Fabris JC, Velten H, Wojnar A. Existence of static spherically-symmetric objects in action-dependent Lagrangian theories. Phys. Rev. D [Internet]. 2019;99 :124031. Publisher's Version
Perenon L, Velten H. The Effective Field Theory of Dark Energy Diagnostic of Linear Horndeski Theories After GW170817 and GRB170817A. Universe [Internet]. 2019;5 (6). Publisher's VersionAbstract
We summarize the effective field theory of dark energy construction to explore observable predictions of linear Horndeski theories. We review the diagnostic of these theories on the correlation of the large-scale structure phenomenological functions: the effective Newton constant, the light deflection parameter, and the growth function of matter perturbations. We take this opportunity to discuss the evolution of the bounds the propagation speed of gravitational waves has undergone and use the most restrictive one to update the diagnostic.
Salla CAM, Teixeira dos Santos J, Farias G, Bortoluzi AJ, Curcio SF, Cazati T, Izsák R, Neese F, de Souza B, Bechtold IH. New Boron(III) Blue Emitters for All-Solution Processed OLEDs: Molecular Design Assisted by Theoretical Modeling. European Journal of Inorganic Chemistry [Internet]. 2019;2019 (17) :2247-2257. Publisher's VersionAbstract
Luminescent boron(III) complexes have recently been employed as emitters in organic light-emitting diodes (OLEDs) with reasonable success. They are easy to prepare and sufficiently stable to be used in such devices, being of great interest as a simple molecular emissive layer. Although emitters for this class with all colors have already been reported, highly efficient and stable blue emitters for applications in solution processed devices still pose a challenge. Here, we report the design, synthesis, and characterization of new boron complexes based on the 2-(benzothiazol-2-yl)phenol ligand (HBT), with different donor and acceptor groups responsible for modulating the emission properties, from blue to red. The molecular design was assisted by calculations using our newly developed formalism, where we demonstrate that the absorption and fluorescence spectra can be successfully predicted, which is a powerful technique to evaluate molecular photophysical properties prior to synthesis. In addition, density functional theory (DFT) enables us to understand the molecular and electronic structure of the molecules in greater detail. The molecules studied here presented fluorescence efficiencies as high as Φ = 0.88 and all solution processed OLEDs were prepared and characterized under an ambient atmosphere, after dispersion in the emitting layer. Surprisingly, even considering these rather simple experimental conditions, the blue emitters displayed superior properties compared to those in the present literature, in particular with respect to the stability of the current efficiency.
Zimdahl W, Velten HES, Algoner WC. Matter Growth in Imperfect Fluid Cosmology. Universe [Internet]. 2019;5 (3). Publisher's VersionAbstract
Extensions of Einstein’s General Relativity (GR) can formally be given a GR structure in which additional geometric degrees of freedom are mapped on an effective energy-momentum tensor. The corresponding effective cosmic medium can then be modeled as an imperfect fluid within GR. The imperfect fluid structure allows us to include, on a phenomenological basis, anisotropic stresses and energy fluxes which are considered as potential signatures for deviations from the cosmological standard Λ -cold-dark-matter ( Λ CDM) model. As an example, we consider the dynamics of a scalar-tensor extension of the standard model, the e Φ Λ CDM model. We constrain the magnitudes of anisotropic pressure and energy flux with the help of redshift-space distortion (RSD) data for the matter growth function f σ 8 .
Dias RF, da Costa CC, Manhabosco TM, de Oliveira AB, Matos MJS, Soares JS, Batista RJC. Ab initio molecular dynamics simulation of methanol and acetonitrile: The effect of van der Waals interactions. Chemical Physics Letters [Internet]. 2019;714 :172 - 177. Publisher's VersionAbstract
We employed PBE and BLYP semi-local functionals and the van der Waals density functional of Dion et al. (2004) (vdW-DF) to investigate structural properties of liquid acetonitrile and methanol. Among those functionals the vdW-DF is the only one that correctly predicts energy minima in inter-molecular interactions between acetonitrile molecules. We found that van der Waals interactions have a negligible effect on H-bonds in methanol chains. However, it significantly increases chain packing resulting in a more dense liquid in comparison to the other two functionals. The overall trend is that the vdW-DF tends to overestimate density and bulk modulus, meanwhile the semi-local functionals tend to underestimate density. Thus, van der Waals interactions play an important role in the properties of liquids in which much stronger dipole-dipole interactions are present.
Souza FS, Matos MJS, Galvão BRL, Arapiraca AFC, da Silva SN, Pinheiro IP. Adsorption of CO2 on biphasic and amorphous calcium phosphates: An experimental and theoretical analysis. Chemical Physics Letters [Internet]. 2019;714 :143 - 148. Publisher's VersionAbstract
Calcium phosphates are suggested as a CO2 adsorbent via pressure swing adsorption. Amorphous calcium phosphate (ACP) and biphasic calcium phosphate (BCP) (composed of hydroxyapatite and beta-tricalcium phosphate) were investigated for the capture/immobilization of the gas. A fluidized bed was set up to assess the levels of CO2 adsorption by ACP and BCP. A gaseous mixture was synthesized, mimicking the conditions for possible industrial use. The results show a significant reduction in CO2 concentrations. Using DFT calculations, we show that CO2 adsorption increases the stability by reducing the surface energy. The energies involved and preferential adsorption sites were also theoretically predicted.
dos Santos PL, Silveira OJ, Huang R, Jardim GAM, Matos MJS, da Silva Júnior EN, Monkman AP, Dias FB, Cury LA. Dynamics of aggregated states resolved by gated fluorescence in films of room temperature phosphorescent emitters. Phys. Chem. Chem. Phys. [Internet]. 2019;21 :3814-3821. Publisher's VersionAbstract
Phenazine derivative molecules were studied using steady state and time resolved fluorescence techniques and demonstrated to lead to strong formation of aggregated species, identified as dimers by time dependent density functional theory calculations. Blended films in a matrix of Zeonex®, produced at different concentrations, showed different contributions of dimer and monomer emissions in a prompt time frame, e.g. less than 50 ns. In contrast, the phosphorescence (e.g. emission from the triplet state) shows no significant effect on dimer formation, although strong dependence of the phosphorescence intensity on concentration is observed, leading to phosphorescence being quenched at higher concentration.
da Silva TM, Bernardes AT. Ripples and grains segregation on unpaved road. International Journal of Modern Physics C [Internet]. 2018;29 (12) :1850120. Publisher's VersionAbstract
Ripples or corrugations are common phenomena observed in unpaved roads in less developed countries or regions. They cause several damages in vehicles leading to increased maintenance and product costs. In this paper, we present a computational study about the so-called washboard roads. Also, we study grain segregation on unpaved roads. Our simulations have been performed by the Discrete Element Method (DEM). In our model, the grains are regarded as soft disks. The grains are subjected to a gravitational field and both translational and rotational movements are allowed. The results show that wheels’ of different sizes, weights and moving with different velocities can change corrugations amplitude and wavelength. Our results also show that some wavelength values are related to specific wheels’ speed intervals. Segregation has been studied in roads formed by three distinct grain diameters distribution. We observed that the phenomenon is more evident for higher grain size dispersion.
da Costa Junior E, da Fernandes BS, da Lima GS, de Siqueira AJ, Paiva JNM, e Santos MG, Tavares JP, de Souza TV, Gomes TMF. Divulgacão e ensino de Astronomia e Física por meio de abordagens informais. Revista Brasileira de Ensino de FÃ\-sica [Internet]. 2018;40. Publisher's Version
Silva Nunes ME, de Silva ÉM, Martins PHL, Plascak JA, Florencio J. Effects of a magnetic field on the dynamics of the one-dimensional Heisenberg model with Dzyaloshinskii-Moriya interactions Phys. Rev. E. PHYSICAL REVIEW E [Internet]. 2018 :null. Publisher's Version
da C. Gonçalves M, Taylor J, Rossoni Júnior J, Carolina S. Rabelo A, Costa D, Cazati T, M. R. dos Santos V. Preliminary Studies of the Cytotoxicity and Photoprotective Properties of Benzophenone and Lactone Derivatives. Revista Virtual de Química. 2018;10 :600-608.
Barboza APM, Matos MJS, Chacham H, Batista RJC, de Oliveira AB, Mazzoni MSC, Neves BRA. Compression-Induced Modification of Boron Nitride Layers: A Conductive Two-Dimensional BN Compound. ACS Nano [Internet]. 2018 :null. Publisher's Version
de Sousa TASL, Fernandes TFD, Matos MJS, Araujo END, Mazzoni MSC, Neves BRA, Plentz F. Thionine Self-Assembled Structures on Graphene: Formation, Organization, and Doping. Langmuir [Internet]. 2018;34 (23) :6903-6911. Publisher's Version
Colla T, Mohanty PS, Nöjd S, Bialik E, Riede A, Schurtenberger P, Likos CN. Self-Assembly of Ionic Microgels Driven by an Alternating Electric Field: Theory, Simulations, and Experiments. ACS Nano [Internet]. 2018 :null. Publisher's Version
Alencar TV, von Dreifus D, Moreira MGC, Eliel GSN, Yeh C-H, Chiu P-W, Pimenta MA, Malard LM, de Paula AM. Twisted bilayer graphene photoluminescence emission peaks at van Hove singularities. Journal of Physics: Condensed Matter [Internet]. 2018;30 (17) :175302. Publisher's VersionAbstract
We report on photoluminescence emission imaging by femtosecond laser excitation on twisted bilayer graphene samples. The emission images are obtained by tuning the excitation laser energies in the near infrared region. We demonstrate an increase of the photoluminescence emission at excitation energies that depends on the bilayer twist angle. The results show a peak for the light emission when the excitation is in resonance with transitions at the van Hove singularities in the electronic density of states. We measured the photoluminescence excitation peak position and width for samples with various twist angles showing resonances in the energy range of 1.2 to 1.7 eV.
Cariglia M, Galajinsky A, Gibbons GW, Horvathy PA. Cosmological aspects of the Eisenhart–Duval lift. The European Physical Journal C [Internet]. 2018;78 (4) :314. Publisher's VersionAbstract
A cosmological extension of the Eisenhart–Duval metric is constructed by incorporating a cosmic scale factor and the energy-momentum tensor into the scheme. The dynamics of the spacetime is governed by the Ermakov–Milne–Pinney equation. Killing isometries include spatial translations and rotations, Newton–Hooke boosts and translation in the null direction. Geodesic motion in Ermakov–Milne–Pinney cosmoi is analyzed. The derivation of the Ermakov–Lewis invariant, the Friedmann equations and the Dmitriev–Zel'dovich equations within the Eisenhart–Duval framework is presented.
Ferrari GA, de Oliveira AB, Silvestre I, Matos MJS, Batista RJC, Fernandes TFD, Meireles LM, Eliel GSN, Chacham H, Neves BRA, et al. Apparent Softening of Wet Graphene Membranes on a Microfluidic Platform. ACS Nano [Internet]. 2018 :null. Publisher's Version
de Cardoso AVM, da Paolinelli SC, Silveira CC, Cota AB. Secondary recrystallization characteristics of 3%Si grain-oriented electrical steel. Journal of Materials Research and Technology [Internet]. 2018. Publisher's Version
de Souza JB, de Souza J, de Castro LML, Siqueira MF, Savedra RML, Silva-Barcellos NM. “Evaluation of the losartan solubility in the biowaiver context by shake-flask method and intrinsic dissolution”. Pharmaceutical Development and Technology [Internet]. 2018;(ja) :1-32. Publisher's Version
Mól LAS, Rodrigues RGM, Stancioli RA, Rocha JCS, Costa BV. On the use of the energy probability distribution zeros in the study of phase transitions. Journal of Physics: Conference Series [Internet]. 2018;1012 (1) :012005. Publisher's VersionAbstract
This contribution is devoted to cover some technical aspects related to the use of the recently proposed energy probability distribution zeros in the study of phase transitions. This method is based on the partial knowledge of the partition function zeros and has been shown to be extremely efficient to precisely locate phase transition temperatures. It is based on an iterative method in such a way that the transition temperature can be approached at will. The iterative method will be detailed and some convergence issues that has been observed in its application to the 2D Ising model and to an artificial spin ice model will be shown, together with ways to circumvent them.