Publications

Abstract Several studies analyzed the importance of absorptive capacity (AC) to achieve economic development. However, to the best of our knowledge, no study compares the building blocks (BBs) of AC between developed and emergent economies. This paper aims to identify and analyze the impact of the BBs on AC under distinct levels of development (i.e., developed vs. emerging economies) using systematic literature review (SLR) and econometrics. Specifically, both linear and nonlinear analyses were employed. Our findings show that BBs in developed and emergent regions are different. For both groups, R&D, FDI (foreign direct investment), infrastructure, and HDI (human development index) variables are BBs of AC. For developed economies, BBs also contemplate secondary education enrollments, the higher education index, and the percentage of GDP spent on higher education. Moreover, the thresholds of BBs also differ between developed and emergent economies. This identification of BBs and possible AC thresholds is valuable, as it provides information to set goals and strategies before a foreign investment attraction policy. Thus, the results facilitate the development of more suitable strategies to enhance positive productivity spillovers and avoid negative spillovers whenever possible. These results show that policymakers cannot employ the same policies for the development of developed and emerging countries.

The scaleup process can be divided into 3 steps in the lab from the basic research, product, process validation up to the more complex 4th step of building and operating the pilot plant.

In this work, we apply a combination of theoretical techniques to characterize a two-dimensional material with formula B2N2O2, featuring a zigzag array of nitrogen atoms. We predict its energetic, thermal, and dynamic stability and determine its electronic properties, including band structure and mobility evaluation for a phonon-mediated mechanism. We show that the compound is a wideband-gap semiconductor, with parabolic band edges and with large electron and hole mobilities within the deformation potential approach. We ascribe this result to the existence of electronic channels defined by the zigzag array of nitrogen bonds, which define the edges of both conduction and valence bands. We also propose a mechanism to synthesize the compound based on oxygen functionalization and application of pressure. Finally, we show that the results can be generalized to represent a family of 2D compounds.

In this study, we explore the potential of functionalized two-dimensional (2D) diamond for spin-dependent electronic devices using first-principles calculations. Specifically, we investigate functionalizations with either hydroxyl (−OH) or fluorine (−F) groups. In the case of an isolated layer, we observe that the quantity and distribution of (−OH) or (−F) on the 2D diamond surface significantly influence the sp 2/sp 3 ratio of the carbon atoms in the layer. As the coverage is reduced, both the band gap and magnetic moment decrease. When the 2D diamond is placed between gold contacts and functionalized with (−OH), it results in a device with lower resistance compared to the (−F) functionalization. We predict that the maximum current achieved in the device increases with decreasing (−OH) surface coverage, while the opposite behavior occurs for (−F). Additionally, the surface coverage alone can alter the direction of current rectification in (−F) functionalized 2D diamonds. For all studied systems, a single spin component contributes to the total current for certain values of applied bias, indicating a spin filter behavior.

Osteosarcoma is the most common type of bone cancer. Despite therapeutic progress, survival rates for metastatic cases or that do not respond well to chemotherapy remain in the 30% range. In this sense, the use of nanotechnology to develop targeted and more effective therapies is a promising tool in the fight against cancer. Nanostructured hydroxyapatite, due to its biocompatibility and the wide possibility of functionalization, is an interesting material to design nanoplatforms for targeted drug delivery. These platforms have the potential to enable the use of natural substances in the fight against cancer, such as curcumin. Curcumin is a polyphenol with promising properties in treating various types of cancer, including osteosarcoma. In this work, hydroxyapatite (n-HA) nanorods synthesized by the hydrothermal method were investigated as a carrier for curcumin. For this, first-principle calculations based on the Density Functional Theory (DFT) were performed, in which the modification of curcumin (CM) with the coupling agent (3-aminopropyl) triethoxysilane (APTES) was theoretically evaluated. Curcumin was incorporated in n-HA and the drug loading stability was evaluated by leaching test. Samples were characterized by a multi-techniques approach, including Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV–Vis), X-ray diffraction (XRD), X-ray fluorescence spectrometry (FRX), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), zeta potential analysis (ζ), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results show that n-HAs with a 90 nm average size were obtained and successful incorporation of curcumin in the nanostructure was achieved. Cell viability and the number of osteosarcoma cells were decreased by CMAP-HA treatment. Furthermore, the stability test suggests that hydroxyapatite nanoparticles present great potential for the transportation of curcumin in the bloodstream, crediting this system for biological performance evaluations aiming at the treatment of osteosarcomas. Keywords: nanostructures, curcumin, hydroxyapatite, osteosarcoma.

Osteosarcoma is the most common type of bone cancer. Despite therapeutic progress, survival rates for metastatic cases or that do not respond well to chemotherapy remain in the 30% range. In this sense, the use of nanotechnology to develop targeted and more effective therapies is a promising tool in the fight against cancer. Nanostructured hydroxyapatite, due to its biocompatibility and the wide possibility of functionalization, is an interesting material to design nanoplatforms for targeted drug delivery. These platforms have the potential to enable the use of natural substances in the fight against cancer, such as curcumin. Curcumin is a polyphenol with promising properties in treating various types of cancer, including osteosarcoma. In this work, hydroxyapatite (n-HA) nanorods synthesized by the hydrothermal method were investigated as a carrier for curcumin. For this, first-principle calculations based on the Density Functional Theory (DFT) were performed, in which the modification of curcumin (CM) with the coupling agent (3-aminopropyl) triethoxysilane (APTES) was theoretically evaluated. Curcumin was incorporated in n-HA and the drug loading stability was evaluated by leaching test. Samples were characterized by a multi-techniques approach, including Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV–Vis), X-ray diffraction (XRD), X-ray fluorescence spectrometry (FRX), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), zeta potential analysis (ζ), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results show that n-HAs with a 90 nm average size were obtained and successful incorporation of curcumin in the nanostructure was achieved. Cell viability and the number of osteosarcoma cells were decreased by CMAP-HA treatment. Furthermore, the stability test suggests that hydroxyapatite nanoparticles present great potential for the transportation of curcumin in the bloodstream, crediting this system for biological performance evaluations aiming at the treatment of osteosarcomas. Keywords: nanostructures, curcumin, hydroxyapatite, osteosarcoma.

Moiré superlattices of two-dimensional heterostructures arose as a new platform to investigate emergent behaviour in quantum solids with unprecedented tunability. To glean insights into the physics of these systems, it is paramount to discover new probes of the moiré potential and moiré minibands, as well as their dependence on external tuning parameters. Hydrostatic pressure is a powerful control parameter, since it allows to continuously and reversibly enhance the moiré potential. Here we use high pressure to tune the minibands in a rotationally aligned MoS2/WSe2 moiré heterostructure, and show that their evolution can be probed via moiré phonons. The latter are Raman-inactive phonons from the individual layers that are activated by the moiré potential. Moiré phonons manifest themselves as satellite Raman peaks arising exclusively from the heterostructure region, increasing in intensity and frequency under applied pressure. Further theoretical analysis reveals that their scattering rate is directly connected to the moiré potential strength. By comparing the experimental and calculated pressure-induced enhancement, we obtain numerical estimates for the moiré potential amplitude and its pressure dependence. The present work establishes moiré phonons as a sensitive probe of the moiré potential as well as the electronic structures of moiré systems.

This article aimed to verify the space occupied by contemporary art in the regular education curriculum since the launching of the Laws of Guidelines and Bases of National Education (LDB) of 1996, the emergence and application of the Curriculum Parameters of Art/PCN, 2000. Through documentary research, it was possible to observe that there are suggestions for proposals and there is a lack of more clarity and guidance for the teachers. In the bibliographical research, the lack of research on the part of the teacher inn highlighted and there is a need for continuing education so that the student has access to methodological guidelines with the possibility of new perpectives that dialogues with their daily lives.

In this work we apply first principles calculations to investigate the stability trends of mixed boron, nitrogen and carbon diamondol-like compounds. Several distinct geometric models are tested by varying the stoichiometry and position of boron and nitrogen dopants. We verify the special stability of a complete boron nitride compound – the bonitrol –, and we show that carbon substitutions in the bonitrol structure may also lead to stable systems. The electronic characterization of the resulting compounds indicates a rich phenomenology, with metallic, semimetallic, half-metallic and semiconducting behaviors.

Vermiculite samples were impregnated with different amounts of calcium oxide by the conventional thermal heating technique and subject to CO2 capture experiments in thermal analysis equipment. The amount of CO2 captured by calcium oxide increased from 13 g of CO2 per mol of CaO to 16.8 g of CO2 per mol of CaO when the experiments were carried out with pure calcium oxide and vermiculite impregnated with CaO (1:1), respectively. Integral isoconversional methods of Kissinger-Akahira-Sunose (KAS) and Osawa-Flynn-Wall (OFW) were used for the kinetic study of the process and good correlation coefficients were achieved. The apparent activation energy values showed that for low conversions (α < 0.3) the controlling step of the process is a mixed step where the chemical reaction and the diffusion of the reagents into the vermiculite have rates of the same order of magnitude (20 kJ < Ea < 40 kJ). For higher conversions values (α > 0.3) the apparent activation energy values suggest that the slow step is a chemical step (Ea> 40 kJ).

Nickel (Ni) and cobalt (Co) are relevant technological metals for the future of the lithium-ion battery (LIB) industry. Based on the current and projected demand for these, an increased interest in developing processing routes to exploit lateritic occurrences has been observed, as these are reported as critical raw materials for future mineral–metallurgical industry. However, the content of Ni and Co in such ores is minimal and requires impracticable mineral-processing operations for concentration before metal extraction. It was identified that information regarding the sulfation roasting of this material is scarce on what concerns the iron sulfates interaction as a function of the temperature. Based on that context, the present work has its purposes associated with the proposition of an alternative chemical pretreatment to upgrade the content of metals of technological interest in lateritic ores through a simple roast–leach process. Thus, the chemical interactions between the mineral sample and iron (III) sulfate (Fe2 (SO4 )3 ) through thermodynamic simulations and experimental procedures were explored. The latter included specific water leaching practices for the selective concentration of metals. The equilibrium calculations indicate that Fe2 (SO4 )3 and FeSO4 tend to decompose at lower temperatures, and considering the higher stability of other metal sulfates, it could be an interesting reagent in this type of process. Regarding the experimental results, the characterization of materials indicates a recovery of Co as high as 73.4 wt.% after sulfation roasting at 500 ◦C followed by water leaching, with the full content of Iron (Fe) being reported in the insoluble phase. Based on these findings, the present development could be an interesting alternative to consider within operations for the chemical upgrade of cobalt in such types of mineralogical occurrences.

Flubendazole (FBZ) is a poorly water-soluble drug, and different methodologies have been proposed to improve its oral bioavailability. Obtaining the amorphous drug phase is an alternative to improve its water solubility. Several techniques for drug amorphization, such as spray drying, lyophilization, melt quenching, solvent-evaporation, and ball milling, can yield various types of structural disorder and possibly render variations in physicochemical properties. Herein, we focus on evaluating the influence of the ball-milling process on the amorphization of FBZ. The characterization of the average global and local structures before, during, and after the milling process is described by sequential Rietveld refinements, pair distribution function analysis, and the Reverse Monte Carlo method. We show that preserving the local structure (nearest molecules) can be responsible for avoiding the fast structure recrystallization commonly observed when using the solvent-evaporation process for the studied drug.

This study aims to unveil the heterogeneous impacts of import product diversification and institutional factors for achieving energy efficiency in Organization for Economic Co-operation and Development (OECD) countries. In doing so, the study employs robust econometric techniques such as Fully modified ordinary least squares (FMOLS) co-integration, pooled Ordinary Least Squares (OLS), Feasible Generalized Least Squares (FGLS), pool mean group regressions, fixed effects, and random effects for panel data from 1990 to 2015 for selected OECD countries. The detailed empirical outcomes suggest that import product diversification is conducive to reducing the energy and carbon intensity (improvement in energy efficiency) in OECD countries. The empirical conclusions provide various guidelines to achieve cleaner and greener growth and align with various Sustainable Development Goals (SDG 7: Affordable and clean energy, SDG 9: Industry, innovation, and infrastructure, and SDG 13: Climate action) of OECD countries. The paper elaborates fruitful policy suggestions regarding the diversification of imports and energy use-carbon emission-nexus for the OECD member nations. Based on the findings, policymakers and environmental scientists should strengthen the trade-energy and import portfolio policies to attain energy efficiency.

The Organization for Economic Co-operation and Development (OECD) economies face the challenges of rising energy demand, urbanization, and growing environmental issues (rising ecological footprint and less biodiversity). The primary objective of this article is to explore the role of environmental taxes and economic growth on the growing ecological footprint in 29 OECD economies. The autoregressive distributed lag (ARDL) approach and the related intermediate estimators are used to attain the purpose. The two substitute single equation estimators, DOLS, FMOLS, and fixed effect, are also employed to check the robustness of the ARDL estimator. Empirical results reveal that environmental-related taxes, economic growth, foreign direct investment, energy use, urbanization, renewable energy, and industrialization significantly influence the long-term ecological footprint in OECD countries. The dynamics of the studied variables got changed when time is considered. In the short-term, these dynamics are mixed while staying similar in the long-term across the OECD countries. This is attributed to varying levels of renewable energy use and industrialization progress in OECD countries. The empirical conclusions suggest that OECD economies need careful monitoring of environmental regulations for energy usage policies and cleaner production goals.

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.

This paper addresses the general and challenging Sports Timetabling Problem proposed during the International Timetabling Competition of 2021 (ITC2021). The problem is expressed in a flexible format which enables modeling a number of real-world constraints that often occur in Sports Timetabling. An integer programming (IP) formulation and a fix-and-optimize heuristic are proposed to address the problem. The fix-and-optimize approach uses the IP formulation to heuristically decompose the problem into sub-problems and efficiently search on very large neighborhoods. The diverse ITC2021 benchmark instances were used to evaluate the proposed methods. The formulation resulted in proven optimal solutions for two instances. However, it failed to produce feasible solutions for most instances. The proposed fix-and-optimize, which uses an automatic sub-problem size calibration strategy, resulted in feasible solutions for 37 out of the 45 ITC2021 instances. Among these solutions, four are the best known in the literature. The proposed approach participated in the ITC2021 and was one of the finalists.

In the present work, we apply a microfluidic channel platform to study mechanical and adhesion properties of suspended graphene in contact with oleic acid (a lipid). In the platform, one side of the suspended graphene, atop a window in a fluidic channel, is placed in contact with the lipid, and the mechanical response of graphene is experimentally accessed with an atomic force microscope probe. We observe a strong effect arising from the presence of oleic acid: the probe undergoes a large jump-to-contact effect, being pulled and partially encapsulated by graphene, in a phagocytosis-like phenomenon, until it penetrates 0.2 µm into graphene. In contrast, such encapsulation effect is negligible in the absence of oleic acid in the channel, with probe penetration of less than 0.02 µm. The lipid-induced encapsulation effect is observed to occur concurrently with graphene delamination from the window walls. Molecular dynamics simulations and continuum mechanics analytical modeling are also performed, the latter allowing quantitative fittings to the experiments.

Phyllosilicate minerals, which form a class of naturally occurring layered materials (LMs), have been recently considered as a low-cost source of two-dimensional (2D) materials. Clinochlore [Mg5Al(AlSi3)O10(OH)8] is one of the most abundant phyllosilicate minerals in nature, exhibiting the capability to be mechanically exfoliated down to a few layers. An important characteristic of clinochlore is the natural occurrence of defects and impurities which can strongly affect their optoelectronic properties, possibly in technologically interesting ways. In the present work, we carry out a thorough investigation of the clinochlore structure on both bulk and 2D exfoliated forms, discussing its optical features and the influence of the insertion of impurities on its macroscopic properties. Several experimental techniques are employed, followed by theoretical first-principles calculations considering several types of naturally-ocurring transition metal impurities in the mineral lattice and their effect on electronic and optical properties. We demonstrate the existence of requirements concerning surface quality and insulating properties of clinochlore that are mandatory for its suitable application in nanoelectronic devices. The results presented in this work provide important informations for clinochlore potential applications and establish a basis for further works that intend to optimize its properties to relevant 2D technological applications through defect engineering.

The FDA-approved anthelmintic flubendazole has shown potential to be repositioned to treat cancer and dry macular degeneration; however, its poor water solubility limits its use. Amorphous solid dispersions may overcome this challenge, but the balance of excipients may impact the preparation method and drug release. The purpose of this study was to evaluate the influence of adjuvants and drug loading on the development of an amorphous solid dispersion of flubendazole-copovidone by hot-melt extrusion. The drug, copovidone, and adjuvants (magnesium stearate and hydroxypropyl cellulose) mixtures were statistically designed, and the process was performed in a twin-screw extruder. The study showed that flubendazole and copovidone mixtures were highly extrudable, except when drug loading was high (>40%). Furthermore, magnesium stearate positively impacted the extrusion and was more effective than hydroxypropyl cellulose. The extruded materials were evaluated by modulated differential scanning calorimetry and X-ray powder diffraction, obtaining positive amorphization and physical stability results. Pair distribution function analysis indicated the presence of drug-rich domains with medium-range order structure and no evidence of polymer-drug interaction. All extrudates presented faster dissolution (HCl, pH 1.2) than pure flubendazole, and both adjuvants had a notable influence on the dissolution rate. In conclusion, hot-melt extrusion may be a viable option to obtain stable flubendazole:copovidone amorphous dispersions.

Nano-talc was successfully incorporated in the hydroxyapatite matrix via pulsed electrodeposition after being obtained using an eco-friendly liquid-phase exfoliation process. Scanning electron microscopy, atomic force microscopy, X-ray spectroscopy, Raman spectroscopy, corrosion and wear resistance, and cytocompatibility tests were used to characterize the biocomposite ceramics. Talc significantly improves the nanomechanical and wear properties of bioceramics (i.e., higher stiffness, reduced friction coefficient, and lower wear damage) as well as corrosion resistance. Talc does not induce cytotoxic activity in in vitro cells and may induce bone maturation as per biocompatibility tests.

In this study, for the first time, caffeine and citrulline were used as fuels for the synthesis of the spinel ferrite CoFe2O4 by gel combustion. The influence of the oxidizer to fuel molar ratio (φ) on the synthesis of cobalt ferrite was studied. X-Ray Diffraction (XRD) showed that the spinel phase was obtained in all the combustions, but the use of caffeine as fuel allowed it to be obtained with high purity, while in the other combustions CoO appeared as a secondary phase due to changes in the reaction. Furthermore, the crystallite size was estimated using the Scherrer equation and considering the plane (311), finding it to be in the range of 32–40 nm, and increasing as the amount of fuel was increased. In addition, the adiabatic flame temperatures were estimated, finding that, in the synthesis with φ = 0.7, the flame temperatures were 1974 K and 1711 K, for the caffeine and citrulline respectively, which could be sufficient to obtain the phase in one stage. The ignition temperatures identified by DSC/TG thermal analysis for caffeine and citrulline samples with φ = 1.0 were 297 and 191 °C, respectively, which are in the range of traditional fuels. The morphology was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which revealed that the particles were agglomerated as a result of high reaction temperatures. The magnetic properties identified by the vibrating sample magnetometer (VSM) for the sample with caffeine and ratio φ = 0.7 were saturation magnetization Ms = 95.16 emu g−1, coercivity field Hc = 710.76 Oe and remanent magnetization Mr = 44.86 emu g−1. Meanwhile, with citrulline and ratio φ = 0.7, the properties were saturation magnetization Ms = 59.14 emu g−1, coercivity field Hc 837.15 Oe and remanent magnetization Mr = 32.30 emu g−1. It should be pointed out that the high saturation magnetization values obtained with caffeine fuel exceed those reported with traditional fuels. The obtained results allow us to infer that these fuels could be used as alternatives in synthesizing inorganic oxides by combustion in one step.

Resumo

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 low energy range. The stoichiometry and distribution of the homopolar bonds in the edges change the absorption, reflectance, refractive index, and optical conductivity of nanoribbons, which may allow the tuning of those properties. Regarding the absorption in the low energy 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.

Abstract: The incorporation of nanoparticles on polymer films is possible to obtain materials with desired properties. In the present work, we address the physical-chemical influence of nanoparticles in polymer films by producing and characterizing polyaniline hybrids with SiO2 and Au nanoparticles and comparing them with films with TiO2 nanoparticles. The hybrid films were characterized by SEM, EDS, UV-Vis, AFM, Raman, and cyclic voltammetry. Unlike TiO2 nanoparticles, SiO2 and Au nanoparticles do not promote any noticeable change in polyaniline oxidation state in less acid environments (pH 5.9 and 6.15). However, in those environments, the presence of nanoparticles significantly increases the film's conductivity. At a pH of 1.5 and 3.9, all three kinds of nanoparticles are screened by ions from the solution diminishing their physical-chemical effects on polyaniline. Thus, our results suggest that, in general, nanoparticles don't have any physical-chemical effects on polyaniline films when deposited in acid enough environments but can change their physical and chemical properties when deposited in less acid environments.

High precision and accuracy make Pb-Fire assay the method of choice for gold analysis in mineralogical samples. The second stage of this method, called cupellation, leaves the used container (cupel) highly contaminated with PbO. Since tons of cupel waste are generated annually from gold analysis worldwide, the disposal of such material constitutes a serious risk to the environment. In the present paper the recovery of the lead from cupel waste by means of an alkaline fusion in the presence of sulfur was evaluated considering the effects of the following variables: amount of NaOH and sulfur, time, and temperature. Gravimetric analyses indicated 81.3% (w/w) recovery of lead in the form of metallic lead from 5.00 g of cupel waste using 3.00 g of NaOH, 0.5 g of S8, after 15 min at 650 °C. During the process, sulfur promoted the reduction of lead oxide. After the process, both the cupel wastes and the resulting secondary wastes presented lead concentrations below the maximum limits determined by both Brazilian legislation and that followed by US Environmental Protection Agency, and can be considered safe for disposal. Furthermore, the proposed method allows cupel wastes to be converted from an environmental liability to a raw material for the production of metallic Pb.

Structural, morphological, magnetic, and electrical properties of the challenging Sr1-xBaxMnO3 (x=0, 0.4) manganite are discussed. Polycrystalline Sr1-xBaxMnO3 samples were prepared via the standard solid-state reaction. Conventional X-ray diffraction and synchrotron radiation measurements showed the hexagonal structure (space group P63/mmc) of the samples. The stability of the hexagonal symmetry of Sr0.6Ba0.4MnO3 persisted up to 120 K. This result, along with the fact that the space group P63/mmc is centrosymmetric, discounted the possibility of having a long-range ferroelectric ordering. Pristine SrMnO3 samples exhibited an antiferromagnetic transition at a Néel temperature ∼280 K. In turn, Sr0.6Ba0.4MnO3 showed two transitions at ∼325 K and ∼270 K. Measurements of the electrical polarization versus the electric field showed closed loops, although visually distinct from those of a true ferroelectric material. Hence it was evident that spurious effects caused the polarization curves that resembled ferroelectric loops. Resistivity measurements on Sr0.6Ba0.4MnO3 showed the insulating nature of these samples.

The development of indexes for human development and environmental sustainability issues are an emerging topic in the current literature. However, the literature has put less emphasis on municipal indexes, which is the focus of this research. In this paper, we considered municipal environmental management as the adoption of environmental activities and the development of infrastructural and technical capacities in municipalities. This article aims to create a sustainable human development index with municipal data from the state of São Paulo in Brazil. Using information from the Municipal Human Development Index (IDHm) and the GreenBlue Municipal Program (PMVA), we applied the data envelopment analysis (DEA) technique to connect human development and environmental sustainability in 645 Brazilian municipalities. Our findings show that regions with higher human development present better DEA scores on the Sustainable Human Development Index. In contrast, regions with a low or a middle level of human development do not present significant change considering both dimensions. Moreover, our findings reveal that PMVA certification has a different and statistically significant impact on the DEA score considering certified, qualified, or not qualified regions. We found similar results for urbanized and service-oriented municipalities. Our indicator is an essential and straightforward tool for regional policymakers, helping to allocate resources and to find human development and environmental sustainability benchmarks among developing regions.

Calcium phosphates are biomaterials widely used in bone tissue engineering. In recent years, the alternative of obtaining these materials with antimicrobial properties, has been explored due to the multiple advantages that this would imply in the design of devices or implants that prevent the failure of these associated with bacterial colonization. The goal of the present work was obtaining gold nanoparticles supported on biphasic calcium phosphates (BCPs) with high crystallinity by one-step solution combustion technique, and with antimicrobial response, a fact that can significantly reduce the production cost of these materials. X-ray diffractograms (XRD) showed that prepared powders have high crystallinity owing to high temperatures during the combustion reaction, also Rietveld refinement showed that the inclusion of gold nanoparticles (AuNPs) influenced the phases’ ratio obtained. Furthermore, scanning electron microscopy (SEM) showed agglomeration of particles with morphologies with shape tending to be equigranular, while the presence of AuNPs was corroborated by transmission electron microscopy (TEM). All samples that were obtained in a single step, by solution combustion, showed antimicrobial behavior validated through the inhibition halos, whereas particles subjected to thermal treatment lost their antimicrobial response. Resumen Los fosfatos de calcio son biomateriales ampliamente usados en ingeniería de tejido óseo. En los últimos años, la alternativa de obtener estos materiales con propiedades antimicrobianas ha sido explorada debido a las múltiples ventajas que presentan en el diseño de dispositivos o implantes que incluyan la prevención de fallas asociadas a la colonización bacteriana. El principal objetivo de esta investigación fue obtener nanopartículas de oro soportadas en fosfatos de calcio bifásicos bien cristalizados en una sola etapa mediante la técnica de combustión de soluciones y con respuesta antimicrobiana, un hecho que puede significar la reducción del coste de producción de estos materiales. Los difractogramas de rayos X evidenciaron que los polvos preparados presentaron una alta cristalinidad debido a las altas temperaturas durante la reacción de combustión. El refinamiento Rietveld mostró que la inclusión de las nanopartículas de oro influenciaron la relación de las fases obtenidas. La microscopia electrónica de barrido mostró la aglomeración de partículas con morfologías tendentes a ser equigranulares. La presencia de nanopartículas de oro fue corroborada mediante microscopia electrónica de transmisión. Todas las muestras que fueron obtenidas en un solo paso mediante la combustión de soluciones mostraron un comportamiento antimicrobiano validado a través de halos de inhibición, mientras que, en las partículas sometidas a tratamiento térmico, este comportamiento estuvo ausente.

The levitation of samples in an acoustic field has been of interest in the preparation and study of amorphous solid dispersions (ASD). Here, niclosamide-polymer solutions were levitated in a multi-emitter single-axis acoustic levitator and analyzed for 10 min at a High-resolution synchrotron X-ray powder diffraction beamline. This assembly enabled high-quality and fast time-resolved measurements with microliter sample size and measurement of solvent evaporation and recrystallization of niclosamide (NCL). Polymers HPMCP-55S, HPMCP-50, HPMCP-55, Klucel®, and poloxamers were not able to form amorphous dispersions with NCL. Plasdone® and Soluplus® demonstrated excellent properties to form NCL amorphous dispersions, with the last showing superior solubility enhancement. Furthermore, this fast levitation polymer screening showed good agreement with results obtained by conventional solvent evaporation screening evaluated for five days in a stability study, carried out at 40 °C/75% RH. The study showed that acoustic levitation and high-resolution synchrotron combination opens up a new horizon with great potential for accelerating ASD formulation screening and analysis.

We use X-ray pair distribution function (PDF) analysis applied to high-energy synchrotron X-ray powder diffraction data to evaluate the amorphous solid dispersions interactions and their aging stability. The obtained systems are based on hydroxypropyl methylcellulose (hypromellose) derivatives and flubendazole (FBZ) drug dispersions prepared using a spray-dryer technique. We carry out stability studies under aging parameters (40 °C/75% relative humidity) to tune the systems’ recrystallization. The results reveal that ion-base interactions between the drug-polymer matrix are responsible for reducing clustering processes yielding slower recrystallization and different ordering in the hypromellose phthalate (HPMCP/FBZ) and hypromellose acetate succinate (HPMC-AS/FBZ) systems and complete drug clustering in hypromellose (HPMC-E3/FBZ). The structural ordering was accessed using differential X-ray PDFs that revealed the region between 3.5 Å and 5.0 Å could be related to FBZ intermolecular interactions and is more ordered for the least stable system (HPMC-E3/FBZ) and less ordered for the most stable system (HPMCP/FBZ). These results show that the ion-base interactions between drug and matrix occur at these intermolecular distances.

Este artigo é uma reflexão sobre as atividades experienciais do cotidiano da escola e da sala de aula. Utilizou-se como tema discutir a interdisciplinaridade da música com as outras linguagens artísticas e com outras áreas de conhecimento que permeiam o currículo escolar, objetivando introduzir o cotidiano da escola como conteúdo a ser explorado e estudado cientificamente como apontam (NÓVOA, 1995; COUTINHO, 2012; FAZENDA, 2012), retirando destas vivências no espaço escolar, a característica de trivialidade do fazer. O fazer na sala de aula é sistematizado, baseado em um currículo geralmente fechado, rígido, no entanto, esse fazer na escola é carente da visão e representação científica. Utilizou-se duas imagens para representar o fazer da educação, uma representando a culminância das atividades relacionadas aos festejos juninos na escola e outra imagem (a fotografia de uma pintura/tela/quadro) realizada num espaço informal (Ong) de ensino de arte. A abordagem é a da mestiçagem da/na arte, a interdisciplinaridade (FAZENDA, 1993; 2012), que por vezes está ligada às atividades realizadas na sala de aula. A Arte na escola (Artes Visuais, Teatro, Música, Dança) está definida enquanto componente curricular, mas no seu fazer, as linguagens desse componente se entrelaçam, se utilizam umas das outras – é a interdisciplinaridade. Do resultado desse entrelaçamento, surgem a mestiçagem e o hibridismo na arte. Como manter a identidade na/da arte diante disso? Objetiva-se problematizar o cotidiano escolar e tecer algumas considerações acerca de conceitos relacionados à prática artística como a mestiçagem, a interdisciplinaridade e o hibridismo na/da arte e a polivalência.

Calcium carbonate (CaCO3) from the seaweed Lithothamnium calcareum is a suitable dietary supplement for the prevention of osteoporosis, due to its chemical composition. This study compared CaCO3 from L. calcareum to CaCO3 from oyster shell and inorganic minerals that are already used in the pharmaceutical industry. The Rietveld refinement of the XRD showed that the mineral fraction of L. calcareum is composed of aragonite (50.3 wt%), magnesian calcite (45.3 wt%), calcite (4.4 wt%), comin contrast to oyster shell and inorganic minerals, which contain only calcite. The morphology of L. calcareum carbonate particles is granular xenomorphic, which is distinct from the scalenohedral form of inorganic calcite and the fibrous and scale-like fragments of oyster shell. The crystal structures of aragonite and magnesian calcite, present in L. calcareum, have higher contents of oligoelements than the pure calcite in other materials. The isotopic composition (stable isotopes of carbon and oxygen) is heavy in the CaCO3 from L. calcareum (δ13C = 1.1‰; δ18O = −0.1‰) and oyster shell (δ13C = −4‰; δ18O = −2.8‰) in marked contrast to the much lighter isotopic composition of inorganic mineral CaCO3 (δ13C = −19.2‰; δ18O = −26.3‰). The differences indicated above were determined through principal component analysis, where the first and second principal components are sufficient for the clear distinction and traceability of CaCO3 sources.

One of the most difficult tasks that economies face is how to generate economic growth without causing environmental damage. Research in economic complexity has provided new methods to reveal structural constraints and opportunities for green economic diversification and sophistication, as well as the effects of economic complexity on environmental pollution indicators. However, no research so far has compared the ecological efficiency of countries with similar productive structures and levels of economic complexity, and used this information to identify the best learning partners. This matters, because there are substantial differences in the environmental damage caused by the same product in different countries, and green diversification needs to be complemented by substantial efficiency improvements of existing products. In this article, we use data on 774 different types of exports, CO2 emissions, and the ecological footprint of 99 countries to create first a relative ecological pollution ranking (REPR). Then, we use methods from network science to reveal a benchmark network of the best learning partners based on country pairs with a large extent of export similarity, yet significant differences in pollution values. This is important because it helps to reveal adequate benchmark countries for efficiency improvements and sustainable production, considering that countries may specialize in substantially different types of economic activities. Finally, the article i) illustrates large efficiency improvements within current global output levels, ii) helps to identify countries that can best learn from each other, and iii) improves the information base in international negotiations for the sake of a cleaner global production system.

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.

In this study, CaCu3Ti4O12 ceramic composites were prepared through solid-state reaction by adding Sr2+ and removing Cu2+. Application of the Rietveld method and structure refinement revealed the presence of pure CaCu3Ti4O12 (CCTO) phase for x = 0.00 and Sr0.75Ca0.25TiO3 (SCTO) phase for sample x = 3.00. The other samples presented a mixture of both phases. The sample microstructures showed that increasing the amount of SCTO phase led to the formation of cubic CCTO grains. The x = 0.15 sample presented giant dielectric permittivity results, 3.28 × 105, associated with increased grain size and greater grain boundary capacitance, thus indicating it could be a promising material for class III capacitors. On the other hand, greater presence of the SCTO phase displayed potential non-ohmic behavior, as seen with sample x = 2.70, which has a high nonlinear coefficient (α ∼ 30.0) and low current leakage, (IL ∼ 9.0 μA).

There is much discussion on the non-linear relationship between economic growth and carbon dioxide (CO2) emissions. Additionally, the effects of Foreign Direct Investment (FDI) on the environment are ambiguous, as both beneficial (i.e., pollution-halo) and harmful (i.e., pollution-haven) effects were found. Therefore, the literature presents no consensus on either of these topics. This is especially problematic for developing regions, as these regions represent growing economies interested in receiving foreign investments, and their CO2-related research is limited. This study aims to understand the impacts of economic growth and FDI on the CO2 emissions of São Paulo state, Brazil. To perform this study, a unique dataset on regional FDI was built, and 592 municipalities were included. The analyses combine linear and non-linear estimations, and the results suggest a non-linear relationship between Gross Domestic Product (GDP) per capita and CO2 emissions, along with a negative association between FDI and CO2. Finally, this study discusses possible policy implications and contributes to the international literature.

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.

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.

Music can reduce stress and anxiety, enhance positive mood, and facilitate social bonding. However, little is known about the role of music and related personal or cultural (individualistic vs. collectivistic) variables in maintaining wellbeing during times of stress and social isolation as imposed by the COVID-19 crisis. In an online questionnaire, administered in 11 countries (Argentina, Brazil, China, Colombia, Italy, Mexico, the Netherlands, Norway, Spain, the UK, and USA, N = 5,619), participants rated the relevance of wellbeing goals during the pandemic, and the effectiveness of different activities in obtaining these goals. Music was found to be the most effective activity for three out of five wellbeing goals: enjoyment, venting negative emotions, and self-connection. For diversion, music was equally good as entertainment, while it was second best to create a sense of togetherness, after socialization. This result was evident across different countries and gender, with minor effects of age on specific goals, and a clear effect of the importance of music in people's lives. Cultural effects were generally small and surfaced mainly in the use of music to obtain a sense of togetherness. Interestingly, culture moderated the use of negatively valenced and nostalgic music for those higher in distress.

Research on economic diversification and complexity has made significant advances in understanding economic development processes, but has only recently explored environmental and social sustainability considerations. In this article we evaluate the current state of this emerging literature and reveal 13 research gaps. A total of 35 different keywords and methods from structured literature reviews and network science helped to identify 374 scientific articles between 1988 and 2020 and revealed a fragmented research landscape around three larger network communities: (1) industrial policies, climate change, and green growth; (2) economic complexity and its association with inequality and environmental sustainability; and (3) economic diversification, including studies on livelihood diversification in poor areas. Economic complexity research applies new empirical methods and considers both social and environmental sustainability, but seldom scrutinizes theory and policy. Industrial policy research focuses on green growth policies but tends to omit social sustainability issues and advanced empirical methods. Research on economic diversification in poor regions provides insights on the livelihood diversification of farmers, but is disconnected from the economic complexity and industrial policy research. This review helps to summarize the main contributions and shows pathways for potential mutual learning between these communities for the sake of sustainable development.

We investigate the local atomic structure of verapamil hydrochloride in the amorphous state (a-VRPH) using the pair distribution function (PDF) and Reverse Monte Carlo (RMC) methods. We obtain the a-VRPH sample from its crystalline counterpart (c-VRPH) using the solvent evaporation technique. From the measured X-ray powder diffraction (XRPD) data for a-VRPH and c-VRPH, two total structure factors S(Q) are derived, and Fourier transforming them, two total reduced distribution functions, γ(R), are obtained. We refine the XRPD pattern of c-VRPH using the Rietveld method to confirm the sample's crystal structure is the pure c-VRPH. The partial Sij(Q) factors and PDF functions are simulated based on the VRPH crystal structure found in the Cambridge Structural Database® (CSD). The PDF and RMC analyses allow us to observe some similarities between a-VRPH and c-VRPH at the intramolecular level and the main differences at the intermolecular level induced by the amorphization process.

Hydrogen reduction and thermal treatment experiments were carried out in the laboratory using a transition zone lateritic nickel ore. The products of the pyrometallurgical operations were subjected to magnetic separation. The ore and samples produced after the thermal processing (reduction and thermal treatment) were characterized by X-ray diffractometry (XRD), thermogravimetric analysis (TG), scanning electronic microscopy (SEM), and energy dispersive spectrometry (EDS). The qualitative identification of the main mineral transformations was performed and the influence of these thermal transformations in the magnetic properties of the sample was studied. When the reduction experiments were performed at 800 ° C, with a magnetic flux of 97.5 ± 10.6 mT, the nickel content increased by up to 33 % (recovery of ≈ 75 %) in the magnetic fraction. During the formation of magnetite in the reduction experiments, carried out at 400°C, the sample became very magnetic and, consequently, the unit operation of magnetic separation was not selective. It was possible to remove magnesium from all samples, regardless of the thermal treatment or reduction temperature used. The contents of this element were adjusted to the characteristic values of a limonitic ore.

This paper presents a Fix-and-Optimize approach for the Unrelated Parallel Machine Scheduling Problem (UPMSP). In short, the UPMSP consists of assigning jobs to unrelated parallel machines where different processing times incur for the same job in different machines. Additionally, a setup time is considered between the execution of jobs in the same machine. Fix-and-Optimize is a matheuristic that iteratively selects a subset of variables to be fixed to their current values so that the remaining variables will compose a sub-problem to be optimized by an integer programming solver. In the proposed approach, each sub-problem consists of a subset of jobs that are assigned to a subset of machines in the incumbent solution. In the conducted experiments on benchmark instances, the proposed Fix-and-Optimize algorithm achieved remarkable results. It outperformed two state-of-the-art exact approaches to the UPMSP and achieved competitive results when compared to the literature’s best performing heuristic method for this problem.

The Aptian evaporitic transitional sequence (sag phase) of the Brazilian marginal basins records the first connection between the Central and South Atlantic oceans in the equatorial area. During this phase, lacustrine carbonate reservoirs and giant salt deposits developed in the southern basins of Santos and Campos, forming world‐class petroleum reservoirs. The sag succession is also well‐preserved in the interior rift basins of north‐eastern Brazil, where upper Aptian strata are represented by a continuous section. This contribution presents an interpretation of the evolution of a third‐order depositional sequence comprising lacustrine limestones, marine siliciclastic facies and evaporite deposits of the intracontinental Araripe Basin. The Lowstand Systems Tract is characterized by fluvial deposits filling accommodation generated during the syn‐rift phase. The overlying deposits comprise marine facies with preservation of dinoflagellates and marine ichnotaxa, evidencing marine deposition in bayhead delta settings. The transgressive surface is represented by limestones, including the Konservat–Lagerstätte laminites, onlapping the basement rocks. Above, tide‐dominated bay deposits with distinct subtidal, intertidal and supratidal portions are recorded. The Maximum Flooding Surface is a dark shale below foreshore to shoreface facies, marking the beginning of the Highstand Systems Tract, culminating with deposition of evaporites (gypsum and anhydrite). The stratigraphic architecture and palaeocurrents measured in different facies associations suggest that marine waters reached the basin from the south. The data unequivocally records late Aptian marine ingressions of an incipient South Atlantic Ocean over the interior basins of north‐eastern Brazil, while lacustrine conditions were still prevailing in the Pre‐Salt sag units of the Santos and Campos basins.

Music consumption is widely recognized as an important facet of everyday life, and the use of algorithms by online streaming services to suggest songs has aroused a growing scientific interest in how musical preferences are structured. However, existing studies have failed to include Latin genres of music. Therefore, the aim of this study was to develop and validate a measure to assess the musical preferences of Spanish-speaking teenagers and adults. To do this, two independent studies were developed (N1 = 312 Spanish teenagers; N2 = 345 Spanish-speaking adults) using an instrument based on a theoretical structure consisting of 20 musical genres, which reflects the MUSIC model. The results indicated the exclusion of reggaetón for both groups, and confirmed the proposed theory of five dimensions of musical preferences: (a) Intense: emphasis on low sounds and use of electronic instruments; (b) Sophisticated: complex musical structure, dissonant harmonies, and melodies that explore unconventional patterns and diversified rhythms; (c) Contemporary: striking rhythm, emphasis on percussion and electronic instruments, versatility in the prosodic construction of lyrics, and often linked to themes such as inequality and social injustice; (d) Moving: strong connection to dance, especially partner dances, with strong potential for socialization; (e) Unpretentious: music with strong cultural roots specific to the research context. In conclusion, the Scale for Musical Preferences Assessment proved to be an effective instrument for assessing the musical preferences of teenagers and adults, presenting a standard structure for both groups, although there were differences in their perception of musical genres.

Two of the main challenges presented by the implementation of nickel laterites atmospheric acid leaching are: (i) high acid consumption and (ii) high final iron concentrations in the PLS. In the current work, a novel process was devised by applying pyrometallurgical and bio-hydrometallurgical operations. The experimental set-up comprised the reduction of a nickel limonitic ore with hydrogen gas in a rotary kiln, at 900 °C, until all the goethite was converted to metallic iron. Subsequently, the reduced sample was bioleached by mesophilic microorganisms grown on Fe2+ (Acidithiobacillus ferrooxidans) at 5% solids, 32 °C, and pH < 3. The results showed that an increase in the Eh values, promoted by the bacteria, resulted in the leaching Fe, Ni and Co, therefore a dissolution of 92% of the nickel and 35% of the cobalt was observed in experiments carried out with 35 Kg H2SO4/(ton of the reduced ore). The iron concentration in the liquor generated under these experimental conditions was below 5 mg/L owing to the fact that Fe3+ precipitated as jarosite. The experimental conditions applied also resulted in low acid consumption and the final total iron concentration was also reduced in the leach liquor (< 200 mg/L), which were considerably lower than the values reported for the HPAL process.

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.

Our study examines the impact of student performance level, student gender and content matter on the verbal strategies (literal language, technical instruction and images and metaphors) teachers use in guitar masterclasses. After recording and transcribing 60 guitar masterclasses, of which 40 were selected for the final sample, we operationalised the variables as follows: independent judges evaluated students’ performance levels, and the content taught and the verbal strategies used by teachers were categorised using the software NVivo 10. Statistical tests (two-way ANOVA, the Mann–Whitney U-test and the Kruskal–Wallis test) suggested that the content presented by the teacher may determine the type of verbal strategy used in the classroom. The results indicate that music education research has used images and metaphors as an umbrella concept, and this may hide specificities of the teacher’s verbal discourse.

This work presents a solution to the Frequency Assignment Problem in cellular networks using the memetic algorithm. The Frequency Assignment Problem that will be addressed in this work consists in finding the smallest number of frequencies that must be used in a network so that there is no interference. This problem is proven NP-hard, so it is often impraticable to solve it by exact methods. Therefore, it is necessary to study heuristics approaches to provide good approximations for it, as is the case with evolutionary algorithms. The results obtained by the memetic algorithm proposed in the present work were superior to those of the existing heuristic approaches in the literature, which indicates that it is a promising approach to this problem.

O Problema de Roteamento de Veículos Capacitados visa a atender um conjunto de pedidos (demandas) de clientes dispersos geograficamente por uma frota de veículos homogênea a um custo mínimo. Este trabalho propõe uma abordagem heurística para um problema real de entregas de um supermercado em uma cidade de Minas Gerais. Na abordagem proposta, a construção de soluções iniciais é feita pelo algoritmo adaptado de Clarke & Wright na estrutura GRASP, e o refinamento dessas soluções é feito pela meta-heurística VNS por meio dos movimentos 2-opt e 3-opt. Para validar a abordagem proposta, foram feitos experimentos computacionais sobre os dados de dois dias de entregas do supermercado. Os resultados sugerem uma redução de aproximadamente 34% na distância percorrida pela frota de veículos nos dois dias de estudo em relação ao processo manual de solução adotado pelo supermercado.

This paper addresses the Uncapacitated Single Allocation p-hub Maximal Covering Problem (USApHMCP), which aims to determine the best allocation for the p-hubs within a node network in order to maximize the network coverage. We proposed a search strategy-based heuristic Basic Variable Neighborhood Search (VNS) to solve the problem. Two different sets of test instances from the literature, Civil Aeronautics Board (CAB) and Australian Post (AP), were used to evaluate the performance of VNS and to compare it with the Tabu Search (TS) metaheuristic. In most instances, the bounds obtained by VNS and TS were the same but, on the other hand, for some of them, VNS presented a slight advantage and vice versa. That is, both algorithms are convenient to solve the proposed problem.

This paper studies two-level uncapacitated facility location problems, a class of discrete location problems that consider different hierarchies of facilities and their interactions. Benders reformulations for both single and multiple assignment variants and while several separation procedures for three classes of Benders cuts are presented: standard optimality cuts, lifted optimality cuts, and non-dominated optimality cuts. Extensive computational experiments are performed on difficult and large-scale benchmark instances to assess the performance of the considered separation routines.

Titanium dioxide substrates have been synthesized by means of solid-state reactions with sintering temperatures varying from 1150 °C up to 1350 °C. X-ray diffraction and scanning electron microscopy (SEM) where employed to investigate the crystal structure, grain size and porosity of the resulting samples. The obtained ceramics are tetragonal (rutile phase) with average grain sizes varying from 2.94 µm up to 5.81 µm. The average grain size of samples increases with increasing temperature, while the porosity decreases. The effect of microstructure on the dielectric properties has been also studied. The reduction of porosity of samples significantly improves the dielectric parameters (relative dielectric permittivity and loss tangent) in comparison to those of commercial substrates, indicating that the obtained ceramic substrates could be useful in the miniaturization of telecommunication devices.

Braking performance is dependent on friction materials of tribological components, generally metal and pad. The pad consists of a composite of thermosetting resin and reinforcement material that exhibits mechanical and wear resistant, heat conduction, lubricant, and others. Slate is a natural rock composed of extremely fine materials that brings interesting tribological properties, in addition, its industrial current activity generates a significant amount of mineral waste, which is a problem for the environment. The objective of this work was to propose a technological alternative as a new friction element based on slate particulate as tribological reinforcement in composite based on phenolic resin as a matrix, besides that, minimize the environmental impact due to the inadequate disposal of these slate tailings and add value to the mineral, classifying it as a residue to be used industrially and no longer as waste. In this sense, the effect of the amount of slate on the friction properties of the brake pads made was investigated. As the brake pad material, four different slate containing formulations were proposed, manufactured and analyzed, and as the brake wheel gray iron was chosen. The friction and wear characteristics were determined by Pin-on-Disk type tribological tests, the pair was composed by disk (pad formulations) and pin of gray iron, representing the brake wheel. The coefficients of friction of the composites were shown to be regular and stable, with an average of 0.44 between the samples. Among the results obtained, the formulation containing 40 % of slate and 35 % of phenolic resin, presented the most satisfactory parameters compared to commercial friction materials in current use.

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.

A sample of limonitic nickel ore was characterized by XRD, SEM-EDS, and ICP-OES techniques. The Rietveld refinement method showed that the main mineral constituent of this sample is goethite (55.8 pct). Thermal analysis experiments were performed and the determination of the goethite content in the sample could be confirmed by the mass loss associated to the dehydroxylation of this mineral at temperature of ≈ 150 °C. After thermal decomposition, the sample was reduced in a rotary kiln using hydrogen and subsequent characterization showed that for low temperatures (400 °C ≤ T < 550 °C) the main chemical reaction is the reduction of hematite to magnetite. At high temperatures (500 °C ≤ T < 800 °C), metallic iron could be identified in the solid product of the reaction by XRD technique and reduction of hematite to metallic iron was the main chemical reaction identified at this temperature. In addition to metallic iron, tetrataenite was identified and quantified in the reduced sample at high temperature (T > 600 °C) and the results suggest that most of the nickel is in this mineral phase. The shrinking core model was used for the kinetic studies of the reduction process and for the reduction of hematite to magnetite at low temperature (T ≤ 550 °C). The slow step was diffusion of reagent (H2) or product (H2O) through the reduced solid product layer on the particle surface, the apparent activation energy calculated for the reaction was 46.2 kJ. For the reduction of hematite to metallic iron at high temperature (T ≥ 550 °C), the slow step was the reaction of hydrogen with hematite at the reaction surface of the particle, and the apparent activation energy achieved by the chemical reaction was 29.5 kJ.

Music is considered a vital element in young people’s lives. It functions as an important means for expressing the emotions and feelings they experience in a daily basis. As such, this study explores the music preferences of high school Brazilian students (N = 940), 530 female (56.9%) and 410 male (43.1%) participants between 14 and 20 years old (M = 16.14 years old, SD = 1.22). The main instrument for data collection was the Questionnaire on Musical Style Preferences, which was adapted to the Brazilian context and encompassed 33 different music styles. A principal component analysis resulted in five dimensions representing different musical styles: (1) Intense, (2) Unique, (3) Sophisticated, (4) Contemporary, and (5) Mellow. The results of this study reinforced theory of the five-factor model of musical preference. Results also suggest that Mellow music was the most preferred while Sophisticated music was the least preferred among participants. Regarding gender, male participants showed a greater preference towards Contemporary, Intense, and Sophisticated music, whereas women generally preferred Mellow and Unique. Regarding age, participants under 20 years old showed a greater preference towards Mellow musical styles as compared to older participants. On the one hand, regression analyses showed that preferences towards Intense music decrease with age. On the other hand, gender was a better predictor for music preferences than age. Although the results of this study correspond to those of previous studies, more research studies are necessary to further explain musical preferences within the Brazilian context.

Hydroxyapatite nanoparticles have been investigated as biological agents for the treatment and diagnosis of bone diseases due to their properties, providing high affinity to bone tissues and also due to the possibility to chemically modify the surfaces of these nanoparticles to provide active targeting to bone tumors or other bone disorders. In this work, synthetic hydroxyapatite nanoparticles and their surface modifications with folic and medronic acid were studied. Copper-64 was produced by neutron irradiation in a TRIGA MARK I nuclear reactor, and the functionalized nanoparticles radiolabeled with this radioisotope. The multi-technique characterization includes FTIR, PXRD, TGA, DSC, CHN, Zeta potential, XPS, SEM, TEM, and Gamma spectroscopy. Furthermore, the evaluation of the chemical interaction stability was through leaching tested for efficiency. The results indicate that folic and medronic acids can be covalently bonded to HA surface, producing a new material not yet described in the literature, been stably attached to hydroxyapatite nanoparticle surfaces, able to provide active targeting for bone disorders. The complexation of copper-64 provides high radiochemistry purity, although the specific activity must be improved.

o presente trabalho investiga nos contos “Partida do audaz navegante” e “Sequência”, do livro Primeiras estórias, de  João Guimarãea Rosa, em que medida a linguagem se estrutura como uma narrativa mítica, fundadora de certa realidade. Neste sentido, assumimos com Antônio Cândido (2004), que a análise literária pressupõe o texto como palavra organizada, ou seja, na literatura, o conteúdo só pode atuar por conta de uma forma que o medeia.

A  música  tem  sido  apontada  na  literatura  científica  como  um  meio  eficaz  para  a  regulação  do  estado  de  ânimo.  Partindo  dessa  premissa,  buscamos  nessa  revisão  apresentar  com  clareza  a  concepção  sobre estado de ânimo, abordando os seus tipos e a sua relação com a música. Para tanto, foi realizada uma ampla pesquisa bibliográfica junto a publicações nacionais e internacionais de maior impacto. Além disso, buscou-se  também  contextualizar  essa  discussão  considerando  os  impactos  psicológicos  negativos  causados pela pandemia da COVID-19. Assim, observamos que existem certos tipos de música que tem demonstrado uma capacidade interessante para induzir estados de ânimo positivos, tais como o dance, a música  clássica  e  o  rap.  Ademais,  a  literatura  sugere  que  a  participação  em  atividades  de  escuta  ou  performance musicais, tanto individual ou coletivamente, podem favorecer a redução de emoções negativas (como ansiedade e depressão) e, consequentemente, melhorar o estado de ânimo. Portanto, essas evidências indicam  que  a  música  pode  ser  concebida  como  um  importante  meio  para  combater  os  impactos  psicológicos  causados  pela  pandemia.  Com  isso,  espera-se  que  esse  estudo  possa  incentivar  e  contribuir  para o desenvolvimento de novos estudos acerca da relação entre música e humor.

The control of geometric structure is a key aspect in the interplay between theoretical predictions and experimental realization in the science and applications of nanomaterials. This is particularly important in one-dimensional structures such as nanoribbons, in which the edge morphology dictates most of the electronic behavior in low energy scale. In the present work we demonstrate by means of first principles calculations that the oxidation of few-layer antimonene may lead to an atomic restructuring with formation of ordered multilayer zig-zag nanoribbons. The widths are uniquely determined by the number of layers of the initial structure, allowing the synthesis of ultranarrow ribbons and chains. We also show that the process may be extended to other compounds based on group V elements, such as arsenene. The characterization of the electronic structure of the resulting ribbons shows an important effect of stacking on band gaps and on modulation of electronic behavior.

Low-dimensionality materials are highly susceptible to interfaces. Indeed, intercalation of different chemical species in between epitaxial graphene and silicon carbide (SiC), for instance, may decouple the graphene with respect to the substrate due to the conversion of the buffer layer into a graphene layer. O-intercalation is known to release the strain of such 2D material and to lead to the formation of high structural quality AB-stacked bilayer graphene. Nonetheless, this interface transformation concomitantly degrades graphene electronic transport properties. In this work we employed different techniques in order to better understand the structure of the graphene/SiC interface generated by O-intercalation and to elucidate the origin of the poor electronic properties of graphene. Experimental results revealed the formation of a SiO2 rich layer with a defective transition layer in between it and the SiC, which is characterized by the existence of silicon oxycarbide structures. Scanning tunneling spectroscopy measurements revealed an extensive presence of electronic states just around the Fermi level all over the sample surface, which may suppress the charge carriers mobility around this region. According to theoretical calculations, such states are mainly due to the formation of silicon oxicarbides within the interfacial layer.