Caractérisation physico-chimique et étude du frittage d'une argile destinée à l'élaboration de membranes de filtration tangentielle

Les procédés de filtration tangentielle sont actuellement reconnus comme des techniques de séparation de haute performance depuis le laboratoire jusqu'à la production industrielle. le cur de ces techniques est la membrane. Le présent travail a pour objectif de mettre au point des membranes en argile à bas prix de revient. Les résultats obtenus ont permis de comprendre le comportement de l'argile vis-à-vis des cycles thermiques imposés et de conclure que les membranes argileuses peuvent être utilisées en microfiltration et support en ultrafiltration tangentielle

Transition α – β type quartz dans les solutions solides Al

La transition α – β type quartz dans des solutions solides de AlP04 est étudiée par des analyses thermique et calorimétrique différentielles. Deux solutions solides ont été envisagées : Al(1–x)GaxPO4 et Al(PO4)(1–y)(AsO4)y La température de la transition se déplace vers les hautes températures en fonction de x (ou y). La transition semble disparaître pour des valeurs de x voisines de 0,02 à 0,03 et des valeurs de y voisines de 0,05 à 0,06

Ultrasonic investigation of ceramic clay membranes

International audienceClay membranes containing various percentages of coal before sintering have been manufactured in order to obtain various volume fractions of porosity. Using echographic techniques, the longitudinal ultrasonic velocity and damping have been measured between 0 and 20% of coal. These results, compared to porosity measurements show that there is a simple linkage between porosity and ultrasonic parameters. Furthermore, the anomalous behaviour of one batch of membranes has been detected with ultrasonic waves and confirmed using classical porosity measurements (triple weight method). A linear behaviour of the ultrasonic velocity versus porosity has been obtained from 38 to 60% of porosit

Effects of Short- and Long-Term Variations in RLS Severity on Perceived Health Status – the COR-Study

In a cohort study among 2751 members (71.5% females) of the German and Swiss RLS patient organizations changes in restless legs syndrome (RLS) severity over time was assessed and the impact on quality of life, sleep quality and depressive symptoms was analysed. A standard set of scales (RLS severity scale IRLS, SF-36, Pittsburgh Sleep Quality Index and the Centre for Epidemiologic Studies Depression Scale) in mailed questionnaires was repeatedly used to assess RLS severity and health status over time and a 7-day diary once to assess short-term variations. A clinically relevant change of the RLS severity was defined by a change of at least 5 points on the IRLS scale. During 36 months follow-up minimal improvement of RLS severity between assessments was observed. Men consistently reported higher severity scores. RLS severity increased with age reaching a plateau in the age group 45–54 years. During 3 years 60.2% of the participants had no relevant (±5 points) change in RLS severity. RLS worsening was significantly related to an increase in depressive symptoms and a decrease in sleep quality and quality of life. The short-term variation showed distinctive circadian patterns with rhythm magnitudes strongly related to RLS severity. The majority of participants had a stable course of severe RLS over three years. An increase in RLS severity was accompanied by a small to moderate negative, a decrease by a small positive influence on quality of life, depressive symptoms and sleep quality