TERMIUM Plus^®

Record 1,  Textual support,  English

Record number: 1, Textual support number: 1 CONT

For a multi-pore membrane with high pore density, a large number of nanochannels are involved in energy conversion, and the total power generation is much greater than that of a single nanochannel. However, the interaction between the pores causes intense concentration polarization, which significantly reduces the driving force of ion transport. As a result, the output power density of the multi-pore membrane is only a few watts per square meter.  2, record 1, English, - output%20power%20density

Record 1,  Textual support,  French

Record number: 1, Textual support number: 1 CONT

[Des chercheurs] ont étudié l'influence du compost dans les biopiles à base de plants de riz et ont trouvé une amélioration de la densité de puissance produite [...]  1, record 1, French, - densit%C3%A9%20de%20puissance%20produite

Record 1,  Textual support,  Spanish

Record 2,  Textual support,  English

Record number: 2, Textual support number: 1 DEF

Well-mixed reactors which rely on a selective membrane to separate low molecular weight products from higher molecular weight substrates. They are therefore most useful for carrying out depolymerization reactions, especially when using soluble enzymes, so as to ensure good contact with macromolecular substrates. The main disadvantages associated with the use of these reactors are the small sizes of reactor available, and concentration polarization, that is blockage of the pores in the membrane by solid, fat or colloid particles present in the substrate.  1, record 2, English, - ultrafiltration%20reactor

Record number: 2, Textual support number: 1 CONT

Production of glucose from cellulose by enzymic methods has been investigated, and a procedure using an enzyme reactor having an ultrafiltration membrane has been reported for this purpose. Cellulose was heated at 200° C in a running porcelain pot mill for 25 min, ground to fine particles with a diameter of 50-150μ, and then suspended in water. The cellulose suspension was reacted with cellulase from Trichoderma viride in an ultrafiltration membrane reactor, and the resulting glucose syrup was continuously removed from the reactor through the membrane.  3, record 2, English, - ultrafiltration%20reactor

Record number: 2, Textual support number: 1 OBS

Similar selective membranes have also been used in hollow-fibre reactors, which can be used in a plug-flow fashion with substrate rapidly recirculated through the reactors, but with the enzyme located inside the fibre.  1, record 2, English, - ultrafiltration%20reactor

Record 2,  Textual support,  French

Record number: 2, Textual support number: 1 CONT

Les réacteurs à ultrafiltration présentent l'inconvénient de posséder un rapport surface de membrane/volume peu favorable. En outre, le phénomène de polarisation de la membrane qui résulte de l'accumulation de composés de masse molaire importante au voisinage de celle-ci provoque souvent une limitation non négligeable du débit. Les membranes d'ultrafiltration commercialisées surtout par AMICON et MILLIPORE, sont disponibles dans un très large éventail de seuils d'exclusion. Ce seuil est le paramètre essentiel intervenant dans le choix de ces membranes car il détermine aussi bien le degré de rétention de l'enzyme ou du substrat que le débit maximal pouvant être atteint.  1, record 2, French, - r%C3%A9acteur%20%C3%A0%20ultrafiltration

Record number: 2, Textual support number: 1 OBS

Dans le cas particulier des réacteurs à ultrafiltration où le débit est déterminé par le diamètre moyen des pores, le fait d'augmenter artificiellement par immobilisation la taille de la molécule d'enzyme, permet de travailler avec des membranes dont les pores ont un diamètre supérieur, c'est-à-dire à des débits plus élevés.  1, record 2, French, - r%C3%A9acteur%20%C3%A0%20ultrafiltration

Record 2,  Textual support,  Spanish

Record 3,  Textual support,  English

Record number: 3, Textual support number: 1 OBS

In order to avoid the risk of scale formation, [polarity reversal electrodialysis] consists in reversing the polarity of the electrodes on a regular basis(for instance for five minutes every 30-60 minutes), thus instantaneously switching the concentration and desalination compartments, and thereby the position of the polarization layers that change sides on the membrane.  1, record 3, English, - polarity%20reversal%20electrodialysis

Record 3,  Textual support,  French

Record number: 3, Textual support number: 1 CONT

[L']électrodialyse à inversion de polarité [...] consiste, pour éviter les risques d'entartrage, à inverser régulièrement la polarité des électrodes (par exemple 5 minutes toutes les 30 à 60 minutes) et à permuter ainsi instantanément compartiments de concentration et compartiments de dessalement et donc la position des couches de polarisation qui changent de côté de la membrane.  1, record 3, French, - %C3%A9lectrodialyse%20%C3%A0%20inversion%20de%20polarit%C3%A9

Record 3,  Textual support,  Spanish

Record 4,  Textual support,  English

Record number: 4, Textual support number: 1 DEF

Device enabling a larger surface area to be obtained without making large and unwieldy stacks of flat membrane. One only has to mould the membrane into a tube and then incorporate a number of such membrane tubes into a cartridge; liquid can then be recirculated through the cartridge and sufficient pressure for ultra-filtration obtained by restricting the flow downstream of the cartridge. In some systems the membrane may be moulded round a plastic rod which is grooved to produce a thin channel effect; it has been suggested that this is more efficient in reducing concentration polarization than a hollow membrane tube. The cartridge system has been used in various large-scale units with membrane areas of up to several square feet.  2, record 4, English, - cartridge%20membrane

Record number: 4, Textual support number: 1 OBS

Molecular weight cut-off range from 500 to 300,000.  1, record 4, English, - cartridge%20membrane

Record 4,  Textual support,  French

Record number: 4, Textual support number: 1 CONT

On préfère généralement installer un filtre par fermenteur plutôt que de filtrer dans une seule unité tout l'air distribué ensuite sur l'ensemble de l'atelier de fermentation. Ces filtres, ainsi que différents matériels de préfiltration, sont distribués par PALL-FRANCE. [...] D'autres firmes [...] proposent des cartouches à membranes plissées de ce type.  1, record 4, French, - cartouche%20%C3%A0%20membranes

Record 4,  Textual support,  Spanish

Record 5,  Textual support,  English

Record number: 5, Textual support number: 1 DEF

Phenomenon which arises as a result of the build-up of a layer of rejected solute at the membrane surface which impedes solvent flow. The resistance to flow due to this layer thus increases until a point is reached where the rate of diffusion of solute away from the polarization layer equals the rate of deposition. This phenomenon also explains why the solvent flux often becomes invariant with an increasing transmembrane pressure drop. Although solvent flux through a membrane is a hydraulic pressure-activated process and should increase with increasing pressure, a point is reached where the rate of build-up of the solute polarization layer is such that flow is impeded and further increases in pressure have no effect.  2, record 5, English, - concentration%20polarization

Record number: 5, Textual support number: 1 CONT

Concentration is the only important application with regard to initial enzyme recovery. Coarse fractionation is rarely attempted on a large scale, mainly because concentration polarisation ... occurs during ultra-filtration, effectively preventing an adequate separation. Equally, removal of salts and low molecular weight species alone is not the prime consideration, although ultrafiltration is commonly used to this end later in enzyme purification processes.  4, record 5, English, - concentration%20polarization

Record 5,  Textual support,  French

Record number: 5, Textual support number: 1 CONT

Grâce à leurs propriétés plastiques, les supports membranaires peuvent équiper des réacteurs de conceptions technologiques très diverses. Dans certains cas, la membrane constitue une simple barrière physique retenant les macromolécules dans le compartiment réactionnel : c'est le principe des membranes d'ultrafiltration utilisées pour récupérer le biocatalyseur dans les réacteurs agités. [...] Le principal inconvénient de cette technique est le phénomène de "polarisation" qui se traduit par une accumulation des composés de haut poids moléculaire sur la face amont de la membrane et un colmatage des pores.  2, record 5, French, - polarisation

Record 5,  Textual support,  Spanish

Record 6,  Textual support,  English

Record number: 6, Textual support number: 1 DEF

Ultrafiltration apparatus used in the removal of bacteria, pyrogen, virus; concentration of protein, virus; enzymes, and prefiltration of sample for electrophoresis. The cell holder consists of a bottom plate which contains the membrane with the membrane support and a reservoir; a top plate which contains a filling port, a pressure inlet. Magnetic stirring is built into the cell holder to minimize concentration polarization on the membrane surface and to avoid foaming when the volume is low.  2, record 6, English, - stirred%20cell

Record number: 6, Textual support number: 1 CONT

A stirred cell... is capable of pressurization, and the contents are stirred with a magnetic stirrer to prevent concentration polarization at the membrane. These units are available with capacities ranging from a few millilitres up to some 21. Although not suitable for large-scale work the units are useful for preliminary trials as well as concentration of column eluates.  3, record 6, English, - stirred%20cell

Record 6,  Textual support,  French

Record number: 6, Textual support number: 1 DEF

Unité d'ultrafiltration, sous vide ou sous pression, constituée d'un contenant de forme cylindrique à la base duquel sont placés la membrane et son support. Cette unité est également munie d'un agitateur magnétique dont la fonction sert à retarder le colmatage de la membrane.  2, record 6, French, - cellule%20%C3%A0%20agitation

Record 6,  Textual support,  Spanish

Record 7,  Textual support,  English

Record number: 7, Textual support number: 1 CONT

Concentration polarization is the development of a concentration gradient across the boundary layer near the membrane surface.  1, record 7, English, - concentration%20polarisation

Record 7,  Textual support,  French

Record number: 7, Textual support number: 1 DEF

Phénomène qui se produit toujours quand on effectue une séparation de substances macromoléculaires, moléculaires ou ioniques par une membrane et qui conduit à la formation, au voisinage de la face amont de la membrane, d'une couche dans laquelle se crée un gradient de concentration (Norme AFNOR).  1, record 7, French, - polarisation%20de%20concentration

Record number: 7, Textual support number: 1 OBS

Dans certains cas, ce phénomène conduit à la formation d'un gel.  1, record 7, French, - polarisation%20de%20concentration

Record number: 7, Textual support number: 2 OBS

La polarisation de concentration crée une résistance supplémentaire au transfert de matière. Pour réduire ce phénomène, on peut modifier les caractéristiques hydrodynamiques de l'écoulement.  1, record 7, French, - polarisation%20de%20concentration

Record number: 7, Textual support number: 3 OBS

La polarisation de concentration représente aujourd'hui le frein principal en séparation membranaire. Elle peut conduire à une diminution considérable des performances des appareils (osmose inverse, ultrafiltration et microfiltration tangentielle) en diminuant le flux de perméat.  1, record 7, French, - polarisation%20de%20concentration

Record number: 7, Textual support number: 4 OBS

concentration de polarisation : Le terme «concentration de polarisation» est déconseillé. C'est une mauvaise traduction de l'anglais «concentration polarisation».  1, record 7, French, - polarisation%20de%20concentration

Record 7,  Textual support,  Spanish

Record 8,  Textual support,  English

Record number: 8, Textual support number: 1 DEF

A transient decrease in membrane polarization induced in a postsynaptic neuron when subjected to a volley of impulses over an excitatory afferent pathway; summation of such potentials may cause discharge by the neuron.  2, record 8, English, - excitatory%20postsynaptic%20potential

Record 8,  Textual support,  French

Record number: 8, Textual support number: 1 DEF

Dépolarisation d'un élément postsynaptique consécutive à la libération de molécules neuromédiatrices par l'élément présynaptique.  2, record 8, French, - potentiel%20postsynaptique%20excitateur

Record 8,  Textual support,  Spanish

Record 9,  Textual support,  English

Record number: 9, Textual support number: 1 CONT

The phenomenon which causes solutes to concentrate at the filter's membrane surface forming a gel layer. The thickness of this gel layer will increase until its hydraulic resistance to solvent transport reduces the flux to an equilibrium value such that the convective transport of solutes on the surface equals the back diffusion from the surface. In single-pass operation the concentration of sulutes is low, so concentration polarization does not limit flux.  1, record 9, English, - concentration%20polarization

Record 9,  Textual support,  French

Record 9,  Textual support,  Spanish

Record 10,  Textual support,  English

Record number: 10, Textual support number: 1 CONT

The tubular membrane module provides significant advantages in terms of control of concentration polarization and membrane fouling.... Here the membrane is placed on the inside of porous stainless steel or fiberglass reinforced plastic tube.  1, record 10, English, - tubular%20membrane%20module

Record 10,  Textual support,  French

Record number: 10, Textual support number: 1 DEF

Module constitué de membranes tubulaires assemblées en faisceau à l'intérieur d'un carter de géométrie tubulaire.  1, record 10, French, - module%20tubulaire

Record number: 10, Textual support number: 1 OBS

Le module tubulaire a pour avantage de permettre une circulation rapide, la filtration de liquides de haute viscosité et le décolmatage à contre-courant. Il a pour inconvénient une surface spécifique réduite.  1, record 10, French, - module%20tubulaire

Record 10,  Textual support,  Spanish