Three-dimensional collagen matrices of porcine origin are being used as substitutes for soft tissue grafts in periodontal plastic surgery in search of aesthetic and natural results. This in vitro study aimed to compar...Three-dimensional collagen matrices of porcine origin are being used as substitutes for soft tissue grafts in periodontal plastic surgery in search of aesthetic and natural results. This in vitro study aimed to compare Fibro-Gide® (GeistlichBiomaterials) and Mucoderm® (BotissBiomaterials) matrices during the initial phase of soft tissue formation. For this purpose, samples of 5 × 5 mm were obtained, and then human fibroblasts were plated on them. After 24, 48 and 72 h, cell viability was assessed using an MTT assay, and the secretion of type I collagen, MMP-2, TIMP-1 and TIMP-2 was analyzed by ELISA immunoassay. The control group (C) consisted of cells plated on polystyrene without the matrices. The morphology of the surfaces was also examined using scanning electron microscopy (SEM), as was the average roughness (Ra) of the samples by a profilometer. Topographic analysis revealed that roughness was significantly higher on Mucoderm® than on Fibro-Gide® (p 0.05). The synthesis of type I collagen, MMP-2 and TIMP-1 were significantly higher from cells plated on Fibro-Gide® than on Mucoderm®, in all time points (p ® than on Mucoderm® (p ® induced an increase in type I collagen, MMP-2 and TIMP-1 and TIMP-2.展开更多
High Explosive Anti-Tank(HEAT) warheads and ammunitions are frequently produced by explosive casting inside an axis-symmetric mold with an inverted conical geometry in the basis. In order to prevent manufacturing defe...High Explosive Anti-Tank(HEAT) warheads and ammunitions are frequently produced by explosive casting inside an axis-symmetric mold with an inverted conical geometry in the basis. In order to prevent manufacturing defects, the solidification process must be controlled. In this study, a dimensionless solidification model has been proposed to investigate the heat transfer considering the natural convection inside the liquid explosive and the numerical simulations were performed by using COMSOL Multiphysics and Modeling Software, employing trinitrotoluene(TNT) thermophysical properties. The effect of three different boundary conditions on the top of the mold have been evaluated: convection, adiabatic and isothermal. It has been observed that solidification process was faster for convection case and slower for isothermal case, while an intermediary total solidification time value was found for adiabatic case.Moreover, liquid explosive was completely surrounded by solid explosive during the solidification process for convection case and also for adiabatic case through the end of the process. Otherwise, it was not observed for isothermal case. The natural convection effects promoted a vortex inside the liquid explosive, accelerating the heat transfer process. It has been concluded that isothermal mold top boundary condition should be preferred to prevent manufacturing defects, avoiding high thermal stress.展开更多
The arrival of Building Information Modelling(BIM)platforms to the Architecture,Engineering and Construction(AEC)markets and companies has led to a significant increase in efficiency in this economy sector.However,man...The arrival of Building Information Modelling(BIM)platforms to the Architecture,Engineering and Construction(AEC)markets and companies has led to a significant increase in efficiency in this economy sector.However,many AEC companies try to implement BIM as a normal or incremental change or improvement in technology rather than as a technological paradigm shift that radically affects most organizational processes.This paper aims to present a basic BIM framework amenable to ensure a successful BIM adoption in Brazilian federal public organizations.Based on a literature review,we propose to split the factors into three groups:project development procedures,model development procedures and public governance policies.Some processes were studied in order to infer which of them is necessary for a successful BIM adoption.A BIM implementation is expected to be a success only if all groups of factors are well defined and the established goals for each of them are reached.We also describe results of two concept proofs related to actual cases of BIM implementation,with changes in product and governance management processes.Main results show that any BIM adoption should consider the close relation among model management,product management and governance management groups.展开更多
The Fukushima nuclear accident has generated doubts and questions which need to be properly understood and addressed. This scientific attitude became necessary to allow the use of the nuclear technology for electricit...The Fukushima nuclear accident has generated doubts and questions which need to be properly understood and addressed. This scientific attitude became necessary to allow the use of the nuclear technology for electricity generation around the world. The nuclear stakeholders are working to obtain these technical answers for the Fukushima questions. We believe that, such challenges will be, certainly, implemented in the next reactor generation, following the technological evolution. The purpose of this work is to perform a critical analysis of the Fukushima nuclear accident, focusing at the common cause failures produced by tsunami, as well as an analysis of the main redundant systems. This work also assesses the mitigative procedures and the subsequent consequences of such actions, which gave results below expectations to avoid the progression of the accident, discussing the concept of sharing of structures, systems and components at multi-unit nuclear power plants, and its eventual inappropriate use in safety-related devices which can compromise the nuclear safety, as well as its consequent impact on the Fukushima accident scenario. The lessons from Fukushima must be better learned, aiming the development of new procedures and new safety systems. Thus, the nuclear technology could reach a higher evolution level in its safety requirements. This knowledge will establish a conceptual milestone in the safety system design, becoming necessary the review of the current acceptance criteria of safety-related systems.展开更多
文摘Three-dimensional collagen matrices of porcine origin are being used as substitutes for soft tissue grafts in periodontal plastic surgery in search of aesthetic and natural results. This in vitro study aimed to compare Fibro-Gide® (GeistlichBiomaterials) and Mucoderm® (BotissBiomaterials) matrices during the initial phase of soft tissue formation. For this purpose, samples of 5 × 5 mm were obtained, and then human fibroblasts were plated on them. After 24, 48 and 72 h, cell viability was assessed using an MTT assay, and the secretion of type I collagen, MMP-2, TIMP-1 and TIMP-2 was analyzed by ELISA immunoassay. The control group (C) consisted of cells plated on polystyrene without the matrices. The morphology of the surfaces was also examined using scanning electron microscopy (SEM), as was the average roughness (Ra) of the samples by a profilometer. Topographic analysis revealed that roughness was significantly higher on Mucoderm® than on Fibro-Gide® (p 0.05). The synthesis of type I collagen, MMP-2 and TIMP-1 were significantly higher from cells plated on Fibro-Gide® than on Mucoderm®, in all time points (p ® than on Mucoderm® (p ® induced an increase in type I collagen, MMP-2 and TIMP-1 and TIMP-2.
文摘High Explosive Anti-Tank(HEAT) warheads and ammunitions are frequently produced by explosive casting inside an axis-symmetric mold with an inverted conical geometry in the basis. In order to prevent manufacturing defects, the solidification process must be controlled. In this study, a dimensionless solidification model has been proposed to investigate the heat transfer considering the natural convection inside the liquid explosive and the numerical simulations were performed by using COMSOL Multiphysics and Modeling Software, employing trinitrotoluene(TNT) thermophysical properties. The effect of three different boundary conditions on the top of the mold have been evaluated: convection, adiabatic and isothermal. It has been observed that solidification process was faster for convection case and slower for isothermal case, while an intermediary total solidification time value was found for adiabatic case.Moreover, liquid explosive was completely surrounded by solid explosive during the solidification process for convection case and also for adiabatic case through the end of the process. Otherwise, it was not observed for isothermal case. The natural convection effects promoted a vortex inside the liquid explosive, accelerating the heat transfer process. It has been concluded that isothermal mold top boundary condition should be preferred to prevent manufacturing defects, avoiding high thermal stress.
文摘The arrival of Building Information Modelling(BIM)platforms to the Architecture,Engineering and Construction(AEC)markets and companies has led to a significant increase in efficiency in this economy sector.However,many AEC companies try to implement BIM as a normal or incremental change or improvement in technology rather than as a technological paradigm shift that radically affects most organizational processes.This paper aims to present a basic BIM framework amenable to ensure a successful BIM adoption in Brazilian federal public organizations.Based on a literature review,we propose to split the factors into three groups:project development procedures,model development procedures and public governance policies.Some processes were studied in order to infer which of them is necessary for a successful BIM adoption.A BIM implementation is expected to be a success only if all groups of factors are well defined and the established goals for each of them are reached.We also describe results of two concept proofs related to actual cases of BIM implementation,with changes in product and governance management processes.Main results show that any BIM adoption should consider the close relation among model management,product management and governance management groups.
文摘The Fukushima nuclear accident has generated doubts and questions which need to be properly understood and addressed. This scientific attitude became necessary to allow the use of the nuclear technology for electricity generation around the world. The nuclear stakeholders are working to obtain these technical answers for the Fukushima questions. We believe that, such challenges will be, certainly, implemented in the next reactor generation, following the technological evolution. The purpose of this work is to perform a critical analysis of the Fukushima nuclear accident, focusing at the common cause failures produced by tsunami, as well as an analysis of the main redundant systems. This work also assesses the mitigative procedures and the subsequent consequences of such actions, which gave results below expectations to avoid the progression of the accident, discussing the concept of sharing of structures, systems and components at multi-unit nuclear power plants, and its eventual inappropriate use in safety-related devices which can compromise the nuclear safety, as well as its consequent impact on the Fukushima accident scenario. The lessons from Fukushima must be better learned, aiming the development of new procedures and new safety systems. Thus, the nuclear technology could reach a higher evolution level in its safety requirements. This knowledge will establish a conceptual milestone in the safety system design, becoming necessary the review of the current acceptance criteria of safety-related systems.
