Gonçalves JA, dos Santos OFP, Batista RJC, Azevedo S. Optical properties of boron nitride nanoribbons with reconstruted edges. Solid State Communications [Internet]. 2022 :114627. Publisher's VersionAbstract
In this work, we employ first-principles calculations to investigate the optical properties of boron nitride nanoribbons with reconstructed edges. We found that because of the presence of homopolar B-B and N-N bonds in the edges, such nanoribbons, unlike boron nitride nanotubes, absorb light and have non-null optical conductivity in the visible and infrared range. The stoichiometry and distribution of the homopolar bonds in the edges change the absorption, reflectance, refraction index, and optical conductivity of nanoribbons, which may allow the tuning of those properties. Regarding the absorption in the infrared and visible range, the nanoribbons with B excess are almost unaffected by the direction of light incidence. On the other hand, the direction of light incidence strongly affects the intensity of the absorption peaks of nanoribbons with N excess in the region. At ultraviolet and above non-cylindrical geometry of the ribbons with the homopolar bonds at the edges also lead to a dependence of the optical properties with the direction of light incidence.
Gonçalves JA, dos Santos OFP, Batista RJC, Azevedo S. First-principle investigation of silicon carbide nanosheets fluorination: Stability trends, electronic, optical and magnetic properties. Chemical Physics Letters [Internet]. 2022;787 :139266. Publisher's VersionAbstract
We employed first-principles calculations to investigate the fluorination of silicon carbide nanosheets. We found that the Si atoms are the energetically favorable adsorption sites for F atoms in silicon carbide nanosheets in all studied cases. The strain caused by the fourfold coordinated Si atoms in the flat SiC nanosheet determines the relative position of the adsorbed F atoms: occupying nearest-neighbor Si sites if they bound sheet’s opposing sides or away from each other if they are on the same side of the sheet. The fluorinated nanosheets’ electronic and magnetic properties are weakly dependent on which side of the sheet the F atoms bind; however, they are strongly dependent on the relative distance between them. For F atoms adsorbed on nearest-neighbor Si sites, the system is a small gap p-type semiconductor with 1 μB per adsorbed atom. On the other hand, if F atoms do not occupy nearest-neighbor Si sites, the system is a metal with 1/2 μB per adsorbed atom. The adsorption of F atoms strongly affects the optical properties of SiC sheets inducing optical anisotropy regarding the direction of the incidence of light.
Lima G, Rocha JN. Interações Discursivas entre Educadores Museais e Estudantes: Um Estudo de Caso em um Museu de Ciências a partir das Contribuições de Bakhtin e do C{\'ırculo. Revista Brasileira de Pesquisa em Educação em Ciências. 2021 :e21788–33.
Fernandes J, Lima G, Aguiar Jr OG. As Representações de Stephen Hawking em Filmes Biográficos. Revista Brasileira de Pesquisa em Educação em Ciências. 2021 :e16539–32.
da Silva Lima G, Pagliarini CR, Aguiar Jr OG. CIÊNCIA, ARTE E FILOSOFIA: MOBILIZANDO DISCURSOS NO USO EDUCATIVO DO CINEMA NUMA ATIVIDADE NÃO FORMAL. Investigações em Ensino de Ciências. 2021;26 (1) :305–323.
da Silva Lima G, Calazans MM, Massi L. Mensagens falsas sobre o novo coronav{\'ırus: legitimidade e manipulação na luta de classes. Chasqui: Revista Latinoamericana de Comunicación. 2021;(147) :259–279.
da Lima GS, Giordan M. Da reformulação discursiva a uma práxis da cultura cient{\'ıfica: reflexões sobre a divulgação cient{\'ıfica. História, Ciências, Saúde-Manguinhos. 2021;28 :375–392.
Fabris JC, Ottoni T, Toniato JD, Velten H. Stellar Structure in a Newtonian Theory with Variable G. Physics [Internet]. 2021;3 (4) :1123–1132. Publisher's VersionAbstract
A Newtonian-like theory inspired by the Brans–Dicke gravitational Lagrangian has been recently proposed by us. For static configurations, the gravitational coupling acquires an intrinsic spatial dependence within the matter distribution. Therefore, the interior of astrophysical configurations may provide a testable environment for this approach as long as no screening mechanism is evoked. In this work, we focus on the stellar hydrostatic equilibrium structure in such a varying Newtonian gravitational coupling G scenario. A modified Lane–Emden equation is presented and its solutions for various values of the polytropic index are discussed. The role played by the theory parameter ω, the analogue of the Brans–Dicke parameter, in the physical properties of stars is discussed.
Bessa MV, Freitas WD, Neme NP, Martins LGP, Barboza APM, Matos MJS, Mazzoni MSC, Neves BRA. Electromechanical Modulations in Transition Metal Dichalcogenide Nanosheets: Implications for Environmental Sensors. ACS Applied Nano Materials [Internet]. 2021 :null. Publisher's Version
Silva VP, Guimarães MHU, Passos MM. Sequência Didática para o ensino de Astronomia. Caderno Brasileiro de Ensino de F{\'ısica. 2021;38 (2) :1135–1165.
Castro-e-Silva A, Bernardes AT, Gon\c calves Barbosa EA, Dáttilo W, RIBEIRO SÉRVIOP. Successive pandemic waves with more virulent strains, and the effects of vaccination for SARS-CoV-2. medRxiv [Internet]. 2021. Publisher's VersionAbstract
Hundred years after the flu pandemic of 1918, the world faces an outbreak of a new severe acute respiratory syndrome, caused by a novel coronavirus. With a high transmissibility, the pandemic spreads worldwide, creating a scenario of devastation in many countries. By the middle of 2021, about 3% of the world population has been infected and more than 4 million people have died. Different from the H1N1 pandemic, which had a deadly wave and cessed, the new disease is maintained by successive waves, mainly produced by new virus variants, and the small number of vaccinated people. In the present work, we create a version of the SIR model with spatial localization of persons, their movements, and taking into account social isolation probabilities. We discuss the effects of virus variants, and the role of vaccination rate in the pandemic dynamics. We show that, unless a global vaccination is implemented, we will have continuous waves of infections.HighlightsThe COVID-19 has infected more than 200 millions and has killed more than 4 million persons.WHO has not been successful in defining a global vaccination policy.Many epidemic scenarios arise when different countries apply different vaccination strategies.Present model can show some insights on how vaccination programs can be managed.Competing Interest StatementThe authors have declared no competing interest.Funding StatementThis research did not receive any specific grant from funding agencies in the commercial, or non-profit sectors. SPR acknowledges grant from Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPq, through proccess 306572/2019-2.Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:The manuscript is a modeling paper, there was no clinical trial of any kind.All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesThe code of model is included in manuscript files.
Velten H, Costa I, Zimdahl W. Early-time thermalization of cosmic components? A hint for solving cosmic tensions. Phys. Rev. D [Internet]. 2021;104 :063507. Publisher's Version
Souza ACR, Matos MJS, Mazzoni MSC. Interplay between structural deformations and flat band phenomenology in twisted bilayer antimonene. RSC Adv. [Internet]. 2021;11 :27855-27859. Publisher's VersionAbstract
In this work we apply first principles calculations to investigate the flat band phenomenology in twisted antimonene bilayer. We show that the relatively strong interlayer interactions which characterize this compound have profound effects in the emergence and properties of the flat bands. Specifically, when the moiré length becomes large enough to create well defined stacking patterns along the structure, out-of-plane displacements take place and are stabilized in the regions dominated by the AB stacking, leading to the emergence of flat bands. The interplay between structural and electronic properties allows for detection of flat bands in higher twist angles comparable to other two-dimensional materials. We also show that their energy position may be modulated by noncovalent functionalization with electron acceptor molecules.
RIBEIRO SÉRVIOP, REIS ALEXANDREB, Dáttilo W, SILVA ALCIDESVCDECASTROE, BARBOSA EDUARDOAUGUSTOG, Coura-vital W, Góes-Neto A, AZEVEDO VASCOAC, Fernandes GW. From Spanish Flu to Syndemic COVID-19: long-standing sanitarian vulnerability of Manaus, warnings from the Brazilian rainforest gateway. [Internet]. 2021;93 (suppl 3). Publisher's Version
Toniato JD, Rodrigues DC. Post-Newtonian $\ensuremath\gamma$-like parameters and the gravitational slip in scalar-tensor and $f(R)$ theories. Phys. Rev. D [Internet]. 2021;104 :044020. Publisher's Version
Nicomedes DNN, Mota LM, Vasconcellos R, Medrado NV, de Oliveira M, de Alvarenga ÉC, Juste KRC, Righi A, Manhabosco SM, Silva GJB, et al. Comparison between hydroxyapatite/soapstone and hydroxyapatite/reduced graphene oxide composite coatings: Synthesis and property improvement. Journal of the Mechanical Behavior of Biomedical Materials [Internet]. 2021;121 :104618. Publisher's VersionAbstract
Economic viability and eco-friendliness are important characteristics that make implants available to the population in a sustainable way. In this work, we evaluate the performance of a low-cost, widely available, and eco-friendly material (talc from soapstone) relative to reduced graphene oxide as reinforcement to brittle hydroxyapatite coatings. We employ a low-cost and straightforward technique, electrodeposition, to deposit the composite coatings on the titanium substrate. Corrosion, wear, and biocompatibility tests indicate that the reduced graphene oxide can be effectively replaced by talc without reducing the mechanical, anticorrosion, and biocompatible composite coatings properties. Our results indicate that talc from soapstone is a promising material for biomedical applications.
Savedra RML, Fonseca AMT, Silva MM, Bianchi RF, Siqueira MF. White LED phototherapy as an improved treatment for neonatal jaundice. Review of Scientific Instruments [Internet]. 2021;92 (6) :064101. Publisher's Version
Antunes A, Gouveia AP, Diogo G, Taylor J, Sousa L, Amparo T, Perasoli F, dos Santos O, Cazati T, Vieira P, et al. In vitro Photoprotective Evaluation and Development of Novel Nanoemulsion with Chromone Derivative. J. Braz. Chem. Soc. [Internet]. 2021. Publisher's Version
Santos JCC, Prado MC, Morais HLO, Sousa SM, Silva-Pinto E, Cançado LG, Neves BRA. Topological vectors as a fingerprinting system for 2D-material flake distributions. npj 2D Mater Appl [Internet]. 2021;5 (1). Publisher's Version
Sales JNB, da Silva RT, Lara LRS, Ramos SLLM, Soares JS, Soares TAS, Machado G, Manhabosco SM, de Oliveira AB, de Carvalho HB, et al. Structural, optical, and magnetic evaluation of Co-, Ni-, and Mn-modified multiferroic BiFeO3 ceramics. Ceramics International [Internet]. 2021. Publisher's VersionAbstract
Co-, Ni-, and Mn-doped BiFeO3 (BFO) ceramics were synthesized herein through a solid-state reaction. All doped BFO samples exhibit visible-light response, and the Co- and Ni-doped BFO samples present enhanced ferromagnetic order at room temperature. All doped samples show secondary phases in minor quantities. Optical spectra reveal two absorptions bands, indicating multiple electron transitions for BFO and its secondary phases. M − H hysteresis loops suggest enhanced ferromagnetism in the Co- and Ni-doped BFO samples because of magnetic spinel CFP and NFO phases, respectively, whereas changes in oxygen vacancies and Fe–O–Fe bond angle play minor roles in the ferromagnetic behavior.