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  • Artigo
    Crack tunneling effects on the elastic unloading compliance of C(T), SE(B) and clamped SE(T) specimens and correction methodology
    (2023) ANDRE, L. G. F.; MATTAR NETO, M.; Gustavo Donato
    © 2023 Elsevier LtdThis paper covers the effects of crack tunneling on SE(B), C(T), and clamped SE(T) specimens and presents a correction methodology for this effect and is divided in two parts. Part one presents an investigation of how crack front curvature affects instantaneous crack size predictions based on the elastic unloading compliance technique. Relative crack depths (a/W) of 0.2, 0.5, and 0.7, were considered alongside five levels of crack curvature. Refined finite element models provided load-CMOD records in order to support compliance assessment. The crack front was modeled as a semi-ellipse, and the compliance results agreed with experimental data from the literature. It was shown that for the same equivalent physical straight crack standardized by ASTM, compliance generally decreases as tunneling increases. Since the maximum crack curvature allowed by the aforementioned standards is very restrictive, compliance did not meaningfully change within that limit, however, if violated, this paper shows that higher deviations may occur, leading to inaccurate crack depth estimations and invalid test results. These limits and deviations were clearly determined and, as a step to improve the techniques, this paper also presents – in part two – an exploration of a possible approach to mitigate this problem, which is based on the modification of how the equivalent straight crack of a curved crack front is determined. This new approach presents reduced errors in compliance-based crack size estimation as crack curvature increases when compared to current standardized protocols, and it can support further investigations in order to validate and standardize improved measuring techniques. Finally, it is important to state that even though the ASTM E1820 is used for the determination of crack driving forces, this study is based only on the study of the crack front curvature, the limit imposed by this standard and the deviations on crack size estimation when those limits are violated, while not focusing on determining errors directly on the J-integral. This paper is a further development on the studies published before by the research group.
  • Artigo de evento
    Biomechanical Analysis of Tissue Engineering Construct for Articular Cartilage Restoration—A Pre-clinical Study
    (2022-04-15) FARIA, R. R. DE; MAIZATO, M. J. S.; CESTARI, I. A.; HERNANDEZ, A. J.; BUENO, D. F.; Roberto Bortolussi; Cyro Albuquerque; FERNANDES, T. L.
    © 2022, Springer Nature Switzerland AG.The chondral lesion and osteoarthritis are conditions associated with an economic burden, since if left untreated may cause changes in the biomechanics of the joint and result in several injuries considered highly disabling to the individual. Mesenchymal Stem Cells (MSCs) have the immunomodulatory capacity and paracrine signaling that are useful for tissue bioengineering to treat bone and cartilage injuries. To the best of our knowledge, there is no institution in Brazil studying cartilage biomechanical properties in Good Manufacturing Practice (GMP) technique. Therefore, this study aims to describe biomechanics analysis for cartilage restoration by tissue engineering and cell therapy treatments in a GMP translational large animal model. A controlled experimental study in fourteen Brazilian miniature pigs was performed, using scaffold-free Tissue Engineering Construct (TEC) from dental pulp and synovial MSCs with 6 months follow-up. To compare the cartilage with and without TEC, indentation and maximum compressive tests were performed, as well as Finite Element model to simulate the osteochondral block and characterize its properties. The Young’s Modulus of each sample was determined, and the outcomes of maximum compressive test demonstrated the cartilage integrity. The proposed method was feasible and capable to properly evaluate articular cartilage restoration.
  • Artigo
    Indoor Airflow Dynamics in Compartmentalized Pneumology Units Equipped with Variable-Thickness MERV-13 Filters
    (2023-04-05) ALVES, C. G. A.; CHECHI JUNIOR, J. T.; Da SILVA NETO F.B.; ANJOS, G. R.; DOS SANTOS, M. D.; OLIVEIRA, G. P. DE
    © 2023 by the authors.Infection containment in the post-pandemic scenario became a top priority for healthcare engineering control staffers, especially in pneumology sectors, where the treatment of airborne infectious diseases is frequent. In Brazil, where COVID-19 left a long record of casualties, there is a lack of information on the influence of filtration systems on the maintenance of regulated operational conditions for indoor comfort in hospital environments. This paper has the following objectives: to study arrangements of filtering systems in hospital acclimatization ducts; to verify how filtering characteristics could compromise safety regulations for airflow in hospital environments; and to identify airflow stagnation points that might favor suspended viral concentrations and increase contamination risks. We used the computational fluid dynamics STAR-CCM+© software to perform numerical simulations of different cases of indoor airflow in a model corresponding to a sector of the Lauro Wanderley University Hospital (João Pessoa city, Brazil). We concluded that standards for maximum velocity are reachable despite thinner or thicker filters affecting the spread of the air. In this way, acclimatization systems are limited by a tradeoff between regulation and protection. Our findings are relevant to future technological development, interventions, safety strategies amidst contamination scenarios, and new filtration arrangements in hospital environments.
  • Artigo
    Synergism between tribological parameters – “micro-abrasive concentration level”, “micro-abrasive particle type”, and “liquid type” of a micro-abrasive slurry composition on the micro-abrasive wear behaviour of Fe-30Al-6Cr (at.%) iron aluminide alloy
    (2023-07-15) DE PAULA, A. F. M.; BORGES, D. F. L.; DA SILVA F. C.; ROSSINO, L. S.; MANFRINATO, M. D.; VERMA, V.; LUNA-DOMINGUEZ, J. H.; MAGNABOSCO, R.; SCHON, C. G.; Ronaldo Câmara Cozza
    © 2023 Elsevier B.V.Observing the importance of intermetallic materials in mechanical and metallurgical applications, the present work investigates the micro-abrasive wear behaviour in a model–carbide reinforced iron aluminide system. Fe–30Al–6Cr (at.%) iron aluminide alloy with carbon additions “as cast” specimen was tested. Micrographs revealed a continuous network of eutectic chromium carbides at the interdendritic regions of the D03 ordered aluminide matrix. AISI 52100 bearing steel sphere of diameter 25.4 mm (1″) was used for wear tests as counter body. Micro-abrasive slurries were prepared with micro-abrasive particles of black silicon carbide – SiC or alumina – Al2O3, with distilled water or glycerin, in four possible combinations of materials ⇒ “Al2O3 + H2O distilled”, “Al2O3 + glycerin”, “SiC + H2O distilled” and “SiC + glycerin”. Further, keeping the normal force constant and together with different levels of micro-abrasive slurries compositions and sliding distances, a factorial experiment was designed. Result analysis showed that wear volume increased with an increase in micro-abrasive slurry concentration, independently of the type of micro-abrasive particle and liquid. However, the micro-abrasive slurries prepared with SiC and distilled water provided larger wear volumes than the volumes of wear reported under the micro-abrasive slurries formulated with Al2O3 and glycerin. The reason is attributed to the high hardness of SiC particles resulting in high abrasion, whereas the Al2O3 – glycerin slurry lubrication effect restricted high wear. Wear micrographs revealed a change in worn surface morphology from “grooving micro-abrasion” to “rolling micro-abrasion” due to an increase in sliding distance and micro-abrasive slurry concentration.
  • Artigo de evento
    SCRUM applied to foundry simulation projects
    (2021-01-05) DE SÁ, D. A.; WILLIAN GOMES, C.; PAULIELI COLOSSETTI, A.; SCHMIDT, J.; RODOLFO ABRAHAM, E.
    © 2021 SAE International.Process simulation has a growing role in the casting industry, considered as an essential tool by most foundries that aim to develop systems that deliver quality parts, with the highest possible yield and lowest scrap rate. The challenges of performing casting simulation as part of tool construction projects for permanent molds are presented here. Real schedules from tooling companies are analyzed and their bottlenecks are explored. Using the concepts of agile project management and the Scrum framework applied to a cast part, it was possible to verify that integration between tool construction and simulation can increase quality and robustness with no impact to product development time.
  • Artigo
    Use of ball-cratering wear test and nanoscratching test to compare the wear resistance of homogeneous and functionally graded titanium nitride thin films
    (2023-01-05) CARNEIRO DA SILVA F.; DE MATOS MACEDO M.; COSTA MISCIONE J. M.; FONTANA, L. C.; SAGA J. C.; Ronaldo Câmara Cozza; SCHON C. G.
    © 2022 The Author(s).Homogeneous (HM) and functionally graded (FG) TiN thin films were produced by the grid-assisted magnetron sputtering (GAMS) technique. The joint use of ball-cratering micro-abrasive wear test (BCMA) and nanoscratching (NN) test was proposed and carried out to evaluate the wear resistance of TiN films. The results showed an increase of 33.3% wear resistance in the FG TiN thin film, when compared with the HM TiN thin film. This result was justified by the higher resistance to nucleation and propagation of cracks and higher level of adhesion to the substrate by the FG TiN thin film, validated through the NN tests.
  • Artigo
    Assessment of different more-electric and hybrid-electric configurations for long-range multi-engine aircraft
    (2023-03-15) GIMENEZ, F. R.; Carlos Mady; HENRIQUES, I. B.
    © 2023 Elsevier LtdIn this study, the characteristics, penalties, gains, and challenges in the electrification and hybridization process for long-range aircraft were investigated. A system and mission analysis was conducted on thermodynamics and cost. A reference aircraft was compared with other more-electric and hybrid-electric versions of the same type. These latter versions may carry batteries to supply the aircraft system and/or engine. A state-of-the-art propulsion and system architecture were also implemented in these innovative aircraft. A full factorial analysis was conducted to vary the battery energy density and the hybridization ratio for the hybrid configurations. A typical mission profile was developed to match the boundary conditions in all cases. The hybrid powertrains were confirmed in our results as exhibiting superior behavior compared to those of the other cases. The least efficient hybrid configuration, which employed an intermediate battery choice, reduced fuel consumption by 10.7% in the conventional aircraft and by 1% in the battery-powered more-electric type. Moreover, both baseline models were surpassed by the worst intermediate-battery hybrid aircraft by 3.6% and 1% in terms of overall mission exergy efficiency. Considering the actual low density of batteries available on the market, long-range hybrid-electric aircraft will require substantial time to become viable.
  • Artigo
    Tissue Engineering and Cell Therapy for Cartilage Repair: Preclinical Evaluation Methods
    (2022-02-05) SANTANNA, J. P. C.; FARIA, R. R.; ASSAD, I. P.; PINHEIRO, C. C. G.; AIELLO, V. D.; Cyro Albuquerque; Roberto Bortolussi; CESTARI, I. A.; MAIZATO, M. J. S.; HERNANDEZ, A. J.; BUENO, D. F.; FERNANDES, T. L.
    A chondral injury is a limiting disease that can affect the quality of life and be an economic burden due to the cost of immediate treatment and loss in work productivity. If left untreated, such an injury may progress to osteoarthritis, a degenerative and debilitating joint disease characterized by pain and functional impairment. Mesenchymal stromal cells (MSCs), which have immune-modulatory properties and the ability to differentiate into chondroblasts and osteoblasts, are a predictable source for the treatment of cartilage injuries. This article presents tools to evaluate cartilage restoration by tissue engineering and cell therapy treatment in a translational and preclinical large animal model. In this controlled experimental study with 14 miniature pigs, a scaffold-free tissue engineering construct (TEC) derived from dental pulp and synovial MSCs for cartilage therapy was tested. Total thickness cartilage defects were performed in both posterior knees. The defect was left empty in one of the knees, and the other received the TEC. The tissue repair was morphologically assessed by magnetic resonance imaging (MRI) using the three-dimensional double echo steady-state (3D-DESS) sequence, and compositional assessment was carried out based on the T2 mapping technique. The osteochondral specimens were fixed for histopathology, decalcified, subjected to standard histological processing, sectioned, and stained with hematoxylin and eosin. The sections stained for immunohistochemical detection of collagen types were digested with pepsin and chondroitinase and incubated with antibodies against them. The mechanical evaluation involved analysis of Young's modulus of the cartilage samples based on the indentation and maximum compression test. In addition, a finite element model was used to simulate and characterize properties of the osteochondral block. At 6 months after surgery, there were no complications with the animals and the MRI, histological, immunohistochemical, and biomechanical evaluations proved to be effective and qualified to differentiate good quality chondral repair from inadequate repair tissue. The proposed methods were feasible and capable to properly evaluate the defect filled with TEC containing stromal cells after 6 months of follow-up in a large animal model for articular cartilage restoration. Impact Statement Articular chondral injuries are prevalent and represent an economic burden due to the cost of treatment. The engineering of cartilage tissue can promote the repair of chondral injuries and is dependent on selecting appropriate cells and biocompatible frameworks. In this article, methods for evaluation of a scaffold-free cell delivery system made from mesenchymal stromal cells were present in a translational study that allows further clinical safety and efficacy trials.
  • Artigo
    Surface integrity analysis in machining of hardened AISI 4140 steel
    (2017-01-23) STIPKOVIC, M. A.; Ed Claudio Bordinassi; Farias, Adalto; Sergio Delijaicov
    This study aimed to analyze the residual stresses and roughness in finishing milling of AISI 4140 steel, quenched and tempered up to hardness of 58 HRC. Machining operations were performed with the use of CBN inserts and by varying three basic cutting parameters (cutting speed, feed per tooth and cutting depth). Hardened materials are typically machined by abrasive processes, which in turn are more expensive and complex to be studied due to the undefined cutting geometry of the grinding wheel. A series of machining tests with milling process and CBN tools was implemented in order to study the resultant condition of the specimeńs surface. An experimental design was used and the results were statistically treated, enabling the generation of a model that aims to obtain roughness values due to the optimization of three adopted cutting parameters. The roughness values found in the range of Ra 0,16 to 0,4 μm indicate that it is possible to use the milling process with CBN tools for finishing, reducing machining time and the cost of the machined part. The generated residual stresses were compressive and the feed per tooth parameter showed greater influence in this result. The research was limited to test only one type of CBN insert, which was constantly replaced, preventing the influence of tool wear on responses. The geometry of the tool as well as the use of cutting fluid were not considered. Milling process with CBN inserts is confirmed as a possibility for replacing grinding process for finishing machining leading to significant gains in machining time. An optimized model was derived to predict the value of the roughness and three optimizations were made to specify the best cutting parameters to desirable answers such as better roughness, higher compressive residual stresses and low cutting forces, for example.
  • Artigo
    Surface integrity of INCONEL 718 turned under cryogenic conditions at high cutting speeds
    (2019-06-26) PEREIRA, W. H.; Sergio Delijaicov
    © 2019, Springer-Verlag London Ltd., part of Springer Nature.Nickel alloys such as Inconel 718 have been widely used in the aerospace, oil and gas, and chemical industries, since they have excellent properties that combine high creep resistance and high mechanical strength, fatigue and corrosion. However, these properties make these alloys extremely difficult to machine, due to a high level of heat generation during material removal, causing rapid wear of cutting tools and a detrimental effect on the surface integrity, reducing the fatigue life of the machined component and lowering the productivity. Looking at the literature, it seemed that there is an opportunity to study the surface integrity of Inconel 718, turned under cryogenic conditions at cutting speeds of 250, 275 and 300 m/min. For these reasons, this work aims to evaluate the influence of the cutting parameters on the surface integrity of Inconel 718 turned under cryogenic conditions using liquid nitrogen (LN2) at high cutting speeds. A whisker-reinforced ceramic tool was used in order to provide wear and shock resistance at high cutting speeds; these are factors that are associated with surface integrity in terms of roughness Ra, residual stresses, microhardness and cutting forces. A central composite design was chosen as factorial planning for the independent variables including cutting speed, feed rate and depth of cut when carrying out the experiments. Cryogenic cooling resulted in an average cutting force of 267 N, where the penetration force was higher. The roughness Ra was 0.52 μm and was influenced by the feed rate and depth of cut. The highest tensile residual stresses in the circumferential direction with LN2 and under dry conditions were 1394 MPa and 1237 MPa, respectively and were influenced by the depth of cut. Small changes in microhardness occurred at a depth of 0.3 mm from beneath machine surface and the presence of a white layer was not observed. Although tensile residual stresses were slightly higher when using LN2 compared to dry machining on the surface, the use of LN2 caused higher compressive residual stresses at the subsurface, which can improve the fatigue life of machined components at high cutting speeds. The results showed that lower cutting parameters tend to give the best results in terms of the cutting force and surface integrity.
  • Artigo
    Tissue Engineering and Cell Therapy for Cartilage Repair: Preclinical Evaluation Methods
    (2022) SANTANNA, J. P. C.; FARIA, R. R.; ASSAD, I. P.; PINHEIRO, C. C. G.; AIELLO, V. D.; Cyro Albuquerque; Roberto Bortolussi; CESTARI, I. A.; MAIZATO, M. J. S.; HERNANDEZ, A. J.; BUENO, D. F.; FERNANDES. T. L.
    A chondral injury is a limiting disease that can affect the quality of life and be an economic burden due to the cost of immediate treatment and loss in work productivity. If left untreated, such an injury may progress to osteoarthritis, a degenerative and debilitating joint disease characterized by pain and functional impairment. Mesenchymal stromal cells (MSCs), which have immune-modulatory properties and the ability to differentiate into chondroblasts and osteoblasts, are a predictable source for the treatment of cartilage injuries. This article presents tools to evaluate cartilage restoration by tissue engineering and cell therapy treatment in a translational and preclinical large animal model. In this controlled experimental study with 14 miniature pigs, a scaffold-free tissue engineering construct (TEC) derived from dental pulp and synovial MSCs for cartilage therapy was tested. Total thickness cartilage defects were performed in both posterior knees. The defect was left empty in one of the knees, and the other received the TEC. The tissue repair was morphologically assessed by magnetic resonance imaging (MRI) using the three-dimensional double echo steady-state (3D-DESS) sequence, and compositional assessment was carried out based on the T2 mapping technique. The osteochondral specimens were fixed for histopathology, decalcified, subjected to standard histological processing, sectioned, and stained with hematoxylin and eosin. The sections stained for immunohistochemical detection of collagen types were digested with pepsin and chondroitinase and incubated with antibodies against them. The mechanical evaluation involved analysis of Young's modulus of the cartilage samples based on the indentation and maximum compression test. In addition, a finite element model was used to simulate and characterize properties of the osteochondral block. At 6 months after surgery, there were no complications with the animals and the MRI, histological, immunohistochemical, and biomechanical evaluations proved to be effective and qualified to differentiate good quality chondral repair from inadequate repair tissue. The proposed methods were feasible and capable to properly evaluate the defect filled with TEC containing stromal cells after 6 months of follow-up in a large animal model for articular cartilage restoration. Impact Statement Articular chondral injuries are prevalent and represent an economic burden due to the cost of treatment. The engineering of cartilage tissue can promote the repair of chondral injuries and is dependent on selecting appropriate cells and biocompatible frameworks. In this article, methods for evaluation of a scaffold-free cell delivery system made from mesenchymal stromal cells were present in a translational study that allows further clinical safety and efficacy trials.
  • Artigo de evento
    Test and Validation of Vehicle Vertical Dynamics in a Multibody Software
    (2015-09-05) AFONSO, B.; CHICUTA, W.; Roberto Bortolussi
    Copyright © 2015 SAE International.This paper shows the elaboration of studies about the driver's comfort in a Baja SAE vehicle in different track conditions. The multibody model was designed in ADAMS VIEW software with full vehicle components aim evaluate frequencies, accelerations and displacements in any part of the vehicle. Several tests and measurements were made to acquire springs, dampers and tire data to ensure the model represents the real vehicle. The full vehicle and also the driver were modeled through a CAD software, thus all geometries, mass and inertias were inputted in the multibody model based on the built vehicle. The vertical displacements were modeled in the multibody software simulating the road profile, so it was possible to analyze the vehicle ride behavior with different set ups in different tracks. The validation of multibody mathematical model was made by modeling the same maneuver that the vehicle instrumented with data acquisition was submitted. The mathematical model output and the data acquisition results were confronted and the results shows that the mathematical model can be considered validated. After the mathematical model be validated, it can be use in future analysis with high confidence level. This model will be helpful to evaluate design and make modifications in earlier phases of vehicle development, reducing cost, engineering time, prototype manufacturing and mainly time in test phase once that will be necessary just the fine tuning.
  • Artigo
    Tissue Engineering and Cell Therapy for Cartilage Repair: Preclinical Evaluation Methods
    (2022-02-05) SANTANNA, J.P. C.; FARIA, R. R.; ASSAD, I. P.; PINHEIRO, C. C. G.; AIELLO, V. D.; Cyro Albuquerque; Roberto Bortolussi; CESTARI, I. A.; MAIZATO, M. J. S.; HERNANDES, A. J.; BUENO, D. F.; FERNANDES, T. L.
    A chondral injury is a limiting disease that can affect the quality of life and be an economic burden due to the cost of immediate treatment and loss in work productivity. If left untreated, such an injury may progress to osteoarthritis, a degenerative and debilitating joint disease characterized by pain and functional impairment. Mesenchymal stromal cells (MSCs), which have immune-modulatory properties and the ability to differentiate into chondroblasts and osteoblasts, are a predictable source for the treatment of cartilage injuries. This article presents tools to evaluate cartilage restoration by tissue engineering and cell therapy treatment in a translational and preclinical large animal model. In this controlled experimental study with 14 miniature pigs, a scaffold-free tissue engineering construct (TEC) derived from dental pulp and synovial MSCs for cartilage therapy was tested. Total thickness cartilage defects were performed in both posterior knees. The defect was left empty in one of the knees, and the other received the TEC. The tissue repair was morphologically assessed by magnetic resonance imaging (MRI) using the three-dimensional double echo steady-state (3D-DESS) sequence, and compositional assessment was carried out based on the T2 mapping technique. The osteochondral specimens were fixed for histopathology, decalcified, subjected to standard histological processing, sectioned, and stained with hematoxylin and eosin. The sections stained for immunohistochemical detection of collagen types were digested with pepsin and chondroitinase and incubated with antibodies against them. The mechanical evaluation involved analysis of Young's modulus of the cartilage samples based on the indentation and maximum compression test. In addition, a finite element model was used to simulate and characterize properties of the osteochondral block. At 6 months after surgery, there were no complications with the animals and the MRI, histological, immunohistochemical, and biomechanical evaluations proved to be effective and qualified to differentiate good quality chondral repair from inadequate repair tissue. The proposed methods were feasible and capable to properly evaluate the defect filled with TEC containing stromal cells after 6 months of follow-up in a large animal model for articular cartilage restoration. Impact Statement Articular chondral injuries are prevalent and represent an economic burden due to the cost of treatment. The engineering of cartilage tissue can promote the repair of chondral injuries and is dependent on selecting appropriate cells and biocompatible frameworks. In this article, methods for evaluation of a scaffold-free cell delivery system made from mesenchymal stromal cells were present in a translational study that allows further clinical safety and efficacy trials.
  • Artigo
    Tissue Engineering and Cell Therapy for Cartilage Repair: Preclinical Evaluation Methods
    (2022) SANTANNA, J. P. C.; FARIA, R. R.; ASSAD, I. P.; PINHEIRO, C. C. G.; AIELLO, V. D.; Cyro Albuquerque; Roberto Bortolussi; CESTARI, I. A.; MAIZATO, M. J. S.; HERNANDEZ, A. J.; BUENO, D. F.; FERNANDES, T. L.
    A chondral injury is a limiting disease that can affect the quality of life and be an economic burden due to the cost of immediate treatment and loss in work productivity. If left untreated, such an injury may progress to osteoarthritis, a degenerative and debilitating joint disease characterized by pain and functional impairment. Mesenchymal stromal cells (MSCs), which have immune-modulatory properties and the ability to differentiate into chondroblasts and osteoblasts, are a predictable source for the treatment of cartilage injuries. This article presents tools to evaluate cartilage restoration by tissue engineering and cell therapy treatment in a translational and preclinical large animal model. In this controlled experimental study with 14 miniature pigs, a scaffold-free tissue engineering construct (TEC) derived from dental pulp and synovial MSCs for cartilage therapy was tested. Total thickness cartilage defects were performed in both posterior knees. The defect was left empty in one of the knees, and the other received the TEC. The tissue repair was morphologically assessed by magnetic resonance imaging (MRI) using the three-dimensional double echo steady-state (3D-DESS) sequence, and compositional assessment was carried out based on the T2 mapping technique. The osteochondral specimens were fixed for histopathology, decalcified, subjected to standard histological processing, sectioned, and stained with hematoxylin and eosin. The sections stained for immunohistochemical detection of collagen types were digested with pepsin and chondroitinase and incubated with antibodies against them. The mechanical evaluation involved analysis of Young's modulus of the cartilage samples based on the indentation and maximum compression test. In addition, a finite element model was used to simulate and characterize properties of the osteochondral block. At 6 months after surgery, there were no complications with the animals and the MRI, histological, immunohistochemical, and biomechanical evaluations proved to be effective and qualified to differentiate good quality chondral repair from inadequate repair tissue. The proposed methods were feasible and capable to properly evaluate the defect filled with TEC containing stromal cells after 6 months of follow-up in a large animal model for articular cartilage restoration. Impact Statement Articular chondral injuries are prevalent and represent an economic burden due to the cost of treatment. The engineering of cartilage tissue can promote the repair of chondral injuries and is dependent on selecting appropriate cells and biocompatible frameworks. In this article, methods for evaluation of a scaffold-free cell delivery system made from mesenchymal stromal cells were present in a translational study that allows further clinical safety and efficacy trials.
  • Artigo
    Adressing Energy Demand and Climate Change through the Second Law of Thermodynamics and LCA towards a Rational Use of Energy in Brazilian Households
    (2022-10-25) PEREIRA, M. T. R. M.; CARVALHO, M.; Carlos Mady
    © 2022 by the authors.This study focuses on a typical Brazilian household through the lens of sustainable development, regarding energy demand and GHG emissions. The analysis encompasses both the direct and indirect energy, exergy consumption, and GHG emissions (quantified by life cycle assessment) associated with the usual routine of a household. The household is modeled as a thermodynamic system to evaluate inputs (food, electricity, fuels for transportation) and outputs (solid and liquid residues). The hypothesis is that each input and output contains CO (Formula presented.) emissions and exergy derived from its physical-chemical characteristics or production chains. Each household appliance is modeled and tested as a function of external parameters. The contribution of several industries was obtained to the total GHG emissions and exergy flows entering and exiting the household (e.g., fuels for transportation, food, gas, electricity, wastewater treatment, solid waste). It was verified that urban transportation was the flow with the highest GHG and exergy intensity, ranging between 1.49 and 7.53 kgCO (Formula presented.) /day and achieving 94.7 MJ/day, almost five times higher than the calculated exergy demand due to electricity. The second largest flow in GHG emissions was food due to the characteristics of the production chains, ranging from 1.6 to 4.75 kgCO (Formula presented.) /day, depending on the adopted diet. On the other hand, the electricity presented low GHG emissions due to the main energy sources used to generate electricity, only 0.52 kgCO (Formula presented.) /day. Moreover, the chemical exergy of the solid waste was 9.7 MJ/day, and is not irrelevant compared to the other flows, representing an interesting improvement opportunity as it is entirely wasted in the baseline scenario.
  • Artigo
    Tissue Engineering and Cell Therapy for Cartilage Repair: Preclinical Evaluation Methods
    (2022-02-05) SANTANNA, J.P. C.; FARIA, R. R.; ASSAD, I. P.; PINHEIRO, C. C. G.; AIELLO, V.D.; Cyro Albuquerque; Roberto Bortolussi; CESTARI, I. A.; MAIZATO, M. J. S.; HERNANDEZ, A. J.; BUENO, D. F.; FERNANDES, T. L.
    A chondral injury is a limiting disease that can affect the quality of life and be an economic burden due to the cost of immediate treatment and loss in work productivity. If left untreated, such an injury may progress to osteoarthritis, a degenerative and debilitating joint disease characterized by pain and functional impairment. Mesenchymal stromal cells (MSCs), which have immune-modulatory properties and the ability to differentiate into chondroblasts and osteoblasts, are a predictable source for the treatment of cartilage injuries. This article presents tools to evaluate cartilage restoration by tissue engineering and cell therapy treatment in a translational and preclinical large animal model. In this controlled experimental study with 14 miniature pigs, a scaffold-free tissue engineering construct (TEC) derived from dental pulp and synovial MSCs for cartilage therapy was tested. Total thickness cartilage defects were performed in both posterior knees. The defect was left empty in one of the knees, and the other received the TEC. The tissue repair was morphologically assessed by magnetic resonance imaging (MRI) using the three-dimensional double echo steady-state (3D-DESS) sequence, and compositional assessment was carried out based on the T2 mapping technique. The osteochondral specimens were fixed for histopathology, decalcified, subjected to standard histological processing, sectioned, and stained with hematoxylin and eosin. The sections stained for immunohistochemical detection of collagen types were digested with pepsin and chondroitinase and incubated with antibodies against them. The mechanical evaluation involved analysis of Young's modulus of the cartilage samples based on the indentation and maximum compression test. In addition, a finite element model was used to simulate and characterize properties of the osteochondral block. At 6 months after surgery, there were no complications with the animals and the MRI, histological, immunohistochemical, and biomechanical evaluations proved to be effective and qualified to differentiate good quality chondral repair from inadequate repair tissue. The proposed methods were feasible and capable to properly evaluate the defect filled with TEC containing stromal cells after 6 months of follow-up in a large animal model for articular cartilage restoration. Impact Statement Articular chondral injuries are prevalent and represent an economic burden due to the cost of treatment. The engineering of cartilage tissue can promote the repair of chondral injuries and is dependent on selecting appropriate cells and biocompatible frameworks. In this article, methods for evaluation of a scaffold-free cell delivery system made from mesenchymal stromal cells were present in a translational study that allows further clinical safety and efficacy trials.
  • Artigo
    Performance and Efficiency Trade-Offs in Brazilian Passenger Vehicle Fleet
    (2022-07-27) MOSQUIM R. F.; Carlos Mady
    © 2022 by the authors.The rate of technological progress is an important metric used for predicting the energy consumption and greenhouse gas emissions of future light-duty fleets. A trade-off between efficiency and performance is essential due to its implications on fuel consumption and efficiency improvement. These values are not directly available in the Brazilian fleet. Hence, this is the main gap in knowledge that has to be overcome. Tendencies in all relevant parameters were also unknown, and we have traced them as well, established on several publications data and models. We estimate the three indicators mentioned above for the Brazilian fleet from 1990 to 2020. Although the rate of technological progress was lower in Brazil than that in developed countries, it has increased from 0.39% to 0.61% to 1.7% to 1.9% in subsequent decades. Performance improvements offset approximately 31% to 39% of these efficiency gains. Moreover, the vehicle market is shifting toward larger vehicles, thus offsetting some efficiency improvements. We predict the fleet fuel efficiency for the years 2030 and 2035 using the above-mentioned factors. The predicted values for efficiency can vary by a factor of two. Thus, trade-off policies play a vital role in steering toward the desired goals of reducing the transportation sector’s impact on the environment.
  • Artigo
    Effect of hybrid manufacturing (am-machining) on the residual stress and pitting corrosion resistance of 316L stainless steel
    (2022-10-05) Ed Claudio Bordinassi; MHURCHADHA, S. U.; SERIACOPI, V.; Sergio Delijaicov; LEBRÃO, S. M. G.; THOMAS, K.; BATALHA, K.; RAGHAVENDRA, R.
    © 2022, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.The use of additive manufacturing (AM) has grown exponentially in recent years and has many advantages, including feasibility, over other conventional processes in many current applications. The use of a second process, for example, machining, improves the surface finish and in this case, the use of two processes is known as hybrid manufacturing. Heat treatments are often performed on parts generated by the AM process, mainly to relieve the residual stresses generated, but for some materials, this can decrease the pitting corrosion resistance of the parts. The objective of this study is to analyze the effect of hybrid manufacturing (AM + machining) on residual stresses and pitting resistance corrosion, which can bring advantages to piece properties without the use of heat treatment. 316L stainless steel parts are generated by direct laser metal sintering (DLMS), with subsequent milling using a complete factorial planning for the design of the experiments. The cutting speed, feed rate, cutting depth, use of the cutting fluid and laser power in the DLMS process are all varied. Residual stresses are measured by X-ray diffraction and the blind hole method, with polarization curves raised by a potentiostat. The results show that it is possible to reduce the residual surface stresses in the parts, even for compressive stresses, and to improve the pitting corrosion resistance, when compared to the part without milling, depending on the cutting parameters used.
  • Artigo
    Behavior of skin temperature during incremental cycling and running indoor exercises
    (2022-10-05) IGARASHI, T. L.; FERNANDES, T. L.; HERNANDEZ, A. J.; Carlos Mady; Cyro, Albuquerque
    © 2022 The Author(s)The study of the human body's energy behavior has received more attention over the past years. The development of thermal infrared cameras brought new possibilities for evaluating physical exercise performance. This work aims to study the skin temperature distribution during treadmill running and cycle ergometer tests with a graded load exercise until exhaustion. Eight amateur athletes performed both tests. In addition, the ventilatory and metabolic data were measured by indirect calorimetry. The thermoregulatory system is highly requested to maintain the internal body temperature. Consequently, the average skin temperature decreased during running and cycling tests, although with a higher variation in running. It was observed that the lower limbs had a similar performance for both exercises; on the other hand, the upper limbs had a higher temperature decrease for running. This may be explained by increased body energy transfer to the environment due to higher degrees of freedom during the test. The main contribution is comparing the thermal behavior of the person's skin performing two different activities, constructing a basis for future energy and exergy analysis of the human body under physical activities complementary to the literature.