Family conference: a quality tool in the communication process in palliative care

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Fracture characterization of wood under Mode I loading using the SEN-TPB Test

Mode I fracture characterization was induced in wood (Picea abies L.) using the single-edge-notched beamloaded in three-point-bending. A developed data reduction scheme based on the equivalent linear elasticfracture mechanics was used to evaluate the Resistance-curve instead of classical methods. The method isfound on beam theory and crack equivalent concept taking into account the triangular stress relief regionthat develops in the crack vicinity. The method dispenses crack length monitoring in the course of theloading process, providing a complete Resistance-curve which is essential for a clear identification of thefracture energy. The validation of the procedure has been performed numerically using a bilinear cohesivedamage model, thus allowing the simulation of both damage initiation and growth. The numerical modelalso provided the critical specimen dimensions that permit the attainment of accurate evaluation of thefracture toughness in wood

A new method for the identification of cohesive laws under pure loading modes

In this work, a new and simple methodology is proposed to identify the cohesive law of composite materials submitted to pure mode I and II loading. This methodology combines the experimental measured crack opening displacement and corresponding strain energy release rate with numerical simulation, using finite element method including cohesive zone modelling. The proposed procedure was tested and validated numerically, considering the determination of cohesive laws with different shapes for pure mode I and II loading. This was accomplished using the double cantilever beam (mode I) and end-notched flexure (mode II) tests. It was verified that the proposed methodology points towards the unicity of the identified solution and reproduces well the cohesive laws used as input.The first and third author acknowledges the Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020. The second author acknowledges FCT for the conceded financial support through the reference projects PTDC/EME-SIS/28225/2017 and UID/EEA/04436/2019. The fourth author acknowledges the “Laboratório Associado de Energia, Transportes e Aeronáutica”(LAETA) for the financial support by the project UID/EMS/50022/2013, and to the funding of Project NORTE-01-0145-FEDER-000022 - SciTech - Science and Technology for Competitive and Sustainable Industries, co-financed by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER)

The double cantilever beam test applied to mode I fracture characterization of polyamide 12 processed by selective laser sintering technology

In recent years, parts produced by Selective Laser Sintering (SLS) technology have aroused growing interest due to their valuable potential for end-use applications. However, to ensure the applicability of SLS products for advanced structural purposes, an accurate characterization of their mechanical behaviour is essential, which includes the assessment of fracture performance. Thus, cohesive zone modelling that allows mimicking damage initiation and propagation in quasi-brittle materials is used in this work to identify the cohesive laws of Polyamide 12 parts sintered by SLS with different values of energy density. This has been accomplished with success in this work for pure mode I loading employing the Double Cantilever Beam (DCB) test. In this context, experimental data is used to evaluate the critical energy release rate under quasi-static loading, by means of the Compliance-Based Beam Method (CBBM). The identification of the cohesive laws comprises finite element analysis to achieve accurate agreement with the experimental load-displacement curves obtained under quasi-static loading. The experimental protocols are duly validated for the tested conditions, which includes a developed numerical procedure combined with experimental data.The authors acknowledge the financial support given by FCT through the reference PhD research scholarship 2020.04520.BD, the reference projects UID/CTM/50025/2019 and UID/EEA/04436/2019, the European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COMPETE 2020) [Project n° 037902; Funding Reference: POCI-01-0247-FEDER-037902], the ‘Laboratório Associado de Energia, Transportes e Aeronáutica’ (LAETA) through the project UID/EMS/50022/2019 and the FCT/MCTES through national funds (PIDDAC)

On the evaluation of strain energy release rate of cement-bone bonded joints under mode II loading

Bone cements based on poly(methylmethacrylate) (PMMA) are primarily used in joint replacement surgeries. In the fixation of joint replacement, the self-curing cement fills constitutes a very important interface. To understand and improve the interaction between cortical bone and bone cement it is essential to characterize the mechanical properties of cement-bone bonded joints in full detail. In this study, the end-notched flexure test was used in the context of pure mode II fracture characterisation of cement-bone bonded joints. A data reduction scheme based on crack equivalent concept was employed to overcome the difficulties inherent to crack length monitoring during damage propagation. A finite element method combined with a cohesive zone model was first used to validate numerically the adopted method. The procedure was subsequently applied to experimental results to determine the fracture toughness of cement-bone bonded joints under pure mode II loading. The consistency of the obtained results leads to the conclusion that the adopted procedure is adequate to carry out fracture characterisation of these joints under pure mode II loading. The innovative aspect of the present work lies in the application of cohesive zone modelling approach to PMMA-based cement-bone bonded joints

Produtividade de palha, teor de N total na palha e nos grãos de milho cultivado sob diferentes doses de N em solo de várzea.

O nitrogênio (N) é o nutriente absorvido e exportado em maior quantidade, o de maior custo, e o que mais influencia a resposta em produtividade do milho. O objetivo deste trabalho foi avaliar o efeito de doses de N na produtividade de matéria seca de palha e nos teores de N total na palha e nos grãos de milho após a colheita, cultivado em solo de várzea sob sistema de drenagem subterrânea. O experimento foi desenvolvido em uma área pertencente à ESALQ/USP, Piracicaba, SP. Utilizou-se o delineamento experimental de blocos casualizados, com cinco tratamentos - 0, 50, 100, 150 e 200 kg ha -1 N - e três repetições. Concluiu-se que: (1) houve resposta quadrática as doses crescentes de N total para a produtividade de matéria seca de palha de milho; (2) a aplicação de N em doses crescentes proporcionou aumento de forma linear e positivo no teor de N total na parte aérea das plantas e nos grãos após a colheita

Crescimento e acúmulo de nutrientes em plantas de Shorgum bicolor L Moench sob irrigação com águas de diferentes concentrações salinas.

: Em muitas áreas irrigadas do mundo, o suprimento de água de boa qualidade pode não ser suficiente para a manutenção da agricultura irrigada, ou seu custo ser elevado, buscando-se alternativas com o uso de água do lençol freático ou mesmo de drenagem. Todavia, geralmente, essas águas não são de boa qualidade e uma das alternativas para viabilizar seu uso é misturá-las com água de baixa concentração de sais. Assim, o objetivo desse trabalho foi avaliar o desenvolvimento inicial e o acúmulo de sais pelo Shorgum bicolor L Moench, irrigado com água de diferentes concentrações salinas originadas da mistura de águas de qualidade diferentes. O experimento foi realizado em condições de casa de vegetação e os tratamentos foram constituídos da aplicação continuada de água de cacimba, do Rio São Francisco e de diferentes misturas entre elas. As unidades experimentais foram constituídas de sacolas plásticas com capacidade para 1,5 dm-3 de solo e o sorgo utilizado como planta indicadora. Os tratamentos foram dispostos em delineamento experimental inteiramente casualizado, com quatro repetições. O aumento da CEa e da RAS da água de irrigação influenciou no crescimento das plantas, reduzindo a produção de matéria fresca e seca da parte aérea, assim como na altura das plantas e número de folhas. O Na+ foi o elemento mais absorvido pela planta, tendo seu teor e acúmulo na matéria aumentado de forma linear e quadrática, respectivamente, em função da concentração salina da água de rrigação. Palavras-chave: RAS, CE, irrigação, sorg

Sistema para avaliação de risco de resistência de insetos a toxinas Bt expressas em culturas transgênicas.

O sistema RRiskBtWeb foi desenvolvido para avaliação de risco de evolução de resistência de insetos a toxinas Bt expressas em culturas transgênicas. A evolução de resistência de insetos a qualquer agente de controle é um processo natural e contribui para a redução da vida útil da tecnologia. RRiskBtWeb é uma versão WEB do software RRiskBt, desenvolvido em Visual Basic, em 2003. Naquela época, não era ainda permitido o cultivo de plantas transgênicas no Brasil e o software foi construído para auxiliar no estabelecimento de estratégias preventivas de manejo de resistência, anteriores à liberação da tecnologia de plantas transgênicas inseticidas. Recentemente, após 2013, começaram a surgir falhas de controle de importantes lepidópteros-praga nas lavouras de milho transgênico, acarretando sérios danos econômicos nos sistemas de produção. Esse evento motivou o desenvolvimento da versão mais acessível aos usuários em geral, o RRiskBtWeb, que pode ser executado em qualquer computador com um navegador de Internet. Esse sistema simula o processo de evolução da resistência em diferentes cenários, gerando informações cientificamente embasadas para auxílio à tomada de decisão sobre estratégias de manejo da resistência, especialmente o tamanho de refúgio. The RRiskBtWeb System was developed for assessing the risk of insect resistance evolution to Bt toxin expressed in transgenic insecticidal crops. Insect resistance evolution in response to any control agent is a natural process, which contributes to reduction of the technology useful life. RRiskBtWeb is a Web version of the RRiskBt software, developed in Visual Basic language in 2003. At that time, cultivation of transgenic crops was not still allowed in Brazil; the software was constructed as a tool for helping definition of preventive resistance management strategies, before liberation of the insecticidal plant technology. Recently, after 2013, control failures of important Lepidopteran pests started to appear in transgenic crop fields, leading to serious economic damage in the corn production systems. Such event motivated the development of a more accessible version, the RRriskBtWeb, which can be run in any computer with Internet browser. This system simulates resistance evolution process in different scenarios thus generating scientifically sound information for helping decision making on resistance management strategies, specially the refuge size

Mode I fracture characterization of wood using the SEN-TPB test

The single-edge-notched beam loaded in three-point-bending has been numerically analyzed to validate its adequacy tocharacterize wood fracture under pure mode I loading. This specimen geometry has been chosen since it is particularlyuseful to perform tests in those fracture systems impossible to be tested with the double cantilever beam (DCB). Thestudy revealed several aspects avoiding the direct measurement of fracture toughness in wood due to confinement of thefracture process zone (FPZ) under loading. This has been confirmed analyzing stress profiles of different specimensizes, differently affected by compression due to bending