1
|
Moon S, Hijikata Y, Irle S. Structural transformations of graphene exposed to nitrogen plasma: quantum chemical molecular dynamics simulations. Phys Chem Chem Phys 2019; 21:12112-12120. [PMID: 30888388 DOI: 10.1039/c8cp06159a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nitrogen-doped graphene (N-graphene) has been intensively studied for tailoring the electronic property of the graphene, because different nitrogen configurations influence the electronic properties of N-graphene in different ways. However, atomically precise control of the nitrogen configurations during the doping process remains a challenge in the synthesis of N-graphene. Moreover, additional structural transformations of the graphene carbon network structure as a side-effect of plasma doping are little understood and are as of yet uncontrollable. Therefore, we theoretically investigated the nitrogen doping process of graphene for a range of nitrogen atom incident kinetic energies in nonequilibrium quantum chemical molecular dynamics (QM/MD) simulations. We observed and characterized prominent configurations of N-containing graphene. In analogy to similar, earlier studies of graphene plasma hydrogenation, we observed an Eley-Rideal associative desorption mechanism during the graphene plasma nitrogenation, producing molecular nitrogen. Especially for graphitic-N (Gr-N) and Stone-Wales-defect-N (SW-N) configurations, which are frequently observed in experimental studies, we discovered two typical chemical reaction mechanisms which were well categorized by two key processes: adsorption of primary nitrogen dopant and collision with a secondary nitrogen dopant. We discussed effects of the incident nitrogen energy on the formation mechanism, and propose a method to generate of Gr-N and SW-N configurations selectively by tuning the conditions with respect to the two key formation processes.
Collapse
Affiliation(s)
- Seokjin Moon
- Department of Chemistry, Seoul National University, Seoul 151-747, Korea
| | - Yuh Hijikata
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Department of Chemistry & Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
| | - Stephan Irle
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Department of Chemistry & Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan. and Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6493, USA.
| |
Collapse
|
2
|
Kimura R, Hijikata Y, Eveleens CA, Page AJ, Irle S. Chiral-selective etching effects on carbon nanotube growth at edge carbon atoms. J Comput Chem 2019; 40:375-380. [PMID: 30548651 DOI: 10.1002/jcc.25610] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/30/2018] [Accepted: 09/05/2018] [Indexed: 11/08/2022]
Abstract
Chemical vapor deposition (CVD) utilizing metal cluster nanoparticle catalysts is commonly used to synthesize carbon nanotubes (CNT), with oxygen-containing species such as water or alcohol included in the feedstock for enhanced yield. However, the etching effect of these additives on the growth mechanism has rarely been investigated, despite evidence suggesting that etching potentially affects the chirality distribution of product CNTs. We used quantum chemical methods to study how water-based etchant radicals (OH and H) may enhance the chiral selectivity during CVD growth using CNT cap models. Chemical reactivities of the caps with the etchant radicals were evaluated using density functional theory (DFT). It was found that the reactivities on the cap edges correlate with the chirality of the caps. These results suggest that proper selection of etchant species can provide opportunities for selective chirality control of the product CNTs. © 2018 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Ryuto Kimura
- Department of Chemistry, School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Yuh Hijikata
- The institute names serve in place of Department information, Institute of Transformative Bio-Molecules and Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Clothilde A Eveleens
- The institute names serve in place of Department information, Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan, 2308, Australia
| | - Alister J Page
- The institute names serve in place of Department information, Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan, 2308, Australia
| | - Stephan Irle
- Department of Chemistry, School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan.,Computational Sciences and Engineering Division & Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831-6493
| |
Collapse
|
3
|
Mitchell I, Irle S, Page AJ. Inducing regioselective chemical reactivity in graphene with alkali metal intercalation. Phys Chem Chem Phys 2018; 20:19987-19994. [PMID: 30022198 DOI: 10.1039/c8cp02903b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
First principles calculations demonstrate that alkali metal atoms, intercalated between metal substrates and adsorbed graphene monolayers, induce localised regions of increased reactivity. The extent of this localisation is proportional to the size of the alkali atom and the strength of the graphene-substrate interaction. Thus, larger alkali atoms are more effective (e.g. K > Na > Li), as are stronger-interacting substrates (e.g. Ni > Cu). Despite the electropositivity of these alkali metal adsorbates, analysis of charge transfer between the alkali metal, the substrate and the adsorbed graphene layer indicates that charge transfer does not give rise to the observed regioselective reactivity. Instead, the increased reactivity induced in the graphene structure is shown to arise from the geometrical distortion of the graphene layer imposed by the intercalated adsorbed atom. We show that this strategy can be used with arbitrary adsorbates and substrate defects, provided such structures are stable, towards controlling the mesoscale patterning and chemical functionalisation of graphene structures.
Collapse
Affiliation(s)
- Izaac Mitchell
- Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan, 2308 NSW, Australia.
| | | | | |
Collapse
|
4
|
Shao J, Yuan L, Hu X, Wu Y, Zhang Z. The effect of nano confinement on the C-h activation and its corresponding structure-activity relationship. Sci Rep 2014; 4:7225. [PMID: 25428459 PMCID: PMC4245521 DOI: 10.1038/srep07225] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 11/11/2014] [Indexed: 11/15/2022] Open
Abstract
The C–H activation of methane, ethane, and t-butane on inner and outer surfaces of nitrogen-doped carbon nanotube (NCNTs) are investigated using density functional theory. It includes NCNTs with different diameters, different N and O concentrations, and different types (armchair and zigzag). A universal structure-reactivity relationship is proposed to characterize the C–H activation occurring both on the inner and outer surfaces of the nano channel. The C–O bond distance, spin density and charge carried by active oxygen are found to be highly related to the C–H activation barriers. Based on these theoretical results, some useful strategies are suggested to guide the rational design of more effective catalysts by nano channel confinement.
Collapse
Affiliation(s)
- Jing Shao
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
| | - Linghua Yuan
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
| | - Xingbang Hu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
| | - Youting Wu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
| | - Zhibing Zhang
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
| |
Collapse
|
5
|
Effect of confinement on the structure and energetics of Zundel cation present inside the hydrophobic carbon nanotubes: an ab initio study. Theor Chem Acc 2014. [DOI: 10.1007/s00214-014-1576-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
6
|
Kroes JMH, Pietrucci F, Curioni A, Andreoni W. Characterizing and Understanding Divalent Adsorbates on Carbon Nanotubes with Ab Initio and Classical Approaches: Size, Chirality, and Coverage Effects. J Chem Theory Comput 2014; 10:4672-83. [PMID: 26588158 DOI: 10.1021/ct500701n] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The study of oxygen chemisorption on single-walled carbon nanotubes generally relies on simple atomistic models and hence hampers the possibility to understand whether nanotube size or adduct concentration have a role in determining the surface-adsorbate interaction. Our large-scale DFT-based simulations show that structural and electronic properties as well as diffusion barriers strongly depend on both nanotube diameter and adsorbate concentration. Our atomistic models cover nanotube of different chirality with diameters from 0.6 to 1.5 nm and oxygen concentration from 0.1 to 1%. In particular, the tendency to cluster increases with concentration and stabilizes ether (ET) groups but affects hopping barriers only to a minor extent. Significant differences with graphene are found, also for 1.5 nm diameter nanotubes. Extension to species isoelectronic to oxygen reveals dissimilarities, and especially for sulfur that tends to form epoxides (EP), to diffuse more easily and to rapidly close the energy gap for increasing concentration. The relative ET-EP stability can be described in terms of the bare-bond curvature, a concentration-dependent chemical descriptor here introduced. Comparison of these DFT calculations-using different exchange-correlation functionals-and our additional investigation with a reactive force-field (ReaxFF) clarifies several similarities but also discrepancies between the predictions of the two schemes.
Collapse
Affiliation(s)
- Jaap M H Kroes
- Institut de Théorie des Phénomènes Physiques, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Fabio Pietrucci
- Institut de Théorie des Phénomènes Physiques, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | | | - Wanda Andreoni
- Institut de Théorie des Phénomènes Physiques, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| |
Collapse
|
7
|
Rance GA, Khlobystov AN. The effects of interactions between proline and carbon nanostructures on organocatalysis in the Hajos-Parrish-Eder-Sauer-Wiechert reaction. NANOSCALE 2014; 6:11141-11146. [PMID: 25213437 DOI: 10.1039/c4nr04009k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The non-covalent interactions of S-(-)-proline with the surfaces of carbon nanostructures (fullerene, nanotubes and graphite) change the nucleophilic-electrophilic and acid-base properties of the amino acid, thus tuning its activity and selectivity in the organocatalytic Hajos-Parrish-Eder-Sauer-Wiechert (HPESW) reaction. Whilst our spectroscopy and microscopy measurements show no permanent covalent bonding between S-(-)-proline and carbon nanostructures, a systematic investigation of the catalytic activity and selectivity of the organocatalyst in the HPESW reaction demonstrates a clear correlation between the pyramidalisation angle of carbon nanostructures and the catalytic properties of S-(-)-proline. Carbon nanostructures with larger pyramidalisation angles have a stronger interaction with the nitrogen atom lone pair of electrons of the organocatalyst, thereby simultaneously decreasing the nucleophilicity and increasing the acidity of the organocatalyst. These translate into lower conversion rates but higher selectivities towards the dehydrated product of Aldol addition.
Collapse
Affiliation(s)
- G A Rance
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | | |
Collapse
|
8
|
Recent applications of carbon nanotube sorbents in analytical chemistry. J Chromatogr A 2014; 1357:110-46. [DOI: 10.1016/j.chroma.2014.05.035] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 01/10/2023]
|
9
|
Page AJ, Chou CP, Pham BQ, Witek HA, Irle S, Morokuma K. Quantum chemical investigation of epoxide and ether groups in graphene oxide and their vibrational spectra. Phys Chem Chem Phys 2013; 15:3725-35. [PMID: 23388654 DOI: 10.1039/c3cp00094j] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a detailed analysis of the factors influencing the formation of epoxide and ether groups in graphene nanoflakes using conventional density functional theory (DFT), the density-functional tight-binding (DFTB) method, π-Hückel theory, and graph theoretical invariants. The relative thermodynamic stability associated with the chemisorption of oxygen atoms at various positions on hexagonal graphene flakes (HGFs) of D(6h)-symmetry is determined by two factors - viz. the disruption of the π-conjugation of the HGF and the geometrical deformation of the HGF structure. The thermodynamically most stable structure is achieved when the former factor is minimized, and the latter factor is simultaneously maximized. Infrared (IR) spectra computed using DFT and DFTB reveal a close correlation between the relative thermodynamic stabilities of the oxidized HGF structures and their IR spectral activities. The most stable oxidized structures exhibit significant IR activity between 600 and 1800 cm(-1), whereas less stable oxidized structures exhibit little to no activity in this region. In contrast, Raman spectra are found to be less informative in this respect.
Collapse
Affiliation(s)
- Alister J Page
- Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan
| | | | | | | | | | | |
Collapse
|
10
|
Fusaro M. Derivation of the linear relationship between SWCNTs functionalization energies and sidewall curvature. Struct Chem 2012. [DOI: 10.1007/s11224-012-0051-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
11
|
Addicoat MA, Page AJ, Brain ZE, Flack L, Morokuma K, Irle S. Optimization of a Genetic Algorithm for the Functionalization of Fullerenes. J Chem Theory Comput 2012; 8:1841-51. [DOI: 10.1021/ct300190u] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Matthew A. Addicoat
- Department
of Computer Science, Australian National University, ACT, 0200, Australia
- Department
of Chemistry, Graduate School of Science, Nagoya University, Nagoya 464-4602, Japan
| | - Alister J. Page
- Fukui Institute for Fundamental
Chemistry, Kyoto University, Kyoto 606-8103,
Japan
| | - Zoe E. Brain
- Department
of Computer Science, Australian National University, ACT, 0200, Australia
| | - Lloyd Flack
- Department
of Rheumatology, University of New South Wales, NSW, 2052, Australia
| | - Keiji Morokuma
- Fukui Institute for Fundamental
Chemistry, Kyoto University, Kyoto 606-8103,
Japan
- Cherry L. Emerson Center for
Scientic Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322,
United States
| | - Stephan Irle
- Department
of Chemistry, Graduate School of Science, Nagoya University, Nagoya 464-4602, Japan
| |
Collapse
|
12
|
Garcia-Borràs M, Romero-Rivera A, Osuna S, Luis JM, Swart M, Solà M. The Frozen Cage Model: A Computationally Low-Cost Tool for Predicting the Exohedral Regioselectivity of Cycloaddition Reactions Involving Endohedral Metallofullerenes. J Chem Theory Comput 2012; 8:1671-83. [DOI: 10.1021/ct300044x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Marc Garcia-Borràs
- Institut de Química Computacional
and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain
| | - Adrian Romero-Rivera
- Institut de Química Computacional
and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain
| | - Sílvia Osuna
- Department of Chemistry and
Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095, United
States
| | - Josep M. Luis
- Institut de Química Computacional
and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain
| | - Marcel Swart
- Institut de Química Computacional
and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, 08010 Barcelona, Catalonia, Spain
| | - Miquel Solà
- Institut de Química Computacional
and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain
| |
Collapse
|
13
|
Water molecule encapsulated in carbon nanotube model systems: effect of confinement and curvature. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1205-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
14
|
Yuan Q, Hu H, Gao J, Ding F, Liu Z, Yakobson BI. Upright Standing Graphene Formation on Substrates. J Am Chem Soc 2011; 133:16072-9. [DOI: 10.1021/ja2037854] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Qinghong Yuan
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, Hong Kong, China
| | - Hong Hu
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, Hong Kong, China
| | - Junfeng Gao
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, Hong Kong, China
| | - Feng Ding
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, Hong Kong, China
- ME&MS Department, Rice University, Houston, Texas 77005, United States
| | - Zhifeng Liu
- Department of Chemistry, The Chinese University of Hong Kong, Hong Kong, China
| | - Boris I. Yakobson
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, Hong Kong, China
- ME&MS Department, Rice University, Houston, Texas 77005, United States
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| |
Collapse
|
15
|
Gao X, Wang Y, Liu X, Chan TL, Irle S, Zhao Y, Zhang SB. Regioselectivity control of graphene functionalization by ripples. Phys Chem Chem Phys 2011; 13:19449-53. [DOI: 10.1039/c1cp22491c] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
16
|
Kazachkin D, Nishimura Y, Irle S, Morokuma K, Vidic RD, Borguet E. Interaction of acetone with single wall carbon nanotubes at cryogenic temperatures: a combined temperature programmed desorption and theoretical study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:7848-7856. [PMID: 18613702 DOI: 10.1021/la800030y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The interaction of acetone with single wall carbon nanotubes (SWCNTs) at low temperatures was studied by a combination of temperature programmed desorption (TPD) and dispersion-augmented density-functional-based tight binding (DFTB-D) theoretical simulations. On the basis of the results of the TPD study and theoretical simulations, the desorption peaks of acetone can be assigned to the following adsorption sites: (i) sites with energy of approximately 75 kJ mol (-1) ( T des approximately 300 K)endohedral sites of small diameter nanotubes ( approximately 7.7 A); (ii) sites with energy 40-68 kJ mol (-1) ( T des approximately 240 K)acetone adsorption on accessible interstitial, groove sites, and endohedral sites of larger nanotubes ( approximately 14 A); (iii) sites with energy 25-42 kJ mol (-1) ( T des approximately 140 K)acetone adsorption on external walls of SWCNTs and multilayer adsorption. Oxidatively purified SWCNTs have limited access to endohedral sites due to the presence of oxygen functionalities. Oxygen functionalities can be removed by annealing to elevated temperature (900 K) opening access to endohedral sites of nanotubes. Nonpurified, as-received SWCNTs are characterized by limited access for acetone to endohedral sites even after annealing to elevated temperatures (900 K). Annealing of both purified and as-produced SWCNTs to high temperatures (1400 K) leads to reduction of access for acetone molecules to endohedral sites of small nanotubes, probably due to defect self-healing and cap formation at the ends of SWCNTs. No chemical interaction between acetone and SWCNTs was detected for low temperature adsorption experiments. Theoretical simulations of acetone adsorption on finite pristine SWCNTs of different diameters suggest a clear relationship of the adsorption energy with tube sidewall curvature. Adsorption of acetone is due to dispersion forces, with its C-O bond either parallel to the surface or O pointing away from it. No significant charge transfer or polarization was found. Carbon black was used to model amorphous carbonaceous impurities present in as-produced SWCNTs. Desorption of acetone from carbon black revealed two peaks at approximately 140 and approximately 180-230 K, similar to two acetone desorption peaks from SWCNTs. The characteristic feature of acetone desorption from SWCNTs was peak at approximately 300 K that was not observed for carbon black. Care should be taken when assigning TPD peaks for molecules desorbing from carbon nanotubes as amorphous carbon can interfere.
Collapse
Affiliation(s)
- Dmitry Kazachkin
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | | | | | | | | | | |
Collapse
|
17
|
Balasubramanian K, Burghard M. Electrochemically functionalized carbon nanotubes for device applications. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b718262g] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
18
|
Horner D, Redfern P, Sternberg M, Zapol P, Curtiss L. Increased reactivity of single wall carbon nanotubes at carbon ad-dimer defect sites. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.10.079] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
19
|
|
20
|
|