Search results for "STRESS"

An analysis of through-thickness residual stresses in aluminium FSW butt joints

2006

Abstract In the paper, the results of a wide experimental campaign on friction stir welding (FSW) of aluminum alloys are reported. The attention was focused on the through-thickness residual stresses that occur on aluminum joints, after the welding process. In detail, using the hole-drilling method the residual stresses distribution in the zone close to the tool shoulder border of the joint advancing side, has been investigated; four different aluminum alloys and three different process conditions have been considered. The experimental analysis has shown that unlike traditional welding processes, the residual stresses are negative in the surface of the examined zone, and increase with depth…

Measurement of residual stresses by the hole-drilling method: General stress-strain relationship and its solution

1990

RESIDUAL STRESS ANALYSIS OF ORTHOTROPIC MATERIALS BY THE THROUGH-HOLE DRILLING METHOD

2007

The present study deals with the development and the application of the through-hole drilling method for the residual stress analysis in orthotropic materials. Through a systematic theoretical study of the stress field present on orthotropic plates with a circular hole, the relationships between the relaxed strains measured by a rectangular strain gauge rosette and the Cartesian components of the unknown residual stresses are obtained. The theoretical formulas of each influence coefficient allow the user an easy application of the method to the analysis of uniform-residual stresses on a generic homogeneous orthotropic material. Furthermore, to extend the method to the analysis of the residu…

Optimal calculation steps for the evaluation of residual stress by the incremental hole-drilling method

1999

The integral method is a suitable calculation procedure for the determination of nonuniform residual stresses by semidestructive mechanical methods such as the hole-drilling method and the ring-core method. However, the high sensitivity to strain measurement errors due to the ill conditioning of the equations has hindered its practical use. the analysis of the influence of the strain measurment error on the computed stresses carried out in the present work has showed that, given both maximum hole depth and number of total steps, the error sensitivity depends on the particular depth increment distribution used. By means of the matrix formulation, the depth increment distribution that optimiz…

Estudio piloto sobre el estrés y la resiliencia familiar en recién nacidos prematuros

2016

Resumen: Introducción: La prematuridad se acompaña de patología severa, estancias prolongadas en el hospital e incertidumbre acerca del futuro de los pacientes. Estas circunstancias suponen un estrés que puede afectar al funcionamiento de la familia. El objetivo de este trabajo ha sido estudiar los factores de riesgo y de protección del funcionamiento familiar en prematuros comparados con neonatos sanos a término. Población y métodos: Se reclutó a prematuros que cursaron el periodo neonatal con y sin patología (n = 40) a los 24 meses de edad posconcepcional y un grupo control de nacidos a término sanos (n = 31) según datos de la historia clínica. El progenitor cuidador habitual respondió al…

Effects of heat and cold on health, with special reference to Finnish sauna bathing.

2018

Environmental stress such as extremely warm or cold temperature is often considered a challenge to human health and body homeostasis. However, the human body can adapt relatively well to heat and cold environments, and recent studies have also elucidated that particularly heat stress might be even highly beneficial for human health. Consequently, the aim of the present brief review is first to discuss general cardiovascular and other responses to acute heat stress, followed by a review of beneficial effects of Finnish sauna bathing on general and cardiovascular health and mortality as well as dementia and Alzheimer's disease risk. Plausible mechanisms included are improved endothelial and …

Hsp70 localizes differently from chaperone Hsc70 in mouse mesoangioblasts under physiological growth conditions

2008

Mouse A6 mesoangioblasts express Hsp70 even in the absence of cellular stress. Its expression and its intracellular localization were investigated under normal growth conditions and under hyperthermic stress. Immunofluorescence assays indicated that without any stress a fraction of Hsp70 co-localized with actin microfilaments, in the cell cortex and in the contractile ring of dividing cells, while the Hsc70 chaperone did not. Hsp70 immunoprecipitation assays confirmed that a portion of Hsp70 binds actin. Immunoblot assays showed that both proteins were present in the nucleus. After heat treatment Hsp70 and actin continued to co-localize in the leading edge of A6 cells but not on microfilame…

Effect of primary mild stresses on resilience and resistance of the nitrate reducer community to a subsequent severe stress

2008

International audience; The factors regulating soil microbial stability (e.g. resistance and resilience) are poorly understood, even though microorganisms are essential for ecosystem functioning. In this study, we tested whether a functional microbial community subjected to different primary mild stresses was equally resistant or resilient to a subsequent severe stress. The nitrate reducers were selected as model community and analysed in terms of nitrate reduction rates and genetic structure by narG PCR-restriction fragment length polymorphism fingerprinting. Heat, copper and atrazine were used as primary stresses and mercury at a high concentration as a severe stress. None of the primary …

The Saccharomyces cerevisiae zinc finger proteins Msn2p and Msn4p are required for transcriptional induction through the stress response element (STR…

1996

The MSN2 and MSN4 genes encode homologous and functionally redundant Cys2His2 zinc finger proteins. A disruption of both MSN2 and MSN4 genes results in a higher sensitivity to different stresses, including carbon source starvation, heat shock and severe osmotic and oxidative stresses. We show that MSN2 and MSN4 are required for activation of several yeast genes such as CTT1, DDR2 and HSP12, whose induction is mediated through stress-response elements (STREs). Msn2p and Msn4p are important factors for the stress-induced activation of STRE dependent promoters and bind specifically to STRE-containing oligonucleotides. Our results suggest that MSN2 and MSN4 encode a DNA-binding component of the…

Human HSP10 variants downregulation after cigarette smoke extract exposure in lung cells

2009

The impact of cigarette-smoke stress (a form of oxidative stress) on human lung fibroblasts and epithelial cells, particularly its effect on Hsp10 expression, has not been characterized despite the fact that a role for mitochondrial chaperonins in the development of lung diseases, ranging from chronic obstructive pulmonary disease to bronchial carcinogenesis, has been suggested (1). We studied the effects of non-lethal doses of cigarette smoke extract (CSE) on the expression of Hsp10 in human lung fibroblasts (HFL-1 line) and epithelial cells (16HBE line). Proteomics was carried out using 2D-IPG, silver stain, western blotting, and mass-spectrometry; mRNA was measured by RT-PCR. Database se…