cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.6272996.v1
title: Gas emission from anaerobic decomposition of plant resources

description: Abstract: Aim The aim of this study was to quantify the emission rates of gases resulting from the anaerobic decomposition of different plant resources under conditions usually found in sediments of tropical aquatic systems and drained organic soils. Methods Incubations were prepared with green leaves, bark, twigs, plant litter, sugarcane stalks and leaves, soybean leaves, grasses, forest leaves and an aquatic macrophyte (Typha domingensis). Over 10 months, the daily volume of gas evolved from decay was measured and a kinetic model was used to describe the anaerobic mineralization. Results Using the mathematical model, it can be observed that the composition of the plant resources is heterogeneous. The temporal variation of the gas rates indicated that the mineralization of the labile fractions of detritus varied, on a carbon basis, from 16.2 (bark) to 100% (samples composed of leaves, grasses and sugar cane stalks). High gas emissions were observed during the mineralization of grasses, sugar cane stalks, leaves and plant litter, while low volumes of gases were measured during the mineralization of bark, twigs, forest leaves and T. domingensis, which are the most fibrous and recalcitrant resources (carbon content: 83.8, 78.2, 64.8 and 53.4%, respectively). The mineralization of labile carbon presented half-life values, which varied from 41 (twigs) to 295 days (grasses). Conclusions Considering the high amount of remaining recalcitrant fraction, the anaerobic decomposition of these plant resources showed a strong trend towards accumulating organic matter in flooded soils. Despite the higher temperatures found in the tropical environment, these environments represent a sink of particulate detritus due to its slow decomposition.
DOI: 10.6084/m9.figshare.6272990
title: Effect of Urea Excess on the Properties of the MgAl2O4 Obtained by Microwave-Assisted Combustion

description: In this paper, magnesium aluminate spinels were prepared by microwave-assisted combustion, using urea as fuel. In order to evaluate the effect of the urea excess used in the synthesis, its mass was added in a range of 1.0 to 2.5 times the stoichiometric amount required. The materials produced were characterized by TGA, FTIR, XRF, XRD, BET, SEM and TEM. The results demonstrated that magnesium aluminate spinel was formed in all solids, but the crystallinity degree and the specific surface area increased according to the amount of urea that was used in the synthesis. The use of excess fuel in the preparation was therefore advantageous, since it eliminated the need of the calcination step, at high temperatures, in order to stabilize the spinel phase and improve the crystallinity of the solid. The heat generated in the combustion process was sufficient to develop the formation of a nanocrystalline structure and produce high purity materials, with a save of 99.4% in energy.
DOI: 10.6084/m9.figshare.6272990.v1
title: Effect of Urea Excess on the Properties of the MgAl2O4 Obtained by Microwave-Assisted Combustion

description: In this paper, magnesium aluminate spinels were prepared by microwave-assisted combustion, using urea as fuel. In order to evaluate the effect of the urea excess used in the synthesis, its mass was added in a range of 1.0 to 2.5 times the stoichiometric amount required. The materials produced were characterized by TGA, FTIR, XRF, XRD, BET, SEM and TEM. The results demonstrated that magnesium aluminate spinel was formed in all solids, but the crystallinity degree and the specific surface area increased according to the amount of urea that was used in the synthesis. The use of excess fuel in the preparation was therefore advantageous, since it eliminated the need of the calcination step, at high temperatures, in order to stabilize the spinel phase and improve the crystallinity of the solid. The heat generated in the combustion process was sufficient to develop the formation of a nanocrystalline structure and produce high purity materials, with a save of 99.4% in energy.
DOI: 10.6084/m9.figshare.6272987
title: Structural changes of the phytoplankton and epiphyton in an urban hypereutrophic reservoir

description: Abstract: Aim This study evaluated the temporal changes of phytoplankton and epiphyton structure and their relationships with limnological factors in an urban hypereutrophic reservoir (Rasgão Reservoir, Brazil). Methods We collected water sample and phytoplankton in different depths at two sites (dam and near tributary input) in summer and winter 2010. Epiphyton on Salvinia spp. was sampled only at site near the tributary input. We determined limnological variables and structural attributes (species composition, density, biovolume, descriptors species, diversity) for both communities. Results Phytoplankton density and epiphyton density and biovolume were higher in the winter (dry season), which occurred the higher nutrient concentrations and lower water flow. Chlorophyceae was dominant in the phytoplankton in both period and Cyanobacteria was the second most abundant class in the winter. In the epiphyton, Bacillariophyceae was dominant in the summer and Cyanobacteria in the winter. The increase in light availability and water flow can have provided high species richness and diversity in the summer. Conclusion Temporal changes in the structure of phytoplankton and epiphyton on Salvinia were more related to increased nutrients availability (nitrogen and phosphorus) and flow variations in a hypereutrophic reservoir.
DOI: 10.6084/m9.figshare.6272987.v1
title: Structural changes of the phytoplankton and epiphyton in an urban hypereutrophic reservoir

description: Abstract: Aim This study evaluated the temporal changes of phytoplankton and epiphyton structure and their relationships with limnological factors in an urban hypereutrophic reservoir (Rasgão Reservoir, Brazil). Methods We collected water sample and phytoplankton in different depths at two sites (dam and near tributary input) in summer and winter 2010. Epiphyton on Salvinia spp. was sampled only at site near the tributary input. We determined limnological variables and structural attributes (species composition, density, biovolume, descriptors species, diversity) for both communities. Results Phytoplankton density and epiphyton density and biovolume were higher in the winter (dry season), which occurred the higher nutrient concentrations and lower water flow. Chlorophyceae was dominant in the phytoplankton in both period and Cyanobacteria was the second most abundant class in the winter. In the epiphyton, Bacillariophyceae was dominant in the summer and Cyanobacteria in the winter. The increase in light availability and water flow can have provided high species richness and diversity in the summer. Conclusion Temporal changes in the structure of phytoplankton and epiphyton on Salvinia were more related to increased nutrients availability (nitrogen and phosphorus) and flow variations in a hypereutrophic reservoir.
DOI: 10.6084/m9.figshare.6272981
title: Fluvial lateral environments in Río de La Plata basin: effects of hydropower damming and eutrophication

description: Abstract Aim: Identify large-scale limnological patterns in lateral water bodies of Río de La Plata Basin, considering the influence of river damming and urban conglomerates. Methods Samplings were performed in a broad spatial scale (along 16 latitude degrees) during two seasonal periods (23 sites in summer and 20 sites in winter) for measurements of physical and chemical variables, chlorophyll a and periphyton biomass. Results Geographical distance between sites was significantly correlated with the environmental dissimilarity (Euclidean distance). Reservoir and floodplain associated sites exhibited lower phosphorus concentration. Eutrophic conditions were higher in sites close to urban areas and regions with intensive agriculture and livestock activities, which exhibited higher conductivity, concentration of nitrogen and chlorophyll a. Sites associated to reservoirs had higher periphyton biomass. Inorganic suspended matter was higher in summer whereas organic suspended matter was higher in the winter, due to contrasting rain seasonality in the upper Paraná River sub-basin. No significant correlation between the dissimilarity of the vegetation and the environmental dissimilarity or geographical distance between sites was observed. Conclusions The limnological conditions in the fluvial lateral habitats in the Río de La Plata basin are highly influenced by reservoirs construction, intensive urban occupation and rain seasonality.
DOI: 10.6084/m9.figshare.6272981.v1
title: Fluvial lateral environments in Río de La Plata basin: effects of hydropower damming and eutrophication

description: Abstract Aim: Identify large-scale limnological patterns in lateral water bodies of Río de La Plata Basin, considering the influence of river damming and urban conglomerates. Methods Samplings were performed in a broad spatial scale (along 16 latitude degrees) during two seasonal periods (23 sites in summer and 20 sites in winter) for measurements of physical and chemical variables, chlorophyll a and periphyton biomass. Results Geographical distance between sites was significantly correlated with the environmental dissimilarity (Euclidean distance). Reservoir and floodplain associated sites exhibited lower phosphorus concentration. Eutrophic conditions were higher in sites close to urban areas and regions with intensive agriculture and livestock activities, which exhibited higher conductivity, concentration of nitrogen and chlorophyll a. Sites associated to reservoirs had higher periphyton biomass. Inorganic suspended matter was higher in summer whereas organic suspended matter was higher in the winter, due to contrasting rain seasonality in the upper Paraná River sub-basin. No significant correlation between the dissimilarity of the vegetation and the environmental dissimilarity or geographical distance between sites was observed. Conclusions The limnological conditions in the fluvial lateral habitats in the Río de La Plata basin are highly influenced by reservoirs construction, intensive urban occupation and rain seasonality.
DOI: 10.6084/m9.figshare.6272978
title: TiF4 varnish protects the retention of brackets to enamel after in vitro mild erosive challenge

description: Abstract The effect of fluoride agents on the retention of orthodontic brackets to enamel under erosive challenge is little investigated. Objective: The aim of this study was to evaluate the effect of titanium tetrafluoride (TiF4) and sodium fluoride (NaF) agents on the shear bond strength of brackets to enamel and on the enamel microhardness around brackets under erosive challenge. Methods: Brackets were bonded to bovine incisors. Five groups were formed according to fluoride application (n=10): TiF4 varnish, TiF4 solution, NaF varnish, NaF solution and control (without application). The specimens were submitted to erosive challenge (90 s cola drink/2h artificial saliva, 4x per day for 7 days). Solutions were applied before each erosive cycle and varnishes were applied once. Vickers Microhardness (VHN) was obtained before and after all cycles of erosion and the percentage of microhardness loss was calculated. Shear bond strength, adhesive remnant index and polarized light microscopy were conducted after erosion. The data were analyzed by ANOVA, Tukey, Kruskal-Wallis and Mann-Whitney U tests (α=0.05). Results: The %VHN had no statistically significant differences among the experimental groups. However, considering the comparisons of all groups with the control group, TiF4 varnish showed the highest protection from enamel demineralization (effect size of 2.94, while the effect size for the other groups was &gt;2.4). The TiF4 varnish group had significantly higher shear bond strength compared to other groups. There was no difference among groups for adhesive remnant index. Polarized light microscopy showed higher demineralization depth for the control group. Conclusions: Application of NaF and TiF4 agents during mild erosive challenge minimized the enamel mineral loss around brackets, however only the experimental TiF4 varnish was able to prevent the reduction of shear bond strength of brackets to enamel.
DOI: 10.6084/m9.figshare.6272978.v1
title: TiF4 varnish protects the retention of brackets to enamel after in vitro mild erosive challenge

description: Abstract The effect of fluoride agents on the retention of orthodontic brackets to enamel under erosive challenge is little investigated. Objective: The aim of this study was to evaluate the effect of titanium tetrafluoride (TiF4) and sodium fluoride (NaF) agents on the shear bond strength of brackets to enamel and on the enamel microhardness around brackets under erosive challenge. Methods: Brackets were bonded to bovine incisors. Five groups were formed according to fluoride application (n=10): TiF4 varnish, TiF4 solution, NaF varnish, NaF solution and control (without application). The specimens were submitted to erosive challenge (90 s cola drink/2h artificial saliva, 4x per day for 7 days). Solutions were applied before each erosive cycle and varnishes were applied once. Vickers Microhardness (VHN) was obtained before and after all cycles of erosion and the percentage of microhardness loss was calculated. Shear bond strength, adhesive remnant index and polarized light microscopy were conducted after erosion. The data were analyzed by ANOVA, Tukey, Kruskal-Wallis and Mann-Whitney U tests (α=0.05). Results: The %VHN had no statistically significant differences among the experimental groups. However, considering the comparisons of all groups with the control group, TiF4 varnish showed the highest protection from enamel demineralization (effect size of 2.94, while the effect size for the other groups was &gt;2.4). The TiF4 varnish group had significantly higher shear bond strength compared to other groups. There was no difference among groups for adhesive remnant index. Polarized light microscopy showed higher demineralization depth for the control group. Conclusions: Application of NaF and TiF4 agents during mild erosive challenge minimized the enamel mineral loss around brackets, however only the experimental TiF4 varnish was able to prevent the reduction of shear bond strength of brackets to enamel.
DOI: 10.6084/m9.figshare.6272963
title: Dislocation Density and Texture in Copper Deformed by Cold Rolling and Ecap

description: Analysis of dislocation density in metallic materials has been pursued with great interest for many years because dislocations are closely associated with plastic deformation and thus exert a deep effect on the mechanical properties of any material. Crystallographic texture has also a decisive influence in some properties. In this work, the dislocation density was estimated from the line broadening of X-ray diffractograms using the Convolutional Multiple Whole Profile Program (CMWP) and crystallographic texture analyses were performed using inverse pole figures (IPF). The material used in this research was pure copper deformed by cold rolling and Equal Channel Angular Pressing (ECAP). The dislocation density values obtained by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) were compared and discussed. While, in the case of cold rolling, the crystallographic texture of the material was enhanced with increasing deformation, it was reduced with increasing deformation in the case of ECAP processing.
DOI: 10.6084/m9.figshare.6272963.v1
title: Dislocation Density and Texture in Copper Deformed by Cold Rolling and Ecap

description: Analysis of dislocation density in metallic materials has been pursued with great interest for many years because dislocations are closely associated with plastic deformation and thus exert a deep effect on the mechanical properties of any material. Crystallographic texture has also a decisive influence in some properties. In this work, the dislocation density was estimated from the line broadening of X-ray diffractograms using the Convolutional Multiple Whole Profile Program (CMWP) and crystallographic texture analyses were performed using inverse pole figures (IPF). The material used in this research was pure copper deformed by cold rolling and Equal Channel Angular Pressing (ECAP). The dislocation density values obtained by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) were compared and discussed. While, in the case of cold rolling, the crystallographic texture of the material was enhanced with increasing deformation, it was reduced with increasing deformation in the case of ECAP processing.
DOI: 10.6084/m9.figshare.6272960
title: A New Approach for Investigation of Mode II Fracture Toughness in Orthotropic Materials

description: Abstract Estimation of mode II fracture toughness (KIIC) in composite materials is known as a troublous and crucial problem. Dissipated values of KIIC that are reported in different fracture mechanics references is the evidence of the mentioned claim. This problem can signify the necessity of modification on common test methods and fixtures. The present study focuses on the causes of shear test results scattering in composite materials and presents some solutions in the form of necessary corrections that should be performed on the common test fixtures. Mixed mode I/II fracture limit curves are employed to show that the scattering in test results have strong relation with the creation of a considerable Fracture Process Zone (FPZ). It is shown that common test fixtures are blind in confrontation with FPZ and are not able to active toughening mechanisms in pure mode II, correctly. Therefore, estimation of KIIC with available test fixtures has considerable standard deviation. After that, by employing some structural modifications on common fixtures, a new scheme of a shear fixture is proposed that in addition to include the FPZ effects, prepare suitable condition in order to activate the mode II toughening mechanisms. In this regard, it could be found that by applying these reforms, shear load concentration as well as the accuracy of empirical test and repeatability and reproducibility are enhanced. Furthermore, a 3D finite element method (FEM) was considered as the numerical method in which the Iosipesque and new fixture’s specimens were analyzed by ANSYS software. It was found that by applying major amendments in the new shear test fixture, a remarkable precision in results can be obtained in comparison with the previous Iosipesque one
DOI: 10.6084/m9.figshare.6272960.v1
title: A New Approach for Investigation of Mode II Fracture Toughness in Orthotropic Materials

description: Abstract Estimation of mode II fracture toughness (KIIC) in composite materials is known as a troublous and crucial problem. Dissipated values of KIIC that are reported in different fracture mechanics references is the evidence of the mentioned claim. This problem can signify the necessity of modification on common test methods and fixtures. The present study focuses on the causes of shear test results scattering in composite materials and presents some solutions in the form of necessary corrections that should be performed on the common test fixtures. Mixed mode I/II fracture limit curves are employed to show that the scattering in test results have strong relation with the creation of a considerable Fracture Process Zone (FPZ). It is shown that common test fixtures are blind in confrontation with FPZ and are not able to active toughening mechanisms in pure mode II, correctly. Therefore, estimation of KIIC with available test fixtures has considerable standard deviation. After that, by employing some structural modifications on common fixtures, a new scheme of a shear fixture is proposed that in addition to include the FPZ effects, prepare suitable condition in order to activate the mode II toughening mechanisms. In this regard, it could be found that by applying these reforms, shear load concentration as well as the accuracy of empirical test and repeatability and reproducibility are enhanced. Furthermore, a 3D finite element method (FEM) was considered as the numerical method in which the Iosipesque and new fixture’s specimens were analyzed by ANSYS software. It was found that by applying major amendments in the new shear test fixture, a remarkable precision in results can be obtained in comparison with the previous Iosipesque one
DOI: 10.6084/m9.figshare.6272957
title: Upper gastrointestinal alterations in kidney transplant candidates

description: ABSTRACT Introduction: The incidence of gastrointestinal disorders among patients with chronic kidney disease (CKD) is high, despite the lack of a good correlation between endoscopic findings and symptoms. Many services thus perform upper gastrointestinal (UGI) endoscopy on kidney transplant candidates. Objectives: This study aims to describe the alterations seen on the upper endoscopies of 96 kidney-transplant candidates seen from 2014 to 2015. Methods: Ninety-six CKD patients underwent upper endoscopic examination as part of the preparation to receive kidney grafts. The data collected from the patients' medical records were charted on Microsoft Office Excel 2016 and presented descriptively. Mean values, medians, interquartile ranges and 95% confidence intervals of the clinic and epidemiological variables were calculated. Possible associations between endoscopic findings and infection by H. pylori were studied. Results: Males accounted for 54.17% of the 96 patients included in the study. Median age and time on dialysis were 50 years and 50 months, respectively. The most frequent upper endoscopy finding was enanthematous pangastritis (57.30%), followed by erosive esophagitis (30.20%). Gastric intestinal metaplasia and peptic ulcer were found in 8.33% and 7.30% of the patients, respectively. H. pylori tests were positive in 49 patients, and H. pylori infection was correlated only with non-erosive esophagitis (P = 0.046). Conclusion: Abnormal upper endoscopy findings were detected in all studied patients. This study suggested that upper endoscopy is a valid procedure for kidney transplant candidates. However, prospective studies are needed to shed more light on this matter.
DOI: 10.6084/m9.figshare.6272957.v1
title: Upper gastrointestinal alterations in kidney transplant candidates

description: ABSTRACT Introduction: The incidence of gastrointestinal disorders among patients with chronic kidney disease (CKD) is high, despite the lack of a good correlation between endoscopic findings and symptoms. Many services thus perform upper gastrointestinal (UGI) endoscopy on kidney transplant candidates. Objectives: This study aims to describe the alterations seen on the upper endoscopies of 96 kidney-transplant candidates seen from 2014 to 2015. Methods: Ninety-six CKD patients underwent upper endoscopic examination as part of the preparation to receive kidney grafts. The data collected from the patients' medical records were charted on Microsoft Office Excel 2016 and presented descriptively. Mean values, medians, interquartile ranges and 95% confidence intervals of the clinic and epidemiological variables were calculated. Possible associations between endoscopic findings and infection by H. pylori were studied. Results: Males accounted for 54.17% of the 96 patients included in the study. Median age and time on dialysis were 50 years and 50 months, respectively. The most frequent upper endoscopy finding was enanthematous pangastritis (57.30%), followed by erosive esophagitis (30.20%). Gastric intestinal metaplasia and peptic ulcer were found in 8.33% and 7.30% of the patients, respectively. H. pylori tests were positive in 49 patients, and H. pylori infection was correlated only with non-erosive esophagitis (P = 0.046). Conclusion: Abnormal upper endoscopy findings were detected in all studied patients. This study suggested that upper endoscopy is a valid procedure for kidney transplant candidates. However, prospective studies are needed to shed more light on this matter.