Effects of heat treatments on the microstructure and mechanical properties of a 6061 aluminium alloy

International audienceThis paper describes the mechanical behavior of the 6061-T6 aluminium alloy at room temperature for various previous thermal histories representative of an electron beam welding. A fast-heating device has been designed to control and apply thermal loadings on tensile specimens. Tensile tests show that the yield stress at ambient temperature decreases if the maximum temperature reached increases or if the heating rate decreases. This variation of the mechanical properties is the result of microstructural changes which have been observed by Transmission Electron Microscopy

Value of syndromic surveillance within the Armed Forces for early warning during a dengue fever outbreak in French Guiana in 2006

<p>Abstract</p> <p>Background</p> <p>A dengue fever outbreak occured in French Guiana in 2006. The objectives were to study the value of a syndromic surveillance system set up within the armed forces, compared to the traditional clinical surveillance system during this outbreak, to highlight issues involved in comparing military and civilian surveillance systems and to discuss the interest of syndromic surveillance for public health response.</p> <p>Methods</p> <p>Military syndromic surveillance allows the surveillance of suspected dengue fever cases among the 3,000 armed forces personnel. Within the same population, clinical surveillance uses several definition criteria for dengue fever cases, depending on the epidemiological situation. Civilian laboratory surveillance allows the surveillance of biologically confirmed cases, within the 200,000 inhabitants.</p> <p>Results</p> <p>It was shown that syndromic surveillance detected the dengue fever outbreak several weeks before clinical surveillance, allowing quick and effective enhancement of vector control within the armed forces. Syndromic surveillance was also found to have detected the outbreak before civilian laboratory surveillance.</p> <p>Conclusion</p> <p>Military syndromic surveillance allowed an early warning for this outbreak to be issued, enabling a quicker public health response by the armed forces. Civilian surveillance system has since introduced syndromic surveillance as part of its surveillance strategy. This should enable quicker public health responses in the future.</p

Correlation between clinical and pathological features of cutaneous calciphylaxis.

Calciphylaxis is a rare and life-threatening disease that classically manifests with painful skin lesions. It occurs mainly in patients with end-stage renal disease (ESRD) treated with dialysis, has poor outcomes, and has no FDA-approved treatment. Our cohort study aims to examine the clinical and pathological features of calciphylaxis and investigates the correlation between cutaneous clinical manifestations and histopathological findings. Data from 70 calciphylaxis patients who were evaluated at the Massachusetts General Hospital between January 2014 and April 2018 were collected from the institutional electronic database. The median age was 58 years (interquartile range [IQR]: 49-69 years), 60% were women, and 73% were of white race. Most (74%) patients reported severe pain at the time of calciphylaxis diagnosis with a median pain intensity score of 8/10 (IQR: 6-10) on a 0-10 pain scale. The median time from symptom onset to clinical diagnosis was 9 weeks (IQR: 6-16 weeks). The majority (87%) of patients presented with open necrotic wounds (advanced stage lesion) at the time of diagnosis. Common cutaneous clinical features included ulceration (79%), induration (57%), and erythema (41%), while common pathological features included cutaneous microvascular calcification (86%) and necrosis (73%). The presence of fibrin thrombi in skin biopsies was associated with pain severity (p = 0.04). The stage of a skin lesion positively correlated with the presence of necrosis on histological analyses (p = 0.02). These findings have implications for improving understanding of calciphylaxis origins and for developing novel treatments

Finding the missing link in single use fermentation line : Evaluation of single use bioreactors for aerobic bacteria

The application of single use technologies for the bioproduction represents a major technology innovation advance. Single use bioreactors for cell culture have been largely implemented for manufacturing, providing significant flexibility, costs reduction and fast implementations. In contrast, few technologies are available for aerobic bacterial fermentation mainly due to limitations for oxygen and heat transfer. Like clinical products derived from bacterial expression system still represent a significant number of bio therapeutics/vaccines, some investigations have been performed in Sanofi Pasteur to evaluate new single use fermenters suitable for aerobic process and matching to clinical manufacturing scale. The 300L HyPerforma SUF (ThermoFisher) has been evaluated with an E.coli strain to produce a recombinant protein and with yeast

Measuring both thermal and kinematic full-fields using a single CMOS camera during high temperature tests

International audienceIn numerous domains, both kinematic and thermal fields are sought to study temperature dependent phenomena. They are usually obtained by digital image correlation and infrared thermography, respectively. Although these techniques are well mastered, their combination is not straightforward since they need radically different conditions to work efficiently. This paper presents a procedure to measure accurately thermal and kinematic full-fields simultaneously using a single CMOS camera in a chosen region of interest. The kinematic field is measured by global digital image correlation and the thermal field by near-infrared thermography for temperatures above 700 °C. A procedure is detailed to identify the radiometric model and compute the thermal field without being affected by the heterogeneous emissivity of the sample surface caused by the speckle pattern. A methodology showing how to manage temperature measurements during high thermal transients is also presented. The proposed approach aims to be widely accessible since it does not need strong knowledge in DIC algorithms and only requires a standard camera. The method is first validated on a virtual test case, before being used on real experiments performed at high temperature with a stereo setup

Thermo-mechanical behavior of Zircaloy-4 claddings under simulated post-DNB conditions

International audienceThe thermo-mechanical behavior of Zircaloy-4 claddings under simulated post-DNB RIA conditions was investigated. Around twenty experiments were performed in simulated post-DNB conditions, i.e. creep ballooning tests with heating rates greater than 1000°C/s. Two different levels of pressure of 7 and 11 bar were tested for temperatures of interest ranging from 840°C to 1020°C. A complex creep behavior was highlighted in this range of temperature. It appears very well correlated to the phase content present within the material during fast thermal transients. Tests with low thermal transients were also performed and evidence a strong impact of the heating rate on the thermo-mechanical properties of the claddings

Corrigendum to “Cyclic behaviour of a 6061 aluminium alloy: Coupling precipitation and elastoplastic modelling”[Acta Mater. 83 (2015) 256―268]

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Cyclic behaviour of a 6061 aluminium alloy: Coupling precipitation and elastoplastic modelling

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