cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.9739244
title: Effect of Curing Temperature, Activator Solution Composition and Particle Size in Brazilian Fly-Ash Based Geopolymer Production

description: The geopolymer binder is a relatively new class of inorganic binding material of elevated mechanical strength and good chemical properties. This can be produced using clay minerals or byproducts of the industrial processes, such as metakaolin, fly-ash and blast furnace slag. In this work, geopolymers were produced by alkaline activation of a Brazilian fly-ash with simple and compound solutions (NaOH and NaOH + Na2SiO3). The hardened specimens presented values of the mechanical strength close to 48 MPa when the activator used presented SiO2/Na2O ration close to 1.0 after 24 h of curing at 65 ºC. The increase of the temperature to 90 ºC favored the reactions of the N-A-S-H gel (geopolymer) formation and compression strength increased to values close to 90 MPa after 24 h. It has been found that physical properties, such as density and porosity, varied when different SiO2/Na2O rations was present in alkaline solutions. Time, temperature of curing and particle size of fly-ash modified the mechanical and physical proprieties of hardened inorganic binder. Was observed the diffraction phases related to zeolitic phases and carbonate new bands of absorption were related to reactions of Na2O in excess with atmospheric CO2. The variation of SiO2/Na2O modified the microstructural of the hardened specimens.
DOI: 10.6084/m9.figshare.9739253.v1
title: An interdisciplinary approach to the Cedro archaeological site, Lower Amazon

description: Abstract The Santarém region served as the cradle for the development of one of the largest Amazonian societies during late pre-colonial times. The inhabitants of the region, described in colonial chronicles as “Tapajó,” occupied a large area south of the Santarém site, which was considered the socio-political center of this society. Permanent and autonomous settlements were established on the Belterra plateau, including the Cedro site (30 km from the Santarém site). This work uses the analysis of the Cedro site to explore two themes that have emerged from the historical/ecological framework: the interdisciplinary method and the long-term perspective. Using analysis of ceramics, stone, geochemical, and archaeobotanical analysis, we describe four areas used by the inhabitants: (1) a food preparation area that was also a ceramic workshop, (2) an area where vessels were buried, (3) a ritual pit, and (4) an artificial pond. Comparing the archaeological context with the long-term use of the space reveals the presence of both terra preta and ponds on the Belterra plateau that are still used by residents there. These findings allow us to reflect on possible functions of terra preta and ponds during precolonial times, as well as the continuation of ancient practices in the modern day.
DOI: 10.6084/m9.figshare.9739250
title: Organizational factors influencing project success: an assessment in the automotive industry

description: Abstract Paper aims Although many researchers have identified important factors for project success, there is no consensus with regard to all the factors that influence project success. This work aims to assess organizational factors that influence project success in automotive firms. Originality Few studies have analyzed the integrated relationship between organizational factors and project success. Research method The study carries out a quantitative survey on a sample of 72 companies. Data were analyzed through confirmatory factor analysis. Main findings The results show that the variable that most influences project success is ‘organizational culture’, followed by ‘change management’, and ‘top management support’. The results also indicate that a culture of flexibility and a climate that supports innovation tend to positively influence project performance. Implications for theory and practice The findings suggest that it is relevant to focus attention on human resource development, empowerment, and teamwork within the context of project management.
DOI: 10.6084/m9.figshare.9739256.v1
title: Antioxidant action in diets with ground soybeans on ruminal microbial production, digestion, and fermentation in buffaloes

description: ABSTRACT The objective of this study was to evaluate the effect of adding ground soybeans and antioxidants to diet of buffaloes on intake, ruminal microbial production, total and ruminal digestibility of nutrients, and ruminal fermentation parameters. Four crossbred buffaloes with a mean weight of 506±29 kg were distributed in a 4×4 Latin square. Four diets were tested: control; diet with ground soybeans; diet with ground soybeans and supplementation with yerba mate; and diet with ground soybeans and supplementation with yerba mate and vitamin E. The addition of ground soybeans had negative effects on intake of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber, as well as ruminal digestibility of neutral detergent fiber and total carbohydrates but did not influence total digestibility of nutrients. Yet, the ground soybeans diet increased the concentration of butyrate and microbial production in the rumen. The diet with ground soybeans supplemented with yerba mate decreased the concentration of acetate and increased the concentration of propionate and increased the efficiency of synthesis and the production of microbial protein in the rumen. There was a positive additive effect of vitamin E in the presence of yerba mate, enhancing the synthesis and production efficiency of microbial protein. Thus, the addition of ground soybeans and antioxidants to diet of buffaloes improves the efficiency of microbial protein synthesis and increases the production of butyrate, without, in general, altering the total digestibility of nutrients.
DOI: 10.6084/m9.figshare.9739238
title: Ballistic Tests of Alumina-UHMWPE Composites Submitted to Gamma Radiation

description: The energy absorption in ballistic tests of alumina-ultra high molecular weight polyethylene (UHMWPE) composites with 60, 80 and 90 wt% alumina submitted to gamma radiation doses of 25, 50 and 75 kGy was investigated. The ballistic tests were carried out at subsonic speed using a compressed air system. The results showed that the composite with 80% alumina irradiated with 50 kGy yields the best ballistic results. Gel content, Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results showed that this composite is the one with the highest concentration of crosslinks and the lowest volume fraction of amorphous UHMWPE. Scanning electron microscopy (SEM) images of the same composite showed a high pullout, suggesting that gamma irradiation increases the adhesion between alumina and UHMWPE.
DOI: 10.6084/m9.figshare.9739244.v1
title: Effect of Curing Temperature, Activator Solution Composition and Particle Size in Brazilian Fly-Ash Based Geopolymer Production

description: The geopolymer binder is a relatively new class of inorganic binding material of elevated mechanical strength and good chemical properties. This can be produced using clay minerals or byproducts of the industrial processes, such as metakaolin, fly-ash and blast furnace slag. In this work, geopolymers were produced by alkaline activation of a Brazilian fly-ash with simple and compound solutions (NaOH and NaOH + Na2SiO3). The hardened specimens presented values of the mechanical strength close to 48 MPa when the activator used presented SiO2/Na2O ration close to 1.0 after 24 h of curing at 65 ºC. The increase of the temperature to 90 ºC favored the reactions of the N-A-S-H gel (geopolymer) formation and compression strength increased to values close to 90 MPa after 24 h. It has been found that physical properties, such as density and porosity, varied when different SiO2/Na2O rations was present in alkaline solutions. Time, temperature of curing and particle size of fly-ash modified the mechanical and physical proprieties of hardened inorganic binder. Was observed the diffraction phases related to zeolitic phases and carbonate new bands of absorption were related to reactions of Na2O in excess with atmospheric CO2. The variation of SiO2/Na2O modified the microstructural of the hardened specimens.
DOI: 10.6084/m9.figshare.9739241
title: Similarities, differences, and the network of relations in the Pleistocene-Holocene transition and the Early Holocene in Central Brazil

description: Abstract The objective of this paper is to explore the similarities and differences between human occupations in Central Brazil during the Pleistocene-Holocene transition and the Early Holocene (11,000 to 9,000 years ago), and to discuss our understanding of these aspects, questioning its theoretical underpinnings. After bringing together a variety of elements presented by researchers working in four areas (the Serra da Capivara in southeastern Piauí, Serranópolis in southwestern Goiás, northern Minas Gerais in the Peruaçu Valley and Montalvânia region, and Middle Tocantins in the Lajeado River region and Lajeado Mountains), we attempt to compare these areas principally with regard to the use and managementof lithic material, the role of the sites, and organization of territory. The final section contains reflections on the theoretical resources usually utilized to compare archaeological contexts as well as suggested alternatives.
DOI: 10.6084/m9.figshare.9739250.v1
title: Organizational factors influencing project success: an assessment in the automotive industry

description: Abstract Paper aims Although many researchers have identified important factors for project success, there is no consensus with regard to all the factors that influence project success. This work aims to assess organizational factors that influence project success in automotive firms. Originality Few studies have analyzed the integrated relationship between organizational factors and project success. Research method The study carries out a quantitative survey on a sample of 72 companies. Data were analyzed through confirmatory factor analysis. Main findings The results show that the variable that most influences project success is ‘organizational culture’, followed by ‘change management’, and ‘top management support’. The results also indicate that a culture of flexibility and a climate that supports innovation tend to positively influence project performance. Implications for theory and practice The findings suggest that it is relevant to focus attention on human resource development, empowerment, and teamwork within the context of project management.
DOI: 10.6084/m9.figshare.9739235
title: The chronology of the cave paintings in the Pedra Pintada Cave, Monte Alegre, Pará: historical review and new data

description: Abstract This article presents a summary of the various theories about the chronology of the cave paintings from Monte Alegre, as well as the formal characteristics of the themes represented at the Caverna da Pedra Pintada site. The main goal is toidentify differences in style and consequently propose different periods for the execution of these paintings. To provide context for the cave paintings at this site, excavations were carried out in 2014 near one of the painted walls. A set ofdates were associated with the recovered material, such as pigments, artifacts, and charcoal, as well as soot stains over the paintings; this information offers possibilities to contextualize the rock art activity at this site.
DOI: 10.6084/m9.figshare.9739235.v1
title: The chronology of the cave paintings in the Pedra Pintada Cave, Monte Alegre, Pará: historical review and new data

description: Abstract This article presents a summary of the various theories about the chronology of the cave paintings from Monte Alegre, as well as the formal characteristics of the themes represented at the Caverna da Pedra Pintada site. The main goal is toidentify differences in style and consequently propose different periods for the execution of these paintings. To provide context for the cave paintings at this site, excavations were carried out in 2014 near one of the painted walls. A set ofdates were associated with the recovered material, such as pigments, artifacts, and charcoal, as well as soot stains over the paintings; this information offers possibilities to contextualize the rock art activity at this site.
DOI: 10.6084/m9.figshare.9739238.v1
title: Ballistic Tests of Alumina-UHMWPE Composites Submitted to Gamma Radiation

description: The energy absorption in ballistic tests of alumina-ultra high molecular weight polyethylene (UHMWPE) composites with 60, 80 and 90 wt% alumina submitted to gamma radiation doses of 25, 50 and 75 kGy was investigated. The ballistic tests were carried out at subsonic speed using a compressed air system. The results showed that the composite with 80% alumina irradiated with 50 kGy yields the best ballistic results. Gel content, Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results showed that this composite is the one with the highest concentration of crosslinks and the lowest volume fraction of amorphous UHMWPE. Scanning electron microscopy (SEM) images of the same composite showed a high pullout, suggesting that gamma irradiation increases the adhesion between alumina and UHMWPE.
DOI: 10.6084/m9.figshare.9739241.v1
title: Similarities, differences, and the network of relations in the Pleistocene-Holocene transition and the Early Holocene in Central Brazil

description: Abstract The objective of this paper is to explore the similarities and differences between human occupations in Central Brazil during the Pleistocene-Holocene transition and the Early Holocene (11,000 to 9,000 years ago), and to discuss our understanding of these aspects, questioning its theoretical underpinnings. After bringing together a variety of elements presented by researchers working in four areas (the Serra da Capivara in southeastern Piauí, Serranópolis in southwestern Goiás, northern Minas Gerais in the Peruaçu Valley and Montalvânia region, and Middle Tocantins in the Lajeado River region and Lajeado Mountains), we attempt to compare these areas principally with regard to the use and managementof lithic material, the role of the sites, and organization of territory. The final section contains reflections on the theoretical resources usually utilized to compare archaeological contexts as well as suggested alternatives.
DOI: 10.6084/m9.figshare.9739232
title: Mapping the fern Blechnum heringeri (Blechnaceae, Polypodiopsida): recording the geographical distribution, ecological preferences and reporting a new record in northeastern Brazil

description: ABSTRACT Blechnum heringeri Brade is an endemic species from Brazil previously considered vulnerable. Until recently, there was a very limited number of records for this species, all from the Cerrado Phytogeographical Domain in central Brazil. Subsequent studies have reported its occurrence in the rupestrian grasslands (campos rupestres) on the “cangas”, within the Amazonian Domain. Here we present the first record of B. heringeri for northeastern Brazil, from an enclave of cerrado vegetation in the middle of the Caatinga Domain (Ceará State). This new record significantly extends the distributional range of the species, about 1,000 km from the known records in the Amazon and Cerrado Phytogeographical Domains. We also show that the species is associated with open vegetation or the transition between open vegetation and riverine forests, being recorded in cerrado vegetation, riverine forests associated with the cerrado, cerrado enclaves in the Caatinga and Amazonian Domains, and Amazonic campos rupestres on “canga”.
DOI: 10.6084/m9.figshare.9739232.v1
title: Mapping the fern Blechnum heringeri (Blechnaceae, Polypodiopsida): recording the geographical distribution, ecological preferences and reporting a new record in northeastern Brazil

description: ABSTRACT Blechnum heringeri Brade is an endemic species from Brazil previously considered vulnerable. Until recently, there was a very limited number of records for this species, all from the Cerrado Phytogeographical Domain in central Brazil. Subsequent studies have reported its occurrence in the rupestrian grasslands (campos rupestres) on the “cangas”, within the Amazonian Domain. Here we present the first record of B. heringeri for northeastern Brazil, from an enclave of cerrado vegetation in the middle of the Caatinga Domain (Ceará State). This new record significantly extends the distributional range of the species, about 1,000 km from the known records in the Amazon and Cerrado Phytogeographical Domains. We also show that the species is associated with open vegetation or the transition between open vegetation and riverine forests, being recorded in cerrado vegetation, riverine forests associated with the cerrado, cerrado enclaves in the Caatinga and Amazonian Domains, and Amazonic campos rupestres on “canga”.
DOI: 10.6084/m9.figshare.9739217
title: HIBISCO-COLIBRI EXTRACT AS GREEN CORROSION INHIBITOR FOR CARBON STEEL IN SULFURIC ACID

description: For this work, a hydroalcoholic extract was prepared from the aerial parts of the Malvaviscus arboreus (Malvaceae) species, popularly known as hibisco-colibri in Brazil; and then, investigated by infrared and NMR spectroscopy. A class of special metabolites containing a porphyrin skeleton and pyrrole units was determined by typical absorption spectra, mainly 1H and 13C NMR, thus indicating the capability of showing anti-corrosion effect. Therefore, the M. arboreus extract was examined as a corrosion inhibitor for AISI 1020 carbon steel in H2SO4 1 mol L-1, using a mass loss (gravimetric) technique. Results showed good corrosion inhibition efficiency, at both time and temperature variation. The maximum efficiency observed at 500 ppm was 97.5%, at 3 h, 24 h and 48 h. The surface morphology was analyzed by scanning electron microscopy (SEM), through which a higher homogeneity was observed in the presence of the M. arboreus extract. The hydroalcoholic extract of hibisco-colibri can be considered an efficient green agent for preventing corrosion.
DOI: 10.6084/m9.figshare.9739226
title: Genetic variability among cashew hybrids and prediction of superior combinations based on agronomic performance

description: Abstract: The objective of this work was to evaluate the use of RAPD and ISSR molecular markers to determine the genetic variability among cashew (Anacardium spp.) genotypes, and to indicate possible promising crosses based on cashew genetic variability and phenotypic performance. Ten hybrids - derived from the crosses CCP 76 x BGC 589, CCP 76 x BRS 226, CCP 76 x HAC 276-1, CCP 76 x Embrapa 51, CCP 76 x BRS 253, CCP 76 x HAC222-4, and BRS226 x Embrapa 51 - and their parents were assessed at the molecular level. The hybrids were evaluated for nut yield, mean nut weight, bored nuts, and powdery mildew on nuts (scale 0-4). The RAPD and ISSR markers were efficient in the determinaton of the genetic variability among cashew genotypes, allowing of the grouping of 21 clusters. Associated with the phenotypic characterization of cashew nut for yield, weight, and health, the used markers can efficiently identify possible combinations with higher genetic variability and higher probability of developing transgressive genotypes in segregating populations.
DOI: 10.6084/m9.figshare.9739217.v1
title: HIBISCO-COLIBRI EXTRACT AS GREEN CORROSION INHIBITOR FOR CARBON STEEL IN SULFURIC ACID

description: For this work, a hydroalcoholic extract was prepared from the aerial parts of the Malvaviscus arboreus (Malvaceae) species, popularly known as hibisco-colibri in Brazil; and then, investigated by infrared and NMR spectroscopy. A class of special metabolites containing a porphyrin skeleton and pyrrole units was determined by typical absorption spectra, mainly 1H and 13C NMR, thus indicating the capability of showing anti-corrosion effect. Therefore, the M. arboreus extract was examined as a corrosion inhibitor for AISI 1020 carbon steel in H2SO4 1 mol L-1, using a mass loss (gravimetric) technique. Results showed good corrosion inhibition efficiency, at both time and temperature variation. The maximum efficiency observed at 500 ppm was 97.5%, at 3 h, 24 h and 48 h. The surface morphology was analyzed by scanning electron microscopy (SEM), through which a higher homogeneity was observed in the presence of the M. arboreus extract. The hydroalcoholic extract of hibisco-colibri can be considered an efficient green agent for preventing corrosion.
DOI: 10.6084/m9.figshare.9739211
title: Cellulose Nanocrystals and Jute Fiber-reinforced Natural Rubber Composites: Cure Characteristics and Mechanical Properties

description: A comparative study was conducted for three natural rubber (NR) composites: one containing raw jute fibers, one containing bleached jute fibers, and one containing cellulose nanocrystals (CNCs). The composites were prepared by adding each filler at 5 or 10 phr to the latex before chemical coagulation, and the composites were processed in a two-roll mixing mill. The mechanical, thermal, and vulcanization properties of the prepared composites were then determined. The NR stiffness increased with increasing fiber content, particularly when bleached fibers were added, as evidenced by the increased elastic moduli, maximum torques, glass transition temperature, and crosslinking density. Scanning electron microscopy showed agglomerates in the composite with 10 phr CNCs, which led to poorer mechanical performance compared to that of the bleached fiber-reinforced composite (10 phr). On the other hand, the addition of CNCs to the NR increased the cure rate index, thereby significantly advancing the optimum vulcanization time.
DOI: 10.6084/m9.figshare.9739214
title: Effect of Carnauba Wax and Coconut Fiber Contents on Tensile Properties of Corn Starch-Based Biocomposites

description: This work aims investigate the changes on tensile properties of biocomposites obtained by addition of carnauba wax and coconut fibers in a corn starch matrix. The influence of carnauba wax and coconut fibers contents on tensile strength, modulus of elasticity and elongation at break was studied using a response surface methodology. A central composite design based on three levels of carnauba wax content (0, 10 and 20 %) and coconut fibers content (0, 10 and 20 %) was elaborated. Empirical models were obtained to describe these properties as function of coconut fiber and carnauba wax contents. Optical microscopy was carried out to visualize the dispersion and interactions between coconut fibers, carnauba wax and starch matrix in the biocomposites. In presence of carnauba wax, the biocomposite became more compact and with a better interaction between the corn starch-based matrix and coconut fibers reinforcement. It was observed that tensile strength and modulus of elasticity rise with the increase in carnauba wax and coconut fiber contents. Moreover, the elongation at break increases with the addition of coconut fiber, while a decrease in the values of this property occurs with the addition of carnauba wax.