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Sample records for anodic stripping voltammetry

  1. Linear sweep anodic stripping voltammetry: Determination of ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 6. Linear sweep anodic stripping voltammetry: Determination of Chromium (VI) using synthesized gold nanoparticles modified screen-printed electrode. Salamatu Aliyu Tukur Nor Azah Yusof Reza Hajian. Regular Articles Volume 127 Issue 6 June 2015 pp ...

  2. Digital simulation of anodic stripping voltammetry from thin film electrodes

    International Nuclear Information System (INIS)

    Magallanes, J.F.

    1984-01-01

    The anodic stripping voltammetry (ASV) is routinely applied to control of Cu(II) in heavy water in the primary cooling loop of the Nuclear Power Reactor. The anodic stripping voltammetry (ASV) is a very well-known technique in electroanalytical chemistry. However, due to the complexity of the phenomena, it is practised with the fundamentals of empiric considerations. A geometric model for the anodic stripping voltammetry (ASV) from thin film electrodes which can be calculated by explicit digital simulation method is proposed as a possibility of solving the electrochemically reversible, cuasi-reversible and irreversible reactions under linear potential scan and multiple potential scans. (Until now the analytical mathematical method was applied to reversible reactions). All the results are compared with analytical solutions and experimental results and it permits to conclude that the anodic stripping voltammetry (ASV) can be studied with the simplicity and potentialities of explicit digital simulation methods. (M.E.L.) [es

  3. Anodic stripping voltammetry – ASV for determination of heavy metals

    International Nuclear Information System (INIS)

    Barón-Jaimez, J; Joya, M R; Barba-Ortega, J

    2013-01-01

    Although voltammetric methods presented a number of difficulties in its early stages, nowadays ''ASV'' anodic stripping voltammetry is considered one of the most sensitive electro-analytical and suitable for trace-level determination of many metals and compounds in environmental samples, clinical and industrial. Its sensitivity is attributed to the combination of a step of pre-concentration effective together with an electrochemical advanced measurement of accumulated analyte. This paper presents an overview of the voltammetry, which includes a group of electro-analytical methods, in them the information about analyte is obtained from measurements of the current flowing in an electrochemical cell when applied a potential difference to an suitable electrode system

  4. Cloud Point Extraction for Electroanalysis: Anodic Stripping Voltammetry of Cadmium.

    Science.gov (United States)

    Rusinek, Cory A; Bange, Adam; Papautsky, Ian; Heineman, William R

    2015-06-16

    Cloud point extraction (CPE) is a well-established technique for the preconcentration of hydrophobic species from water without the use of organic solvents. Subsequent analysis is then typically performed via atomic absorption spectroscopy (AAS), UV-vis spectroscopy, or high performance liquid chromatography (HPLC). However, the suitability of CPE for electroanalytical methods such as stripping voltammetry has not been reported. We demonstrate the use of CPE for electroanalysis using the determination of cadmium (Cd(2+)) by anodic stripping voltammetry (ASV). Rather than using the chelating agents which are commonly used in CPE to form a hydrophobic, extractable metal complex, we used iodide and sulfuric acid to neutralize the charge on Cd(2+) to form an extractable ion pair. This offers good selectivity for Cd(2+) as no interferences were observed from other heavy metal ions. Triton X-114 was chosen as the surfactant for the extraction because its cloud point temperature is near room temperature (22-25 °C). Bare glassy carbon (GC), bismuth-coated glassy carbon (Bi-GC), and mercury-coated glassy carbon (Hg-GC) electrodes were compared for the CPE-ASV. A detection limit for Cd(2+) of 1.7 nM (0.2 ppb) was obtained with the Hg-GC electrode. ASV with CPE gave a 20x decrease (4.0 ppb) in the detection limit compared to ASV without CPE. The suitability of this procedure for the analysis of tap and river water samples was demonstrated. This simple, versatile, environmentally friendly, and cost-effective extraction method is potentially applicable to a wide variety of transition metals and organic compounds that are amenable to detection by electroanalytical methods.

  5. Disposable copper-based electrochemical sensor for anodic stripping voltammetry.

    Science.gov (United States)

    Pei, Xing; Kang, Wenjing; Yue, Wei; Bange, Adam; Heineman, William R; Papautsky, Ian

    2014-05-20

    In this work, we report the first copper-based point-of-care sensor for electrochemical measurements demonstrated by zinc determination in blood serum. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Electrochemistry offers a simple approach to metal detection on the microscale, but traditional carbon, gold (Au), or platinum (Pt) electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor features a new low-cost electrode material, copper, which offers simple fabrication and compatibility with microfabrication and PCB processing, while maintaining competitive performance in electrochemical detection. Anodic stripping voltammetry of zinc using our new copper-based sensors exhibited a 140 nM (9.0 ppb) limit of detection (calculated) and sensitivity greater than 1 μA/μM in the acetate buffer. The sensor was also able to determine zinc in a bovine serum extract, and the results were verified with independent sensor measurements. These results demonstrate the advantageous qualities of this lab-on-a-chip electrochemical sensor for clinical applications, which include a small sample volume (μL scale), reduced cost, short response time, and high accuracy at low concentrations of analyte.

  6. Anodic Stripping Voltammetry for Arsenic Determination on Composite Gold Electrode

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Kopanica, M.; Krista, J.

    2003-01-01

    Roč. 48, č. 2 (2003), s. 265-272 ISSN 0009-2223 Grant - others:GIT(AR) 101/02/U111/CZ Institutional research plan: CEZ:AV0Z4040901 Keywords : arsenic determination * stripping voltammetry * composite gold electrode Subject RIV: CG - Electrochemistry Impact factor: 0.415, year: 2003

  7. Anodic stripping voltammetry using graphite composite solid electrode

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Barek, J.; Kopanica, Miloslav

    2009-01-01

    Roč. 74, 11-12 (2009), s. 1807-1826 ISSN 0010-0765 R&D Projects: GA AV ČR IAA400400806; GA ČR GA203/07/1195; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : Graphite composite solid electrode * voltammetry * metals Subject RIV: CG - Electrochemistry Impact factor: 0.856, year: 2009

  8. Anodic stripping voltammetry of mercury, zinc, cadmium, and lead in a rice farm ecosystem

    International Nuclear Information System (INIS)

    Del Mundo, F.R.; Vicente-Beckett, V.A.

    1990-01-01

    Analytical procedures based on differential pulse anodic stripping voltammetry were developed and applied to the analysis of some trace metals in a rice farm ecosystem. A gold wire served as working electrode for the analysis of mercury in 0.1M HNO 3 ; a hanging mercury drop electrode was used for the simultaneous analyses of zinc, cadmium, and lead in 0.1M sodium acetate buffer (pH 4.5). Mercury was pre-concentrated for five minutes at + 0.20 V vs SCE. The area of the anodic stripping peaks varied linearly over the concentration range 3x10 -10 -2x10 -8 M Hg(II); the limit of detection was 0.06 ppb or 3x10 -10 M Hg(II). The simultaneous analytical method involved pre-electrolysis at -1.2 V vs SCE for ten minutes. The heights of the individual anodic stripping peaks varied linearly with concentration in a mixture of the ions over the concentration range 0.020-0.10 ppm for each ion; the limits of detection were 0.004 ppm, 0.01 ppm, and 0.01 ppm for Cd, Pb, Zn, respectively. The developed procedures were used to determine the baseline levels of these metals in soil, water, and rice plant samples from a one-hectare traditional rice farm in San Pedro, Laguna. (auth.). 26 refs.; 4 tabs.; 6 figs

  9. DIFFERENTIAL PULSE ANODIC STRIPPING VOLTAMMETRY FOR DETERMINATION OF SOME HEAVY METALS IN URANIUM

    Directory of Open Access Journals (Sweden)

    Saryati Saryati

    2010-06-01

    Full Text Available The direct determination of some metals impurity in uranium by using differential pulse anodic stripping voltammetry (DPASV method at a hanging mercury drop electrode and in a carbonate buffer media was developed. It was found that the carbonate buffer show the strongest affinity for uranium and gives the best separation between the DPASV peaks of heavy metals impurities. The carbonate concentration markedly affects the oxidation and reduction the major and the minor constituents of the uranium samples. In 0.1 M carbonate buffer solution pH 10, copper, bismuth, thalium, lead, cadmium, zinc, could be determined without the removal of the uranium matrix. Recovery and relative standard deviation (RSD of this method was in the range of 174% - 85.2% for recovery and 36.8% - 1.2% for RSD. The larger error of analytical result was obtained for Zn at low concentration. In general, the analytic results error and RSD decreased with increasing metals concentration.   Keywords: heavy metal determination, differential pulse anodic stripping voltammetry, uranium

  10. Anodic stripping voltammetry of antimony using gold nanoparticle-modified carbon screen-printed electrodes

    International Nuclear Information System (INIS)

    Dominguez Renedo, Olga; Arcos Martinez, M. Julia

    2007-01-01

    Carbon screen-printed electrodes (CSPE) modified with gold nanoparticles present an interesting alternative in the determination of antimony using differential pulse anodic stripping voltammetry. Metallic gold nanoparticles deposits have been obtained by direct electrochemical deposition. Scanning electron microscopy measurements show that the electrochemically synthesized gold nanoparticles are deposited in aggregated form. Any undue effects caused by the presence of foreign ions in the solution were also analyzed to ensure that common interferents in the determination of antimony by ASV. The detection limit for Sb(III) obtained was 9.44 x 10 -10 M. In terms of reproducibility, the precision of the above mentioned method in %R.S.D. values was calculated at 2.69% (n = 10). The method was applied to determine levels of antimony in seawater samples and pharmaceutical preparations

  11. The learning machine in quantitative chemical analysis : Part I. Anodic Stripping Voltammetry of Cadmium, Lead and Thallium

    NARCIS (Netherlands)

    Bos, M.; Jasink, G.

    1978-01-01

    The linear learning machine method was applied to the determination of cadmium, lead and thallium down to 10-8 M by anodic stripping voltammetry at a hanging mercury drop electrode. With a total of three trained multicategory classifiers, concentrations of Cd, Pb and Tl could be predicted with an

  12. Functioning of antimony film electrode in acid media under cyclic and anodic stripping voltammetry conditions.

    Science.gov (United States)

    Sebez, Bine; Ogorevc, Bozidar; Hocevar, Samo B; Veber, Marjan

    2013-06-27

    New insights into the functioning, i.e. electrochemical behaviour and analytical performance, of in situ prepared antimony film electrodes (SbFEs) under square-wave anodic stripping (SW-ASV) and cyclic (CV) voltammetry conditions are presented by studying several key operational parameters using Pb(II), Cd(II) and Zn(II) as model analyte ions. Five different carbon- and metal-based substrate transducer electrodes revealed a clear advantage of the former ones while the concentration of the precursor Sb(III) ion exhibited a distinct influence on the ASV functioning of the SbFE. Among six acids examined as potential supporting electrolytes the HNO3 was demonstrated to yield nearly identical results in conducting ASV experiments with SbFE as so far almost exclusively used HCl. This is extremely important as HNO3 is commonly employed acidifying agent in trace metal analysis, especially in elemental mass spectrometry measurements. By carrying out a systematic CV and ASV investigation using a medium exchange protocol, we confirmed the formation of poorly soluble oxidized Sb species at the substrate electrode surface at the end of each stripping step, i.e. at the potentials beyond the anodic dissolution of the antimony film. Hence, the significance of the cleaning and initializing the surface of a substrate electrode after accomplishing a stripping step was thoroughly studied in order to find conditions for a complete removal of the adhered Sb-oxides and thus to assure a memory-free functioning of the in situ prepared SbFE. Finally, the practical analytical application of the proposed ASV method was successfully tested and evaluated by measuring the three metal analytes in ground (tap) and surface (river) water samples acidified with HNO3. Our results approved the appropriateness of the SbFE and the proposed method for measuring low μg L(-1) levels of some toxic metals, particularly taking into account the possibility of on-field testing and the use of low cost

  13. Anodic stripping voltammetry of gold nanoparticles at boron-doped diamond electrodes and its application in immunochromatographic strip tests.

    Science.gov (United States)

    Ivandini, Tribidasari A; Wicaksono, Wiyogo P; Saepudin, Endang; Rismetov, Bakhadir; Einaga, Yasuaki

    2015-03-01

    Anodic stripping voltammetry (ASV) of colloidal gold-nanoparticles (AuNPs) was investigated at boron-doped diamond (BDD) electrodes in 50 mM HClO4. A deposition time of 300 s at-0.2 V (vs. Ag/AgCl) was fixed as the condition for the ASV. The voltammograms showed oxidation peaks that could be attributed to the oxidation of gold. These oxidation peaks were then investigated for potential application in immunochromatographic strip tests for the selective and quantitative detection of melamine, in which AuNPs were used as the label for the antibody of melamine. Linear regression of the oxidation peak currents appeared in the concentration range from 0.05-0.6 μg/mL melamine standard, with an estimated LOD of 0.069 μg/mL and an average relative standard deviation of 8.0%. This indicated that the method could be considered as an alternative method for selective and quantitative immunochromatographic applications. The validity was examined by the measurements of melamine injected into milk samples, which showed good recovery percentages during the measurements. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Detection of trace levels of Pb2+ in tap water at boron-doped diamond electrodes with anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Dragoe, Diana; Spataru, Nicolae; Kawasaki, Ryuji; Manivannan, Ayyakkannu; Spataru, Tanta; Tryk, Donald A.; Fujishima, Akira

    2006-01-01

    Boron-doped diamond (BDD) electrodes were used to investigate the possibility of detecting trace levels of lead by linear-sweep anodic stripping voltammetry. The low limit of detection (2 nM) is an advantage compared to other electrode materials, and it was found that at low pH values, copper concentrations that are usually present in drinking water do not affect to a large extent the detection of lead. These findings recommend anodic stripping voltammetry at the BDD electrodes as a suitable mercury-free method for the determination of trace levels of lead in drinking water. The results obtained for the lead detection in tap water real samples are in excellent agreement with those found by inductively coupled plasma-mass spectrometry (ICP-MS), demonstrating the practical analytical utility of the method

  15. Anodic stripping voltammetry of synthesized CdS nanoparticles at boron-doped diamond electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, Mohammad; Ivandini, Tribidasari A., E-mail: ivandini.tri@sci.ui.ac.id; Saepudin, Endang [Department of Chemistry, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Einaga, Yasuaki [Department of Chemistry, Keio University (Japan)

    2016-04-19

    Cadmium sulphide (CdS) nanoparticles were chemically synthesized using reverse micelles microreactor methods. By using different washing treatments, UV-Vis spectroscopy showed that the absorption peaks appeared at 465 nm, 462 nm, 460 nm, and 459 nm respectively for CdS nanoparticles without and with 1, 2, and 3 times washing treatments using pure water. In comparison with the absorbance peak of bulk CdS at 512 nm, the shifted absorption peaks, indicates that the different sizes of CdS can be prepared. Anodic stripping voltammetry of the CdS nanoparticles was then studied at a boron-doped diamond electrode using 0.1 M KClO{sub 4} and 0.1 M HClO{sub 4} as the electrolytes. A scan rate of 100 mV/s with a deposition potential of -1000 mV (vs. Ag/AgCl) for 60 s at a potential scan from -1600 mV to +800 mV (vs. Ag/AgCl) was applied as the optimum condition of the measurements. Highly-accurate linear calibration curves (R{sup 2} = 0.99) in 0.1 M HClO{sub 4} with the sensitivity of 0.075 mA/mM and the limit of detection of 81 µM in 0.1 M HClO{sub 4} can be achieved, which is promising for an application of CdS nanoparticles as a label for biosensors.

  16. Investigations on the use of anodic stripping voltammetry for the analyses of lead in saline environments

    Energy Technology Data Exchange (ETDEWEB)

    Case, C.W.

    1978-08-01

    Research is reported directed to modification of the anodic stripping voltammetry (ASV) analytic method in order to acquire data for lead from ambient sea water conditions, and development of a chemical model which uses these data to identify inorganic lead species for saline environments. Laboratory and field samples were analyzed for lead partitioning in: (a) KCl electrolyte solutions; (b) I.A.P.S.O. Standard Sea Water; (c) seawater samples from Quatsino Sound, British Columbia; (d) a series of seawater samples from San Francisco Bay; and (e) seawater samples from the Gulf of Mexico. The electrochemical traits of the lead species and the ASV oxidation potential expression are the fundamental constituents of the chemical model. The model uses the data from the analyses to provide the mass balance relationships for lead partitioned among the major anions in seawater. The laboratory analyses of KCl electrolyte and Standard Seawater give the following results. The modified ASV method and chemical model provide information on ambient labile and non-labile inorganic lead complexes in these saline solutions down to the parts-per-billion level. No purge and the simple electrodes cause some erratic behavior and spurious potentials, but the data are reproducible. In addition to Pb/sup 2 +/, the most dominant measured lead species in order include PbCO/sub 3//sup 0/, PbSO/sub 4//sup 0/, PbCl/sup +/, and Pb(NO/sub 3/)/sub 2//sup 0/ from the lead additions solution. The analyses of the field samples give the following results. Samples were taken from the partially anoxic basin in Quatsino Sound, British Columbia with one successful analysis which is for somewhat normal dissolved oxygen conditions. Data show that lead is partitioned among Pb/sup 2 +/, Pb(OH)/sub 2//sup 0/, PbCO/sub 3//sup 0/, and PbSO/sub 4//sup 0/. The analyses with purge for the San Francisco Bay water partitions lead among Pb/sup 2 +/, PbCO/sub 3//sup 0/, PbSO/sub 4//sup 0/, PbCl/sup +/, and Pb

  17. Nafion/2,2'-bipyridyl-modified bismuth film electrode for anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Torma, Ferenc; Kadar, Mihaly; Toth, Klara; Tatar, Eniko

    2008-01-01

    This paper describes the fabrication, characterisation and the application of a Nafion/2,2'-bipyridyl/bismuth composite film-coated glassy carbon electrode (NC(Bpy)BiFE) for the anodic stripping voltammetric determination of trace metal ions (Zn 2+ , Cd 2+ and Pb 2+ ). The NC(Bpy)BiFE electrode is prepared by first applying a 2.5 mm 3 drop of a coating solution containing 0.5 wt% Nafion and 0.1% (w/v) 2,2'-bipyridil (Bpy) onto the surface of a glassy carbon electrode, while the Bi film was plated in situ simultaneously with the target metal ions at -1.4 V. The main advantage of the polymer coated bismuth film electrode is that the sensitivity of the stripping responses is increased considerably due to the incorporation of the neutral chelating agent of 2,2'-bipyridyl (Bpy) in the Nafion film, while the Nafion coating improved the mechanical stability of the bismuth film and its resistance to the interference of surfactants. The key experimental parameters relevant to both the electrode fabrication and the voltammetric measurement were optimized on the basis of the stripping signals. With a 2 min deposition time in the presence of oxygen, linear calibration curves were obtained in a wide concentration range (about 2-0.001 μM) with detection limits of 8.6 nM (0.56 μg dm -3 ) for Zn 2+ , 1.1 nM (0.12 μg dm -3 ) for Cd 2+ and 0.37 nM (0.077 μg dm -3 ) for Pb 2+ . For nine successive preconcentration/determination/electrode renewal experiments the standard deviations were between 3 and 5% at 1.2 μM for zinc and 0.3-0.3 μM concentration level for lead and cadmium, respectively, and the method exhibited excellent selectivity in the presence of the excess of several potential interfering metal ions. The analytical utility of the stripping voltammetric method elaborated was tested in the assay of heavy metals in some real samples and the method was validated by ICP-MS technique

  18. Determination of Traces of Pb, Cu and Cd in Seawater around Thane Creek by Anodic Stripping Voltammetry Method.

    Science.gov (United States)

    Maity, Sukanta; Sahu, S K; Pandit, G G

    2017-04-01

    Trace metals (Pb, Cu and Cd) in seawater samples were pre-concentrated for the simultaneous quantitative determination using solvent extraction procedure in the presence of ammonium pyrrolidine dithiocarbamate (APDC) as complexing agent and methyl isobutyl ketone (MIBK) as organic phase and acid exchange back - extraction followed by its determination by Differential Pulse Anodic Stripping Voltammetry (DPASV). Concentrations of Pb, Cu and Cd vary from 3.0 to 9.44 ng/mL, 12.7 to 28.6 ng/mL and 0.31 to 1.21 ng/mL respectively in seawater samples collected from different locations across Thane Creek area, Mumbai, India. Pb, Cu, Cd concentration were observed to be higher in the eastern side of the Thane Creek as it is covered by various industries.

  19. Electrochemical Performances of Diamond Like Carbon Films for Pb(II) Detection in Tap Water Using Differential Pulse Anodic Stripping Voltammetry Technique

    Czech Academy of Sciences Publication Activity Database

    Sbartai, A.; Namour, F.; Barbier, F.; Krejčí, J.; Kučerová, R.; Krejčí, T.; Neděla, Vilém; Sobota, Jaroslav; Jaffrezic-Renault, N.

    2013-01-01

    Roč. 11, č. 8 (2013), s. 1524-1529 ISSN 1546-198X Institutional support: RVO:68081731 Keywords : Diamond Like Carbon DLC * Lead Detection * Differential Pulse Anodic Stripping * Voltammetry * Tap Water Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.558, year: 2013

  20. The detection of Cd and Pb in soil solution by differential pulse anodic stripping voltammetry

    Czech Academy of Sciences Publication Activity Database

    Jakl, M.; Jaklová Dytrtová, J.; Šestáková, Ivana; Szaková, J.; Tlustoš, P.

    2008-01-01

    Roč. 102, - (2008), s. 99-100 E-ISSN 1213-7103. [International Conference on Electroanalysis /12./. 16.06.2008-19.06.2008, Prague] R&D Projects: GA ČR GA521/06/0496 Institutional research plan: CEZ:AV0Z40400503 Keywords : heavy metals * voltammetry Subject RIV: CG - Electrochemistry

  1. Low-level determination of silicon in steels by anodic stripping voltammetry on a hanging mercury drop electrode.

    Science.gov (United States)

    Rahier, A H; Lunardi, S; Nicolle, F; George, S M

    2010-10-15

    The sensitive differential pulse anodic stripping voltammetry (DPASV) proposed originally by Ishiyama et al. (2001) has been revised and improved to allow the accurate measurement of silicon on a hanging mercury drop electrode (HMDE) instead of a glassy carbon electrode. We assessed the rate of formation of the partially reduced β-silicododecamolybdate and found that metallic mercury promotes the reaction in the presence of a large concentration of Fe(3+). The scope of the method has been broadened by carrying out the measurements in the presence of a constant amount of Fe(3+). The limit of detection (LOD) of the method described in the present paper is 100 μg Sig(-1) of steel, with a relative precision ranging from 5% to 12%. It can be further enhanced to 700 ng Sig(-1) of steel provided the weight of the sample, the dilution factors, the duration of the electrolysis and the ballast of iron are adequately revised. The tolerance to several interfering species has been examined, especially regarding Al(3+), Cr(3+) and Cr VI species. The method was validated using four low-alloy ferritic steels certified by the National Institute of Standards and Technology (NIST). Its application to nickel base alloys as well as to less complicated matrixes is straightforward. It has also been successfully applied to the determination of free silicon into silicon carbide nano-powder. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Preparation and Evaluation of Acetabularia-Modified Carbon Paste Electrode in Anodic Stripping Voltammetry of Copper and Lead Ions

    Directory of Open Access Journals (Sweden)

    Muhammad Raziq Rahimi Kooh

    2013-01-01

    Full Text Available Seaweed is well known about for potential in chelating heavy metals. In this study, carbon paste electrodes were fabricated with siphonous seaweed Acetabularia acetabulum as the modifiers to sense lead (II and copper (II by square-wave anodic stripping voltammetry. Various scan rates and deposition potentials were measured to obtain the optimal peak current for Pb(II and Cu(II. Optimum conditions of Acetabularia-CPE for sensing Pb(II were at the scan rate of 75 mV/s and deposition potential of −800 mV, while for Cu(II sensing were at 100 mV/s and −300 mV, respectively. The electrodes were characterized by the duration of accumulation time, preconcentration over a range of standards, supporting electrolyte, and standard solutions of various pH values. Interference studies were carried out. Both Zn(II and Cu(II were found to interfere with Pb(II sensing, whereas only Zn(II causes interference with Cu(II sensing. The electrode was found to have good regeneration ability via electrochemical cleaning. Preliminary testing of complex samples such as NPK fertilisers, black soil, and sea salt samples was included.

  3. Trace metal characterization and speciation in geothermal effluent by multiple scanning anodic stripping voltammetry and atomic absorption analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, B.R.

    1979-05-25

    Recent studies have shown geothermal power plants to have a significant environmental impact on the ground water of the area. The heavy metals arsenic and mercury are special problems, as both are concentrated by flora and fauna exposed to the effluent waters. Because the toxicity of these and other metallic pollutants present in geothermal effluent depends on the chemical form, or speciation, of the particular metal, any serious study of the environmental impact of a geothermal development should include studies of trace metal speciation, in addition to trace metal concentration. This proposal details a method for determining metal speciation in dilute waters. The method is based on ion-exchange and backed by atomic absorption spectrometry and multiple scanning anodic stripping voltammetry. Special laboratory studies will be performed on mercury, arsenic and selenium speciation in synthetic geothermal water. The method will be applied to three known geothermal areas in Washington and Oregon, with emphasis on the speciation of mercury, arsenic and selenium in these waters. The computer controlled electrochemical instrumentation was built and tested. Using this instrumentation, a new experimental procedure was developed to determine the chemical form (speciation) of metal ions in very dilute solutions (ng/ml). This method was tested on model systems including Pb, Cd, and As with C1/sup -/, CO/sub 3//sup 2 -/ and glycine ligands. Finally, the speciation of lead in a geothermal water was examined and the PbC1/sup +/ complex was observed and quantified.

  4. Determination of Antimony (III in Real Samples by Anodic Stripping Voltammetry Using a Mercury Film Screen-Printed Electrode

    Directory of Open Access Journals (Sweden)

    Olga Domínguez-Renedo

    2009-01-01

    Full Text Available This paper describes a procedure for the determination of antimony (III by differential pulse anodic stripping voltammetry using a mercury film screen-printed electrode as the working electrode. The procedure has been optimized using experimental design methodology. Under these conditions, in terms of Residual Standard Deviation (RSD, the repeatability (3.81 % and the reproducibility (5.07 % of the constructed electrodes were both analyzed. The detection limit for Sb (III was calculated at a value of 1.27×10–8 M. The linear range obtained was between 0.99 × 10–8 – 8.26 × 10–8 M. An analysis of possible effects due to the presence of foreign ions in the solution was performed and the procedure was successfully applied to the determination of antimony levels in pharmaceutical preparations and sea water samples.

  5. Application of Box-Behnken designs in parameters optimization of differential pulse anodic stripping voltammetry for lead(II) determination in two electrolytes.

    Science.gov (United States)

    Yu, Xiao-Lan; He, Yong

    2017-06-05

    Box-Behnken design was advantageous to parameters optimization of differential pulse anodic stripping voltammetry (DPASV) for the analysis of lead(II) with its high efficiency and accuracy. Five Box-Behnken designs were designed and conducted in the electrolyte of 0.1 mol/L acetate buffer and 0.1 mol/L HCl without the removal of oxygen. Significant parameters and interactions in each electrolyte were found (P-value Box-Behnken designs in parameters optimization of DPASV for lead(II) determination regardless of the electrolyte kinds.

  6. Trace analysis of Cd, Cu, Pb and Zn in various materials using differential pulse anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Ahmed, R.; Viqar-un-Nisa; Tanwir, R.

    1988-09-01

    Sampling and sample preparation methods have been described. Digestion methods for different types of materials and acid purification systems have been developed. For trace analysis purposes cleaning methods for glassware etc. have been described. Differential pulse anodic stripping voltametric (DPASV) method has been worked out for the trace analysis of zn, cd, pb and Cu in different types of materials. Linearity of the method has been checked by drawing concentration versus currents (peak height) curves. Precision of the method has been checked by analysing a number of actual samples. of the method has been verified by analysing standards of U.S.A. Comparative studies have been done between Differential pulse anodic stripping voltammetric method and Atomic Absorption spectroscopic method. Problems of contamination and systematic errors during trace and ultra-trace analysis have been discussed. A variety of samples including soil, spinach, wheat flour, rice flour, dry milk, coriander, kidney stones, bladder stones etc. have been analysed and preliminary results have been reported. (author)

  7. Functionalized Nanoporous Track-Etched b-PVDF Membrane Electrodes for Heavy Metal Determination by Square-Wave Anodic Stripping Voltammetry

    Directory of Open Access Journals (Sweden)

    Bessbousse H.

    2013-04-01

    Full Text Available Track-etched functionalized nanoporous β-PVDF membrane electrodes, or functionalized membrane electrodes (FMEs, are electrodes made from track-etched, poly(acrylic acid (PAA functionalized nanoporous β-poly(vinylidene fluoride (β-PVDF membranes with thin porous Au films sputtered on each side as electrodes. To form the β-PVDF nanoporous membranes, β-PVDF films are irradiated by swift heavy ions. After irradiation, radical tracks are stable in the membranes. Chemical etching removes some of the radical tracks revealing nanopores. Radicals, remaining in the pores, initiate radio grafting of PAA from the pore walls of the nanoporous β-PVDF. PAA is a cation exchange polymer that adsorbs metal ions, such as Pb2+, from aqueous solutions thus concentrating the ions into the membrane. After a calibrated time the FME is transferred to an electrochemical cell for square-wave anodic stripping voltammetry analysis.

  8. Determination of Cd2+ and Pb2+ Based on Mesoporous Carbon Nitride/Self-Doped Polyaniline Nanofibers and Square Wave Anodic Stripping Voltammetry

    Directory of Open Access Journals (Sweden)

    Chang Zhang

    2016-01-01

    Full Text Available The fabrication and evaluation of a glassy carbon electrode (GCE modified with self-doped polyaniline nanofibers (SPAN/mesoporous carbon nitride (MCN and bismuth for simultaneous determination of trace Cd2+ and Pb2+ by square wave anodic stripping voltammetry (SWASV are presented here. The morphology properties of SPAN and MCN were characterized by transmission electron microscopy (TEM, and the electrochemical properties of the fabricated electrode were characterized by cyclic voltammetry (CV. Experimental parameters, such as deposition time, pulse potential, step potential, bismuth concentration and NaCl concentration, were optimized. Under the optimum conditions, the fabricated electrode exhibited linear calibration curves ranging from 5 to 80 nM for Cd2+ and Pb2+. The limits of detection (LOD were 0.7 nM for Cd2+ and 0.2 nM for Pb2+ (S/N = 3. Additionally, the repeatability, reproducibility, anti-interference ability and application were also investigated, and the proposed electrode exhibited excellent performance. The proposed method could be extended for other heavy metal determination.

  9. Anodic stripping voltammetry with gold electrodes as an alternative method for the routine determination of mercury in fish. Comparison with spectroscopic approaches.

    Science.gov (United States)

    Giacomino, Agnese; Ruo Redda, Andrea; Squadrone, Stefania; Rizzi, Marco; Abete, Maria Cesarina; La Gioia, Carmela; Toniolo, Rosanna; Abollino, Ornella; Malandrino, Mery

    2017-04-15

    The applicability to the determination of mercury in tuna of square wave anodic stripping voltammetry (SW-ASV) conducted at both solid gold electrode (SGE) and a gold nanoparticle-modified glassy carbon electrode (AuNPs-GCE) was demonstrated. Mercury content in two certified materials and in ten samples of canned tuna was measured. The performances of the electrodes were compared with one another as well as with two spectroscopic techniques, namely cold vapour atomic absorption spectroscopy (CV-AAS) and a direct mercury analyser (DMA). The results found pointed out that both SW-ASV approaches were suitable and easy-to-use method to monitor mercury concentration in tunas, since they allowed accurate quantification at concentration values lower than the maximum admissible level in this matrix ([Hg]=1mg/kg wet weight,ww ). In particular, mercury detection at the AuNPs-GCE showed a LOQ in fish-matrix of 0.1μg/l, corresponding to 0.06mg/kg ww , with performance comparable to that of DMA. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Determination of vitamin E in margarines and edible oils using square wave anodic stripping voltammetry with a glassy carbon paste electrode.

    Science.gov (United States)

    Sýs, Milan; Švecová, Blanka; Švancara, Ivan; Metelka, Radovan

    2017-08-15

    A new electroanalytical method for determination of vitamin E in the form of the total content of tocopherols present in margarines and edible oils has been developed. The method is based on extraction of these biologically active compounds into silicone oil, acting as lipophilic binder of glassy carbon paste electrode, with subsequent electrochemical detection by square wave anodic stripping voltammetry (SWASV) in 0.1M HNO 3 . The values of vitamin E contents were expressed as mass equivalent of α-tocopherol known as the most active form of this lipophilic vitamin. The linear ranges for α-tocopherol determination were 5×10 -7 -4×10 -5 and 5×10 -8 -1×10 -5 molL -1 with the detection limits of 1×10 -7 and 3.3×10 -9 molL -1 for 5 and 15min accumulation, respectively. The results have shown that SWASV with extraction step is very sensitive method for the determination of vitamin E, being comparable to reversed-phase high performance liquid chromatography chosen as reference method. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Determination of trace heavy metals in herbs by sequential injection analysis-anodic stripping voltammetry using screen-printed carbon nanotubes electrodes

    International Nuclear Information System (INIS)

    Injang, Uthaitip; Noyrod, Peeyanun; Siangproh, Weena; Dungchai, Wijitar; Motomizu, Shoji; Chailapakul, Orawon

    2010-01-01

    A method for the simultaneous determination of Pb(II), Cd(II), and Zn(II) at low μg L -1 concentration levels by sequential injection analysis-anodic stripping voltammetry (SIA-ASV) using screen-printed carbon nanotubes electrodes (SPCNTE) was developed. A bismuth film was prepared by in situ plating of bismuth on the screen-printed carbon nanotubes electrode. Operational parameters such as ratio of carbon nanotubes to carbon ink, bismuth concentration, deposition time and flow rate during preconcentration step were optimized. Under the optimal conditions, the linear ranges were found to be 2-100 μg L -1 for Pb(II) and Cd(II), and 12-100 μg L -1 for Zn(II). The limits of detection (S bl /S = 3) were 0.2 μg L -1 for Pb(II), 0.8 μg L -1 for Cd(II) and 11 μg L -1 for Zn(II). The measurement frequency was found to be 10-15 stripping cycle h -1 . The present method offers high sensitivity and high throughput for on-line monitoring of trace heavy metals. The practical utility of our method was also demonstrated with the determination of Pb(II), Cd(II), and Zn(II) by spiking procedure in herb samples. Our methodology produced results that were correlated with ICP-AES data. Therefore, we propose a method that can be used for the automatic and sensitive evaluation of heavy metals contaminated in herb items.

  12. Determination of trace amounts of indium in some sediments by means of coprecipitation with zirconium hydroxide and differential pulse anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Yoshimura, Wataru; Uzawa, Atushi; Hong Luxin.

    1994-01-01

    Indium in some sediments was determined by means of coprecipitation and differential pulse anodic stripping voltammetry. The analytical procedure was as follows. Fifty milliliters of distilled water is added to 10 ml of sample solution containing 0.04 g of sediment. Then, constant amounts of indium standard solution and 1 ml of zirconium oxychloride solution are added and the pH adjusted to 8.8 with ammonia water (1:2). The precipitate is separated by filtration and then dissolved in 25 ml of 4 M hydrochloric acid. After 1 ml of 5% KCNS solution is added, this solution is diluted to 50 ml with distilled water. A portion of this solution is employed for the determination of indium. After bubbling nitrogen gas through the sample solution for 100 s it was pre-electrolyzed for 100 s. The potential was scanned from -0.9 V to -0.3 Vυs. SCE for dissolution of indium ion. Indium ion was determined from the peak current of the voltammogram. The results are as follows: (1) Zirconium hydroxide was the most effective collector of indium when the pH was adjusted to 8.8 with ammonia water (1:2). (2) Iron (III) and cadmium ions were found to interfere with the determination of indium. (3) The analytical procedure took about 90 min and 0.01 ppm of indium in sample solution could be determined. (4) This method is applicable to the determination of indium in river bottom and sea floor sediment. (author)

  13. 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.

  14. O modelamento estatístico de misturas: experimento tutorial usando voltametria de redissolução anódica Statistical modeling of mixtures: a tutorial experiment using anodic stripping voltammetry

    Directory of Open Access Journals (Sweden)

    Aline Renée Coscione

    2005-12-01

    Full Text Available This work illustrates the modeling procedure for a solvent mixture using the simplex- centroid approach. The selected experiment was the optimization of the peak current observed in the direct determination of nickel by anodic stripping voltammetry (ASV in a solvent mixture composed of N,N-dimethylformamide, ethanol and water. The text is presented in a tutorial way, showing in detail the several steps which must be followed in such a process. Since not all possible mixtures lead to a measurable instrumental response, pseudocomponents had to be used to rescale the experimental design. This also allows to show how to apply this tool, usually troublesome for non-specialists in mixture modeling procedures.

  15. Direct Quantification of Cd2+in the Presence of Cu2+by a Combination of Anodic Stripping Voltammetry Using a Bi-Film-Modified Glassy Carbon Electrode and an Artificial Neural Network.

    Science.gov (United States)

    Zhao, Guo; Wang, Hui; Liu, Gang

    2017-07-03

    Abstract : In this study, a novel method based on a Bi/glassy carbon electrode (Bi/GCE) for quantitatively and directly detecting Cd 2+ in the presence of Cu 2+ without further electrode modifications by combining square-wave anodic stripping voltammetry (SWASV) and a back-propagation artificial neural network (BP-ANN) has been proposed. The influence of the Cu 2+ concentration on the stripping response to Cd 2+ was studied. In addition, the effect of the ferrocyanide concentration on the SWASV detection of Cd 2+ in the presence of Cu 2+ was investigated. A BP-ANN with two inputs and one output was used to establish the nonlinear relationship between the concentration of Cd 2+ and the stripping peak currents of Cu 2+ and Cd 2+ . The factors affecting the SWASV detection of Cd 2+ and the key parameters of the BP-ANN were optimized. Moreover, the direct calibration model (i.e., adding 0.1 mM ferrocyanide before detection), the BP-ANN model and other prediction models were compared to verify the prediction performance of these models in terms of their mean absolute errors (MAEs), root mean square errors (RMSEs) and correlation coefficients. The BP-ANN model exhibited higher prediction accuracy than the direct calibration model and the other prediction models. Finally, the proposed method was used to detect Cd 2+ in soil samples with satisfactory results.

  16. Application of different methodologies in the preparation of organic matrices for determination of trace elements by differential pulse anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Sisti, Cristina

    2001-01-01

    The determination of trace elements in food samples is of great importance for the human health, considering the factors of essentiality and toxicity. On the other hand, the chemical analysis is largely affected for the steps of sample preparation; laboratory contamination of the sample and the reagents or still volatilization and losses of the elements. If these parameters are not controlled the achieved precision and accuracy could be low. In this work, the content of zinc, cadmium, lead and copper was determined in adults diet samples collected by duplicate portion technique and bovine liver, applying the differential pulse anodic stripping voltametry - (DP-ASV) technique. In the digestion of the matrices in acid medium, conventional methodologies were used, conductive heating in open recipients and equipment with microwaves source in open and closed vessels. The best procedure was the sample digestion by microwaves, in closed vessels and the other treatments made in controlled atmosphere with hood laminar-airflow class 100. The established methodology was validated with the use of a certified sample as reference (NIST - bovine liver 1577b). (author)

  17. Optimising carbon electrode materials for adsorptive stripping voltammetry

    OpenAIRE

    Chaisiwamongkhol, K; Batchelor-McAuley, C; Sokolov, S; Holter, J; Young, N; Compton, R

    2017-01-01

    Different types of carbon electrode materials for adsorptive stripping voltammetry are studied through the use of cyclic voltammetry. Capsaicin is utilised as a model compound for adsorptive stripping voltammetry using unmodified and modified basal plane pyrolytic graphite (BPPG) electrodes modified with multi-walled carbon nanotubes, carbon black or graphene nanoplatelets, screen printed carbon electrodes (SPE), carbon nanotube modified screen printed electrodes, and carbon paste electrodes....

  18. Practical measurement of silicon in low alloy steels by differential pulse stripping voltammetry

    International Nuclear Information System (INIS)

    Rahier, A.; Lunardi, S.; Triki, C.

    2005-01-01

    A sensitive differential pulse anodic stripping voltammetry has been adapted to allow the determination of Si in low-alloy steels using a hanging mercury drop electrode. The method has been qualified using certified ASTM standards and is now running in routine. The present report describes the experimental details, thereby allowing the reader to carry out the measurements precisely. (author)

  19. Application of silica fume as a new SP-extractor for trace determination of Zn(II) and Cd(II) in pharmaceutical and environmental samples by square-wave anodic stripping voltammetry

    Science.gov (United States)

    Ahmed, Salwa A.; Gaber, Ahmed A. Abdel; Rahim, Asmaa M. Abdel

    2017-05-01

    In this work, silica fume (SF) is used as a solid-phase extractor for extraction of Zn(II) and Cd(II) from aqueous solutions. Characterization of SF is performed by Fourier transform infrared, X-ray diffraction, transmission and scanning electron microscopy. The optimum experimental conditions for the two metal ions are investigated using batch and column techniques. The maximum adsorption capacity values are found to be 54.13 and 121.28 mg g-1 at the optimum pH 6.0 and 8.0 for Zn(II) and Cd(II), respectively. The equilibrium data are analyzed using the Langmuir, Freundlich, and Temkin isotherms by nonlinear regression analysis. Also, the kinetics analysis revealed that the overall adsorption process is successfully fitted with the pseudo-second-order model. The method is applied for determination of the target metal ions in pharmaceutical and environmental samples using square-wave anodic stripping voltammetry. The limit of detection (LOD) values are 0.102 and 1.43 × 10-3 mg L-1 for Zn(II) and Cd(II), respectively. The percentage recovery values are 98.8-100.5 % which indicate the success of the proposed method for determination of Zn(II) and Cd(II) without interfering effects.

  20. The determination, by differential pulse anodic-stripping voltammetry at the thin mercury-film electrode, of cadmium and thallium in six NIMROC reference materials

    International Nuclear Information System (INIS)

    Lee, A.F.

    1981-01-01

    A previously reported procedure has been extended to include the determination of thallium. In samples where thallium occurred in the presence of relatively high concentrations of cadmium, the stripping peak for cadmium was first suppressed with non-ionic surface-active agent, Triton X-100. Cadmium and thallium were determined directly in six NIMROC reference materials without interference from iron(III), in a reducing electrolyte, which is also a complexing agent, consisting of 1 M ammonium chloride, 0,1 M citric acid, and 0,025 M ascorbic acid. Interelement interferences were eliminated by the use of a mercury-film electrode of adequate thickness. The limits of detection for cadmium were 10ng/g and those for thallium 20ng/g

  1. Microanalysis of DNA by stripping transfer voltammetry

    Czech Academy of Sciences Publication Activity Database

    Jelen, František; Kouřilová, Alena; Pečinka, Petr; Paleček, Emil

    2004-01-01

    Roč. 63, 1-2 (2004), s. 249-252 ISSN 1567-5394 R&D Projects: GA ČR GA203/02/0422; GA AV ČR IAA1163201; GA AV ČR IBS5004107 Institutional research plan: CEZ:AV0Z5004920 Keywords : DNA determination * determination of purine base s * linear sweep voltammetry Subject RIV: BO - Biophysics Impact factor: 2.261, year: 2004

  2. Linear sweep anodic stripping voltammetry: Determination of ...

    Indian Academy of Sciences (India)

    Abstract. A highly sensitive electrochemical sensor has been constructed for determination of Cr(VI) with the lowest limit of detection (LOD) reported to date using gold nanoparticles (AuNPs) modified screen-printed electrode (SPE). The modification of SPE by casting pure AuNPs increases the sensitivity for detection of.

  3. Linear sweep anodic stripping voltammetry: Determination of ...

    Indian Academy of Sciences (India)

    –18 Gold nanoparticles pos- ... trode for improving sensitivity and low memory loss. Cr(VI) is reduced on SPE-AuNPs to form chromium ... peak current after background subtraction at 0.05 V. 3. Results and Discussion. 3.1 Characterization of ...

  4. 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.

  5. A Hyphenation of Stripping Voltammetry with Electrospray Ionization Mass Spectrometry; an Effect of Sodium Perchlorate on Ferrocene Oxidation

    Czech Academy of Sciences Publication Activity Database

    Jaklová Dytrtová, Jana; Jakl, M.; Navrátil, Tomáš; Schröder, Detlef

    2013-01-01

    Roč. 8, č. 2 (2013), s. 1623-1634 ISSN 1452-3981 R&D Projects: GA ČR GAP206/11/1638 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : ESI-MS * anodic stripping voltammetry * electrochemistry * ferrocene * ferricene * base electrolyte Subject RIV: CG - Electrochemistry Impact factor: 1.956, year: 2013

  6. Application of different methodologies in the preparation of organic matrices for determination of trace elements by differential pulse anodic stripping voltammetry; Aplicacao de diferentes metodologias na preparacao de matrizes organicas para a determinacao voltametrica de elementos traco

    Energy Technology Data Exchange (ETDEWEB)

    Sisti, Cristina

    2001-07-01

    The determination of trace elements in food samples is of great importance for the human health, considering the factors of essentiality and toxicity. On the other hand, the chemical analysis is largely affected for the steps of sample preparation; laboratory contamination of the sample and the reagents or still volatilization and losses of the elements. If these parameters are not controlled the achieved precision and accuracy could be low. In this work, the content of zinc, cadmium, lead and copper was determined in adults diet samples collected by duplicate portion technique and bovine liver, applying the differential pulse anodic stripping voltametry - (DP-ASV) technique. In the digestion of the matrices in acid medium, conventional methodologies were used, conductive heating in open recipients and equipment with microwaves source in open and closed vessels. The best procedure was the sample digestion by microwaves, in closed vessels and the other treatments made in controlled atmosphere with hood laminar-airflow class 100. The established methodology was validated with the use of a certified sample as reference (NIST - bovine liver 1577b). (author)

  7. Application of Stripping Voltammetry for the Determination of Cadmium, Lead, Copper and Zinc in Yemani soils and Vegetables

    OpenAIRE

    Matloob, Mohammed H.; Al Joufi, Abdulsalam M.; Al Badani, Abdu Ali S.; Aqlan, Essam M. K.

    2004-01-01

    Heavy metals contents in the solutions from acid digestion of Yemeni soils and vegetables were deter¬mined by differential pulsed anodic stripping voltammetry. The geometric mean for Cd, Pb, Cu and Zn concentrations for the soils (to a depth of 40 cm) were 0.56, 9.4, 35 and 58 mg kg"1 dry weight respec¬tively. These levels are closely related to the literature values for uncontaminated soils. Highest and low¬est concentrations of Cd were in watercress and cucumber (37.6 and 2.6|j.g kg"1, resp...

  8. Determination of trace mercury in water based on N-octylpyridinium ionic liquids preconcentration and stripping voltammetry.

    Science.gov (United States)

    Li, Zhenhan; Xia, Shanhong; Wang, Jinfen; Bian, Chao; Tong, Jianhua

    2016-01-15

    A novel method for determination of trace mercury in water is developed. The method is performed by extracting mercury firstly with ionic liquids (ILs) and then detecting the concentration of mercury in organic media with anodic stripping voltammetry. Liquid-liquid extraction of mercury(II) ions by four ionic liquids with N-octylpyridinium cations ([OPy](+)) was studied. N-octylpyridinium tetrafluoroborate and N-octylpyridinium trifluoromethylsulfonate were found to be efficient and selective extractant for mercury. Temperature controlled dispersive liquid phase microextraction (TC-DLPME) technique was utilized to improve the performance of preconcentration. After extraction, precipitated IL was diluted by acetonitrile buffer and mercury was detected by differential pulse stripping voltammetry (DPSV) with gold disc electrode. Mercury was enriched by 17 times while interfering ions were reduced by two orders of magnitude in the organic media under optimum condition. Sensitivity and selectivity for electrochemical determination of mercury were improved by using the proposed method. Tap, pond and waste water samples were analyzed with recoveries ranging from 81% to 107% and detection limit of 0.05 μg/L. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Bismuth-based electrochemical stripping analysis

    Science.gov (United States)

    Wang, Joseph

    2004-01-27

    Method and apparatus for trace metal detection and analysis using bismuth-coated electrodes and electrochemical stripping analysis. Both anodic stripping voltammetry and adsorptive stripping analysis may be employed.

  10. Determination of nanogram quantities of osmium-labeled single stranded DNA by differential pulse stripping voltammetry

    Czech Academy of Sciences Publication Activity Database

    Kizek, René; Havran, Luděk; Fojta, Miroslav; Paleček, Emil

    2002-01-01

    Roč. 55, 1/2 (2002), s. 199-121 ISSN 1567-5394 R&D Projects: GA ČR GV204/97/K084; GA ČR GA204/00/D049; GA AV ČR IAA4004108 Institutional research plan: CEZ:AV0Z5004920 Keywords : differential pulse stripping voltammetry * microdetermination of DNA * chemical modification of DNA Subject RIV: BO - Biophysics Impact factor: 1.463, year: 2002

  11. 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.

  12. The Graphene/l-Cysteine/Gold-Modified Electrode for the Differential Pulse Stripping Voltammetry Detection of Trace Levels of Cadmium

    Directory of Open Access Journals (Sweden)

    Yu Song

    2016-06-01

    Full Text Available Cadmium(II is a common water pollutant with high toxicity. It is of significant importance for detecting aqueous contaminants accurately, as these contaminants are harmful to human health and environment. This paper describes the fabrication, characterization, and application of an environment-friendly graphene (Gr/l-cysteine/gold electrode to detect trace levels of cadmium (Cd by differential pulse stripping voltammetry (DPSV. The influence of hydrogen overflow was decreased and the current response was enhanced because the modified graphene extended the potential range of the electrode. The Gr/l-cysteine/gold electrode showed high electrochemical conductivity, producing a marked increase in anodic peak currents (vs. the glass carbon electrode (GCE and boron-doped diamond (BDD electrode. The calculated detection limits are 1.15, 0.30, and 1.42 µg/L, and the sensitivities go up to 0.18, 21.69, and 152.0 nA·mm−2·µg−1·L for, respectively, the BDD electrode, the GCE, and the Gr/l-cysteine/gold electrode. It was shown that the Gr/l-cysteine/gold-modified electrode is an effective means for obtaining highly selective and sensitive electrodes to detect trace levels of cadmium.

  13. Determination of Lamotrigine in Pharmaceutical Preparations by Adsorptive Stripping Voltammetry Using Screen Printed Electrodes

    Directory of Open Access Journals (Sweden)

    M. Julia Arcos-Martínez

    2008-07-01

    Full Text Available This paper describes a procedure that has been optimized for the determination of lamotrigine by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV using carbon screen-printed electrodes (CSPE and mercury coated carbon screen-printed electrodes. Selection of the experimental parameters was made using experimental design methodology. The detection limit found was 5.0 x 10-6 M and 2.0 x 10-6 M for the non modified and Hg modified CSPE, respectively. In terms of reproducibility, the precision of the above mentioned methods was calculated in %RSD values at 9.83% for CSPE and 2.73% for Hg-CSPE. The Hg-coated CSPEs developed in this work were successfully applied in the determination of lamotrigine in pharmaceutical preparations.

  14. Electrochemistry and analytical determination of lysergic acid diethylamide (LSD) via adsorptive stripping voltammetry.

    Science.gov (United States)

    Merli, Daniele; Zamboni, Daniele; Protti, Stefano; Pesavento, Maria; Profumo, Antonella

    2014-12-01

    Lysergic acid diethylamide (LSD) is hardly detectable and quantifiable in biological samples because of its low active dose. Although several analytical tests are available, routine analysis of this drug is rarely performed. In this article, we report a simple and accurate method for the determination of LSD, based on adsorptive stripping voltammetry in DMF/tetrabutylammonium perchlorate, with a linear range of 1-90 ng L(-1) for deposition times of 50s. LOD of 1.4 ng L(-1) and LOQ of 4.3 ng L(-1) were found. The method can be also applied to biological samples after a simple extraction with 1-chlorobutane. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Comparison of adsorptive with extractive stripping voltammetry in electrochemical determination of retinol

    Directory of Open Access Journals (Sweden)

    Milan Sýs

    2017-01-01

    Full Text Available Adsorptive stripping voltammetry (AdSV of retinol at solid glassy carbon electrode (GCE, carbon paste electrode (CPE covered by thin layer of multi-wall carbon nanotubes (CPE/MWCNTs and carbon paste electrode covered by thin layer of single layer graphene (CPE/Graphene was compared with an extractive stripping voltammetry (ExSV into silicone oil (SO as lipophilic binder of glassy carbon paste electrode (GCPE. All types of selected working electrodes were characterized by a scanning electron microscopy to determine overall morphology of electrode surfaces together with spatial arrangement of used carbon particles. The retinol, also known as vitamin A1, was chosen as a model analyte because it is the most biologically active representative of retinoids which are classified as a significant group of lipophilic vitamins. Based on this comparison, it was observed that electrochemical method with high sensitivity (ExSV at GPCE is generally characterized by shorter linear range of the calibration curve than in case of AdSV at CPE/MWCNTs or CPE/Graphene. Unlike AdSV at solid GCE, all other tested electrochemical methods could represent suitable analytical tools for monitoring of retinoids in different types of foodstuffs. Especially, content of retinol up to tenths milligrams can be easily determined using ExSV. Additionally, negative interference of chemical species present in real samples is minimal in comparison with direct voltammetric methods performed in supporting electrolytes based on organic solvents due to application of accumulation step in "ex-situ" mode.

  16. "Determination of domperidone in tablet dosage form by anodic differential pulse voltammetry".

    Science.gov (United States)

    Wahdan, Tarek; El-Ghany, Nadia Abd

    2005-10-01

    A differential pulse voltammetric method was described for the determination of domperidone. The method was based on the anodic oxidation of domperidone on a glassy carbon electrode at +0.64 V vs. SCE in Britton-Robinson buffer solution of pH 2.3. The reversibility of the oxidation was tested by cyclic voltammetry; the electrode process is irreversible and diffusion-adsorption controlled. Calibrations are linear over the range 1.0 x 10(-6)-2.0 x 10(-5) M of domperidone with a detection limit of 4.0 x 10(-7) M. The method was applied, without any interference from the excipients, to the determination of the drug in a tablet dosage form.

  17. Analysis of spironolactone residues in industrial wastewater and in drug formulations by cathodic stripping voltammetry.

    Science.gov (United States)

    El-Shahawi, M S; Bashammakh, A S; Al-Sibaai, A A; Bahaidarah, E A

    2013-04-01

    The redox behavior of spironolactone (SP) drug in Britton-Robinson (BR) buffer of pH 2-11 was investigated by differential pulse cathodic stripping voltammetry (DPCSV) and cyclic voltammetry (CV) at hanging mercury dropping electrode (HMDE). At pH 9-10.5, the DPCSV of SP drug showed two cathodic peaks at -1.15 and -1.38 V at the HMDE vs. Ag/AgCl reference electrode. In the CV, at pH 9-10, the dependence of the cathodic peak current, I p , c and peak potential, E p , c of the second peak ( E p , c 2 ) on the scan rate ( ν ) and on the depolizer (SP) concentrations was typical of an electrode coupled (EC) chemical reaction type mechanism. The plot of I p , c at -1.380 V of the DPCSV vs. SP concentration at pH 9 was linear over the concentration range of 1.2×10 -10 -9.6×10 -7  M. The lower limit of detection (LLOD) and limit of quantification (LOQ) of the drug were 1.1×10 -11 and 4.14×10 -11  M, respectively. The method was successfully applied for the analysis of SP residues in industrial wastewater, in pure form (98.2±3.1%) and in drug formulations e.g. Aldactone® tablet (98.35±2.9%).The method was validated by comparison with HPLC and the official data methods.

  18. 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.

  19. Determination of Au, Pt, Pd in gold ore mineral raw materials by stripping voltammetry

    Directory of Open Access Journals (Sweden)

    Kolpakova N.A.

    2016-01-01

    Full Text Available The paper considers the possibilities of use of the method of stripping voltammetry for finding platinum metals in mineral gold and ore raw material. A review of new options of electro-concentration of platinum metals on the surface of graphite electrode with the following sediment electro-oxidation and receipt of an analytical signal is presented: platinum finding was carried out by picks of selective electro-oxidation of iridium from intermetallic compound with platinum; gold finding was carried out by picks of gold electro-oxidation on the surface of graphite electrode modified by bismuth; palladium finding was performed by picks of palladium electro-oxidation on the surface of graphite electrode. 1M HCL solution was selected as a supporting electrolyte. Gold and hydrogen elimination on the process of palladium electro-oxidation was performed by means of UV irradiation of solution in the process of electro-concentration of palladium sediment. Gold, platinum and palladium determination was carried out in mineral gold and ore raw material of Verkhneamylskiy gold and ore district.

  20. Anodic stripping voltammetric determination of silver ion at a carbon paste electrode modified with carbon nanotubes

    International Nuclear Information System (INIS)

    Tashkhourian, J.; Javadi, S.; Ana, F.N.

    2011-01-01

    A carbon paste electrode (CPE) was modified with multi-wall carbon nanotubes and successfully applied to the determination of silver ion by differential pulse anodic stripping voltammetry. Compared to a conventional CPE, a remarkably improved peak current response and sensitivity is observed. The analytical procedure consisted of an open circuit accumulation step for 2 min in -0.4 V, this followed by an anodic potential scan between +0.2 and + 0.6 V to obtain the voltammetric peak. The oxidation peak current is proportional to the concentration of silver ion in the range from 1.0 x 10 -8 to 1.0 x 10 -5 mol L -1 , with a detection limit of 1.8 x 10 -9 mol L -1 after an accumulation time of 120 s. The relative standard deviation for 7 successive determinations of Ag(I) at 0.1 μM concentration is 1.99%. The procedure was validated by determining Ag(I) in natural waters. (author)

  1. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. A mercury free electrode for anodic stripping voltammetric determination of Pb (II) ions using poly zincon film modified electrode

    Science.gov (United States)

    Vasanthi, S.; Devendiran, M.; Narayanan, S. Sriman

    2017-11-01

    With an aim of developing a mercury-free electrode for anodic stripping voltammetric determination of Pb (II) ions, a poly zincon film (PZF) modified electrode is reported here. The PZF on the electrode surface has been obtained by electropolymerisation of zincon. PZF present on the electrode surface has been used for preconcentrating Pb (II) ions through complexation. The electrochemical determination of the above metal ion has been carried out by reducing the preconcentrated Pb (II) at -1.0 V followed by anodic stripping in acetate buffer of pH 6 and measuring the stripping current at -0.64 V. The PZF and Pb preconcentrated PZF modified electrodes have been characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The factors influencing the determination of Pb (II) ions such as the nature of medium/background electrolyte, pH, preconcentration time and electrode regeneration have been studied in detail. Under optimum conditions, a linear relation for the stripping current with Pb (II) ions in the solution has been observed in the range from 3.45 to 136.3 μg L-1 with a detection limit of 0.98 μg L-1. The regeneration of the modified electrode after each experiment has been achieved by simply immersing the electrode in 0.1 M EDTA solution for 2 min and washing thoroughly in de-ionised water. PZF modified electrode has shown a promising and sensitive platform for the anodic stripping determination of Pb (II) ions and the regeneration of the electrode has been found to be easy for subsequent uses. The proposed method has been applied for the determination of Pb (II) ions in ground water and tap water samples.

  4. Detection of mercury ions using L-cysteine modified electrodes by anodic stripping voltammetric method

    Science.gov (United States)

    Vanitha, M.; Balasubramanian, N.; Joni, I. Made; Panatarani, Camellia

    2018-02-01

    The detection of contaminants in wastewater is of massive importance in today's situation as they pose a serious threat to the environment as well as humans. One such vital contaminants is mercury and its compound, the reported mercury detectors grieve from low sensitivity, high cost and slow response. In the present work graphene based electrode material is developed for sensing mercury contaminants in wastewater using electrochemical technique. The synthesized material graphene oxide (GO) modified with L-Cysteine in presence of polyvinylpyrrolidone (PVP) as capping agent was characterized using SEM, TEM and Raman Spectroscopic analysis. It is ascertained from the morphological characterization that the nanocomposite exhibits a spherical morphology. The L-cysteine modified graphene oxide electrode is electrochemically characterized using redox couple [Fe(CN)63-/4-] and electrochemical impedance spectroscopic (EIS) analysis. Electrochemical sensing of Hg (II) ions in solution was done using Square wave anodic stripping voltammetry (SWASV). The incorporation of graphene significantly increases the sensitivity and selectivity towards mercury sensing.

  5. Anodic stripping voltammetric measurement of trace cadmium at tin-coated carbon paste electrode.

    Science.gov (United States)

    Li, Bang Lin; Wu, Zhi Ling; Xiong, Chang Hong; Luo, Hong Qun; Li, Nian Bing

    2012-01-15

    A carbon paste electrode modified with tin was used for the determination of trace cadmium by anodic stripping voltammetry. The electroanalytical performance for the determination of Cd(II) on the tin-coated carbon paste electrode(SnF-CPE) was better than that on the carbon paste electrode. The measuring conditions have been optimized. The measurement of trace cadmium on the SnF-CPE has the best response under the conditions of 0.10molL(-1) acetate buffer solution (pH 3.9), 3.5mgL(-1) Sn(II), deposition potential of -1.40V, and deposition time of 150s. The SnF-CPE revealed highly linear behavior in the concentration range of 2.0-90.0μgL(-1) with the detection limit of 1.13μgL(-1) for Cd(II). The developed sensor has been applied to the determination of Cd(II) in real water samples with satisfactory results. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Stripping voltammetry of thallium, indium and gallium on mercury-graphite electrodes

    International Nuclear Information System (INIS)

    Kamenev, A.I.; Kharitonova, O.I.; Chernova, N.A.; Agasyan, P.K.

    1986-01-01

    Electrochemical Tl(1), In(3) and Ga(3) behaviour in mercury-graphite electrodes by the method of direct-current and alternating-current voltammetry is studied. Comparison of mathematical models and their experimental check are carried out. Possibility to forecast the investigation results is shown, and the procedure for mercury-graphite electrode surface formation necessary in measurements is chosen

  7. Cathodic Stripping Voltammetry of Cysteine Using Silver and Copper Solid Amalgam Electrodes

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Novotný, Ladislav

    2002-01-01

    Roč. 56, č. 5 (2002), s. 971-976 ISSN 0039-9140 R&D Projects: GA ČR GV204/97/K084 Institutional research plan: CEZ:AV0Z4040901 Keywords : silver or copper solid amalgam electrode * cysteine * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 2.054, year: 2002

  8. Square wave stripping voltammetry of unlabeled single- and double-stranded DNAs

    Czech Academy of Sciences Publication Activity Database

    Bartošík, Martin; Paleček, Emil

    2011-01-01

    Roč. 23, č. 6 (2011), s. 1311-1319 ISSN 1040-0397 R&D Projects: GA MŠk(CZ) ME09038; GA MŠk(CZ) LC06035 Grant - others:GA ČR(CZ) GAP301/11/2055 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : square wave voltammetry * nucleic acids * mercury electrode Subject RIV: BO - Biophysics Impact factor: 2.872, year: 2011

  9. Simultaneous detection of Ponceat 4R and tartrazine in food using adsorptive stripping voltammetry on an acetylene black nanoparticle-modified electrode.

    Science.gov (United States)

    Yang, Xiaofeng; Qin, Haibin; Gao, Miaomiao; Zhang, Huajie

    2011-12-01

    Ponceau 4R and tartrazine have been widely used in foodstuffs. However, they are pathogenic if they are excessively consumed. Therefore, the detection of Ponceat 4R and tartrazine is quite important. A sensitive and rapid electrochemical method was developed for the simultaneous detection of Ponceat 4R and tartrazine using anodic adsorptive stripping voltammetry and based on the strong enhancement effect of acetylene black nanoparticle. For Ponceat 4R, the linear range was from 0.05 to 4 mg kg(-1) , and the limit of detection was 0.03 mg kg(-1) . For tartrazine, the linear range was from 0.15 to 18 mg kg(-1) , and the limit of detection was 0.1 mg kg(-1) . The relative standard deviation was 3.8% and 4.7% for 10 successive measurements of 1 mg kg(-1) Ponceau 4R and tartrazine. The method was used to determine Ponceat 4R and tartrazine in soft drinks, and recovery was in the range of 92.4-104.8%. At the acetylene black nanoparticle-modified electrode, the oxidation current signal of Ponceau 4R and tartrazine greatly increase. This new method is sensitive, rapid, simple and feasible. Copyright © 2011 Society of Chemical Industry.

  10. Anodic stripping voltammetric detection of Zn(II), Cd(II) and Pb(II) of coal gangue at bismuth film glassy carbon electrodes

    Science.gov (United States)

    Wang, Xiu-Teng; Zhang, Yajing; Li, Xiaoyan; Xu, Ling; Lin, Ling; Chen, Qian; Yang, Shuo

    2018-02-01

    For coal gangue it is very important to detect the heavy metals of the products in view of environment risk control, because the heavy metals in coal gangue can cause multiple significant toxic effects. Most of the techniques now available are more suitable for laboratory conditions only and usually cost much testing time. In this work, we develop a new rapid detecting method of Zn(II), Cd(II) and Pb(II) in coal gangue based on anodic stripping voltammetry. Through a large number of experiments, operational parameters have been optimized. This work provides a quick and convenient detection method for heavy metals in coal gangue.

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

    International Nuclear Information System (INIS)

    Vaze, Vishwanath D.; Srivastava, Ashwini K.

    2007-01-01

    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 -1 with 2-electron/2-proton transfer for the peak at +0.71 V against SCE. An adsorption equilibrium constant of 5 x 10 3 l/mol for maximum surface coverage of 2.89 x 10 -10 mol/cm 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 -12 M to 1.93 x 10 -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 -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

  12. 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.

  13. Stripping voltammetry glassy carbon on the study of Cd and Pb heavy metals pollution using anadara antiquata linn bioindicator

    International Nuclear Information System (INIS)

    Iswani, G.S.; Hidayat, F.; Zulkarnaen, A.

    1996-01-01

    The presence of cadmium and lead in sea water and shell fish (anadara antiquata linn) bioindicator in Gresik waters by glassy carbon stripping voltammetry was studied at menu 2 parameters as follows: time and potential plating-1000V and 90 second, sweep rate: 375 mV/second, strip time 2 second, electrolyte: aquatrides, pH = 0.4 (for shell fish) and -1000 V and 120 second, 999 mV/se con, 2 second, chloracetic, pH = 5.0. It was found that the mean of Cd and Pb contents in sea water at pH = 7.0, salinity = 28-29 ppm, oxygen content = 7.1-8.1 and temperature = 27-30 o C which was monitoring at location 1.2 and location 3.4 were 0.01 and 0.17 ppm, 1.44 and 1.35 ppm respectively. Furthermore the mean of Cd and Pb contents in shell fish at location 1.2 and 3.4 (snail range and shell fish dry weight were reported) were 5.94 and 3.05 ppm, 0,03 and 0,03 ppm. The t-tes for Cd and Pb contents in sea waters and shell fish at location 1,2 compared with location 3.4 were significant and no significant. The accuracy of the method was tested with SRM coppepoda MA-A-1-A-a and W-4. (author)

  14. The mathematical model of the stripping voltammetry hydrogen evolution/dissolution process on Pd layer

    International Nuclear Information System (INIS)

    Skital, Piotr M.; Sanecki, Przemyslaw T.; Kaczmarski, Krzysztof

    2010-01-01

    The advanced two-plate mathematical model of electrochemical hydrogen evolution/dissolution process has been presented and discussed. The model, with Langmuir adsorption equation, has been experimentally verified by the use of the glassy carbon/Pd layer electrode system at different scan rates. The two cathodic-anodic stages of hydrogen evolution/dissolution process in 0.1 M and 0.001 M HCl solutions have been interpreted and discussed. The thickness of the layer and the way of deposition were also investigated. The fundamental kinetic problem of a change of electrode properties during electrode process as an effect of the elementary hydrogen presence in the solid electrode is presented and interpreted. The isopotential point phenomenon, an electrochemical analog of isosbestic point in absorption spectroscopy, was unexpectedly discovered as experimental effect of hydrogen adsorption and α variability.

  15. Determination of Sudan I in drinks containing Sunset yellow by adsorptive stripping voltammetry.

    Science.gov (United States)

    Gómez, Marisol; Arancibia, Verónica; Aliaga, Margarita; Núñez, Claudia; Rojas-Romo, Carlos

    2016-12-01

    An efficient, fast and sensitive method for the determination of Sudan I (SI) in drinks containing Sunset yellow (Sy) is developed and validated using an adsorptive stripping voltammetric procedure. Sy is currently added to a large number of foods; however during their synthesis SI may be produced. The determination is based on adsorption of Sy and SI onto HMDE and later reduction of the azo group at -0.71 and -0.82V, respectively. Using the best set of the experimental conditions (pH 12.3; Eads: -0.40V) for the determination of SI in Sy, a linear response for SI in the concentration range 0.5-27.2μgL(-1) was found, with a detection limit of 1.5μgL(-1) in a tads of only 30s. The method was applied to the determination of SI in commercial drinks with satisfactory results. The presence of SI was confirmed by mass spectrometry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Boron doped diamond electrodes for the dopamine identification by anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Vojs, M.; Behul, M.; Michniak, P.; Rehacek, V.; Tvarozek, V.; Vesely, M.; Rossberg, M.; Schaaf, P.

    2012-01-01

    Polycrystalline BDD films 200-280 nm thick (Fig. 1) were produced in the double bias enhanced HF CVD reactor with sheet resistivity ∼ 100 Ω/sq. As a substrate, highly conductive (0.008-0.024 Ωcm) N (100) type silicon substrate was used with ∼ 200 nm wet SiO 2 oxide. Throughout the deposition, gas flows in reaction chamber were controlled to be 1 % CH 4 in H 2 and trymethylboron (TMB) in the range of 0-200 sccm (corresponding to 0-13 333 ppm of B/C). We have compared different measurements in presence of biological molecules (DA) with various BDD electrodes. These electrodes exhibited very high sensitivity, long-therm stability and high reproducibility. A very good performance (LOD = 6.02, R 2 =0.9921) of the BDD surface has been demonstrated only for very high 10 000 ppm B/C ratio (B doping levels n = 3.6·10 21 cm -3 ) for surface sensitive reactions in complex biological matrices. (authors)

  17. Simultaneous determination of lead, cadmium and zinc in Metro Manila air particulates by anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Castaneda, Soledad S.

    1999-02-01

    Air particulate samples were collected from two monitoring stations in Metro Manila using a 'Gent' type dichotomous sampler for pollutant source apportionment studies. Samples were collected in two fractions: a fine fraction with aerodynamic diameter, d p p 3 : HCL: HF, 4: 1: 1) for at least 20 minutes with subsequent heating at lower power settings for a total of 20 minutes more, effectively decomposed the sample with complete recovery of the elements. The digests were evaporated to near dryness to eliminate the troublesome effect of HF and HNO 3 and to decrease acidity of the electrolytic solution to pH ≥ 2. At pH 2, the addition of at least 0.01 M KCl was needed to improve sensitivity. The formation of Zn-Cu intermetallic compounds which interfered in the accurate quantitation of zinc was eliminated by addition of gallium as a 'third' element. The amount of gallium needed varied from sample to sample and was affected by the pH of the solution. The DPASV parameters found to be optimum for the analysis of the air particulate samples are as follows: pulse amplitude, 50 mV; scan rate, 10 mV/sec; E dep , - 1.30 V; t dep , 2 min; and RDE rotation rate, 1500 rpm. Detection limits of 0.2 ppb for zinc, 0.6 ppb for lead, and 0.05 ppb for cadmium in the sample matrix were obtained. The standard addition method was found to be reliable for the quantitative determination of the analytes in the sample. All R 2 values obtained were > 0.9900 at 95% confidence level. Validation of the established analytical methodology by analyzing certified reference standards and performing parallel analysis by GF-AAS and flame AAS showed acceptable accuracy of the DPASV measurements. (Author)

  18. Mercury-Free Analysis of Lead in Drinking Water by Anodic Stripping Square Wave Voltammetry

    Science.gov (United States)

    Wilburn, Jeremy P.; Brown, Kyle L.; Cliffel, David E.

    2007-01-01

    The analysis of drinking water for lead, which has well-known health effects, is presented as an instructive example for undergraduate chemistry students. It allows the students to perform an experiment and evaluate to monitor risk factors and common hazard of everyday life.

  19. Determination of Cd, Pb and Cu in Mandovi estuary by differential pulse anodic stripping voltammetry

    Digital Repository Service at National Institute of Oceanography (India)

    George, M.D.; Sawkar, K.; Reddy, C.V.G.

    Dissolved labile and non-labile (organically associated) concentration of Cd, Pb and Cu in Mandovi Estuary, Goa, India have been measured for 1 y (February 1980 to January 1981). Percentage non-labile form varies from 0-50% of the total for Cd, from...

  20. Application of stripping voltammetry and microelectrodes in vitro biocompatibility and in vivo toxicity tests of AISI 316L corrosion products.

    Science.gov (United States)

    Morais, S; Pereira, M C

    2000-04-01

    Adsorptive stripping voltammetric procedures, using mercury film microelectrodes, were optimised and applied to quantify total iron, chromium and nickel in samples of osteoblast-like cells culture medium and mice organs (liver, kidney and spleen) obtained from, respectively, in vitro and in vivo 316L stainless steel corrosion products biocompatibility and toxicity studies. The methods were based on the pre-concentration of the iron-catechol complex by adsorption at the potential of -1.80 V (vs. Ag/AgCl), of the chromium-diethylenetriaminepentaacetic acid complex at -1.00 V or -1.15 V (vs. Ag/AgCl) and of the nickel-dimethylglyoxime complex at -0.70 V (vs. Ag/AgCl). The detection limits achieved for each metal ion (i) in the culture medium were 1.93x10(-8) mol/L Fe, 2.80x10(-10) mol/L Cr and 7.70x10(-9) mol/L Ni for a collection time of 30 s, 40 s and 10 s, respectively, and (ii) in the mice organ solutions were 1.37x10(-8) mol/L Fe, 1.54x10(-8) mol/L Cr and 1.58x10(-9) mol/L Ni for an adsorption time of 25 s, 25 s and 15 s, respectively. The accuracy of the proposed procedures was verified by comparison of the results obtained by adsorptive stripping voltammetry with those attained by atomic absorption spectrometry for the same set of samples and good agreement was found. The in vitro study showed that stainless steel corrosion products affect the expression of the osteogenic phenotype. The in vivo mice model, used to investigate the systemic effects provoked by the corrosion products per se, indicated that Fe, Cr and Ni are partially accumulated in the organs studied and that Ni induced the more significant morphological alterations.

  1. Een bepalingsmethode voor thallium in regenwater met behulp van voltammetrie

    NARCIS (Netherlands)

    Struijs; J.; Wolfs; P.M.; Esseveld; F.G.van

    1985-01-01

    In dit rapport wordt een bepalingmethode beschreven voor thallium in het nanogram/liter-gebied, waarbij gebruik wordt gemaakt van differentiele pulse-anodic stripping voltammetry (DPASV) aan de dunne kwikfilm. Met deze techniek blijkt het mogelijk om de concentratie van dit element rechtstreeks

  2. Gas detector with a μm size strips anode

    International Nuclear Information System (INIS)

    Oed, A.

    1988-01-01

    A flat electrode device for an ionizing radiation multidetector, particularly for an X-ray detector used in tomodensitometry, is presented. It consists of either two active electrodes of the same kind, or an anode-electrode and a cathode electrode, on opposite sides of a base plate. The device avoids problems linked to flatness and parallelism, and the base plate consists of at least two intermediate plates separated by a space containing at least layer of binding material. The device thus overcomes difficulties associated with thickness and the need to stop ionizing radiation from passing from one cell to another by traversing the base plate. The steps of the fabrication process are detailed [fr

  3. The redox thermodynamics and kinetics of flavonoid rutin adsorbed at glassy carbon electrodes by stripping square wave voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Aragao Catunda, Francisco Eduardo; Araujo, Marcelo Francisco de [Departamento de Quimica, Instituto de Ciencias Exactas, Universidad Federal Rural do Rio de Janeiro, BR 465 KM 07, 23890-000, Seropedica, RJ (Brazil); Granero, Adrian Marcelo; Arevalo, Fernando Javier [Departamento de Quimica, Facultad de Ciencias Exactas, Fisico-Quimicas y Naturales, Universidad Nacional de Rio Cuarto, Agencia Postal No 3 - (5800), Rio Cuarto (Argentina); Carvalho, Mario Geraldo de [Departamento de Quimica, Instituto de Ciencias Exactas, Universidad Federal Rural do Rio de Janeiro, BR 465 KM 07, 23890-000, Seropedica, RJ (Brazil); Zon, Maria Alicia, E-mail: azon@exa.unrc.edu.ar [Departamento de Quimica, Facultad de Ciencias Exactas, Fisico-Quimicas y Naturales, Universidad Nacional de Rio Cuarto, Agencia Postal No 3 - (5800), Rio Cuarto (Argentina); Fernandez, Hector, E-mail: hfernandez@exa.unrc.edu.ar [Departamento de Quimica, Facultad de Ciencias Exactas, Fisico-Quimicas y Naturales, Universidad Nacional de Rio Cuarto, Agencia Postal No 3 - (5800), Rio Cuarto (Argentina)

    2011-11-30

    Highlights: > Adsorptive accumulation of rutin is studied at glassy carbon (GC) electrodes. > The Frumkin adsorption isotherm described the specific interaction. > Gibbs free energy of adsorption and the interaction parameter were determined. > Thermodynamics and kinetics of the surface redox process were characterized by SWV. > Detection limit for rutin was 2 x 10{sup -8} mol dm{sup -3} (12 ppb). - Abstract: The adsorptive accumulation of rutin (RU) at glassy carbon (GC) electrodes in 10% ethanol + 90% 1 mol dm{sup -3} HClO{sub 4} aqueous solution is studied by using cyclic (CV) and square wave (SWV) voltammetries. The Frumkin adsorption isotherm best described the specific interaction of rutin with carbon electrodes. By fitting the experimental data, values of -31.9 kJ mol{sup -1} and 0.54 {+-} 0.02 were obtained for the Gibbs free energy of adsorption and the interaction parameter, respectively. SWV fully characterized the thermodynamics and kinetics of the surface redox process, using a combination of the 'quasi-reversible maximum' and the 'splitting of SW peaks' methods. Average values of 0.644 {+-} 0.003 V and 0.44 {+-} 0.02 were obtained for the formal potential and the anodic transfer coefficient, respectively. Moreover, a formal rate constant of 6.1 x 10{sup 2} s{sup -1} was obtained. SWV was also employed to generate calibration curves. The lowest concentration of RU experimentally measured for a signal-to-noise ratio of 3:1 was 2 x 10{sup -8} mol dm{sup -3} (12 ppb).

  4. Differential pulse anodic stripping voltametry for ultratrace determination of cadmium and lead in Antarctic snow

    International Nuclear Information System (INIS)

    Scarponi, G.; Barbante, C.; Cescon, P.

    1994-01-01

    Differential pulse anodic stripping voltametry has sufficient sensitivity to be used for direct determination of heavy metals in Antarctic snow, thus avoiding long and contamination-prone enrichment procedures. A result of particular concern to global change studies can be drawn from these preliminary data: lead concentration in Antarctic snow decreased rapidly during the 1980s from about 10-15 pg/g to 2-4 pg/g in 1991. (authors). 16 refs., 3 figs., 1 tab

  5. Voltammetric behaviour at gold electrodes immersed in the BCR sequential extraction scheme media Application of underpotential deposition-stripping voltammetry to determination of copper in soil extracts

    Energy Technology Data Exchange (ETDEWEB)

    Beni, Valerio; Newton, Hazel V.; Arrigan, Damien W.M.; Hill, Martin; Lane, William A.; Mathewson, Alan

    2004-01-30

    The development of mercury-free electroanalytical systems for in-field analysis of pollutants requires a foundation on the electrochemical behaviour of the chosen electrode material in the target sample matrices. In this work, the behaviour of gold working electrodes in the media employed in the BCR sequential extraction protocol, for the fractionation of metals in solid environmental matrices, is reported. All three of the BCR sequential extraction media are redox active, on the basis of acidity and oxygen content as well as the inherent reducing or oxidising nature of some of the reagents employed: 0.11 M acetic acid, 0.1 M hydroxylammonium chloride (adjusted to pH 2) and 1 M ammonium acetate (adjusted to pH 2) with added trace hydrogen peroxide. The available potential ranges together with the demonstrated detection of target metals in these media are presented. Stripping voltammetry of copper or lead in the BCR extract media solutions reveal a multi-peak behaviour due to the stripping of both bulk metal and underpotential metal deposits. A procedure based on underpotential deposition-stripping voltammetry (UPD-SV) was evaluated for application to determination of copper in 0.11 M acetic acid soil extracts. A preliminary screening step in which different deposition times are applied to the sample enables a deposition time commensurate with UPD-SV to be selected so that no bulk deposition or stripping occurs thus simplifying the shape and features of the resulting voltammograms. Choice of the suitable deposition time is then followed by standards addition calibration. The method was validated by the analysis of a number of BCR 0.11 M acetic acid soil extracts. Good agreement was obtained been the UPD-SV method and atomic spectroscopic results.

  6. Application of a wedge strip anode in micro-pattern gaseous detectors

    International Nuclear Information System (INIS)

    Tian Yang; Yang Yigang; Li Yulan; Li Yuanjing

    2013-01-01

    The wedge strip anode (WSA) has been widely used in 2-D position-sensitive detectors. A circular WSA with an effective diameter of 52 mm is successfully coupled to a tripe gas electron multiplier (GEM) detector through a simple resistive layer. A spatial resolution of 440 μm (FWHM) is achieved for a 10 kVp X-ray using 1 atm Ar:CO 2 =70:30 gas. The simple electronics of only three channels makes it very useful in applications strongly requiring simple interface design, e.g. sealed tubes and high pressure detectors. (authors)

  7. Microprocessor controlled anodic stripping voltameter for trace metals analysis in tap water

    Energy Technology Data Exchange (ETDEWEB)

    Clem, R.G.; Park, F.W.; Kirsten, F.A.; Phillips, S.L.; Binnall, E.P.

    1981-04-01

    The construction and use of a portable, microprocessor controlled anodic stripping voltameter for on-site simultaneous metal analysis of copper, lead and cadmium in tap water is discussed. The instrumental system is comprised of a programmable controller which permits keying in analytical parameters such as sparge time and plating time; a rotating cell for efficient oxygen removal and amalgam formation; and, a magnetic tape which can be used for data storage. Analysis time can be as short as 10 to 15 minutes. The stripping analysis is based on a pre-measurement step during which the metals from a water sample are concentrated into a thin mercury film by deposition from an acetate solution of pH 4.5. The concentrated metals are then electrochemically dissolved from the film by application of a linearly increasing anodic potential. Typical peak-shaped curves are obtained. The heights of these curves are related to the concentration of metals in the water by calibration data. Results of tap water analysis showed 3 +- 1 ..mu..g/L lead, 22 +- 0.3 ..mu..g/L copper, and less than 0.2 ..mu..g/L cadmium for a Berkeley, California tap water, and 1 to 1000 ..mu..g/L Cu, 1 to 2 ..mu..g/L Pb for ten samples of Seattle, Washington tap water. Recommendations are given for a next generation instrument system.

  8. Effect of humic acid on the underpotential deposition-stripping voltammetry of copper in acetic acid soil extract solutions at mercaptoacetic acid-modified gold electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Herzog, Gregoire; Beni, Valerio; Dillon, Patrick H.; Barry, Thomas; Arrigan, Damien W.M

    2004-05-24

    Electrochemical measurements were undertaken for the investigation of the underpotential deposition-stripping process of copper at bare and modified gold electrodes in 0.11 M acetic acid, the first fraction of the European Union's Bureau Communautaire de References (BCR) sequential extraction procedure for fractionating metals within soils and sediments. Gold electrodes modified with mercaptoacetic acid showed higher sensitivity for the detection of copper than bare gold electrodes, both in the absence and in the presence of humic acid in acetic acid solutions, using the underpotential deposition-stripping voltammetry (UPD-SV) method. In the presence of 50 mg l{sup -1} of humic acid, the mercaptoacetic acid modified electrode proved to be 1.5 times more sensitive than the bare gold electrode. The mercaptoacetic acid monolayer formed on the gold surface provided efficient protection against the adsorption of humic acid onto the gold electrode surface. Variation of the humic acid concentration in the solution showed little effect on the copper stripping signal at the modified electrode. UPD-SV at the modified electrode was applied to the analysis of soil extract samples. Linear correlation of the electrochemical results with atomic spectroscopic results yielded the straight-line equation y ({mu}g l{sup -1}) = 1.10x - 44 (ppb) (R=0.992, n=6), indicating good agreement between the two methods.

  9. Initial stages of anodic oxidation of silver in sodium hydroxide solution studied by potential sweep voltammetry and ellipsometry

    NARCIS (Netherlands)

    Droog, J.M.M.; Alderliesten, P.T.; Bootsma, G.A.

    1979-01-01

    The first stages of the oxidation of polycrystalline silver electrodes in NaOH solutions were studied by potential sweep voltammetry and ellipsometry. Formation of bulk Ag2O was found to be preceded by dissolution of silver species and deposition of a surface oxide. The equilibrium oxide coverage

  10. Modelling the background current with partial least squares regression and transference of the calibration models in the simultaneous determination of Tl and Pb by stripping voltammetry.

    Science.gov (United States)

    Herrero, A; Ortiz, M C

    1998-05-01

    With the aim of carrying out a calibration transfer for routine analysis, partial least squares (PLS) regression was successfully applied to simultaneously determine thallium and lead by stripping voltammetry when an interfering background current is present. The presence of a significant blank signal that overlaps the thallium peak, together with the overlapping thallium and lead signals were both suitably modelled by this multivariate regression technique. Moreover, once the PLS models are built, the piecewise direct standardization (PDS) method can be used to transfer these models over time in such a way that the number of calibration samples that will be needed in future determinations is reduced from 25 to 9, without a loss of quality in the analyses. The mean of the relative errors (in absolute values) obtained for thallium and lead is below 4.94% and 3.19%, respectively.

  11. Selective determination of trace copper(II) by cathodic adsorptive stripping voltammetry with a naphthol-derivative Schiff's base.

    Science.gov (United States)

    Shamsipur, Mojtaba; Saeidi, Mahboubeh; Sharghi, Hashem; Naeimi, Hossein

    2003-01-01

    A selective and sensitive stripping voltammetric method for the determination of trace amounts of copper(II) with a recently synthesized naphthol-derivative Schiff's base (2,2'-[1,2-ethanediylbis(nitriloethylidyne)]bis(1-naphthalene)) is presented. The method is based on adsorptive accumulation of the resulting copper-Schiff's base complex on a hanging mercury drop electrode, followed by the stripping voltammetric measurement at the reduction current of adsorbed complex at -0.15 V (vs. Ag/AgCl). The optimal conditions for the stripping analysis of copper include pH 5.5 to 6.5, 8 microM Schiff's base and an accumulation potential of -0.05 V (vs. Ag/AgCI). The peak current is linearly proportional to the copper concentration over a range 2.3-50.8 ng ml(-1) with a limit of detection of 1.9 ng ml(-1). The accumulation time and RSD are 90 s and (3.2-3.5)%, respectively. The method was applied to the determination of copper in some analytical grade salts, tap water, human serum and sheep's liver.

  12. Determination of Xanthine in the Presence of Hypoxanthine by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

    Directory of Open Access Journals (Sweden)

    Percio Augusto Mardini Farias

    2014-01-01

    Full Text Available 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.

  13. The electroanalytical detection and determination of copper in heavily passivating media: ultrasonically enhanced solvent extraction by N-benzoyl-N-phenyl-hydroxylamine in ethyl acetate coupled with electrochemical detection by sono-square wave stripping voltammetry analysis.

    Science.gov (United States)

    Hardcastle, J L; Compton, R G

    2001-11-01

    N-benzoyl-N-phenyl-hydroxylamine dissolved in ethyl acetate was employed as a ligand for the solvent extraction of copper. Ultrasonic emulsification was shown to be effective both in the extraction of copper from an aqueous phase into ethyl acetate and its recovery or "back extraction" into a fresh clean aqueous solution. Experimental determination of thermodynamic parameters governing the extraction process via UV/visible spectroscopy is reported. This permitted theoretical predictions for the amount of copper transferred into the final aqueous solution to be fitted to experimental data. Quantitative analysis of copper removed via double sono-extraction from an aqueous medium hostile to voltammetric analysis proceeded via sono-square wave anodic stripping voltammetry analysis (sono-SWASV). This resulted in very high sensitivity in the relatively clean medium. The technique was then applied to the analysis of copper in the soft drink 'Ribena Light'. In the absence of sample preparation by solvent extraction sono-SWASV yields a measurable peak current for copper. However it is irreproducible and erratic due to passivating effects, possibly attributed to the sugars, natural flavourings and colourings present. Following sono-solvent extraction, the overall copper concentration could be obtained with a detection limit of 2 microg L(-1). Biphasic sono-extraction synergistically coupled with the recognized technique sono-SWASV presents an attractive technique for copper analysis in electrode passivating media. The technique necessarily removes contaminants present in the test solution since these will prefer to remain in the initial aqueous phase, or will transfer to the organic phase but are unlikely to be doubly transferred into the 'clean' final aqueous phase.

  14. Complexation-Based Detection of Nickel(II at a Graphene-Chelate Probe in the Presence of Cobalt and Zinc by Adsorptive Stripping Voltammetry

    Directory of Open Access Journals (Sweden)

    Keagan Pokpas

    2017-07-01

    Full Text Available The adsorptive stripping voltammetric detection of nickel and cobalt in water samples at metal film electrodes has been extensively studied. In this work, a novel, environmentally friendly, metal-free electrochemical probe was constructed for the ultra-trace determination of Ni2+ in water samples by Adsorptive Cathodic Stripping Voltammetry (AdCSV. The electrochemical platform is based on the adsorptive accumulation of Ni2+ ions directly onto a glassy carbon electrode (GCE modified with dimethylglyoxime (DMG as chelating agent and a Nafion-graphene (NGr nanocomposite to enhance electrode sensitivity. The nafion-graphene dimethylglyoxime modified glassy carbon electrode (NGr-DMG-GCE shows superior detection capabilities as a result of the improved surface-area-to-volume ratio and enhanced electron transfer kinetics following the incorporation of single layer graphene, while limiting the toxic effects of the sensor by removal of the more common mercury, bismuth and lead films. Furthermore, for the first time the NGr-DMG-GCE, in the presence of common interfering metal ions of Co2+ and Zn2+ demonstrates good selectivity and preferential binding towards the detection of Ni2+ in water samples. Structural and morphological characterisation of the synthesised single layer graphene sheets was conducted by Raman spectrometry, HRTEM and HRSEM analysis. The instrumental parameters associated with the electrochemical response, including accumulation potential and accumulation time were investigated and optimised in addition to the influence of DMG and graphene concentrations. The NGr-DMG-GCE demonstrated well resolved, reproducible peaks, with RSD (% below 5% and a detection limit of 1.5 µg L−1 for Ni2+ reduction at an accumulation time of 120 s., the prepared electrochemical sensor exhibited good detection and quantitation towards Ni2+ detection in tap water samples, well below 0.1 mg L−1 set by the WHO and EPA standards. This comparable to the South

  15. Trace analysis of lead and cadmium in seafoods by differential pulse anodic stripping voltametry

    International Nuclear Information System (INIS)

    Sumera, F.C.; Verceluz, F.P.; Kapauan, P.A.

    1979-01-01

    A method for the simultaneous determination of cadmium and lead in seafoods is described. The sample is dry ashed in a muffle furnace elevating the temperature gradually up to 500 0 C. The ashed sample is treated with concentrated nitric acid, dried on a heating plate and returned to the muffle furnace for further heating. The treated ash is then dissolved in 1 N HCL acetate buffer and citric acid are added and the pH adjusted to 3.6-4. The resulting solution is analyzed for lead and cadmium by differential pulse anodic stripping voltametry (DPASV) using a wax-impregnated graphite thin film electrode. The average recoveries of 0.4 of cadmium and lead added to 5 fish samples were 97% and 99% respectively. The standard deviations, on a homogenized shark sample for lead and cadmium analysis were 6.7 ppb and 12.3 ppb, respectively, and the relative standard deviations were 21.0% and 15.5% respectively. Studies on instrumental parameters involved in the DPASV step of analysis and methods of measuring peak current signals were also made. (author)

  16. Dual Approach to Amplify Anodic Stripping Voltammetric Signals Recorded Using Screen Printed Electrodes

    Directory of Open Access Journals (Sweden)

    Agnieszka KRÓLICKA

    2016-12-01

    Full Text Available Screen printed electrodes plated with bismuth were used to record anodic stripping voltammograms of Pb(II, In(III and Cd(II. Using two bismuth precursors: Bi2O3 dispersed in the electrode body and Bi(III ions spiked into the tested solution it was possible to deposit bismuth layers, demonstrating exceptional ability to accumulate metals forming alloys with bismuth. The voltammetric signals were amplified by adjusting the electrode location with respect to rotating magnetic field. The electrode response was influenced by vertical and horizontal distance between the magnet center and the sensing area of screen printed electrode as well as the angle between the magnet surface and the electrode. When the electrode was moved away from the magnet center the recorded peaks were increasingly smaller and almost not affected by the presence of bismuth ions. It was shown that to obtain well-shaped signals a favourable morphology of bismuth deposits is of key importance. Hypotheses explaining processes responsible for the amplification of voltammetric signals were proposed.

  17. 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.

  18. Heavy metal distribution in organic and siliceous marine sponge tissues measured by square wave anodic stripping voltammetry.

    Science.gov (United States)

    Illuminati, S; Annibaldi, A; Truzzi, C; Scarponi, G

    2016-10-15

    May sponge spicules represent a "tank" to accumulate heavy metals? In this study we test this hypothesis determining the distribution of Cd, Pb and Cu concentrations between organic and siliceous tissues in Antarctic Demospongia (Sphaerotylus antarcticus, Kirkpatrikia coulmani and Haliclona sp.) and in the Mediterranean species Petrosia ficiformis. Results show that although, in these sponges, spicules represent about 80% of the mass content, the accumulation of pollutant is lower in the spicules than in the corresponding organic fraction. The contribution of tissues to the total sponge content of Cd, Pb and Cu is respectively 99%, 82% and 97% for Antarctic sponges and 96%, 95% and 96% for P. ficiformis, similar in polar and temperate organisms. These results pave the way to a better understanding of the role of marine sponges in uptaking heavy metals and to their possible use as monitor of marine ecosystems, recommend by the Water Framework Directive. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Trace vanadium analysis by catalytic adsorptive stripping voltammetry using mercury-coated micro-wire and polystyrene-coated bismuth film electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Dansby-Sparks, Royce; Chambers, James Q. [Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600 (United States); Xue Ziling, E-mail: xue@ion.chem.utk.edu [Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600 (United States)

    2009-06-08

    An electrochemical technique has been developed for ultra-trace (ng L{sup -1}) vanadium (V) measurement. Catalytic adsorptive stripping voltammetry for V analysis was developed at mercury-coated gold micro-wire electrodes (MWEs, 100 {mu}m) in the presence of gallic acid (GA) and bromate ion. A potential of -0.275 V (vs Ag/AgCl) was used to accumulate the complex in acetate buffer (pH 5.0) at the electrode surface followed by a differential pulse voltammetric scan. Parameters affecting the electrochemical response, including pH, concentration of GA and bromate, deposition potential and time have been optimized. Linear response was obtained in the 0-1000 ng L{sup -1} range (2 min deposition), with a detection limit of 0.88 ng L{sup -1}. The method was validated by comparison of results for an unknown solution of V by atomic absorption measurement. The protocol was evaluated in a real sample by measuring the amount of V in river water samples. Thick bismuth film electrodes with protective polystyrene films have also been made and evaluated as a mercury free alternative. However, ng L{sup -1} level detection was only attainable with extended (10 min) deposition times. The proposed use of MWEs for the detection of V is sensitive enough for future use to test V concentration in biological fluids treated by the advanced oxidation process (AOP).

  20. Impact of geo-chemical environment of subsurface water on the measurement of ultra trace level of uranium in ground water by adsorptive stripping voltammetry

    International Nuclear Information System (INIS)

    Singhal, R.K.; Preetha, J.; Karpe, Rupali; Ajay Kumar; Hegde, A.G.

    2005-01-01

    During the present work, impacts of cations (Ca 2+ , Mg 2+ , K + ,), anions (Cl -1 , F -1 , and PO 4 3- ) and DOC (Dissolved Organic Carbon) on the measurement of ultra trace level of uranium (VI) in subsurface water by adsorptive stripping voltammetry (AdSV) is studied. The concentrations of these anions, cations and DOC in subsurface water changes due to change in the geo-chemical environment at different locations. In AdSV, concentration of U was determined by forming an uranium-chloranilic acid complex (2,5-dichloro- 3,6-dihydroxy-1,4-benzoquinone). AdSV measurements were carried out in the differential pulse (DP) mode using a pulse amplitude of -50 mV, a pulse time of 30 ms and a potential step of 4 mV. The detection limit, was calculated to 2+ , Mg 2+ , K + ) and anions (Cl -1 , F -1 , and PO 4 3- ) was carried out by using Ion Chromatography. Ground water samples were spiked with varying degree of cations, anions and DOC (dissolved organic carbon). DOC in ground waters were measured by Total Organic Carbon (TOC) analyzer. Various experiments show that analysis of uranium in the concentration range of 2+ , Mg 2+ , K + , Cl -1 , F -1 , and PO 4 3- . In case of DOC there is no interference observed in the concentration range of 0.02-15 ppm but beyond 15 ppm the concentration of uranium decrease sharply. Further, if DOC exceeded 16 ppm it was not possible to do the analysis of uranium by AdSV without destruction of DOC, as DOC is surface active organic compound and accumulates on Hg electrode preferentially over uranium-chloroanailic complex. (author)

  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. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Novel acyclonucleoside analog bearing a 1,2,4-triazole–Schiff base: Synthesis, characterization and analytical studies using square wave-adsorptive stripping voltammetry and HPLC

    Directory of Open Access Journals (Sweden)

    Ali F. Alghamdi

    2017-09-01

    Full Text Available New acyclonucleoside analogs tethered by a 1,2,4-triazole scaffold were synthesized through the condensation of 4-amino-5-(2-phenyleth-1-yl-2,4-dihydro-3H-1,2,4-triazole-3-thione (2 with benzaldehyde followed by the alkylation of the resulting Schiff base (3with 2-bromoethanol, 3-chloropropanol and/or 3-chloropropan-1,2-diol. Voltammetric studies were carried out for the analysis of 1 × 10−6 mol L−1 of the newly synthesized acyclonucleoside analogs (4–6 using square wave-adsorptive stripping voltammetry (SW-AdSV. The sharp voltammetric peak and high reduction current were recorded using a Britton–Robinson B–R pH 10 buffer at Ep = −1250 mV on the hanging mercury drop surface (HMDE and Ag/AgCl reference electrode. Several experimental conditions were studied, such as the supporting electrolytes, the pH, and the accumulation time, as well as the potential, the scan rate, the frequency and the step potential for 4-benzylideneamino-5-(2-phenyleth-1-yl-3-[(2,3-dihydroxyprop-1-ylthio]-1,2,4-triazole (6. The analytical performance of the voltammetric technique was investigated through the analysis of the calibration curve, the detection limit, the recovery and the stability. The voltammetric analytical applications were evaluated by the recovery of compound (6 in the urine and plasma samples. The HPLC technique was also applied for the separation of compound (6 from interference using a C-18 (5 μm column with UV detection at 254 nm.

  3. Zinc (Zn Analysis in Milk by Microwave Oven Digestion and Differential Pulse Anodic Stripping Voltametry (DPASV Technique

    Directory of Open Access Journals (Sweden)

    Mohineesh

    2013-04-01

    Full Text Available Milk is very important component of human diet. The presence of over limit of heavy metal in milk may create significant health problems. In the present study, the direct determination of Zinc (Zn heavy metal in milk samples of different brands was carried out by differential pulse anodic stripping Voltammetric technique at Hanging Mercury Drop Electrode (HMDE. Milk samples were processed by microwave oven digestion using HP/VHP Vessels and TFM Liners and nitric acid (HNO3.Determination of Zn was made in acetate buffer (pH 4.6 with a sweep rate (scan rate of 59.5 mV/s and pulse amplitude 50mV by HMDE by standard addition method. The solution was stirred during pre-electrolysis at -1150mV (vs. Ag/AgCl for 90 seconds and the potential was scanned from -1150V to +100V (vs. Ag/AgCl. The zinc ions were deposited by reduction at -1150 mV on HMDE. The stripping current arising from the oxidation of metal was correlated with the concentration the metal in the sample. .As a result the minimum level of Zn observed in the milk sample of different brands was determined as 2.28 mgL−1.

  4. Qualification of a Voltammetry Measurement System

    OpenAIRE

    Scholz, Sunna

    2014-01-01

    The voltammetry measurement system consisting of a potentiostat μStat 200, electrode strips and accessories has been scrutinized, following the four phases of instrument qualification. These are design qualification, installation qualification, operational qualification and performance qualification in succeeding order. As design qualification operational specifications of the voltammetry measurement system have been collected. These were the innovative technique of screen printing electro...

  5. Identification of phase structure of plated zinc alloys based on a linear voltammetry in alkaline solutions

    Directory of Open Access Journals (Sweden)

    Lina V. Petrenko

    2016-12-01

    Full Text Available The purpose of research was the development of new and effective technique of electroplatings phase composition analysis by inversion voltammetric methods. As a result the possibility of the phase composition of the plated zinc-based alloys identification using anodic linear voltammetry in alkaline solutions was shown. The phase composition Zn–(0.27–9.4% Fe alloy electroplated from alkaline zincate solutions was defined based on voltammetry data. As part of the Zn–Fe alloys the phase of hexagonal structure was found which is absent in the equilibrium phase diagram. The ratio of hexagonal crystal lattice axes (c/a and the electron concentration (e/a for this phase are significantly different from the corresponding values for the primary solid solution η. From the analysis of c/a and e/a values of investigated Zn–Fe alloy the defined phase was identified as a solid solution phase type ε. It also was shown that anodic linear voltammetry accomplished in alkaline solutions is more sensitive to the identification of the phase composition of zinc alloys than the traditional X-ray method and stripping voltammetry.

  6. Sensitive and stable monitoring of lead and cadmium in seawater using screen-printed electrode and electrochemical stripping analysis

    International Nuclear Information System (INIS)

    Gueell, Raquel; Aragay, Gemma; Fontas, Claudia; Antico, Enriqueta; Merkoci, Arben

    2008-01-01

    Sensitive and stable monitoring of heavy metals in seawater using screen-printed electrodes (SPE) is presented. The analytical performance of SPE coupled with square wave anodic stripping voltammetry (SWASV) for the simultaneous determination of Pb and Cd in seawater samples, in the low μg L -1 range, is evaluated. The stripping response for the heavy metals following 2 min deposition was linear over the concentration range examined (10-2000 μg L -1 ) with detection limits of 1.8 and 2.9 μg L -1 for Pb and Cd, respectively. The accuracy of the method was validated by analyzing metal contents in different spiked seawater samples and comparing these results to those obtained with the well-established anodic stripping voltammetry using the hanging mercury drop electrode. Moreover, a certified reference material was also used and the results obtained were satisfactory

  7. Sensitive and stable monitoring of lead and cadmium in seawater using screen-printed electrode and electrochemical stripping analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gueell, Raquel [ICREA and Nanobioelectronics and Biosensors Group, Institut Catala de Nanotecnologia, Bellaterra, Barcelona (Spain); Department of Chemistry, Universitat Autonoma de Barcelona, Bellaterra, Barcelona (Spain); Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Aragay, Gemma [ICREA and Nanobioelectronics and Biosensors Group, Institut Catala de Nanotecnologia, Bellaterra, Barcelona (Spain); Department of Chemistry, Universitat Autonoma de Barcelona, Bellaterra, Barcelona (Spain); Fontas, Claudia; Antico, Enriqueta [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Merkoci, Arben [ICREA and Nanobioelectronics and Biosensors Group, Institut Catala de Nanotecnologia, Bellaterra, Barcelona (Spain); Department of Chemistry, Universitat Autonoma de Barcelona, Bellaterra, Barcelona (Spain)], E-mail: arben.merkoci.icn@uab.es

    2008-10-10

    Sensitive and stable monitoring of heavy metals in seawater using screen-printed electrodes (SPE) is presented. The analytical performance of SPE coupled with square wave anodic stripping voltammetry (SWASV) for the simultaneous determination of Pb and Cd in seawater samples, in the low {mu}g L{sup -1} range, is evaluated. The stripping response for the heavy metals following 2 min deposition was linear over the concentration range examined (10-2000 {mu}g L{sup -1}) with detection limits of 1.8 and 2.9 {mu}g L{sup -1} for Pb and Cd, respectively. The accuracy of the method was validated by analyzing metal contents in different spiked seawater samples and comparing these results to those obtained with the well-established anodic stripping voltammetry using the hanging mercury drop electrode. Moreover, a certified reference material was also used and the results obtained were satisfactory.

  8. Adsorptive stripping voltammetry for simultaneous determination of hydrochlorothiazide and triamterene in hemodialysis samples using a multi-walled carbon nanotube-modified glassy carbon electrode.

    Science.gov (United States)

    Hudari, Felipe Fantinato; Souza, João Carlos; Zanoni, Maria Valnice Boldrin

    2018-03-01

    Hemodialysis is the most commonly used method for the treatment of chronic kidney disease. In this procedure, some patients use diuretics to control weight gain and blood pressure. In this work, a voltammetric sensor based on a glassy carbon electrode modified with carbon nanotubes (GCE/MWCNT) is described for the simultaneous determination of the diuretics hydrochlorothiazide (HCT) and triamterene (TRT). The oxidation of the diuretics on the GCE/MWCNT surface was observed at 1.01 and 1.17V for HCT and TRT, respectively, allowing simultaneous determination, which was not possible with the unmodified glassy carbon electrode. The GCE/MWCNT electrode provided 6-fold and 10-fold gains in anode peak intensity for HCT and TRT, respectively, compared to the unmodified electrode. After optimization of the conditions (pH, accumulation time, and accumulation potential), analytical curves were constructed for the analytes in the range from 1.0 × 10 -7 to 2.0 × 10 -5 molL -1 . The detection limits for HCT and TRT were 2.8 × 10 -8 and 2.9 × 10 -8 molL -1 , respectively. A high performance liquid chromatography method with diode array detection was also developed for the determination of HCT and TRT in hemodialysis samples, for comparison with the electroanalytical method. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Experimental designs in the development of a new method for the sensitive determination of cadmium in seawater by adsorptive cathodic stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Jurado-Gonzalez, Jose A.; Galindo-Riano, Maria D.; Garcia-Vargas, Manuel

    2003-07-08

    A new differential pulse adsorptive cathodic stripping voltammetric (DPAdCSV) method for the direct determination of cadmium at subnanomolar levels in saline waters based on metal complexation with 2-acetylpyridine salicyloylhydrazone (APSH) and subsequent adsorptive deposition onto a hanging mercury drop electrode (HMDE) is presented. A study strategy based on experimental designs has been followed. Operating conditions were improved with exploratory (Plackett-Burman) and surface response (central composite) experimental designs, involving several chemical and instrumental parameters (pH, ligand concentration, pulse amplitude, time interval for voltage step, voltage step, deposition potential and deposition time). Analytical parameters as repeatability, linearity and accuracy were also investigated and a detection limit (DL) of 0.06 nM was achieved which could be lowered by extending the adsorption time. The interference of other metals and major salts present in seawater was also studied. The method was validated with reference water samples: NIST-SRM 1643d and BCR-CRM 505, showing good concordance with the certified values.

  10. A Simple, Fast, and Inexpensive Simultaneous Determination of Trace Bismuth(III) and Lead(II) in Water Samples by Adsorptive Stripping Voltammetry.

    Science.gov (United States)

    Grabarczyk, Malgorzata; Adamczyk, Marzena

    2017-01-01

    A simple, fast, and inexpensive voltammetric method for the simultaneous determination of trace bismuth(III) and lead(II) using (Hg(Ag)FE) as a working electrode was optimized. For adsorptive stripping voltammetric determination of Bi(III) and Pb(II) in a single scan, the cupferron was applied as a complexing agent. Experimental conditions under which these elements can be simultaneously detected include 0.1 mol L -1 acetate buffer (pH = 4.6), 1 × 10 -4  mol L -1 cupferron, accumulation potential -0.05 V, and accumulation time 30 s. The experiments were performed without deaeration of the solutions. The calibration graph was linear from 2 × 10 -9  mol L -1 to 1 × 10 -7  mol L -1 for the simultaneous presence of bismuth and lead. The detection limits for preconcentration time of 30 s were 6.7 × 10 -10  mol L -1 and 8.8 × 10 -10  mol L -1 for bismuth and lead, respectively. The application of this procedure was tested by analyzing certified reference material (SPS-WW1 Wastewater) and Lake Zemborzyce water (eastern areas of Poland).

  11. The use of differential pulse anodic stripping voltammetry and diffusive gradient in thin films for heavy metals speciation in soil solution

    Czech Academy of Sciences Publication Activity Database

    Jaklová Dytrtová, J.; Šestáková, Ivana; Jakl, M.; Száková, J.; Miholová, D.; Tlustoš, P.

    2008-01-01

    Roč. 6, č. 1 (2008), s. 71-79 ISSN 1895-1066 R&D Projects: GA ČR GA521/06/0496 Institutional research plan: CEZ:AV0Z40400503 Keywords : heavy metal s * soil solution * speciation Subject RIV: CG - Electrochemistry Impact factor: 0.741, year: 2008

  12. The direct determination, by differential pulse anodic-stripping voltammetry at the thin mercury-film electrode, of cadmium, lead and copper

    International Nuclear Information System (INIS)

    Lee, A.F.

    1981-01-01

    This report describes the development and application of a voltammetric procedure for the direct, simultaneous determination of cadmium, lead, and copper in three SAROC reference materials (carbonatite, magnesite, and quartz). The electrolyte was a mixture of 1 M ammonium chloride, 0,1 M citric acid, and 0,025 M ascorbic acid. No interferences were encountered from Fe(III), As(III), Sb(V), Tl(I), or In(III) at the concentrations present in the samples. Intermetallic interferences were eliminated by the use of thin mercury-film electrodes not less than 80nm thick. Limits of detection were determined by the degree to which the supporting electrolyte could be purified, and were estimated to be 10ng/g, 250ng/g, and 150ng/g for cadmium, lead, and copper respectively

  13. Trace metal detection in Sibenik Bay, Croatia: Cadmium, Lead and Copper with anodic stripping voltammetry and manganese via sonoelectrochemistry. a case study

    International Nuclear Information System (INIS)

    Omanovic, D.; Kwokal, Z.; Goodwin, A.; Lawrence, A.; Banks, C.E.; Compton, R.G.; Komersky-Lovric, S.

    2006-01-01

    The vertical profiles of the concentration of reactive Mn and total concentrations of Cd, Pb, and Cu ions in the water column of the Sibenik Bay (Krka river estuary) were determined. The measured ranges of concentrations are: 60-1300 ng 1 -1f or Mn, 5-13 ng 1 -1 for Cd, 70-230 ng 1 -1f or Pb, and 375-840 ng 1 -1f or Cu. These values are comparable with the concentrations found in the unpolluted estuaries. The Krka river estuary is highly stratified, with the measured salinity gradient of 20% within a half meter of the freshwater-seawater interface . The main changes in the vertical profiles of the measured parameters occur in the freshwater-seawater interface: the temperature increases for 1 d ig C and the pH decreases for 0.1 unit, whereas the metal concentrations show different behaviour. Generally, Mn, Pb, and Cd ions show the increase of concentrations in the freshwater-seawater interface , while copper concentration profile indicates anthropogenic pollution in the brackish layer caused by agriculture activities and by the paint with copper basis used as an antifoulant biocide for the ships. UV-digested samples show an increase in manganese concenbations for at least 3.5 times comparing to non UV-digested. This suggests that in natural water manganese exists mainly in the form of inert complexes and as associated to particulate matter (about 70-80%). UV irradiation has no influence on the concentration of cadmium, while for lead an increase of 50% in the seawater layer is observed. The twofold increase of the copper concentration in the upper freshwater layer and at least the fourfold one in the seawater layer were measured in the UV-digested samples. These results show that copper is strongly bound to inert complexes, and that UV-digestion is necessary step in determination of the total metal concentrations in natural water samples. No significant increase of the metal concentrations in the deeper seawater layer was observed, indicating the absence of the processes of remobilization or dissolution of metals from the sediment. Presented results confirm that the new method for the determination of manganese by CSV on boron-doped diamond electrode with ultrasound enhanced accumulation can be successfully applied to natural waters

  14. Part I. Application of pulse polarography and pulse anodic stripping to the determination of selected heavy metals in natural waters. Part II. Application of controlled potential coulometric techniques to the determination of uranium

    International Nuclear Information System (INIS)

    Crosmun, S.T.

    1977-06-01

    The use of a thin mercury film wax-impregnated graphite electrode for the simultaneous determination of cadmium, lead and zinc in an acetate buffer by differential pulse anodic stripping voltammetry is described. Optimal instrumental parameters for maximum resolution and sensitivity for simultaneous analysis of these three elements in natural waters are discussed. The interference of copper with the determination of zinc is investigated in detail. An optimal mercury film thickness for this electrode is suggested. A method utilizing differential pulse polarography for the determination of chromium (VI) in natural water is described. Additions of 0.62 μg Cu(II) ml -1 and 0.55 μg Fe(III) ml -1 did not interfere with the determination of 0.050 μg Cr(VI) ml -1 . The natural water samples containing Cr(VI) were buffered to approximately pH 7 with 0.1 M ammonium acetate and 0.005 M ethylenediamine and analyzed. Natural water samples of chromium from 0.035 μg to 2.0 μg.ml -1 may be analyzed directly without further preparation. The detection limit is 0.010 μg.ml -1 . A novel, highly efficient cell with integral stirrer for controlled potential coulometry is described. This cell was used to demonstrate the feasibility of determining uranium (VI) by predictive coulometry. A PDP 8/I minicomputer was used to predict the coulometric endpoint with high accuracy within 2.5 minutes in a titration which normally takes about 10 minutes. This technique was shown to yield acceptable results even in the presence of an interfering phosphate matrix

  15. Rapid, quantitative and sensitive immunochromatographic assay based on stripping voltammetric detection of a metal ion label

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Fang; Wang, Kaihua; Lin, Yuehe

    2005-10-10

    A novel, sensitive immunochromatographic electrochemical biosensor (IEB) which combines an immunochromatographic strip technique with an electrochemical detection technique is demonstrated. The IEB takes advantages of the speed and low-cost of the conventional immunochromatographic test kits and high-sensitivity of stripping voltammetry. Bismuth ions (Bi3+) have been coupled with the antibody through the bifunctional chelating agent diethylenetriamine pentaacetic acid (DTPA). After immunoreactions, Bi3+ was released and quantified by anodic stripping voltammetry at a built-in single-use screen-printed electrode. As an example for the applications of such novel device, the detection of human chorionic gonadotronphin (HCG) in a specimen was performed. This biosensor provides a more user-friendly, rapid, clinically accurate, and less expensive immunoassay for such analysis in specimens than currently available test kits.

  16. Study of cadmium-humic interactions and determination of stability constants of cadmium-humate complexes from their diffusion coefficients obtained by scanned stripping voltammetry and dynamic light scattering techniques.

    Science.gov (United States)

    Chakraborty, Parthasarathi

    2010-02-05

    Diffusion coefficients of Cd-humate complexes are dependent on pH and [Cd]/[Humic] Acid (HA)] ratio in a Cd-HA system. These two factors mainly control the mass transport and complexation kinetics of Cd that may influence bioavailability and toxicity of Cd species in environmental systems. Determination of diffusion coefficients of Cd-HA systems by Scanned stripping voltammetry and dynamic light scattering techniques can provide a better understanding of the systems and can be very useful for extracting other speciation parameters of the systems. This study revealed that Cd(2+) ion along with small dynamic Cd complexes was predominantly present in a Cd-HA system at pH 5 with high diffusion coefficients. HA molecules were in aggregated form at pH 5. However, HA molecules were in disaggregated form at pH 6 and concentrations of Cd(2+) ion and small Cd-dynamic complexes decreased with a decrease in diffusion coefficients of Cd complexes at this pH due to formation of Cd-humate complexes. No further decrease in the hydrodynamic radii of HA was observed with the increase of pH from 6 to 7. The Cd-humate system partially lost its lability at pH 7. Conditional stability constants were calculated for Cd-humate complexes by combining the diffusion coefficient data obtained by two techniques. The log K values calculated in this study are in good agreement with the data available from the literature. Copyright 2009 Elsevier B.V. All rights reserved.

  17. Clay matrix voltammetry

    International Nuclear Information System (INIS)

    Perdicakis, Michel

    2012-01-01

    Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS 2 ), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

  18. Adsorptive stripping voltammetric methods for determination of aripiprazole

    Directory of Open Access Journals (Sweden)

    Derya Aşangil

    2012-06-01

    Full Text Available Anodic behavior of aripiprazole (ARP was studied using electrochemical methods. Charge transfer, diffusion and surface coverage coefficients of adsorbed molecules and the number of electrons transferred in electrode mechanisms were calculated for quasi-reversible and adsorption-controlled electrochemical oxidation of ARP at 1.15 V versus Ag/AgCl at pH 4.0 in Britton–Robinson buffer (BR on glassy carbon electrode. Voltammetric methods for direct determination of ARP in pharmaceutical dosage forms and biological samples were developed. Linearity range is found as from 11.4 μM (5.11 mg/L to 157 μM (70.41 mg/L without stripping mode and it is found as from 0.221 μM (0.10 mg/L to 13.6 μM (6.10 mg/L with stripping mode. Limit of detection (LOD was found to be 0.11 μM (0.05 mg/L in stripping voltammetry. Methods were successfully applied to assay the drug in tablets, human serum and human urine with good recoveries between 95.0% and 104.6% with relative standard deviation less than 10%. Keywords: Adsorptive stripping voltammetry, Aripiprazole, Electrochemical behavior, Human serum and urine, Pharmaceuticals

  19. Voltammetry Method Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, N. [Argonne National Lab. (ANL), Argonne, IL (United States); Pereira, C. [Argonne National Lab. (ANL), Argonne, IL (United States); Willit, J. [Argonne National Lab. (ANL), Argonne, IL (United States); Williamson, M. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-07-29

    The purpose of the ANL MPACT Voltammetry project is to evaluate the suitability of previously developed cyclic voltammetry techniques to provide electroanalytical measurements of actinide concentrations in realistic used fuel processing scenarios. The molten salts in these scenarios are very challenging as they include high concentrations of multiple electrochemically active species, thereby creating a variety of complications. Some of the problems that arise therein include issues related to uncompensated resistance, cylindrical diffusion, and alloying of the electrodeposited metals. Improvements to the existing voltammetry technique to account for these issues have been implemented, resulting in good measurements of actinide concentrations across a wide range of adverse conditions.

  20. A research of portable voltammetry system for sensing heavy metal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Myoung; Lee, Dong Jin; Park, Joong Hark [KAERI, Daejeon (Korea, Republic of)

    2010-12-15

    In this research, nano-bismuth(Bi) sensor electrode with high sensitivity and reliability has been developed for the trace analyses of heavy metals (Zn, Cd, Pb, Tl) in aqueous system. The Bi nanopowders with various particle size distributions were prepared by gas condensation method and the prepared nanopowders were strongly fixed on the screen-printed carbon or silver paste electrode. The sensitivity and detection limit of sensor electrodes were quantitatively estimated from the linear relationship between the heavy metal concentration and the peak current of square-wave anodic stripping voltammogram. From the comparison of sensor characteristics of nano-Bi electrode with ICP method and Hg/Bi film electrodes, it is suggested that the nano-Bi electrode can detect the traces of heavy metals smaller than 1ppb which can not be detected by ICP. In particular, the nano-Bi electrode exhibited a superior sensor characteristics such as detection limit, precision and accuracy of measurements, compared to the Hg/Bi film electrodes. Furthermore, the hardware and software for the portable sensor system (voltammetry) were manufactured, which makes the commercialization of the developed sensor technology earlier

  1. Cyclic voltammetry of dental amalgams.

    Science.gov (United States)

    Horasawa, N; Nakajima, H; Ferracane, J L; Takahashi, S; Okabe, T

    1996-05-01

    This study used cyclic voltammetry to examine the effect of the composition of dental amalgams on their electrochemical behavior, including reactions occurring outside of oral conditions. Amalgams (residual mercury 47.5%) were prepared using two low-copper (3 wt% Cu) powders and five high-copper powders (40-80 wt% Ag, 12-30 wt% Cu) with and without zinc (1.5 wt%). Cyclic voltammograms were obtained at 37 degrees C in 1.0% NaCl scanning at 2 mV/s in the potential range from -1.5 V to +0.8 V vs. Ag/AgCl. During the anodic scans, AgCl and Hg2Cl2 films were formed on all amalgams except the one with only 40 wt% Ag. In all high-copper amalgams, a prominent Cu (oxidation) peak was found at -0.1 V, indicating the release of copper during corrosion. Zinc affected the oxidation process for both low- and high-copper amalgams. When zinc was absent, a peak for Sn2+ oxidation appeared at -0.4 V. When zinc was present, a Sn4+ oxidation peak was revealed at -0.6 V. In some amalgams, there was evidence of the selective corrosion (pitting corrosion) of tin and copper. In the lowest silver-content amalgam, no protective films were formed, which is indicative of its poor corrosion resistance. As expected, in all the low-copper amalgams, an extreme increase in current density was recorded immediately at 0 V, due to the release of tin from gamma 2. Cyclic voltammetry is useful for the rapid examination (less than an hour) of the electrochemical behavior of amalgams, specifically to obtain information on the formation of compounds and the sequences of electrochemical reactions.

  2. Galinstan in voltammetry

    OpenAIRE

    Channaa, Hanan (geb. Zeyat)

    2010-01-01

    Abstract and outlook The aim of this thesis was to provide a novel, liquid electrode material with highly reproducible and renewable surface as working electrode in polarography and voltammetry, which is besides less toxic than mercury. Our patent pending "procedure of voltammetric measuring of a measuring substance and a device for a voltammetric measurement" could demonstrate the use of a liquid metal electrode on the basis of detailed examples. Initial doubts concerning the employ...

  3. Comparison of analytical possibilities of inversion voltammetry of tellurium with cathodic and anodic potential scanning taking layer-by-layer analysis of GaAs-Te films as example

    International Nuclear Information System (INIS)

    Kaplin, A.A.; Portnyagina, Eh.O.; Gridaev, V.F.

    1979-01-01

    Possibility of application in analytical purposes of the process of tellurium precipitation electrosolution from the surfaces of graphite and mercury-graphite electrodes at the cathode scanning of the potential is shown. As a result of comparison of direct and inversion scanning with cathodic and anodic scanning of the potential, variants of voltammetric method of tellurium determination in artificial solutions and, taking the developed method of layer-by-layer analysis of the GaAsTe films as an example, advantage of mercury-graphite electrode with cathodic scanning as compared to graphite electrode with cathode scanning of the potential is shown. Reproducibility of the GaAs film analysis results according to anodic and cathodic tellurium peaks is satisfactory. Maximum deviation from the results of analysis of oxidation peaks and tellurium peduction does not exceed 15 rel. %. Thus, for tellurium concentrations, exceeding 5x10 -6 g-ion/l, both anodic and cathodic scanning of the potential can be used, though error in tellurium determination according to cathodic peaks is 1.5-2.0 times higher. At tellurium amounts lower 5x10 -6 g-ion/l the determination should be carried out according to the peaks of tellurium anodic oxidation from the surface of graphite electrode or according to the peaks of tellurium cathodic reduction from the surface of mercury-graphite electrode

  4. Stripping Voltammetric Determination Of Zinc, Cadmium, Lead And Copper In Blood Samples Of Children Aged Between 3 Months And 6 years

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Mahajan

    2005-05-01

    Full Text Available Blood samples of 160 children, ranging age between 3 months and 6 years were selected from five different parts of Amritsar district of Punjab (India and were analyzed for Zn, Cd, Pb and Cu using anodic stripping voltammetry. Large variations in the results have been correlated to the area inhabited, age differences and other factors. It was found that the areas, more prone to environmental stress, had shown more quantities of these metals in blood samples in comparison to those which were taken from safer sites. Similarly the younger children lesser exposed to environmental pollution had shown comparatively lesser quantity of these metals in comparison to older objects.

  5. Adsorptive Transfer Stripping AC Voltammetry of DNA Complexes with Intercalators

    Czech Academy of Sciences Publication Activity Database

    Fojta, Miroslav; Havran, Luděk; Fulnečková, Jana; Kubičárová, Tatiana

    2000-01-01

    Roč. 12, č. 12 (2000), s. 926-934 ISSN 1040-0397 R&D Projects: GA AV ČR IAA4004801; GA ČR GA204/98/P091; GA ČR GV204/97/K084 Institutional research plan: CEZ:AV0Z5004920 Subject RIV: BO - Biophysics Impact factor: 1.972, year: 2000

  6. Characterisation of biosynthesised silver nanoparticles by scanning electrochemical microscopy (SECM) and voltammetry.

    Science.gov (United States)

    Battistel, Dario; Baldi, Franco; Gallo, Michele; Faleri, Claudia; Daniele, Salvatore

    2015-01-01

    Silver nanoparticles (AgNPs) were biosynthesised by a Klebsiella oxytoca strain BAS-10, which, during its growth, is known to produce a branched exopolysaccharide (EPS). Klebsiella oxytoca cultures, treated with AgNO3 and grown under either aerobic or anaerobic conditions, produced silver nanoparticles embedded in EPS (AgNPs-EPS) containing different amounts of Ag(0) and Ag(I) forms. The average size of the AgNPs-EPS was determined by transmission electron microscopy, while the relative abundance of Ag(0)- or Ag(I)-containing AgNPs-EPS was established by scanning electrochemical microscopy (SECM). Moreover, the release of silver(I) species from the various types of AgNPs-EPS was investigated by combining SECM with anodic stripping voltammetry. These measurements allowed obtaining information on the kinetic of silver ions release from AgNPs-EPS and their concentration profiles at the substrate/water interface. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Raspberry-Like Bismuth Oxychloride on Mesoporous Siliceous Support for Sensitive Electrochemical Stripping Analysis of Cadmium.

    Science.gov (United States)

    Song, Yiyan; Xu, Zhihui; Yu, Xinyu; Shi, Xueyan; Jiang, Huijun; Li, Xiaoming; Kong, Yan; Xu, Qin; Chen, Jin

    2017-05-13

    BiOCl-SiO₂ KIT-6 composite materials with raspberry-like structures are facilely prepared under hydrothermal conditions. The mesoporous siliceous support of SiO₂ KIT-6-incorporated BiOCl with enlarged yet refined surface morphology characterized by physiochemical methods exhibits an improved electrochemical performance. A sensitive electrochemical detection method of cadmium concentration using square wave anodic stripping voltammetry was developed based on BiOCl-SiO₂ KIT-6 composite-modified glassy carbon electrodes, which displayed wide linear ranges of 0.5 to 10 μg/L and 10 to 300 μg/L and a detection limit of 65 ng/L. The sensitive, versatile and eco-friendly sensor was successfully applied for the determination of cadmium-spiked human blood samples.

  8. Elastic strips

    OpenAIRE

    Chubelaschwili, David; Pinkall, Ulrich

    2010-01-01

    Motivated by the problem of finding an explicit description of a developable narrow Moebius strip of minimal bending energy, which was first formulated by M. Sadowsky in 1930, we will develop the theory of elastic strips. Recently E.L. Starostin and G.H.M. van der Heijden found a numerical description for an elastic Moebius strip, but did not give an integrable solution. We derive two conservation laws, which describe the equilibrium equations of elastic strips. In applying these laws we find...

  9. CO-Tolerant Pt–BeO as a Novel Anode Electrocatalyst in Proton Exchange Membrane Fuel Cells

    Directory of Open Access Journals (Sweden)

    Kyungjung Kwon

    2016-05-01

    Full Text Available Commercialization of proton exchange membrane fuel cells (PEMFCs requires less expensive catalysts and higher operating voltage. Substantial anodic overvoltage with the usage of reformed hydrogen fuel can be minimized by using CO-tolerant anode catalysts. Carbon-supported Pt–BeO is manufactured so that Pt particles with an average diameter of 4 nm are distributed on a carbon support. XPS analysis shows that a peak value of the binding energy of Be matches that of BeO, and oxygen is bound with Be or carbon. The hydrogen oxidation current of the Pt–BeO catalyst is slightly higher than that of a Pt catalyst. CO stripping voltammetry shows that CO oxidation current peaks at ~0.85 V at Pt, whereas CO is oxidized around 0.75 V at Pt–BeO, which confirms that the desorption of CO is easier in the presence of BeO. Although the state-of-the-art PtRu anode catalyst is dominant as a CO-tolerant hydrogen oxidation catalyst, this study of Be-based CO-tolerant material can widen the choice of PEMFC anode catalyst.

  10. The effect of methanol and ethanol cross-over on the performance of PtRu/C-based anode DAFCs

    Energy Technology Data Exchange (ETDEWEB)

    Song, Shuqin; Zhou, Weijiang; Liang, Zhenxing; Sun, Gongquan; Xin, Qin [Direct Alcohol Fuel Cell Laboratory, Dalian Institute of Chemical Physics, CAS, P. O. Box 110, 116023 Dalian (China); Cai, Rui [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, CAS, P. O. Box 110, 116023 Dalian (China); Stergiopoulos, Vaios; Tsiakaras, Panagiotis [Department of Mechanical and Industrial Engineering, School of Engineering, University of Thessalia, Pedion Areos, 383 34 Volos (Greece)

    2005-01-10

    In the present work, the cross-over rates of methanol and ethanol, respectively, through Nafion{sup (R)}-115 membranes at different temperatures and different concentrations have been measured and compared. The changes of Nafion{sup (R)}-115 membrane porosity in the presence of methanol or ethanol aqueous solutions were also determined by weighing vacuum-dried and alcohol solution-equilibrated membranes. The techniques of anode polarization and adsorption stripping voltammetry were applied to compare the electrochemical activity and adsorption ability, respectively. To investigate the consequences of methanol and ethanol permeation from the anode to the cathode on the performance of direct alcohol fuel cells (DAFCs), single DAFC tests, with methanol or ethanol as the fuel, have been carried out and the corresponding anode and cathode polarizations versus dynamic hydrogen electrode (DHE) were also performed. The effect of alcohol concentration on the performance of PtRu/C anode-based DAFCs was investigated. It was found that ethanol shows lower cross-over rates than methanol through the Nafion{sup (R)} membrane in spite of the higher membrane porosity resulted in presence of ethanol aqueous solutions. Furthermore, it was found that ethanol presents less negative effect on the cathode performance due to both its smaller permeability through Nafion{sup (R)} membrane and its slower electrochemical oxidation kinetics over Pt/C cathode.

  11. Monitoring of epitaxial graphene anodization

    International Nuclear Information System (INIS)

    Vagin, Mikhail Yu.; Sekretaryova, Alina N.; Ivanov, Ivan G.; Håkansson, Anna; Iakimov, Tihomir; Syväjärvi, Mikael; Yakimova, Rositsa; Lundström, Ingemar; Eriksson, Mats

    2017-01-01

    Anodization of a graphene monolayer on silicon carbide was monitored with electrochemical impedance spectroscopy. Structural and functional changes of the material were observed by Raman spectroscopy and voltammetry. A 21 fold increase of the specific capacitance of graphene was observed during the anodization. An electrochemical kinetic study of the Fe(CN) 6 3−/4− redox couple showed a slow irreversible redox process at the pristine graphene, but after anodization the reaction rate increased by several orders of magnitude. On the other hand, the Ru(NH 3 ) 6 3+/2+ redox couple proved to be insensitive to the activation process. The results of the electron transfer kinetics correlate well with capacitance measurements. The Raman mapping results suggest that the increased specific capacitance of the anodized sample is likely due to a substantial increase of electron doping, induced by defect formation, in the monolayer upon anodization. The doping concentration increased from less than 1 × 10 13 of the pristine graphene to 4–8 × 10 13 of the anodized graphene.

  12. Disposable screen-printed bismuth electrode modified with multi-walled carbon nanotubes for electrochemical stripping measurements.

    Science.gov (United States)

    Niu, Xiangheng; Zhao, Hongli; Lan, Minbo

    2011-01-01

    Integrating the advantages of screen printing technology with the encouraging electroanalytical characteristic of metallic bismuth, we developed an ultrasensitive and disposable screen-printed bismuth electrode (SPBE) modified with multi-walled carbon nanotubes (MWCNTs) for electrochemical stripping measurements. Metallic bismuth powders and MWCNTs were homogeneously mixed with graphite-carbon ink to mass-prepare screen-printed bismuth electrode doped with multi-walled carbon nanotubes (SPBE/MWCNT). The electroanalytical performance of the prepared SPBE/MWCNT was intensively evaluated by measuring trace Hg(II) with square-wave anodic stripping voltammetry (SWASV). The results indicated that the SPBE modified with 2 wt% MWCNTs could offer a more sensitive response to trace Hg(II) than the bare SPBE. The stripping current obtained at SPBE/MWCNT was linear with Hg(II) concentration in the range from 0.2 to 40 µg/L (R(2) = 0.9976), with a detection limit of 0.09 µg/L (S/N = 3) under 180 s accumulation. The proposed "mercury-free" electrode, with extremely simple preparation and ultrahigh sensitivity, holds wide application prospects in both environmental and industrial monitoring. 2011 © The Japan Society for Analytical Chemistry

  13. Solar UV Photooxidation as Pretreatment for Stripping Voltammetric Trace Metal Analysis in River Water

    Directory of Open Access Journals (Sweden)

    Gelaneh Woldemichael

    2011-01-01

    Full Text Available The application of solar ultraviolet radiation as sample pretreatment or preparation step in stripping voltammetric analysis of trace metals in presence of low levels of dissolved organic carbon (DOC natural water samples (river water was studied. River water samples were collected from downstream of Warnow river (Germany and acidified to pH of 2±0.2 (by addition of 1 mL of ultrapure 65% HNO3 per liter sample. Furthermore, 100 μL/L of hydrogen peroxide solution (ultrapure, 30% H2O2 was added to the samples as photochemical reaction initiator. The samples were transferred to polyethylene terephthalate (PET bottles and irradiated with solar radiation of UV-A intensity of 3.6 mW/m2 for six hours, and the concentrations of Zn, Cd, Pb, and Cu were determined by differential pulse anodic stripping voltammetry (DPASV. The comparison of the values with the results obtained for the original untreated sample and artificial UV-treated one proved that solar UV radiation can be applied to the digestion of dissolved organic carbon in trace metal analysis in natural waters like river water, lake waters, well waters, and so forth.

  14. Cyclic voltammetry and reduction mechanistic studies of ...

    African Journals Online (AJOL)

    styrylpyrylium perchlorates have been evaluated using cyclic voltammetry, in comparison to their non-methylated derivatives values. The reduction peak of all studied compounds remained chemically irreversible. The presence of the ...

  15. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  16. Characterization of proton exchange membrane fuel cell anode catalysts prepared by colloid method

    Energy Technology Data Exchange (ETDEWEB)

    Franco, E.G.; Dantas-Filho, P.L.; Burani, G.F. [Universidade de Sao Paulo (IEE/USP), Sao Paulo, SP (Brazil). Instituto de Eletrotecnica e Energia

    2009-07-01

    Full text: Anode catalysts for Proton Exchange Membrane Fuel Cell (PEMFC) were synthesized by the colloid method and their structure was investigated by transmission electron microscopy (TEM), energy dispersive analyses (EDS), X-ray Diffraction (XRD). The electrochemical behavior of the anode catalyst was analyzed by cyclic voltammetry (CV) and polarization curves (UxI). (author)

  17. Fundamental Investigation of Si Anode in Li-Ion Cells

    Science.gov (United States)

    Wu, James J.; Bennett, William R.

    2012-01-01

    Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is approximately 10 times of graphite and it is an abundant element on earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of Si anode during the first cycle, the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes.

  18. Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

    Science.gov (United States)

    Wu, James J.; Bennett, William R.

    2012-01-01

    Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is 10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

  19. Simultaneous DPV determination of morphine and codeine using dsDNA modified screen printed electrode strips coupled with electromembrane extraction

    Directory of Open Access Journals (Sweden)

    Rouhollah Feizbakhsh

    2016-01-01

    Full Text Available In this work a sensitive electrochemical sensor for simultaneous determination of morphine and codeine constructed by application of disposable screen printed carbon electrode strips (SPCE modified by double strand (ds calf thymus DNA. According to the results of the modified SPCE strips and experimented parameters, we observed a considerable shift between potentials of morphine and codeine current peaks. Related to these observed shifts, we studied on the effect of the concentration of modifier and pH value on the anodic oxidation pattern of morphine and codeine in the case of optimize the method to get better signals with maximum potential distance. Also to boosting the LODs of this electroanalytical method coupled with an electro-membrane preconcentration (EME step. The calibration curve which was plotted by the variation of differential pulse voltammetry (DPV currents as a function of different morphine and codeine concentration were linear within the range of 0.7– 40 µM and 2.3- 40 µM for morphine and codeine respectively. Also the limits of detection were 0.07 µM and 0.23 µM, respectively. Finally, the proposed method was able to determine morphine and codeine simultaneously and effectively in urinary real samples

  20. Steady state oxygen reduction and cyclic voltammetry

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Karlberg, Gustav; Jaramillo, Thomas

    2008-01-01

    The catalytic activity of Pt and Pt3Ni for the oxygen reduction reaction is investigated by applying a Sabatier model based on density functional calculations. We investigate the role of adsorbed OH on the activity, by comparing cyclic voltammetry obtained from theory with previously published...

  1. Cathode readout with stripped resistive drift tubes

    International Nuclear Information System (INIS)

    Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhiltsov, V.E.

    1995-01-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. (orig.)

  2. Modification of Poly- and Oligosaccharides with Os(VI) pyridine. Voltammetry of the Os(VI) Adducts Obtained by Ligand Exchange

    Czech Academy of Sciences Publication Activity Database

    Trefulka, Mojmír; Paleček, Emil

    2013-01-01

    Roč. 25, č. 8 (2013), s. 1813-1817 ISSN 1040-0397 R&D Projects: GA ČR(CZ) GAP301/11/2055 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : OS(VI)-MODIFIED POLYSACCHARIDES * STRIPPING VOLTAMMETRY * TRANS-ESTERIFICATION Subject RIV: BO - Biophysics Impact factor: 2.502, year: 2013

  3. Evaluating the Passivation of Corrosion of API-X100 Steel with Cyclic Voltammetry

    Science.gov (United States)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2017-10-01

    In this research, cyclic voltammetry, in oxygen-free low bicarbonate-carbonate solutions, was used to study the corrosion reactions of a high-strength steel, API-X100. With cycles of different scan ranges, the effects of cycling, transpassivation, and cathodic reduction on the electrochemistry of the passive films were analyzed. It was found that carbonate in higher concentrations reduces the anodic activity and the cathodic reactions of the surface. Bicarbonate in small concentrations in solutions that contained low carbonate concentrations catalyzed dissolution and disrupted the formation of the passive films, in reference to the measured anodic currents. From the experiments, there was electrochemical evidence that with more cycles, the passive films were growing thicker, the transpassivation deteriorated the passive films, and during the cathodic reduction, the dissolution was occurring at lower potentials to facilitate later the passivation at higher potentials.

  4. 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

    Directory of Open Access Journals (Sweden)

    Guo Zhao

    2016-09-01

    Full Text Available 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.

  5. Voltammetry at micro-mesh electrodes

    Directory of Open Access Journals (Sweden)

    Wadhawan Jay D.

    2003-01-01

    Full Text Available The voltammetry at three micro-mesh electrodes is explored. It is found that at sufficiently short experimental durations, the micro-mesh working electrode first behaves as an ensemble of microband electrodes, then follows the behaviour anticipated for an array of diffusion-independent micro-ring electrodes of the same perimeter as individual grid-squares within the mesh. During prolonged electrolysis, the micro-mesh electrode follows that behaviour anticipated theoretically for a cubically-packed partially-blocked electrode. Application of the micro-mesh electrode for the electrochemical determination of carbon dioxide in DMSO electrolyte solutions is further illustrated.

  6. The importance of anodic discharge of H2O in anodic oxygen-transfer reactions

    International Nuclear Information System (INIS)

    Vitt, J.E.; Johnson, D.C.

    1992-01-01

    This paper discusses difference voltammetry at rotated disk electrodes which are applied to a study of several anodic O-transfer reactions that appear to occur concurrently with O 2 evolution. This voltammetric technique was useful for extracting the rotation-dependent component of the total current from the large, virtually rotation-independent current for O 2 evolution. Data for oxidation of I - at Pt, Au, Pd, Ir, and glassy carbon electrodes show that the E 1/2 for IO - 3 production is correlated with the overpotential for O 2 evolution at these electrode materials. Data obtained at an Ir electrode for various reactions with widely varying E o values reveal uniform E 1/2 values closely correlated with the potential for onset of O 2 evolution in both alkaline and acidic solutions. The results support the conclusion that the anodic discharge of H 2 O is a prerequisite of these anodic O-transfer mechanisms

  7. Varicose vein stripping

    Science.gov (United States)

    ... stripping; Venous reflux - vein stripping; Venous ulcer - veins Patient Instructions Surgical wound care - open Varicose veins - what to ask your doctor Images Circulatory system References American Family Physician. Management of varicose veins. www.aafp.org/afp/2008/ ...

  8. Voltammetry study of quinoxaline in aqueous electrolytes

    International Nuclear Information System (INIS)

    Milshtein, Jarrod D.; Su, Liang; Liou, Catherine; Badel, Andres F.; Brushett, Fikile R.

    2015-01-01

    Organic compounds have recently received considerable attention as active materials in redox flow batteries (RFBs) due to their good electrochemical reversibility, high theoretical energy densities, and promise for low cost production. Until now, organic active material candidates for aqueous RFBs have been limited to the quinone family, a set of aromatic-derived organic molecules, distinguished by an even number of ketone (R−C(=O)−R′) groups. This work aims to elucidate and optimize the electrochemical behavior of quinoxaline, an organic molecule consisting of fused benzene and pyrazine rings, in aqueous electrolytes. More than 30 electrolytes are screened by cyclic voltammetry, and the five most promising electrolytes are investigated further using rotating disk voltammetry. Electrochemical behavior of quinoxaline shows pH dependent thermodynamics and reaction mechanisms, while chloride-containing supporting electrolytes greatly enhance solubility. This study sheds light on the promising characteristics of quinoxaline as a low potential compound for aqueous RFBs; quinoxaline has a redox potential of E° ≈ −0.02 V vs. RHE, is soluble up to ∼4.5 M in water, exhibits a two-electron transfer capability, and possesses a low molecular weight (130.15 g mol −1 ), resulting in a theoretical capacity of 410 mAh g −1 .

  9. Lateral flow strip assay

    Science.gov (United States)

    Miles, Robin R [Danville, CA; Benett, William J [Livermore, CA; Coleman, Matthew A [Oakland, CA; Pearson, Francesca S [Livermore, CA; Nasarabadi, Shanavaz L [Livermore, CA

    2011-03-08

    A lateral flow strip assay apparatus comprising a housing; a lateral flow strip in the housing, the lateral flow strip having a receiving portion; a sample collection unit; and a reagent reservoir. Saliva and/or buccal cells are collected from an individual using the sample collection unit. The sample collection unit is immersed in the reagent reservoir. The tip of the lateral flow strip is immersed in the reservoir and the reagent/sample mixture wicks up into the lateral flow strip to perform the assay.

  10. 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......-ship code available at the department. It will be structured as a general preprocessor mainly to determine the hydrodynamic mass and damping. A strip processor including three different theories: A linear frequency domain strip theory, a quadratic strip theory and a nonlinear time domain strip theory...

  11. Determination of triazines in hemodialysis saline solutions by adsorptive stripping voltammetry after extraction in acetonitrile

    Directory of Open Access Journals (Sweden)

    Nascimento Paulo Cícero do

    2003-01-01

    Full Text Available A method for the voltammetric determination of 2-methylthio-4,6-dialkylamino-1,3,5-triazine (triazines herbicides in hemodialysis (HD saline solutions was developed. The herbicides were detected in the saline solutions at the hanging mercury drop electrode (HMDE with high sensitivities only after extraction of the analytes in acetonitrile (ACN. The salting out effect originated by the saline environment existing in the solutions enabled the extractions. The volume ratio between the saline and ACN phases was investigated in order to find the best sensitivity to detect the triazines. The speciation amongst them (ametryn, desmetryn, prometryn and terbutryn was not possible. Recoveries between 88 and 107% were calculated in spiked samples, and detection limits of 0.03 mumol L-1 were calculated for the triazines in the saline samples using this methodology.

  12. Wet digestion and differential pulse stripping voltammetry determination of total chromium in the millet

    Directory of Open Access Journals (Sweden)

    Yaqin LIU

    2015-06-01

    Full Text Available The chromium content of millet is measured by HNO3-H2O2 digestion and electrochemical method. In the DTPA-HAc-NaAc system, the oxidation peak current of amalgam formed by hexavalent chrome ion is obtained in the plating mercury electrode, and the pre-treatment technology of wet digestion can meet the electrochemical determination. The optimized detection condition of electrochemical method for hexavalent chrome ion is 130 ℃ of digestion solution, 10 mL hydrogen peroxide, 38 mL nitric acid, and neutral of pH. The linear correlation coefficient of electrochemical method is 0.99, and the recovery of standard addition is 90%~110%. This method can be used to trace chromium (Ⅵ determination in millet.

  13. Native and denatured bovine serum albumin. D.c. polarography, stripping voltammetry and constant current chronopotentiometry

    Czech Academy of Sciences Publication Activity Database

    Ostatná, Veronika; Uslu, B.; Dogan, B.; Ozkan, S.; Paleček, Emil

    2006-01-01

    Roč. 593, č. 1-2 (2006), s. 172-178 ISSN 0022-0728 R&D Projects: GA AV ČR(CZ) IAA500040513; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507 Keywords : protein electrochemistry * bovine serum albumin * native and denatured proteins Subject RIV: BO - Biophysics Impact factor: 2.339, year: 2006

  14. FIELD MEASUREMENT TECHNOLOGY FOR MERCURY IN SOIL AND SEDIMENT MTI INC'S PDV 6000 STRIPPING VOLTAMMETRY

    Science.gov (United States)

    Monitoring Technologies International Pty. Ltd. (MTI) has developed a Portable Digital Voltammeter (PDV) designed to identify and measure the concentration of heavy metal ions. MTI's PDV 6000 was demonstrated under the U.S. Environmental Protection Agency Superfund Innovative Tec...

  15. Determination of picogram quantities of oligodeoxynucleotides by stripping voltammetry at mercury modified graphite electrode surfaces

    Czech Academy of Sciences Publication Activity Database

    Hasoň, Stanislav; Jelen, František; Fojt, Lukáš; Vetterl, Vladimír

    2005-01-01

    Roč. 577, č. 2 (2005), s. 263-272 ISSN 0022-0728 R&D Projects: GA AV ČR IAA4004404; GA AV ČR(CZ) KJB4004305; GA AV ČR(CZ) IBS5004107; GA ČR(CZ) GA203/02/0422 Institutional research plan: CEZ:AV0Z50040507 Keywords : pyrolitic graphite electrode * glassy carbon electrode * mercury film electrodes Subject RIV: BO - Biophysics Impact factor: 2.223, year: 2005

  16. Double-Polymer-Modified Pencil Lead for Stripping Voltammetry of Perchlorate in Drinking Water

    Science.gov (United States)

    Izadyar, Anahita; Kim, Yushin; Ward, Michelle M.; Amemiya, Shigeru

    2012-01-01

    The inexpensive and disposable electrode based on a double-polymer-modified pencil lead is proposed for upper-division undergraduate instrumental laboratories to enable the highly sensitive detection of perchlorate. Students fabricate and utilize their own electrodes in the 3-4 h laboratory session to learn important concepts and methods of…

  17. Direct Determination of Nimesulide in Natural Waters and Wastewater by Cathodic Stripping Voltammetry.

    Science.gov (United States)

    Miranda, Luciane; Pereira, Vanessa C; Machado, Christiane S; Torres, Yohandra R; Dos Anjos, Vanessa E; Quináia, Sueli P

    2017-11-01

    Pharmaceuticals are included in a group of compounds considered as contaminants of emerging concern (CECs) in environmental matrices. The quantification of CECs is typically accomplished using chromatographic methods that require several sample pretreatment steps. The current study proposes a voltammetric method to quantify directly nimesulide (NIM) in aqueous samples. The voltammetric parameters were optimized and chosen based on the profile of the voltammograms and peak current intensity. The adequacy of the analytical method was evaluated using validation criteria, such as accuracy, selectivity, linearity, detection, and quantification limits. Linearity was assessed by a standard addition curve at a concentration range of 0.5-130 µg L -1 of NIM. The limit of quantification was 0.50 µg L -1 , with 60 s of preconcentration time. Accuracy was expressed as recovery percentages of NIM and ranged from 111.4 to 119.8%. The voltammetric method herein proposed has several advantages over others already used to determine NIM, such as fewer sample pretreatment steps, faster, and cheaper analyses. NIM was detected in wastewater samples at concentration levels ranging from 101.7 to 385.0 µg L -1 . This result is the first evidence about NIM occurrences in environmental matrices in the area surrounding the Itaipu Lake reservoir in Brazil.

  18. Protein-film voltammetry: A theoretical study of the temperature effect using square-wave voltammetry

    OpenAIRE

    Gulaboski, Rubin; Lovrić, Milivoj; Mirceski, Valentin; Bogeski, Ivan; Hoth, Markus

    2008-01-01

    Square-wave voltammetry of surface redox reactions is considered as an adequate model for a protein-film voltammetric setup. Here we develop a theoretical approach to analyze the effects of temperature on squarewave voltammograms. The performed simulations address the surface redox reactions featuring slow, modest and fast electron transfer. The theoretical calculations show that the temperature affects the squarewave voltammetric responses in a complex way resulting in a variety ...

  19. Determination of genotoxic effects of methidathion alkaline hydrolysis in human lymphocytes using the micronucleus assay and square-wave voltammetry.

    Science.gov (United States)

    Stivaktakis, Polychronis D; Giannakopoulos, Evangelos; Vlastos, Dimitris; Matthopoulos, Demetrios P

    2017-02-01

    The interaction of pesticides with environmental factors, such as pH, may result in alterations of their physicochemical properties and should be taken into consideration in regard to their classification. This study investigates the genotoxicity of methidathion and its alkaline hydrolysis by-products in cultured human lymphocytes, using the square-wave voltammetry (square wave-adsorptive cathodic stripping voltammetry (SW-AdCSV) technique) and the cytokinesis block micronucleus assay (CBMN assay). According to the SW-AdCSV data the alkaline hydrolysis of methidathion results in two new molecules, one non-electro-active and a second electro-active which is more genotoxic than methidathion itself in cultured human lymphocytes, inducing higher micronuclei frequencies. The present study confirms the SW-AdCSV technique as a voltammetric method which can successfully simulates the electrodynamics of the cellular membrane. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 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

  1. FLUORINE CELL ANODE ASSEMBLY

    Science.gov (United States)

    Cable, R.E.; Goode, W.B. Jr.; Henderson, W.K.; Montillon, G.H.

    1962-06-26

    An improved anode assembly is deslgned for use in electrolytlc cells ln the productlon of hydrogen and fluorlne from a moIten electrolyte. The anode assembly comprises a copper post, a copper hanger supported by the post, a plurality of carbon anode members, and bolt means for clamplng half of the anode members to one slde of the hanger and for clamplng the other half of the anode members to the other slde of the hanger. The heads of the clamplng bolts are recessed withln the anode members and carbon plugs are inserted ln the recesses above the bolt heads to protect the boIts agalnst corroslon. A copper washer is provided under the head of each clamplng boIt such that the anode members can be tightly clamped to the hanger with a resultant low anode jolnt resistance. (AEC)

  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. ALICE silicon strip module

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    This small silicon detector strip will be inserted into the inner tracking system (ITS) on the ALICE detector at CERN. This detector relies on state-of-the-art particle tracking techniques. These double-sided silicon strip modules have been designed to be as lightweight and delicate as possible as the ITS will eventually contain five square metres of these devices.

  5. Novel Lead dioxide-Graphite-Polymer composite anode for electrochemical chlorine generation

    Czech Academy of Sciences Publication Activity Database

    Gedam, N.; Neti, R.N.; Kormunda, M.; Šubrt, Jan; Bakardjieva, Snejana

    2015-01-01

    Roč. 169, JUL (2015), s. 109-116 ISSN 0013-4686 Institutional support: RVO:61388980 Keywords : beta-Lead dioxide * Graphite * Polymer composite anode * Chlorine generation * Cyclic voltammetry Subject RIV: CG - Electrochemistry Impact factor: 4.803, year: 2015

  6. Anodic voltammetry of zolmitriptan at boron-doped diamond electrode and its analytical applications.

    Science.gov (United States)

    Uslu, B; Canbaz, D

    2010-04-01

    The electrooxidative behavior and determination of zolmitriptan at a boron-doped diamond electrode were investigated using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. Zolmitriptan undergoes irreversible oxidation at a peak potential of about +0.9 V (vs Ag/AgCl/3 M KCl). DPV and SWV techniques are proposed for the determination of zolmitriptan in phosphate buffer at pH 3.03, which allows quantitation over the two different ranges (8 x 10(-7) - 8 x 10(-6) M and 1 x 10(-5) - 1 x 10(-4) M) in supporting electrolyte for both methods. A linear response was obtained in phosphate buffer over two different ranges (6 x 10(-7) - 8 x 10(-6) M and 1 x 10(-5) - 1 x 10(-4) M) for spiked serum samples at pH 3.03 for both techniques. The repeatability and reproducibility of the methods for all media were determined. The standard addition method was used in serum. Precision and accuracy were also checked in all media. No electroactive interferences from the excipients and endegenous substances were found in the pharmaceutical dosage form and the biological sample, respectively.

  7. Cathode Dependence of Liquid-Alloy Na-K Anodes.

    Science.gov (United States)

    Xue, Leigang; Gao, Hongcai; Li, Yutao; Goodenough, John B

    2018-03-07

    Alkali ions can be plated dendrite-free into a liquid alkali-metal anode. Commercialized Na-S battery technology operates above 300 °C. A low-cost Na-K alloy is liquid at 25 °C from 9.2 to 58.2 wt% of sodium; sodium and/or potassium can be plated dendrite-free in the liquid range at room temperature. The co-existence of two alkali metals in an anode raises a question: whether the liquid Na-K alloy acts as a Na or a K anode. Here we show the alkali-metal that is stripped from the liquid Na-K anode is dependent on the preference of the cathode host. It acts as the anode of a sodium rechargeable cell if the cathode host structure selectively accepts only Na + ions; as the anode of a potassium rechargeable cell if the cathode accepts K + ions in preference to Na + ions. This dual-anode behavior means the liquid Na-K alkali-alloy can be applied as a dendrite-free anode in Na-metal batteries as well as K-metal batteries.

  8. Emerging trends in biosensing using stripping voltammetric detection of metal-containing nanolabels – A review

    Energy Technology Data Exchange (ETDEWEB)

    Kokkinos, Christos; Economou, Anastasios, E-mail: aeconomo@chem.uoa.gr

    2017-04-08

    Over the last years, nanomaterials have found many applications in the development of electrochemical biosensors. Among other functions, metal nanoparticles (NPs) and quantum dots (QDs) (semiconducting nanocrystals composed of metal salts) are increasingly being used as voltammetric labels in affinity biosensing. Labeling is based on the attachment of the label(s) on the target biomolecules or on a biorecognition reporting probe. After an appropriate specific affinity interaction between the target and the reporting probe, the metallic nanolabels are converted to the respective cations which are quantified by a voltammetric technique. The very use of metal-containing nanoprobes as labels provides a first amplification step since each nanoprobe can release a very significant number of detectable cations. When anodic stripping voltammetry (ASV) (in which a preconcentration step precedes the actual voltammetric scan) is further employed as the detection format, ultra-sensitive bioassays can be developed. The present paper reviews the emerging trends in affinity biosensing using ASV detection of metal-containing nanolabels. It provides a critical discussion of recent developments in ASV transduction and electrodes, novel strategies for signal enhancement, approaches for multiplexed detection as well as fluidics, paper-based and lab-on-a-chip devices. - Highlights: • This paper reviews the use of ASV for affinity biosensing with metal-containing nanolabels. • Both metal nanoparticles and quantum dots applications are considered. • Transducers and new electrode materials are covered. • Signal enhancement and multiplexing strategies are discussed. • Sensor arrays, paper-based, fluidic and lab-on-chip applications are described.

  9. Anodic titania films as anode materials for lithium ion batteries

    International Nuclear Information System (INIS)

    Lindsay, M.J.; Blackford, M.G.; Attard, D.J.; Luca, V.; Skyllas-Kazacos, M.; Griffith, C.S.

    2007-01-01

    Titania thin films were prepared through the anodisation of titanium metal in a 1.0 M sulphuric acid solution at 80 o C utilising a series of pulsed dc constant currents of increasing magnitude. Films were then tested as a potential anode material for lithium batteries using a variety of techniques. Electrochemical testing revealed that the films (3.8 cm 2 ) offered good rate capabilities affording a constant capacity of 48 μAh for a constant current of 10 μA which decreased to 25 μAh on increasing the current to 1250 μA. Cyclic voltammetry was conducted over a range of scan rates from which capacitive currents were examined and rate constants, transfer coefficients and diffusion coefficients calculated. Electrochemical impedance spectroscopy was conducted over six potentials in the range 0.1-2.7 V with the experimental data successfully modelled using an equivalent circuit with the notation R(Q(RW))C. TEM observation of focussed ion beam milled cross-sections showed significant structural differences between the as-anodised film and those cycled in a lithium battery. Raman spectroscopy showed that the films had an anatase character that transformed into an unidentified lithium-containing, titanate phase on cycling. Based on a film thickness of 100 nm, and assuming density of 4 g cm -3 such films offered a stable capacity of 316 mAh g -1

  10. Electrochemical characterization of anode passivation mechanisms in copper electrorefining

    Science.gov (United States)

    Moats, Michael Scott

    Anode passivation can decrease productivity and quality while increasing costs in modern copper electrorefineries. This investigation utilized electrochemical techniques to characterize the passivation behavior of anode samples from ten different operating companies. It is believed that this collection of anodes is the most diverse set ever to be assembled to study the effect of anode composition on passivation. Chronopotentiometry was the main electrochemical technique, employing a current density of 3820 A m-2. From statistical analysis of the passivation characteristics, increasing selenium, tellurium, silver, lead and nickel were shown to accelerate passivation. Arsenic was the only anode impurity that inhibited passivation. Oxygen was shown to accelerate passivation when increased from 500 to 1500 ppm, but further increases did not adversely affect passivation. Nine electrolyte variables were also examined. Increasing the copper, sulfuric acid or sulfate concentration of the electrolyte accelerated passivation. Arsenic in the electrolyte had no effect on passivation. Chloride and optimal concentrations of thiourea and glue delayed passivation. Linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy provided complementary information. Analysis of the electrochemical results led to the development of a unified passivation mechanism. Anode passivation results from the formation of inhibiting films. Careful examination of the potential details, especially those found in the oscillations just prior to passivation, demonstrated the importance of slimes, copper sulfate and copper oxide. Slimes confine dissolution to their pores and inhibit diffusion. This can lead to copper sulfate precipitation, which blocks more of the surface area. Copper oxide forms because of the resulting increase in potential at the interface between the copper sulfate and anode. Ultimate passivation occurs when the anode potential is high enough to stabilize the oxide film in

  11. Dopamine Dynamics during Continuous Intracranial Self-Stimulation: Effect of Waveform on Fast-Scan Cyclic Voltammetry Data

    Science.gov (United States)

    2016-01-01

    The neurotransmitter dopamine is heavily implicated in intracranial self-stimulation (ICSS). Many drugs of abuse that affect ICSS behavior target the dopaminergic system, and optogenetic activation of dopamine neurons is sufficient to support self-stimulation. However, the patterns of phasic dopamine release during ICSS remain unclear. Early ICSS studies using fast-scan cyclic voltammetry (FSCV) rarely observed phasic dopamine release, which led to the surprising conclusion that it is dissociated from ICSS. However, several advances in the sensitivity (i.e., the use of waveforms with extended anodic limits) and analysis (i.e., principal component regression) of FSCV measurements have made it possible to detect smaller, yet physiologically relevant, dopamine release events. Therefore, this study revisits phasic dopamine release during ICSS using these tools. It was found that the anodic limit of the voltammetric waveform has a substantial effect on the patterns of dopamine release observed during continuous ICSS. While data collected with low anodic limits (i.e., +1.0 V) support the disappearance of phasic dopamine release observed in previous investigation, the use of high anodic limits (+1.3 V, +1.4 V) allows for continual detection of dopamine release throughout ICSS. However, the +1.4 V waveform lacks the ability to resolve narrowly spaced events, with the best balance of temporal resolution and sensitivity provided by the +1.3 V waveform. Ultimately, it is revealed that the amplitude of phasic dopamine release decays but does not fully disappear during continuous ICSS. PMID:27548680

  12. Quantum strips on surfaces

    OpenAIRE

    Krejcirik, David

    2002-01-01

    Motivated by the theory of quantum waveguides, we investigate the spectrum of the Laplacian, subject to Dirichlet boundary conditions, in a curved strip of constant width that is defined as a tubular neighbourhood of an infinite curve in a two-dimensional Riemannian manifold. Under the assumption that the strip is asymptotically straight in a suitable sense, we localise the essential spectrum and find sufficient conditions which guarantee the existence of geometrically induced bound states. I...

  13. Factors influencing the performances of micro-strips gas chambers

    International Nuclear Information System (INIS)

    Mack, V.; Brom, J.M.; Fang, R.; Fontaine, J.C.; Huss, D.; Kachelhoffer, T.; Kettunen, H.; Levy, J.M.; Pallares, A.; Bergdolt, A.M.; Cailleret, J.; Christophel, E.; Coffin, J.; Eberle, H.; Osswald, F.; Sigward, M.H.

    1995-01-01

    Damages to MSGCs (Micro-Strips Gas Chambers) induced by discharges have been investigated. Optimization of electrode shapes and/or deposition of a protective coating allows the potential difference between anode and cathode, thus increasing the gain. For prototypes of MSGCs made at the Centre de Recherches Nucleaires, each step of the manufacturing processes was carefully controlled. Results are presented on the influence of cleaning processes on the surface resistance of glass substrates. (author). 21 refs., 8 figs., 2 tabs

  14. Stripping voltammetric determination of palladium, platinum and rhodium in freshwater and sediment samples from South African water resources

    CSIR Research Space (South Africa)

    Van der Horst, C

    2012-08-01

    Full Text Available Stripping voltammetry as technique has proved to be very useful in the analysis of heavy and other metal ions due to its excellent detection limits and its sensitivity in the presence of different metal species or interfering ions. Recent...

  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. Anodized dental implant surface

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Mishra

    2017-01-01

    Full Text Available Purpose: Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. Materials and Methods: A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. Results: The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. Conclusions: The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

  17. Investigation of different anode materials for aluminium rechargeable batteries

    Science.gov (United States)

    Muñoz-Torrero, David; Leung, Puiki; García-Quismondo, Enrique; Ventosa, Edgar; Anderson, Marc; Palma, Jesús; Marcilla, Rebeca

    2018-01-01

    In order to shed some light into the importance of the anodic reaction in reversible aluminium batteries, we investigate here the electrodeposition of aluminium in an ionic liquid electrolyte (BMImCl-AlCl3) using different substrates. We explore the influence of the type of anodic material (aluminium, stainless steel and carbon) and its 3D geometry on the reversibility of the anodic reaction by cyclic voltammetry (CV) and galvanostatic charge-discharge. The shape of the CVs confirms that electrodeposition of aluminium was feasible in the three materials but the highest peak currents and smallest peak separation in the CV of the aluminium anode suggested that this material was the most promising. Interestingly, carbon-based substrates appeared as an interesting alternative due to the high peak currents in CV, moderate overpotentials and dual role as anode and cathode. 3D substrates such as fiber-based carbon paper and aluminium mesh showed significantly smaller overpotentials and higher efficiencies for Al reaction suggesting that the use of 3D substrates in full batteries might result in enhanced power. This is corroborated by polarization testing of full Al-batteries.

  18. Gallium oxide nanorods as novel, safe and durable anode material for Li- and Na-ion batteries

    NARCIS (Netherlands)

    Meligrana, Giuseppina; Lueangchaichaweng, Warunee; Colo, Francesca; Destro, Matteo; Fiorilli, Sonia; Pescarmona, Paolo P.; Gerbaldi, Claudio

    2017-01-01

    Gallium oxide nanorods prepared by template-free synthesis are reported for the first time as safe and durable anode material for lithium- and sodium-ion batteries. The ambient temperature electrochemical response of the nanorods, tested by cyclic voltammetry and constant-current reversible cycling,

  19. 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.

  20. Selective chemical stripping

    Science.gov (United States)

    Malavallon, Olivier

    1995-04-01

    At the end of the 80's, some of the large European airlines expressed a wish for paint systems with improved strippability on their aircraft, allowing the possibility to strip down to the primer without altering it, using 'mild' chemical strippers based on methylene chloride. These improvements were initially intended to reduce costs and stripping cycle times while facilitating rapid repainting, and this without the need to change the conventionally used industrial facilities. The level of in-service performance of these paint systems was to be the same as the previous ones. Requirements related to hygiene safety and the environment were added to these initial requirements. To meet customers' expectations, Aerospatiale, within the Airbus Industry GIE, formed a work group. This group was given the task of specifying, following up the elaboration and qualifying the paint systems allowing requirements to be met, in relation with the paint suppliers and the airlines. The analysis made in this report showed the interest of transferring as far upstream as possible (to paint conception level) most of the technical constraints related to stripping. Thus, the concept retained for the paint system, allowing selective chemical stripping, is a 3-coat system with characteristics as near as possible to the previously used paints.

  1. Fast Selective Detection of Pyocyanin Using Cyclic Voltammetry

    DEFF Research Database (Denmark)

    Al Atraktchi, Fatima Al-Zahraa; Breum Andersen, Sandra; Johansen, Helle Krogh

    2016-01-01

    method to detect pyocyanin in a complex electroactive environment using commercially available electrodes. It is shown that cyclic voltammetry measurements between –1.0 V to 1.0 V reveal a potential detection window of pyocyanin of 0.58–0.82 V that is unaffected by other redox-active interferents...

  2. Fast Selective Detection of Pyocyanin Using Cyclic Voltammetry

    DEFF Research Database (Denmark)

    Alatraktchi, Fatima AlZahra'a; Andersen, Sandra Breum; Johansen, Helle Krogh

    2016-01-01

    method to detect pyocyanin in a complex electroactive environment using commercially available electrodes. It is shown that cyclic voltammetry measurements between -1.0 V to 1.0 V reveal a potential detection window of pyocyanin of 0.58-0.82 V that is unaffected by other redox-active interferents...

  3. Electrochemical dissolution of chalcopyrite studied by voltammetry of immobilized microparticles

    Czech Academy of Sciences Publication Activity Database

    Pikna, L.; Lux, L.; Grygar, Tomáš

    2006-01-01

    Roč. 60, č. 4 (2006), s. 293-296 ISSN 0366-6352 Grant - others:VEGA(SK) No1/1108/04; APVT(SK) No20-009404 Institutional research plan: CEZ:AV0Z40320502 Keywords : chalcopyrite * cyclic voltammetry Subject RIV: CA - Inorganic Chemistry Impact factor: 0.360, year: 2006

  4. Voltammetry of hypoxic cells radiosensitizer etanidazole radical anion in water

    Czech Academy of Sciences Publication Activity Database

    Gál, Miroslav; Hromadová, Magdaléna; Pospíšil, Lubomír; Híveš, J.; Sokolová, Romana; Kolivoška, Viliam; Kocábová, Jana

    2010-01-01

    Roč. 78, č. 2 (2010), s. 118-123 ISSN 1567-5394 R&D Projects: GA ČR GP203/09/P502 Institutional research plan: CEZ:AV0Z40400503 Keywords : etanidazole * radiosensitizer * electron transfer * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 3.520, year: 2010

  5. Cyclic Voltammetry of Biopolymer Heparin at PVC Plasticized Liquid Membrane

    Czech Academy of Sciences Publication Activity Database

    Samec, Zdeněk; Trojánek, Antonín; Langmaier, Jan; Samcová, E.

    2003-01-01

    Roč. 5, - (2003), s. 867-870 ISSN 1388-2481 R&D Projects: GA ČR GA203/04/0424 Institutional research plan: CEZ:AV0Z4040901 Keywords : cyclic voltammetry * PVC plasticized liquit membrane * heparin Subject RIV: CG - Electrochemistry Impact factor: 2.300, year: 2003

  6. Electrochemical polymerization of phenol on 304 stainless steel anodes and subsequent coating structure analysis

    International Nuclear Information System (INIS)

    Bao Liyin; Xiong Rongchun; Wei Gang

    2010-01-01

    Anodic oxidation was carried out using 304 stainless steel anodes in neutral 0.1 mol/L phenol solution with an electrolyte composed of 0.1 mol/L sodium sulfate. This oxidation generated a yellow brown polyphenol coating on the steel anode surface. The reaction conditions discussed in this report relate to the methods of linear scanning, cyclic voltammetry and constant current oxidation. The proper anodic electrode potential for polyphenol deposition was observed to be 1.45 V, with a bath voltage of 2.5 V. The chemical structure of the polyphenol coating was analyzed by infrared spectroscopy and the molecular weight of the soluble part of the coating was detected by gel permeation chromatography. A scanning electron microscope was used to analyze the microstructure of the polyphenol coating, taking advantage of the partial solubility of the polyphenol in tetrahydrofuran. The observed linear and flake-layer modes of the polyphenol coating growth are summarized herein.

  7. Electrochemical polymerization of phenol on 304 stainless steel anodes and subsequent coating structure analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bao Liyin [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Xiong Rongchun, E-mail: rongchunxiong@163.co [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Wei Gang [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2010-04-30

    Anodic oxidation was carried out using 304 stainless steel anodes in neutral 0.1 mol/L phenol solution with an electrolyte composed of 0.1 mol/L sodium sulfate. This oxidation generated a yellow brown polyphenol coating on the steel anode surface. The reaction conditions discussed in this report relate to the methods of linear scanning, cyclic voltammetry and constant current oxidation. The proper anodic electrode potential for polyphenol deposition was observed to be 1.45 V, with a bath voltage of 2.5 V. The chemical structure of the polyphenol coating was analyzed by infrared spectroscopy and the molecular weight of the soluble part of the coating was detected by gel permeation chromatography. A scanning electron microscope was used to analyze the microstructure of the polyphenol coating, taking advantage of the partial solubility of the polyphenol in tetrahydrofuran. The observed linear and flake-layer modes of the polyphenol coating growth are summarized herein.

  8. Anodic ammonia oxidation to nitrogen gas catalyzed by mixed biofilms in bioelectrochemical systems

    International Nuclear Information System (INIS)

    Zhan, Guoqiang; Zhang, Lixia; Tao, Yong; Wang, Yujian; Zhu, Xiaoyu; Li, Daping

    2014-01-01

    In this paper we report ammonia oxidation to nitrogen gas using microbes as biocatalyst on the anode, with polarized electrode (+600 mV vs. Ag/AgCl) as electron acceptor. In batch experiments, the maximal rate of ammonia-N oxidation by the mixed culture was ∼ 60 mg L −1 d −1 , and nitrogen gas was the main products in anode compartment. Cyclic voltammetry for testing the electroactivity of the anodic biofilms revealed that an oxidation peak appeared at +600 mV (vs. Ag/AgCl), whereas the electrode without biofilms didn’t appear oxidation peak, indicating that the bioanode had good electroactivities for ammonia oxidation. Microbial community analysis of 16S rRNA genes based on high throughput sequencing indicated that the combination of the dominant genera of Nitrosomonas, Comamonas and Paracocus could be important for the electron transfer from ammonia oxidation to anode

  9. Enhancing hybrid direct carbon fuel cell anode performance using Ag2O

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2015-01-01

    A hybrid-direct carbon fuel cell (HDCFC), consisting of a molten slurry of solid carbon black and (Li-K)2CO3 added to the anode chamber of a solid oxide fuel cell, was characterized using current-potential-power density curves, electrochemical impedance spectroscopy, and cyclic voltammetry. Two...... types of experimental setups were employed in this study, an anode-supported full cell configuration (two electrodes, two atmospheres setup) and a 3-electrode electrolyte-supported half-cell setup (single atmosphere). Anode processes with and without catalysts were investigated as a function...... of temperature (700-800 °C) and anode sweep gas (N2, 4-100% CO2 in N2-CO2). It was shown that the addition of silver based catalysts (Ag, Ag2O, Ag2CO3) into the carbon-carbonate slurry enhanced the performance of the HDCFC....

  10. Photosensitive Strip RETHGEM

    CERN Document Server

    Peskov, Vladimir; Nappi, E.; Oliveira, R.; Paic, G.; Pietropaolo, F.; Picchi, P.

    2008-01-01

    An innovative photosensitive gaseous detector, consisting of a GEM like amplification structure with double layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen printing technology on the top of the metallic strips grid The inner metallic grid is used for 2D position measurements whereas the resistive layer provides an efficient spark protected operation at high gains - close to the breakdown limit. Detectors with active areas of 10cm x10cm and 10cm x20cm were tested under various conditions including the operation in photosensitive gas mixtures containing ethylferrocene or TMAE vapors. The new technique could have many applications requiring robust and reliable large area detectors for UV visualization, as for example, in Cherenkov imaging devices.

  11. Anode Support Creep

    DEFF Research Database (Denmark)

    2015-01-01

    Initial reduction temperature of an SOC is kept higher than the highest intended operation temperature of the SOC to keep the electrolyte under compression by the Anode Support at all temperatures equal to and below the maximum intended operation temperature.......Initial reduction temperature of an SOC is kept higher than the highest intended operation temperature of the SOC to keep the electrolyte under compression by the Anode Support at all temperatures equal to and below the maximum intended operation temperature....

  12. Liquid Silicon Pouch Anode

    Science.gov (United States)

    2017-09-06

    collector 18 can be made from nickel; however, other high conductivity metals and alloys can be used for this such as gold, silver , platinum, alloys of...The conductive particles can be carbon such as carbon black or graphite. These particles can also be metals such as copper, nickel, silver , gold...anode cycling characteristics, higher battery capacity, and longer cycle life. [0005] Rechargeable batteries with lithium metal anodes have been

  13. Alcohol Saliva Strip Test

    OpenAIRE

    Thokala, Madhusudhana Rao; Dorankula, Shyam Prasad Reddy; Muddana, Keertrthi; Velidandla, Surekha Reddy

    2014-01-01

    Alcohol is a factor in many categories of injury. Alcohol intoxication is frequently associated with injuries from falls, fires, drowning, overdoses, physical and sexual abusements, occupational accidents, traffic accidents and domestic violence. In many instances, for forensic purpose, it may be necessary to establish whether the patients have consumed alcohol that would have been the reason for the injury/accidents. Combining rapidity and reliability, alcohol saliva strip test (AST) has bee...

  14. Anode process on platinum in CaCl2-CaO-based melt

    Directory of Open Access Journals (Sweden)

    K. V. Tatarenko

    2014-12-01

    Full Text Available Methods potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic processes on platinum in the molten CaCl2-KCl-CaO when 725–775 °C. Given thermodynamic values of potential difference probable total reactions in the range of the studied temperature. Using potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic process on platinum in the molten CaCl2-KCl-CaO when 725–775 °C thermodynamic assessment of the probability of occurrence total reactions during electrolysis melt on the basis of CaCl2-CaO using non-carbon anode. It is shown that at high current densities anodic process takes place mainly in the conditions of slow diffusion of electrically active particles to the anode, and at low densities (up to 10 mA/cm2 to their discharge to the atomic and lecular oxygen is preceded by a stage, which can be associated with adsorption of atoms of oxygen or with the formation of an oxide film on the surface of platinum. To detect the nature of this stage, further research is needed.

  15. Evaluation of tetraphenylporphyrin modified ZnO as anode material for Ni-Zn rechargeable battery

    International Nuclear Information System (INIS)

    Huang, Jianhang; Yang, Zhanhong; Wang, Tingting

    2014-01-01

    The cycle life of zinc anode in alkaline medium was enhanced by tetraphenylporphyrin (TPP) as modifier through a facile co-precipitation method. The as-prepared electrode material before and after charge/discharge test were characterized by scanning electron microscopy (SEM) to investigate the effect of TPP on the zinc dendrite growth. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and polarization measurement were utilized to examine the electrochemical performances of TPP-modified ZnO as anode material. TPP-modified ZnO possess higher discharge voltage, higher cycle stability and lower corrosion current, but larger charge-transfer resistance in comparison with bare ZnO

  16. Cyclic voltammetry of Monel 400 in lithium hydroxide solution at elevated temperatures

    International Nuclear Information System (INIS)

    MacDonald, D.D.

    1976-01-01

    The electrochemistry of Monel 400 in 1 mole/kg -1 LiOH solution at 25, 125 and 250 0 C has been investigated using the technique of cyclic voltammetry. The general electrochemical behaviour is found to most closely approximate to that of the major component, nickel, although expansion of the current scale reveals anodic and cathodic peaks which probably arise from redox processes involving copper. The general similarity to nickel can be rationalized in terms of either the d electron theory for cupronickel alloys or phase separation, the latter being favoured in the present study. At 25 0 C the majority of charge consumed on sweeping the potential in the positive direction is involved in the formation of an oxide film at potentials close to oxygen evolution. This process is no longer observed at 2500C, due to a sharp reduction in the oxygen evolution overpotential with temperature. The majority of charge consumed on cyclic sweeping at this temperature is attributed to active dissolution of the nickel component of the alloy to form HNiO 2 - (or Ni(OH) 3 - ) at potentials slightly positive to the hydrogen evolution region. (author)

  17. Elimination Voltammetry with Linear Scan as a New Detection Method for DNA Sensors

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2005-11-01

    Full Text Available The paper describes successful coupling of adsorptive transfer stripping (AdTS andelimination voltammetry with linear scan (EVLS for the resolution of reduction signals of cytosine (Cand adenine (A residues in hetero-oligodeoxynucleotides (ODNs. Short ODNs (9-mers and 20-merswere adsorbed from a small volume on a hanging mercury drop electrode (HMDE. After washing ofthe ODN-modified electrode by water and its transferring to an electrochemical cell, voltammetric curves were measured. The AdTS EVLS was able to determine of C/A ratio of ODNs through theelimination function conserving the diffusion current component and eliminating kinetic and chargingcurrent components. This function, which provides the elimination signal in a peak-counterpeak form,increased the current sensitivity for A and C resolution, and for the recognition of bases sequences inODN chains. Optimal conditions of elimination experiments such as pH, time of adsorption, and scanrate were found. The combination of EVLS with AdTS procedure can be considered as a newdetection method in a DNA sensor.

  18. Ferrate(VI synthesis at boron-doped diamond anode

    Directory of Open Access Journals (Sweden)

    Čekerevac Milan

    2013-01-01

    Full Text Available The oxidation of iron compounds from alkaline 10 M KOH electrolytes on a boron doped diamond electrode is examined by cyclic voltammetry between the potentials of hydrogen evolution reaction and oxygen evolution reaction, due to ferrate(VI electrochemical synthesis. It is shown that the anodic current peak that appears in iron free electrolyte at a less positive potential than the potential of oxygen evolution probably coincides with oxidation of hydrogen in >CH2 groups and C-sp2 graphite impurities with formation of >C=O groups at C-sp3 diamond structure. Addition of Fe(III compounds to the electrolyte provoke formation of the anodic wave on cyclic voltammograms in the potential region which correlates with generation of ferrate(VI. It is concluded that the direct electrochemical synthesis of Fe(VI at the boron doped diamond anode is possible because of the less positive potential of ferrate(VIFeO2-4 formation in respect to the potential of oxygen evolution reaction. Presence of ferrate(VI in electrolyte, formed after anodic polarization of boron electrode in 10 M KOH electrolyte saturated with Fe(III at + 0.9 V against Hg|HgO electrode, has been proven by UV-VIS spectrometry.

  19. Thin-film voltammetry and its analytical applications: A review

    International Nuclear Information System (INIS)

    Tian, Huihui; Li, Yunchao; Shao, Huibo; Yu, Hua-Zhong

    2015-01-01

    Highlights: • Electrochemistry at immiscible liquid–liquid interfaces is fundamentally important. • Methods for studying redox processes at liquid–liquid interfaces are reviewed. • Thin-film voltammetry is simple in experimental operation and kinetic data analysis. • Thin-film voltammetry’s analytical applications are prevailing and comprehensive. - Abstract: Electrochemical reactions at the interfaces of immiscible electrolyte solutions (ITIES) are of fundamental importance in the fields of chemical, biological and pharmaceutical sciences. Four-electrode cell setup, scanning electrochemical microscopy (SECM) and thin-film voltammetry are the three most frequently used methods for studying the electrochemical processes at these interfaces. The principle, experimental design, advantages and challenges of the three methods are described and compared. The thin-film voltammetry is highlighted for its simplicity in experimental operation and kinetic data analysis. Its versatile analytical applications are discussed in detail, including the study of redox properties of hydrophobic compounds, evaluation of interfacial electron transfer kinetics, synthesis of nanoparticles/nanostructures, and illustration of cross-membrane ion transport phenomena

  20. 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.

  1. Corrosion Cyclic Voltammetry of Two Types of Heat-Affected Zones (HAZs) of API-X100 Steel in Bicarbonate Solutions

    Science.gov (United States)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2014-12-01

    This paper examined the electrochemical corrosion behavior and corrosion products of two types of heat-affected HAZs made from API-X100 steel. Cyclic voltammetry, with different scan rates and potential ranges at 10 cycles, was applied to analyze the interdependent corrosion reactions of cathodic reduction, anodic dissolution, passivation, and transpassivation. The HAZ cooled at 60 K/s, from a peak temperature of 1470 K (1197 °C) that was held for 15 seconds, exhibited better passivation and lower cathodic activity than the HAZ cooled at 10 K/s. Increasing bicarbonate concentration, from 0.05 and 0.2 to 0.6 M, increases the anodic activity and cathodic reduction, but accordingly protects the active surfaces and enhances passivation.

  2. Dynamic Underground Stripping Project

    International Nuclear Information System (INIS)

    Aines, R.; Newmark, R.; McConachie, W.; Udell, K.; Rice, D.; Ramirez, A.; Siegel, W.; Buettner, M.; Daily, W.; Krauter, P.; Folsom, E.; Boegel, A.J.; Bishop, D.; Udell, K.

    1992-01-01

    LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation and underground imaging techniques for use in rapid cleanup of localized underground spills. Called ''Dynamic Stripping'' to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first 8 months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques before moving the contaminated site in FY 92

  3. A conducting polymer/ferritin anode for biofuel cell applications

    International Nuclear Information System (INIS)

    Inamuddin; Shin, Kwang Min; Kim, Sun I.; So, Insuk; Kim, Seon Jeong

    2009-01-01

    An enzyme anode for use in biofuel cells (BFCs) was constructed using an electrically connected bilayer based on a glassy carbon (GC) electrode immobilized with the conducting polymer polypyrrole (Ppy) as electron transfer enhancer, and with horse spleen ferritin protein (Frt) as electron transfer mediator. The surface-coupled redox system of nicotinamide adenine dinucleotide (NADH) catalyzed with diaphorase (Di) was used for the regeneration of NAD + in the inner layer and the NAD + -dependent enzyme catalyst glucose dehydrogenase (GDH) in the outer layer. The outer layer of the GC-Ppy-Frt-Di-NADH-GDH electrode effectively catalyzes the oxidation of glucose biofuel continuously; using the NAD + generated at the inner layer of the Di-catalyzed NADH redox system mediated by Frt and Ppy provides electrical communication with enhancement in electron transport. The electrochemical characteristics of the electrodes were investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). This anode provides a current density of 1.2 mA cm -2 in a 45 mM glucose solution and offers a good possibility for application in biofuel cells.

  4. Lithium batteries, anodes, and methods of anode fabrication

    KAUST Repository

    Li, Lain-Jong

    2016-12-29

    Prelithiation of a battery anode carried out using controlled lithium metal vapor deposition. Lithium metal can be avoided in the final battery. This prelithiated electrode is used as potential anode for Li- ion or high energy Li-S battery. The prelithiation of lithium metal onto or into the anode reduces hazardous risk, is cost effective, and improves the overall capacity. The battery containing such an anode exhibits remarkably high specific capacity and a long cycle life with excellent reversibility.

  5. Electronic rumble strip

    Science.gov (United States)

    Stauffer, Donald R.; Lenz, James

    1997-02-01

    Single vehicle run-off-road accidents are responsible for significant numbers of injuries and fatalities, and significant property damage. This fact spurs interest in warning systems to alert drivers that vehicles are drifting towards the edge of the road, and that a run-off road accident is imminent. An early attempt at such a warning system is the use of machined grooves on the shoulder to create a rumble strip. Such a system only provides warning, however, as the vehicle actually leaves the traffic lane. More desirable is a system that warns in anticipation of such departure. Honeywell has under development a magnetic lateral guidance system that couples a sensitive magnetoresistive transducer with a magnetic traffic marking tape being developed by 3M. While this development was initially undertaken for use in automated highways, or for special tasks such as guiding snowplow owners, the system can provide an effective, all-weather warning system to provide alert of impending departure from the roadway. This electronic rumble strip is actually a simpler system than the baseline guidance system, and can monitor both distance from the traffic lane edge and the speed of approach to the edge with a low cost sensor.

  6. 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.\

  7. Low material budget floating strip Micromegas for ion transmission radiography

    Energy Technology Data Exchange (ETDEWEB)

    Bortfeldt, J., E-mail: jonathan.bortfeldt@cern.ch [LMU Munich, LS Schaile, Am Coulombwall 1, D-85748 Garching (Germany); Biebel, O.; Flierl, B.; Hertenberger, R.; Klitzner, F.; Lösel, Ph. [LMU Munich, LS Schaile, Am Coulombwall 1, D-85748 Garching (Germany); Magallanes, L. [LMU Munich, LS Parodi, Am Coulombwall 1, D-85748 Garching (Germany); University Hospital Heidelberg, Im Neuenheimer Feld 672, D-69120 Heidelberg (Germany); Müller, R. [LMU Munich, LS Schaile, Am Coulombwall 1, D-85748 Garching (Germany); Parodi, K. [LMU Munich, LS Parodi, Am Coulombwall 1, D-85748 Garching (Germany); Heidelberg Ion-Beam Therapy Center, Im Neuenheimer Feld 450, D-69120 Heidelberg (Germany); Schlüter, T. [LMU Munich, Excellence Cluster Universe, Boltzmannstr. 2, D-85748 Garching (Germany); Voss, B. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, D-64291 Darmstadt (Germany); Zibell, A. [JMU Würzburg, Sanderring 2, D-97070 Würzburg (Germany)

    2017-02-11

    Floating strip Micromegas are high-accuracy and discharge insensitive gaseous detectors, able to track single particles at fluxes of 7 MHz/cm{sup 2} with 100 μm resolution. We developed low-material-budget detectors with one-dimensional strip readout, suitable for tracking at highest particle rates as encountered in medical ion transmission radiography or inner tracker applications. Recently we additionally developed Kapton-based floating strip Micromegas with two-dimensional strip readout, featuring an overall thickness of 0.011 X{sub 0}. These detectors were tested in high-rate proton and carbon-ion beams at the tandem accelerator in Garching and the Heidelberg Ion-Beam Therapy Center, operated with an optimized Ne:CF{sub 4} gas mixture. By coupling the Micromegas detectors to a new scintillator based range detector, ion transmission radiographies of PMMA and tissue-equivalent phantoms were acquired. The range detector with 18 layers is read out via wavelength shifting fibers, coupled to a multi-anode photomultiplier. We present the performance of the Micromegas detectors with respect to timing and single plane track reconstruction using the μTPC method. We discuss the range resolution of the scintillator range telescope and present the image reconstruction capabilities of the combined system.

  8. Determination of Ascorbic Acid Content of Some Fruit Juices and Wine by Voltammetry Performed at Pt and Carbon Paste Electrodes

    Directory of Open Access Journals (Sweden)

    Aurel Pisoschi

    2011-02-01

    Full Text Available A method was developed for assessing ascorbic acid concentration in fruit juices and wine by differential pulse voltammetry. The oxidation peak for ascorbic acid occurs at about 530 mV (versus SCE on a Pt strip working electrode and at about 470 mV on a carbon paste working electrode. The influence of the operational parameters like the pulse amplitude and the pulse period on the analytical signal was investigated. The obtained calibration graph shows a linear dependence between the peak height and ascorbic acid concentration within the range 0.31-20 mM with a Pt working electrode, and within the range 0.07-20 mM with a carbon paste working electrode. The equation of the calibration graph was y = 21.839x + 35.726, r2 = 0.9940, when a Pt strip electrode was used (where y represents the value of the current intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM. R.S.D. = 2.09%, n = 10, Cascorbic acid = 2.5 mM. The equation of the calibration graph was y = 3.4429x + 5.7334, r2 = 0.9971, when a carbon paste electrode was used (where y represents the value of intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM. R.S.D. = 2.35%, n = 10, Cascorbic acid = 2.5 mM. The developed method was applied to ascorbic acid assessment in fruit juices and wine. The ascorbic acid content determined ranged between 6.83 mg/100 mL juice for soft drinks (Fanta Madness and 54.74 mg/100 mL for citrus (lemon juices obtained by squeezing fruit. Different ascorbic acid concentrations (from standard solutions were added to the analysed samples, the degree of recovery being comprised between 94.74 and 104.97%. The results of ascorbic acid assessment by differential pulse voltammetry were compared with those obtained by cyclic voltammetry. The results obtained by the two methods were in good agreement.

  9. Readout of silicon strip detectors

    CERN Document Server

    Dabrowski, W

    2003-01-01

    Various architectural and technological options of readout electronics for silicon strip detectors in vertex and tracking applications are discussed briefly. The ABCD3T ASIC for the readout of silicon strip detectors in the ATLAS semiconductor tracker is presented. The architecture of the chip, some design issues and radiation effects are discussed.

  10. The CMS Silicon Strip Tracker

    CERN Document Server

    Azzurri, P

    2005-01-01

    With over 200 square meters of sensitive Silicon and almost 10 million readout channels, the Silicon Strip Tracker of the CMS experiment at the LHC will be the largest Silicon strip detector ever built. The design, construction and expected performance of the CMS Tracker is reviewed in the following.

  11. Inert Anode Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1999-07-01

    This ASME report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issues associated with these technologies from a technical, environmental, and economic viewpoint.

  12. Anodes for alkaline electrolysis

    Science.gov (United States)

    Soloveichik, Grigorii Lev [Latham, NY

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  13. Movable anode x-ray source with enhanced anode cooling

    Science.gov (United States)

    Bird, C.R.; Rockett, P.D.

    1987-08-04

    An x-ray source is disclosed having a cathode and a disc-shaped anode with a peripheral surface at constant radius from the anode axis opposed to the cathode. The anode has stub axle sections rotatably carried in heat conducting bearing plates which are mounted by thermoelectric coolers to bellows which normally bias the bearing plates to a retracted position spaced from opposing anode side faces. The bellows cooperate with the x-ray source mounting structure for forming closed passages for heat transport fluid. Flow of such fluid under pressure expands the bellows and brings the bearing plates into heat conducting contact with the anode side faces. A worm gear is mounted on a shaft and engages serrations in the anode periphery for rotating the anode when flow of coolant is terminated between x-ray emission events. 5 figs.

  14. Hemispherical Shell Nanostructures from Metal-Stripped Embossed Alumina on Aluminum Templates

    DEFF Research Database (Denmark)

    Nielsen, Peter; Albrektsen, Ole; Simonsen, Adam Cohen

    2011-01-01

    aluminum/ alumina (Al/Al2O3) templates as a novel and versatile nanofabrication procedure, and we demonstrate explicitly how to exploit the technique for developing large-area hexagonally close-packed hemispherical shell nanostructures by stripping noble metal layers from embossed templates fabricated from...... anodized Al. Utilizing for this process the linear relationship between anodization voltage and the resulting interpore distance in the formed oxide, it is possible to tune the radius of curvature of the resulting hemispherical shells continuously, which in turn results in tunable optical properties...

  15. Range gated strip proximity sensor

    Science.gov (United States)

    McEwan, T.E.

    1996-12-03

    A range gated strip proximity sensor uses one set of sensor electronics and a distributed antenna or strip which extends along the perimeter to be sensed. A micro-power RF transmitter is coupled to the first end of the strip and transmits a sequence of RF pulses on the strip to produce a sensor field along the strip. A receiver is coupled to the second end of the strip, and generates a field reference signal in response to the sequence of pulse on the line combined with received electromagnetic energy from reflections in the field. The sensor signals comprise pulses of radio frequency signals having a duration of less than 10 nanoseconds, and a pulse repetition rate on the order of 1 to 10 MegaHertz or less. The duration of the radio frequency pulses is adjusted to control the range of the sensor. An RF detector feeds a filter capacitor in response to received pulses on the strip line to produce a field reference signal representing the average amplitude of the received pulses. When a received pulse is mixed with a received echo, the mixing causes a fluctuation in the amplitude of the field reference signal, providing a range-limited Doppler type signature of a field disturbance. 6 figs.

  16. Test beam results of a low-pressure micro-strip gas chamber with a secondary-electron emitter

    International Nuclear Information System (INIS)

    Kwan, S.; Anderson, D.F.; Zimmerman, J.; Sbarra, C.; Salomon, M.

    1994-10-01

    We present recent results, from a beam test, on the angular dependence of the efficiency and the distribution of the signals on the anode strips of a low-pressure microstrip gas chamber with a thick CsI layer as a secondary-electron emitter. New results of CVD diamond films as secondary-electron emitters are discussed

  17. Continuous power generation and microbial community structure of the anode biofilms in a three-stage microbial fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyungmi; Okabe, Satoshi [Hokkaido Univ., Sapporo (Japan). Dept. of Urban and Environmental Engineering

    2009-07-15

    A mediator-less three-stage two-chamber microbial fuel cell (MFC) system was developed and operated continuously for more than 1.5 years to evaluate continuous power generation while treating artificial wastewater containing glucose (10 mM) concurrently. A stable power density of 28 W/m3 was attained with an anode hydraulic retention time of 4.5 h and phosphate buffer as the cathode electrolyte. An overall dissolved organic carbon removal ratio was about 85%, and coulombic efficiency was about 46% in this MFC system. We also analyzed the microbial community structure of anode biofilms in each MFC. Since the environment in each MFC was different due to passing on the products to the next MFC in series, the microbial community structure was different accordingly. The anode biofilm in the first MFC consisted mainly of bacteria belonging to the Gammaproteobacteria, identified as Aeromonas sp., while the Firmicutes dominated the anode biofilms in the second and third MFCs that were mainly fed with acetate. Cyclic voltammetric results supported the presence of a redox compound(s) associated with the anode biofilm matrix, rather than mobile (dissolved) forms, which could be responsible for the electron transfer to the anode. Scanning electron microscopy revealed that the anode biofilms were comprised of morphologically different cells that were firmly attached on the anode surface and interconnected each other with anchor-like filamentous appendages, which might support the results of cyclic voltammetry. (orig.)

  18. ATLAS Strips Upgrade

    CERN Document Server

    Miñano, Mercedes

    2009-01-01

    It is foreseen to increase the luminosity of the LHC at CERN around 2020 by about an order of magnitude (SLHC). The ATLAS experiment will require a new particle tracking system for SLHC operation in order to cope with the increase in background events by about one order of magnitude at the higher luminosity. , an all silicon detector with enhanced radiation hardness is being designed. A massive R&D programme, involving many particles physics groups and several leadings manufacturers of silicon detectors for particle physics, is underway to develop silicon sensors with sufficient radiation hardness. In this framework new sensor materials like p-type silicon and the 3D technology are investigated. In parallel, the SCT commissioning experience has taught us to look into alternative module concepts, in which higher levels of integration are combined with the modularity of the SCT approach. We will report on the status of the R&D projects on radiation hard silicon strip detectors for particle physics, link...

  19. ATLAS Strip Upgrade

    CERN Document Server

    Bernabeu, J; The ATLAS collaboration

    2012-01-01

    A phased upgrade of the Large Hadron Collider (LHC) at CERN is planned. The last upgrade phase (HL-LHC) is currently foreseen in 2022-2023. It aims to increase the integrated luminosity to about ten times the original LHC design luminosity. To cope with the harsh conditions in terms of particle rates and radiation dose expected during HL-LHC operation, the ATLAS collaboration is developing technologies for a complete tracker replacement. This new detector will need to provide extreme radiation hardness and a high granularity, within the tight constraints imposed by the existing detectors and their services. An all-silicon high-granularity tracking detector is proposed. An international R&D collaboration is working on the strip layers for this new tracker. A number of large area prototype planar detectors produced on p-type wafers have been designed and fabricated for use at HL-LHC. These prototype detectors and miniature test detectors have been irradiated to a set of fluences matched to HL-LHC expectatio...

  20. Characterization of galvannealed strip

    International Nuclear Information System (INIS)

    Moreas, G.; Hardy, Y.

    1999-01-01

    With the aim of enhancing coating quality control during galvannealing process, an online microscopic image acquisition sensor has been developed at CRM. In galvannealing process, the ζ phase surface density is a coating quality characteristic, and the on-line microscope, equipped with optics placed at 20 mm from the surface, grabs 250 μm x 190 μm images on which ζ crystals (approximate dimensions: 1 μm x 10 μm) can be clearly identified. On-line, the sensor is mounted in front of a roll where the strip has a stable position. The coating surface to sensor optics distance is continuously measured by an accurate triangulation sensor (1 μm repeatability) and is adjusted in such a way that, due to roll eccentricity, the image is focused at least twice per revolution. When focused, image of moving product is frozen by a short (10 ns) laser light pulse and is grabbed. The obtained image is then processed to extract ζ phase percentage and allows adjustment of process parameters to reach the desired coating characteristics. (author)

  1. Buffers and vegetative filter strips

    Science.gov (United States)

    Matthew J. Helmers; Thomas M. Isenhart; Michael G. Dosskey; Seth M. Dabney

    2008-01-01

    This chapter describes the use of buffers and vegetative filter strips relative to water quality. In particular, we primarily discuss the herbaceous components of the following NRCS Conservation Practice Standards.

  2. Process for anodizing aluminum foil

    International Nuclear Information System (INIS)

    Ball, J.A.; Scott, J.W.

    1984-01-01

    In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 80 0 C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V

  3. The effects of silicon doping on the performance of PMAN carbon anodes in Li-ion cells

    Energy Technology Data Exchange (ETDEWEB)

    Guidotti, R.A.; Johnson, B.J. [Sandia National Labs., Albuquerque, NM (United States); Even, W. Jr. [Sandia National Labs., Livermore, CA (United States)

    1996-05-01

    Carbons derived from polymethylacrylonitrile (PMAN) have been studied for use as intercalation anodes in Li-ion cells. The effect of Si doping upon the electrochemical performance of PMAN carbons was studied using tetravinylsilane (TVS) and tetramethysilane (TMS) as sources of Si during the formation of the PMAN precursors. The carbons were characterized by galvanostatic cycling, cyclic voltammetry, and complex impedance. The presence of 9 to 11 w/o Si in the PMAN lattice greatly increased the irreversible capacity of these materials.

  4. The anodization synthesis of copper oxide nanosheet arrays and their photoelectrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Xia [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zheng, Hongmei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Xu, Guangqing, E-mail: gqxu1979@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Zhao, Jiebo [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Cui, Lihua [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Materials Science and Engineering, Beifang University of Nationalities, Yinchuan 750021 (China); Cui, Jiewu; Qin, Yongqiang; Wang, Yan [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Yong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Wu, Yucheng, E-mail: ycwu@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China)

    2017-08-01

    Graphical abstract: Current-time and potential-time curves of the copper foil anodization process, CV of copper substrate in anodization solution and SEM morphologies of anodization products on Cu substrates obtained at different time. - Highlights: • Copper oxides nanosheet arrays were achieved via anodization method. • The growth mechanisms of the copper anodization process were studied. • Photoelectrochemical performances of copper oxides NSAs were studied. - Abstract: We studied the growth of copper oxide nanosheet arrays on copper foil via a simple anodization method. The structures, morphologies, and elemental compositions of the specimens were characterized with an X-ray diffractometer, scanning electron microscope, high resolution transmission electron microscope, and X-ray photoelectron spectrometer. The copper oxide (Cu{sub 2}O and CuO) nanosheet arrays were comprised of 30-nm-thick nanosheets that stand vertically on the Cu substrate. The anodizing parameters, such as the current density, temperature, and polyethylene glycol concentration, were optimized to obtain the regular nanosheet arrays. The optical absorption properties of the anodized products were evaluated using a diffuse reflectance spectrometer, and broad and strong optical absorption bands arising from the UV to visible region were observed. The photoelectrochemical performance of the nanosheet arrays was measured with chronoamperometry and cyclic voltammetry on an electrochemical workstation equipped with a Xe lamp (wavelength >400 nm). A negative photocurrent was obtained due to the p-type semiconductor of the copper oxides. The copper oxide nanosheet arrays achieve the highest photocurrent of 0.4 mA/cm{sup 2} at the current density of 1.0 A/dm{sup 2}, temperature of 70 °C, and polyethylene glycol concentration of 0.5 g/L.

  5. Electro-catalytic degradation of sulfisoxazole by using graphene anode.

    Science.gov (United States)

    Wang, Yanyan; Liu, Shuan; Li, Ruiping; Huang, Yingping; Chen, Chuncheng

    2016-05-01

    Graphite and graphene electrodes were prepared by using pure graphite as precursor. The electrode materials were characterized by a scanning electron microscope (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV) measurements. The electro-catalytic activity for degradation of sulfisoxazole (SIZ) was investigated by using prepared graphene or graphite anode. The results showed that the degradation of SIZ was much more rapid on the graphene than that on the graphite electrode. Moreover, the graphene electrode exhibited good stability and recyclability. The analysis on the intermediate products and the measurement of active species during the SIZ degradation demonstrated that indirect oxidation is the dominant mechanism, involving the electro-catalytic generation of OH and O2(-) as the main active oxygen species. This study implies that graphene is a promising potential electrode material for long-term application to electro-catalytic degradation of organic pollutants. Copyright © 2015. Published by Elsevier B.V.

  6. Anodic oxidation of chloride ions in 1-butyl-3-methyl-limidazolium tetrafluoroborate ionic liquid

    International Nuclear Information System (INIS)

    Zhang, Qibo; Hua, Yixin; Wang, Rui

    2013-01-01

    Highlights: • The anodic oxidation of Cl − in BMIMBF 4 is electrochemically irreversible with diffusion controlled. • The oxidation of Cl − in BMIMBF 4 is more likely to form tri-chloride ion, Cl 3 − but not chlorine, Cl 2 . • The minute amount of Cl 2 detected after electrolysis forms according to the equilibrium of Cl 2 + Cl − ⇌ Cl 3 − . -- Abstract: The oxidation behavior of chloride ions on platinum electrodes was investigated in a natural ionic liquid, 1-butyl-3-methyl-limidazolium tetrafluoroborate (BMIMBF 4 ) in the presence of high concentrations of 1-butyl-3-methyl-limidazolium chloride (BMIMCl). Analysis of the electrode reaction was explored using cyclic voltammetry, and chronoamperometry with a platinum micro-disk electrode, and bulk potentiostatic electrolysis and UV–vis spectroscopy. The anodic oxidation of chloride ions on the platinum micro-disk electrode in the mixture was considered to be an irreversible process with diffusion controlled as revealed by cyclic voltammetry. The diffusion coefficient, D, and the number of electrons transferred, n, for anodic oxidation of Cl − in BMIMBF 4 derived from results of chronoamperometry revealed that the oxidation of chloride ions was more likely to form tri-chloride ion, Cl 3 − but not chlorine, Cl 2 . Bulk electrolysis and UV–vis spectroscopy further confirmed that the tri-chloride ion was the main product from the overall oxidation of the chloride ion

  7. Mesoporous Silicon-Based Anodes

    Science.gov (United States)

    Peramunage, Dharmasena

    2015-01-01

    For high-capacity, high-performance lithium-ion batteries. A new high-capacity anode composite based on mesoporous silicon is being developed. With a structure that resembles a pseudo one-dimensional phase, the active anode material will accommodate significant volume changes expected upon alloying and dealloying with lithium (Li).

  8. Anodic Concentration Polarization in SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Williford, Rick E.; Chick, Lawrence A.; Maupin, Gary D.; Simner, Steve P.; Stevenson, Jeffry W.; Khaleel, Mohammad A.; Wachsman, ED, et al

    2003-08-01

    Concentration polarization is important because it determines the maximum power output of a solid oxide fuel cell (SOFC) at high fuel utilization. Anodic concentration polarization occurs when the demand for reactants exceeds the capacity of the porous ceramic anode to supply them by gas diffusion mechanisms. High tortuosities (bulk diffusion resistances) are often assumed to explain this behavior. However, recent experiments show that anodic concentration polarization originates in the immediate vicinity of the reactive triple phase boundary (TPB) sites near the anode/electrolyte interface. A model is proposed to describe how concentration polarization is controlled by two localized phenomena: competitive adsorption of reactants in areas adjacent to the reactive TPB sites, followed by relatively slow surface diffusion to the reactive sites. Results suggest that future SOFC design improvements should focus on optimization of the reactive area, adsorption, and surface diffusion at the anode/electrolyte interface.

  9. Electrochemical performance and interfacial investigation on Si composite anode for lithium ion batteries in full cell

    Science.gov (United States)

    Shobukawa, Hitoshi; Alvarado, Judith; Yang, Yangyuchen; Meng, Ying Shirley

    2017-08-01

    Lithium ion batteries (LIBs) containing silicon (Si) as a negative electrode have gained much attention recently because they deliver high energy density. However, the commercialization of LIBs with Si anode is limited due to the unstable electrochemical performance associated with expansion and contraction during electrochemical cycling. This study investigates the electrochemical performance and degradation mechanism of a full cell containing Si composite anode and LiFePO4 (lithium iron phosphate (LFP)) cathode. Enhanced electrochemical cycling performance is observed when the full cell is cycled with fluoroethylene carbonate (FEC) additive compared to the standard electrolyte. To understand the improvement in the electrochemical performance, x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) are used. Based on the electrochemical behavior, FEC improves the reversibility of lithium ion diffusion into the solid electrolyte interphase (SEI) on the Si composite anode. Moreover, XPS analysis demonstrates that the SEI composition generated from the addition of FEC consists of a large amount of LiF and less carbonate species, which leads to better capacity retention over 40 cycles. The effective SEI successively yields more stable capacity retention and enhances the reversibility of lithium ion diffusion through the interphase of the Si anode, even at higher discharge rate. This study contributes to a basic comprehension of electrochemical performance and SEI formation of LIB full cells with a high loading Si composite anode.

  10. Voltammetry of Organic Pollutants on FeOOH Nanorods

    International Nuclear Information System (INIS)

    Zhang, Yuanyuan; Wan, Qijin; Yang, Nianjun

    2017-01-01

    FeOOH nanorods synthesized using a solvothermal approach have been employed to investigate the electrochemistry of organic pollutions, including ponceau 4R (PR), sunset yellow (SY), and tetrabromobisphenol A (TBBPA). The as-prepared FeOOH nanorods have been characterized using scanning electron microscopes (SEM), transmission electron microscope (TEM), X-ray photoelectron spectrometry, Brunauer-Emmett-Teller measurements, and electrochemical techniques. The modified electrode based on FeOOH nanorods exhibits a porous and net-like structure, resulting in a high surface area and many reactive/adsorption sites for soluble compounds. On this modified electrode, fast electron transfer processes of redox probes have been achieved. Electrochemistry of PR, SY, and TBBPA has been studied in detail using voltammetry, impedance, and chronocoulometry. The sensitive monitoring of both individual and total concentrations of three organic pollutions has been realized. The detection limits are 0.2, 1.0, and 0.55 nM for PR, SY, and TBBPA, respectively. Such an electrode is then promising for the electrochemical investigation and analysis of organic pollutions in different environments.

  11. Kinetics of degradation of ascorbic acid by cyclic voltammetry method

    Directory of Open Access Journals (Sweden)

    Grudić Veselinka V.

    2015-01-01

    Full Text Available Cyclic voltammetry was used to examine the kinetics of degradation of ascorbic acid (AA at different temperatures. It has been shown that the reduction of the concentration of AA in all temperatures follow the kinetics of the first order reaction. The rate constant of the oxidation reaction increases with temperature as follows: 5x10-5; 2x10-4; 1x10-3 and 3x10-3 min-1 at temperatures of 25°C, 35°C, 65°C and 90°C, respectively. The temperature dependence of the rate constant follows Arrhenius equation, and the value of activation energy of the reaction degradation is 48.2 kJ mol-1 . The effect of storage time at a temperature of 90 °C on AA content in fresh juice of green peppers was investigated. It was shown that AA oxidation reaction in the juice is also the first order reaction, while the lower rate constant in relation to the pure AA (5x10-3 min-1 indicates the influence of other substances present in peppers.

  12. Voltammetry of redox analytes at trace concentrations with nanoelectrode ensembles.

    Science.gov (United States)

    Moretto, Ligia Maria; Pepe, Niki; Ugo, Paolo

    2004-04-19

    Gold nanoelectrodes ensembles (NEEs) have been prepared by electroless plating of Au nanoelectrode elements within the pores of a microporous polycarbonate template membrane. Cyclic voltammograms recorded in (ferrocenylmethyl) trimethylammonium hexafluorophosphate (FA(+) PF(6)(-)) solutions showed that these NEEs operate in the "total-overlap" response regime, giving well resolved peak shaped voltammograms. Experimental results show that the faradaic/background currents ratios at the NEE are independent on the total geometric area of the ensemble, so that NEE can be enlarged or miniaturized at pleasure without influencing the very favorable signal/noise ratio. Differential pulse voltammetry (DPV) at the NEE is optimized for direct determinations at trace levels. DPV at NEE allowed the determination (with no preconcentration) of trace amounts of FA(+), with a detection limit of 0.02muM. The use of NEE and DPV in cytochrome c (cyt c) solutions showed the possibility to observe the direct electrochemistry of submicromolar concentration of the protein, even without the need of adding any promoter or mediator.

  13. Cyclic voltammetry and RBS study of paint components

    International Nuclear Information System (INIS)

    Bowman, Lynn; Spencer, Dirk; Muntele, Claudiu; Muntele, Iulia; Ila, D.

    2007-01-01

    Heavy metals and metalloid ions are found in environmental matrices. The most toxic are lead, cadmium and mercury. These three heavy metals have no biological function and are toxic at all concentrations. Lead is one of the most insidious heavy metals and is introduced into the environment by many different means. It persists in both urban and rural settings, being found in paint chips, pottery, crystal and pharmaceutical and nutritional products. The analysis of heavy elements such as lead in soil is of particular importance [W.T. Sturges, R.M. Harrison, Sci. Total Environ. 44 (3) (1985) 225; M.L. Lepow, L. Bruckman, M. Gillette, S. Markowitz, R. Robino, J. Kapish, Environ. Res. 10 (3) (1975) 415; A.E. Daniels, J.R. Kominsky, P.J. Clark, J. Hazard. Mater. B 87 (2001) 117; G. Hutter, D. Moshman, J. Hazard. Mater. 40 (1995) 1]. In preparing the methods for lead detection in paint, we have used Rutherford backscattering spectrometry (RBS) in order to study the type and amount of heavy metal content in paint samples collected at various sites in the historic campus at A and M University (AAMU). We will show the results of our study with emphasis on comparison of what we learned about presence of lead in paints using our ion beam methods compared with the analysis of lead in paints using cyclic voltammetry

  14. Optical strip waveguide: an analysis.

    Science.gov (United States)

    Ogusu, K; Kawakami, S; Nishida, S

    1979-03-15

    An analysis of the strip waveguide is presented with special emphasis on reflection and transmission of a wave obliquely incident on the side of a strip. Mode conversion and the contribution of radiation modes are taken into account in the formulation. The numerical results of the mode conversion and attenuation constant of the fundamental leaky mode are presented and compared with the results of other authors. The numerical accuracy of our analysis is also checked by two different procedures. It is found that the radiation modes have considerable effects on the waveguide characteristics.

  15. Cyclic Voltammetry Probe Approach Curves with Alkali Amalgams at Mercury Sphere-Cap Scanning Electrochemical Microscopy Probes.

    Science.gov (United States)

    Barton, Zachary J; Rodríguez-López, Joaquín

    2017-03-07

    We report a method of precisely positioning a Hg-based ultramicroelectrode (UME) for scanning electrochemical microscopy (SECM) investigations of any substrate. Hg-based probes are capable of performing amalgamation reactions with metal cations, which avoid unwanted side reactions and positive feedback mechanisms that can prove problematic for traditional probe positioning methods. However, prolonged collection of ions eventually leads to saturation of the amalgam accompanied by irreversible loss of Hg. In order to obtain negative feedback positioning control without risking damage to the SECM probe, we implement cyclic voltammetry probe approach surfaces (CV-PASs), consisting of CVs performed between incremental motor movements. The amalgamation current, peak stripping current, and integrated stripping charge extracted from a shared CV-PAS give three distinct probe approach curves (CV-PACs), which can be used to determine the tip-substrate gap to within 1% of the probe radius. Using finite element simulations, we establish a new protocol for fitting any CV-PAC and demonstrate its validity with experimental results for sodium and potassium ions in propylene carbonate by obtaining over 3 orders of magnitude greater accuracy and more than 20-fold greater precision than existing methods. Considering the timescales of diffusion and amalgam saturation, we also present limiting conditions for obtaining and fitting CV-PAC data. The ion-specific signals isolated in CV-PACs allow precise and accurate positioning of Hg-based SECM probes over any sample and enable the deployment of CV-PAS SECM as an analytical tool for traditionally challenging conditions.

  16. Investigation of the Reversible Lithiation of an Oxide Free Aluminum Anode by a LiBH4 Solid State Electrolyte

    Directory of Open Access Journals (Sweden)

    Jason A. Weeks

    2017-11-01

    Full Text Available In this study, we analyze and compare the physical and electrochemical properties of an all solid-state cell utilizing LiBH4 as the electrolyte and aluminum as the active anode material. The system was characterized by galvanostatic lithiation/delithiation, cyclic voltammetry (CV, X-ray diffraction (XRD, energy dispersive X-ray spectroscopy (EDS, Raman spectroscopy, electrochemical impedance spectroscopy (EIS, and scanning electron microscopy (SEM. Constant current cycling demonstrated that the aluminum anode can be reversibly lithiated over multiple cycles utilizing a solid-state electrolyte. An initial capacity of 895 mAh/g was observed and is close to the theoretical capacity of aluminum. Cyclic voltammetry of the cell was consistent with the constant current cycling data and showed that the reversible lithiation/delithiation of aluminum occurs at 0.32 V and 0.38 V (vs. Li+/Li respectively. XRD of the aluminum anode in the initial and lithiated state clearly showed the formation of a LiAl (1:1 alloy. SEM-EDS was utilized to examine the morphological changes that occur within the electrode during cycling. This work is the first example of reversible lithiation of aluminum in a solid-state cell and further emphasizes the robust nature of the LiBH4 electrolyte. This demonstrates the possibility of utilizing other high capacity anode materials with a LiBH4 based solid electrolyte in all-solid-state batteries.

  17. Cyclic voltammetry study of Ce(IV/Ce(III redox couple and Ce(IV-F complex in sulfuric acid medium

    Directory of Open Access Journals (Sweden)

    J. G. He

    2016-10-01

    Full Text Available In this paper the electrochemical behaviors of Ce(IV/Ce(III redox couple and Ce(IV - F complex in sulfuric acid medium were studied by cyclic voltammetry using a platinum electrode. Both of the Ce(IV/Ce(III couple in Ce(IV solution and Ce(IV - F complex is a quasi-reversible process, and gives a linear correlation between the peak potentials and square root of scan rates, showing that the kinetics of the overall process is diffusion controlled. The complexation of cerium(IV and fluoride is favorable for the oxidation of Ce(III. The kinetic parameters such as diffusion coefficients, anodic transfer coefficients and rate constants were studied.

  18. Surface modification of pyrolyzed carbon fibres by cyclic voltammetry and their characterization with XPS and dye adsorption

    International Nuclear Information System (INIS)

    Georgiou, P.; Walton, J.; Simitzis, J.

    2010-01-01

    Commercial carbon fibres were pyrolyzed up to 1000 deg. C and were then electrochemically treated by cyclic voltammetry in aqueous electrolyte solutions of H 2 SO 4 , in two potential sweep ranges: a narrow region, N, and a wide region, W, avoiding and including water decomposition, respectively. The anodic and cathodic peaks were correlated with oxide formation and their partial reduction, respectively. The nature of oxygen containing groups on the fibre surfaces was determined by XPS. Wide scan spectra and high energy resolution spectra were recorded through the C 1s, O 1s, N 1s and S 2p photoelectron regions. The ability of the fibres to adsorb methylene blue and alizarin yellow dyes from their aqueous solutions indicates the presence of electron acceptor or donor groups on the fibres, respectively. The carbon fibres were classified into two categories. The first includes electrochemically untreated and treated in the N region, and the second those treated in the W region. The high oxygen concentration and effective dye adsorption on the carbon fibres in the second category indicates that their surfaces were effectively modified. The adsorption of dyes on carbon fibres constitutes a complementary method to XPS for an indirect estimation of oxygen and other groups present on the carbon fibre surfaces.

  19. Suitability of the voltammetry of immobilized microparticles to detect and discriminate lead compounds in microsamples of ancient black cosmetics

    International Nuclear Information System (INIS)

    Pérez-Arantegui, Josefina; Cepriá, Gemma

    2014-01-01

    Lead compounds, in the form of galena, have been used as eye cosmetics since ancient times and they still appear in traditional products. The presence of some black pigments in several archaeological glass objects gave us the opportunity to study the nature of these products, in order to evaluate the results of an electrochemical method to characterise lead compounds when only heterogeneous microsamples are available and the material requires to be as less manipulated as possible. The present paper describes the data obtained with an electroanalytical methodology (Voltammetry of immobilised microparticles, VMP), and a complementary Scanning Electron Microscopy study, to detect these lead compounds. A simple and fast characterisation method is discussed in order to be able to monitor the presence of lead compounds without previous sample preparation, directly in the solid micro-sample, and using an affordable instrumentation. PbS could be identified and distinguished from other lead compounds in cosmetics by Differential Pulse VMP in 1 M NaCl medium by a set of three peaks (−0.63 V, −0.44 V, +0.45 V) in the anodic voltammogram and two peaks around −0.65 V and +0.45 V in the cathodic scan. The results showed the suitability of the electroanalytical method, offering valuable information about the chemical and mineral composition of the samples using a minimum amount of material, and illustrating the advantages in terms of time consuming, cost and accessibility of the laboratory facilities

  20. Adsorption and desorption of bis-(3-sulfopropyl) disulfide during Cu electrodeposition and stripping at Au electrodes.

    Science.gov (United States)

    Chiu, Yong-Da; Dow, Wei-Ping; Krug, Klaus; Liu, Yung-Fang; Lee, Yuh-Lang; Yau, Shueh-Lin

    2012-10-09

    The adsorption and desorption of bis-(3-sulfopropyl) disulfide (SPS) on Cu and Au electrodes and its electrochemical effect on Cu deposition and dissolution were examined using cyclic voltammetry stripping (CVS), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). SPS dissociates into 3-mercapto-1-propanesulfonate when it is contacted with Au and Cu electrodes, producing Cu(I)- and Au(I)-thiolate species. These thiolates couple with chloride ions and promote not only the reduction of Cu(2+) in Cu deposition but also the oxidation of Cu(0) to Cu(+) in Cu stripping. During Cu electrodeposition on the SPS-modified Au electrode, thiolates transfer from Au onto the Cu underpotential deposition (UPD) layer. The Cu UPD layer stabilizes a large part of the transferred thiolates which subsequently is buried by the Cu overpotential deposition (OPD) layer. The buried thiolates reappear on the Au electrode after the copper deposit is electrochemically stripped off. A much smaller part of thiolates transfers to the top of the Cu OPD layer. In contrast, when SPS preadsorbs on a Cu-coated Au electrode, almost all of the adsorbed SPS leaves the Cu surface during Cu electrochemical stripping and does not return to the uncovered Au surface. A reaction mechanism is proposed to explain these results.

  1. Electrocatalytic properties and stability of titanium anodes activated by the inorganic sol–gel procedure

    Directory of Open Access Journals (Sweden)

    VLADIMIR V. PANIC

    2008-10-01

    Full Text Available The properties of activated titanium anodes, RuO2–TiO2/Ti and RuO2–TiO2–IrO2/Ti, prepared from oxide sols by the sol–gel procedure, are reviewed. RuO2 and TiO2 sols were synthesized by forced hydrolysis of the corresponding chlorides in acid medium. The morphology of the prepared sols was investigated by transmission electron microscopy. The chemical composition of the RuO2 sol was determined by X-ray diffraction and thermogravimetric analysis. The loss of electrocatalytic activity of a RuO2–TiO2/Ti anode during an accelerated stability test was investigated by examination of the changes in the electrochemical characteristics in the potential region of the chlorine and oxygen evolution reaction, as well as on the open circuit potential. These electrochemical characteristics were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and polarization measurements. The changes in electrochemical characteristics of the anode prepared by the sol–gel procedure were compared to the changes registered for an anode prepared by the traditional thermal decomposition of metal chlorides. The comparison indicated that the main cause for the activity loss of the sol–gel prepared anode was the electrochemical dissolution of RuO2, while in the case of thermally prepared anode the loss was mainly caused by the formation of an insulating TiO2 layer in the coating/Ti substrate interphase. The results of an accelerated stability test on RuO2–TiO2/Ti and RuO2–TiO2–IrO2/Ti anodes showed that the ternary coating is considerably more stable than the binary one, which is the consequence of the greater stability of IrO2 in comparison to RuO2.

  2. Stripping and bulk CO electro-oxidation at the Pt-electrode interface: Dynamic Monte Carlo simulations

    Science.gov (United States)

    Saravanan, Chandra; Markovic, N. M.; Head-Gordon, M.; Ross, P. N.

    2001-04-01

    We perform dynamic Monte Carlo simulations to understand the kinetics of CO oxidation on Pt surface. Our simulations are performed on a model for CO electro-oxidation, where oxygen-containing species (adsorbed OH) formed on the Pt surface reacts with adsorbed CO by a Langmuir-Hinshelwood mechanism to form CO2. A systematic study of the model parameters shows that we obtain better electrocatalytic activity by increasing the surface diffusion coefficient of CO (kD) or the rate of reaction between adsorbed CO and adsorbed OH. We also show that if the initial state of adsorbed CO is a closely packed structure, increasing the surface coverage can result in negative voltammetry peak shifts because of the formation of weakly adsorbed states of CO. We have also modeled bulk CO voltammetry by introducing a CO adsorption rate, k4. We show that near-zero currents are obtained for the potentials (E) where the rate of OH adsorption, k1(E), is much smaller than k4. We also note that kD plays no significant role in CO oxidation when kD≪k4. Our results also show that bulk CO voltammetry peaks shift to more positive potentials compared to the stripping, as observed in experiments. Our potential step simulations show no difference in bulk and stripping current transients in the potential regions where k1(E)≫k4, whereas they vary significantly when k4≅k1(E).

  3. Selection of a Commercial Anode Oxide Coating for Electro-oxidation of Cyanide

    Directory of Open Access Journals (Sweden)

    Lanza Marcos Roberto V.

    2002-01-01

    Full Text Available This paper presents a study of the performance of two commercial dimensionally stable anode (DSA® oxide coatings in the electrochemical process for cyanide oxidation. The coatings studied were 70TiO2/30RuO2 and 55Ta2O5/45IrO2, on Ti substrate. The efficiency of both materials in the electro-oxidation of free cyanide was compared using linear voltammetry and electrolysis at constant potential. The 70TiO2/30RuO2 electrode shows a better performance in the electro-oxidation of free cyanide.

  4. Lithium intercalation and interfacial kinetics of composite anodes formed by oxidized graphite and copper

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, M.; Nobili, F.; Dsoke, S.; Tossici, R.; Marassi, R. [Dipartimento di Scienze Chimiche, Universita di Camerino, Via S. Agostino, 1, 62032 Camerino (MC) (Italy); D' Amico, F. [Dipartimento di Fisica, Universita di Camerino, Via Madonna delle Carceri, 9, 62032 Camerino (MC) (Italy); Croce, F. [Dipartimento di Scienze del Farmaco, Universita degli Studi ' ' G. D' Annunzio' ' , Via dei Vestini, 31, 66013 Chieti (Italy)

    2009-05-01

    The electrochemical behavior of composite anodes prepared either by mixing partially oxidized graphite and Cu powders or by coating the pristine partially oxidized graphite electrodes with few-nanometer-thick Cu layers has been studied by slow-scan-rate cyclic voltammetry (SSCV) and galvanostatic charge/discharge cycles over the temperature range of -30 C to 20 C. The interfacial intercalation/deintercalation kinetics has also been investigated using electrochemical impedance spectroscopy (EIS). The role of the Cu in improving low-temperature performances and kinetics of graphite electrodes is discussed. (author)

  5. Porous Al Current Collector for Dendrite-Free Na Metal Anodes.

    Science.gov (United States)

    Liu, Shan; Tang, Shan; Zhang, Xinyue; Wang, Aoxuan; Yang, Quan-Hong; Luo, Jiayan

    2017-09-13

    Na-based batteries are proposed as promising energy storage candidates for beyond Li-ion technology due to the higher natural earth of Na metal. For its high capacity and low potential, Na metal may carve itself a niche when directly used as anodes. Similar to or even more problematic than Li, however, uneven plating/stripping of Na leads to dendrite formation. As the plating substrates, current collectors have a paramount influence on the Na plating/stripping behaviors. Here we propose porous Al current collectors as the plating substrate to suppress Na dendrites. Al does not alloy with Na. It is advantageous over Cu current collectors in terms of cost and weight. The interconnected porous structure can increase available surface for Na to nucleate and decrease the Na + flux distribution, leading to homogeneous plating. The Na metal anodes can run for over 1000 cycles on porous Al with a low and stable voltage hysteresis and their average plating/stripping Coulombic efficiency was above 99.9%, which is greatly improved compared to planar Al. We used the porous Al for Na-O 2 , Na-Na 3 V 2 (PO 4 ) 3 cells with low Na amount and anode free Na-TiS 2 batteries and anticipate that using this strategy can be combined with further electrolyte and cathodes to develop high performance Na-based batteries.

  6. Buttock Lifting with Polypropylene Strips.

    Science.gov (United States)

    Ballivian Rico, José; Esteche, Atilio; Hanke, Carlos José Ramírez; Ribeiro, Ricardo Cavalcanti

    2016-04-01

    The purpose of this study was to evaluate the results of gluteal suspension with polypropylene strips. Ninety healthy female patients between the ages of 20 and 50 years (mean, 26 years), who wished to remodel their buttocks from December 2004 to February 2013 were studied retrospectively. All 90 patients were treated with 2 strips of polypropylene on each buttock using the following procedures: 27 (30 %) patients were suspended with polypropylene strips; 63 (70 %) patients were treated with tumescent liposuction in the sacral "V", lower back, supragluteal regions, and flanks to improve buttocks contour (aspirated volume of fat from 350 to 800 cc); 16 (18 %) patients underwent fat grafting in the subcutaneous and intramuscular layers (up to 300 cc in each buttock to increase volume); 5 (6 %) patients received implants to increase volume; and 4 (4.4 %) patients underwent removal and relocation of intramuscular gluteal implants to improve esthetics. Over an 8-year period, 90 female patients underwent gluteal suspension surgeries. Good esthetic results without complications were obtained in 75 of 90 (84 %) cases. Complications occurred in 15 of 90 (16.6 %) patients, including strip removal due to postoperative pain in 1 (1.1 %) patient, and seroma in both subgluteal sulci in 3 (3.3 %) patients. The results of this study performed in 90 patients over 8 years showed that the suspension with polypropylene strips performed as a single procedure or in combination with other cosmetic methods helps to enhance and lift ptosed gluteal and paragluteal areas. This journal requires that the authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

  7. Novel Anode Catalyst for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    S. Basri

    2014-01-01

    Full Text Available PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni and iron (Fe. Multiwalled carbon nanotubes (MWCNTs are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX, X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, and X-ray photoelectron spectroscopy (XPS, are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR. The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2–5 nm PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g−1 catalyst.

  8. Novel anode catalyst for direct methanol fuel cells.

    Science.gov (United States)

    Basri, S; Kamarudin, S K; Daud, W R W; Yaakob, Z; Kadhum, A A H

    2014-01-01

    PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs) but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni) and iron (Fe). Multiwalled carbon nanotubes (MWCNTs) are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV) is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA) tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR). The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2-5 nm) PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g(-1) catalyst.

  9. Note: Simulation and test of a strip source electron gun.

    Science.gov (United States)

    Iqbal, Munawar; Islam, G U; Misbah, I; Iqbal, O; Zhou, Z

    2014-06-01

    We present simulation and test of an indirectly heated strip source electron beam gun assembly using Stanford Linear Accelerator Center (SLAC) electron beam trajectory program. The beam is now sharply focused with 3.04 mm diameter in the post anode region at 15.9 mm. The measured emission current and emission density were 1.12 A and 1.15 A/cm(2), respectively, that corresponds to power density of 11.5 kW/cm(2), at 10 kV acceleration potential. The simulated results were compared with then and now experiments and found in agreement. The gun is without any biasing, electrostatic and magnetic fields; hence simple and inexpensive. Moreover, it is now more powerful and is useful for accelerators technology due to high emission and low emittance parameters.

  10. Rechargeable lithium and sodium anodes in chloroaluminate molten salts containing thionyl chloride

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, J.; Osteryoung, R.A. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Chemistry; Carlin, R.T.

    1995-11-01

    Lithium and sodium deposition-stripping studies were performed in room temperature buffered neutral chloroaluminate melts containing low concentrations of thionyl chloride (SOCl{sub 2}). The SOCl{sub 2} solute promotes high cycling efficiencies of the alkali metals in these electrolytes. Staircase cyclic voltammetry and chronopotentiometry show cycling efficiencies of approximately 90% for both lithium and sodium. High cycling efficiencies are maintained following extended exposure of the melt to the dry box atmosphere and after time delays at open circuit. The performance of the SOCl{sub 2}-promoted systems is substantially improved over previous studies in room temperature melts containing hydrogen chloride as the promoting solute.

  11. High pressure anode operation of direct methanol fuel cells for carbon dioxide management

    Science.gov (United States)

    Lundin, Michael D.; McCready, Mark J.

    Experiments with independent pressurization of the direct methanol fuel cell anode and cathode allow for the observation of DMFC operation with carbon dioxide gas formation suppressed. Results indicate that the limiting current density is strongly related to the applied pressure, and, therefore, to the presence of CO 2 in the liquid phase. An additional experiment where CO 2 is allowed to accumulate in recycled anode fuel solution over a period of time and is then stripped from solution using nitrogen gas indicates that the presence of CO 2 in anode fuel solution at any pressure contributes to significant decreases in power and current density. Because CO 2 bubbles are ubiquitous in direct methanol fuel cells, this finding is key to the optimization of these systems.

  12. Cyclic voltammetric behaviour of dimensionally stable anodes in the presence of C1 - C3 aldehydes

    Directory of Open Access Journals (Sweden)

    Malpass Geoffroy R. P.

    2003-01-01

    Full Text Available This work describes the cyclic voltammetry study of three aliphatic aldehydes: formaldehyde, acetaldehyde and propionaldehyde at dimensionally stable anodes (DSA®. Electrodes of nominal composition Ti/Ru0.3M0.7O2 (where M = Ti ou Sn were used in 0.5 mol dm-3 H2SO4 in a filter-press cell. Both electrodes exhibit behaviour typical of such materials in the presence of formaldehyde. However, with acetaldehyde and propionaldehyde non-typical behaviour is observed. This is characterised by a fall in the normalised faradaic anodic charge (q nf and also a decrease in the current density associated with the oxygen evolution reaction (OER. A possible reaction mechanism, considering the direct oxidation of the aldehyde at the electrode surface, is suggested.

  13. Electrocoagulation of whey acids: anode and cathode materials, electroactive area and polarization curves

    Directory of Open Access Journals (Sweden)

    Francisco Prieto Garcia

    2017-06-01

    Full Text Available Anode (Al and Fe and cathode (graphite and Ti/RuO2 materials have been tested for electrocoagulation (EC and purification of the acid whey. The electroactive areas (EA of electrodes were calculated by the double layer capacitance method. Experiments were performed by cyclic voltammetry, chronoamperometry and polarization experiments. Among cathodic materials, the Ti/RuO2 electrode showed higher EA (2167 cm2 than graphite (1560 cm2. The Fe anode was found more stable than Al with greater charge transfer carried out in less time. Correlation of these results with those obtained during preliminary tests confirmed high removals (79 % in 8 h. For the Al electrode, 24 h were required to achieve efficiency of 49 %.

  14. Electrolysis of metal oxides in MgCl2 based molten salts with an inert graphite anode.

    Science.gov (United States)

    Yuan, Yating; Li, Wei; Chen, Hualin; Wang, Zhiyong; Jin, Xianbo; Chen, George Z

    2016-08-15

    Electrolysis of solid metal oxides has been demonstrated in MgCl2-NaCl-KCl melt at 700 °C taking the electrolysis of Ta2O5 as an example. Both the cathodic and anodic processes have been investigated using cyclic voltammetry, and potentiostatic and constant voltage electrolysis, with the cathodic products analysed by XRD and SEM and the anodic products by GC. Fast electrolysis of Ta2O5 against a graphite anode has been realized at a cell voltage of 2 V, or a total overpotential of about 400 mV. The energy consumption was about 1 kW h kgTa(-1) with a nearly 100% Ta recovery. The cathodic product was nanometer Ta powder with sizes of about 50 nm. The main anodic product was Cl2 gas, together with about 1 mol% O2 gas and trace amounts of CO. The graphite anode was found to be an excellent inert anode. These results promise an environmentally-friendly and energy efficient method for metal extraction by electrolysis of metal oxides in MgCl2 based molten salts.

  15. Synthesis of bismuth (III oxide films based anodes for electrochemical degradation of reactive blue 19 and crystal violet

    Directory of Open Access Journals (Sweden)

    Petrović Milica M.

    2014-01-01

    Full Text Available The Bi2O3 films-based anodes were synthesized by electrodeposition of Bi on stainless steel substrate at constant current density and during different deposition times, fallowed by calcination, forming Bi2O3. The thickness of the films was determined by two methods: the observation under the microscope and by calculation from mass difference. Electrochemical proceses at the anodes were ivestigated by linear sweep voltammetry. At the anodes obtained within 2, 5, 10 and 15 minutes of deposition, two dyes, namely: Reactive Blue 19 and Crystal Violet, were decolorized by oxidation with •OH radical, generated from H2O2 decomposition at the anodes. Decoloration times of the anodes varied, and the shortest one was achieved with the anode obtained during 5 minutes of deposition, with the film thickness of 2.5±0.3 μm. The optimal H2O2 concentration for the dyes degradation was found to be 10 mmol dm-3. [Projekat Ministarstva nauke Republike Srbije, br. ТR 34008

  16. The 2D-Micro Hole & Strip Plate in CF4 atmosphere aiming neutron imaging

    Science.gov (United States)

    Natal da Luz, H.; Gouvêa, A. L.; Mir, J. A.; dos Santos, J. M. F.; Veloso, J. F. C. A.

    2009-12-01

    The Micro Hole & Strip Plate (MHSP) achieves gains above 300 in tetrafluoromethane (CF4) at 2.6 bar, making it suitable for neutron detection. Over the past few years, the imaging capabilities of the MHSP have been developed, leading to the 2D-MHSP. In this device, the position coordinates are determined using the principle of resistive charge division. The GEM-side was specially patterned in strips interconnected by a resistive strip for one of the coordinates and, in the MS-side, the anode strips were also interconnected by another resistive strip. By applying a trivial center of mass algorithm it is possible to obtain both coordinates and the energy of each detected event. The ability to register position and energy for each event can be very useful for event validation in neutron detection. In this work, the performance of the 2D-MHSP in CF4 is investigated. The Modular Transfer Function (MTF) is presented, showing that position resolutions of 700μm in x and 1 mm in the y-direction are obtained with X-rays. It is also demonstrated that resolutions below the proton range (1 mm) are possible at 2.6 bar CF4, demonstrating that the MHSP can be a cost effective choice for neutron imaging.

  17. Nano structural anodes for radiation detectors

    Science.gov (United States)

    Cordaro, Joseph V.; Serkiz, Steven M.; McWhorter, Christopher S.; Sexton, Lindsay T.; Retterer, Scott T.

    2015-07-07

    Anodes for proportional radiation counters and a process of making the anodes is provided. The nano-sized anodes when present within an anode array provide: significantly higher detection efficiencies due to the inherently higher electric field, are amenable to miniaturization, have low power requirements, and exhibit a small electromagnetic field signal. The nano-sized anodes with the incorporation of neutron absorbing elements (e.g., .sup.10B) allow the use of neutron detectors that do not use .sup.3He.

  18. Anodic behavior of uranium in AlCl3-1-ethyl-3-methyl-imidazolium chloride ionic liquid

    Science.gov (United States)

    Jiang, Yidong; Luo, Lizhu; Wang, Shaofei; Bin, Ren; Zhang, Guikai; Wang, Xiaolin

    2018-01-01

    The oxidation state of metals unambiguously affects its anodic behavior in ionic liquid. We systematically investigated the anodic behavior of uranium with different surface oxidation states by electrochemical measurements, spectroscopic methods and surface analysis techniques. In the anodic process, metal uranium can be oxidized to U3+. The corresponding products accumulated on the metal/ILs interface will form a viscous layer. The anodic behavior of uranium is also strongly dependent upon the surface oxide states including thickness and homogeneity of the oxide film. With an increase in the thickness of oxide film, it will be breached at potentials in excess of a critical value. A uniform oxide on uranium surface can be breached evenly, and then the underlying metal starts to dissolve forming a viscous layer which can facilitate uniformly stripping of oxide, thus giving an oxide-free surface. Otherwise, a nonuniform oxide can result in a severe pitted surface with residue oxygen.

  19. Voltammetry and Electrocatalysis of Achrornobacter Xylosoxidans Copper Nitrite Reductase on Functionalized Au(111)-Electrode Surfaces

    DEFF Research Database (Denmark)

    Welinder, Anna C.; Zhang, Jingdong; Hansen, Allan G.

    2007-01-01

    A long-standing issue in protein film voltammetry (PFV), particularly electrocatalytic voltammetry of redox enzyme monolayers, is the variability of protein adsorption modes, reflected in distributions of catalytic activity of the adsorbed protein/enzyme molecules. Use of well-defined, atomically...... planar electrode surfaces is a step towards the resolution of this central issue. We report here the voltammetry of copper nitrite reductase (CNiR, Achromobacter xylosoxidons) on Au(111)-electrode surfaces modified by monolayers of a broad variety of thiol-based linker molecules. These represent......NiR thus shows highly efficient, close to ideal reversible electrocatalytic voltammetry on cysteamine-covered Au(111)-electrode surfaces, most likely due to two cysteamine orientations previously disclosed by in situ scanning tunnelling microscopy. Such a dual orientation exposes both a hydrophobic...

  20. Influence of silver on the anodic corrosion and gas evolution of Pb-Sb-As-Se alloys as positive grids in lead acid batteries

    International Nuclear Information System (INIS)

    Tizpar, A.; Ghasemi, Z.

    2006-01-01

    The influence of silver addition in the range 0.01-0.09 wt.% on the anodic corrosion and gas evolution of Pb-Sb-As-Se alloy in 1.28 sp.gr. H 2 SO 4 solution at 25 deg. C was studied using linear sweep voltammetry, cyclic voltammetry, weight loss measurements and scanning electron microscopy. The results drawn from different techniques are comparable. The effect of different concentration of silver on the corrosion behavior of Pb-Sb-As-Se was investigated. The experimental results show that the silver added to Pb-Sb-As-Se alloy inhibits the growth of anodic corrosion layer. A decrease in the oxygen evolution overpotential and an increase in the hydrogen evolution overpotential with the addition of Ag were also observed during the experiments. Cyclic voltammetric measurements provided information on the effect of Ag on the oxidation of PbSO 4 to PbO 2

  1. The effect of the presence of alcohol in the dispersing phase of oxide sols on the properties of RuO2-TiO2/Ti anodes obtained by the sol–gel procedure

    Directory of Open Access Journals (Sweden)

    R. ATANASOSKI

    2000-09-01

    Full Text Available The effect of the addition of ethanol and 2-propanol to the dispersing phase of TiO2 and RuO2 sols mixture on the morphology and, consequently, on the electrochemical properties of the sol-gel obtained activated titanium anodes was investigated. The properties of the obtained anodes were compared to those obtained by the thermal decomposition of appropriate chloride salts. The morphology of the anode coatings was examined by scanning tunneling microscopy. The electrochemical behaviour was investigated by cyclic voltammetry and by polarization measurements. An accelerated stability test was used for the examination of the stability of the anodes under simultaneous oxygen and chlorine evolution reaction. A dependence of the anode stability on the type of added alcohol is indicated.

  2. Voltammetry and In Situ Scanning Tunneling Microscopy of Cytochrome c Nitrite Reductase on Au(111)-Electrodes

    DEFF Research Database (Denmark)

    Gwyer, James; Zhang, Jingdong; Butt, Julea

    2006-01-01

    of the density and orientational distribution of NrfA molecules are disclosed. The submonolayer coverage resolved by in situ STM is readily reconciled with the failure to detect nonturnover signals in cyclic voltammetry of the NrfA films. The molecular structures show a range of lateral dimensions...... a direct approach to correlate electrocatalytic and molecular properties of the protein layer, a long-standing issue in protein film voltammetry....

  3. Electrically Conductive Anodized Aluminum Surfaces

    Science.gov (United States)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  4. Controlling the occurrence of power overshoot by adapting microbial fuel cells to high anode potentials

    KAUST Repository

    Zhu, Xiuping

    2013-04-01

    Power density curves for microbial fuel cells (MFCs) often show power overshoot, resulting in inaccurate estimation of MFC performance at high current densities. The reasons for power overshoot are not well understood, but biofilm acclimation and development are known factors. In order to better explore the reasons for power overshoot, exoelectrogenic biofilms were developed at four different anode potentials (-0.46 V, -0.24 V, 0 V, and 0.50 V vs. Ag/AgCl), and then the properties of the biofilms were examined using polarization tests and cyclic voltammetry (CV). The maximum power density of the MFCs was 1200±100 mW/m2. Power overshoot was observed in MFCs incubated at -0.46 V, but not those acclimated atmore positive potentials, indicating that bacterial activitywas significantly influenced by the anode acclimation potential. CV results further indicated that power overshoot of MFCs incubated at the lowest anode potential was associatedwith a decreasing electroactivity of the anodic biofilm in the high potential region,which resulted from a lack of sufficient electron transfer components to shuttle electrons at rates needed for these more positive potentials. © 2012 Elsevier B.V.

  5. Collisional stripping of planetary crusts

    Science.gov (United States)

    Carter, Philip J.; Leinhardt, Zoë M.; Elliott, Tim; Stewart, Sarah T.; Walter, Michael J.

    2018-02-01

    Geochemical studies of planetary accretion and evolution have invoked various degrees of collisional erosion to explain differences in bulk composition between planets and chondrites. Here we undertake a full, dynamical evaluation of 'crustal stripping' during accretion and its key geochemical consequences. Crusts are expected to contain a significant fraction of planetary budgets of incompatible elements, which include the major heat producing nuclides. We present smoothed particle hydrodynamics simulations of collisions between differentiated rocky planetesimals and planetary embryos. We find that the crust is preferentially lost relative to the mantle during impacts, and we have developed a scaling law based on these simulations that approximates the mass of crust that remains in the largest remnant. Using this scaling law and a recent set of N-body simulations of terrestrial planet formation, we have estimated the maximum effect of crustal stripping on incompatible element abundances during the accretion of planetary embryos. We find that on average approximately one third of the initial crust is stripped from embryos as they accrete, which leads to a reduction of ∼20% in the budgets of the heat producing elements if the stripped crust does not reaccrete. Erosion of crusts can lead to non-chondritic ratios of incompatible elements, but the magnitude of this effect depends sensitively on the details of the crust-forming melting process on the planetesimals. The Lu/Hf system is fractionated for a wide range of crustal formation scenarios. Using eucrites (the products of planetesimal silicate melting, thought to represent the crust of Vesta) as a guide to the Lu/Hf of planetesimal crust partially lost during accretion, we predict the Earth could evolve to a superchondritic 176Hf/177Hf (3-5 parts per ten thousand) at present day. Such values are in keeping with compositional estimates of the bulk Earth. Stripping of planetary crusts during accretion can lead to

  6. Effects of Nafion loading in anode catalyst inks on the miniature direct formic acid fuel cell

    Science.gov (United States)

    Morgan, Robert D.; Haan, John L.; Masel, Richard I.

    Nafion, within the anode and cathode catalyst layers, plays a large role in the performance of fuel cells, especially during the operation of the direct formic acid fuel cell (DFAFC). Nafion affects the proton transfer in the catalyst layers of the fuel cell, and studies presented here show the effects of three different Nafion loadings, 10 wt.%, 30 wt.% and 50 wt.%. Short term voltage-current measurements using the three different loadings show that 30 wt.% Nafion loading in the anode shows the best performance in the miniature, passive DFAFC. Nafion also serves as a binder to help hold the catalyst nanoparticles onto the proton exchange membrane (PEM). The DFAFC anode temporarily needs to be regenerated by raising the anode potential to around 0.8 V vs. RHE to oxidize CO bound to the surface, but the Pourbaix diagram predicts that Pd will corrode at these potentials. We found that an anode loading of 30 wt.% Nafion showed the best stability, of the three Nafion loadings chosen, for reducing the amount of loss of electrochemically active area due to high regeneration potentials. Only 58% of the area was lost after 600 potential cycles in formic acid compared to 96 and 99% for 10 wt.% and 50 wt.% loadings, respectively. Lastly we present cyclic voltammetry data that suggest that the Nafion adds to the production of CO during oxidation of formic acid for 12 h at 0.3 V vs. RHE. The resulting data showed that an increase in CO coverage was observed with increasing Nafion content in the anode catalyst layer.

  7. Encapsulation of Metallic Na in an Electrically Conductive Host with Porous Channels as a Highly Stable Na Metal Anode.

    Science.gov (United States)

    Luo, Wei; Zhang, Ying; Xu, Shaomao; Dai, Jiaqi; Hitz, Emily; Li, Yiju; Yang, Chunpeng; Chen, Chaoji; Liu, Boyang; Hu, Liangbing

    2017-06-14

    Room-temperature Na ion batteries (NIBs) have attracted great attention because of the widely available, abundant sodium resources and potentially low cost. Currently, the challenge of the NIB development is due primarily to the lack of a high-performance anode, while the Na metal anode holds great promise considering its highest specific capacity of 1165 mA h/g and lowest anodic potential. However, an uneven deposit, relatively infinite volume change, and dendritic growth upon plating/stripping cycles cause a low Coulombic efficiency, poor cycling performance, and severe safety concerns. Here, a stable Na carbonized wood (Na-wood) composite anode was fabricated via a rapid melt infusion (about 5 s) into channels of carbonized wood by capillary action. The channels function as a high-surface-area, conductive, mechanically stable skeleton, which lowers the effective current density, ensures a uniform Na nucleation, and restricts the volume change over cycles. As a result, the Na-wood composite anode exhibited flat plating/stripping profiles with smaller overpotentials and stable cycling performance over 500 h at 1.0 mA/cm 2 in a common carbonate electrolyte system. In sharp comparison, the planar Na metal electrode showed a much shorter cycle life of 100 h under the same test conditions.

  8. Evaluation of Kefir as a New Anodic Biocatalyst Consortium for Microbial Fuel Cell.

    Science.gov (United States)

    Silveira, Gustavo; Schneedorf, José Maurício

    2018-02-21

    Kefir, a combined consortium of bacteria and yeast encapsulated by a polymeric matrix of exopolysaccharides, was used as anodic biocatalyst in a two-chamber microbial fuel cell (MFC). Fermentation was followed during 72 h and polarization curves were obtained from linear sweep voltammetry. The effect of methylene blue as charge-transfer mediator in the kefir metabolism was evaluated. UV/Vis spectrophotometry and cyclic voltammetry were applied to evaluate the redox state of the mediator and to characterize the electrochemical activity, whereas current interruption was used for internal resistance determination. Aiming to establish a relationship between the microbial development inside the anodic chamber with the generated power in the MFC, total titratable acidity, pH, viscosity, carbohydrate assimilation, and microbial counting were assayed. The kefir-based MFC demonstrated a maximum power density of 54 mW m -2 after 24 h fermentation, revealing the potential use of kefir as a biocatalyst for microbial fuel cells.

  9. Anodic galvanostatic polarization of AA2024-T3 aircraft alloy in conventional mineral acids

    Energy Technology Data Exchange (ETDEWEB)

    Kozhukharov, S., E-mail: stephko1980@abv.bg [Department of Chemical Sciences, University of Chemical Technology and Metallurgy, 8 “Kliment Okhridski” Blvd, 1756, Sofia (Bulgaria); Girginov, Ch. [Department of Chemical Sciences, University of Chemical Technology and Metallurgy, 8 “Kliment Okhridski” Blvd, 1756, Sofia (Bulgaria); Avramova, I. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Science, 11 “Georgi Bonchev” Str., 1113, Sofia (Bulgaria); Machkova, M. [Department of Chemical Sciences, University of Chemical Technology and Metallurgy, 8 “Kliment Okhridski” Blvd, 1756, Sofia (Bulgaria)

    2016-09-01

    The present study is devoted to the determination of the impact of the anodization of AA2024-T3 alloys in HCl, HNO{sub 3}, H{sub 2}SO{sub 4} or H{sub 3}PO{sub 4} on the samples’ surface morphology and properties. Subsequent systematic assessments were performed by Scanning Electron Microscopy (SEM), Energy Dispersion X-Ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS). These observations were combined with Linear Voltammetry (LVA) and Electrochemical Impedance Spectroscopy (EIS) after 48 and 168 h of exposure to a 3.5% NaCl model corrosive medium. The main result is, that completely different effects were observed in accordance to the acid used. It was established that the monoprotonic acids have a deep destructive effect due to dissolution of the alloy components, whereas the polyprotonic ones possess either indistinguishable influence, or surface film formation. - Highlights: • AA2024 was polarized anodically in 15%{sub wt} acid solutions at 15 mA cm{sup −2} for 2 h. • Four mineral acids were selected for investigation: HCl, HNO{sub 3}, H{sub 2}SO{sub 4} and H{sub 3}PO{sub 4}. • SEM, EDX and XPS were applied for morphological description. • Electrochemical characterizations were performed by EIS and linear voltammetry. • The acid used predetermines completely different interaction with the AA2024 alloy.

  10. Capacitively coupled pickup in MCP-based photodetectors using a conductive metallic anode

    Energy Technology Data Exchange (ETDEWEB)

    Angelico, E.; Seiss, T. [Enrico Fermi Institute, University of Chicago, 5640 S Ellis Ave, Chicago, IL 60637 (United States); Adams, B. [Incom, Inc., 294 SouthBridge Rd, Charlton, Massachusetts 01507 (United States); Elagin, A.; Frisch, H.; Spieglan, E. [Enrico Fermi Institute, University of Chicago, 5640 S Ellis Ave, Chicago, IL 60637 (United States)

    2017-02-21

    We have designed and tested a robust 20×20 cm{sup 2} thin metal film internal anode capacitively coupled to an external array of signal pads or micro-strips for use in fast microchannel plate photodetectors. The internal anode, in this case a 10 nm-thick NiCr film deposited on a 96% pure Al{sub 2}O{sub 3} 3 mm-thick ceramic plate and connected to HV ground, provides the return path for the electron cascade charge. The multi-channel pickup array consists of a printed-circuit card or glass plate with metal signal pickups on one side and the signal ground plane on the other. The pickup can be put in close proximity to the bottom outer surface of the sealed photodetector, with no electrical connections through the photodetector hermetic vacuum package other than a single ground connection to the internal anode. Two pickup patterns were tested using a small commercial MCP-PMT as the signal source: 1) parallel 50 Ω 25-cm-long micro-strips with an analog bandwidth of 1.5 GHz, and 2) a 20×20 cm{sup 2} array of 2-dimensional square ‘pads’ with sides of 1.27 cm or 2.54 cm. The rise-time of the fast input pulse is maintained for both pickup patterns. For the pad pattern, we observe 80% of the directly coupled amplitude. For the strip pattern we measure 34% of the directly coupled amplitude on the central strip of a broadened signal. The physical decoupling of the photodetector from the pickup pattern allows easy customization for different applications while maintaining high analog bandwidth.

  11. Simultaneous extraction and determination of trace amounts of diclofenac from whole blood using supported liquid membrane microextraction and fast fourier transform voltammetry.

    Science.gov (United States)

    Mofidi, Zahra; Norouzi, Parviz; Sajadian, Masumeh; Ganjali, Mohammad Reza

    2018-01-19

    A novel, simple and inexpensive analytical technique based on flat sheet supported liquid membrane microextraction coupled with fast Fourier transform stripping cyclic voltammetry on a reduced graphene oxide carbon paste electrode was used for the extraction and online determination of diclofenac in whole blood. First, diclofenac was extracted from blood samples using a polytetrafluoroethylene membrane impregnated with 1-octanol and then into an acceptor solution, subsequently it was oxidized on a carbon paste electrode modified with reduced graphene oxide nano-sheets. The optimal values of the key parameters influencing the method were; scan rate = 6 V s -1 , stripping potential = 200 mV, stripping time = 5 s, pH of the sample solution = 5, pH of the acceptor solution = 7, and extraction time = 240 min. The calibration curves were plotted for the whole blood samples and the method was found to have a good linearity within the range of 1-25 μg mL -1 with a determination coefficient of 0.99. The limits of detection and quantification were 0.1 and 1.0 μg mL -1 , respectively. Using this coupled method, the extraction and determination were merged into one step. Accordingly, the speed of detection for sensitive determination of diclofenac in complex samples like blood increased considerably. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  12. Dynamic Underground Stripping Demonstration Project

    International Nuclear Information System (INIS)

    Aines, R.; Newmark, R.; McConachie, W.; Rice, D.; Ramirez, A.; Siegel, W.; Buettner, M.; Daily, W.; Krauter, P.; Folsom, E.; Boegel, A.J.; Bishop, D.; udel, K.

    1992-03-01

    LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation and underground imaging techniques for use in rapid cleanup of localized underground spills. Called ''Dynamic Stripping'' to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first 8 months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques before moving to the contaminated site in FY 92

  13. 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

  14. Diffraction by a finite strip

    Science.gov (United States)

    Williams, M. H.

    1982-01-01

    A new approach is presented to diffraction problems involving plane strip barriers or slit apertures. These are problems that display the effects of multiple interacting edges. The approach taken here provides exact, compact solutions. The theory is introduced through a series of examples that are, in fact, the 'standard' problems of the subject, diffraction of a plane oblique wave by a slit, for example. In each case, the solutions are found to depend explicitly on a single 'special' function and its Fourier transform. These fundamental functions are described, with the emphasis placed on practical computational methods. The example problems are all couched in the language of acoustics.

  15. Anodic oxide films on tungsten

    International Nuclear Information System (INIS)

    Di Paola, A.; Di Quarto, F.; Sunseri, C.

    1980-01-01

    Scanning electron microscopy was used to investigate the morphology of anodic oxide films on tungsten, obtained in various conditions of anodization. Studies were made of the growth of porous films, whose thickness increases with time and depends upon the current density. Temperature and electrolyte composition influence the film morphology. Gravimetric measurements of film dissolution at 70 0 C show that after a transient time, the rate of metal dissolution and that of film formation coincide. The porous films thicken because tungsten dissolves as WO 2 2+ and precipitates as WO 3 .H 2 O. (author)

  16. Mechanical behaviour of a creased thin strip

    OpenAIRE

    Liu, Jie; Xu, Shanqing; Wen, Guilin; Xie, Yi Min

    2018-01-01

    In this study the mechanical behaviour of a creased thin strip under opposite-sense bending was investigated. It was found that a simple crease, which led to the increase of the second moment of area, could significantly alter the overall mechanical behaviour of a thin strip, for example the peak moment could be increased by 100 times. The crease was treated as a cylindrical segment of a small radius. Parametric studies demonstrated that the geometry of the strip could stron...

  17. Quantifiable Lateral Flow Assay Test Strips

    Science.gov (United States)

    2003-01-01

    As easy to read as a home pregnancy test, three Quantifiable Lateral Flow Assay (QLFA) strips used to test water for E. coli show different results. The brightly glowing control line on the far right of each strip indicates that all three tests ran successfully. But the glowing test line on the middle left and bottom strips reveal their samples were contaminated with E. coli bacteria at two different concentrations. The color intensity correlates with concentration of contamination.

  18. Anodic selective functionalization of cyclic amine derivatives

    OpenAIRE

    Onomura, Osamu

    2012-01-01

    Anodic reactions are desirable methods from the viewpoint of Green Chemistry, since no toxic oxidants are necessary for the oxidation of organic molecules. This review introduces usefulness of anodic oxidation and successive reaction for selective functionalization of cyclic amine derivatives.

  19. Ammonia stripping of biologically treated liquid manure.

    Science.gov (United States)

    Alitalo, Anni; Kyrö, Aleksis; Aura, Erkki

    2012-01-01

    A prerequisite for efficient ammonia removal in air stripping is that the pH of the liquid to be stripped is sufficiently high. Swine manure pH is usually around 7. At pH 7 (at 20°C), only 0.4% of ammonium is in ammonia form, and it is necessary to raise the pH of swine slurry to achieve efficient ammonia removal. Because manure has a very high buffering capacity, large amounts of chemicals are needed to change the slurry pH. The present study showed that efficient air stripping of manure can be achieved with a small amount of chemicals and without strong bases like NaOH. Slurry was subjected to aerobic biological treatment to raise pH before stripping. This facilitated 8 to 32% ammonia removal without chemical treatment. The slurry was further subjected to repeated cycles of stripping with MgO and Ca(OH)(2) additions after the first and second strippings, respectively, to raise slurry pH in between the stripping cycles. After three consecutive stripping cycles, 59 to 86% of the original ammonium had been removed. It was shown that the reduction in buffer capacity of the slurry was due to ammonia and carbonate removal during the stripping cycles. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  20. Optimizing the Stripping Procedure for LHCb

    CERN Document Server

    Richardson, Rachel

    2017-01-01

    The LHCb experiment faces a major challenge from the large amounts of data received while the LHC is running. The ability to sort this information in a useful manner is important for working groups to perform physics analyses. Both hardware and software triggers are used to decrease the data rate and then the stripping process is used to sort the data into streams and further into stripping lines. This project studies the hundreds of stripping lines to look for overlaps between them in order to make the stripping process more efficient.

  1. Potential profile in a conducting polymer strip

    DEFF Research Database (Denmark)

    Bay, Lasse; West, Keld; Vlachopoulos, Nikolaos

    2002-01-01

    Many conjugated polymers show an appreciable difference in volume between their oxidized and reduced forms. This property can be utilized in soft electrochemically driven actuators, "artificial muscles". Several geometries have been proposed for the conversion of the volume expansion into useful...... mechanical work. In a particularly simple geometry, the length change of polymer strips is exploited. The polymer strips are connected to the driving circuit at the end of the strip that is attached to the support of the device. The other end of the strip is connected to the load. The advantage of this set...

  2. Anode Fall Formation in a Hall Thruster

    International Nuclear Information System (INIS)

    Dorf, Leonid A.; Raitses, Yevgeny F.; Smirnov, Artem N.; Fisch, Nathaniel J.

    2004-01-01

    As was reported in our previous work, accurate, nondisturbing near-anode measurements of the plasma density, electron temperature, and plasma potential performed with biased and emissive probes allowed the first experimental identification of both electron-repelling (negative anode fall) and electron-attracting (positive anode fall) anode sheaths in Hall thrusters. An interesting new phenomenon revealed by the probe measurements is that the anode fall changes from positive to negative upon removal of the dielectric coating, which appears on the anode surface during the course of Hall thruster operation. As reported in the present work, energy dispersion spectroscopy analysis of the chemical composition of the anode dielectric coating indicates that the coating layer consists essentially of an oxide of the anode material (stainless steel). However, it is still unclear how oxygen gets into the thruster channel. Most importantly, possible mechanisms of anode fall formation in a Hall thruster with a clean and a coated anodes are analyzed in this work; practical implication of understanding the general structure of the electron-attracting anode sheath in the case of a coated anode is also discussed

  3. The 'KATOD-1' strip readout ASIC for cathode strip chamber

    International Nuclear Information System (INIS)

    Golutvin, I.A.; Gorbunov, N.V.; Karzhavin, V.Yu.; Khabarov, V.S.; Movchan, S.A.; Smolin, D.A.; Dvornikov, O.V.; Shumejko, N.M.; Chekhovskij, V.A.

    2001-01-01

    The 'KATOD-1', a 16-channels readout ASIC, has been designed to perform tests of P3 and P4 full-scale prototypes of the cathode strip chamber for the ME1/1 forward muon station of the Compact Muon Solenoid (CMS) experiment. The ASIC channel consists of two charge-sensitive preamplifiers, a three-stage shaper with cancellation, and an output driver. The ASIC is instrumented with control of gain, in the range of (-4.2 : +5.0) mV/fC, and control of output pulse-shape. The equivalent input noise is equal to 2400 e with the slope of 12 e/pF for detector capacity up to 200 pF. The peaking time is 100 ns for the chamber signal. The ASIC has been produced by a microwave Bi-jFET technology

  4. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  5. Mechanistic modeling of cyclic voltammetry: A helpful tool for understanding biosensor principles and supporting design optimization

    DEFF Research Database (Denmark)

    Semenova, Daria; Zubov, Alexandr; Silina, Yuliya E.

    2018-01-01

    development and to perform cyclic voltammetry (CV) measurements. As initial step in the model development we proposed the interpretation of experimental voltammograms obtained in the absence of substrate (glucose). The model equations describe dynamic diffusion and reaction of the involved species (oxygen...... optimization were independently supported by results of cyclic voltammetry and multi-analytical studies, such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Remarkably, a linear...

  6. New strips of convergence for Dirichlet series

    OpenAIRE

    Defant, Andreas

    2010-01-01

    In this article we study the interplay of the theory of classical Dirichlet series in one complex variable with recent development on monomial expansions of holomorphic functions in infinitely many variables. For a given Dirichlet series we obtain new strips of convergence in the complex plane related to Bohr’s classical strips of uniform but non absolute convergence.

  7. Hardness of approximation for strip packing

    DEFF Research Database (Denmark)

    Adamaszek, Anna Maria; Kociumaka, Tomasz; Pilipczuk, Marcin

    2017-01-01

    Strip packing is a classical packing problem, where the goal is to pack a set of rectangular objects into a strip of a given width, while minimizing the total height of the packing. The problem has multiple applications, for example, in scheduling and stock-cutting, and has been studied extensive...

  8. Mechanical behaviour of a creased thin strip

    Directory of Open Access Journals (Sweden)

    J. Liu

    2018-02-01

    Full Text Available In this study the mechanical behaviour of a creased thin strip under opposite-sense bending was investigated. It was found that a simple crease, which led to the increase of the second moment of area, could significantly alter the overall mechanical behaviour of a thin strip, for example the peak moment could be increased by 100 times. The crease was treated as a cylindrical segment of a small radius. Parametric studies demonstrated that the geometry of the strip could strongly influence its flexural behaviour. We showed that the uniform thickness and the radius of the creased segment had the greatest and the least influence on the mechanical behaviour, respectively. We further revealed that material properties could dramatically affect the overall mechanical behaviour of the creased strip by gradually changing the material from being linear elastic to elastic-perfect plastic. After the formation of the fold, the moment of the two ends of the strip differed considerably when the elasto-plastic materials were used, especially for materials with smaller tangent modulus in the plastic range. The deformation patterns of the thin strips from the finite element simulations were verified by physical models made of thin metal strips. The findings from this study provide useful information for designing origami structures for engineering applications using creased thin strips.

  9. CMS Silicon Strip Tracker Performance

    CERN Document Server

    Agram, Jean-Laurent

    2012-01-01

    The CMS Silicon Strip Tracker (SST), consisting of 9.6 million readout channels from 15148 modules and covering an area of 198 square meters, needs to be precisely calibrated in order to correctly reconstruct the events recorded. Calibration constants are derived from different workflows, from promptly reconstructed events with particles as well as from commissioning events gathered just before the acquisition of physics runs. The performance of the SST has been carefully studied since the beginning of data taking: the noise of the detector, data integrity, signal-over-noise ratio, hit reconstruction efficiency and resolution have been all investigated with time and for different conditions. In this paper we describe the reconstruction strategies, the calibration procedures and the detector performance results from the latest CMS operation.

  10. Ultrasonic examination of JBK-75 strip material

    International Nuclear Information System (INIS)

    Cook, K.V.; Cunningham, R.A. Jr.; Lewis, J.C.; McClung, R.W.

    1982-12-01

    An ultrasonic inspection system was assembled to inspect the JBK-75 stainless steel sheath material (for the Large Coil Project) for the Westinghouse-Airco superconducting magnet program. The mechanical system provided for handling the 180-kg (400-lb) coils of strip material [1.6 mm thick by 78 mm wide by 90 to 120 m long (0.064 by 3.07 in. by 300 to 400 ft)], feeding the strip through the ultrasonic inspection and cleaning stations, and respooling the coils. We inspected 54 coils of strip for both longitudinal and laminar flaws. Simulated flaws were used to calibrate both inspections. Saw-cut notches [0.28 mm deep (0.011 in., about 17% of the strip thickness)] were used to calibrate the longitudinal flaw inspections; 1.59-mm-diam (0.063-in.) flat-bottom holes drilled halfway through a calibration strip were used to calibrate the laminar flaw tests

  11. Fabrication of advanced design (grooved) cermet anodes

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr. [Pacific Northwest Lab., Richland, WA (United States); Huettig, F.R. [Ceramic Magnetics, Inc., Fairfield, NJ (United States)

    1993-05-01

    Attempts were made to fabricate full-size anodes with advanced, or grooved, design using isostatic pressing, slip casting injection molding. Of the three approaches, isostatic pressing produced an anode with dimensions nearest to the target specifications, without serious macroscopic flaws. This approach is considered the most promising for making advanced anodes for aluminum smelting. However, significant work still remains to optimize the physical properties and microstructure of the anode, both of which were significantly different from that of previous anodes. Injection molding and slip casting yielded anode materials with serious deficiencies, including cracks and holes. Injection molding gave cermet material with the best intrinsic microstructure, i.e., the microstructure of the material between macroscopic flaws was very similar to that of anodes previously made at PNL. Reason for the similarity may have to do with amount of residual binder in the material prior to sintering.

  12. Magnesium sacrificial anode behavior at elevated temperature

    International Nuclear Information System (INIS)

    Othman, Mohsen Othman

    2006-01-01

    Magnesium sacrificial anode coupled to mild steel was tasted in sodium chloride and tap water environments at elevated temperatures. The anode failed to protect the mild steel specimens in tap water environment at all temperatures specified. This was partly due to low conductivity of this medium. The temperature factor did not help to activate the anode in this medium. In sodium chloride environment the anode demonstrated good protection for steel cathodes. The weight loss was high for magnesium in sodium chloride environment particularly beyond 60 degree centigrade. In tap water environment the weight loss was negligible for the anode. It also suffered localized shallow pitting corrosion. Magnesium anode cannot be utilized where high temperature is involved particularly in high conductivity mediums. Protection of structures containing high resistivity waters is not feasible using sacrificial anode system. (author)

  13. Diffusion-free mediator based miniature biofuel cell anode fabricated on a carbon-MEMS electrode.

    Science.gov (United States)

    Bisht, Gobind S; Holmberg, Sunny; Kulinsky, Lawrence; Madou, Marc

    2012-10-02

    We report on the functionalization of a micropatterned carbon electrode fabricated using the carbon-MEMS process for its use as a miniature diffusion-free glucose oxidase anode. Carbon-MEMS based electrodes offer precise manufacturing control on both the micro- and nanoscale and possess higher electron conductivity than redox hydrogels. However, the process involves pyrolysis in a reducing environment that renders the electrode surface less reactive and introduction of a high density of functional groups becomes challenging. Our functionalization strategy involves the electrochemical oxidation of amine linkers onto the electrode. This strategy works well with both aliphatic and aryl linkers and uses stable compounds. The anode is designed to operate through mediated electron transfer between 2,5-dihydroxybenzaldehyde (DHB) based redox mediator and glucose oxidase enzyme. The electrode was first functionalized with ethylene diamine (EDA) to serve as a linker for the redox mediator. The redox mediator was then grafted through reductive amination, and attachment was confirmed through cyclic voltammetry. The enzyme immobilization was carried out through either adsorption or attachment, and their efficiency was compared. For enzyme attachment, the DHB attached electrode was functionalized again through electro-oxidation of aminobenzoic acid (ABA) linker. The ABA functionalization resulted in reduction of the DHB redox current, perhaps due to increased steric hindrance on the electrode surface, but the mediator function was preserved. Enzyme attachment was then carried out through a coupling reaction between the free carboxyl group on the ABA linker and the amine side chains on the enzyme. The enzyme incubation for both adsorption and attachment was done either through a dry spotting method or wet spotting method. The dry spotting method calls for the evaporation of enzyme droplet to form a thin film before sealing the electrode environment, to increase the effective

  14. Cyclic Voltammetry Simulations with DigiSim Software: An Upper-Level Undergraduate Experiment

    Science.gov (United States)

    Messersmith, Stephania J.

    2014-01-01

    An upper-division undergraduate chemistry experiment is described which utilizes DigiSim software to simulate cyclic voltammetry (CV). Four mechanisms were studied: a reversible electron transfer with no subsequent or proceeding chemical reactions, a reversible electron transfer followed by a reversible chemical reaction, a reversible chemical…

  15. Ion transfer voltammetry of metformin and phenformin at a polarized ionic liquid-membrane

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Samec, Zdeněk; Samcová, E.

    2015-01-01

    Roč. 61, č. 3 (2015), s. 214-214 ISSN 0034-6691. [Annual Meeting of the Polarographic Society of Japan /61./. 24.11.2015-25.11.2015, Himeji] R&D Projects: GA ČR(CZ) GA15-03139S Institutional support: RVO:61388955 Keywords : electrochemistry * voltammetry Subject RIV: CG - Electrochemistry

  16. Extreme Basicity of Biguanide Drugs in Aqueous Solutions: Ion Transfer Voltammetry and DFT Calculations

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Pižl, Martin; Samec, Zdeněk; Záliš, Stanislav

    2016-01-01

    Roč. 120, č. 37 (2016), s. 7344-7350 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GA15-03139S Institutional support: RVO:61388955 Keywords : voltammetry * Alkalinity * Complexation Subject RIV: CG - Electrochemistry Impact factor: 2.847, year: 2016

  17. Evidence of metallic plating on archaeological artefacts by voltammetry of microparticles

    Czech Academy of Sciences Publication Activity Database

    Ottenwelter, Estelle; Costa, V.

    2015-01-01

    Roč. 57, č. 3 (2015), s. 497-504 ISSN 0003-813X Institutional support: RVO:67985912 Keywords : metallic plating * voltammetry of microparticles * non-invasive analysis * medieval period * archaeological artefacts Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 1.364, year: 2015

  18. Polymyxin-coated Au and carbon nanotube electrodes for stable [NiFe]-hydrogenase film voltammetry.

    NARCIS (Netherlands)

    Hoeben, F.J.M.; Heller, I.; Albracht, S.P.J.; Dekker, C.; Lemay, S.G.; Heering, H.A.

    2008-01-01

    We report on the use of polymyxin (PM), a cyclic cationic lipodecapeptide, as an electrode modifier for studying protein film voltammetry (PFV) on Au and single-walled carbon nanotube (SWNT) electrodes. Pretreating the electrodes with PM allows for the subsequent immobilization of an active

  19. The anodization synthesis of copper oxide nanosheet arrays and their photoelectrochemical properties

    Science.gov (United States)

    Shu, Xia; Zheng, Hongmei; Xu, Guangqing; Zhao, Jiebo; Cui, Lihua; Cui, Jiewu; Qin, Yongqiang; Wang, Yan; Zhang, Yong; Wu, Yucheng

    2017-08-01

    We studied the growth of copper oxide nanosheet arrays on copper foil via a simple anodization method. The structures, morphologies, and elemental compositions of the specimens were characterized with an X-ray diffractometer, scanning electron microscope, high resolution transmission electron microscope, and X-ray photoelectron spectrometer. The copper oxide (Cu2O and CuO) nanosheet arrays were comprised of 30-nm-thick nanosheets that stand vertically on the Cu substrate. The anodizing parameters, such as the current density, temperature, and polyethylene glycol concentration, were optimized to obtain the regular nanosheet arrays. The optical absorption properties of the anodized products were evaluated using a diffuse reflectance spectrometer, and broad and strong optical absorption bands arising from the UV to visible region were observed. The photoelectrochemical performance of the nanosheet arrays was measured with chronoamperometry and cyclic voltammetry on an electrochemical workstation equipped with a Xe lamp (wavelength >400 nm). A negative photocurrent was obtained due to the p-type semiconductor of the copper oxides. The copper oxide nanosheet arrays achieve the highest photocurrent of 0.4 mA/cm2 at the current density of 1.0 A/dm2, temperature of 70 °C, and polyethylene glycol concentration of 0.5 g/L.

  20. Prototype Strip Barrel Modules for the ATLAS ITk Strip Detector

    CERN Document Server

    Sawyer, Craig; The ATLAS collaboration

    2017-01-01

    The module design for the Phase II Upgrade of the new ATLAS Inner Tracker (ITk) detector at the LHC employs integrated low mass assembly using single-sided flexible circuits with readout ASICs and a powering circuit incorporating control and monitoring of HV, LV and temperature on the module. Both readout and powering circuits are glued directly onto the silicon sensor surface resulting in a fully integrated, extremely low radiation length module which simultaneously reduces the material requirements of the local support structure by allowing a reduced width stave structure to be employed. Such a module concept has now been fully demonstrated using so-called ABC130 and HCC130 ASICs fabricated in 130nm CMOS technology to readout ATLAS12 n+-in-p silicon strip sensors. Low voltage powering for these demonstrator modules has been realised by utilising a DCDC powerboard based around the CERN FEAST ASIC. This powerboard incorporates an HV multiplexing switch based on a Panasonic GaN transistor. Control and monitori...

  1. Electrochemical activity of Geobacter sulfurreducens biofilms on stainless steel anodes

    International Nuclear Information System (INIS)

    Dumas, Claire; Basseguy, Regine; Bergel, Alain

    2008-01-01

    Stainless steel was studied as anode for the biocatalysis of acetate oxidation by biofilms of Geobacter sulfurreducens. Electrodes were individually polarized at different potential in the range -0.20 V to +0.20 V vs. Ag/AgCl either in the same reactor or in different reactors containing acetate as electron donor and no electron acceptor except the working electrode. At +0.20 V vs. Ag/AgCl, the current increased after a 2-day lag period up to maximum current densities around 0.7 A m -2 and 2.4 A m -2 with 5 mM and 10 mM acetate, respectively. No current was obtained during chronoamperometry (CA) at potential values lower than 0.00 V vs. Ag/AgCl, while the cyclic voltammetries (CV) that were performed periodically always detected a fast electron transfer, with the oxidation starting around -0.25 V vs. Ag/AgCl. Epifluorescent microscopy showed that the current recorded by chronoamperometry was linked to the biofilm growth on the electrode surface, while CVs were more likely linked to the cells initially adsorbed from the inoculum. A model was proposed to explain the electrochemical behaviour of the biofilm, which appeared to be controlled by the pioneering adherent cells playing the role of 'electrochemical gate' between the biofilm and the electrode surface

  2. Aeroelastic deformation of a perforated strip

    Science.gov (United States)

    Guttag, M.; Karimi, H. H.; Falcón, C.; Reis, P. M.

    2018-01-01

    We perform a combined experimental and numerical investigation into the static deformation of perforated elastic strips under uniform aerodynamic loading at high-Reynolds-number conditions. The static shape of the porous strips, clamped either horizontally or vertically, is quantified as they are deformed by wind loading, induced by a horizontal flow. The experimental profiles are compared to numerical simulations using a reduced model that takes into account the normal drag force on the deformed surface. For both configurations (vertical and horizontal clamping), we compute the drag coefficient of the strip, by fitting the experimental data to the model, and find that it decreases as a function of porosity. Surprisingly, we find that, for every value of porosity, the drag coefficients for the horizontal configuration are larger than those of the vertical configuration. For all data in both configurations, with the exception of the continuous strip clamped vertically, a linear relation is found between the porosity and drag. Making use of this linearity, we can rescale the drag coefficient in a way that it becomes constant as a function of the Cauchy number, which relates the force due to fluid loading on the elastic strip to its bending rigidity, independently of the material properties and porosity of the strip and the flow speed. Our findings on flexible strips are contrasted to previous work on rigid perforated plates. These results highlight some open questions regarding the usage of reduced models to describe the deformation of flexible structures subjected to aerodynamic loading.

  3. Reactions on carbon anodes in aluminium electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Eidet, Trygve

    1997-12-31

    The consumption of carbon anodes and energy in aluminium electrolysis is higher than what is required theoretically. This thesis studies the most important of the reactions that consume anode materials. These reactions are the electrochemical anode reaction and the airburn and carboxy reactions. The first part of the thesis deals with the kinetics and mechanism of the electrochemical anode reaction using electrochemical impedance spectroscopy. The second part deals with air and carboxy reactivity of carbon anodes and studies the effects of inorganic impurities on the reactivity of carbon anodes in the aluminium industry. Special attention is given to sulphur since its effect on the carbon gasification is not well understood. Sulphur is always present in anodes, and it is expected that the sulphur content of available anode cokes will increase in the future. It has also been suggested that sulphur poisons catalyzing impurities in the anodes. Other impurities that were investigated are iron, nickel and vanadium, which are common impurities in anodes which have been reported to catalyze carbon gasification. 88 refs., 92 figs., 24 tabs.

  4. The 2D-Micro Hole and Strip Plate in CF{sub 4} atmosphere aiming neutron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Natal da Luz, H; Gouvea, A L; Veloso, J F C A [Physics Department, University of Aveiro, Campus Universitario de Santiago, 3810 Aveiro (Portugal); Mir, J A [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxon, OX11 0QX (United Kingdom); Santos, J M F dos, E-mail: hugonluz@ua.p [Physics Department, University of Coimbra, Rua Larga, 3004 Coimbra (Portugal)

    2009-12-15

    The Micro Hole and Strip Plate (MHSP) achieves gains above 300 in tetrafluoromethane (CF{sub 4}) at 2.6 bar, making it suitable for neutron detection. Over the past few years, the imaging capabilities of the MHSP have been developed, leading to the 2D-MHSP. In this device, the position coordinates are determined using the principle of resistive charge division. The GEM-side was specially patterned in strips interconnected by a resistive strip for one of the coordinates and, in the MS-side, the anode strips were also interconnected by another resistive strip. By applying a trivial center of mass algorithm it is possible to obtain both coordinates and the energy of each detected event. The ability to register position and energy for each event can be very useful for event validation in neutron detection. In this work, the performance of the 2D-MHSP in CF{sub 4} is investigated. The Modular Transfer Function (MTF) is presented, showing that position resolutions of 700{mu}m in x and 1 mm in the y-direction are obtained with X-rays. It is also demonstrated that resolutions below the proton range (1 mm) are possible at 2.6 bar CF{sub 4}, demonstrating that the MHSP can be a cost effective choice for neutron imaging.

  5. A comparative study of enhanced electrochemical stability of tin–nickel alloy anode for high-performance lithium ion battery

    International Nuclear Information System (INIS)

    Guan, Dongsheng; Li, Jianyang; Gao, Xianfeng; Yuan, Chris

    2014-01-01

    Highlights: • Sn and Sn–Ni alloy nanoparticles are synthesized by chemical co-precipitation method. • Sn–Ni alloy particles show different phase structure and morphology from Sn particles. • Cyclic voltammetry reveals distinct redox reaction behaviors at Sn and alloy anodes. • Impedance analyses show better stability of alloy electrodes over prolonged cycling. - Abstract: Sn and Sn–Ni alloy nanoparticles are synthesized readily by co-precipitation method for their applications in Li-ion batteries. It is found that nickel not only affects the phase structure and morphology of the alloy, but also impacts Li–Sn alloying and dealloying behaviors. In Li-ion batteries, the alloy electrodes deliver stronger cycling stability than the pure Sn anode. In tests the former exhibits a final capacity of 228.5 mA h g −1 over 50 cycles, while the latter displays 14.3 mA h g −1 . Smaller current for battery cycles increases capacities of the alloys beyond 408.4 mA h g −1 . The mechanism of enhanced stability of Sn–Ni alloys is examined. Redox reaction characteristics and Li-ion transfer kinetics at these anodes after different cycles are investigated by cyclic voltammetry and electrochemical impedance spectroscopy, which are considered to associate with buffering effects of nickel and structural integrity of electrodes. Li–Sn alloying and dealloying reactions cause volume changes and induce stress that releases in the formation of tiny cracks within the particles. The cracks accelerate side reactions and decelerate charge transport, detrimental to the electrode stability. Nickel cushions the volume variations and reduces the stress and cracks at Sn–Ni alloy anodes to allow them to maintain better electrode integrity and smaller charge resistance, thus yielding their improved Li-ion intercalation stability during long-term cycling

  6. Avoiding short circuits from zinc metal dendrites in anode by backside-plating configuration

    Science.gov (United States)

    Higashi, Shougo; Lee, Seok Woo; Lee, Jang Soo; Takechi, Kensuke; Cui, Yi

    2016-01-01

    Portable power sources and grid-scale storage both require batteries combining high energy density and low cost. Zinc metal battery systems are attractive due to the low cost of zinc and its high charge-storage capacity. However, under repeated plating and stripping, zinc metal anodes undergo a well-known problem, zinc dendrite formation, causing internal shorting. Here we show a backside-plating configuration that enables long-term cycling of zinc metal batteries without shorting. We demonstrate 800 stable cycles of nickel–zinc batteries with good power rate (20 mA cm−2, 20 C rate for our anodes). Such a backside-plating method can be applied to not only zinc metal systems but also other metal-based electrodes suffering from internal short circuits. PMID:27263471

  7. Position sensitive anodes for MCP read-out using induced charge measurement

    CERN Document Server

    Jagutzki, O; Mergel, V; Schmidt-Böcking, H; Spillmann, U; Worth, L B C

    2002-01-01

    We investigate the method of an indirect detection of a MCP charge avalanche projected onto a resistive layer (G. Battistoni, et al., Nucl. Instr. and Meth., 202 (1982) 459). If the sheet resistance is favourable one can detect the charge cloud by the capacitive coupling to an anode structure a few millimetres behind the layer. The anode structure can be, for example, a wedge-and-strip electrode pattern (M. Unverzagt, Diplomarbeit, Universitaet Frankfurt 1992, private communication) as it is used for directly collecting the electron avalanche from a MCP. Detection of the induced charge is beneficial in several respects. Firstly, image distortions produced by secondary electron mediated charge redistribution are eliminated. Secondly, the noise component due to quantized charge collection, commonly referred to as partition noise, is not present. In addition, the dielectric substrate can function both as an element of the vacuum enclosure and HV insulator, making the electrical connections easily accessible and ...

  8. A video strip chart program

    International Nuclear Information System (INIS)

    Jones, N.L.

    1994-01-01

    A strip chart recorder has been utilized for trend analysis of the Oak Ridge National Laboratory EN tandem since 1987. At the EN, the author could not afford the nice eight channel thermal pen recorder that was used at the 25 URC. He had to suffice with two channel fiber tip or capillary pen type recorders retrieved from salvage and maintained with parts from other salvaged recorders. After cycling through several machines that eventually became completely unserviceable, a search for a new thermal recorder was begun. As much as he hates to write computer code, he decided to try his hand at getting an old data acquisition unit, that had been retrieved several years ago from salvage, to meet his needs. A BASIC language compiler was used because time was not available to learn a more advanced language. While attempting to increase acquisition and scroll speed on the 6 MHz 80286 that the code was first developed on, it became apparent that scrolling only the first small portion of the screen at high speed and then averaging that region and histogramming the average provided both the speed necessary for capturing fairly short duration events, and a trend record without use of back scrolling and disk storage routines. This turned out to be quite sufficient

  9. The Panda Strip Asic: Pasta

    Science.gov (United States)

    Lai, A.

    2018-01-01

    PASTA is the 64 channel front-end chip, designed in a 110 nm CMOS technology to read out the strip sensors of the Micro Vertex Detector (MVD) of the PANDA experiment. This chip provides high resolution timestamp and deposited charge information by means of the time-over-threshold technique. Its working principle is based on a predecessor, the TOFPET ASIC, that was designed for medical applications. A general restructuring of the architecture was needed, in order to meet the specific requirements imposed by the physics programme of PANDA, especially in terms of radiation tolerance, spatial constraints, and readout in absence of a first level hardware trigger. The first revision of PASTA is currently under evaluation at the Forschungszentrum Jülich, where a data acquisition system dedicated to the MVD prototypes has been developed. This paper describes the main aspect of the chip design, gives an overview of the data acquisition system used for the verification, and shows the first results regarding the performance of PASTA.

  10. Dynamic underground stripping demonstration project

    International Nuclear Information System (INIS)

    Newmark, R.L.

    1992-04-01

    LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation techniques for rapid cleanup of localized underground spills. Called dynamic stripping to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first eight months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques. Tests then began on the contaminated site in FY 1992. This report describes the work at the Clean Site, including design and performance criteria, test results, interpretations, and conclusions. We fielded 'a wide range of new designs and techniques, some successful and some not. In this document, we focus on results and performance, lessons learned, and design and operational changes recommended for work at the contaminated site. Each section focuses on a different aspect of the work and can be considered a self-contained contribution

  11. Prevention of Stripping under Chip Seals

    Science.gov (United States)

    2017-10-01

    Eighteen chip-sealed roadways in eight cities and counties in Minnesota were evaluated both in the field (for condition surveys and density tests) and in the laboratory (for permeability, stripping, tensile-strength ratio, asphalt film thickness, and...

  12. Buffer Strips for Riparian Zone Management

    National Research Council Canada - National Science Library

    1991-01-01

    This study provides a review of technical literature concerning the width of riparian buffer strips needed to protect water quality and maintain other important values provided by riparian ecosystem...

  13. Temperature Profile of the Duracell Test Strip.

    Science.gov (United States)

    Viiri, Jouni; Kettunen, Lasse

    1996-01-01

    Presents the temperature profile of the Duracell Test Strip obtained using a Inframetrics 740 thermal imaging radiometer and ThermaGRAM95 software and compares this to the theoretical profile derived by Clark and Bonicamp. (JRH)

  14. Deuteron stripping reactions using dirac phenomenology

    Science.gov (United States)

    Hawk, E. A.; McNeil, J. A.

    2001-04-01

    In this work deuteron stripping reactions are studied using the distorted wave born approximation employing dirac phenomenological potentials. In 1982 Shepard and Rost performed zero-range dirac phenomenological stripping calculations and found a dramatic reduction in the predicted cross sections when compared with similar nonrelativistic calculations. We extend the earlier work by including full finite range effects as well as the deuteron's internal D-state. Results will be compared with traditional nonrelativistic approaches and experimental data at low energy.

  15. The charge collection in silicon strip detectors

    International Nuclear Information System (INIS)

    Boehringer, T.; Hubbeling, L.; Weilhammer, P.; Kemmer, J.; Koetz, U.; Riebesell, M.; Belau, E.; Klanner, R.; Lutz, G.; Neugebauer, E.; Seebrunner, H.J.; Wylie, A.

    1983-02-01

    The charge collection in silicon detectors has been studied, by measuring the response to high-energy particles of a 20μm pitch strip detector as a function of applied voltage and magnetic field. The results are well described by a simple model. The model is used to predict the spatial resolution of silicon strip detectors and to propose a detector with optimized spatial resolution. (orig.)

  16. Properties isotropy of magnesium alloy strip workpieces

    OpenAIRE

    Р. Кавалла; В. Ю. Бажин

    2016-01-01

    The paper discusses the issue of obtaining high quality cast workpieces of magnesium alloys produced by strip roll-casting. Producing strips of magnesium alloys by combining the processes of casting and rolling when liquid melt is fed continuously to fast rolls is quite promising and economic. In the process of sheet stamping considerable losses of metal occur on festoons formed due to anisotropy of properties of foil workpiece, as defined by the macro- and microstructure and modes of rolling...

  17. 33 CFR 157.128 - Stripping system.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Stripping system. 157.128 Section... Crude Oil Washing (COW) System on Tank Vessels Design, Equipment, and Installation § 157.128 Stripping system. (a) Each tank vessel having a COW system under § 157.10(e), § 157.10a(a)(2), or § 157.10c(b)(2...

  18. Quantitative comparison of 3 enamel-stripping devices in vitro: how precisely can we strip teeth?

    Science.gov (United States)

    Johner, Alexander Marc; Pandis, Nikolaos; Dudic, Alexander; Kiliaridis, Stavros

    2013-04-01

    In this in-vitro study, we aimed to investigate the predictability of the expected amount of stripping using 3 common stripping devices on premolars. One hundred eighty extracted premolars were mounted and aligned in silicone. Tooth mobility was tested with Periotest (Medizintechnik Gulden, Modautal, Germany) (8.3 ± 2.8 units). The selected methods for interproximal enamel reduction were hand-pulled strips (Horico, Hapf Ringleb & Company, Berlin, Germany), oscillating segmental disks (O-drive-OD 30; KaVo Dental, Biberach, Germany), and motor-driven abrasive strips (Orthofile; SDC Switzerland, Lugano-Grancia, Switzerland). With each device, the operator intended to strip 0.1, 0.2, 0.3, or 0.4 mm on the mesial side of 15 teeth. The teeth were scanned before and after stripping with a 3-dimensional laser scanner. Superposition and measurement of stripped enamel on the most mesial point of the tooth were conducted with Viewbox software (dHal Software, Kifissia, Greece). The Wilcoxon signed rank test and the Kruskal-Wallis test were applied; statistical significance was set at alpha ≤ 0.05. Large variations between the intended and the actual amounts of stripped enamel, and between stripping procedures, were observed. Significant differences were found at 0.1 mm of intended stripping (P ≤ 0.05) for the hand-pulled method and at 0.4 mm of intended stripping (P ≤ 0.001 to P = 0.05) for all methods. For all scenarios of enamel reduction, the actual amount of stripping was less than the predetermined and expected amount of stripping. The Kruskal-Wallis analysis showed no significant differences between the 3 methods. There were variations in the stripped amounts of enamel, and the stripping technique did not appear to be a significant predictor of the actual amount of enamel reduction. In most cases, actual stripping was less than the intended amount of enamel reduction. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights

  19. Cyclic Voltammetry and Impedance Spectroscopy Behavior Studies of Polyterthiophene Modified Electrode

    Directory of Open Access Journals (Sweden)

    Naima Maouche

    2011-01-01

    Full Text Available We present in this work a study of the electrochemical behaviour of terthiophene and its corresponding polymer, which is obtained electrochemically as a film by cyclic voltammetry (CV on platinum electrode. The analysis focuses essentially on the effect of two solvents acetonitrile and dichloromethane on the electrochemical behaviour of the obtained polymer. The electrochemical behavior of this material was investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS. The voltammograms show that the film of polyterthiophene can oxide and reduce in two solutions; in acetonitrile, the oxidation current intensity is more important than in dichloromethane. The impedance plots show the semicircle which is characteristic of charge-transfer resistance at the electrode/polymer interface at high frequency and the diffusion process at low frequency.

  20. Process and electrolyte for applying barrier layer anodic coatings

    International Nuclear Information System (INIS)

    Dosch, R.G.; Prevender, T.S.

    1975-01-01

    Various metals may be anodized, and preferably barrier anodized, by anodizing the metal in an electrolyte comprising quaternary ammonium compound having a complex metal anion in a solvent containing water and a polar, water soluble organic material. (U.S.)

  1. Electrodeposited gold nanoparticles on carbon nanotube-textile: Anode material for glucose alkaline fuel cells

    KAUST Repository

    Pasta, Mauro

    2012-06-01

    In the present paper we propose a new anode material for glucose-gluconate direct oxidation fuel cells prepared by electrodepositing gold nanoparticles onto a conductive textile made by conformally coating single walled carbon nanotubes (SWNT) on a polyester textile substrate. The electrodeposition conditions were optimized in order to achieve a uniform distribution of gold nanoparticles in the 3D porous structure of the textile. On the basis of previously reported studies, the reaction conditions (pH, electrolyte composition and glucose concentration) were tuned in order to achieve the highest oxidation rate, selectively oxidizing glucose to gluconate. The electrochemical characterization was carried out by means of cyclic voltammetry. © 2012 Elsevier B.V. All rights reserved.

  2. Utilization of Plant Refuses as Component of Heavy Metal Ion ...

    African Journals Online (AJOL)

    The ability of the fabricated sensors to detect the presence of heavy metals was analyzed using electrochemical methods like cyclic voltammetry and differential pulse anodic stripping voltammetry. Results showed that the fabricated electrode were able to detect the presence of mercury and lead ions in aqueous solutions ...

  3. Voltammetry of Aluminum Nanoparticles in Aqueous Media with Hanging Mercury Drop Electrode

    Czech Academy of Sciences Publication Activity Database

    Korshunov, A.; Heyrovský, Michael

    2010-01-01

    Roč. 22, 17-18 (2010), s. 1989-1993 ISSN 1040-0397. [International Conference on Modern Electroanalytical Methods. Prague, 09.12.2009-14.12.2009] R&D Projects: GA AV ČR IAA400400806 Institutional research plan: CEZ:AV0Z40400503 Keywords : linear cyclic voltammetry * Hanging mercury drop electrode * Aluminum nanoparticles dispersion Subject RIV: CG - Electrochemistry Impact factor: 2.721, year: 2010

  4. Determination of azidothymidine - an antiproliferative and virostatic drug by square-wave voltammetry

    Czech Academy of Sciences Publication Activity Database

    Vacek, Jan; Andrysík, Zdeněk; Trnková, L.; Kizek, René

    2004-01-01

    Roč. 16, č. 3 (2004), s. 224-230 ISSN 1040-0397 R&D Projects: GA ČR GA203/02/0422; GA AV ČR IAA1163201; GA AV ČR IBS5004009 Institutional research plan: CEZ:AV0Z5004920 Keywords : azidothymidine (AZT) * square-wave voltammetry * hanging mercury drop electrode (HMDE) Subject RIV: BO - Biophysics Impact factor: 2.038, year: 2004

  5. The Redox Chemistry of Ruthenium Dioxide: A Cyclic Voltammetry Study—Review and Revision

    Directory of Open Access Journals (Sweden)

    Sebastian Chalupczok

    2018-01-01

    Full Text Available By cyclic voltammetry at high scan rates, the electrochemical properties of RuO2 in acidic and alkaline solutions were investigated in detail. Thirteen current peaks can be distinguished in sulfuric acid and sodium hydroxide. With respect to the pH sensitivity of RuO2 electrodes, we considered charge calculations, peak currents, and apparent diffusion coefficients. The nature of the Ru(II oxidation was clarified by Ru(I−Ru(III species.

  6. Correlation of the first reduction potential of selected radiosensitizers determined by cyclic voltammetry with theoretical calculations

    Czech Academy of Sciences Publication Activity Database

    Gál, Miroslav; Kolivoška, Viliam; Ambrová, M.; Híveš, J.; Sokolová, Romana

    2011-01-01

    Roč. 76, č. 8 (2011), s. 937-946 ISSN 0010-0765 R&D Projects: GA ČR GP203/09/P502; GA ČR GA203/09/0705; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : cyclic voltammetry * radical ions * radiochemistry Subject RIV: CG - Electrochemistry Impact factor: 1.283, year: 2011

  7. Hairy carbon electrodes studied by cyclic voltammetry and battery discharge testing

    Science.gov (United States)

    Chung, Deborah D. L.; Shui, Xiaoping; Frysz, Christine A.

    1993-01-01

    Hairy carbon is a new material developed by growing submicron carbon filaments on conventional carbon substrates. Typical substrate materials include carbon black, graphite powder, carbon fibers, and glassy carbon. A catalyst is used to initiate hair growth with carbonaceous gases serving as the carbon source. To study the electrochemical behavior of hairy carbons, cyclic voltammetry (CV) and discharge testing were conducted. In both cases, hairy carbon results surpassed those of the substrate material alone.

  8. Novel acyclonucleoside analog bearing a 1,2,4-triazole–Schiff base: Synthesis, characterization and analytical studies using square wave-adsorptive stripping voltammetry and HPLC

    OpenAIRE

    Ali F. Alghamdi; Nadjet Rezki

    2017-01-01

    New acyclonucleoside analogs tethered by a 1,2,4-triazole scaffold were synthesized through the condensation of 4-amino-5-(2-phenyleth-1-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (2) with benzaldehyde followed by the alkylation of the resulting Schiff base (3)with 2-bromoethanol, 3-chloropropanol and/or 3-chloropropan-1,2-diol. Voltammetric studies were carried out for the analysis of 1 × 10−6 mol L−1 of the newly synthesized acyclonucleoside analogs (4–6) using square wave-adsorptive stripp...

  9. Application of avidin-biotin technology and adsorptive transfer stripping square-wave voltammetry for detection of DNA hybridization and avidin in transgenic avidin maize

    Czech Academy of Sciences Publication Activity Database

    Masařík, Michal; Kizek, René; Kramer, K. J.; Billová, Sabina; Brázdová, Marie; Jelen, František; Howard, J. A.

    2003-01-01

    Roč. 75, č. 11 (2003), s. 2663-2669 ISSN 0003-2700 R&D Projects: GA ČR GA203/02/0422; GA AV ČR IAA1163201; GA AV ČR IBS5004107 Institutional research plan: CEZ:AV0Z5004920 Keywords : carbon electrodes * mercury electrodes * streptavidin Subject RIV: BO - Biophysics Impact factor: 5.250, year: 2003

  10. Multi-anode wire straw tube tracker

    International Nuclear Information System (INIS)

    Oh, S.H.; Ebenstein, W.L.; Wang, C.W.

    2011-01-01

    We report on a test of a straw tube detector design having several anode (sense) wires inside a straw tube. The anode wires form a circle inside the tube and are read out independently. This design could solve several shortcomings of the traditional single wire straw tube design such as double hit capability and stereo configuration.

  11. Screened anode N/sub 2/ laser

    Energy Technology Data Exchange (ETDEWEB)

    Sabry, M.M.F.

    1985-01-01

    An experimental study of the effect of screening the discharge channel on the output energy is presented. It has been found that a screened anode nitrogen laser generates higher output energy than that of a screened cathode, and also higher than that when both cathode and anode are unshielded at higher pressures.

  12. Anodic Voltammetric determination of gemifloxacin using screen-printed carbon electrode

    Directory of Open Access Journals (Sweden)

    Abd-Elgawad Radi

    2013-04-01

    Full Text Available The electrochemical oxidation behavior and voltammetric assay of gemifloxacin were investigated using differential-pulse and cyclic voltammetry on a screen-printed carbon electrode. The effects of pH, scan rates, and concentration of the drug on the anodic peak current were studied. Voltammograms of gemifloxacin in Tris–HCl buffer (pH 7.0 exhibited a well-defined single oxidation peak. A differential-pulse voltammetric procedure for the quantitation of gemifloxacin has been developed and suitably validated with respect to linearity, limits of detection and quantification, accuracy, precision, specificity, and robustness. The calibration was linear from 0.5 to 10.0 μM, and the limits of detection and quantification were 0.15 and 5.0 μM. Recoveries ranging from 96.26% to 103.64% were obtained. The method was successfully applied to the determination of gemifloxacin in pharmaceutical tablets without any pre-treatment. Excipients present in the tablets did not interfere in the assay. Keywords: Screen-printed carbon electrode, Voltammetry, Gemifloxacin, Pharmaceutical analysis

  13. Ultrasound-assisted anodization of aluminum in oxalic acid

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Rong; Jiang Kaiming [Department of Physics, Shanghai Maritime University, 1550 Pudong Avenue, Shanghai 200135 (China); Zhu Yun [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China); Qi Haiyang [Department of Physics, Shanghai Maritime University, 1550 Pudong Avenue, Shanghai 200135 (China); Ding Guqiao, E-mail: gqding@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China)

    2011-10-15

    Porous anodic alumina is an important nanoscale template for fabrication of various nanostructures. We report a new ultrasound-assisted anodization process in oxalic acid. Under the continuous irradiation of ultrasound, the one-step-anodized sample has a smooth and clean surface, and two-step-anodization brings ordered porous anodic alumina with higher growth rate of 52 {mu}m/h. The ultrasound applied during the anodization can clean the surface and enhance the nanopore growth since it can accelerate the oxide dissolving on the electrolyte/oxide interface. The ultrasound-assisted anodization may be utilized for other anodizations.

  14. The influence of silicate and sulphate anions on the anodic corrosion and the transpassivity of iron and silicon-rich steel in concentrated KOH solution

    International Nuclear Information System (INIS)

    Čekerevac, Milan; Simičić, Miloš; Bujanović, Ljiljana Nikolić; Popović, Negica

    2012-01-01

    Highlights: ► Anodic behaviour of Fe and steel in 10 M KOH with sulphate and silicate is examined. ► X-ray diffraction confirmed the formation of Fe 3 (Si 1.32 Fe 0.68 )O 5 (OH) 4 in anodic layer. ► X-ray diffraction confirmed the formation of Ba(Fe, S)O 4 at anodic oxidation. - Abstract: The effect of sulphate and silicate addition in a 10 M KOH electrolyte on the anodic corrosion and transpassivity of iron and steel rich in silicon are explored by cyclic and linear sweep voltammetry. Formation of ferrate(VI) in the iron transpassivity region is noticed in all explored electrolytes. The electrochemical sulphato- and silico-ferrate(VI) formation is discussed as a possible result of Fe 3 III (Si 1.32 Fe 0.68 )O 5 (OH) 4 and [Fe(II) 4 Fe(III) 2 (OH) 12 ]SO 4 oxidation in the 10 M KOH electrolytes with silicate and sulphate, respectively. The presence of Fe 3 (Si 1.32 Fe 0.68 )O 5 (OH) 4 in the anodic layer of silicon steel and the crystal structure of electrochemically synthesised Ba(Fe, S)O 4 have been revealed by XRD.

  15. An integrated electrochemical device based on immunochromatographic test strip and enzyme labels for sensitive detection of disease-related biomarkers

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Zhexiang; Wang, Jun; Wang, Hua; Li, Yao Q.; Lin, Yuehe

    2012-05-30

    A novel electrochemical biosensing device that integrates an immunochromatographic test strip and a screen-printed electrode (SPE) connected to a portable electrochemical analyzer was presented for rapid, sensitive, and quantitative detection of disease-related biomarker in human blood samples. The principle of the sensor is based on sandwich immunoreactions between a biomarker and a pair of its antibodies on the test strip, followed by highly sensitive square-wave voltammetry (SWV) detection. Horseradish peroxidase (HRP) was used as a signal reporter for electrochemical readout. Hepatitis B surface antigen (HBsAg) was employed as a model protein biomarker to demonstrate the analytical performance of the sensor in this study. Some critical parameters governing the performance of the sensor were investigated in detail. The sensor was further utilized to detect HBsAg in human plasma with an average recovery of 91.3%. In comparison, a colorimetric immunochromatographic test strip assay (ITSA) was also conducted. The result shows that the SWV detection in the electrochemical sensor is much more sensitive for the quantitative determination of HBsAg than the colorimetric detection, indicating that such a sensor is a promising platform for rapid and sensitive point-of-care testing/screening of disease-related biomarkers in a large population

  16. Electrochemical stripping determination of traces of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide

    International Nuclear Information System (INIS)

    Stulik, K.; Beran, P.; Dolezal, J.; Opekar, F.

    1978-01-01

    Procedures have been developed for the determination of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide, at concentrations of 1ppm or less. Zirconium metal was dissolved in sulphuric acid, and zirconium dioxide decomposed under pressure with hydrofluoric acid. Sample solutions were prepared in dilute sulphuric acid. For the stripping determination, the sample solution was either mixed with a complexing tartrate base electrolyte or the pre-electrolysis was carried out in acid solution, with the acid solution being exchanged for a pure base electrolyte (e.g. an acetate buffer) for the stripping step. The stripping step was monitored by d.c., differential pulse and Kalousek commutator voltammetry and the three methods were compared. A stationary mercury-drop electrode can generally be used for all the methods, whereas a mercury-film electrode is suitable only for the d.c. voltammetric determination of copper, lead and cadmium, as pulse measurements with films are poorly reproducible and the electrodes are easily damaged. The relative standard deviation does not exceed 20%. Some samples contained relatively large amounts of copper, which is best separated by electrodeposition on a platinum electrode. (author)

  17. Properties isotropy of magnesium alloy strip workpieces

    Directory of Open Access Journals (Sweden)

    Р. Кавалла

    2016-12-01

    Full Text Available The paper discusses the issue of obtaining high quality cast workpieces of magnesium alloys produced by strip roll-casting. Producing strips of magnesium alloys by combining the processes of casting and rolling when liquid melt is fed continuously to fast rolls is quite promising and economic. In the process of sheet stamping considerable losses of metal occur on festoons formed due to anisotropy of properties of foil workpiece, as defined by the macro- and microstructure and modes of rolling and annealing. The principal causes of anisotropic mechanical properties of metal strips produced by the combined casting and rolling technique are the character of distribution of intermetallic compounds in the strip, orientation of phases of metal defects and the residual tensions. One of the tasks in increasing the output of fit products during stamping operations consists in minimizing the amount of defects. To lower the level of anisotropy in mechanical properties various ways of treating the melt during casting are suggested. Designing the technology of producing strips of magnesium alloys opens a possibility of using them in automobile industry to manufacture light-weight body elements instead of those made of steel.

  18. Superconducting nano-strip particle detectors

    International Nuclear Information System (INIS)

    Cristiano, R; Ejrnaes, M; Casaburi, A; Zen, N; Ohkubo, M

    2015-01-01

    We review progress in the development and applications of superconducting nano-strip particle detectors. Particle detectors based on superconducting nano-strips stem from the parent devices developed for single photon detection (SSPD) and share with them ultra-fast response times (sub-nanosecond) and the ability to operate at a relatively high temperature (2–5 K) compared with other cryogenic detectors. SSPDs have been used in the detection of electrons, neutral and charged ions, and biological macromolecules; nevertheless, the development of superconducting nano-strip particle detectors has mainly been driven by their use in time-of-flight mass spectrometers (TOF-MSs) where the goal of 100% efficiency at large mass values can be achieved. Special emphasis will be given to this case, reporting on the great progress which has been achieved and which permits us to overcome the limitations of existing mass spectrometers represented by low detection efficiency at large masses and charge/mass ambiguity. Furthermore, such progress could represent a breakthrough in the field. In this review article we will introduce the device concept and detection principle, stressing the peculiarities of the nano-strip particle detector as well as its similarities with photon detectors. The development of parallel strip configuration is introduced and extensively discussed, since it has contributed to the significant progress of TOF-MS applications. (paper)

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

    International Nuclear Information System (INIS)

    Aage, H.K.; Korsbech, U.

    2006-04-01

    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)

  20. 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)

  1. Discharge modes at the anode of a vacuum arc

    International Nuclear Information System (INIS)

    Miller, H.C.

    1982-01-01

    The two most common anode modes in a vacuum arc are the low current mode, where the anode is basically inert; and the high current mode with a fully developed anode spot. This anode spot is very bright, has a temperature near the boiling point of the anode material, and is a copious source of vapor and energetic ions. However, other anode modes can exist. A low current vacuum arc with electrodes of readily sputterable material will emit a flux of sputtered atoms from the anode. An intermediate currents an anode footpoint can form. This footpoint is luminous, but much cooler than a true anode spot. Finally, a high current mode can exist where several small anode spots are present instead of a single large anode spot

  2. Microelectrode voltammetry of multi-electron transfers complicated by coupled chemical equilibria: a general theory for the extended square scheme.

    Science.gov (United States)

    Laborda, Eduardo; Gómez-Gil, José María; Molina, Angela

    2017-06-28

    A very general and simple theoretical solution is presented for the current-potential-time response of reversible multi-electron transfer processes complicated by homogeneous chemical equilibria (the so-called extended square scheme). The expressions presented here are applicable regardless of the number of electrons transferred and coupled chemical processes, and they are particularized for a wide variety of microelectrode geometries. The voltammetric response of very different systems presenting multi-electron transfers is considered for the most widely-used techniques (namely, cyclic voltammetry, square wave voltammetry, differential pulse voltammetry and steady state voltammetry), studying the influence of the microelectrode geometry and the number and thermodynamics of the (electro)chemical steps. Most appropriate techniques and procedures for the determination of the 'interaction' between successive transfers are discussed. Special attention is paid to those situations where homogeneous chemical processes, such as protonation, complexation or ion association, affect the electrochemical behaviour of the system by different stabilization of the oxidation states.

  3. Architecture engineering of hierarchically porous chitosan/vacuum-stripped graphene scaffold as bioanode for high performance microbial fuel cell.

    Science.gov (United States)

    He, Ziming; Liu, Jing; Qiao, Yan; Li, Chang Ming; Tan, Timothy Thatt Yang

    2012-09-12

    The bioanode is the defining feature of microbial fuel cell (MFC) technology and often limits its performance. In the current work, we report the engineering of a novel hierarchically porous architecture as an efficient bioanode, consisting of biocompatible chitosan and vacuum-stripped graphene (CHI/VSG). With the hierarchical pores and unique VSG, an optimized bioanode delivered a remarkable maximum power density of 1530 mW m(-2) in a mediator-less MFC, 78 times higher than a carbon cloth anode.

  4. Analysis of 'Coma strip' galaxy redshift catalog

    International Nuclear Information System (INIS)

    Klypin, A.A.; Karachentsev, I.D.; Lebedev, V.S.

    1990-01-01

    We present results of the analysis of a galaxy redshift catalog made at the 6-m telescope by Karachentsev and Kopylov (1990. Mon. Not. R. astr. Soc., 243, 390). The catalog covers a long narrow strip on the sky (10 arcmin by 63 0 ) and lists 283 galaxies up to limiting blue magnitude m B = 17.6. The strip goes through the core of Coma cluster and this is called the 'Coma strip' catalog. The catalog is almost two times deeper than the CfA redshift survey and creates the possibility of studying the galaxy distribution on scales of 100-250 Mpc. Due to the small number of galaxies in the catalog, we were able to estimate only very general and stable parameters of the distribution. (author)

  5. Perovskites synthesis to SOFC anodes

    International Nuclear Information System (INIS)

    Wendler, L.P.; Chinelatto, A.L.; Chinelatto, A.S.A.; Ramos, K.

    2012-01-01

    Perovskite structure materials containing lanthanum have been widely applied as solid oxide fuel cells (SOFCs) electrodes, due to its electrical properties. Was investigated the obtain of the perovskite structure LaCr 0,5 Ni 0,5 O 3 , by Pechini method, and its suitability as SOFC anode. The choice of this composition was based on the stability provided by chromium and the catalytic properties of nickel. After preparing the resins, the samples were calcined at 300 deg C, 600 deg C, 700 deg C and 850 deg C. The resulting powders were characterized by X-ray diffraction to determine the existing phases. Furthermore, were performed other analysis, like X-ray fluorescence, He pycnometry, specific surface area by BET isotherm and scanning electronic microscopy (author)

  6. Wokker. Notes on a Surrealist comic strip

    Directory of Open Access Journals (Sweden)

    Roger Sabin

    2012-05-01

    Full Text Available This essay explores the creation and development of a British comic strip, Wokker (1971-1999, and its connections with the surrealist movement. Although the strip is remarkable for its content and formalist properties, it remains obscure both because of its publishing circumstances, and because it does not fit easily into a history of comics. Rather it can be argued that its conceptual roots can be traced to the artistic ferment that happened in Paris in the 1920s (with Breton as a key reference point, and that it represents a very English, and late-flowering, example of the surrealist idea.

  7. 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.

  8. Spray Rolling Aluminum Strip for Transportation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kevin M. McHugh; Y. Lin; Y. Zhou; E. J. Lavernia; J.-P. Delplanque; S. B. Johnson

    2005-02-01

    Spray rolling is a novel strip casting technology in which molten aluminum alloy is atomized and deposited into the roll gap of mill rolls to produce aluminum strip. A combined experimental/modeling approach has been followed in developing this technology with active participation from industry. The feasibility of this technology has been demonstrated at the laboratory scale and it is currently being scaled-up. This paper provides an overview of the process and compares the microstructure and properties of spray-rolled 2124 aluminum alloy with commercial ingot-processed material

  9. Silicon strip detectors for the LHCb experiment

    OpenAIRE

    Steinkamp, O

    2005-01-01

    The LHCb experiment is a single-arm magnetic spectrometer. Silicon micro-strip detectors are employed in a significant fraction of the tracking system. The Vertex Locator consists of 21 detector stations that operate inside the LHC beam pipe and are separated from the beam vacuum by a thin aluminium foil. The Silicon Tracker is a large-surface silicon micro-strip detector that covers the full acceptance of the experiment in a single tracking station upstream of the spectrometer magnet and the...

  10. CMS Silicon Strip Tracker Operation and Performance

    CERN Document Server

    Boudoul, Gaelle

    2011-01-01

    The Silicon Strip Tracker (SST) of the CMS experiment is, with 9.6 million readout channels, the largest strip tracker ever built. In order to correctly interpret and reconstruct the events recorded it needs to be precisely calibrated, thus ensuring that it fully contributes to the physics research program of the CMS experiment. In 2009 and 2010, the performance of the SST has been carefully studied using cosmic muons and tracks from proton-proton collisions at centre-of-mass energies of 900 GeV, 2.36 TeV and 7 TeV. In this paper, we present some results of the detector performance.

  11. Test strip and method for its use

    International Nuclear Information System (INIS)

    1981-01-01

    A test strip device is described which is useful in performing binding assays involving antigens, antibodies, hormones, vitamins, metabolites or pharmacological agents. The device is capable of application to analytical methods in which a set of sequential test reactions is involved and in which a minute sample size may be used. This test strip is particularly useful in radioimmunoassays. The use of the device is illustrated in radioimmunoassays for 1) thyroxine in serum, 2) the triiodothyronine binding capacity of serum and 3) folic acid and its analogues in serum. (U.K.)

  12. Kinetics and mechanism of the anodic dissolution of gold in solutions of 1,5-diazabicyclo[3.1.0]hexane and its precursors

    Science.gov (United States)

    Simakova, A. P.; Vedenyapina, M. D.; Kuznetsov, V. V.; Makhova, N. N.; Vedenyapin, A. A.

    2014-02-01

    Studies of the electrochemical behavior of hexahydropyrimidine, 1,5-diazabicyclo[3.1.0]hexane, and 1,3-diaminopropane on a gold electrode via cyclic voltammetry allow us to conclude that gold anodes are subject to corrosion in presence these compounds, yielding complexes that migrate into the solutions and discharge on the counter electrode, producing gold metal deposit. 1,5-Diazabicyclo[3.1.0]hexane is found to form complexes with gold that are much more stable that those formed by hexahydropyrimidine and 1,3-diaminopropane.

  13. Orthorhombic Lithium Titanium Phosphate as an Anode Material for Li-ion Rechargeable Battery

    International Nuclear Information System (INIS)

    Kee, Yongho; Dimov, Nikolay; Minami, Keita; Okada, Shigeto

    2015-01-01

    Highlights: • Li-rich orthorhombic lithium titanium phosphate (OLTP) has been synthesized via a sol-gel route. • OLTP adopts a different space group from the previously reported rhombohedral lithium titanium phosphate (RLTP) and shows solid-solution charge/discharge curves. • OLTP shows higher Li + diffusivity and electrical conductivity, which makes it an attractive alternative for RLTP. - Abstract: Rhombohedral lithium titanium phosphate, LiTi 2 (PO 4 ) 3 , has been considered a suitable anode material for aqueous lithium-ion batteries. However, the electrochemical behaviors of pure lithium-rich polymorphs have not been described yet even Li-rich phase may show better electrochemical properties than conventional LiTi 2 (PO 4 ) 3 at the expense of somewhat lowered capacity. We have synthesized orthorhombic Li 1.5 Ti 2 (PO 4 ) 3 (OLTP) and rhombohedral LiTi 2 (PO 4 ) 3 (RLTP) via sol-gel reactions and studied their fundamental electrochemical properties using galvanostatic charge/discharge and cyclic voltammetry (CV). Their feasibility as anode materials in LiFePO 4 //Li x Ti 2 (PO 4 ) 3 configurations using aqueous electrolytes were also considered. The faster kinetics of the orthorhombic lithium titanium phosphate in this study were attributed to higher Li + diffusivity and electrical conductivity, making this material an attractive alternative for conventional rhombohedral LiTi 2 (PO 4 ) 3

  14. Anodic oxidation of anthraquinone dye Alizarin Red S at Ti/BDD electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Sun Jianrui; Lu Haiyan [College of Chemistry, Jilin University, Changchun 130012 (China); Du Lili [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Lin Haibo, E-mail: lhb910@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China); State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130012 (China); Li Hongdong, E-mail: hdli@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)

    2011-05-15

    The boron-doped diamond (BDD) thin-film electrode with high quality using industrially titanium plate (Ti/BDD) as substrate has been prepared and firstly used in the oxidation of anthraquinone dye Alizarin Red S (ARS) in wastewaters. The Ti/BDD electrodes are shown to have high concentration of sp{sup 3}-bonded carbon and wide electrochemical window. The results of the cyclic voltammetries show that BDD has unique properties such as high anodic stability and the production of active intermediates at the high potential. The oxidation regions of ARS and water are significantly separated at the Ti/BDD electrode, and the peak current increases linearly with increasing ARS concentration. The bulk electrolysis shows that removal of chemical oxygen demand (COD) and color can be completely reached and the electrooxidation of ARS behaves as a mass-transfer-controlled process at the Ti/BDD electrode. It is demonstrated that the performances of the Ti/BDD electrode for anodic oxidation ARS have been significantly improved with respect to the traditional electrodes.

  15. Hybrid direct carbon fuel cell anode processes investigated using a 3-electrode half-cell setup

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Arenillas, A.; Menendez, J.A.

    2015-01-01

    A 3-electrode half-cell setup consisting of a yttria-stabilized zirconia (YSZ) electrolyte support was employed to investigate the chemical and electrochemical processes occurring in the vicinity of a model hybrid direct carbon fuel cell (HDCFC) anode (Ni-YSZ) in contact with a molten carbon......-alkali carbonate slurry. Electrochemical testing, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), with and without the Ni-YSZ layer highlighted the promotional effect of the Ni-YSZ anode layer, and revealed the contributions of Ni/NiO, and potentially K/K2O, redox couple(s). Treated...... anthracite and bituminous coals, as well as carbon black, were tested, revealing similar open circuit potential and activation energies in mixed 96-4vol% N2-CO2 and 50-50vol% CO-CO2 environments between 700 and 800°C. Bituminous coal showed the highest activity, likely associated to a high O/C ratio...

  16. Effect of anodization on corrosion behaviour and biocompatibility of ...

    Indian Academy of Sciences (India)

    Pores of some anodized samples are sealed by exposing the anodized surface in boiling water. Corrosion behaviour of the anodized specimen is studied in Ringer's solution at 30 ± 2 °C, using electrochemical impedance and cyclic polarization technique. Biocompatibility of the anodized surface is accessed using MG63 ...

  17. Slow scan voltammetry for diffusion-controlled currents in sodium alginate solutions

    OpenAIRE

    Wang, Bo; Aoki, Koichi Jeremiah; Chen, Jingyuan; Nishiumi, Toyohiko

    2013-01-01

    Slow scan voltammetry is useful for extracting Faradaic diffusion-controlled currentfrom capacitive one, because the former and the latter are, respectively, proportional tothe square-root of scan rate and the scan rate itself. This report shows clear, reproduciblevoltammograms of 0.5μM redox species with the help of sodium alginate(SA)at scanrates less than 0.1 mV s-1. SA enhances viscosity of solution without any influence ondiffusion coefficient of the redox species so that natural convent...

  18. Characterization of an electrochemical mercury sensor using alternating current, cyclic, square wave and differential pulse voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Guerreiro, Gabriela V.; Zaitouna, Anita J.; Lai, Rebecca Y., E-mail: rlai2@unl.edu

    2014-01-31

    Graphical abstract: -- Highlights: •An electrochemical Hg(II) sensor based on T–Hg(II)–T sensing motif was fabricated. •A methylene blue-modified DNA probe was used to fabricate the sensor. •Sensor performance was evaluated using ACV, CV, SWV, and DPV. •The sensor behaves as a “signal-off” sensor in ACV and CV. •The sensor behaves as either a “signal-on” or “signal-off” sensor in SWV and DPV. -- Abstract: Here we report the characterization of an electrochemical mercury (Hg{sup 2+}) sensor constructed with a methylene blue (MB)-modified and thymine-containing linear DNA probe. Similar to the linear probe electrochemical DNA sensor, the resultant sensor behaved as a “signal-off” sensor in alternating current voltammetry and cyclic voltammetry. However, depending on the applied frequency or pulse width, the sensor can behave as either a “signal-off” or “signal-on” sensor in square wave voltammetry (SWV) and differential pulse voltammetry (DPV). In SWV, the sensor showed “signal-on” behavior at low frequencies and “signal-off” behavior at high frequencies. In DPV, the sensor showed “signal-off” behavior at short pulse widths and “signal-on” behavior at long pulse widths. Independent of the sensor interrogation technique, the limit of detection was found to be 10 nM, with a linear dynamic range between 10 nM and 500 nM. In addition, the sensor responded to Hg{sup 2+} rather rapidly; majority of the signal change occurred in <20 min. Overall, the sensor retains all the characteristics of this class of sensors; it is reagentless, reusable, sensitive, specific and selective. This study also highlights the feasibility of using a MB-modified probe for real-time sensing of Hg{sup 2+}, which has not been previously reported. More importantly, the observed “switching” behavior in SWV and DPV is potentially generalizable and should be applicable to most sensors in this class of dynamics-based electrochemical biosensors.

  19. SPR imaging combined with cyclic voltammetry for the detection of neural activity

    Directory of Open Access Journals (Sweden)

    Hui Li

    2014-03-01

    Full Text Available Surface plasmon resonance (SPR detects changes in refractive index at a metal-dielectric interface. In this study, SPR imaging (SPRi combined with cyclic voltammetry (CV was applied to detect neural activity in isolated bullfrog sciatic nerves. The neural activities induced by chemical and electrical stimulation led to an SPR response, and the activities were recorded in real time. The activities of different parts of the sciatic nerve were recorded and compared. The results demonstrated that SPR imaging combined with CV is a powerful tool for the investigation of neural activity.

  20. Screening of pharmacologic adulterant classes in herbal formulations using voltammetry of microparticles.

    Science.gov (United States)

    Doménech-Carbó, Antonio; Martini, Mariele; de Carvalho, Leandro Machado; Viana, Carine; Doménech-Carbó, María Teresa; Silva, Miguel

    2013-02-23

    A solid state electrochemical method for screening different families of adulterant chemicals illegally added to commercial phytotherapuetic formulations is described. The proposed method, based on the voltammetry of microparticles approach, permits a fast and sensitive way to distinguish between anorexics (amfepramone, fenproporex, sibutramine), benzozodiazepinic anxiolytics (clonazepam, flurazepam, alprazolam, midazolam, medazepam, chlordiazepoxide, diazepam), antidepressants (bupropione, fluoxetine, sertraline, paroxetine), diuretics (hydrochlorothiazide, furosemide, chlortalidone, amiloride, spironolactone), and hypoglycemics (glimepiride, chlorpropamide, glibenclamide) based on characteristic voltammetric signals recorded on solid micro- or nanosamples attached to graphite electrodes immersed into aqueous electrolytes. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Electrodeposition of Iridium Oxide by Cyclic Voltammetry: Application of Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Kakooei Saeid

    2014-07-01

    Full Text Available The effects of scan rate, temperature, and number of cycles on the coating thickness of IrOX electrodeposited on a stainless steel substrate by cyclic voltammetry were investigated in a statistical system. The central composite design, combined with response surface methodology, was used to study condition of electrodeposition. All fabricated electrodes were characterized using electrochemical methods. Field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy were performed for IrOX film characterization. Results showed that scan rate significantly affects the thickness of the electrodeposited layer. Also, the number of cycles has a greater effect than temperature on the IrOX thickness.

  2. Theory of Square-Wave Voltammetry of Two-Electron Reduction with the Adsorption of Intermediate

    Directory of Open Access Journals (Sweden)

    Milivoj Lovric

    2012-01-01

    Full Text Available Thermodynamically unstable intermediate of fast and reversible two-electron electrode reaction can be stabilized by the adsorption to the electrode surface. In square-wave voltammetry of this reaction mechanism, the split response may appear if the electrode surface is not completely covered by the adsorbed intermediate. The dependence of the difference between the net peak potentials of the prepeak and postpeak on the square-wave frequency is analyzed theoretically. This relationship can be used for the estimation of adsorption constant.

  3. Bacterial Community Analysis, New Exoelectrogen Isolation and Enhanced Performance of Microbial Electrochemical Systems Using Nano-Decorated Anodes

    Science.gov (United States)

    Xu, Shoutao

    Microbial electrochemical systems (MESs) have attracted much research attention in recent years due to their promising applications in renewable energy generation, bioremediation, and wastewater treatment. In a MES, microorganisms interact with electrodes via electrons, catalyzing oxidation and reduction reactions at the anode and the cathode. The bacterial community of a high power mixed consortium MESs (maximum power density is 6.5W/m2) was analyzed by using denature gradient gel electrophoresis (DGGE) and 16S DNA clone library methods. The bacterial DGGE profiles were relatively complex (more than 10 bands) but only three brightly dominant bands in DGGE results. These results indicated there are three dominant bacterial species in mixed consortium MFCs. The 16S DNA clone library method results revealed that the predominant bacterial species in mixed culture is Geobacter sp (66%), Arcobacter sp and Citrobacter sp. These three bacterial species reached to 88% of total bacterial species. This result is consistent with the DGGE result which showed that three bright bands represented three dominant bacterial species. Exoelectrogenic bacterial strain SX-1 was isolated from a mediator-less microbial fuel cell by conventional plating techniques with ferric citrate as electron acceptor under anaerobic conditions. Phylogenetic analysis of the 16S rDNA sequence revealed that it was related to the members of Citrobacter genus with Citrobacter sp. sdy-48 being the most closely related species. The bacterial strain SX-1 produced electricity from citrate, acetate, glucose, sucrose, glycerol, and lactose in MFCs with the highest current density of 205 mA/m2 generated from citrate. Cyclic voltammetry analysis indicated that membrane associated proteins may play an important role in facilitating electron transfer from the bacteria to the electrode. This is the first study that demonstrates that Citrobacter species can transfer electrons to extracellular electron acceptors

  4. KRITIK SOSIAL DALAM KOMIK STRIP PAK BEI

    Directory of Open Access Journals (Sweden)

    Yudhi Novriansyah

    2016-08-01

    Full Text Available This research aimed to do interpret the marking which flange social criticism and know laboring ideology in story of Comic Strip Pak Bei. Research based on theory of structural semiotic according to Ferdinand De Saussure. Using analysis of Syntagmatic as first level of meaning to the text network and also picture, and analysis of Paradigmatic as second level of meaning or implicit meaning (connota-tion, myth, ideology Analysis done to six Comic choice edition of Strip Pak Bei period of November 2004 - Februari 2005 which tend to flange social criticism. At band of syntagmatic, result of research indicate that story theme lifted from social problems that happened in major society. The fact clear progressively when connected by Intertextual with information and texts which have preexisted. At band of Paradigmatic, social criticism tend to emerge dimly, is not transparent. Because of Comic Strip Pak Bei expand in the middle of Java cultural domination that developing myth of criticize as action menacing compatibility and orderliness of society. Story of Comic Strip Pak Bei also confirm dominant ideology in Java society culture, namely ideology of Patriarkhi and Feudalism which still go into effect until now. This prove ideology idea according to Louis Althusser which not again opposition between class, but have been owned and practiced by all social class.

  5. Trees for strip-mined lands

    Science.gov (United States)

    George Hart; William R. Byrnes

    1960-01-01

    Open-pit or strip mining has become an important method of mining bituminous coal in Pennsylvania. In 1958 some 19.5 million tons of soft coal - 29 percent of the total bituminous production in the State - were produced by this method.

  6. Asset Stripping in a Mature Market Economy

    DEFF Research Database (Denmark)

    Klarskov Jeppesen, Kim; Møller, Ulrik Gorm

    2011-01-01

    Purpose – The purpose of this paper is to document a Danish fraud scheme, in which a large number of limited companies were stripped of their assets leaving them with nothing but tax debt, eventually causing the Danish Tax and Customs Administration to lose large sums. Furthermore, the purpose is...... the social supervisory system of a mature market economy. Originality/value – The paper contributes to the knowledge about asset stripping by documenting and analysing the phenomenon in a mature market economy context.......Purpose – The purpose of this paper is to document a Danish fraud scheme, in which a large number of limited companies were stripped of their assets leaving them with nothing but tax debt, eventually causing the Danish Tax and Customs Administration to lose large sums. Furthermore, the purpose...... is to analyse why the asset-stripping schemes occurred in a mature market economy with a strong corporate governance system and a low level of corruption. Design/methodology/approach – The research is conducted as a longitudinal single case study based on documentary research. Findings – The Danish case...

  7. 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…

  8. 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.

  9. Magnetic Fe3O4@TiO2 Nanoparticles-based Test Strip Immunosensing Device for Rapid Detection of Phosphorylated Butyrylcholinesterase

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Xiaoxiao; Zhang, Weiying; Lin, Yuehe; Du, Dan

    2013-12-15

    An integrated magnetic nanoparticles-based test-strip immunosensing device was developed for rapid and sensitive quantification of phosphorylated butyrylcholinesterase (BChE), the biomarker of exposure to organophosphous pesticides (OP), in human plasma. In order to overcome the difficulty in scarce availability of OP-specific antibody, here magnetic Fe3O4@TiO2 nanoparticles were used and adsorbed on the test strip through a small magnet inserted in the device to capture target OP-BChE through selective binding between TiO2 and OP moiety. Further recognition was completed by horseradish peroxidase (HRP) and anti-BChE antibody (Ab) co-immobilized gold nanoparticles (GNPs). Their strong affinities among Fe3O4@TiO2, OP-BChE and HRP/Ab-GNPs were characterized by quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and square wave voltammetry (SWV) measurements. After cutting off from test strip, the resulted immunocomplex (HRP/Ab-GNPs/OP-BChE/Fe3O4@TiO2) was measured by SWV using a screen printed electrode under the test zone. Greatly enhanced sensitivity was achieved by introduction of GNPs to link enzyme and antibody at high ratio, which amplifies electrocatalytic signal significantly. Moreover, the use of test strip for fast immunoreactions reduces analytical time remarkably. Coupling with a portable electrochemical detector, the integrated device with advanced nanotechnology displays great promise for sensitive, rapid and in-filed on-site evaluation of OP poisoning.

  10. Ductility of reinforced concrete columns confined with stapled strips

    International Nuclear Information System (INIS)

    Tahir, M.F.; Khan, Q.U.Z.; Shabbir, F.; Sharif, M.B.; Ijaz, N.

    2015-01-01

    Response of three 150x150x450mm short reinforced concrete (RC) columns confined with different types of confining steel was investigated. Standard stirrups, strips and stapled strips, each having same cross-sectional area, were employed as confining steel around four comer column bars. Experimental work was aimed at probing into the affect of stapled strip confinement on post elastic behavior and ductility level under cyclic axial load. Ductility ratios, strength enhancement factor and core concrete strengths were compared to study the affect of confinement. Results indicate that strength enhancement in RC columns due to strip and stapled strip confinement was not remarkable as compared to stirrup confined column. It was found that as compared to stirrup confined column, stapled strip confinement enhanced the ductility of RC column by 183% and observed axial capacity of stapled strip confined columns was 41 % higher than the strip confined columns. (author)

  11. Laboratory testing of Alcoscan saliva-alcohol test strips

    Science.gov (United States)

    1986-10-01

    This report describes a laboratory evaluation of Alcoscan saliva-alcohol test strips. The objectives of this work were: (1) to determine the precision and accuracy of the Alcoscan strips; and (2) to determine what effect extreme ambient temperatures ...

  12. Imaging of Low Compressibility Strips in the Quantum Hall Liquid

    OpenAIRE

    Finkelstein, G.; Glicofridis, P. I.; Tessmer, S. H.; Ashoori, R. C.; Melloch, M. R.

    1999-01-01

    Using Subsurface Charge Accumulation scanning microscopy we image strips of low compressibility corresponding to several integer Quantum Hall filling factors. We study in detail the strips at Landau level filling factors $\

  13. Structural Engineering of Nanoporous Anodic Alumina Photonic Crystals by Sawtooth-like Pulse Anodization.

    Science.gov (United States)

    Law, Cheryl Suwen; Santos, Abel; Nemati, Mahdieh; Losic, Dusan

    2016-06-01

    This study presents a sawtooth-like pulse anodization approach aiming to create a new type of photonic crystal structure based on nanoporous anodic alumina. This nanofabrication approach enables the engineering of the effective medium of nanoporous anodic alumina in a sawtooth-like manner with precision. The manipulation of various anodization parameters such as anodization period, anodization amplitude, number of anodization pulses, ramp ratio and pore widening time allows a precise control and fine-tuning of the optical properties (i.e., characteristic transmission peaks and interferometric colors) exhibited by nanoporous anodic alumina photonic crystals (NAA-PCs). The effect of these anodization parameters on the photonic properties of NAA-PCs is systematically evaluated for the establishment of a fabrication methodology toward NAA-PCs with tunable optical properties. The effective medium of the resulting NAA-PCs is demonstrated to be optimal for the development of optical sensing platforms in combination with reflectometric interference spectroscopy (RIfS). This application is demonstrated by monitoring in real-time the formation of monolayers of thiol molecules (11-mercaptoundecanoic acid) on the surface of gold-coated NAA-PCs. The obtained results reveal that the adsorption mechanism between thiol molecules and gold-coated NAA-PCs follows a Langmuir isotherm model, indicating a monolayer sorption mechanism.

  14. Macrokinetic relationships between anodic processes in chlorine electrolysis on ruthenium-titanium oxide anodes

    International Nuclear Information System (INIS)

    Evdokimov, S.V.

    1999-01-01

    Effect of porosity on kinetics of the main (chlorine evolution) and side (oxygen evolution and anodic dissolution of ruthenium dioxide) reactions for chlorine electrolysis conditions has been analyzed. Making allowance for chlorine hydrolysis secondary reaction, the distribution of chlorine concentration, solution pH and current densities of the main and side processes over the porous anode depth, have been found. It is shown that solution acidification in the anode pores due to chlorine hydrolysis can bring about replacement of oxygen evolution and ruthenium dioxide dissolution side reactions toward the porous anode external sides thus affecting its selectivity and corrosion resistance [ru

  15. Electrometallurgy of copper refinery anode slimes

    Science.gov (United States)

    Scott, J. D.

    1990-08-01

    High-selenium copper refinery anode slimes form two separate and dynamically evolving series of compounds with increasing electrolysis time. In one, silver is progressively added to non-stoichiometric copper selenides, both those originally present in the anode and those formed subsequently in the slime layer, and in the other, silver-poor copper selenides undergo a dis-continuous crystallographic sequence of anodic-oxidative transformations. The silver-to-selenium molar ratio in the as-cast anode and the current density of electrorefining can be used to construct predominance diagrams for both series and, thus, to predict the final bulk “mineralogy” of the slimes. Although totally incorrect in detail, these bulk data are sufficiently accurate to provide explanations for several processing problems which have been experienced by Kidd Creek Division, Falconbridge Ltd., in its commercial tankhouse. They form the basis for a computer model which predicts final cathode quality from chemical analyses of smelter feed.

  16. 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.

  17. Parallel superconducting strip-line detectors: reset behaviour in the single-strip switch regime

    International Nuclear Information System (INIS)

    Casaburi, A; Heath, R M; Tanner, M G; Hadfield, R H; Cristiano, R; Ejrnaes, M; Nappi, C

    2014-01-01

    Superconducting strip-line detectors (SSLDs) are an important emerging technology for the detection of single molecules in time-of-flight mass spectrometry (TOF-MS). We present an experimental investigation of a SSLD laid out in a parallel configuration, designed to address selected single strip-lines operating in the single-strip switch regime. Fast laser pulses were tightly focused onto the device, allowing controllable nucleation of a resistive region at a specific location and study of the subsequent device response dynamics. We observed that in this regime, although the strip-line returns to the superconducting state after triggering, no effective recovery of the bias current occurs, in qualitative agreement with a phenomenological circuit simulation that we performed. Moreover, from theoretical considerations and by looking at the experimental pulse amplitude distribution histogram, we have the first confirmation of the fact that the phenomenological London model governs the current redistribution in these large area devices also after detection events. (paper)

  18. Parallel superconducting strip-line detectors: reset behaviour in the single-strip switch regime

    Science.gov (United States)

    Casaburi, A.; Heath, R. M.; Tanner, M. G.; Cristiano, R.; Ejrnaes, M.; Nappi, C.; Hadfield, R. H.

    2014-04-01

    Superconducting strip-line detectors (SSLDs) are an important emerging technology for the detection of single molecules in time-of-flight mass spectrometry (TOF-MS). We present an experimental investigation of a SSLD laid out in a parallel configuration, designed to address selected single strip-lines operating in the single-strip switch regime. Fast laser pulses were tightly focused onto the device, allowing controllable nucleation of a resistive region at a specific location and study of the subsequent device response dynamics. We observed that in this regime, although the strip-line returns to the superconducting state after triggering, no effective recovery of the bias current occurs, in qualitative agreement with a phenomenological circuit simulation that we performed. Moreover, from theoretical considerations and by looking at the experimental pulse amplitude distribution histogram, we have the first confirmation of the fact that the phenomenological London model governs the current redistribution in these large area devices also after detection events.

  19. Polyelectrolyte microparticles for enhancing anode performance in an air–cathode μ-Liter microbial fuel cell

    International Nuclear Information System (INIS)

    Chen, Yan-Yu; Wang, Hsiang-Yu

    2015-01-01

    Highlights: • Microparticles with high consistency and surface area per volume are fabricated. • P(DADMAC) microparticles facilitate microorganism accumulation and charge transfer. • Microbes in microparticles are capable of proliferation and electricity generation. • Microparticles increase limiting current/power output to more than 200% of biofilm. • Microparticles decrease the anode charge-transfer resistance to 44% of biofilm. - Abstract: Microbial fuel cell (MFC) is considered an environmentally friendly energy source because it generates electrical power by digesting organic substrates in the wastewater. However, it is still challenging for MFC to become an economically affordable and highly efficient energy source due to its relatively low power output and coulombic efficiency. The aim of this study is to increase the performance of anode by using polyelectrolyte microparticles to facilitate the accumulation of microorganisms and the collection of electrons. The polyelectrolyte microparticle is subjected to microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and continuous electricity generation in an air–cathode μ-Liter MFC (μMFC) to validate its biocompatibility, ability in retaining redox species, reduced electron transfer resistance, and sustained energy generation. During the 168-hour operation, microorganisms proliferate inside the microparticle and generate around 250% power output and 200% limiting current of those from microorganism biofilm. The polyelectrolyte microparticle also decreased charge-transfer resistance of anode electrode in air–cathode μMFC by 56% compared with biofilm.

  20. Enhanced performance of a novel anodic PdAu/VGCNF catalyst for electro-oxidation in a glycerol fuel cell.

    Science.gov (United States)

    Yahya, N; Kamarudin, S K; Karim, N A; Masdar, M S; Loh, K S

    2017-11-25

    This study presents a novel anodic PdAu/VGCNF catalyst for electro-oxidation in a glycerol fuel cell. The reaction conditions are critical issues affecting the glycerol electro-oxidation performance. This study presents the effects of catalyst loading, temperature, and electrolyte concentration. The glycerol oxidation performance of the PdAu/VGCNF catalyst on the anode side is tested via cyclic voltammetry with a 3 mm 2 active area. The morphology and physical properties of the catalyst are examined using X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Then, optimization is carried out using the response surface method with central composite experimental design. The current density is experimentally obtained as a response variable from a set of experimental laboratory tests. The catalyst loading, temperature, and NaOH concentration are taken as independent parameters, which were evaluated previously in the screening experiments. The highest current density of 158.34 mAcm -2 is obtained under the optimal conditions of 3.0 M NaOH concentration, 60 °C temperature and 12 wt.% catalyst loading. These results prove that PdAu-VGCNF is a potential anodic catalyst for glycerol fuel cells.

  1. Electrochemical incineration of chloromethylphenoxy herbicides in acid medium by anodic oxidation with boron-doped diamond electrode

    International Nuclear Information System (INIS)

    Boye, Birame; Brillas, Enric; Marselli, Beatrice; Michaud, Pierre-Alain; Comninellis, Christos; Farnia, Giuseppe; Sandona, Giancarlo

    2006-01-01

    The electrochemical degradation of saturated solutions of herbicides 4-chloro-2-methylphenoxyacetic acid, 2-(4-chlorophenoxy)-2-methylpropionic acid and 2-(4-chloro-2-methylphenoxy)propionic acid in 1 M HClO 4 on a boron-doped diamond (BDD) thin film anode has been studied by chronoamperometry, cyclic voltammetry and bulk electrolysis. At low anodic potentials polymeric products are formed causing the fouling and deactivation of BDD. This is reactivated at high potentials when water decomposes producing hydroxyl radical as strong oxidant of organics. Electrolyses in a batch recirculation system at constant current density ≥8 mA cm -2 yielded overall decontamination of all saturated solution. The effect of current density and herbicide concentration on the degradation rate of each compound, the specific charge required for its total mineralization and instantaneous current efficiency have been investigated. Experimental results have been compared with those predicted by a theoretical model based on a fast anodic oxidation of initial herbicides, showing that at 30 mA cm -2 their degradation processes are completely controlled by mass transfer. Kinetic analysis of the change of herbicide concentration with time during electrolysis, determined by high-performance liquid chromatography, revealed that all compounds follow a pseudo first-order reaction. Aromatic intermediates and generated carboxylic acids have been identified using this technique and a general pathway for the electrochemical incineration of all herbicides on BDD is proposed

  2. Anodic growth of titanium dioxide nanostructures

    DEFF Research Database (Denmark)

    2010-01-01

    Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

  3. Electrical results of double-sided silicon strip modules for the ATLAS Upgrade Strip Tracker

    CERN Document Server

    Gonzalez-Sevilla, S; The ATLAS collaboration; Cadoux, F; Clark, A; Ferrere, D; Ikegami, Y; Hara, K; La Marra, D; Pelleriti, G; Pohl, M; Takubo, Y; Terada, S; Unno, Y; Weber, M

    2012-01-01

    A double-sided silicon strip module has been designed for the short-strip barrel region of the future ATLAS inner tracker for the High Luminosity LHC. University of Geneva and KEK have produced first module prototypes with common components and similar assembly procedures and jigs. This note reports on the electrical performance of the modules tested. The data acquisition system is described. Results from individual and combined module readout are shown.

  4. Use of hydrogen peroxide to achieve interference-free stripping voltammetric determination of copper at the bismuth-film electrode

    International Nuclear Information System (INIS)

    Pacheco, Wagner F.; Miguel, Eliane M.; Ramos, Gabriel V.; Cardoso, Carlos E.; Farias, Percio A.M.; Aucelio, Ricardo Q.

    2008-01-01

    In this work, a new approach is presented to allow interference-free determination of Cu (II) by stripping voltammetry using the bismuth-film electrode. The addition of hydrogen peroxide to the electroanalytical cell has promoted complete resolution between re-dissolution peaks of Bi (III) and Cu (II). The absence of interference could be evaluated by the correlation coefficient (r > 0.99) between Cu (II) concentration and its shifted current peak (at +212 mV) while achieving a slightly fluctuation of the bismuth current peak at -180 mV. Studies were performed aiming towards the optimum conditions for trace determination of Cu (II) using hydrogen peroxide. The methodology was applied to a real sample (sugarcane spirits) and the results were compared to those from graphite furnace atomic absorption spectrometry. The analytical parameters of merit and the results of the analysis indicated that the analytical methodology could be readily used for trace determination of Cu (II)

  5. Testbeam evaluation of silicon strip modules for ATLAS Phase - II Strip Tracker Upgrade

    CERN Document Server

    Blue, Andrew; The ATLAS collaboration; Ai, Xiaocong; Allport, Phillip; Arling, Jan-Hendrik; Atkin, Ryan Justin; Bruni, Lucrezia Stella; Carli, Ina; Casse, Gianluigi; Chen, Liejian; Chisholm, Andrew; Cormier, Kyle James Read; Cunningham, William Reilly; Dervan, Paul; Diez Cornell, Sergio; Dolezal, Zdenek; Dopke, Jens; Dreyer, Etienne; Dreyling-Eschweiler, Jan Linus Roderik; Escobar, Carlos; Fabiani, Veronica; Fadeyev, Vitaliy; Fernandez Tejero, Javier; Fleta Corral, Maria Celeste; Gallop, Bruce; Garcia-Argos, Carlos; Greenall, Ashley; Gregor, Ingrid-Maria; Greig, Graham George; Guescini, Francesco; Hara, Kazuhiko; Hauser, Marc Manuel; Huang, Yanping; Hunter, Robert Francis Holub; Keller, John; Klein, Christoph; Kodys, Peter; Koffas, Thomas; Kotek, Zdenek; Kroll, Jiri; Kuehn, Susanne; Lee, Steven Juhyung; Liu, Yi; Lohwasser, Kristin; Meszarosova, Lucia; Mikestikova, Marcela; Mi\\~nano Moya, Mercedes; Mori, Riccardo; Moser, Brian; Nikolopoulos, Konstantinos; Peschke, Richard; Pezzullo, Giuseppe; Phillips, Peter William; Poley, Anne-luise; Queitsch-Maitland, Michaela; Ravotti, Federico; Rodriguez Rodriguez, Daniel

    2018-01-01

    The planned HL-LHC (High Luminosity LHC) is being designed to maximise the physics potential of the LHC with 10 years of operation at instantaneous luminosities of \\mbox{$7.5\\times10^{34}\\;\\mathrm{cm}^{-2}\\mathrm{s}^{-1}$}. A consequence of this increased luminosity is the expected radiation damage requiring the tracking detectors to withstand hadron equivalences to over $1x10^{15}$ 1 MeV neutron equivalent per $cm^{2}$ in the ATLAS Strips system. The silicon strip tracker exploits the concept of modularity. Fast readout electronics, deploying 130nm CMOS front-end electronics are glued on top of a silicon sensor to make a module. The radiation hard n-in-p micro-strip sensors used have been developed by the ATLAS ITk Strip Sensor collaboration and produced by Hamamatsu Photonics. A series of tests were performed at the DESY-II test beam facility to investigate the detailed performance of a strip module with both 2.5cm and 5cm length strips before irradiation. The DURANTA telescope was used to obtain a pointing...

  6. Fibrous zinc anodes for high power batteries

    Science.gov (United States)

    Zhang, X. Gregory

    This paper introduces newly developed solid zinc anodes using fibrous material for high power applications in alkaline and large size zinc-air battery systems. The improved performance of the anodes in these two battery systems is demonstrated. The possibilities for control of electrode porosity and for anode/battery design using fibrous materials are discussed in light of experimental data. Because of its mechanical integrity and connectivity, the fibrous solid anode has good electrical conductivity, mechanical stability, and design flexibility for controlling mass distribution, porosity and effective surface area. Experimental data indicated that alkaline cells made of such anodes can have a larger capacity at high discharging currents than commercially available cells. It showed even greater improvement over commercial cells with a non-conventional cell design. Large capacity anodes for a zinc-air battery have also been made and have shown excellent material utilization at various discharge rates. The zinc-air battery was used to power an electric bicycle and demonstrated good results.

  7. Investigation of antioxidant capacity of the extracts of bilberry (VACCINUM MYRTILLIS L.) by voltammetry

    International Nuclear Information System (INIS)

    Vtorushina, A N; Nikonova, E D

    2016-01-01

    This paper deals with the urgent issue of the search of new drugs based on plant raw materials that have an influence on various stages of oxidation processes occurring in the human body. The aim of this paper is to determine the antioxidant activity of the bilberry extracts that are used in the medicine practice by a cathodic voltammetry method.We consider the influence of water and alcohol bilberry extracts on the process of oxygen electroreduction. From these extracts the most activity relation to the process of cathodic oxygen reduction showed alcohol (40%) bilberry extract. It was also stated that the alcohol extract of bilberry has a greater antioxidant activity than other known antioxidants such as ascorbic acid, glucose, dihydroquercetin.Thus, after consideration of a number of plant objects, we showed the possibility of applying the method of cathodic voltammetry for the determination of total antioxidant activity of plant material and identifying and highlighting the most perspective sources of biologically active substances (BAS), as well as the ability of identifying extractants that fully extract BAS from plant raw materials. The activity data of extracts of plant raw materials gives an opportunity of establishing an effective yield phytopreparation based on bilberry that has an antioxidant effect. (paper)

  8. Investigation of antioxidant capacity of the extracts of bilberry (VACCINUM MYRTILLIS L.) by voltammetry

    Science.gov (United States)

    Vtorushina, A. N.; Nikonova, E. D.

    2016-02-01

    This paper deals with the urgent issue of the search of new drugs based on plant raw materials that have an influence on various stages of oxidation processes occurring in the human body. The aim of this paper is to determine the antioxidant activity of the bilberry extracts that are used in the medicine practice by a cathodic voltammetry method. We consider the influence of water and alcohol bilberry extracts on the process of oxygen electroreduction. From these extracts the most activity relation to the process of cathodic oxygen reduction showed alcohol (40%) bilberry extract. It was also stated that the alcohol extract of bilberry has a greater antioxidant activity than other known antioxidants such as ascorbic acid, glucose, dihydroquercetin. Thus, after consideration of a number of plant objects, we showed the possibility of applying the method of cathodic voltammetry for the determination of total antioxidant activity of plant material and identifying and highlighting the most perspective sources of biologically active substances (BAS), as well as the ability of identifying extractants that fully extract BAS from plant raw materials. The activity data of extracts of plant raw materials gives an opportunity of establishing an effective yield phytopreparation based on bilberry that has an antioxidant effect.

  9. Parameters affecting the determination of paraquat at silver rotating electrodes using differential pulse voltammetry

    Directory of Open Access Journals (Sweden)

    A. Farahi

    2014-08-01

    Full Text Available The electrochemical determination of aqueous paraquat PQ(II by differential pulse voltammetry at a solid rotating silver electrode (RSE is described. The aim of this work is to optimize all factors that can influence this determination. Potential wave forms, potential scan parameters and deposition time were examined for their effect on the paraquat peak shape and intensity. The best responses were obtained with differential pulse voltammetry in 0.1 mol L−1 Na2SO4 as supporting electrolyte using amplitude 50 mV, scan increment 5 mV, deposition time 120 s, frequency 50 s−1 and step amplitude 0.05 V. Electrochemical and mechanical surface cleaning, aimed at removing the amount of paraquat deposited onto the silver surface, were necessary for obtaining a good performance of the electrode. Response linearity, repeatability, accuracy and detection limit were also evaluated. The obtained detection limits were 7.1 × 10−9 mol L−1 and 2.8 × 10−9 mol L−1 for peak 1 and peak 2 respectively. The relative standard deviation (RSD was found to be 1.19% in 1.0 × 10−4 mol L−1 paraquat. The applicability of the RSE for PQ(II determination in milk samples, without any sample pretreatment, was successfully demonstrated.

  10. Hydrodynamic Voltammetry as a Rapid and Simple Method for Evaluating Soil Enzyme Activities

    Directory of Open Access Journals (Sweden)

    Kazuto Sazawa

    2015-03-01

    Full Text Available Soil enzymes play essential roles in catalyzing reactions necessary for nutrient cycling in the biosphere. They are also sensitive indicators of ecosystem stress, therefore their evaluation is very important in assessing soil health and quality. The standard soil enzyme assay method based on spectroscopic detection is a complicated operation that requires the removal of soil particles. The purpose of this study was to develop a new soil enzyme assay based on hydrodynamic electrochemical detection using a rotating disk electrode in a microliter droplet. The activities of enzymes were determined by measuring the electrochemical oxidation of p-aminophenol (PAP, following the enzymatic conversion of substrate-conjugated PAP. The calibration curves of β-galactosidase (β-gal, β-glucosidase (β-glu and acid phosphatase (AcP showed good linear correlation after being spiked in soils using chronoamperometry. We also performed electrochemical detection using real soils. Hydrodynamic chronoamperometry can be used to assess the AcP in soils, with a detection time of only 90 s. Linear sweep voltammetry was used to measure the amount of PAP released from β-gal and β-glu by enzymatic reaction after 60 min. For the assessment of soil enzymes, the results of hydrodynamic voltammetry assay compared favorably to those using a standard assay procedure, but this new procedure is more user-friendly, rapid and simple.

  11. Preservation of NADH voltammetry for enzyme-modified electrodes based on dehydrogenase.

    Science.gov (United States)

    Hayes, M A; Kuhr, W G

    1999-05-01

    Minimizing overpotential and generating high faradaic currents are critical issues for fast-scan voltammetry of beta-nicotinamide adenine dinucleotide (NADH) for the sensitivity of enzyme-modified electrodes based on dehydrogenases. Although NADH voltammetry exhibits high overpotential and poor voltammetric peak shape at solid electrode surfaces, modification of the electrode surface can improve the electrochemical response at carbon fibers. However, these improvements are severely degraded upon the covalent attachment of enzyme. The creation of improved electron-transfer properties and the retention of these properties throughout the enzyme attachment process is the focus of this study. A novel polishing and electrochemical pretreatment method was developed which generated a decreased overpotential and a high faradaic current at carbon-fiber electrodes for NADH. Factors that lead to a degradation of voltammetric response during the enzyme fabrication were investigated, and both the aging and the covalent modification of the pretreated surface contributed to this degradation. Attachment processes that minimized the preparation time, in turn, maximized the retention of the facile electron-transfer properties. These attachment processes included varying the surface attachment reactions for the enzyme. Preparation time reduction techniques included modeling existing techniques and then improving kinetic and mass transport issues where possible. Alternate covalent attachment methods included a direct electrochemical amine reaction and an electrochemically reductive hydrazide reaction. The surface attachment and retention of electron-transfer properties of these probes were confirmed by fluorescence and electrochemical studies.

  12. Combined characterization of bovine polyhemoglobin microcapsules by UV-Vis absorption spectroscopy and cyclic voltammetry.

    Science.gov (United States)

    Knirsch, Marcos Camargo; Dell'Anno, Filippo; Salerno, Marco; Larosa, Claudio; Polakiewicz, Bronislaw; Eggenhöffner, Roberto; Converti, Attilio

    2017-03-01

    Polyhemoglobin produced from pure bovine hemoglobin by reaction with PEG bis(N-succynimidil succinate) as a cross-linking agent was encapsulated in gelatin and dehydrated by freeze-drying. Free carboxyhemoglobin and polyhemoglobin microcapsules were characterized by UV-Vis spectroscopy in the absorption range 450-650 nm and cyclic voltammetry in the voltage range from -0.8 to 0.6 mV to evaluate the ability to break the bond with carbon monoxide and to study the carrier's affinity for oxygen, respectively. SEM used to observe the shape of cross-linked gelatin-polyhemoglobin microparticles showed a regular distribution of globular shapes, with mean size of ~750 nm, which was ascribed to gelatin. Atomic absorption spectroscopy was also performed to detect iron presence in microparticles. Cyclic voltammetry using an Ag-AgCl electrode highlighted characteristic peaks at around -0.6 mV that were attributed to reversible oxygen bonding with iron in oxy-polyhemoglobin structure. These results suggest this technique as a powerful, direct and alternative method to evaluate the extent of hemoglobin oxygenation.

  13. Conveyorized Photoresist Stripping Replacement for Flex Circuit Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Megan Donahue

    2009-02-24

    A replacement conveyorized photoresist stripping system was characterized to replace the ASI photoresist stripping system. This system uses the qualified ADF-25c chemistry for the fabrication of flex circuits, while the ASI uses the qualified potassium hydroxide chemistry. The stripping process removes photoresist, which is used to protect the copper traces being formed during the etch process.

  14. 7 CFR 29.6128 - Straight Stripped (X Group).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Straight Stripped (X Group). 29.6128 Section 29.6128... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.6128 Straight Stripped (X Group). This group consists of..., and tolerances X1 Fine Quality Straight Stripped. Heavy, ripe, firm, semielastic, normal strength and...

  15. 21 CFR 880.2200 - Liquid crystal forehead temperature strip.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Liquid crystal forehead temperature strip. 880... Personal Use Monitoring Devices § 880.2200 Liquid crystal forehead temperature strip. (a) Identification. A liquid crystal forehead temperature strip is a device applied to the forehead that is used to indicate...

  16. Voltage Oscillations in a Polymer Electrolyte Membrane Fuel Cell with Pd-Pt/C and Pd/C Anodes.

    Science.gov (United States)

    Nogueira, Jéssica Alves; Varela, Hamilton

    2017-10-01

    Polymer electrolyte membrane fuel cells (PEMFC) fed with H 2 contaminated with CO may exhibit oscillatory behavior when operated galvanostatically. The self-organization of the anodic overpotential is interesting because it can be accompanied by an increase in the average performance. Herein we report experimental studies of voltage oscillations that emerge in a PEMFC equipped with a Pd/C or PdPt/C anode and fed with H 2 contaminated with CO (100 ppm). We used on-line mass spectrometry to investigate how the mass fragments associated with CO 2 and CO ( m / z 44 and 28, respectively) varied with the voltage oscillations. Overall, we observed that oscillations in the anodic overpotential are in phase with that of the CO and CO 2 signals. This fact is consistent with an autonomous adsorption-oxidation cyclic process. For both anodes, it has been observed that, in general, an increase in current density implies an increase in oscillatory frequency. By using CO stripping, we also discuss how the onset of CO oxidation is related to the maximum overpotential reached during a cycle, whereas the minimum overpotential can be associated with the catalytic activity of the electrode for H 2 oxidation.

  17. Study of the CSC anode self-trigger ability with P3 ME1/1 prototype

    International Nuclear Information System (INIS)

    Golutvin, I.; Gorbunov, N.; Khabarov, V.; Mojsenz, P.; Movchan, S.; Perelygin, V.; Sergeev, S.; Smolin, D.; Zarubin, A.

    2005-01-01

    The influence of the high background rates on the Cathode Strip Chamber (CSC) anode trigger has been studied. The investigation has been made with P3 prototype of the CSC of the ME1/1 endcap muon station of the CMS experiment (CERN). The work has been done at the Gamma Irradiation Facility (GIF, CERN). P3 has been installed at the X5c muon beam line in the background field of the 137 Cs source. The CSC timing resolution and track registration efficiency as a function of the gamma rate are presented

  18. 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

  19. The Effects of Trace Anions on the Voltammetry of Single Crystal Gold Surfaces

    Science.gov (United States)

    1989-08-18

    therefore where adsorption is diffusion limited) is equivalent to increasing the effective concen- tration. Variation of sweep speed has a similar...suggestive of a Temkin -like desorption process (21). 7. The curve at more negative potentials values drops slightly, probably because of residual traces...by the intentional addition of Ci- ions. It is not as clear where in the anodic sweep the ions are adsorbed since the adsorption is diffusion limited

  20. New High-Energy Nanofiber Anode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangwu [North Carolina State Univ., Raleigh, NC (United States); Fedkiw, Peter [North Carolina State Univ., Raleigh, NC (United States); Khan, Saad [North Carolina State Univ., Raleigh, NC (United States); Huang, Alex [North Carolina State Univ., Raleigh, NC (United States); Fan, Jiang [North Carolina State Univ., Raleigh, NC (United States)

    2013-11-15

    The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 μm or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

  1. Ammonia recovery from anaerobically digested cattle manure by steam stripping.

    Science.gov (United States)

    Zeng, L; Mangan, C; Li, X

    2006-01-01

    Ammonia recovery from anaerobically digested cattle manure effluents through steam stripping was studied at a stripping tower temperature of 98-99 degrees C and a steam-water ratio approximately 56-72 g/L. The digested manure effluents were first treated by microfiltration and then the permeate was used as feed in steam stripping. The stripping performance was evaluated under different feed pH values, ammonia concentrations and temperatures. The increase of the initial feed pH does not significantly improve ammonia stripping efficiency due to the fact that the stripped effluent pH is increased during steam stripping. This suggests that steam stripping of anaerobically digested manure effluents for ammonia recovery may not need pre-raised pH. In contrast, the pH value of the synthetic ammonia wastewater containing NH4Cl dramatically decreases after steam stripping. Increasing the feed temperature slightly improves ammonia stripping efficiency, but reduces the concentration of the recovered ammonia in the condensate due to an increased condensate volume at a higher feed temperature. Therefore, the feed temperature should be controlled at an optimum point that can compromise the condensate ammonia concentration and the ammonia stripping efficiency. Experimental results indicate that recovery of ammonia from anaerobically digested cattle manure effluents as NH4OH is technically feasible.

  2. Dual deflectable beam strip engine development.

    Science.gov (United States)

    Dulgeroff, C. R.; Zuccaro, D. E.; Kami, S.; Schnelker, D. E.; Ward, J. W.

    1972-01-01

    This paper describes a dual beam thruster that has been designed, constructed, and tested. The system is suitable for two-axes attitude control and is comprised of two orthogonal strips, each capable of producing 0.30 mlb thrust and beam deflections of more than plus or minus 20 deg. The nominal specific impulse for the thruster is 5000 sec, and the thrust level from each strip can be varied from 0 to 100%. Neutralizer filaments that were developed and life tested over 2000 hours producing more than 40 mA of electron emission per watt of input power are also discussed. The system power required for clean ionizers is approximately 200 W.

  3. Nuclear reactor spring strip grid spacer

    International Nuclear Information System (INIS)

    Patterson, J.F.; Flora, B.S.

    1980-01-01

    An improved and novel grid spacer was developed for use in nuclear reactor fuel assemblies. It is comprised of a series of intersecting support strips and a peripheral support band attached to the ends of the support strips. Each of the openings into which the fuel element is inserted has a number of protruding dimples and springs extending in different directions. The dimples coact with the springs to secure the fuel rods in the openings. Compared with previous designs, this design gives more positive alignment of the support stips while allowing greater flexibility to counterbalance the effects of thermal expansion. The springs are arranged in alternating directions so that the reaction forces tend to counterbalance each other, which in turn minimizes the reaction loads on the supporting structure. (D.N.)

  4. 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.

  5. Strip-till seeder for sugar beets

    Directory of Open Access Journals (Sweden)

    Peter Schulze Lammers

    2014-06-01

    Full Text Available Strip-till save costs by reducing tillage on the area of sugar beet rows only. The seeding system is characterized by a deep loosening of soil with a tine combined with a share and by following tools generating fine-grained soil as seed bed. In cooperation with the Kverneland company group Soest/Germany a strip tiller combined with precision seeder was designed and tested in field experiments. Tilling and seeding was performed in one path on fields with straw and mustard mulch. Even the plant development was slower as compared to conventional sawn sugar beets the yield was on equivalent level. Further field experiments are planned to attest constant yield, cost and energy efficiency of the seeding system.

  6. Continuous liquid sheet generator for ion stripping

    International Nuclear Information System (INIS)

    Gavin, B.; Batson, P.; Leemann, B.; Rude, B.

    1984-10-01

    Many of the technical problems of generating a large thin liquid sheet from 0.02 to 0.20 μm thick (3 to 40 μgm/cm 2 ) have been solved. It is shown that this perennial sheet is stable and consonant in dimension. Several ion beam species from the SuperHILAC have been used for evaluation; at 0.11 MeV/n. In one of three modes this sheet serves as an equivalent substitute for a carbon foil. The second mode is characterized by a solid-like charge state distribution but with a varying fraction of unstripped ions. The third mode gives stripping performance akin to a vapor stripping medium. 9 references, 7 figures

  7. Strengthening Bridges with Prestressed CFRP Strips

    Science.gov (United States)

    Siwowski, Tomasz; Żółtowski, Piotr

    2012-06-01

    Limitation of bridge's carrying bearing capacity due to aging and deterioration is a common problem faced by road administration and drivers. Rehabilitation of bridges including strengthening may be applied in order to maintain or upgrade existing bridge parameters. The case studies of strengthening of two small bridges with high modulus prestressed CFRP strips have been presented in the paper. The first one - reinforced concrete slab bridge - and the other - composite steel-concrete girder bridge - have been successfully upgraded with quite new technology. In both cases the additional CFRP reinforcement let increasing of bridge carrying capacity from 15 till 40 metric tons. The CFRP strip prestressing system named Neoxe Prestressing System (NPS), developed by multi-disciplinary team and tested at full scale in Rzeszow University of Technology, has been also described in the paper.

  8. The extent of the stop coannihilation strip

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, John [King' s College London, Theoretical Particle Physics and Cosmology Group, Department of Physics, London (United Kingdom); CERN, Theory Division, Geneva 23 (Switzerland); Olive, Keith A. [University of Minnesota, School of Physics and Astronomy, Minneapolis, MN (United States); University of Minnesota, William I. Fine Theoretical Physics Institute, School of Physics and Astronomy, Minneapolis, MN (United States); Zheng, Jiaming [University of Minnesota, School of Physics and Astronomy, Minneapolis, MN (United States)

    2014-07-15

    Many supersymmetric models such as the constrained minimal supersymmetric extension of the Standard Model (CMSSM) feature a strip in parameter space where the lightest neutralino χ is identified as the lightest supersymmetric particle, the lighter stop squark t{sub 1} is the next-to-lightest supersymmetric particle (NLSP), and the relic χ cold darkmatter density is brought into the range allowed by astrophysics and cosmology by coannihilation with the lighter stop squark t{sub 1} NLSP. We calculate the stop coannihilation strip in the CMSSM, incorporating Sommerfeld enhancement effects, and we explore the relevant phenomenological constraints and phenomenological signatures. In particular, we show that the t{sub 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. (orig.)

  9. 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...

  10. Antenna with distributed strip and integrated electronic components

    Science.gov (United States)

    Rodenbeck, Christopher T [Albuquerque, NM; Payne, Jason A [Albuquerque, NM; Ottesen, Cory W [Albuquerque, NM

    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.

  11. Neutralization of H- beams by magnetic stripping

    International Nuclear Information System (INIS)

    Jason, A.J.; Hudgings, D.W.; van Dyck, O.B.

    1981-01-01

    The stability of H - beams passing through strong magnetic fields has been relevant to accelerator transport problems and, recently, to neutral beam preparation techniques. The H - electron detachment rate was measured as a function of rest-frame electric field and provides parameters for a theoretical lifetime expression. The limitations imposed on H - transport by magnetic stripping, and neutral-beam preparation in emittance growth, magnetic fields, and beam energies are discussed. Application techniques are also briefly discussed

  12. Ram pressure stripping of tilted galaxies

    Czech Academy of Sciences Publication Activity Database

    Jáchym, Pavel; Köppen, J.; Palouš, Jan; Combes, F.

    2009-01-01

    Roč. 500, č. 2 (2009), s. 693-703 ISSN 0004-6361 R&D Projects: GA MŠk(CZ) LC06014; GA ČR GP205/08/P556 Institutional research plan: CEZ:AV0Z10030501 Keywords : interstellar medium * clusters of galaxies * gas stripping Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.179, year: 2009

  13. Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

    Science.gov (United States)

    Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

    2018-06-05

    Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. CLOSED-LOOP STRIPPING ANALYSIS (CLSA) OF ...

    Science.gov (United States)

    Synthetic musk compounds have been found in surface water, fish tissues, and human breast milk. Current techniques for separating these compounds from fish tissues require tedious sample clean-upprocedures A simple method for the deterrnination of these compounds in fish tissues has been developed. Closed-loop stripping of saponified fish tissues in a I -L Wheaton purge-and-trap vessel is used to strip compounds with high vapor pressures such as synthetic musks from the matrix onto a solid sorbent (Abselut Nexus). This technique is useful for screening biological tissues that contain lipids for musk compounds. Analytes are desorbed from the sorbent trap sequentially with polar and nonpolar solvents, concentrated, and directly analyzed by high resolution gas chromatography coupled to a mass spectrometer operating in the selected ion monitoring mode. In this paper, we analyzed two homogenized samples of whole fish tissues with spiked synthetic musk compounds using closed-loop stripping analysis (CLSA) and pressurized liquid extraction (PLE). The analytes were not recovered quantitatively but the extraction yield was sufficiently reproducible for at least semi-quantitative purposes (screening). The method was less expensive to implement and required significantly less sample preparation than the PLE technique. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water,

  15. Deuteron stripping reactions with Tabakin potential

    International Nuclear Information System (INIS)

    Osman, A.

    1976-05-01

    Deuteron stripping reactions are considered. Due to the strong repulsion between nucleons at very short distances, we have investigated the nuclear short-range correlations. The neutron proton nuclear potential in the deuteron is taken as a short-range repulsive core surrounded by a long-range attractive potential. The neutron-proton potential is taken as the Tabakin separable potential to take into account the short-range correlations. The differential cross-sections for deuteron stripping reactions have been calculated in two different cases by taking Yamaguchi or Breit et al type parameters for the Tabakin potential used. The angular distributions for different (d,p) stripping reactions on the different target nuclei 28 Si, 32 , 34 S, 36 Ar, 40 , 48 Ca, 50 , 52 , 54 Cr have been calculated using the DWBA calculations. Our present theoretical calculations for the angular distributions of the different reactions cosidered have been fitted to the experimental data, where good agreement is obtained. The extracted spectroscopic factors from the present work are found to be more reliable

  16. A novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances

    International Nuclear Information System (INIS)

    Dong Linxi; Chen Jindan; Huo Weihong; Li Yongjie; Sun Lingling; Yan Haixia

    2009-01-01

    The comb capacitances fabricated by deep reactive ion etching (RIE) process have high aspect ratio which is usually smaller than 30: 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate's effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio (30 : 1) of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy (FEM) tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.

  17. Electrolytic Cell For Production Of Aluminum Employing Planar Anodes.

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, Robert J. (Goldendale, WA); Mezner, Michael B. (Sandy, OR); Bradford, Donald R (Underwood, WA)

    2004-10-05

    A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising providing a molten salt electrolyte having alumina dissolved therein in an electrolytic cell. A plurality of anodes and cathodes having planar surfaces are disposed in a generally vertical orientation in the electrolyte, the anodes and cathodes arranged in alternating or interleaving relationship to provide anode planar surfaces disposed opposite cathode planar surfaces, the anode comprised of carbon. Electric current is passed through anodes and through the electrolyte to the cathodes depositing aluminum at the cathodes and forming carbon containing gas at the anodes.

  18. Noise analysis due to strip resistance in the ATLAS SCT silicon strip module

    International Nuclear Information System (INIS)

    Kipnis, I.

    1996-08-01

    The module is made out of four 6 cm x 6 cm single sided Si microstrip detectors. Two detectors are butt glued to form a 12 cm long mechanical unit and strips of the two detectors are electrically connected to form 12 cm long strips. The butt gluing is followed by a back to back attachment. The module in this note is the Rφ module where the electronics is oriented parallel to the strip direction and bonded directly to the strips. This module concept provides the maximum signal-to-noise ratio, particularly when the front-end electronics is placed near the middle rather than at the end. From the noise analysis, it is concluded that the worst-case ΔENC (far-end injection) between end- and center-tapped modules will be 120 to 210 el. rms (9 to 15%) for a non-irradiated detector and 75 to 130 el. rms (5 to 9%) for an irradiated detector, for a metal strip resistance of 10 to 20 Ω/cm

  19. Voltammetry of uranyl chloride in the LiCl - KCl eutectic

    International Nuclear Information System (INIS)

    Fondanaiche, J.C.

    1965-01-01

    Spent UO 2 - PuO 2 fuels can be reprocessed in a molten salt media. Uranium dioxide can easily be dissolved as UO 2 Cl 2 in a molten salt bath using chlorine gas. A study of quantitative analysis of an uranyl chloride solution in the LiCl-KCl eutectic at 400 C has been performed here using voltammetry (a large area-graphite indicator electrode has been employed). The precision which is obtained is around 6 per cent for concentrations below 10 -2 M. Precision decreases slightly for more concentrated solutions. The study of polarization curves allowed to give a reduction mechanism for the UO 2 ++ ion. For dilute solutions, this reduction proceeds through the UO 2 + ion. But interpretation of current-potential curves is made difficult by the dismutation reaction of the UO 2 ion and by the fact that the surface of the indicator electrode is not renewed. (author) [fr

  20. Square Wave Voltammetry: An Alternative Technique to Determinate Piroxicam Release Profiles from Nanostructured Lipid Carriers.

    Science.gov (United States)

    Otarola, Jessica; Garrido, Mariano; Correa, N Mariano; Molina, Patricia G

    2016-08-04

    A new, simple, and fast electrochemical (EC) method has been developed to determine the release profile of piroxicam, a nonsteroidal anti-inflammatory drug, loaded in a drug delivery system based on nanostructured lipid carriers (NLCs). For the first time, the samples were analyzed by using square wave voltammetry, a sensitive EC technique. The piroxicam EC responses allow us to propose a model that explains the experimental results and to subsequently determine the amount of drug loaded into the NLCs formulation as a function of time. In vitro drug release studies showed prolonged drug release (up to 5 days), releasing 60 % of the incorporated drug. The proposed method is a promising and stable alternative for the study of different drug delivery systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The qualitative determination of oseltamivir phosphate in Tamiflu® capsule by cyclic voltammetry

    Directory of Open Access Journals (Sweden)

    Avramov-Ivić Milka L.

    2011-01-01

    Full Text Available A gold electrode was applied in the voltammetric determination of oseltamivir phosphate standard in 0.05 M NaHCO3. Oseltamivir phosphate as a standard and as a component of Tamiflu® capsule exhibited the identical cyclic voltammogram. The peaks originated from excipients in capsule do not appear under the applied electrochemical conditions. The electrochemical method for the qualitative determination of oseltamivir phosphate in Tamiflu® capsule by cyclic voltammetry was developed. The presence of oseltamivir phosphate as standard and as a content of Tamiflu® capsule in electrolyte as well as their concentrations were simultaneously checked by HPLC. The lack of the current/concentration dependency was established. The not pretreated glassy carbon electrode cannot be used for the determination of oseltamivir phosphate under identical experimental conditions presented for gold electrode.

  2. Determination of the selenium (VI)/(IV) standard redox potential by cyclic voltammetry

    International Nuclear Information System (INIS)

    Doi, Reisuke

    2014-01-01

    An electrochemical investigation of selenium, using cyclic voltammetry, has been carried out to determine the standard redox potential of the following reaction: SeO 4 2- + 2H + + 2e - ⇌ SeO 3 2- + H 2 O. The Se(VI)/(IV) half-wave potentials were measured in alkaline sodium perchlorate solutions as a function of molality of a sodium ion. Extrapolation of the experimental data to the standard state using specific ion interaction theory yields the following standard redox potential and ion interaction coefficients: E 0 (SeO 4 2- /SeO 3 2- ) = 0.8227 ± 0.0032V vs. SHE, ε(SeO 4 2- , Na + ) - ε(SeO 3 2- , Na + ) = 0.59 ± 0.12 kg mole -1 . (author)

  3. Life assessment of PVD based hard coatings by linear sweep voltammetry for high performance industrial application

    International Nuclear Information System (INIS)

    Malik, M.; Alam, S.; Irfan, M.; Hassan, Z.

    2006-01-01

    PVD based hard coatings have remarkable achievements in order to improve Tribological and surface properties of coating tools and dies. As PVD based hard coatings have a wide range of industrial applications especially in aerospace and automobile parts where they met different chemical attacks and in order to improve industrial performance these coatings must provide an excellent resistance against corrosion, high temperature oxidation and chemical reaction. This paper focuses on study of behaviour of PVD based hard coatings under different corrosive environments like as H/sub 2/SO/sub 4/, HCl, NaCl, KCl, NaOH etc. Corrosion rate was calculate under linear sweep voltammetry method where the Tafel extrapolation curves used for continuously monitoring the corrosion rate. The results show that these coatings have an excellent resistance against chemical attack. (author)

  4. Analysis of nitroguanidine in aqueous solutions by HPLC (high performance liquid chromatography) with electrochemical detection and voltammetry: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Manning, D.L.; Maskarinec, M.P.

    1987-04-01

    This study was directed towards the analysis of nitroguanidine in aqueous solutions. Nitroguanidine, which is the strongest organic base known, is used in the manufacture of some explosives. A method based on reverse phase HPLC with reductive electrochemical detection was developed for the determination of low levels of nitroguanidine. The nitroguanidine can be concentrated in the aqueous solutions by rotary evaporation at 50/sup 0/C. If the samples are not too complex, the nitroguanidine can be measured directly by voltammetry. From voltammetry, it was established that nitroguanidine is reduced via an irreversible diffusion controlled four electron process. 15 refs., 2 figs., 3 tabs.

  5. Nonradical oxidation from electrochemical activation of peroxydisulfate at Ti/Pt anode: Efficiency, mechanism and influencing factors.

    Science.gov (United States)

    Song, Haoran; Yan, Linxia; Ma, Jun; Jiang, Jin; Cai, Guangqiang; Zhang, Wenjuan; Zhang, Zhongxiang; Zhang, Jiaming; Yang, Tao

    2017-06-01

    Electrochemical activation of peroxydisulfate (PDS) at Ti/Pt anode was systematically investigated for the first time in this work. The synergistic effect produced from the combination of electrolysis and the addition of PDS demonstrates that PDS can be activated at Ti/Pt anode. The selective oxidation towards carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), benzoic acid (BA) rather than atrazine (ATZ) and nitrobenzene (NB) was observed in electrochemical activation of PDS process. Moreover, addition of excess methanol or tert-butanol had negligible impact on CBZ (model compound) degradation, demonstrating that neither sulfate radical (SO 4 - ) nor hydroxyl radical (HO) was produced in electrochemical activation of PDS process. Direct oxidation (PDS oxidation alone and electrolysis) and nonradical oxidation were responsible for the degradation of contaminants. The results of linear sweep voltammetry (LSV) and chronoamperometry suggest that electric discharge may integrate PDS molecule with anode surface into a unique transition state structure, which is responsible for the nonradical oxidation in electrochemical activation of PDS process. Adjustment of the solution pH from 1.0 to 7.0 had negligible effect on CBZ degradation. Increase of either PDS concentration or current density facilitated the degradation of CBZ. The presence of chloride ion (Cl - ) significantly enhanced CBZ degradation, while addition of bicarbonate (HCO 3 - ), phosphate (PO 4 3- ) and humic acid (HA) all inhibited CBZ degradation with the order of HA > HCO 3 -  > PO 4 3- . The degradation products of CBZ and chlorinated products were also identified. Electrochemical activation of PDS at Ti/Pt anode may serve as a novel technology for selective oxidation of organic contaminants in water and soil. Copyright © 2017. Published by Elsevier Ltd.

  6. Anodic oxidation of Ta/Fe alloys

    International Nuclear Information System (INIS)

    Mato, S.; Alcala, G.; Thompson, G.E.; Skeldon, P.; Shimizu, K.; Habazaki, H.; Quance, T.; Graham, M.J.; Masheder, D.

    2003-01-01

    The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V -1 . Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface

  7. Study of the physical processes involved in the operating mode of the micro-strips gas detector Micromegas

    International Nuclear Information System (INIS)

    Barouch, G.

    2001-04-01

    Micromegas is a micro-strip gaseous detector invented in 1996. It consists of two volumes of gas separated by a micro-mesh. The first volume of gas, 3 mm thick, is used to liberate ionization electrons from the incident charged particle. In the second volume, only 100 μm thick, an avalanche phenomenon amplifies the electrons produced in the first volume. Strips printed on an insulating substrate collect the electrons from the avalanche. The geometrical configuration of Micromegas showed many advantages. The short anode-cathode distance combined with a high granularity provide high rate capabilities due to a fast collection of ions produced during the avalanche development. Moreover, the possibility to localize the avalanche with strips printed about every hundreds of micrometers allows to measure the position of the incident particle with a good resolution. In this work, experimental tests of Micromegas are presented along with detailed Monte Carlo simulations used to understand and optimize the detector's performances. The prototypes were tested several times at the PS accelerator at CERN. The analysis of the date showed a stable and efficient behavior of Micromegas combined with an excellent space resolution. In fact, spatial resolutions of less than 15 μm were obtained. In parallel with the in-beam tests, several simulations have been developed in order to gain a better understanding of the detector's response. (author)

  8. Task 1: Modeling Study of CO Effects on Polymer Electrolyte Fuel Cell Anodes Task 2: Study of Ac Impedance as Membrane/Electrode Manufacturing Diagnostic Tool

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Springer

    1998-01-30

    Carbon monoxide poisoning of polymer electrolyte fuel cell anodes is a key problem to be overcome when operating a polymer electrolyte fuel cell (PEFC) on reformed fuels. CO adsorbs preferentially on the precious metal surface leading to substantial performance losses. Some recent work has explored this problem, primarily using various Pt alloys in attempts to lower the degree of surface deactivation. In their studies of hydrogen oxidation on Pt and Pt alloy (Pt/Sn, Pt/Ru) rotating disk electrodes exposed to H{sub 2}/CO mixtures, Gasteiger et al. showed that a small hydrogen oxidation current is observed well before the onset of major CO oxidative stripping (ca. 0.4 V) on Pt/Ru. However, these workers concluded that such current observed at low anode overpotentials was too low to be of practical value. Nonetheless, MST-11 researchers and others have found experimentally that it is possible to run a PEFC, e.g., with a Pt/Ru anode, in the presence of CO levels in the range 10--100 ppm with little voltage loss. Such experimental results suggest that, in fact, PEFC operation at significant current densities under low anode overpotentials is possible in the presence of such levels of CO, even before resorting to air bleeding into the anode feed stream. The latter approach has been shown to be effective in elimination of Pt anode catalyst poisoning effects at CO levels of 20--50 ppm for cells operating at 80 C with low Pt catalyst loading. The effect of oxygen bleeding is basically to lower P{sub CO} down to extremely low levels in the anode plenum thanks to the catalytic (chemical) oxidation of CO by dioxygen at the anode catalyst. In this modeling work the authors do not include specific description of oxygen bleeding effects and concentrate on the behavior of the anode with feed streams of H{sub 2} or reformate containing low levels of CO. The anode loss is treated in this work as a hydrogen and carbon monoxide electrode kinetics problem, but includes the effects of

  9. An Insoluble Titanium-Lead Anode for Sulfate Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ferdman, Alla

    2005-05-11

    The project is devoted to the development of novel insoluble anodes for copper electrowinning and electrolytic manganese dioxide (EMD) production. The anodes are made of titanium-lead composite material produced by techniques of powder metallurgy, compaction of titanium powder, sintering and subsequent lead infiltration. The titanium-lead anode combines beneficial electrochemical behavior of a lead anode with high mechanical properties and corrosion resistance of a titanium anode. In the titanium-lead anode, the titanium stabilizes the lead, preventing it from spalling, and the lead sheathes the titanium, protecting it from passivation. Interconnections between manufacturing process, structure, composition and properties of the titanium-lead composite material were investigated. The material containing 20-30 vol.% of lead had optimal combination of mechanical and electrochemical properties. Optimal process parameters to manufacture the anodes were identified. Prototypes having optimized composition and structure were produced for testing in operating conditions of copper electrowinning and EMD production. Bench-scale, mini-pilot scale and pilot scale tests were performed. The test anodes were of both a plate design and a flow-through cylindrical design. The cylindrical anodes were composed of cylinders containing titanium inner rods and fitting over titanium-lead bushings. The cylindrical design allows the electrolyte to flow through the anode, which enhances diffusion of the electrolyte reactants. The cylindrical anodes demonstrate higher mass transport capabilities and increased electrical efficiency compared to the plate anodes. Copper electrowinning represents the primary target market for the titanium-lead anode. A full-size cylindrical anode performance in copper electrowinning conditions was monitored over a year. The test anode to cathode voltage was stable in the 1.8 to 2.0 volt range. Copper cathode morphology was very smooth and uniform. There was no

  10. Silicon Whisker and Carbon Nanofiber Composite Anode

    Science.gov (United States)

    Lang, Christopher M.

    2015-01-01

    Phase II Objectives: Demonstrate production levels of grams per batch; Achieve full cell anode capacity of greater than 1,000 mAh/g at a charge rate of 10 (C/10) and 0 degree C; Establish a full cell cycle life of over 300 cycles; Display an operating temperature of negative 30 degrees C to plus 30 degrees C; Demonstrate a rate capability of C/5 or higher; Deliver to NASA three 2.5 Ah cells (energy density greater than 220 Wh/kg); Exhibit the safety features of the anode and full cells; Design a 1 kWh prismatic battery pack.

  11. The effect of ethylene glycol on pore arrangement of anodic aluminium oxide prepared by hard anodization

    Science.gov (United States)

    Guo, Yang; Zhang, Li; Han, Mangui; Wang, Xin; Xie, Jianliang; Deng, Longjiang

    2018-03-01

    The influence of the addition of ethylene glycol (EG) on the pore self-ordering process in anodic aluminium oxide (AAO) membranes prepared by hard anodization (HA) was investigated. It was illustrated that EG has a substantial effect on the pore arrangement of AAO, and it was found that a smaller pore size can be obtained with an EG concentration reaching 20 wt% in aqueous electrolyte. The number of estimated defects of AAO increases significantly with an increase in EG concentration to 50 wt%. Excellent ordering of pores was realized when the samples were anodized in the 30 wt%-EG-containing aqueous electrolyte.

  12. Silicon Whisker and Carbon Nanofiber Composite Anode, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) proposes to develop a silicon whisker and carbon nanofiber composite anode for lithium ion batteries on a Phase I program. This anode...

  13. Ceria-Based Anodes for Next Generation Solid Oxide Fuel Cells

    Science.gov (United States)

    Mirfakhraei, Behzad

    Mixed ionic and electronic conducting materials (MIECs) have been suggested to represent the next generation of solid oxide fuel cell (SOFC) anodes, primarily due to their significantly enhanced active surface area and their tolerance to fuel components. In this thesis, the main focus has been on determining and tuning the physicochemical and electrochemical properties of ceria-based MIECs in the versatile perovskite or fluorite crystal structures. In one direction, BaZr0.1Ce0.7Y0.1 M0.1O3-delta (M = Fe, Ni, Co and Yb) (BZCY-M) perovskites were synthesized using solid-state or wet citric acid combustion methods and the effect of various transition metal dopants on the sintering behavior, crystal structure, chemical stability under CO2 and H 2S, and electrical conductivity, was investigated. BZCY-Ni, synthesized using the wet combustion method, was the best performing anode, giving a polarization resistance (RP) of 0.4 O.cm2 at 800 °C. Scanning electron microscopy and X-ray diffraction analysis showed that this was due to the exsolution of catalytic Ni nanoparticles onto the oxide surface. Evolving from this promising result, the effect of Mo-doped CeO 2 (nCMO) or Ni nanoparticle infiltration into a porous Gd-doped CeO 2 (GDC) anode (in the fluorite structure) was studied. While 3 wt. % Ni infiltration lowered RP by up to 90 %, giving 0.09 O.cm2 at 800 °C and exhibiting a ca. 5 times higher tolerance towards 10 ppm H2, nCMO infiltration enhanced the H2 stability by ca. 3 times, but had no influence on RP. In parallel work, a first-time study of the Ce3+ and Ce 4+ redox process (pseudocapacitance) within GDC anode materials was carried out using cyclic voltammetry (CV) in wet H2 at high temperatures. It was concluded that, at 500-600 °C, the Ce3+/Ce 4+ reaction is diffusion controlled, probably due to O2- transport limitations in the outer 5-10 layers of the GDC particles, giving a very high capacitance of ca. 70 F/g. Increasing the temperature ultimately

  14. Silicon-Based Anode and Method for Manufacturing the Same

    Science.gov (United States)

    Yushin, Gleb Nikolayevich (Inventor); Luzinov, Igor (Inventor); Zdyrko, Bogdan (Inventor); Magasinski, Alexandre (Inventor)

    2017-01-01

    A silicon-based anode comprising silicon, a carbon coating that coats the surface of the silicon, a polyvinyl acid that binds to at least a portion of the silicon, and vinylene carbonate that seals the interface between the silicon and the polyvinyl acid. Because of its properties, polyvinyl acid binders offer improved anode stability, tunable properties, and many other attractive attributes for silicon-based anodes, which enable the anode to withstand silicon cycles of expansion and contraction during charging and discharging.

  15. Theory of Square-Wave Voltammetry of Two-Step Electrode Reaction Using an Inverse Scan Direction

    OpenAIRE

    Lovrić, Milivoj; Komorsky-Lovrić, Šebojka

    2011-01-01

    A theory of square-wave voltammetry of two-step electrode reaction with kinetically controlled electron transfers is developed, and a special case of thermodynamically unstable intermediate is analyzed. If the first reaction step is reversible and the second one is quasireversible, the response splits into two peaks if the scan direction is inverted. The separation of these peaks increases with frequency.

  16. Voltammetry of Lead Cations on a New Type of Silver Composite Electrode in the Presence of Other Cations

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Šebková, Světlana; Kopanica, M.

    2004-01-01

    Roč. 379, - (2004), s. 294-301 ISSN 1618-2642 Grant - others:GIT(AR) 101/02/U111/CZ Institutional research plan: CEZ:AV0Z4040901 Keywords : voltammetry * silver composite electrode * lead cations Subject RIV: CG - Electrochemistry Impact factor: 2.098, year: 2004

  17. Analysis of low concentration of free ferric oxides in clays by vis diffuse reflectance spectroscopy and voltammetry

    Czech Academy of Sciences Publication Activity Database

    Grygar, Tomáš; Dědeček, Jiří; Hradil, David

    2002-01-01

    Roč. 53, č. 2 (2002), s. 71-77 ISSN 0016-7738 R&D Projects: GA ČR GA205/00/1349 Institutional research plan: CEZ:AV0Z4032918 Keywords : voltammetry * Vis spectroscopy * analysis Subject RIV: CA - Inorganic Chemistry

  18. Catalytic monolayer voltammetry and in situ scanning tunneling microscopy of copper nitrite reductase on cysteamine-modified Au(111) electrodes

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Welinder, A.C.; Hansen, Allan Glargaard

    2003-01-01

    We have studied the adsorption and electrocatalysis of the redox metalloenzyme blue copper nitrite reductase from Achromobacter xylosoxidans (AxCuNiR) on single-crystal Au(111)-electrode surfaces modified by a self-assembled monolayer of cysteamine. A combination of cyclic voltammetry and in situ...

  19. Cathode Readout with Stripped Resistive Drift Tubes

    International Nuclear Information System (INIS)

    Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhil'tsov, V.E.

    1994-01-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with carbon layer of resistivity 0.5, 30 and 70 k Ohm/sq. The gas mixture used was Ar/CH 4 . Both the anode wire and cathode signals were detected in order to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. 7 refs., 11 figs., 1 tab

  20. 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.

  1. The CMS Si-Strip Tracker

    CERN Document Server

    Sguazzoni, Giacomo

    2004-01-01

    The Compact Muon Solenoid (CMS) experiment at LHC features the largest Silicon Strip Tracker (SST) ever build. This device is immersed in a 4T magnetic field and, in conjunction with a Pixel system, it allows the momentum of the charged particles to be measured and the heavy-flavour final states to be tagged despite the hostile radiation environment. The impact of operating conditions and physics requirements on the SST layout and design choices is discussed and the expected performances are reviewed. The SST collaboration is now facing the production of the ~15000 modules and their assembly into the SST substructures. A status is given.

  2. The CMS Si-strip Tracker

    CERN Document Server

    Sguazzoni, Giacomo

    2004-01-01

    The Compact Muon Solenoid (CMS) experiment at LHC features the largest Silicon Strip Tracker (SST) ever build. This device is immersed in a 4T magnetic field and, in conjunction with a Pixel system, it allows the momentum of the charged particles to be measured and the heavy-flavour final states to be tagged despite the hostile radiation environment. The impact of operating conditions and physics requirements on the SST layout and design choices is discussed and the expected performances are reviewed. The SST collaboration is now facing the production of the ~15000 modules and their assembly into the SST substructures. A status is given.

  3. Tritium stripping by a catalytic exchange stripper

    International Nuclear Information System (INIS)

    Heung, L.K.; Gibson, G.W.; Ortman, M.S.

    1991-01-01

    A catalytic exchange process for stripping elemental tritium from gas streams has been demonstrated. The process uses a catalyzed isotopic exchange reaction between tritium in the gas phase and protium or deuterium in the solid phase on alumina. The reaction is catalyzed by platinum deposited on the alumina. The process has been tested with both tritium and deuterium. Decontamination factors (ration of inlet and outlet tritium concentrations) as high as 1000 have been achieved, depending on inlet concentration. The test results and some demonstrated applications are presented

  4. Hollow Anode Cascading Plasma Focus | Alabraba | Journal of the ...

    African Journals Online (AJOL)

    Using the 3-phase model for each focus event, the 9-phase, two solid disc auxiliary anode cascading plasma focus has been extended to include holes at the center of each cascade anode (hereafter referred to as hollow anode cascading focus) with a view of increasing the neutron yield with each focus event. Results ...

  5. Anode heat transfer in a constricted tube arc.

    Science.gov (United States)

    Lukens, L. A.; Incropera, F. P.

    1971-01-01

    The complex energy exchange mechanisms occurring on the most severely heated component of an arc constrictor, the anode, have been investigated. Measurements performed to determine the anode heat flux for a cascade, atmospheric argon arc of the Maecker type are described. The results are used to check the validity of an existing anode heat transfer model.

  6. Anodization of Aluminium using a fast two-step process

    Indian Academy of Sciences (India)

    the electrolyte for the first anodization to form pits on. Al substrate, while in second anodization these pits act as the pattern for nanopore formation.26 Nanoporous alumina is used in the development of thermoelectric devices using metamaterials and for energy harvest- ing. Anodized magnetic nanohole arrays are used in.

  7. Comparative study of corneal strip extensometry and inflation tests

    OpenAIRE

    Elsheikh, Ahmed; Anderson, Kevin

    2005-01-01

    Strip extensometry tests are usually considered less reliable than trephinate inflation tests in studying corneal biomechanics. In spite of the evident simplicity of strip extensometry tests, several earlier studies preferred inflation tests in determining the constitutive relationship of the cornea and its other material properties, such as Young's modulus and the hysteresis behaviour. In this research, the deficiencies of the strip tests are discussed and a mathematical procedure presented ...

  8. DEVELOPMENT OF DEFORMATION STRIPS WHILE STRETCHING OF CYLINDRICAL SAMPLES

    Directory of Open Access Journals (Sweden)

    Y. V. Vasilevich

    2011-01-01

    Full Text Available Deformation strips have been experimentally revealed and described while stretching of cylindrical samples by means of computer thermography. It has been established that temperature of shift strip surface grows smoothly up to the stage of crack origin in material defect. Sharp growth of surface temperature occurs when tensile stresses reach tensile strength. Change in surface temperature occurs wavy after destruction (while cooling the sample. Processes of material destruction origin and development  characterize temperature changes in deformation strips.

  9. An integrated electrochemical device based on immunochromatographic test strip and enzyme labels for sensitive detection of disease-related biomarkers.

    Science.gov (United States)

    Zou, Zhe-Xiang; Wang, Jun; Wang, Hua; Li, Yao-Qun; Lin, Yuehe

    2012-05-30

    A novel electrochemical biosensing device that integrates an immunochromatographic test strip and a screen-printed electrode (SPE) connected to a portable electrochemical analyzer was presented for rapid, sensitive, and quantitative detection of disease-related biomarker in human blood samples. The principle of the sensor is based on sandwich immunoreactions between a biomarker and a pair of its antibodies on the test strip, followed by highly sensitive square-wave voltammetry (SWV) detection. Horseradish peroxidase (HRP) was used as a signal reporter for electrochemical readout. Hepatitis B surface antigen (HBsAg) was employed as a model protein biomarker to demonstrate the analytical performance of the sensor in this study. Some critical parameters governing the performance of the sensor were investigated in detail. Under optimal conditions, this sensor was capable of detecting a minimum of 0.3 ng mL(-1) (S/N=3) HBsAg with a wide linear concentration range from 1 to 500 ng mL(-1). The sensor was further utilized to detect HBsAg spiked in human plasma with an average recovery of 91.3%. In comparison, a colorimetric immunochromatographic test strip assay (ITSA) was also conducted. The result shows that the SWV detection in the electrochemical sensor is much more sensitive for the quantitative determination of HBsAg than the colorimetric detection, indicating that such a sensor is a promising platform for rapid and sensitive point-of-care testing/screening of disease-related biomarkers in a large population. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Silicon Whisker and Carbon Nanofiber Composite Anode

    Science.gov (United States)

    Ma, Junqing (Inventor); Newman, Aron (Inventor); Lennhoff, John (Inventor)

    2015-01-01

    A carbon nanofiber can have a surface and include at least one crystalline whisker extending from the surface of the carbon nanofiber. A battery anode composition can be formed from a plurality of carbon nanofibers each including a plurality of crystalline whiskers.

  11. Growth of anodic films on niobium

    International Nuclear Information System (INIS)

    Gomes, M.A.B.; Bulhoes, L.O.S.

    1988-01-01

    The analysis of the response of the galvanostatic growth of anodic films on niobium metal in aqueous solutions is shown. The first spark voltage showed a dependence upon value of current density that could be explained as the incorporation of anions into the film. (M.J.C.) [pt

  12. Anode materials for lithium-ion batteries

    Science.gov (United States)

    Sunkara, Mahendra Kumar; Meduri, Praveen; Sumanasekera, Gamini

    2014-12-30

    An anode material for lithium-ion batteries is provided that comprises an elongated core structure capable of forming an alloy with lithium; and a plurality of nanostructures placed on a surface of the core structure, with each nanostructure being capable of forming an alloy with lithium and spaced at a predetermined distance from adjacent nanostructures.

  13. Hybrid anode for semiconductor radiation detectors

    Science.gov (United States)

    Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

    2013-11-19

    The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

  14. Characterization of nanopores ordering in anodic alumina

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.; Piraux, L.

    2008-01-01

    A simple characterization method of the ordering of the nanopores is described for nanoporous anodized aluminium oxides. The method starts with image analysis on scanning electron microscopy representations for the purpose to find repetitive shapes and their centres, i.e. nanopores. Then triangles...

  15. Stability of barotropic vortex strip on a rotating sphere.

    Science.gov (United States)

    Sohn, Sung-Ik; Sakajo, Takashi; Kim, Sun-Chul

    2018-02-01

    We study the stability of a barotropic vortex strip on a rotating sphere, as a simple model of jet streams. The flow is approximated by a piecewise-continuous vorticity distribution by zonal bands of uniform vorticity. The linear stability analysis shows that the vortex strip becomes stable as the strip widens or the rotation speed increases. When the vorticity constants in the upper and the lower regions of the vortex strip have the same positive value, the inner flow region of the vortex strip becomes the most unstable. However, when the upper and the lower vorticity constants in the polar regions have different signs, a complex pattern of instability is found, depending on the wavenumber of perturbations, and interestingly, a boundary far away from the vortex strip can be unstable. We also compute the nonlinear evolution of the vortex strip on the rotating sphere and compare with the linear stability analysis. When the width of the vortex strip is small, we observe a good agreement in the growth rate of perturbation at an early time, and the eigenvector corresponding to the unstable eigenvalue coincides with the most unstable part of the flow. We demonstrate that a large structure of rolling-up vortex cores appears in the vortex strip after a long-time evolution. Furthermore, the geophysical relevance of the model to jet streams of Jupiter, Saturn and Earth is examined.

  16. Strip type radiation detector and method of making same

    International Nuclear Information System (INIS)

    Jantsch, O.; Feigt, I.; Willig, W.R.

    1976-01-01

    An improved strip detector and a method for making such a detector in which a high resistivity N conduction semiconductor body has electrode strips formed thereon by diffusion is described. The strips are formed so as to be covered by an oxide layer at the surface point of the PN junction and in which the opposite side of the semiconductor body then has a substantial amount of material etched away to form a thin semiconductor upon which strip electrodes which are perpendicular to the electrodes on the first side are then placed

  17. Strip defect recognition in electrical tests of silicon microstrip sensors

    Energy Technology Data Exchange (ETDEWEB)

    Valentan, Manfred, E-mail: valentan@mpp.mpg.de

    2017-02-11

    This contribution describes the measurement procedure and data analysis of AC-coupled double-sided silicon microstrip sensors with polysilicon resistor biasing. The most thorough test of a strip sensor is an electrical measurement of all strips of the sensor; the measured observables include e.g. the strip's current and the coupling capacitance. These measurements are performed to find defective strips, e.g. broken capacitors (pinholes) or implant shorts between two adjacent strips. When a strip has a defect, its observables will show a deviation from the “typical value”. To recognize and quantify certain defects, it is necessary to determine these typical values, i.e. the values the observables would have without the defect. As a novel approach, local least-median-of-squares linear fits are applied to determine these “would-be” values of the observables. A least-median-of-squares fit is robust against outliers, i.e. it ignores the observable values of defective strips. Knowing the typical values allows to recognize, distinguish and quantify a whole range of strip defects. This contribution explains how the various defects appear in the data and in which order the defects can be recognized. The method has been used to find strip defects on 30 double-sided trapezoidal microstrip sensors for the Belle II Silicon Vertex Detector, which have been measured at the Institute of High Energy Physics, Vienna (Austria).

  18. Stability of barotropic vortex strip on a rotating sphere

    Science.gov (United States)

    Sohn, Sung-Ik; Sakajo, Takashi; Kim, Sun-Chul

    2018-02-01

    We study the stability of a barotropic vortex strip on a rotating sphere, as a simple model of jet streams. The flow is approximated by a piecewise-continuous vorticity distribution by zonal bands of uniform vorticity. The linear stability analysis shows that the vortex strip becomes stable as the strip widens or the rotation speed increases. When the vorticity constants in the upper and the lower regions of the vortex strip have the same positive value, the inner flow region of the vortex strip becomes the most unstable. However, when the upper and the lower vorticity constants in the polar regions have different signs, a complex pattern of instability is found, depending on the wavenumber of perturbations, and interestingly, a boundary far away from the vortex strip can be unstable. We also compute the nonlinear evolution of the vortex strip on the rotating sphere and compare with the linear stability analysis. When the width of the vortex strip is small, we observe a good agreement in the growth rate of perturbation at an early time, and the eigenvector corresponding to the unstable eigenvalue coincides with the most unstable part of the flow. We demonstrate that a large structure of rolling-up vortex cores appears in the vortex strip after a long-time evolution. Furthermore, the geophysical relevance of the model to jet streams of Jupiter, Saturn and Earth is examined.

  19. Pavement Stripping in Saudi Arabia: Prediction and Prevention

    Directory of Open Access Journals (Sweden)

    H.I. Al-Abdul Wahhab

    2004-12-01

    Full Text Available Pavement weathering or stripping is a major distress in highway networks in arid regions. Using the Saudi Arabian road network as a case study area, seventeen road test sections were selected, out of which eight were stripped and nine were non-stripped. Aggregates from quarries used to build these sections were also collected and subjected to detailed physical and chemical tests to evaluate the ability of these tests to distinguish between stripped and non-stripped sections. The modified Lottman test was used to distinguish between compacted mixes. In addition, the Swedish Rolling Bottle test, was also found to be effective in being able to distinguish between different asphalt-aggregates for stripping potential. Eleven anti-stripping liquid additives, lime and cement, in addition to two polymers, were evaluated for their ability to reduce/eliminate stripping potential of stripping-prone aggregates. It was found that EE-2 Polymer, Portland cement, and their combination were effective with all aggregate sources.

  20. Voltammetry and single-molecule in situ scanning tunneling microscopy of laccases and bilirubin oxidase in electrocatalytic dioxygen reduction on Au(111) single-crystal electrodes

    DEFF Research Database (Denmark)

    Climent, Victor; Zhang, Jingdong; Friis, Esben Peter

    2012-01-01

    to elucidate the catalytic mechanism, where laccase (sub)monolayer voltammetry has been a core approach. In this report, we address voltammetry and electrocatalysis of O2 reduction of (sub)monolayers of several laccases in new ways. These are based on the use of single-crystal, atomically planar bare Au(111...

  1. Quantitative relationship between nanotube length and anodizing current during constant current anodization

    International Nuclear Information System (INIS)

    Zhang, Yulian; Cheng, Weijie; Du, Fei; Zhang, Shaoyu; Ma, Weihua; Li, Dongdong; Song, Ye; Zhu, Xufei

    2015-01-01

    Highlights: • Ti anodization was performed by constant current rather than constant voltage. • The nanotube length was controlled by ionic current rather than dissolution current. • Electronic current can be estimated by the nanotube length and the anodizing current. • Dissolution reaction hardly contributes electric current across the barrier layer. - Abstract: The growth kinetics of anodic TiO 2 nanotubes (ATNTs) still remains unclear. ATNTs are generally fabricated under potentiostatic conditions rather than galvanostatic ones. The quantitative relationship between nanotube length and anodizing current (J total ) is difficult to determine, because the variable J total includes ionic current (J ion ) (also called oxide growth current J grow =J ion ) and electronic current (J e ), which cannot be separated from each other. One successful approach to achieve this objective is to use constant current anodization rather than constant voltage anodization, that is, through quantitative comparison between the nanotube length and the known J total during constant current anodization, we can estimate the relative magnitudes of J grow and J e . The nanotubes with lengths of 1.24, 2.23, 3.51 and 4.70 μm, were formed under constant currents (J total ) of 15, 20, 25 and 30 mA, respectively. The relationship between nanotube length (y) and anodizing current (x =J total =J grow +J e ) can be expressed by a fitting equation: y=0.23(x-10.13), from which J grow (J grow = x -10.13) and J e (∼10.13 mA) could be inferred under the present conditions. Meanwhile, the same conclusion could also be deduced from the oxide volume data. These results indicate that the nanotube growth is attributed to the oxide growth current rather than the dissolution current.

  2. Solute diffusion through stripped mouse duodenum.

    Science.gov (United States)

    Takeuchi, T; Ham, M; Mizumori, M; Guth, P H; Engel, E; Kaunitz, J D; Akiba, Y

    2007-12-01

    We measured villous cell intracellular pH (pH(i)) and solute diffusion between the bathing media and the epithelial cells in stripped, chambered mouse duodenum. Apical perfusion of a high CO2 solution rapidly acidified the upper villous cells with recovery after its removal. Apical zoniporide (ZP) enhanced CO(2)-induced acidification. Serosal ZP, dimethylamiloride (DMA) or stilbene anion transport inhibitors failed to alter CO(2)-induced acidification, whereas serosal high CO(2) buffer acidified the upper villous cells. Serosal 5-hydroxytryptamine rapidly acidified the upper villous cells. All serosally-perfused fluorescent compounds stained the crypt area, but not the villi or villous cells. In contrast, intravenous carboxyfluorescein quickly diffused into the interstitial space of the entire mucosa, and mucosally perfused fluorescent compound rapidly penetrated the epithelial cell layer. In muscle-stripped duodenum mounted in a small-aperture perfusion chamber, serosal solutes can readily diffuse only to the crypt cell region, whereas access to the villous epithelial cells is diffusion-limited. In contrast, rapid villous cell responses to serosally applied solutes are best explained by neural reflexes. Limited viability of the villous cells and impaired structural stability of the villi further limit long-term, villous cell functional studies of mucosal preparations mounted in small aperture diffusion chambers.

  3. Evaluation of silicon micro strip detectors with large read-out pitch

    International Nuclear Information System (INIS)

    Senyo, K.; Yamamura, K.; Tsuboyama, T.; Avrillon, S.; Asano, Y.; Bozek, A.; Natkaniec, Z.; Palka, H.; Rozanska, M.; Rybicki, K.

    1996-01-01

    For the development of the silicon micro-strip detector with the pitch of the readout strips as large as 250 μm on the ohmic side, we made samples with different structures. Charge collection was evaluated to optimize the width of implant strips, aluminum read-out strips, and/or the read-out scheme among strips. (orig.)

  4. Cyclic Voltammetry Based Solid State Gas Sensor for Methane and Other VOCs Detection.

    Science.gov (United States)

    Gross, Pierre-Alexandre; Jaramillo, Thomas F; Pruitt, Beth L

    2018-04-12

    We present the fabrication, characterization, and testing of an electrochemical Volatile Organic Compound (VOC) sensor operating in gaseous condition at room temperature. It is designed to be microfabricated to prove the sensing principle based on Cyclic Voltammetry (CVs). It is composed of a Working Electrode (WE), a Counter Electrode (CE), a Reference Electrode (RE) and a Nafion solid-state electrolyte. Nafion is a polymer that conducts protons (H + ) generated from redox reactions from the WE to the CE. The sensor needs to be activated prior to exposure to gases, which consists of hydrating the Nafion layer to enable its ion conduction properties. During testing, we have shown that our sensor is not only capable of detecting methane, but it can also quantify its concentration in the gas flow as well as differentiate its signal from carbon monoxide (CO). These results have been confirmed by exposing the sensor to two different concentrations of methane (50% and 10% of methane diluted in N 2 ), as well as pure CO. Although the signal is positioned in the H ads region of Pt, because of thermodynamic reasons it cannot be directly attributed to methane oxidation into CO 2 . However, its consistency suggests the presence of a methane related oxidation process that can be used for detection, identification, and quantification purposes.

  5. Nanostructured platform for the detection of Neisseria gonorrhoeae using electrochemical impedance spectroscopy and differential pulse voltammetry

    International Nuclear Information System (INIS)

    Singh, R.; Matharu, Z.; Srivastava, A.K.; Sood, S.; Gupta, R.K.; Malhotra, B.D.

    2012-01-01

    We report on a nanocomposite based genosensor for the detection of Neisseria gonorrhoeae, a bacterium causing the sexually transmitted disease gonorrhoea. Amino-labeled probe DNA was covalently immobilized on electrochemically prepared polyaniline and iron oxide (PANI-Fe 3 O 4 ) nanocomposite film on an indium tin oxide (ITO) electrode. Scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) techniques have been employed to characterize surface of the modified electrode. The genosensor has detection limits of 1 x 10 -15 M and 1 x 10 -17 M, respectively, using the EIS and DPV techniques. This biosensor can discriminate a complementary sequence from a single-base mismatch and from non-complementary DNA, and has been utilized for detection of DNA extracted from N. gonorrhoeae culture, and from patient samples with N. gonorrhoeae. It is found to exhibit good specificity for N. gonorrhoeae species and shows no response towards non-gonorrhoeae type of Neisseria species (NgNs) and other gram-negative bacterias (GNBs). The affinity constant for hybridization calculated using the Langmuir adsorption isotherm model is found to be 3. 39 x 10 8 M -1 . (author)

  6. Cyclic voltammetry, spectroelectrochemistry and electron spin resonance as combined tools to study thymoquinone in aprotic medium

    International Nuclear Information System (INIS)

    Petrucci, Rita; Marrosu, Giancarlo; Astolfi, Paola; Lupidi, Giulio; Greci, Lucedio

    2012-01-01

    Nigella sativa has been used for centuries as a natural remedy for a number of chronic and age-related diseases. Thymoquinone (TQ), the main constituent of its extracts, has recently received particular attention and has been tested for its antioxidant, anti-inflammatory and anticancer properties. To further investigate the mechanisms involved in the biological activities of this natural quinone and, among these, in its antioxidant properties, the redox-system of TQ and its interaction with superoxide was studied in aprotic medium by cyclic voltammetry, spectroelectrochemistry and Electron Spin Resonance (ESR). The electrochemical behavior of dithymoquinone (DTQ), the photodimer of TQ, was also studied in the same medium. Experimental data evidenced the formation of the radical anion TQ· − by cathodic reduction of TQ at potential values very close to coenzymes Q ones, by electron transfer (ET) between TQ and superoxide, as KO 2 or electrogenerated, by chemical comproportionation between TQ and the dianion TQ −− and by fast cleavage of the electrogenerated radical anion DTQ· − . Spectroelectrochemical data evidenced that TQ· − , in the presence of TQ, evolves to the hydroquinone monoanion TQH − , suggesting that an H-atom transfer (HT) may occur, likely from the isopropylic side-chain of TQ to TQ· − The H-atom donating ability of TQ may be also supported by Bond Dissociation Energy values and ESR data.

  7. Impact of Adsorption on Scanning Electrochemical Microscopy Voltammetry and Implications for Nanogap Measurements.

    Science.gov (United States)

    Tan, Sze-yin; Zhang, Jie; Bond, Alan M; Macpherson, Julie V; Unwin, Patrick R

    2016-03-15

    Scanning electrochemical microscopy (SECM) is a powerful tool that enables quantitative measurements of fast electron transfer (ET) kinetics when coupled with modeling predictions from finite-element simulations. However, the advent of nanoscale and nanogap electrode geometries that have an intrinsically high surface area-to-solution volume ratio realizes the need for more rigorous data analysis procedures, as surface effects such as adsorption may play an important role. The oxidation of ferrocenylmethyl trimethylammonium (FcTMA(+)) at highly oriented pyrolytic graphite (HOPG) is used as a model system to demonstrate the effects of reversible reactant adsorption on the SECM response. Furthermore, the adsorption of FcTMA(2+) species onto glass, which is often used to encapsulate ultramicroelectrodes employed in SECM, is also found to be important and affects the voltammetric tip response in a nanogap geometry. If a researcher is unaware of such effects (which may not be readily apparent in slow to moderate scan voltammetry) and analyzes SECM data assuming simple ET kinetics at the substrate and an inert insulator support around the tip, the result is the incorrect assignment of tip-substrate heights, kinetics, and thermodynamic parameters. Thus, SECM kinetic measurements, particularly in a nanogap configuration where the ET kinetics are often very fast (only just distinguishable from reversible), require that such effects are fully characterized. This is possible by expanding the number of experimental variables, including the voltammetric scan rate and concentration of redox species, among others.

  8. Penentuan Unsur Tanah Jarang Kelompok Sedang secara Voltammetri Pindai Linier Menggunakan Elektrode Grafit Pensil

    Directory of Open Access Journals (Sweden)

    Yeni Wahyuni Hartati

    2016-01-01

    Full Text Available Rare earth elements play an important role in a variety of applications, mostly for high-tech industries. But their presence in mineral jointly separation makes it difficult to determine the content of rare earths because each element has physical and chemical properties are almost identical. The purpose of this study is the use of a linear scan voltammetry method to study the electrochemical characteristics of the medium rare earth element group (Sm, Gd, Eu, Tb, as an alternative method of separation and analysis of rare earth elements. The electrode used is a graphite pencil electrodes without modification, with a variety of supporting electrolyte. The results obtained show some supporting electrolyte provides good reduction peak for gadolinium, compared to the peaks of the reduction potential of the single rare earth ions other. The potential range of the most well using pencil graphite electrode obtained at 0.50 V to -1.00 V. Analysis of single gadolinium provide linear regression equation in a concentration range of 4.0 to 10.0 mg/L by the equation Y = 0.9862 X + 0.828 with R2 = 0.9954. The limit of detection is determined from the linear regression obtained 0.72 mg / L.

  9. Electrode calibration with a microfluidic flow cell for fast-scan cyclic voltammetry.

    Science.gov (United States)

    Sinkala, Elly; McCutcheon, James E; Schuck, Matthew J; Schmidt, Eric; Roitman, Mitchell F; Eddington, David T

    2012-07-07

    Fast-scan cyclic voltammetry (FSCV) is a common analytical electrochemistry tool used to measure chemical species. It has recently been adapted for measurement of neurotransmitters such as dopamine in awake and behaving animals (in vivo). Electrode calibration is an essential step in FSCV to relate observed current to concentration of a chemical species. However, existing methods require multiple components, which reduce the ease of calibrations. To this end, a microfluidic flow cell (μFC) was developed as a simple device to switch between buffer and buffer with a known concentration of the analyte of interest--in this case dopamine--in a microfluidic Y-channel. The ability to quickly switch solutions yielded electrode calibrations with faster rise times and that were more stable at peak current values. The μFC reduced the number of external electrical components and produced linear calibrations over a range of concentrations. To demonstrate this, an electrode calibrated with the μFC was used in FSCV recordings from a rat during the delivery of food reward--a stimulus that reliably evokes a brief increase in current due to the oxidation of dopamine. Using the linear calibration, dopamine concentrations were determined from the current responses evoked during the behavioral task. The μFC is able to easily and quickly calibrate FSCV electrode responses to chemical species for both in vitro and in vivo experiments.

  10. Portable Chronic Alcohol Consumption Monitor in Human Sweat through Square-Wave Voltammetry.

    Science.gov (United States)

    Kinnamon, David; Muthukumar, Sriram; Panneer Selvam, Anjan; Prasad, Shalini

    2017-09-01

    Chronic alcohol consumption is a significant financial and physical burden in the United States each year. Alcohol consumption monitors focus on establishing a state of intoxication, not assessing a user's health risks as a function of consumed alcohol. This work demonstrates a biosensor for a chronic alcohol consumption monitor through the electrochemical detection of ethyl glucuronide (EtG) in human sweat using square-wave voltammetry (SWV). A novel affinity assay was demonstrated in which monoclonal antibodies were chemically coabsorbed onto a gold electrode surface in parallel with thiolated charge transfer molecule. Concentration-dependent EtG binding was detected by measuring a reduction in the charge transfer of the sensor, manifesting as a current response during SWV measurement. A companion compact electronic reader was constructed, demonstrating comparable sensitivity to a conventional lab instrument. Both tools demonstrated a limit of detection of 0.1 µg/L and a linear dynamic range of 0.1-100 µg/L corresponding to the physiologically relevant range of EtG expression in human sweat. This device can address the need for a chronic alcohol consumption monitor toward establishing a user's long-term consumption habits to assess the risk of developing specific diseases and conditions associated with regular alcohol consumption, through integration with existing technologies.

  11. Tracking degradation in lithium iron phosphate batteries using differential thermal voltammetry

    Science.gov (United States)

    Shibagaki, Toshio; Merla, Yu; Offer, Gregory J.

    2018-01-01

    Diagnosing the state-of-health of lithium ion batteries in-operando is becoming increasingly important for multiple applications. We report the application of differential thermal voltammetry (DTV) to lithium iron phosphate (LFP) cells for the first time, and demonstrate that the technique is capable of diagnosing degradation in a similar way to incremental capacity analysis (ICA). DTV has the advantage of not requiring current and works for multiple cells in parallel, and is less sensitive to temperature introducing errors. Cells were aged by holding at 100% SOC or cycling at 1C charge, 6D discharge, both at an elevated temperature of 45 °C under forced air convection. Cells were periodically characterised, measuring capacity fade, resistance increase (power fade), and DTV fingerprints. The DTV results for both cells correlated well with both capacity and power, suggesting they could be used to diagnose SOH in-operando for both charge and discharge. The DTV peak-to-peak capacity correlated well with total capacity fade for the cycled cell, suggesting that it should be possible to estimate SOC and SOH from DTV for incomplete cycles within the voltage hysteresis region of an LFP cell.

  12. Cyclic voltammetry study of PEO processing of porous Ti and resulting coatings

    Science.gov (United States)

    Shbeh, Mohammed; Yerokhin, Aleksey; Goodall, Russell

    2018-05-01

    Ti is one of the most commonly used materials for biomedical applications. However, there are two issues associated with the use of it, namely its bio-inertness and high elastic modulus compared to the elastic modulus of the natural bone. Both of these hurdles could potentially be overcome by introducing a number of pores in the structure of the Ti implant to match the properties of the bone as well as improve the mechanical integration between the bone and implant, and subsequently coating it with a biologically active ceramic coating to promote chemical integration. Hence, in this study we investigated the usage of cyclic voltammetry in PEO treatment of porous Ti parts with different amount of porosity produced by both Metal Injection Moulding (MIM) and MIM in combination with a space holder. It was found that porous samples with higher porosity and open pores develop much thicker surface layers that penetrate through the inner structure of the samples forming a network of surface and subsurface coatings. The results are of potential benefit in producing surface engineered porous samples for biomedical applications which do not only address the stress shielding problem, but also improve the chemical integration.

  13. Mechanistic Insight into the Stability of HfO2-Coated MoS2 Nanosheet Anodes for Sodium Ion Batteries

    KAUST Repository

    Ahmed, Bilal

    2015-06-01

    It is demonstrated for the first time that surface passivation of 2D nanosheets of MoS2 by an ultrathin and uniform layer of HfO2 can significantly improve the cyclic performance of sodium ion batteries. After 50 charge/discharge cycles, bare MoS2 and HfO2 coated MoS2 electrodes deliver the specific capacity of 435 and 636 mAh g-1, respectively, at current density of 100 mA g-1. These results imply that batteries using HfO2 coated MoS2 anodes retain 91% of the initial capacity; in contrast, bare MoS2 anodes retain only 63%. Also, HfO2 coated MoS2 anodes show one of the highest reported capacity values for MoS2. Cyclic voltammetry and X-ray photoelectron spectroscopy results suggest that HfO2 does not take part in electrochemical reaction. The mechanism of capacity retention with HfO2 coating is explained by ex situ transmission electron microscope imaging and electrical impedance spectroscopy. It is illustrated that HfO2 acts as a passivation layer at the anode/electrolyte interface and prevents structural degradation during charge/discharge process. Moreover, the amorphous nature of HfO2 allows facile diffusion of Na ions. These results clearly show the potential of HfO2 coated MoS2 anodes, which performance is significantly higher than previous reports where bulk MoS2 or composites of MoS2 with carbonaceous materials are used. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Quasi–solid state rechargeable Na-CO2 batteries with reduced graphene oxide Na anodes

    Science.gov (United States)

    Hu, Xiaofei; Li, Zifan; Zhao, Yaran; Sun, Jianchao; Zhao, Qing; Wang, Jianbin; Tao, Zhanliang; Chen, Jun

    2017-01-01

    Na-CO2 batteries using earth-abundant Na and greenhouse gas CO2 are promising tools for mobile and stationary energy storage, but they still pose safety risks from leakage of liquid electrolyte and instability of the Na metal anode. These issues result in extremely harsh operating conditions of Na-CO2 batteries and increase the difficulty of scaling up this technology. We report the development of quasi–solid state Na-CO2 batteries with high safety using composite polymer electrolyte (CPE) and reduced graphene oxide (rGO) Na anodes. The CPE of PVDF-HFP [poly(vinylidene fluoride-co-hexafluoropropylene)]–4% SiO2/NaClO4–TEGDME (tetraethylene glycol dimethyl ether) has high ion conductivity (1.0 mS cm−1), robust toughness, a nonflammable matrix, and strong electrolyte-locking ability. In addition, the rGO-Na anode presents fast and nondendritic Na+ plating/stripping (5.7 to 16.5 mA cm−2). The improved kinetics and safety enable the constructed rGO-Na/CPE/CO2 batteries to successfully cycle in wide CO2 partial pressure window (5 to 100%, simulated car exhaust) and especially to run for 400 cycles at 500 mA g−1 with a fixed capacity of 1000 mA·hour g−1 in pure CO2. Furthermore, we scaled up the reversible capacity to 1.1 A·hour in pouch-type batteries (20 × 20 cm, 10 g, 232 Wh kg−1). This study makes quasi–solid state Na-CO2 batteries an attractive prospect. PMID:28164158

  15. Synthesis and Performance of Tungsten Disulfide/Carbon (WS2/C) Composite as Anode Material

    Science.gov (United States)

    Yuan, Zhengyong; Jiang, Qiang; Feng, Chuanqi; Chen, Xiao; Guo, Zaiping

    2018-01-01

    The precursors of an amorphous WS2/C composite were synthesized by a simple hydrothermal method using Na2WO4·2H2O and CH3CSNH2 as raw materials, polyethylene glycol as dispersant, and glucose as the carbon source. The as-synthesized precursors were further annealed at a low temperature in flowing argon to obtain the final materials (WS2/C composite). The structure and morphology of the WS2/C composite were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, and scanning electron microscopy. The electrochemical properties were tested by galvanostatic charge/discharge testing and alternating current (AC) impedance measurements. The results show that the as-prepared amorphous WS2/C composite features both high specific capacity and good cycling performance at room temperature within the potential window from 3.0 V to 0.01 V (versus Li+/Li) at current density of 100 mAg-1. The achieved initial discharge capacity was 1080 mAhg-1, and 786 mAhg-1 was retained after 170 cycles. Furthermore, the amorphous WS2/C composite exhibited a lower charge/discharge plateau than bare WS2, which is more beneficial for use as an anode. The cyclic voltammetry and AC impedance testing further confirmed the change in the plateau and the decrease in the charge transfer resistance in the WS2/C composite. The chemical formation process and the electrochemical mechanism of the WS2/C composite are also presented. The amorphous WS2/C composite can be used as a new anode material for future applications.

  16. EQCM behavior of copper anodes in alkaline medium and characterization of the electrocatalysis of ethanol oxidation by Cu(III

    Directory of Open Access Journals (Sweden)

    Paixão Thiago R. L. C.

    2006-01-01

    Full Text Available The anodic oxidation of copper electrodes in alkaline solutions was investigated by using voltammetry, chronoamperometry, impedance measurements and the electrochemical quartz crystal microbalance (EQCM. Experiments were carried out in NaOH solutions in the 0.1 to 3.0 mol L-1 concentration range. The formation of soluble and insoluble species such as Cu(OH4(2- and Cu2O during the electrodic dissolution of copper anodes was characterized by analyzing potentiodynamic mass responses and the relationship between mass changes and charge. On the other hand, EQCM data were not effective to confirm the nature of other copper species proposed in literature named as CuO and Cu(OH2 because of viscoelastic changes in the film layer electrodeposited onto the quartz crystal. The participation of a Cu(III soluble species in the electrocatalytic oxidation of ethanol was proved by EQCM measurements, data providing valuable information on the mechanism of the electrode process and formation of a Cu(II insoluble species from the reaction of Cu(III with ethanol.

  17. 25 CFR 170.445 - What is a strip map?

    Science.gov (United States)

    2010-04-01

    ... BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER INDIAN RESERVATION ROADS PROGRAM Planning, Design, and Construction of Indian Reservation Roads Program Facilities Irr Inventory § 170.445 What is a strip map? A strip map is a graphic representation of a section of road or other...

  18. Determination of residual stresses in roll compacted titanium strips

    CSIR Research Space (South Africa)

    Mothosi, KL

    2017-01-01

    Full Text Available induced during roll compaction of titanium strips were measured for strips of different densities. The different densities were achieved by rolling two different particle size (100 and 325 mesh) titanium powders varying the roll gap (0.1, 0.3 and 0.5 mm...

  19. Hollow Mill for Extraction of Stripped Titanium Screws: An Easy ...

    African Journals Online (AJOL)

    Removal of jammed titanium screws can be difficult due to the problem of stripping of the hexagonal heads of the screws. We present a technique of extraction of stripped screws with the use of a standard 4.5 mm stainless steel hollow mill in a patient of peri‑implant fracture of the radius fixed with a titanium locking plate 2 ...

  20. Hollow Mill for Extraction of Stripped Titanium Screws: An Easy ...

    African Journals Online (AJOL)

    screws. We present a technique of extraction of stripped screws with the use of a standard 4.5 mm stainless steel hollow mill in a patient of peri-implant fracture of the radius fixed with a titanium locking plate 2 years back. The technique is quick, safe, and cost effective. Key words: Hollow mill, stripped screws, titanium locked.

  1. Great saphenous vein stripping using nasogastric tube | Ademola ...

    African Journals Online (AJOL)

    Method and result: We describe the use of nasogastric tube in the stripping of GSV. This simple technique has been successfully applied in three patients. Conclusion: There is a need to carry out a prospective study regarding the application of this technique of GSV stripping. Keywords: Great saphenous vein, crossectomy, ...

  2. Reforestation of strip-mined lands in West Virginia

    Science.gov (United States)

    H. Spencer Potter; Sidney Weitzman; George R., Jr. Trimble

    1951-01-01

    The early 1940's witnessed a striking increase in strip-mining throughout the eastern coal region. West Virginia, with its extensive coal resources, naturally was caught in the full current of this shift in mining methods. Today the raw gash on the hillside - almost infallibly the mark of a strip-mine operation - is a familiar sight in the State.

  3. 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.

  4. Temperature sensitivity of the oxygenation reaction of stripped ...

    African Journals Online (AJOL)

    Temperature sensitivity of the oxygenation reaction of stripped haemolysates from the freshwater fishes Labeo capensis and Ciarias gariepinus. ... of the mudfish Labeo capensis and the catfish Clarias gariepinus, stripped by gel filtration chromatography and buffered at 23°C in 0,05 M Hepes (pH 7,48), were determined at ...

  5. Tape Stripping Technique for Stratum Corneum Protein Analysis

    DEFF Research Database (Denmark)

    Clausen, Maja-Lisa; Slotved, H.-C.; Krogfelt, Karen Angeliki

    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 ...

  6. Quality Tests of Double-Sided Silicon Strip Detectors

    CERN Document Server

    Cambon, T; CERN. Geneva; Fintz, P; Guillaume, G; Jundt, F; Kuhn, C; Lutz, Jean Robert; Pagès, P; Pozdniakov, S; Rami, F; Sparavec, K; Dulinski, W; Arnold, L

    1997-01-01

    The quality of the SiO2 insulator (AC coupling between metal and implanted strips) of double-sided Silicon strip detectors has been studied by using a probe station. Some tests performed on 23 wafers are described and the results are discussed. Remark This note seems to cause problems with ghostview but it can be printed without any problem.

  7. Stripping foils for the PSB H- injection system

    CERN Document Server

    Aiba, M; Goddard, B; Weterings, W

    2009-01-01

    Beam physics considerations for the stripping foil of the PSB H- injection system are described, including the arguments for the foil type, thickness, geometry and positioning. The foil performance considerations are described, including expected stripping efficiency, emittance growth, energy straggling, temperature and lifetime. The required movement ranges and tolerances are detailed, together with the assumptions used.

  8. Coiled sheet metal strip opens into tubular configuration

    Science.gov (United States)

    Park, J. J.

    1966-01-01

    Copper alloy is converted into a spring material that can be rolled into a compact coil which will spontaneously open to form a tube in the long direction of the strip. The copper alloy is passed through a furnace at a prescribed temperature while restraining the strip in the desired tubular configuration.

  9. 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.

  10. 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.

  11. Silicon strip detectors for the ATLAS upgrade

    CERN Document Server

    Gonzalez Sevilla, S; The ATLAS collaboration

    2011-01-01

    The Large Hadron Collider at CERN will extend its current physics program by increasing the peak luminosity by one order of magnitude. For ATLAS, one of the two general-purpose experiments of the LHC, an upgrade scenario will imply the complete replacement of its internal tracker due to the harsh conditions in terms of particle rates and radiation doses. New radiation-hard prototype n-in-p silicon sensors have been produced for the short-strip region of the future ATLAS tracker. The sensors have been irradiated up to the fluences expected in the high-luminous LHC collider. This paper summarizes recent results on the performance of the irradiated n-in-p detectors.

  12. Dynamic underground stripping. Innovative technology summary report

    International Nuclear Information System (INIS)

    1995-04-01

    Dynamic Underground Stripping (DUS) is a combination of technologies targeted to remediate soil and ground water contaminated with organic compounds. DUS is effective both above and below the water table and is especially well suited for sites with interbedded sand and clay layers. The main technologies comprising DUS are steam injection at the periphery of a contaminated area to heat permeable subsurface areas, vaporize volatile compounds bound to the soil, and drive contaminants to centrally located vacuum extraction wells; electrical heating of less permeable sediments to vaporize contaminants and drive them into the steam zone; and underground imaging such as Electrical Resistance Tomography to delineate heated areas to ensure total cleanup and process control. A full-scale demonstration was conducted on a gasoline spill site at Lawrence Livermore National Laboratory in Livermore, California from November 1992 through December 1993

  13. 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.

  14. 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

    2013-01-01

    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. PMID:24179697

  15. Comparative study of corneal strip extensometry and inflation tests.

    Science.gov (United States)

    Elsheikh, Ahmed; Anderson, Kevin

    2005-06-22

    Strip extensometry tests are usually considered less reliable than trephinate inflation tests in studying corneal biomechanics. In spite of the evident simplicity of strip extensometry tests, several earlier studies preferred inflation tests in determining the constitutive relationship of the cornea and its other material properties, such as Young's modulus and the hysteresis behaviour. In this research, the deficiencies of the strip tests are discussed and a mathematical procedure presented to take account of these deficiencies when obtaining the corneal material properties. The study also involves testing 10 pairs of porcine corneas using both strip extensometry and trephinate inflation techniques and the results are subjected to mathematical back analysis in order to determine the stress-strain behaviour. The behaviour obtained from the strip extensometry tests and using the new mathematical analysis procedure is shown to match closely the inflation test results.

  16. Superconducting strip detectors as position sensitive particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Scherschel, M. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland) Paul Scherrer Inst., Solid State Div., Villigen (Switzerland)); Finkbeiner, F. (Paul Scherrer Inst., Solid State Div., Villigen (Switzerland)); Zhao, S.P. (Paul Scherrer Inst., Solid State Div., Villigen (Switzerland)); Jaggi, A. (Paul Scherrer Inst., Solid State Div., Villigen (Switzerland)); Maier, T. (Paul Scherrer Inst., Solid State Div., Villigen (Switzerland)); Lerch, P. (Paul Scherrer Inst., Solid State Div., Villigen (Switzerland)); Zehnder, A. (Paul Scherrer Inst., Solid State Div., Villigen (Switzerland)); Ott, H.R. (Lab. fuer Festkoerperphysik, ETH-Hoenggerberg, Zuerich (Switzerland) Paul Scherrer Inst., Solid State Div., Villigen (Switzerland))

    1994-02-01

    The feasibility of using of current-biased superconducting strips for radiation detection is investigated. Narrow Ta strips are exposed to 5.5 MeV [alpha]-particle radiation and the rise-time of the induced voltage pulses is measured as function of temperature and bias current. The rise-time of the voltage signal strongly depends on the site on the strip which is hit by the [alpha]-particle. In order to determine the spatial resolution of a superconducting strip detector, position-sensitive measurements were performed. The maximum lateral resolution estimated so far is 25[mu]m in a 7[mu]m wide, 340 nm thick and 0.6 mm long Ta-strip. (orig.)

  17. Development and application of potentiometric stripping analysis

    Directory of Open Access Journals (Sweden)

    Babincev Ljiljana M.

    2017-01-01

    Full Text Available This paper focuses on the voltammetric determination of lead, cadmium and zinc in water. Two ways of determining were investigated: individually and all three metals simultaneously. The experiments were performed using the Potentiometric Stripping Analysis (PSA. Determination of metals in real samples was preceded by preliminary tests. Preliminary investigations were performed in order to determine the optimal conditions of measurement. It was concluded that the process of determining was for most part influenced by: pH, time of metals extraction, stirring rate of the solution and the thickness of the mercury layer on the working electrode. The smallest concentrations of metals which can be determined using this method are: for lead 22.48 μg dm-3, for cadmium 16.23 μg dm-3 and for zinc 18.75 μg dm-3. The obtained results deviated from the actual 1.12% for lead, 1.91% for cadmium and 1.81% for zinc. All tests (individually and simultaneously were conducted from model solution with concentration as follows: 44.96 μg dm-3 for lead, 32.47 μg dm-3 for cadmium and 37.50 μg dm-3 for zinc. The results of individual measurements deviated by 1.02% lead, 1.90% for cadmium and 1.89% for zinc. Simultaneously the contents were lower than real for: -4.58% for lead, cadmium for -1.91% and -1.89% for zinc. For the conditions determined, except for lead, deviations did not exceed ±2% . This indicates that Potentiometric Stripping Analysis is a good way of individual and simultaneous determination of lead, cadmium and zinc and for determination of their concentrations in water (river and groundwater.

  18. Homogeneous growth of TiO2-based nanotubes on nitrogen-doped reduced graphene oxide and its enhanced performance as a Li-ion battery anode.

    Science.gov (United States)

    Mehraeen, Shayan; Taşdemir, Adnan; Gürsel, Selmiye Alkan; Yürüm, Alp

    2018-06-22

    The pursuit of a promising replacement candidate for graphite as a Li-ion battery anode, which can satisfy both engineering criteria and market needs has been the target of researchers for more than two decades. In this work, we have investigated the synergistic effect of nitrogen-doped reduced graphene oxide (NrGO) and nanotubular TiO 2 to achieve high rate capabilities with high discharge capacities through a simple, one-step and scalable method. First, nanotubes of hydrogen titanate were hydrothermally grown on the surface of NrGO sheets, and then converted to a mixed phase of TiO 2 -B and anatase (TB) by thermal annealing. Specific surface area, thermal gravimetric, structural and morphological characterizations were performed on the synthesized product. Electrochemical properties were investigated by cyclic voltammetry and cyclic charge/discharge tests. The prepared anode showed high discharge capacity of 150 mAh g -1 at 1 C current rate after 50 cycles. The promising capacity of synthesized NrGO-TB was attributed to the unique and novel microstructure of NrGO-TB in which long nanotubes of TiO 2 have been grown on the surface of NrGO sheets. Such architecture synergistically reduces the solid-state diffusion distance of Li + and increases the electronic conductivity of the anode.

  19. An in situ method of creating metal oxide–carbon composites and their application as anode materials for lithium-ion batteries

    KAUST Repository

    Yang, Zichao

    2011-01-01

    Transition metal oxides are actively investigated as anode materials for lithium-ion batteries (LIBs), and their nanocomposites with carbon frequently show better performance in galvanostatic cycling studies, compared to the pristine metal oxide. An in situ, scalable method for creating a variety of transition metal oxide-carbon nanocomposites has been developed based on free-radical polymerization and cross-linking of poly(acrylonitrile) in the presence of the metal oxide precursor containing vinyl groups. The approach yields a cross-linked polymer network, which uniformly incorporates nanometre-sized transition metal oxide particles. Thermal treatment of the organic-inorganic hybrid material produces nearly monodisperse metal oxide nanoparticles uniformly embedded in a porous carbon matrix. Cyclic voltammetry and galvanostatic cycling electrochemical measurements in a lithium half-cell are used to evaluate the electrochemical properties of a Fe3O 4-carbon composite created using this approach. These measurements reveal that when used as the anode in a lithium battery, the material exhibits stable cycling performance at both low and high current densities. We further show that the polymer/nanoparticle copolymerization approach can be readily adapted to synthesize metal oxide/carbon nanocomposites based on different particle chemistries for applications in both the anode and cathode of LIBs. © 2011 The Royal Society of Chemistry.

  20. α-Fe{sub 2}O{sub 3} lithium battery anodes by nanocasting strategy from ordered 2D and 3D templates

    Energy Technology Data Exchange (ETDEWEB)

    Di Lupo, F. [GAME Lab, Department of Applied Science and Technology – DISAT, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy); Gerbaldi, C., E-mail: claudio.gerbaldi@polito.it [GAME Lab, Department of Applied Science and Technology – DISAT, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy); Casino, S.; Francia, C.; Meligrana, G. [GAME Lab, Department of Applied Science and Technology – DISAT, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy); Tuel, A. [Institut de Recherches sur la Catalyse, IRC-CNRS (UPR 5401), 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); Penazzi, N. [GAME Lab, Department of Applied Science and Technology – DISAT, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy)

    2014-12-05

    Highlights: • Nanosized α-Fe{sub 2}O{sub 3} lithium battery conversion anodes with tunable morphology. • Nanocasting technique using MCM-41 and MCM-48 silica moulds is adopted. • Textural/morphological characteristics define the electrochemical behaviour. • α-Fe{sub 2}O{sub 3} replica of MCM-41 exhibits stable capacity (∼300 mA h g{sup −1}) after 100 cycles. • α-Fe{sub 2}O{sub 3} replica of MCM-41 shows promising prospects as high-capacity Li-ion battery anode. - Abstract: Nanocasting strategy is here proposed as effective approach to tune structure and size of α-Fe{sub 2}O{sub 3} active nanoparticles as a promising anode material for Li-ion cells. MCM-41 and MCM-48 silicas, presenting hexagonal 2D and cubic 3D symmetry, respectively, and regular pore diameter of about 4 nm are selected as moulds. The structural–morphological and electrochemical characteristics are assessed by X-ray diffraction, transmission electron microscopy, N{sub 2} physisorption at 77 K, cyclic voltammetry and galvanostatic discharge/charge cycling. It is here demonstrated that structural–morphological features change accordingly to the template used and careful control of the texture/particle characteristics is likely a fundamental variable noticeably affecting the cycling behaviour.