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Arts offer an engaging opportunity to bring about women's underrepresentation issues in physics. In this work, we report the creation process, production, and reception of the short 360° video entitled 'Women in Science.' This movie maps and portrays female researchers' situation in physics at the University of Sao Paulo, a representative subset of the Brazilian physics community. The 360° movies are a novel way of storytelling, attracting public attention, and increasing the empathy caused by immersive experiences. The plots were based on interviews and surveys that embodied the female researcher's experiences over distinct career phases and levels. Challenges concerning the work environment, peer relationships, and the balance between work and personal life have been covered in the movie. All of them emerged in the descriptive analysis as effects that can influence women's career paths and affect their production capacity. This paper summarizes and discusses the scenes and the creative choices over the whole film production. It also reports the movie exhibition and dissemination processes by online streaming video platforms and public sessions with Virtual Reality (VR) gadgets. Based on the attendees' spontaneous response, it is possible to conclude that the movie brought contributions and promoted discussions on gender-related issues in the academic environment. Art, combined with VR immersive narratives, has proved to be an engaging, low-cost, and reproducible way to communicate sensitive issues to the viewers. Moreover, these experiences through 360° videos can be extended to document and highlight issues from women and other underrepresented minorities in physics.

Layered clay materials have been used to incorporate transition metal (TM) contaminants. Based on first-principles calculations, we have examined the energetic stability and the electronic properties due to the incorporation of Cd and Hg in layered clay materials, kaolinite (KAO) and pyrophyllite (PYR). The TM can be (i) adsorbed on the clay surface as well as (ii) intercalated between the clay layers. For the intercalated case, the contaminant incorporation rate can be optimized by controlling the interlayer spacing of the clay, namely, pillared clays. Our total energy results reveal that the incorporation of the TMs can be maximized through a suitable tuning of vertical distance between the clay layers. Based on the calculated TM/clay binding energies and the Langmuir absorption model, we estimate the concentrations of the TMs. Further kinetic properties have been examined by calculating the activation energies, where we found energy barriers of ~20 and ~130 meV for adsorbed and intercalated cases, respectively. The adsorption and intercalation of ionized TM adatoms were also considered within the deprotonated KAO surface. This also leads to an optimal interlayer distance which maximizes the TM incorporation rate. By mapping the total charge transfers at the TM/clay interface, we identify a net electronic charge transfer from the TM adatoms to the topmost clay surface layer. The effect of such a charge transfer on the electronic structure of the clay (host) has been examined through a set of X-ray absorption near edge structure (XANES) simulations, characterizing the changes of the XANES spectra upon the presence of the contaminants. Finally, for the pillared clays, we quantify the Cd and Hg K-edge energy shifts of the TMs as a function of the interlayer distance between the clay layers and the Al K-edge spectra for the pristine and pillared clays. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are among the most employed nanomaterials in developing new technologies. Their applicability requires a fundamental understanding of the chirality and defect effects on the mechanical properties. In this study, molecular dynamics (MD) simulations were performed to investigate the mechanical response of defective single-walled carbon nanotubes (SWCNTs) under tension loading. The Stones-Wales, monovacancy, and the divacancy reconstructions (585, 555777, and 555567777) defects were considered. In addition, we investigated the influence of the adaptive intermolecular reactive bond order (AIREBO) potential cut-off radii on the defect formation energy of SWCNTs. Our results reveal that the tensile strength properties are notably dependent on the chirality and defect configurations at strains over 8%. Energetically favourable defects have a high impact on the mechanical response of SWCNTs. A combination of certain defects may lead the control on the fracture pattern of the SWCNTs, which can significantly contribute to the designing of innovative nanostructures with tailored properties. [ABSTRACT FROM AUTHOR]

The electronic and coordination environment of minerals surfaces, as calcite, are very difficult to characterize experimentally. This is mainly due to the fact that there are relatively few spectroscopic techniques able to detect Ca2+. Since calcite is a major constituent of sedimentary rocks in oil reservoir, a more detailed characterization of the interaction between hydrocarbon molecules and mineral surfaces is highly desirable. Here we perform a first principles study on the adsorption of hydrocarbon molecules on calcite surface (CaCO3 (1014)). The simulations were based on Density Functional Theory with Solid State Nuclear Magnetic Resonance (SS-NMR) calculations. The Gauge-Including Projector Augmented Wave method was used to compute mainly SS-NMR parameters for 43Ca, 13C, and 17O in calcite surface. It was possible to assign the peaks in the theoretical NMR spectra for all structures studied. Besides showing different chemical shifts for atoms located on different environments (bulk and surface) for calcite, the results also display changes on the chemical shift, mainly for Ca sites, when the hydrocarbon molecules are present. Even though the interaction of the benzene molecule with the calcite surface is weak, there is a clearly distinguishable displacement of the signal of the Ca sites over which the hydrocarbon molecule is located. A similar effect is also observed for hexane adsorption. Through NMR spectroscopy, we show that aromatic and alkane hydrocarbon molecules adsorbed on carbonate surfaces can be differentiated. [ABSTRACT FROM AUTHOR]

Melanophlogite, a low-pressure silica polymorph, has been extensively studied at different temperatures and pressures by molecular dynamics simulations. While the high-temperature form is confirmed as cubic, the low-temperature phase is found to be slightly distorted, in agreement with experiments. With increasing pressure, the crystalline character is gradually lost. At 8 GPa, the radial distribution function is consistent with an amorphous state. Like pristine glass, the topology changes, plastic behavior, and permanent densification appear above ∼12 GPa, triggered by Si coordination number changes. We predict that a partial crystalline and amorphous sample can be obtained by recovering the sample from a pressure of ∼12-16 GPa. [ABSTRACT FROM AUTHOR]

We calculate by molecular dynamics the optical functions of MgO in the far infrared region 100–1000 cm-1, for pressures up to 40 GPa and temperatures up to 4000 K. An ab initio parametrized many-body force field is used to generate the trajectories. Infrared spectra are obtained from the time correlation of the polarization, and from Kramers–Kronig relations. The calculated spectra agree well with experimental data at ambient pressure. We find that the infrared absorption of MgO at CO2 laser frequencies increases substantially with both pressure and temperature and we argue that this may explain the underestimation, with respect to theoretical calculations, of the high-pressure melting temperature of MgO determined in CO2 laser-heated diamond-anvil cell experiments. [ABSTRACT FROM AUTHOR]

The structural, electronic, and thermodynamic properties of ammonia-borane complexes with varying amounts of hydrogen have been characterized by first principles calculations within density functional theory. The calculated structural parameters and thermodynamic functions (free energy, enthalpy and entropy) were found to be in good agreement with experimental and quantum chemistry data for the crystals, dimers, and molecules. The authors find that zero-point energies change several H2 release reactions from endothermic to exothermic. Both the ammonia-borane polymeric and borazine-cyclotriborazane cycles show a strong exothermic decomposition character (approximately -10 kcal/mol), implying that rehydrogenation may be difficult to moderate H2 pressures. Hydrogen bonding in these systems has been characterized and they find the N–H bond to be more covalent than the more ionic B–H bond. [ABSTRACT FROM AUTHOR]

The general aim of this study is to test the reliability of polarizable model potentials for the prediction of vibrational (infrared and Raman) spectra in highly anharmonic systems such as high temperature crystalline phases. By using an ab initio parametrized interatomic potential for SiO2 and molecular dynamics simulations, we calculate the infrared and Raman spectra for quartz, cristobalite, and stishovite at various thermodynamic conditions. The model is found to perform very well in the prediction of infrared spectra. Raman peak positions are also reproduced very well by the model; however, Raman intensities calculated by explicitly taking the derivative of the polarizability with respect to the atomic displacements are found to be in poorer agreement than intensities calculated using a parametrized “bond polarizability” model. Calculated spectra for the high temperature β phases, where the role of dynamical disorder and anharmonicities is predominant, are found to be in excellent agreement with experiments. For the octahedral phases, our simulations are able to reproduce changes in the Raman spectra across the rutile-to-CaCl2 transition around 50 GPa, including the observed phonon softening. [ABSTRACT FROM AUTHOR]

We have investigated the transitions between disordered phases in supercooled liquid silicon using computer simulations. The thermodynamic properties were directly obtained from the free energy, which was computed using the recently proposed reversible scaling method. The calculated free energies of the crystalline and liquid phases of silicon at zero pressure, obtained using the environment dependent interatomic potential, are in excellent agreement with the available experimental data. The results show that, at zero pressure, a weak first-order liquid–liquid transition occurs at 1135 K and a continuous liquid–amorphous transition takes place at 843 K. These results are consistent with the existence of a second critical point for the liquid–liquid transition at a negative pressure. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Several molecular dynamics simulations are conducted to explain the characteristics exhibited by the water and a light-oil model interface with self-accumulation of aromatics. The observed accumulation is shown to be a result of the differences observed in the interfacial tension of the system.