficiency FCC stripping system.In addition to high efficiency,simple structure and easiness of installation and maintenance for a new FCC stripper are all of consideration.

  9. Determination of vanillin in commercial food product by adsorptive stripping voltammetry using a boron-doped diamond electrode.

    Science.gov (United States)

    Yardım, Yavuz; Gülcan, Mehmet; Şentürk, Zühre

    2013-12-01

    A method for the determination of food additive vanillin was developed by adsorptive stripping voltammetry. Its determination was carried out at the anodically pre-treated boron-doped diamond electrode in aqueous solutions. Using square-wave stripping mode, the compound yielded a well-defined voltammetric response in phosphate buffer, pH 2.5 at +1.14 V (vs. Ag/AgCl) (a pre-concentration step being carried out at open-circuit condition for 60s). A linear calibration graph was obtained in the concentration range of 0.5-15.0 μg mL(-1) (3.3×10(-6)-9.8×10(-5) mol L(-1)) with a detection limit of 0.024 μg mL(-1) (1.6×10(-7) mol L(-1)). As an example, the practical applicability of the proposed method was tested for the determination of this flavouring agent in commercial pudding powder of Keshkule (Turkish milk pudding with almond flour).

  10. Gas proportional detectors with interpolating cathode pad readout for high track multiplicities

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Bo

    1991-12-01

    New techniques for position encoding in very high rate particle and photon detectors will be required in experiments planned for future particle accelerators such as the Superconducting Super Collider and new, high intensity, synchrotron sources. Studies of two interpolating cathode ``pad`` readout systems are described in this thesis. They are well suited for high multiplicity, two dimensional unambiguous position sensitive detection of minimum ionizing particles and heavy ions as well as detection of x-rays at high counting rates. One of the readout systems uses subdivided rows of pads interconnected by resistive strips as the cathode of a multiwire proportional chamber (MWPC). A position resolution of less than 100 {mu}m rms, for 5.4 keV x-rays, and differential non-linearity of 12% have been achieved. Low mass ({approximately}0.6% of a radiation length) detector construction techniques have been developed. The second readout system uses rows of chevron shaped cathode pads to perform geometrical charge division. Position resolution (FWHM) of about 1% of the readout spacing and differential non-linearity of 10% for 5.4 keV x-rays have been achieved. A review of other interpolating methods is included. Low mass cathode construction techniques are described. In conclusion, applications and future developments are discussed. 54 refs.

  11. Gas proportional detectors with interpolating cathode pad readout for high track multiplicities

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Bo.

    1991-12-01

    New techniques for position encoding in very high rate particle and photon detectors will be required in experiments planned for future particle accelerators such as the Superconducting Super Collider and new, high intensity, synchrotron sources. Studies of two interpolating cathode pad'' readout systems are described in this thesis. They are well suited for high multiplicity, two dimensional unambiguous position sensitive detection of minimum ionizing particles and heavy ions as well as detection of x-rays at high counting rates. One of the readout systems uses subdivided rows of pads interconnected by resistive strips as the cathode of a multiwire proportional chamber (MWPC). A position resolution of less than 100 {mu}m rms, for 5.4 keV x-rays, and differential non-linearity of 12% have been achieved. Low mass ({approximately}0.6% of a radiation length) detector construction techniques have been developed. The second readout system uses rows of chevron shaped cathode pads to perform geometrical charge division. Position resolution (FWHM) of about 1% of the readout spacing and differential non-linearity of 10% for 5.4 keV x-rays have been achieved. A review of other interpolating methods is included. Low mass cathode construction techniques are described. In conclusion, applications and future developments are discussed. 54 refs.

  12. Voltammetric behavior of nitrofurazone and its hydroxymethyl prodrug with potential anti-Chagas activity

    Energy Technology Data Exchange (ETDEWEB)

    La-Scalea, Mauro Aquiles [Sao Paulo Univ., SP (Brazil). Faculdade de Ciencias Farmaceuticas; Sao Paulo Univ., SP (Brazil). Inst. de Quimica]. E-mail: scalea@usp.br; Menezes, Carla Maria de Souza; Ferreira, Elizabeth Igne [Sao Paulo Univ., SP (Brazil). Faculdade de Ciencias Farmaceuticas; Juliao, Murilo Sergio da Silva [Sao Paulo Univ., SP (Brazil). Inst. de Quimica; Universidade Estadual Vale do Acaraju, Fortaleza, CE (Brazil). Centro de Ciencias Exatas e Tecnologicas; Man Chin Chung [UNESP, Araraquara, SP (Brazil). Faculdade de Ciencias Farmaceuticas; Serrano, Silvia Helena Pires [Sao Paulo Univ., SP (Brazil). Inst. de Quimica

    2005-07-15

    Chagas' disease is a serious health problem for Latin America. The situation is worsened by the lack of efficient chemotherapy. The two available commercial drugs, benznidazole and nifurtimox, are more effective in the acute phase of the disease. Nitrofurazone is active against Trypanosoma cruzi, however its high toxicity precludes its current use in parasitosis. Hydroxymethyl nitrofurazone is a prodrug of nitrofurazone. It is more active against Trypanosoma cruzi than nitrofurazone, besides being less toxic. This work shows the voltammetric behavior of nitrofurazone and a comparison with those of metronidazole and chloramphenicol using cyclic, linear sweep and differential pulse voltammetries. For these drugs also the prediction of the diffusion coefficients using Wilke-Chang equation was performed. The reduction of nitrofurazone is pH-dependent and in acidic medium the hydroxylamine derivative, involving four electrons, is the principal product formed. In aqueous-alkaline medium and with a glassy carbon electrode pre-treatment the reduction of nitrofurazone occurs in two steps, the first involving one electron to form the nitro-radical anion and the second corresponding to the hydroxylamine derivative formation. Hydroxymethyl nitrofurazone presented the same voltammetric behavior and electroactivity, indicating that the molecular modification performed in nitrofurazone did not change its capacity to be reduced. A brief discussion regarding the differences in biological activity between the two compounds is also presented. (author)

  13. Voltammetric behaviour of drotaverine hydrochloride in surfactant media and its enhancement determination in Tween-20.

    Science.gov (United States)

    Jain, Rajeev; Vikas; Rather, Jahangir Ahmad

    2011-02-01

    Simple, sensitive and rapid adsorptive voltammetric behaviour of drotaverine hydrochloride onto the HMDE has been explored and validated in surfactant media by using cyclic, differential pulse and square-wave voltammetry. Addition of Tween-20 to the drotaverine hydrochloride containing electrolyte enhances the reduction current signal. The voltammograms of the drug with Tween-20 in phosphate buffers of pH 2.5-11.0 exhibit a single well defined reduction peak which may be due to the reduction of -CC- group. The cyclic voltammetric studies indicated the reduction of drotaverine hydrochloride at the electrode surface through two electron irreversible step and diffusion-controlled. The peak current showed a linear dependence with the drug concentration over the range 0.8-7.2μgmL(-1). The calculated LOD and LOQ are 1.8 and 6.0ngmL(-1) by SWCAdSV and 8.1 and 27.2ngmL(-1) by DPCAdSV, respectively. The procedure was applied to the assay of the drug in tablet form with mean percentage recoveries of 100.2% with SWCAdSV and 99.7% with DPCAdSV. The validity of the proposed methods was further assessed by applying a standard addition technique.

  14. Determination of total polyphenol index in wines employing a voltammetric electronic tongue.

    Science.gov (United States)

    Cetó, Xavier; Gutiérrez, Juan Manuel; Gutiérrez, Manuel; Céspedes, Francisco; Capdevila, Josefina; Mínguez, Santiago; Jiménez-Jorquera, Cecilia; del Valle, Manel

    2012-06-30

    This work reports the application of a voltammetric electronic tongue system (ET) made from an array of modified graphite-epoxy composites plus a gold microelectrode in the qualitative and quantitative analysis of polyphenols found in wine. Wine samples were analyzed using cyclic voltammetry without any sample pretreatment. The obtained responses were preprocessed employing discrete wavelet transform (DWT) in order to compress and extract significant features from the voltammetric signals, and the obtained approximation coefficients fed a multivariate calibration method (artificial neural network-ANN-or partial least squares-PLS-) which accomplished the quantification of total polyphenol content. External test subset samples results were compared with the ones obtained with the Folin-Ciocalteu (FC) method and UV absorbance polyphenol index (I(280)) as reference values, with highly significant correlation coefficients of 0.979 and 0.963 in the range from 50 to 2400 mg L(-1) gallic acid equivalents, respectively. In a separate experiment, qualitative discrimination of different polyphenols found in wine was also assessed by principal component analysis (PCA).

  15. Copper(II) complexes of prion protein PEG11-tetraoctarepeat fragment: spectroscopic and voltammetric studies.

    Science.gov (United States)

    Bonomo, Raffaele P; Di Natale, Giuseppe; Rizzarelli, Enrico; Tabbì, Giovanni; Vagliasindi, Laura I

    2009-04-14

    Spectroscopic (UV-Vis and EPR) and voltammetric studies have been carried out on the copper(II) complexes with the Ac-PEG11-(PHGGGWGQ)4-NH2 (L) polypeptide. In the ratios Cu : L 3 : 1 and 4 : 1, the two [Cu3(L)H(-6)] and [Cu4(L)H(-8)] complex species have been characterized at neutral pH values. All the copper atoms occupy similar coordination sites formed by imidazole, peptidic nitrogen atoms and carbonyl oxygen atoms in a square base pyramidal geometry. Voltammetric measurements on these systems point out the cooperativity in the electron transfer processes among the copper(II) sites during their reduction. NO interaction with these polynuclear copper species is characterized by the reduction of the copper sites through the formation of two different intermediate complex species. When an excess of the Ac-PEG11-(PHGGGWGQ)4-NH2 ligand is considered, frozen solution EPR parameters and UV-Vis spectroscopic data identify the [Cu(N(im))4]2+ chromophore, which does not interact with NO.

  16. Microgravimetric and voltammetric study of Zn underpotential deposition on platinum in alkaline medium

    Science.gov (United States)

    Calegaro, M. L.; Santos, M. C.; Miwa, D. W.; Machado, S. A. S.

    2005-03-01

    The microgravimetric and voltammetric responses of a polycrystalline Pt electrode in 0.1 mol L -1 NaOH solution in the presence and the absence of 1.6 × 10 -4 Zn 2+, at 0.1 V s -1 were analyzed. During the positive potential sweep, the water molecules are progressively substituted by OH - ions, prior to PtO formation. The voltammetric charges obtained under the Zn ads dissolution peaks suggest that 0.7 monolayers are deposited, with each Zn ad-atom occupying one active site and transferring two electrons. The total loss of mass due to the dissolution of the Zn ad-layer was 136.6 ng cm -2 and the mass increase due to PtO formation was found to be only 12 ng cm -2 less than the theoretical ones, 157.5 and 37.4 ng cm -2, respectively, indicating that both processes are overlapped. In this way it is proposed that an adsorbed by-layer of Zn and OH - ions is formed.

  17. Vapor permeation-stepwise injection simultaneous determination of methanol and ethanol in biodiesel with voltammetric detection.

    Science.gov (United States)

    Shishov, Andrey; Penkova, Anastasia; Zabrodin, Andrey; Nikolaev, Konstantin; Dmitrenko, Maria; Ermakov, Sergey; Bulatov, Andrey

    2016-02-01

    A novel vapor permeation-stepwise injection (VP-SWI) method for the determination of methanol and ethanol in biodiesel samples is discussed. In the current study, stepwise injection analysis was successfully combined with voltammetric detection and vapor permeation. This method is based on the separation of methanol and ethanol from a sample using a vapor permeation module (VPM) with a selective polymer membrane based on poly(phenylene isophtalamide) (PA) containing high amounts of a residual solvent. After the evaporation into the headspace of the VPM, methanol and ethanol were transported, by gas bubbling, through a PA membrane to a mixing chamber equipped with a voltammetric detector. Ethanol was selectively detected at +0.19 V, and both compounds were detected at +1.20 V. Current subtractions (using a correction factor) were used for the selective determination of methanol. A linear range between 0.05 and 0.5% (m/m) was established for each analyte. The limits of detection were estimated at 0.02% (m/m) for ethanol and methanol. The sample throughput was 5 samples h(-1). The method was successfully applied to the analysis of biodiesel samples.

  18. Differential pulse voltammetric determination of acyclovir in pharmaceutical preparations using a pencil graphite electrode.

    Science.gov (United States)

    Dilgin, Didem Giray; Karakaya, Serkan

    2016-06-01

    In this study, a new selective and sensitive voltammetric procedure for determination of acyclovir (ACV) was proposed using a disposable electrode, pencil graphite electrode (PGE). Cyclic and differential pulse voltammograms of ACV were recorded in Britton-Robinson buffer solution containing 0.10 M KCl with pH of 4.0 at PGE. The PGE displayed a very good electrochemical behavior with significant enhancement of the peak current compared to a glassy carbon electrode (GCE). Under experimental conditions, the PGE had a linear response range from 1.0 μM to 100.0 μM ACV with a detection limit of 0.3 μM (based on 3 Sb). Relative standard deviations of 4.8 and 3.6% were obtained for five successive determinations of 10.0 and 50.0 μM ACV, respectively, which indicate acceptable repeatability. This voltammetric method was successfully applied to the direct determination of ACV in real pharmaceutical samples. The effect of various interfering compounds on the ACV peak current was studied.

  19. Voltammetric studies on the electrochemical determination of methylmercury in chloride medium at carbon microelectrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, F. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal); Neto, M.M.M. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal) and Departamento de Quimica Agricola e Ambiental, Instituto Superior de Agronomia, Tapada da Ajuda, 1349-017 Lisbon (Portugal)]. E-mail: mm.neto@netcabo.pt; Rocha, M.M. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal); Fonseca, I.T.E. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal)

    2006-10-10

    Electroanalytical techniques have been used to determine methylmercury at low levels in environmental matrices. The electrochemical behaviour of methylmercury at carbon microelectrodes in a hydrochloric acid medium using cyclic, square wave and fast-scan linear-sweep voltammetric techniques has been investigated. The analytical utility of the methylmercury reoxidation peak has been explored, but the recorded peak currents were found to be poorly reproducible. This is ascribed to two factors: the adsorption of insoluble chloromercury compounds on the electrode surface, which appears to be an important contribution to hinder the voltammetric signal of methylmercury; and the competition between the reoxidation of the methylmercury radical and its dimerization reaction, which limits the reproducibility of the methylmercury peak. These problems were successfully overcome by adopting the appropriate experimental conditions. Fast-scan rates were employed and an efficient electrochemical regeneration procedure of the electrode surface was achieved, under potentiostatic conditions in a mercury-free solution containing potassium thiocyanate-a strong complexing agent. The influence of chloride ion concentration was analysed. Interference by metals, such as lead and cadmium, was considered. Calibration plots were obtained in the micromolar and submicromolar concentration ranges, allowing the electrochemical determination of methylmercury in trace amounts. An estuarine water sample was analysed using the new method with a glassy carbon microelectrode.

  20. Inapproximability of maximal strip recovery

    CERN Document Server

    Jiang, Minghui

    2009-01-01

    In comparative genomic, the first step of sequence analysis is usually to decompose two or more genomes into syntenic blocks that are segments of homologous chromosomes. For the reliable recovery of syntenic blocks, noise and ambiguities in the genomic maps need to be removed first. Maximal Strip Recovery (MSR) is an optimization problem proposed by Zheng, Zhu, and Sankoff for reliably recovering syntenic blocks from genomic maps in the midst of noise and ambiguities. Given $d$ genomic maps as sequences of gene markers, the objective of \\msr{d} is to find $d$ subsequences, one subsequence of each genomic map, such that the total length of syntenic blocks in these subsequences is maximized. For any constant $d \\ge 2$, a polynomial-time 2d-approximation for \\msr{d} was previously known. In this paper, we show that for any $d \\ge 2$, \\msr{d} is APX-hard, even for the most basic version of the problem in which all gene markers are distinct and appear in positive orientation in each genomic map. Moreover, we provi...

  1. Speciation study of aluminium in beverages by Competitive Ligand Exchange-Adsorptive Stripping Voltammetry.

    Science.gov (United States)

    Magnier, A; Fekete, V; Van Loco, J; Bolle, F; Elskens, M

    2014-05-01

    Competitive Ligand Exchange-Adsorptive Stripping Voltammetry (CLE-AdSV) was used for determining the speciation of aluminium in commonly consumed beverages (water, tea, infusion, coffee, orange juice, tomato juice, beer and red wine). Aluminium determination involves the adsorption of Al-complexes with the ligand cupferron onto a hanging mercury drop electrode. All samples were studied at pH 6.5 with an accumulation step at -0.60 V (all potential values in the paper are given versus the Ag/AgCl, [KCl]=3 M reference electrode) during 60 s, and a final cupferron concentration of 4 × 10(-4)M. These conditions were used to establish (i) the concentration of electro-labile aluminium, (ii) the range of ligand concentrations and (iii) the conditional stability constants of beverage samples using titration procedures. The results based on Ruzic plots were compared to computer simulation with Visual MINTEQ. This comparison suggests that labile monomeric Al-forms and soluble organic complexes of low molecular weight can be quantified by the CLE-AdSV procedure. Overall the relative uncertainties on the determination of the electro-active Al fraction and the complexing parameters, i.e., concentration and conditional stability constant of natural ligands in the samples, are less than 15%. Thanks to these results, information on Al bioavailability in beverages was collected and discussed. This study also illustrates the value of computer simulations when complex, time-consuming voltammetric techniques are applied.

  2. Plaque accumulations caused by interdental stripping.

    Science.gov (United States)

    Radlanski, R J; Jäger, A; Schwestka, R; Bertzbach, F

    1988-11-01

    Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evaluated with the scanning electron microscope (SEM). Even under in vitro conditions with the finest finishing strips, it was not possible to produce an enamel surface free of the furrows that result from the initial abrasion caused by the coarse strip. Enamel surfaces stripped gradually from coarse to superfine were left in the mouths of patients for 12 weeks and evaluated with the SEM. The edges of the furrows were found to be smoother but the furrows remained wide and deep enough to facilitate more plaque accumulations than those on untreated surfaces. The use of dental floss did not result in prevention of plaque accumulations along the bottom of the furrows.

  3. Determination of mercury in hair by square-wave anodic stripping voltammetry at a rotating gold disk electrode after microwave digestion.

    Science.gov (United States)

    East, Gaston A; Marinho, Epitácio P

    2005-03-01

    A simple and reliable method for the determination of mercury in hair on a rotating gold disk electrode using subtractive anodic stripping voltammetry without removal of oxygen is reported. Voltammetric and microwave parameters were optimized to obtain the best analytical results. Parameters such as supporting electrolyte concentration, influence of chloride in the Hg peak, deposition potential, scan rate, accumulation time, rotation rate, square-wave amplitude, and electrode conditioning were studied. Pressurized microwave-assisted digestion of hair, suitable for the accurate voltammetric determination of Hg, was evaluated using six acid mixtures and several time-power programs. Under the optimized conditions, no interference by copper, cadmium, lead, nickel, manganese, iron, or zinc was found at concentrations corresponding to their occurrence in normal hair. A calibration plot between 6,67 and 46,69 microg/L was linear, with r(2) better than 0.999. The detection limit for a deposition time of 60 s at 254 g was calculated as 1.92 nM (3omega). Validation of the method was demonstrated with the use of a certified reference sample of hair. Eight real samples of hair (four unexposed children and four exposed persons) were also analyzed.

  4. A pulsed cathodic arc spacecraft propulsion system

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, P R C; Bilek, M M M; Tarrant, R N; McKenzie, D R [School of Physics, University of Sydney, NSW 2006 Australia (Australia)

    2009-11-15

    We investigate the use of a centre-triggered cathodic arc as a spacecraft propulsion system that uses an inert solid as a source of plasma. The cathodic vacuum arc produces almost fully ionized plasma with a high exhaust velocity (>10{sup 4} m s{sup -1}), giving a specific impulse competitive with other plasma or ion thrusters. A centre trigger design is employed that enables efficient use of cathode material and a high pulse-to-pulse repeatability. We compare three anode geometries, two pulse current profiles and two pulse durations for their effects on impulse generation, energy and cathode material usage efficiency. Impulse measurement is achieved through the use of a free-swinging pendulum target constructed from a polymer material. Measurements show that impulse is accurately controlled by varying cathode current. The cylindrical anode gave the highest energy efficiency. Cathode usage is optimized by choosing a sawtooth current profile. There is no requirement for an exhaust charge neutralization system.

  5. Strip Casting of High Performance Structural Alloys

    Institute of Scientific and Technical Information of China (English)

    S S Park; J G Lee; Nack J Kim

    2004-01-01

    There exists a great need for the development of high performance alloys due to increasing demands for energy conservation and environmental protection. Application of strip casting shows a strong potential for the improvement of properties of existing alloys and also for the development of novel alloy systems with superior properties. The present paper reviews our Center's activities in the development of high performance alloys by strip casting. Examples include (1) Al alloys, (2) wrought Mg alloys, and (3) bulk metallic glass (BMG) alloys.

  6. Anodic voltammetric behavior and determination of rosiglitazone in pharmaceutical dosage forms and biological fluids on solid electrode.

    Science.gov (United States)

    Dogan-Topal, Burcu; Tuncel, Secil; Ozkan, Sibel A

    2010-09-01

    The anodic voltammetric behavior and electroanalytical determination of rosiglitazone was studied using cyclic, linear sweep, differential pulse and square wave voltammetric techniques on glassy carbon electrode. The oxidation of rosiglitazone was irreversible and exhibited diffusion controlled process depending on pH. Different parameters were tested to optimize the conditions for the determination of the oxidation mechanism of rosiglitazone. The dependence of current intensities and potentials on pH, concentration, scan rate, nature of the buffer was also investigated. According to the linear relationship between the peak current and the concentration, differential pulse and square wave voltammetric methods for rosiglitazone assay in pharmaceutical dosage forms and biological fluids were developed. A linear response was obtained within the range of 1x10-6M - 6x10-5M in 0.1 M H2SO4 and acetate buffer at pH 5.70 for both voltammetric methods in human serum samples. The practical analytical value of the method is demonstrated by quantitative determination of rosiglitazon in pharmaceutical formulation and human serum, without the need for separation or complex sample preparation, since there was no interference from the excipients and endogenous substances. The methods were fully validated and successfully applied to the high throughput determination of the drug in tablets and human serum with good recoveries.

  7. Preventing Corrosion by Controlling Cathodic Reaction Kinetics

    Science.gov (United States)

    2016-03-25

    Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith...dominate the metal’s cathodic behavior. Within an alkaline environment, we expect the following reduction reactions to be catalyzed on the oxide

  8. Speed Control and Coiling Temperature Control of Strip

    Institute of Scientific and Technical Information of China (English)

    CAI Xiao-hui; ZHANG Dian-hua; WANG Guo-dong; LIU Xiang-hua; FAN Lei

    2004-01-01

    Considering the strip speed during controlled laminar cooling on Baosteel 1580 hot strip mill in China, the influence of strip speed fluctuation on coiling temperature control for the tail and "neck" of the strip was analyzed. The optimization strategies were put forward and proved effective in operation.

  9. Excess Production Capacity Squeezes Profits of Brass Strip Enterprises

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Between 2003 and 2006,under the backdrop of rapid growth of domestic demand for brass strip and soaring copper price,brass strip manufacturers made a fortune.And brass strip manufacturers mushroomed in Zhejiang,Anhui and Jiangsu.Large brass strip manufacturers

  10. Process development of thin strip steel casting

    Energy Technology Data Exchange (ETDEWEB)

    Sussman, R.C.; Williams, R.S.

    1990-12-01

    An important new frontier is being opened in steel processing with the emergence of thin strip casting. Casting steel directly to thin strip has enormous benefits in energy savings by potentially eliminating the need for hot reduction in a hot strip mill. This has been the driving force for numerous current research efforts into the direct strip casting of steel. The US Department of Energy initiated a program to evaluate the development of thin strip casting in the steel industry. In earlier phases of this program, planar flow casting on an experimental caster was studied by a team of engineers from Westinghouse Electric corporation and Armco Inc. A subsequent research program was designed as a fundamental and developmental study of both planar and melt overflow casting processes. This study was arranged as several separate and distinct tasks which were often completed by different teams of researchers. An early task was to design and build a water model to study fluid flow through different designs of planar flow casting nozzles. Another important task was mathematically modeling of melt overflow casting process. A mathematical solidification model for the formation of the strip in the melt overflow process was written. A study of the material and conditioning of casting substrates was made on the small wheel caster using the melt overflow casting process. This report discusses work on the development of thin steel casting.

  11. Novel photoresist stripping technology using steam-water mixture*

    Institute of Scientific and Technical Information of China (English)

    Wang Lei; Hui Yu; Gao Chaoqun; Jing Yupeng

    2011-01-01

    A novel wet vapor photoresist stripping technology is developed as an alternative to dry plasma ashing and wet stripping. Experiments using this technology to strip hard baked SU-8 photoresist, aurum and chromium film are carried out. Then the images of stripping results are shown and the mechanism is analyzed and discussed.The most striking result of this experiment is that the spraying mixture of steam and water droplets can strip photoresist and even metal film with ease.

  12. Cathode materials: A personal perspective

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B. [Texas Materials Institute, University of Texas at Austin, ETC 9.102, 1 University Station, Austin, TX 78712-1063 (United States)

    2007-12-06

    A thermodynamically stable rechargeable battery has a voltage limited by the window of the electrolyte. An aqueous electrolyte has a window of 1.2 eV, which prevents achieving the high energy density desired for many applications. A non-aqueous electrolyte with a window of 5 eV requires Li{sup +} rather than H{sup +} as the working ion. Early experiments with Li{sub x}TiS{sub 2} cathodes showed competitive capacity and rate capability, but problems with a lithium anode made the voltage of a safe cell based on a sulfide cathode too low to be competitive with a nickel/metal-hydride battery. Transition-metal oxides can give voltages of 4.5 V versus Li{sup +}/Li{sup 0}. However, the challenge with oxides has been to obtain a competitive capacity and rate capability while retaining a high voltage with low-cost, environmentally friendly cathode materials. Comparisons will be made between layered Li{sub 1-x}MO{sub 2}, spinels Li{sub 1-x}[M{sub 2}]O{sub 4}, and olivines Li{sub 1-x}MPO{sub 4} having 0 < x < 1. Although higher capacities can be obtained with layered Li{sub 1-x}MO{sub 2} compounds, which have enabled the wireless revolution, their metastability makes them unlikely to be used in power applications. The spinel and olivine framework structures have been shown to be capable of charge/discharge rates of over 10C with a suitable temperature range for plug-in hybrid vehicles. (author)

  13. Construction of an electrochemical sensor based on amino-functionalized metal-organic frameworks for differential pulse anodic stripping voltammetric determination of lead.

    Science.gov (United States)

    Wang, Yang; Ge, Huali; Wu, Yichun; Ye, Guiqin; Chen, Huanhuan; Hu, Xiaoya

    2014-11-01

    Metal-organic frameworks composite materials have received tremendous attention because of their versatile structures and tunable porosity for various applications. Herein, amino-functionalized metal-organic frameworks (NH2-Cu3(BTC)2; BTC=benzene-1,3,5-tricarboxylate) was prepared and used as a novel electrode modifier for the determination of trace levels of lead. NH2-Cu3(BTC)2 shows quite a good capability for the efficient adsorption of lead from aqueous solutions. The parameters affecting the electrochemical process, such as electrolyte solution pH, the amount of NH2-Cu3(BTC)2 suspension, accumulation potential and accumulation time, were investigated in detail. Under the optimal conditions, the electrochemical sensor exhibited a linear response to the concentration of lead in the range of 1.0×10(-8)-5.0×10(-7) mol L(-1) (R(2)=0.9951) with a detection limit of 5.0×10(-9) mol L(-1). The relative standard deviation of 11 successive scans was 3.10% for 1.0×10(-8) mol L(-1) lead. The method was validated with certified reference material (stream sediment and milk powder) and the analytical results coincided well with the certified values. Furthermore, the method was successfully applied to the determination of target analytes in tap and lake water samples and good recoveries were obtained from different spiked values.

  14. The contents of sesamol and related lignans in sesame, tahina and halva as determined by a newly developed polarographic and stripping voltammetric analysis

    Directory of Open Access Journals (Sweden)

    2009-06-01

    Full Text Available The contents of antioxidant lignans (Sesamol in sesame, commercial formulations of tahina and halva, which are processed tahina foods, were determined by Differential Pulse Polarography (DPP with a capillary hanging mercury drop electrode (HMDE. A platinum wire was used as the counter electrode and Ag/AgCl was the reference electrode. Samples have been analyzed by standard addition procedures and found to be quantitative (p2=0.9999 (pSe determinó el contenido del lignano antioxidante (Sesamol en sésamo, formulaciones comerciales de tahina y halva, que es el producto procesado de tahina, por polarografía de pulsos diferencial (DPP con un capilar conteniendo un electrodo de gota de mercurio (HMDE. Un hilo de platino fué usado como el electrodo contador y Ag/AgCl como electrodo de referencia. Las muestras fueron analizadas por procedimientos de adición de patrones y se encontró que wl procedimiento era cuantitativo (p2= 0.9999 (p< 0.01. El método polarográfico propuesto (DPP es un método rápido y reproducible para la determinación simultánea de lignanos fenólicos en sésamo y otros productos alimentarios que contienen sésamo. Éste proporciona una detección cuantitativa adecuada y sensible de este compuesto nutraceútico en alimentos comerciales.

  15. Detection of Adulteration in Argan Oil by Using an Electronic Nose and a Voltammetric Electronic Tongue

    Directory of Open Access Journals (Sweden)

    Madiha Bougrini

    2014-01-01

    Full Text Available Adulteration detection of argan oil is one of the main aspects of its quality control. Following recent fraud scandals, it is mandatory to ensure product quality and customer protection. The aim of this study is to detect the percentages of adulteration of argan oil with sunflower oil by using the combination of a voltammetric e-tongue and an e-nose based on metal oxide semiconductor sensors and pattern recognition techniques. Data analysis is performed by three pattern recognition methods: principal component analysis (PCA, discriminant factor analysis (DFA, and support vector machines (SVMs. Excellent results were obtained in the differentiation between unadulterated and adulterated argan oil with sunflower one. To the best of our knowledge, this is the first attempt to demonstrate whether the combined e-nose and e-tongue technologies could be successfully applied to the detection of adulteration of argan oil.

  16. Voltammetric Behavior of Sodium 7-Methoxyl-4'-hydroxylisoflavone-3'-sulfonate and Its Application

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zun-Ting张尊听; DONG She-Ying董社英; ZHENG Jian-Bin郑建斌; ZHANG Hong-Fang张宏芳; GAO Hong高鸿

    2004-01-01

    Voltammetric behavior of sodium 7-methoxyl-4'-hydroxylisoflavone-3'-sulfonate (SMHS) in the aqueous solution from pH 1 to 5 was studied by linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry.SMHS caused only one reduction wave at -1.34 V (vs. saturated calomel electrode, SCE), which was an irreversible adsorptive wave of SMHS protonized involving one electron and one proton. The peak current of SMHS on synthetic samples. In addition, its scavenging effect on superoxide anion radical was studied by the auto-oxidation of pyrogallol in HCl-tris buffer solution (pH=8.2) in order to explain its peculiar biological effects. The experimental results proved that SMHS has antioxidant quality, and it is an efficient free radical scavenger of superoxide anion radical.

  17. Spectrophotometric and Voltammetric Studies on the Interaction of Heparin with Phenosafranine

    Institute of Scientific and Technical Information of China (English)

    Wei SUN; Ya Qin DING; Kui JIAO

    2005-01-01

    The interaction of phenosafranine (PSF) with a glycosaminoglycans of heparin (Hep) in aqueous solution has been characterized by UV-Vis absorption spectrophotometry and cyclic voltammetry in pH 1.5 Britton-Robinson (B-R) buffer solution. The addition of Hep caused decrease of the absorbance of PSF at 532 nm and the redox peak current of PSF. The study showed that an supramolecular complex of PSF-Hep was formed because of the electrostatic attraction of negatively charged Hep with the positively charged PSF, which resulted in the decrease of the equilibrium concentration of PSF in solutions, and the decrease of the absorbance or the Peak current of PSF. The stoichiometry of the Hep/PSF complex was further calculated by voltammetric data with the result of 1:1 complex.

  18. Rapid screening and guided extraction of antioxidants from microalgae using voltammetric methods.

    Science.gov (United States)

    Goiris, Koen; De Vreese, Peter; De Cooman, Luc; Muylaert, Koenraad

    2012-08-01

    Currently, microalgae draw much attention as a promising source of natural antioxidants to replace synthetic antioxidants for food applications. In this paper, the use of voltammetric techniques as a fast alternative for chemical assays to determine the antioxidant power of microalgal biomass is discussed. It was found that antioxidant activities determined by square wave voltammetry correlate well with the results from other established antioxidant assays, such as Trolox equivalent antioxidant capacity (R(2) = 0.737), ferric reducing antioxidant potential (R(2) = 0.729), and AAPH-induced oxidation of linoleic acid (R(2) = 0.566). Besides yielding quantitative data on the antioxidant activity, square wave voltammetry provides additional information on the antioxidant profile of microalgal biomass as the peak potentials of antioxidant components are determined. Consequently, square wave voltammetry can be used as a tool for optimizing the extraction processes to recover antioxidant components from microalgae.

  19. Differential Pulse Voltammetric Determination of Fulvestrant in Pharmaceutical Dosage Forms and Serum Samples

    Directory of Open Access Journals (Sweden)

    Dilek Kul

    2011-01-01

    Full Text Available The electrooxidation behavior and determination of fulvestrant at a glassy carbon electrode were investigated. The voltammetric study of the model compounds allowed elucidating the possible oxidation mechanism of fulvestrant. The dependence of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate was determined. The oxidation of fulvestrant showed a single and irreversible peak at glassy carbon electrode, and the process was found diffusion controlled. Linear responses were obtained for the concentrations between 4×10−6 M and 6×10−5 M in standard samples and between 2×10−5 M and 1×10−4 M in serum samples. The repeatability of the method was found 0.93 RSD%. The repeatability, reproducibility, precision, and accuracy of proposed method were investigated.

  20. Voltammetric Determination of Estrogens Based on the Enhancement Effect of Surfactant at Carbon Paste Electrode

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Highly sensitive voltammetric method for the determination of estrogens, based on the enhancement effect of cetyltrimethylammonium bromide (CTAB) has been described. In the presence of CTAB, the oxidation peak currents of estrogens (estradiol, estrone, estriol, estradiol valerate and diethylstilbestrol) at the carbon paste electrode (CPE) increased significantly after open-circuit accumulation. The peak current was proportional to the concentration of estradiol over the range from 5×10-9 to 2.5×10-6 mol\\5L-1. The detection limit was 8×10-10 mol\\5L-1 at 6 min of accumulation. The total amounts of estrogens in the blood serums were determined and the average recovery was 104.92%. Under the conditions used, the electrode process of estradiol was examined and the mechanism for peak current enhancement was also discussed.

  1. Anodic stripping voltammetry of silver nanoparticles: aggregation leads to incomplete stripping.

    Science.gov (United States)

    Cloake, Samantha J; Toh, Her Shuang; Lee, Patricia T; Salter, Chris; Johnston, Colin; Compton, Richard G

    2015-02-01

    The influence of nanoparticle aggregation on anodic stripping voltammetry is reported. Dopamine-capped silver nanoparticles were chosen as a model system, and melamine was used to induce aggregation in the nanoparticles. Through the anodic stripping of the silver nanoparticles that were aggregated to different extents, it was found that the peak area of the oxidative signal corresponding to the stripping of silver to silver(I) ions decreases with increasing aggregation. Aggregation causes incomplete stripping of the silver nanoparticles. Two possible mechanisms of 'partial oxidation' and 'inactivation' of the nanoparticles are proposed to account for this finding. Aggregation effects must be considered when anodic stripping voltammetry is used for nanoparticle detection and quantification. Hence, drop casting, which is known to lead to aggregation, is not encouraged for preparing electrodes for analytical purposes.

  2. Effect of Load Distribution on Strip Crown in Hot Strip Rolling

    Institute of Scientific and Technical Information of China (English)

    Hongshuang DI; Jianzhong XU; Dianyao GONG; Xianghua LIU; Guodong WANG; Xiaoming HE; Liying BA

    2004-01-01

    In order to establish precision model, a software to calculate the strip crown of four-high hot rolling mill was developed by using affecting function method according to the strip crown calculation theory. The effect of work roll diameter, unit width rolling load, roll bending force, work roll crown, initial strip crown and reduction, etc, on load distribution effect rate was simulated by using the software. The results show that the load distribution effect rate increases with the increase of strip width, work roll diameter, unit width rolling load, roll bending force, work roll crown, initial strip crown and reduction. Based on the simulation results, base value of load distribution effect rate and fitting coefficients of six power polynomial of load distribution effect rate modification coefficient were determined considering all of the above parameters. A simplified mathematical model for calculating load distribution effect rate was established.

  3. Preliminary Results of Field Emission Cathode Tests

    Science.gov (United States)

    Sovey, James S.; Kovaleski, Scott D.

    2001-01-01

    Preliminary screening tests of field emission cathodes such as chemical vapor deposited (CVD) diamond, textured pyrolytic graphite, and textured copper were conducted at background pressures typical of electric thruster test facilities to assess cathode performance and stability. Very low power electric thrusters which provide tens to hundreds micronewtons of thrust may need field emission neutralizers that have a capability of tens to hundreds of microamperes. From current voltage characteristics, it was found that the CVD diamond and textured metals cathodes clearly satisfied the Fowler-Nordheim emission relation. The CVD diamond and a textured copper cathode had average current densities of 270 and 380 mA/sq cm, respectively, at the beginning-of-life. After a few hours of operation the cathode emission currents degraded by 40 to 75% at background pressures in the 10(exp -5) Pa to 10(exp -4) Pa range. The textured pyrolytic graphite had a modest current density at beginning-of-life of 84 mA/sq cm, but this cathode was the most stable of all. Extended testing of the most promising cathodes is warranted to determine if current degradation is a burn-in effect or whether it is a long-term degradation process. Preliminary experiments with ferroelectric emission cathodes, which are ceramics with spontaneous electric polarization, were conducted. Peak current densities of 30 to 120 mA/sq cm were obtained for pulse durations of about 500 ns in the 10(exp -4) Pa pressure range.

  4. Development of floating strip micromegas detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bortfeldt, Jonathan

    2014-04-28

    Micromegas are high-rate capable, high-resolution micro-pattern gaseous detectors. Square meter sized resistive strip Micromegas are foreseen as replacement of the currently used precision tracking detectors in the Small Wheel, which is part of the forward region of the ATLAS muon spectrometer. The replacement is necessary to ensure tracking and triggering performance of the muon spectrometer after the luminosity increase of the Large Hadron Collider beyond its design value of 10{sup 34} cm{sup -2}s{sup -1} around 2020. In this thesis a novel discharge tolerant floating strip Micromegas detector is presented and described. By individually powering copper anode strips, the effects of a discharge are confined to a small region of the detector. This reduces the impact of discharges on the efficiency by three orders of magnitude, compared to a standard Micromegas. The physics of the detector is studied and discussed in detail. Several detectors are developed: A 6.4 x 6.4 cm{sup 2} floating strip Micromegas with exchangeable SMD capacitors and resistors allows for an optimization of the floating strip principle. The discharge behavior is investigated on this device in depth. The microscopic structure of discharges is quantitatively explained by a detailed detector simulation. A 48 x 50 cm{sup 2} floating strip Micromegas is studied in high energy pion beams. Its homogeneity with respect to pulse height, efficiency and spatial resolution is investigated. The good performance in high-rate background environments is demonstrated in cosmic muon tracking measurements with a 6.4 x 6.4 cm{sup 2} floating strip Micromegas under lateral irradiation with 550 kHz 20 MeV proton beams. A floating strip Micromegas doublet with low material budget is developed for ion tracking without limitations from multiple scattering in imaging applications during medical ion therapy. Highly efficient tracking of 20 MeV protons at particle rates of 550 kHz is possible. The reconstruction of the

  5. Voltammetric Behaviour of Sulfamethoxazole on Electropolymerized-Molecularly Imprinted Overoxidized Polypyrrole

    Directory of Open Access Journals (Sweden)

    Yücel Sahin

    2008-12-01

    Full Text Available In this work, preparation of a molecularly imprinted polymer (MIP film and its recognition properties for sulfamethoxazolewere investigated. The overoxidized polypyrrole (OPPy film was prepared by the cyclic voltammetric deposition of pyrrole (Py in the presence of supporting electrolyte (tetrabutylammonium perchlorate-TBAP with and without a template molecule (sulfamethoxazole on a pencil graphite electrode (PGE. The voltammetric behaviour of sulfamethoxazole on imprinted and non-imprinted (NIP films was investigated by differential pulse voltammetry (DPV in Britton-Robinson (BR buffer solutions prepared in different ratio of acetonitrile-water binary mixture, between the pH 1.5 and 7.0. The effect of the acetonitrile-water ratio and pH, monomer and template concentrations, electropolymerization cycles on the performance of the MIP electrode was investigated and optimized. The MIP electrode exhibited the best reproducibility and highest sensitivity. The results showed that changing acetonitrile-water ratio and pH of BR buffer solution changes the oxidation peak current values. The highest anodic signal of sulfamethoxazole was obtained in BR buffer solution prepared in 50% (v/v acetonitrile-water at pH 2.5. The calibration curve for sulfamethoxazole at MIP electrode has linear region for a concentration range of 25.10-3 to 0.75 mM (R2=0.9993. The detection limit of sulfamethoxazole was found as 3.59.10-4 mM (S/N=3. The same method was also applied to determination of sulfamethoxazole in commercial pharmaceutical samples. Method precision (RSD87% were satisfactory. The proposed method is simple and quick. The polypyrrole (PPy electrodes have low response time, good mechanical stability and are disposable simple to construct.

  6. Discrimination of Apple Liqueurs (Nalewka Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Magdalena Śliwińska

    2016-10-01

    Full Text Available The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin–Ciocalteu method (R2 of 0.97 in calibration and R2 of 0.93 in validation and also with the density, a marker of the alcoholic content method (R2 of 0.93 in calibration and R2 of 0.88 in validation. UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R2 of 0.99 in calibration and R2 of 0.99 in validation but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R2 of 0.96 in calibration and R2 of 0.85 in validation. In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content—the most important parameters to be measured in this type of liqueurs.

  7. Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy.

    Science.gov (United States)

    Śliwińska, Magdalena; Garcia-Hernandez, Celia; Kościński, Mikołaj; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Śliwińska-Bartkowiak, Małgorzata; Jurga, Stefan; Garcia-Cabezon, Cristina; Rodriguez-Mendez, Maria Luz

    2016-10-09

    The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin-Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content-the most important parameters to be measured in this type of liqueurs.

  8. Determination of trace amounts of Ga(III) by adsorptive stripping voltammetry with in situ plated bismuth film electrode.

    Science.gov (United States)

    Grabarczyk, Malgorzata; Wasąg, Joanna

    2015-11-01

    The determination of trace gallium using adsorptive stripping voltammetry at an in situ plated bismuth film electrode was described. The method was based on simultaneous film formation and the Ga(III)-cupferron complex preconcentration at -0.65 V and its cathodic stripping during the potential scan. The effect of Bi(III) and cupferron concentration, the influence of deposition potential and time, and the scan rate on the determination of Ga(III) were studied. A linear response in the concentration range of 3×10(-10) to 3×10(-7) mol L(-1) (r=0.998) was obtained with detection limit of 1.05×10(-10) mol L(-1) using accumulation time of 180 s. Finally, the bismuth film electrode was successfully applied for the determination of Ga(III) in certified reference material seawater NASS-5 with satisfactory results.

  9. Area specific stripping factors for AGS. A method for extracting stripping factors from survey data

    Energy Technology Data Exchange (ETDEWEB)

    Aage, H.K.; Korsbech, U. [Technical Univ. of Denmark (Denmark)

    2006-04-15

    In order to use Airborne Gamma-ray Spectrometry (AGS) for contamination mapping, for source search etc. one must to be able to eliminate the contribution to the spectra from natural radioactivity. This in general is done by a stripping technique. The parameters for performing a stripping have until recently been measured by recording gamma spectra at special calibration sites (pads). This may be cumbersome and the parameters may not be correct when used at low gamma energies for environmental spectra. During 2000-2001 DTU tested with success a new technique for Carborne Gamma-ray Spectrometry (CGS) where the spectra from the surveyed area (or from a similar area) were used for calculating the stripping parameters. It was possible to calculate usable stripping ratios for a number of low energy windows - and weak source signals not detectable by other means were discovered with the ASS technique. In this report it is shown that the ASS technique also works for AGS data, and it has been used for recent Danish AGS tests with point sources. (Check of calibration of AGS parameters.) By using the ASS technique with the Boden data (Barents Rescue) an exercise source was detected that has not been detected by any of the teams during the exercise. The ASS technique therefore seems to be better for search for radiation anomalies than any other method known presently. The experiences also tell that although the stripping can be performed correctly at any altitude there is a variation of the stripping parameters with altitude that has not yet been quite understood. However, even with the oddly variations the stripping worked as expected. It was also observed that one might calculate a single common set of usable stripping factors for all altitudes from the entire data set i.e. some average a, b and c values. When those stripping factors were used the stripping technique still worked well. (au)

  10. Beam stripping extraction from the VINCY cyclotron

    Directory of Open Access Journals (Sweden)

    Ristić-Đurović Jasna L.

    2006-01-01

    Full Text Available The extraction system of a cyclotron guides an ion beam from a spiral acceleration orbit, through an extraction trajectory, into a high energy transport line. The two methods commonly used to direct an ion into the extraction path are deflection, by the electric field of an electrostatic deflector, and ion stripping, by a thin carbon foil. Compared to the electrostatic deflector system, the stripping extraction provides a fast and easy change of the extracted ion energy and is easier to manufacture operate, and maintain. However, the extraction trajectory and dynamics of an ion beam after stripping are highly dependant on the ion energy and specific charge. Thus, when a multipurpose machine such as the VINCY Cyclotron is concerned, it is far from easy to deliver a variety of ion beams into the same high energy transport line and at the same time preserve a reasonable compactness of the extraction system. The front side stripping extraction system of the VINCY Cyclotron provides high (~70 MeV and mid (~30 MeV energy protons, as well as a number of heavy ions in broad energy ranges. The back side stripping extraction system extracts low energy protons (~18 MeV and enables their simultaneous use with high energy protons at the front side of the machine.

  11. Modeling of continuous strip production by rheocasting

    Science.gov (United States)

    Matsumiya, T.; Flemings, M. C.

    1981-03-01

    A process was experimentally and mathematically modeled for continuous and direct production of metal strip from its molten state by the use of Rheocasting. The process comprises 1) continuous production of a Rheocast semisolid alloy, and 2) direct shaping of the semisolid into strip. Sn-15 pct Pb was used as the modeling alloy. Crack formation and surface quality of the strip produced depend on fraction solid and deformation force. Continuous, sound strip could be obtained with good surface quality when fraction solid was between 0.50 and 0.70 and deformation force did not exceed a given maximum. Sheet thickness depends on deformation force, fraction solid, rotor rate of Rheocaster and production line speed. At constant deformation force, sheet thickness increases as fraction solid increases, rotor rate decreases and line speed is reduced. Sheet thickness is larger in the center than in the edge, but the difference is reduced by applying edgers. Some segregation of lead toward the edges is observed, and the segregation increases as amount of deformation is increased. A mathematical model for heat flow, solidification and deformation was constructed. The model predicts the point of completion of solidification in the strip and sheet thickness as a function of deformation force and line speed. Calculations are in good agreement with experimental results.

  12. Modeling of continuous strip production by rheocasting

    Energy Technology Data Exchange (ETDEWEB)

    Matsumiya, T.; Flemings, M.C.

    1981-03-01

    A process was experimentally and mathematically modeled for continuous and direct production of metal strip from its molten state by the use of Rheocasting. The process comprises 1) continuous production of a Rheocast semisolid alloy, and 2) direct shaping of the semisolid into strip. Sn-15 pct Pb was used as the modeling alloy. Crack formation and surface quality of the strip produced depend on fraction solid and deformation force. Continuous, sound strip could be obtained with good surface quality when fraction solid was between 0.50 and 0.70 and deformation force did not exceed a given maximum. Sheet thickness depends on deformation force, fraction solid, rotor rate of Rheocaster and production line speed. At constant deformation force, sheet thickness increases as fraction solid increases, rotor rate decreases and line speed is reduced. Sheet thickness is larger in the center than in the edge, but the difference is reduced by applying edgers. Some segregation of lead toward the edges is observed, ad the segregation increases as amount of deformation is increased. A mathematical model for heat flow, solidification and deformation was constructed. The model predicts the point of completion of solidification in the strip and sheet thickness as a function of deformation force and line speed. Calculations are in good agreement with experimental results.

  13. Effects of 12-crown-4 ether on the electrochemical performance of CoO2 and TiS2 cathodes in Li polymer electrolyte cells

    Science.gov (United States)

    Nagasubramanian, G.; Attia, Alan I.; Halpert, G.

    1992-01-01

    The effect of adding 12-crown-4 ether (12Cr4) to the polyethylene oxide (PEO) electrolyte on the electrochemical properties of cells with Li(x)CoO2 or TiS2 as the cathode was investigated. The polymer electrolyte films were: (1) PEO, LiBF4; (2) PEO, LiBF4 with 12Cr4; (3) Li(x)CoO2, PEO, and LiBF4; and (4) Li(x)CoO2, PEO, LiBF4, and 12Cr4. It was found that, although 12Cr4 improved the cell performance over cells without 12Cr4 in the shallow c/d cycles (cyclic voltammetric behavior), it did not seem to prolong the active life of the cell. The cells with CoO2 as the cathode failed after a few c/d cycles, while similar cells with TiS2 did not fail even after 12 c/d cycles. The probable cause of failure in the case of CoO2 is ascribed to the instability of the CoO2 cathode.

  14. Effect of Initial Crown on Shape of Hot Rolled Strip

    Institute of Scientific and Technical Information of China (English)

    HU Yu; GONG Dian-yao; JIANG Zheng-yi; XU Jian-zhong; ZHANG Dian-hua; LIU Xiang-hua

    2009-01-01

    Based on the influence coefficient method, the effect of entry strip crown on the shape of hot rolled strip was analyzed using the software of roll elastic deformation simulation. According to the practical condition of a domestic hot roiled strip plant, the unit strip crown change from the first stand to the last stand was calculated when the entry crown of hot strip varies. The calculated result shows that the entry strip crown does not significantly affect the target strip crown at the exit of the last finishing stand in respect to a fixed strip shape control reference (such as bending force). The calculation was analyzed, and the research is helpful in modeling strip shape setup and shape control.

  15. Ram pressure stripping of tilted galaxies

    CERN Document Server

    Jachym, P; Palous, J; Combes, F

    2009-01-01

    Ram pressure stripping of galaxies in clusters can yield gas deficient disks. Previous numerical simulations based on various approaches suggested that, except for near edge-on disk orientations, the amount of stripping depends very little on the inclination angle. Following our previous study of face-on stripping, we extend the set of parameters with the disk tilt angle and explore in detail the effects of the ram pressure on the interstellar content (ISM) of tilted galaxies that orbit in various environments of clusters, with compact or extended distributions of the intra-cluster medium (ICM). We further study how results of numerical simulations could be estimated analytically. A grid of numerical simulations with varying parameters is produced using the tree/SPH code GADGET with a modified method for calculating the ISM-ICM interaction. These SPH calculations extend the set of existing results obtained from different codes using various numerical techniques. The simulations confirm the general trend of le...

  16. Pd/RGO modified carbon felt cathode for electro-Fenton removing of EDTA-Ni.

    Science.gov (United States)

    Zhang, Zhen; Zhang, Junya; Ye, Xiaokun; Hu, Yongyou; Chen, Yuancai

    Ethylenediaminetetraacetic acid (EDTA) forms stable complexes with toxic metals such as nickel due to its strong chelation. The electro-Fenton (EF) process using a cathode made from palladium (Pd), reduced graphene oxide (RGO) and carbon felt, fed with air, exhibited high activities and stability for the removal of 10 mg L(-1) EDTA-Ni solution. Pd/RGO catalyst was prepared by one-pot synthesis; the scanning electron microscopy and X-ray diffraction analysis indicated nanoparticles and RGO were well distributed on carbon felt, forming three dimensional architecture with both large macropores and a mesoporous structure. The cyclic voltammetric results showed that the presence of RGO in Pd/RGO/carbon felt significantly increased the current response of two-electron reduction of O2 (0.45 V). The key factors influencing the removal efficiency of EDTA-Ni, such as pH, current and Fe(2+) concentration, were investigated. Under the optimum conditions, the removal efficiency of EDTA-Ni reached 83.8% after 100 min EF treatment. Mechanism analysis indicated that the introduction of RGO in Pd/RGO/carbon felt significantly enhanced the electrocatalytic activities by inducing •OH in the EF process; direct H2O2 oxidation still accounted for a large amount of EDTA-Ni removal efficiency.

  17. Rapid diagnosis of meningitis using reagent strips

    Directory of Open Access Journals (Sweden)

    Parmar Ramesh

    2004-02-01

    Full Text Available OBJECTIVES: Identification of causative agent with estimation of cerebrospinal fluid (CSF glucose, protein, cells is necessary for accurate diagnosis of meningitis. Unfortunately, even these facilities are not available in many areas. Reagent strips that measure glucose and protein in blood and urine can serve this task but have been used with varying results in the past. This study was carried out to evaluate the utility and efficacy of Combur 10 strips in the diagnosis of meningitis. DESIGN, SETTINGS AND METHODS: A prospective clinical single blinded study of 63 children suspected to have meningitis undergoing CSF analysis. Each CSF sample was divided in to two and was utilised for reagent strip analysis in addition to standard laboratory evaluation and a correlation analysis were made. Statistical Method used: Results were analysed using standard statistical tests. Accuracy of the reagent strips as a screening tool was established using Godyn′s test. RESULTS: The sensitivity, specificity of the reagent strips for the diagnosis of meningitis was 97.14%, 96.42%. The sensitivity, specificity for tuberculous meningitis and bacterial meningitis were 100%, and 96.55%. That for the aseptic meningitis was 70% and 96.55%. Accuracy for the diagnosis of meningitis as a whole, bacterial meningitis, tuberculous meningitis, and aseptic meningitis were 96.78%, 98.2%, 98.27% and 83.0% respectively. CONCLUSION: Combur10 strips thus can be used for the rapid CSF analysis and screening with good accuracy. In situations where facilities of routine laboratory testing are not available this can be of an immense help.

  18. Validation of the Hot Strip Mill Model

    Energy Technology Data Exchange (ETDEWEB)

    Richard Shulkosky; David Rosberg; Jerrud Chapman

    2005-03-30

    The Hot Strip Mill Model (HSMM) is an off-line, PC based software originally developed by the University of British Columbia (UBC) and the National Institute of Standards and Technology (NIST) under the AISI/DOE Advanced Process Control Program. The HSMM was developed to predict the temperatures, deformations, microstructure evolution and mechanical properties of steel strip or plate rolled in a hot mill. INTEG process group inc. undertook the current task of enhancing and validating the technology. With the support of 5 North American steel producers, INTEG process group tested and validated the model using actual operating data from the steel plants and enhanced the model to improve prediction results.

  19. slice of LEP beamtube with getter strip

    CERN Multimedia

    1989-01-01

    A section of the LEP beam pipe. This is the chamber in which LEP's counter-rotating electron and positron beams travel. It is made of lead-clad aluminium. The beams circulate in the oval cross-section part of the chamber. In the rectangular cross-section part, LEP's innovative getter-strip vacuum pump is installed. After heating to purify the surface of the getter, the strip acts like molecular sticky tape, trapping any stray molecules left behind after the accelerator's traditional vacuum pumps have done their job.

  20. Potential profile in a conducting polymer strip

    DEFF Research Database (Denmark)

    Bay, Lasse; West, Keld; Vlachopoulos, Nikolaos

    2002-01-01

    and complicate measurements on free-standing films. A model of the potential profile in a free-standing strip is derived. It is found that the active length (the length with a given potential change) of the polymer will scale as square root (d sigma /i/sub d/). (d is the thickness, sigma the conductivity...... of the film, and i/sub d/ the diffusion limited current density for oxygen reduction). The active length is typically of the order of millimeters. The model is compared with measurements on a strip of polypyrrole doped with dodecylbenzene sulfonate...

  1. Multi-twist optical Mobius strips

    CERN Document Server

    Freund, Isaac

    2009-01-01

    Circularly polarized Gauss-Laguerre GL(0,0) and GL(0,1) laser beams that cross at their waists at a small angle are shown to generate a quasi-paraxial field that contains an axial line of circular polarization, a C line, surrounded by polarization ellipses whose major and minor axes generate multi-twist Mobius strips with twist numbers that increase with distance from the C point. These Mobius strips are interpreted in terms of Berry's phase for parallel transport of the ellipse axes around the C point.

  2. Lubrication in strip cold rolling process

    Institute of Scientific and Technical Information of China (English)

    Jianlin Sun; Yonglin Kang; Tianguo Xiao; Jianze Wang

    2004-01-01

    A lubrication model was developed for explaining how to form an oil film in the deformation zone, predicting the film thickness and determining the characteristics of lubrication in the strip rolling process, combined with the knowledge of hydrodythicknesses in the strip cold rolling. Results from the experiment and calculation show that the oil film forming in hydrodynamic lubrication is up to the bit angle and a higher rolling speed or a higher rolling oil viscosity. The mechanism of mechanical entrainment always affects the film thickness that increases with the rolling oil viscosity increasing or the reduction rate decreasing in rolling.

  3. Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Causa, Federica [Dipartimento di Scienze dell' Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Universita degli studi di Messina, 98122 Messina (Italy); Ghezzi, Francesco; Caniello, Roberto; Grosso, Giovanni [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dellasega, David [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dipartimento di Energia, Politecnico di Milano, Via Ponzio 34/3, 20133 Milano (Italy)

    2012-12-15

    Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

  4. Hall-effect thruster--Cathode coupling: The effect of cathode position and magnetic field topology

    Science.gov (United States)

    Sommerville, Jason D.

    2009-12-01

    Hall-effect thruster (HET) cathodes are responsible for the generation of the free electrons necessary to initiate and sustain the main plasma discharge and to neutralize the ion beam. The position of the cathode relative to the thruster strongly affects the efficiency of thrust generation. However, the mechanisms by which the position affects the efficiency are not well understood. This dissertation explores the effect of cathode position on HET efficiency. Magnetic field topology is shown to play an important role in the coupling between the cathode plasma and the main discharge plasma. The position of the cathode within the magnetic field affects the ion beam and the plasma properties of the near-field plume, which explains the changes in efficiency of the thruster. Several experiments were conducted which explored the changes of efficiency arising from changes in cathode coupling. In each experiment, the thrust, discharge current, and cathode coupling voltage were monitored while changes in the independent variables of cathode position, cathode mass flow and magnetic field topology were made. From the telemetry data, the efficiency of the HET thrust generation was calculated. Furthermore, several ion beam and plasma properties were measured including ion energy distribution, beam current density profile, near-field plasma potential, electron temperature, and electron density. The ion beam data show how the independent variables affected the quality of ion beam and therefore the efficiency of thrust generation. The measurements of near-field plasma properties partially explain how the changes in ion beam quality arise. The results of the experiments show that cathode position, mass flow, and field topology affect several aspects of the HET operation, especially beam divergence and voltage utilization efficiencies. Furthermore, the experiments show that magnetic field topology is important in the cathode coupling process. In particular, the magnetic field

  5. Cathode heating mechanisms in pseudospark plasma switches

    Science.gov (United States)

    Sommerer, Timothy J.; Pak, Hoyoung; Kushner, Mark J.

    1992-10-01

    Pseudosparks, and the back-lighted thyratron (BLT) in particular, are finding increasing application as pulse power switches. An attractive feature of BLTs is that high current densities (≥ tens of kA cm-2) can be sustained from metal cathodes without auxiliary heating. The source of this current is believed to be electric-field-enhanced thermionic emission resulting from heating of the cathode by ion bombardment during commutation which ultimately melts the surface of the cathode. It is proposed that a photon-driven ionization mechanism in the interelectrode gap of the BLT is responsible for initiating the observed patterns of cathode surface melting and electron emission. A 21/2-dimensional computer model is presented that incorporates a photo-induced ionization mechanism to spread the plasma into the interelectrode gap. It predicts a melting of the cathode in a pattern similar to that which is experimentally observed, and predicts a rate of field-enhanced thermionic electron emission that is sufficient to explain the high BLT conduction current density. In the absence of these mechanisms, the model does not predict the observed large-area melting of the face of the cathode. The cathode heating rate during the BLT switching phase is maximum for operating parameters that are very close to the limit for which the switch will close (that is, the smallest possible pressure-electrode spacing product and smallest possible electrode holes).

  6. Voltammetric Study and Determination of Phenylephrine Hydrochloride at INP-Nafion-Modified CPE Sensor Employing Differential Pulse Voltammetry

    Directory of Open Access Journals (Sweden)

    Zeinab Pourghobadi

    2014-03-01

    Full Text Available In this study, describes the voltammetric oxidation and determination of phenylephrine (PHE hydrochloride at a new chemically modified electrode. Iron nanoparticle (INPs was dispersed in Nafion solution to obtain a INP-Nafion-modified CPE for the voltammetric analysis of PHE .The electrochemical behaviour of PHE on INP-Nafion-modified CPE was studied, using cyclic voltammetry as a diagnostic technique. The effects of amount of INPs-Nafion dispersion, pH, and scan rate on the response of modified electrode for the oxidation of PHE were investigated. Using differential pulse voltammetry (DPV, the modified electrode indicated a dynamic linear range for quantitative determination of PHE in the range of 5 μM−130 μM, and the detection limit was estimated to be 0.76 μM. The method was developed for the determination of PHE in pharmaceutical samples with satisfactory results.

  7. Influence of melatonin or its antagonism on alcohol consumption in ethanol drinking rats: a behavioral and in vivo voltammetric study.

    Science.gov (United States)

    Crespi, Francesco

    2012-05-03

    Melatonin, an indoleamine hormone synthesized in the pinealocytes, has been implicated as influencing the intake of alcohol in rats. It has been shown that this hormone is voltammetrically electroactive at the surface of pretreated carbon fiber microelectrodes in vitro and in vivo, in rat cerebral melatonergic regions such the pineal gland. The aim of this work consisted in the study of the influence of melatonin on spontaneously ethanol drinking or ethanol avoiding rats selected throughout a free choice two bottle test. It appeared that only the water preferring rats were affected by treatment with the hormone and that in vivo voltammetric related levels of melatonin were higher in the pineal gland of ethanol drinking rats versus water preferring rats. In addition, when treated with the melatonin antagonist GR128107 ethanol drinking rats significantly reduced the spontaneous consumption of alcohol.

  8. Application of voltammetric techniques at microelectrodes to the study of the chemical stability of highly reactive species.

    Science.gov (United States)

    Laborda, Eduardo; Olmos, José-Manuel; Torralba, Encarnación; Molina, Angela

    2015-02-03

    The application of voltammetric techniques to the study of chemical speciation and stability is addressed both theoretically and experimentally in this work. In such systems, electrode reactions are coupled to homogeneous chemical equilibria (complexations, protonations, ion associations, ...) that can be studied in a simple, economical, and accurate way by means of electrochemical methods. These are of particular interest when some of the participating species are unstable given that the generation and characterization of the species are performed in situ and on a short time scale. With the above aim, simple explicit solutions are presented in this article for quantitative characterization with any voltammetric technique and with the most common electrode geometries. From the theoretical results obtained, it is pointed out that the use of square-wave voltammetry in combination with microelectrodes is very suitable. Finally, the theory is applied to the investigation of the ion association between the anthraquinone radical monoanion and the tetrabutylammonium cation in acetonitrile medium.

  9. Selective Voltammetric Determination of Uric Acid in the Presence of Ascorbic Acid at Ordered Mesoporous Carbon Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    WEN,Yan-Li; JIA,Neng-Qin; WANG,Zhi-Yong; SHEN,He-Bai

    2008-01-01

    A novel chemically modified electrode was fabricated by immobilizing ordered mesoporous carbon (OMC)onto a glassy carbon (GC) electrode.The electrocatalytic behavior of the OMC modified electrode towards the oxidation of uric acid (UA) and ascorbic acid (AA) was studied.Compared to a glassy carbon electrode,the OMC modified electrode showed a faster electron transfer rate and reduced the overpotentials greatly.Furthermore,the OMC modified electrode resolved the overlapping voltammetric responses of UA and AA into two well-defined voltammetric peaks with peak separation of ca.0.38 V.All results show that the OMC modified electrode has a good electrocatalytic ability to UA and AA,and has an excellent response towards UA even in the presence of high concentration AA.

  10. Investigation of voltammetric enzyme-linked immunoassay based on new system of ODA-H2O2-HRP

    Institute of Scientific and Technical Information of China (English)

    焦奎; 张书圣; 韦璐

    1996-01-01

    A voltammetric enzyme-linked immunoassay based on a new system of ODA-H2O2-HRP has first been developed and used in the detection of HRP and labelled HRP. By this method, the enzyme-catalyzing reaction of H2O2 oxidizing odianisidine (ODA) couples the electrode-reduction reaction of the oxidizing product of odianisidine, which produces a sensitive polarographic wave at potential of -0.56V (SCE) in Britton-Robinson buffer solution. In using this polarographic wave, a detection limit to HRP is 3.7×10-12g/mL and a linear range 1.0×10-11-2.0×10-9g/mL. And the mechanisms of the coupling reaction and the process of electro-reduction in the ODA-H2O2-HRP voltammetric enzyme-linked immunoassay system have also been carefully studied.

  11. Batteries: Overview of Battery Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Doeff, Marca M

    2010-07-12

    The very high theoretical capacity of lithium (3829 mAh/g) provided a compelling rationale from the 1970's onward for development of rechargeable batteries employing the elemental metal as an anode. The realization that some transition metal compounds undergo reductive lithium intercalation reactions reversibly allowed use of these materials as cathodes in these devices, most notably, TiS{sub 2}. Another intercalation compound, LiCoO{sub 2}, was described shortly thereafter but, because it was produced in the discharged state, was not considered to be of interest by battery companies at the time. Due to difficulties with the rechargeability of lithium and related safety concerns, however, alternative anodes were sought. The graphite intercalation compound (GIC) LiC{sub 6} was considered an attractive candidate but the high reactivity with commonly used electrolytic solutions containing organic solvents was recognized as a significant impediment to its use. The development of electrolytes that allowed the formation of a solid electrolyte interface (SEI) on surfaces of the carbon particles was a breakthrough that enabled commercialization of Li-ion batteries. In 1990, Sony announced the first commercial batteries based on a dual Li ion intercalation system. These devices are assembled in the discharged state, so that it is convenient to employ a prelithiated cathode such as LiCoO{sub 2} with the commonly used graphite anode. After charging, the batteries are ready to power devices. The practical realization of high energy density Li-ion batteries revolutionized the portable electronics industry, as evidenced by the widespread market penetration of mobile phones, laptop computers, digital music players, and other lightweight devices since the early 1990s. In 2009, worldwide sales of Li-ion batteries for these applications alone were US$ 7 billion. Furthermore, their performance characteristics (Figure 1) make them attractive for traction applications such as

  12. Batteries: Overview of Battery Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Doeff, Marca M

    2010-07-12

    The very high theoretical capacity of lithium (3829 mAh/g) provided a compelling rationale from the 1970's onward for development of rechargeable batteries employing the elemental metal as an anode. The realization that some transition metal compounds undergo reductive lithium intercalation reactions reversibly allowed use of these materials as cathodes in these devices, most notably, TiS{sub 2}. Another intercalation compound, LiCoO{sub 2}, was described shortly thereafter but, because it was produced in the discharged state, was not considered to be of interest by battery companies at the time. Due to difficulties with the rechargeability of lithium and related safety concerns, however, alternative anodes were sought. The graphite intercalation compound (GIC) LiC{sub 6} was considered an attractive candidate but the high reactivity with commonly used electrolytic solutions containing organic solvents was recognized as a significant impediment to its use. The development of electrolytes that allowed the formation of a solid electrolyte interface (SEI) on surfaces of the carbon particles was a breakthrough that enabled commercialization of Li-ion batteries. In 1990, Sony announced the first commercial batteries based on a dual Li ion intercalation system. These devices are assembled in the discharged state, so that it is convenient to employ a prelithiated cathode such as LiCoO{sub 2} with the commonly used graphite anode. After charging, the batteries are ready to power devices. The practical realization of high energy density Li-ion batteries revolutionized the portable electronics industry, as evidenced by the widespread market penetration of mobile phones, laptop computers, digital music players, and other lightweight devices since the early 1990s. In 2009, worldwide sales of Li-ion batteries for these applications alone were US$ 7 billion. Furthermore, their performance characteristics (Figure 1) make them attractive for traction applications such as

  13. Non-conductive nanomaterial enhanced electrochemical response in stripping voltammetry: The use of nanostructured magnesium silicate hollow spheres for heavy metal ions detection.

    Science.gov (United States)

    Xu, Ren-Xia; Yu, Xin-Yao; Gao, Chao; Jiang, Yu-Jing; Han, Dong-Dong; Liu, Jin-Huai; Huang, Xing-Jiu

    2013-08-06

    Nanostructured magnesium silicate hollow spheres, one kind of non-conductive nanomaterials, were used in heavy metal ions (HMIs) detection with enhanced performance for the first time. The detailed study of the enhancing electrochemical response in stripping voltammetry for simultaneous detection of ultratrace Cd(2+), Pb(2+), Cu(2+) and Hg(2+) was described. Electrochemical properties of modified electrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The operational parameters which have influence on the deposition and stripping of metal ions, such as supporting electrolytes, pH value, and deposition time were carefully studied. The anodic stripping voltammetric performance toward HMIs was evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The detection limits achieved (0.186nM, 0.247nM, 0.169nM and 0.375nM for Cd(2+), Pb(2+), Cu(2+) and Hg(2+)) are much lower than the guideline values in drinking water given by the World Health Organization (WHO). In addition, the interference and stability of the modified electrode were also investigated under the optimized conditions. An interesting phenomenon of mutual interference between different metal ions was observed. Most importantly, the sensitivity of Pb(2+) increased in the presence of certain concentrations of other metal ions, such as Cd(2+), Cu(2+) and Hg(2+) both individually and simultaneously. The proposed electrochemical sensing method is thus expected to open new opportunities to broaden the use of SWASV in analysis for detecting HMIs in the environment.

  14. Assessments of the Effect of Increasingly Severe Cathodic Pretreatments on the Electrochemical Activity of Polycrystalline Boron-Doped Diamond Electrodes.

    Science.gov (United States)

    Brocenschi, Ricardo F; Hammer, Peter; Deslouis, Claude; Rocha-Filho, Romeu C

    2016-05-17

    The electrochemical response of many redox species on boron-doped diamond (BDD) electrodes can be strongly dependent on the type of chemical termination on their surface, hydrogen (HT-BDD) or oxygen (OT-BDD). For instance, on an HT-BDD electrode the [Fe(CN)6](3-/4-) redox system presents a reversible voltammetric behavior, whereas the oxidation overpotential of ascorbic acid (AA) is significantly decreased. Moreover, the electrochemical activity of BDD electrodes can be significantly affected by electrochemical pretreatments, with cathodic pretreatments (CPTs) leading to redox behaviors associated with HT-BDD. Here we report on the effect of increasingly severe CPTs on the electrochemical activity of a highly doped BDD electrode, assessed with the [Fe(CN)6](3-/4-) and AA redox probes, and on the atomic bonding structure on the BDD surface, assessed by XPS. The hydrogenation level of the BDD surface was increased by CPTs, leading to decreases of the total relative level of oxidation of the BDD surface of up to 36%. Contrary to what is commonly assumed, we show that BDD surfaces do not need to be highly hydrogenated to ensure that a reversible voltammetric behavior is obtained for Fe(CN)6](3-/4-); after a CPT, this was attained even when the total relative level of oxidation on the BDD surface was about 15%. At the same time, the overpotential for AA oxidation was confirmed as being very sensitive to the level of oxidation of the BDD surface, a behavior that might allow the use of AA as a secondary indicator of the relative atomic bonding structure on the BDD surface.

  15. Plasma distribution of cathodic ARC deposition system

    Energy Technology Data Exchange (ETDEWEB)

    Anders, S.; Raoux, S.; Krishnan, K.; MacGill, R.A.; Brown, I.G. [Lawrence Berkeley National Lab., CA (United States)

    1996-08-01

    The plasma distribution using a cathodic arc plasma source with and without magnetic macroparticle filter has been determined by depositing on a transparent plastic substrate and measuring the film absorption. It was found that the width of the distribution depends on the arc current, and it also depends on the cathode material which leads to a spatial separation of the elements when an alloy cathode is used. By applying a magnetic multicusp field near the exit of the magnetic filter, it was possible to modify the plasma distribution and obtain a flat plasma profile with a constant and homogeneous elemental distribution.

  16. Electrochemical Impedance Studies of SOFC Cathodes

    DEFF Research Database (Denmark)

    Hjelm, Johan; Søgaard, Martin; Wandel, Marie

    2007-01-01

    impedance of the cathode at intermediate operating temperatures. The perovskite is of the La-Sr-Co-Fe type. The EIS response of symmetrical cells with a thick (similar to 200 mu m) gadolinia doped ceria electrolyte was compared with the impedance contribution of the cathode of a full anode supported cell....... The full cells had a Ni-YSZ anode and anode support, a thin YSZ electrolyte, and a CGO barrier layer. The symmetric and full cell cathode responses were compared at open-circuit voltage. Humidified hydrogen was used as the fuel in the full cell measurements. Differential analysis of the impedance data...

  17. Anodic Stripping Voltammetry: An Instrumental Analysis Experiment.

    Science.gov (United States)

    Wang, Joseph

    1983-01-01

    Describes an experiment designed to acquaint students with the theory and applications of anodic stripping voltammetry (ASV) as well as such ASV problems as contamination associated with trace analysis. The experimental procedure, instrumentation, and materials discussed are designed to minimize cost and keep procedures as simple as possible. (JM)

  18. Improved lower bound for online strip packing

    NARCIS (Netherlands)

    Harren, Rolf; Kern, Walter

    2015-01-01

    We study the online strip packing problem and derive an improved lower bound of ρ ≥ 2.589... for the competitive ratio of this problem. The construction is based on modified “Brown-Baker-Katseff sequences” (Brown et al. in Acta Inform. 18:207–225, 1982) using only two types of rectangles. In additio

  19. Cardiac Muscle Studies with Rat Ventricular Strips

    Science.gov (United States)

    Whitten, Bert K.; Faleschini, Richard J.

    1977-01-01

    Details undergraduate physiology laboratory experiments that demonstrate mechanical properties of cardiac muscle, using strips from the ventricle of a rat heart. Includes procedures for obtaining length-tension curves, demonstrating the role of calcium in excitation-contraction coupling, and showing effects of several cardiovascular drugs…

  20. Asset Stripping in a Mature Market Economy

    DEFF Research Database (Denmark)

    Klarskov Jeppesen, Kim; Møller, Ulrik Gorm

    2011-01-01

    indicates that asset stripping may take place in mature market economies to the extent that perpetrators are able to circumvent the corporate governance system by giving lawyers, public accountants and banks incentives to act less critically towards dubious business transactions. Research limitations...

  1. Propulsion by Helical Strips in Circular Channels

    Science.gov (United States)

    Yesilyurt, Serhat; Demir, Ebru

    2016-11-01

    Progress in manufacturing techniques avails the production of artificial micro swimmers (AMS) in various shapes and sizes. There are numerous studies on the generation of efficient locomotion by means of helical tails with circular cross-sections. This work focuses on locomotion with helical strips in circular channels. A CFD model is used to analyze the effects of geometric parameters and the radius of the channel on swimming velocity of infinite helical-strips in circular channels. Results show that there is an optimum wavelength that depends on thickness to channel radius ratio, suggesting that these parameters need to be optimized simultaneously. With constant torque, thinner strips swim faster, whereas under constant angular velocity application, thicker strips (in radial direction) prevail. As width approaches the wavelength, velocity decreases under both conditions, unless a magnetically coated tail is simulated, for which width has an optimum value. Increasing channel radius to helix amplitude ratio increases the velocity up to a maximum and after a slight drop, saturation occurs as bulk swimming conditions are approached.

  2. Comic Strips to Accompany Science Museum Exhibits

    Science.gov (United States)

    Chung, Beom Sun; Park, Eun-mi; Kim, Sang-Hee; Cho, Sook-kyoung; Chung, Min Suk

    2016-01-01

    Science museums make the effort to create exhibits with amusing explanations. However, existing explanation signs with lengthy text are not appealing, and as such, visitors do not pay attention to them. In contrast, conspicuous comic strips composed of simple drawings and humors can attract science museum visitors. This study attempted to reveal…

  3. Nanoscale Test Strips for Multiplexed Blood Analysis

    Science.gov (United States)

    Chan, Eugene

    2015-01-01

    A critical component of the DNA Medicine Institute's Reusable Handheld Electrolyte and Lab Technology for Humans (rHEALTH) sensor are nanoscale test strips, or nanostrips, that enable multiplexed blood analysis. Nanostrips are conceptually similar to the standard urinalysis test strip, but the strips are shrunk down a billionfold to the microscale. Each nanostrip can have several sensor pads that fluoresce in response to different targets in a sample. The strips carry identification tags that permit differentiation of a specific panel from hundreds of other nanostrip panels during a single measurement session. In Phase I of the project, the company fabricated, tested, and demonstrated functional parathyroid hormone and vitamin D nanostrips for bone metabolism, and thrombin aptamer and immunoglobulin G antibody nanostrips. In Phase II, numerous nanostrips were developed to address key space flight-based medical needs: assessment of bone metabolism, immune response, cardiac status, liver metabolism, and lipid profiles. This unique approach holds genuine promise for space-based portable biodiagnostics and for point-of-care (POC) health monitoring and diagnostics here on Earth.

  4. Topics in Chemical Instrumentation: CII. Automated Anodic Stripping Voltammetry.

    Science.gov (United States)

    Stock, John T.; Ewing, Galen W., Ed.

    1980-01-01

    Presents details of anodic stripping analysis (ASV) in college chemistry laboratory experiments. Provides block diagrams of the analyzer system, circuitry and power supplies of the automated stripping analyzer, and instructions for implementing microcomputer control of the ASV. (CS)

  5. Comparative evaluation of scanned stripping techniques: SSCP vs. SSV

    NARCIS (Netherlands)

    Town, R.M.; Leeuwen, van H.P.

    2006-01-01

    The characteristic features of scanned deposition potential curves constructed from stripping chronopotentiometry (SSCP) and various modes of stripping voltammetry (SSV) are critically evaluated. The strengths and weaknesses of each method for identification of metal ion speciation features and susc

  6. Refuges, flower strips, biodiversity and agronomic interest.

    Science.gov (United States)

    Roy, Grégory; Wateau, Karine; Legrand, Mickaël; Oste, Sandrine

    2008-01-01

    Several arthropods are natural predators of pests, and they are able to reduce and control their population development. FREDON Nord Pas-de-Calais (Federation Regionate de Defense contre les Organismes Nuisibles = Regional Federation for Pest Control) has begun for a long time to form farmers to the recognition of beneficial arthropods and to show them their usefulness. These beneficial insects or arachnids are present everywhere, in orchards and even in fields which are areas relatively poor in biodiversity. Adults feed in the flower strips instead larvae and some adults feed on preys such as aphids or caterpillars. Most of the time, beneficial insects can regulate pest but sometimes, in agricultural area, they can't make it early enough and efficiently. Their action begin too late and there biodiversity and number are too low. It's possible to enhance their action by manipulating the ecological infrastructures, like sewing flower strips or installing refuges. Flower strips increase the density of natural enemies and make them be present earlier in the field in order to control pests. Refuges permit beneficial's to spend winter on the spot. So they're able to be active and to grow in number earlier. From 2004 to 2007, on the one hand, FREDON Nord Pas-de-Calais has developed a research program. Its purpose was to inventory practices and also tools and means available and to judge the advisability of using such or such beneficial refuge in orchards. On the second hand, it studied the impact in orchard of refuges on population of beneficial's and the difference there were between manufactured refuges and homemade refuges. Interesting prospects were obtained with some of them. Otherwise, since 2003, FREDON has studied flower strips influence on beneficial population and their impact on pest control. In cabbage fields, results of trials have shown that flower strips lead to a reduction of aphid number under acceptable economic level, up to 50 meters from flower strips

  7. Utility of Activated Glassy Carbon and Pencil Graphite Electrodes for Voltammetric Determination of Nalbuphine Hydrochloride in Pharmaceutical and Biological Fluids

    Directory of Open Access Journals (Sweden)

    Hoda M. Elqudaby

    2016-01-01

    Full Text Available This work compares voltammetric response of nalbuphine hydrochloride (NP·HCl at both activated glassy carbon and pencil graphite electrodes. The electrochemical oxidation of the drug was studied using cyclic voltammetry (CV, differential pulse voltammetry (DPV, and square wave voltammetry (SWV techniques. For analytical purpose a well-resolved irreversible diffusion controlled voltammetric peak was established in Britton-Robinson (B-R buffer solution of pH 6.00 using pencil graphite electrode (PGE. Using activated glassy carbon electrode (GCE a well-resolved irreversible diffusion controlled voltammetric peak was obtained at pH 7.00 using the same buffer solution. According to the linear relationship between the peak current and NP·HCl concentration, DPV and SWV methods were developed for their quantitative determination in pharmaceutical and human biological fluids. The linear response was obtained in the range from 1.6×10-5 to 1.5×10-4 mol L−1 using PGE and from 12.5×10-6 to 13.75×10-5 mol L−1 using a GC electrode, respectively. Precision and accuracy of the developed method were checked by recovery studies.

  8. Dual Strip-Excited Dielectric Resonator Antenna with Parasitic Strips for Radiation Pattern Reconfigurability

    Directory of Open Access Journals (Sweden)

    M. Kamran Saleem

    2014-01-01

    Full Text Available A novel pattern reconfigurable antenna concept utilizing rectangular dielectric resonator antenna (DRA placed over dielectric substrate backed by a ground plane is presented. A dual strip excitation scheme is utilized and both excitation strips are connected together by means of a 50 Ω microstrip feed network placed over the substrate. The four vertical metallic parasitic strips are placed at corner of DRA each having a corresponding ground pad to provide a short/open circuit between the parasitic strip and antenna ground plane, through which a shift of 90° in antenna radiation pattern in elevation plane is achieved. A fractional bandwidth of approximately 40% at center frequency of 1.6 GHz is achieved. The DRA peak realized gain in whole frequency band of operation is found to be above 4 dB. The antenna configuration along with simulation and measured results are presented.

  9. Advances in Thermionic Cathode of Tungsten and Molybdenum

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Several kinds of tungsten thermonic cathodes have been introduced. As a promising alternative for thoriated tungsten, rare earth doped molybdenum cathode has been studied. Compared with the traditional thoriated tungsten, La-Mo cathode has higher emission current density at lower temperature, but it has poor emission stability. In order to improve the emission stability, systematical study on the emission mechanism of La-Mo cathode has been carried out. The life of La-Mo cathode has been improved and has achieved 1400 h, which exceeds the minimum life for practical uses (1000 h). As another alternative for thoriated tungsten cathode, Y-Mo cathode has shown better performance. The thermionic emission capability of Y-Mo cathode is between that of La-Mo cathode and Th-W cathode.

  10. Strip reduction testing of lubricants developed during ENFORM project

    DEFF Research Database (Denmark)

    Gazvoda, S.; Andreasen, Jan Lasson; Olsson, David Dam

    Strip reduction testing of lubricants developed during ENFORM project. Experiments were conducted with the strip reduction test [1] in order to classify experimental lubricants, developed during concerned project. One reference lubricant was used during testing.......Strip reduction testing of lubricants developed during ENFORM project. Experiments were conducted with the strip reduction test [1] in order to classify experimental lubricants, developed during concerned project. One reference lubricant was used during testing....

  11. TOMOGRAPHIC MEASUREMENT OF LONGITUDINAL EMITTANCE GROWTH DUE TO STRIPPING FOILS.

    Energy Technology Data Exchange (ETDEWEB)

    MONTAG, C.; AHRENS, L.; THIEBERGER, P.

    2005-05-16

    During beam acceleration in the Brookhaven accelerator complex, heavy ions are stripped of their electrons in several steps. Depending on the properties of the stripping foils, this process results in an increased energy spread and longitudinal emittance growth. A tomographic phase space reconstruction technique has been applied to measure the associated emittance growth for different stripping foil materials.

  12. RF Electron Gun with Driven Plasma Cathode

    CERN Document Server

    Khodak, Igor

    2005-01-01

    It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

  13. Reservoir Scandate Cathode for Electric Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to combine two revolutionary cathode technologies into a single device for use in electric space propulsion. This will overcome problems that both...

  14. Modeling High Pressure Micro Hollow Cathode Discharges

    Science.gov (United States)

    2007-11-02

    cathode discharge excimer lamps , Phys. Plasmas 7, 286 (2000). [3] RH Stark and KH Schoenbach, Direct high pressure glow discharges, J. Appl. Phys...temperature profiles in argon glow discharges, J. Appl. Phys. 88, 2234 (2000) [8] M. Moselhy, W. Shi, R. Stark, A flat glow discharge excimer radiation...MHCD acts as a plasma cathode for a third electrode (anode). Some experimental results in this geometry are available for argon and for air from the

  15. Development of plasma cathode electron guns

    Science.gov (United States)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  16. Bird community response to filter strips in Maryland

    Science.gov (United States)

    Blank, P.J.; Dively, G.P.; Gill, D.E.; Rewa, C.A.

    2011-01-01

    Filter strips are strips of herbaceous vegetation planted along agricultural field margins adjacent to streams or wetlands and are designed to intercept sediment, nutrients, and agrichemicals. Roughly 16,000 ha of filter strips have been established in Maryland through the United States Department of Agriculture's Conservation Reserve Enhancement Program. Filter strips often represent the only uncultivated herbaceous areas on farmland in Maryland and therefore may be important habitat for early-successional bird species. Most filter strips in Maryland are planted to either native warm-season grasses or cool-season grasses and range in width from 10.7 m to 91.4 m. From 2004 to 2007 we studied the breeding and wintering bird communities in filter strips adjacent to wooded edges and non-buffered field edges and the effect that grass type and width of filter strips had on bird community composition. We used 5 bird community metrics (total bird density, species richness, scrub-shrub bird density, grassland bird density, and total avian conservation value), species-specific densities, nest densities, and nest survival estimates to assess the habitat value of filter strips for birds. Breeding and wintering bird community metrics were greater in filter strips than in non-buffered field edges but did not differ between cool-season and warm-season grass filter strips. Most breeding bird community metrics were negatively related to the percent cover of orchardgrass (Dactylis glomerata) in ???1 yr. Breeding bird density was greater in narrow (60 m) filter strips. Our results suggest that narrow filter strips adjacent to wooded edges can provide habitat for many bird species but that wide filter strips provide better habitat for grassland birds, particularly obligate grassland species. If bird conservation is an objective, avoid planting orchardgrass in filter strips and reduce or eliminate orchardgrass from filter strips through management practices. Copyright ?? 2011 The

  17. Improving Thin Strip Profile Using Work Roll Cross and Work Roll Shifting Methods in Cold Strip Rolling

    Directory of Open Access Journals (Sweden)

    Hasan Tibar

    2017-01-01

    Full Text Available The optimization of rolling parameters in order to achieve better strip shape and to reduce rolling force is a challenge in rolling practice. In this paper, thin strip asymmetrical rolling of aluminum at various speed ratios under lubricated condition has been investigated at various combinations of work rolls cross (WRC angles and work rolls shifting (WRS values. The effects of strip width, reduction, and rolling speed on strip shape taking WRC and WRS into consideration are discussed. Results show that strip profile improves significantly when the WRC angle is increased from 0° to 1°, with an associated reduction in rolling force. Increasing WRS value from 0 to 8 mm improves the strip profile as well but not as significantly as when WRC angle is increased. No significant improvement was found in strip shape when the strip width was increased. At higher reduction, the strip shape was improved; a decrease in the rolling force was also observed. A higher speed ratio was found to be effective only at a higher WRC angle. The effect of lubrication on the strip profile was significant. Results indicate that an optimum combination of WRC, WRS, reduction, width, and speed ratio under lubricated conditions can ensure an improved exit strip profile, reduce rolling force, and obtain a better quality strip.

  18. Determination of tryptamine in foods using square wave adsorptive stripping voltammetry.

    Science.gov (United States)

    Costa, Daniel J E; Martínez, Ana M; Ribeiro, Williame F; Bichinho, Kátia M; Di Nezio, María Susana; Pistonesi, Marcelo F; Araujo, Mario C U

    2016-07-01

    Tryptamine, a biogenic amine, is an indole derivative with an electrophilic substituent at the C3 position of the pyrrole ring of the indole moiety. The electrochemical oxidation of tryptamine was investigated using glassy carbon electrode (GCE), and focusing on trace level determination in food products by square wave adsorptive stripping voltammetry (SWAdSV). The electrochemical responses of tryptamine were evaluated using differing voltammetric techniques over a wide pH range, a quasi-reversible electron-transfer to redox system represented by coupled peaks P1-P3, and an irreversible reaction for peak P2 were demonstrated. The proton and electron counts associated with the oxidation reactions were estimated. The nature of the mass transfer process was predominantly diffusion-limited for the oxidation process of P1, the most selective and sensitive analytical response (acetate buffer solution pH 5.3), being used for the development of SWAdSV method, under optimum conditions. The excellent response allowed the development of an electroanalytical method with a linear response range of from 4.7-54.5)×10(-)(8)molL(-1), low detection limit (0.8×10(-)(9)molL(-)(1)), and quantification limit (2.7×10(-9)molL(-1)), and acceptable levels of repeatability (3.6%), and reproducibility (3.8%). Tryptamine content was determined in bananas, tomatoes, cheese (mozzarella and gorgonzola), and cold meats (chicken sausage and pepperoni sausage), yielding recoveries above 90%, with excellent analytical performance using simple and low cost instrumentation.

  19. Electrochemical Investigation of Catechol at Poly(niacinamide Modified Carbon Paste Electrode: A Voltammetric Study

    Directory of Open Access Journals (Sweden)

    A. B. Teradale

    2016-01-01

    Full Text Available A polymeric thin film modified electrode, that is, poly(niacinamide modified carbon paste electrode (MCPE, was developed for the electrochemical determination of catechol (CC by using cyclic voltammetric technique. Compared to bare carbon paste electrode (BCPE, the poly(niacinamide MCPE shows good electrocatalytic activity towards the oxidation of catechol in phosphate buffer solution (PBS of physiological pH 7.4. All experimental parameters were optimized. Poly(niacinamide modified carbon paste electrode gave a linear response between concentration of CC and its anodic peak current in the range within 20.6–229.0 μM. The limit of detection (3S/M and limit of quantification (10S/M were 1.497 μM and 4.99 μM, respectively. From the study of scan rate variation, the electrode process was found to be adsorption-controlled. The involvement of protons and electrons in the oxidation of CC was found to be equal. The probable electropolymerisation mechanism of niacinamide was proposed. Finally, this method can be used in development of a sensor for sensitive determination of CC.

  20. Classification and prediction of rice wines with different marked ages by using a voltammetric electronic tongue.

    Science.gov (United States)

    Wei, Zhenbo; Wang, Jun; Ye, Linshuang

    2011-08-15

    A voltammetric electronic tongue (VE-tongue) was developed to discriminate the difference between Chinese rice wines in this research. Three types of Chinese rice wine with different marked ages (1, 3, and 5 years) were classified by the VE-tongue by principal component analysis (PCA) and cluster analysis (CA). The VE-tongue consisted of six working electrodes (gold, silver, platinum, palladium, tungsten, and titanium) in a standard three-electrode configuration. The multi-frequency large amplitude pulse voltammetry (MLAPV), which consisted of four segments of 1 Hz, 10 Hz, 100 Hz, and 1000 Hz, was applied as the potential waveform. The three types of Chinese rice wine could be classified accurately by PCA and CA, and some interesting regularity is shown in the score plots with the help of PCA. Two regression models, partial least squares (PLS) and back-error propagation-artificial neural network (BP-ANN), were used for wine age prediction. The regression results showed that the marked ages of the three types of Chinese rice wine were successfully predicted using PLS and BP-ANN.

  1. Maize tassel-modified carbon paste electrode for voltammetric determination of Cu(II).

    Science.gov (United States)

    Moyo, Mambo; Okonkwo, Jonathan O; Agyei, Nana M

    2014-08-01

    The preparation and application of a practical electrochemical sensor for environmental monitoring and assessment of heavy metal ions in samples is a subject of considerable interest. In this paper, a carbon paste electrode modified with maize tassel for the determination of Cu(II) has been proposed. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study morphology and identify the functional groups on the modified electrode, respectively. First, Cu(II) was adsorbed on the carbon paste electrode surface at open circuit and voltammetric techniques were used to investigate the electrochemical performances of the sensor. The electrochemical sensor showed an excellent electrocatalytic activity towards Cu(II) at pH 5.0 and by increasing the amount of maize tassel biomass, a maximum response at 1:2.5 (maize tassel:carbon paste; w/w) was obtained. The electrocatalytic redox current of Cu(II) showed a linear response in the range (1.23 μM to 0.4 mM) with the correlation coefficient of 0.9980. The limit of detection and current-concentration sensitivity were calculated to be 0.13 (±0.01) μM and 0.012 (±0.001) μA/μM, respectively. The sensor gave good recovery of Cu(II) in the range from 96.0 to 98.0 % when applied to water samples.

  2. New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study.

    Science.gov (United States)

    Gulaboski, Rubin; Bogeski, Ivan; Kokoskarova, Pavlinka; Haeri, Haleh H; Mitrev, Sasa; Stefova, Marina; Stanoeva, Jasmina Petreska; Markovski, Velo; Mirčeski, Valentin; Hoth, Markus; Kappl, Reinhard

    2016-10-01

    Coenzyme Q-0 (CoQ-0) is the only Coenzyme Q lacking an isoprenoid group on the quinoid ring, a feature important for its physico-chemical properties. Here, the redox behavior of CoQ-0 in buffered and non-buffered aqueous media was examined. In buffered aqueous media CoQ-0 redox chemistry can be described by a 2-electron-2-proton redox scheme, characteristic for all benzoquinones. In non-buffered media the number of electrons involved in the electrode reaction of CoQ-0 is still 2; however, the number of protons involved varies between 0 and 2. This results in two additional voltammetric signals, attributed to 2-electrons-1H(+) and 2-electrons-0H(+) redox processes, in which mono- and di-anionic compounds of CoQ-0 are formed. In addition, CoQ-0 exhibits a complex chemistry in strong alkaline environment. The reaction of CoQ-0 and OH(-) anions generates several hydroxyl derivatives as products. Their structures were identified with HPLC/MS. The prevailing radical reaction mechanism was analyzed by electron paramagnetic resonance spectroscopy. The hydroxyl derivatives of CoQ-0 have a strong antioxidative potential and form stable complexes with Ca(2+) ions. In summary, our results allow mechanistic insights into the redox properties of CoQ-0 and its hydroxylated derivatives and provide hints on possible applications.

  3. Electrodeposited apatite coating for solid-phase microextraction and sensitive indirect voltammetric determination of fluoride ions.

    Science.gov (United States)

    Mao, Yuehong; Chen, Yufei; Chu, Lin; Zhang, Xiaoli

    2013-10-15

    Electrodeposition was used to prepare a new solid phase microextraction (SPME) coatings. Two apatite SPME coatings, dicalcium phosphate dihydrate (DCPD or brushite) and hydroxyapatite (HAP) were validly and homogeneously one-step electrodeposited on glassy carbon electrode (GCE) under different conditions. The coatings were characterized by XRD, FTIR, SEM, CV and EIS. The apatite SPME coatings showed excellent and selective adsorbability to fluoride ions. A novel indirect voltammetric strategy for sensitive detection of fluoride was proposed using K3Fe(CN)6 as indicating probe. The detection principle of fluoride ions was based on the increment of steric hindrance after fluoride adsorption, which resulting in the decrease of the amperometric signal to Fe(CN)6(3-). The liner ranges were 0.5-20.0 μmol/L for n-DCPD/GCE with the limit of detection of 0.14 μmol/L and 0.1-50.0 μmol/L for n-HAP/GCE with the limit of detection of 0.069 μmol/L, respectively. The developed method was applied to the analysis of water samples (lake, spring and tap water) and the recovery values were found to be in the range of 90-106%.

  4. Detection of antibiotic residues in bovine milk by a voltammetric electronic tongue system.

    Science.gov (United States)

    Wei, Zhenbo; Wang, Jun

    2011-05-23

    A voltammetric electronic tongue (VE-tongue) was developed to detect antibiotic residues in bovine milk. Six antibiotics (Chloramphenicol, Erythromycin, Kanamycin sulfate, Neomycin sulfate, Streptomycin sulfate and Tetracycline HCl) spiked at four different concentration levels (0.5, 1, 1.5 and 2 maximum residue limits (MRLs)) were classified based on VE-tongue by two pattern recognition methods: principal component analysis (PCA) and discriminant function analysis (DFA). The VE-tongue was composed of five working electrodes (gold, silver, platinum, palladium, and titanium) positioned in a standard three-electrode configuration. The Multi-frequency large amplitude pulse voltammetry (MLAPV) which consisted of four segments (1 Hz, 10 Hz, 100 Hz and 1000 Hz) was applied as potential waveform. The six antibiotics at the MRLs could not be separated from bovine milk completely by PCA, but all the samples were demarcated clearly by DFA. Three regression models: Principal Component Regression Analysis (PCR), Partial Least Squares Regression (PLSR), and Least Squares-Support Vector Machines (LS-SVM) were used for concentrations of antibiotics prediction. All the regression models performed well, and PCR had the most stable results.

  5. Mesoporous carbon-containing voltammetric biosensor for determination of tyramine in food products.

    Science.gov (United States)

    Kochana, Jolanta; Wapiennik, Karolina; Knihnicki, Paweł; Pollap, Aleksandra; Janus, Paula; Oszajca, Marcin; Kuśtrowski, Piotr

    2016-07-01

    A voltammetric biosensor based on tyrosinase (TYR) was developed for determination of tyramine. Carbon material (multi-walled carbon nanotubes or mesoporous carbon CMK-3-type), polycationic polymer-i.e., poly(diallyldimethylammonium chloride) (PDDA), and Nafion were incorporated into titania dioxide sol (TiO2) to create an immobilization matrix. The features of the formed matrix were studied by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The analytical performance of the developed biosensor was evaluated with respect to linear range, sensitivity, limit of detection, long-term stability, repeatability, and reproducibility. The biosensor exhibited electrocatalytic activity toward tyramine oxidation within a linear range from 6 to 130 μM, high sensitivity of 486 μA mM(-1) cm(-2), and limit of detection of 1.5 μM. The apparent Michaelis-Menten constant was calculated to be 66.0 μM indicating a high biological affinity of the developed biosensor for tyramine. Furthermore, its usefulness in determination of tyramine in food product samples was also verified. Graphical abstract Different food samples were analyzed to determine tyramine using biosensor based on tyrosinase.

  6. Gold nanoparticles modified carbon paste electrode for differential pulse voltammetric determination of eugenol.

    Science.gov (United States)

    Afzali, Daryoush; Zarei, Somaye; Fathirad, Fariba; Mostafavi, Ali

    2014-10-01

    In the present study, a carbon paste electrode chemically modified with gold nanoparticles was used as a sensitive electrochemical sensor for determination of eugenol. The differential pulse voltammetric method was employed to study the behavior of eugenol on this modified electrode. The effect of variables such as percent of gold nanoparticles, pH of solution, accumulation potential and time on voltammogram peak current were optimized. The proposed electrode showed good oxidation response for eugenol in 0.1 mol L(-1) phosphate buffer solution (pH8) and the peak potential was about +285 mV (vs. Ag/AgCl). The peak current increased linearly with the eugenol concentration in the range of 5-250 μmol L(-1). The detection limit was found to be 2.0 μmol L(-1) and the relative standard deviation was 1.2% (n=7). The effect of interferences on the eugenol peak current was studied. The method has been applied to the determination of eugenol in different real samples, spiked recoveries were in the range of 96%-99%.

  7. Differential pulse voltammetric determination of eugenol at a pencil graphite electrode.

    Science.gov (United States)

    Sağlam, Özlem; Dilgin, Didem Giray; Ertek, Bensu; Dilgin, Yusuf

    2016-03-01

    In this study, the electrochemical behavior of eugenol, a widely used herbal drug, was investigated at a pencil graphite electrode (PGE). A low-cost, disposable, sensitive and selective electrochemical sensor is proposed for the determination of eugenol by recording its differential pulse voltammograms in Britton-Robinson buffer solution containing 0.1 M KCl with pH of 2.0 at the PGE. The PGE displayed a very good electrochemical behavior with significant enhancement of the peak current compared to a glassy carbon electrode. Under experimental conditions, the PGE had a linear response range from 0.3 μM to 50.0 μM eugenol with a detection limit of 0.085 μM (based on 3S(b)). Relative standard deviations of 2.4 and 4.8% were obtained for five successive determinations of 30.0 and 5.0 μM eugenol, respectively, which indicate acceptable repeatability. This voltammetric method was successfully applied for the direct determination of eugenol in real samples. The effect of various interfering compounds on the eugenol peak current was also studied.

  8. Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode

    Directory of Open Access Journals (Sweden)

    Anamaria Baciu

    2015-06-01

    Full Text Available This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix.

  9. Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode

    Science.gov (United States)

    Baciu, Anamaria; Ardelean, Magdalena; Pop, Aniela; Pode, Rodica; Manea, Florica

    2015-01-01

    This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD) electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix. PMID:26102487

  10. Enzyme-catalyzed reaction of voltammetric enzyme-linked immunoassay system based on OAP as substrate

    Institute of Scientific and Technical Information of China (English)

    张书圣; 陈洪渊; 焦奎

    1999-01-01

    The o-aminophenol (OAP)-H2O2-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay new system has extremely high sensitivity. HRP can be measured with a detection limit of 6.0×10-(10) g/L and a linear range of 1.0×10-9—4.0×10-6 g/L. The pure product of H2O2 oxidizing OAP catalyzed by HRP was prepared with chemical method. The enzyme-catalyzed reaction has been investigated with electroanalytical chemistry, UV/Vis spectrum, IR spectrum, 13C NMR, 1H NMR, mass spectrum, elemental analysis, etc. Under the selected enzyme-catalyzed reaction conditions, the oxidation product of OAP with H2O2 catalyzed by HRP is 2-aminophe-noxazine-3-one. The processes of the enzyme-catalyzed reaction and the electroreduction of the product of the enzymecatalyzed reaction have been described.

  11. Voltammetric Determination of Paraquat Using Graphite Pencil Electrode Modified with Doped Polypyrrole

    CERN Document Server

    Sayyahmanesh, Maryam; Meibodi, Azam S Emami; Ahooyi, Taha Mohseni

    2016-01-01

    Recognition and determination of paraquat (PQ) using graphite pencil electrode (GPE) modified with polypyrrole (Ppy) doped with Eriochrome blue-black B (EBB) is reported. To that end, a thin film of Ppy was deposited onto the electrode surface by electropolymerization in the presence of a functional doping ion, EBB. The Ppy/EBB-coated electrode was templated by PQ ion and then the performance of the molecularly imprinted EBB/Ppy/GPE was evaluated by voltammetric technique. The prepared electrode exhibited considerable increase in electroactivity of the sensor toward this herbicide compared to the non-imprinted electrode. To enhance the detection capability of the prepared system, the factors controlling its response were investigated and optimized using differential pulse voltammetry. The proposed analytical procedure was proved to be applicable in the concentration range of 5 to 50 {\\mu}M (R^2 = 0.9939) and detection limit of (3{\\sigma}) 0.22 {\\mu}M. Ultimately, the proposed analytical methodology was applie...

  12. Detection of antibiotic residues in bovine milk by a voltammetric electronic tongue system

    Energy Technology Data Exchange (ETDEWEB)

    Wei Zhenbo [Zhejiang University, Department of Bio-Systems Engineering, 268 Kaixuan Road, Hangzhou, Zhejiang 310029 (China); Wang Jun, E-mail: jwang@zju.edu.cn [Zhejiang University, Department of Bio-Systems Engineering, 268 Kaixuan Road, Hangzhou, Zhejiang 310029 (China)

    2011-05-23

    A voltammetric electronic tongue (VE-tongue) was developed to detect antibiotic residues in bovine milk. Six antibiotics (Chloramphenicol, Erythromycin, Kanamycin sulfate, Neomycin sulfate, Streptomycin sulfate and Tetracycline HCl) spiked at four different concentration levels (0.5, 1, 1.5 and 2 maximum residue limits (MRLs)) were classified based on VE-tongue by two pattern recognition methods: principal component analysis (PCA) and discriminant function analysis (DFA). The VE-tongue was composed of five working electrodes (gold, silver, platinum, palladium, and titanium) positioned in a standard three-electrode configuration. The Multi-frequency large amplitude pulse voltammetry (MLAPV) which consisted of four segments (1 Hz, 10 Hz, 100 Hz and 1000 Hz) was applied as potential waveform. The six antibiotics at the MRLs could not be separated from bovine milk completely by PCA, but all the samples were demarcated clearly by DFA. Three regression models: Principal Component Regression Analysis (PCR), Partial Least Squares Regression (PLSR), and Least Squares-Support Vector Machines (LS-SVM) were used for concentrations of antibiotics prediction. All the regression models performed well, and PCR had the most stable results.

  13. Synthesis, characterization and cyclic voltammetric study of copper(II) and nickel(II) polymer chelates.

    Science.gov (United States)

    Azmeera, Venkanna; Rastogi, Pankaj Kumar; Adhikary, Pubali; Ganesan, Vellaichamy; Krishnamoorthi, S

    2014-09-22

    Graft copolymers based on dextran (Dx) and 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) were synthesized by free radical initiated solution polymerization technique using ceric ammonium nitrate as initiator. These graft copolymers were used to prepare Cu(II) and Ni(II) chelates by reactions with Cu(II) and Ni(II) metal ions respectively. Graft copolymer and metal chelates were characterized by elemental analysis, intrinsic viscosity, FT-IR, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and powder X-ray diffraction (XRD). Elemental analysis, intrinsic viscosity and FT-IR studies revealed the incorporation of metal ions to form metal chelates. SEM studies showed the change in morphology due to metal incorporation. From AFM studies it was observed that there was increase in Root mean square (RMS) roughness values in case of metal complexes. Metal chelates were observed to be thermally more stable than graft copolymer from TGA. UV-vis spectroscopy study revealed increase in absorbance values and cyclic voltammetric (CV) studies showed more than tenfold increase in redox current due to formation of Cu(II) and Ni(II) metal chelates. The binding constants of each complex determined by using UV-visible spectroscopy revealed that Cu(II) has more binding ability than Ni(II).

  14. The Formation and Evolution of Stripped Dark Matter Halos

    Science.gov (United States)

    Zhu, Jessica; Tuan, Austin Zong; Lee, Christoph; Primack, Joel R.

    2016-01-01

    We implement a model to describe the density profiles of stripped dark matter halos. Our model generalizes the Navarro-Frenk-White (NFW) distribution to allow for more flexibility in the slope of the outer halo. We find that the density distributions of stripped halos tend to have outer slopes steeper than assumed by the NFW distribution. We also examine the relationship between severity of stripping and halo shape, spin parameter and concentration, and find that highly stripped halos are more spheroidal, have lower spin parameters, and have higher concentrations compared to less stripped halos.

  15. Shape Setup System for 1700 Hot Strip Mill

    Institute of Scientific and Technical Information of China (English)

    GUO Zhong-feng; XU Jian-zhong; LI Chang-sheng; LIU Xiang-hua

    2007-01-01

    Shape setup (SSU) system is the core technology for hot strip mill (HSM). A precise SSU system was used to improve the strip quality for HSM. The function of SSU, setup, and feedback was introduced. The main mathematical models of roll gap profile and longitudinal strain difference are set up. Strip profile allocation strategy was researched according to the SSU system of a domestic 1 700 mm HSM. The SSU system was put into practical use and the measurement results showed that strip flatness variation and strip profile variation could be controlled in target scope.

  16. Direct in situ measurement of dissolved zinc in the presence of zinc oxide nanoparticles using anodic stripping voltammetry.

    Science.gov (United States)

    Jiang, Chuanjia; Hsu-Kim, Heileen

    2014-11-01

    The wide use of metal-based nanomaterials such as zinc oxide (ZnO) nanoparticles (NPs) has generated concerns regarding their environmental and health risks. For ZnO NPs, their toxicity in aquatic systems often depends on the release of dissolved zinc species, and the rate of dissolution is influenced by water chemistry, including the presence of zinc-chelating ligands. A challenge, however, remains in quantifying the dissolution of ZnO NPs, particularly for time scales that are short enough to determine rates. This paper reports the application of anodic stripping voltammetry (ASV) with a hanging mercury drop electrode to directly measure the concentration of dissolved zinc in ZnO NP suspensions, without separation of the ZnO NPs from the aqueous phase. The effects of the deposition time and the electrochemical potential scan rate on the ASV measurement were consistent with expectations for dissolved phase measurements. The dissolved zinc concentration measured by ASV ([Zn]ASV) was compared with that measured by inductively coupled plasma mass spectrometry (ICP-MS) after ultracentrifugation ([Zn]ICP-MS), for four types of ZnO NPs with different coatings and primary particle diameters. For small ZnO NPs (4-5 nm), [Zn]ASV was 20% higher than [Zn]ICP-MS, suggesting that these small NPs contributed to the voltammetric measurement. For larger ZnO NPs (approximately 20 nm), [Zn]ASV was (79 ± 19)% of [Zn]ICP-MS, despite the high concentrations of ZnO NPs in suspension. Using ASV, the dissolution of ZnO NPs was studied, with or without Suwannee River Fulvic Acid (SRFA). Although SRFA diminished the ASV stripping current, dissolution of 20 nm ZnO NPs was significantly promoted at high fulvic acid to ZnO NP ratios. The ASV method described in this paper provides a useful tool for studying the dissolution kinetics of ZnO NPs in complex environmental matrices.

  17. ITCS Test Strip Development and Certification

    Science.gov (United States)

    Carrigan, Caitlin; Adam, Niklas; Pickering, Karen; Gazda, Daniel; Piowaty, Hailey

    2011-01-01

    Internal coolant loops used for International Space Station thermal control must be periodically monitored for system health, including pH, biocide levels and any indication of ammonia. The presence of ammonia, possible via a microleak in the interface between the internal and external thermal control systems, could be a danger to the crew. The Internal Thermal Control System (ITCS) Sampling Kit uses test strips as a colorimetric indicator of pH and concentrations of biocide and free ammonia. This paper describes the challenges in designing an ammonia colorimetric indicator in a variable pH environment, as well as lessons learned, ultimately resulting in a robust test strip to indicate a hazardous ammonia leak.

  18. The Extent of the Stop Coannihilation Strip

    CERN Document Server

    Ellis, John; Zheng, Jiaming

    2014-01-01

    Many supersymmetric models such as the CMSSM feature a strip in parameter space where the lightest neutralino \\chi is identified as the lightest supersymmetric particle (LSP), the lighter stop squark \\tilde t_1 is the next-to-lightest supersymmetric particle (NLSP), and the relic \\chi cold dark matter density is brought into the range allowed by astrophysics and cosmology by coannihilation with the lighter stop squark \\tilde t_1 NLSP. We calculate the stop coannihilation strip in the CMSSM, incorporating Sommerfeld enhancement effects, and explore the relevant phenomenological constraints and phenomenological signatures. In particular, we show that the \\tilde t_1 may weigh several TeV, and its lifetime may be in the nanosecond range, features that are more general than the specific CMSSM scenarios that we study in this paper.

  19. Operation of a Batch Stripping Distillation Column

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A stripping batch distillation column is preferred when the amount of the light component in the feed is small and the products are to be recovered at high purity. The operation modes of a batch stripping are believed to be the same as those of a rectifier. However, the control system of a stripper is different. In this paper, we explore three different control methods with Hysys (Hyprotech Ltd. 1997) for a batch stripper. The main difference is the control scheme for reboiler liquid level: (a) controlled by reflux flow; (b) controlled by reboiler heat duty; (c) controlled by bottom product flow. The main characteristics of operating a batch stripper with different control scheme are presented in this paper. Guidelines are provided for the startup of a batch stripper, the effects of somecontrol tuning parameters on the column performance are discussed.

  20. L-strip proximity fed ga

    Directory of Open Access Journals (Sweden)

    Ashish Singh

    2014-03-01

    Full Text Available In this article, the analysis of dualband L-strip fed compact semi-circular disk microstrip patch antenna has been presented using circuit theory concept. The antenna parameters such as return loss, VSWR and radiation pattern are calculated. The effect of geometric dimensions of the proposed antenna such as length of vertical and horizontal portion of L-strip is investigated. It is found that antenna resonate at two distinct modes i.e. 1.3 GHz and 6.13 GHz for lower and upper resonance frequencies respectively. The bandwidth of the proposed antenna at lower resonance frequency is 6.61% (simulated and 10.64% (theoretical whereas at upper resonance frequency, it is 6.02% (simulated and 9.06 % (theoretical. The theoretical results are compared with IE3D simulation results as well as experimental results and they are in close agreement.

  1. Coiling Temperature Control in Hot Strip Mill

    Science.gov (United States)

    Imanari, Hiroyuki; Fujiyama, Hiroaki

    Coiling temperature is one of the most significant factors in products of hot strip mill to determine material properties such as strength, toughness of steel, so it is very important to achieve accurate coiling temperature control (CTC). Usually there are a few pyrometers on the run out table in hot strip mill, therefore temperature model and its adapting system have large influences on the accuracy of CTC. Also unscheduled change of rolling speed has a bad effect to keep coiling temperature as its target. Newly developed CTC system is able to get very accurate coiling temperature against uncertain factors and disturbances by adopting easily identified temperature model, learning method and dynamic set up function. The features of the CTC system are discussed with actual data, and the effectiveness of the system is shown by actual control results.

  2. Frequency dependent magnetization of superconductor strip

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Kailash Prasad [Landcare Research, Palmerston North (New Zealand); Raj, Ashish [Computer Science in Radiology, Weill Medical College, Cornell University, NY (United States); Brandt, Ernst Helmut [Max-Planck-Institut fuer Metallforschung, POB 800665, D-70506 Stuttgart (Germany); Sastry, Pamidi V P S S, E-mail: thakurk@landcareresearch.co.nz, E-mail: asr2004@med.cornell.edu, E-mail: ehb@mf.mpg.de, E-mail: pamidi@caps.fsu.edu [Center for Advanced Power Systems, Florida State University, Tallahassee, FL 32310 (United States)

    2011-04-15

    The frequency dependence of magnetic ac loss of thin superconductor strip subjected to an ac magnetic field perpendicular to the surface of the strip is investigated by incorporating a flux creep model into the critical state model of Brandt and Indenbom. It is found that the reduced ac loss exhibits a maximum value at a frequency f{sub m}, which is a rapidly varying function of the applied ac magnetic field. At low magnetic field, f{sub m} becomes zero, and ac loss decreases with frequency as a power law ({approx}f{sup -2/n}). Whereas at high magnetic field f{sub m} becomes infinite and ac loss increases with frequency, still following the power law ({approx}f{sup 1/n}). The analytical results are substantiated with experimental data and the results of a 2D finite element simulation.

  3. PRESUPPOSITIONS AND IMPLICATURES IN COMIC STRIPS

    Directory of Open Access Journals (Sweden)

    Ienneke Indra Dewi

    2008-05-01

    Full Text Available Article aimed to find out the role of presuppositions, implicatures, as well as to see the maxims violated or flouted in the comic strips i.e. to whether there is a miscommunication among the characters in the comic strips. Data were taken from the three comics, those are Peanuts, Andy, and Tintin, and were analysed based on the pattern that the sender made a presupposition before transferring information and the receiver would try to get the implied message. The results show that presuppositions and implicatures are much influenced by the background knowledge. The more the speaker and hearer know each other’s background, the better presuppositions and implicatures they make and finally, the less miscommunication occurred.

  4. Stage- vs. Channel-strip Metaphor

    DEFF Research Database (Denmark)

    Gelineck, Steven; Korsgaard, Dannie Michael; Büchert, Morten

    2015-01-01

    This study compares the stage metaphor and the channel strip metaphor in terms of performance. Traditionally, music mixing consoles employ a channels strip control metaphor for adjusting parameters such as volume and panning of each track. An alternative control metaphor, the so-called stage...... metaphor lets the user adjust volume and panning by positioning tracks relative to a virtual listening position. In this study test participants are given the task to adjust volume and panning of one channel (in mixes consisting of three channels) in order to replicate a series of simple pre-rendered mixes....... They do this using (1) a small physical mixing controller and (2) using an iPad app, which implements a simple stage metaphor interface. We measure how accurately they are able to replicate mixes in terms of volume and panning and how fast they are at doing so. Results reveal that performance...

  5. Mechanics of Thin Strip Steering in Hot Rolling

    Science.gov (United States)

    Jiang, Zhengyi; Tieu, Kiet A.

    2004-06-01

    The hot rolling of thin strip can result in several problems in hot rolling, for instance, the control of strip steering, strip shape and flatness and surface roughness etc. Therefore, the hot rolling of thin strip brings out a requirement of innovative technologies such as the extended control of shape and flatness, steering control and reduction of load by roll gap lubrication. In this paper, the authors focus on the analysis of thin strip snaking movement, as well as solve the related problems such as the shape and flatness due to a larger reduction applied when the strip is thinner. A finite element method was used to simulate this nonsymmetricity rolling considering the non-uniform reduction along the strip width. The calculated spread is compared with the measured values obtained from the rolling mill in laboratory and the friction effect is also discussed.

  6. Antenna with distributed strip and integrated electronic components

    Science.gov (United States)

    Rodenbeck, Christopher T.; Payne, Jason A.; Ottesen, Cory W.

    2008-08-05

    An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element can be in proximity to a ground conductor and/or arranged as a dipole. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. An antenna can comprise a distributed strip patterned on a printed wiring board, integrated with electronic components mounted on top of or below the distributed strip, and substantially within the extents of the distributed strip. Mounting of electronic components on top of or below the distributed strip has little effect on the performance of the antenna, and allows for realizing the combination of the antenna and integrated components in a compact form. An embodiment of the invention comprises an antenna including a distributed strip, integrated with a battery mounted on the distributed strip.

  7. Determination of Xanthine in the Presence of Hypoxanthine by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

    Science.gov (United States)

    Farias, Percio Augusto Mardini; Castro, Arnaldo Aguiar

    2014-01-01

    A stripping method for the determination of xanthine in the presence of hypoxanthine at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10−3 mol L−1 NaOH solution as supporting electrolyte, an accumulation potential of 0.00 V for xanthine and −0.50 V for hypoxanthine–copper, and a linear scan rate of 200 mV second−1. The response of xanthine is linear over the concentration ranges of 20–140 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 36 ppt (2.3 × 10−10 mol L−1). Adequate conditions for measuring the xanthine in the presence of hypoxanthine, copper and other metals, uric acid, and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of xanthine associated with hypoxanthine, uric acid, nitrogenated bases, ATP, and ssDNA. PMID:24940040

  8. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  9. Development of Silicon Multi-strip Detector

    Institute of Scientific and Technical Information of China (English)

    TanJilian; JinGenming; WangHongwei; YuanXiaohua; DuanLiming; LiSonglin; LuZiwei; XuHushan; NingBaojun; TianDayu; WangWei; ZhangLu

    2003-01-01

    Position sensitive detector is very important for nuclear physics experiment. There several techniques can be used to fabricate position sensitive detector, for example, Si-surface barrier method, diffusion method, ion implantation and planar process etc. Among all the techniques mentioned above planar process is the best one. We have developed batch of position sensitive detector -- silicon multi-strip detector by using planar process.

  10. A Spinning Particle in a Mobius Strip

    CERN Document Server

    Nieto, J A

    2011-01-01

    We develop the classical and quantum theory of a spinning particle moving in a Mobius strip. We first propose a Lagrangian for such a system and then we proceed to quantize the system via the constraint Hamiltonian system formalism. Our results may be of particular interest in several physical scenarios, including solid state physics and optics. In fact, the present work may shed some new light on the recent discoveries on condensed matter concerning topological insulators.

  11. Multitwist optical Möbius strips.

    Science.gov (United States)

    Freund, Isaac

    2010-01-15

    Circularly polarized Gauss-Laguerre GL00 and GL01 laser beams that cross at their waists at a small angle are shown to generate a quasi-paraxial field that contains a line of circular polarization, a C line, surrounded by polarization ellipses whose major and minor axes generate multitwist Möbius strips with twist numbers that increase with the distance from the C point.

  12. Hot Strip Laminar Cooling Control Model

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; WANG Guo-dong; LIU Xiang-hua

    2004-01-01

    The control model of laminar cooling system for hot strip, including air-cooling model, water-cooling model, temperature distribution model along thickness direction, feedforward control model, feedback control model and self-learning model, was introduced. PID arithmetic and Smith predictor controller were applied to feedback control. The sample of model parameter classification was given. The calculation process was shown by flow chart. The model has been proved to be simple, effective and of high precision.

  13. Mastering Interproximal Stripping: With Innovations in Slenderization

    OpenAIRE

    Sharma, Narendra Shriram; Shrivastav, Sunita S; Hazarey, Pushpa V

    2012-01-01

    ABSTRACT Crowding and irregularity remain a consistent problem for children. Management of space problems continues to play an important role in a dental practice. It also represents an area of major interaction between the primary provider and the specialists. Proximal stripping is routinely carried out to avoid extraction in borderline cases where space discrepancy is less and in cases where there is a discrepancy between the mesio- distal width of maxillary and mandibular teeth to satisfy ...

  14. Wakes of ram pressure stripped disc galaxies

    CERN Document Server

    Roediger, E; Hoeft, M

    2006-01-01

    Spiral galaxies that move through the intracluster medium lose a substantial amount of their gas discs due to ram pressure stripping. The recent observations of NGC 4388 by Oosterloo & van Gorkom 2005 reveal a tail of stripped gas of ~ 100 kpc behind the source galaxy. We present first 3D hydrodynamical simulations of the evolution of such ram pressure stripped tails. We find that if the ICM wind does not vary significantly over a period of a few 100 Myr, subsonic galaxies produce a tail with regular features similar to a von-Karman vortex street. In this case, the tail widens systematically by about 45 kpc per 100 kpc distance behind the source galaxy. The widening rate is independent of the galaxy's inclination for a large range of inclinations. For supersonic galaxies, the tail is more irregular than for subsonic ones. The tail observed for NGC 4388 is narrower than the tails in our simulations. Reasons for this difference may be additional physical processes such as heat conduction or viscosity. In ad...

  15. Sustainable Water and Energy in Gaza Strip

    Science.gov (United States)

    Hamdan, L.; Zarei, M.; Chianelli, R.; Gardner, E.

    2007-12-01

    Shortage of fresh water is a common problem in different areas of the world including the Middle East. Desalination of seawater and brackish water is the cheapest way to obtain fresh water in many regions. This research focuses on the situation in Gaza Strip where there is a severe shortage in the energy and water supply. The depletion of fresh water supplies and lack of wastewater treatments result in environmental problems. A solar powered cogeneration plant producing water and energy is proposed to be a suitable solution for Gaza Strip. Solar energy, using Concentrating Solar thermal Power (CSP) technologies, is used to produce electricity by a steam cycle power plant. Then the steam is directed to a desalination plant where it is used to heat the seawater to obtain freshwater. The main objective of this research is to outline a solution for the water problems in Gaza Strip, which includes a cogeneration (power and water) solar powered plant. The research includes four specific objectives: 1- an environmental and economic comparison between solar and fossil fuel energies; 2- technical details for the cogeneration plant; 3- cost and funding, 4- the benefits.

  16. High-Rate Capable Floating Strip Micromegas

    CERN Document Server

    Bortfeldt, Jonathan; Biebel, Otmar; Danger, Helge; Flierl, Bernhard; Hertenberger, Ralf; Lösel, Philipp; Moll, Samuel; Parodi, Katia; Rinaldi, Ilaria; Ruschke, Alexander; Zibell, André

    2015-01-01

    We report on the optimization of discharge insensitive floating strip Micromegas (MICRO-MEsh GASeous) detectors, fit for use in high-energy muon spectrometers. The suitability of these detectors for particle tracking is shown in high-background environments and at very high particle fluxes up to 60MHz/cm$^2$. Measurement and simulation of the microscopic discharge behavior have demonstrated the excellent discharge tolerance. A floating strip Micromegas with an active area of 48cm$\\times$50cm with 1920 copper anode strips exhibits in 120GeV pion beams a spatial resolution of 50$\\mu$m at detection efficiencies above 95%. Pulse height, spatial resolution and detection efficiency are homogeneous over the detector. Reconstruction of particle track inclination in a single detector plane is discussed, optimum angular resolutions below $5^\\circ$ are observed. Systematic deviations of this $\\mu$TPC-method are fully understood. The reconstruction capabilities for minimum ionizing muons are investigated in a 6.4cm$\\time...

  17. 2013 Estorm - Invited Paper - Cathode Materials Review

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Claus [ORNL; Mohanty, Debasish [ORNL; Li, Jianlin [ORNL; Wood III, David L [ORNL

    2014-01-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403 431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783 789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  18. Improved cathode materials for microbial electrosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T; Nie, HR; Bain, TS; Lu, HY; Cui, MM; Snoeyenbos-West, OL; Franks, AE; Nevin, KP; Russell, TP; Lovley, DR

    2013-01-01

    Microbial electrosynthesis is a promising strategy for the microbial conversion of carbon dioxide to transportation fuels and other organic commodities, but optimization of this process is required for commercialization. Cathodes which enhance electrode-microbe electron transfer might improve rates of product formation. To evaluate this possibility, biofilms of Sporomusa ovata, which are effective in acetate electrosynthesis, were grown on a range of cathode materials and acetate production was monitored over time. Modifications of carbon cloth that resulted in a positive-charge enhanced microbial electrosynthesis. Functionalization with chitosan or cyanuric chloride increased acetate production rates 6-7 fold and modification with 3-aminopropyltriethoxysilane gave rates 3-fold higher than untreated controls. A 3-fold increase in electrosynthesis over untreated carbon cloth cathodes was also achieved with polyaniline cathodes. However, not all strategies to provide positively charged surfaces were successful, as treatment of carbon cloth with melamine or ammonia gas did not stimulate acetate electrosynthesis. Treating carbon cloth with metal, in particular gold, palladium, or nickel nanoparticles, also promoted electrosynthesis, yielding electrosynthesis rates that were 6-,4.7- or 4.5-fold faster than the untreated control, respectively. Cathodes comprised of cotton or polyester fabric treated with carbon nanotubes yielded cathodes that supported acetate electrosynthesis rates that were similar to 3-fold higher than carbon cloth controls. Recovery of electrons consumed in acetate was similar to 80% for all materials. The results demonstrate that one approach to increase rates of carbon dioxide reduction in microbial electrosynthesis is to modify cathode surfaces to improve microbe-electrode interactions.

  19. Multiple cathodic reaction mechanisms in seawater cathodic biofilms operating in sediment microbial fuel cells.

    Science.gov (United States)

    Babauta, Jerome T; Hsu, Lewis; Atci, Erhan; Kagan, Jeff; Chadwick, Bart; Beyenal, Haluk

    2014-10-01

    In this study, multiple reaction mechanisms in cathodes of sediment microbial fuel cells (SMFCs) were characterized by using cyclic voltammetry and microelectrode measurements of dissolved oxygen and pH. The cathodes were acclimated in SMFCs with sediment and seawater from San Diego Bay. Two limiting current regions were observed with onset potentials of approximately +400 mVAg/AgCl for limiting current I and -120 mVAg/AgCl for limiting current II. The appearance of two catalytic waves suggests that multiple cathodic reaction mechanisms influence cathodic performance. Microscale oxygen concentration measurements showed a zero surface concentration at the electrode surface for limiting current II but not for limiting current I, which allowed us to distinguish limiting current II as the conventional oxygen reduction reaction and limiting current I as a currently unidentified cathodic reaction mechanism. Microscale pH measurements further confirmed these results.

  20. LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes.

    Science.gov (United States)

    Economou, Anastasios; Voulgaropoulos, Anastasios

    2003-01-01

    The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV.

  1. Preparation of nanocomposite thoriated tungsten cathode by swaging technique

    Institute of Scientific and Technical Information of China (English)

    王发展; 诸葛飞; 张晖; 丁秉钧

    2002-01-01

    By using the high energy ball milling method,the nanosized ThO2 powders were obtained.Through mixing powders,sintering and hot swaging processing,a nanocomposite thoriated tungsten cathode was fabricated.The relative density of the nanocomposite material is near 100%.The microstructure of nanocomposite cathode is quite different from that of conventional thoriated tungsten cathode.Most of thoria particles are less than 100 nm in diameter,and distribute on the boundaries of tungsten grains.The nanocomposite cathode shows a much lower arc starting field than that of conventional cathode,which will improve the performance of the cathode significantly.

  2. The influence of cathode excavation of cathodic arc evaporator on thickness uniformity and erosion products angle distribution

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2014-01-01

    Full Text Available Cathodic arc evaporators are used for coating with functional films. Prolonged or buttend evaporators may be used for this purposes. In butt-end evaporator the cathode spots move continuously on the cathode work surface and evaporate cathode material. High depth excavation profile forms on the cathode work surface while the thick coating precipitation (tens or hundreds of microns. The cathode excavation profile is shaped like a “cup” with high walls for electrostatic discharge stabilization systems with axial magnetic fields. Cathode spots move on the bottom of the “cup”. It is very likely that high “cup” walls are formed as a result of lasting work time influence on the uniformity of precipitated films.In the present work the influence of excavation profile walls height on the uniformity of precipitated coating was carried out. The high profile walls are formed due to lasting work of DC vacuum arc evaporator. The cathode material used for tests was 3003 aluminum alloy. The extended substrate was placed parallel to the cathode work surface. Thickness distribution along the substrate length with the new cathode was obtained after 6 hours and after 12 hours of continuous operation.The thickness distribution of precipitated coating showed that the cathode excavation has an influence on the angular distribution of the matter escaping the cathode. It can be clearly seen from the normalized dependence coating thickness vs the distance from the substrate center. Also the angular distribution of the matter flow from the cathode depending on the cathode working time was obtained. It was shown that matter flow from the cathode differs from the LambertKnudsen law. The more the cathode excavation the more this difference.So, cathode excavation profile has an influence on the uniformity of precipitated coating and it is necessary to take in account the cathode excavation profile while coating the thick films.

  3. Parallel Operation of Microhollow Cathode Discharges

    Science.gov (United States)

    Stark, Robert H.; Shi, Wenhui; Schoenbach, Karl H.

    1998-10-01

    The dc current-voltage characteristics of microhollow cathode discharges has, in certain ranges of the discharge current, a positive slope [1]. In these current ranges it should be possible to operate multiple discharges in parallel without individual ballast, and be used as flat panel excimer lamps [2] or large area plasma cathodes. In order to verify this hypothesis we have studied the parallel operation of two microhollow cathode discharges of 100 micrometer hole diameter in argon at pressures from 100 Torr to 800 Torr. Stable dc operation of the two discharges, without individual ballast, was obtained if the voltage-current characteristics of the individual discharges had a positive slope greater than 10 V/mA over a voltage range of more than 5 to obtain parallel operation over the entire current range of the microhollow cathode discharges, which includes regions of negative differential conductivity, we have replaced the metal anode by a semi-insulating semiconductor, which serves as distributed resistive ballast. With this method, we were able to ignite and sustain an array of dc microhollow cathode discharges over a wide range of pressure and discharge current. [1] K.H.Schoenbach et al. Appl. Phys. Lett. 68, 13 (1996). [2] A.El-Habachi and K.H.Schoenbach, APL. 72, 1 (1998). This work was funded by the Department of Energy, Advanced Energy Division, and by the Air Force Office of Scientific Research (AFOSR) in cooperation with the DDR&E Air Plasma Ramparts MURI Program.

  4. Effect of boron on hot strips of low carbon steel produced by compact strip production

    Institute of Scientific and Technical Information of China (English)

    Hao Yu; Yonglin Kang

    2008-01-01

    The effect of boron on hot strips of low carbon steel produced by compact strip production (CSP) to reduce the strength to a certain degree was investigated, which is quite different from that of high-strength low alloy steel. The mechanical properties and microstructural evolution of the hot strip were studied using optical microscopy and tensile tests. By means of an electrolytic disso- lution technique and Thermo-Cal calculation, the precipitates containing boron were analyzed and detected. From the electron back- scattered diffraction analysis, it can be deciphered whether the microstructure has recrystallized or not. Furthermore, the effect of boron segregation on the recrystallization or non-recrystallization conditions can be distinguished. The segregation behavior of boron was investigated in boron-containing steel. The nonequilibrium segregation of boron during processing was discussed on the basis of the forming complexes with vacancies that migrate to the boundaries prior to annihilation, which was confirmed by the subsequent cold rolling with annealing experiments.

  5. Differential Pulse Anodic Stripping Voltammetry for Mercury Determination

    OpenAIRE

    2015-01-01

    In the present work voltammetric investigations have been performed on HgCl2 aqueous solutions prepared from a Cz 9024 reagent. Carbon paste electrode (CPE), eriochrome black T modified carbon paste electrode (MCPE/EBT) and KCl 1M as background electrolyte, were involved within the experimental procedures. Cyclic voltammetry (CV) has been performed in order to compare the behaviour of the two electrodes in both K3[Fe(CN)6] and mercury calibration aqueous solution. Differential pulse anodic st...

  6. Controlled functionalisation of single-walled carbon nanotube network electrodes for the enhanced voltammetric detection of dopamine.

    Science.gov (United States)

    E, Sharel P; Miller, Thomas S; Macpherson, Julie V; Unwin, Patrick R

    2015-10-21

    Voltammetric studies of dopamine (DA) oxidation on pristine and acid-treated single-walled carbon nanotube (SWNT) network electrodes were undertaken in order to investigate both the effect of network density and acid treatment times on the voltammetric characteristics for DA oxidation and the susceptibility of the electrodes to fouling. Through careful control of catalysed chemical vapour deposition growth parameters, multiply interconnected and randomly oriented SWNT networks of two significantly different densities were grown (high density, HD, coverage ≫10 μm length of SWNT per μm(-2) and low density, LD, coverage = 5 (±1) μmSWNTμm(-2)). Acid treatment was performed to provide materials with different electrochemical properties and SWNT coverage, as determined by field emission-scanning electron microscopy, atomic force microscopy and micro-Raman spectroscopy. A high concentration of DA (100 μM) was deliberately employed to accelerate the fouling phenomenon associated with DA oxidation in order to evaluate the lifetime of the electrodes. HD pristine SWNT networks were found to promote more facile electron transfer (ET) and were less susceptible to blocking, compared to LD pristine SWNT networks. Acid treatment resulted in both a further enhancement of the ET rate and a reduction in susceptibility towards electrode fouling. However, lengthy acid treatment detrimentally affected ET, due to a decrease in network density and significant damage to the SWNT network structure. These studies highlight the subtle interplay between SWNT coverage and degree of acid functionalisation when seeking to achieve the optimal SWNT electrode for the voltammetric detection of DA.

  7. Voltammetric Determination of Prochlorperazine and Ethopropazine Using a Gold Electrode Modified with Decanethiol SAM

    Directory of Open Access Journals (Sweden)

    Baizhao Zeng

    2003-12-01

    Full Text Available The voltammetric behavior of prochlorperazine and ethopropazine at a decanethiol (DEC self-assembled monolayer (SAM modified gold electrode (DEC/Au has been studied. It was observed that prochlorperazine exhibited an anodic peak at about 0.60 V (vs SCE, while ethopropazine exhibited two anodic peaks at about 0.49 V and 0.58 V on DEC/Au in pH 10 sodium carbonate buffer. This was due to their different electrochemical oxidation mechanisms. In this case, the oxidation of prochlorperazine and ethopropazine included one 2e step and two 1e steps, respectively. In the presence of some reductants such as ascorbic acid, the oxidation products of them can catalyze the oxidation of the reductants and thus make the peaks grow. In addition, it was found that the SAM structure became not so compact when prochlorperazine and ethopropazine were present, resulting from their permeating in the SAM. Various conditions were optimized for their determination. Under the selected conditions (i.e. 0.080 M pH 10 sodium carbonate buffer; scan rate: 100 mV/s; accumulation potential: –0.4 V or 0 V; accumulation time: 60 s, the peak currents were linear to prochlorperazine concentration in the ranges of 0.1~2.0 μM and 5.0~50 μM, and linear with ethopropazine in the ranges of 10 nM~0.1 μM and 0.5~20 μM. The RSD was 4.28% for 8 successive measurements of 1.0 μM prochlorperazine. The influence of some coexistents was examined.

  8. Indirect differential pulse voltammetric determination of aluminum by a pyrocatechol violet-modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Chen, G.; Bi, S.; Dai, L.; Cao, M.; Chen, Y. Wang, X. [Nanjing Univ. (China)

    1999-03-01

    Aluminum is one of the abundant elements in the earth`s crust. It has been considered to be a causative agent for various neurological disorders such as Alzheimer Senile, presenile dementia and amyotrophic lateral sclerosis. It is also very harmful to plants and aquatic organisms. Therefore, the determination of Al is very important. A Pyrocatechol Violet (PCV) modified electrode for the voltammetric determination of aluminum is reported. The modified electrode is simply prepared by dip-coating a pyrolytic graphite electrode in a NaAc-HAc buffer solution of PCV. Optimum experimental conditions for aluminum determination include a 0.2 mol/L NaAc-HAc buffer solution of pH 4.8, a PCV concentration of 0.02 mol/L used to modify the electrode and the use of differential-pulse mode for measurement. The peak currents of differential pulse voltammograms (DPV) decrease with the addition of Al into the buffer solution while the peak potentials remain the same. The decreasing value of peak current {Delta}i{sub p} is linear with Al concentration in the range of 1{times}10{sup {minus}8} to 1{times}10{sup {minus}7} mol/L and 1{times}10{sup {minus}7} to 1{times}10{sup {minus}6} mol/L. The detection limit is 5{times}10{sup {minus}9} mol/L and the relative standard deviation for 4{times}10{sup {minus}8} mol/L Al is 2.9% (n=8). The stability of this electrode is satisfactory. No serious interference is found. This method has been applied to determine Al in drinking water samples.

  9. Simultaneous voltammetric determination of tramadol and acetaminophen using carbon nanoparticles modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbani-Bidkorbeh, Fatemeh [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Shahrokhian, Saeed, E-mail: shahrokhian@sharif.ed [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Institute for Nanoscience and Technology, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mohammadi, Ali [Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Dinarvand, Rassoul [Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran (Iran, Islamic Republic of)

    2010-03-01

    A sensitive and selective electrochemical sensor was fabricated via the drop-casting of carbon nanoparticles (CNPs) suspension onto a glassy carbon electrode (GCE). The application of this sensor was investigated in simultaneous determination of acetaminophen (ACE) and tramadol (TRA) drugs in pharmaceutical dosage form and ACE determination in human plasma. In order to study the electrochemical behaviors of the drugs, cyclic and differential pulse voltammetric studies of ACE and TRA were carried out at the surfaces of the modified GCE (MGCE) and the bare GCE. The dependence of peak currents and potentials on pH, concentration and the potential scan rate were investigated for these compounds at the surface of MGCE. Atomic force microscopy (AFM) was used for the characterization of the film modifier and its morphology on the surface of GCE. The results of the electrochemical investigations showed that CNPs, via a thin layer model based on the diffusion within a porous layer, enhanced the electroactive surface area and caused a remarkable increase in the peak currents. The thin layer of the modifier showed a catalytic effect and accelerated the rate of the electron transfer process. Application of the MGCE resulted in a sensitivity enhancement and a considerable decrease in the anodic overpotential, leading to negative shifts in peak potentials. An optimum electrochemical response was obtained for the sensor in the buffered solution of pH 7.0 and using 2 muL CNPs suspension cast on the surface of GCE. Using differential pulse voltammetry, the prepared sensor showed good sensitivity and selectivity for the determination of ACE and TRA in wide linear ranges of 0.1-100 and 10-1000 muM, respectively. The resulted detection limits for ACE and TRA was 0.05 and 1 muM, respectively. The CNPs modified GCE was successfully applied for ACE and TRA determinations in pharmaceutical dosage forms and also for the determination of ACE in human plasma.

  10. Sheet Plasma Produced by Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    张龙; 张厚先; 杨宣宗; 冯春华; 乔宾; 王龙

    2003-01-01

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field.The plasma is about 40cm in length,4 cm in width and 1cm in thickness.The electron density is about 108cm-3.The hollow cathode is made to be shallow with a large opening,which is different from the ordinary deep hollow cathode.A Langmuir probe is used to detect the plasma.The electron density and the spatial distribution of the plasma change when voltage,pressure and the magnetic field vary.A peak and a data fluctuation at about 200 G-300 G are observed in the variation of electron density(or thickness of the sheet plasma)with the magnetic field.Our work will be helpful in characterizing the sheet plasma and will make the production of dense sheet plasma more controllable.

  11. Filtered cathodic arc deposition apparatus and method

    Science.gov (United States)

    Krauss, Alan R.

    1999-01-01

    A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.

  12. Synchrotron Investigations of SOFC Cathode Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Idzerda, Yves

    2013-09-30

    The atomic variations occurring in cathode/electrolyte interface regions of La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3-δ} (LSCF) cathodes and other SOFC related materials have been investigated and characterized using soft X-ray Absorption Spectroscopy (XAS) and diffuse soft X-ray Resonant Scattering (XRS). X-ray Absorption Spectroscopy in the soft X-ray region (soft XAS) is shown to be a sensitive technique to quantify the disruption that occurs and can be used to suggest a concrete mechanism for the degradation. For LSC, LSF, and LSCF films, a significant degradation mechanism is shown to be Sr out-diffusion. By using the XAS spectra of hexavalent Cr in SrCrO4 and trivalent Cr in Cr2O3, the driving factor for Sr segregation was identified to be the oxygen vacancy concentration at the anode and cathode side of of symmetric LSCF/GDC/LSCF heterostructures. This is direct evidence of vacancy induced cation diffusion and is shown to be a significant indicator of cathode/electrolyte interfacial degradation. X-ray absorption spectroscopy is used to identify the occupation of the A-sites and B-sites for LSC, LSF, and LSCF cathodes doped with other transition metals, including doping induced migration of Sr to the anti-site for Sr, a significant cathode degradation indicator. By using spatially resolved valence mapping of Co, a complete picture of the surface electrochemistry can be determined. This is especially important in identifying degradation phenomena where the degradation is spatially localized to the extremities of the electrochemistry and not the average. For samples that have electrochemical parameters that are measured to be spatially uniform, the Co valence modifications were correlated to the effects of current density, overpotential, and humidity.

  13. Klystron Amplifier Utilizing Scandate Cathode and Electrostatic Focusing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to build an electrostatically focused klystron that exploits recent breakthroughs in scandate cathode technology. We have built cathodes with greater than...

  14. Nano-Particle Scandate Cathode for Space Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an improved cathode based on our novel theory of the role of scandium oxide in enhancing emission in tungsten impregnate cathodes. Recent results have...

  15. Long Life Cold Cathodes for Hall effect Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An electron source incorporating long life, high current density cold cathodes inside a microchannel plate for use with ion thrusters is proposed. Cathode lifetime...

  16. Review on MIEC Cathode Materials for Solid Oxide Fuel Cells

    Science.gov (United States)

    Burnwal, Suman Kumar; Bharadwaj, S.; Kistaiah, P.

    2016-11-01

    The cathode is one of the most important components of solid oxide fuel cells (SOFCs). The reduction of oxygen at the cathode (traditional cathodes like LSM, LSGM, etc.) is the slow step in the cell reaction at intermediate temperature (600-800∘C) which is one of the key obstacles to the development of SOFCs. The mixed ionic and electronic conducting cathode (MIEC) like LSCF, BSCF, etc., has recently been proposed as a promising cathode material for SOFC due to the improvement of the kinetic of the cathode reaction. The MIEC materials provide not only the electrons for the reduction of oxygen, but also the ionic conduction required to ensure the transport of the formed oxygen ions and thereby improves the overall electrochemical performance of SOFC system. The characteristics of MIEC cathode materials and its comparison with other traditional cathode materials is studied and presented in the paper.

  17. VOLTAMMETRIC CHARACTERIZATION OF THE BEHAVIOR OF BIOLOGICALLY ACTIVE COMPOUND ENOXIL IN VARIOUS MEDIA

    Directory of Open Access Journals (Sweden)

    Gheorghe Nemţoi

    2011-06-01

    Full Text Available This paper presents the results of scientific research related to the electrochemical behavior of the complex preparation Enoxil. It was established that the oxidation-reduction process of Enoxil is quasireversible. The reactivity of Enoxil obtained from alcohol soluble enotannins is more pronounced, compared to that obtained from standard enotannins. The dependence of cathodic current intensity on Enoxil concentration is linear. This can be used to establish Enoxil concentration in solution. Cyclic voltamograms were used to establish reduction and oxidation potential and the formal redox potential on platinum electrode in sodium perchlorate aqueous environment. These features can be used for identification and determination of Enoxil in pharmaceuticals.

  18. Hollow-Cathode Source Generates Plasma

    Science.gov (United States)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  19. DARHT 2 kA Cathode Development

    Energy Technology Data Exchange (ETDEWEB)

    Henestroza, E.; Houck, T.; Kwan, J.W.; Leitner, M.; Miram, G.; Prichard, B.; Roy, P.K.; Waldron, W.; Westenskow, G.; Yu, S.; Bieniosek, F.M.

    2009-03-09

    In the campaign to achieve 2 kA of electron beam current, we have made several changes to the DARHT-II injector during 2006-2007. These changes resulted in a significant increase in the beam current, achieving the 2 kA milestone. Until recently (before 2007), the maximum beam current that was produced from the 6.5-inch diameter (612M) cathode was about 1300 A when the cathode was operating at a maximum temperature of 1140 C. At this temperature level, the heat loss was dominated by radiation which is proportional to temperature to the fourth power. The maximum operating temperature was limited by the damage threshold of the potted filament and the capacity of the filament heater power supply, as well as the shortening of the cathode life time. There were also signs of overheating at other components in the cathode assembly. Thus it was clear that our approach to increase beam current could not be simply trying to run at a higher temperature and the preferred way was to operate with a cathode that has a lower work function. The dispenser cathode initially used was the type 612M made by SpectraMat. According to the manufacturer's bulletin, this cathode should be able to produce more than 10 A/cm{sup 2} of current density (corresponding to 2 kA of total beam current) at our operating conditions. Instead the measured emission (space charge limited) was 6 A/cm{sup 2}. The result was similar even after we had revised the activation and handling procedures to adhere more closely to the recommend steps (taking longer time and nonstop to do the out-gassing). Vacuum was a major concern in considering the cathode's performance. Although the vacuum gauges at the injector vessel indicated 10{sup -8} Torr, the actual vacuum condition near the cathode in the central region of the vessel, where there might be significant out-gassing from the heater region, was never determined. Poor vacuum at the surface of the cathode degraded the emission (by raising the work function

  20. A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

    Science.gov (United States)

    Gütz, Christoph; Selt, Maximilian; Bänziger, Markus; Bucher, Christoph; Römelt, Christina; Hecken, Nadine; Gallou, Fabrice; Galvão, Tomás R; Waldvogel, Siegfried R

    2015-09-28

    Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives.

  1. Low-current hollow-cathode discharge in a trigger unit of a cold cathode thyratron

    OpenAIRE

    Landl, N. V.; Korolev, Yuriy Dmitrievich; Frants, O. B.; Geyman, V. G.; Bolotov, A. V.

    2015-01-01

    The paper deals with the investigations of the effect of cathode emissivity on the regimes of low-current hollow-cathode glow discharge. It is shown that an increase in the emissivity due to the so-called high-emissivity tablet allows the essential decrease in the discharge initiation voltage and the discharge burning voltage. The model of current sustaining for the hollow-cathode discharge, which takes into account the external emission current has been developed. On basis of the model, the ...

  2. Low-current hollow-cathode discharge in a trigger unit of a cold cathode thyratron

    Science.gov (United States)

    Landl, N. V.; Korolev, Y. D.; Frants, O. B.; Geyman, V. G.; Bolotov, A. V.

    2015-11-01

    The paper deals with the investigations of the effect of cathode emissivity on the regimes of low-current hollow-cathode glow discharge. It is shown that an increase in the emissivity due to the so-called high-emissivity tablet allows the essential decrease in the discharge initiation voltage and the discharge burning voltage. The model of current sustaining for the hollow-cathode discharge, which takes into account the external emission current has been developed. On basis of the model, the current-voltage characteristics of the discharge have been interpreted.

  3. Uranium stripping from tributyl phosphate by urea solutions

    Science.gov (United States)

    Skripchenko, S. Yu.; Titova, S. M.; Smirnov, A. L.; Rychkov, V. N.

    2016-09-01

    The process of uranium stripping from tri-n-butyl phosphate in kerosene by urea solutions was investigated at the volume ratio of the organic and aqueous phases of (1-10) : 1 in the temperature range of 20-60 °C. The stripping of uranium from a loaded organic phase increased with increasing urea content in the solution and with increasing temperature. Maximum recovery of uranium from tributyl phosphate was obtained using a solution that contained 8-12 mol/l of urea. The application of a urea solution for uranium stripping resulted in the strip product solution containing 200-240 g/L of uranium. The process of uranium stripping by dilute nitric acid was also investigated. Results of uranium stripping by the two methods are compared and discussed.

  4. Uniform large-area thermionic cathode for SCALPEL

    Science.gov (United States)

    Katsap, Victor; Sewell, Peter B.; Waskiewicz, Warren K.; Zhu, Wei

    1999-11-01

    An electron beam lithography tool, which employs the SCALPEL technique, requires an extremely uniform beam to illuminate the scattering Mask, with the cathode operating in the temperature limited mode. It has been previously shown that LaB6 cathodes are not stable in this mode of operation. We have explored the possibility of implementing refined Tantalum-based emitters in the SCALPEL source cathode, and have developed large-area flat cathodes featuring suitably high emission uniformity under temperature limited operation.

  5. Simultaneous Voltammetric Determination of Three Herbicides in Food and Water Samples with the Aid of Chemometrics

    Institute of Scientific and Technical Information of China (English)

    NI Yong-nian; WANG Lin; KOKOT Serge

    2009-01-01

    Differential pulse stripping voltammetry method(DPSV) was applied to the determination of three herbicides,ametryn,cyanatryn,and dimethametryn.It was found that their voltammograms overlapped strongly,and it is difficult to determine these compounds individually from their mixtures.With the aid of chemometrics,classical least squares(CLS),principal component regression(PCR) and partial least squares(PLS),voltammogram resolution and quantitative analysis of the synthetic mixtures of the three compounds were successfully performed.The proposed method was also applied to the analysis of some real samples with satisfactory results.

  6. Gas Stripping in the Simulated Pegasus Galaxy

    Science.gov (United States)

    Mercado, Francisco Javier; Samaniego, Alejandro; Wheeler, Coral; Bullock, James

    2017-01-01

    We utilize the hydrodynamic simulation code GIZMO to construct a non-cosmological idealized dwarf galaxy built to match the parameters of the observed Pegasus dwarf galaxy. This simulated galaxy will be used in a series of tests in which we will implement different methods of removing the dwarf’s gas in order to emulate the ram pressure stripping mechanism encountered by dwarf galaxies as they fall into more massive companion galaxies. These scenarios will be analyzed in order to determine the role that the removal of gas plays in rotational vs. dispersion support (Vrot/σ) of our galaxy.

  7. High pressure water jet cutting and stripping

    Science.gov (United States)

    Hoppe, David T.; Babai, Majid K.

    1991-01-01

    High pressure water cutting techniques have a wide range of applications to the American space effort. Hydroblasting techniques are commonly used during the refurbishment of the reusable solid rocket motors. The process can be controlled to strip a thermal protective ablator without incurring any damage to the painted surface underneath by using a variation of possible parameters. Hydroblasting is a technique which is easily automated. Automation removes personnel from the hostile environment of the high pressure water. Computer controlled robots can perform the same task in a fraction of the time that would be required by manual operation.

  8. Intelligent Control on Hot Strip Coiling Temperature

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new intelligent control scheme for hot strip coiling temperature is presented. In this scheme, the prediction model of finishing temperature and the presetting model of main cooling zone are establish based on BP neural network, the feed-forward open-loop control model of main cooling zone is constructed based on T-S fuzzy neural network, a new improved structure of T-S fuzzy neural network is developed, and the feedback close-loop control model of precision cooling zone is obtained based on fuzzy control. The effectiveness of the proposed scheme has been demonstrated by computer simulation with a satisfactory result.

  9. Fermilab silicon strip readout chip for BTev

    Energy Technology Data Exchange (ETDEWEB)

    Yarema, Raymond; Hoff, Jim; Mekkaoui, Abderrezak; Manghisoni, Massimo; Re, Valerio; Angeleri, Valentina; Manfredi, Pier Francesco; Ratti, Lodovico; Speziali, Valeria; /Fermilab /Bergamo U. /INFN, Pavia /Pavia U.

    2005-05-01

    A chip has been developed for reading out the silicon strip detectors in the new BTeV colliding beam experiment at Fermilab. The chip has been designed in a 0.25 {micro}m CMOS technology for high radiation tolerance. Numerous programmable features have been added to the chip, such as setup for operation at different beam crossing intervals. A full size chip has been fabricated and successfully tested. The design philosophy, circuit features, and test results are presented in this paper.

  10. Factors Influencing Bonding Strength of Laminated Bamboo Strips Lumber

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Factors influencing bonding strength of laminated bamboo strips lumber (LBSL) were investigated in this paper. In order to find an optimized technology, this paper investigated how the thickness of bamboo strips, the assembly orientation of bamboo curtain, the type of adhesives, as well as coupling agent treatment of bamboo curtain affected the bonding strength. The following conclusions were drawn: 1)The thinner the thickness of the bamboo strips, the bigger the bonding strength of LBSL; 2) The assembly or...

  11. Time domain non linear strip theory for ship motions

    OpenAIRE

    Fan, Y.T.; Wilson, P. A.

    2004-01-01

    A new implementation of strip theory is proposed based on the strip theory by Salvesen, et al. [1] and early work by Westlake and Wilson [2]. Compared with traditional strip theory, the main difference is that the calculation is carried out in the time domain. This makes it possible to cope with relatively large-amplitude motions and non-constant forward speed problems. At each time step, the exact underwater sections are extracted; the velocity potential is required to satisfyt...

  12. Study on Production of Rubber Sealing Strips with Steel Bones

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Rubber sealing strips with steel bones are used in car manufacturing that produced in large quantities. Cutting processes, such as milling and punching, are needed when the strips are produced. Accuracy, smoothness and flatness of the machined surface have to be guaranteed in the cutting process; moreover, deformation of the steel bone and peeling-off of the rubber must be avoided. Therefore cutting action of rubber/steel strips differs from that of rubber or metal workpiece separately. In this paper, milli...

  13. Beam Test Results for MSGC's with Thick Metal Strips.

    CERN Document Server

    Beaumont, W; Bernier, K; Bouhali, O; Boulogne, I; Daubie, Evelyne; De Troy, J G; Delentdecker, G; Devroede, O; Gregoire,,; Iacopi, F; Udo, Fred; Van Doninck, W K; Van Dyck, C; Van Lancker, L; Van der Velde, C; Verbeure, F; Zhukov, V

    1999-01-01

    Micro Strip Gas Counters with robust gold strips have been developed at IMEC, the Interuniversity Microelectronics Center at Leuven, in Belgium. The electroless plating technology was used, allowing to achieve a strip thickness of up to 1.6 mu m on 10 X 10 cm**2 substrates. Results on signal to noise ratio, spark rate, resulting damages and detector occupancy are presented for counters exposed to various intensities of heavily ionizing particles.

  14. Space Vehicle Heat Shield Having Edgewise Strips of Ablative Material

    Science.gov (United States)

    Blosser, Max L. (Inventor); Poteet, Carl C. (Inventor); Bouslog, Stan A. (Inventor)

    2015-01-01

    A heat shield for a space vehicle comprises a plurality of phenolic impregnated carbon ablator (PICA) blocks secured to a surface of the space vehicle and arranged in a pattern with gaps therebetween. The heat shield further comprises a plurality of PICA strips disposed in the gaps between the PICA blocks. The PICA strips are mounted edgewise, such that the structural orientation of the PICA strips is substantially perpendicular to the structural orientation of the PICA blocks.

  15. Optical properties of lamps with cold emission cathode

    Science.gov (United States)

    Kalenik, Jerzy; Czerwosz, ElŻbieta; Biernacki, Krzysztof; Rymarczyk, Joanna; Stepińska, Izabela

    2016-12-01

    A luminescent lamp was constructed and tested. Phosphor excited by electrons is the source of light. The source of electrons is field emission cathode. The cathode is covered with nickel-carbon layer containing carbon nanotubes that enhance electron emission from the cathode. Results of luminance measurements are presented. Luminance is high enough for lighting application.

  16. Three-Dimensional Model for Strip Hot Rolling

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-min; XIAO Hong; WANG Chun-hua

    2006-01-01

    A three-dimensional model for strip hot rolling was developed, in which the plastic deformation of strip, the thermal crown of rolls, roll deflection and flattening were calculated by rigid-plastic finite element method, finite difference method, influential function method and elastic finite element method respectively. The roll wear was taken into consideration. The model can provide detailed information such as rolling pressure distribution, contact pressure distribution between backup rolls and work rolls, deflection and flattening of work rolls, lateral distribution of strip thickness, and lateral distribution of front and back tensions. The finish rolling on a 1 450 mm hot strip mill was simulated.

  17. Clad strip casting by a twin roll caster

    OpenAIRE

    T. Haga; Nakamura, R; S. Kumai; H. Watari

    2009-01-01

    Purpose: Of this paper is to realize the casting of the clad strip by only one process. Therefore, the investigation of the ability of the casting of the clad strip by a vertical type twin roll caster was operated. The aim of the use of the twin roll caster to make clad strip was in the reduction of the production-energy of the clad strip.Design/methodology/approach: Used in the present study was a vertical type twin roll caster with the scriber. The scriber was used to prevent the mixture of...

  18. Stripped elliptical galaxies as probes of ICM physics: I. Tails, wakes, and flow patterns in and around stripped ellipticals

    CERN Document Server

    Roediger, E; Nulsen, P E J; Forman, W R; Machacek, M; Randall, S; Jones, C; Churazov, E; Kokotanekova, R

    2014-01-01

    (abridged) Elliptical cluster galaxies are successively stripped of their gaseous atmospheres due to their motion through the ICM. The stripped galactic gas forms a 'tail' in the galaxy's wake. Deep X-ray observations reveal the fine-structure of the gas tail and of the interface between galactic gas and ICM. This fine-structure depends on dynamic conditions (galaxy potential, initial gas contents, orbit in the host cluster), stripping stage (early infall, pre-/post-pericenter passage), and on the still ill-constrained ICM plasma properties (thermal conductivity, viscosity, magnetic field structure). In a series of papers, we aim at disentangling dynamic and plasma effects in order to use observed stripped ellipticals as probes of the ICM plasma properties. This first paper determines flow phases and flow patterns of successive gas stripping by means of hydrodynamical simulations. During quasi-steady stripping, the flow of ICM around the remnant atmosphere is similar to the flow around solid bodies, including...

  19. Improving cyclic stability of lithium nickel manganese oxide cathode at elevated temperature by using dimethyl phenylphosphonite as electrolyte additive

    Science.gov (United States)

    Mai, Shaowei; Xu, Mengqing; Liao, Xiaolin; Xing, Lidan; Li, Weishan

    2015-01-01

    A novel electrolyte additive, dimethyl phenylphosphonite (DMPP), is reported in this paper to be able to improve significantly the cyclic stability of LiNi0.5Mn1.5O4 cathode of high voltage lithium ion battery at elevated temperature. When experiencing charge/discharge cycling at 50 °C with 1C (1C = 146.7 mAh g-1) rate in a standard (STD) electrolyte (1.0 M LiPF6 in ethylene carbonate (EC)/dimethyl carbonate (DMC), EC/DMC = 1/2 in volume), LiNi0.5Mn1.5O4 suffers serious discharge capacity decaying, with a capacity retention of 42% after 100 cycles. With adding 0.5% DMPP into the STD electrolyte, the capacity retention is increased to 91%. This improvement can be ascribed to the preferential oxidation of DMPP to the STD electrolyte and the subsequent formation of a protective film on LiNi0.5Mn1.5O4, which suppresses the electrolyte decomposition and protects LiNi0.5Mn1.5O4 from destruction. Theoretical calculations together with voltammetric analyses demonstrate the preferential oxidation of DMPP and the consequent suppression of electrolyte decomposition, while the observations from scanning electron microscopy, X-ray photoelectronic spectroscopy and Fourier transform infrared spectroscopy confirm the protection that DMPP provides for LiNi0.5Mn1.5O4.

  20. Electrochemical performance of carbon nanotube-modified LiFePO_4 cathodes for Li-ion batteries

    Institute of Scientific and Technical Information of China (English)

    陈召勇; 朱华丽; 朱伟; 张建利; 李奇峰

    2010-01-01

    Carbon nanotubes (CNTs) and acetylene black (AB) were dispersed synchronously or separately between LiFePO4 (LFP) particles as conducting agents during the course of manufacture of LiFePO4 cathodes. The morphology and electrochemical performances of as-prepared LiFePO4 were evaluated by means of transmission electron microscopy (TEM), charge-discharge test, electrochemical impedance spectroscope (EIS) and cyclic voltammetry (CV). CNTs contribute to the interconnection of the isolated LiFePO4 or carbon particles. For the CNTs-modified LiFePO4, it exhibits excellent performance in terms of both specific capacity and cycle life. The initial discharge capacity is 147.9 mA·h/g at 0.2C rate and 134.2 mA·h/g at 1C rate, keeping a capacity retention ratio of 97% after 50 cycles. The results from EIS indicate that the impedance value of the solid electrolyte interface decreases. The cyclic voltammetric peak profiles is more symmetric and spiculate and there are fewer peaks. CNTs are promising conductive additives candidate for high-power Li-ion batteries.

  1. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson

    2000-03-31

    . However, they have the potential of being useful as an interface on the anode side of the electrolyte. NexTech has focused much of its effort during the past few months on establishing tape casting methods for porous LSM substrates. This work, performed under a separate DOE-funded program, involved tape casting formulations comprising LSM powders with bi-modal particle size distributions and fugitive pore forming additives. Sintered LSM substrates with porosities in the 30 to 40 vol% range, and pore sizes of 10 {approx} 20 microns have been prepared. In addition, tape casting formulations involving composite mixtures of LSM and Sm-doped ceria (SDC) have been evaluated. The LSM/SDC cathode substrates are expected to provide better performance at low temperatures. Characterization of these materials is currently underway.

  2. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Wayne Huebner; Igor Kosacki

    2001-09-30

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. In this portion of study we have focused on producing YSZ films on porous LSM substrates. When using the polymer precursor there are a number of obstacles to overcome in order to form dense electrolyte layers on porous substrates (cathode or anode). Probably the most difficult problems are: (1) Extreme penetration of the polymer into the substrate must be prevented. (2) Shrinkage cracking must be avoided. (3) Film thickness in the 1 to 5{micro}m range must be achieved. We have demonstrated that cracking due to shrinkage involved during the elimination of solvents and organic matter and densification of the remaining oxide is not a problem as long as the resulting oxide film is < {approx} 0.15 {micro}m in thickness. We have also shown that we can make thicker films by making multiple depositions if the substrate is smooth (roughness {le} 0.1 {micro}m) and contains no surface pores > 0.2 {micro}m. The penetration of the polymer into the porous substrate can be minimized by increasing the viscosity of the polymer and reducing the largest pore at the surface of the substrate to {le} 0.2 {micro}m. We have shown that this can be done, but we have also shown that it is difficult to make dense films that are defect free with areas > 1 cm{sup 2}. This is because of the roughness of the substrate and the difficulty in making a substrate which does not have surface voids > 0.2 {micro}m. Thus the process works well for dense, smooth substrates for films < 1 {micro}m thick, but is difficult to apply to rough, porous surfaces and to make film thickness > 1 {micro}m. As a result of these problems, we have been addressing the issue of how to make dense films in the thickness range of 1 to 5 {micro}m on sintered porous substrates without introducing cracks and holes due to shrinkage and surface voids? These

  3. The double sheath on cathodes of discharges burning in cathode vapour

    Energy Technology Data Exchange (ETDEWEB)

    Benilov, M S; Benilova, L G [Departamento de Fisica, Universidade da Madeira, Largo do MunicIpio, 9000 Funchal (Portugal)

    2010-09-01

    The model of a collisionless near-cathode space-charge sheath with ionization of atoms emitted by the cathode surface is considered. Numerical calculations showed that the mathematical problem is solvable and its solution is unique. In the framework of this model, the sheath represents a double layer with a potential maximum, with the ions which are produced before the maximum returning to the cathode surface and those produced after the maximum escaping into the plasma. Numerical results are given in a form to be readily applicable in analysis of discharges burning in cathode vapour, such as vacuum arcs. In particular, the results indicate that the ion backflow coefficient in such discharges exceeds 0.5, in agreement with values extracted from the experiment.

  4. SKULL-STRIPPING WITH DEFORMABLE ORGANISMS.

    Science.gov (United States)

    Prasad, Gautam; Joshi, Anand A; Thompson, Paul M; Toga, Arthur W; Shattuck, David W; Terzopoulos, Demetri

    2011-01-01

    Segmenting brain from non-brain tissue within magnetic resonance (MR) images of the human head, also known as skull-stripping, is a critical processing step in the analysis of neuroimaging data. Though many algorithms have been developed to address this problem, challenges remain. In this paper, we apply the "deformable organism" framework to the skull-stripping problem. Within this framework, deformable models are equipped with higher-level control mechanisms based on the principles of artificial life, including sensing, reactive behavior, knowledge representation, and proactive planning. Our new deformable organisms are governed by a high-level plan aimed at the fully-automated segmentation of various parts of the head in MR imagery, and they are able to cooperate in computing a robust and accurate segmentation. We applied our segmentation approach to a test set of human MRI data using manual delineations of the data as a reference "gold standard." We compare these results with results from three widely used methods using set-similarity metrics.

  5. Therapeutic surfactant-stripped frozen micelles

    Science.gov (United States)

    Zhang, Yumiao; Song, Wentao; Geng, Jumin; Chitgupi, Upendra; Unsal, Hande; Federizon, Jasmin; Rzayev, Javid; Sukumaran, Dinesh K.; Alexandridis, Paschalis; Lovell, Jonathan F.

    2016-05-01

    Injectable hydrophobic drugs are typically dissolved in surfactants and non-aqueous solvents which can induce negative side-effects. Alternatives like `top-down' fine milling of excipient-free injectable drug suspensions are not yet clinically viable and `bottom-up' self-assembled delivery systems usually substitute one solubilizing excipient for another, bringing new issues to consider. Here, we show that Pluronic (Poloxamer) block copolymers are amenable to low-temperature processing to strip away all free and loosely bound surfactant, leaving behind concentrated, kinetically frozen drug micelles containing minimal solubilizing excipient. This approach was validated for phylloquinone, cyclosporine, testosterone undecanoate, cabazitaxel and seven other bioactive molecules, achieving sizes between 45 and 160 nm and drug to solubilizer molar ratios 2-3 orders of magnitude higher than current formulations. Hypertonic saline or co-loaded cargo was found to prevent aggregation in some cases. Use of surfactant-stripped micelles avoided potential risks associated with other injectable formulations. Mechanistic insights are elucidated and therapeutic dose responses are demonstrated.

  6. Linear sweep voltammetric studies on the supramolecular complex of alizarin red S with lysozyme and determination of lysozyme

    Indian Academy of Sciences (India)

    Wei Sun; Na Zhao; Xueliang Niu; Yan Wang; Kui Jiao

    2009-03-01

    An electrochemical method for the determination of lysozyme (LYS) based on its interaction with alizarin red S (ARS) was established by linear sweep voltammetry in this paper. The electrochemical behaviour of ARS with LYS was investigated on a dropping mercury working electrode in 0.2 mol/L pH 4.8 Britton-Robinson (B-R) buffer solution. ARS showed a sensitive second order derivative linear sweep voltammetric reductive peak at -0.42 V (vs SCE). After the addition of LYS, the reductive peak current of ARS decreased without the shift of the reductive peak potential and no new waves appeared, which was due to the formation of a supramolecular complex of ARS with LYS in the solution. The stoichiometry of the ARS-LYS complex was further calculated by the electrochemical data with the results of the binding ratio as 3 : 1 and the binding constant as 2.82 × 1014. Under the selected conditions, the decrease of the second order derivative linear sweep voltammetric reductive peak current of ARS was in proportion to the LYS concentration in the range from 0.8 to 35.0 mg/L and the detection limit of LYS was calculated as 0.52 mg/L (3). Different kinds of LYS samples were detected satisfactorily with this method.

  7. Electroanalytical characteristics of piribedil and its differential pulse and square wave voltammetric determination in pharmaceuticals and human serum.

    Science.gov (United States)

    Uslu, Bengi; Ozkan, Sibel A

    2003-03-10

    The electrochemical oxidative behavior of piribedil (PR) was described. It was investigated by cyclic, linear sweep, differential pulse (DPV) and square wave (SWV) voltammetric techniques. The redox behavior of PR was found irreversible. Different parameters were tested to optimize the conditions for the determination of PR. The dependence of intensities of currents and potential on pH, concentration, scan rate, nature of the buffer was investigated. Two sensitive methods for the measurement of PR were described. For analytical purposes, a very well resolved diffusion controlled voltammetric peak was obtained in 0.1 M H(2)SO(4) and pH 5.7 acetate buffer. The determination peaks are obtained at 1.27 and 0.95 V for differential pulse and 1.29 and 0.97 V for SWV in 0.1 M H(2)SO(4) and pH 5.7 acetate buffer, respectively. The linear response was obtained in the ranges of 2 x 10(-6)-1 x 10(-3) M in 0.1 M H(2)SO(4) and 2 x 10(-6)-8 x 10(-4) M in pH 5.7 acetate buffer for both techniques. The proposed techniques were successfully applied to the determination of PR in tablet dosage forms and human serum. Excipients did not interfere in the determination. The necessary statistical validation reveals that the proposed methods are free from significant systematic errors.

  8. Electrooxidative decarboxylation of vanillylmandelic acid: voltammetric differentiation between the structurally related compounds homovanillic acid and vanillylmandelic acid.

    Science.gov (United States)

    Li, Qian; Batchelor-McAuley, Christopher; Compton, Richard G

    2010-07-29

    Vanillylmandelic acid (VMA) and homovanillic acid (HVA) are the major end products of catecholamine metabolism. Abnoramally high levels in both plasma and urine may be indicative of a number of diseases including neuroblastoma and phaeochromocytoma. Commonly the VMA:HVA ratio is used as a disease marker, so that any measurement techniques need to be able to differentiate between these two structurally similar compounds. Electrochemistry is often limited in selectivity due to many organic molecules being oxidized or reduced at similar potentials. This work investigates the electrochemical oxidation mechanism of VMA at an edge-plane pyrolytic graphite electrode and highlights how, although structurally similar to HVA, their voltammetric responses may be differentiated through appropriate selection of the electrode material. The oxidation of VMA exhibits two clear peaks and the mechanism is shown to proceed through the decarboxylation of VMA to form vanillin, which is further oxidized resulting in the second peak. Modification of the electrode with a porous layer of multiwalled carbon nanotubes so as to change the mass transport to that of a thin layer system causes the voltammetric resolution between the two species to be enhanced. Differential pulse voltammetry is used to measure the limits of detection for VMA on an edge-plane pyrolytic graphite electrode and on commercially available multiwalled carbon nanotube screen printed electrode, with limits of detection of 1.7 and 1.0 microM, respectively. These limits of detection are well within the range of sensitivity required for clinical sample measurement.

  9. High-pressure hollow cathode discharges

    Science.gov (United States)

    Schoenbach, Karl H.; El-Habachi, Ahmed; Shi, Wenhui; Ciocca, Marco

    1997-11-01

    Reducing the diameter of the cathode hole in a plane anode - hollow cathode geometry to 0963-0252/6/4/003/img1m has allowed us to generate direct current discharges in argon at atmospheric pressure. Up to pressure times cathode hole diameter (pD) values of approximately 5 Torr cm, and at sub-mA currents, glow discharges (predischarges) are observed with a shape which is determined by the vacuum electric field. In the same pD range, but at higher currents of up to approximately 4 mA, the discharges are of the hollow cathode discharge type. At pD values exceeding 5 Torr cm the predischarges turn into surface discharges along the mica spacer between the electrodes. At currents > 4 mA filamentary, pulsed discharges are observed. Qualitative information on the electron energy distribution in the microdischarges has been obtained by studying the VUV emission from ionized argon atoms and the argon excimer radiation at 130 nm. The results of the spectral measurements indicate the presence of a relatively large concentration of electrons with energies > 15 eV over the entire pressure range. The fact that the current - voltage characteristic of the microdischarges has a positive slope over much of the current range where excimer radiation is emitted indicates the possibility of forming arrays of these discharges and using them in flat panel excimer lamps.

  10. Barium depletion in hollow cathode emitters

    Energy Technology Data Exchange (ETDEWEB)

    Polk, James E., E-mail: james.e.polk@jpl.nasa.gov; Mikellides, Ioannis G.; Katz, Ira [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Capece, Angela M. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States)

    2016-01-14

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al{sub 2}O{sub 3} source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  11. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  12. Anode and cathode readout electronics for cylindrical multiwire proportional chambers of the PIBETA detector

    CERN Document Server

    Kalinnikov, V A; Khomutov, N V; Korenchenko, A S; Korenchenko, S M; Kuchinskij, N A; Sidorkin, V V

    2002-01-01

    The cathode amplifier is intended to amplify the positive current pulses from the cathode strips of proportional chambers and drive the 50 Ohm coaxial cable. The amplifier gain and the output voltage swing are matched for operation with the LeCroy 1882F ADC. The special feature of the anode system is the integration of the amplifying section, signal delay unit and digital section for the data outputting to computer in the common ADD-32 module (CAMAC). The 1M-wide ADD-32 module contains the electronics for 32 wires that makes it possible to place up to 672 data channels in the CAMAC crate with a standard bus. To amplify signals, Amp1 8.3 8-channel microcircuits are used. The output logic signals are delayed by 9-channel IDT72421 FIFO microcircuits that enables one to obtain a total signal delay of up to hundreds of microseconds and longer. The digital section of the system is based on ALTERA programmable logic arrays. This system with a total of 576 channels is used in the PIBETA experiment to study rare pion ...

  13. Stream Surface Strip Element Method and Simulation of Three-Dimensional Deformation of Continuous Hot Rolled Strip

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-min; WANG Ying-rui

    2004-01-01

    A new method, the stream surface strip element method, for simulating the three-dimensional deformation of plate and strip rolling process was proposed. The rolling deformation zone was divided into a number of stream surface (curved surface) strip elements along metal flow traces, and the stream surface strip elements were mapped into the corresponding plane strip elements for analysis and computation. The longitudinal distributions of the lateral displacement and the altitudinal displacement of metal were respectively constructed to be a quartic curve and a quadratic curve, of which the lateral distributions were expressed as the third-power spline function, and the altitudinal distributions were fitted in the quadratic curve. From the flow theory of plastic mechanics, the mathematical models of the three-dimensional deformations and stresses of the deformation zone were constructed. Compared with the streamline strip element method proposed by the first author of this paper, the stream surface strip element method takes into account the uneven distributions of stresses and deformations along altitudinal direction, and realizes the precise three-dimensional analysis and computation. The simulation example of continuous hot rolled strip indicates that the method and the model accord with facts and provide a new reliable engineering-computation method for the three-dimensional mechanics simulation of plate and strip rolling process.

  14. Cathode depth sensing in CZT detectors

    Science.gov (United States)

    Hong, JaeSub; Bellm, Eric C.; Grindlay, Jonathan E.; Narita, Tomohiko

    2004-02-01

    Measuring the depth of interaction in thick Cadmium-Zinc-Telluride (CZT) detectors allows improved imaging and spectroscopy for hard X-ray imaging above 100 keV. The Energetic X-ray Imaging Survey Telescope (EXIST) will employ relatively thick (5 - 10 mm) CZT detectors, which are required to perform the broad energy-band sky survey. Interaction depth information is needed to correct events to the detector "focal plane" for correct imaging and can be used to improve the energy resolution of the detector at high energies by allowing event-based corrections for incomplete charge collection. Background rejection is also improved by allowing low energy events from the rear and sides of the detector to be rejected. We present experimental results of intereaction depth sensing in a 5 mm thick pixellated Au-contact IMARAD CZT detector. The depth sensing was done by making simultaneous measurements of cathode and anode signals, where the interaction depth at a given energy is proportional to the ratio of cathode/anode signals. We demonstrate how a simple empirical formula describing the event distributions in the cathode/anode signal space can dramatically improve the energy resolution. We also estimate the energy and depth resolution of the detector as a function of the energy and the interaction depth. We also show a depth-sensing prototype system currently under development for EXIST in which cathode signals from 8, 16 or 32 crystals can be read-out by a small multi-channel ASIC board that is vertically edge-mounted on the cathode electrode along every second CZT crystal boundary. This allows CZT crystals to be tiled contiguously with minimum impact on throughput of incoming photons. The robust packaging is crucial in EXIST, which will employ very large area imaging CZT detector arrays.

  15. Voltammetric behaviour and determination of clonazepam using a disposable screen-printed sensor and its determination in serum and wine

    OpenAIRE

    Honeychurch, K. C.; Brooks, J.; Hart, J. P.

    2016-01-01

    Clonazepam\\ud Screen-printed Carbon Electrodes\\ud Cyclic Voltammetry\\ud Gas chromatography mass spectrometry\\ud Adsorptive Stripping Voltammetry\\ud Sample Preparation and Analysis\\ud Conclusions

  16. Polymer coatings as separator layers for microbial fuel cell cathodes

    KAUST Repository

    Watson, Valerie J.

    2011-03-01

    Membrane separators reduce oxygen flux from the cathode into the anolyte in microbial fuel cells (MFCs), but water accumulation and pH gradients between the separator and cathode reduces performance. Air cathodes were spray-coated (water-facing side) with anion exchange, cation exchange, and neutral polymer coatings of different thicknesses to incorporate the separator into the cathode. The anion exchange polymer coating resulted in greater power density (1167 ± 135 mW m-2) than a cation exchange coating (439 ± 2 mW m-2). This power output was similar to that produced by a Nafion-coated cathode (1114 ± 174 mW m-2), and slightly lower than the uncoated cathode (1384 ± 82 mW m-2). Thicker coatings reduced oxygen diffusion into the electrolyte and increased coulombic efficiency (CE = 56-64%) relative to an uncoated cathode (29 ± 8%), but decreased power production (255-574 mW m-2). Electrochemical characterization of the cathodes ex situ to the MFC showed that the cathodes with the lowest charge transfer resistance and the highest oxygen reduction activity produced the most power in MFC tests. The results on hydrophilic cathode separator layers revealed a trade off between power and CE. Cathodes coated with a thin coating of anion exchange polymer show promise for controlling oxygen transfer while minimally affecting power production. © 2010 Elsevier B.V. All rights reserved.

  17. Virtual cathode microwave generator having annular anode slit

    Science.gov (United States)

    Kwan, Thomas J. T.; Snell, Charles M.

    1988-01-01

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

  18. Cathode R&D for Future Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, D.H.; /SLAC; Bazarov, I.; Dunham, B.; /Cornell U., CLASSE; Harkay, K.; /Argonne; Hernandez-Garcia; /Jefferson Lab; Legg, R.; /Wisconsin U., SRC; Padmore, H.; /LBL, Berkeley; Rao, T.; Smedley, J.; /Brookhaven; Wan, W.; /LBL, Berkeley

    2010-05-26

    This paper reviews the requirements and current status of cathodes for accelerator applications, and proposes a research and development plan for advancing cathode technology. Accelerator cathodes need to have long operational lifetimes and produce electron beams with a very low emittance. The two principal emission processes to be considered are thermionic and photoemission with the photocathodes being further subdivided into metal and semi-conductors. Field emission cathodes are not included in this analysis. The thermal emittance is derived and the formulas used to compare the various cathode materials. To date, there is no cathode which provides all the requirements needed for the proposed future light sources. Therefore a three part research plan is described to develop cathodes for these future light source applications.

  19. Design of ANSYS-based Cathode with Complex Groove

    Institute of Scientific and Technical Information of China (English)

    范植坚; 赵刚刚; 张丽娟

    2012-01-01

    The profile of cathode with complex groove needs to be modified time after time during design of electrochemical machining (ECM) cathode.A design scheme using finite element method (FEM) for cathode with complex profile is put forward to shorten the period of cathode design.Based on Laplace equation,the potential distribution on parameter-transformation model was calculated by using ANSYS,which is compared to the potential distribution calculated by substituting conductivity and current efficiency into Laplace equation.According to the difference between the results calculated and simulated by ANSYS,the cathode profile was modified by adjusting the cathode boundary.The experiments show that the dimensions and shape of workpiece machined by numerically simulated cathode conform well with the blueprint.

  20. A strip array for spoligotyping of Mycobacterium tuberculosis complex isolates.

    Science.gov (United States)

    Tu, Yiling; Zeng, Xiaohong; Li, Hui; Zheng, Rongrong; Xu, Ye; Li, Qingge

    2016-03-01

    A novel strip array was developed for a nine-spacer spoligotyping scheme of Mycobacterium tuberculosis complex (MTBC). The new method was evaluated using 211 MTBC isolates and the results were fully concordant with the traditional spoligotyping approach. The strip array proved to be rapid and convenient for spoligotyping of MTBC.

  1. Tape Stripping Technique for Stratum Corneum Protein Analysis

    DEFF Research Database (Denmark)

    Clausen, Maja-Lisa; Slotved, H-C; Krogfelt, Karen A

    2016-01-01

    The aim of this study was to investigate the amount of protein in stratum corneum in atopic dermatitis (AD) patients and healthy controls, using tape stripping technique. Furthermore, to compare two different methods for protein assessment. Tape stripping was performed in AD patients and healthy...

  2. Modeling of Strip Heating Process in Vertical Continuous Annealing Furnace

    Institute of Scientific and Technical Information of China (English)

    WAN Fei; WANG Yong-qin; QIN Shu-ren

    2012-01-01

    The mechanism for heat transfer of radiation is usually adopted to heat strip in vertical continuous annealing furnace. The rate of heat transfer among strip and other objects can be hugely affected by the parameters of strip speed, geometry factors and radiating characteristic of surfaces of strip, radiating tubes and walls of furnace. A model including all parameters is proposed for calculating the heat transfer coefficient, predicting the strip tempera- ture and boundary temperature of strip through analyzing these parameters. The boundary temperature is a important datum and different from average arithmetic value of temperature of strip and temperature in furnace. Also, the model can be used to analyze the relation for temperature of strip and heat transfer coefficient, total heat transfer quantity and heating time. The model is built by using the radiating heat transfer rate, the Newtonrs law of cooling, and lumped system analysis. The results of calculation are compared to the data from production line. The comparisons indicate that the model can well predict the heating process. The model is already applied for process control in pro- duction line. Also, this research will provide a new method for analyzing the radiation heat transfer.

  3. Fabrication of chitosan-magnetite nanocomposite strip for chromium removal

    Science.gov (United States)

    Sureshkumar, Vaishnavi; Kiruba Daniel, S. C. G.; Ruckmani, K.; Sivakumar, M.

    2016-02-01

    Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan-magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV-visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15-30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan-magnetite nanocomposite strip from aqueous solution was evaluated using UV-visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan-magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

  4. Young tourists visiting strip clubs and paying for sex

    DEFF Research Database (Denmark)

    Hesse, Morten; Tutenges, Sébastien

    2011-01-01

    Little is known about young adults’ use of strip clubs and prostitution during their holidays abroad. This study examined this issue with a sample of 1125 Danish tourists between the ages of 16 and 34, and sought data about the frequency with which they paid for sex and attended strip clubs while...

  5. Using Comic Strips as a Book Report Alternative

    Science.gov (United States)

    Reading Teacher, 2012

    2012-01-01

    Comic strips are great to share with parents, younger students, and peers. This article presents an activity where students use a six-paneled comic strip to summarize a story. This activity allows for multiple interpretations and enhances comprehension by drawing attention to story elements.

  6. Status Quo of China’s Aluminum Sheet & Strip Industry

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>Aluminum sheet & strip products are one of the major product varieties in the aluminum processing industry, they also provide indis-pensable basic materials for the development of national economy. In recent years, driven by rapid economic growth, China’s investment in aluminum sheet & strip industry continued to

  7. Voltammetric and theoretical studies of electrochemical behavior of cephalosporins at the mercury electrode

    Directory of Open Access Journals (Sweden)

    Nikolić Katarina

    2015-01-01

    Full Text Available Study of the adsorption and electroreduction behavior of cefpodoxime proxetil, cefotaxime, desacetylcefotaxime, cefetamet, ceftriaxone, ceftazidime, and cefuroxime axetile at the mercury electrode surface has been performed using Cyclic (CV, Differential Pulse (DPV, and Adsorptive Stripping Differential Pulse Voltammetry (AdSDPV. The Quantitative Structure Property Relationship (QSPR study of the seven cephalosporins adsorption at the mercury electrode has been based on the density functional theory DFT-B3LYP/6-31G (d,p calculations of molecular orbitals, partial charges and electron densities of analytes. The DFT-parameters and QSPR model explain well the process of adsorption of the examined cephalosporins. QSPR study defined that cefalosporins with lower charge of sulphur in the thiazine moiety, lower electron density on the nitrogen atom of the N-O bond, higher number of hydrogen bond accepting groups, and higher principal moment of inertia should express high adsorption on the mercury electrode. [Projekat Ministarstva nauke Republike Srbije, br. 172033

  8. Graphene–platinum nanocomposite as a sensitive and selective voltammetric sensor for trace level arsenic quantification

    Directory of Open Access Journals (Sweden)

    R. Kempegowda

    2014-01-01

    Full Text Available A simple protocol for the chemical modification of graphene with platinum nanoparticles and its subsequent electroanalytical application toward sensitive and selective determination of arsenic has been described. Chemical modification was carried out by the simultaneous and sequential chemical reduction of graphene oxide and hexachloroplatinic acid in the presence of ethylene glycol as a mild reducing agent. The synthesized graphene–platinum nanocomposite (Gr–nPt has been characterized through infrared spectroscopy, x-ray diffraction study, field emission scanning electron microscopy and cyclic voltammetry (CV techniques. CV and square-wave anodic stripping voltammetry have been used to quantify arsenic. The proposed nanostructure showed linearity in the concentration range 10–100 nM with a detection limit of 1.1 nM. The proposed sensor has been successfully applied to measure trace levels of arsenic present in natural sample matrices like borewell water, polluted lake water, agricultural soil, tomato and spinach leaves.

  9. Differential pulse voltammetric determination of metformin using copper-loaded activated charcoal modified electrode.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Mohammadi-Behzad, Leila

    2013-07-01

    A simple and sensitive carbon paste electrode has been developed for the electrochemical trace determination of metformin (MET). This sensor was designed by Copper(II)-loaded activated charcoal (Cu-AC) in the carbon paste electrode (CPE), which provides remarkably improved sensitivity and selectivity for the electrochemical stripping assay of MET. The drug was accumulated on the surface of the electrode through formation of a coordination complex with copper ions, which enhanced the sensitivity of the method. The effects of various copper(II) salts and oxidation states of copper (within the carbon paste electrode) on MET oxidation behavior were also investigated. The calibration graph was linear over the concentration range of 50 nM to 60 μM MET, and the detection limit was calculated as 9 nM. The proposed electrode was used successfully for MET determination in real matrices.

  10. Evaluation of anatomy comic strips for further production and applications.

    Science.gov (United States)

    Shin, Dong Sun; Kim, Dae Hyun; Park, Jin Seo; Jang, Hae Gwon; Chung, Min Suk

    2013-09-01

    The corresponding author of the study has been sketching comic strips to explain anatomy in a humorous manner. All the anatomy comic strips, including those in Korean (650 episodes) and English (451 episodes), can be viewed on the homepage (http://anatomy.co.kr). Such comic strips were created with the aim of assisting medical students. However, their impact was unknown, and therefore, we surveyed the students' responses. We noted that anatomy grades were better in the students who read the comic strips. The comics helped the trainees chat with individuals with and without a medical background. The authors also considered comments on the problems with the comic strips and attempted to find solutions. The episodes are being currently used and further produced for educational purposes. To support this effort, the readers' valuable opinions will be continuously collected and assessed.

  11. Flux avalanches in Nb superconducting shifted strip arrays

    Science.gov (United States)

    Tsuchiya, Y.; Mawatari, Y.; Ibuka, J.; Tada, S.; Pyon, S.; Nagasawa, S.; Hidaka, M.; Maezawa, M.; Tamegai, T.

    2013-09-01

    Flux penetrations into three-dimensional Nb superconducting strip arrays, where two layers of strip arrays are stacked by shifting a half period, are studied using a magneto-optical imaging method. Flux avalanches are observed when the overlap between the top and bottom layers is large even if the width of each strip is well below the threshold value. In addition, anomalous linear avalanches perpendicular to the strip are observed in the shifted strip array when the overlap is very large and the thickness of the superconductor is greater than the penetration depth. We discuss possible origins for the flux avalanches, including linear ones, by considering flux penetration calculated by the Campbell method assuming the Bean model.

  12. Digital autoradiography using silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Overdick, M.

    1998-05-01

    Spatially resolving radiation detection systems operating in real time can be used to acquire autoradiographic images. An overview over alternatives to traditional autoradiography is given and the special features of these filmless methods are discussed. On this basis the design of a system for digital autoradiography using silicon strip detectors is presented. Special emphasis is put on the physical background of the detection process in the semiconductor and on the self-triggering read-out technique. The practical performance of the system is analyzed with respect to energy and spatial resolution. This analysis is complemented by case studies from cell biology (especially electrophoresis), botany and mineralogy. Also the results from a time-resolved autoradiographic experiment are presented. (orig.) 80 refs.

  13. [Obstetrical handbook in comic strip form].

    Science.gov (United States)

    1998-04-01

    An obstetric handbook was created in comic strip form in cooperation with the Ministry of Health in the region of Segou, Mali, for training of traditional midwives living far from community health centers. The drawings illustrate pregnancies at risk that the midwife should be able to identify in order to advise women to stay near the health facility before onset of labor. Drawings indicate pregnancies that are at risk because of the following: small stature, limping as a result of polio or sciatic paralysis, high parity, prior cesarean delivery, heart disease, overly large uterus, or prior stillbirth. Serious complications requiring referral to a health service are also illustrated and include severe anemia, genital bleeding, and signs of toxemia and edema. The midwife should accompany the woman during transport.

  14. Nonlinear optical model for strip plasmonic waveguides

    DEFF Research Database (Denmark)

    Lysenko, Oleg; Bache, Morten; Lavrinenko, Andrei

    2016-01-01

    This paper presents a theoretical model of nonlinear optical properties for strip plasmonic waveguides. The particular waveguides geometry that we investigate contains a gold core, adhesion layers, and silicon dioxide cladding. It is shown that the third-order susceptibility of the gold core...... significantly depends on the layer thickness and has the dominant contribution to the effective third-order susceptibility of the long-range plasmon polariton mode. This results in two nonlinear optical effects in plasmonic waveguides, which we experimentally observed and reported in [Opt. Lett. 41, 317 (2016......)]. The first effect is the nonlinear power saturation of the plasmonic mode, and the second effect is the spectral broadening of the plasmonic mode. Both nonlinear plasmonic effects can be used for practical applications and their appropriate model will be important for further developments in communication...

  15. Optical fiber cable chemical stripping fixture

    Science.gov (United States)

    Kolasinski, John R. (Inventor); Coleman, Alexander M. (Inventor)

    1995-01-01

    An elongated fixture handle member is connected to a fixture body member with both members having interconnecting longitudinal central axial bores for the passage of an optical cable therethrough. The axial bore of the fixture body member, however, terminates in a shoulder stop for the outer end of a jacket of the optical cable covering both an optical fiber and a coating therefor, with an axial bore of reduced diameter continuing from the shoulder stop forward for a predetermined desired length to the outer end of the fixture body member. A subsequent insertion of the fixture body member including the above optical fiber elements into a chemical stripping solution results in a softening of the exposed external coating thereat which permits easy removal thereof from the optical fiber while leaving a desired length coated fiber intact within the fixture body member.

  16. Streptococcus pneumoniae carriage in the Gaza strip.

    Directory of Open Access Journals (Sweden)

    Gili Regev-Yochay

    Full Text Available BACKGROUND: Pneumococcal infections cause major morbidity and mortality in developing countries. We report the epidemiology of S. pneumoniae carriage in a developing region, the Gaza strip, and evaluate the theoretical coverage of carriage strains by pneumococcal conjugate vaccines (PCVs. METHODOLOGY: In 2009 we conducted a cross-sectional survey of S. pneumoniae carriage in healthy children and their parents, living throughout the Gaza strip. Data were collected and nasopharyngeal swabs were obtained. Antibiotic susceptibilities were determined by Vitek-2 and serotypes by the Quellung reaction. PRINCIPAL FINDINGS: S. pneumoniae carriage was detected in 189/379 (50% of children and 30/376 (8% of parents. Carriage prevalence was highest in children <6 months of age (63%. Significant predictors for child carriage were number of household members and DCC attendance. The proportion of pediatric and adults isolates with serotypes included in PCV7 were 32% and 20% respectively, and 46% and 33% in PCV13 respectively. The most prominent non-vaccine serotypes (NVT were 35B, 15B/C and 23B. Penicillin-nonsusceptible strains were carried by 70% of carriers, penicillin-resistant strains (PRSP by 13% and Multi-drug-resistant (MDR by 30%. Of all PRSP isolates 54% belonged to serotypes included in PCV7 and 71% in the PCV13. Similarly, 59% and 73% of MDR-SP isolates, would theoretically be covered by PCV7 and PCV13, respectively. CONCLUSIONS: This study demonstrates that, PCV13-included strains were carried by 46% and 33% of pediatric and adult subjects respectively. In the absence of definitive data regarding the virulence of the NVT strains, it is difficult to predict the effect of PCVs on IPD in this region.

  17. Erosion behaviour of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    CERN Document Server

    Franz, Robert; Hawranek, Gerhard; Polcik, Peter

    2015-01-01

    Al$_{x}$Cr$_{1-x}$ composite cathodes with Al contents of x = 0.75, 0.5 and 0.25 were exposed to cathodic arc plasmas in Ar, N$_2$ and O$_2$ atmospheres and their erosion behaviour was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by X-ray diffraction analysis. Cathode poisoning effects in the reactive N$_2$ and O$_2$ atmospheres were non-uniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded centre region of the cathodes.

  18. Application of WLS strips for position determination in Strip PET tomograph based on plastic scintillators

    CERN Document Server

    Smyrski, J; Bednarski, T; Białas, P; Czerwiński, E; Kapłon, Ł; Kochanowski, A; Korcyl, G; Kowal, J; Kowalski, P; Kozik, T; Krzemień, W; Molenda, M; Niedźwiecki, Sz; Pałka, M; Pawlik, M; Raczyński, L; Rudy, Z; Salabura, P; Sharma, N G; Silarski, M; Słomski, A; Strzelecki, A; Wiślicki, W; Zieliński, M; Zoń, N

    2013-01-01

    A method of determination of a gamma quantum absorption point in a plastic scintillator block using a matrix of wavelength-shifting (WLS) strips is proposed. Application of this method for improvement of position resolution in newly proposed PET detectors based on plastic scintillators is presented. The method enables to reduce parallax errors in reconstruction of images which occurs in the presently used Positron Emission Tomography scanners.

  19. Facile synthesis and thermoelectric studies of n-type bismuth telluride nanorods with cathodic stripping Te electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Guoqiu [School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, Jiangsu (China); Li, Yusong [School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, Jiangsu (China); Department of Chemistry and Chemical Engineering, Southeast University, 210092 Jiangsu (China); Bao, Ning [School of Public Health, Nantong University, Nantong 226019, Jiangsu (China); Miao, Jianwen [School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, Jiangsu (China); Ge, Cunwang, E-mail: gecunwang@ntu.edu.cn [School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, Jiangsu (China); Wang, Yihong [Department of Chemistry and Chemical Engineering, Southeast University, 210092 Jiangsu (China)

    2014-01-15

    Bismuth telluride (Bi{sub 2}Te{sub 3}) nanorods (NRs) of n-type thermoelectric materials were prepared using an electrogenerated precursor of tellurium electrode in the presence of Bi{sup 3+} and mercapto protecting agent in aqueous solution under atmosphere condition. The optimal preparation conditions were obtained with ratio of Bi{sup 3+} to mercapto group and Te coulomb by photoluminescence spectra. The mechanism for generation of Bi{sub 2}Te{sub 3} precursor was investigated via the cyclic voltammetry. The highly crystalline rhombohedral structure of as-prepared Bi{sub 2}Te{sub 3} NRs with the shell of Bi{sub 2}S{sub 3} was evaluated with high resolution transmission electron microscopy (HRTEM) and powder X-ray diffraction (XRD) spectroscopy. The near-infrared absorption of synthetic Bi{sub 2}Te{sub 3} NRs was characterized with spectrophotometer to obtain information of electron at interband transition. The thermoelectric performance of Bi{sub 2}Te{sub 3} NRs was assessed with the result of electrical resistivity, Seebeck coefficient, thermal conductivity, and the figure of merit ZT parameters, indicating that thermoelectric performance of as-prepared Bi{sub 2}Te{sub 3} nanocrystals was improved by reducing thermal conductivity while maintaining the power factor. - Graphical abstract: The nanorods of n-type chalcogenides semiconductors of Bi{sub 2}Te{sub 3} are prepared using electrochemical technique with Te electrode. The highly crystalline rhombohedral structure of Bi{sub 2}Te{sub 3} nanorods with the shell of Bi{sub 2}S{sub 3} is demonstrated. The thermoelectric measurement indicated that thermoelectric performance of Bi{sub 2}Te{sub 3} NRs was improved by a highly reduced thermal conductivity while maintaining the power factor. - Highlights: • The n-type Bi{sub 2}Te{sub 3} nanorods are prepared using an electrogenerated precursor. • The rhombohedral structure of Bi{sub 2}Te{sub 3} nanorods with the shell of Bi{sub 2}S{sub 3} is demonstrated. • Bi{sub 2}Te{sub 3} nanorods show high thermoelectric performance.

  20. New Concept of Cultivation Using Limited Strip-Tillage with Strip Shallow Irrigation

    Directory of Open Access Journals (Sweden)

    Yazid Ismi Intara

    2014-04-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE Dry land is one of land resources which potentially used for food crop cultivation, especially in the areas which have light to medium technical obstacles. The development of technology to improve soil quality in marginal lands to be productive lands is still widely open for agricultural development in Indonesia. Rooting medium quality can be improved by changing soil tillage method and observing the proper crop irrigation technology. It can be the solution for crop cultivation in clay loam soil. This study aimed to obtain water movement model in a minimally-tilled clay soil with strip shallow irrigation. The concept is limited soil-tillage with strip shallow irrigation method, water supply technique, and crop water requirement. Method used in this study includes developing water movement model (software development in a minimally-tilled clay soil with subsurface irrigation. In the final stages, research also conducted water movement analysis testing apparatus in the laboratory, field validation of the subsurface irrigation performance, and cultivation technique testing to chili pepper growth (Capsicum annuumL.. The development of water movement simulation on a limited strip-tillage with subsurface irrigation uses the concept to quantify the amount of water in the soil. The analysis of movement pattern was demonstrated on contour patterns. It showed that the wetting process can reach depth zone – 5 cm to the rooting zone. It was an important discovery on the development of minimum stripe tillage soil with subsurface irrigation. Specifically, it can be concluded that: the result of fitting by eyes to diffusivity graphic and water content obtained the required parameter values for soil physical properties. It was then simulated on horizontal water movement model on a minimum strip-tillage with strip shallow irrigation /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso

  1. Cathodic Cage Plasma Nitriding: An Innovative Technique

    OpenAIRE

    Sousa,R.R.M.; de Araújo, F. O.; J. A. P. da Costa; Brandim,A.S.; R. A. de Brito; C. Alves

    2012-01-01

    Cylindrical samples of AISI 1020, AISI 316, and AISI 420 steels, with different heights, were simultaneously treated by a new technique of ionic nitriding, entitled cathodic cage plasma nitriding (CCPN), in order to evaluate the efficiency of this technique to produce nitrided layers with better properties compared with those obtained using conventional ionic nitriding technique. This method is able to eliminate the edge effect in the samples, promoting a better uniformity of temperature, and...

  2. FUZZY LOGIC CONTROLLED CATHODIC PROTECTION CIRCUIT DESIGN

    OpenAIRE

    AKÇAYOL, M. Ali

    2010-01-01

    In this study, output voltage of automatic transformer-rectifier (TR) unit of impressed current cathodic protection has been controlled by using fuzzy logic controller. To prevent corrosion, voltage between the protection metal and the auxiliary anode has to be controlled on a desired level. Because soil resistance in the environment changes with humidity and soil characteristics, TRs must control the output voltage between protection metal and auxiliary anode automatically. In this study, a ...

  3. The Hollow Cathode Phase of Pseudospark Operation

    Science.gov (United States)

    1993-06-01

    THE HOLLOW CATHODE PHASE OF PSEUDOSPARK OPERATION L. Pitchford and J. P. Boeuf University Paul Sabatier, France V. Puech University De Paris-Sud...ORGANIZATION NAME(S) AND ADDRESS(ES) University Paul Sabatier, France 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME...Appl. Phys. 53, 1699 (1988). [9] A. Anders, S. Anders, and M. Gundersen, submitted to Phys. Rev. Lett. [10] J. P. Boeuf and L. Pitchford , IEEE

  4. A definitive criterion for cathodic protection

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Roger [Cathodic Protection Network International Ltd., Reading (United Kingdom)

    2009-07-01

    The corrosion reaction is defined using the Pourbaix Diagram and includes consideration of the pH, temperature, pressure, nobility of the metal and conductivity of the electrolyte. The passive zone can be established in a laboratory by creating a closed circuit condition in which the voltages can be measured. Natural corrosion cells occurring in simple conditions can be evaluated for the purpose of monitoring the performance of cathodic protection. Metal pipelines are complex networks of conductors submerged in electrolyte of infinitely variable qualities. The present method used to ascertain the effectiveness of cathodic protection has many inherent errors and results in costly and unpredictable corrosion failures. An electrode has been devised to define the exact electrical status of the corrosion reaction at its location. The design allows a closed circuit measurement of the corrosion current that can determine whether or not corrosion has been stopped by cathodic protection. This has allowed the development of software that can calculate the condition and corrosion status throughout a network of pipelines, using electrical circuit analysis common in the electronics industry. (author)

  5. Voltammetric Detection of Urea on an Ag-Modified Zeolite-Expanded Graphite-Epoxy Composite Electrode

    Directory of Open Access Journals (Sweden)

    Joop Schoonman

    2008-09-01

    Full Text Available In this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification.

  6. Cadmium binding in mixtures of phytochelatins and their fragments: a voltammetric study assisted by multivariate curve resolution and mass spectrometry.

    Science.gov (United States)

    Gusmão, Rui; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

    2010-01-01

    Phytochelatins (PC(n), (gamma-Glu-Cys)(n)Gly) are cysteine-rich peptides synthesized by plants which are involved in metal bioregulation and phytoremediation. Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) is applied to voltammetric data obtained from the analysis of the competitive binding of Cys or Cys-Gly with PC(2) or PC(3) by Cd(2+). The displacements between ligands, the chain length dependence on the competitive binding to PC(n) and the possible existence of mixed ligand metal-complexes are investigated. The shape analysis of the resulting pure voltammograms and concentration profiles of the components resolved by MCR-ALS suggests that ligands containing more thiol groups are able to displace the shorter chain ligands from their metal complexes, whereas the opposite does not happen. Electrochemical results are compared with ESI-MS measurements.

  7. Morphological and compositional engineering of Ni/carbon nanotube composite film via a novel cyclic voltammetric route

    Indian Academy of Sciences (India)

    Yu Jun Yang

    2012-08-01

    Ni/multi-walled carbon nanotubes (MWCNTs) composite films were deposited on the glassy carbon electrode (GCE) by a Ni plating bath containing homogeneously dispersed MWCNTs using polyvinylpyrrolidone (PVP) as dispersion additive. Incorporation of MWCNTs into Ni matrix was greatly enhanced by the application of cyclic voltammetric (CV) deposition technique. The structure and nature of the Ni/MWCNT were characterized by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). The results show that the content of MWCNT and the morphology of the deposited Ni/MWCNT composite film can be controlled by selecting the appropriate electroplating conditions. Further study indicates that the obtained Ni/MWCNT showed excellent electro-catalytic activity for the oxidation of ethanol in alkaline solution.

  8. The Application of Nafion Metal Catalyst Free Carbon Nanotube Modified Gold Electrode: Voltammetric Zinc Detection in Serum

    Science.gov (United States)

    Yue, Wei; Bange, Adam; Riehl, Bill L.; Johnson, Jay M.; Papautsky, Ian; Heineman, William R.

    2013-01-01

    Metal catalyst free carbon nanotube (MCFCNT) whiskers were first used as an electrode modification material on a gold electrode surface for zinc voltammetric measurements. A composite film of Nafion and MCFCNT whiskers was applied to a gold electrode surface to form a mechanically stable sensor. The sensor was then used for zinc detection in both acetate buffer solution and extracted bovine serum solution. A limit of detection of 53 nM was achieved for a 120 s deposition time. The zinc in bovine serum was extracted via a double extraction procedure using dithizone in chloroform as a zinc chelating ligand. The modified electrode was found to be both reliable and sensitive for zinc measurements in both matrices. PMID:24436574

  9. Amplified voltammetric characterization of cleavage of the biotinylated peptide by BACE1 and screening of BACE1 inhibitors.

    Science.gov (United States)

    Yi, Xinyao; Han, Hongxing; Zhang, Yu; Wang, Jianxiu; Zhang, Yi; Zhou, Feimeng

    2013-12-15

    Cleavage of amyloid precursor protein (APP) by the β-site APP cleaving enzyme 1 (BACE1) is a key step in the formation of amyloid beta (Aβ) peptide, the main component of amyloid plaques in Alzheimer's disease (AD). Suppression of BACE1 activity has thus become an efficient way for the treatment of AD. In this study, BACE1 in the absence or presence of BACE1 inhibitors was exposed to the biotinylated peptide substrate-modified electrode. This step was followed by the attachment of ferrocene (Fc)-capped gold nanoparticle/streptavidin conjugates. Due to the blockage of the BACE1 activity by select inhibitors, well-defined voltammetric peaks of high signal intensity were obtained. However, featureless voltammogram was obtained upon initiating the cleavage reaction. The proposed method is simple, sensitive, and suitable for monitoring of BACE1 activity and screening of BACE1 inhibitors.

  10. Cathode power distribution system and method of using the same for power distribution

    Science.gov (United States)

    Williamson, Mark A; Wiedmeyer, Stanley G; Koehl, Eugene R; Bailey, James L; Willit, James L; Barnes, Laurel A; Blaskovitz, Robert J

    2014-11-11

    Embodiments include a cathode power distribution system and/or method of using the same for power distribution. The cathode power distribution system includes a plurality of cathode assemblies. Each cathode assembly of the plurality of cathode assemblies includes a plurality of cathode rods. The system also includes a plurality of bus bars configured to distribute current to each of the plurality of cathode assemblies. The plurality of bus bars include a first bus bar configured to distribute the current to first ends of the plurality of cathode assemblies and a second bus bar configured to distribute the current to second ends of the plurality of cathode assemblies.

  11. Effect of cathode model on arc attachment for short high-intensity arc on a refractory cathode

    Science.gov (United States)

    Javidi Shirvan, Alireza; Choquet, Isabelle; Nilsson, Håkan

    2016-12-01

    Various models coupling the refractory cathode, the cathode sheath and the arc at atmospheric pressure exist. They assume a homogeneous cathode with a uniform physical state, and differ by the cathode layer and the plasma arc model. However even the most advanced of these models still fail in predicting the extent of the arc attachment when applied to short high-intensity arcs such as gas tungsten arcs. Cathodes operating in these conditions present a non-uniform physical state. A model taking into account the first level of this non-homogeneity is proposed based on physical criteria. Calculations are done for 5 mm argon arcs with a thoriated tungsten cathode. The results obtained show that radiative heating and cooling of the cathode surface are of the same order. They also show that cathode inhomogeneity has a significant effect on the arc attachment, the arc temperature and pressure. When changing the arc current (100 A, 200 A) the proposed model allows predicting trends observed experimentally that cannot be captured by the homogeneous cathode model unless restricting a priori the size of the arc attachment. The cathode physics is thus an important element to include to obtain a comprehensive and predictive arc model.

  12. The water crisis in the gaza strip: prospects for resolution.

    Science.gov (United States)

    Weinthal, E; Vengosh, A; Marei, A; Kloppmann, W

    2005-01-01

    Israel and the Palestinian Authority share the southern Mediterranean coastal aquifer. Long-term overexploitation in the Gaza Strip has resulted in a decreasing water table, accompanied by the degradation of its water quality. Due to high levels of salinity and nitrate and boron pollution, most of the ground water is inadequate for both domestic and agricultural consumption. The rapid rate of population growth in the Gaza Strip and dependence upon ground water as a single water source present a serious challenge for future political stability and economic development. Here, we integrate the results of geochemical studies and numerical modeling to postulate different management scenarios for joint management between Israel and the Palestinian Authority. The chemical and isotopic data show that most of the salinity phenomena in the Gaza Strip are derived from the natural flow of saline ground water from Israel toward the Gaza Strip. As a result, the southern coastal aquifer does not resemble a classic "upstream-downstream" dispute because Israel's pumping of the saline ground water reduces the salinization rates of ground water in the Gaza Strip. Simulation of different pumping scenarios using a monolayer, hydrodynamic, two-dimensional model (MARTHE) confirms the hypothesis that increasing pumping along the Gaza Strip border combined with a moderate reduction of pumping within the Gaza Strip would improve ground water quality within the Gaza Strip. We find that pumping the saline ground water for a source of reverse-osmosis desalination and then supplying the desalinated water to the Gaza Strip should be an essential component of a future joint management strategy between Israel and the Palestinian Authority.

  13. Modelling cathode spots in glow discharges in the cathode boundary layer geometry

    CERN Document Server

    Almeida, P G C; Bieniek, M S

    2015-01-01

    Self-organized patterns of cathode spots in glow discharges are computed in the cathode boundary layer geometry, which is the one employed in most of the experiments reported in the literature. The model comprises conservation and transport equations of electrons and a single ion species, written in the drift-diffusion and local-field approximations, and Poisson's equation. Multiple solutions existing for the same value of the discharge current and describing modes with different configurations of cathode spots are computed by means of a stationary solver. The computed solutions are compared to their counterparts for plane-parallel electrodes, and experiments. All of the computed spot patterns have been observed in the experiment.

  14. Cathodic phosphate coating containing nano zinc particles on magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A technology for preparation of a cathodic phosphate coating mainly containing nano metallic zinc particles and phosphate compounds on magnesium alloy was developed.The influence of cathodic current density on the microstructure of the cathodic phosphate coating Was investigated.The results show that the crystals of the coating are finer and the microstructures of the outer surface of the coatings are zigzag at the cathodic density of 0.2-0.5 A/dm2.The content of nano metallic zinc particles in the coating decreases with the increase of the thickness of the coatings and tends to be zero when the coating thickness is 4.14 μm.The cathodic phosphate coating was applied to be a transition coating for improving the adhesion between the paints and the magnesium alloys.The formation mechanism of the cathodic phosphate coating was investigated as well.

  15. Preliminary experimental study of a carbon fiber array cathode

    Science.gov (United States)

    Li, An-kun; Fan, Yu-wei

    2016-08-01

    The preliminary experimental results of a carbon fiber array cathode for the magnetically insulated transmission line oscillator (MILO) operations are reported. When the diode voltage and diode current were 480 kV and 44 kA, respectively, high-power microwaves with a peak power of about 3 GW and a pulse duration of about 60 ns were obtained in a MILO device with the carbon fiber array cathode. The preliminary experimental results show that the shot-to-shot reproducibility of the diode current and the microwave power is stable until 700 shots. No obvious damage or deterioration can be observed in the carbon fiber surface morphology after 700 shots. Moreover, the cathode performance has no observable deterioration after 700 shots. In conclusion, the maintain-free lifetime of the carbon fiber array cathode is more than 700 shots. In this way, this carbon fiber array cathode offers a potential replacement for the existing velvet cathode.

  16. Effect of cathodic protection on the state of steel reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Cam, Phan Luong; Thuy, Thi Bich [Hanoi University of Technology, Hanoi (Viet Nam)

    2002-10-15

    Damage of reinforced concrete structures is mainly caused by chloride or carbonation induced corrosion of steel. Cathodic protection is a very effective measure for corrosion control of steel in concrete, especially in chloride contaminated concrete. In this paper, effect of cathodic protection on the state of steel reinforcement is presented. Cathodic polarization of reinforcements in concrete was done under different submerged conditions. Cyclic potentiodynamic tests were used to determine the effect of cathodic protection on the behavior of the steel. Pitting appeared on the non-protected steel, but was not observed on the cathodically protected steel. microscopic photographs show that a close film exists on the protected steel, while the non-protected steel's film is loose. Investigated results have proved the effect of cathodic protection in restoring or strengthening passive film on the steel reinforcement

  17. Rf Gun with High-Current Density Field Emission Cathode

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2005-12-19

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  18. Assistant Anode in a Cathodic Arc Plasma Source

    Institute of Scientific and Technical Information of China (English)

    张涛; Paul K. Chu; 张荟星; Ian G. Brown

    2001-01-01

    The performance and characteristics of a cathodic arc plasma source, consisting of a titanium cathode, an anode with and without a tungsten mesh, and a coil producing a focusing magnetic field between the anode and cathode,are investigated. The high transparency and large area of the mesh allow a high plasma flux to penetrate the anode from the cathodic arc. The mesh helps to decrease the arc resistance and the ignition voltage of the cathodic arc in the focusing magnetic field, and to increase the life of the source, which means that the source makes the cathodic arc easily and greatly stabilized during the operation when a focusing magnetic field exists in the source.

  19. Cathodic electrocatalyst layer for electrochemical generation of hydrogen peroxide

    Science.gov (United States)

    Rhodes, Christopher P. (Inventor); Tennakoon, Charles L. K. (Inventor); Singh, Waheguru Pal (Inventor); Anderson, Kelvin C. (Inventor)

    2011-01-01

    A cathodic gas diffusion electrode for the electrochemical production of aqueous hydrogen peroxide solutions. The cathodic gas diffusion electrode comprises an electrically conductive gas diffusion substrate and a cathodic electrocatalyst layer supported on the gas diffusion substrate. A novel cathodic electrocatalyst layer comprises a cathodic electrocatalyst, a substantially water-insoluble quaternary ammonium compound, a fluorocarbon polymer hydrophobic agent and binder, and a perfluoronated sulphonic acid polymer. An electrochemical cell using the novel cathodic electrocatalyst layer has been shown to produce an aqueous solution having between 8 and 14 weight percent hydrogen peroxide. Furthermore, such electrochemical cells have shown stable production of hydrogen peroxide solutions over 1000 hours of operation including numerous system shutdowns.

  20. Element Tracking Strategies for Hot Strip Laminar Cooling Control

    Institute of Scientific and Technical Information of China (English)

    HAN Bin; ZHANG Zhong-ping; LIU Xiang-hua; WANG Guo-dong

    2005-01-01

    Feedforward control is the core to control function in the cooling process of hot strip. One of the most important tasks in feedforward control is to determine the arrival time of the strip at various locations on the runout table for effective control. Based on the principles of element tracking and tracking strategies for variable rolling speed and constant rolling speed, a simple diagonal tracking method for an existing hot strip mill was proposed and tested. The test results show that the proposed strategies are effective for improving tracking control.