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Author |
Chaves, A.; Farias, G.A.; Peeters, F.M.; Ferreira, R. |
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Title |
The Split-operator technique for the study of spinorial wavepacket dynamics |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Communications in computational physics |
Abbreviated Journal |
Commun Comput Phys |
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Volume |
17 |
Issue |
17 |
Pages |
850-866 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The split-operator technique for wave packet propagation in quantum systems is expanded here to the case of propagatingwave functions describing Schrodinger particles, namely, charge carriers in semiconductor nanostructures within the effective mass approximation, in the presence of Zeeman effect, as well as of Rashba and Dresselhaus spin-orbit interactions. We also demonstrate that simple modifications to the expanded technique allow us to calculate the time evolution of wave packets describing Dirac particles, which are relevant for the study of transport properties in graphene. |
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Wos |
000353695400010 |
Publication Date |
2015-03-24 |
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Series Issue |
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Edition |
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ISSN |
1815-2406;1991-7120; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.004 |
Times cited |
24 |
Open Access |
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Notes |
; The authors gratefully acknowledge fruitful discussions with J. M. Pereira Jr. and R. N. Costa Filho. This work was financially supported by CNPq through the INCT-NanoBioSimes and the Science Without Borders programs (contract 402955/ 2012-9), PRONEX/FUNCAP, CAPES, the Bilateral programme between Flanders and Brazil, and the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 2.004; 2015 IF: 1.943 |
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Call Number |
c:irua:126028 |
Serial |
3593 |
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Author |
da Costa, D.R.; Zarenia, M.; Chaves, A.; Farias, G.A.; Peeters, F.M. |
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Title |
Analytical study of the energy levels in bilayer graphene quantum dots |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Carbon |
Abbreviated Journal |
Carbon |
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Volume |
78 |
Issue |
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Pages |
392-400 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Using the four-band continuum model we derive a general expression for the infinite-mass boundary condition in bilayer graphene. Applying this new boundary condition we analytically calculate the confined states and the corresponding wave functions in a bilayer graphene quantum dot in the absence and presence of a perpendicular magnetic field. Our results for the energy spectrum show an energy gap between the electron and hole states at small magnetic fields. Furthermore the electron (e) and hole (h) energy levels corresponding to the K and K' valleys exhibit the E-K(e(h)) (m) = E-K'(e(h)) (m) symmetry, where m is the angular momentum quantum number. (C) 2014 Elsevier Ltd. All rights reserved. |
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Place of Publication |
Oxford |
Editor |
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Wos |
000341463900042 |
Publication Date |
2014-07-16 |
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Series Issue |
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Edition |
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ISSN |
0008-6223; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.337 |
Times cited |
35 |
Open Access |
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Notes |
; This work was financially supported by CNPq, under contract NanoBioEstruturas 555183/2005-0, PRONEX/FUNCAP, CAPES Foundation under the process number BEX 7178/13-1, the Flemish Science Foundation (FWO-Vl), the European Science Foundation (ESF) under the EUROCORES program Euro-GRAPHENE (project CONGRAN), the Bilateral programme between CNPq and FWO-Vl, and the Brazilian Program Science Without Borders (CsF). We thank M. Ramezani Masir and M. Grujic for helpful comments and discussions. ; |
Approved |
Most recent IF: 6.337; 2014 IF: 6.196 |
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Call Number |
UA @ lucian @ c:irua:119280 |
Serial |
109 |
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Author |
Tran, T.T.; Lee, Y.; Roy, S.; Tran, T.U.; Kim, Y.; Taniguchi, T.; Watanabe, K.; Milošević, M.V.; Lim, S.C.; Chaves, A.; Jang, J.I.; Kim, J. |
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Title |
Synergetic enhancement of quantum yield and exciton lifetime of monolayer WS₂ by proximal metal plate and negative electric bias |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
ACS nano |
Abbreviated Journal |
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Volume |
18 |
Issue |
1 |
Pages |
220-228 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The efficiency of light emission is a critical performance factor for monolayer transition metal dichalcogenides (1L-TMDs) for photonic applications. While various methods have been studied to compensate for lattice defects to improve the quantum yield (QY) of 1L-TMDs, exciton-exciton annihilation (EEA) is still a major nonradiative decay channel for excitons at high exciton densities. Here, we demonstrate that the combined use of a proximal Au plate and a negative electric gate bias (NEGB) for 1L-WS2 provides a dramatic enhancement of the exciton lifetime at high exciton densities with the corresponding QY enhanced by 30 times and the EEA rate constant decreased by 80 times. The suppression of EEA by NEGB is attributed to the reduction of the defect-assisted EEA process, which we also explain with our theoretical model. Our results provide a synergetic solution to cope with EEA to realize high-intensity 2D light emitters using TMDs. |
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Wos |
001139516800001 |
Publication Date |
2023-12-21 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1936-0851 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
17.1 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: 17.1; 2023 IF: 13.942 |
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Call Number |
UA @ admin @ c:irua:202811 |
Serial |
9101 |
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Permanent link to this record |
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Author |
Dantas, D.S.; Chaves, A.; Farias, G.A.; Ramos, A.C.A.; Peeters, F.M. |
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Title |
Low-dimensional confining structures on the surface of helium films suspended on designed cavities |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Journal of low temperature physics |
Abbreviated Journal |
J Low Temp Phys |
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Volume |
173 |
Issue |
3-4 |
Pages |
207-226 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We investigate the formation of quantum confined structures on the surface of a liquid helium film suspended on a nanostructured substrate. We show theoretically that, by nanostructuring the substrate, it is possible to change the geometry of the liquid helium surface, opening the possibility of designing and controlling the formation of valleys with different shapes. By applying an external electric field perpendicular to the substrate plane, surface electrons can be trapped into these valleys, as in a quantum dot. We investigate how the external parameters, such as the electric field strength and the height of the liquid helium bath, can be tuned to control the energy spectrum of the trapped surface electrons. |
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Place of Publication |
New York |
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Wos |
000324820300008 |
Publication Date |
2013-08-22 |
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Edition |
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ISSN |
0022-2291;1573-7357; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.3 |
Times cited |
1 |
Open Access |
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Notes |
; This work has received financial support from the Brazilian National Research Council (CNPq), Fundacao Cearense de Apoio ao Desenvolvimento Cientifico e Tecnologico (Funcap), CAPES and Pronex/CNPq/Funcap. This work was partially supported by the Flemish Science Foundation (FWO-Vl) and the bilateral project between CNPq and FWO-Vl. ; |
Approved |
Most recent IF: 1.3; 2013 IF: 1.036 |
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Call Number |
UA @ lucian @ c:irua:111140 |
Serial |
1845 |
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Permanent link to this record |
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Author |
Chaves, A.; Neilson, D. |
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Title |
Exotic state seen at high temperatures |
Type |
Editorial |
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Year |
2019 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
574 |
Issue |
7776 |
Pages |
39-40 |
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Keywords |
Editorial; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The phenomenon of Bose-Einstein condensation is typically limited to extremely low temperatures. The effect has now been spotted at much higher temperatures for particles called excitons in atomically thin semiconductors. |
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Wos |
000488832500022 |
Publication Date |
2019-10-02 |
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Edition |
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ISSN |
0028-0836 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
40.137 |
Times cited |
2 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 40.137 |
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Call Number |
UA @ admin @ c:irua:163739 |
Serial |
5413 |
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Permanent link to this record |
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Author |
Chaves, A.; Azadani, J.G.; Alsalman, H.; da Costa, D.R.; Frisenda, R.; Chaves, A.J.; Song, S.H.; Kim, Y.D.; He, D.; Zhou, J.; Castellanos-Gomez, A.; Peeters, F.M.; Liu, Z.; Hinkle, C.L.; Oh, S.-H.; Ye, P.D.; Koester, S.J.; Lee, Y.H.; Avouris, P.; Wang, X.; Low, T. |
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Title |
Bandgap engineering of two-dimensional semiconductor materials |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
npj 2D Materials and Applications |
Abbreviated Journal |
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Volume |
4 |
Issue |
1 |
Pages |
29-21 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Semiconductors are the basis of many vital technologies such as electronics, computing, communications, optoelectronics, and sensing. Modern semiconductor technology can trace its origins to the invention of the point contact transistor in 1947. This demonstration paved the way for the development of discrete and integrated semiconductor devices and circuits that has helped to build a modern society where semiconductors are ubiquitous components of everyday life. A key property that determines the semiconductor electrical and optical properties is the bandgap. Beyond graphene, recently discovered two-dimensional (2D) materials possess semiconducting bandgaps ranging from the terahertz and mid-infrared in bilayer graphene and black phosphorus, visible in transition metal dichalcogenides, to the ultraviolet in hexagonal boron nitride. In particular, these 2D materials were demonstrated to exhibit highly tunable bandgaps, achieved via the control of layers number, heterostructuring, strain engineering, chemical doping, alloying, intercalation, substrate engineering, as well as an external electric field. We provide a review of the basic physical principles of these various techniques on the engineering of quasi-particle and optical bandgaps, their bandgap tunability, potentials and limitations in practical realization in future 2D device technologies. |
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Wos |
000565588500001 |
Publication Date |
2020-08-24 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2397-7132 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
604 |
Open Access |
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Notes |
; Discussions and interactions with D.R. Reichman, F. Tavazza, N.M.R. Peres, and K. Choudhary are gratefully acknowledged. A.C. acknowledges financial support by CNPq, through the PRONEX/FUNCAP and PQ programs. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 755655, ERCStG 2017 project 2D-TOPSENSE). Computational support from the Minnesota Supercomputing Institute (MSI) and EU Graphene Flagship funding (Grant Graphene Core 2, 785219) is acknowledged. R.F. acknowledges support from the Netherlands Organization for Scientific Research (NWO) through the research program Rubicon with project number 680-50-1515. D.H., J.Z., and X.W. acknowledge support by National Natural Science Foundation of China 61734003, 61521001, 61704073, 51861145202, and 61851401, and National Key Basic Research Program of China 2015CB921600 and 2018YFB2200500. J.Z. and Z.L. acknowledge support by RG7/18, MOE2017-T2-2-136, MOE2018-T3-1-002, and A*Star QTE program. S.H.S. and Y.H.L. acknowledge the support from IBS-R011-D1. Y.D.K. is supported by Samsung Research and Incubation Funding Center of Samsung Electronics under Project Number SRFC-TB1803-04. S.J.K acknowledges financial support by the National Science Foundation (NSF), under award DMR-1921629. T.L. and J.G.A. acknowledge funding support from NSF/DMREF under Grant Agreement No. 1921629. S.-H.O. acknowledges support from the U.S. National Science Foundation (NSF ECCS 1809723) and Samsung Global Research Outreach (GRO) project. ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:172069 |
Serial |
6459 |
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Permanent link to this record |
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Author |
Conti, S.; Chaves, A.; Pandey, T.; Covaci, L.; Peeters, F.M.; Neilson, D.; Milošević, M.V. |
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Title |
Flattening conduction and valence bands for interlayer excitons in a moire MoS₂/WSe₂ heterobilayer |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Nanoscale |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
1-11 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We explore the flatness of conduction and valence bands of interlayer excitons in MoS2/WSe2 van der Waals heterobilayers, tuned by interlayer twist angle, pressure, and external electric field. We employ an efficient continuum model where the moire pattern from lattice mismatch and/or twisting is represented by an equivalent mesoscopic periodic potential. We demonstrate that the mismatch moire potential is too weak to produce significant flattening. Moreover, we draw attention to the fact that the quasi-particle effective masses around the Gamma-point and the band flattening are reduced with twisting. As an alternative approach, we show (i) that reducing the interlayer distance by uniform vertical pressure can significantly increase the effective mass of the moire hole, and (ii) that the moire depth and its band flattening effects are strongly enhanced by accessible electric gating fields perpendicular to the heterobilayer, with resulting electron and hole effective masses increased by more than an order of magnitude – leading to record-flat bands. These findings impose boundaries on the commonly generalized benefits of moire twistronics, while also revealing alternative feasible routes to achieve truly flat electron and hole bands to carry us to strongly correlated excitonic phenomena on demand. |
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Wos |
001047512300001 |
Publication Date |
2023-07-25 |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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ISSN |
2040-3364; 2040-3372 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.7 |
Times cited |
1 |
Open Access |
Not_Open_Access: Available from 25.01.2024 |
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Notes |
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Approved |
Most recent IF: 6.7; 2023 IF: 7.367 |
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Call Number |
UA @ admin @ c:irua:198290 |
Serial |
8819 |
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Permanent link to this record |