Adaptation of High-Growth Influenza H5N1 Vaccine Virus in Vero Cells: Implications for Pandemic Preparedness

Current egg-based influenza vaccine production technology can't promptly meet the global demand during an influenza pandemic as shown in the 2009 H1N1 pandemic. Moreover, its manufacturing capacity would be vulnerable during pandemics caused by highly pathogenic avian influenza viruses. Therefore, vaccine production using mammalian cell technology is becoming attractive. Current influenza H5N1 vaccine strain (NIBRG-14), a reassortant virus between A/Vietnam/1194/2004 (H5N1) virus and egg-adapted high-growth A/PR/8/1934 virus, could grow efficiently in eggs and MDCK cells but not Vero cells which is the most popular cell line for manufacturing human vaccines. After serial passages and plaque purifications of the NIBRG-14 vaccine virus in Vero cells, one high-growth virus strain (Vero-15) was generated and can grow over 108 TCID50/ml. In conclusion, one high-growth H5N1 vaccine virus was generated in Vero cells, which can be used to manufacture influenza H5N1 vaccines and prepare reassortant vaccine viruses for other influenza A subtypes

Indirect measurement of the ice content curve of partially frozen cement based materials

International audienceThe goal of this paper is to investigate the validity of indirectly built ice content curves from porous network characterization tests to predict the behavior of a freezing cement based material. To do so, the results obtained by the two classical methods, namely the mercury intrusion porosimetry (MIP) and the gravimetric water desorption (WD) tests, are compared with the direct measurement of the ice content with a dielectric capacitive apparatus. A corrective approach, based on an interface energy analysis between the in-pore phases, is proposed in order to increase the accuracy of MIP based prediction of the ice saturation curve. The impact of the method used to estimate the ice saturation curve on the behavior of freezing porous medium is evaluated and discussed in the framework of poromechanics. © 2013 Elsevier B.V

Analyse micromécanique des variations dimensionnelles du Polystyrène expansé

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Elastic behavior of saturated porous materials under undrained freezing

International audienceThe elastic behavior of saturated porous materials under undrained freezing is investigated by using a poromechanical approach. Thermodynamic equilibria are used to describe the crystallization process of the partially frozen solution in bulk state and confined state in pores. By phase transition at freezing, fusion energy, thermal contraction of solid, solution and ice crystals, volume changes of crystallization build up remarkable pore pressure that induces expansion or shrinkage of solid matrix. Owing to the lower chemical potential when pore water mixes with salts, fewer ice forms in pores. Penetration of ice into the porous materials increases the capillary pressure, but limits effect on the pore liquid pressure and the strain of solid matrix. On the contrary, the pore pressure induced by solution density rises as salt concentration increases and causes significant shrinkage of solid matrix. © 2013 The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg

Détermination des Caractéristiques Viscoélastiques du polystyrène au sein de billes expansibles

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Une meilleure compréhension du gel des matériaux cimentaires en présence de sel pour un béton durable

Ce texte présente les méthodes d'essais de caractérisation de résistance au gel actuellement applicables en France. Ces essais en place depuis 10 à 20 ans ont largement contribué à l'amélioration de la prescription et de la durabilité des bétons face à la résistance au gel en présence de sels. Dans une deuxième partie, la distribution et la répétabilité ainsi que la méthode d'analyse du résultat de l'essai d'écaillage XP P18-420 sont évalués au travers d'un nombre significatif d'essais sur des bétons composés d'un ciment de Portland avec un agent entraîneur d'air

Influence of the saturation state of recycled sand on mortars compressive strength

This paper investigates the water content of pre-saturated recycled concrete aggregates (RCA) that has a diameter of 1-4 mm called recycled sand (RS), in order to determine the degree of saturation of the RS. It also puts forward the effects of the saturation state of the RS on the mechanical properties. For this matter, experiments were conducted in this research as: evaporation method to determine the water content of the RS and the compressive strength of mortars. These properties are tested for different saturation states and different saturation methods of the RS and for two types of curing conditions: laboratory curing conditions (LCC) and water immersion conditions (WIC). Results show that the standard method (NF EN 1097-6) largely underestimates the water absorption coefficient of RCA and that the saturation state of the RS and curing conditions affects the compressive strength of mortar

Penetration of chlorides in hardened concrete during frost salt scaling cycles

Sixty samples from three concrete mixes (same components) were prepared and subjected to frost salt scaling cycles. A set of 20 samples from the same mix was tested according to the French standard XP P18-420. Another set was exposed to different chloride concentrations. Different numbers of freeze/thaw cycles were applied to the last set. The mass of scaled-off particles follows a lognormal distribution. Despite high standard deviation, this scaling test enables to separate high resistant from very low resistant concrete. A combined analysis reveals that the scaling and the chloride penetration front are independent from a phenomenological point of view and that the chloride concentration on the exposed surface directly influences the amount of scaled mass according to the typical pessimum effect. These results raise two main questions: is the amount of chloride on the surface solution a direct or indirect parameter and what happens to this pessimum effect if we take into account the scaling test dispersion