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Jang LW, Razu ME, Jensen EC, Jiao H, Kim J. A fully automated microfluidic micellar electrokinetic chromatography analyzer for organic compound detection. LAB ON A CHIP 2016; 16:3558-3564. [PMID: 27507322 DOI: 10.1039/c6lc00790b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An integrated microfluidic chemical analyzer utilizing micellar electrokinetic chromatography (MEKC) is developed using a pneumatically actuated Lifting-Gate microvalve array and a capillary zone electrophoresis (CZE) chip. Each of the necessary liquid handling processes such as metering, mixing, transferring, and washing steps are performed autonomously by the microvalve array. In addition, a method is presented for automated washing of the high resistance CZE channel for device reuse and periodic automated in situ analyses. To demonstrate the functionality of this MEKC platform, amino acids and thiols are labeled and efficiently separated via a fully automated program. Reproducibility of the automated programs for sample labeling and periodic in situ MEKC analysis was tested and found to be equivalent to conventional sample processing techniques for capillary electrophoresis analysis. This platform enables simple, portable, and automated chemical compound analysis which can be used in challenging environments.
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Affiliation(s)
- Lee-Woon Jang
- Department of Mechanical Engineering, Texas Tech University, Lubbock, TX79409, USA.
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2
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Kim J, Jensen EC, Stockton AM, Mathies RA. Universal Microfluidic Automaton for Autonomous Sample Processing: Application to the Mars Organic Analyzer. Anal Chem 2013; 85:7682-8. [DOI: 10.1021/ac303767m] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Jungkyu Kim
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United
States
| | - Erik C. Jensen
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United
States
| | - Amanda M. Stockton
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United
States
| | - Richard A. Mathies
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United
States
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Gibson LR, Branagan SP, Bohn PW. Convective delivery of electroactive species to annular nanoband electrodes embedded in nanocapillary-array membranes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:90-97. [PMID: 22907773 DOI: 10.1002/smll.201200237] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 06/15/2012] [Indexed: 06/01/2023]
Abstract
Significant technological drivers motivate interest in the use of reaction sites embedded within nanometer-scale channels, and an important class of these structures is realized by an embedded annular nanoband electrode (EANE) in a cylindrical nanochannel. In this structure, the convective delivery of electroactive species to the nanoelectrode is tightly coupled to the electrochemical overpotential via electroosmotic flow. Simulation results indicate that EANE arrays significantly outperform comparable microband electrode/microchannel structures, producing higher conversion efficiencies at low Peclet number. The results of this in-depth analysis are useful in assessing possible implementation of the EANE geometry for a wide range of electrochemical targets within microscale total analysis systems.
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Affiliation(s)
- Larry R Gibson
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
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4
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Branagan SP, Contento NM, Bohn PW. Enhanced mass transport of electroactive species to annular nanoband electrodes embedded in nanocapillary array membranes. J Am Chem Soc 2012; 134:8617-24. [PMID: 22506659 DOI: 10.1021/ja3017158] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electroosmotic flow (EOF) is used to enhance the delivery of Fe(CN)(6)(4-)/Fe(CN)(6)(3-) to an annular nanoband electrode embedded in a nanocapillary array membrane, as a route to high efficiency electrochemical conversions. Multilayer Au/polymer/Au/polymer membranes are perforated with 10(2)-10(3) cylindrical nanochannels by focused ion beam (FIB) milling and subsequently sandwiched between two axially separated microchannels, producing a structure in which transport and electron transfer reactions are tightly coupled. The middle Au layer, which contacts the fluid only at the center of each nanochannel, serves as a working electrode to form an array of embedded annular nanoband electrodes (EANEs), at which sufficient overpotential drives highly efficient electrochemical processes. Simultaneously, the electric field established between the EANE and the QRE (>10(3) V cm(-1)) drives electro-osmotic flow (EOF) in the nanochannels, improving reagent delivery rate. EOF is found to enhance the steady-state current by >10× over a comparable structure without convective transport. Similarly, the conversion efficiency is improved by approximately 10-fold compared to a comparable microfluidic structure. Experimental data agree with finite element simulations, further illustrating the unique electrochemical and transport behavior of these nanoscale embedded electrode arrays. Optimizing the present structure may be useful for combinatorial processing of on-chip sample delivery with electrochemical conversion; a proof of concept experiment, involving the generation of dissolved hydrogen in situ via electrolysis, is described.
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Affiliation(s)
- Sean P Branagan
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Indiana 46556, United States
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5
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Escobedo C, Brolo AG, Gordon R, Sinton D. Optofluidic concentration: plasmonic nanostructure as concentrator and sensor. NANO LETTERS 2012; 12:1592-6. [PMID: 22352888 DOI: 10.1021/nl204504s] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The integration of fluidics and optics, as in flow-through nanohole arrays, has enabled increased transport of analytes to sensing surfaces. Limits of detection, however, are fundamentally limited by local analyte concentration. We employ the nanohole array geometry and the conducting nature of the film to actively concentrate analyte within the sensor. We achieve 180-fold enrichment of a dye, and 100-fold enrichment and simultaneous sensing of a protein in less than 1 min. The method presents opportunities for an order of magnitude increase in sensing speed and 2 orders of magnitude improvement in limit of detection.
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Affiliation(s)
- Carlos Escobedo
- Department of Biosystems Science and Engineering, Bio Engineering Laboratory, ETH Zurich, Mattenstrasse 26, CH-4058 Basel, Switzerland
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6
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Sheng Y, Bowser MT. Size selective DNA transport through a nanoporous membrane in a PDMS microfluidic device. Analyst 2012; 137:1144-51. [PMID: 22262059 DOI: 10.1039/c2an15966j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A microfluidic counter current dialysis device for size based purification of DNA is described. The device consists of two polydimethylsiloxane (PDMS) channels separated by a track etched polycarbonate membrane with a 50 nm pore size. Recovery of fluorescein across the membrane was compared with 10 and 80 nucleotide (nt) ssDNA to characterize the device. Recovery of all three analytes improved with decreasing flow rate. Size selectivity was observed. Greater than 2-fold selectivity between 10 nt and 80 nt ssDNA was observed at linear velocities less than 3mm s(-1). Increasing the ionic strength of the buffer increased transport across the membrane. Recovery of 80 nt ssDNA increased over 4-fold by adding 30 mM NaCl to the buffer. The effect was size dependent as 10 nt showed a smaller increase while the recovery of fluorescein was largely unaffected by increasing the ionic strength of the buffer.
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Affiliation(s)
- Yixiao Sheng
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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7
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Piruska A, Branagan SP, Minnis AB, Wang Z, Cropek DM, Sweedler JV, Bohn PW. Electrokinetic control of fluid transport in gold-coated nanocapillary array membranes in hybrid nanofluidic-microfluidic devices. LAB ON A CHIP 2010; 10:1237-1244. [PMID: 20445875 DOI: 10.1039/b924164g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The introduction of metallic elements into microfluidic devices that support electrokinetic transport creates several fundamental issues relative to the high conductivity of the metal, which can act as a current shunt, causing profound effects on the transport process. Here we examine the use of Au-coated nanocapillary array membranes (Au NCAMs) as electrically addressable fluid control elements in multi-layer microfluidic architectures. Three alternative methods for fluid injection across Au NCAMs are presented: electrokinetic injection across NCAMs with Au coated on one side (asymmetric NCAM), electrokinetic injection across NCAMs with an embedded Au layer (symmetric NCAM), and field-free electroosmotic flow (EOF) pumping across either type of Au NCAM. Injection efficiency across asymmetric NCAMs depends on the orientation of the asymmetric membrane relative to the driving potential. Efficient injections are enabled when the Au coating is on the receiving side of the membrane, however, some distortion of the injected volume element is observed, especially with large injection potentials. These results for asymmetric membranes agree qualitatively with two-dimensional numerical simulations of injections across a single slit pore, which suggest that the direction-selective transport behavior is related to electrophoretic transport of the anionic fluorescein probe. Reproducible, high quality injections are also achieved in symmetric Au NCAMs having an embedded gold nanoband region within the nanopores. Nanoband Au NCAMs are excellent candidates for a range of applications, including high efficiency electrochemical sensing, electrochemically catalyzed conversion or pretreatment and label free sensing utilizing extraordinary optical transmission. EOF pumping could be an alternative to electrokinetic injections in some applications, however, this approach is only useful for relatively large pore sizes (>400 nm) and presents considerably worse sample spreading via Taylor dispersion.
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Affiliation(s)
- Aigars Piruska
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
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Kuang C, Wang G. A novel far-field nanoscopic velocimetry for nanofluidics. LAB ON A CHIP 2010; 10:240-245. [PMID: 20066253 DOI: 10.1039/b917584a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
For the first time we have been able to measure the flow velocity profile for nanofluidics with a spatial resolution better than 70 nm. Due to the diffraction resolution barrier, traditional optical methods have so far failed in measuring the velocity profile in a nanocapillary or a closed nanochannel without an opened sidewall. A novel optical point measurement method is presented which applies stimulated emission depletion (STED) microscopy to laser induced fluorescence photobleaching anemometer (LIFPA) techniques to measure flow velocity. Herein we demonstrate this far-field nanoscopic velocimetry method by measuring the velocity profile in a nanocapillary with an inner diameter of 360 nm. The closest measuring point to the wall is about 35 nm. This method opens up a new class of functional measuring techniques for nanofluidics and for nanoscale flows from the wall.
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Affiliation(s)
- Cuifang Kuang
- Department of Mechanical Engineering & Biomedical Engineering Program, University of South Carolina, Columbia, SC 29208, USA
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9
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Piruska A, Gong M, Sweedler JV, Bohn PW. Nanofluidics in chemical analysis. Chem Soc Rev 2010; 39:1060-72. [DOI: 10.1039/b900409m] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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10
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Perdue RK, Laws DR, Hlushkou D, Tallarek U, Crooks RM. Bipolar Electrode Focusing: The Effect of Current and Electric Field on Concentration Enrichment. Anal Chem 2009; 81:10149-55. [DOI: 10.1021/ac901913r] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robbyn K. Perdue
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Derek R. Laws
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Dzmitry Hlushkou
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Richard M. Crooks
- Department of Chemistry and Biochemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Hlushkou D, Perdue RK, Dhopeshwarkar R, Crooks RM, Tallarek U. Electric field gradient focusing in microchannels with embedded bipolar electrode. LAB ON A CHIP 2009; 9:1903-1913. [PMID: 19532966 DOI: 10.1039/b822404h] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The complex interplay of electrophoretic, electroosmotic, bulk convective, and diffusive mass/charge transport in a hybrid poly(dimethylsiloxane) (PDMS)/glass microchannel with embedded floating electrode is analyzed. The thin floating electrode attached locally to the wall of the straight microchannel results in a redistribution of local field strength after the application of an external electric field. Together with bulk convection based on cathodic electroosmotic flow, an extended field gradient is formed in the anodic microchannel segment. It imparts a spatially dependent electrophoretic force on charged analytes and, in combination with the bulk convection, results in an electric field gradient focusing at analyte-specific positions. Analyte concentration in the enriched zone approaches a maximum value which is independent of its concentration in the supplying reservoirs. A simple approach is shown to unify the temporal behavior of the concentration factors under general conditions.
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Affiliation(s)
- Dzmitry Hlushkou
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032, Marburg, Germany
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12
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Kim BY, Yang J, Gong M, Flachsbart BR, Shannon MA, Bohn PW, Sweedler JV. Multidimensional separation of chiral amino acid mixtures in a multilayered three-dimensional hybrid microfluidic/nanofluidic device. Anal Chem 2009; 81:2715-22. [PMID: 19271741 DOI: 10.1021/ac802630p] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microscale total analysis systems (microTAS) allow high-throughput analyses by integrating multiple processes, parallelization, and automation. Here we combine unit operations of microTAS to create a device that can perform multidimensional separations using a three-dimensional hybrid microfluidic/nanofluidic device composed of alternating layers of patterned poly(methyl methacrylate) and nanocapillary array membranes constructed from nuclear track-etched polycarbonate. Two consecutive electrophoretic separations are performed, the first being an achiral separation followed by a chiral separation of a selected analyte band. Separation conditions are optimized for a racemic mixture of fluorescein-isothiocyanate-labeled amino acids, serine and aspartic acid, chosen because there are endogenous D-forms of these amino acids in animals. The chiral separation is implemented using micellar electrokinetic chromatography using beta-cyclodextrin as the chiral selector and sodium taurocholate as the micelle-forming agent. Analyte separation is monitored by dual-beam laser-induced fluorescence detection. After separation in the first electrophoretic channel, the preselected analyte is sampled by the second-stage separation using an automated collection sequence with a zero-crossing algorithm. The controlled fluidic environment inherent to the three-dimensional architecture enables a series of separations in varying fluidic environments and allows sample stacking via different background electrolyte pH conditions. The ability to interface sequential separations, selected analyte capture, and other fluidic manipulations in the third dimension significantly improves the functionality of multilayer microfluidic devices.
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Affiliation(s)
- Bo Young Kim
- Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Chow KF, Mavré F, Crooks JA, Chang BY, Crooks RM. A Large-Scale, Wireless Electrochemical Bipolar Electrode Microarray. J Am Chem Soc 2009; 131:8364-5. [DOI: 10.1021/ja902683f] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kwok-Fan Chow
- Department of Chemistry and Biochemistry, Center for Electrochemistry, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165
| | - François Mavré
- Department of Chemistry and Biochemistry, Center for Electrochemistry, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165
| | - John A. Crooks
- Department of Chemistry and Biochemistry, Center for Electrochemistry, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165
| | - Byoung-Yong Chang
- Department of Chemistry and Biochemistry, Center for Electrochemistry, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165
| | - Richard M. Crooks
- Department of Chemistry and Biochemistry, Center for Electrochemistry, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165
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King TL, Gatimu EN, Bohn PW. Single nanopore transport of synthetic and biological polyelectrolytes in three-dimensional hybrid microfluidicnanofluidic devices. BIOMICROFLUIDICS 2009; 3:12004. [PMID: 19693385 PMCID: PMC2717587 DOI: 10.1063/1.3059546] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 12/08/2008] [Indexed: 05/28/2023]
Abstract
This paper presents a study of electrokinetic transport in single nanopores integrated into vertically stacked three-dimensional hybrid microfluidicnanofluidic structures. In these devices, single nanopores, created by focused ion beam (FIB) milling in thin polymer films, provide fluidic connection between two vertically separated, perpendicular microfluidic channels. Experiments address both systems in which the nanoporous membrane is composed of the same (homojunction) or different (heterojunction) polymer as the microfluidic channels. These devices are then used to study the electrokinetic transport properties of synthetic (i.e., polystyrene sulfonate and polyallylamine) and biological (i.e., DNA) polyelectrolytes across these nanopores using both electrical current measurements and confocal microscopy. Both optical and electrical measurements indicate that electro-osmotic transport is predominant over electrophoresis in single nanopores with d>180 nm, consistent with results obtained under similar conditions for nanocapillary array membranes.
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Wang Z, King TL, Branagan SP, Bohn PW. Enzymatic activity of surface-immobilized horseradish peroxidase confined to micrometer- to nanometer-scale structures in nanocapillary array membranes. Analyst 2009; 134:851-9. [DOI: 10.1039/b815590a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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