cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.9870800.v1
title: Production and nutritive value of pastures in integrated livestock production systems: shading and management effects

description: ABSTRACT This study aimed to evaluate the production characteristics of pastures in integrated livestock production systems. For that, an experiment was carried out in São Carlos, SP, Brazil, from 2013 to 2015. Forage development, production and nutritive value were evaluated in five beef cattle production systems: extensive continuous stocking (Urochloa decumbens) = EXT; intensive = INT; crop-livestock = iCL; livestock-forest = iLF and crop-livestock-forest = iCLF. Rotational stocking pastures in INT, iCL, iLF and iCLF systems were established with Urochloa brizantha cv. BRS Piatã. In iCL and iCLF, pastures were renovated by resowing the grass simultaneously with corn. In iLF and iCLF, eucalyptus (Eucalyptus urograndis clone GG100) was planted in Apr 2011 in single rows with 15 × 2 m spacing. In the 2013/2014 crop season, INT, iCL, and iCLF pastures were more productive than in iLF and EXT. Shading increase in the 2014/2015 season reduced pasture production in iLF and iCLF, compared with INT and iCL, but increased crude protein content and digestibility. In the shaded systems, pasture production was affected by proximity to trees, mainly due to reductions in solar radiation transmission. The principal component analyses showed that forage accumulation and leaf area index were associated with the position in the middle of the inter-row, and nutritive value was associated with the position at 1.5 m from the trees. In iCLF, solar radiation transmission greater than 60 % maintained forage accumulation similar to iCL, while in iLF, it reduced forage accumulation, evidencing that pasture renovation minimized shading effects in these systems.
DOI: 10.6084/m9.figshare.9870803.v1
title: Productivity and Superficial Quality of an Aspherical Die Using CAD/CAM

description: ABSTRACT Nowadays, it is hard to imagine modern industry without the manufacturing and design software aided by computer, known as CAD/CAM, once the search for excellence in complex geometry parts, reduced time, quality assurance and interchangeability is increasing. Within this quest, the CAD/CAM platform has become a significant factor in manufacturing, especially on complex surfaces parts, mainly because of superficial quality, reliability and product competitiveness. Defined as surface within one or more non-flat surfaces or non-square, usually represented by parametric models, the freeform surfaces are very complex, requiring the control of three or more axes simultaneously, making the CAM tool indispensable. Tests were carried out by milling of aspherical cavities, on VP100 steel samples, with cemented carbide ball nose inserts with TiAlN coating. Two cutting strategies – zig-zag and spiral – and two finishing (CAM) strategies – parallel plans and Z level – were also investigated. Final Surface quality, tool productivity and tool wear were related to machining time, surface roughness (Ra, Rz, Rku and Rsk) and tool wear (VBmax). Results showed that the chosen strategy (tool path) it is the main factor to productivity.
DOI: 10.6084/m9.figshare.9870788
title: Synthesis and characterization of a novel biomaterial based on chitosan modified with amino acids

description: ABSTRACT The chemical modification of chitosan (CH) from shrimp shells (Litopenaeus vannamei) was performed with amino acids: L-leucine (Leu) and L-tyrosine (Tyr), in order to change some of its physical and chemical properties, which allow the enhancement of the applications of chitosan in biomedical and pharmacological areas. The characterization of chitosan derivatives (CH-CH-Leu and Tyr) was performed by infrared spectroscopy studies (ATR-FTIR) to verify the new structure of the modified compounds. The thermal stability was analyzed by thermogravimetry (TGA). Solubility tests were carried out, where it was observed that the obtained derivatives are soluble in aqueous solutions at neutral and alkaline pH values, unlike the chitosan that is only soluble under acid pH conditions. The cytotoxicity of the derivatives was analyzed by hemocompatibility tests with human erythrocytes. Subsequently, membranes were obtain from the derivatives of CH-Leu and CH-Tyr, and contact angle was measured. The process of biodegradability in these membranes was studied through hydrolysis processes in H2O and phosphate buffered saline (PBS), pH 7.4 at 37ºC during time intervals of 24, 72 and 168 h. Scaffolds were prepared using the electrospinning technique to be able to prepare a mixture between poly (vinyl alcohol) (PVA) and CH derivatives (given their solubility in water) and the morphology was studied using scanning electron microscopy (SEM). In general, FTIR spectroscopy, TGA thermal analysis and SEM served as tools to verify the modification, and these derivatives allow to expand the physical and chemical properties of neat chitosan, mainly in terms of its solubility, allowing this novel biomaterial to be used in multiple applications, highlighting that they can be mixed with synthetic polymer phases which opens windows for the use of this interesting biopolymer.
DOI: 10.6084/m9.figshare.9870791
title: An experimental and numerical approach for determining compression curves for plain and steel fiber reinforced concretes

description: ABSTRACT The stress-strain diagram of concrete is important for the design of concrete structures because compressive strength, peak deformation, modulus of elasticity and toughness can be obtained from this diagram. However, the stress-strain relationship is not commonly determined in concrete quality control trials, and usually, only compressive strength is determined. However, when more refined methods are used for designing concrete structures, such as physical nonlinear analysis with the finite element method, the stress-strain diagram is fundamental for structure analysis. In this case, the compression strain-strain curve should be determined in a laboratory, even if recommended curves from design codes are used. Thus, the objective of this paper is to propose a methodology to evaluate the compressive strain-strain diagram of plain and steel fiber reinforced concretes using low-cost test machines available in most concrete control laboratories. In addition, a numerical method is presented for inverse analysis of the strain-strain diagram, with the objective of estimating parameters for modeling concrete structures by means of damage mechanics.
DOI: 10.6084/m9.figshare.9870797.v1
title: Partial substitution of fishmeal with soybean protein-based diets for dourado Salminus brasiliensis

description: ABSTRACT Cost and environmental restrictions limit the use of fishmeal (FM) in aquafeeds and plant protein (PP) sources. Soybean by-products are important alternative; however, their antinutritional factors may reduce fish growth. This study evaluates the effect of FM substitution for PP (soybean meal and soy protein concentrate) in diets of dourado (Salminus brasiliensis), a promising species for fish farming and empirically considered highly tolerant to PP-based diets. A control diet was formulated to contain 20 % of fishmeal and 61 % of plant protein (SBM) and other five diets with decreasing FM graded levels (16 %, 12 %, 8 %, 4 %, 0 %), which were replaced by soybean protein concentrate (SPC), comprising six treatments and four replicates. Fifteen dourados (6.73 ± 0.2 g) were stocked into 200 L tanks in a recirculating system, fed with experimental diets three times a day to apparent satiation for 90 days. Growth performance, food conversion ratio, protein efficiency ratio and protein retention efficiency of fish were impaired when FM substitution exceeded 13.05 % (the broken line analysis method). Histological analysis of intestinal mucosa showed a decrease in villus height when fishmeal was totally replaced by PP, which probably impaired digestive functions of fish and reflected in a severe loss on growth performance.
DOI: 10.6084/m9.figshare.9870782
title: Double Environmental Benefit by the Removal of Photosensitizing Dyes from the Water Using Particulate Solid Waste

description: ABSTRACT Textile industries are among the most pollutant sectors in the world, mainly by the discard of synthetic dye residues in effluents. Some processes currently used for the removal of dyes from the effluents have the disadvantages of low economic viability and difficulty for reproducing on a large scale. In parallel, the disposal and the degradation of solid waste also constitute serious environmental problems that pose challenges for recycling and degradation strategies. Considering that some dyes have photosensitizing properties and some discarded solid materials are porous, the present study proposes a strategy for removal and concomitant degradation of effluent dyes and particulate solid wastes. The rationale of this process is the use of solid particulate residue to adsorb dyes dissolved in water making both the adsorbed residue and adsorbents more susceptible to photodegradation. In the present study: an anionic synthetic porphyrin TPPS4 (meso-tetrakis (4-sulfonatophenyl) porphyrin) was used as a model of photosensitizing dye to be removed from the water. The solid waste models were neat poly(lactic acid) (PLA) and mixed with 10 wt% of thermoplastic acid (TPS). The free and adsorbed porphyrins degraded by one-day exposure to sunlight. TPPS4 adsorbed more efficiently in PLA/TPS and degraded faster in neat PLA. Adsorption of the porphyrin promoted photodegradation of both PLA and PLA/TPS.
DOI: 10.6084/m9.figshare.9870785
title: Influence of Hap incorporation and β- TCP in the wollastonite/brushite bone cement

description: ABSTRACT The high number of patients with health problems due to bone diseases or trauma has promoted the development of biomaterial research to ensure a better quality of life. Among the various biomaterials, polymeric (PMMA) or ceramic bone cements (phosphates and calcium silicates) stands out for such application. In view of the above, the objective of the research was to evaluate the incorporation of calcium phosphates (β-TCP (sample 1-A1) and hydroxyapatite-HAp (sample 2-A2) in the proportion of 2% (m/m) for the formation of calcium silicate bone cement (wollastonite / brushite) by the method of dissolution/precipitation. The powder mixture (wollastonite) was homogenized, subsequently a solution of phosphoric acid added to form the bone cement were placed in a teflon mold based on the ISO 5833 ABNT NBR standard, and finally left at 25ºC for 24 hours obtaining the specimens. XRD analysis of the samples indicated the presence of the crystalline phases of calcium phosphate (β-TCP and HAp) and calcium silicate (wollastonite and Brushite). The MEV images showed particle size wollastonite/brushite/HAp/β-TCP. A granulometric analysis was carried out from the micrographs, where it was observed that the incorporation of the phosphates influenced the agglomeration of the particle sizes when compared to the pure bone cement. The compression test indicates that the incorporation of the phosphates improves the compressive strength, due to the reduction of the particles which causes a greater compression. It is concluded that A2 with the incorporation of HAp this improvement of mechanical resistance was more intense in relation to A1, however the two samples had significant improvements in relation to calcium silicate bone cement.
DOI: 10.6084/m9.figshare.9870788.v1
title: Synthesis and characterization of a novel biomaterial based on chitosan modified with amino acids

description: ABSTRACT The chemical modification of chitosan (CH) from shrimp shells (Litopenaeus vannamei) was performed with amino acids: L-leucine (Leu) and L-tyrosine (Tyr), in order to change some of its physical and chemical properties, which allow the enhancement of the applications of chitosan in biomedical and pharmacological areas. The characterization of chitosan derivatives (CH-CH-Leu and Tyr) was performed by infrared spectroscopy studies (ATR-FTIR) to verify the new structure of the modified compounds. The thermal stability was analyzed by thermogravimetry (TGA). Solubility tests were carried out, where it was observed that the obtained derivatives are soluble in aqueous solutions at neutral and alkaline pH values, unlike the chitosan that is only soluble under acid pH conditions. The cytotoxicity of the derivatives was analyzed by hemocompatibility tests with human erythrocytes. Subsequently, membranes were obtain from the derivatives of CH-Leu and CH-Tyr, and contact angle was measured. The process of biodegradability in these membranes was studied through hydrolysis processes in H2O and phosphate buffered saline (PBS), pH 7.4 at 37ºC during time intervals of 24, 72 and 168 h. Scaffolds were prepared using the electrospinning technique to be able to prepare a mixture between poly (vinyl alcohol) (PVA) and CH derivatives (given their solubility in water) and the morphology was studied using scanning electron microscopy (SEM). In general, FTIR spectroscopy, TGA thermal analysis and SEM served as tools to verify the modification, and these derivatives allow to expand the physical and chemical properties of neat chitosan, mainly in terms of its solubility, allowing this novel biomaterial to be used in multiple applications, highlighting that they can be mixed with synthetic polymer phases which opens windows for the use of this interesting biopolymer.
DOI: 10.6084/m9.figshare.9870791.v1
title: An experimental and numerical approach for determining compression curves for plain and steel fiber reinforced concretes

description: ABSTRACT The stress-strain diagram of concrete is important for the design of concrete structures because compressive strength, peak deformation, modulus of elasticity and toughness can be obtained from this diagram. However, the stress-strain relationship is not commonly determined in concrete quality control trials, and usually, only compressive strength is determined. However, when more refined methods are used for designing concrete structures, such as physical nonlinear analysis with the finite element method, the stress-strain diagram is fundamental for structure analysis. In this case, the compression strain-strain curve should be determined in a laboratory, even if recommended curves from design codes are used. Thus, the objective of this paper is to propose a methodology to evaluate the compressive strain-strain diagram of plain and steel fiber reinforced concretes using low-cost test machines available in most concrete control laboratories. In addition, a numerical method is presented for inverse analysis of the strain-strain diagram, with the objective of estimating parameters for modeling concrete structures by means of damage mechanics.
DOI: 10.6084/m9.figshare.9870776
title: Investigation of the effect of nozzle design on rheological bioprinting properties using computational fluid dynamics

description: ABSTRACT Bioprinting is the utilization of techniques derived from three-dimensional printing to generate complex biological structures which may replace natural tissues or organs. It employs high spatial resolution deposition of different cell types, growth factors and biomaterials. Those together form bioinks, which are the bioprinting inputs, analogously to conventional inks with regard to inkjet printing. In extrusion bioprinting, continuous bioink filaments are deposited layer by layer on a surface by means of an extruder nozzle, employing the displacement of a piston or pneumatic pressure. If mechanical stresses applied on a cell membrane exceed a critical value, which depends on the cell type, the cell membrane may disrupt. Computational fluid dynamics (CFD) simulations of the bioink extrusion were done to evaluate shear stresses caused by the internal pressure of extruder nozzles during bioprinting. Different three-dimensional conical nozzle designs were tested by varying angles of convergence, lengths, input diameters and output diameters of the nozzles. The power-law model, with constants k = 109.73 Pa·s0,154 and n = 0.154, was used to describe the expected non-Newtonian behavior of the bioink. Shear stresses and shear rates were evaluated for each nozzle design considering different pressures or velocities as boundary conditions at the nozzle entrance. The maximum wall shear stress value on each different nozzle varied between 1,038 Pa and 4,915 Pa. The results indicated which details of nozzle geometry are most relevant in order to optimize bioprinting. The best conditions for bioink rheology were also evaluated to ensure good printability and high cell viability.
DOI: 10.6084/m9.figshare.9870782.v1
title: Double Environmental Benefit by the Removal of Photosensitizing Dyes from the Water Using Particulate Solid Waste

description: ABSTRACT Textile industries are among the most pollutant sectors in the world, mainly by the discard of synthetic dye residues in effluents. Some processes currently used for the removal of dyes from the effluents have the disadvantages of low economic viability and difficulty for reproducing on a large scale. In parallel, the disposal and the degradation of solid waste also constitute serious environmental problems that pose challenges for recycling and degradation strategies. Considering that some dyes have photosensitizing properties and some discarded solid materials are porous, the present study proposes a strategy for removal and concomitant degradation of effluent dyes and particulate solid wastes. The rationale of this process is the use of solid particulate residue to adsorb dyes dissolved in water making both the adsorbed residue and adsorbents more susceptible to photodegradation. In the present study: an anionic synthetic porphyrin TPPS4 (meso-tetrakis (4-sulfonatophenyl) porphyrin) was used as a model of photosensitizing dye to be removed from the water. The solid waste models were neat poly(lactic acid) (PLA) and mixed with 10 wt% of thermoplastic acid (TPS). The free and adsorbed porphyrins degraded by one-day exposure to sunlight. TPPS4 adsorbed more efficiently in PLA/TPS and degraded faster in neat PLA. Adsorption of the porphyrin promoted photodegradation of both PLA and PLA/TPS.
DOI: 10.6084/m9.figshare.9870785.v1
title: Influence of Hap incorporation and β- TCP in the wollastonite/brushite bone cement

description: ABSTRACT The high number of patients with health problems due to bone diseases or trauma has promoted the development of biomaterial research to ensure a better quality of life. Among the various biomaterials, polymeric (PMMA) or ceramic bone cements (phosphates and calcium silicates) stands out for such application. In view of the above, the objective of the research was to evaluate the incorporation of calcium phosphates (β-TCP (sample 1-A1) and hydroxyapatite-HAp (sample 2-A2) in the proportion of 2% (m/m) for the formation of calcium silicate bone cement (wollastonite / brushite) by the method of dissolution/precipitation. The powder mixture (wollastonite) was homogenized, subsequently a solution of phosphoric acid added to form the bone cement were placed in a teflon mold based on the ISO 5833 ABNT NBR standard, and finally left at 25ºC for 24 hours obtaining the specimens. XRD analysis of the samples indicated the presence of the crystalline phases of calcium phosphate (β-TCP and HAp) and calcium silicate (wollastonite and Brushite). The MEV images showed particle size wollastonite/brushite/HAp/β-TCP. A granulometric analysis was carried out from the micrographs, where it was observed that the incorporation of the phosphates influenced the agglomeration of the particle sizes when compared to the pure bone cement. The compression test indicates that the incorporation of the phosphates improves the compressive strength, due to the reduction of the particles which causes a greater compression. It is concluded that A2 with the incorporation of HAp this improvement of mechanical resistance was more intense in relation to A1, however the two samples had significant improvements in relation to calcium silicate bone cement.
DOI: 10.6084/m9.figshare.9870773
title: Lithium catalyst concentration influence on bio-polyols structure and polyurethane adhesives properties

description: ABSTRACT Polyol structure can be affected by the catalyst used for its synthesis and may affect the curing kinetics and mechanical strength of the final polyurethane (PU). This work aimed to study the influence of catalyst concentration on the structure of bio-based polyols and on the final properties of the polyurethane adhesive obtained from these polyols. Polyols were investigated by Fourier transform infrared (FTIR), gel permeation chromatography (GPC) and hydroxyl index analysis, with the purpose of investigating the polyols chemical state after the synthesis. Results suggest that higher catalyst concentration led to polyols with higher hydroxyl index and other differences in the polyols structure. The influence of the catalysts concentration on the cure kinetics of the polyurethanes was verified using the Fourier transform infrared (FTIR). In addition, peel strength of PU adhesives was obtained by increasing catalyst concentration on polyol synthesis.
DOI: 10.6084/m9.figshare.9870779
title: Morphological evaluation of electrospun polycaprolactone fibers depending on the type of solvent

description: ABSTRACT Recently, tissue engineering strategies for wound and burn treatment focuses on the use of nanostructures biomaterials capable of facilitating skin regeneration and wound healing. One of the processes used to obtain this type of biomaterial is electrospinning. This process allows to producing films composed of polymeric nanofibers from a polymeric solution and thus, mimics the skin extracellular matrix. Among the most commonly used polymers, polycaprolactone (PCL) can be highlighted due to its solubility in several types of solvents. This study aimed to evaluate the effect of electrical conductivity of different solvents on morphology of electrospun PCL fibers. The influence of molar mass and viscosity of solution as well as flow rate and voltage was also investigated. Acetic acid (AC), formic acid (AF), chloroform (CLO), dichloromethane (DCM) and dimethylformamide (DMF) were used as solvents. Fibers with uniform diameters and defect-free, such as beads, were obtained using the DCM:DMF 70:30 (m/m) solvent system. In spite of decreasing PCL molar mass during processing, this solvent system presented the best results for PCL electrospinning. Electrical conductivity directly influenced all studied variables. When solvent systems with higher electrical conductivity value were used, lower voltage was necessary to produce defect-free fibers.