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.
Alencar TV, Carvalho EJ. Fotografando com uma cÃ\textcentmera de pixel Ã\textordmasculinenico. Revista Brasileira de Ensino de FÃ\-sica [Internet]. 2021;43. Publisher's Version
Pogna EAA, Miao X, von Dreifus D, Alencar TV, Moutinho MVO, Venezuela P, Manzoni C, Ji M, Cerullo G, de Paula AM. Angle-tunable intersubband photoabsorption and enhanced photobleaching in twisted bilayer graphene. Nano Res. [Internet]. 2021. Publisher's Version
Bernardes AT, Ribeiro LC. Information, opinion and pandemic. Physica A: Statistical Mechanics and its Applications [Internet]. 2021;565 :125586. Publisher's VersionAbstract
The world’s population suffers a COVID-19 pandemic. By September 2020 nearly 1 million people had died. These are official numbers. The real cases might be much higher, due to under-reporting in many countries. Different strategies were adopted by national governments. Neglecting what was defined by sanitarian authorities, some politicians, at the beginning of the pandemic, declared that it would be a little flu, without consequences, lighter than seasonal flues. Some politicians propagated medicines with no scientific support. In many countries and regions, people became confused. The population’s reactions to these political positions may facilitate or block the virus spread. In this paper, we propose a model connecting the spreading of opinions with the propagation of a pandemic. We discuss how conflicting opinions can diffuse in the pandemic environment and the influence it has on the population’s behavior; how it may cause a greater or smaller number of infected individuals.
Gabriel LT, Bianchi RF, Bernardes AT. Mechanical Property Assessment of Interlocking Plastic Pavers Manufactured from Electronic Industry Waste in Brazil. Recycling [Internet]. 2021;6 (1) :15. Publisher's Version
Sousa L, Azevedo ML\'ıza, Rocha D, Andrade Â, Amparo T, dos Santos O, Seibert J\'ına, Pereira L, Vieira P, Carneiro C, et al. Trypanocidal Activity and Increased Solubility of Benznidazole Incorporated in PEG 4000 and Its Derivatives. J. Braz. Chem. Soc. [Internet]. 2021. Publisher's Version
Velten H. Matéria escura e as estruturas cósmicas. Cadernos de Astronomia [Internet]. 2021;2 (1) :58. Publisher's Version
Velten H, Caramês TRP. To conserve, or not to conserve: A review of nonconservative theories of gravity. Universe. 2021;7 (2) :38.
Fabris JC, Gomes T, Toniato JD, Velten H. Newtonian-like gravity with variable G. Eur. Phys. J. Plus [Internet]. 2021;136 (2). Publisher's Version
Cota AB. TERMODINÂMICADOS MATERIAIS. 1st ed. Ouro Preto; 2020. abcota_termodinamica_dos_materiais.pdf
Ribeiro LC, Bernardes AT. Estimate of underreporting of COVID-19 in Brazil by Acute Respiratory Syndrome hospitalization reports. Notas Técnicas Cedeplar-UFMG [Internet]. 2020;xx (xx) :xx. Publisher's VersionAbstract
The number of COVID-19 infected people in each country is a crucial factor to determine public policies. It guides the governments to strengthen movement restrictions of people or to relieve it. The number of infected people is very important to forecast the needs of the health systems, which are collapsing in many countries. Thus, underreporting of infected people is a huge problem, since authorities do not know the real problem and act in darkness. In the present work, we discuss this subject for the Brazilian case. We take the time series of acute respiratory syndromes reported in the health public system in the last ten years and estimated the number for March/20 when the COVID-19 appeared in Brazil. Our results show a 7.7:1 rate of underreporting, meaning that the real cases in Brazil should be, at least, seven times the publicized number.
Andrade MV, Noronha K, Turra CM, Guedes G, Cimini FANDR, Costa L, Bernardes AT, et. al. Os primeiros 80 dias da pandemia da COVID-19 em Belo Horizonte: da contenção à flexibilização. Nova Economia [Internet]. 2020;30 (0103-6351) :701-737. Publisher's VersionAbstract
Este artigo examina o contexto e as implicações da pandemia por Covid-19 na cidade de Belo Horizonte (BH) nos primeiros 80 dias da doença. Utilizamos um recorte analítico descritivo para mensurar a evolução dos casos, o excesso de óbitos, a taxa de transmissibilidade do vírus e a pressão da doença sobre o sistema de saúde de BH e região, através da taxa de ocupação hospitalar nos leitos públicos. Além disso, identificamos as principais políticas de contenção adotadas pelas autoridades locais, bem como as implicações da redução do distanciamento social. Nossos resultados demonstram que o Sistema Único de Saúde (SUS), bem gerido, é fundamental para o enfrentamento da pandemia e a mitigação de suas consequências para a população. O processo de flexibilização que se inicia tem imposto novos desafios que requererão monitoramento atento das autoridades e da sociedade.
Alencar AB, de Oliveira A, Chacham H. Crystal reorientation and plastic deformation of single-layer MoS2 and MoSe2 under uniaxial stress. Journal of Physics: Condensed Matter [Internet]. 2020. Publisher's VersionAbstract
We investigate theoretically, through of first-principles calculations, the effect of the application of large in-plane uniaxial stress on single-layer of MoS2, MoSe2, and MoSSe alloys. For stress applied along the zigzag direction, we predict an anomalous behavior near the point fracture. This behavior is characterized by the reorientation of the MoS2 structure along the applied stress from zigzag to armchair due to the formation of transient square-lattice regions in the crystal, with an apparent (although not real) crystal rotation of 30 degrees. After reorientation, a large plastic deformation √3-1 remains after the stress is removed. This behavior is also observed in MoSe2 and in MoSSe alloys. This phenomenon is observed both in stress-constrained geometry optimizations and in ab initio molecular dynamics simulations at finite temperature and applied stress.
Velten H, Dito G. Post-Editorial of the Special Issue “Estate Quantistica Conference—Recent Developments in Gravity, Cosmology, and Mathematical Physics”. Universe [Internet]. 2020;6 (12) :240. Publisher's Version
de Santos ABS, Manfredi AM, Salla CAM, Farias G, Girotto E, Eccher J, Westphal E, Curcio SF, Cazati T, Malvestiti I, et al. Highly luminescent liquid crystals by connecting 1,3,4-oxadiazole with thiazolo[5,4-d]thiazole units. Journal of Molecular Liquids [Internet]. 2020 :114887. Publisher's VersionAbstract
The direct bonding between a thiazolo[5,4-d]thiazole and two 1,3,4-oxadiazole units allowed us to create a new and versatile rigid core for luminescent liquid crystal, which showed interesting and variable mesomorphic and photophysical properties. From the 5-bis(5-phenyl-1,3,4-oxadiazol-2-yl)thiazolo[5,4-d]thiazole new core, three molecules with different number of alkoxy chains were synthesized and had their properties correlated with the molecular structure. The molecule with two chains showed a smectic C mesophase, while the mesogens with four and six chains presented hexagonal columnar mesomorphism, which was confirmed by POM and XRD measurements. In addition, the molecule with six chains presented liquid crystalline behavior close to room temperature. In solution, the molecules presented strong photoluminescence ranging from blue to yellow, with quantum yields higher than 0.6. Excited state lifetimes allowed to correlate the fluorescence component associated to the different emitting species to the molecular organization in spin coated films. The molecular energy levels, together with thermal stability and possible charge carrier transport due to molecular packing, suggest that these molecules are promising for optoelectronic applications. Overall, this work contributes to the development of the use of thiazolo[5,4-d]thiazole in liquid crystals, demonstrating its great efficiency and versatility.
Batista RJC, Dias RF, Barboza APM, de Oliveira AB, Manhabosco TM, Gomes-Silva TR, Gadellha AC, Rabelo C, Cançado LGL, Jorio A, et al. Nanomechanics of few-layer materials: do individual layers slide upon folding?. Beilstein J. Nanotechnol. 2020;11 :1801–1808.
Diniz MO, Coelho RS, Bianchi RF, Guerra EM. Electrical Impedance of V 2 O 5/POMA Hybrid Film Deposited by Casting for Application in Ammonia Gas Sensor. Journal of Electronic Materials. 2020 :1–6.
Martins LGP, Silva DL, Smith JS, Lu A-Y, Su C, Hempel M, Occhialini C, Ji X, Pablo R, Alencar RS, et al. Hard, transparent, sp3-containing 2D phase formed from few-layer graphene under compression. Carbon [Internet]. 2020. Publisher's VersionAbstract
Despite several theoretically proposed two-dimensional (2D) diamond structures, experimental efforts to obtain such structures are in initial stage. Recent high-pressure experiments provided significant advancements in the field, however, expected properties of a 2D-like diamond such as sp3 content, transparency and hardness, have not been observed together in a compressed graphene system. Here, we compress few-layer graphene samples on SiO2/Si substrate in water and provide experimental evidence for the formation of a quenchable hard, transparent, sp3-containing 2D phase. Our Raman spectroscopy data indicates phase transition and a surprisingly similar critical pressure for two-, five-layer graphene and graphite in the 4-6 GPa range, as evidenced by changes in several Raman features, combined with a lack of evidence of significant pressure gradients or local non-hydrostatic stress components of the pressure medium up to ≈ 8 GPa. The new phase is transparent and hard, as evidenced from indentation marks on the SiO2 substrate, a material considerably harder than graphene systems. Furthermore, we report the lowest critical pressure (≈ 4 GPa) in graphite, which we attribute to the role of water in facilitating the phase transition. Theoretical calculations and experimental data indicate a novel, surface-to-bulk phase transition mechanism that gives hint of diamondene formation.
Farias G, Salla CAM, da Silva Heying R, Bortoluzzi AJ, Curcio S, Cazati T, dos Santos PL, Monkman AP, de Souza B, BECHTOLD IVANH. Reducing Lifetime in Cu(I) Complexes with Thermally Activated Delayed Fluorescence and Phosphorescence promoted by Chalcogenolate-Diimine Ligand. J. Mater. Chem. C [Internet]. 2020 :-. Publisher's VersionAbstract
Luminescent copper(I) complexes have drawn attention due to their promising performance as alternative optoelectronic materials to the well-known heavy transition metals complexes. Herein, we report the synthesis of six luminescent Cu(I) complexes with phosphines and 1,10-phenanthroline-derived ligands with thiadiazole and selenodiazole groups in order to evaluate the effect of heavy atom on their photophysical properties. Steady-state and time-resolved spectroscopy confirmed delayed fluorescence emission via a thermally activated delayed fluorescence mechanism in all cases. The experimental spectroscopic data was analyzed with detailed quantum-chemical calculations. Interestingly, these complexes did not show the expected “heavy atom effect”, that enhances the spin-orbit coupling matrix elements, but nevertheless the addition of the heavier chalcogens contributed to reduce the photoluminescence lifetime to roughly 800 ns, which is the lowest reported so far for such TADF materials.