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Goodman WR, Scott ER, Keith Z, Singh L, Anderson DT. Upgrade of the helically symmetric experiment Thomson scattering diagnostic suite. Rev Sci Instrum 2022; 93:093518. [PMID: 36182445 DOI: 10.1063/5.0101879] [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] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/17/2022] [Indexed: 06/16/2023]
Abstract
The Helically Symmetric eXperiment (HSX) Thomson Scattering (TS) diagnostic is being upgraded to decrease uncertainty in electron temperature and density measurements. Upgrades to the HSX TS diagnostic will consist of a novel redesign of polychromator electronics and digitization of the TS output signal. Here, we also present a study of the benefits of an additional spectral channel that will sample the red-shifted band of the scattered spectrum. To maximize system bandwidth (BW) and gain, while minimizing noise, the existing low-BW polychromator electronics on HSX will be replaced by high-BW, high gain circuitry designed in-house.
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Affiliation(s)
- W R Goodman
- HSX Plasma Laboratory, University of Wisconsin, Madison, Wisconsin 53703, USA
| | - E R Scott
- HSX Plasma Laboratory, University of Wisconsin, Madison, Wisconsin 53703, USA
| | - Z Keith
- HSX Plasma Laboratory, University of Wisconsin, Madison, Wisconsin 53703, USA
| | - L Singh
- HSX Plasma Laboratory, University of Wisconsin, Madison, Wisconsin 53703, USA
| | - D T Anderson
- HSX Plasma Laboratory, University of Wisconsin, Madison, Wisconsin 53703, USA
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Beidler CD, Smith HM, Alonso A, Andreeva T, Baldzuhn J, Beurskens MNA, Borchardt M, Bozhenkov SA, Brunner KJ, Damm H, Drevlak M, Ford OP, Fuchert G, Geiger J, Helander P, Hergenhahn U, Hirsch M, Höfel U, Kazakov YO, Kleiber R, Krychowiak M, Kwak S, Langenberg A, Laqua HP, Neuner U, Pablant NA, Pasch E, Pavone A, Pedersen TS, Rahbarnia K, Schilling J, Scott ER, Stange T, Svensson J, Thomsen H, Turkin Y, Warmer F, Wolf RC, Zhang D. Publisher Correction: Demonstration of reduced neoclassical energy transport in Wendelstein 7-X. Nature 2021; 598:E5. [PMID: 34642470 PMCID: PMC8550957 DOI: 10.1038/s41586-021-04023-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- C D Beidler
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany.
| | - H M Smith
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - A Alonso
- Laboratorio Nacional de Fusion, CIEMAT, Madrid, Spain
| | - T Andreeva
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Baldzuhn
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | | | - M Borchardt
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - S A Bozhenkov
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - K J Brunner
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - H Damm
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - M Drevlak
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - O P Ford
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - G Fuchert
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Geiger
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - P Helander
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - U Hergenhahn
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany.,Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
| | - M Hirsch
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - U Höfel
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - Ye O Kazakov
- Laboratory for Plasma Physics (LPP), École royale militaire/Koninklijke Militaire School (ERM/KMS), Brussels, Belgium
| | - R Kleiber
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - M Krychowiak
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - S Kwak
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - A Langenberg
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - H P Laqua
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - U Neuner
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - N A Pablant
- Princeton Plasma Physics Laboratory, Princeton, NJ, USA
| | - E Pasch
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - A Pavone
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - T S Pedersen
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - K Rahbarnia
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Schilling
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - E R Scott
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - T Stange
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Svensson
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - H Thomsen
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - Y Turkin
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - F Warmer
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - R C Wolf
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - D Zhang
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
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Beidler CD, Smith HM, Alonso A, Andreeva T, Baldzuhn J, Beurskens MNA, Borchardt M, Bozhenkov SA, Brunner KJ, Damm H, Drevlak M, Ford OP, Fuchert G, Geiger J, Helander P, Hergenhahn U, Hirsch M, Höfel U, Kazakov YO, Kleiber R, Krychowiak M, Kwak S, Langenberg A, Laqua HP, Neuner U, Pablant NA, Pasch E, Pavone A, Pedersen TS, Rahbarnia K, Schilling J, Scott ER, Stange T, Svensson J, Thomsen H, Turkin Y, Warmer F, Wolf RC, Zhang D. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X. Nature 2021; 596:221-226. [PMID: 34381232 PMCID: PMC8357633 DOI: 10.1038/s41586-021-03687-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/02/2021] [Indexed: 02/07/2023]
Abstract
Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak1 is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)2, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator's non-turbulent 'neoclassical' energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas3,4. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible1,5. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization.
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Affiliation(s)
- C D Beidler
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany.
| | - H M Smith
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - A Alonso
- Laboratorio Nacional de Fusion, CIEMAT, Madrid, Spain
| | - T Andreeva
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Baldzuhn
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | | | - M Borchardt
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - S A Bozhenkov
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - K J Brunner
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - H Damm
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - M Drevlak
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - O P Ford
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - G Fuchert
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Geiger
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - P Helander
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - U Hergenhahn
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
| | - M Hirsch
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - U Höfel
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - Ye O Kazakov
- Laboratory for Plasma Physics (LPP), École royale militaire/Koninklijke Militaire School (ERM/KMS), Brussels, Belgium
| | - R Kleiber
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - M Krychowiak
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - S Kwak
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - A Langenberg
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - H P Laqua
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - U Neuner
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - N A Pablant
- Princeton Plasma Physics Laboratory, Princeton, NJ, USA
| | - E Pasch
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - A Pavone
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - T S Pedersen
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - K Rahbarnia
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Schilling
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - E R Scott
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - T Stange
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - J Svensson
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - H Thomsen
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - Y Turkin
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - F Warmer
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - R C Wolf
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - D Zhang
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
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Ford OP, Vanó L, Alonso JA, Baldzuhn J, Beurskens MNA, Biedermann C, Bozhenkov SA, Fuchert G, Geiger B, Hartmann D, Jaspers RJE, Kappatou A, Langenberg A, Lazerson SA, McDermott RM, McNeely P, Neelis TWC, Pablant NA, Pasch E, Rust N, Schroeder R, Scott ER, Smith HM, Wegner T, Kunkel F, Wolf RC. Charge exchange recombination spectroscopy at Wendelstein 7-X. Rev Sci Instrum 2020; 91:023507. [PMID: 32113444 DOI: 10.1063/1.5132936] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/16/2020] [Indexed: 06/10/2023]
Abstract
The Charge Exchange Recombination Spectroscopy (CXRS) diagnostic has become a routine diagnostic on almost all major high temperature fusion experimental devices. For the optimized stellarator Wendelstein 7-X (W7-X), a highly flexible and extensive CXRS diagnostic has been built to provide high-resolution local measurements of several important plasma parameters using the recently commissioned neutral beam heating. This paper outlines the design specifics of the W7-X CXRS system and gives examples of the initial results obtained, including typical ion temperature profiles for several common heating scenarios, toroidal flow and radial electric field derived from velocity measurements, beam attenuation via beam emission spectra, and normalized impurity density profiles under some typical plasma conditions.
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Affiliation(s)
- O P Ford
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - L Vanó
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - J A Alonso
- CIEMAT, Avenida Complutense, 40, 28040 Madrid, Spain
| | - J Baldzuhn
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - M N A Beurskens
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - C Biedermann
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - S A Bozhenkov
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - G Fuchert
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - B Geiger
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - D Hartmann
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - R J E Jaspers
- Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
| | - A Kappatou
- Max-Planck Institut für Plasmaphysik, 85748 Garching, Germany
| | - A Langenberg
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - S A Lazerson
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - R M McDermott
- Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
| | - P McNeely
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - T W C Neelis
- Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
| | - N A Pablant
- Princeton University Plasma Physics Laboratory, Princeton, New Jersey 08544, USA
| | - E Pasch
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - N Rust
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - R Schroeder
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - E R Scott
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - H M Smith
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - Th Wegner
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - F Kunkel
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - R C Wolf
- Max-Planck Institut für Plasmaphysik, 17491 Greifswald, Germany
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Bozhenkov SA, Heym SJ, Beurskens MNA, Fuchert G, Pasch E, Scott ER, Wolf RC. On using Rayleigh scattering for in situ spectral calibration of Thomson scattering diagnostics. Rev Sci Instrum 2019; 90:033505. [PMID: 30927799 DOI: 10.1063/1.5072781] [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] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 02/28/2019] [Indexed: 06/09/2023]
Abstract
A new method for in situ spectral calibration of Thomson scattering diagnostics is proposed. The idea of the method is to apply a wavelength tunable optical parametric oscillator for measurements of Rayleigh scattering at different wavelengths, from which relative sensitivities can be calculated. This extends the usual approach where Rayleigh scattering is used only at a single wavelength for the absolute calibration and spectral sensitivities are obtained separately. With the new approach, the full diagnostic setup is spectrally calibrated at once. Such a calibration can be repeated at regular intervals during an experimental campaign since it does not require a break of the vacuum. In this paper, the Rayleigh scattering calibration is tested in a laboratory setup with a sample Wendelstein 7-X (W7-X) polychromator. It is shown that relative sensitivities of spectral channels can be recovered with a sufficient resolution even under conditions of significant stray light. The stray light is overcome by measuring the linear dependence of the scattered signal on the gas pressure. Good results of laboratory tests motivate the installation of the new calibration system for the Thomson scattering diagnostic at W7-X.
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Affiliation(s)
- S A Bozhenkov
- Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald, Germany
| | - S J Heym
- Faculty of Mathematics and Natural Sciences, Technical University of Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - M N A Beurskens
- Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald, Germany
| | - G Fuchert
- Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald, Germany
| | - E Pasch
- Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald, Germany
| | - E R Scott
- Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald, Germany
| | - R C Wolf
- Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald, Germany
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Scott ER, Barchfeld R, Riemenschneider P, Domier CW, Muscatello CM, Sohrabi M, Kaita R, Ren Y, Luhmann NC. Far-infrared tangential interferometer/polarimeter design and installation for NSTX-U. Rev Sci Instrum 2016; 87:11E114. [PMID: 27910494 DOI: 10.1063/1.4960415] [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] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Far-infrared Tangential Interferometer/Polarimeter (FIReTIP) system has been refurbished and is being reinstalled on the National Spherical Torus Experiment-Upgrade (NSTX-U) to supply real-time line-integrated core electron density measurements for use in the NSTX-U plasma control system (PCS) to facilitate real-time density feedback control of the NSTX-U plasma. Inclusion of a visible light heterodyne interferometer in the FIReTIP system allows for real-time vibration compensation due to movement of an internally mounted retroreflector and the FIReTIP front-end optics. Real-time signal correction is achieved through use of a National Instruments CompactRIO field-programmable gate array.
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Affiliation(s)
- E R Scott
- Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616, USA
| | - R Barchfeld
- Department of Applied Science, University of California, Davis, California 95616, USA
| | - P Riemenschneider
- Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA
| | - C W Domier
- Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA
| | | | - M Sohrabi
- Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA
| | - R Kaita
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - Y Ren
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - N C Luhmann
- Department of Electrical and Computer Engineering, University of California, Davis, California 95616, USA
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7
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Bath BD, Scott ER, Phipps JB, White HS. Scanning electrochemical microscopy of iontophoretic transport in hairless mouse skin. Analysis of the relative contributions of diffusion, migration, and electroosmosis to transport in hair follicles. J Pharm Sci 2000; 89:1537-49. [PMID: 11042601 DOI: 10.1002/1520-6017(200012)89:12<1537::aid-jps4>3.0.co;2-j] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Scanning electrochemical microscopy (SECM) is used to measure spatially localized diffusive and iontophoretic transport rates in hairless mouse skin. Molecular fluxes within individual hair follicles are quantified by measuring the rate at which redox-active probe molecules emerge from the follicle. The influence of an applied current on the flux of an anion (ascorbate), a cation (ferrocenylmethyltrimethylammonium), and a neutral molecule (acetaminophen) is used to determine the contributions of diffusion, migration, and electroosmosis to iontophoretic transport. The direction of electroosmotic transport is consistent with hair follicles possessing a net negative charge at neutral pH. Electroosmosis results in a modest increase in the transport rate of the neutral molecule (a factor of approximately 2.4x at an iontophoretic current density of 0.1 mA/cm(2)). Larger enhancements in the flux of the electrically charged species are associated with migration. The electroosmotic flow velocity within hair follicles is established to be 0.5 (+/-0.1) microm/s at 0.1 mA/cm(2), independent of the electrical charge of permeant. The net volume flow rate across skin resulting from electroosmosis in hair follicles is estimated to be 0.3 microL/cm(2)h. The results suggest that hair follicles are a significant pathway for electroosmotic solution flow during iontophoresis. The radius of the hair follicle openings in hairless mouse skin is measured to be 21 +/- 5 microm.
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Affiliation(s)
- B D Bath
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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8
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Abstract
PURPOSE To identify the physiological structures in hairless mouse skin responsible for the generation of electroosmotic flow during iontophoresis. Also, to determine the effects of changing the pH of the contacting solution on the magnitude of electroosmotic flow in these structures. METHODS Localized diffusive and iontophoretic fluxes of a neutral molecule, hydroquinone (HQ), across hairless mouse skin were quantified using scanning electrochemical microscopy (SECM). The iontophoretic flux was determined as a function of the direction of the applied current and pH of the contacting solution. RESULTS SECM images of HQ transport recorded during iontophoresis at moderate current densities (+/-0.1 mA/cm2) demonstrate that electroosmotic flow is localized to hair follicles. The direction of flow is from anode to cathode at pH > 3.5 and from cathode to anode at pH <3.5. CONCLUSIONS Electroosmotic flow through hair follicles is an efficient and controllable means of transporting small, electrically neutral molecules across hairless mouse skin. Transport through the appendages is sensitive to the pH of the solution in contact with the skin. The isoelectric point of hair follicles, pI, is estimated to be 3.5 from the dependence of electroosmotic flow on the solution pH.
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Affiliation(s)
- B D Bath
- Department of Chemistry, University of Utah, Salt Lake City 84112, USA
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Bath BD, White HS, Scott ER. Electrically facilitated molecular transport. Analysis of the relative contributions of diffusion, migration, and electroosmosis to solute transport in an ion-exchange membrane. Anal Chem 2000; 72:433-42. [PMID: 10695125 DOI: 10.1021/ac9910637] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electrically facilitated molecular transport in an ion-exchange membrane (Nafion, 1100 equiv wt) has been studied using a scanning electrochemical microscope. The transport rates of ferrocenylmethyltrimethylammonium (a cation), acetaminophen (a neutral molecule), and ascorbate (an anion) through approximately 120-micron-thick membranes were measured as a function of the iontophoretic current passed across the membrane (-1.0 to +1.0 A/cm2). Transport rates were analyzed by employing the Nernst-Planck equation, modified to account for electric field-driven convective transport. Excellent agreement between experimental and theoretical values of the molecular flux was obtained using a single fitting parameter for each molecule (electroosmotic drag coefficient). The electroosmotic velocity of the neutral molecule, acetaminophen, was shown to be a factor of approximately 500 larger than that of the cation ferrocenylmethyltrimethylammonium, a consequence of the electrostatic interaction of the cation with the negatively charged pore walls of the ion-exchange membrane. Electroosmotic transport of ascorbate occurred at a negligible rate due to repulsion of the anion by the cation-selective membrane. These results suggest that electroosmotic velocities of solute molecules are determined by specific chemical interactions of the permeant and membrane and may be very different from the average solution velocity. The efficiency of electroosmotic transport was also shown to be a function of the membrane thickness, in addition to membrane/solute interactions.
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Affiliation(s)
- B D Bath
- Department of Chemistry, University of Utah, Salt Lake City 84112, USA
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10
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Abstract
A review of the mineralogical, isotopic, and chemical properties of the carbonates and associated submicrometer iron oxides and sulfides in Martian meteorite ALH84001 provides minimal evidence for microbial activity. Some magnetites resemble those formed by magnetotactic microorganisms but cubic crystals <50 nm in size and elongated grains <25 nm long are too small to be single-domain magnets and are probably abiogenic. Magnetites with shapes that are clearly unique to magnetotactic bacteria appear to be absent in ALH84001. Magnetosomes have not been reported in plutonic rocks and are unlikely to have been transported in fluids through fractures and uniformly deposited where abiogenic magnetite was forming epitaxially on carbonate. Submicrometer sulfides and magnetites probably formed during shock heating. Carbonates have correlated variations in Ca, Mg, and 18O/16O, magnetite-rich rims, and they appear to be embedded in pyroxene and plagiociase glass. Carbonates with these features have not been identified in carbonaceous chondrites and terrestrial rocks, suggesting that the ALH84001 carbonates have a unique origin. Carbonates and hydrated minerals in ALH84001, like secondary phases in other Martian meteorites, have O and H isotopic ratios favoring formation from fluids that exchanged with the Martian atmosphere. I propose that carbonates originally formed in ALH84001 from aqueous fluids and were subsequently shock heated and vaporized. The original carbonates were probably dolomite-magnesite-siderite assemblages that formed in pores at interstitial sites with minor sulfate, chloride, and phyllosilicates. These phases, like many other volatile-rich phases in Martian meteorites, may have formed as evaporate deposits from intermittent floods.
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Affiliation(s)
- E R Scott
- Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, USA.
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11
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Abstract
Fayalite grains in chondrules in the oxidized, aqueously altered CV3 chondrite Mokoia have large excesses of radiogenic chromium-53. These excesses indicate the in situ decay of short-lived manganese-53 (half-life = 3.7 million years) and define an initial 53Mn/55Mn ratio of 2.32 (+/-0.18) x 10(-6). This ratio is comparable to values for carbonates in CI and CM chondrites and for several classes of differentiated meteorites. Mokoia fayalites formed 7 to 16 million years after Allende calcium-aluminum-rich inclusions, during hydrothermal activity on a geologically active asteroid after chondritic components had ceased forming in the solar nebula.
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Affiliation(s)
- I D Hutcheon
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94551, USA
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12
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Scott ER, Krot AN, Yamaguchi A. Carbonates in fractures of Martian meteorite Allan Hills 84001: petrologic evidence for impact origin. Meteorit Planet Sci 1998; 33:709-719. [PMID: 11543072 DOI: 10.1111/j.1945-5100.1998.tb01677.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Carbonates in Martian meteorite Allan Hills 84001 occur as grains on pyroxene grain boundaries, in crushed zones, and as disks, veins, and irregularly shaped grains in healed pyroxene fractures. Some carbonate disks have tapered Mg-rich edges and are accompanied by smaller, thinner and relatively homogeneous, magnesite microdisks. Except for the microdisks, all types of carbonate grains show the same unique chemical zoning pattern on MgCO3-FeCO3-CaCO3 plots. This chemical characteristic and the close spatial association of diverse carbonate types show that all carbonates formed by a similar process. The heterogeneous distribution of carbonates in fractures, tapered shapes of some disks, and the localized occurrence of Mg-rich microdisks appear to be incompatible with growth from an externally derived CO2-rich fluid that changed in composition over time. These features suggest instead that the fractures were closed as carbonates grew from an internally derived fluid and that the microdisks formed from a residual Mg-rich fluid that was squeezed along fractures. Carbonate in pyroxene fractures is most abundant near grains of plagioclase glass that are located on pyroxene grain boundaries and commonly contain major or minor amounts of carbonate. We infer that carbonates in fractures formed from grain boundary carbonates associated with plagiociase that were melted by impact and dispersed into the surrounding fractured pyroxene. Carbonates in fractures, which include those studied by McKay et al. (1996), could not have formed at low temperatures and preserved mineralogical evidence for Martian organisms.
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Affiliation(s)
- E R Scott
- Hawai'i Institute of Geophysics and Planetology, University of Hawai'i at Manoa, Honolulu 96822, USA.
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13
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Abstract
The meteorite ALH84001--a shocked igneous rock of probable martian origin-contains chemically and isotopically heterogeneous carbonate globules, associated with which are organic and inorganic structures that have been interpreted as possible fossil remains of ancient martian biota. A critical assumption underlying this suggestion is that the carbonates formed from low-temperature fluids penetrating the cracks and voids of the host rock. Here we report petrological studies of ALH84001 which investigate the effects of shock on the various mineralogical components of the rock. We find that carbonate, plagioclase and silica were melted and partly redistributed by the same shock event responsible for the intense local crushing of pyroxene in the meteorite. Texture and compositional data show that, during the period of shock decompression, monomineralic melts were injected into pyroxene fractures that were subsequently cooled and resealed within seconds. Our results therefore suggest that the carbonates in ALH84001 could not have formed at low temperatures, but instead crystallized from shock-melted material; this conclusion weakens significantly the arguments that these carbonates could host the fossilized remnants of biogenic activity.
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Affiliation(s)
- E R Scott
- Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu 96822, USA.
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14
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Abstract
Physiological structures associated with iontophoretic paths in hairless mouse skin and two cultured skin models ("EpiDerm" by Mattek, Corp., and "SKIN2" by Advanced Tissue Sciences, Inc.) are reported. Visualization of ionic paths at current densities between 20 and 100 microA/ cm2 is accomplished by the counterdirectional transport of Fe(CN)6(4-) and Fe3+, resulting in the controlled precipitation of colloidal Prussian blue, Fe4[Fe(CN)6]3, at sites of high ionic conductivity. Examination of the Fe4[Fe(CN)6]3-stained tissues using optical microscopy allows unequivocal assignment of iontophoretic paths to physiological structures in the stratum corneum. Deposition of Fe4[Fe(CN)6]3 occurs exclusively at hair follicles in hairless mouse skin, indicating that these appendages provide highly conductive porous paths during iontophoresis. In contrast, the counterdirectional transport of Fe(CN)6(4-) and Fe3+ across cultured skin models, which lack appendages, results in the deposition of Fe4-[Fe(CN)6]3 along the boundaries of corneocytes. This observation suggests that paracellular iontophoretic transport through lipid bilayer regions is the predominant transport path in the absence of low-resistance pores.
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Affiliation(s)
- R D Lee
- Department of Chemistry, University of Utah, Salt Lake City 84112, USA
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15
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Abstract
Scanning electrochemical microscopy (SECM) was used to image spatial variations in the molecular flux of Fe(CN)6(-4) across excised hairless and nude mouse skin. The SECM response is specific to electroactive molecules, allowing selective imaging of the flux of Fe(CN)6(-4) in multicomponent ionic solutions. Quantitative SECM image analysis demonstrated that 40% to 60% of the total Fe(CN)6(-4) flux occurred through appendages in the skin. SECM analysis of skin samples exposed to a known transport enhancer, sodium dodecylsulfate, indicated that the increase in the ion transport rate occurred exclusively in nonporous skin tissue.
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Affiliation(s)
- E R Scott
- Medtronic, Inc., Brooklyn Center, Minnesota
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16
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Abstract
Two methods are reported that allow visualization of high conductance paths in skin at current densities typically used during clinical iontophoretic drug delivery (10-200 microA/cm2). In the first method, the counter-directional iontophoretic transport of Fe(CN)6(4-) and Fe3+ across skin results in the precipitation of colloidal prussian blue, Fe4[Fe(CN)6]3, at sites of high iontophoretic flux. The appearance of localized deposits of Fe4[Fe(CN)6]3 is recorded by video microscopy and used to document the activation of low-resistance paths. In the second method, the ionic flux of Fe(CN)6(4-) through pores is directly imaged by scanning electrochemical microscopy (SECM). Both methods demonstrate that the iontophoretic flux across skin is highly localized. Activation of low-resistance pores in hairless mouse skin is shown to occur during iontophoresis. The spatial density of current carrying pores increases from 0 to 100-600 pores/cm2 during the first 30-60 min of iontophoresis. At longer times, the active pore density approaches a quasi-steady-state value that is proportional to the applied current density. The total conductance of the skin is proportional to the number of pores, consistent with a model of conduction in skin that is comprised of low-resistivity pores in parallel with a high-resistivity bulk phase. The contribution of pores to the total skin conductance during iontophoresis increases from an initial value of 0-5% to a quasi-steady-state value of 50-95%.
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Affiliation(s)
- E R Scott
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis 55455
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17
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Scott ER, White HS, Phipps JB. Iontophoretic transport through porous membranes using scanning electrochemical microscopy: application to in vitro studies of ion fluxes through skin. Anal Chem 1993; 65:1537-45. [PMID: 8328671 DOI: 10.1021/ac00059a010] [Citation(s) in RCA: 119] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Scanning electrochemical microscopy (SECM) is used to map localized iontophoretic fluxes of electroactive species through porous membranes. A method is described that allows both the rate of transport of species from a microscopic pore and the pore's diameter to be measured. SECM images and analyses of synthetic porous membranes (track-etched polycarbonate and mica membranes) and hairless mouse skin are reported. Preliminary analysis of SECM images of the mouse skin indicates that a significant percentage of the iontophoretic flux occurs through pores associated with hair follicles.
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Affiliation(s)
- E R Scott
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis 55455
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18
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Margolick JB, Scott ER, Chadwick KR, Shapiro HM, Hetzel AD, Smith SJ, Vogt RF. Comparison of lymphocyte immunophenotypes obtained simultaneously from two different data acquisition and analysis systems on the same flow cytometer. Cytometry 1992; 13:198-203. [PMID: 1547669 DOI: 10.1002/cyto.990130215] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Immunophenotyping of different lymphocyte populations was carried out in parallel on 113 consecutively received specimens of human peripheral blood using 2 different data acquisition and analysis systems (EPICS C and 4Cyte-Acmecyte) on the same flow cytometer (EPICS C). The phenotypes analyzed were CD3+, CD4+, CD8+ CD56+ CD16+ CD3-, TCR-gamma delta+ CD8-, and TCR-gamma delta+ CD8+. Both HIV- and HIV+ specimens were used for this study, including some with CD4 levels as low as 2% of all lymphocytes. Despite differences in gating procedures and shapes of bitmap (rectilinear vs. "amorphous"), the 2 methods agreed to within 2% positive cells in 97% of the cases. Although some statistically significant biases in the methods were observed, these were small and not biologically important. We conclude that both methods of data acquisition and analysis, as employed by experienced operators on the EPICS C flow cytometer, gave essentially equivalent results for lymphocyte sub-populations in peripheral blood preparations.
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Affiliation(s)
- J B Margolick
- Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland 21205
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19
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Margolick JB, Scott ER, Odaka N, Saah AJ. Flow cytometric analysis of gamma delta T cells and natural killer cells in HIV-1 infection. Clin Immunol Immunopathol 1991; 58:126-38. [PMID: 1824568 DOI: 10.1016/0090-1229(91)90154-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have previously shown that HIV-1 seropositivity is associated with an increase in the difference between the number of CD3+ lymphocytes and the total number of CD4+ and CD8+ lymphocytes [CD3 - (CD4 + CD8)] among peripheral blood lymphocytes (PBL). To investigate the cellular basis of this increase, PBL from seronegative (SN) and AIDS-free seropositive (SP) homosexual men and intravenous drug users were analyzed by two-color flow cytometry. Results showed that SP compared to SN manifested the expected elevation in calculated [CD3 - (CD4 + CD8)] cells (87 vs 28 cells/mm3; P less than 0.001). Only small differences in lymphocyte populations that could contribute to this increase were observed, namely lymphocytes expressing the CD3+CD4-CD8-phenotype (67 vs 56 cells/mm3; P greater than 0.10) or the CD8dim phenotype (135 vs 142 cells/mm3; P greater than 0.10). However, SP had significantly lower numbers of cells expressing the CD56+CD3- phenotype characteristic of natural killer cells (81 vs 170 cells/mm3; P less than 0.001) and significantly higher numbers of T cells expressing the gamma delta T cell receptor (TCR) (81 vs 62 cells/mm3; P = 0.10). The latter difference was primarily due to higher numbers of cells coexpressing gamma delta-TCR and low levels of CD8 (27 vs 15 cells/mm3; P = 0.009). These data suggest that HIV-1 seropositivity is associated with low numbers of natural killer cells and high numbers of CD8+ gamma delta-TCR lymphocytes. Changes in these populations may reflect altered host defense against HIV-1 or altered T cell kinetics in the presence of HIV-1 infection.
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Affiliation(s)
- J B Margolick
- Department of Environmental Health Sciences, Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland 21205
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20
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Margolick JB, McArthur JC, Scott ER, McArthur JH, Cohn S, Farzadegan H, Polk BF. Flow cytometric quantitation of T cell phenotypes in cerebrospinal fluid and peripheral blood of homosexual men with and without antibodies to human immunodeficiency virus, type I. J Neuroimmunol 1988; 20:73-81. [PMID: 3263391 DOI: 10.1016/0165-5728(88)90116-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [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: 01/05/2023]
Abstract
Two-color flow cytometry was used to analyze T cell subsets (total (CD3), helper-inducer (CD4), and suppressor-cytotoxic (CD8] in paired specimens of cerebrospinal fluid (CSF) and peripheral blood of 66 homosexual men, including 62 with antibodies to human immunodeficiency virus, type 1 (HIV-1). With the exception of one traumatic specimen, all of the CSF specimens, 52 of which had less than or equal to 5 lymphocytes/mm3, were evaluated fully, with the number of lymphocytes counted for each antibody ranging from 200 to 2933 (mean = 1129). Proportions of CD3, CD4, and CD8 lymphocytes in CSF were very highly correlated with the proportions of these cells in the peripheral blood (r = 0.87, 0.96, and 0.94, respectively), as was the CD4/CD8 ratio (r = 0.98). These strong correlations were present in each of seven subgroups of study subjects defined on the basis of detailed neurologic examination, neuropsychological testing, and the presence or absence of antibodies to HIV-1. In the population studied, T cell phenotypes in CSF as analyzed by two-color flow cytometry were largely determined by the corresponding proportions in the peripheral blood.
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Affiliation(s)
- J B Margolick
- Department of Environmental Health Sciences, Johns Hopkins Medical Institutions, Baltimore, MD 21205
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Williams RC, Leone CW, Jeffcoat MK, Scott ER, Goldhaber P. Tetracycline treatment of periodontal disease in the beagle dog. I. Clinical and radiographic course over 12 months-maximal effect on rate of alveolar bone loss. J Periodontal Res 1981; 16:659-65. [PMID: 6460864 DOI: 10.1111/j.1600-0765.1981.tb01004.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Scott ER. A national association. Dent Tech 1966; 19:106-8 passim. [PMID: 5224989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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