Search results for "Process Engineering"
showing 10 items of 931 documents
Red blood cell plasmalogens and docosahexaenoic acid are independently reduced in primary open-angle glaucoma
2009
International audience; Among several theories involved in the pathogenesis of primary open-angle glaucoma (POAG), the vascular theory considers the disease to be a consequence of reduced ocular blood flow associated with red blood cell abnormalities. Red blood cell membrane structure and function are influenced by their phospholipid composition. We investigated whether specific lipid entities that may affect the membrane physiology, namely, polyunsaturated fatty acids (PUFAs) and plasmalogens, are modified in POAG and whether these potential variations are related to the stage of glaucoma. Blood samples were collected from 31 POAG patients and 10 healthy individuals. The stage of glaucoma …
Lipid and fatty acid profile of the retina, retinal pigment epithelium/choroid, and the lacrimal gland, and associations with adipose tissue fatty ac…
2008
International audience; Accumulation of lipids within Bruch’s membrane (BrM) and between BrM and retinal pigment epithelium (RPE) accounts for one of the biological changes associated with normal aging and may contribute to the development of age-related maculopathies. The origin of these lipids is still being actively investigated. The relative contribution of plasma lipids and lipids coming from the neural retina remains a matter of controversy. Low-density lipoproteins (LDLs) have been reported to significantly participate in the retina’s lipid supply, after active remodeling within RPE. Meanwhile, RPE expresses the enzymatic machinery for synthesizing lipoprotein-like particles. The obj…
Role of the basolateral amygdala in retrieval of conditioned flavors in the awake rat.
2014
International audience; Learned association between odor, taste and further post-ingestive consequence is known as flavor nutrient conditioned preference. Amygdala is supposed to be one of the areas involved in these associations. In the present study, one flavor was associated with a 16% glucose (CS+) whereas another flavor was paired with less reinforcing 4% glucose (CS-). We showed that CS+ presentation after conditioning increased Fos expression in the basolateral nucleus of amygdala (BLA). Furthermore, we performed electrophysiological recordings in the BLA in free moving rats. After preference acquisition, rats were exposed to either the CS+ or the CS-. The proportion of neurons showi…
Human newborns match tongue protrusion of disembodied human and robotic mouths
2011
International audience; No evidence had been provided so far of newborns' capacity to give a matching response to 2D stimuli. We report evidence from 18 newborns who were presented with three types of stimuli on a 2D screen. The stimuli were video-recorded displays of tongue protrusion shown by: (a) a human face, (b) a human tongue from a disembodied mouth, and (c) an artificial tongue from a robotic mouth. Compared to a baseline condition, neonates increased significantly their tongue protrusion when seeing disembodied human and artificial tongue movements, but not when seeing a 2D full-face protruding tongue. This result was interpreted as revealing the exploration of top-heavy patterns o…
Mass transfer and hydrodynamic characteristics of unbaffled stirred bio-reactors: Influence of impeller design
2014
Abstract Unbaffled stirred tanks are increasingly recognized as a viable alternative to common baffled tanks for a range of processes where the presence of baffles is undesirable for some reason. For instance, in the case of shear sensitive cell cultivation (e.g. human cells), unbaffled tanks have been recently found to be able to provide sufficient mass transfer through the free surface vortex. As a consequence the need for bubble formation and subsequent bursting, along with relevant cells damage, is conveniently avoided. In this work the influence of impeller geometry on mass transfer performance and power demand of an unbaffled stirred vessel operating both in sub-critical conditions (t…
Unbaffled, Stirred Bioreactors for Animal Cell Cultivation
2017
One of the main features of animal cell bioreactors is that the cultured cells lack a strong membrane and are therefore more prone to shear damage. It is widely accepted that animal cell damage in aerated bioreactors is mainly related to burst bubbles at the air–liquid interface. A viable alternative to sparged bioreactors, aimed at minimizing cell damage, may be represented by uncovered, unbaffled, stirred tanks, which are able to provide sufficient mass transfer through the deep free surface vortex that takes place under agitation. As a consequence the need for bubble formation and subsequent bursting accompanied by cell damage is conveniently avoided. In this chapter, mass transfer perfo…
Effect of the height-to-diameter ratio on the mass transfer and mixing performance of a biotrickling filter
2017
BACKGROUND Biotrickling filters (BTFs) are among the most widely used biological technologies for air pollution control. The pollutant removal rate in BTFs relies to a large extent on its gas–liquid mass transfer performance. Therefore, knowledge of the design parameters affecting the mass transfer and mixing performance of full-scale BTFs is of paramount importance. RESULTS This work showed that the height-to-diameter (H/D) ratio is an important parameter in the design of BTFs devoted to air pollution control. The H/D ratio significantly affected the mass transfer and mixing performance of the BTF with and without additional stirring in the holding tank. It was observed that under the same…
Application of low intensity ultrasonics to cheese manufacturing processes.
2002
Ultrasound has been used to non-destructively assess the quality of many foods such as meat, fish, vegetables and dairy products. This paper addresses the applications of low intensity ultrasonics in the cheese manufacturing processes and highlights the areas where ultrasonics could be successfully implemented in the future. The decrease of ultrasonic attenuation during the renneting process can be used to determine the optimum cut time for cheese making. The ultrasonic velocity increases during maturation for those types of cheese that become harder during this manufacturing stage, thus being an indicator of the maturity degree. Moreover, ultrasonic measurements could be linked to sensory …
A shear test for structural adhesives used in the consolidation of old timber
2001
A test method was developed specifically for structural adhesives used in thick joints. It is based on compressive shear loading of glued joints (GJ) and solid wood (SW) specimens, before and after a suitable accelerated ageing cycle. The evaluation of results is based on the ratios of wet strength to dry strength and on the comparison of GJ specimens to SW specimens which are prepared from the same batch of wood, in order to minimise the influence of the variability in wood characteristics. On a group of 10 epoxy-based adhesives, specifically marketed for the consolidation of old timber structures, the method has proved to be effective to differentiate the performances of each product. Amo…
On the origin of the sigmoid shape in the UO2 oxidation weight gain curves
2009
International audience; Cracking and spalling are known to occur during the oxidation of UO2. However, these phenomena are not considered by the existing kinetic models of the oxidation of UO2 into U3O8. In this study the oxidation of UO2 samples of various sizes from the single crystal to nanopowders, has been followed by isothermal and isobaric thermogravimetry, environmental scanning electron microscopy and in situ X-ray diffraction at temperatures ranging from 250 to 370°C in air. It has been shown that cracking occurs once a critical layer thickness of intermediate oxide has been reached, which corresponds to the beginning of the sigmoid kinetic curve. Cracking contribution to the sigm…