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A probabilistic analysis of Miner’s law for different loading conditions
Sergio Blasón,José A.F.O. Correia,Abílio M.P. De Jesus,Rui A.B. Calçada,Alfonso Fernández-Canteli 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.1
In this paper, the normalized variable V=(log N-B)(log Δσ-C), as derived from the probabilistic S-N field of Castillo and Canteli, is taken as a reference for calculation of damage accumulation and probability of failure using the Miner number in scenarios of variable amplitude loading. Alternative damage measures, such as the classical Miner and logarithmic Miner, are also considered for comparison between theoretical lifetime prediction and experimental data. The suitability of this approach is confirmed for it provides safe lifetime prediction when applied to fatigue data obtained for riveted joints made of a puddle iron original from the Fão bridge, as well as for data from experimental programs published elsewhere carried out for different materials (aluminium and concrete specimens) under distinct variable loading histories.
Strain energy-based fatigue life prediction under variable amplitude loadings
Shun-Peng Zhu,Peng Yue,José Correia,Sergio Blasón,Abílio De Jesus,Qingyuan Wang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.2
With the aim to evaluate the fatigue damage accumulation and predict the residual life of engineering components under variable amplitude loadings, this paper proposed a new strain energy-based damage accumulation model by considering both effects of mean stress and load interaction on fatigue life in a low cycle fatigue (LCF) regime. Moreover, an integrated procedure is elaborated for facilitating its application based on S-N curve and loading conditions. Eight experimental datasets of aluminum alloys and steels are utilized for model validation and comparison. Through comparing experimental results with model predictions by the proposed, Miner’s rule, damaged stress model (DSM) and damaged energy model (DEM), results show that the proposed one provides more accurate predictions than others, which can be extended for further application under multi-level stress loadings.
Accumulation of High Levels of ABA Regulates the Pleiotropic Response of the nhr1 Arabidopsis Mutant
Francisco Quiroz-Figueroa,Adrián Rodríguez-Acosta,Amed Salazar-Blas,Elizabeta Hernández-Domínguez,Maria Eugenia Campos,Nobutaka Kitahata,Tadao Asami,Rosa M. Galaz-Avalos,Gladys I. Cassab 한국식물학회 2010 Journal of Plant Biology Vol.53 No.1
Plants have evolved a variety of mechanisms for responding to environmental cues, which allows them to survive in the presence of limited resources or environmental stresses. One of the most significant growth adaptations plants have attained is tropism, a growth response that involves bending of plant organs toward or away from a stimulus. Roots exhibit hydrotropism in response to moisture gradients, which is thought to be critical in acquiring water and establishing their stand in the soil. However, the mechanism underlying hydrotropism remains unsolved. Here, we report that the no hydrotropic response (nhr1) mutant of Arabidopsis, which is impaired in hydrotropism, is tolerant to drought. The no hydrotropic response phenotype of nhr1 was repressed by AbamineSG,an inhibitor of abscisic acid (ABA) biosynthesis, indicating that ABA negatively regulates hydrotropism. Furthermore,the content of ABA was higher in nhr1 compared to those of wild type (wt). However, the higher ABA levels in nhr1plants were not due to higher transcript levels of 9-cisepoxycarotenoid dioxygenase (NCED3), since these were diminished compared to those of wt. Our results indicated that the root hydrotropic response of the nhr1 mutant is modulated by ABA and that the higher ABA levels of the mutant might confer it drought resistance.
Silva-Correa Carmen R.,Villarreal-La Torre Víctor E.,González-Siccha Anabel D.,Cruzado-Razco José L.,González-Blas María V.,Sagástegui-Guarniz William Antonio,Calderón-Peña Abhel A.,Aspajo-Villalaz Ci 한국독성학회 2022 Toxicological Research Vol.38 No.2
Medicinal plants play an important role in the management of various diseases, so their use has become widespread. However, in some cases the population uses plant species regardless of the toxicity they may possess. The objective of this study was to evaluate the acute toxicity of aqueous extract from the leaves of Ambrosia arborescens Mill. on the biochemical and histopathological parameters of albino Holtzman rats. To do this, the leaves of A. arborescens were collected in the province of Julcan, La Libertad Region—Peru. OECD (Organisation for Economic Cooperation and Development) guideline 423 was conducted, forming experimental groups of 10 animals each one (5 males and 5 females): Group I (Control), which received 2 mL physiological saline solution (SSF 0.9%), Groups II and III (A. arborescens-300 and A. arborescens-2000), which were given the aqueous extract leaves of A. arborescens in a single dose of 300 and 2000 mg/kg/day, respectively. On the 14th day of exposure, biochemical (creatinine, ALT and AST) and histopathological parameters were measured. The results show that the aqueous extract of A. arborescens at the dose of 2000 mg/kg produces an increase in biochemical parameters which is related to histopathological analysis of liver and renal tissue with mild congestion. The study concludes that the aqueous extract leaves of A. arborescens has a LD50 greater than 2000 mg/kg and produces mild congestion in kidneys and liver, but showed no significant toxicological changes in the other albino Holtzman rats organs.