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.

Solar UV-assisted sample preparation of river water for ultra-trace determination of uranium by adsorptive stripping voltammetry

International Nuclear Information System (INIS)

Woldemichael, G.; Tulu, T.; Flechsig, G.-U.

2012-01-01

The article describes how solar ultraviolet-A radiation can be used to digest samples as needed for voltammetric ultratrace determination of uranium(VI) in river water. We applied adsorptive stripping voltammetry (AdSV) using chloranilic acid as the complexing agent. Samples from the river Warnow in Rostock (Germany) were pretreated with either soft solar UV or wit artificial hard UV from a 30-W source emitting 254-nm light. Samples were irradiated for 12 h, and both methods yielded the same results. We were able to detect around 1 μg.L -1 of uranium(VI) in a sample of river water that also contained dissolved organic carbon at a higher mg.L -1 levels. No AdSV signal was obtained for U(VI) without any UV pre-treatment. Pseudo-polarographic experiments confirmed the dramatic effect of both digestion techniques the the AdSV response. The new method is recommended for use in mobile ultratrace voltammetry of heavy metals for most kinds of natural water samples including tap, spring, ground, sea, and river waters. The direct use of solar radiation for sample pre-treatment represents a sustainable technique for sample preparation that does not consume large quantities of chemicals or energy. (author)

Linear sweep anodic stripping voltammetry: Determination of ...

Indian Academy of Sciences (India)

The aim of this work is to determine Cr(VI) in water resources by anodic stripping voltammetry using SPE-. AuNPs modified electrode .... surface area about 4 fold). 3.2 Optimization of Parameters ..... in water samples. The above system offers a.

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

Directory of Open Access Journals (Sweden)

Rajeev Jain

2012-12-01

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

Double elimination voltammetry of short oligonucleotides

Czech Academy of Sciences Publication Activity Database

Mikelová, R.; Trnková, L.; Jelen, František

2007-01-01

Roč. 19, č. 17 (2007), s. 1807-1814 ISSN 1040-0397 R&D Projects: GA AV ČR(CZ) IAA100040602 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : adsorptive stripping voltammetry * elimination voltammetry * oligodeoxynucleotide Subject RIV: BO - Biophysics Impact factor: 2.949, year: 2007

Trace determination of yttrium and some heavy rare-earths by adsorptive stripping voltammetry

International Nuclear Information System (INIS)

Wang, J.; Zadeii, J.M.

1986-01-01

The interfacial and redox behaviour of rare-earth chelates the Solochrome Violet RS are exploited for developing a sensitive adsorptive stripping procedure. Yttrium and heavy rare earths such as dysprosium, holmium and ytterbium can thus be measured at ng/ml levels and below, by controlled adsorptive accumulation of the metal chelate at the hanging mercury drop electrode, followed by voltammetric measurement of the surface species. With a 3-min preconcentration time, the detection limit ranges from 5 x 10 -10 to 1.4 x 10 -9 M. The relative standard deviation at the 7 ng/ml level ranges from 4 to 7%. A separation method is required to differentiate between the individual rare-earth metals. (author)

Simultaneous determination of copper, lead and cadmium by cathodic adsorptive stripping voltammetry using artificial neural network

International Nuclear Information System (INIS)

Ensafi, Ali A.; Khayamian, T.; Benvidi, A.; Mirmomtaz, E.

2006-01-01

In this work, simultaneous determination of two groups of elements consisting of Pb(II)-Cd(II) and Cu(II)-Pb(II)-Cd(II) using adsorptive cathodic stripping voltammetry are described. The method is based on accumulation of these metal ions on mercury electrode using xylenol orange as a suitable complexing agent. The potential was scanned to the negative direction and the differential pulse stripping voltammograms were recorded. The instrumental and chemical factors were optimized using artificial neural network. The optimized conditions were obtained in pH of 5.5, xylenol orange concentration of 4.0 μM, accumulation potential of -0.50 V, accumulation time of 30 s, scan rate of 10 mV/s and pulse height of 70 mV. The relationship between the peak current versus concentration was linear over the range of 5.0-150.0 ng ml -1 for cadmium and 5.0-150.0 ng ml -1 for lead. The limits of detection were 0.98 and 1.18 ng ml -1 for lead and cadmium ions, respectively. In simultaneous determination of Cu(II), Pb(II) and Cd(II) there are inter-metallic interactions, which result a non-linear relationship between the peak current and the ionic concentration for each of the element. Therefore, an artificial neural network was used as the multivariate calibration method. The ANN was constructed with three neurons as the output layer for the simultaneous determination of the three elements. The constructed model was able to predict the concentration of the elements in the ranges of 1.0-50.0, 5.0-200.0 and 10.0-200.0 ng ml -1 , for Cu(II), Pb(II) and Cd(II), respectively

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

Science.gov (United States)

Pokpas, Keagan; Jahed, Nazeem; Baker, Priscilla G; Iwuoha, Emmanuel I

2017-07-25

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 Ni 2+ in water samples by Adsorptive Cathodic Stripping Voltammetry (AdCSV). The electrochemical platform is based on the adsorptive accumulation of Ni 2+ 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 Co 2+ and Zn 2+ demonstrates good selectivity and preferential binding towards the detection of Ni 2+ 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 Ni 2+ reduction at an accumulation time of 120 s., the prepared electrochemical sensor exhibited good detection and quantitation towards Ni 2+ detection in tap water samples, well below 0.1 mg L -1 set by the WHO and EPA standards. This comparable to the South African

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

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.

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

Differential pulse polarography of cadmium-and lead-urate and adsorptive stripping voltammetric determination of uric acid.

Science.gov (United States)

Gandour, M A; Ensaf-Aboul-Kasim; Amrallah, A H; Farghaly, O A

1994-03-01

The complex formation between uric acid and zinc, cadmium and lead ions has been investigated using differential pulse polarography in 0.01M NaNO(3). It is found that the complexes formed by Cd(II) and Pb(II) ions with uric acid have the stoichiometry of 1:2 and the logarithmic values of the apparent stability constant are 9.47 and 11.7, respectively. On the other hand, zinc(II) ions do not give any indication of complexation with uric acid. A sensitive voltammetric method is developed for the quantitative determination of uric acid. This method is based on controlled adsorptive preconcentration of uric acid on the hanging mercury drop electrode (HMDE), followed by tracing the voltammogram in the cathodic going potential scan. The modes used are direct current stripping voltammetry (DCSV) and differential pulse stripping voltammetry (DPSV). The detection limits found were 8 x 10(-9)M (quiescent period 15 sec) by DPSV and 1.6 x 10(-8)M by DCSV.

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).

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.

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

Functionalized Nanoporous Track Etched {beta}-PVDF Membrane Electrodes for Lead (II) Determination by Square Wave Anodic Stripping Voltammetry

Energy Technology Data Exchange (ETDEWEB)

Bessbousse, H [Laboratoire des Solides Irradies, CEA-CNRS-Ecole Polytechnique, 91128 Palaiseau (France); Nadhakumar, I [School of Chemistry, University of Southampton, University Road, Southampton S017 1BJ (United Kingdom); Decker, M; Clochard, M -C; Wade, T L [Laboratoire des Solides Irradies, CEA-CNRS-Ecole Polytechnique, 91128 Palaiseau (France); Barsbay, M [Hacettepe University, Department of Chemistry, Polymer Chemistry Division, 06800 Beytepe Ankara (Turkey)

2012-09-15

Track etched functionalized nanoporous {beta}-PVDF membrane electrodes, or functionalized membrane electrodes (FME), are thin-layer cells made from poly(acrylic acid) (PAA) functionalized nanoporous {beta}-poly(vinylidene fluoride) ({beta}-PVDF) membranes with thin Au films sputtered on each side as electrodes. The Au film is thin enough that the pores of the membranes are not completely covered. The PAA functionalization is specifically localised in the walls of the nanoporous {beta}-PVDF membrane by grafting. The PAA is a cation exchange polymer that adsorbs metal ions, such as Pb{sup 2+}, from aqueous solutions concentrating the ions into the membrane. After a time the FME is transferred to an electrochemical cell for analysis. A negative potential is applied to the Au film of the FME for a set time to reduce the adsorbed ions onto the Au film working electrode. The other metalized side of the FME functions as a counter electrode. Finally, square-wave anodic stripping voltammetry (SW-ASV) is performed on the FME to determine the metal ion concentrations in the original solution. The calibration curve of charge versus log concentration has a Temkin isotherm form. The FME membranes are 9 {mu}m thick and have 40 nm diameter pores with a density of 10{sup 10} pores/cm{sup 2}. This high pore density provides a large capacity for ion adsorption. Au ingress in the pores during sputtering forms a random array of nanoelectrodes. Like surface modified electrodes for adsorptive stripping voltammetry, the pre-concentration step for the FME is performed at open circuit. The zero current intercept of the calibration for Pb{sup 2+} is 0.13 ppb ({mu}g/L) and a detection limit of 0.050 ppb based on 3S/N from blank measurements. Voltammetry (CV) and chronoapmerometry (CA) were used to characterize the system. The apparent diffusion coefficient (D) for Pb{sup 2+} in the PAA functionalized pores was determined to be 2.44 x 10{sup -7} cm{sup 2}/s and the partition coefficient (p

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

Science.gov (United States)

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

2014-12-16

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

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

Differential Pulse Anodic Stripping Voltammetry for Mercury Determination

Directory of Open Access Journals (Sweden)

Vereștiuc Paul C.

2015-07-01

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

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)

Adsorptive stripping voltammetric behaviour of copper complexes of some heterocyclic azo compounds.

Science.gov (United States)

Farias, P A; Ferreira, S L; Ohara, A K; Bastos, M B; Goulart, M S

1992-10-01

Controlled adsorptive accumulation of copper complexed with TAN, TAC, TAR and TAM (heterocyclic azo-compounds) on a static mercury drop electrode provides the basis for the direct stripping measurement of this element in the nanomolar concentration level. The ligand TAN exhibited great sensitivity and better separation of the peak current of the ligand in relation to the complex. The reduction current of adsorbed complex ions of copper is measured by linear scan cathodic stripping voltammetry, preceded by a period of accumulation of a few minutes. The peak potential is at approximately -0.37 V vs. Ag/AgCl. Optimal experimental parameters were found to be a TAN concentration of 1 x 10(-5)M, an accumulation potential of -0.22 V, and a solution pH of 3.7 (acetate buffer). The detection limit is 0.8nM after a 5-min accumulation with a stirred solution, and the response is linear up to 50 mug/l. Many common cations and anions do not interfere in the determination of copper. The interference of titanium is eliminated by addition of fluoride ion. Results are reported for a fresh water sample.

Anodic Stripping Voltammetry at Nanoelectrodes: Trapping of Mn2+ by Crown Ethers

International Nuclear Information System (INIS)

Danis, Laurence; Gateman, Samantha Michelle; Snowden, Michael Edward; Halalay, Ion C.; Howe, Jane Y.; Mauzeroll, Janine

2015-01-01

The work presented here describes the development and characterization of platinum-mercury hemispherical nanoelectrodes for the spatially resolved quantitative detection of manganese cations. The electrochemical probes were made by electrodeposition of metallic mercury from a mercuric ion solution onto Pt/quartz laser-pulled concentric disk nanoelectrodes (with disk radii ranging from 3 to 500 nm). The nanoelectrodes were characterized by steady-state voltammetry, scanning electrochemical microscopy, environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy and calibrated with respect to the concentration of Mn 2+ ions using anodic stripping voltammetry. The fully characterized probes were employed for the quantitative detection of Mn 2+ . The technique has been used to evaluate the impact of a novel approach for mitigating the undesirable consequences of manganese dissolution in Li-ion batteries

Arsenic speciation study using x ray fluorescence and cathodic stripping voltammetry

International Nuclear Information System (INIS)

Valcarcel, Lino; Montero, Alfredo; Estevez, Juan; Pupo, Ivan

2006-01-01

Two methods for the determination of total As concentration and its inorganic species by Energy Dispersive X Ray Fluorescence (EDXRF) and Cathodic Stripping Voltammetry (CSV) were developed. The effect of pH on As (III) recovery after precipitation with APDC and EDXRF measurement was studied. Quantification of As was done using the thin layer approach. A reduction of As(V) to As(III) with sodium thiosulphate was necessary in order to determine the total As concentration. The effect of the amount of reducing agent on the recovery was also studied. As(V) concentration was calculated by difference between total As and As(III) concentration. On the other hand, a polarographic method, using the cathodic stripping mode was implemented. As(III) deposition on the electrode was enhanced by addition of Se(IV). Factors affecting As determination (selenium concentration, deposition potential, deposition time) were studied

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

Directory of Open Access Journals (Sweden)

Vu Dang Hoang

2013-01-01

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

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.

Nanomolar detection of rutin based on adsorptive stripping analysis at single-sided heated graphite cylindrical electrodes with direct current heating

Energy Technology Data Exchange (ETDEWEB)

Wu, Shao-Hua; Sun, Jian-Jun; Zhang, De-Feng; Lin, Zhi-Bin; Nie, Fa-Hui; Qiu, He-Yuan; Chen, Guo-Nan [Key Laboratory of Analysis and Detection Technology for Food Safety, Ministry of Education, College of Chemistry and Chemical Engineering, Fuzhou University, 523 Gong Ye Road, Fuzhou 350002 (China)

2008-09-20

A single-sided heated graphite cylindrical electrode (ss-HGCE) was designed. Compared to previous alternative current (AC) heating, much simpler and cheaper direct current (DC) heating supplier was adopted for the first time to perform adsorptive accumulation of rutin at ss-HGCE at elevated electrode temperature. This offers great promise for low cost, miniaturization and high compatibility with portability. The square wave voltammetry (SWV) stripping peak current was enhanced with increasing the electrode temperature only during preconcentration step. This enhancement was contributed to the forced thermal convection induced by heating the electrode rather than the bulk solution, which is able to improve mass transfer and facilitate adsorption hence enhance stripping response. A detection limit of 1.0 x 10{sup -9} M (S/N = 3) could be obtained at an electrode temperature of 48 C during 5 min accumulation, one magnitude lower than that at 28 C (room temperature). This is the lowest value at carbon-based electrodes for rutin determination as we know. Such novel method was also successfully used to determine rutin in pharmaceutical tablets. (author)

Extraction or adsorption? Voltammetric assessment of protamine transfer at ionophore-based polymeric membranes.

Science.gov (United States)

Garada, Mohammed B; Kabagambe, Benjamin; Amemiya, Shigeru

2015-01-01

Cation-exchange extraction of polypeptide protamine from water into an ionophore-based polymeric membrane has been hypothesized as the origin of a potentiometric sensor response to this important heparin antidote. Here, we apply ion-transfer voltammetry not only to confirm protamine extraction into ionophore-doped polymeric membranes but also to reveal protamine adsorption at the membrane/water interface. Protamine adsorption is thermodynamically more favorable than protamine extraction as shown by cyclic voltammetry at plasticized poly(vinyl chloride) membranes containing dinonylnaphthalenesulfonate as a protamine-selective ionophore. Reversible adsorption of protamine at low concentrations down to 0.038 μg/mL is demonstrated by stripping voltammetry. Adsorptive preconcentration of protamine at the membrane/water interface is quantitatively modeled by using the Frumkin adsorption isotherm. We apply this model to ensure that stripping voltammograms are based on desorption of all protamine molecules that are transferred across the interface during a preconcentration step. In comparison to adsorption, voltammetric extraction of protamine requires ∼0.2 V more negative potentials, where a potentiometric super-Nernstian response to protamine is also observed. This agreement confirms that the potentiometric protamine response is based on protamine extraction. The voltammetrically reversible protamine extraction results in an apparently irreversible potentiometric response to protamine because back-extraction of protamine from the membrane extremely slows down at the mixed potential based on cation-exchange extraction of protamine. Significantly, this study demonstrates the advantages of ion-transfer voltammetry over potentiometry to quantitatively and mechanistically assess protamine transfer at ionophore-based polymeric membranes as foundation for reversible, selective, and sensitive detection of protamine.

Application of adsorptive stripping voltammetry to the simultaneous determination of bismuth and copper in the presence of nuclear fast red

International Nuclear Information System (INIS)

Gholivand, M.B.; Romiani, A.A.

2006-01-01

A sensitive and selective method for the simultaneous determination of copper and bismuth by adsorptive stripping was developed using nuclear fast red (2-anthracenesulfonic acid, 4-amino-9,10-dihydro-1,3-dihydroxy-9,10-dioxo-, monosodium salt) as selective complexing agent onto hanging mercury drop electrode. In a single scan both metals gave peaks that were distinctly separated by 85 mV allowing their determination in the presence of each other. Optimal analytical conditions were found to be: nuclear fast red concentration of 80 μM, pH of 2.8 and adsorptive potential of -300 mV versus Ag/AgCl. With accumulation time of 180 s the peaks currents are proportional to concentration of copper and bismuth over the 1-100 and 5-60 ng mL -1 range with detection limits of 0.2 and 1.2 ng mL -1 , respectively. The procedure was applied to simultaneous determination of copper and bismuth in some real samples

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

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

Square-wave adsorptive stripping voltammetric determination of nanomolar levels of bezafibrate using a glassy carbon electrode modified with multi-walled carbon nanotubes within a dihexadecyl hydrogen phosphate film.

Science.gov (United States)

Ardila, Jorge Armando; Oliveira, Geiser Gabriel; Medeiros, Roberta Antigo; Fatibello-Filho, Orlando

2014-04-07

A highly sensitive method for bezafibrate determination using a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes within a dihexadecyl hydrogen phosphate film based on square-wave adsorptive stripping voltammetry (SWAdSV) is proposed. The electrochemical behaviour of bezafibrate has been studied by cyclic voltammetry, showing an irreversible anodic peak at a potential of 1.09 V in 0.1 mol L(-1) phosphate buffer solution (pH 2.0). A study of the scan rate showed that the oxidation of bezafibrate is an adsorptive-controlled process, involving the transfer of two electrons and two protons per molecule. The analytical curve was linear over a bezafibrate concentration range from 50 to 910 nmol L(-1), with a detection limit of 16 nmol L(-1). This analytical method was successfully applied for benzafibrate determination in pharmaceutical formulations, with results showing good agreement with those obtained using a comparative spectrophotometric method, and has the potential for field application.

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.

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.

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)

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.

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

Science.gov (United States)

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

2013-08-06

Nanostructured magnesium silicate hollow spheres, one kind of non-conductive nanomaterials, were used in heavy metal ions (HMIs) detection with enhanced performance for the first time. The detailed study of the enhancing electrochemical response in stripping voltammetry for simultaneous detection of ultratrace Cd(2+), Pb(2+), Cu(2+) and Hg(2+) was described. Electrochemical properties of modified electrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The operational parameters which have influence on the deposition and stripping of metal ions, such as supporting electrolytes, pH value, and deposition time were carefully studied. The anodic stripping voltammetric performance toward HMIs was evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The detection limits achieved (0.186nM, 0.247nM, 0.169nM and 0.375nM for Cd(2+), Pb(2+), Cu(2+) and Hg(2+)) are much lower than the guideline values in drinking water given by the World Health Organization (WHO). In addition, the interference and stability of the modified electrode were also investigated under the optimized conditions. An interesting phenomenon of mutual interference between different metal ions was observed. Most importantly, the sensitivity of Pb(2+) increased in the presence of certain concentrations of other metal ions, such as Cd(2+), Cu(2+) and Hg(2+) both individually and simultaneously. The proposed electrochemical sensing method is thus expected to open new opportunities to broaden the use of SWASV in analysis for detecting HMIs in the environment. Copyright © 2013 Elsevier B.V. All rights reserved.

The redox behaviour of diazepam (Valium®) using a disposable screen-printed sensor and its determination in drinks using a novel adsorptive stripping voltammetric assay.

Science.gov (United States)

Honeychurch, Kevin C; Crew, Adrian; Northall, Hannah; Radbourne, Stuart; Davies, Owian; Newman, Sam; Hart, John P

2013-11-15

In this study we investigated the possibility of applying disposable electrochemical screen-printed carbon sensors for the rapid identification and quantitative determination of diazepam in beverages. This was achieved utilising a previously unreported oxidation peak. The origin of this peak was investigated further by cyclic voltammetry and gas chromatography/mass spectroscopy. At pH 6 the voltammetric behaviour of this oxidation process was found to involve adsorption of the drug allowing for the development of an adsorptive stripping voltammetric assay. Experimental conditions were then optimised for the determination of diazepam in a beverage sample using a medium exchange technique. It was shown that no elaborate extraction procedures were required as the calibration plots obtained in the absence and presence of the beverage were very similar. © 2013 Elsevier B.V. All rights reserved.

Adsorptive stripping voltammetric determination of uranium with cephradine

International Nuclear Information System (INIS)

Ali, A.M.M.; Ghandour, M.A.; Khodari, M.

1995-01-01

Uranium adsorbed with cephradine is reduced on a hanging mercury drop electrode. This property was exploited in developing a highly sensitive stripping voltammetric procedure for the determination of uranium. A detection limit 2 x 10 -9 mol I -1 (0.5 μg I -1 ) of uranium ion is obtained with an 180 s accumulation time. Cyclic voltammetry was used to characterize the interfacial and redox behaviour. The effects of various parameters are discussed. Experimental conditions include the use of 5 x 10 -6 mol I -1 cephradine in 0.05 mol I -1 sodium perchlorate (pH ''approx ='' 6.5), an accumulation potential of 0.0 V versus SCE and a direct current stripping technique. The response is linear up to 5 x 10 -6 mol I -1 uranium and the relative standard deviation at 1 x 10 -7 mol I -1 ) UO 2+ is 4.4%. The effect of other metal ions was investigated. (author)

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.

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.

Total inorganic arsenic detection in real water samples using anodic stripping voltammetry and a gold-coated diamond thin-film electrode.

Science.gov (United States)

Song, Yang; Swain, Greg M

2007-06-12

An accurate method for total inorganic arsenic determination in real water samples was developed using differential pulse anodic stripping voltammetry (DPASV) and a Au-coated boron-doped diamond thin-film electrode. Keys to the method are the use of a conducting diamond platform and solid phase extraction for sample preparation. In the method, the As(III) present in the sample is first detected by DPASV. The As(V) present is then reduced to As(III) by reaction with Na2SO3 and this is followed by a second detection of As(III) by DPASV. Interfering metal ions (e.g., Cu(II)) that cause decreased electrode response sensitivity for arsenic in real samples are removed by solid phase extraction as part of the sample preparation. For example, Cu(II) caused a 30% decrease in the As stripping peak current at a solution concentration ratio of 3:1 (Cu(II)/As(III)). This loss was mitigated by passage of the solution through a Chelex 100 cation exchange resin. After passage, only a 5% As stripping current response loss was seen. The effect of organic matter on the Au-coated diamond electrode response for As(III) was also evaluated. Humic acid at a 5 ppm concentration caused only a 9% decrease in the As stripping peak charge for Au-coated diamond. By comparison, a 50% response decrease was observed for Au foil. Clearly, the chemical properties of the diamond surface in the vicinity of the metal deposits inhibit molecular adsorption on at least some of the Au surface. The method provided reproducible and accurate results for total inorganic arsenic in two contaminated water samples provided by the U.S. Bureau of Reclamation. The total inorganic As concentration in the two samples, quantified by the standard addition method, was 23.2+/-2.9 ppb for UV plant influent water and 16.4+/-0.9 ppb for Well 119 water (n=4). These values differed from the specified concentrations by less than 4%.

Total inorganic arsenic detection in real water samples using anodic stripping voltammetry and a gold-coated diamond thin-film electrode

International Nuclear Information System (INIS)

Song Yang; Swain, Greg M.

2007-01-01

An accurate method for total inorganic arsenic determination in real water samples was developed using differential pulse anodic stripping voltammetry (DPASV) and a Au-coated boron-doped diamond thin-film electrode. Keys to the method are the use of a conducting diamond platform and solid phase extraction for sample preparation. In the method, the As(III) present in the sample is first detected by DPASV. The As(V) present is then reduced to As(III) by reaction with Na 2 SO 3 and this is followed by a second detection of As(III) by DPASV. Interfering metal ions (e.g., Cu(II)) that cause decreased electrode response sensitivity for arsenic in real samples are removed by solid phase extraction as part of the sample preparation. For example, Cu(II) caused a 30% decrease in the As stripping peak current at a solution concentration ratio of 3:1 (Cu(II)/As(III)). This loss was mitigated by passage of the solution through a Chelex 100 cation exchange resin. After passage, only a 5% As stripping current response loss was seen. The effect of organic matter on the Au-coated diamond electrode response for As(III) was also evaluated. Humic acid at a 5 ppm concentration caused only a 9% decrease in the As stripping peak charge for Au-coated diamond. By comparison, a 50% response decrease was observed for Au foil. Clearly, the chemical properties of the diamond surface in the vicinity of the metal deposits inhibit molecular adsorption on at least some of the Au surface. The method provided reproducible and accurate results for total inorganic arsenic in two contaminated water samples provided by the U.S. Bureau of Reclamation. The total inorganic As concentration in the two samples, quantified by the standard addition method, was 23.2 ± 2.9 ppb for UV plant influent water and 16.4 ± 0.9 ppb for Well 119 water (n = 4). These values differed from the specified concentrations by less than 4%

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

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

Adsorptive differential pulse voltammetry for determination of uranium in sea water

International Nuclear Information System (INIS)

Khandekar, R.N.; Raghunath, R.

1990-01-01

An adsorptive stripping voltammetric procedure for direct determination of trace quantities of uranium in sea water is described. Optimal conditions include pH 6.7, 2 x 10 -5 M 8-hydroxyquinoline (oxine) and collection potential of -0.4V (vs Ag/AgCl) at hanging mercury drop electrode. With controlled adsorptive accumulation for one min. a detection limit of 2.8 x 10 -10 M uranium is obtained. The response is linear upto 7 x 10 -8 M uranium and the relative standard deviation at 4 x 10 -9 M uranium is 11.5%. The effect of possible interference from other metals has been investigated. The accuracy of the method has been tested by comparison with the results obtained by fluorimetric method. (author). 2 figs., 1 tab., 20 refs

Combined micro-droplet and thin-film-assisted pre-concentration of lead traces for on-line monitoring using anodic stripping voltammetry.

Science.gov (United States)

Belostotsky, Inessa; Gridin, Vladimir V; Schechter, Israel; Yarnitzky, Chaim N

2003-02-01

An improved analytical method for airborne lead traces is reported. It is based on using a Venturi scrubber sampling device for simultaneous thin-film stripping and droplet entrapment of aerosol influxes. At least threefold enhancement of the lead-trace pre-concentration is achieved. The sampled traces are analyzed by square-wave anodic stripping voltammetry. The method was tested by a series of pilot experiments. These were performed using contaminant-controlled air intakes. Reproducible calibration plots were obtained. The data were validated by traditional analysis using filter sampling. LODs are comparable with the conventional techniques. The method was successfully applied to on-line and in situ environmental monitoring of lead.

Combined micro-droplet and thin-film-assisted pre-concentration of lead traces for on-line monitoring using anodic stripping voltammetry

Energy Technology Data Exchange (ETDEWEB)

Belostotsky, Inessa; Gridin, Vladimir V.; Schechter, Israel; Yarnitzky, Chaim N. [Department of Chemistry, Technion Israel Institute of Technology, 32000, Haifa (Israel)

2003-02-01

An improved analytical method for airborne lead traces is reported. It is based on using a Venturi scrubber sampling device for simultaneous thin-film stripping and droplet entrapment of aerosol influxes. At least threefold enhancement of the lead-trace pre-concentration is achieved. The sampled traces are analyzed by square-wave anodic stripping voltammetry. The method was tested by a series of pilot experiments. These were performed using contaminant-controlled air intakes. Reproducible calibration plots were obtained. The data were validated by traditional analysis using filter sampling. LODs are comparable with the conventional techniques. The method was successfully applied to on-line and in situ environmental monitoring of lead. (orig.)

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

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

OpenAIRE

Yu Song; Chao Bian; Jianhua Tong; Yang Li; Shanghong Xia

2016-01-01

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 curr...

Anodic stripping voltammetry with carbon paste electrodes for rapid Ag(I) and Cu(II) determinations.

Science.gov (United States)

Labar, C; Lamberts, L

1997-05-01

The simultaneous determination of silver(I) and copper(II) is realized for the routine analysis of trace levels of these elements by anodic stripping voltammetry (ASV) at the carbon paste electrode (CPE). The electrochemical response is studied in 14 different supporting electrolytes, ranging from acidic solutions (pH 0.1) to neutral and basic (pH 9.7) media, and the parameters governing electrodeposition and stripping steps are characterized for each medium by the use of pseudo-voltammograms. Comparison between different modes of matter transport mechanisms is also given. The dynamic range of the method is 0.05 to 150 mug 1(-1) Ag(I) in the majority of the media studied and can be extended to 400 mug l(-1) in selected media, with a general reproducibility in the +/- 2% range for five replicate measurements. The total analysis time lies between approximately 30 s and 10 min. Activation of the CPE surface has been studied, but this pretreatment is demonstrated to be unfavourable and is replaced by a simpler unique 'cleaning' procedure of dipping the CPE in diluted nitric acid.

Square-wave stripping voltammetric determination of caffeic acid on electrochemically reduced graphene oxide-Nafion composite film.

Science.gov (United States)

Filik, Hayati; Çetintaş, Gamze; Avan, Asiye Aslıhan; Aydar, Sevda; Koç, Serkan Naci; Boz, İsmail

2013-11-15

An electrochemical sensor composed of Nafion-graphene nanocomposite film for the voltammetric determination of caffeic acid (CA) was studied. A Nafion graphene oxide-modified glassy carbon electrode was fabricated by a simple drop-casting method and then graphene oxide was electrochemically reduced over the glassy carbon electrode. The electrochemical analysis method was based on the adsorption of caffeic acid on Nafion/ER-GO/GCE and then the oxidation of CA during the stripping step. The resulting electrode showed an excellent electrocatalytical response to the oxidation of caffeic acid (CA). The electrochemistry of caffeic acid on Nafion/ER-GO modified glassy carbon electrodes (GCEs) were studied by cyclic voltammetry and square-wave adsorption stripping voltammetry (SW-AdSV). At optimized test conditions, the calibration curve for CA showed two linear segments: the first linear segment increased from 0.1 to 1.5 and second linear segment increased up to 10 µM. The detection limit was determined as 9.1×10(-8) mol L(-1) using SW-AdSV. Finally, the proposed method was successfully used to determine CA in white wine samples. Copyright © 2013 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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

2016-09-02

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-04-15

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

International comparison of Cd content in a quality control material of Navajuelas (Tagelus dombeii) determined by anodic stripping voltammetry, atomic absorption spectrometry and neutron activation analysis

International Nuclear Information System (INIS)

Queirolo, F.; Forschungszentrum Juelich GmbH; Universidad de Extremadura, Badajoz; Ostapczuk, P.; Valenta, P.; Stegen, S.; Universidad de Extremadura, Badajoz; Marin, C.; Vinagre, F.; Sanchez, A.

1991-01-01

The determination of Cd was performed by neutron activation analysis (NAA), atomic absorption spectrometry (AAS) with flame or in the electrothermal mode and anodic stripping voltammetry in the differential pulse mode (DPASV) and the square wave mode (SWASV). (orig./EF)

A one-dimensional stochastic approach to the study of cyclic voltammetry with adsorption effects

Energy Technology Data Exchange (ETDEWEB)

Samin, Adib J. [The Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19" t" h Avenue, Columbus, Ohio 43210 (United States)

2016-05-15

In this study, a one-dimensional stochastic model based on the random walk approach is used to simulate cyclic voltammetry. The model takes into account mass transport, kinetics of the redox reactions, adsorption effects and changes in the morphology of the electrode. The model is shown to display the expected behavior. Furthermore, the model shows consistent qualitative agreement with a finite difference solution. This approach allows for an understanding of phenomena on a microscopic level and may be useful for analyzing qualitative features observed in experimentally recorded signals.

A one-dimensional stochastic approach to the study of cyclic voltammetry with adsorption effects

International Nuclear Information System (INIS)

Samin, Adib J.

2016-01-01

In this study, a one-dimensional stochastic model based on the random walk approach is used to simulate cyclic voltammetry. The model takes into account mass transport, kinetics of the redox reactions, adsorption effects and changes in the morphology of the electrode. The model is shown to display the expected behavior. Furthermore, the model shows consistent qualitative agreement with a finite difference solution. This approach allows for an understanding of phenomena on a microscopic level and may be useful for analyzing qualitative features observed in experimentally recorded signals.

Determination of sub-parts per billion levels of copper in complex matrices by adsorptive string voltammetry on a mercury electrode

International Nuclear Information System (INIS)

Shahbaazi, H.R.; Shahbaazi, H.R.; Safavi, A.; Maleki, N.

2008-01-01

The voltammetric characteristics of Cu(II)-SSA complex at the mercury electrode were investigated. An analytical method that based on the adsorptive accumulation of Cu(II)-SSA complex followed by the reduction of the complexed copper was developed for the copper determination in complex matrices in presence of the large amount of foreign ions. Adsorptive voltammetry determination showed that the Cu(II)-SSA complex behaves irreversibly exchanging two electrons on the hanging mercury drop electrode (HMDE). Factor affecting on the complextion, accumulation and stripping steps were studied and a procedure was developed. The instrumental parameters in the measurement step were also tested. The optimum conditions of pH, SSA concentration, accumulation potential and accumulation time were studied. Under optimal conditions (pH=12.9 glycin Buffer, 7 x 10 - '3 M SSA and accumulation potential -100 mV vs. Ag/ AgCl), a linear calibration graph in the range 1.25 μg L -1 to 42.5 μg L'- 1 and a detection limit of 0.8 μ L -1 were obtained. The average relative standard deviation (RSD) for seven determinations was calculated as 7 %, 5.5 % and 3 % for the concentrations between 3, 15 and 23 μg L'- 1 . The effect of foreign ions and surfactants on the peak height of Cu(II)-SSA complex was evaluated. The method was applied for the determination of the copper in different real samples such as crude oil, crude oil tank button sludge, waste water and tap water samples. The accuracy of the results was checked by ICP. (author)

Using of multi-walled carbon nanotubes electrode for adsorptive stripping voltammetric determination of ultratrace levels of RDX explosive in the environmental samples.

Science.gov (United States)

Rezaei, Behzad; Damiri, Sajjad

2010-11-15

A study of the electrochemical behavior and determination of RDX, a high explosive, is described on a multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) using adsorptive stripping voltammetry and electrochemical impedance spectroscopy (EIS) techniques. The results indicated that MWCNTs electrode remarkably enhances the sensitivity of the voltammetric method and provides measurements of this explosive down to the sub-mg/l level in a wide pH range. The operational parameters were optimized and a sensitive, simple and time-saving cyclic voltammetric procedure was developed for the analysis of RDX in ground and tap water samples. Under optimized conditions, the reduction peak have two linear dynamic ranges of 0.6-20.0 and 8.0-200.0 mM with a detection limit of 25.0 nM and a precision of <4% (RSD for 8 analysis). Copyright © 2010 Elsevier B.V. All rights reserved.

Electrochemical sample preparation for the determination of Cd, Pb, and Cu in the presence of surfactants by stripping voltammetry

International Nuclear Information System (INIS)

Svintsova, L.D.; Chernysheva, N.N.

1997-01-01

The electrochemical pretreatment of aqueous solutions of synthetic surfactants in a diaphragm elelctrolyzer was used in order to diminish surfactant interference. The determination of cadmium, lead, and copper by stripping voltammetry with a mercury-film electrode in model solutions of cetylpyriridinium chloride, sodium lauryl sulfate, and OP-10 was taken as an example. It was found that the reproducibility of anodic peaks of the elements was improved, and the linearity of calibration characteristics was recovered; however, the sensitivity was not always as high as the value in the blank experiment

Applications of voltammetry in environmental science

Energy Technology Data Exchange (ETDEWEB)

Richardson, D.H.S.

1985-01-01

The wide-ranging applications of voltammetry to the analysis of trace metals and other ions of interest to environmental scientists are reviewed. It is concluded that the availability of modern microprocessor controlled instrumentation, capable of performing both anodic stripping and square wave voltammetry, provides a flexible and powerful technique to aid in solving analytical problems and carrying out routine analyses. The recent identification of many sensitizing agents which reduce detection limits to part per thousand million level, or below, is a further exciting development in this field.

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

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.

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.

Behaviour and quantification studies of terbacil and lenacil in environmental samples using cyclic and adsorptive stripping voltammetry at hanging mercury drop electrode.

Science.gov (United States)

Thriveni, T; Rajesh Kumar, J; Sujatha, D; Sreedhar, N Y

2007-05-01

The cyclic voltammograms of terbacil and lenacil at the hanging mercury drop electrode showed a single well defined four electron irreversible peak in universal buffer of pH 4.0 for both compounds. The peak potentials were shifted to more negative values on the increase of pH of the medium, implying the involvement of protons in the electrode reaction and that the proton transfer reaction precedes the proper electrode process. The four electron single peak may be attributed to the simultaneous reduction of carbonyl groups present in 2 and 4 in pyrimidine ring of terbacil and lenacil to the corresponding hydroxy derivative. Based on the interfacial adsorptive character of the terbacil and lenacil onto the mercury electrode surface, a simple sensitive and low cost differential pulse adsorptive stripping voltammetric procedure was optimized for the analysis of terbacil and lenacil. The optimal operational conditions of the proposed procedure were accumulation potential E (acc) = -0.4 V, accumulation time t (acc) = 80 s, scan rate = 40 mV s(-1), pulse amplitude = 25 mV using a universal buffer pH 4.0 as a supporting electrolyte. The linear concentration range was found to be 1.5 x 10(-5) to 1.2 x 10(-9) mol/l and 1.5 x 10(-5) to 2.5 x 10(-8) mol/l with the lower detection limit of 1.22 x 10(-9) and 2.0 x 10(-8) mol/l. The correlation coefficient and relative standard deviation values are found to be 0.942, 0.996, 1.64% and 1.23%, respectively, for 10 replicants. The procedure was successfully applied for determination of terbacil and lenacil in formulations, mixed formulations, environmental samples such as fruit samples and spiked water samples.

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

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.

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.

Carbon paste electrode modified molecularly imprinted polymer as a sensor for creatinine analysis by stripping voltammetry

Science.gov (United States)

Khasanah, M.; Darmokoesoemo, H.; Rizki, D. A.

2017-09-01

Modification of carbon paste electrode with molecularly imprinted polymer (CP-MIP) as a voltammetric sensor for creatinine has been developed. MIP was synthesized by reacting melamine, chloranil and creatinine with a mole ratio of 1:1:0.1. Creatinine was extracted from polymer chain by using hot water to form a specific imprinted for creatinine molecule. Carbon paste-MIP electrode was prepared by mixing activated carbon, solid paraffin, and MIP in a 45:40:15(w/w %) ratio. The optimum conditions of creatinine analysis by differential pulse stripping voltammetry (DPSV) using the developed electrode were the accumulation potential -1000 mV during 90 s at pH 5. The precision of the method for 0.1-0.5 μlg/L creatinine was 88.7-96.3%, while the detection limit of this method was 0.0315 μlg/L. The accuracy compared by spectrophotometric method was 95.3-103.6%

Cathodic adsorptive stripping voltammetric determination of Ribavirin in pharmaceutical dosage form, urine and serum

Directory of Open Access Journals (Sweden)

Ahmed A. Abdel Gaber

2017-05-01

Full Text Available A sensitive, simple and rapid square-wave adsorptive stripping voltammetric method was developed and validated for the determination of Ribavirin in pharmaceutical formulations. The proposed method was based on the electrochemical reduction of Ribavirin at a hanging mercury drop electrode in Britton Robinson buffer at pH 10. A well-defined peak was observed at 880 mV with 30 s of accumulation time and 50 mV of accumulation potential. Under these optimized conditions, the square-wave adsorptive stripping voltammetric peak current showed a linear correlation on drug concentration over the range of 1 × 10−10–2 × 10−7 mol L−1 with a correlation coefficient of 0.9995 for the proposed method. The detection and quantitation limits for this method were 2.02 × 10−10 and 6.80 × 10−10 mol L−1, respectively. The results obtained for intra-day and inter-day precision (as RSD % were between 0.447% and 1.024%. This method was applied successfully for the determination of Ribavirin in its pharmaceutical dosage forms with mean recoveries of 99.68 ± 0.13 with RSD % of 0.81% and 99.20 ± 0.24 with RSD % of 0.49% for two concentrations 5 × 10−9 and 5 × 10−8 mol L−1, respectively for 200 mg capsules. The results obtained from the developed square-wave adsorptive stripping voltammetric method were compared with those obtained by the analytical method reported in the literature.

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.

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

International Nuclear Information System (INIS)

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

2004-01-01

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

Differential pulse adsorptive stripping voltammetric determination of nanomolar levels of atorvastatin calcium in pharmaceutical and biological samples using a vertically aligned carbon nanotube/graphene oxide electrode.

Science.gov (United States)

Silva, Tiago Almeida; Zanin, Hudson; Vicentini, Fernando Campanhã; Corat, Evaldo José; Fatibello-Filho, Orlando

2014-06-07

A novel vertically aligned carbon nanotube/graphene oxide (VACNT-GO) electrode is proposed, and its ability to determine atorvastatin calcium (ATOR) in pharmaceutical and biological samples by differential pulse adsorptive stripping voltammetry (DPAdSV) is evaluated. VACNT films were prepared on a Ti substrate by a microwave plasma chemical vapour deposition method and then treated with oxygen plasma to produce the VACNT-GO electrode. The oxygen plasma treatment exfoliates the carbon nanotube tips exposing graphene foils and inserting oxygen functional groups, these effects improved the VACNT wettability (super-hydrophobic) which is crucial for its electrochemical application. The electrochemical behaviour of ATOR on the VACNT-GO electrode was studied by cyclic voltammetry, which showed that it underwent an irreversible oxidation process at a potential of +1.08 V in pHcond 2.0 (0.2 mol L(-1) buffer phosphate solution). By applying DPAdSV under optimized experimental conditions the analytical curve was found to be linear in the ATOR concentration range of 90 to 3.81 × 10(3) nmol L(-1) with a limit of detection of 9.4 nmol L(-1). The proposed DPAdSV method was successfully applied in the determination of ATOR in pharmaceutical and biological samples, and the results were in close agreement with those obtained by a comparative spectrophotometric method at a confidence level of 95%.

An environmental friendly electrode and extended cathodic potential window for anodic stripping voltammetry of zinc detection

International Nuclear Information System (INIS)

Dueraning, Anisah; Kanatharana, Proespichaya; Thavarungkul, Panote; Limbut, Warakorn

2016-01-01

This work reports on a novel polyeriochrome black T (poly(EBT) modified electrode for use as an environmentally-friendly electrode material that extends the cathodic potential window and improves the sensitivity and repeatability to detect zinc in industrial wastewater. The poly(EBT) film on the GCE surface was fabricated by electropolymerization. The surface morphology and electrochemical behavior of the modified electrode were characterized by scanning electron microscopy, fourier transform infrared spectroscopy and anodic stripping voltammetry. Under optimal conditions, the poly(EBT)/GCE exhibited a high hydrogen overvoltage (extended cathodic potential window). It provided a high sensitivity, a wide linear range (1.0 to 400.0 μg L −1 ), a low detection limit (0.9 μg L −1 ), had excellent repeatability and good recoveries (95% to 105%). This proposed modified electrode was applied to the determination of zinc in wastewater samples, and the results were consistent with those of an inductively coupled plasma atomic emission spectroscopy analysis.

Pseudo-stir bar hollow fiber solid/liquid phase microextraction combined with anodic stripping voltammetry for determination of lead and cadmium in water samples

Directory of Open Access Journals (Sweden)

Zarrin Es’haghi

2014-11-01

Full Text Available A new procedure is presented for the determination of low concentrations of lead and cadmium in water samples. Ligand assisted pseudo-stir bar hollow fiber solid/liquid phase microextraction using sol–gel sorbent reinforced with carbon nanotubes was combined with differential pulse anodic stripping voltammetry for simultaneous determination of cadmium and lead in tap water, and Darongar river water samples. In the present work, differential pulse anodic stripping voltammetry (DPASV using a hanging mercury drop electrode (HMDE was used in order to determine the ultra trace level of lead and cadmium ions in real samples. This method is based on accumulation of lead and cadmium ions on the electrode using different ligands; Quinolin-8-ol, 5,7-diiodo quinoline-8-ol, 4,5-diphenyl-1H-imidazole-2(3H-one and 2-{[2-(2-Hydroxy-ethylamino-ethylamino]-methyl}-phenol as the complexing agent. The optimized conditions were obtained. The relationship between the peak current versus concentration was linear over the range of 0.05–500 ng mL−1 for Cd (II and Pb (II. The limits of detection for lead and cadmium were 0.015 ng mL−1 and 0.012 ng mL−1, respectively. Under the optimized conditions, the pre-concentration factors are 2440 and 3710 for Cd (II and Pb (II in 5 mL of water sample, respectively.

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.

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

Directory of Open Access Journals (Sweden)

Grabarczyk M.

2013-04-01

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

Differential Pulse Anodic Stripping Voltammetry for Mercury Determination

OpenAIRE

Vereștiuc Paul C.; Tucaliuc Oana-Maria; Breabăn Iuliana G.; Crețescu Igor; Nemțoi Gheorghe

2015-01-01

In the present work voltammetric investigations have been performed on HgCl2 aqueous solutions prepared from a Cz 9024 reagent. Carbon paste electrode (CPE), eriochrome black T modified carbon paste electrode (MCPE/EBT) and KCl 1M as background electrolyte, were involved within the experimental procedures. Cyclic voltammetry (CV) has been performed in order to compare the behaviour of the two electrodes in both K3[Fe(CN)6] and mercury calibration aqueous solution. Differential pulse anodic st...

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

Determination of mercury in ambient water samples by anodic stripping voltammetry on screen-printed gold electrodes.

Science.gov (United States)

Bernalte, E; Marín Sánchez, C; Pinilla Gil, E

2011-03-09

The applicability of commercial screen-printed gold electrodes (SPGEs) for the determination of Hg(II) in ambient water samples by square wave anodic stripping voltammetry has been demonstrated. Electrode conditioning procedures, chemical and instrumental variables have been optimized to develop a reliable method capable of measuring dissolved mercury in the low ng mL(-1) range (detection limit 1.1 ng mL(-1)), useful for pollution monitoring or screening purposes. The proposed method was tested with the NIST 1641d Mercury in Water Standard Reference Material (recoveries 90.0-110%) and the NCS ZC 76303 Mercury in Water Certified Reference Material (recoveries 82.5-90.6%). Waste water samples from industrial origin and fortified rain water samples were assayed for mercury by the proposed method and by a reference ICP-MS method, with good agreement. Screen printing technology thus opens a useful way for the construction of reliable electrochemical sensors for decentralized or even field Hg(II) testing. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

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)

Corrosion of Cu-xZn alloys in slightly alkaline chloride solutions studied by stripping voltammetry and microanalysis.

Science.gov (United States)

Milosev, I; Minović, A

2001-01-01

The mechanism of corrosion of Cu-xZn alloys (x = 10-40 wt %) in slightly alkaline chloride solutions was investigated by analysing solid reaction products by energy dispersive X-ray analysis (EDS) and dissolved reaction products by differential anodic pulse stripping (DAPS) voltammetry. The corrosion process was studied under open circuit and under potentiostatic conditions at selected potentials. Pure metals were studied comparatively so that an interacting effect of particular metal components in the alloy could be determined. All four Cu-xZn alloys show an improved behaviour compared to pure metals. Under open-circuit condition both components dissolve simultaneously in the solution. With increasing immersion time the preferential, dissolution of zinc in the solution becomes pronounced. It is the highest for Cu-10Zn and the lowest for Cu-30Zn alloy. Under potentiostatic control the dissolution mechanism depends on the electrode potential and changes from exclusive dissolution of zinc to simultaneous dissolution of both components with preferential dissolution of zinc. The latter decreases, as the electrode potential becomes more positive.

Metal ion analysis in contaminated water samples using anodic stripping voltammetry and a nanocrystalline diamond thin-film electrode

International Nuclear Information System (INIS)

Sonthalia, Prerna; McGaw, Elizabeth; Show, Yoshiyuki; Swain, Greg M.

2004-01-01

Boron-doped nanocrystalline diamond thin-film electrodes were employed for the detection and quantification of Ag (I), Cu (II), Pb (II), Cd (II), and Zn (II) in several contaminated water samples using anodic stripping voltammetric (ASV). Diamond is an alternate electrode that possesses many of the same attributes as Hg and, therefore, appears to be a viable material for this electroanalytical measurement. The nanocrystalline form has been found to perform slightly better than the more conventional microcrystalline form of diamond in this application. Differential pulse voltammetry (DPASV) was used to detect these metal ions in lake water, well water, tap water, wastewater treatment sludge, and soil. The electrochemical results were compared with data from inductively coupled plasma mass spectrometric (ICP-MS) and or atomic absorption spectrometric (AAS) measurements of the same samples. Diamond is shown to function well in this electroanalytical application, providing a wide linear dynamic range, a low limit of quantitation, excellent response precision, and good response accuracy. For the analysis of Pb (II), bare diamond provided a response nearly identical to that obtained with a Hg-coated glassy carbon electrode

Finite-element simulations of the influence of pore wall adsorption on cyclic voltammetry of ion transfer across a liquid-liquid interface formed at a micropore.

Science.gov (United States)

Ellis, Jonathan S; Strutwolf, Jörg; Arrigan, Damien W M

2012-02-21

Adsorption onto the walls of micropores was explored by computational simulations involving cyclic voltammetry of ion transfer across an interface between aqueous and organic phases located at the micropore. Micro-interfaces between two immiscible electrolyte solutions (micro-ITIES) have been of particular research interest in recent years and show promise for biosensor and biomedical applications. The simulation model combines diffusion to and within the micropore, Butler-Volmer kinetics for ion transfer at the liquid-liquid interface, and Langmuir-style adsorption on the pore wall. Effects due to pore radius, adsorption and desorption rates, surface adsorption site density, and scan rates were examined. It was found that the magnitude of the reverse peak current decreased due to adsorption of the transferring ion on the pore wall; this decrease was more marked as the scan rate was increased. There was also a shift in the half-wave potential to lower values following adsorption, consistent with a wall adsorption process which provides a further driving force to transfer ions across the ITIES. Of particular interest was the disappearance of the reverse peak from the cyclic voltammogram at higher scan rates, compared to the increase in the reverse peak size in the absence of wall adsorption. This occurred for scan rates of 50 mV s(-1) and above and may be useful in biosensor applications using micropore-based ITIES.

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

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.

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.

A new strategy for 2,4,6-Trinitrotoluene adsorption and electrochemical reduction on poly(melamine)/graphene oxide modified electrode

International Nuclear Information System (INIS)

Cotchim, Suparat; Thavarungkul, Panote; Kanatharana, Proespichaya; Limbut, Warakorn

2015-01-01

Highlights: • A new fabrication strategy of a poly(melamine)/graphene oxide (PM/GO) modified glassy carbon electrode (GCE) (PM/GO/GCE) for the detection of ultra-traces of TNT is proposed. • The PM/GO/GCE exhibits excellent adsorption and electrochemical reduction of TNT via the AdCSV technique. • The PM/GO/GCE provides for a high sensitivity, good repeatability and selectivity. • This strategy opens new opportunities for the sensitive detection of TNT aiming at protection of the environmental and homeland securities. - Abstract: A poly(melamine)/graphene oxide (PM/GO) layer modified on a glassy carbon electrode (GCE) was used for the adsorption and electrochemical detection of 2,4,6 trinitrotoluene (TNT). The surface morphology and electrochemical behaviour of the PM/GO/GCE were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV) and adsorptive cathodic stripping voltammetry (AdCSV). The PM/GO/GCE exhibited excellent adsorption and electrochemical reduction of TNT via the AdCSV technique with two linear ranges, 1–90 μg L −1 and 100–1000 μg L −1 , a detection limit of 0.34 μg L −1 and a quantitation limit of 1.14 μg L −1 . The PM/GO/GCE provided for a high sensitivity, good repeatability and selectivity. This modified electrode was successfully applied to detect TNT in soil samples with good recoveries that ranged from 93 to 99%.

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.

Comparative voltammetric study and determination of carbamate pesticide residues in soil at carbon nanotubes paste electrodes

Directory of Open Access Journals (Sweden)

THOMMANDRU RAVEENDRANATH BAB

2014-02-01

Full Text Available In this investigation, the persistence of carbamate pesticides in soil samples was investigated. A simple and selective differential pulse adsorptive stripping voltammetry was selected for this investigation. Carbon nanotubes paste electrodes were used as working electrodes for differential pulse adsorptive stripping voltammetry and cyclic voltammetry. A symmetric study of the various operational parameters that affect the stripping response was carried out by differential pulse voltammetry. Peak currents were linear over the concentration range of 10-5 to 10-10 M with an accumulation potential of -0.6 V and a 70 s accumulation time with lower detection limits of 1.09 x 10-7 M, 1.07 × 10-7M, 1.09×10-7 M for chlorphropham, thiodicarb, aldicarb. The relative standard deviation (n=10 and correlation coefficient values were 1.15 %, 0.988; 1.13 %, 0.978; and 1.14 %, 0.987, respectively. Universal buffer with pH range 2.0 - 6.0 was used as sup­porting electrolyte. The solutions with uniform concentration (10-5 M were used in all deter­minations. Calculations were made by standard addition method.

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

Science.gov (United States)

Jiang, Chuanjia; Hsu-Kim, Heileen

2014-11-01

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

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

Adsorptive Stripping Voltammetric Determination of Amaranth and Tartrazine in Drinks and Gelatins Using a Screen-Printed Carbon Electrode

Directory of Open Access Journals (Sweden)

Yeny Perdomo

2017-11-01

Full Text Available A fast, sensitive, and selective method for the simultaneous determination of one pair of synthetic colorants commonly found mixed in food products, Amaranth (AM and Tartrazine (TZ, based on their adsorption and oxidation on a screen-printed electrode (SPE is presented. The variation of peak current with pH, supporting electrolyte, adsorption time, and adsorption potential were optimized using square wave adsorptive voltammetry. The optimal conditions were found to be: pH 3.2 (PBS, Eads 0.00 V, and tads 30 s. Under these conditions, the AM and TZ signals were observed at 0.56 and 0.74 V, respectively. A linear response were found over the 0.15 to 1.20 µmol L−1 and 0.15 to 0.80 µmol L−1 concentrations, with detection limits (3σ/slope of 26 and 70 nmol L−1 for AM and TZ, respectively. Reproducibility for 17.7 µmol L–1 AM and TZ solutions were 2.5 and 3.0% (n = 7, respectively, using three different electrodes. The method was validated by determining AM and TZ in spiked tap water and unflavored gelatin spiked with AM and TZ. Because a beverage containing both AM and TZ was not found, the method was applied to the determination of AM in a kola soft drink and TZ in an orange jelly and a soft drink powder.

Adsorptive Stripping Voltammetric Determination of Amaranth and Tartrazine in Drinks and Gelatins Using a Screen-Printed Carbon Electrode

Science.gov (United States)

Perdomo, Yeny; Arancibia, Verónica; Nagles, Edgar

2017-01-01

A fast, sensitive, and selective method for the simultaneous determination of one pair of synthetic colorants commonly found mixed in food products, Amaranth (AM) and Tartrazine (TZ), based on their adsorption and oxidation on a screen-printed electrode (SPE) is presented. The variation of peak current with pH, supporting electrolyte, adsorption time, and adsorption potential were optimized using square wave adsorptive voltammetry. The optimal conditions were found to be: pH 3.2 (PBS), Eads 0.00 V, and tads 30 s. Under these conditions, the AM and TZ signals were observed at 0.56 and 0.74 V, respectively. A linear response were found over the 0.15 to 1.20 µmol L−1 and 0.15 to 0.80 µmol L−1 concentrations, with detection limits (3σ/slope) of 26 and 70 nmol L−1 for AM and TZ, respectively. Reproducibility for 17.7 µmol L–1 AM and TZ solutions were 2.5 and 3.0% (n = 7), respectively, using three different electrodes. The method was validated by determining AM and TZ in spiked tap water and unflavored gelatin spiked with AM and TZ. Because a beverage containing both AM and TZ was not found, the method was applied to the determination of AM in a kola soft drink and TZ in an orange jelly and a soft drink powder. PMID:29156561

Adsorptive Stripping Voltammetric Determination of Amaranth and Tartrazine in Drinks and Gelatins Using a Screen-Printed Carbon Electrode.

Science.gov (United States)

Perdomo, Yeny; Arancibia, Verónica; García-Beltrán, Olimpo; Nagles, Edgar

2017-11-18

A fast, sensitive, and selective method for the simultaneous determination of one pair of synthetic colorants commonly found mixed in food products, Amaranth (AM) and Tartrazine (TZ), based on their adsorption and oxidation on a screen-printed electrode (SPE) is presented. The variation of peak current with pH, supporting electrolyte, adsorption time, and adsorption potential were optimized using square wave adsorptive voltammetry. The optimal conditions were found to be: pH 3.2 (PBS), E ads 0.00 V, and t ads 30 s. Under these conditions, the AM and TZ signals were observed at 0.56 and 0.74 V, respectively. A linear response were found over the 0.15 to 1.20 µmol L -1 and 0.15 to 0.80 µmol L -1 concentrations, with detection limits (3σ/slope) of 26 and 70 nmol L -1 for AM and TZ, respectively. Reproducibility for 17.7 µmol L -1 AM and TZ solutions were 2.5 and 3.0% ( n = 7), respectively, using three different electrodes. The method was validated by determining AM and TZ in spiked tap water and unflavored gelatin spiked with AM and TZ. Because a beverage containing both AM and TZ was not found, the method was applied to the determination of AM in a kola soft drink and TZ in an orange jelly and a soft drink powder.

Adsorptive Stripping Determination of Trace Nickel Using Bismuth Modified Mesoporous Carbon Composite Electrode

Science.gov (United States)

Ouyang, Ruizhuo; Feng, Kai; Su, Yongfu; Zong, Tianyu; Zhou, Xia; Lei, Tian; Jia, Pengpeng; Cao, Penghui; Zhao, Yuefeng; Guo, Ning; Chang, Haizhou; Miao, Yuqing; Zhou, Shuang

Novel bismuth nanoparticle-modified mesoporous carbon (MPC) was successfully prepared on a glassy carbon electrode (Bi@MPC/GCE) for the adsorptive stripping voltammetric determination of nickel by complexing with dimethylglyoxime (DMG). The presence of MPC obviously improved the properties of Bi particles like the electron transfer ability, particle size and hydrophicility, important parameters to achieve preferable analytical performances of Bi@MPC/GCE toward Ni(II). The best electrochemical behaviors of Bi@MPC/GCE was obtained for the stripping determination of Ni(II), compared with electrodes individually modified with Bi and MPC. The synergic effect between metallic Bi and ordered MPC (forming a 3D array like Bi microelectrodes) made major contribution to such improved electrochemical properties of Bi@MPC/GCE for Ni(II) sensing. The good linear analytical curve was achieved in a Ni(II) concentration range from 0.1μM to 5.0μM with a correlation coefficient of 0.9995. The detection limit and sensitivity were calculated to be 1.2nM (S/N=3) and 1410μAmM-1cm-2, respectively. The new method was successfully applied to Ni(II) determination in soybean samples with recoveries higher than 99% and proved to be a simple, efficient alternative for Ni(II) monitoring in real samples.

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.

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...

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.

An insight into the adsorption and electrochemical processes occurring during the analysis of copper and lead in wines, using an electrochemical quartz crystal nanobalance.

Science.gov (United States)

Yamasaki, Alzira; Oliveira, João A B P; Duarte, Armando C; Gomes, M Teresa S R

2012-08-30

Copper and lead in wine were quantified by anodic stripping voltammetry (ASV), performed onto the gold electrode of a piezoelectric quartz crystal. Both current or mass changes could be used as analytical signals, without a statistical difference in the results (α=0.05). However, the plot of mass vs. potential provided an in depth understanding of the electrochemical processes and allowed studying adsorption phenomena. Copper interaction with fructose is an example of a process which was not possible to ignore by observing the mass change on the gold electrode of the piezoelectric quartz crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Sensitive Adsorptive Voltammetric Method for Determination of Bisphenol A by Gold Nanoparticle/Polyvinylpyrrolidone-Modified Pencil Graphite Electrode

Directory of Open Access Journals (Sweden)

Yesim Tugce Yaman

2016-05-01

Full Text Available A novel electrochemical sensor gold nanoparticle (AuNP/polyvinylpyrrolidone (PVP modified pencil graphite electrode (PGE was developed for the ultrasensitive determination of Bisphenol A (BPA. The gold nanoparticles were electrodeposited by constant potential electrolysis and PVP was attached by passive adsorption onto the electrode surface. The electrode surfaces were characterized by electrochemical impedance spectroscopy (EIS and scanning electron microscopy (SEM. The parameters that affected the experimental conditions were researched and optimized. The AuNP/PVP/PGE sensor provided high sensitivity and selectivity for BPA recognition by using square wave adsorptive stripping voltammetry (SWAdSV. Under optimized conditions, the detection limit was found to be 1.0 nM. This new sensor system offered the advantages of simple fabrication which aided the expeditious replication, low cost, fast response, high sensitivity and low background current for BPA. This new sensor system was successfully tested for the detection of the amount of BPA in bottled drinking water with high reliability.

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.

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

Electrocatalytic oxidative determination of reserpine at electrochemically functionalized single walled carbon nanotube with polyaniline

International Nuclear Information System (INIS)

Dar, Riyaz Ahmad; Naikoo, Gowhar Ahmad; Pitre, Krishna Sadashive

2013-01-01

Graphical abstract: Electrode oxidation mechanism of reserpine at PANI modified-SWCNT/CPE. -- Highlights: • Electropolymerization of polyaniline at SWCNT/CPE. • CV, EIS, CC SEM techniques were used for characterization of electrode. • Electrode showed electrocatalytic activity towards anodic oxidation of reserpine. • Oxidation process as irreversible and adsorption-controlled. • Reserpine in bark of Rauwolfia serpentina and in its pharmaceutical formulations. -- Abstract: In the present work a polyaniline film was successfully deposited by electropolymerization on single walled carbon nanotube paste electrode. The electrode was characterized using cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and scanning electron microscopy. The modified electrode showed electrocatalytic behaviour towards the anodic oxidation of reserpine. The adsorptive stripping voltammetric behaviour of reserpine at polyaniline film modified single walled carbon nanotube paste electrode (modified-SWCNTPE) was investigated and validated in pharmaceuticals and biological fluids by cyclic voltammetry (CV) and adsorptive stripping differential pulse voltammetry (AdSDPV) in 0.02 M phosphate buffer in the pH range of 2.5–8.5. Cyclic voltammetry has shown that the oxidation process is irreversible over the pH range studied and exhibited an adsorption-controlled behaviour. Further, the overall electrode process is mainly diffusion controlled with adsorption effects. The proposed more sensitive AdSDPV method allow quantitation over the range 0.085 μg mL −1 to 0.87 μg mL −1 with the detection limit of 0.407 ng mL −1 and has been successfully used to determine reserpine in bark of Rauwolfia serpentina and in its pharmaceutical formulations

Adsorptive accumulation in constant current stripping chronopotentiometry as an alternative for the electrochemical study of metal complexation by thiol–containing peptides

Czech Academy of Sciences Publication Activity Database

Serrano, N.; Šestáková, Ivana; Diaz-Cruz, J. M.; Arino, C.

2006-01-01

Roč. 591, č. 1 (2006), s. 105-117 ISSN 0022-0728 R&D Projects: GA MŠk OC D21.002 Grant - others:Spanish Ministry of Science and Technology(ES) BQU2003-07587-C02-01; Generalitat de Catalunya(ES) 2001SGR-00056 Institutional research plan: CEZ:AV0Z40400503 Keywords : stripping chronopotentiometry * adsorptive accumulation * phytochelatins * glutathione Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.339, year: 2006

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

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

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.

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.

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.

Comparative Studies of the Speciation Patterns of Nickel and ...

African Journals Online (AJOL)

Results of speciation stdies of nickel and chromium in wastewater, surface and groundwater systems using flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS) and differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) are presented. Dimethylglyoxime ...

Cd, Pb and Cu in spring waters of the Sibylline Mountains National Park (Central Italy, determined by square wave anodic stripping voltammetry

Directory of Open Access Journals (Sweden)

Truzzi C.

2013-04-01

Full Text Available Square wave anodic stripping voltammetry (SWASV was used to determine Cd, Pb and Cu in spring waters of the Sibylline Mountains National Park, Central Italy. Samples were collected from three different areas of the Park (Mount Bove North, Mount Bove South and Springs of River Nera during the period 2004-2011. Physical-chemical parameters were also determined to obtain a general characterization of the waters. Very low metal concentrations were observed (i.e., Cd 1.3±0.4 ng L-1, Pb 13.8±5.6 ng L-1, Cu 157±95 ng L-1, well below the legal limits and also below the medians of known Italian and European data. Comparing the three areas it was noted that waters from the area of the Nera Springs are the poorest in heavy metals and the richest in minerals, that conversely the waters of Mt. Bove North are the richest in heavy metals and the poorest in mineral salts, and finally that intermediate values both for heavy metals and mineral salts were observed for the waters of Mt. Bove South.

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

Cascade air stripping: Techno-economic evaluation of a new ground water treatment process

International Nuclear Information System (INIS)

Nirmalakhandan, N.; Peace, G.L.; Shanbhag, A.R.; Speece, R.E.

1992-01-01

A simple modification of the conventional air-stripping process introduced as cascade air stripping is proposed for efficient and economical removal of semivolatile and low volatility contaminants from ground water. The technical feasibility and economic viability of this process are evaluated using field test results and cost model simulations. The field tests enabled the process model to be verified at various water flow rates ranging from 150 gpm to 400 gpm. The field study also demonstrated the feasibility of the proposed system at a near full-scale level. Cost models were used to compare the proposed process to conventional air stripping and granular-activated carbon adsorption in removing a range of contaminants. This analysis showed that the treatment cost (cents/1,000 gal) of cascade air stripping is about 15% lower than conventional air stripping and about 40% lower than granular-activated carbon adsorption

Highly sensitive determination of mercury using copper enhancer by diamond electrode coupled with sequential injection–anodic stripping voltammetry

Energy Technology Data Exchange (ETDEWEB)

Chaiyo, Sudkate [Department of Chemistry, Faculty of Science, Srinakharinwirot University (Thailand); Chailapakul, Orawon [Department of Chemistry, Faculty of Science, Chulalongkorn University (Thailand); Center for Petroleum, Petrochemicals, and Advanced Materials, Chulalongkorn University (Thailand); Siangproh, Weena, E-mail: weena@swu.ac.th [Department of Chemistry, Faculty of Science, Srinakharinwirot University (Thailand)

2014-12-10

Highlights: • Highly sensitive determination of Hg(II) using SI–ASV-BDD was achieved. • Electrochemical detection of Hg(II) using Cu(II) enhancer was accomplished. • LOD and LOQ were found to be very low at 40.0 ppt and 135.0 ppt. • This method was successfully applied for determination of Hg(II) in real samples. - Abstract: A highly sensitive determination of mercury in the presence of Cu(II) using a boron-doped diamond (BDD) thin film electrode coupled with sequential injection–anodic stripping voltammetry (SI–ASV) was proposed. The Cu(II) was simultaneously deposited with Hg(II) in a 0.5 M HCl supporting electrolyte by electrodeposition. In presence of an excess of Cu(II), the sensitivity for the determination of Hg(II) was remarkably enhanced. Cu(II) and Hg(II) were on-line deposited onto the BDD electrode surface at −1.0 V (vs. Ag/AgCl, 3 M KCl) for 150 s with a flow rate of 14 μL s{sup −1}. An anodic stripping voltammogram was recorded from −0.4 V to 0.25 V using a frequency of 60 Hz, an amplitude of 50 mV, and a step potential of 10 mV at a stopped flow. Under the optimal conditions, well-defined peaks of Cu(II) and Hg(II) were found at −0.25 V and +0.05 V (vs. Ag/AgCl, 3 M KCl), respectively. The detection of Hg(II) showed two linear dynamic ranges (0.1–30.0 ng mL{sup −1} and 5.0–60.0 ng mL{sup −1}). The limit of detection (S/N = 3) obtained from the experiment was found to be 0.04 ng mL{sup −1}. The precision values for 10 replicate determinations were 1.1, 2.1 and 2.9% RSD for 0.5, 10 and 20 ng mL{sup −1}, respectively. The proposed method has been successfully applied for the determination of Hg(II) in seawater, salmon, squid, cockle and seaweed samples. A comparison between the proposed method and an inductively coupled plasma optical emission spectrometry (ICP-OES) standard method was performed on the samples, and the concentrations obtained via both methods were in agreement with the certified values of Hg

Factors affecting the simultaneous determination of copper, lead, cadmium, and zinc concentrations in human head hair using differential pulse anodic stripping voltammetry method

International Nuclear Information System (INIS)

Wandiga, S.O.; Jumba, I.O.

1982-01-01

Conditions of analysis of copper, lead, cadmium and zinc content in human hair using differential pulse anodic stripping voltammetry (DPASV) and hanging mercury drop electrode (HMDE) have been established. Sample digestion using using the mixture HCI; H 2 O 2 ;HNO 3 in the ratio 2:1:40 by volume gave the best wet-ashing procedure. The peak currents and peak potentials of zinc, cadmium and lead, copper were maximum at pH 6-7 and 1-3 respectively, when excess H 2 O 2 was eliminated with subsequent addition of hydroxyamine hydrochloride. Matrix concentration effects were minimized by digesting weights not exceeding 50 mg per sample. The effect of selenium (IV) was negligible and was ignored. The detection limit of 0.0036 ng/cm 3 for Cd + 2 was obtained while the values for zinc, lead and copper were 0.0230, 0.0287 and 0.0269 ng/cm 3 respectively at the 95% confidence limit. The observed DPASV condition of analysis of these metals are useful for routine determination of the metals in human hair and should complement the conventional flame absorption spectrophotometry method. (author)

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

Directory of Open Access Journals (Sweden)

Abdul Niaz1,

2008-12-01

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

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

Organic complexation of iron in the West Atlantic Ocean

NARCIS (Netherlands)

Gerringa, L.J.A.; Rijkenberg, M.J.; Schoemann, V.; Laan, P.; de Baar, H.J.W.

2015-01-01

The characteristics of the dissolved iron (DFe) binding organic ligands were determined during 3 Dutch GEOTRACES cruises covering the length of the West Atlantic Ocean. Adsorptive Differential Pulse Cathodic Stripping Voltammetry (AdDPCSV) with TAC as competing ligand was used to measure Fe binding

Biogeochemical speciation of Fe in ocean water

NARCIS (Netherlands)

Hiemstra, T.; Riemsdijk, van W.H.

2006-01-01

The biogeochemical speciation of Fe in seawater has been evaluated using the consistent Non-Ideal Competitive Adsorption model (NICA¿Donnan model). Two types of data sets were used, i.e. Fe-hydroxide solubility data and competitive ligand equilibration/cathodic stripping voltammetry (CLE/CSV) Fe

Fe-Binding Dissolved Organic Ligands in the Oxic and Suboxic Waters of the Black Sea

NARCIS (Netherlands)

Gerringa, L.J.A.; Rijkenberg, M.J.A.; Bown, J.; Margolin, A.R.; Laan, P.; De Baar, H.J.W.

2016-01-01

In the oxygen-rich layer of the Black Sea, above the permanent halocline, the Fe and nitrate concentrations are low where fluorescence is relatively high, indicating uptake by phytoplankton. In this study we used ligand exchange adsorptive cathodic stripping voltammetry (CLE-aCSV), using

Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry

International Nuclear Information System (INIS)

Ammar, Hafedh Belhadj; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef

2016-01-01

The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH 11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2–4.2 μmol L"−"1, with a detection limit of 0.065 μmol L"−"1. - Highlights: • SWV for the determination of MTZ • Boron-doped diamond as a new electrochemical sensor • Simple and rapid detection of MTZ • Efficiency of BDD for sensitive determination of MTZ

Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study.

Science.gov (United States)

Cataldo, Salvatore; Gianguzza, Antonio; Milea, Demetrio; Muratore, Nicola; Pettignano, Alberto

2016-11-01

The adsorption capacity of an activated carbon - calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH=5, in NaCl medium and in the ionic strength range 0.1-0.75molL -1 . Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate (AA-Ca) improves the adsorption capacity (q m ) of active carbon (AC) in the ACAA-Ca adsorbent material (e.g., q m =15.7 and 10.5mgg -1 at I=0.25molL -1 , for ACAA-Ca and AC, respectively). SEM-EDX and thermogravimetric (TGA) measurements were carried out in order to characterize the composite material. The results of the speciation study on the Pb(II) solution and of the characterization of the ACAA-Ca and of the pristine AA-Ca and AC were evaluated in order to explain the specific contribution of AC and AA-Ca to the adsorption of the metal ion. Copyright © 2016 Elsevier B.V. All rights reserved.

Measuring marine iron(III) complexes by CLE-AdSV

NARCIS (Netherlands)

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

2005-01-01

Iron(iii) speciation data, as determined by competitive ligand exchange?adsorptive stripping voltammetry (CLE-AdSV), is reconsidered in the light of the kinetic features of the measurement. The very large stability constants reported for iron(iii) in marine ecosystems are shown to be possibly due to

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

Directory of Open Access Journals (Sweden)

Kowalik R.

2015-04-01

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

Stripping voltammetric behavior of technetium at various chemically modified electrodes

International Nuclear Information System (INIS)

Dick, R.

1990-09-01

In monitoring of nuclear processing plants and storage facilities the necessity arises of assaying traces of the artificial radioactive element technetium. The oxidation states IV and VII are of particular interest. Stripping voltammetry is among the methods of assay which are suited for this purpose. It allows an enhanced selectivity to be achieved by preconcentration of the analyte and of an oxidation state of the analyte, respectively, at the electrode used. This specific enrichment is successful after appropriate chemical modification of the electrode through immobilization of a Tc-specific reagent. When various approaches of chemical modification of a glassy carbon electrode were examined, the tetraphenylarsonium chloride extractant, which is highly selective with respect to technetium, proved to be the best suited reagent, capable of fixation both by ionic and by covalent bonding on an electrodeposited polymer film. For ionic immobilization the reagent was reacted to m-sulfophenyltriphenyl arsonium and then bound to a copolymer of vinylferrocene and vinylpyridine, which had been provided with cations. It was possible to enrich Tc(VII) at such an electrode and to determine it by stripping voltammetry down to a concentration of 1x10 -8 M after 5 minutes enrichment time. (orig./EF) [de

Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry

Energy Technology Data Exchange (ETDEWEB)

Ammar, Hafedh Belhadj, E-mail: hbelhadjammar@yahoo.fr; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef

2016-02-01

The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH 11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2–4.2 μmol L{sup −1}, with a detection limit of 0.065 μmol L{sup −1}. - Highlights: • SWV for the determination of MTZ • Boron-doped diamond as a new electrochemical sensor • Simple and rapid detection of MTZ • Efficiency of BDD for sensitive determination of MTZ.

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.

Factors affecting hydrocarbon removal by air stripping

International Nuclear Information System (INIS)

McFarland, W.E.

1992-01-01

This paper includes an overview of the theory of air stripping design considerations and the factors affecting stripper performance. Effects of temperature, contaminant characteristics, stripping tower geometry and air/water ratios on removal performance are discussed. The discussion includes treatment of groundwater contaminated with petroleum hydrocarbons and chlorinated solvents such as TCE and PCE. Control of VOC emissions from air strippers has become a major concern in recent years, due to more stringent restrictions on air quality in many areas. This paper includes an overview of available technology to control air emissions (including activated carbon adsorption, catalytic oxidation and steam stripping) and the effects of air emission control on overall efficiency of the treatment process. The paper includes an overview of the relative performance of various packing materials for air strippers and explains the relative advantages and disadvantages of comparative packing materials. Field conditions affecting selection of packing materials are also discussed. Practical guidelines for the design of air stripping systems are presented, as well as actual case studies of full-scale air stripping projects

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...

Electrochemical methods for monitoring of environmental carcinogens.

Science.gov (United States)

Barek, J; Cvacka, J; Muck, A; Quaiserová, V; Zima, J

2001-04-01

The use of modern electroanalytical techniques, namely differential pulse polarography, differential pulse voltammetry on hanging mercury drop electrode or carbon paste electrode, adsorptive stripping voltammetry and high performance liquid chromatography with electrochemical detection for the determination of trace amounts of carcinogenic N-nitroso compounds, azo compounds, heterocyclic compounds, nitrated polycyclic aromatic hydrocarbons and aromatic and heterocyclic amines is discussed. Scope and limitations of these methods are described and some practical applications based on their combination with liquid-liquid or solid phase extraction are given.

Membrane air stripping utilizing a plate and frame configuration

International Nuclear Information System (INIS)

Boswell, S.T.

1991-01-01

Membrane air stripping has recently been proposed as a possible method to remove volatile organic chemicals (VOCs) and radon from drinking water supplies. Current and anticipated regulatory requirements, driven by health consequences, make the removal of these contaminants mandatory. This work examines the use of plate and frame membrane air stripping for the removal of VOCs and radon from a water supply. The theoretical basis of membrane air stripping and a literature review are included. The advantages of membrane air stripping versus other methods of removal, as well as the advantages of a plate and frame configuration versus a hollow fiber configuration for membrane air stripping are discussed. Multiple regression/correlation techniques are used to model mass transfer coefficients and fluid resistances. An economic evaluation is performed using the developed models. The costs of comparable membrane and packed tower air stripping systems are 4.86 cents per thousand gallons versus 4.36 cents per thousand gallons, respectively. This work indicates that plate and frame membrane air stripping may, in fact, prove to be an economical alternative to packed tower aeration and carbon adsorption for the removal of VOCs and radon

Method development for the determination of arsenic by sequential injection/anodic stripping voltammetry using long-lasting gold-modified screen-printed carbon electrode.

Science.gov (United States)

Punrat, Eakkasit; Chuanuwatanakul, Suchada; Kaneta, Takashi; Motomizu, Shoji; Chailapakul, Orawon

2013-11-15

An automated method has been developed for determining the concentration of inorganic arsenic. The technique uses sequential injection/anodic stripping voltammetry with a long-lasting gold-modified screen-printed carbon electrode. The long-lasting gold electrode was electrochemically deposited onto a screen-printed carbon electrode at a potential of -0.5 V vs. Ag/AgCl in a supporting electrolyte solution of 1M hydrochloric acid. Under optimal conditions and the applied potentials, the electrode demonstrated that it can be used for a long time without a renewal process. The linear range for the determination of arsenic(III) was 1-100 μg L(-1), and the limit of detection (LOD) in standard solutions was as low as 0.03 μg L(-1) for a deposition time of 120 s and sample volume of 1 mL. This method was used to determine the concentration of arsenic(III) in water samples with satisfactory results. The LOD in real samples was found to be 0.5 μg L(-1). In addition, speciation between arsenic(III) and arsenic(V) has been achieved with the proposed method using deposition potentials of -0.5 V and -1.5 V for the determination of the arsenic(III) concentration and the total arsenic concentration, respectively; the results were acceptable. The proposed method is an automated system that offers a less expensive alternative for determining trace amounts of inorganic arsenic. © 2013 Elsevier B.V. All rights reserved.

Fe (III) speciation in the high nutrient, low chlorophyll Pacific region of the Southern Ocean

NARCIS (Netherlands)

Nolting, R.F.; Gerringa, L.J.A.; Swagerman, M.J.W.; Timmermans, K.R.; Baar, H.J.W. de

1998-01-01

Fe speciation was measured with competitive ligand equilibration adsorptive cathodic stripping voltammetry in the Pacific part of the Southern Ocean between 58° and 68°30′S along the 90°W meridian. The conditional stability constant (K′ with respect to [Fe3+]) was between 10^20.6 and 10^21.6 when

First Electrochemical Method of Nitrothal-Isopropyl Determination in Water Samples

Directory of Open Access Journals (Sweden)

Dariusz Guziejewski

2016-01-01

Full Text Available The aim of the research was the use of square wave adsorptive stripping voltammetry (SWAdSV in conjunction with a hanging mercury drop electrode (HMDE for the determination of nitrothal-isopropyl. It was found that optimal SW technique parameters were frequency, 200 Hz; amplitude, 50 mV; and step potential, 5 mV. Accumulation time and potential were studied to select the optimal conditions in adsorptive stripping voltammetry: 45 s at 0.0 V, respectively. The calibration curve (SWSV was linear in the nitrothal-isopropyl concentration range from 2.0 × 10−7 to 2.0 × 10−6 mol L−1 with detection limit of 3.46 × 10−8 mol L−1. The repeatability of the method was determined at a nitrothal-isopropyl concentration level equal to 6.0 × 10−7 mol L−1 and expressed as RSD = 5.5% (n=6. The proposed method was successfully validated by studying the recovery of nitrothal-isopropyl in spiked environmental samples.

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)

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

Science.gov (United States)

Alghamdi, Ahmad H

2005-01-01

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

Stripping voltammetry of technetium using a TOA modified carbon paste electrode

International Nuclear Information System (INIS)

Ruf, H.; Schorb, K.

1989-10-01

Low concentrations of technetium have been measured DP-stripping-voltammetrically using a carbon paste electrode modified with tri-n-octylamine (TOA-CPE). Preconcentration of the metal ion on the electrode surface accomplished by dipping of the latter in the sample solution which is 2M in HCl, relies on the chemical reaction with the amine acting as a liquid anion exchanger. Both, Tc-IV occurring as the TcCl 6 2- ion in chloride solutions as well as Tc-VII hereby are deposited. Measurements following deposition yield voltammograms of essentially different shapes for the two Tc species. With Tc-IV a characteristic curve with a prominent current signal at -280 mV (vs. Ag/AgCl) is obtained which can be evaluated for Tc quantitation. However, starting from Tc-VII, complex voltammograms are registered not allowing direct technetium assays. Nevertheless, after reduction to Tc-IV, e.g. by means of ascorbic acid, also Tc-VII can be quantified reliably by the method described, the lower detection limit for both oxidation states being about 4x10 -8 M. (orig.) [de

Effect of reduced glutathione, surface active agents, and ionic strength on the detection of metallothioneins by using of Brdicka reaction

Czech Academy of Sciences Publication Activity Database

Křížková, S.; Fabrik, I.; Adam, V.; Kukačka, J.; Průša, R.; Trnková, L.; Strnádel, Ján; Horák, Vratislav; Kizek, R.

2009-01-01

Roč. 21, 3-5 (2009), s. 640-644 ISSN 1040-0397. [International Conference on Electroanalysis /12./. Prague, 16.06.2008-19.06.2008] Grant - others:GA AV ČR(CZ) IAA401990701 Institutional research plan: CEZ:AV0Z50450515 Keywords : differential pulse voltammetry * adsorptive transfer stripping technique * proteins Subject RIV: CG - Electrochemistry Impact factor: 2.630, year: 2009

Insights into the Hydrothermal Stability of Triamine-Functionalized SBA-15 Silica for CO2 Adsorption.

Science.gov (United States)

Jahandar Lashaki, Masoud; Ziaei-Azad, Hessam; Sayari, Abdelhamid

2017-10-23

The hydrothermal stability of triamine-grafted, large-pore SBA-15 CO 2 adsorbents was studied by using steam stripping. Following two 3 h cycles of steam regeneration, lower CO 2 uptakes, lower CO 2 /N ratios, and slower adsorption kinetics were observed relative to fresh samples, particularly at the lowest adsorption temperature (25 °C). CO 2 adsorption measurements for a selected sample exposed to 48 h of steam stripping depicted that after the initial loss during the first exposure to steam (3-6 h), the adsorptive properties stabilized. For higher adsorption temperatures (i.e., 50 and 75 °C), however, all adsorptive properties remained almost unchanged after steaming, indicating the significance of diffusional limitations. Thermogravimetric analysis and FTIR spectroscopy on grafted samples before and after steam stripping showed no amine leaching and no change in the chemical nature of the amine groups, respectively. Also, a six-cycle CO 2 adsorption/desorption experiment under dry conditions showed no thermal degradation. However, N 2 adsorption measurement at 77 K showed significant reductions in the BET surface area of the grafted samples following steaming. Based on the pore size distribution of calcined, grafted samples before and after steaming, it is proposed that exposure to steam restructured the grafted materials, causing mass transfer resistance. It is inferred that triamine-grafted, large-pore SBA-15 adsorbents are potential candidates for CO 2 capture at relatively high temperatures (50-75 °C; for example, flue gas) combined with steam regeneration. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption on smooth electrodes: A radiotracer study

International Nuclear Information System (INIS)

Rice-Jackson, L.M.

1990-01-01

Adsorption on solids is a complicated process and in most cases, occurs as the early stage of other more complicated processes, i.e. chemical reactions, electrooxidation, electroreduction. The research reported here combines the electroanalytical method, cyclic voltammetry, and the use of radio-labeled isotopes, soft beta emitters, to study adsorption processes at smooth electrodes. The in-situ radiotracer method is highly anion (molecule) specific and provides information on the structure and composition of the electric double layer. The emphasis of this research was on studying adsorption processes at smooth electrodes of copper, gold, and platinum. The application of the radiotracer method to these smooth surfaces have led to direct in-situ measurements from which surface coverage was determined; anions and molecules were identified; and weak interactions of adsorbates with the surface of the electrodes were readily monitored. 179 refs

Simultaneous detection of metronidazole and chloramphenicol by differential pulse stripping voltammetry using a silver nanoparticles/sulfonate functionalized graphene modified glassy carbon electrode

International Nuclear Information System (INIS)

Zhai, Haiyun; Liang, Zhixian; Chen, Zuanguang; Wang, Haihang; Liu, Zhenping; Su, Zihao; Zhou, Qing

2015-01-01

Graphical abstract: Display Omitted -- Highlights: • A novel and reliable AgNPs/SF-GR modified glassy carbon electrode was constructed and characterized. • The AgNPs/SF-GR/GCE was successfully applied in the shrimp for simultaneous determination of MTZ and CAP. • Under optimized conditions, common substances such as UA, AA, DA and ion did not interfered in the electrode performance. • The modified electrode exhibited considerable sensitivity, stability and reproducibility. • This fabricated electrode achieved a satisfactory level compared with other electrodes toward MTZ and CAP. -- Abstract: A novel silver nanoparticles/sulfonated functionalized graphene modified glassy carbon electrode (AgNPs/SF-GR/GCE) was fabricated to determine chloramphenicol and metronidazole simultaneously. Taking advantage of sulfonic group, AgNPs were successfully electrodeposited on functionalized GR immobilized on the surface of a GCE. Scanning electron microscopy and energy spectrum analysis results confirmed that AgNPs were deposited on the functionalized GR film. Compared to the bare GCE or the pristine SF-GR modified electrode, AgNPs/SF-GR/GCE exhibited excellent electroreduction towards chloramphenicol and metronidazole. In addition, the two antibacterial drugs were separated completely in 0.10 M citric acid-sodium citrate buffer (pH 4.0) by differential pulse stripping voltammetry under optimum conditions. The cathodic current was linearly related with 0.02∼20.0 μM chloramphenicol and 0.10∼20.0 μM metronidazole, with the detection limits of 0.01 μM and 0.05 μM respectively. Furthermore, AgNPs/SF-GR/GCE was applied to the simultaneous determination of chloramphenicol and metronidazole in an aquatic product

Synthesis of Fe–Cu/TiO2 nanostructure and its use in construction of a sensitive and selective sensor for metformin determination

International Nuclear Information System (INIS)

Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Paimard, Giti; Feyzi, Mostafa; Jafari, Fataneh

2014-01-01

A carbon paste electrode modified with Fe-Cu/TiO 2 was prepared and used for low level determination of metformin (MET) using square wave adsorptive stripping voltammetry (SWAdSV). The Fe-Cu/TiO 2 nanoparticle was synthesized by a modified sol–gel method. The surface structure and composition of nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction analysis (XRD) and N 2 physisorption. Also, electrochemical properties of the prepared nanocomposite modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range of 15 nM to 75 μM MET, with a detection limit of 3 nM. The proposed sensor exhibited a high sensitivity, good selectivity and was successfully applied for MET determination in real samples such as human urine and pharmaceutical formulations. - Highlights: • A carbon paste modified electrode for determination of MET was developed. • The synthesized Fe-Cu/TiO 2 nanocomposite was used as a modifier. • The sensor was successfully applied for MET determination in real samples. • Square wave adsorptive stripping voltammetric method was used for MET determination

Simultaneous Determination of Copper, Lead, and Cadmium Ions at a Mo6S9-xIx Nanowires Modified Glassy Carbon Electrode Using Differential Pulse Anodic Stripping Voltammetry

International Nuclear Information System (INIS)

Lin, Hong; Li, Meixian; Mihailovič, Dragan

2015-01-01

Highlights: • An electrochemical sensor based on Mo 6 S 9-x I x nanowires was constructed. • Mo 6 S 9-x I x nanowires can amplify electrochemical responses of heavy metal ions. • Mo 6 S 9-x I x nanowires can promote electron transfer. • Mo 6 S 9-x I x nanowires can accumulate metal ions due to large surface area. • The preparation of the sensor is simple, short-time and it does not require a special apparatus. -- ABSTRACT: A novel electrochemical sensor based on a new kind of nanomaterials Mo 6 S 9-x I x nanowires modified glassy carbon electrode (GCE) was constructed for simultaneous determination of cadmium(II), lead(II) and copper(II) using differential pulse anodic stripping voltammetry (DPASV). Various experimental parameters such as the modified amount, pH, deposition time and deposition potential were optimized. Under the optimal conditions, the stripping peak currents increase linearly with increasing concentrations of Cd(II), Pb(II) and Cu(II) ions in the ranges of 0.5∼150 μg · L −1 , 1.5∼450 μg · L −1 and 0.8~240 μg · μg·L −1 , 1.5∼450 μg·L −1 and 0.8∼240 μg·L −1 , respectively. And the limits of detection (S/N = 3) are estimated to be 0.10 μg · L −1 for Cd (II), 0.45 μg·L −1 for Pb(II) and 0.20 μg·L −1 for Cu(II), which are two orders of magnitude lower than those obtained at the unmodified electrodes. Most importantly, the sensor has been successfully applied to the determination of trace metal ions in the tap water samples. This developed electrochemical sensor exhibits high sensitivity, good stability and reproducibility

Analytical methods for determination of free metal ion concentration, labile species fraction and metal complexation capacity of environmental waters: a review.

Science.gov (United States)

Pesavento, Maria; Alberti, Giancarla; Biesuz, Raffaela

2009-01-12

Different experimental approaches have been suggested in the last few decades to determine metal species in complex matrices of unknown composition as environmental waters. The methods are mainly focused on the determination of single species or groups of species. The more recent developments in trace elements speciation are reviewed focusing on methods for labile and free metal determination. Electrochemical procedures with low detection limit as anodic stripping voltammetry (ASV) and the competing ligand exchange with adsorption cathodic stripping voltammetry (CLE-AdCSV) have been widely employed in metal distribution studies in natural waters. Other electrochemical methods such as stripping chronopotentiometry and AGNES seem to be promising to evaluate the free metal concentration at the low levels of environmental samples. Separation techniques based on ion exchange (IE) and complexing resins (CR), and micro separation methods as the Donnan membrane technique (DMT), diffusive gradients in thin-film gels (DGT) and the permeation liquid membrane (PLM), are among the non-electrochemical methods largely used in this field and reviewed in the text. Under appropriate conditions such techniques make possible the evaluation of free metal ion concentration.

Reduction of NO adlayers on Pt(110) and Pt(111) in acidic media: evidence for adsorption site-specific reduction

NARCIS (Netherlands)

Rosca, V.; Beltramo, G.L.; Koper, M.T.M.

2005-01-01

We present a combined in situ Fourier transform infrared reflection-absorption spectroscopy and voltammetric study of the reduction of saturated and subsaturated NO adlayers on Pt(111) and Pt(110) single-crystal surfaces in acidic media. The stripping voltammetry experiments and the associated

Differential pulse cathodic stripping voltammetric determination of uranium with arsenazo-III at the hanging mercury dropping electrode

Energy Technology Data Exchange (ETDEWEB)

Kadi, M.W.; El-Shahawi, M.S. [Chemistry Dept., King Abdulaziz Univ., Jeddah (Saudi Arabia)

2009-07-01

An accurate, inexpensive and less laborious controlled adsorptive accumulation of uranium(VI)-arsenazo-III on a hanging mercury drop electrode (HMDE) has been developed for uranium(VI) determination. The method is based upon the collection of uranium(VI)-arsenazo-III complex at pH 5-6 at the HMDE and subsequent direct stripping measurement of the element in the nanomolar concentration level. The cathodic peak current (i{sub p,c}) of the adsorbed complex ions of uranium(VI) was measured at -0.35 V vs. Ag/AgCl reference electrode by differential pulse cathodic stripping voltammetry (DP-CSV), proceeded by an accumulation period of 150s2.5 in Britton-Robinson buffer of pH 5. The plot of the resulting i{sub p,c} vs. uranium(VI) concentration was linear in the range 2.1 x 10{sup -9} to 9.60 x 10{sup -7} mol L{sup -1} uranium(VI) and tended to level off at above 9.6 x 10{sup -7} mol L{sup -1}. The limits of detection and quantification of uranium(VI) were found to be 4.7 x 10{sup -10} and 1.5 x 10{sup -9} mol L{sup -1}, respectively. A relative standard deviation of {+-}2.39% (n = 5) at 8.5 x 10{sup -7} mol L{sup -1} uranium(VI) was obtained. The method was validated by comparing the results with that obtained by ICP-MS method with RSD less than {+-}3.3%. The method was applied successfully for the analysis of uranium in certified reference material (IAEA soil-7), and in phosphate fertilizers. (orig.)

Electrocatalysis and kinetics of the direct alcohol fuel cells. DEMS and ac voltammetry studies

Energy Technology Data Exchange (ETDEWEB)

Othman Mostafa, Ehab Mostafa

2013-01-11

For the direct methanol fuel cell (DMFC) operating at low temperature, the main problem that arises at the anode is its poisoning (deactivation) due to the accumulation of the fuel adsorption product (CO{sub ad}) which can only be oxidized at high potentials (> 0.7 V). For low temperature direct ethanol fuel cells (DEFCs), the main problem that arises at the anode, beside its poisoning by ethanol adsorption products (CO{sub ad} and CH{sub x,ad}), is the incomplete ethanol oxidation due to the difficulty of (C-C) bond breaking. In the previous types of fuel cells, a sluggish oxygen reduction reaction (ORR) kinetics was observed at the cathode which results in a large voltage drop. Such behavior is due to strong inhibition of the cathodic ORR, resulting in high overpotentials and therefore, significant deterioration in the energy conversion efficiency of the cell. The slow kinetic behavior stems from the difficulty of (O=O) bond breaking. In order to model the conditions of continuous oxidation/reduction in a fuel cell, the continuous mass transfer to the electrode surface is necessary. Therefore, mass spectrometry and AC voltammetry measurements presented here were done using the thin layer flow through cell. This thesis aims at a determination of the rate constant of single reaction steps during the oxidation of CO, methanol and ethanol at different platinum surfaces. Towards that aim, I investigated the electrocatalytic oxidation and adsorption rate of methanol (chapter 3) and the electrocatalytic oxidation of ethanol (chapter 4) at different Pt surfaces, using DEMS. In chapter 5, the potential dependence of the bulk and adsorbed methanol oxidation reaction rate (presented by the apparent transfer coefficient, {alpha}') and the corresponding Tafel slope of the reaction have been determined under convection conditions using a potential modulation ac voltammetry technique. Finally, as an application of the method presented in chapter 5, my work in chapter 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)

Voltammetric method to determine chromium (III) in potable water at level of ultra plans

International Nuclear Information System (INIS)

Jimenez B, Irene; Alvarado G, Ana L.

2004-01-01

It was established an analytical methodology to determine Cr (III) in drinking water using a voltammetric technique of Differential Pulse Cathodic Stripping Voltammetry with an Adsorptive Preconcentration of a complex Cr(III)-diethiltriaminpentaceticacid (Cr-DTPA) in a mercury drop. A dissolution of sodium nitrate was used as a supporting electrolyte. The optimized voltammetric parameters were: adsorption time, scan rate, absorption potential, p H, complex agent and sodium nitrate concentration. The linear range of the methodology is between 20 ng/L and 60 ng/L and the detection and quantification limits are 13 ng/L and 20 ng/L respectively. (Author) [es

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.

Synthesis of Fe–Cu/TiO{sub 2} nanostructure and its use in construction of a sensitive and selective sensor for metformin determination

Energy Technology Data Exchange (ETDEWEB)

Gholivand, Mohammad Bagher, E-mail: mbgholivand@yahoo.com; Shamsipur, Mojtaba; Paimard, Giti; Feyzi, Mostafa; Jafari, Fataneh

2014-09-01

A carbon paste electrode modified with Fe-Cu/TiO{sub 2} was prepared and used for low level determination of metformin (MET) using square wave adsorptive stripping voltammetry (SWAdSV). The Fe-Cu/TiO{sub 2} nanoparticle was synthesized by a modified sol–gel method. The surface structure and composition of nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction analysis (XRD) and N{sub 2} physisorption. Also, electrochemical properties of the prepared nanocomposite modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range of 15 nM to 75 μM MET, with a detection limit of 3 nM. The proposed sensor exhibited a high sensitivity, good selectivity and was successfully applied for MET determination in real samples such as human urine and pharmaceutical formulations. - Highlights: • A carbon paste modified electrode for determination of MET was developed. • The synthesized Fe-Cu/TiO{sub 2} nanocomposite was used as a modifier. • The sensor was successfully applied for MET determination in real samples. • Square wave adsorptive stripping voltammetric method was used for MET determination.

Butanol production from wood pulping hydrolysate in an integrated fermentation-gas stripping process.

Science.gov (United States)

Lu, Congcong; Dong, Jie; Yang, Shang-Tian

2013-09-01

Wood pulping hydrolysate (WPH) containing mainly xylose and glucose as a potential substrate for acetone-butanol-ethanol (ABE) fermentation was studied. Due to the inhibitors present in the hydrolysate, several dilution levels and detoxification treatments, including overliming, activated charcoal adsorption, and resin adsorption, were evaluated for their effectiveness in relieving the inhibition on fermentation. Detoxification using resin and evaporation was found to be the most effective method in reducing the toxicity of WPH. ABE production in batch fermentation by Clostridium beijerinckii increased 68%, from 6.73 g/L in the non-treated and non-diluted WPH to 11.35 g/L in the resin treated WPH. With gas stripping for in situ product removal, ABE production from WPH increased to 17.73 g/L, demonstrating that gas stripping was effective in alleviating butanol toxicity by selectively separating butanol from the fermentation broth, which greatly improved solvents production and sugar conversion in the fermentation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Surface area and pore size characteristics of nanoporous gold subjected to thermal, mechanical, or surface modification studied using gas adsorption isotherms, cyclic voltammetry, thermogravimetric analysis, and scanning electron microscopy

Science.gov (United States)

Tan, Yih Horng; Davis, Jason A.; Fujikawa, Kohki; Ganesh, N. Vijaya; Demchenko, Alexei V.

2012-01-01

Nitrogen adsorption/desorption isotherms are used to investigate the Brunauer, Emmett, and Teller (BET) surface area and Barrett-Joyner-Halenda (BJH) pore size distribution of physically modified, thermally annealed, and octadecanethiol functionalized np-Au monoliths. We present the full adsorption-desorption isotherms for N2 gas on np-Au, and observe type IV isotherms and type H1 hysteresis loops. The evolution of the np-Au under various thermal annealing treatments was examined using scanning electron microscopy (SEM). The images of both the exterior and interior of the thermally annealed np-Au show that the porosity of all free standing np-Au structures decreases as the heat treatment temperature increases. The modification of the np-Au surface with a self-assembled monolayer (SAM) of C18-SH (coverage of 2.94 × 1014 molecules cm−2 based from the decomposition of the C18-SH using thermogravimetric analysis (TGA)), was found to reduce the strength of the interaction of nitrogen gas with the np-Au surface, as reflected by a decrease in the ‘C’ parameter of the BET equation. From cyclic voltammetry studies, we found that the surface area of the np-Au monoliths annealed at elevated temperatures followed the same trend with annealing temperature as found in the BET surface area study and SEM morphology characterization. The study highlights the ability to control free-standing nanoporous gold monoliths with high surface area, and well-defined, tunable pore morphology. PMID:22822294

Dependence of adenine isolation efficiency on the chain length evidenced using paramagnetic particles and voltammetry measurements

International Nuclear Information System (INIS)

Huska, Dalibor; Adam, Vojtech; Trnkova, Libuse; Kizek, Rene

2009-01-01

The main aim of this work was to study the dependence of oligoadenine isolation efficiency on the chain length by using paramagnetic particles covered by homo-deoxythymidines ((dT)25) with subsequent detection by adsorptive transfer technique coupled with square wave voltammetry. For this purpose, the oligonucleotides of the length A5, A10, A15, A20, A25, A30, A35, A40 and poly(A) in various concentrations were chosen. We determined that the isolation efficiency defined as 'isolated oligonucleotide concentration'/'given oligonucleotide concentration' was about 55% on average. Sequence A25 demonstrated the best binding onto microparticles surface.

Strip interpolation in silicon and germanium strip detectors

International Nuclear Information System (INIS)

Wulf, E. A.; Phlips, B. F.; Johnson, W. N.; Kurfess, J. D.; Lister, C. J.; Kondev, F.; Physics; Naval Research Lab.

2004-01-01

The position resolution of double-sided strip detectors is limited by the strip pitch and a reduction in strip pitch necessitates more electronics. Improved position resolution would improve the imaging capabilities of Compton telescopes and PET detectors. Digitizing the preamplifier waveform yields more information than can be extracted with regular shaping electronics. In addition to the energy, depth of interaction, and which strip was hit, the digitized preamplifier signals can locate the interaction position to less than the strip pitch of the detector by looking at induced signals in neighboring strips. This allows the position of the interaction to be interpolated in three dimensions and improve the imaging capabilities of the system. In a 2 mm thick silicon strip detector with a strip pitch of 0.891 mm, strip interpolation located the interaction of 356 keV gamma rays to 0.3 mm FWHM. In a 2 cm thick germanium detector with a strip pitch of 5 mm, strip interpolation of 356 keV gamma rays yielded a position resolution of 1.5 mm FWHM

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.

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

Science.gov (United States)

Rodrigues, José A; Rodrigues, Carlos M; Almeida, Paulo J; Valente, Inês M; Gonçalves, Luís M; Compton, Richard G; Barros, Aquiles A

2011-09-09

An improved approach to the anodic stripping voltammetric (ASV) determination of heavy metals, using the hanging mercury drop electrode (HMDE), is reported. It was discovered that using very cathodic accumulation potentials, at which the solvent reduction occurs (overpotential deposition), the voltammetric signals of zinc(II), cadmium(II), lead(II) and copper(II) increase. When compared with the classical methodology a 5 to 10-fold signal increase is obtained. This effect is likely due to both mercury drop oscillation at such cathodic potentials and added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles. Copyright © 2011 Elsevier B.V. All rights reserved.

Quantitative determination of glycyrrhizinic acid by square-wave

Directory of Open Access Journals (Sweden)

Aneta Dimitrovska

2003-06-01

Full Text Available Novel adsorptive stripping square-wave voltammetric method as well as a new high-pressure liquid chromatographic method for direct determination of glycyrrhizinic acid in dosage pharmaceutical preparation, used against virus infections, have been developed. Glycyrrhizinic acid is an electrochemically active compound, which undergoes irreversible reduction on a mercury electrode surface in an aqueous medium. Its redox properties were studied thoroughly by means of square-wave voltammetry, as one of the most advanced electroanalytical technique. The voltammetric response depends mainly on the pH of the medium, composition of the supporting electrolyte, as well as the parameters of the excitement signal. It was also observed that the voltammetric properties strongly depend on the accumulation time and potential, revealing significant adsorption of glycyrrhizinic acid onto the mercury electrode surface. Upon this feature, an adsorptive stripping voltammetric method for quantitative determination of glycyrrhizinic acid was developed. A simple, sensitive and precise reversed phase HPLC method with photodiode array UV detection has also been developed, mainly for comparison and conformation of the results obtained with the voltammetric method.

Cyclic voltammetry, square wave voltammetry, electrochemical impedance spectroscopy and colorimetric method for hydrogen peroxide detection based on chitosan/silver nanocomposite

Directory of Open Access Journals (Sweden)

Hoang V. Tran

2018-05-01

Full Text Available In this paper, we demonstrate a promising method to fabricate a non-enzymatic stable, highly sensitive and selective hydrogen peroxide sensor based on a chitosan/silver nanoparticles (CS/AgNPs hybrid. Using this composite, we elaborated both electrochemical and colorimetric sensors for hydrogen peroxide detection. The colorimetric sensor is based on a homogenous reaction which fades the color of CS/AgNPs solutions from red-orange to colorless depending on hydrogen peroxide concentration. For the electrochemical sensor, CS/AgNPs were immobilized on glassy carbon electrodes and hydrogen peroxide was measured using cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy. The response time is less than 10 s and the detection limit is 5 μM. Keywords: Spectrophotometric detection, Electrochemical impedance spectroscopy, Square wave voltammetry, Cyclic voltammetry, Chitosan/silver nanoparticles (CS/AgNPs hybrid, Hydrogen peroxide

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.

Dependence of adenine isolation efficiency on the chain length evidenced using paramagnetic particles and voltammetry measurements

Energy Technology Data Exchange (ETDEWEB)

Huska, Dalibor [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Adam, Vojtech [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Department of Animal Nutrition and Forage Production, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Trnkova, Libuse [Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Kizek, Rene [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic)], E-mail: kizek@sci.muni.cz

2009-05-15

The main aim of this work was to study the dependence of oligoadenine isolation efficiency on the chain length by using paramagnetic particles covered by homo-deoxythymidines ((dT)25) with subsequent detection by adsorptive transfer technique coupled with square wave voltammetry. For this purpose, the oligonucleotides of the length A5, A10, A15, A20, A25, A30, A35, A40 and poly(A) in various concentrations were chosen. We determined that the isolation efficiency defined as 'isolated oligonucleotide concentration'/'given oligonucleotide concentration' was about 55% on average. Sequence A25 demonstrated the best binding onto microparticles surface.

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

Electrochemical manipulation of localized electrolysis of water: application to determination of gallium by stripping voltammetry

International Nuclear Information System (INIS)

Gopinath, N.; Kamat, J.V.; Aggarwal, S.K.

2003-01-01

A large enhancement in the stripping peak current of gallium disproportionate to the preconcentration deposition potential, more negative than -1.4 V, was observed in 0.005 M HCl electrolyte. It was attributed to the fact that water was electrolysed and an alkaline environment (OH ions) in the vicinity of the Hg drop electrode was generated. As a result, the Ga +3 ions were hydrolysed and gallate ions were in situ produced. The easy-to-reduce gallate ions were involved in the preconcentration step instead of the difficult-to-reduce Ga + 3 ions. Hence there was an increase in the quantity of gallium deposited / dissolved in the Hg drop electrode. Experimental conditions were optimized for the determination of gallium in 0.005 M HCl electrolyte. (author)

Theoretical treatment of high-frequency, large-amplitude ac voltammetry applied to ideal surface-confined redox systems

International Nuclear Information System (INIS)

Bell, Christopher G.; Anastassiou, Costas A.; O’Hare, Danny; Parker, Kim H.; Siggers, Jennifer H.

2012-01-01

Highlights: ► Theory of ac voltammetry on ideal surface-confined redox systems. ► Analytical description of the harmonics and transient of the current response. ► Solution valid for high frequency, large-amplitude sinusoidal input voltage. ► Protocol for determining system parameters from experimental current responses. - Abstract: Large-amplitude ac voltammetry, where the applied voltage is a large-amplitude sinusoidal waveform superimposed onto a dc ramp, is a powerful method for investigating the reaction kinetics of surface-confined redox species. Here we consider the large-amplitude ac voltammetric current response of a quasi-reversible, ideal, surface-confined redox system, for which the redox reaction is described by Butler–Volmer theory. We derive an approximate analytical solution, which is valid whenever the angular frequency of the sine-wave is much larger than the rate of the dc ramp and the standard kinetic rate constant of the redox reaction. We demonstrate how the third harmonic and the initial transient of the current response can be used to estimate parameters of the electrochemical system, namely the kinetic rate constant, the electron transfer coefficient, the adsorption formal potential, the initial proportion of oxidised molecules and the linear double-layer capacitance.

QUANTIFICATION OF LEAD AND CADMIUM IN POULTRY AND BIRD GAME MEAT BY SQUARE WAVE ANODIC STRIPPING VOLTAMMETRY

OpenAIRE

2011-01-01

Abstract A Square Wave Anodic Stripping Voltammetric method for the analysis of lead and cadmium in chicken muscle and liver was developed and validated, and the results of a monitoring study relative to chicken and pigeon meat are reported. The voltammetric method allows the analysis of lead and cadmium at the same time in samples after acid digestion. The use of perchloric acid for digestion and of acetate buffer in the supporting electrolyte have been found suitable to reduce ma...

Interplay of complete wetting, critical adsorption, and capillary condensation.

Science.gov (United States)

Drzewiński, A; Maciołek, A; Barasiński, A; Dietrich, S

2009-04-01

The excess adsorption Gamma in two-dimensional Ising strips (infinityxL), subject to identical boundary fields at both one-dimensional surfaces decaying in the orthogonal direction j as -h1j(-p), is studied for various values of p and along various thermodynamic paths below the bulk critical point by means of the density-matrix renormalization-group method. The crossover behavior between the complete-wetting and critical-adsorption regimes, occurring in semi-infinite systems, is strongly influenced by confinement effects. Along isotherms T=const the asymptotic power-law dependences on the external bulk field, which characterize these two regimes, are pre-empted by capillary condensation. Along the pseudo-first-order phase-coexistence line of the strips, which varies with temperature, we find a broad crossover regime in which both the thickness of the wetting film and Gamma increase as functions of the reduced temperature tau but do not follow any power law. Above the wetting temperature the order-parameter profiles are not slablike but exhibit wide interfacial variations and pronounced tails.

Electro-oxidation of methanol diffused through proton exchange membrane on Pt surface: crossover rate of methanol

International Nuclear Information System (INIS)

Jung, Inhwa; Kim, Doyeon; Yun, Yongsik; Chung, Suengyoung; Lee, Jaeyoung; Tak, Yongsug

2004-01-01

Methanol crossover rate through proton exchange membrane (Nafion 117) was investigated with a newly designed electrochemical stripping cell. Nanosize Pt electrode was prepared by the electroless deposition. Distinct electrocatalytic oxidation behaviors of methanol inside membrane were similar to the methanol oxidation in aqueous electrolyte, except adsorption/desorption of hydrogen. The amount of methanol diffused through membrane was calculated from the charge of methanol oxidation during repetitive cyclic voltammetry (CV) and methanol crossover rate was estimated to be 0.69 nmol/s

REMEDIATION OF MTBE FROM DRINKING WATER: AIR STRIPPING FOLLOWED BY OFF-GAS ADSORPTION

Science.gov (United States)

The widespread use of methyl tertiary butyl ether (MTBE) as an oxygenate in gasoline has resulted in the contamination of a large number of ground and surface water sources. Even though air stripping has been proven to be an effective treatment technology for MTBE removal, off-ga...

Adsorption behavior of ractopamine on carbon nanoparticle modified electrode and its analytical application

International Nuclear Information System (INIS)

Yao Su; Hu Yufei; Li Gongke; Zhang Yukui

2012-01-01

Graphical abstract: - Abstract: In this paper, carbon nanoparticle (CNP) with abundant oxygen-containing groups was prepared. The adsorption behavior of ractopamine on the CNP surface was investigated by electrochemical study. Two oxidative peaks of ractopamine were observed at 0.60 and 0.82 V. The oxidative peaks were distinctly enhanced on the CNP surface and the enhancements were result from the adsorption. The adsorption mechanism was discussed in detail and deduced to be via π–π interaction and salt linkage. The salt linkage between the secondary amide of ractopamine and the carboxyl group on CNP surfaces was confirmed. It provided a novel electron transfer channel for the electrochemical oxidation of phenolic groups. A sensitive differential pulse voltammetry method based on the adsorption was proposed for the determination of ractopamine with the detection limit of 2.0 × 10 −10 mol L −1 . This method was successfully applied to the analysis of ractopamine in urine sample.

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)

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.

Voltammetric technique, a panacea for analytical examination of environmental samples

International Nuclear Information System (INIS)

Zahir, E.; Mohiuddin, S.; Naqvi, I.I.

2012-01-01

Voltammetric methods for trace metal analysis in environmental samples of marine origin like mangrove, sediments and shrimps are generally recommended. Three different electro-analytical techniques i.e. polarography, anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (ADSV) have been used. Cd/sub 2/+, Pb/sub 2/+, Cu/sub 2/+ and Mn/sub 2/+ were determined through ASV, Cr/sub 6/+ was analyzed by ADSV and Fe/sub 2/+, Zn/sub 2/+, Ni/sub 2/+ and Co/sub 2/+ were determined through polarography. Out of which pairs of Fe/sub 2/+Zn/sub 2/+ and Ni/sub 2/+Co/sub 2/+ were determined in two separate runs while Cd/sub 2/+, Pb/sub 2/+, Cu/sub 2/+ were analyzed in single run of ASV. Sensitivity and speciation capabilities of voltammetric methods have been employed. Analysis conditions were optimized that includes selection of supporting electrolyte, pH, working electrodes, sweep rate etc. Stripping voltammetry was adopted for analysis at ultra trace levels. Statistical parameters for analytical method development like selectivity factor, interference, repeatability (0.0065-0.130 macro g/g), reproducibility (0.08125-1.625 macro g/g), detection limits (0.032-5.06 macro g/g), limits of quantification (0.081-12.652 macro g/g), sensitivities (5.636-2.15 nA mL macro g-1) etc. were also determined. The percentage recoveries were found in between 95-105% using certified reference materials. Real samples of complex marine environment from Karachi coastline were also analyzed. The standard addition method was employed where any matrix effect was evidenced. (author)

Analytical electrochemistry of vitamin B12 on a bismuth-film electrode surface

International Nuclear Information System (INIS)

Kreft, Gabriel L.; Braga, Otoniel C. de; Spinelli, Almir

2012-01-01

Cyclic voltammetry (CV) and square wave adsorptive stripping voltammetry (SWAdSV) were used to investigate the performance of an ex situ plated bismuth-film electrode (BiFE) employed to study the electrochemical behavior and the electroanalytical determination of vitamin B 12 . Two pH-dependent reversible peaks were observed for the B 12r –B 12s (Co(II)–Co(I)) couple after pre-concentration of vitamin B 12 at −1.2 V for 30 s. An adsorption-controlled reaction rate with one electron involved in the electrochemical step was observed for the mechanism implicated. The calibration curve obtained in a Britton–Robinson solution at pH 12.0 was linear in the concentration range of 0.100–1.000 μmol L −1 (r = 0.9980). The detection limit was found to be 33.1 nmol L −1 . The electrode was successfully employed for the determination of vitamin B 12 in two pharmaceutical products. The electrode performance was compared with those of modified and unmodified electrodes as well as with the UV–vis spectrophotometric method.

Determination of tellurium in gallium by alternating current stripping voltammetry with a mercury/graphite electrode

International Nuclear Information System (INIS)

Berengard, I.B.; Kaplan, B. Ya.

1986-01-01

The analytical signal in ac stripping coltammetry (ACSV) with mercury indicator electrodes depends on the weight of the electrolytically collected analyte at the electrode surface, the depth of the collection layer being equal to the effective diffusion-layer thickness. Replacement of the static mercury drop electrode (SMDE) by the mercury/graphite electrode (MGE) is of practical interest in that the analyte detection limit can be lowered by decreasing the colume of the telluriumcontaining polarographed solution; in addition, plant laboratories find it difficult to control the SDME uniformity. The work in this article was done on a PU-1 universal polarograph in a square-wave vol tage component mode using the three-electrode cell shown. The rotating mercury/graphite electrode is found by the authors to be superior to the static mercury drop electrode in that it can lower the detection limit for tellurium in gallium to 5.10 /SUP -7percent/ , due to the smaller volume of the polarographed solution

A STUDY ON ADSORPTION AND DESORPTION BEHAVIORS OF 14C FROM A MIXED BED RESIN

Directory of Open Access Journals (Sweden)

SEUNG-CHUL PARK

2014-12-01

Full Text Available Spent resin waste containing a high concentration of 14C radionuclide cannot be disposed of directly. A fundamental study on selective 14C stripping, especially from the IRN-150 mixed bed resin, was carried out. In single ion-exchange equilibrium isotherm experiments, the ion adsorption capacity of the fresh resin for non-radioactive HCO3− ion, as the chemical form of 14C, was evaluated as 11mg-C/g-resin. Adsorption affinity of anions to the resin was derived in order of NO3− > HCO3− ≥ H2PO4−. Thus the competitive adsorption affinity of NO3− ion in binary systems appeared far higher than that of HCO3− or H2PO4−, and the selective desorption of HCO3− from the resin was very effective. On one hand, the affinity of Co2+ and Cs+ for the resin remained relatively higher than that of other cations in the same stripping solution. Desorption of Cs+ was minimized when the summation of the metal ions in the spent resin and the other cations in solution was near saturation and the pH value was maintained above 4.5. Among the various solutions tested, from the view-point of the simple second waste process, NH4H2PO4 solution was preferable for the stripping of 14C from the spent resin.

Lignite utilisation for binding of radionuclides and uranium determination by adsorptive stripping chronopotentiometry

International Nuclear Information System (INIS)

Zavodska, L.

2010-01-01

-cupferron on amalgam work electrode with the value of accumulation potential +200 mV (vs. Ag/AgCl). The work includes optimisation of the accumulation and regeneration time, the regeneration potential, the pH value of supporting electrolyte and concentration of used complexing agent (cupferron). The interference impacts of selected cations on uranium determination by means of adsorptive stripping chronopotentiometry (AdSC) have been also studied. The method is linear within the range of up to 50 μg dm -3 , relative standard deviation for 10 μg dm -3 of uranium is 5.2 % (n=10, accumulation time 60 s). Experimentally, the value of limit of detection was determined for uranium (1.2 μg dm -3 ) as well as the value of limit of quantification (3.6 μg dm -3 ). Using AdSC, the content of uranium was successfully determined in the sample of natural mineral water with high content of salts. The newly designed electrochemical method of determining uranium was validated by means of ICP- MS analysis and spectrophotometric determination of uranium with arsenazo III. The AdSC method may be used for uranium monitoring in waters and after potential further optimisation of sample pre-treatment also in sediments and in soil. (author)

Electrocatalytic activity of a mononuclear yttrium(III)–methyl orange complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles for adsorption/desorption of hydrogen

Energy Technology Data Exchange (ETDEWEB)

Shafaie, Fahimeh [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Hadadzadeh, Hassan, E-mail: hadad@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Behnamfar, Mohammad Taghi [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Rudbari, Hadi Amiri [Faculty of Chemistry, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of)

2016-12-01

A new mononuclear yttrium(III) complex, [Y(MO){sub 3}(DMF){sub 3}(H{sub 2}O){sub 2}] (where MO{sup –} is methyl orange anion (4-[(4-dimethylamino)phenyldiazenyl]benzenesulfonate)), was synthesized in an aqueous solution. The complex was characterized by elemental analysis, UV/Vis, FT-IR, and single-crystal X-ray crystallography. The yttrium oxysulfate nanoparticles (Y{sub 2}O{sub 2}SO{sub 4}) were then prepared by calcination of [Y(MO){sub 3}(DMF){sub 3}(H{sub 2}O){sub 2}]. The obtained nanoparticles were characterized by FT-IR, X-ray diffraction analysis (XRD), and field-emission scanning electron microscopy (FE-SEM). The hydrogen adsorption/desorption (H{sub ads}/H{sub des}) behavior of the Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles was studied at a carbon paste electrode (CPE) in H{sub 2}SO{sub 4} by cyclic voltammetry (CV). The recorded voltammograms exhibited a pair of peaks corresponding to the adsorption/desorption of hydrogen for the Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles. The results show a reversible hydrogen adsorption/desorption reaction for both compounds. The voltammograms of the nanoparticles indicate an excellent cycling stability for the adsorption/desorption of hydrogen. In addition, the linear sweep voltammetry (LSV) technique was used to investigate the electrocatalytic activity of both compounds for the hydrogen adsorption reaction. The linear voltammograms of both compounds demonstrate the excellent electrocatalytic activity for the hydrogen adsorption reaction. - Highlights: • Preparation of a new Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles. • Investigation of the H{sub ads}/H{sub des} reaction for both compounds by voltammetry. • Observation of two peaks corresponding to the H{sub ads}/H{sub des} in both compounds. • An excellent cycling stability for the nanoparticles in H{sub 2}SO{sub 4}.

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

2018-04-01

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 nanosheets. The optimal values of the key parameters influencing the method were as follows: scan rate, 6 V/s; 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 with a determination coefficient of 0.99. The limits of detection and quantification were 0.1 and 1.0 μg/mL, 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, such as blood, increased considerably. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pyrolyzed Photoresist Carbon Electrodes for Trace Electroanalysis of Nickel(II

Directory of Open Access Journals (Sweden)

Ligia Maria Moretto

2015-05-01

Full Text Available Novel pyrolyzed photoresist carbon electrodes for electroanalytical applications have been produced by photolithographic technology followed by pyrolysis of the photoresist. A study of the determination of Ni(II dimethylglyoximate (Ni-DMG through adsorptive cathodic stripping voltammetry at an in situ bismuth-modified pyrolyzed photoresist electrode (Bi-PPCE is reported. The experimental conditions for the deposition of a bismuth film on the PPCE were optimized. The Bi-PPCE allowed the analysis of trace concentrations of Ni(II, even in the presence of Co(II, which is the main interference in this analysis, with cathodic stripping square wave voltammograms characterized by well-separated stripping peaks. The calculated limits of detection (LOD were 20 ng∙L−1 for Ni(II alone and 500 ng∙L−1 in the presence of Co(II. The optimized method was finally applied to the analysis of certified spring water (NIST1640a.

Investigation of the suppression effect of polyethylene glycol on copper electroplating by electrochemical impedance spectroscopy

International Nuclear Information System (INIS)

Hung, C.-C.; Lee, W.-H.; Wang, Y.-L.; Chan, D.-Y.; Hwang, G.-J.

2008-01-01

Polyethylene glycol (PEG) is an additive that is commonly used as a suppressor in the semiconductor copper (Cu)-electroplating process. In this study, electrochemical impedance spectroscopy (EIS) was used to analyze the electrochemical behavior of PEG in the Cu-electroplating process. Polarization analysis, cyclic-voltammetry stripping, and cell voltage versus plating time were examined to clarify the suppression behavior of PEG. The equivalent circuit simulated from the EIS data shows that PEG inhibited the Cu-electroplating rate by increasing the charge-transfer resistance as well as the resistance of the adsorption layer. The presence of a large inductance demonstrated the strong adsorption of cuprous-PEG-chloride complexes on the Cu surface during the Cu-electroplating process. Increasing the PEG concentration appears to increase the resistances of charge transfer, the adsorption layer, and the inductance of the electroplating system

A Practical Beginner's Guide to Cyclic Voltammetry

Science.gov (United States)

Elgrishi, Noémie; Rountree, Kelley J.; McCarthy, Brian D.; Rountree, Eric S.; Eisenhart, Thomas T.; Dempsey, Jillian L.

2018-01-01

Despite the growing popularity of cyclic voltammetry, many students do not receive formalized training in this technique as part of their coursework. Confronted with self-instruction, students can be left wondering where to start. Here, a short introduction to cyclic voltammetry is provided to help the reader with data acquisition and…

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-07-01

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

Dynamics of Pseudomonas aeruginosa azurin and its Cys3Ser mutant at single crystal gold surfaces investigated by cyclic voltammetry and atomic force microscopy

DEFF Research Database (Denmark)

Friis, Esben P.; Andersen, Jens Enevold Thaulov; Madsen, Lars Lithen

1997-01-01

Cyclic voltammetry of Pseudomonas aeruginosa azurin on polycrystalline gold is reversible (E0=360mV vs she;50mM ammonium acetate) but the voltammetric signals decay with time constants of about 3x10-3 s-1. No signal is observed for monocrystalline Au(111). Cys3Ser azurin is electrochemically inac...... into the solution, recovering the free Au(111) surface. The cyclic voltammetry and AFM data are consistent with time dependent adsorption of the azurins on gold via the disulphide bridge (wild-type) or free thiol group (Cys3Ser mutant).......Cyclic voltammetry of Pseudomonas aeruginosa azurin on polycrystalline gold is reversible (E0=360mV vs she;50mM ammonium acetate) but the voltammetric signals decay with time constants of about 3x10-3 s-1. No signal is observed for monocrystalline Au(111). Cys3Ser azurin is electrochemically...... inactive on either type of gold electrode but shows a reversible although decaying peak (362mV, 50mM ammonium acetate; decay time constant ~ 2x10-3 s-1) on edge-plane pyrolytic graphite.Ex situ and in situ atomic force microscopy (AFM) of the azurins on Au(111) show initially arrays of protein structures...

Estimation of uranium in drinking water samples collected from different locations across Tarapur, India

International Nuclear Information System (INIS)

Dusane, C.B.; Maity, Sukanta; Sahu, S.K.; Pandit, G.G.

2015-01-01

In this study, drinking water samples were collected from different locations across Tarapur, India for screening uranium contents. Uranium concentrations were determined by differential pulse adsorptive stripping voltammetry (DPASV). Uranium concentration in water samples varied in a wide range from 0.6-7.9 μg L -1 . Results were compared with the international water quality guidelines World Health Organization (WHO, 2011) and were found within the permissible limit. Results were also compared with the safe limit values for drinking water recommended by national organization like Atomic Energy Regulatory Board (AERB). (author)

Avaliação da labilidade de alumínio em infusões de erva-mate empregando voltametria adsortiva de redissolução catódica

Directory of Open Access Journals (Sweden)

Bruna Kauely de Campos

2014-01-01

Full Text Available Infusions of yerba mate obtained at different stages of industrialization were evaluated to determine the bioavailable fraction of Al. Adsorptive Cathodic Stripping Voltammetry using DASA (complexing agent was applied to determine the labile fraction of Al at pH 5.0 and pH 8.0 for the total fraction of dissolved Al. The results indicate that on average 60% of Al is complexed with organic compounds, minimizing their bioavailability; however, the labile fraction exceeds by up to 4 times the maximum weekly intake recommended by the World Health Organization.

Investigation of Mercury Reduction in Gold Stripping Process at Elevated Temperature

Science.gov (United States)

Pramudya, Irawan

Mercury is present in many gold ores. By processing these ores, there is a potential of emitting mercury to the environment. Carbon regeneration kiln stacks have been observed as one of the primary source of mercury emission into the atmosphere. Before it is recycled back into the carbon in leach (CIL) or carbon in columns (CIC), carbon used in the gold extraction process needs to be reactivated thermally. Emission of mercury can be minimized by keeping the mercury left in the carbon low before it goes to the carbon regeneration kiln stacks. The objective of this study is establishing the optimum elution conditions of mercury cyanide from loaded carbon (which includes the eluent, concentration, temperature and elution time) with respect to gold stripping. Several methods such as acid washing (UNR-100, HCl or ethanol/UNR-100) were investigated prior to the stripping process. Furthermore, conventional pressurized Zadra and modified Zadra were also studied with regards to mercury concentration in the solution and vapor state as well as maximizing the gold stripping from industrial loaded carbon. 7% UNR-100 acid washing of loaded carbon at 80°C was able to wash out approximately 90% of mercury while maintaining the gold adsorption on the carbon (selective washing). The addition of alcohol in the UNR-100 acid washing solution was able to enhance mercury washing from 90% to 97%. Furthermore, mercury stripping using conventional pressurized (cyanide-alkaline) Zadra was best performed at 80°C (minimal amount of mercury reduced and volatilized) whereas using the same process only 40% of gold was stripped, which makes this process not viable. When alcohol was added to the stripping solution, at 80°C, 95% of gold was detected in the solution while keeping the reduction and volatilization of mercury low. The outcome of this study provides a better understanding of mercury behavior during the acid washing and stripping processes so that the risk of mercury exposure and

Activated Carbon Preparation and Modification for Adsorption

Science.gov (United States)

Cao, Yuhe

Butanol is considered a promising, infrastructure-compatible biofuel. Butanol has a higher energy content than ethanol and can be used in conventional gas engines without modifications. Unfortunately, the fermentation pathway for butanol production is restricted by its toxicity to the microbial strains used in the process. Butanol is toxic to the microbes, and this can slow fermentation rates and reduce butanol yields. Gas stripping technology can efficiently remove butanol from the fermentation broth as it is produced, thereby decreasing its inhibitory effects. Traditional butanol separation heavily depends on the energy intensive distillation method. One of the main issues in acetone-butanol-ethanol fermentation is that butanol concentrations in the fermentation broth are low, ranging from 1 to 1.2 percent in weight, because of its toxicity to the microorganisms. Therefore distillation of butanol is even worse than distillation of corn ethanol. Even new separation methods, such as solid- extraction methods involve adding substances, such as polymer resin and zeolite or activated carbon, to biobutanol fermentatioon broth did not achieve energy efficient separation of butanol due to low adsorption selectivity and fouling in broth. Gas-stripping - condensation is another new butanol recovery method, however, the butanol in gas-stripping stream is too low to be condensed without using expensive and energy intensive liquid nitrogen. Adsorption can then be used to recover butanol from the vapor phase. Activated carbon (AC) samples and zeolite were investigated for their butanol vapor adsorption capacities. Commercial activated carbon was modified via hydrothermal H2O2 treatment, and the specific surface area and oxygen-containing functional groups of activated carbon were tested before and after treatment. Hydrothermal H2O 2 modification increased the surface oxygen content, Brunauer-Emmett-Teller surface area, micropore volume, and total pore volume of active carbon

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-09-09

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

Simultaneous extraction and determination of lead, cadmium and copper in rice samples by a new pre-concentration technique: Hollow fiber solid phase microextraction combined with differential pulse anodic stripping voltammetry

Energy Technology Data Exchange (ETDEWEB)

Es' haghi, Zarrin, E-mail: z_eshaghi@pnu.ac.i [Department of Chemistry, Faculty of Sciences, Payame Noor University, Mashhad (Iran, Islamic Republic of); Khalili, Maryam; Khazaeifar, Ali [Department of Chemistry, Faculty of Sciences, Payame Noor University, Mashhad (Iran, Islamic Republic of); Rounaghi, Gholam Hossein [Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

2011-03-30

In the present work, a novel solid phase microextraction (SPME) technique using a hollow fiber-supported sol-gel combined with multi-walled carbon nanotubes, coupled with differential pulse anodic stripping voltammetry (DPASV) was employed in the simultaneous extraction and determination of lead, cadmium and copper in rice. In this technique, an innovative solid sorbent containing mixture of carbon nanotube and a composite microporous compound was developed by the sol-gel method via the reaction of tetraethylorthosilicate (TEOS) with 2-amino-2-hydroxymethyl-propane-1,3-diol (TRIS). The growth process was initiated in basic condition (pH 10-11). Afterward this sol was injected into a polypropylene hollow fiber segment for in situ gelation process. The main factors influencing the pre-concentration and extraction of the metal ions; pH of the aqueous feed solution, extraction time, aqueous feed volume, agitation speed, the role of carbon nanotube reinforcement (as-grown and functionalized MWCNT) and salting effect have been examined in detail. Under the optimized conditions, linear calibration curves were established for the concentration of Cd(II), Pb(II) and Cu(II) in the range of 0.05-500, 0.05-500 and 0.01-100 ng mL{sup -1}, respectively. Detection limits obtained in this way are, 0.01, 0.025 and 0.0073 ng mL{sup -1} for Cd(II), Pb(II) and Cu(II), respectively. The relative standard deviations (RSDs) were found to be less than 5% (n = 5, conc.: 1.0 ng mL{sup -1}).

Optimisation of the conditions for stripping voltammetric analysis at liquid-liquid interfaces supported at micropore arrays: a computational simulation.

Science.gov (United States)

Strutwolf, Jörg; Arrigan, Damien W M

2010-10-01

Micropore membranes have been used to form arrays of microinterfaces between immiscible electrolyte solutions (µITIES) as a basis for the sensing of non-redox-active ions. Implementation of stripping voltammetry as a sensing method at these arrays of µITIES was applied recently to detect drugs and biomolecules at low concentrations. The present study uses computational simulation to investigate the optimum conditions for stripping voltammetric sensing at the µITIES array. In this scenario, the diffusion of ions in both the aqueous and the organic phases contributes to the sensing response. The influence of the preconcentration time, the micropore aspect ratio, the location of the microinterface within the pore, the ratio of the diffusion coefficients of the analyte ion in the organic and aqueous phases, and the pore wall angle were investigated. The simulations reveal that the accessibility of the microinterfaces during the preconcentration period should not be hampered by a recessed interface and that diffusional transport in the phase where the analyte ions are preconcentrated should be minimized. This will ensure that the ions are accumulated within the micropores close to the interface and thus be readily available for back transfer during the stripping process. On the basis of the results, an optimal combination of the examined parameters is proposed, which together improve the stripping voltammetric signal and provide an improvement in the detection limit.

Conditioning of renewable silver amalgam film electrode for the characterization of clothianidin and its determination in selected samples by adsorptive square-wave voltammetry.

Science.gov (United States)

Brycht, Mariola; Skrzypek, Sławomira; Guzsvány, Valéria; Berenji, Janoš

2013-12-15

A new square-wave adsorptive stripping voltammetric (SWAdSV) method was developed for the determination of the neonicotinoid insecticide clothianidin (Clo), based on its reduction at a renewable silver amalgam film electrode (Hg(Ag)FE). The key point of the procedure is the pretreatment of the Hg(Ag)FE by applying the appropriate conditioning potential (-1.70 V vs. Ag/AgCl reference electrode). Under the optimized voltammetric conditions, such pretreatment resulted in the peak for the Clo reduction in Britton-Robinson buffer pH 9.0 at about -0.60 V, which was used for the analytical purpose. The developed SWAdSV procedure made it possible to determine Clo in the concentration range of 6.0×10(-7)-7.0×10(-6) mol L(-1) (LOD=1.8×10(-7) mol L(-1), LOQ=6.0×10(-7) mol L(-1)) and 7.0×10(-6)-4.0×10(-5) mol L(-1) (LOD=1.3×10(-6) mol L(-1), LOQ=4.2×10(-6) mol L(-1)). The repeatability, precision, and the recovery of the method were determined. The effect of common interfering pesticides was also investigated. Standard addition method was successfully applied and validated for the determination of Clo in spiked Warta River water, corn seeds samples, and in corn seeds samples treated with the commercial formulation PONCHO 600 FS. © 2013 Elsevier B.V. All rights reserved.

Model for prediction of strip temperature in hot strip steel mill

International Nuclear Information System (INIS)

Panjkovic, Vladimir

2007-01-01

Proper functioning of set-up models in a hot strip steel mill requires reliable prediction of strip temperature. Temperature prediction is particularly important for accurate calculation of rolling force because of strong dependence of yield stress and strip microstructure on temperature. A comprehensive model was developed to replace an obsolete model in the Western Port hot strip mill of BlueScope Steel. The new model predicts the strip temperature evolution from the roughing mill exit to the finishing mill exit. It takes into account the radiative and convective heat losses, forced flow boiling and film boiling of water at strip surface, deformation heat in the roll gap, frictional sliding heat, heat of scale formation and the heat transfer between strip and work rolls through an oxide layer. The significance of phase transformation was also investigated. Model was tested with plant measurements and benchmarked against other models in the literature, and its performance was very good

Model for prediction of strip temperature in hot strip steel mill

Energy Technology Data Exchange (ETDEWEB)

Panjkovic, Vladimir [BlueScope Steel, TEOB, 1 Bayview Road, Hastings Vic. 3915 (Australia)]. E-mail: Vladimir.Panjkovic@BlueScopeSteel.com

2007-10-15

Proper functioning of set-up models in a hot strip steel mill requires reliable prediction of strip temperature. Temperature prediction is particularly important for accurate calculation of rolling force because of strong dependence of yield stress and strip microstructure on temperature. A comprehensive model was developed to replace an obsolete model in the Western Port hot strip mill of BlueScope Steel. The new model predicts the strip temperature evolution from the roughing mill exit to the finishing mill exit. It takes into account the radiative and convective heat losses, forced flow boiling and film boiling of water at strip surface, deformation heat in the roll gap, frictional sliding heat, heat of scale formation and the heat transfer between strip and work rolls through an oxide layer. The significance of phase transformation was also investigated. Model was tested with plant measurements and benchmarked against other models in the literature, and its performance was very good.

Development of anodic stripping voltametry for the determination of palladium in high level nuclear waste

Energy Technology Data Exchange (ETDEWEB)

Bhardwaj, T. K. [North Carolina State University, Raleigh (United States); Sharma, H. S.; Affarwal, S. K. [Bhabha Atomic Research Centre, Mumbai (India); Jain, P. C. [Meerut College, Meerut (India)

2012-12-15

Deposition potential, deposition time, square wave frequency, rotation speed of the rotating disc electrode, and palladium concentration were studied on a Glassy Carbon Electrode (GCE) in 0.01M HCl for the determination of palladium in High Level Nuclear Waste (HLNW) by anodic stripping voltammetry. Experimental conditions were optimized for the determination of palladium at two different, 10-8 and 10-7 M, levels. Error and standard deviation of this method were under 1% for all palladium standard solutions. The developed technique was successfully applied as a subsidiary method for the determination of palladium in simulated high level nuclear waste with very good precision and high accuracy (under 1 % error and standard deviation).

Voltammetric Determination of Carcinogenic Nitrobiphenyls at a Hanging Mercury Drop Electrode

Directory of Open Access Journals (Sweden)

Jiří Zima

2003-02-01

Full Text Available Differential pulse voltammetry (DPV and adsorptive stripping voltammetry (AdSV at a hanging mercury drop electrode (HMDE was used for the determination of trace amounts of carcinogenic nitrobiphenyls, namely 2-nitrobiphenyl (2-NBP, 3-nitrobiphenyl (3-NBP and 4-nitrobiphenyl (4-NBP within the concentration range from 2.10-8 to 1.10-5 mol⋅L-1 for DPV and from 2.10-9 to 1.10-7 mol⋅L-1 for AdSV using a Britton-Robinson buffer – methanol (1:1 mixture with resulting pH 12 as a base electrolyte. The practical applicability of newly developed methods was verified using model samples of drinking and river water and liquid-liquid extraction for a preliminary separation and preconcentration.

Anodic stripping voltammetric determination of heavy metals in solutions containing humic acids

International Nuclear Information System (INIS)

Labuda, J.; Saur, D.; Neeb, R.

1994-01-01

Various simultaneous effects of humic acids on the current and potential of differential pulse anodic stripping peaks of copper, lead, cadmium and zinc in weakly alkaline and acidic (pH 2) solutions have been investigated and interpreted with regard to metal complexation and the adsorption of humic acid on the mercury electrode. The applicability of the standard additions method for metal quantitation and the experimental conditions for UV-photolysis with a high-pressure mercury lamp have been examined in model as well as real water samples. (orig.)

Determination of Trace Antimony (III by Adsorption Voltammetry at Carbon Paste Electrode

Directory of Open Access Journals (Sweden)

Nongyue He

2005-05-01

Full Text Available This work presents a sensitive method for the determination of trace antimonybased on the antimony-pyrogallol red (PGR adsorption at a carbon paste electrode (CPE.The optimal conditions were to use an electrode containing 25% paraffin oil and 75%high purity graphite powder as working electrode, a 0.10 mol/L HCl solution containing3.0×10-5 mol/L PGR as accumulation medium and a 0.20 mol/L HCl solution aselectrolyte with an accumulation time of 150 s and a reduction time of 60 s at -0.50 Vfollowed with a sweep from -0.50 V to 0.20 V. The mechanism of the electrode reactionwas discussed. Interferences of other metal ions were studied as well. The detection limitwas 1×10-9 mol/L. The linear range was from 2.0×10-9 mol/L to 5.0×10-7 mol/L.Application of the proposed method to the determination of antimony in water andhuman hair samples gave good results.

Stripping analysis of nanomolar perchlorate in drinking water with a voltammetric ion-selective electrode based on thin-layer liquid membrane.

Science.gov (United States)

Kim, Yushin; Amemiya, Shigeru

2008-08-01

A highly sensitive analytical method is required for the assessment of nanomolar perchlorate contamination in drinking water as an emerging environmental problem. We developed the novel approach based on a voltammetric ion-selective electrode to enable the electrochemical detection of "redox-inactive" perchlorate at a nanomolar level without its electrolysis. The perchlorate-selective electrode is based on the submicrometer-thick plasticized poly(vinyl chloride) membrane spin-coated on the poly(3-octylthiophene)-modified gold electrode. The liquid membrane serves as the first thin-layer cell for ion-transfer stripping voltammetry to give low detection limits of 0.2-0.5 nM perchlorate in deionized water, commercial bottled water, and tap water under a rotating electrode configuration. The detection limits are not only much lower than the action limit (approximately 246 nM) set by the U.S. Environmental Protection Agency but also are comparable to the detection limits of the most sensitive analytical methods for detecting perchlorate, that is, ion chromatography coupled with a suppressed conductivity detector (0.55 nM) or electrospray ionization mass spectrometry (0.20-0.25 nM). The mass transfer of perchlorate in the thin-layer liquid membrane and aqueous sample as well as its transfer at the interface between the two phases were studied experimentally and theoretically to achieve the low detection limits. The advantages of ion-transfer stripping voltammetry with a thin-layer liquid membrane against traditional ion-selective potentiometry are demonstrated in terms of a detection limit, a response time, and selectivity.

Electroanalytical Determination of Gemifloxacin Mesylate in Bulk, Tablets and Human Urine Using Gold Nanoparticles Modified Carbon Paste Electrode

Directory of Open Access Journals (Sweden)

Ali Attia

2014-12-01

Full Text Available A simple, precise, inexpensive and sensitive voltammetric method has been developed for the determination of gemifloxacin mesylate (GEM in the presence of tween 80 in the bulk, farmaceutical dosage forms and human urine at gold nanoparticles modified carbon paste electrode (GNCPE. The electrochemical behavior of GEM has been investigated by using cyclic voltammetry (CV and differential pulse voltammetry (DPV techniques. The electrochemical oxidation of GEM was an irreversible process which exhibited adsorption-diffusion controlled process behavior in Britton-Robinson (BR buffer over the entire pH range of values from 2 to 9. The adsorptive stripping response was evaluated as a function of some variables such as pH, type of surfactant, scan rate and accumulation time. The anodic peak current varied linearly over the range from 8.0 × 10-7 to 2.8 × 10-5 M. The limits of detection and quantification were 7.32 × 10-8 M and 2.44 × 10-7 M, respectively. The relative standard deviations and the percentage recoveries were found in the following ranges: 0.58-1.35% and 99.37-101.76%, respectively.

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

Determination of uranium in sea water by adsorptive differential pulse voltametry

International Nuclear Information System (INIS)

Khandekar, R.N.; Raghunath, Radha

1991-01-01

An adsorptive stripping voltametric procedure for direct determination of trace quantities of uranium in sea water has been described. Optimal conditions include pH 6.7, 2 x 10 -5 M 8-hydroxy quinoline (oxine) and collection potential of -0.4V (Vs Ag/AgCl) at hanging mercury drop electrode. With controlled adsorptive accumulation for one minute a detection limit of 2.8 x 10 -10 M uranium is obtained. The response is linear upto 7 x 10 -8 M uranium and the relative standard deviation at 4 x 10 -9 M is 11.5%. The effect of possible interference from other metals has been investigated. (author). 14 refs., 1 tab

Standardization of solvent extraction procedure for determination of uranium in seawater

International Nuclear Information System (INIS)

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

2015-01-01

Solvent extraction procedure using ammonium pyrolidine dithiocarbamate complexing agent in methyl isobutyl ketone organic phase and acid exchange back-extraction is described for the simultaneous quantitative pre-concentration of uranium in seawater followed by its determination by differential pulse adsorptive stripping voltammetry. Solvent extraction time is optimized for extraction of uranium from seawater. Solvent extraction efficiency for uranium in seawater at different pH was carried out. The method gives a recovery of 98 ± 2 % for 400 mL sample at pH 3.0 ± 0.02, facilitating the rapid and interference free analysis of seawater samples. (author)

A ω-mercaptoundecylphosphonic acid chemically modified gold electrode for uranium determination in waters in presence of organic matter.

Science.gov (United States)

Merli, Daniele; Protti, Stefano; Labò, Matteo; Pesavento, Maria; Profumo, Antonella

2016-05-01

A chemically modified electrode (CME) on a gold surface assembled with a ω-phosphonic acid terminated thiol was investigated for its capability to complex uranyl ions. The electrode, characterized by electrochemical techniques, demonstrated to be effective for the determination of uranyl at sub-μgL(-1) level by differential pulse adsorptive stripping voltammetry (DPAdSV) in environmental waters, also in presence of humic matter and other potential chelating agents. The accuracy of the measurements was investigated employing as model probes ligands of different complexing capability (humic acids and EDTA). Copyright © 2016 Elsevier B.V. All rights reserved.

Ultramicroelectrode voltammetry and scanning electrochemical microscopy in room-temperature ionic liquid electrolytes.

Science.gov (United States)

Walsh, Darren A; Lovelock, Kevin R J; Licence, Peter

2010-11-01

The high viscosity and unusual properties of room temperature ionic liquids (RTILs) present a number of challenges when performing steady-state voltammetry and scanning electrochemical microscopy in RTILs. These include difficulties in recording steady-state currents at ultramicroelectrode surfaces due to low diffusion coefficients of redox species and problems associated with unequal diffusion coefficients of oxidised and reduced species in RTILs. In this tutorial review, we highlight the recent progress in the use of RTILs as electrolytes for ultramicroelectrode voltammetry and SECM. We describe the basic principles of ultramicroelectrode voltammetry and SECM and, using examples from the recent literature, we discuss the conditions that must be met to perform steady-state voltammetry and SECM measurements in RTILs. Finally, we briefly discuss the electrochemical insights that can be obtained from such measurements.

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.

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 ...

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

Promotion of the oxidation of carbon monoxide at stepped platinum single-crystal electrodes in alkaline media by lithium and beryllium cations.

Science.gov (United States)

Stoffelsma, Chantal; Rodriguez, Paramaconi; Garcia, Gonzalo; Garcia-Araez, Nuria; Strmcnik, Dusan; Marković, Nenad M; Koper, Marc T M

2010-11-17

The role of alkali cations (Li(+), Na(+), K(+), Cs(+), and Be(2+)) on the blank voltammetric response and the oxidative stripping of carbon monoxide from stepped Pt single-crystal electrodes in alkaline media has been investigated by cyclic voltammetry. A strong influence of the nature of the cation on both the blank voltammetric profile and the CO oxidation is observed and related to the influence of the cation on the specific adsorption of OH on the platinum surface. Especially Li(+) and Be(2+) cations markedly affect the adsorption of OH and thereby have a significant promoting effect on CO(ads) oxidation. The voltammetric experiments suggest that, on Pt(111), the influence of Li(+) (and Be(2+)) is primarily through a weakening of the repulsive interactions between the OH in the OH adlayer, whereas in the presence of steps also, the onset of OH adsorption is at a lower potential, both on steps and on terraces.

Graphite electrodes modified by 8-hydroxyquinolines and its application for the determination of copper in trace levels

Directory of Open Access Journals (Sweden)

Sousa Eliane R. de

2006-01-01

Full Text Available Surface modification by 8-hydroxyquinoline-5-sulfonic acid (8-HQS or 8-hydroxyquinoline (8-HQ on a graphite electrode through irreversible adsorption is reported in this paper. Cyclic voltammetry was used to characterize the surface behavior. The modified surface exhibited an affinity to chelating Cu(II in the solution, forming a Cu(II complex, which was employed for Cu(II trace analysis. Of the metals Zn, Ni, Pb, Co, and Cd, none presented interference until excess concentration of 10 times. Significant interference could be observed from Co(II, Cd(II and Fe(II for an excess concentration of 100 times on the analyte. A differential pulse voltammetry, combined with a preconcentrating-stripping process and a standard addition method was used for the analysis. A detection limit for trace copper determination in water, such as 5.110-9 mol L-1, was obtained.

Determination of picomolar silver concentrations by differential pulse anodic stripping voltammetry at a carbon paste electrode modified with phenylthiourea-functionalized high ordered nanoporous silica gel

International Nuclear Information System (INIS)

Javanbakht, Mehran; Divsar, Faten; Badiei, Alireza; Fatollahi, Fatemeh; Khaniani, Yeganeh; Ganjali, Mohammad Reza; Norouzi, Parviz; Chaloosi, Marzieh; Ziarani, Ghodsi Mohammadi

2009-01-01

This study introduces the design of an anodic stripping voltammetric (ASV) method for the silver ion determination at a carbon paste electrode (CPE), chemically modified with phenylthiourea-nanoporous silica gel (Tu-SBA-15-CPE). The electroanalytical pro includes two steps: preconcentration of metal ions at an electrode surface, followed by quantification of the accumulated species by differential pulse anodic stripping voltammetric methods. Factors affecting the performance of the anodic stripping were investigated, including the modifier quantity in the paste, the electrolyte concentrations, the solution pH and the accumulation potential or time. The most sensitive and reliable electrode contained 10% Tu-SBA-15 and 90% carbon paste. The accumulation potential and time were set at, -200 mV and 300 s, respectively, and the scan rate at 50 mV s -1 in the scan range of -200 to 700 mV. The resulting electrode demonstrated a linear response over range of silver ion concentration of 8.0-80 pmol/L with detection limit (S/N = 3) of 5 pmol/L. The prepared electrodes were used for the silver determination in sea and tap water samples and very good recovery results were obtained. The accuracy was assessed through recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

Determination of picomolar silver concentrations by differential pulse anodic stripping voltammetry at a carbon paste electrode modified with phenylthiourea-functionalized high ordered nanoporous silica gel

Energy Technology Data Exchange (ETDEWEB)

Javanbakht, Mehran [Department of Chemistry, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Nano Science and Technology Research Center, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: mehranjavanbakht@gmail.com; Divsar, Faten [Department of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Badiei, Alireza [School of Chemistry, University College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Fatollahi, Fatemeh [Department of Chemistry, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Khaniani, Yeganeh [School of Chemistry, University College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza; Norouzi, Parviz [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Chaloosi, Marzieh [Department of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Ziarani, Ghodsi Mohammadi [Department of Chemistry, University of Alzahra, Tehran (Iran, Islamic Republic of)

2009-09-30

This study introduces the design of an anodic stripping voltammetric (ASV) method for the silver ion determination at a carbon paste electrode (CPE), chemically modified with phenylthiourea-nanoporous silica gel (Tu-SBA-15-CPE). The electroanalytical pro includes two steps: preconcentration of metal ions at an electrode surface, followed by quantification of the accumulated species by differential pulse anodic stripping voltammetric methods. Factors affecting the performance of the anodic stripping were investigated, including the modifier quantity in the paste, the electrolyte concentrations, the solution pH and the accumulation potential or time. The most sensitive and reliable electrode contained 10% Tu-SBA-15 and 90% carbon paste. The accumulation potential and time were set at, -200 mV and 300 s, respectively, and the scan rate at 50 mV s{sup -1} in the scan range of -200 to 700 mV. The resulting electrode demonstrated a linear response over range of silver ion concentration of 8.0-80 pmol/L with detection limit (S/N = 3) of 5 pmol/L. The prepared electrodes were used for the silver determination in sea and tap water samples and very good recovery results were obtained. The accuracy was assessed through recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

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

METHANOL REMOVAL FROM METHANOL-WATER MIXTURE USING ACTIVATED SLUDGE, AIR STRIPPING AND ADSORPTION PROCESS: COMPARATIVE STUDY

Directory of Open Access Journals (Sweden)

SALAM K. AL-DAWERY

2015-12-01

Full Text Available An experimental research has been carried out in order to examine the removal of methanol from methanol-water mixtures using three different methods; activated sludge; activated carbon and air stripping. The results showed that the methanol was totally consumed by the bacteria as quickly as the feed entered the activated sludge vessel. Air stripping process has a limited ability for removing of methanol due to strong intermolecular forces between methanol and water; however, the results showed that the percentage of methanol removed using air pressure at 0.5 bar was higher than that of using air pressure of 0.25 bar. Removal of methanol from the mixture with a methanol content of 5% using activated carbon was not successful due to the limited capacity of the of the activated carbon. Thus, the activated sludge process can be considered as the most suitable process for the treatment of methanol-water mixtures.

Anodic stripping voltammetric determination of traces of Pb(II) and Cd(II) using a glassy carbon electrode modified with bismuth nanoparticles

International Nuclear Information System (INIS)

Yang, Die; Wang, Liang; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravi

2014-01-01

We report on a glassy carbon electrode modified with bismuth nanoparticles (NanoBiE) for the simultaneous determination Pb 2+ and Cd 2+ by anodic stripping voltammetry. Operational parameters such as bismuth nanoparticles labelling amount, deposition potential, deposition time and stripping parameters were optimized with respect to the determination of Pb 2+ and Cd 2+ in 0.1 M acetate buffer solution (pH 4.5). The NanoBiE gives well-defined, reproducible and sharp stripping peaks. The peak current response increases linearly with the metal concentration in a range of 5.0–60.0 μg L −1 , with a detection limit of 0.8 and 0.4 μg L −1 for Pb 2+ and Cd 2+ , respectively. The morphology and composition of the modified electrode before and after voltammetric measurements were analysed by scanning electron microscopy and energy dispersive X-ray analysis. The NanoBiE was successfully applied to analysis of Pb 2+ and Cd 2+ in real water samples and the method was validated by ICP-MS technique, suggesting that the electrode can be considered as an interesting alternative to the bismuth film electrode for possible use in electrochemical studies and electro analysis. (author)

Determination of uranium in biological objects using adsorption

International Nuclear Information System (INIS)

Zakharova, Eh.A.; Filichkina, O.G.; Pikula, N.P.; Slepchenko, G.B.

2002-01-01

A method of U 6+ (0.0001-0.005 mg/liter) determination in urine using adsorption cathode voltammetry is presented. The signal was measured using supporting 0.01 M KCl + 5 x 10 -5 M oxyquinoline + 1x10 -4 M trilon B at pH 6.8 - 7.0. A stationary mercury film electrode on a silver substrate was restituted mechanically and electrochemically. The interfering matrix effect was eliminated using wet mineralization and calcination of the samples (up to 100 ml) and subsequent isolation of oxyquinolinate complex of uranyl with chloroform. The total error, within which the error falls with the probability p=0.95, is ±33%. A systematic error attributed to partial isolation is eliminated via a correction coefficient equal to 1.3 [ru

Anodic Stripping Voltammetric Detection of Arsenic(III) at Platinum-Iron(III) Nanoparticle Modified Carbon Nanotube on Glassy Carbon Electrode

International Nuclear Information System (INIS)

Shin, Seung Hyun; Hong, Hun Gi

2010-01-01

The electrochemical detection of As(III) was investigated on a platinum-iron(III) nanoparticles modified multiwalled carbon nanotube on glassy carbon electrode(nanoPt-Fe(III)/MWCNT/GCE) in 0.1 M H 2 SO 4 . The nanoPt-Fe(III)/ MWCNT/GCE was prepared via continuous potential cycling in the range from .0.8 to 0.7 V (vs. Ag/AgCl), in 0.1 M KCl solution containing 0.9 mM K 2 PtCl 6 and 0.6 mM FeCl 3 . The Pt nanoparticles and iron oxide were co-electrodeposited into the MWCNT-Nafion composite film on GCE. The resulting electrode was examined by cyclic voltammetry (CV), scanning electron microscopy (SEM), and anodic stripping voltammetry (ASV). For the detection of As(III), the nanoPt-Fe(III)/MWCNT/GCE showed low detection limit of 10 nM (0.75 ppb) and high sensitivity of 4.76 μAμM -1 , while the World Health Organization's guideline value of arsenic for drinking water is 10 ppb. It is worth to note that the electrode presents no interference from copper ion, which is the most serious interfering species in arsenic detection

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.

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/ ...

Carbon Paste Electrode Modified with Carbamoylphosphonic Acid Functionalized Mesoporous Silica: A New Mercury-Free Sensor for Uranium Detection

International Nuclear Information System (INIS)

Yantasee, Wassana; Lin, Yuehe; Fryxell, Glen E.; Wang, Zheming

2004-01-01

This study reports a new approach for developing a uranium (U(VI)) electrochemical sensor that is mercury-free, solid-state, and has less chance for ligand depletion than existing sensors. A carbon-paste electrode modified with carbamoylphosphonic acid self-assembled monolayer on mesoporous silica was developed for uranium detection based on an adsorptive square-wave stripping voltammetry technique. Voltammetric responses for U(VI) detection are reported as a function of pH, preconcentration time, and aqueous phase U(VI) concentration. The uranium detection limit is 25 ppb after 5 minutes preconcentration and improved to 1 ppb after 20 minutes preconcentration. The relative standard deviations are normally less than 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...

Regenerating an Arsenic Removal Iron-Based Adsorptive ...

Science.gov (United States)

The replacement of exhausted, adsorptive media used to remove arsenic from drinking water accounts for approximately 80% of the total operational and maintenance (O/M) costs of this commonly used small system technology. The results of three, full scale system studies of an on-site media regeneration process (Part 1) showed it to be effective in stripping arsenic and other contaminants from the exhausted media. Part 2, of this two part paper, presents information on the performance of the regenerated media to remove arsenic through multiple regeneration cycles (3) and the approximate cost savings of regeneration over media replacement. The results of the studies indicate that regenerated media is very effective in removing arsenic and the regeneration cost is substantially less than the media replacement cost. On site regeneration, therefore, provides small systems with alternative to media replacement when removing arsenic from drinking water using adsorptive media technology. Part 2 of a two part paper on the performance of the regenerated media to remove arsenic through multiple regeneration cycles (3) and the approximate cost savings of regeneration over media replacement.

Removal of semivolatiles from soils by steam stripping. 1. A local equilibrium model

International Nuclear Information System (INIS)

Wilson, D.J.; Clarke, A.N.

1992-01-01

A mathematical model for the in-situ steam stripping of volatile and semivolatile organics from contaminated vadose zone soils at hazardous waste sites is developed. A single steam injection well is modeled. The model assumes that the pneumatic permeability of the soil is spatially constant and isotropic, that the adsorption isotherm of the contaminant is linear, and that the local equilibrium approximation is adequate. The model is used to explore the streamlines and transit times of the injected steam as well as the effects of injection well depth and contaminant distribution on the time required for remediation

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 ex...

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…

Adsorptive stripping voltammetric determination of triprolidine hydrochloride in pharmaceutical tablets.

Science.gov (United States)

Zayed, S I M; Habib, I H I

2005-01-01

The electrochemical behavior of antihistaminic drug, viz. triprolidine hydrochloride (TripCl), at a hanging mercury drop electrode (HMDE) is investigated. Chemical and electrical parameters affecting the adsorptive voltammetric measurements are optimized. Different modes of sweep, viz. direct current DC, normal pulse NP, differential pulse DP and square wave SW modes, over the potential range from -800 to -1400 mV, are used in the presence of 0.04 M Britton-Robinson buffer pH 11, with accumulation time 30 s, scan rate 50 mV/s and pulse amplitude 50 mV. The reduction process is irreversible and involved the transfer of two electrons and two protons. Their responses are linear over the concentration range 15-157 ng/ml with average correlation coefficient 0.9998, while the detection limit is 2.64, 6.24, 8.80 and 2.12 ng/ml for DC, DP, SW and NP mode, respectively. The differential pulse method has been applied successfully for the determination of the drug in Egyptian pharmaceutical preparation with mean recovery 99.55+/-0.67%.

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.…

The Electrodeposition of Cobalt, Iron, and Antimony and their Aluminum Alloys from Room-Temperature Aluminum Chloride 1-Methyl-3-Ethylimidazolium Chloride Molten Salt

National Research Council Canada - National Science Library

Mitchell, John

1997-01-01

.... The plating and stripping of these metals was investigated using cyclic voltammetry, rotating disk and rotating ring-disk electrode voltammetry, controlled potential coulometry, and potential step chronoamperometry...

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...

Nuclear reactor spring strip grid spacer

International Nuclear Information System (INIS)

Patterson, J.F.; Flora, B.S.

1978-01-01

A bimetallic grid spacer is described comprising a grid structure of zircaloy formed by intersecting striplike members which define fuel element openings for receiving fuel elements and spring strips made of Inconel positioned within the grid structure for cooperating with the fuel elements to maintain them in their desired position. A plurality of these spring strips extend longitudinally between sides of the grid structure, being locked in position by the grid retaining strips. The fuel rods, which are disposed in the fuel openings formed in the grid structure, are positioned by means of the springs associated with the spring strips and a plurality of dimples which extend from the zircaloy grid structure into the openings. In one embodiment the strips are disposed in a plurality of arrays with those spring strip arrays situated in opposing diagonal quadrants of the grid structure extending in the same direction and adjacent spring strip arrays in each half of the spacer extending in relatively perpendicular directions. Other variations of the spring strip arrangements for a particular fuel design are disclosed herein

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

Voltammetric determination of mixtures of caffeine and chlorogenic acid in beverage samples using a boron-doped diamond electrode.

Science.gov (United States)

Yardım, Yavuz; Keskin, Ertugrul; Şentürk, Zühre

2013-11-15

Herein, a boron-doped diamond (BDD) electrode that is anodically pretreated was used for the simultaneous determination of caffeine (CAF) and chlorogenic acid (CGA) by cyclic and adsorptive stripping voltammetry. The dependence of peak current and potential on pH, scan rate, accumulation parameters and other experimental variables were studied. By using square-wave stripping mode after 60 s accumulation under open-circuit voltage, the BDD electrode was able to separate the oxidation peak potentials of CAF and CGA present in binary mixtures by about 0.4V in Britton-Robinson buffer at pH 1.0. The limits of detection were 0.107 µg mL(-1) (5.51×10(-7) M) for CAF, and 0.448 µg mL(-1) (1.26×10(-6) M) for CGA. The practical applicability of this methodology was tested in commercially available beverage samples. © 2013 Elsevier B.V. All rights reserved.

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)

Strip casting apparatus and method

Science.gov (United States)

Williams, R.S.; Baker, D.F.

1988-09-20

Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip. 6 figs.

Ruthenium determination by the method of inversion voltammetry on graphite electrode

Energy Technology Data Exchange (ETDEWEB)

Dominova, I G; Kolpakova, N A; Stromberg, A G [Tomskij Politekhnicheskij Inst. (USSR)

1978-12-01

Optimal conditions for determining ruthenium by inversion voltammetry on a graphite electrode are 0.1 M KCl or KNO/sub 3/, pH 2-3, electrolysis potential - 1.0 V. A linear dependence of ruthenium electrodissolution current on its concentration in the solution makes it possible to use inversion voltammetry for determining 5x10/sup -7/ - 1x10/sup -4/ g-ion Ru/l. Ruthenium can be determined in the presence of a large excess of nickel and copper but commensurable amounts of mercury adn platinum metals interfere.

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

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.

Determinação de manganês em material particulado atmosférico de ambientes de trabalho utilizando eletrodo de diamante dopado com boro e voltametria de onda quadrada com redissolução catódica

Directory of Open Access Journals (Sweden)

Felix Fabiana da Silva

2005-01-01

Full Text Available A boron-doped diamond electrode is used for determination of Mn(II in atmospheric particulate matter by square wave cathodic stripping voltammetry. The analytical curve was linear for Mn(II concentrations between 5.0 and 37.5 µg L-1, with quantification limit of 3.6 µg L-1. The precision was evaluated by the relative standard deviation, with values between 5.1% and 9.3%. The electrode is free of adsorption, minimizing memory effects. Samples collected in the workplace atmosphere of a foundry had Mn(II concentrations between 0.4 and 4 µg m-3. No significant differences were observed between the proposed method and inductively coupled plasma optical emission spectroscopy.

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.

The Honeycomb Strip Chamber

International Nuclear Information System (INIS)

Graaf, Harry van der; Buskens, Joop; Rewiersma, Paul; Koenig, Adriaan; Wijnen, Thei

1991-06-01

The Honeycomb Strip Chamber (HSC) is a new position sensitive detector. It consists of a stack of folded foils, forming a rigid honeycomb structure. In the centre of each hexagonal cell a wire is strung. Conducting strips on the foils, perpendicular to the wires, pick up the induced avalanche charge. Test results of a prototype show that processing the signals form three adjacent strips nearest to the track gives a spatial resolution better than 64 μm for perpendicular incident tracks. The chamber performance is only slightly affected by a magnetic field. (author). 25 refs.; 21 figs

Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

Directory of Open Access Journals (Sweden)

Qing Chen

2017-01-01

Full Text Available Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indicates that nitrogen adsorption on shale includes monolayer adsorption, multilayer adsorption, and capillary condensation. Usually, Langmuir isotherm is a monolayer adsorption model for ideal interfaces; BET (Brunauer, Emmett, Teller adsorption isotherm is a multilayer adsorption model based on specific assumptions; Freundlich isotherm is an empirical equation widely applied in liquid phase adsorption. In this study, a new nitrogen adsorption isotherm is applied to simultaneously depict monolayer adsorption, multilayer adsorption, and capillary condensation, which provides more real and accurate representation of nitrogen adsorption on shale. In addition, parameters are discussed in relation to heat of adsorption which is relevant to the shape of the adsorption isotherm curve. The curve fitting results indicate that our new nitrogen adsorption isotherm can appropriately describe the whole process of nitrogen adsorption on shale.

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

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.

Charge collection in silicon strip detectors

International Nuclear Information System (INIS)

Kraner, H.W.; Beuttenmuller, R.; Ludlam, T.; Hanson, A.L.; Jones, K.W.; Radeka, V.; Heijne, E.H.M.

1982-11-01

The use of position sensitive silicon detectors as very high resolution tracking devices in high energy physics experiments has been a subject of intense development over the past few years. Typical applications call for the detection of minimum ionizing particles with position measurement accuracy of 10 μm in each detector plane. The most straightforward detector geometry is that in which one of the collecting electrodes is subdivided into closely spaced strips, giving a high degree of segmentation in one coordinate. Each strip may be read out as a separate detection element, or, alternatively, resistive and/or capacitive coupling between adjacent strips may be exploited to interpolate the position via charge division measrurements. With readout techniques that couple several strips, the numer of readout channels can, in principle, be reduced by large factors without sacrificing the intrinsic position accuracy. The testing of individual strip properties and charge division between strips has been carried out with minimum ionizing particles or beams for the most part except in one case which used alphs particless scans. This paper describes the use of a highly collimated MeV proton beam for studies of the position sensing properties of representative one dimensional strip detectors

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)

Dynamics of ordered-domain formation of DNA fragments on Au(111) with molecular resolution

DEFF Research Database (Denmark)

Wackerbarth, Hainer; Ulstrup, Jens

2004-01-01

KeyWords Plus: SCANNING-TUNNELING-MICROSCOPY; PSEUDOMONAS-AERUGINOSA AZURIN; INTERFACIAL ELECTRON-TRANSFER; SELF-ASSEMBLED MONOLAYERS; SINGLE-CRYSTAL; THIN-FILMS; SURFACES; ELECTROCHEMISTRY; VOLTAMMETRY; ADSORPTION......KeyWords Plus: SCANNING-TUNNELING-MICROSCOPY; PSEUDOMONAS-AERUGINOSA AZURIN; INTERFACIAL ELECTRON-TRANSFER; SELF-ASSEMBLED MONOLAYERS; SINGLE-CRYSTAL; THIN-FILMS; SURFACES; ELECTROCHEMISTRY; VOLTAMMETRY; ADSORPTION...

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.

Using Comic Strips in Language Classes

Science.gov (United States)

Csabay, Noémi

2006-01-01

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

A novel tin-bismuth alloy electrode for anodic stripping voltammetric determination of zinc

International Nuclear Information System (INIS)

Pan, D.; Yin, T.; Qin, W.; Zhang, L.; Zhuang, J.

2012-01-01

We report on a novel tin-bismuth alloy electrode (SnBiE) for the determination of trace concentrations of zinc ions by square-wave anodic stripping voltammetry without deoxygenation. The SnBiE has the advantages of easy fabrication and low cost, and does not require a pre-treatment (in terms of modification) prior to measurements. A study on the potential window of the electrode revealed a high hydrogen overvoltage though a limited anodic range due to the oxidation of tin. The effects of pH value, accumulation potential, and accumulation time were optimized with respect to the determination of trace zinc(II) at pH 5. 0. The response of the SnBiE to zinc(II) ion is linear in the 0.5-25 μM concentration range. The detection limit is 50 nM (after 60 s of accumulation). The SnBiE was applied to the determination of zinc(II) in wines and honeys, and the results were consistent with those of AAS. (author)

Test-beam evaluation of heavily irradiated silicon strip modules for ATLAS Phase-II Strip Tracker Upgrade

CERN Document Server

Blue, Andrew; The ATLAS collaboration

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 7.5x1034cm−2s−1. A consequence of this increased luminosity is the expected radiation damage requiring the tracking detectors to withstand hadron equivalences to over 1x1015 1 MeV neutron equivalent per cm2 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 and CERN SPS test beam facilities to investigate the detailed performance of a strip module with both 2.5cm and 5cm length strips before and after irradiation with 8x1014neqcm−2 protons and a total ionising dose of 37.2MRad. The DURA...

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.

Crystallic silver amalgam--a novel electrode material.

Science.gov (United States)

Danhel, Ales; Mansfeldova, Vera; Janda, Pavel; Vyskocil, Vlastimil; Barek, Jiri

2011-09-21

A crystallic silver amalgam was found to be a suitable working electrode material for voltammetric determination of electrochemically reducible organic nitro-compounds. Optimum conditions for crystal growth were found, the crystal surface was investigated by atomic force microscopy in tapping mode and single crystals were used for the preparation of quasi-cylindrical single crystal silver amalgam electrode (CAgAE). An electrochemical behavior of this alternative electrode material was investigated in aqueous media by direct current voltammetry, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) using 4-nitrophenol as a model compound. Applicable potential windows of the CAgAE were found comparable with those obtained at a hanging mercury drop electrode, providing high hydrogen overpotential, and polished silver solid amalgam electrode. Thanks to the smooth single crystal electrode surface, the effect of the passivation is not too pronounced, direct DPV determination of 100 μmol l(-1) of 4-nitrophenol at CAgAEs in 0.2 mol l(-1) acetate buffer pH 4.8 provides a RSD around 1.5% (n = 15). DPV calibration curves of 4-nitrophenol are linear in the whole concentration range 1-100 μmol l(-1) with a limit of quantification of 1.5 μmol l(-1). The attempt to increase sensitivity by application of AdSV was not successful. The mechanism of 4-nitrophenol reduction at CAgAE was investigated by CV.

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.

Doping as a means to probe the potential dependence of dopamine adsorption on carbon-based surfaces: A first-principles study

Science.gov (United States)

Aarva, Anja; Laurila, Tomi; Caro, Miguel A.

2017-06-01

In this work, we study the adsorption characteristics of dopamine (DA), ascorbic acid (AA), and dopaminequinone (DAox) on carbonaceous electrodes. Our goal is to obtain a better understanding of the adsorption behavior of these analytes in order to promote the development of new carbon-based electrode materials for sensitive and selective detection of dopamine in vivo. Here we employ density functional theory-based simulations to reach a level of detail that cannot be achieved experimentally. To get a broader understanding of carbonaceous surfaces with different morphological characteristics, we compare three materials: graphene, diamond, and amorphous carbon (a-C). Effects of solvation on adsorption characteristics are taken into account via a continuum solvent model. Potential changes that take place during electrochemical measurements, such as cyclic voltammetry, can also alter the adsorption behavior. In this study, we have utilized doping as an indirect method to simulate these changes by shifting the work function of the electrode material. We demonstrate that sp2- and sp3-rich materials, as well as a-C, respond markedly different to doping. Also the adsorption behavior of the molecules studied here differs depending on the surface material and the change in the surface potential. In all cases, adsorption is spontaneous, but covalent bonding is not detected in vacuum. The aqueous medium has a large effect on the adsorption behavior of DAox, which reaches its highest adsorption energy on diamond when the potential is shifted to more negative values. In all cases, inclusion of the solvent enhances the charge transfer between the slab and DAox. Largest differences in adsorption energy between DA and AA are obtained on graphene. Gaining better understanding of the behavior of the different forms of carbon when used as electrode materials provides a means to rationalize the observed complex phenomena taking place at the electrodes during electrochemical oxidation

A review on adsorption refrigeration technology and adsorption deterioration in physical adsorption systems

Energy Technology Data Exchange (ETDEWEB)

Wang, D.C.; Li, Y.H. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Li, D.; Zhang, J.P. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Y.Z. [Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China)

2010-01-15

As one kind of environmentally friendly refrigeration, the adsorption refrigeration has attracted many attentions in resent decades. This paper introduces the researches of adsorption refrigeration systems with the commonly used working pairs, advanced adsorption cycles, heat and mass transfer enhancement and attempts of adsorption refrigeration applications. Poor heat and mass transfer problem is a bottleneck to prevent the improvements of the adsorption refrigeration technique. Two ways to enhance the heat and mass transfer are discussed in this paper. The adsorption deterioration of adsorbent, another obstacle to physical adsorption refrigeration applications, is also pointed out. And the possible reasons and the possible methods are analyzed. (author)

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

Science.gov (United States)

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

2014-07-01

We have developed an eletroanalytical method that employs Cu(2+) solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110μgL(-1) and from 10 to 110μgL(-1) for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5μgL(-1) for mineral oil and 3.4 and 11.2μgL(-1) for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS). Copyright © 2014 Elsevier Ltd. All rights reserved.

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)

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)

Large strip RPCs for the LEPS2 TOF system

Energy Technology Data Exchange (ETDEWEB)

Tomida, N., E-mail: natsuki@scphys.kyoto-u.ac.jp [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Niiyama, M. [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Ohnishi, H. [RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama 351-0198 (Japan); Tran, N. [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047 (Japan); Hsieh, C.-Y.; Chu, M.-L.; Chang, W.-C. [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Chen, J.-Y. [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 30076, Taiwan (China)

2014-12-01

High time-resolution resistive plate chambers (RPCs) with large-size readout strips are developed for the time-of-flight (TOF) detector system of the LEPS2 experiment at SPring-8. The experimental requirement is a 50-ps time resolution for a strip size larger than 100 cm{sup 2}/channel. We are able to achieve 50-ps time resolutions with 2.5×100 cm{sup 2} strips by directly connecting the amplifiers to strips. With the same time resolution, the number of front-end electronics (FEE) is also reduced by signal addition. - Highlights: • Find a way to achieve a good time resolution with a large strip RPC. • 2.5 cm narrow strips have better resolutions than 5.0 cm ones. • The 0.5 mm narrow strip interval shows flat time resolutions between strips. • FEEs directly connected to strips make the signal reflection at the strip edge small. • A time resolution of 50 ps was achieved with 2.5 cm×100 cm strips.

The fabrication and characterization of an ex situ plated lead film electrode prepared with the use of a reversibly deposited mediator metal

International Nuclear Information System (INIS)

Tyszczuk, Katarzyna

2011-01-01

Research highlights: → The lead film electrode prepared with use of the mediator metal was elaborated. → The lead-based sensors were characterized by optical and voltammetric methods. → The adsorptive system of folic acid was employed to investigate a new electrode. → The application of the mediator metal improved properties of a lead film electrode. - Abstract: In this paper an ex situ plated lead film electrode prepared with use of the mediator metal (Zn) was elaborated. The electrochemical method for lead film formation is based on a co-deposition of a metal of interest (Pb) with a reversibly deposited mediator metal (Zn) and then on an oxidation of zinc and further deposition of lead by the appropriate potential. This serves to increase the density of islands of lead atoms, promoting lead film growth. The lead-based sensors were characterized by optical method (atomic force microscopy (AFM)) and as well as cyclic, linear sweep and square wave voltammetry. The adsorptive system of folic acid was employed to investigate the electrochemical characteristics a novel type of lead film electrode. Well-formed stripping peaks and a linear dependence of the stripping current on the folic acid concentration were observed on the lead film electrode prepared with use of the mediator metal while comparative measurements attempted with the lead film electrode prepared without use of the mediator metal were unsuccessful.

Glycolate adsorption at gold and platinum electrodes: A theoretical and in situ spectroelectrochemical study

International Nuclear Information System (INIS)

Delgado, Jose Manuel; Blanco, Raquel; Orts, Jose Manuel; Perez, Juan Manuel; Rodes, Antonio

2010-01-01

The adsorption of glycolate anions at sputtered gold thin-film electrodes was studied in perchloric acid solutions by cyclic voltammetry experiments combined with in situ Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Reflection Absorption Spectroscopy under attenuated total reflection conditions (ATR-SEIRAS). Theoretical harmonic vibrational frequencies and band intensities obtained from B3LYP/LANL2DZ,6-31+G(d) calculations for glycolate species adsorbed on Au clusters with (1 1 1) orientation were used to interpret the experimental spectra. Vibrational data confirm the bidentate bonding of glycolate anions through the oxygen atoms of the carboxylate group, in a bridge configuration with the OCO plane perpendicular to the metal surface. The DFT calculations show no significant effect of the total charge of the metal cluster-adsorbate adduct on the vibrational frequencies of adsorbed glycolate species. The infrared experimental study is extended to platinum films electrochemically deposited onto sputtered gold thin-film electrodes showing the potential-dependent formation of adsorbed CO upon dissociative adsorption of glycolate anions. As in the case of gold, the reversible adsorption of glycolate anions takes place in a bidentate configuration as predicted by DFT calculations for glycolate adsorbed on Pt(1 1 1) clusters. At low glycolic acid concentration, the in situ ATR-SEIRA spectra evidence the formation of adsorbed oxalate as reaction intermediate.

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.

Comparative limnology of strip-mine lakes

Energy Technology Data Exchange (ETDEWEB)

Parsons, J D

1964-01-01

Lakes were classified according to chemical properties. The concentration of the ferric iron oxides was responsible for a reddish-black turbidity which, in turn, played a major role in the thermal stratification of red strip-mine lakes. Owing to the lack of measurable turbidity and as a result of selective absorption of visible solar radiation, other strip-mine lakes appeared blue in color. The annual heat budget and the summer heat budget are essentially equivalent under saline conditions. Regardless of the physical and chemical conditions of the strip-mine lakes, heat income was a function of the circulating water mass. The progressive oxidation and precipitation of the iron oxides is the key to the classification of strip-mine lakes.

Electrocatalytic Oxidation of Hydroxylamine at a Quinizarine Modified Glassy Carbon Electrode: Application to Differential Pulse Voltammetry Detection of Hydroxylamine

OpenAIRE

MAZLOUMARDAKANI, Mohammad; KARAMI, Payam EBRAHIMI

2014-01-01

The electrocatalytic behavior of hydroxylamine was studied on a glassy carbon electrode modified by electrodeposition of quinizarine, using cyclic voltammetry, chronoamperometry, and rotating disk voltammetry as diagnostic techniques. Cyclic voltammetry showed that the catalytic current of the system depends on the concentration of hydroxylamine. The magnitude of the peak current for quinizarine increased sharply in the presence of hydroxylamine and proportional to hydroxylamine conc...

Quantification of lead and cadmium in poultry and bird game meat by square-wave anodic-stripping voltammetry.

Science.gov (United States)

Trevisani, M; Cecchini, M; Taffetani, L; Vercellotti, L; Rosmini, R

2011-02-01

A square-wave anodic-stripping voltammetric method for the analysis of lead and cadmium in chicken muscle and liver was developed and validated, and the results of a monitoring study relative to chicken and pigeon meat are reported. The voltammetric method allows the analysis of lead and cadmium at the same time in samples after acid digestion. The use of perchloric acid for digestion and of acetate buffer in the supporting electrolyte are suitable to reduce matrix interferences and obtain limits of quantification which were below 10 ng g⁻¹ for meat and liver samples. The regression between the analytical signal and the concentration of the target analytes in spiked samples and Certified Reference Materials proved to be linear within the 10-100 ng g⁻¹ range for meat and within the 50-500 ng g⁻¹ range for liver. The analytical method was verified using available Certified Reference Materials BCR-184 (cattle meat) and BCR-185R (cattle liver) as well as with spiked chicken samples. Precision (i.e. repeatability and intermediate precision) and accuracy (percentage recovery and bias) were of the order of 0.3-4.5% for both lead and cadmium The level of lead in muscle was in the range between 6.4 and 59.8 ng g⁻¹ in chickens and between 7.9 and 63.6 ng g⁻¹ in farmed pigeons, whereas it was between 8.0 and 84.4 ng g⁻¹ in chicken liver. The cadmium concentration was 0.4-10.4 ng g⁻¹ in chicken muscle, 10.4-90.6 ng g⁻¹ in chicken liver and 2.2-8.0 ng g⁻¹ in farmed pigeons.

Facilitated ion transfer of protonated primary organic amines studied by square wave voltammetry and chronoamperometry

Energy Technology Data Exchange (ETDEWEB)

Torralba, E. [Departamento de Química Física, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Ortuño, J.A. [Departamento de Química Analítica, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Molina, A., E-mail: amolina@um.es [Departamento de Química Física, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Serna, C. [Departamento de Química Física, Facultad de Química, Universidad de Murcia, Murcia 30100 (Spain); Karimian, F. [Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

2014-05-01

Highlights: • Facilitated ion transfer of organic protonated amines is studied. • Cyclic square wave voltammetry is used as main technique. • Complexation constants and standard ion transfer potentials are determined. • Diffusion coefficients in the organic and aqueous phases are determined. • The goodness of square wave voltammetry as analytical tool is shown. - Abstract: The transfer of the protonated forms of heptylamine, octylamine, decylamine, procaine and procainamide facilitated by dibenzo-18-crown-6 from water to a solvent polymeric membrane has been investigated by using cyclic square wave voltammetry. The experimental voltammograms obtained are in good agreement with theoretical predictions. The values of the standard ion transfer potential, complexation constant and diffusion coefficient in water have been obtained from these experiments, and have been used to draw some conclusions about the lipophilicity of these species and the relative stability of the organic ammonium complexes with dibenzo-18-crown-6. The results have been compared with those provided by linear sweep voltammetry. Calibration graphs were obtained with both techniques. An interesting chronoamperometric method for the determination of the diffusion coefficient of the target ion in the membrane has been developed and applied to all these protonated amines.

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)

Probing the electrochemical properties of TiO{sub 2}/graphene composite by cyclic voltammetry and impedance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yadav, Pankaj [Department of Physics, Marwadi Education Foundation, Rajkot 360003 (India); Pandey, Kavita; Bhatt, Parth [School of Solar Energy, Pandit Deendayal Petroleum University, Gandhinagar 382007 (India); Tripathi, Brijesh, E-mail: brijesh.tripathi@sse.pdpu.ac.in [School of Technology, Pandit Deendayal Petroleum University, Gandhinagar 382007 (India); Pandey, Manoj Kumar; Kumar, Manoj [School of Technology, Pandit Deendayal Petroleum University, Gandhinagar 382007 (India)

2016-04-15

Highlights: • Role of TiO{sub 2}/graphene composite in charge transport within supercapacitors. • DC and AC characterization to investigate voltage dependence of charge transport. • Physical insight into the electrochemistry of electrode–electrolyte interface. - Abstract: This work describes the role of graphene in charge transport and diffusion mechanism at TiO{sub 2}/graphene electrode–electrolyte interface. To explore the mechanism, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used. The CV results depict that TiO{sub 2} and TiO{sub 2}/graphene electrodes behave differently in terms of charge transport and ion adsorption under the steady state conditions. The performance of TiO{sub 2} electrode–electrolyte interface is mainly limited by the charge transport and pseudo-capacitive effects while the response of TiO{sub 2}/graphene electrode–electrolyte interface is mainly dominated by the double layer capacitive effects. The EIS measurement leads to the direct determination of broad range of parameters, i.e. series resistance, charge transport, rate capability and ion diffusion. The experimental results and their analysis will have a significant impact on understanding the role of graphene in the electrochemical response of an electrode–electrolyte interface.

Synthesis and application of ion imprinting polymer coated magnetic multi-walled carbon nanotubes for selective adsorption of nickel ion

Science.gov (United States)

He, Junnan; Shang, Hongzhou; Zhang, Xing; Sun, Xiaoran

2018-01-01

A novel nickel ion imprinted polymers (IIPs) based on multi-walled carbon nanotubes (MWCNTs) were synthesized inverse emulsion system, using chitosan(CS) and acrylic acid as the functional monomers, Ni (II) as the template, and N' N-methylene bis-acrylamide as the cross-linker. The chemical structure and morphological feature of the IIPs were characterized by scanning electron microscopy (SEM), Thermogravimetry (TG), X-ray diffraction (XRD), and Fourier transform infrared spectrometer (FTIR). The studies indicated that the gel layer was well grafted on the surface of MWCNTs. Studies on the adsorption ability of the IIPs, by atomic absorption spectrophotometry, demonstrated that IIPs possessed excellent adsorption and selective ability towards Ni (II), fitting to pseudo second-order kinetic isotherms and with a maximum capacity of 19.86 mg/g, and selectivity factor of 13.09 and 4.42. The electrochemical performance of ion imprinting carbon paste electrode (CPE/IIPs) was characterized by Cyclic voltammetry (CV). Studies have shown that CPE/IIPs showed excellent electrochemical performance.

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

NARCIS (Netherlands)

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

2004-01-01

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

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

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)

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...

Study on lifetime of C stripping foils

International Nuclear Information System (INIS)

Zhang Hongbin; Lu Ziwei; Zhao Yongtao; Li Zhankui; Xu Hushan; Xiao Guoqing; Wang Yuyu; Zhang Ling; Li Longcai; Fang Yan

2007-01-01

The carbon stripping foils can be prepared with the AC and DC arc discharge methods, or even sandwiched with AC-DC alternative layers. The lifetime of the carbon stripping foils of 19 μg/cm 2 prepared with different methods and/or structures was measured. The factors affecting the bombarding lifetime of the carbon stripping foils, especially the method of the foil preparation and the structure of the carbon stripping foils, were discussed. It is observed that the foils prepared with the DC arc discharge method have a longer bombarding lifetime than those prepared with the AC arc discharge method. (authors)

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

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

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)

Potentiometric stripping analysis of arsenic using a graphene paste electrode modified with a thiacrown ether and gold nanoparticles

International Nuclear Information System (INIS)

Sanghavi, Bankim J.; Gadhari, Nayan S.; Kalambate, Pramod K.; Srivastava, Ashwini K.; Karna, Shashi P.

2015-01-01

An electrochemical method is presented for the determination of arsenic at subnanomolar levels. It is based on potentiometric stripping analysis (PSA) using a graphene paste electrode modified with the thiacrown 1,4,7-trithiacyclononane (TTCN) and gold nanoparticles (AuNPs). The electrode surface was characterized by means of cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and scanning electron microscopy. The modified electrode displays a 15-fold enhancement in the PSA signal (dt/dE) compared to a conventional graphene paste electrode. Under optimized conditions, the signal is proportional to the concentration of As(III) in the range from 25 pM to 34 nM (r 2  = 0.9977), and the detection limit (SD/s) is as low as 8 pM. The modified electrode was successfully applied to the determination of total arsenic [i.e., As(III) and As(V)] in pharmaceutical formulations, human hair, sea water, fruits, vegetables, soil, and wine samples. (author)

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

Adsorption of water and butanol in silicalite-1 film studied with in situ attenuated total reflectance-Fourier transform infrared spectroscopy.

Science.gov (United States)

Farzaneh, Amirfarrokh; Zhou, Ming; Potapova, Elisaveta; Bacsik, Zoltán; Ohlin, Lindsay; Holmgren, Allan; Hedlund, Jonas; Grahn, Mattias

2015-05-05

Biobutanol produced by, e.g., acetone-butanol-ethanol (ABE) fermentation is a promising alternative to petroleum-based chemicals as, e.g., solvent and fuel. Recovery of butanol from dilute fermentation broths by hydrophobic membranes and adsorbents has been identified as a promising route. In this work, the adsorption of water and butanol vapor in a silicalite-1 film was studied using in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy to better understand the adsorption properties of silicalite-1 membranes and adsorbents. Single-component adsorption isotherms were determined in the temperature range of 35-120 °C, and the Langmuir model was successfully fitted to the experimental data. The adsorption of butanol is very favorable compared to that of water. When the silicalite-1 film was exposed to a butanol/water vapor mixture with 15 mol % butanol (which is the vapor composition of an aqueous solution containing 2 wt % butanol, a typical concentration in an ABE fermentation broth, i.e., the composition of the gas obtained from gas stripping of an ABE broth) at 35 °C, the adsorption selectivity toward butanol was as high as 107. These results confirm that silicalite-1 quite selectively adsorbs hydrocarbons from vapor mixtures. To the best of our knowledge, this is the first comprehensive study on the adsorption of water and butanol in silicalite-1 from vapor phase.

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 extensively......)-approximation by two independent research groups [FSTTCS 2016,WALCOM 2017]. This raises a questionwhether strip packing with polynomially bounded input data admits a quasi-polynomial time approximation scheme, as is the case for related twodimensional packing problems like maximum independent set of rectangles or two...

Square-wave anodic-stripping voltammetric determination of Cd, Pb and Cu in wine: Set-up and optimization of sample pre-treatment and instrumental parameters

International Nuclear Information System (INIS)

Illuminati, Silvia; Annibaldi, Anna; Truzzi, Cristina; Finale, Carolina; Scarponi, Giuseppe

2013-01-01

For the first time, square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for the determination of Cd, Pb and Cu in white wine after UV photo-oxidative digestion of the sample. The best procedure for the sample pre-treatment consisted in a 6-h UV irradiation of diluted, acidified wine, with the addition of ultrapure H 2 O 2 (three sequential additions during the irradiation). Due to metal concentration differences, separate measurements were carried out for Cd (deposition potential −950 mV vs. Ag/AgCl/3 M KCl deposition time 15 min) and simultaneously for Pb and Cu (E d −750 mV, t d 30 s). The optimum set-up of the main instrumental parameters, evaluated also in terms of the signal-to-noise ratio, were as follows: E SW 20 mV, f 100 Hz, ΔE step 8 mV, t step 100 ms, t wait 60 ms, t delay 2 ms, t meas 3 ms. The electrochemical behaviour was reversible bielectronic for Cd and Pb, and kinetically controlled monoelectronic for Cu. Good accuracy was found both when the recovery procedure was used and when the results were compared with data obtained by differential pulse anodic stripping voltammetry. The linearity of the response was verified up to ∼4 μg L −1 for Cd and Pb and ∼15 μg L −1 for Cu. The detection limits for t d = 5 min in the 10 times diluted, UV digested sample were (ng L −1 ): Cd 7.0, Pb 1.2 and Cu 6.6, which are well below currently applied methods. Application to a Verdicchio dei Castelli di Jesi white wine revealed concentration levels of Cd ∼0.2, Pb ∼10, Cu ∼30 μg L −1 with repeatabilities of (±RSD%) Cd ±6%, Pb ±5%, Cu ±10%

Transfusion and blood donation in comic strips.

Science.gov (United States)

Lefrère, Jean-Jacques; Danic, Bruno

2013-07-01

The representation of blood transfusion and donation of blood in the comic strip has never been studied. The comic strip, which is a relatively recent art, emerged in the 19th century before becoming a mass medium during the 20th century. We have sought, by calling on collectors and using the resources of Internet, comic strips devoted, wholly or in part, to the themes of transfusion and blood donation. We present some of them here in chronologic order, indicating the title, country of origin, year of publication, and names of authors. The theme of the superhero using transfusion to transmit his virtues or his powers is repeated throughout the 20th century in North American comic strips. More recently, comic strips have been conceived from the outset with a promotional aim. They perpetuate positive images and are directed toward a young readership, wielding humor to reduce the fear of venipuncture. Few comic strips denounce the abuse of the commercialization of products derived from the human body. The image of transfusion and blood donation given by the comic strips is not to be underestimated because their readership is primarily children, some of whom will become blood donors. Furthermore, if some readers are transfused during their lives, the impact of a memory more or less conscious of these childhood readings may resurface, both in hopes and in fears. Copyright © 2013 Elsevier Inc. All rights reserved.

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

Strong adsorption characteristics of a novel overoxidized poly(3,4-ethylenedioxythiophene) film and application for dopamine sensing

International Nuclear Information System (INIS)

Lin, Jia-Min; Su, Ya-Ling; Chang, Wei-Ting; Su, Wan-Yu; Cheng, Shu-Hua

2014-01-01

Highlights: • A novel overoxidized poly(3,4-ethylenedioxythiophene) film is obtained. • The film structure favors the adsorption of dopamine. • The sensor is able to detect dopamine in the presence of ascorbic acid (1000X). - Abstract: An overoxidized poly(3,4-ethylenedioxythiophene) film-modified screen-printed carbon electrodes (SPCE/PEDOT ox ) was prepared and characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle techniques. The obtained film is a porous structure with highly abundant oxygen functionality. The SPCE/PEDOT ox could adsorb cations strongly and perform catalytic oxidation of biomolecules. The potential-induced adsorption of dopamine was observed for SPCE/PEDOT ox . A simple medium-exchange procedure was developed for the selective determination of dopamine by the use of the dopamine-adsorbed electrode. Under optimal differential pulse voltammetry (DPV), the proposed assay can be employed in the determination of submicromolar concentration of dopamine without the coexisting interferences of ascorbic acid (1000-fold) and uric acid (10-fold)

Competitive Protein Adsorption - Multilayer Adsorption and Surface Induced Protein Aggregation

DEFF Research Database (Denmark)

Holmberg, Maria; Hou, Xiaolin

2009-01-01

In this study, competitive adsorption of albumin and IgG (immunoglobulin G) from human serum solutions and protein mixtures onto polymer surfaces is studied by means of radioactive labeling. By using two different radiolabels (125I and 131I), albumin and IgG adsorption to polymer surfaces...... is monitored simultaneously and the influence from the presence of other human serum proteins on albumin and IgG adsorption, as well as their mutual influence during adsorption processes, is investigated. Exploring protein adsorption by combining analysis of competitive adsorption from complex solutions...... of high concentration with investigation of single protein adsorption and interdependent adsorption between two specific proteins enables us to map protein adsorption sequences during competitive protein adsorption. Our study shows that proteins can adsorb in a multilayer fashion onto the polymer surfaces...

Adsorption Behavior of TBPS in the Process of Cu Electrodeposition on an Au Film.

Science.gov (United States)

Chen, Liang-Huei; Liu, Yung-Fang; Krug, Klaus; Lee, Yuh-Lang

2018-05-15

The adsorption behavior of an Cu electroplating additive, 3,3 thiobis-(1-propanesulfonic acid sodium salt) (TBPS) in a process of Cu deposition onto a single crystalline Au(111) surface is studied by an in-situ Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS). The SEIRAS spectra of the TBPS adlayer on a Cu film is investigated first and compared to that on an Au film. These results are utilized to evaluate the characteristics of TBPS adlayer on the electrode surface during the Cu deposition and stripping processes. The results show that the SEIRAS spectra of TBPS adsorbed on the Cu film resembles closely to that on the Au film, and the most pronounced peaks are symmetric S-O (ss-SO) and asymmetric S-O (as-SO) stretching modes. However, the as-SO band is sharper with a higher intensity on the Cu film. Since the ss-SO and as-SO peaks correspond to the molecular with upright and lie-down orientations, respectively, it implies that the TBPS molecules have higher ratio of lie-down orientation on the Cu film. In the Cu electrodeposition process, the cyclic voltammetry (CV) result shows that the presence of the TBPS in the HClO 4 solution can decrease the inhibition effect of HClO 4 to the Cu deposition. For the spectra measured at various potential during cathodic and anodic sweeping, an obvious change of the spectra occurs at ca. 0.6 V, the initiation of Cu underpotential deposition (Cu-UPD). For potentials higher and lower than 0.6 V, the spectra are similar, respectively, to those measured for the Au and Cu films. This result indicates that the TBPS molecules originally adsorbing on the Au film transfer to the surface of deposited Cu layer. This inference is also confirmed by the variation in wavenumber and peak intensity of ss-SO and as-SO peaks during the potential sweeping.

Interfacial adsorption of insulin - Conformational changes and reversibility of adsorption

NARCIS (Netherlands)

Mollmann, SH; Jorgensen, L; Bukrinsky, JT; Elofsson, U; Norde, W; Frokjaer, S

The adsorption of human insulin to Teflon particles was studied with respect to conformational changes and the reversibility of adsorption was examined by total internal reflection fluorescence (TIRF). Adsorption isotherms for the adsorption of human insulin indicated high affinity adsorption, even

Electrochemically modified sulfisoxazole nanofilm on glassy carbon for determination of cadmium(II) in water samples

International Nuclear Information System (INIS)

Gupta, Vinod Kumar; Yola, Mehmet Lütfi; Atar, Necip; Solak, Ali Osman; Uzun, Lokman; Üstündağ, Zafer

2013-01-01

Highlights: • Sulfisoxazole was grafted onto glassy carbon electrode. • The electrode was characterized by spectroscopic and electrochemical methods. • It has been used for the determination of Cd(II) ions in real samples in very low concentrations. -- Abstract: Sulfisoxazole (SO) was grafted to glassy carbon electrode (GCE) via the electrochemical oxidation of SO in acetonitrile solution containing 0.1 M tetrabutylammoniumtetra-fluoroborate (TBATFB). The prepared electrode was characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), reflection–absorption infrared spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS). The ellipsometric thickness of SO nanofilm at the glassy carbon surface was obtained as 14.48 ± 0.11 nm. The stability of the SO modified GCE was studied. The SO modified GCE was also utilized for the determination of Cd(II) ions in water samples in the presence of Pb(II) and Fe(II) by adsorptive stripping voltammetry. The linearity range and the detection limit of Cd(II) ions were 1.0 × 10 −10 to 5.0 × 10 −8 M and 3.3 × 10 −11 M (S/N = 3), respectively

Electrochemical study of varenicline adsorptive behaviour and its interaction with DNA

Directory of Open Access Journals (Sweden)

Radulović Valentina

2012-01-01

Full Text Available The electrochemical behaviour of novel nicotinic α4β2 subtype receptor partial agonist varenicline (VAR which is used for smoking cessation, was investigated in Britton-Robinson buffers (pH 2.0-12.0 by cyclic, differential pulse and square wave voltammetry at a hanging mercury drop elctrode. The influence of pH, scan rate, concentration, accumulation potential and time on peak current and potential suggested that in alkaline media the redox process was adsorption controlled. Also, the experimental value of surface coverage, G = 1.03´10-10 mol cm-2, was used to determine the conditions when VAR was fully adsorbed at the electrode surface. Having in mind potential high toxicity of VAR due to the presence of quinoxaline structure, its interaction with DNA was postulated, and studied when both compounds were in the adsorbed state at modified HMDE. Using adsorptive transfer technique, the changes in potential and decrease in normalized peak currents were observed. The estimated value of the ratio of surface-binding constants indicated that the reduced form of VAR interacted with dsDNA more strongly than the oxidized form. Subtle DNA damage under conditions of direct DNA-VAR interaction at room temperature was observed. The proposed type of interaction was an intercalation. This study used simple electroanalytical methodology and showed the potential of DNA/HMDE biosensor for investigation of genotoxic effects.

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

Development of floating strip micromegas detectors

International Nuclear Information System (INIS)

Bortfeldt, Jonathan

2014-01-01

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 34 cm -2 s -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 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 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 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 track inclination in a single

Voltammetric determination of arsenic in high iron and manganese groundwaters.

Science.gov (United States)

Gibbon-Walsh, Kristoff; Salaün, Pascal; Uroic, M Kalle; Feldmann, Joerg; McArthur, John M; van den Berg, Constant M G

2011-09-15

Determination of the speciation of arsenic in groundwaters, using cathodic stripping voltammetry (CSV), is severely hampered by high levels of iron and manganese. Experiments showed that the interference is eliminated by addition of EDTA, making it possible to determine the arsenic speciation on-site by CSV. This work presents the CSV method to determine As(III) in high-iron or -manganese groundwaters in the field with only minor sample treatment. The method was field-tested in West-Bengal (India) on a series of groundwater samples. Total arsenic was subsequently determined after acidification to pH 1 by anodic stripping voltammetry (ASV). Comparative measurements by ICP-MS as reference method for total As, and by HPLC for its speciation, were used to corroborate the field data in stored samples. Most of the arsenic (78±0.02%) was found to occur as inorganic As(III) in the freshly collected waters, in accordance with previous studies. The data shows that the modified on-site CSV method for As(III) is a good measure of water contamination with As. The EDTA was also found to be effective in stabilising the arsenic speciation for longterm sample storage at room temperature. Without sample preservation, in water exposed to air and sunlight, the As(III) was found to become oxidised to As(V), and Fe(II) oxidised to Fe(III), removing the As(V) by adsorption on precipitating Fe(III)-hydroxides within a few hours. Copyright © 2011 Elsevier B.V. All rights reserved.

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...

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 ...

Apparatus for measuring profile thickness of strip material

International Nuclear Information System (INIS)

Hold, A.C.

1982-01-01

Apparatus for measuring the thickness profile of steel strip comprises a radiation source reciprocally movable in a stepwise fashion (by a belt) across the strip width on one side thereof and a single elongated detector on the other side of the strip aligned with the scanning source. This detector may be a fluorescent scintillator detector or an ionisation chamber. Means are provided for sensing the degree of excitation in the detector in synchronism with the scanning source whereby to provide an output representative of the thickness profile of the strip. (author)

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....

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)

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.

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.

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

Magnetic stripping studies for SPL

CERN Document Server

Posocco, P; CERN. Geneva. BE Department

2010-01-01

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

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.

Microstructural research on hot strips of low carbon steel produced by a compact strip production line under different thermal histories

International Nuclear Information System (INIS)

Yu Hao; Chen Qixiang; Kang Yonglin; Sun Yi

2005-01-01

Coupons with the same composition and thickness (4.0 mm nominal gauge) obtained from hot strips of low carbon steel underwent a series of investigations to analyze the microstructural characteristics and mechanisms responsible for their differences in mechanical properties. Two different industrial technologies were adopted, although the strips used in this research were produced on the same Compact Strip Production (CSP) line. One of the strips was produced with a routine γ→α CSP thermal history, but the other with a γ→α→γ* conventional thermal history. The only difference between them was that one technology had a α→γ* thermal history. Different specimens of both types of strips were prepared for metallographic observation, tensile tests, electron back-scattered diffraction tests and positron annihilation technique tests. Experimental results showed that the differences in mechanical properties could be ascribed to dissimilarities not only in the grain size and textural components but also in dislocation density

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

OpenAIRE

Kowalik R.

2015-01-01

The different voltammetry techniques were applied to understand the process of selenium deposition from sulfate solution on gold polycrystalline electrode. By applying the cycling voltammetry with different scan limits as well as the chronoamper-ometry combined with the cathodic and anodic linear stripping voltammetry, the different stages of the deposition of selenium were revealed. It was found that the process of reduction of selenous acid on gold surface exhibits a multistage character. T...

High Pressure Water Stripping Using Multi-Orifice Nozzles

Science.gov (United States)

Hoppe, David

1999-01-01

The use of multi-orifice rotary nozzles greatly increases the speed and stripping effectiveness of high pressure water blasting systems, but also greatly increases the complexity of selecting and optimizing the operating parameters. The rotational speed of the nozzle must be coupled with its transverse velocity as it passes across the surface of the substrate being stripped. The radial and angular positions of each orifice must be included in the analysis of the nozzle configuration. Orifices at the outer edge of the nozzle head move at a faster rate than the orifices located near the center. The energy transmitted to the surface from the impact force of the water stream from an outer orifice is therefore spread over a larger area than energy from an inner orifice. Utilizing a larger diameter orifice in the outer radial positions increases the total energy transmitted from the outer orifice to compensate for the wider distribution of energy. The total flow rate from the combination of all orifices must be monitored and should be kept below the pump capacity while choosing orifice to insert in each position. The energy distribution from the orifice pattern is further complicated since the rotary path of all the orifices in the nozzle head pass through the center section. All orifices contribute to the stripping in the center of the path while only the outer most orifice contributes to the stripping at the edge of the nozzle. Additional orifices contribute to the stripping from the outer edge toward the center section. With all these parameters to configure and each parameter change affecting the others, a computer model was developed to track and coordinate these parameters. The computer simulation graphically indicates the cumulative affect from each parameter selected. The result from the proper choices in parameters is a well designed, highly efficient stripping system. A poorly chosen set of parameters will cause the nozzle to strip aggressively in some areas

Investigation of adsorption performance deterioration in silica gel–water adsorption refrigeration

International Nuclear Information System (INIS)

Wang Dechang; Zhang Jipeng; Xia Yanzhi; Han Yanpei; Wang Shuwei

2012-01-01

Highlights: ► Adsorption deterioration of silica gel in refrigeration systems is verified. ► Possible factors to cause such deterioration are analyzed. ► Specific surface area, silanol content and adsorption capacity are tested. ► The pollution is the primary factor to decline the adsorption capacity. ► Deteriorated samples are partly restored after being processed by acid solution. - Abstract: Silica gel acts as a key role in adsorption refrigeration systems. The adsorption deterioration must greatly impact the performance of the silica gel–water adsorption refrigeration system. In order to investigate the adsorption deterioration of silica gel, many different silica gel samples were prepared according to the application surroundings of silica gel in adsorption refrigeration systems after the likely factors to cause such deterioration were analyzed. The specific surface area, silanol content, adsorption capacity and pore size distribution of those samples were tested and the corresponding adsorption isotherms were achieved. In terms of the experimental data comparisons, it could be found that there are many factors to affect the adsorption performance of silica gel, but the pollution was the primary one to decline the adsorption capacity. In addition, the adsorption performance of the deteriorated samples after being processed by acid solution was explored in order to find the possible methods to restore its adsorption performance.

Cyclic Voltammetry of Highly Hydrophilic Ions at a Supported Liquid Membrane

Czech Academy of Sciences Publication Activity Database

Ulmeanu, S. M.; Jensen, H.; Samec, Zdeněk; Bouchard, G.; Carrupt, P. A.; Giraut, H. H.

2002-01-01

Roč. 530, 1/2 (2002), s. 10-15 ISSN 0022-0728 R&D Projects: GA AV ČR IAA4040902 Institutional research plan: CEZ:AV0Z4040901 Keywords : liquid-liquid interface * membrane * cyclic voltammetry Subject RIV: CG - Electrochemistry Impact factor: 2.027, year: 2002

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.

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.

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.)

Micro-strip sensors based on CVD diamond

Energy Technology Data Exchange (ETDEWEB)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D' Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D. E-mail: dirk.meier@cern.ch; Mishina, M.; Moroni, L.; Oh, A.; Pan, L.S.; Pernicka, M.; Peitz, A.; Perera, L.; Pirollo, S.; Procario, M.; Riester, J.L.; Roe, S.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; Wetstein, M.; White, C.; Zeuner, W.; Zoeller, M

2000-10-11

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

Micro-strip sensors based on CVD Diamond

CERN Document Server

Adam, W; Bergonzo, P; Bertuccio, G; Bogani, F; Borchi, E; Brambilla, A; Bruzzi, Mara; Colledani, C; Conway, J; D'Angelo, P; Dabrowski, W; Delpierre, P A; Deneuville, A; Dulinski, W; van Eijk, B; Fallou, A; Fizzotti, F; Foulon, F; Friedl, M; Gan, K K; Gheeraert, E; Hallewell, G D; Han, S; Hartjes, F G; Hrubec, Josef; Husson, D; Kagan, H; Kania, D R; Kaplon, J; Kass, R; Koeth, T W; Krammer, Manfred; Lo Giudice, A; Lü, R; MacLynne, L; Manfredotti, C; Meier, D; Mishina, M; Moroni, L; Oh, A; Pan, L S; Pernicka, Manfred; Peitz, A; Perera, L P; Pirollo, S; Procario, M; Riester, J L; Roe, S; Rousseau, L; Rudge, A; Russ, J; Sala, S; Sampietro, M; Schnetzer, S R; Sciortino, S; Stelzer, H; Stone, R; Suter, B; Tapper, R J; Tesarek, R J; Trischuk, W; Tromson, D; Vittone, E; Walsh, A M; Wedenig, R; Weilhammer, Peter; Wetstein, M; White, C; Zeuner, W; Zoeller, M M

2000-01-01

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

Micro-strip sensors based on CVD diamond

International Nuclear Information System (INIS)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L.S.; Pernicka, M.; Peitz, A.; Perera, L.; Pirollo, S.; Procario, M.; Riester, J.L.; Roe, S.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; Wetstein, M.; White, C.; Zeuner, W.; Zoeller, M.

2000-01-01

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation

Micro-strip sensors based on CVD diamond

Science.gov (United States)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L. S.; Pernicka, M.; Peitz, A.; Perera, L.; Pirollo, S.; Procario, M.; Riester, J. L.; Roe, S.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; Wetstein, M.; White, C.; Zeuner, W.; Zoeller, M.; RD42 Collaboration

2000-10-01

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

Advection endash diffusion past a strip. II. Oblique incidence

International Nuclear Information System (INIS)

Knessl, C.; Keller, J.B.

1997-01-01

Advection and diffusion of particles past an impenetrable strip is considered when the strip is oblique to the advection or drift velocity. The particle concentration p(x,y) is determined asymptotically for large values of vL/D, where v is the drift velocity, D is the diffusion coefficient, and 2L is the width of the strip. The results complement those of Part I, which treated a strip normal to the drift velocity. copyright 1997 American Institute of Physics

Spectroelectrochemical study of the adsorption of acetate anions at gold single crystal and thin-film electrodes

International Nuclear Information System (INIS)

Berna, Antonio; Delgado, Jose Manuel; Orts, Jose Manuel; Rodes, Antonio; Feliu, Juan Miguel

2008-01-01

Acetate adsorption at gold electrodes is studied in perchloric acid solutions by cyclic voltammetry and in-situ infrared spectroscopy. External reflection measurements, performed with gold single crystal electrodes, are combined with Surface Enhanced Infrared Reflection Absorption Spectroscopy experiments under attenuated total reflection conditions (ATR-SEIRAS) carried out with sputtered gold thin-film electrodes. Theoretical harmonic IR frequencies of acetate species adsorbed with different geometries on Au clusters with (1 1 1), (1 0 0) and (1 1 0) orientations have been obtained from B3LYP/LANL2DZ, 6-31 + G* calculations. The theoretical and experimental results confirm that, irrespective of the surface crystallographic orientation, bonding of acetate to the surface involves the two oxygen atoms of the carboxylate group, with the OCO plane perpendicular to the metal surface. DFT calculations reveal also that the total charge of the metal cluster-acetate supermolecule has small effect on the vibrational frequencies of adsorbed acetate species. Both the external and the internal reflection measurements show the co-adsorption of acetate and perchlorate anions. Step-scan measurements carried out with the gold thin-film electrodes have allowed the monitoring of the time-dependent behaviour of perchlorate, acetate and water bands in potential step experiments. Acetate adsorption under those conditions is shown to involve perchlorate desorption and to follow a Langmuir-type kinetics. The step-scan spectra also show the rise and decay of transient water structures with parallel time-dependent shifts of the background intensity in the infrared spectra

Stripping of uranium from Dehpa/kerosene solvents by different aqueous media

International Nuclear Information System (INIS)

Khorfan, S.; Stas, J.; Kassem, M.

1998-01-01

Stripping uranium from Dehpa/kerosene solvent is a crucial step in the recovery of uranium. Stripping was studied using different stripping media mainly ammonium carbonate, phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid. Stripping was measured at different operating conditions such as aqueous concentrations, temperatures, and Dehpa/kerosene concentrations. The results obtained showed that stripping by acid media increases with the acid concentration and follows the order: HF > H 3 PO 4 > H 2 SO 4 > HCl > HNO 3 . To achieve higher stripping by phosphoric acid it was found necessary to increase the temperature to 50 deg C, the acid concentration to 5 mol/l and to reduce the uranium to U 4+ . Stripping by basic media was found to increase with increasing concentration of the stripping media and to follow the order: Na 2 CO 3 > (NH 4 ) 2 CO 3 > NH 4 HCO 3 . Stripping by ammonium carbonate was found to increase with temperature and carbonate concentration. The stripping was optimized at 0.5 mol/l carbonate concentration and at a temperature of 50 deg C. Stripping was decreased by increasing concentration of Dehpa in kerosene and was depressed more by adding the synergant Topo to the Dehpa solvent especially at 1/4 mol/mol ratio. (author)

VOLTAMMETRY OF AQUEOUS CHLOROAURIC ACID WITH HANGING MERCURY DROP ELECTRODE

Czech Academy of Sciences Publication Activity Database

Korshunov, A.; Josypčuk, Bohdan; Heyrovský, Michael

2011-01-01

Roč. 76, č. 7 (2011), s. 929-936 ISSN 0010-0765 R&D Projects: GA ČR GAP206/11/1638; GA AV ČR IAA400400806; GA MŠk(CZ) LC06063 Institutional research plan: CEZ:AV0Z40400503 Keywords : aqueous chloauric acid * voltammetry * hanging mercury drop electrode Subject RIV: CG - Electrochemistry Impact factor: 1.283, year: 2011

Unravelling the influence of carbon dioxide on the adsorptive recovery of butanol from fermentation broth using ITQ-29 and ZIF-8.

Science.gov (United States)

Martin-Calvo, Ana; Van der Perre, Stijn; Claessens, Benjamin; Calero, Sofia; Denayer, Joeri F M

2018-04-18

The vapor phase adsorption of butanol from ABE fermentation at the head space of the fermenter is an interesting route for the efficient recovery of biobutanol. The presence of gases such as carbon dioxide that are produced during the fermentation process causes a stripping of valuable compounds from the aqueous into the vapor phase. This work studies the effect of the presence of carbon dioxide on the adsorption of butanol at a molecular level. With this aim in mind Monte Carlo simulations were employed to study the adsorption of mixtures containing carbon dioxide, butanol and ethanol. Molecular models for butanol and ethanol that reproduce experimental properties of the molecules such as polarity, vapor-liquid coexistence or liquid density have been developed. Pure component isotherms and heats of adsorption have been computed and compared to experimental data to check the accuracy of the interacting parameters. Adsorption of butanol/ethanol mixtures has been studied in absence and presence of CO2 on two representative materials, a pure silica LTA zeolite and a hydrophobic metal-organic framework ZIF-8. To get a better understanding of the molecular mechanism that governs the adsorption of the targeted mixture in the selected materials, the distribution of the molecules inside the structures was analyzed. The combination of these features allows obtaining a deeper understanding of the process and to identify the role of carbon dioxide in the butanol purification process.

Stage- vs. Channel-strip Metaphor

DEFF Research Database (Denmark)

Gelineck, Steven; Korsgaard, Dannie Michael; Büchert, Morten

2015-01-01

This study compares the stage metaphor and the channel strip metaphor in terms of performance. Traditionally, music mixing consoles employ a channels strip control metaphor for adjusting parameters such as volume and panning of each track. An alternative control metaphor, the so-called stage meta...... is surprisingly similar and thus we are not able to detect any significant difference in performance between the two interfaces. Qualitative data however, suggests that the stage metaphor is largely favoured for its intuitive interaction - confirming earlier studies....

Study of inter-strip gap effects and efficiency for full energy detection of double sided silicon strip detectors

International Nuclear Information System (INIS)

Fisichella, M.; Forneris, J.; Grassi, L.

2015-01-01

We performed a characterization of Double Sided Silicon Strip Detectors (DSSSD) with the aim to carry out a systematic study of the inter-strip effects on the energy measurement of charged particles. The dependence of the DSSSD response on ion, energy and applied bias has been investigated. (author)

Ship-in-a-bottle CMPO in MIL-101(Cr) for selective uranium recovery from aqueous streams through adsorption

Energy Technology Data Exchange (ETDEWEB)

De Decker, Jeroen [Department of Inorganic and Physical Chemistry, Center for Ordered Materials, Organometallics, and Catalysis (COMOC), Ghent University, Krijgslaan 281-S3, 9000 Ghent (Belgium); Folens, Karel [Laboratory of Analytical Chemistry and Applied Ecochemistry, Ghent University, Coupure Links 653, 9000 Ghent (Belgium); De Clercq, Jeriffa [Department of Materials, Textiles, and Chemical Engineering, Industrial Catalysis and Adsorption Technology (INCAT), Ghent University, Valentin, Vaerwyckweg 1, 9000 Ghent (Belgium); Meledina, Maria; Van Tendeloo, Gustaaf [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Du Laing, Gijs [Laboratory of Analytical Chemistry and Applied Ecochemistry, Ghent University, Coupure Links 653, 9000 Ghent (Belgium); Van Der Voort, Pascal, E-mail: pascal.vandervoort@ugent.be [Department of Inorganic and Physical Chemistry, Center for Ordered Materials, Organometallics, and Catalysis (COMOC), Ghent University, Krijgslaan 281-S3, 9000 Ghent (Belgium)

2017-08-05

Highlights: • Highly stable metal-organic framework, MIL-101(Cr), for uses in aqueous, acidic adsorption. • Uranium recovery from low concentration acidic solutions. • One-step ship-around-the-bottle synthetic approach to incorporate CMPO in MIL-101(Cr). • Highly selective U(VI) adsorbent in competition with a high variety of metals, incl. rare earths and transition metals. • Regenerable and reusable adsorbent via 0.1 M nitric acid stripping. - Abstract: Mesoporous MIL-101(Cr) is used as host for a ship-in-a-bottle type adsorbent for selective U(VI) recovery from aqueous environments. The acid-resistant cage-type MOF is built in-situ around N,N-Diisobutyl-2-(octylphenylphosphoryl)acetamide (CMPO), a sterically demanding ligand with high U(VI) affinity. This one-step procedure yields an adsorbent which is an ideal compromise between homogeneous and heterogeneous systems, where the ligand can act freely within the pores of MIL-101, without leaching, while the adsorbent is easy separable and reusable. The adsorbent was characterized by XRD, FTIR spectroscopy, nitrogen adsorption, XRF, ADF-STEM and EDX, to confirm and quantify the successful encapsulation of the CMPO in MIL-101, and the preservation of the host. Adsorption experiments with a central focus on U(VI) recovery were performed. Very high selectivity for U(VI) was observed, while competitive metal adsorption (rare earths, transition metals...) was almost negligible. The adsorption capacity was calculated at 5.32 mg U/g (pH 3) and 27.99 mg U/g (pH 4), by fitting equilibrium data to the Langmuir model. Adsorption kinetics correlated to the pseudo-second-order model, where more than 95% of maximum uptake is achieved within 375 min. The adsorbed U(VI) is easily recovered by desorption in 0.1 M HNO{sub 3}. Three adsorption/desorption cycles were performed.

Ship-in-a-bottle CMPO in MIL-101(Cr) for selective uranium recovery from aqueous streams through adsorption

International Nuclear Information System (INIS)

De Decker, Jeroen; Folens, Karel; De Clercq, Jeriffa; Meledina, Maria; Van Tendeloo, Gustaaf; Du Laing, Gijs; Van Der Voort, Pascal

2017-01-01

Highlights: • Highly stable metal-organic framework, MIL-101(Cr), for uses in aqueous, acidic adsorption. • Uranium recovery from low concentration acidic solutions. • One-step ship-around-the-bottle synthetic approach to incorporate CMPO in MIL-101(Cr). • Highly selective U(VI) adsorbent in competition with a high variety of metals, incl. rare earths and transition metals. • Regenerable and reusable adsorbent via 0.1 M nitric acid stripping. - Abstract: Mesoporous MIL-101(Cr) is used as host for a ship-in-a-bottle type adsorbent for selective U(VI) recovery from aqueous environments. The acid-resistant cage-type MOF is built in-situ around N,N-Diisobutyl-2-(octylphenylphosphoryl)acetamide (CMPO), a sterically demanding ligand with high U(VI) affinity. This one-step procedure yields an adsorbent which is an ideal compromise between homogeneous and heterogeneous systems, where the ligand can act freely within the pores of MIL-101, without leaching, while the adsorbent is easy separable and reusable. The adsorbent was characterized by XRD, FTIR spectroscopy, nitrogen adsorption, XRF, ADF-STEM and EDX, to confirm and quantify the successful encapsulation of the CMPO in MIL-101, and the preservation of the host. Adsorption experiments with a central focus on U(VI) recovery were performed. Very high selectivity for U(VI) was observed, while competitive metal adsorption (rare earths, transition metals...) was almost negligible. The adsorption capacity was calculated at 5.32 mg U/g (pH 3) and 27.99 mg U/g (pH 4), by fitting equilibrium data to the Langmuir model. Adsorption kinetics correlated to the pseudo-second-order model, where more than 95% of maximum uptake is achieved within 375 min. The adsorbed U(VI) is easily recovered by desorption in 0.1 M HNO 3 . Three adsorption/desorption cycles were performed.

Stripping of uranium from Dehpa/Kerosene solvents by different aqueous media

International Nuclear Information System (INIS)

Khorfan, S.; Stas, J.; Kassem, M.

2000-01-01

Stripping uranium from Dehpa/kerosene solvent is a crucial step in the recovery of uranium. Stripping was studied using different stripping media mainly ammonium carbonate, phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid. Stripping was measured at different operating conditions such as aqueous concentrations, temperatures, and Dehpa/kerosene concentrations. The results obtained showed that stripping by acid media increases with the acid concentration and follows the order: HF > H sub 3 Po sub 4 > H sub 2 S O sub 4 > HCl > HNO sub 3. To achieve higher stripping by phosphoric acid it was found necessary to increase the temperature to 50 deg C, the acid concentration to 5 mol/l and to reduce the uranium to U sup 4 sup +. Stripping by basic media was found to increase with increasing concentration of the stripping media and to follow the order: Na sub 2 CO sub 3 > (NH sub 4) sub 2 CO sub 3 > NH sub 4 HCO sub 3. Stripping by ammonium carbonate was found to increase with temperature and carbonate concentration. The stripping was optimized at 0.5 mol/l carbonate concentration and at a temperature of 50 deg C. Stripping was decreased by increasing concentration of Dehpa in kerosene and was depressed more by adding the synergant TOPO to the Dehpa solvent especially at 1/4 mol/mol ratio. (author)

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).

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

Study and Elimination of the Interference of Aluminium on the Voltammetric Determination of Uranium with Chloranilic Acid. Application to the Determination of Uranium in Waters and Geological Samples

International Nuclear Information System (INIS)

Fernandez, C.; Sanchez, M.; Ballesteros, O.; Fernandez, M.; Clavero, M. A.; Gonzalez, A. M.

2000-01-01

The interference of aluminium during the voltammetric determination of uranium with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid) has been investigated. The presence of aluminium originates a voltammetric signal due to its chloranilic acid complex at the same potential range as the uranium analytical signal appears. The interference of aluminium can be overcome by addition of an appropriate amount of sodium fluoride as complexing reagent. The determination of uranium by adsorptive stripping voltammetry (AdSV) can be carried out at concentration levels as low as 1 μg/L in the presence of 100 μg/L aluminium after the addition of 100μL of 0.1 mol/L NaF. The method can be applied to the determination of uranium in aluminium-containing waters and geological samples containing high aluminium levels. (Author) 19 refs

Characteristics of curcumin using cyclic voltammetry, UV–vis, fluorescence and thermogravimetric analysis

International Nuclear Information System (INIS)

Masek, Anna; Chrzescijanska, Ewa; Zaborski, Marian

2013-01-01

Highlights: • Electrooxidation of curcumin was investigated with cyclic voltammetry. • The curcumin is irreversibly oxidized at the platinum electrode in anhydrous media. • Absorbance, fluorescence and thermogravimetric analysis of curcumin was studied. • The HOMO and Mapped Electron Densities were calculated using HyperChem. • Oxidation mechanism for curcumin proposed. -- Abstract: Curcumin, the yellow, primary bioactive component of turmeric, has recently received attention from chemists due its wide range of potential biological applications as an antioxidant, anti-inflammatory, and anti-carcinogenic agent. The electrochemical behaviour of curcumin at a platinum electrode has been studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The oxidation of curcumin is an irreversible process that proceeds in two steps in 0.1 M (C 4 H 9 ) 4 NClO 4 in acetonitrile. The process of oxidation and its kinetics have been investigated. The rate constant, electron transfer coefficient and diffusion coefficients for the electrochemical oxidation of curcumin were determined. A mechanism for the oxidation of curcumin is proposed. The data obtained are consistent with the current literature and suggest that voltammetric studies on mechanically transferred solids may be a convenient method for elucidating the electrochemical oxidation mechanisms of compounds in anhydrous media. Theoretical calculations regarding the optimization of curcumin, electronic properties like highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated using with HyperChem software by AM1 semi-empirical method. The properties of curcumin in a homogeneous environment were investigated using spectroscopic techniques and thermogravimetric analysis

Static and Dynamic Measurement of Dopamine Adsorption in Carbon Fiber Microelectrodes Using Electrochemical Impedance Spectroscopy.

Science.gov (United States)

Rivera-Serrano, Nilka; Pagan, Miraida; Colón-Rodríguez, Joanisse; Fuster, Christian; Vélez, Román; Almodovar-Faria, Jose; Jiménez-Rivera, Carlos; Cunci, Lisandro

2018-02-06

In this study, electrochemical impedance spectroscopy was used for the first time to study the adsorption of dopamine in carbon fiber microelectrodes. In order to show a proof-of-concept, static and dynamic measurements were taken at potentials ranging from -0.4 to 0.8 V versus Ag|AgCl to demonstrate the versatility of this technique to study dopamine without the need of its oxidation. We used electrochemical impedance spectroscopy and single frequency electrochemical impedance to measure different concentrations of dopamine as low as 1 nM. Moreover, the capacitance of the microelectrodes surface was found to decrease due to dopamine adsorption, which is dependent on its concentration. The effect of dissolved oxygen and electrochemical oxidation of the surface in the detection of dopamine was also studied. Nonoxidized and oxidized carbon fiber microelectrodes were prepared and characterized by optical microscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Optimum working parameters of the electrodes, such as frequency and voltage, were obtained for better measurement. Electrochemical impedance of dopamine was determined at different concentration, voltages, and frequencies. Finally, dynamic experiments were conducted using a flow cell and single frequency impedance in order to study continuous and real-time measurements of dopamine.

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

New Concept of Cultivation Using Limited Strip-Tillage with Strip Shallow Irrigation

Directory of Open Access Journals (Sweden)

Yazid Ismi Intara

2014-04-01

Full Text Available Normal 0 false false false IN X-NONE X-NONE Dry land is one of land resources which potentially used for food crop cultivation, especially in the areas which have light to medium technical obstacles. The development of technology to improve soil quality in marginal lands to be productive lands is still widely open for agricultural development in Indonesia. Rooting medium quality can be improved by changing soil tillage method and observing the proper crop irrigation technology. It can be the solution for crop cultivation in clay loam soil. This study aimed to obtain water movement model in a minimally-tilled clay soil with strip shallow irrigation. The concept is limited soil-tillage with strip shallow irrigation method, water supply technique, and crop water requirement. Method used in this study includes developing water movement model (software development in a minimally-tilled clay soil with subsurface irrigation. In the final stages, research also conducted water movement analysis testing apparatus in the laboratory, field validation of the subsurface irrigation performance, and cultivation technique testing to chili pepper growth (Capsicum annuumL.. The development of water movement simulation on a limited strip-tillage with subsurface irrigation uses the concept to quantify the amount of water in the soil. The analysis of movement pattern was demonstrated on contour patterns. It showed that the wetting process can reach depth zone – 5 cm to the rooting zone. It was an important discovery on the development of minimum stripe tillage soil with subsurface irrigation. Specifically, it can be concluded that: the result of fitting by eyes to diffusivity graphic and water content obtained the required parameter values for soil physical properties. It was then simulated on horizontal water movement model on a minimum strip-tillage with strip shallow irrigation /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso

Determination of the phthalocyanine textile dye, reactive turquoise blue, by electrochemical techniques

Directory of Open Access Journals (Sweden)

Osugi Marly E.

2003-01-01

Full Text Available Turquoise blue 15 (AT15 is a reactive dye widely used in the textile industry to color natural fibers. The presence of these dyes in effluent and industrial wastewater is of considerable interest due ecotoxicological and environmental problems. The electrochemical reduction of this dye has been investigated in aqueous solution using cyclic voltammetry, controlled potential electrolysis and cathodic stripping voltammetry. Optimum conditions for dye discoloration by controlled potential electrolysis use an alkaline medium. Using cathodic stripping voltammetry a linear calibration graph was obtained from 5.00x10-8 mol L-1 to 1.00x10-6 mol L-1 of AT15 at pH 4.0, using accumulation times of 180 and 240 s and an accumulation potential of 0.0 V. The proposed method was applied in direct determination of the dye in tap water and in textile industry effluent.

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…

Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

OpenAIRE

Chen, Qing; Tian, Yuanyuan; Li, Peng; Yan, Changhui; Pang, Yu; Zheng, Li; Deng, Hucheng; Zhou, Wen; Meng, Xianghao

2017-01-01

Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indi...

Strip specimen tests for pipeline materials and girth welds

Energy Technology Data Exchange (ETDEWEB)

Mohr, William C. [Edison Welding Institute (EWI), Columbus, Ohio (United States)

2009-07-01

Strip specimen testing of pipeline materials has been widely applied as a method of getting data relevant to the performance of pipelines under axial direction loading. Comparisons of strip specimen against smaller standard tests (round tensile bar, fracture toughness specimens, polished round bars) and against full-scale or large-scale testing will be explored. Data from early-generation pipe welds from the 1920's to the 1940's to the most recent materials for offshore reeled pipe will be used for examples. Strip samples can provide full thickness information to take account of varying material properties or imperfection distribution through the thickness. Strip samples can also accommodate measurement of effects of the original surface finish or weld surface shape. Strip samples have more design flexibility than standard tests, but must be designed to limit stress concentrations and effects of local bending. (author)

Fatigue of graphite/epoxy buffer strip panels with center cracks

Science.gov (United States)

Bigelow, C. A.

1985-01-01

The effects of fatigue loading on the behavior of graphite/epoxy panels with either S-Glass or Kevlar-49 buffer strips is studied. Buffer strip panels are fatigued and tested in tension to measure their residual strength with crack-like damage. Panels are made with 45/0/-45/90 sub 2s layup with either S-Glass or Kevlar-49 buffer strip material. The buffer strips are parallel to the loading direction and made by replacing narrow strips of the 0-degree graphite plies with strips of either 0-degree S-Glass/epoxy or Kevlar-49/epoxy on a one-for-one basis. The panels are subjected to a fatigue loading spectrum MINITWIST, the shortened version of the standardized load program for the wing lower surface of a transport aircraft. Two levels of maximum strain are used in the spectrum with three durations of the fatigue spectrum. One group of panels is preloaded prior to the application of the fatigue cycling. The preload consists of statistically loading the spectrum in tension until the crack-tip damage zone reaches the ajacent buffer strips. After fatigue loading, all specimens are statistically loaded in tension to failure to determine their residual strengths.

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.

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.

Data acquisition software for the CMS strip tracker

International Nuclear Information System (INIS)

Bainbridge, R; Cripps, N; Fulcher, J; Radicci, V; Wingham, M; Baulieu, G; Bel, S; Delaere, C; Drouhin, F; Gill, K; Mirabito, L; Cole, J; Jesus, A C A; Giassi, A; Giordano, D; Gross, L; Hahn, K; Mersi, S; Nikolic, M; Tkaczyk, S

2008-01-01

The CMS silicon strip tracker, providing a sensitive area of approximately 200 m 2 and comprising 10 million readout channels, has recently been completed at the tracker integration facility at CERN. The strip tracker community is currently working to develop and integrate the online and offline software frameworks, known as XDAQ and CMSSW respectively, for the purposes of data acquisition and detector commissioning and monitoring. Recent developments have seen the integration of many new services and tools within the online data acquisition system, such as event building, online distributed analysis, an online monitoring framework, and data storage management. We review the various software components that comprise the strip tracker data acquisition system, the software architectures used for stand-alone and global data-taking modes. Our experiences in commissioning and operating one of the largest ever silicon micro-strip tracking systems are also reviewed

The development of drift-strip detectors based on CdZnTe

DEFF Research Database (Denmark)

Gostilo, V.; Budtz-Jørgensen, Carl; Kuvvetli, Irfan

2002-01-01

The design and technological development of a CdZnTe drift strip detector is described. The device is based on a monocrystal of dimensions 10 x 10 x 3 mm(3) and has a pitch of 200 mum and a strip width of 100 mum. The strip length is 9.5 mm. The distribution of the leakage currents of the strips...

Oxidation management of white wines using cyclic voltammetry and multivariate process monitoring.

Science.gov (United States)

Martins, Rui C; Oliveira, Raquel; Bento, Fatima; Geraldo, Dulce; Lopes, Vitor V; Guedes de Pinho, Paula; Oliveira, Carla M; Silva Ferreira, Antonio C

2008-12-24

The development of a fingerprinting strategy capable to evaluate the "oxidation status" of white wines based on cyclic voltammetry is proposed here. It is known that the levels of specific antioxidants and redox mechanisms may be evaluated by cyclic voltammetry. This electrochemical technique was applied on two sets of samples. One group was composed of normal aged white wines and a second group obtained from a white wine forced aging protocol with different oxygen, SO(2), pH, and temperature regimens. A study of antioxidant additions, namely ascorbic acid, was also made in order to establish a statistical link between voltammogram fingerprints and chemical antioxidant substances. It was observed that the oxidation curve presented typical features, which enables sample discrimination according to age, oxygen consumption, and antioxidant additions. In fact, it was possible to place the results into four significant orthogonal directions, compressing 99.8% of nonrandom features. Attempts were made to make voltammogram fingerprinting a tool for monitoring oxidation management. For this purpose, a supervised multivariate control chart was developed using a control sample as reference. When white wines are plotted onto the chart, it is possible to monitor the oxidation status and to diagnose the effects of oxygen regimes and antioxidant activity. Finally, quantification of substances implicated in the oxidation process as reagents (antioxidants) and products (off-flavors) was tried using a supervised algorithmic the partial least square regression analysis. Good correlations (r > 0.93) were observed for ascorbic acid, Folin-Ciocalteu index, total SO(2), methional, and phenylacetaldehyde. These results show that cyclic voltammetry fingerprinting can be used to monitor and diagnose the effects of wine oxidation.

Study of the voltammetric behaviour of the ethalfluralin and methalpropalin and its determination in environmental matrices at hanging mercury drop electrode.

Science.gov (United States)

Thriveni, T; Kumar, J Rajesh; Lee, Jin Young; Sreedhar, N Y

2009-04-01

An electroanalytical method has been developed for the determination of the herbicides ethalfluralin[N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) bezenamine] and methalpropalin [N-(2-methyl-2-propenyl)-2, 6-dinitro-N-propyl-4 (trifluoromethyl) benzenamine] by differential pulse adsorptive stripping voltammetry (DP-AdSV) on a hanging mercury drop electrode (HMDE) with universal buffer as supporting electrolyte. The optimum adsorption conditions were found to be pH 6.0, an accumulation potential of -0.6 V (HMDE vs SCE), an accumulation time of 80 s. and scan rate 45 mVs(-1). Calibration curve is linear in the range 1.30 x 10(-9) to 1.32 x 10(-5) M of ethalfluralin and 1.13 x 10(-5) to 2.0 x 10(-8) M of methalpropalin with detection limits of 1.08 x 10(-9) and 1.87 x 10(-8) M, respectively. The relative SD and correlation coefficients were found to be 1.24%, 0.998 and 1.34%, 0.995, respectively for ten replicates. The method is applied to the determination of the ethalfluralin and methalpropalin in formulations and environmental matrices.

Eddy current distribution and lift force for finite MAGLEV strips

Energy Technology Data Exchange (ETDEWEB)

Atherton, D L; Eastham, A R; Fombrun, C; Chong, M

1974-07-01

The transverse distribution of induced eddy currents across a flat conducing strip of finite width, due to a rectangular dc magnet moving above it, was modelled experimentally, and was compared with that calculated for an infinite sheet. The electrodynamic suspension was simulated by means of a stationary ac-excited copper magnet suspended above an aluminum strip, and the induced surface current density was measured by a voltage pickup probe connected to a lock-in amplifier. The effect of reducing strip width is examined and shown to produce high current densities close to the edges. These results are related to the variation of lift force with strip width, determined by impedance modelling. A slight enhancement of lift is evident for intermediate strip widths.

Development of on-line electrochemical sample pretreatment methods for the analysis of thallium and uranium by ICP-MS

International Nuclear Information System (INIS)

Zhou, F.; Van Berkel, G.J.; Morton, S.J.; Duckworth, D.C.; Adeniyi, W.K.; Keller, J.M.

1995-01-01

Anodic and adsorptive stripping voltammetry (AWV and AdSV, respectively) were performed on-line with a mercury thin-film electrode (MTFE) to effect the selective accumulation and detection of thallium and uranium, respectively. ASV-ICP-MS experiments using thallium as the test element were performed to characterize the behavior of the on-line system for low level and quantitative determinations. Excellent linearity in response was demonstrated for thallium standards ranging from 0.25 ng/L to 50 microg/L. The 1.0 pg/L detection limit calculated from this data for thallium (3σ/sensitivity) was 400 times lower than that of conventional ICP-MS. The ability to overcome sample matrix effects in quantitative determinations was demonstrated by the analysis of an undiluted synthetic urine sample. AdSV-ICP-MS experiments were performed using uranium as the test element to demonstrate the utility of this method for the determination of radiologically important elements. A uranium(VI)-cupferron complex was used to effect adsorptive accumulation of uranium from a 10 microg/L standard solution onto the MTFE. The uranium was chemically stripped from the electrode for subsequent downstream detection by the ICP-MS. The quantitative nature of this method and a modest enhancement of signal levels (∼X10) over those levels obtained with conventional ICP-MS for samples in the microgram/liter concentration range were demonstrated. Modifications to the current system to provide low flow rate operation will allow further optimization of the ASV-ICP-MS and AdSV-ICP-MS combinations

DNA bases assembled on the Au(110)/electrolyte interface: A combined experimental and theoretical study

DEFF Research Database (Denmark)

Salvatore, Princia; Nazmutdinov, Renat R.; Ulstrup, Jens

2015-01-01

Among the low-index single-crystal gold surfaces, the Au(110) surface is the most active toward molecular adsorption and the one with fewest electrochemical adsorption data reported. Cyclic voltammetry (CV), electrochemically controlled scanning tunneling microscopy (EC-STM), and density functional......, accompanied by a pair of strong voltammetry peaks in the double-layer region in acid solutions. Adsorption of the DNA bases gives featureless voltammograms with lower double-layer capacitance, suggesting that all the bases are chemisorbed on the Au(110) surface. Further investigation of the surface structures...... of the adlayers of the four DNA bases by EC-STM disclosed lifting of the Au(110) reconstruction, specific molecular packing in dense monolayers, and pH dependence of the A and G adsorption. DFT computations based on a cluster model for the Au(110) surface were performed to investigate the adsorption energy...

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.

LYCORIS - A Large Area Strip Telescope

CERN Document Server

Krämer, U; Stanitzki, M; Wu, M

2018-01-01

The LYCORIS Large Area Silicon Strip Telescope for the DESY II Test Beam Facility is presented. The DESY II Test Beam Facility provides elec- tron and positron beams for beam tests of up to 6 GeV. A new telescope with a large 10 × 20 cm2 coverage area based on a 25 μm pitch strip sensor is to be installed within the PCMAG 1 T solenoid. The current state of the system is presented.

Determination of Trace Amounts of Gold in Environmental Samples by Adsorptive Stripping Voltammetry of Its Complex with Rhodamine Using Osc-Pls

Directory of Open Access Journals (Sweden)

A. Akrami

2012-11-01

Full Text Available The multivariate calibration method was applied for the determination of trace amounts of gold based on a hanging mercury drop electrode (HMDE in the presence of rhodanine, followed by reduction of adsorbed gold by voltammetric scan using differential pulse modulation The optimum experimental conditions are: rhodanine concentration of 0.20 mg mL-1, pH 5.0, accumulation potential of -600 mV versus Ag/AgCl, accumulation time of 100 sec, scan rate of 30 mV s-1 and pulse height of 100 mV. The calibration matrix for partial least squares (PLS regression was designed with 9 samples. Orthogonal signal correction (OSC is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for PLS calibration without loss of prediction capacity using electrochemical method. The RMSEP for gold determination with PLS and OSC-PLS were 8.51 and 1.94, respectively. This procedure allows the determination of gold in synthetic and real samples with good reliability of the determination. 

Combined effect of bulk and surface damage on strip insulation properties of proton irradiated n$^{+}$-p silicon strip sensors

CERN Document Server

Dalal, R; Ranjan, K; Moll, M; Elliott-Peisert, A

2014-01-01

Silicon sensors in next generation hadron colliders willface a tremendously harsh radiation environment. Requirement tostudy rarest reaction channels with statistical constraints hasresulted in a huge increment in radiation flux, resulting in bothsurface damage and bulk damage. For sensors which are used in acharged hadron environment, both of these degrading processes takeplace simultaneously. Recently it has been observed in protonirradiated n$^{+}$-p Si strip sensors that n$^{+}$ strips had a goodinter-strip insulation with low values of p-spray and p-stop dopingdensities which is contrary to the expected behaviour from thecurrent understanding of radiation damage. In this work a simulationmodel has been devised incorporating radiation damage to understandand provide a possible explanation to the observed behaviour ofirradiated sensors.

Voltammetry under a Controlled Temperature Gradient

Directory of Open Access Journals (Sweden)

Jan Krejci, Jr.

2010-07-01

Full Text Available Electrochemical measurements are generally done under isothermal conditions. Here we report on the application of a controlled temperature gradient between the working electrode surface and the solution. Using electrochemical sensors prepared on ceramic materials with extremely high specific heat conductivity, the temperature gradient between the electrode and solution was applied here as a second driving force. This application of the Soret phenomenon increases the mass transfer in the Nernst layer and enables more accurate control of the electrode response enhancement by a combination of diffusion and thermal diffusion. We have thus studied the effect of Soret phenomenon by cyclic voltammetry measurements in ferro/ferricyanide. The time dependence of sensor response disappears when applying the Soret phenomenon, and the complicated shape of the cyclic voltammogram is replaced by a simple exponential curve. We have derived the Cotrell-Soret equation describing the steady-state response with an applied temperature difference.

Induction heating in in-line strip production process

International Nuclear Information System (INIS)

Costa, P.; Santinelli, M.

1995-05-01

ISP (In-line Strip Production), a continuous process for steel strip production, has recently been set in an italian innovative plant, where ecological impact and power requirements are lighter than usual. This report describes the studies performed by ENEA (Italian Agency for New Technologies, Energy and the Environment), while a prototype reheating facility was arranged by Acciaieria ISP in Cremona (Italy). The authors, after a study of the prototype electromagnetic field, calculate the heating rate, with the thermal network method. Then they detect, with a 1-D-FEM, the heat diffusion through the strip cross section. Afterward, since the heat distribution depends on the eddy current density one, which is given by the magnetic field distribution, the authors, with a 3-D-FEM, carry out a coupled, electromagnetic and thermal, analysis in time domain. The strip temperature map is established by the balance between skin depth heating and surface cooling: a thermal analysis, performed with a moving 2-D-FEM, take into account the effects of the different heating and cooling situations, originated by the strip moving at a speed of 6m/min through four consecutive reheating facilities. The temperatures of a strip sample heated by the prototype have been monitored, acquired by a computer and related with the simulation results. The little difference between experiment and simulation assessed the qualitative and quantitative validity of this analysis, that has come out to be a tool, useful to evaluate the effects of possible improvements to the ISP process

Electrochemical behavior of the antituberculosis drug isoniazid and its square-wave adsorptive stripping voltammetric estimation in bulk form, tablets and biological fluids at a mercury electrode.

Science.gov (United States)

Ghoneim, M M; el-Baradie, K Y; Tawfik, A

2003-11-24

Isoniazid, pyridine-4-carboxylic acid hydrazide, is an antituberculosis-agent, which is used to prevent the development of clinical tuberculosis. A validated square-wave adsorptive cathodic stripping voltammetric procedure for the trace determination of the bulk drug at the hanging mercury drop electrode (HMDE) has been developed. Under the optimized conditions, (accumulation potential=-0.9 V, accumulation time=50-300 s, scan increment=8 mV, pulse-amplitude=25 mV, frequency=120 Hz and acetate buffer at pH 5.5) isoniazed generated two irreversible cathodic peaks. The first peak current showed a linear dependence with the drug concentration over the range 5 x 10(-10)-21 x 0(-6) M. The mean percentage recoveries, based on the average of five replicate measurements, for 7 x 10(-9) and 5 x 10(-8) M isoniazid were 97.71+/-2.93 and 99.76+/-0.77, respectively. The achieved limits of detection (LOD) and quantitation (LOQ) were 1.18 x 10(-10) and 3.93 x 10(-10) M isoniazid, respectively. The procedure was applied to the assay of the drug in tablets (Isocid and T.B. Zide), spiked human serum and urine with mean percentage recoveries of 97.81+/-1.49, 97.45+/-2.09, and 97.08+/-1.06, respectively. The limits of detection of 1.47 x 10(-9) and 2.4 x 10(-8) M, and quantitation of 4.9 x 10(-9) and 8 x 10(-8) M drug in human serum and urine, respectively, were achieved. The mean values of the various pharmackinetic parameters of isoniazid (C(max), T(max), t(1/2), AUC, and K(e)), estimated from analysis of plasma of two volunteers by means of the proposed procedure were similar to literature values.

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)

Simultaneous determination of mycophenolate mofetil and its active metabolite, mycophenolic acid, by differential pulse voltammetry using multi-walled carbon nanotubes modified glassy carbon electrode

Energy Technology Data Exchange (ETDEWEB)

Madrakian, Tayyebeh, E-mail: madrakian@basu.ac.ir; Soleimani, Mohammad; Afkhami, Abbas

2014-09-01

A highly sensitive electrochemical sensor for the simultaneous determination of mycophenolate mofetil (MPM) and mycophenolic acid (MPA) was fabricated by multi-walled carbon nanotubes modified glassy carbon electrode (MWCNTs/GCE). The electrochemical behavior of these two drugs was studied at the modified electrode using cyclic voltammetry and adsorptive differential pulse voltammetry. MPM and MPA were oxidized at the GCE during an irreversible process. DPV analysis showed two oxidation peaks at 0.87 V and 1.1 V vs. Ag/AgCl for MPM and an oxidation peak at 0.87 V vs. Ag/AgCl for MPA in phosphate buffer solution of pH 5.0. The MWCNTs/GCE displayed excellent electrochemical activities toward oxidation of MPM and MPA relative to the bare GCE. The experimental design algorithm was used for optimization of DPV parameters. The electrode represents linear responses in the range 5.0 × 10{sup −6} to 1.6 × 10{sup −4} mol L{sup −1} and 2.5 × 10{sup −6} mol L{sup −1} to 6.0 × 10{sup −5} mol L{sup −1} for MPM and MPA, respectively. The detection limit was found to be 9.0 × 10{sup −7} mol L{sup −1} and 4.0 × 10{sup −7} mol L{sup −1} for MPM and MPA, respectively. The modified electrode showed a good sensitivity and stability. It was successfully applied to the simultaneous determination of MPM and MPA in plasma and urine samples. - Highlights: • A new modified electrochemical sensor was constructed and used. • Multiwalled carbon nanotubes were used as the modifiers. • MPM and MPA were measured simultaneously at the low levels. • The sensor was used to the determination of MPA and MPM in real samples.

Water adsorption on goethite: Application of multilayer adsorption models

Science.gov (United States)

Hatch, C. D.; Tumminello, R.; Meredith, R.

2016-12-01

Adsorbed water on the surface of atmospheric mineral dust has recently been shown to significantly affect the ability of mineral dust aerosol to act as cloud condensation nuclei. We have studied water adsorption as a function of relative humidity (RH) on goethite (α-FeO(OH)), a common component of atmospheric mineral dust. The goethite surface area and particle size was determined using BET analysis and with N2 as an adsorbate and scanning electron microscopy, respectively. Water adsorption on the sample was monitored using horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy equipped with a flow cell. Water content was determined using Beer's law and the optical constants for bulk water. The results were analyzed using Type II adsorption isotherms to model multilayer adsorption, including BET (Brunauer, Emmet and Teller), FHH (Frenkel, Halsey and Hill) and Freundlich. BET fits to experimental data provide parameters of monolayer coverage, while the FHH and Freundlich isotherms provide insights into multilayer adsorption mechanisms. Results indicate that goethite contains 5% H2O by mass at 50% RH, which increases to 12% by mass at 90% RH. Adsorption parameters and experimental results will be presented.

31 CFR 356.31 - How does the STRIPS program work?

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false How does the STRIPS program work? 356.31 Section 356.31 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued...) Miscellaneous Provisions § 356.31 How does the STRIPS program work? (a) General. Notes or bonds may be “stripped...

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.

Magnetic ring for stripping enhancement

International Nuclear Information System (INIS)

Selph, F.

1992-10-01

A ring designed to recycle ions through a stripping medium offers the possibility for increasing output of the desired charge state by up to 4x. This could be a very important component of a Radioactive Nuclear Beam Facility. In order for such a ring to work effectively it must satisfy certain design conditions. These include achromaticity at the stripper, a dispersed region for an extraction magnet, and a number of first and higher order optics constraints which are necessary to insure that the beam emittance is not degraded unduly by the ring. An example is given of a candidate design of a stripping ring

Phenolic resin-based porous carbons for adsorption and energy storage applications

Science.gov (United States)

Wickramaratne, Nilantha P.

The main objective of this dissertation research is to develop phenolic resin based carbon materials for range of applications by soft-templating and Stober-like synthesis strategies. Applications Studied in this dissertation are adsorption of CO2, bio-molecular and heavy metal ions, and energy storage devices. Based on that, our goal is to design carbon materials with desired pore structure, high surface area, graphitic domains, incorporated metal nanoparticles, and specific organic groups and heteroatoms. In this dissertation the organic-organic self-assembly of phenolic resins and triblock copolymers under acidic conditions will be used to obtain mesoporous carbons/carbon composites and Stober-like synthesis involving phenolic resins under basic condition will be used to prepare polymer/carbon particles and their composites. The structure of this dissertation consists of an introductory chapter (Chapter 1) discussing the general synthesis of carbon materials, particularly the soft-templating strategy and Stober-like carbon synthesis. Also, Chapter 1 includes a brief outline of applications namely adsorption of CO2, biomolecule and heavy metal ions, and supercapacitors. Chapter 2 discusses the techniques used for characterization of the carbon materials studied. This chapter starts with nitrogen adsorption analysis, which is used to measure the specific surface area, pore volume, distribution of pore sizes, and pore width. In addition to nitrogen adsorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution thermogravimetric analysis (HR-TGA), cyclic voltammetry (CV) and CHNS elemental analysis (EA) are mentioned too. Chapter 3 is focused on carbon materials for CO2 adsorption. There are different types of porous solid materials such as silicate, MOFs, carbons, and zeolites studied for CO2 adsorption. However, the carbon based materials are considered to be the best candidates for CO 2 adsorption to the industrial point of

Analysis Of The Underpotential Deposition Of Cadmium On Copper

Directory of Open Access Journals (Sweden)

Kowalik R.

2015-09-01

Full Text Available In this study the process of deposition of cadmium on polycrystalline copper electrode in sulfate solution was investigated. The process of underpotential and bulk deposition was analyzed by classical electrochemical method: cyclic voltammetry(CV, anodic stripping voltammetry(ASV and electrochemical quartz crystal microbalance(EQCM. The obtained results were compared with electrochemical impedance spectroscopy(EIS measurements. CV, EQCM and EIS results suggest that the UPD of cadmium starts below potential −0.4 V vs Ag/AgCl. Additionally the stripping analysis indicates the formation of cadmium monolayer with different density of deposited atoms depending on the applied potential. The transition from UPD to bulk deposition occurs below potential −0,7 V.

Comportamiento electroquímico de un electrodo de oro modificado con una monocapa autoensamblada del ácido 2-N-bencil-1- ciclopenten-di-tiocarboxílico

Directory of Open Access Journals (Sweden)

R.R. Contreras

2009-01-01

Full Text Available The study of coverage (nmol/cm-2 of N-bencyl-1-cyclopenten-di-thiocarboxylic acid (novel compound depending on the immersion time of the gold electrode in a solution of the mentioned compound, as well as the characterization of the adsorbed monolayer has been carried out by cyclic voltammetry (CV. The self assembled monolayer (SAM has been tested for stability in defined potential intervals and blocking properties for electron transfer [Fe(CN6]3-/[Fe(CN6]4- and Cu(II. Detection and quantifying of copper by stripping of underpotential deposits and by stripping of bulk deposition formed at the modified gold electrode was carried out by square wave voltammetry (SWV in copper-free phosphate buffer.

Sensitive stripping voltammetric determination of Cd(II) and Pb(II) by a Bi/multi-walled carbon nanotube-emeraldine base polyaniline-Nafion composite modified glassy carbon electrode

International Nuclear Information System (INIS)

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

2016-01-01

Highlights: • A MWCNT-EBP-NA composite film modified GCE was fabricated and characterized. • The GCE modified with the MWCNT-EBP-NA composite film exhibited excellent performance in the analysis of Cd(II) and Pb(II) by SWASV. • The Cd(II) and Pb(II) detection limits of the developed electrode were approximately 0.06 μg/L and 0.08 μg/L, respectively. • Bi/MWCNT-EBP-NA/GCE was successfully used to determine metal ions in soil samples. - Abstract: In this study, a multi-walled carbon nanotube (MWCNT)-emeraldine base polyaniline (EBP)-Nafion (NA) composite modified glassy carbon electrode (MWCNT-EBP-NA/GCE) was prepared and used for the sensitive detection of trace Pb(II) and Cd(II), with a detection limit of 0.06 μg/L for Cd(II) and 0.08 μg/L for Pb(II) (S/N = 3), by square wave anodic stripping voltammetry (SWASV). A bismuth film was prepared through the in situ plating of bismuth on the MWCNT-EBP-NA/GCE. The morphologies and electrochemical properties of the modified electrode were characterized by SWASV, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The parameters affecting the stripping current response were investigated and optimized. The formed MWCNTs in the composite film enlarged the specific surface area of the electrode and significantly promoted electron transferring, and the formed polyaniline (PANI) enhanced the ion-exchange capacity and prevented the macromolecules in real samples from absorbing onto the surface of the electrode. The presence of NA effectively increased the stability and adhesion of the composite film, enhanced the cation-exchange capacity and improved the ability to preconcentrate metal ions. Under the optimized conditions, a linear range of 1.0 to 50.0 μg/L was achieved for both metal ions, with a detection limit of 0.06 μg/L for Cd(II) and 0.08 μg/L for Pb(II) (S/N = 3), offering good repeatability. Finally, the Bi/MWCNT-EBP-NA/GCE was used for the

Do repeated rumble strip hits improve driver alertness?

NARCIS (Netherlands)

Watling, C.N.; Akerstedt, T.; Kecklund, L.G.; Anund, A.

2016-01-01

Driving while sleepy is associated with increased crash risk. Rumble strips are designed to alert a sleepy or inattentive driver when they deviate outside their driving lane. The current study sought to examine the effects of repeated rumble strip hits on levels of physiological and subjective

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

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.

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.)

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite.

Directory of Open Access Journals (Sweden)

Yajun Chen

Full Text Available Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR and ciprofloxacin (CIP, by nano-hydroxyapatite (n-HAP were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g · L(-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics.

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite

Science.gov (United States)

Chen, Yajun; Lan, Tao; Duan, Lunchao; Wang, Fenghe; Zhao, Bin; Zhang, Shengtian; Wei, Wei

2015-01-01

Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g·L-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics. PMID:26698573

Refuges, flower strips, biodiversity and agronomic interest.

Science.gov (United States)

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

2008-01-01

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

Estimation of key physical properties for LaCl_3 in molten eutectic LiCl–KCl by fitting cyclic voltammetry data to a BET-based electrode reaction kinetics model

International Nuclear Information System (INIS)

Samin, Adib; Wang, Zhonghang; Lahti, Erik; Simpson, Michael; Zhang, Jinsuo

2016-01-01

Understanding the electrochemical properties of rare earth elements is important for developing efficient techniques for separating rare earth elements from actinides recovered during the electrodeposition process. In this study the cyclic voltammetry for lanthanum in molten LiClKCl eutectic was recorded at 773 K for different scan rates and different bulk concentrations. A model accounting for mass transport, kinetics and adsorption was applied to analyze the experimental data via performing a nonlinear least squares fit. The results of the simulation are compared against the results of a conventional analysis of the cyclic voltammograms and against the existing literature. At the scan rates used, the reduction/oxidation process is quasi-reversible. The values of diffusivities derived from simulation were larger than the ones derived commonly using equations for diffusion-limited processes. However, those equations were derived based on an assumption of reversibility. This simulation-based approach may provide a more accurate option for analyzing systems that do not exhibit reversibility.

Optimization of the process of steel strip perforation and nickel platting for the purpose of elimination of trichloroethylene from the cleaning process of perforated steel strip

Directory of Open Access Journals (Sweden)

Petrović Aleksandra B.

2009-01-01

Full Text Available In the production of pocket type electrodes for Ni-Cd batteries perforation of proper steel strips and then nickel platting of perforated steel strips were made. In the nickel platting process, the organic solvent, trichloroethylene, has previously been used for cleaning. Due to the carcinogenic nature of trichloroethylene and the many operations previously required during cleaning, it was considered to do cleaning of perforated steel strips without use of the mentioned organic solvent. In the purpose of elimination of trichloroethylene from the cleaning process of perforated steel strips, the tests of perforation of steel strips with use of oils of different viscosity were made. It was shown that there was no dysfunction during the work of the perforation plants, meaning there was no additional heating of the strips, deterring of the steel filings, nor excessive wearing of the perforation apparatus. The perforation percent was the same irrelevant of the viscosity of the used oil. Before being perforated using the oils with different viscosity, the nickel platting steel strips were cleaned in different degreasers (based on NaOH as well as on KOH. It was shown that efficient cleaning without the use of trichloroethylene is possible with the use of oil with smaller viscosity in the perforated steel strips process and the degreaser based on KOH in the cleaning process, before nickel platting. It also appeared that the alkali degreaser based on KOH was more efficient, bath corrections were made less often and the working period of the baths was longer, which all in summary means less quantity of chemicals needed for degreasing of perforated steel strips.

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

International Nuclear Information System (INIS)

Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

2013-01-01

Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

Energy Technology Data Exchange (ETDEWEB)

Nam, Sangchul; Namkoong, Wan [Department of Environmental Engineering, Konkuk University, Hwayang-Dong, Gwangjin-Gu, Seoul 143-701 (Korea, Republic of); Kang, Jeong-Hee; Park, Jin-Kyu [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of); Lee, Namhoon, E-mail: nhlee@anyang.ac.kr [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of)

2013-10-15

Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

Langmuir and Freundlich Isotherm Adsorption Equations for Chromium (VI) Waste Adsorption by Zeolite

International Nuclear Information System (INIS)

Murni Handayani; Eko Sulistiyono

2009-01-01

The research of chromium (VI) waste adsorption by zeolite has done. Wastes which are produced by Industries, both radioactive waste and heavy metal waste need done more processing so that they are not endanger environment and human health. Zeolite has very well-ordered crystal form with cavity each other to way entirely so that cause surface wide of zeolite become very big and very good as adsorbents. This research intends to know appropriate isotherm adsorption method to determine maximum capacity of zeolite to chromium (VI) waste. The equations which used in adsorption process are Langmuir and Freundlich isotherm Adsorption equations. The instrument was used in adsorption process by using Atomic Adsorption Spectroscopy (AAS). The experiment result showed that the biggest mass of chromium (VI) metal ion which was absorb by zeolite in 20 ppm concentration was 7.71 mg/gram zeolite. Adsorption process of Chromium (VI) waste by zeolite followed Langmuir and Freundlich isotherm equations with R 2 >0,9 . Appropriate equation to determine maximum adsorption capacity of zeolite for chromium (VI) waste adsorption is Langmuir equation. The maximum adsorption capacity of zeolite is 52.25 mg/gram. (author)

Polymer Inclusion Membranes with Strip Dispersion

Directory of Open Access Journals (Sweden)

Yueh-Hsien Li

2017-06-01

Full Text Available The present work investigated the permeation of indium ions through a polymer inclusion membrane (PIM, prepared with cellulose triacetate (CTA as the base polymer, tris(2-butoxyethyl phosphate (TBEP as the plasticizer and di-(2-ethylhexylphosphoric acid (D2EHPA as the extractant. With 5 M HCl aqueous solution as the strip solution, we observed an initial indium permeability of 2.4 × 10−4 m/min. However, the permeability decreases with time, dropping to about 3.4 × 10−5 m/min after 200 min of operation. Evidence was obtained showing that hydrolysis of CTA occurred, causing a dramatic decrease in the feed pH (protons transported from strip to feed solutions and a loss of extractant and plasticizer from the membrane, and then leading to the loss of indium permeability. To alleviate the problem of hydrolysis, we proposed an operation scheme called polymer inclusion membranes with strip dispersion: dispersing the strip solution in extractant-containing oil and then bringing the dispersion to contact with the polymer membrane. Since the strong acid was dispersed in oil, the membrane did not directly contact the strong acid at all times, and membrane hydrolysis was thus alleviated and the loss of indium permeability was effectively prevented. With the proposed scheme, a stable indium permeability of 2.5 × 10−4 m/min was obtained during the whole time period of the permeation experiment.

Validity of HydraTrend reagent strips for the assessment of hydration status.

Science.gov (United States)

Abbey, Bryce M; Heelan, Kate A; Brown, Gregory A; Bartee, Rodrick T

2014-09-01

Hydration is used by athletic governing organizations for weight class eligibility. The measurement of urine specific gravity (USG) as a measure of hydration by reagent strips is a controversial issue. The purpose of this study was to determine the validity of HydraTrend reagent strips that facilitate the correction of USG for alkaline urine samples against refractometry for the assessment of USG. Fifty-one participants (33 males, age = 22.3 ± 1.3 years; 18 females, age = 22.4 ± 1.2 years) provided 84 urine samples. The samples were tested for USG using refractometry and reagent strips and for pH using reagent strips and a digital pH meter. Strong correlation coefficients were found between refractometry and reagent strips for USG (rs(82) = 0.812, p refractometry with USG >1.020, pass reagent strips with USG ≤1.020) occurred 39% (33/84) of the time and false negative results for National Federation of State High School Association (NFHS) requirements (fail refractometry with USG >1.025, pass reagent strips with USG ≤1.025) occurred 14% (12/84) of the time. There were no false positives (pass refractometry and fail reagent strips) for NCAA or NFHS requirements. These data show that refractometry and reagent strips have strong positive correlations. However, the risk of a false negative result leading to incorrect certification of euhydration status outweighs the benefits of the HydraTrend reagent strips for the measurement of USG.

Significance of wave form parameters in stripping chronopotentiometric metal speciation analysis

NARCIS (Netherlands)

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

2002-01-01

An analysis is presented of the significance of stripping chronopotentiometric (SCP) stripping peak parameters (peak potential, Ep, and peak half-width, w1/2) for determination of metal ion speciation. This study focuses on depletive SCP (low stripping current, I¿ constant), and considers the change

Electrode/Dielectric Strip For High-Energy-Density Capacitor

Science.gov (United States)

Yen, Shiao-Ping S.

1994-01-01

Improved unitary electrode/dielectric strip serves as winding in high-energy-density capacitor in pulsed power supply. Offers combination of qualities essential for high energy density: high permittivity of dielectric layers, thinness, and high resistance to breakdown of dielectric at high electric fields. Capacitors with strip material not impregnated with liquid.

Strip reduction testing of lubricants developed during ENFORM project

DEFF Research Database (Denmark)

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

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

Adsorption. What else?

OpenAIRE

Rodrigues, Alirio E.

2012-01-01

[EN] Chemical Engineering today combines Molecular and Materials Engineerig and Process and Product Engineering (ChE=M2P2). Cyclic adsorptive processes (Simulated Moving Bed –SMB and Pressure Swing Adsorption-PSA) will be discussed for “old” and “new” applications making use of “old” and “new” (MOFs) adsorbent materials. After revisiting my memory as PhD student and the First Brazilian Adsorption meeting I will review the basic concepts involved in adsorption processes and then...

Micro-strip Metal Foil Detectors for the Beam Profile Monitoring

CERN Document Server

Pugatch, V M; Fedorovitch, O A; Mikhailenko, A V; Prystupa, S V; Pylypchenko, Y

2005-01-01

The Micro-strip Metal Foil Detectors (MMFD) designed and used for the Beam Profile Monitoring (BPM) are discussed. Fast particles hitting a metal strip initiate Secondary Electron Emission (SEE) which occurs at 10 - 50 nm surface layers of a strip. The SEE yield is measured by a sensitive Charge Integrator with built-in current-to-frequency converter (1 Hz per 1 fA). The MMFD (deposited onto the 20 μm thick Si-wafer) with 32 Al strips (10 μm wide, 32 μm pitch) has been used for the BPM of the 32 MeV alpha-particle beam at the MPIfK (Heidelberg) Tandem generator for Single-Event-Upset studies of the BEETLE micro-chip. Similar MMFD (0.5 μm thick Ni-strips) with totally removed Si-wafer (by plasma-chemistry, at the working area of 8 x 10 mm2) has been applied for the on-line X-ray BPM at the HASYLAB (DESY). The number of photons (11.3 GeV, mean X-ray energy 18 keV) producing out of a strip a single SEE was evaluated as (1.5 ±0.5)* 104. MMFD has demonstrated stable...

Thin-layer voltammetry of soluble species on screen-printed electrodes: proof of concept.

Science.gov (United States)

Botasini, S; Martí, A C; Méndez, E

2016-10-17

Thin-layer diffusion conditions were accomplished on screen-printed electrodes by placing a controlled-weight onto the cast solution and allowing for its natural spreading. The restricted diffusive conditions were assessed by cyclic voltammetry at low voltage scan rates and electrochemical impedance spectroscopy. The relationship between the weight exerted over the drop and the thin-layer thickness achieved was determined, in such a way that the simple experimental set-up designed for this work could be developed into a commercial device with variable control of the thin-layer conditions. The experimental results obtained resemble those reported for the voltammetric features of electroactive soluble species employing electrodes modified with carbon nanotubes or graphene layers, suggesting that the attainment of the benefits reported for these nanomaterials could be done simply by forcing the solution to spread over the screen-printed electrodic system to form a thin layer solution. The advantages of thin-layer voltammetry in the kinetic characterization of quasi-reversible and irreversible processes are highlighted.

Removal of nitrogen from swine manure by ammonia stripping; Reduccion del contenido en nitrogeno amoniacal del purin procino mediante la tecnica de stripping

Energy Technology Data Exchange (ETDEWEB)

Hidalgo, M. D.; Alamo, J. del; Nunez, U.; Irusta, R. [Grupo de Tecnologia Ambiental . Laboratorio de Analisis y Estudios Medioambientales. Valladolid (Spain)

2001-07-01

Lab scale experiments were undertaken to investigate air stripping as method for removing ammonia from cattle effluents and, more concretely, from the liquid fraction of swine manure. The effects of packet size, influent pH, air to liquid flow ratio and liquid recirculation flow in the stripping tower were investigated. The high ammonia removal efficiency of the air stripping method indicates that it could provide an interim solution for current waste management problems in the swine industry. (Author) 5 refs.

Adsorption of antimony onto iron oxyhydroxides: Adsorption behavior and surface structure

Energy Technology Data Exchange (ETDEWEB)

Guo, Xuejun; Wu, Zhijun [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); He, Mengchang, E-mail: hemc@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); Meng, Xiaoguang [Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Jin, Xin [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); Qiu, Nan; Zhang, Jing [Beijing Synchrotron Radiation Facility (BSRF), Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2014-07-15

Graphical abstract: - Highlights: • Antimony adsorption depended on the Sb species, pH, and the type of iron oxides. • Sb(V) adsorption favored at acidic pH, Sb(III) adsorption optimized in wider pH. • Antimony was adsorbed onto the iron oxides by the inner-sphere surface complex. • Bidentate mononuclear ({sup 2}E) was the dominant form of Sb incorporated into HFO. • XAFS and XPS indicated Sb(III) adsorbed was slowly oxidized to Sb(V). - Abstract: Antimony is detected in soil and water with elevated concentration due to a variety of industrial applications and mining activities. Though antimony is classified as a pollutant of priority interest by the United States Environmental Protection Agency (USEPA) and Europe Union (EU), very little is known about its environmental behavior and adsorption mechanism. In this study, the adsorption behaviors and surface structure of antimony (III/V) on iron oxides were investigated using batch adsorption techniques, surface complexation modeling (SCM), X-ray photon spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS). The adsorption isotherms and edges indicated that the affinity of Sb(V) and Sb(III) toward the iron oxides depended on the Sb species, solution pH, and the characteristics of iron oxides. Sb(V) adsorption was favored at acidic pH and decreased dramatically with increasing pH, while Sb(III) adsorption was constant over a broad pH range. When pH is higher than 7, Sb(III) adsorption by goethite and hydrous ferric oxide (HFO) was greater than Sb(V). EXAFS analysis indicated that the majority of Sb(III), either adsorbed onto HFO or co-precipitated by FeCl{sub 3}, was oxidized into Sb(V) probably due to the involvement of O{sub 2} in the long duration of sample preservation. Only one Sb–Fe subshell was filtered in the EXAFS spectra of antimony adsorption onto HFO, with the coordination number of 1.0–1.9 attributed to bidentate mononuclear edge-sharing ({sup 2}E) between Sb and

Evaluation of adsorption and Fenton-adsorption processes for landfill leachate treatment

OpenAIRE

San Pedro-Cedillo, L.; Méndez-Novelo, R.I.; Rojas-Valencia, M.N.; Barceló-Quintal, M.; Castillo-Borges, E.R.; Sauri-Riancho, M.R.; Marrufo-Gómez, J.M.

2015-01-01

The objective of this research was to compare the adsorption and Fenton-adsorption treatments for the removal of contaminants in leachate from landfills and thus determine the most efficient one. The adsorption process with granular activated carbon was tested in two types of samples: raw leachate and leachate treated by Fenton. The results showed color, chemical oxygen demand (COD), total nitrogen and total organic carbon (TOC) removal rates higher than 99% through the Fenton-adsorption proc...

Flexible strip supercapacitors for future energy storage

OpenAIRE

Zhang, R-R; Xu, Y-M; Harrison, D; Fyson, J; Qiu, F-L; Southee, D

2015-01-01

Flexible strip supercapacitors are developed and their electrochemical properties are characterized. Activated carbon is used as the electrode material and it is found to have a good porous structure which provides a large surface area for energy storage. Furthermore, this activated carbon performs well. The manufacturing processes for the supercapacitors are described in detail and the preparation process has good reproducibility. The strip supercapacitors are combined in series and parallel...

Comparative characteristics of polystyrene scintillation strips

International Nuclear Information System (INIS)

Gapienko, V.A.; Denisov, A.G.; Mel'nikov, E.A.

1992-01-01

Results are provided for a study of the main characteristics of polystyrene scintillation strips with a cross-section of 200 x 10 mm with two different scintillation-additive compositions: 1.5% p-terphenyl + 0.01% POPOP and 1.5% p-terphenyl + 0.01% DBP. The mean light-attenuation lengths are 180 cm and 260 cm, respectively, for strips with POPOP and DBP. The emittances of the polystyrene scintillators with DBP and POPOP additives have a ratio of 0.8:1.0 as recorded by an FEU-110 photomultiplier. 2 refs., 1 fig., 2 tabs

Method for thermal swing adsorption and thermally-enhanced pressure swing adsorption

Science.gov (United States)

Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

2003-10-07

The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

Apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

Science.gov (United States)

Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

2005-12-13

The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

Study the Z-Plane Strip Capacitance

International Nuclear Information System (INIS)

Parikh, H.; Swain, S.

2005-01-01

The BaBaR detector at the Stanford Linear Accelerator Center is currently undergoing an upgrade to improve its muon and neutral hadron detection system. The Resistive Plate Chambers (RPCs) that had been used till now have deteriorated in performance over the past few years and are being replaced by Limited Streamer Tube (LSTs). Each layer of the system consists of a set of up to 10 streamer tube modules which provide one coordinate (φ coordinate) and a single ''Z-plane'' which provides the Z coordinate of the hit. The large area Z-planes (up to 12m 2 ) are 1mm thick and contain 96 copper strips that detect the induced charge from avalanches created in the streamer tube wires. All the Z-planes needed for the upgrade have already been constructed, but only a third of the planes were installed last summer. After installing the 24 Z-planes last year, it was learned that 0.7% of the strips were dead when put inside the detector. This was mainly due to the delicate solder joint between the read-out cable and the strip, and since it is difficult to access or replace the Z-planes inside the detector, it is very important to perform various tests to make sure that the Z-planes will be efficient and effective in the long term. We measure the capacitance between the copper strips and the ground plane, and compare it to the theoretical value that we expect. Instead of measuring the capacitance channel by channel, which would be a very tedious job, we developed a more effective method of measuring the capacitance. Since all the Z-planes were built at SLAC, we also built a smaller 46 cm by 30 cm Z-plane with 12 strips just to see how they were constructed and to gain a better understanding about the solder joints

Radioactive nuclide adsorption

International Nuclear Information System (INIS)

Fukushima, Kimichika.

1982-01-01

Purpose: To improve the efficiency of a radioactive nuclide adsorption device by applying a nickel plating on a nickel plate to render the surface active. Constitution: A capturing device for radioactive nuclide such as manganese 54, cobalt 60, 58 and the like is disposed to the inside of a pipeway provided on the upper portion of fuel assemblies through which liquid sodium as the coolant for LMFBR type reactor is passed. The device comprises a cylindrical adsorption body and spacers. The adsorption body is made of nickel and applied with a nickel plating on the surface thereof. The surface of the adsorption body is unevened to result in disturbance in the coolant and thereby improve the adsorptive efficiency. (Kawakami, Y.)

Effects of hydrostatic strain on eigenstates of Möbius strips

DEFF Research Database (Denmark)

Lassen, Benny; Willatzen, Morten; Gravesen, Jens

2011-01-01

In this paper we theoretically investigate the allowed energies and associate wave-functions for Möbius strips with varying thicknesses. We show that the induced strain in fabricating these Möbius strips will have an pronounced impact on the energies and wave-functions for thick strips, while f...... for thin strips the impact of strain is negligible. We furthermore, show that a simpler strain free approximate theory base on differential geometry is in excellent agreement with detailed finite element calculations. © 2011 IEEE....

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.

Low-resistance strip sensors for beam-loss event protection

International Nuclear Information System (INIS)

Ullán, M.; Benítez, V.; Quirion, D.; Zabala, M.; Pellegrini, G.; Lozano, M.; Lacasta, C.; Soldevila, U.; García, C.; Fadeyev, V.; Wortman, J.; DeFilippis, J.; Shumko, M.; Grillo, A.A; Sadrozinski, H.F.-W.

2014-01-01

AC-coupled silicon strip sensors can be damaged in case of a beam loss due to the possibility of a large charge accumulation in the bulk, developing very high voltages across the coupling capacitors which can destroy them. Punch-through structures are currently used to avoid this problem helping to evacuate the accumulated charge as large voltages are developing. Nevertheless, previous experiments, performed with laser pulses, have shown that these structures can become ineffective in relatively long strips. The large value of the implant resistance can effectively isolate the “far” end of the strip from the punch-through structure leading to large voltages. We present here our developments to fabricate low-resistance strip sensors to avoid this problem. The deposition of a conducting material in contact with the implants drastically reduces the strip resistance, assuring the effectiveness of the punch-through structures. First devices have been fabricated with this new technology. Initial results with laser tests show the expected reduction in peak voltages on the low resistivity implants. Other aspects of the sensor performance, including the signal formation, are not affected by the new technology

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

Potentiometric stripping analysis of antimony based on carbon paste electrode modified with hexathia crown ether and rice husk

International Nuclear Information System (INIS)

Gadhari, Nayan S.; Sanghavi, Bankim J.; Srivastava, Ashwini K.

2011-01-01

Highlights: → Potentiometric stripping analysis (PSA) employed for the determination of antimony. → Hexathia-18C6 and rice husk modified carbon paste electrode developed for the analysis. → Lowest detection limit obtained for the determination of Sb(III) using PSA. → Analysis of Sb in pharmaceutical formulations, human hair, blood serum, urine and sea water. → Rice husk used as a modifier for the first time in electrochemistry. - Abstract: An electrochemical method based on potentiometric stripping analysis (PSA) employing a hexathia 18C6 (HT18C6) and rice husk (RH) modified carbon paste electrode (HT18C6-RH-CPE) has been proposed for the subnanomolar determination of antimony. The characterization of the electrode surface has been carried out by means of scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and chronocoulometry. By employing HT18C6-RH-CPE, a 12-fold enhancement in the PSA signal (dt/dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/dE (s V -1 ) was proportional to the Sb(III) concentration in the range of 1.42 x 10 -8 to 6.89 x 10 -11 M (r = 0.9944) with the detection limit (S/N = 3) of 2.11 x 10 -11 M. The practical analytical utilities of the modified electrode were demonstrated by the determination of antimony in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as simple preparation method, high sensitivity, very low detection limit and excellent reproducibility. Moreover, the results obtained for antimony analysis in commercial and real samples using HT18C6-RH-CPE and those obtained by inductively coupled plasma-atomic emission spectrometry (ICP-AES) are in agreement at the 95% confidence level.

Potentiometric stripping analysis of antimony based on carbon paste electrode modified with hexathia crown ether and rice husk

Energy Technology Data Exchange (ETDEWEB)

Gadhari, Nayan S.; Sanghavi, Bankim J. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India); Srivastava, Ashwini K., E-mail: aksrivastava@chem.mu.ac.in [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India)

2011-10-03

Highlights: {yields} Potentiometric stripping analysis (PSA) employed for the determination of antimony. {yields} Hexathia-18C6 and rice husk modified carbon paste electrode developed for the analysis. {yields} Lowest detection limit obtained for the determination of Sb(III) using PSA. {yields} Analysis of Sb in pharmaceutical formulations, human hair, blood serum, urine and sea water. {yields} Rice husk used as a modifier for the first time in electrochemistry. - Abstract: An electrochemical method based on potentiometric stripping analysis (PSA) employing a hexathia 18C6 (HT18C6) and rice husk (RH) modified carbon paste electrode (HT18C6-RH-CPE) has been proposed for the subnanomolar determination of antimony. The characterization of the electrode surface has been carried out by means of scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and chronocoulometry. By employing HT18C6-RH-CPE, a 12-fold enhancement in the PSA signal (dt/dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/dE (s V{sup -1}) was proportional to the Sb(III) concentration in the range of 1.42 x 10{sup -8} to 6.89 x 10{sup -11} M (r = 0.9944) with the detection limit (S/N = 3) of 2.11 x 10{sup -11} M. The practical analytical utilities of the modified electrode were demonstrated by the determination of antimony in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as simple preparation method, high sensitivity, very low detection limit and excellent reproducibility. Moreover, the results obtained for antimony analysis in commercial and real samples using HT18C6-RH-CPE and those obtained by inductively coupled plasma-atomic emission spectrometry (ICP-AES) are in agreement at the 95% confidence level.

Silicon strip detector qualification for the CMS experiment

Energy Technology Data Exchange (ETDEWEB)

Kaussen, Gordon

2008-10-06

To provide the best spatial resolution for the particle trajectory reconstruction and a very fast readout, the inner tracking system of CMS is build up of silicon detectors with a pixel tracker in the center surrounded by a strip tracker. The silicon strip tracker consists of so-called modules representing the smallest detection unit of the tracking device. These modules are mounted on higher-level structures called shells in the tracker inner barrel (TIB), rods in the tracker outer barrel (TOB), disks in the tracker inner disks (TID) and petals in the tracker end caps (TEC). The performance of the participating two shells of the TIB, four rods of the TOB and two petals of the TEC (representing about 1% of the final strip tracker) could be studied in different magnetic fields over a period of approximately two month using cosmic muon signals. The last test before inserting the tracker in the CMS experiment was the Tracker Slice Test performed in spring/summer 2007 at the Tracker Integration Facility (TIF) at CERN after installing all subdetectors in the tracker support tube. Approximately 25% of the strip tracker +z side was powered and read out using a cosmic ray trigger built up of scintillation counters. In total, about 5 million muon events were recorded under various operating conditions. These events together with results from commissioning runs were used to study the detector response like cluster charges, signal-to-noise ratios and single strip noise behaviour as well as to identify faulty channels which turned out to be in the order of a few per mille. The performance of the silicon strip tracker during these different construction stages is discussed in this thesis with a special emphasis on the tracker end caps. (orig.)

Silicon strip detector qualification for the CMS experiment

International Nuclear Information System (INIS)

Kaussen, Gordon

2008-01-01

To provide the best spatial resolution for the particle trajectory reconstruction and a very fast readout, the inner tracking system of CMS is build up of silicon detectors with a pixel tracker in the center surrounded by a strip tracker. The silicon strip tracker consists of so-called modules representing the smallest detection unit of the tracking device. These modules are mounted on higher-level structures called shells in the tracker inner barrel (TIB), rods in the tracker outer barrel (TOB), disks in the tracker inner disks (TID) and petals in the tracker end caps (TEC). The performance of the participating two shells of the TIB, four rods of the TOB and two petals of the TEC (representing about 1% of the final strip tracker) could be studied in different magnetic fields over a period of approximately two month using cosmic muon signals. The last test before inserting the tracker in the CMS experiment was the Tracker Slice Test performed in spring/summer 2007 at the Tracker Integration Facility (TIF) at CERN after installing all subdetectors in the tracker support tube. Approximately 25% of the strip tracker +z side was powered and read out using a cosmic ray trigger built up of scintillation counters. In total, about 5 million muon events were recorded under various operating conditions. These events together with results from commissioning runs were used to study the detector response like cluster charges, signal-to-noise ratios and single strip noise behaviour as well as to identify faulty channels which turned out to be in the order of a few per mille. The performance of the silicon strip tracker during these different construction stages is discussed in this thesis with a special emphasis on the tracker end caps. (orig.)

Metal films with imprinted nanostructures by template stripping

DEFF Research Database (Denmark)

Eriksen, René Lynge; Pors, Anders; Dreier, Jes

We present a novel template stripping procedure for fabricating metal films with imprinted nanostructures. The basic idea is to deposit a gold film onto a nano-structured substrate and subsequently strip the film from the substrate surface thereby revealing imprinted nanostructures in the film...... result is a thin gold film with imprinted nano-cavities....

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

International Nuclear Information System (INIS)

Guerreiro, Gabriela V.; Zaitouna, Anita J.; Lai, Rebecca Y.

2014-01-01

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 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 2+ rather rapidly; majority of the signal change occurred in 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

Liquidity, Reconstitution, and the Value of U.S. Treasury Strips.

OpenAIRE

Daves, Phillip R; Ehrhardt, Michael C

1993-01-01

An apparent pricing anomaly exists in the market for U.S. Treasury strips: zero-coupon strips created from principal payments typically trade at significantly higher prices than otherwi se identical zero-coupon strips created from coupon payments. In additi on to documenting this phenomenon, this study demonstrates that differences in liquidity and differences in reconstitution characteristics explain much of this price variation. Copyright 1993 by American Finance Association.

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

Precipitation stripping of neodymium from carboxylate extractant with aqueous oxalic acid solutions

International Nuclear Information System (INIS)

Konishi, Yasuhiro; Asai, Satoru; Murai, Tetuya

1993-01-01

This paper describes a precipitation stripping method in which neodymium ions are stripped from carboxylate extractant in organic solvent and simultaneously precipitated with aqueous oxalic acid solution. For the single-stage process, a quantitative criterion for precipitating oxalate powders was derived theoretically, and stripping experiments were done under the precipitation conditions. The resultant precipitates were neodymium oxalate, which is completely free from contamination by the carboxylate extractant and the organic solvent. The overall rate of stripping was controlled by the transfer of neodymium carboxylate in the organic solution, indicating that the presence of oxalic acid in the aqueous phase has no effect on the stripping rate. These findings demonstrate the feasibility of combining the conventional stripping and precipitation stages in a solvent extraction process for separation and purification of rare earths

Estimation of key physical properties for LaCl{sub 3} in molten eutectic LiCl–KCl by fitting cyclic voltammetry data to a BET-based electrode reaction kinetics model

Energy Technology Data Exchange (ETDEWEB)

Samin, Adib [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, OH 43210 (United States); Wang, Zhonghang [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, Metallurgical Engineering Department, University of Utah, Salt Lake City, UT 84112 (United States); Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Lahti, Erik [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, OH 43210 (United States); Simpson, Michael [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, Metallurgical Engineering Department, University of Utah, Salt Lake City, UT 84112 (United States); Zhang, Jinsuo, E-mail: zhang.3558@osu.edu [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, OH 43210 (United States)

2016-07-15

Understanding the electrochemical properties of rare earth elements is important for developing efficient techniques for separating rare earth elements from actinides recovered during the electrodeposition process. In this study the cyclic voltammetry for lanthanum in molten LiClKCl eutectic was recorded at 773 K for different scan rates and different bulk concentrations. A model accounting for mass transport, kinetics and adsorption was applied to analyze the experimental data via performing a nonlinear least squares fit. The results of the simulation are compared against the results of a conventional analysis of the cyclic voltammograms and against the existing literature. At the scan rates used, the reduction/oxidation process is quasi-reversible. The values of diffusivities derived from simulation were larger than the ones derived commonly using equations for diffusion-limited processes. However, those equations were derived based on an assumption of reversibility. This simulation-based approach may provide a more accurate option for analyzing systems that do not exhibit reversibility.

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.

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.

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.

Evaluation of a portable urinary pH meter and reagent strips.

Science.gov (United States)

De Coninck, Vincent; Keller, Etienne Xavier; Rodríguez-Monsalve, María; Haymann, Jean-Philippe; Doizi, Steeve; Traxer, Olivier

2018-04-27

To evaluate a portable electronic pH meter and to put its accuracy in perspective with reagent strips read by a layperson, a healthcare professional and an electronic reading device. Based on a pre-analysis on 20 patients, a sample size of 77 urine aliquots from healthy volunteers was necessary to obtain sufficient study power. Measurements of urinary pH were obtained by use of reagent strips, a portable pH meter and a laboratory pH meter (gold standard). Reagents strips were read by a professional experienced in interpreting strips, a layperson, and an electronic strip reader. The mean matched pair difference between measurement methods was analyzed by the paired t-test. The degree of correlation and agreement were evaluated by the Pearson's correlation coefficient and Bland-Altman plots, respectively. The mean matched pair difference between the gold standard and all other pH measurement methods was the smallest with the portable electronic pH meter (bias 0.01, 95% CI -0.07 to 0.08; p=0.89), followed by strips read by a professional (bias -0.09, 95% CI -0.21 to 0.02; p=0.10), layperson (bias -0.17, 95% CI -0.31 to -0.04; p=0.015) and electronic strip reader (bias -0.29, 95% CI -0.41 to -0.16; pmeter achieved the highest Pearson's correlation coefficient and narrowest 95% limits of agreement, followed by strip interpretation by a professional, the electronic strip reader and the layperson. In order to quantify the ability of pH measurement methods to correctly classify values within a predefined urinary pH target range, we performed classification tests for several stones. The portable electronic pH meter outperformed all other measurement methods for negative predictive values. Findings of the current study support that the portable electronic pH meter is a reliable pH measuring device. It seems to be more accurate compared to reagent strips readings.

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

A new strips tracker for the upgraded ATLAS ITk detector

Science.gov (United States)

David, C.

2018-01-01

The ATLAS detector has been designed and developed to function in the environment of the present Large Hadron Collider (LHC). At the next-generation tracking detector proposed for the High Luminosity LHC (HL-LHC), the so-called ATLAS Phase-II Upgrade, the fluences and radiation levels will be higher by as much as a factor of ten. The new sub-detectors must thus be faster, of larger area, more segmented and more radiation hard while the amount of inactive material should be minimized and the power supply to the front-end systems should be increased. For those reasons, the current inner tracker of the ATLAS detector will be fully replaced by an all-silicon tracking system that consists of a pixel detector at small radius close to the beam line and a large area strip tracker surrounding it. This document gives an overview of the design of the strip inner tracker (Strip ITk) and summarises the intensive R&D activities performed over the last years by the numerous institutes within the Strips ITk collaboration. These studies are accompanied with a strong prototyping effort to contribute to the optimisation of the Strip ITk's structure and components. This effort culminated recently in the release of the ATLAS Strips ITk Technical Design Report (TDR).

Comparison of blood glucose test strips in the detection of neonatal hypoglycaemia

OpenAIRE

Wilkins, B H; Kalra, D

1982-01-01

Blood glucose levels were estimated in 101 neonatal blood samples using three glucose test strip methods and the results compared with those from a laboratory. BM-test-glycemie 20-800 test strips and Reflotest-hypoglycemie test strips gave a rapid and reliable estimate of blood glucose level in the range 0-8 mmol/l (0-140 mg/100 ml). Dextrostix test strips tended to overestimate all blood glucose levels.

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

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

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.

The depletion properties of silicon microstrip detectors with variable strip pitch

International Nuclear Information System (INIS)

Krizmanic, J.F.

1994-01-01

We have investigated the depletion properties of trapezoidal shaped silicon microstrip detectors which have variable strip pitch. Four types of detectors were examined: three detectors have constant strip width and a fourth has a varying strip width. The detectors are single sided with readout performed via p + strips. The depletion properties of the devices were measured using two different methods. The first used capacitance versus voltage measurements, while the second used a 1060 nm wavelength laser coupled to a single mode fiber with a mode field diameter less than 10 μm. The small laser spot size allowed for the depletion depth to be measured in a localized area of the detector. The laser induced charge on an electrode was measured as a function of reverse bias voltage using a sensitive charge preamplifier. The depletion voltages of the detectors demonstrate a strong dependence upon the ratio of strip width to strip pitch. Moreover, these measurements show that a large value of this ratio yields a lower depletion voltage and vice versa. (orig.)

A GEM readout with radial zigzag strips and linear charge-sharing response

Science.gov (United States)

Zhang, Aiwu; Hohlmann, Marcus; Azmoun, Babak; Purschke, Martin L.; Woody, Craig

2018-04-01

We study the position sensitivity of radial zigzag strips intended to read out large GEM detectors for tracking at future experiments. Zigzag strips can cover a readout area with fewer strips than regular straight strips while maintaining good spatial resolution. Consequently, they can reduce the number of required electronic channels and related cost for large-area GEM detector systems. A non-linear relation between incident particle position and hit position measured from charge sharing among zigzag strips was observed in a previous study. We significantly reduce this non-linearity by improving the interleaving of adjacent physical zigzag strips. Zigzag readout structures are implemented on PCBs and on a flexible foil and are tested using a 10 cm × 10 cm triple-GEM detector scanned with a strongly collimated X-ray gun on a 2D motorized stage. Angular resolutions of 60-84 μrad are achieved with a 1.37 mrad angular strip pitch at a radius of 784 mm. On a linear scale this corresponds to resolutions below 100 μm.

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.

Sediment removal by prairie filter strips in row-cropped ephemeral watersheds

Science.gov (United States)

Matthew J. Helmers; Xiaobo Zhou; Heidi Asbjornsen; Randy Kolka; Mark D. Tomer; Richard M. Cruse

2012-01-01

Twelve small watersheds in central Iowa were used to evaluate the eff ectiveness of prairie filter strips (PFS) in trapping sediment from agricultural runoff. Four treatments with PFS of different size and location (100% rowcrop, 10% PFS of total watershed area at footslope, 10% PFS at footslope and in contour strips, 20% PFS at footslope and in contour strips)...

Efficiency measurements for 3D silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Parzefall, Ulrich, E-mail: ulrich.parzefall@physik.uni-freiburg.d [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); Dalla Betta, Gian-Franco [INFN Trento and Universita di Trento, via Sommarive 14, 38050 Povo di Trento (Italy); Boscardin, Maurizio [FBK-irst, Center for Materials and Microsystems, via Sommarive 18, 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; Koehler, Michael; Kuehn, Susanne; Pahn, Gregor [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); Parkes, Chris; Pennicard, David [University of Glasgow, Department of Physics and Astronomy, Glasgow G12 8QQ (United Kingdom); Ronchin, Sabina [FBK-irst, Center for Materials and Microsystems, via Sommarive 18, 38050 Povo di Trento (Italy); Zoboli, Andrea [INFN Trento 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)

2010-11-01

Silicon strip detectors are widely used as part of the inner tracking layers in particle physics experiments. For applications at the luminosity upgrade of the Large Hadron Collider (LHC), the sLHC, silicon detectors with extreme radiation hardness are required. The 3D detector design, where electrodes are processed from underneath the strips into the silicon bulk material, provides a way to enhance the radiation tolerance of standard planar silicon strip detectors. Detectors with several innovative 3D designs that constitute a simpler and more cost-effective processing than the 3D design initially proposed were connected to read-out electronics from LHC experiments and subsequently tested. Results on the amount of charge collected, the noise and the uniformity of charge collection are given.

First results from a silicon-strip detector with VLSI readout

International Nuclear Information System (INIS)

Anzivino, G.; Horisberger, R.; Hubbeling, L.; Hyams, B.; Parker, S.; Breakstone, A.; Litke, A.M.; Walker, J.T.; Bingefors, N.

1986-01-01

A 256-strip silicon detector with 25 μm strip pitch, connected to two 128-channel NMOS VLSI chips (Microplex), has been tested using straight-through tracks from a ruthenium beta source. The readout channels have a pitch of 47.5 μm. A single multiplexed output provides voltages proportional to the integrated charge from each strip. The most probable signal height from the beta traversals is approximately 14 times the rms noise in any single channel. (orig.)

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.

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

Adsorption of human insulin on single-crystal gold surfaces investigated by in situ scanning tunnelling microscopy and electrochemistry

DEFF Research Database (Denmark)

Welinder, Anna Christina; Zhang, Jingdong; Steensgaard, D.B.

2010-01-01

sweep, LSV, cyclic, CV, and square wave (SQWV) voltammetry. Multifarious electrochemical patterns were observed. Most attention was given to reductive desorption caused by insulin binding to the Au-surfaces via up to three disulfide groups per insulin monomer, presumably converted to single Au-S links....... SQWV suggested the Au-S bond strength order Au(111) > Au(110) > Au(100) based on the reductive desorption potentials. The voltammetric diversity was paralleled by different in situ STM insulin adsorption modes on the three surfaces. Single-molecule resolution was achieved in all cases. The coverage...... followed the order Au(110) > Au(100) > Au(111) and differs from the reductive desorption order that records the Au-S bonding element. Evenly distributed single molecules were scattered over large Au(111)-terraces, with intriguing molecular arrays disclosed near the terrace edges. In comparison, high...

Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

CERN Document Server

Losel, Philipp Jonathan; The ATLAS collaboration

2015-01-01

Resisitve strip Micromegas detectors behave discharge tolerant. They have been tested extensively as smaller detectors of about 10 x 10 cm$^2$ in size and they work reliably at high rates of 100\\,kHz/cm$^2$ and above. Tracking resolutions well below 100\\,$\\mu$m have been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3\\,m$^2$ in size. To investigate possible differences between small and large detectors, a 1\\,m$^2$ detector with 2048 resistive strips at a pitch of 450 $\\mu$m was studied in the LMU Cosmic Ray Facility (CRF) using two 4 $\\times$ 2.2 m$^2$ large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. Segmentation of the resistive strip anode plane in 57.6\\,mm x 95\\,mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by 11 95\\,mm broad trigger scintillators placed along the readout strips.\\\\ This allows for mapping of homogenity in pulse height and efficiency, deter...

Humor in elementary science: Development and evaluation of comic strips about sound

Directory of Open Access Journals (Sweden)

Ertuğrul Özdemir

2017-06-01

Full Text Available Comic strips on newspapers, magazines and Internet are one of the most accessible materials that may be used in science classroom as instructional tool. However, it is sometimes difficult to find and adapt appropriate comic strips useful for instructional purposes, because most of them are irrelevant. The purpose of this study is to develop and evaluate instructional comic strips aiming to contribute learning about sound related concepts. In this study, a series of instructional comic strips were created and implemented to a group of seventh grade students. Students’ responses to a number of open-ended questions were evaluated through qualitative content analysis. According to results, most of the students believed that comic strips help learning through simplifying science concepts and making retention of them easier. In addition, comic strips seemed to contribute students’ enjoyment toward science and perception of success in science.

Development of pore interconnectivity/morphology in porous silica films investigated by cyclic voltammetry and slow positron annihilation spectroscopy

International Nuclear Information System (INIS)

Tang, Xiuqin; Xiong, Bangyun; Li, Qichao; Mao, Wenfeng; Xiao, Wei; Fang, Pengfei; He, Chunqing

2015-01-01

Highlights: •Porous silica films were studied by cyclic voltammetry and positron annihilation. •Highly interconnected pores were formed in the film fabricated with more CTAB. •Aligned nanochannels were observed in the porous flim prepared with 25 wt.% CTAB. •I − and Ps diffusion in the films was governed by pore interconnectivity/morphology. •Cyclic voltammetry is feasible to explore pore interconnectivity/morphology. -- Abstract: Cyclic voltammetry and positronium (Ps) 3γ-annihilation spectroscopy were applied to investigate pore interconnectivity/morphology of porous silica films fabricated with various loading of cetyltrimethyl ammonium bromide (CTAB). With increasing the ratio of CTAB up to 15 wt.%, the total charge Q, resulted from I − diffusion across the silica films, increased remarkably, indicative of formation of highly interconnected pores in the films prepared with more porogen. However, it decreased dramatically with further loading CTAB of 25 wt.%. Interestingly, 3γ-annihilation fraction I 3γ due to a triplet-state Ps (ortho-positronium, o-Ps) emission from the silica films showed a similar behavior as a function of CTAB loading. The abnormal decrement in Q and I 3γ in the film fabricated with 25 wt.% CTAB was well explained by formation of long nanochannels aligning parallel to the film surface. The results indicated that the total charge Q and Ps 3γ-annihilation fraction were closely associated with I − and Ps diffusion governed by the pore interconnectivity/morphology of the silica films, which made cyclic voltammetry possible to be a feasible tool to characterize pore interconnectivity/morphology of porous thin films

Performance of a new test strip for freestyle blood glucose monitoring systems.

Science.gov (United States)

Lock, John Paul; Brazg, Ronald; Bernstein, Robert M; Taylor, Elizabeth; Patel, Mona; Ward, Jeanne; Alva, Shridhara; Chen, Ting; Welsh, Zoë; Amor, Walter; Bhogal, Claire; Ng, Ronald

2011-01-01

a new strip, designed to enhance the ease of use and minimize interference of non-glucose sugars, has been developed to replace the current FreeStyle (Abbott Diabetes Care, Alameda, CA) blood glucose test strip. We evaluated the performance of this new strip. laboratory evaluation included precision, linearity, dynamic range, effects of operating temperature, humidity, altitude, hematocrit, interferents, and blood reapplication. System accuracy, lay user performance, and ease of use for finger capillary blood testing and accuracy for venous blood testing were evaluated at clinics. Lay users also compared the speed and ease of use between the new strip and the current FreeStyle strip. for glucose concentrations blood glucose results obtained by lay users fell within ± 5, 10, and 15 mg/dL, respectively, of the reference. For glucose concentrations ≥75 mg/dL, 68%, 95%, 99%, and 99% of the lay user results fell within  ±  5%, 10%, 15%, and 20%, respectively, of the reference. Comparable accuracy was obtained in the venous blood study. Lay users found the new test strip easy to use and faster and easier to use than the current FreeStyle strip. The new strip maintained accuracy under various challenging conditions, including high concentrations of various interferents, sample reapplication up to 60 s, and extremes in hematocrit, altitude, and operating temperature and humidity. our results demonstrated excellent accuracy of the new FreeStyle test strip and validated the improvements in minimizing interference and enhancing ease of use.

A design aid for sizing filter strips using buffer area ratio

Science.gov (United States)

M.G. Dosskey; M.J. Helmers; D.E. Eisenhauer

2011-01-01

Nonuniform field runoff can reduce the effectiveness of filter strips that are a uniform size along a field margin. Effectiveness can be improved by placing more filter strip where the runoff load is greater and less where the load is smaller. A modeling analysis was conducted of the relationship between pollutant trapping efficiency and the ratio of filter strip area...

Adsorption of uranium on halloysite

International Nuclear Information System (INIS)

Kilislioglu, A.; Bilgin, B.

2002-01-01

Adsorption of uranium (U(VI)) from aqueous solutions on halloysite type clay was studied as a function of amount of adsorbent, initial concentration and pH. The values of adsorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The mean energy of adsorption was calculated as 5.91 kJ/mol from D-R adsorption isotherm. Lagergren and Bangham equation has been used for dynamic modelling of process and the rate constants of adsorption of uranium on halloysite type clay were calculated at 293, 313 and 333 K. In order to explain the mechanism of adsorption reaction, the rate constants were calculated at high and low uranium concentrations. Adsorption reaction was studied at 293, 303, 313, 323 and 333 K for halloysite type clay and also thermodynamic constants have been calculated. The results show that the adsorption reaction was endothermic and more spontaneous at high temperature. (orig.)

Adsorption of uranium on halloysite

Energy Technology Data Exchange (ETDEWEB)

Kilislioglu, A.; Bilgin, B. [Istanbul Univ. (Turkey). Faculty of Engineering

2002-07-01

Adsorption of uranium (U(VI)) from aqueous solutions on halloysite type clay was studied as a function of amount of adsorbent, initial concentration and pH. The values of adsorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The mean energy of adsorption was calculated as 5.91 kJ/mol from D-R adsorption isotherm. Lagergren and Bangham equation has been used for dynamic modelling of process and the rate constants of adsorption of uranium on halloysite type clay were calculated at 293, 313 and 333 K. In order to explain the mechanism of adsorption reaction, the rate constants were calculated at high and low uranium concentrations. Adsorption reaction was studied at 293, 303, 313, 323 and 333 K for halloysite type clay and also thermodynamic constants have been calculated. The results show that the adsorption reaction was endothermic and more spontaneous at high temperature. (orig.)

Cyclic voltammetry and reduction mechanistic studies of styrylpyrylium perchlorates

Directory of Open Access Journals (Sweden)

Y. L. Bonzi-Coulibaly

2013-04-01

Full Text Available The reduction and oxidation potentials of methylated 4-styrylpyrylium and 6-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 electron-donating methyl group on pyrylium ring leads to a shift of the styrylpyrylium perchlorates reduction potential towards cathodic values. Kinetic studies on platinum electrodes based on the variation of the peak potential at different scan rates and upon substrate concentrations confirm, in another way, the mechanism of electron transfer.DOI: http://dx.doi.org/10.4314/bcse.v27i1.12

Science comic-strips on display at Microcosm

CERN Document Server

Alix Marcastel

2011-01-01

To mark the publication of his new comic-strip "Les Vies de Marie Curie", the Genevan artist Fiami will be placing some of his previous creations on the theme "women and science" on display at CERN. The new comic-strip pays tribute to the illustrious Nobel prize-winner by taking a light-hearted look at the history of chemistry and how the role of women scientists in society has evolved through the ages.   It's no easy task,  presenting the history of science to the general public in a light-hearted way. As part of the various events organised in the Fête de la Science and the Europeans Researchers Night, CERN will be hosting an exhibition entirely devoted to the comic-strips created by Fiami. The artist describes his comics as "a relaxed way of looking at serious and apparently highly complex subjects."  Fiami's very latest creation, Les Vies de Marie Curie, published in June 2011, celebrates th...

The Argonne silicon strip-detector array

Energy Technology Data Exchange (ETDEWEB)

Wuosmaa, A H; Back, B B; Betts, R R; Freer, M; Gehring, J; Glagola, B G; Happ, Th; Henderson, D J; Wilt, P [Argonne National Lab., IL (United States); Bearden, I G [Purdue Univ., Lafayette, IN (United States). Dept. of Physics

1992-08-01

Many nuclear physics experiments require the ability to analyze events in which large numbers of charged particles are detected and identified simultaneously, with good resolution and high efficiency, either alone, or in coincidence with gamma rays. The authors have constructed a compact large-area detector array to measure these processes efficiently and with excellent energy resolution. The array consists of four double-sided silicon strip detectors, each 5x5 cm{sup 2} in area, with front and back sides divided into 16 strips. To exploit the capability of the device fully, a system to read each strip-detector segment has been designed and constructed, based around a custom-built multi-channel preamplifier. The remainder of the system consists of high-density CAMAC modules, including multi-channel discriminators, charge-sensing analog-to-digital converters, and time-to-digital converters. The array`s performance has been evaluated using alpha-particle sources, and in a number of experiments conducted at Argonne and elsewhere. Energy resolutions of {Delta}E {approx} 20-30 keV have been observed for 5 to 8 MeV alpha particles, as well as time resolutions {Delta}T {<=} 500 ps. 4 figs.

Determination of residual stresses in roll compacted titanium strips

CSIR Research Space (South Africa)

Mothosi, KL

2017-01-01

Full Text Available residual stresses using x-ray diffraction (XRD) surface probing technique. Preliminary results were obtained for the surface residual stress at the center of the titanium strips for the 100 and 325 mesh strips rolled at 0.1 roll gap for 20 and 50 mm set...

Method of stripping solid particles

International Nuclear Information System (INIS)

1980-01-01

A method of stripping loaded solid particles is specified in which uniform batches of the loaded particles are passed successively upwardly through an elution column in the form of discrete plugs, the particles of which do not intermingle substantially with the particles of the vertically adjacent plug(s), and are contacted therein with eluant liquid flowed downwardly, strong eluate being withdrawn from the lower region of the column, the loaded particles being supplied as a slurry in a carrier liquid, and successive batches of loaded particles being isolated as measured batches and being separated from their carrier liquid before being contacted with strong eluate and slurried with the strong eluate into the lower region of the column. An example describes the stripping of ion exchange resin particles loaded with complex uranium ions. (author)

Process for recovering uranium using an alkyl pyrophosphoric acid and alkaline stripping solution

International Nuclear Information System (INIS)

Worthington, R.E.; Magdics, A.

1987-01-01

A process is described for stripping uranium for a pregnant organic extractant comprising an alkyl pyrophosphoric acid dissolved in a substantially water-immiscible organic diluent. The organic extractant contains tetravalent uranium and an alcohol or phenol modifier in a quantity sufficient to retain substantially all the unhydrolyzed alkyl pyrophosphoric acid in solution in the diluent during stripping. The process comprises adding an oxidizing agent to the organic extractant and thereby oxidizing the tetravalent uranium to the +6 state in the organic extractant, and contacting the organic extractant containing the uranium in the +6 state with a stripping solution comprising an aqueous solution of an alkali metal or ammonium carbonate or hydroxide thereby stripping uranium from the organic extractant into the stripping solution. The resulting barren organic extractant containing substantially all of the unhydrolyzed alkyl pyrophosphoric acid dissolved in the diluent is separated from the stripping solution containing the stripped uranium, the barren extractant being suitable for recycle

Single electron attachment and stripping cross sections for relativistic heavy ions

International Nuclear Information System (INIS)

Crawford, H.J.

1979-06-01

The results of a Bevalac experiment to measure the single electron attachment and stripping cross sections for relativistic (0.5 1 , and fully stripped, N 0 , ion beams emerging from the targets. Separate counters measured the number of ions in each charge state. The ratios N 1 /N 0 for different target thicknesses were fit to a simple growth curve to yield electron attachment and stripping cross sections. The data are compared to relativistic extrapolations of available theories. Clear evidence for two separate attachment processes, radiative and non-radiative, is found. Data are compared to a recently improved formulation for the stripping cross sections

Observational study on the pavement performance effects of shoulder rumble strip on shoulders

Directory of Open Access Journals (Sweden)

Sean Coffey

2016-07-01

Full Text Available Rumble strip implementation has shown a constant increase with its safety benefits. Rumble strips are milled into the roadway shoulder to produce noise and vibrations when driven on. With the milling process, the pavement performance is expected to be negatively impacted by the decreased depth, though not mathematically quantified. Using methods defined by the Long-Term Pavement Performance Program, the severity of the shoulder site’s distresses, with and without shoulder rumble strips, will be quantified. The quantification would permit the design to compensate for the impact. This design compensation allows the implementation of hard shoulder running, the use of shoulder as a travel lane during congestion, and retains the shoulder rumble strip safety instead of removing, as suggested by some proposed projects. While hard shoulder running would not impact specific time periods, the safety benefit of rumble strips could be needed at any time. This study aims to quantify the rumble strip impact to enable the full shoulder strength for hard shoulder running while retaining the safety benefits of rumble strips. Keywords: Rumble strips, Shoulder, Cracking, Pavement performance, Hard shoulder running

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.

Influence for high intensity irradiation on characteristics of silicon strip-detectors

International Nuclear Information System (INIS)

Anokhin, I.E.; Pugatch, V.M.; Zinets, O.S.

1995-01-01

Full text: Silicon strip detectors (SSD) are widely used for the coordinate determination of short-range as well as minimum ionizing particles with high spatial resolution. Submicron position sensitivity of strip-detectors for short-range particles has been studied by means of two dimensional analyses of charges collected by neighboring strips as well as by measurement of charge collection times [1]. Silicon strip detectors was also used for testing high energy electron beam [2]. Under large fluences the radiation defects are stored and such characteristics of strip-detectors as an accuracy of the coordinate determination and the registration efficiency are significantly changed. Radiation defects lead to a decrease of the lifetime and mobility of charge carriers and therefore to changes of conditions for the charge collection in detectors. The inhomogeneity in spatial distribution if defects and electrical field plays an important role in the charge collection. In this report the role of the diffusion and drift in the charge collection in silicon strip-detectors under irradiation up to 10 Mrad has been studied. The electric field distribution and its dependence on the radiation dose in the detector have been calculated. It is shown that for particles incident between adjacent strips the coordinate determination precision depends strongly on the detector geometry and the electric field distribution, particularly in the vicinity of strips. Measuring simultaneously the collected charges and collection times on adjacent strips one can essentially improve reliability of the coordinate determination for short-range particles. Usually SSD are fabricated on n-type wafers. It is well known that under high intensity irradiation n-Si material converts into p-Si as far as p-type silicon is more radiative hard than n-type silicon [3] it is reasonable to fabricate SSD using high resistivity p-Si. Characteristics of SSD in basis n-and P-Si have been compared and higher

Comparisons of boll weevil (Coleoptera: Curculionidae) pheromone traps with and without kill strips.

Science.gov (United States)

Suh, C P C; Armstrong, J S; Spurgeon, D W; Duke, S

2009-02-01

Boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), eradication programs typically equip pheromone traps with an insecticide-impregnated kill strip. These strips are intended to kill captured insects, thereby simplifying trap servicing and reducing the loss of weevils from predation and escape. However, the effectiveness of kill strips has not been extensively evaluated. We examined the influences of kill strips on weevil captures, trap servicing, and the incidences of weevil predation and trap obstruction (e.g., by spider webs). Evaluations were conducted weekly during three different production periods (pre- to early-, late-, and postseason) of cotton, Gossypium hirsutum L., to represent different environmental conditions and weevil population levels. Within each period, mean weekly captures of weevils in traps with and without kill strips were statistically similar. On average, traps with kill strips took 9 s longer to service than traps without kill strips, but statistical differences were only detected during the late-season period. Overall, the mean weekly proportion of traps with evidence of weevil predation or trap obstruction was significantly lower for traps with kill strips (0.25) than for traps without kill strips (0.37). However, this reduction in the frequency of weevil predation or trap obstruction was too small to produce a corresponding increase in the numbers of weevils captured. In light of these findings, the use of kill strips is likely unnecessary in eradication programs, but may be a consideration in situations when the numbers of deployed traps are reduced and chronic problems with weevil predation or trap obstruction exist.

Cyclic voltammetry deposition of copper nanostructure on MWCNTs modified pencil graphite electrode: An ultra-sensitive hydrazine sensor

Energy Technology Data Exchange (ETDEWEB)

Heydari, Hamid [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, Mohammad B., E-mail: mbgholivand@razi.ac.ir [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Abdolmaleki, Abbas [Department of Chemistry, Malek Ashtar University of Technology, Tehran (Iran, Islamic Republic of)

2016-09-01

In this study, Copper (Cu) nanostructures (CuNS) were electrochemically deposited on a film of multiwall carbon nanotubes (MWCNTs) modified pencil graphite electrode (MWCNTs/PGE) by cyclic voltammetry method to fabricate a CuNS–MWCNTs composite sensor (CuNS–MWCNT/PGE) for hydrazine detection. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) were used for the characterization of CuNS on the MWCNTs matrix. The composite of CuNS-MWCNTs was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The preliminary studies showed that the proposed sensor have a synergistic electrocatalytic activity for the oxidation of hydrazine in phosphate buffer. The catalytic currents of square wave voltammetry had a linear correlation with the hydrazine concentration in the range of 0.1 to 800 μM with a low detection limit of 70 nM. Moreover, the amperometric oxidation current exhibited a linear correlation with hydrazine concentration in the concentration range of 50–800 μM with the detection limit of 4.3 μM. The proposed electrode was used for the determination of hydrazine in real samples and the results were promising. Empirical results also indicated that the sensor had good reproducibility, long-term stability, and the response of the sensor to hydrazine was free from interferences. Moreover, the proposed sensor benefits from simple preparation, low cost, outstanding sensitivity, selectivity, and reproducibility for hydrazine determination. - Highlights: • The Copper nanostructures (CuNS) were prepared by cyclic voltammetry deposition. • The CuNS-MWCNT/PGE sensor shows high activity toward hydrazine (N{sub 2}H{sub 4}). • The proposed sensor exhibits a wide linear range (0.1 to 800 μM), low detection limit (70 nM), high sensitivity and stability for hydrazine.

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test.

Science.gov (United States)

Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

2013-10-01

Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. Copyright © 2013 Elsevier Ltd. All rights reserved.

Voltammetric Study of Arsenic (III and Arsenic (V in Ground Water of Hajigonj and Kalkini in Bangladesh

Directory of Open Access Journals (Sweden)

Mohammad Arifur Rahman

2008-06-01

Full Text Available The speciation of arsenic in groundwater samples using Square Wave Anodic Stripping Voltammetry (SWASV, Differential Pulse Anodic Stripping Voltammetry (DPASV and Normal Pulse Anodic Stripping Voltammetry (NPASV are described. Good resolution of the species, arsenic (III and arsenic (V is achieved using SWASV. The reliability of the methods was checked by analyzing the total arsenic content of the samples by Hydride Generation Atomic Absorptioion Spectrophotometer and by analyzing prepared controlled laboratory standard solution. Since this technique is comparatively cheaper than other available techniques it could be a better analytical technique for arsenic speciation from water. In this study, the assessment of inorganic arsenic species in ground water of Kalkini (Madaripur and Hajigonj (Chandpur is reported. It shows that arsenic content in water in different locations is irregular. Most of the locations contain higher level of As(III than As(V. The highest concentration of arsenic is found in Anayetnagor (554.46 ± 0.07 mg/L of Kalkini and Raichar (562 ± 0.50 mg/L of Hajigonj. However, the level of total arsenic and As(III of most of the villages of the study areas are more than the WHO guideline value (50mg/L. Therefore a proper monitoring process should be evolved along with the development of methods to keep the water free from arsenic.

Adsorption facility and adsorption vessel for radioactive carbon dioxide

International Nuclear Information System (INIS)

Harashina, Heihachi; Miwa, Keiichi; Kobayashi, Takeo.

1992-01-01

If 14 CO 2 gas-containing gases to be adsorbed are pressurized and sent to a packaging adsorption means, CO 2 ingredient in the gases to be adsorbed is adsorbed or absorbed, and remaining gases are passed through and sent out to downstream. CO 2 adsorption or absorption of the packaging adsorption means is judged by monitoring the state of the remaining gases, and if it is normal, remaining gases are sent further to downstream and processed. If abnormality is found, a gas feedback system is operated, and CO 2 removing gas is sent again to the packaging adsorption means, in which CO 2 gases are adsorbed or absorbed again repeatingly. With such procedures, in a case where C 14 nuclides having a long half decay time are supplied in the form of 14 CO 2 gas, they are efficiently adsorbed or absorbed in the packaging system to improve removing and storing property of 14 C nuclides. (T.M.)

Numerical analysis of edge effects in side illuminated strip detectors for digital radiology

CERN Document Server

Krizaj, D

2000-01-01

The influence of edge defects on side illuminated X-ray strip detectors for digital radiology is investigated by numerical device modeling. By assuming positive fixed oxide charges on side and top surfaces simulations have shown strong curvature of the equipotential lines in the edge region. A fraction of the edge generated current surpasses the edge guard-ring junction and is collected by the readout strips. As a consequence, strips cannot be placed close to the edge of the structure and collection efficiency is reduced. An n-on-n instead of a p-on-n strip detector is proposed enabling collection of edge generated carriers by a very narrow guard-ring junction and placement of the readout strip close to the edge without increase of the strip leakage current.

Generalized thick strip modelling for vortex-induced vibration of long flexible cylinders

International Nuclear Information System (INIS)

Bao, Y.; Palacios, R.; Graham, M.; Sherwin, S.

2016-01-01

We propose a generalized strip modelling method that is computationally efficient for the VIV prediction of long flexible cylinders in three-dimensional incompressible flow. In order to overcome the shortcomings of conventional strip-theory-based 2D models, the fluid domain is divided into “thick” strips, which are sufficiently thick to locally resolve the small scale turbulence effects and three dimensionality of the flow around the cylinder. An attractive feature of the model is that we independently construct a three-dimensional scale resolving model for individual strips, which have local spanwise scale along the cylinder's axial direction and are only coupled through the structural model of the cylinder. Therefore, this approach is able to cover the full spectrum for fully resolved 3D modelling to 2D strip theory. The connection between these strips is achieved through the calculation of a tensioned beam equation, which is used to represent the dynamics of the flexible body. In the limit, however, a single “thick” strip would fill the full 3D domain. A parallel Fourier spectral/hp element method is employed to solve the 3D flow dynamics in the strip-domain, and then the VIV response prediction is achieved through the strip–structure interactions. Numerical tests on both laminar and turbulent flows as well as the comparison against the fully resolved DNS are presented to demonstrate the applicability of this approach.

Generalized thick strip modelling for vortex-induced vibration of long flexible cylinders

Energy Technology Data Exchange (ETDEWEB)

Bao, Y., E-mail: ybao@sjtu.edu.cn [Department of Civil Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiaotong University, No. 800 Dongchuan Road, Shanghai (China); Department of Aeronautics, Imperial College London, South Kensington Campus, London (United Kingdom); Palacios, R., E-mail: r.palacios@imperial.ac.uk [Department of Aeronautics, Imperial College London, South Kensington Campus, London (United Kingdom); Graham, M., E-mail: m.graham@imperial.ac.uk [Department of Aeronautics, Imperial College London, South Kensington Campus, London (United Kingdom); Sherwin, S., E-mail: s.sherwin@imperial.ac.uk [Department of Aeronautics, Imperial College London, South Kensington Campus, London (United Kingdom)

2016-09-15

We propose a generalized strip modelling method that is computationally efficient for the VIV prediction of long flexible cylinders in three-dimensional incompressible flow. In order to overcome the shortcomings of conventional strip-theory-based 2D models, the fluid domain is divided into “thick” strips, which are sufficiently thick to locally resolve the small scale turbulence effects and three dimensionality of the flow around the cylinder. An attractive feature of the model is that we independently construct a three-dimensional scale resolving model for individual strips, which have local spanwise scale along the cylinder's axial direction and are only coupled through the structural model of the cylinder. Therefore, this approach is able to cover the full spectrum for fully resolved 3D modelling to 2D strip theory. The connection between these strips is achieved through the calculation of a tensioned beam equation, which is used to represent the dynamics of the flexible body. In the limit, however, a single “thick” strip would fill the full 3D domain. A parallel Fourier spectral/hp element method is employed to solve the 3D flow dynamics in the strip-domain, and then the VIV response prediction is achieved through the strip–structure interactions. Numerical tests on both laminar and turbulent flows as well as the comparison against the fully resolved DNS are presented to demonstrate the applicability of this approach.

Design, Analysis, and On-Sun Evaluation of Reflective Strips Under Controlled Buckling

Science.gov (United States)

Jaworske, Donald A.; Sechkar, Edward A.; Colozza, Anthony J.

2014-01-01

Solar concentrators are envisioned for use in a variety of space-based applications, including applications involving in situ resource utilization. Identifying solar concentrators that minimize mass and cost are of great interest, especially since launch cost is driven in part by the mass of the payload. Concentrators must also be able to survive the wide temperature excursions on the lunar surface. Identifying smart structures which compensate for changes in concentrator geometry brought about by temperature extremes are of interest. Some applications may benefit from the ability to change the concentrators focal pattern at will. This paper addresses a method of designing a single reflective strip to produce a desired focal pattern through the use of controlled buckling. Small variations in the cross section over the length of the reflective strip influence the distribution of light in the focal region. A finite element method of analysis is utilized here which calculates the curve produced for a given strip cross section and axial load. Varying axial force and strip cross section over the length of the reflective strip provide a means of optimizing ray convergence in the focal region. Careful selection of a tapered cross section yields a reflective strip that approximates a parabola. An array of reflective strips under controlled buckling produces a light weight concentrator and adjustments in the compression of individual strips provide a means of compensating for temperature excursions or changing the focal pattern at will.

360-degrees profilometry using strip-light projection coupled to Fourier phase-demodulation.

Science.gov (United States)

Servin, Manuel; Padilla, Moises; Garnica, Guillermo

2016-01-11

360 degrees (360°) digitalization of three dimensional (3D) solids using a projected light-strip is a well-established technique in academic and commercial profilometers. These profilometers project a light-strip over the digitizing solid while the solid is rotated a full revolution or 360-degrees. Then, a computer program typically extracts the centroid of this light-strip, and by triangulation one obtains the shape of the solid. Here instead of using intensity-based light-strip centroid estimation, we propose to use Fourier phase-demodulation for 360° solid digitalization. The advantage of Fourier demodulation over strip-centroid estimation is that the accuracy of phase-demodulation linearly-increases with the fringe density, while in strip-light the centroid-estimation errors are independent. Here we proposed first to construct a carrier-frequency fringe-pattern by closely adding the individual light-strip images recorded while the solid is being rotated. Next, this high-density fringe-pattern is phase-demodulated using the standard Fourier technique. To test the feasibility of this Fourier demodulation approach, we have digitized two solids with increasing topographic complexity: a Rubik's cube and a plastic model of a human-skull. According to our results, phase demodulation based on the Fourier technique is less noisy than triangulation based on centroid light-strip estimation. Moreover, Fourier demodulation also provides the amplitude of the analytic signal which is a valuable information for the visualization of surface details.

Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy.

Science.gov (United States)

Muti, Mihrican; Erdem, Arzum; Caliskan, Ayfer; Sınag, Ali; Yumak, Tugrul

2011-08-01

The effect of the SnO(2) nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified electrodes were compared to those of unmodified ones and the parameters affecting the response of the modified electrode were optimized. The SNP modified electrodes were then tested for the electrochemical sensing of DNA purine base adenine to explore their further development in biosensor applications. Copyright © 2011 Elsevier B.V. All rights reserved.

Basic chemistry for radioactive waste management

International Nuclear Information System (INIS)

Eom, Tae Yoon; Kim, Sung Soo; Kim, Jeong Seok; Park, Soon Dal; Park, Yong Jun; Seo, Moo Yeul; Sohn, Se Chul; Song, Byung Chul; Lee, Chang Heun; Jun, Young Shin

1992-03-01

Chemical analysis on geological materials was performed for radioactive waste management. Seven major elements including Mn, Fe in JG-2, DWC-l, W-2 and BIR standard samples were determined by acid digestion decomposition and fusion method with sodium carbonate, respectively. About 40 trace elements including Na were determined by instrumental neutron activation analysis method. Retention times of lanthanides were measured by ion chromatography using α-hydroxyisobutyric acid and mandelic acid, respectively. This result gave good agreement between the measured value and the calculated by stepwise elution equation. Trace amount of gallium and indium in natural water were analysed by adsorptive stripping voltammetry using Morin as chelating agent. Detection limit of gallium and indium were 1.1 nM nd 2.6 nM in each. Low level of H-3 and C-14 in natural water were measured by liquid scintillation counting technique. Minimum detectable activity(MDA) by this method were shown to be 0.722 Bq/L and 0.111 Bq/L. (Author)

Electrochemical determination of mesotrione at organoclay modified glassy carbon electrodes.

Science.gov (United States)

Kamga Wagheu, Josephine; Forano, Claude; Besse-Hoggan, Pascale; Tonle, Ignas K; Ngameni, Emmanuel; Mousty, Christine

2013-01-15

A natural Cameroonian smectite-type clay (SaNa) was exchanged with cationic surfactants, namely cetyltrimethylammonium (CTA) and didodecyldimethyl ammonium (DDA) modifying its physico-chemical properties. The resulting organoclays that have higher adsorption capacity for mesotrione than the pristine SaNa clay, have been used as modifiers of glassy carbon electrode for the electrochemical detection of this herbicide by square wave voltammetry. The stripping performances of SaNa, SaCTA and SaDDA modified electrodes were therefore evaluated and the experimental parameters were optimized. SaDDA gives the best results in deoxygenated acetate buffer solution (pH 6.0) after 2 min accumulation under open circuit conditions. Under optimal conditions, the reduction current is proportional to mesotrione concentration in the range from 0.25 to 2.5 μM with a detection limit of 0.26 μM. The fabricated electrode was also applied for the commercial formulation CALLISTO, used in European maize market. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of fenitrothion in water using a voltammetric sensor based on a polymer-modified glassy carbon electrode.

Science.gov (United States)

Amare, Meareg; Abicho, Samuel; Admassie, Shimelis

2014-01-01

A glassy carbon electrode (GCE) modified with poly(4-amino-3-hydroxynaphthalene sulfonic acid) (poly-AHNSA) was used for the selective and sensitive determination of fenitrothion (FT) organophosphorus pesticide in water. The electrochemical behavior of FT at the bare GCE and the poly-AHNSA/GCE were compared using cyclic voltammetry. Enhanced peak current response and shift to a lower potential at the polymer-modified electrode indicated the electrocatalytic activity of the polymer film towards FT. Under optimized solution and method parameters, the adsorptive stripping square wave voltammetric reductive peak current of FT was linear to FT concentration in the range of 0.001 to 6.6 x 10(-6) M, and the LOD obtained (3delta/m) was 7.95 x 10(-10) M. Recoveries in the range 96-98% of spiked FT in tap water and reproducible results with RSD of 2.6% (n = 5) were obtained, indicating the potential applicability of the method for the determination of trace levels of FT in environmental samples.

Phytochelatin Modified Electrode Surface as a Sensitive Heavy- Metal Ion Biosensor

Directory of Open Access Journals (Sweden)

Rene Kizek

2005-02-01

Full Text Available Electrochemical biosensors have superior properties over other existingmeasurement systems because they can provide rapid, simple and low-cost on-fielddetermination of many biological active species and a number of dangerous pollutants. Inour work, we suggested a new heavy metal biosensor based on interaction of heavy metalions (Cd2+ and Zn2+ with phytochelatin, which was adsorbed on the surface of the hangingmercury drop electrode, using adsorptive transfer stripping differential pulse voltammetry.In addition, we applied the suggested technique for the determination of heavy metals in abiological sample – human urine and platinum in a pharmaceutical drug. The detectionlimits (3 S/N of Cd(II, Zn(II and cis-platin were about 1.0, 13.3 and 1.9 pmole in 5 μl,respectively. On the basis of the obtained results, we propose that the suggested techniqueoffers simple, rapid, and low-cost detection of heavy metals in environmental, biologicaland medical samples.

Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00389527; The ATLAS collaboration

2016-01-01

Resistive strip Micromegas detectors are discharge tolerant. They have been tested extensively as small detectors of about 10 x 10 cm$^2$ in size and they work reliably at high rates of 100 kHz/cm$^2$ and above. Tracking resolution well below 100 $\\mu$m has been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3 m$^2$ in size. To investigate possible differences between small and large detectors, a 1 m$^2$ detector with 2048 resistive strips at a pitch of 450 $\\mu$m was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4 $\\times$ 2.2 m$^2$ large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6 mm x 93 mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93 mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, d...

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.

Bioelectrochemical sensing of promethazine with bamboo-type multiwalled carbon nanotubes dispersed in calf-thymus double stranded DNA.

Science.gov (United States)

Primo, Emiliano N; Oviedo, M Belén; Sánchez, Cristián G; Rubianes, María D; Rivas, Gustavo A

2014-10-01

We report the quantification of promethazine (PMZ) using glassy carbon electrodes (GCE) modified with bamboo-like multi-walled carbon nanotubes (bCNT) dispersed in double stranded calf-thymus DNA (dsDNA) (GCE/bCNT-dsDNA). Cyclic voltammetry measurements demonstrated that PMZ presents a thin film-confined redox behavior at GCE/bCNT-dsDNA, opposite to the irreversibly-adsorbed behavior obtained at GCE modified with bCNT dispersed in ethanol (GCE/bCNT). Differential pulse voltammetry-adsorptive stripping with medium exchange experiments performed with GCE/bCNT-dsDNA and GCE modified with bCNTs dispersed in single-stranded calf-thymus DNA (ssDNA) confirmed that the interaction between PMZ and bCNT-dsDNA is mainly hydrophobic. These differences are due to the intercalation of PMZ within the dsDNA that supports the bCNTs, as evidenced from the bathochromic displacement of UV-Vis absorption spectra of PMZ and quantum dynamics calculations at DFTB level. The efficient accumulation of PMZ at GCE/bCNT-dsDNA made possible its sensitive quantification at nanomolar levels (sensitivity: (3.50±0.05)×10(8) μA·cm(-2)·M(-1) and detection limit: 23 nM). The biosensor was successfully used for the determination of PMZ in a pharmaceutical product with excellent correlation. Copyright © 2014 Elsevier B.V. All rights reserved.

Silicon Strip Detectors for ATLAS at the HL-LHC Upgrade

CERN Document Server

Hara, K; The ATLAS collaboration

2012-01-01

The present ATLAS silicon strip (SCT) and transition radiation (TRT) trackers will be replaced with new silicon strip detectors, as part of the Inner Tracker System (ITK), for the Phase-2 upgrade of the Large Hadron Collider, HL-LHC. We have carried out intensive R&D programs to establish radiation harder strip detectors that can survive in a radiation level up to 3000 fb-1 of integrated luminosity based on n+-on-p microstrip detector. We describe main specifications for this year’s sensor fabrication, followed by a description of possible module integration schema

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.)

Wide Strip Casting Technology of Magnesium Alloys

Science.gov (United States)

Park, W.-J.; Kim, J. J.; Kim, I. J.; Choo, D.

Extensive investigations relating to the production of high performance and low cost magnesium sheet by strip casting have been performed for the application to automotive parts and electronic devices. Research on magnesium sheet production technology started in 2004 by Research Institute of Industrial Science and Technology (RIST) with support of Pohang Iron and Steel Company (POSCO). POSCO has completed the world's first plant to manufacture magnesium coil. Another big project in order to develop wide strip casting technology for the automotive applications of magnesium sheets was started in succession.

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

Apparatus for irradiating a continuous line metallic strip with electron beams

International Nuclear Information System (INIS)

Matsuda, Shozo; Tanaka, Tadashi; Okamoto, Tadaaki; Ueno, Nagaharu.

1970-01-01

The secondary X-rays from an irradiated object are completely shielded by providing direction-change rollers between applicator rollers and irradiation devices. The substrate strip turns its direction of travel by 90 0 through idle rollers and before it enters a front side applicator roller. After the application of coatings, the strip travels over a roller to turn upwardly, so that the applicator is isolated from the following irradiation enclosure. Next, the irradiated strip changes its direction by 90 0 through a roller to enter a bake side coating applicator. After a direction change through a roller, the strip enters the irradiation enclosure. In this way, the applicators can prevent leakage of secondary X-rays. (Iwakiri, K.)

Removal of phosphorus from agricultural wastewaters using adsorption media prepared from acid mine drainage sludge

Science.gov (United States)

Sibrell, Philip L.; Montgomery, Gary A.; Ritenour, Kelsey L.; Tucker, Travis W.

2009-01-01

Excess phosphorus in wastewaters promotes eutrophication in receiving waterways. A??cost-effective method for the removal of phosphorus from water would significantly reduce the impact of such wastewaters on the environment. Acid mine drainage sludge is a waste product produced by the neutralization of acid mine drainage, and consists mainly of the same metal hydroxides used in traditional wastewater treatment for the removal of phosphorus. In this paper, we describe a method for the drying and pelletization of acid mine drainage sludge that results in a particulate media, which we have termed Ferroxysorb, for the removal of phosphorus from wastewater in an efficient packed bed contactor. Adsorption capacities are high, and kinetics rapid, such that a contact time of less than 5 min is sufficient for removal of 60-90% of the phosphorus, depending on the feed concentration and time in service. In addition, the adsorption capacity of the Ferroxysorb media was increased dramatically by using two columns in an alternating sequence so that each sludge bed receives alternating rest and adsorption cycles. A stripping procedure based on treatment with dilute sodium hydroxide was also developed that allows for recovery of the P from the media, with the possibility of generating a marketable fertilizer product. These results indicate that acid mine drainage sludges - hitherto thought of as undesirable wastes - can be used to remove phosphorus from wastewater, thus offsetting a portion of acid mine drainage treatment costs while at the same time improving water quality in sensitive watersheds.

stripping of uranium from DEHPA/TOPO solvent by ammonium carbonate solutions

International Nuclear Information System (INIS)

Khorfan, S.; Shino, O.; Wahood, A.; Dahdouh, A.

2002-01-01

Uranium is recovered from phosphoric acid by the DEHPA/TOPO process. In this process uranium is stripped from the loaded DEHPA/TOPO solvent in the second cycle by an ammonium carbonate solution. This paper studied stripping of uranium from 0.3 Mol DEHPA/0.075 Mol TOPO in kerosene by different ammonium carbonate solutions. The ammonium carbonate solutions tested were either made locally from ammonia and carbon dioxide gases or commercial and laboratory grades available on the market. A comparison was made between these carbonate solutions in terms of purity, stripping efficiency and phase separation. Both stripping and phase separation were carried out under different conditions of phase ratio and concentrations. The results obtained showed that ammonium carbonate prepared from direct synthesis of ammonia and carbon dioxide gases had a high purity and gave the same stripping yield as the laboratory grade. The phase separation was also slightly improved using a pure synthesized ammonium carbonate solution. the phase separation was found to be best at concentration of 0.5 Mol/L ammonium carbonate solution and at a phase A/O of 1/1 and a temperature of 50 degree centigrade. It was possible to obtain >99% yield by operating 2 stripping stages counter currently under these conditions. (authors)

Compton recoil electron tracking with silicon strip detectors

International Nuclear Information System (INIS)

O'Neill, T.J.; Ait-Ouamer, F.; Schwartz, I.; Tumer, O.T.; White, R.S.; Zych, A.D.

1992-01-01

The application of silicon strip detectors to Compton gamma ray astronomy telescopes is described in this paper. The Silicon Compton Recoil Telescope (SCRT) tracks Compton recoil electrons in silicon strip converters to provide a unique direction for Compton scattered gamma rays above 1 MeV. With strip detectors of modest positional and energy resolutions of 1 mm FWHM and 3% at 662 keV, respectively, 'true imaging' can be achieved to provide an order of magnitude improvement in sensitivity to 1.6 x 10 - 6 γ/cm 2 -s at 2 MeV. The results of extensive Monte Carlo calculations of recoil electrons traversing multiple layers of 200 micron silicon wafers are presented. Multiple Coulomb scattering of the recoil electron in the silicon wafer of the Compton interaction and the next adjacent wafer is the basic limitation to determining the electron's initial direction