Search results for " gas-liquid"
showing 6 items of 6 documents
International descriptive and interventional survey for oxycholesterol determination by gas- and liquid-chromatographic methods
2018
International audience; Increasing numbers of laboratories develop new methods based on gas-liquid and high-performance liquid chromatography to determine serum concentrations of oxygenated cholesterol metabolites such as 7alpha-, 24(S)-, and 27-hydroxycholesterol. We initiated a first international descriptive oxycholesterol (OCS) survey in 2013 and a second interventional survey 2014 in order to compare levels of OCS reported by different laboratories and to define possible sources of analytical errors. In 2013 a set of two lyophilized serum pools (A and B) was sent to nine laboratories in different countries for OCS measurement utilizing their own standard stock solutions. In 2014 eleven…
Oxygen transfer performance of unbaffled stirred vessels in view of their use as biochemical reactors for animal cell growth
2012
Cultivation of microorganisms, plants or animal cells requires liquid agitation in order to ensure oxygen and nutrient transfer and to maintain cell suspension. However, In such suspensions both mechanical agitation and sparging aeration can cause cell death. Many studies on animal cell damage due to mechanical agitation and sparging aeration have shown that mechanical damage of freely suspended animal cells is in most cases associated with bursting bubbles at the air–liquid interface (Barrett et al., 2010, Nienow et al., 1996). Gas bubbles are usually generated by direct air sparging to propagate oxygen in a culture suspension. Mechanical agitation may also introduce gas bubbles to the cul…
Caratterizzazione del pattern lipidico e degli acidi grassi del muscolo dell’ibrido Acipenser naccarii (Bonaparte, 1836) x A. baerii (Brandt, 1869) e…
2002
Muscle phospholipids and tryglicerides were measured in two sturgeon (Acipenseridae) hybrids. Fatty acid composition of the two lipidic fractions showed a strong similarity between the two hybrids.
Oxygen Transfer Performances of Unbaffled Bio_Reactors with Various Aspect Ratios
2014
Cultivation of microorganisms, plants or animal cells requires liquid agitation in order to ensure oxygen and nutrient transfer and to maintain cell suspension. Many studies on animal cell damage due to mechanical agitation and sparging aeration have shown that mechanical damage of freely suspended animal cells is in most cases associated with bursting bubbles at the air–liquid interface (Barrett et al., 2010). Gas bubbles are usually generated by direct air sparging aimed at supplying oxygen to the culture medium. Mechanical agitation may also introduce gas bubbles in the culture medium via vortexing entrainment from the free surface. In this work oxygen transfer performance of an unbaffle…
CFD simulation of gas-liquid stirred vessels
2006
Computational Fluid Dynamics is an increasingly important tool for carrying out realistic simulations of process apparatuses. As a difference from single phase systems, for multipliase systcms the development of CFD models is still at its early stages. In the present work CFD simulations of gasliquid stirred tanks are reported. All bubbles are assumed to share the same size, and a simplified approach is adopted for the description of momentum exchanges between tile two phases. In particular ir is shown that the only parameter needed for modeling drag forces is bubble terminal velocity. Results show that in a quite wide range encompassing most practical applications, bubble size has a limite…