cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.7244264
title: ARSENIC AND TRACE METALS IN WATER AND SEDIMENT OF THE VELHAS RIVER, SOUTHEASTERN IRON QUADRANGLE REGION, MINAS GERAIS, BRAZIL

description: This work was undertaken in the Velhas River Basin, in the municipalities of Rio Acima, Nova Lima, Raposos and Sabará, upstream of the city of Belo Horizonte in Minas Gerais State, Brazil. Velhas River provides the public water supply for much of this region. The gold and iron mining activities in the Velhas River yield considerable amounts of suspended solids as well as metals to the hydrological system of the region. Thus, the present study sought to evaluate the concentrations of arsenic and trace metals in the waters and their distribution and mobility in sediment by BCR sequential extraction. Arsenic concentrations in the water samples were between 78.1 and 85.3 μg L-1, which exceeded 10 μg L-1 (maximum limit permitted by Brazilian environmental regulations for water destined to human consumption, CONAMA Resolution 357/2005). The sequential extraction of the sediment showed considerable amounts of As (20%), Cd (55%), Co (56%), Cr (16%), Cu (23%), Ni (29%), Pb (47%) and Zn (71%) associated with the geochemical fractions considered potentially available for the remobilization to the aquatic environment. The presence of the elements in these fractions indicated high ecotoxicological risk and potential harm to the health of the local population.
DOI: 10.6084/m9.figshare.7244270
title: Evaluation of the SR Portland cement against sodium and magnesium sulfate attack: a physical and comparative analysis of mortars

description: Abstract Sulfate attack is a term used to describe a series of chemical reactions between sulfate ions and hydrated compounds of the hardened cement paste. Thus, the chemical composition of the binders used is important for the durability of the structure against this aggressive agent. The objective of the present research is to evaluate the influence of sodium and magnesium sulfates on physical properties (linear expansion, flexure tensile strength, and compressive strength) of mortars composed by SR cement (CP V - ARI RS), as commercially sold in Brazil. The results indicate that SR cement complies the requirements established by Brazilian standards, as to chemical composition and resistance to sodium sulfate. However, for magnesium sulfate, SR cement was harmful to mortars mainly in mechanical.
DOI: 10.6084/m9.figshare.7244264.v1
title: ARSENIC AND TRACE METALS IN WATER AND SEDIMENT OF THE VELHAS RIVER, SOUTHEASTERN IRON QUADRANGLE REGION, MINAS GERAIS, BRAZIL

description: This work was undertaken in the Velhas River Basin, in the municipalities of Rio Acima, Nova Lima, Raposos and Sabará, upstream of the city of Belo Horizonte in Minas Gerais State, Brazil. Velhas River provides the public water supply for much of this region. The gold and iron mining activities in the Velhas River yield considerable amounts of suspended solids as well as metals to the hydrological system of the region. Thus, the present study sought to evaluate the concentrations of arsenic and trace metals in the waters and their distribution and mobility in sediment by BCR sequential extraction. Arsenic concentrations in the water samples were between 78.1 and 85.3 μg L-1, which exceeded 10 μg L-1 (maximum limit permitted by Brazilian environmental regulations for water destined to human consumption, CONAMA Resolution 357/2005). The sequential extraction of the sediment showed considerable amounts of As (20%), Cd (55%), Co (56%), Cr (16%), Cu (23%), Ni (29%), Pb (47%) and Zn (71%) associated with the geochemical fractions considered potentially available for the remobilization to the aquatic environment. The presence of the elements in these fractions indicated high ecotoxicological risk and potential harm to the health of the local population.
DOI: 10.6084/m9.figshare.7244270.v1
title: Evaluation of the SR Portland cement against sodium and magnesium sulfate attack: a physical and comparative analysis of mortars

description: Abstract Sulfate attack is a term used to describe a series of chemical reactions between sulfate ions and hydrated compounds of the hardened cement paste. Thus, the chemical composition of the binders used is important for the durability of the structure against this aggressive agent. The objective of the present research is to evaluate the influence of sodium and magnesium sulfates on physical properties (linear expansion, flexure tensile strength, and compressive strength) of mortars composed by SR cement (CP V - ARI RS), as commercially sold in Brazil. The results indicate that SR cement complies the requirements established by Brazilian standards, as to chemical composition and resistance to sodium sulfate. However, for magnesium sulfate, SR cement was harmful to mortars mainly in mechanical.
DOI: 10.7284/135125
title: Gyrocompass data collected during research cruise SKQ201912S using a Sperry NAVIGAT 2100 instrument system onboard the platform RV Sikuliaq

description: Original (unprocessed) data collected during a Field_expedition
DOI: 10.6084/m9.figshare.7244261
title: Neolignans isolated from twigs of Nectandra leucantha Ness & Mart (Lauraceae) displayed in vitro antileishmanial activity

description: Abstract Background: The therapeutic arsenal for the treatment of Leishmaniasis is limited and includes toxic compounds (antimonials, amphotericin B, pentamidine and miltefosine). Given these aspects, the search for new compounds based on floristic biodiversity is crucial. In the present work, we report the isolation, characterization and antileishmanial activity of six related neolignans (1–6) of bioactive extract from Nectandra leucantha (Lauraceae) twigs. Methods: Dried and powdered twigs of N. leucantha were exhaustively extracted using n-hexane. The crude extract was dereplicated by HPLC/HRESIMS and subjected to column chromatography to yield pure compounds 1–6. Their chemical structures were identified via NMR and comparison of obtained data with those previously published in the literature. Biological assays of compounds 1–6 and their respective monomers (eugenol and methyleugenol) were performed using promastigote and amastigote forms of Leishmania (L.) infantum. Results: Dereplication procedures followed by chemical characterization of isolated compounds by NMR enabled the identification of related neolignans 1–6. Neolignans 2, 4 and 6 showed potential against amastigote forms of L. (L.) infantum (EC50 values of 57.9, 67.7 and 13.7 μM, respectively), while compounds 1 and 3 were inactive. As neolignans 2–4 are chemically related, it may be suggested that the presence of the methoxyl group at C4 constitutes an important structural aspect to increase antileishmanial potential against amastigote forms. Compound 6, which consists of a methylated derivative of compound 5 (inactive) showed antileishmanial activity similar to that of the standard drug miltefosine (EC50 =16.9 μM) but with reduced toxicity (SI = 14.6 and 7.2, respectively). Finally, two related monomers, eugenol and methyleugenol, were also tested and did not display activity, suggesting that the formation of dimeric compounds by oxidative coupling is crucial for antiparasitic activity of dimeric compounds 2, 4 and 6. Conclusion: This study highlights compound 6 against L. (L.) infantum amastigotes as a scaffold for future design of new compounds for drug treatment of visceral leishmaniasis.
DOI: 10.6084/m9.figshare.7244261.v1
title: Neolignans isolated from twigs of Nectandra leucantha Ness & Mart (Lauraceae) displayed in vitro antileishmanial activity

description: Abstract Background: The therapeutic arsenal for the treatment of Leishmaniasis is limited and includes toxic compounds (antimonials, amphotericin B, pentamidine and miltefosine). Given these aspects, the search for new compounds based on floristic biodiversity is crucial. In the present work, we report the isolation, characterization and antileishmanial activity of six related neolignans (1–6) of bioactive extract from Nectandra leucantha (Lauraceae) twigs. Methods: Dried and powdered twigs of N. leucantha were exhaustively extracted using n-hexane. The crude extract was dereplicated by HPLC/HRESIMS and subjected to column chromatography to yield pure compounds 1–6. Their chemical structures were identified via NMR and comparison of obtained data with those previously published in the literature. Biological assays of compounds 1–6 and their respective monomers (eugenol and methyleugenol) were performed using promastigote and amastigote forms of Leishmania (L.) infantum. Results: Dereplication procedures followed by chemical characterization of isolated compounds by NMR enabled the identification of related neolignans 1–6. Neolignans 2, 4 and 6 showed potential against amastigote forms of L. (L.) infantum (EC50 values of 57.9, 67.7 and 13.7 μM, respectively), while compounds 1 and 3 were inactive. As neolignans 2–4 are chemically related, it may be suggested that the presence of the methoxyl group at C4 constitutes an important structural aspect to increase antileishmanial potential against amastigote forms. Compound 6, which consists of a methylated derivative of compound 5 (inactive) showed antileishmanial activity similar to that of the standard drug miltefosine (EC50 =16.9 μM) but with reduced toxicity (SI = 14.6 and 7.2, respectively). Finally, two related monomers, eugenol and methyleugenol, were also tested and did not display activity, suggesting that the formation of dimeric compounds by oxidative coupling is crucial for antiparasitic activity of dimeric compounds 2, 4 and 6. Conclusion: This study highlights compound 6 against L. (L.) infantum amastigotes as a scaffold for future design of new compounds for drug treatment of visceral leishmaniasis.
DOI: 10.6084/m9.figshare.7244258
title: Which Deductive Structures Are Used by Freshmen?

description: Abstract This report presents the results of a research that inquired about the effects over freshmen of initial Mathematics courses at university have on the learning of contents which aims to the comprehension and use of deductive structures frequently used in reasoning or argumentations. This issue is interesting in Uruguay, because of students’ high rates of desertion at first year. Antecedents to this study are an analysis of textbooks and classroom notes taken by students, in search of evidence about how explicit are these structures in teaching practices. Among the results observed, it may be highlighted that only the participation in Mathematics courses, in absence of intentional instruction, seems not to be enough to acquire skills on these subjects, and only few evidences were found that shows that teaching takes in consideration instruction in Logic, except in specific texts or courses.
DOI: 10.7284/135126
title: Gyrocompass data collected during research cruise SKQ201912S using a Sperry NAVIGAT 2100 instrument system onboard the platform RV Sikuliaq

description: Original (unprocessed) data collected during a Field_expedition
DOI: 10.6084/m9.figshare.7244255
title: ALLOMETRIC MODELS TO ESTIMATE ABOVEGROUND BIOMASS OF SMALL TREES IN WET TROPICAL FORESTS OF COLOMBIAN PACIFIC AREA

description: ABSTRACT World wet tropical forests, and especially the ones in the Colombian Pacific area, are the target of a small tree (minor diameter) selective harvest process, used in short-cycle industries, such as bioenergy. This situation generates a reduction in stored carbon and biomass, and becomes an emission of greenhouse gases (GHG). Allometric models for aboveground biomass are few, despite being an important tool of carbon calculation. The goal of this study was to develop multi-species allometric models for small trees aboveground biomass in wet tropical forests. A total of 61 individuals (diameter at breast height -DBH- &lt; 12 cm) was measured, cut and weighed to estimate their biomass. The model with the best adjustment was selected considering criteria of determination coefficient (R2) and adjusted R2, mean quadratic error of prediction, Akaike and Bayesian Information Criteria and the biological logic of the model. Best-fit allometric model (R2= 0,72) was with DBH and total height as independent variables, considering that it is a multi-species model coming from forests with a high diversity.
DOI: 10.6084/m9.figshare.7244258.v1
title: Which Deductive Structures Are Used by Freshmen?

description: Abstract This report presents the results of a research that inquired about the effects over freshmen of initial Mathematics courses at university have on the learning of contents which aims to the comprehension and use of deductive structures frequently used in reasoning or argumentations. This issue is interesting in Uruguay, because of students’ high rates of desertion at first year. Antecedents to this study are an analysis of textbooks and classroom notes taken by students, in search of evidence about how explicit are these structures in teaching practices. Among the results observed, it may be highlighted that only the participation in Mathematics courses, in absence of intentional instruction, seems not to be enough to acquire skills on these subjects, and only few evidences were found that shows that teaching takes in consideration instruction in Logic, except in specific texts or courses.
DOI: 10.6084/m9.figshare.7244249
title: Design and implementation of direct tension-compression fatigue testing apparatus for damage evaluation in hot mix asphalt

description: ABSTRACT In the country, there are two most common distress found on highways: rutting and fatigue cracking. Through the most varied causes, the formation and propagation of cracks occurs as a result of repeated traffic demands and over time will drastically reduce the service life of the pavement, for example, facilitating ingress of water in granular layers of the structure and accelerating its deterioration. In addition, the most commonly used methods in Brazil for assessing and predicting fatigue behavior of asphalt concrete raises many questions to the scientific and technical community. Thus, in the context of Hot Mix Asphalt (HMA) advanced characterization, projects of the apparatus were developed as well the data processing. It is the Direct Tension Cyclic Fatigue Test to evaluate and characterize HMA behavior when it comes to fatigue damage. Adaptations of existing parts from two other research centers were made in to fit the hydraulic press used in Universidade Federal de Santa Maria (UFSM): the Universal Testing Machine (UTM-25). Tests were performed to verify the compatibility between pieces produced and hydraulic press, which demonstrated success in this matter.
DOI: 10.6084/m9.figshare.7244255.v1
title: ALLOMETRIC MODELS TO ESTIMATE ABOVEGROUND BIOMASS OF SMALL TREES IN WET TROPICAL FORESTS OF COLOMBIAN PACIFIC AREA

description: ABSTRACT World wet tropical forests, and especially the ones in the Colombian Pacific area, are the target of a small tree (minor diameter) selective harvest process, used in short-cycle industries, such as bioenergy. This situation generates a reduction in stored carbon and biomass, and becomes an emission of greenhouse gases (GHG). Allometric models for aboveground biomass are few, despite being an important tool of carbon calculation. The goal of this study was to develop multi-species allometric models for small trees aboveground biomass in wet tropical forests. A total of 61 individuals (diameter at breast height -DBH- &lt; 12 cm) was measured, cut and weighed to estimate their biomass. The model with the best adjustment was selected considering criteria of determination coefficient (R2) and adjusted R2, mean quadratic error of prediction, Akaike and Bayesian Information Criteria and the biological logic of the model. Best-fit allometric model (R2= 0,72) was with DBH and total height as independent variables, considering that it is a multi-species model coming from forests with a high diversity.
DOI: 10.7284/135137
title: INS (Inertial Navigation System) data collected during research cruise SKQ201912S using a Kongsberg Seapath 320+ instrument system onboard the platform RV Sikuliaq

description: Original (unprocessed) data collected during a Field_expedition
DOI: 10.6084/m9.figshare.7244249.v1
title: Design and implementation of direct tension-compression fatigue testing apparatus for damage evaluation in hot mix asphalt

description: ABSTRACT In the country, there are two most common distress found on highways: rutting and fatigue cracking. Through the most varied causes, the formation and propagation of cracks occurs as a result of repeated traffic demands and over time will drastically reduce the service life of the pavement, for example, facilitating ingress of water in granular layers of the structure and accelerating its deterioration. In addition, the most commonly used methods in Brazil for assessing and predicting fatigue behavior of asphalt concrete raises many questions to the scientific and technical community. Thus, in the context of Hot Mix Asphalt (HMA) advanced characterization, projects of the apparatus were developed as well the data processing. It is the Direct Tension Cyclic Fatigue Test to evaluate and characterize HMA behavior when it comes to fatigue damage. Adaptations of existing parts from two other research centers were made in to fit the hydraulic press used in Universidade Federal de Santa Maria (UFSM): the Universal Testing Machine (UTM-25). Tests were performed to verify the compatibility between pieces produced and hydraulic press, which demonstrated success in this matter.
DOI: 10.6084/m9.figshare.7244252
title: The potentiality of the use of tire rubber residue in mortar: analysis of physical and mechanical properties

description: ABSTRACT The construction industry has been absorbing waste from various industrial segments and transforming them into components for use in construction, through its incorporation in materials such as mortars and concretes. Due to this fact, this study aims to evaluate the behavior of mortars with different substitutions of small aggregates for rubber residue, conferring their physical and mechanical behavior. In order to verify the best substitution ratio, the tests were carried out on reference mortar and mortar with residues in the proportions of 2,5% wt, 5% wt, 10% wt and 15% wt of substitution of sand by rubber, the reference trace is 1: 3 (cement: aggregate). For the preparation of the mortars, the aggregates, sand and rubber were divided into four granulometric fractions, generating four subfamilies of mortars for each family of mortar with residues. For characterizing of the mortars, tests of consistency index, axial compression, tensile strength by diametrical compression, absorption by capillarity and absorption by immersion were performed. Based on these tests two traces of mortar were chosen to cover two prototypes of masonry, in order to verify the behavior of the coating mortar. The prototypes were analyzed visually in relation to the appearance of pathological manifestations and were tested for water absorption by the pipe method. The results indicate that in mortars with residue a decrease in the resistances has occurred. In the absorptions some subfamilies had better performance than the reference mortar. For the prototypes the use of rubber did not influence the behavior of the mortar coating and the permeability by the pipe method was shown without significant differences in the results obtained.
DOI: 10.6084/m9.figshare.7244246
title: Numerical Studies of Penetration in Light Armor, Concrete and Brick-Wall Targets

description: ABSTRACT The accurate numerical simulation of projectile penetration process is a complex challenge. Experimental investigation of these time-dependent non-linear events is expensive and time-consuming. In this paper, 3-D numerical simulations are carried out to estimate the penetration performance of designed penetrators against the double and triple brick-wall, plain concrete wall and light armor targets at impact velocities of 120 to 300 m/s, undergoing normal and oblique impacts. In all simulations, both the projectile and targets are modeled using Lagrange solver facility, available in ANSYS/Autodyn. During penetration process, targets experience severe grid deformation in the region local to the penetrator. Highly distorted elements are removed from the calculation using erosion strain algorithm. The simulation results suggest that at maximum velocity flat-nose (FN) projectile successfully perforate all the targets with significant residual velocity, for both normal and maximum oblique impact scenarios. For impact velocity of 120 m/s, the FN projectile perforated the armor and concrete targets but was not able to penetrate and cross through these targets. However, both brick-wall targets were perforated at normal and maximum oblique angle with sufficient residual velocity. The validation of the calculated results and numerical setup were made with experiments against double and triple brick-wall targets for impacting velocity of 170 m/s. Good agreement between the experimental and estimated projectile residual velocity has been achieved. In contrast to FN projectile, the ogive-nose penetrator calculated results has shown ricocheting behavior on impacting the light armor target at minimum velocity and maximum obliquity. The FN projectile has shown better perforation and penetration performance against light armor and domestic targets. The projectile minimum velocity is also estimated numerically to fully penetrate three different types of targets. These results would be beneficial for the designers and operators to get the desired performance against domestic and light armor targets with sureness.
DOI: 10.6084/m9.figshare.7244252.v1
title: The potentiality of the use of tire rubber residue in mortar: analysis of physical and mechanical properties

description: ABSTRACT The construction industry has been absorbing waste from various industrial segments and transforming them into components for use in construction, through its incorporation in materials such as mortars and concretes. Due to this fact, this study aims to evaluate the behavior of mortars with different substitutions of small aggregates for rubber residue, conferring their physical and mechanical behavior. In order to verify the best substitution ratio, the tests were carried out on reference mortar and mortar with residues in the proportions of 2,5% wt, 5% wt, 10% wt and 15% wt of substitution of sand by rubber, the reference trace is 1: 3 (cement: aggregate). For the preparation of the mortars, the aggregates, sand and rubber were divided into four granulometric fractions, generating four subfamilies of mortars for each family of mortar with residues. For characterizing of the mortars, tests of consistency index, axial compression, tensile strength by diametrical compression, absorption by capillarity and absorption by immersion were performed. Based on these tests two traces of mortar were chosen to cover two prototypes of masonry, in order to verify the behavior of the coating mortar. The prototypes were analyzed visually in relation to the appearance of pathological manifestations and were tested for water absorption by the pipe method. The results indicate that in mortars with residue a decrease in the resistances has occurred. In the absorptions some subfamilies had better performance than the reference mortar. For the prototypes the use of rubber did not influence the behavior of the mortar coating and the permeability by the pipe method was shown without significant differences in the results obtained.