cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14305719.v1
title: Longitudinal, Transverse, and Torsional Free Vibrational and Mechanical Behavior of Silicon Nanotubes Using an Atomistic Model

description: Abstract Silicon nanotubes (SiNTs) have been successfully synthesized recently. Despite the wide potential applications of SiNTs, their mechanical properties are rarely reported. In this study, as the first step, the mechanical behavior of clamped-free single-walled silicon nanotubes (SWSiNTs) for both armchair and zigzag structures is investigated by using molecular dynamics (MD) simulations while the inter-atomic forces are described by the Tersoff-Brenner many-body potential energy function. Meanwhile, the results of the total strain energy are used to establish an expression for predicting Young’s modulus of the nanotubes. Afterward, the free vibrational analysis including torsional, longitudinal and transverse vibrations behavior of SWSiNTs with different diameters and lengths are investigated to report the corresponding fundamental frequencies as a significant design parameter. In this study, also, an important stress-strain parameter ratio is defined for vibration analyses named dynamic Young’s modulus. Thereafter, the natural frequencies that are obtained using the current atomistic model are successfully compared with those evaluated by the continuum mechanics model. It is concluded that the utilized approach can predict the frequencies with reasonable accuracy. Furthermore, the effects of geometry on the natural frequencies for both armchair and zigzag structures are examined. The obtained results provide valuable insights into the vibrational behavior of silicon-based nanotubes.
DOI: 10.6084/m9.figshare.14305717.v1
title: Metallurgical and Electrochemical characterization of a Supermartensitic Steel

description: The pitting corrosion of supermartensitic stainless steel (SMSS) was studied in an aqueous solution of 0.1 mol/L NaCl using the scanning vibrating electrode technique (SVET) and cyclic voltammetry. The SMSS showed 0.9% of retained austenite, as verified by Mössbauer spectroscopy. Cuboidal TiN particles were identified on the steel surfaces, by using optical, scanning electron, and transmission microscopy, associated to Mg-Ca-Al rich precipitates. Pit nucleation was slow and only verified after 24 h, associated to TiN/CaO·MgO·Al2O3 complex inclusions, thus on original interdendritic spaces, where lower Cr content and the presence of inclusions are expected.
DOI: 10.6084/m9.figshare.14305716.v1
title: The Influence of Different Concentrations of a Natural Clay Material as Active Principle in Cosmetic Formulations

description: Abstract The clay minerals have characteristics and properties that allow their applicability in the cosmetic area, being incorporated into formulations as an active principle. Therefore, the aim of this work is characterizing and evaluating the influence of a clay from Miracema do Norte, Tocantins, Brazil, named Clay V, on the physicochemical characteristics of a hydrophilic gel of Aristoflex®, a copolymer of the neutralized acryloyldimethyltaurate and vinylpyrrolidone sulphonic acid. Clay V was decontaminated and characterized through microbiological evaluation, crystalline phases present by X-Ray Diffraction (XRD), chemical composition by X-Ray Fluorescence (XRF), thermogravimetric analysis (TGA) and granulometric distribution by sieving. Gels were prepared using Clay V with particles in the range ≤ 180 μm in three different concentrations: 1%, 3% and 5% (w/w) and a standard gel without clay. The formulations were evaluated according to organoleptic characteristics, pH, viscosity, spreadability and the centrifugation test. The microbiological evaluation showed that the clay sample is in compliance with the parameters established by the legislation. The following mineral phases were identified by XRD: kaolinite, illite, vermiculite and quartz, mainly composed of silica and alumina according to XRF. Thermal analysis showed that the clay has two thermal decomposition reactions, the largest being 547.6°C. The granulometric analysis identified that the largest fraction (63.22%) was of particles with sizes greater than 710 μm. The organoleptic characteristics presented by the formulations were suitable, with characteristic gel odor, homogeneous appearance, soft and refreshing texture and staining based on the concentration of Clay V used. The obtained pH values were within the range between 5.5 and 6.5, and it was verified that the gel has high spreadability, distributing evenly on the skin. The values obtained for viscosity showed that the formulations are non-Newtonian fluids with pseudoplastic behavior. The centrifugation test showed that the formulations are stable, with no phase separation. The results obtained with the tests showed that the natural clay V material is beneficial in cosmetic products and can be used for incorporation in cosmetic gel formulations of Aristoflex® type.
DOI: 10.6084/m9.figshare.14305715.v1
title: Influence of Physical and Chemical Components on the Physical-Mechanical Properties of Ten Brazilian Wood Species

description: Abstract Wood offers a good combination of high strength and low density, but its complete characterization takes a long time. This study aimed to correlate apparent density, chemical component and porosity parameters with the physical and mechanical properties of the wood as an alternative route to reduce the time spent proposing equations to estimate each mechanical property. Ten tropical wood species were characterized in accordance with Brazilian Standards and chemical components were determined by the Klason method, and the porosity using mercury intrusion. Multivariate regression models were applied to the results of each species to find the relationships. Good results were obtained, such as the coefficient of determination and the analysis of variance, which indicated that the equations for 10 out of the 16 properties are significant. Therefore, the apparent density, chemical component and porosity parameters used reduce the time intervals much lower than the time test stipulated by the standard.
DOI: 10.6084/m9.figshare.14305712.v1
title: Response of a DIN 18MnCrSiMo6-4 Continuous Cooling Bainitic Steel to Plasma Nitriding with a Nitrogen Rich Gas Composition

description: Abstract The use of continuous cooling bainitic steels can provide a more energy efficient manufacturing route. However, for their use in mechanical components like gears, it is necessary to improve their surface properties without impacting the core properties to guarantee reliable mechanical performance. The effect of temperature and time on the plasma nitriding response of a DIN 18MnCrSiMo6-4 steel was investigated. The plasma nitriding was performed for 3, 6 and 9 hours, at 400, 450, 500 and 550 °C, using a gas mixture composed of 76 vol.% nitrogen and 24 vol.% hydrogen. Samples were characterized before and after plasma nitriding concerning the microstructure, hardness and microhardness, fracture toughness, phase composition and residual stress states. Based on the results presented, layer growth constants (k) for different temperatures was determined. Moreover, it could be found that 500 °C gave the best results investigated here, as higher temperature took to core and surface hardness decrease. The nitrided samples with thicker compound layers presented a fracture behavior dominated by the formation of Palmqvist cracks. X-ray phase analysis indicated the formation of biphasic compound layer on the surface of all nitrided samples. The diffusion zone presented compressive residual stresses with highest values near the surface.
DOI: 10.6084/m9.figshare.14305710.v1
title: Analysis of Spinel Based Inclusions During the Last Stage of The Steelmaking Process of SAE 52100

description: Abstract Al2O3 (alumina) and MgO·Al2O3 (spinel) inclusions cause valve obstruction (clogging) in continuous casting and can deteriorate the quality of the final product. In this context, industrial heats of the bearing steel SAE 52100 was examined. Samples were collected in the final steps of the steelmaking process, both after vacuum treatment and during continuous casting. A scanning electron microscope (SEM) equipped with a energy-dispersive spectrometer (EDS) and automated particle characterization analysis was used to characterize the inclusions present in the steel samples. Thermodynamic calculations were performed with the commercial software FactSageTM 7.2. Based on thermodynamic predictions, parameters such as solid fraction, liquid fraction, MgO saturation point of the slags, content of dissolved elements in steel (Al, Mg, Ca,...) and the construction of a phase stability diagram were determined. The results in this study showed a tendency for increase in MgO content in the inclusions with the decrease of �O and SiO2 contents in the slag, an increase of binary basicity (�O/%SiO2). It is verified that the MgO contents in the slag were close to the saturation, increasing the probability for the formation of inclusions rich in MgO and/or spinel. On the other hand, stability diagrams confirm the formation of spinel inclusions for each of the heats analyzed. During the final step of the steelmaking process, there is a tendency for re-oxidation, which is verified by an increase in the density of inclusions (or total oxygen TO values).
DOI: 10.6084/m9.figshare.14305707.v1
title: Enhancement of the Photodegradative Potential of Polymer Composites Containing Babassu Fiber

description: Abstract Vegetable fibers are widely used as reinforcement in the production of composites. In this work, the photodegradative potential of polymer composites containing babassu fiber was characterized and evaluated. The fibers were extracted manually and immersed in a 10% NaOH solution (Mercerization). After drying, they were crushed and incorporated into the low-density polyethylene matrix in proportions of 5%, 10%, and 20% of the total mass of the composite. The composites were subjected to Scanning Electron Microscopy analysis (showed the incorporation of fibers into the polymeric matrix), Infrared Spectroscopy (the presence of fiber was observed with peaks at 3200-3600 cm-1, and 1596 cm-1-1036 cm-1), Mechanical Tests (with 20% fiber, there is a 44% decrease in tension, 48% in strain and 12% in Young's modulus) and Thermogravimetric Analysis (inicial fiber degradation starts between 220-337 °C, and matrix degradation between 333-550 °C). The composites were subjected to degradation processes by solar radiation and under artificial UV-B. Samples of oxy-biodegradable plastic bags were also degraded under the same degradation conditions of the composites. These results show that the materials used in the research, besides presenting an excellent degree of compatibilization, also reveal an improvement in the photodegradation potential of composites.
DOI: 10.6084/m9.figshare.14305704.v1
title: Thermal, Morphological, and Mechanical Properties of Regular and Waxy Maize Starch Films Reinforced with Cellulose Nanofibers (CNF)

description: Abstract Biodegradable films were prepared using regular and waxy starch and reinforced with cellulose nanofibers (CNF) from eucalyptus. Both films were characterized by their optical, structural, barrier, thermal and mechanical properties. The films presented a homogeneous, smooth surface without bubbles or cracks and good handling characteristics. Both films showed a mixture of B and V-type diffraction patterns. The water solubility of the samples decreased after the incorporation of nanocellulose. The water vapor permeability for both sources significantly reduced after incorporating nanocellulose at 0.5% and 1%. It is possible to observe that the addition of CNF increased the thermal stability of the starch films. On the other hand, the incorporation of nanocellulose improved either the mechanical resistance of the starch films.
DOI: 10.6084/m9.figshare.14305703.v1
title: Plasma Nitriding of ISO 5832-1 Stainless Steel with Intermittent Nitrogen Flow at 450°C

description: Abstract ISO 5832-1 stainless steel specimens were plasma nitrided at different nitrogen potentials. The main goal was to obtain the S-phase with different nitrogen concentrations and free of chromium-based precipitates. The control of nitrogen potential was made by pulsing the gas at predetermined times: 10/10, 05/15, 02/18, and 01/19, where the numbers represent the time in minutes that the nitrogen flow was kept on/off, respectively. For all pulsing conditions, the nitriding was carried out at 450 °C for 2 hours. After nitriding, specimens were characterized by means of optical (OM) and electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and microhardness. Results show that the nitrided layer thickness decreases with decreasing times of nitrogen pulse, and that lower times of nitrogen flow lead to lower precipitation of chromium nitrides. It can be thus concluded that the use of intermittent nitrogen flow is an alternative to control the nitrided layer in terms of thickness, hardness, and the amount of nitrogen present in phase ɣN (S-phase).
DOI: 10.6084/m9.figshare.14305698.v1
title: Corrosion Susceptibility and Functionally Graded Properties of Ti-35Nb-4Sn Alloy Processed by Laser Remelting

description: The effect of laser remelting on the corrosion susceptibility and mechanical properties of Ti-35Nb-4Sn (mass%) alloy is investigated across the remelted track profile. In comparison to the cold-rolled microstructure of base metal, recrystallization of heat affected zone (HAZ) improved plastic energy absorption and pitting corrosion resistance, by the reduction of active sites for pit nucleation. In fusion zone, however, passivation was compromised by the formation of dendritic microstructure with Sn enriched interdendritic region, where preferential pitting corrosion occurred. Fusion zone was the most anodic region and presented a corrosion potential difference of 35 mV, in comparison to the adjacent and most cathodic HAZ. Electrochemical impedance analysis showed that spontaneous passivation was most effective in base metal, that developed a thicker and more compact passive film. Local increase in elastic modulus and microhardness of fusion zone shows that laser remelting is a viable processing route for the manufacturing of biomaterials with functionally graded properties.
DOI: 10.6084/m9.figshare.14305695.v1
title: Characterization Alloys of the Sn-Zn System Produced by Melt Spinning

description: The objective of this work was the conformation of ribbons from Sn3Zn alloy and Sn pure, using the melt-spinning fast cooling technique, in order to investigate the applicability as biomaterial. The ribbons were coated with 1% poly-caprolactone (PCL) and subsequent incorporation of silver nanoparticles (NPAg). In the uncoated ribbon was observing a surface roughness due of agglomerate caused by rapid solidification. In the ribbon coated with PCL and NPAg incorporation, it was observed that these compounds adhered to the ribbon. X-ray diffraction analysis showed no ribbons amorphization. The analysis by differential scanning calorimetry, indicated that the Sn3Zn ribbon had a lower melting temperature (198.1°C) than the Sn ribbon (228.7°C). The microhardness of Sn3Zn ribbon was 13.38 HV and Sn ribbon was 11.00 HV, both for the face without contact with the cooling wheel. In the bioactivity assays, performed in simulated body fluid medium, all samples showed apatites formation after four weeks of testing.
DOI: 10.6084/m9.figshare.14305693.v1
title: Evaluation of Microbiological Corrosion of API 5L X80 Steel by Electrochemical Techniques in Produced Water by the Oil Industry

description: Corrosion of pipelines can be significantly affected by the activity of microorganisms present in the environment. The objective of this work was to investigate the influence microbial in the corrosion behavior of API 5L X80 steel in produced water by open circuit potential, polarization curves and electrochemical impedance spectroscopy measurements. Physical-chemical and microbiological analyzes were performed in the produced water and the tests were conducted in biotic and abiotic systems. The films and corrosion morphology developed in the steel over time were characterized by scanning electron microscopy. The results confirm that the activity of the consortium of microorganisms in the formed biofilm accelerated the dissolution of the iron, causing pitting corrosion in the steel exposed to the biotic system. Through the adjustment of the equivalent electrochemical circuit, the impedance results allowed to interpret the interactions between electrode, film and electrolyte.
DOI: 10.6084/m9.figshare.14305692.v1
title: Thermomechanical Characterization of Superelastic Ni-Ti SMA Helical Extension Springs Manufactured by Investment Casting

description: Shape memory alloy (SMA) helical springs are special mechanical parts that require a previous evaluation of its behavior for application. Therefore, in this paper thermal and mechanical behaviour of superelastic Ni-Ti SMA helical extension springs manufactured by investment casting (IC) are evaluated. Phase transformation temperatures were measured by Electrical Resistance as a function of Temperature (ERT) and Differential Scanning Calorimetry (DSC). Tensile tests were carried out within strain and temperatures ranges. The pitch angle and stiffness of each spring were determined. Results demonstrated that Ni-Ti SMA helical springs produced by IC presented phase transformation corresponding to the superelastic effect (SE). The reversible deformations under tensile test were of the order of 70%. The mechanical behavior as function of temperature revealed a linear relationship between maximum force and spring temperature.
DOI: 10.6084/m9.figshare.14305691.v1
title: Cost-Effective Thin n-type Silicon Solar Cells with Rear Emitter

description: Abstract The silicon solar cells achieved relatively low prices in the last years and to introduce a new structure in the PV industry, the amount of silicon per watt has to be reduced, requiring a cost-effective manufacturing process. The use of n-type solar grade silicon has the advantages of presenting higher minority carrier lifetime than p-type one and the absence of the boron-oxygen defects. The aim of this paper is to present the development of 100 μm thick n+np+ silicon solar cells with a selective p+ rear emitter formed by boron deposited by spin-on and an Al/Ag grid deposited by screen-printing. The firing temperature of Ag/Al (rear face) e Ag (front face) was optimized and the temperature of 840 °C produced the devices with higher efficiency. The solar cells presented efficiencies of 16%, achieving a low silicon consumption of 1.6 g/W, 40% lower than thick p-type devices produced by the same process.
DOI: 10.6084/m9.figshare.14305686.v1
title: INFORMALITY AND SEGMENTATION OF THE BRAZILIAN LABOR MARKET IN THE 2000s: A QUANTILE DECOMPOSITION OF EARNINGS DIFFERENTIALS

description: ABSTRACT This paper decomposes the changes in the earnings differentials between formal and informal labor over the last decade in Brazil, between composition and segmentation effects, separately by gender. We use microdata from the Demographic Census of 2000 and 2010 and follow Machado and Mata’s (2010) method to decompose the changes along the earnings distribution with correction for sample selection. For women and men, the segmentation effect contributed to increase the earnings advantage to formal labor at the bottom of the earnings distribution, while the composition effect contributed by decreasing these differentials along the earnings distribution, but this effect is higher at the top than the bottom of the distribution. However, there are important differences by gender in the level and variation of these components over the period and along the earnings distribution. Inequality level is higher among women than among men, and the segmentation effect is more severe for female informal labor at the bottom of the distribution. On the other hand, the reduction in the composition effect along the earnings distribution was higher among women than among men, resulting in a decrease of the total differential, from the 30th quantil, higher for the female labor, although this differential remains lower for the male labor.
DOI: 10.6084/m9.figshare.14305683.v1
title: Biopsychosocial factors associated to self-percepted sleep function in Brazilian elderly people: analysis of a national survey

description: ABSTRACT: Background: Sleep is a dimension of well-being and health. Non-restful sleep is related to health dysfunctions, especially in vulnerable populations, considering that related factors change contextually. Thus, the objective of the present study was to measure the magnitude of the reduction in sleep restorative function (SRF) and related biopsychosocial factors in Brazilian elderly. Method: Secondary data from the 2013 National Health Survey of cross-sectional design were analyzed. The sample consisted of individuals as from 60 years old. The outcome considered was the prevalence of reduced self-perceived sleep restorative function (SRF). Health and sleep characteristics, emotional behavior, lifestyle, social support, and urbanization were all investigated. The association with outcome was measured with the prevalence ratio (PR) and estimated with Cox regression, assuming α ≤ 0.05. Results: SRF was reduced by 29.2% (95%CI 27.2 - 30.6%). It is related to depression (PR = 3.37; 95%CI 2.87 - 3.97), insomnia/sleepiness (PR = 2.45; 95%CI 2.14 - 2.79); behavioral oscillation (PR = 1.75; 95%CI 1.53 - 1.99), negative health perception (PR = 1.50; 95%CI 1.23 - 1.82), computer and internet (PR = 1.44; 95%CI 1.01 - 2.07) and functional difficulty (PR = 1.13; 95%CI 1.01 - 1.27). Living in urban areas (PR = 1.32; 95%CI 1.14 - 1.52) and having a chronic condition (PR = 1.58; 95%CI 1.11 - 2.40) were only associated to the worst situation of reduced SRF. Conclusion: The reduction in SRF affects one third of the elderly in Brazil and is closely related to biopsychosocial factors, requiring intersectoral public health promotion approaches.
DOI: 10.6084/m9.figshare.14305681.v1
title: Minsky on money, the survival constraint and the current hierarchy of the globalized monetary system

description: Abstract Hyman Minsky is well-known for his contributions to the theory of financial instability. He proposes that crises in the capitalist system have an endogenous origin since companies and banks adopt increasingly speculative behavior, the longer a period of economic stability lasts. However, other original and relevant concepts developed by Minsky, such as the ‘survival constraint’, are not as widely discussed in the literature. This study intends to cover this gap, presenting and discussing the relevance of the survival constraint to the theory of money and to the understanding of the hierarchy adopted by the globalized monetary system, after the 2008 crisis.
DOI: 10.6084/m9.figshare.14305680.v1
title: Geopolitics and monetary diplomacy: the global dollar system of taxation and the international economy’s de-dollarization initiatives

description: Abstract In the international context of intensifying rivalries among great powers, the international monetary system, based on the dollar and globalized in the post-Cold War era, has been questioned and tackled. The aim of this paper is to analyze: the origins and how this system works; the US monetary and financial power, expressed by the US’s huge funding and spending capacity; and the most recent reactions from other countries in order to de-dollarize the international economy. It is concluded that the United States has built a system of global taxation based on the dollar; in addition, some recent initiatives of de-dollarization have attacked the bases of US monetary diplomacy since the Second World War.