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Hadjisolomou P, Jeong TM, Valenta P, Korn G, Bulanov SV. Gamma-ray flash generation in irradiating a thin foil target by a single-cycle tightly focused extreme power laser pulse. Phys Rev E 2021; 104:015203. [PMID: 34412282 DOI: 10.1103/physreve.104.015203] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 06/15/2021] [Indexed: 11/07/2022]
Abstract
We present a regime where an ultraintense laser pulse interacting with a foil target results in high γ-photon conversion efficiency, obtained via three-dimensional quantum-electrodynamics particle-in-cell simulations. A single-cycle laser pulse is used under the tight-focusing condition for obtaining the λ^{3} regime. The simulations employ a radially polarized laser as it results in higher γ-photon conversion efficiency compared to both azimuthal and linear polarizations. A significant fraction of the laser energy is transferred to positrons, while a part of the electromagnetic wave escapes the target as attosecond single-cycle pulses.
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Affiliation(s)
- P Hadjisolomou
- ELI Beamlines Centre, Institute of Physics, Czech Academy of Sciences, Za Radnicí 835, 25241 Dolní Břežany, Czech Republic
| | - T M Jeong
- ELI Beamlines Centre, Institute of Physics, Czech Academy of Sciences, Za Radnicí 835, 25241 Dolní Břežany, Czech Republic
| | - P Valenta
- ELI Beamlines Centre, Institute of Physics, Czech Academy of Sciences, Za Radnicí 835, 25241 Dolní Břežany, Czech Republic
| | - G Korn
- ELI Beamlines Centre, Institute of Physics, Czech Academy of Sciences, Za Radnicí 835, 25241 Dolní Břežany, Czech Republic
| | - S V Bulanov
- ELI Beamlines Centre, Institute of Physics, Czech Academy of Sciences, Za Radnicí 835, 25241 Dolní Břežany, Czech Republic
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Mu J, Esirkepov TZ, Valenta P, Gu Y, Jeong TM, Pirozhkov AS, Koga JK, Kando M, Korn G, Bulanov SV. Relativistic flying forcibly oscillating reflective diffraction grating. Phys Rev E 2020; 102:053202. [PMID: 33327116 DOI: 10.1103/physreve.102.053202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/08/2020] [Indexed: 11/07/2022]
Abstract
Relativistic flying forcibly oscillating reflective diffraction gratings are formed by an intense laser pulse (driver) in plasma. The mirror surface is an electron density singularity near the joining area of the wake wave cavity and the bow wave; it moves together with the driver laser pulse and undergoes forced oscillations induced by the field. A counterpropagating weak laser pulse (source) is incident at grazing angles, being efficiently reflected and enriched by harmonics. The reflected spectrum consists of the source pulse base frequency and its harmonics, multiplied by a large factor due to the double Doppler effect.
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Affiliation(s)
- Jie Mu
- ELI Beamlines Project, Institute of Physics of the ASCR, Na Slovance 2, 18221 Prague, Czech Republic
| | - Timur Zh Esirkepov
- Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
| | - Petr Valenta
- ELI Beamlines Project, Institute of Physics of the ASCR, Na Slovance 2, 18221 Prague, Czech Republic.,Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 11519 Prague, Czech Republic
| | - Yanjun Gu
- ELI Beamlines Project, Institute of Physics of the ASCR, Na Slovance 2, 18221 Prague, Czech Republic
| | - Tae Moon Jeong
- ELI Beamlines Project, Institute of Physics of the ASCR, Na Slovance 2, 18221 Prague, Czech Republic
| | - Alexander S Pirozhkov
- Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
| | - James K Koga
- Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
| | - Masaki Kando
- Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
| | - Georg Korn
- ELI Beamlines Project, Institute of Physics of the ASCR, Na Slovance 2, 18221 Prague, Czech Republic
| | - Sergei V Bulanov
- ELI Beamlines Project, Institute of Physics of the ASCR, Na Slovance 2, 18221 Prague, Czech Republic.,Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
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Valenta P, Esirkepov TZ, Koga JK, Nečas A, Grittani GM, Lazzarini CM, Klimo O, Korn G, Bulanov SV. Polarity reversal of wakefields driven by ultrashort pulse laser. Phys Rev E 2020; 102:053216. [PMID: 33327156 DOI: 10.1103/physreve.102.053216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/25/2020] [Indexed: 06/12/2023]
Abstract
Using an analytical model and computer simulation, we show that the wakefield driven by an ultrashort laser pulse in high-density plasma periodically reverses its polarity due to the carrier-envelope phase shift of the driver. The wakefield polarity reversal occurs on spatial scales shorter than the typical length considered for electron acceleration with the laser-wakefield mechanism. Consequently, the energies of accelerated electrons are significantly affected. The results obtained are important for the laser-wakefield acceleration under the conditions relevant to present-day high-repetition-rate laser systems.
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Affiliation(s)
- P Valenta
- ELI Beamlines, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 18221, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, Prague 11519, Czech Republic
| | - T Zh Esirkepov
- Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, Umemidai 8-1-7, Kizugawa, Kyoto 619-0215, Japan
| | - J K Koga
- Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, Umemidai 8-1-7, Kizugawa, Kyoto 619-0215, Japan
| | - A Nečas
- TAE Technologies, Pauling 19631, Foothill Ranch, California 92610, USA
| | - G M Grittani
- ELI Beamlines, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 18221, Czech Republic
| | - C M Lazzarini
- ELI Beamlines, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 18221, Czech Republic
| | - O Klimo
- ELI Beamlines, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 18221, Czech Republic
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, Prague 11519, Czech Republic
| | - G Korn
- ELI Beamlines, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 18221, Czech Republic
| | - S V Bulanov
- ELI Beamlines, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 18221, Czech Republic
- Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, Umemidai 8-1-7, Kizugawa, Kyoto 619-0215, Japan
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Moravec T, Valenta P. The Comparison of Efficiency of Disqualification of Directors in New Czech Business Corporation Act and in the Legal System of England. Acta Univ Agric Silvic Mendelianae Brun 2015. [DOI: 10.11118/actaun201563051711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Revis N, Merks A, Valenta P, Rützel H. Heavy metal uptake by plankton and other seston particles. Chemical Speciation & Bioavailability 2015. [DOI: 10.1080/09542299.1989.11083105] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Koglin E, Séquaris JM, Valenta P. Hydrogen-Deuterium Exchange in Adenosine 5'-Monophosphate Detected by Surface Enhanced Raman Scattering (SERS). ACTA ACUST UNITED AC 2014. [DOI: 10.1515/znc-1981-9-1019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The enhanced Raman effect from 5'-AMP adsorbed on the roughened silver surface is used to characterize hydrogen-deuterium exchange. SERS spectra of 5'-AMP present in H2O and D2O solutions at rather low concentrations were recorded in the spectral range of 2000 to 3500 cm-1. Surface enhanced Raman bands in this spectral range are found to increase in intensity, relative to bands of normal Raman solution spectra. In addition, one notes that the CH and CD stretching vibrations, almost obscured by H2O2 or D2O scattering, now stand out clearly.
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Affiliation(s)
- E. Koglin
- Institut für Chemie der Kemforschungsanlage Jülich GmbH, Institut 4: Angewandte Physikalische Chemie, D-5170 Jülich, Bundesrepublik Deutschland
| | - J. M. Séquaris
- Institut für Chemie der Kemforschungsanlage Jülich GmbH, Institut 4: Angewandte Physikalische Chemie, D-5170 Jülich, Bundesrepublik Deutschland
| | - P. Valenta
- Institut für Chemie der Kemforschungsanlage Jülich GmbH, Institut 4: Angewandte Physikalische Chemie, D-5170 Jülich, Bundesrepublik Deutschland
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Valenta P, Carroll PJ, Walsh PJ. Stereoselective synthesis of β-hydroxy enamines, aminocyclopropanes, and 1,3-amino alcohols via asymmetric catalysis. J Am Chem Soc 2010; 132:14179-90. [PMID: 20853837 PMCID: PMC3014220 DOI: 10.1021/ja105435y] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tandem methods for the catalytic asymmetric preparation of enantioenriched β-hydroxy (E)-enamines and aminocyclopropanes are presented. The diastereoselective hydrogenation of enantioenriched (E)-trisubstituted hydroxy enamines to generate 1,2-disubstituted-1,3-amino alcohols is also outlined. These methods are initiated by highly regioselective hydroboration of N-tosyl-substituted ynamides with diethylborane to generate β-amino alkenyl boranes. In situ boron-to-zinc transmetalation generates β-amino alkenylzinc reagents. These functionalized vinylzinc intermediates are subsequently added to aldehydes in the presence of a catalyst derived from an enantioenriched amino alcohol (morpholino isoborneol, MIB). The catalyst promotes highly enantioselective C-C bond formation to provide β-hydroxy enamines in good isolated yields (68-86%) with 54-98% enantioselectivity. The intermediate zinc β-alkoxy enamines can be subjected to a tandem cyclopropanation to afford aminocyclopropyl carbinols with three continuous stereocenters in a one-pot procedure with good yields (72-82%), enantioselectivities of 76-94%, and >20:1 diastereomeric ratios. Diastereoselective hydrogenation of isolated enantioenriched β-hydroxy enamines over Pd/C furnished syn-1,2-disubstituted-1,3-amino alcohols in high yields (82-90%) with moderate to excellent diastereoselectivities. These methods were used in an efficient preparation of the enantioenriched precursor to PRC200-SS derivatives, which are potent serotonin-norepinephrine-dopamine reuptake inhibitors.
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Affiliation(s)
- Petr Valenta
- P. Roy and Diana T. Vagelos Laboratories, University of Pennsylvania, Department of Chemistry, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323
| | - Patrick J. Carroll
- P. Roy and Diana T. Vagelos Laboratories, University of Pennsylvania, Department of Chemistry, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323
| | - Patrick J. Walsh
- P. Roy and Diana T. Vagelos Laboratories, University of Pennsylvania, Department of Chemistry, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323
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Abstract
A simple and efficient method to convert aldehydes into alpha,beta-unsaturated aldehydes with a two-carbon homologation is presented. Hydroboration of ethoxy acetylene with BH(3).SMe(2) generates tris(ethoxyvinyl) borane. Transmetalation with diethylzinc, addition to aldehydes or ketones, and acidic workup affords enals. When the addition is quenched with anilinium hydrochloride, 1,2-dithioglycol, or acetic anhydride, the unsaturated imine, dithiolane, or 1,1-diacetate is isolated in high yield. These transformations can be performed in a one-pot procedure.
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Affiliation(s)
- Petr Valenta
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA
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Jin W, Nguyen VD, Valenta P, Nürnberg HW. Simultaneous Determination of Seven Toxic Trace and/or Ultratrace Metals in Environmental Plants by Differential Pulse Voltammetry Without Change of Solution and Electrode. ANAL LETT 2006. [DOI: 10.1080/00032719708004052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Queirolo F, Valenta P, Stegen S, Sanchez AM. Study of the radial and axial distribution of heavy metals in oak growth rings by stripping voltammetry. ELECTROANAL 1991. [DOI: 10.1002/elan.1140030413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Queirolo F, Ostapczuk P, Valenta P, Stegen S, Mar�n C, Vinagre F, S�nchez A. 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. Anal Bioanal Chem 1991. [DOI: 10.1007/bf00324396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Queirolo F, Ostapczuk P, Valenta P, Stegen S, Mar�n C, Vinagre F, Sanchez A. Determination of Cd in Navajuelas (Tagelus dombeii) by differential pulse anodic stripping voltammetry (DPASV). Anal Bioanal Chem 1991. [DOI: 10.1007/bf00328501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Temerk Y, Kamal M, Valenta P. Adsorption and association of adenosine dinucleotides at charged interfaces. J Electroanal Chem (Lausanne) 1990. [DOI: 10.1016/0022-0728(90)87518-o] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Oehme F, Valenta P. Ionenselektive elektroden. Anal Chim Acta 1987. [DOI: 10.1016/s0003-2670(00)82852-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Qneirolo F, Valenta P. Trace determination of Cd, Cu, Pb and Zn in annual growth rings by differential pulse anodic stripping voltammetry. ACTA ACUST UNITED AC 1987. [DOI: 10.1007/bf00560958] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ostapczuk P, Valenta P, Nürnberg H. Square wave voltammetry - a rapid and reliable determination method of Zn, Cd, Pb, Cu, Ni and Co in biological and environmental samples. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0022-0728(86)80085-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Pihlar B, Valenta P, Nürnberg H. Electrochemical reduction of Ni(II) on the hanging mercury drop electrode in the presence of dimethylglyoxime. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0022-0728(86)80094-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Czochralska B, Bojarska E, Valenta P, Nürnberg H. On the participation of adenine reduction in the electrochemical reduction of the coenzyme NAD+. ACTA ACUST UNITED AC 1985. [DOI: 10.1016/0302-4598(85)80022-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Golimowski J, Valenta P, Nürnberg HW. Trace determination of chromium in various water types by adsorption differential pulse voltammetry. ACTA ACUST UNITED AC 1985. [DOI: 10.1007/bf00490915] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Wagner F, Valenta P, Nürnberg HW. Ionen-chromatographische Bestimmung der Anionen Cl−, NO
3
−
und SO
4
2−
in Regenwasser. ACTA ACUST UNITED AC 1985. [DOI: 10.1007/bf00479814] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Narres HD, Valenta P, Nürnberg HW. [Voltammetric determination of heavy metals in meat and the internal organs of slaughter cattle]. Z Lebensm Unters Forsch 1984; 179:440-6. [PMID: 6524082 DOI: 10.1007/bf01043421] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The most important uptake of heavy metal by man occurs through ingestion. Therefore heavy metal analysis of food becomes of great importance. The whole analytical procedure including sampling, transport, drying, homogenisation, digestion and measurement for the determination of Zn, Cd, Pb, Cu, Ni, and Co in meat is described with due consideration given to the requirements for trace and ultratrace analysis. The particular advantages of the voltammetric approach for heavy metal determinations in meat and meat products are generally featured by this study. A standard deviation of 3-5% RSD in the microgram/g-range and 5-10%-RSD in the ng/g-range was obtained. In order to check the accuracy of the results, mixtures of sample and standard reference material were analysed. While the Cd-content in meat is in the range of 1 ng/g (wet weight) it increases in organs, such as liver (100-500 ng/g wet weight) and kidney (600-2000 ng/g wet weight). Pb shows a similar behaviour. The levels of these elements were found to be below the maximum allowable limits set by the "Bundesgesundheitsamt", with the exception of Cd in the kidneys. There is a statistical significant correlation between the Cd and Pb contents in liver and kidney. In liver the Cu content was especially high, because there are Cu-containing enzymes in this organ. Vitamin B12 is a Co containing complex in the liver. Therefore the Co values in liver are clearly higher than those in muscle meat.
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Sugawara M, Valenta P, Nürnberg H, Kambara T. Voltammetric study of the speciation of cadmium(II) with L-aspartic acid in sea water. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0368-1874(84)83592-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Narasimhan SV, Valenta P, N�rnberg HW. Study on the speciation of copper(I) in the presence of cyclohexylamine in alkaline solution by differential pulse polarography. Mikrochim Acta 1984. [DOI: 10.1007/bf01207076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Narres HD, Valenta P, Nürnberg HW. Inversvoltammetrische Bestimmung von Schwermetallen in Fleisch, Leber und Nieren von Schlachtrindern. ACTA ACUST UNITED AC 1984. [DOI: 10.1007/bf00494524] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Simões Goncalves M, Valenta P, Nürnberg H. Voltammetric and potentiometric investigations on the complexation of Cd(II) by glycine in seawater. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/s0022-0728(83)80573-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Mart L, Rützel H, Klahre P, Sipos L, Platzek U, Valenta P, Nürnberg HW. Comparative studies on the distribution of heavy metals in the oceans and coastal waters. Sci Total Environ 1982; 26:1-17. [PMID: 7167812 DOI: 10.1016/0048-9697(82)90092-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Results of our investigations during the last five years are summarized. The concentrations of Cd, Pb and Cu have been determined in coastal areas of the Western Mediterranean and the North Sea, reflecting the influence of the pollution sources along the shore line. Deep sea water and surface water sample from the Pacific, Atlantic, Mediterranean and Arctic Sea have been analyzed for Cd, Pb, Cu and at some stations also additionally for Ni, Co. It is demonstrated that concentration levels of surface and deep sea waters may differ significantly in diverse oceans. The same is valid to a greater extent for coastal waters affected particularly by anthropogenic input that can be dispersed by tidal currents. Applying reliable sampling methods and the voltammetric determination procedure in particular suitable for heavy metals at the trace level, significant contributions to a consistent data basis for the distribution of heavy metals in the sea could be achieved.
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Séquaris JM, Valenta P, Nürnberg HW. A new electrochemical approach for the in vitro investigation of damage in native DNA by small gamma-radiation doses. Int J Radiat Biol Relat Stud Phys Chem Med 1982; 42:407-15. [PMID: 6983509 DOI: 10.1080/09553008214551331] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Voltammetry provides a new method to assess gamma-radiation damage to native DNA in vitro after low doses of irradiation. Using single sweep voltammetry at a stationary mercury electrode a substantial labilization of the double helical conformation of gamma-irradiated DNA was found. Up to 40 Gy a linear dose-effect relationship exists reflected for the number of strand breaks and the number of destabilized base pairs. A considerable difference in the frequency of formation of the two kinds of radiation damage is seen in the ratio of their G-values. Base pair labilization occurs depending on aeration conditions 200 to 300 times more frequently than the formation of a single strand break.
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Bodewig FG, Valenta P, Nürnberg HW. Trace determination of As(III) and As(V) in natural waters by differential pulse anodic stripping voltammetry. ACTA ACUST UNITED AC 1982. [DOI: 10.1007/bf00476644] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Reddy SJ, Valenta P, Nürnberg HW. Simultaneous determination of the toxic trace metals Cd, Cu, Pb and Zn in soils by differential pulse anodic stripping voltammetry. ACTA ACUST UNITED AC 1982. [DOI: 10.1007/bf00495840] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ervin K, Koglin E, Sequaris J, Valenta P, Nürnberg H. Surface enhanced Raman spectra of nucleic acid components adsorbed at a silver electrode. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/s0022-0728(80)80446-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Temerk Y, Valenta P, Nürnberg H. Electrochemical behavior of mono- and oligonucleotides. VIII. Voltammetric studies on the interfacial behavior of mono-, Di- and triphosphate of cytidine. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/s0022-0728(80)80300-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Mart L, N�rnberg HW, Valenta P. Prevention of contamination and other accuracy risks in voltammetric trace metal analysis of natural waters. ACTA ACUST UNITED AC 1980. [DOI: 10.1007/bf01154736] [Citation(s) in RCA: 124] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Golimowski J, Valenta P, Stoeppler M, Nürnberg HW. Toxic trace metals in food. II. A comparative study of the levels of toxic trace metals in wine by differential pulse anodic stripping voltammetry and electrothermal atomic absorption spectrometry. Z Lebensm Unters Forsch 1979; 168:439-43. [PMID: 463347 DOI: 10.1007/bf01479257] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A new high-performance analytical procedure for the determination of the toxic trace metals cadmium, lead and copper in wines by differential pulse anodic-stripping voltammetry (DPASV) subsequent to UV irradiation of the sample is compared with the hitherto more common application of electrothermal atomic absorption spectrometry (AAS). In this manner also mutually the accuracy attainable with both alternatives has been established. The particularly favourable potentialities of the new voltammetric approach for toxic metal control of wines are demonstrated by the investigation of a typical selection of 36 wines from recent vintages and common vine types of the German and some European wine cultivating regions.
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Golimowski J, Valenta P, Nürnberg HW. Toxic trace metals in food. I. A new voltammetric procedure for toxic trace metal control of wines. Z Lebensm Unters Forsch 1979; 168:353-9. [PMID: 473925 DOI: 10.1007/bf01186492] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A new highly sensitive and particularly reliable analytical procedure for the precise determination of the most relevant toxic trace metals cadmium, lead and copper in wine is presented. It consists of a simple and convenient sample pretreatment by UV irradiation (1,5 h, 500-W-Hg-lamp) to release the toxic trace metals bound by organic substances and subsequent voltammetry (DPASV) of cadmium and lead simultaneously at a mercury film electrode (MFE) formed in situ on a vitreous carbon carrier and of copper on a gold electrode. Particular emphasis has been placed on the efficient exclusion of interference due to contamination. Only special wines, with more than 10% of sugar, require substitution of UV irradiation by a wet digestion also described. The procedure may be easily expanded to include the determination of mercury and zinc.
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Valenta P. J Electroanal Chem (Lausanne) 1979; 104:620-621. [DOI: 10.1016/s0022-0728(79)81075-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Malfoy B, Sequaris J, Valenta P, Nürnberg H. Electrochemical behaviour of natural and biosynthetic polynucleotides at the mercury electrode. ACTA ACUST UNITED AC 1977. [DOI: 10.1016/s0022-0728(77)80190-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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