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

MODE I FRACTURE CHARACTERIZATION: WOOD SEN-TPB

The single edge notched beam loaded in three-point-bending (SEN-TPB) was used in this study to induce mode I fracture in wood (Picea abeas L.). Numerical analyses of stress profiles along the specimen length revealed a stress relief region as crack grows in size. Based on this data, beam theory and crack equivalent concepts were employed to develop an expedite data reduction scheme to estimate the Resistance-curve, taking advantage of a simplification performed on the revealed stress relief region. Besides allowing the evaluation of wood fracture toughness without crack length monitoring during loading, the developed procedure provides a user-friendly method when compared to other sophisticated procedures. Experiments involving the SEN-TPB were performed to evaluate fracture toughness in wood

Wood beam repairing with carbon-epoxy composites

Wood damaged beams submitted to bending loads were repaired using carbon-epoxy patches. The effect of patch thickness as well as adhesive filleting were both studied experimentally and numerically. The objective was to verify the influence of these aspects on the strength and failure of the repaired structural components. Cohesive zone modeling considering mixedmode (I+II) loading was carried out to simulate the observed experimental behavior. It was concluded that repair can successful recover the original bearing capacity, although patch thickness and adhesive filleting did not reveal a significant gain on strength

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)

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

NMR structural elucidation of the arabinan from Prunus dulcis immunobiological active pectic polysaccharides

The structure of the arabinan moiety of a purified arabinan-rich pectic polysaccharide from the cell walls of Prunus dulcis seeds was investigated by NMR spectroscopy. This polymer, which is able to induce a lymphocyte stimulatory effect, had an arabinan glycosidiclinkage composed of T-Araf: (1→5)-Araf: (1→3,5)-Araf: (1→2,3,5)-Araf in the relative proportions of approximately 3:2:1:1. Based on the ¹H, ¹³C, COSYPR, gHSQC and gHMBC spectra of analysed arabinan, a tentative structure is presented, showing that it is composed by a very branched and, possibly, repetitive structure of seven residues. The observed (1→5) direct linkage between (1→2,3,5)- Araf and (1→3,5)-Araf residues support the occurrence of these contiguous branched residues in the arabinan backbone.Fundação para a Ciência e a Tecnologia (FCT)University of Aveiro

Characterization of the structural, thermal, mechanical and electrical properties of bacterial cellulose

Although chemically similar to plant cellulose, bacterial cellulose (BC) produced by Gluconoacetobacter xylinum, a strict aerobe bacteria, is chemically pure, as is deprived of non-cellulosic polysaccharides (Jonas et al., 1998; Vandamme et al., 1998; Klemm et al., 2001; Amano, et al., 2005; Helenius et al., 2006). Its unique properties include high water holding capacity, high crystallinity, ultrafine fiber network, high tensile strength in the wet state, the ability to be shaped into 3D structures during synthesis (in-situ moldability) and excellent shape retention (Klemm et al., 2001; Helenius et al., 2006). The unique properties provided by the nanomeric structure of BC offer a wide range of applications such as in the human and veterinary medicine, odonthology, pharmaceutical industry, acoustic and filter membranes, biotechnological devices and in the food and paper industry. This work is focused on the production and characterization of bacterial cellulose from Gluconoacetobacter xylinus (ATCC 53582 and ATCC 10245 strains) concerning its structural, thermal, mechanical, electrical and morphological properties

Aplicabilidad de escalas/indicadores para el control del dolor en pacientes críticamente incapaces de verbalizar: una revisión sistemática de la literatura

Objective: To conduct a systematic review of the existing literature about the applicability of scales/indicators for pain monitoring in critically ill patients who are unable to verbalize. Methods: We performed a systematic review of the literature, according to the Joanna Briggs Institute's guidelines, in the following databases: MEDLINE, CINAHL, and Cochrane Central Register of Controlled Trials. The search was executed using, as main descriptors, "Critically Ill Patient", "Pain", "Scale" and "Instrument", in Portuguese, English, Italian, and Spanish. We considered the period between January 2012 and December 2017, and obtained a total of 149 results. From these, we selected 11 fi nal full-text articles for extraction and analysis, which met the required inclusion criteria. Two researchers made the search and two independent reviewers carried out the critical evaluation, extraction and synthesis of the data. Results: The key to adequate pain management lies in detecting and assessing several indicators, such as: facial expression, vocalization, body movements, muscle tone, adaptation to mechanical ventilation. Subsequently, it is fundamental to intervene accordingly and to reassess the patient's status. The BPS (Behavioral Pain Scale) and the CPOT (Critical-care Pain Observation Tool) are considered the most appropriate scales for pain assessment in critically ill patients who are incapable of verbalizing. While the BPS should only be used in ventilated patients, the CPOT can be used in both ventilated and non-ventilated patients. Conclusion: The BPS and the CPOT are two scales recognized as reliable, valid, and easy to apply, for pain monitoring in critically ill patients who are unable to verbalize their pain.Objetivo: Llevar a cabo una revisión sistemática de la literatura existente sobre la aplicabilidad de escalas/indicadores para el control del dolor en pacientes críticamente enfermos que no pueden verbalizar. Métodos: Se realizó una revisión sistemática de la literatura en las siguientes bases de datos: MEDLINE, CINAHL y el Registro Cochrane Central de Ensayos Controlados, como descriptores principales “Paciente en estado crítico”, “Dolor”, “Escala” e “Instrumento”. Consideramos el periodo entre enero de 2012 y diciembre de 2017, y obtuvimos un total de 149 resultados. De estos, seleccionamos 12 artículos finales de texto completo para extracción y análisis, que cumplieron con los criterios de inclusión requeridos. Dos revisores independientes llevaron a cabo la evaluación crítica, extracción y síntesis de los datos. Resultados: La clave para el manejo adecuado del dolor radica en detectar y evaluar varios indicadores, tales como: expresión facial, tamaño de la pupila, vocalización, movimientos corporales, tono muscular, adaptación a la ventilación mecánica, presión arterial y frecuencia cardiaca. Posteriormente, es fundamental intervenir en consecuencia y reevaluar el estado del paciente. La BPS (Escala de dolor conductual) y la CPOT (herramienta de observación del dolor en cuidados críticos) se consideran las escalas más adecuadas para la evaluación del dolor en pacientes críticos que son incapaces de verbalizar. Si bien el BPS solo se debe utilizar en pacientes ventilados, el CPOT se puede usar tanto en pacientes ventilados como no ventilados. Conclusión: el BPS y el CPOT son dos escalas reconocidas como confiables, válidas y fáciles de aplicar para el control del dolor en pacientes críticamente enfermos que no pueden verbalizar su dolor.info:eu-repo/semantics/publishedVersio