Experimental investigation of multi-material aluminum-to-steel and GFRP-to-steel bonded and bolted/bonded connections

Abstract : Through an experimental study, this paper describes the behavior of single-lap bonded, bolted and bolted/bonded connections for configurations with minimum geometric parameters proposed in design references. Two types of multi-material connections are considered: Glass Fiber Reinforced Polymer (GFRP)-to-steel and aluminum-to-steel. At first, the behavior of multi-material bonded connection using methacrylate and epoxy adhesives is evaluated. Then experimental results of bolted connections are presented. Finally, the contribution of adhesive in GFRP-to-steel and aluminum-to-steel bolted connections is investigated. Test results show that on single-lap simply bonded joints, failures mostly occur at the substrate to adhesive interface. Sanding the GFRP plate was found to improve the connection strength. Despite their lower elastic modulus, methacrylate adhesives with larger elongation provides better strength due to their high resistance in peeling. For bolted/bonded joints, the adhesive was found to improve the elastic behavior and the strength of GFRP-steel joints while its effect for aluminum-steel joints was not apparent due to reduce bonded surface and the high strength performance of the bolted plates

Effect of geometric parameters on the behavior of bolted GFRP pultruded plates

Abstract : This paper presents the effect of geometric parameters on the behavior of bolted GFRP pultruded plates for civil engineering applications. After a literature review, results of an experimental analysis investigating the behavior of GFRP-to-steel single-lap bolted connections are presented. Then, a finite element analysis validated by experimental data is used to evaluate the effects of the end-distance, side-distance, gage, pitch and plate properties on the strength and failure mode of the connection. A critical examination of geometric recommendations proposed in design references is presented. Bearing failure caused by contact of the bolt on the GFRP plate is usually defined as the preferred failure mode. With highly orthotropic plate, this type of failure was found to be less likely to occur when loading is applied in the pultruded direction. The investigation showed that the minimum end-distance and pitch-distance recommended by design references usually produce a connection with the maximum capacity. However, it was found that the minimum side-distance recommended by these references does not necessarily lead to the maximum capacity for one-bolt and for two-bolt in a column connections

Cucurbitacin E has neuroprotective properties and autophagic modulating activities on dopaminergic neurons

Natural molecules are under intensive study for their potential as preventive and/or adjuvant therapies for neurodegenerative disorders such as Parkinson’s disease (PD). We evaluated the neuroprotective potential of cucurbitacin E (CuE), a tetracyclic triterpenoid phytosterol extracted from the Ecballium elaterium (Cucurbitaceae), using a known cellular model of PD, NGF-differentiated PC12. In our postmitotic experimental paradigm, neuronal cells were treated with the parkinsonian toxin 1-methyl-4-phenylpyridinium (MPP+) to provoke significant cellular damage and apoptosis or with the potent N,N-diethyldithiocarbamate (DDC) to induce superoxide () production, and CuE was administered prior to and during the neurotoxic treatment. We measured cellular death and reactive oxygen species to evaluate the antioxidant and antiapoptotic properties of CuE. In addition, we analyzed cellular macroautophagy, a bulk degradation process involving the lysosomal pathway. CuE showed neuroprotective effects on MPP+-induced cell death. However, CuE failed to rescue neuronal cells from oxidative stress induced by MPP+ or DDC. Microscopy and western blot data show an intriguing involvement of CuE in maintaining lysosomal distribution and decreasing autophagy flux. Altogether, these data indicate that CuE decreases neuronal death and autophagic flux in a postmitotic cellular model of PD.peer-reviewe

Améliorer la détection et le traitement des psychoses débutantes au Québec : L’Association québécoise des programmes pour premiers épisodes psychotiques (AQPPEP) y voit

Juin 2004 : l’AQPPEP (Association québécoise des programmes pour premiers épisodes psychotiques) (http://www.aqppep.com/) voit le jour. Son rôle est de favoriser les échanges cliniques et scientifiques entre les professionnels et les chercheurs qui s’intéressent aux personnes atteintes de psychose débutante, et de permettre une détection plus précoce de la psychose. Elle vise également une prise de conscience de cette problématique par la population et les instances gouvernementales. À cette fin, l’AQPPEP a organisé la première journée québécoise de sensibilisation à la psychose, et développé un des rares sites internet francophones dans ce domaine. Dans un esprit de concertation, l’Association constitue un outil pour affronter les problèmes que plusieurs cliniques pour premiers épisodes psychotiques rencontrent, pour partager et développer des solutions communes entre elles.June 2004: the Quebec association of early psychosis programs, AQPPEP (Association québécoise des programmes pour premiers épisodes psychotiques), was created. The Association’s objectives is to promote clinical and scientific discussions between health care professionals and researchers sharing an interest for people suffering from an early psychosis, and to improve earlier detection of psychosis. It also aims at increasing awareness of the problem in the general population and governments. To reach these goals, AQPPEP has organized the first early psychosis awareness day in Quebec and developed one of the rare French language web sites in this area. Finally, the Association is a tool to better face, in a concerted approach, some difficulties that many first episode clinics have to deal with, in order to share or develop common solutions.Junio de 2004: se crea la AQPPEP (Asociación Quebequense de Programas Para los Primeros Episodios Psicóticos) (http://www.aqppep. com/). Su papel consiste en favorecer los intercambios clínicos y científicos entre los profesionales y los investigadores que se interesan en las personas que sufren de psicosis inicial, y permitir una detección más temprana de la psicosis. También busca la toma de conciencia de este problema por parte de la población y las instancias gubernamentales. Para ello, la AQPPEP organizó el primer día quebequense de sensibilización a la psicosis y desarrolló uno de los pocos sitios Internet francófonos en este campo. Con un espíritu de concertación, la Asociación constituye una herramienta para afrontar los problemas que encuentran varias clínicas para los primeros episodios psicóticos, además de compartir y desarrollar soluciones comunes entre ellas.Junho de 2004: Criação da AQPPEP, Associação Quebequense dos Programas para os Primeiros Episódios Psicóticos (Association québécoise des programmes pour premiers épisodes psychotiques -http://www.aqppep.com/). Seu papel é favorecer os intercâmbios clínicos e científicos entre os profissionais e os pesquisadores que se interessam pelas pessoas que sofrem de psicose inicial, e permitir uma detecção mais precoce da psicose. Ela visa, igualmente, uma tomada de consciência desta problemática pela população e pelas instâncias governamentais. Para este fim, a AQPPEP organizou a primeira jornada quebequense de sensibilização à psicose, e desenvolveu um dos raros sites francófonos na Internet nesta área. Com um espírito de comum acordo, a Associação constitui uma ferramenta para enfrentar os problemas que várias clínicas encontram com respeito aos primeiros episódios psicóticos, compartilhar e desenvolver soluções comuns entre elas

Effect of geometrical parameters of aluminum-to-steel bolted connections

Abstract : Through experimental and numerical studies, this research work aims to provide directions on the optimal geometric configuration for single-lap and double-lap bolted connection between aluminum alloy 6061-T6 and steel. From experimental test results, the effects of different geometric parameters on the joint strength were discussed. These parameters include the end-distance, the side-distance, the pitch-distance, the plate thickness and the joint eccentricity. Then, the experimental results were compared to predicted results using design references and geometric recommendations proposed by design references were critically examined. The experimental study was complemented by finite element (FE) analysis to extend the study to a larger range of parameters. In addition to the analysis of the geometric parameters listed above, the effects of the gage-distance on the joint strength were studied in the FE analysis. The experimental and finite element results show that a careful selection of geometric parameters can result in the high improvement of the connection strength and failure mode. Limiting the side-distance to the minimum recommended value was found to limit the strength of a connection with two bolts in a column to that of the one-bolt connection. In most cases, bearing was found to govern the strength of the connections. The calculated bearing strengths were found to underestimate significantly the connection strength. Based on these analyses, maximum geometric parameters beyond which there is no further increase of the joint capacity were evaluated and optimum geometric parameters were proposed

La perception de la menace nucléaire soviétique par l'Office of Reports & Estimates, 1946-1950 : pourquoi ont-ils raté la bombe?

Québec Université Laval, Bibliothèque 201