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Donnan equilibrium Summary In the absence of a Donnan equilibrium, the bulky sodium molecule would not normally tend to move across the membrane and an electrical potential would be created. Donnan equilibrium refers to the distribution of ion species between two ionic solutions separated by a semipermeable membrane or boundary. Donnan equilibrium is prominent in the triphasic model for articular cartilage proposed by Mow and Ratcliffe, as well as in electrochemical fuel cells and dialysis. www.bookrags.com /Donnan_equilibrium   (495 words)

Donnan Equilibrium: World of Microbiology and Immunology Donnan equilibrium (which can also be referred to as the Gibbs-Donnan equilibrium) describes the equilibrium that exists between two solutions that are separated by a membrane. The membrane, however, does not allow the passage of all the ions present in the solutions and is thus a selectively permeable membrane. Donnan equilibrium is named after Frederick George Donnan, who proved its existence in biological cells. science.enotes.com /microbiology-encyclopedia/donnan-equilibrium   (174 words)

Bond Graph Modelling of Electrolyte Gel For example, the Donnan equilibrium membrane potential is the electric potential difference across the membrane induced by the balance between the individual ion diffusion tendencies and the bulk electroneutrality in each region. Therefore, in most case, the Donnan equilibrium condition and the bulk electroneutrality is valid even in the non-equilibrium case with net transport, and they may be employed as the boundary conditions for the states of gel/membrane's bulk units. As with the Donnan quasi-equilibrium model considered previously, the dissipated energy (heat of reaction) and the entropy generation are assumed to be unimportant in the overall dynamics of the ion's transport for the quasi-equlibrium chemical reaction model. www.ai.mit.edu /projects/muscle/papers/elegel/ele.htm   (3337 words)

Lehigh - Environmental Engineering Research Theoretically, Donnan membrane process (DMP) is not susceptible to fouling because particulate matter or large organic molecules do not concentrate on the membrane surface, as commonly observed with pressure driven membrane processes. Donnan membrane process is uniquely capable of recovering alum from WTR in a single-step process using sulfuric acid and a cation-exchange membrane. In the Donnan membrane cell, the feed side of the membrane contained 6.0 liters of the decanted and slightly acidified WTR collected from the AWTP while the recovery side contained 1.5 liters of 10% sulfuric acid solution, separated by a cation-exchange membrane Nafion 117. www.lehigh.edu /~aks0/Prakhar'sPAge/Prakhar'sPage.htm   (1317 words)

Donnan   (Site not responding. Last check: 2007-10-13) Donnan was educated at Queen's College in Belfast, N. Ireland, from 1889 to 1893 (BA in 1892) and in 1894 he received MA from the Royal University of Ireland. In 1911 Donnan studied the conditions under which equilibrium is established between two electrolytic solutions separated by a semipermeable membrane--that is, by a membrane through which the solvent and some, but not all, of the dissolved ions can pass. The equilibrium characterized by an unequal distribution of diffusible ions between two ionic solutions (one or both of the solutions may be gelled) separated by a membrane which is impermeable to at least one of the ionic species present, e.g. www.geocities.com /bioelectrochemistry/donnan.htm   (705 words)

NICA-Donnan model The partitioning of ions between the two phases is governed by a Donnan equilibrium. The amount of cation bound is assumed to be in equilibrium with the concentration of the cation in the Donnan phase. is the concentration of the reacting ion in the Donnan phase, and p is the site-specific non-ideality. www.colorado.edu /ceae/environmental/ryan/cven3454/spreadsheets/nicadonnan.htm   (2012 words)

The UCL Periodic Table of the Lecturers: George Frederick Donnan Donnan worked in the Department for several years, his work including studies of deviations from Graham 's law of effusion, and was co-editor with Ramsay of a very successful series of Textbooks of Physical chemistry, published by Longmans and Green. For more information on the Donnan equilibrium see the animated lecture from Texas A and M (2.1 Mb). Donnan, who was blind in one eye is depicted in profile above in a manner reminiscent of Piero della Francesca's famous portrait of the Duke of Urbino, Federigo da Montefeltro (in the Uffizi Gallery in Florence) shown below: www.chem.ucl.ac.uk /resources/history/people/donnan.html   (349 words)

23Na-Nuclear Magnetic Resonance Study of Ionophore-Mediated Cation Exchange between Two Populations of Liposomes -- ... A model system to observe and investigate the transfer of Na+ ions between different internal compartments in a suspension of liposomes was developed, and the exchange was followed by nuclear magnetic resonance spectroscopy. Donnan potentials and ionic compositions at equilibrium for the three-compartment system were calculated numerically. The model system may be used to explore further the effects of membrane potentials, surface potentials, and ionic mobilities on ion transport in biological (model) systems in general. library.wolfram.com /infocenter/Articles/873   (169 words)

MEMBRANE POTENTIALS The equilibrium potential is related to the logarithm of the ratio of internal and external concentrations of the diffusible ion as described by the Nernst potential. Observations early in this century by the physical chemists Gibbs and Donnan with regard to equilibrium of diffusable and impermeant ions across semipermeable membranes have been applied to understanding the basis for the unique distribution of ion concentrations across the membranes of excitable tissues. The Donnan Rule holds-- this states that at equilibrium the products of the diffusible ions on the two sides of the membrane are equal. www.med.mun.ca /tedhoekman/trans/trans2.htm   (906 words)

ELECTROCHEMICAL TERMS IN COLLOID AND SURFACE CHEMISTRY Potential determining ions are those species of ions which by virtue of their equilibrium distribution between the two phases (or by their equilibrium with electrons in one of the phases) determine the difference in Galvani potential between these phases. Donnan equilibrium is the equilibrium characterized by an unequal distribution of diffusible ions between two ionic solutions (one or both of the solutions may be gelled) separated by a membrane which is impermeable to at least one of the ionic species present, e.g. , is the Donnan emf between a suspension and its equilibrium liquid. www.iupac.org /reports/2001/colloid_2001/manual_of_s_and_t/node41.html   (668 words)

Fluid Physiology: 6.2 Regulation of Cell Volume The high intracellular concentration of non-diffusable anions leads to a Gibbs-Donnan equilibrium across the cell membrane. At equilibrium (if it occurred), electroneutrality would be preserved on both sides of the membrane but there would be more particles (higher osmolality) intracellularly. Overall, the equilibrium situation is that the Gibbs-Donnan effect due to the impermeant extracellular sodium balances the Gibbs-Donnan effect due to the impermeant intracellular colloids. www.anaesthesiamcq.com /FluidBook/fl6_2.php   (1281 words)

Computation of the Electrical Double Layer Properties of Semipermeable Membranes in Multicomponent Electrolytes -- ... All ions are assumed to freely penetrate the membrane. Donnan phenomena in membranes with charge due to ion adsorption: effects of the interaction between adsorbed charged groups. The influence of A-band and B-band lipopolysaccharide on the surface characteristics and adhesion of Pseudomonas aeruginosa to surfaces. aem.asm.org /cgi/content/full/64/6/2295   (3203 words)

Michael Thomas Flanagan's Java Library: Class Donnan The Donnan potential is calculated using a Nelder and Mead simplex non-linear minimisation procedure which minimises the square of the total bulk charge in Compartment B, which should equal zero at equilibrium, i.e This does not detract greatly, in most situations, from the calculation of the Donnan potential as the interface ion concentration is usually a very small fraction of the total ion concentration and the inclusion of the interface charge in the calculation of the Donnan potential allows: The initial estimate of the Donnan Potential, in volts, is entered using this method. www.ee.ucl.ac.uk /~mflanaga/java/Donnan.html   (4306 words)

Determinants of plasma water sodium concentration as reflected in the Edelman equation: role of osmotic and ... Determinants of plasma water sodium concentration as reflected in the Edelman equation: role of osmotic and Gibbs-Donnan equilibrium -- Nguyen and Kurtz 286 (5): F828 -- AJP - Renal Physiology equilibrium and the osmotic coefficient of Na salts at physiological Of note, if the movement of water were not prevented by the closed-system conditions depicted in the figure, osmosis would occur and compartment 1 would expand at the expense of compartment 2. ajprenal.physiology.org /cgi/content/full/286/5/F828   (4589 words)

Research School SENSE > Research descriptions > Biospec: Development and applications of the Donnan Membrane Technique To achieve this objective, a systematic approach will be adopted in which well-defined simple ligands, isolated natural ligands, soil solution samples and natural freshwaters are analysed in parallel by a range of analytical techniques in conjunction with metal biouptake studies. The Donnan Membrane Technique contains a continuous flow system, in which the donor side and the acceptor side of the DMT cell are continuously flushed with solution across the membrane. The cell allows reaching pseudo equilibrium for the free metal ions via Donnan Equilibrium across a negatively charged ion-exchange membrane within a reasonable time span. www.sense.nl /articles/1725   (502 words)

Model for Counterion-Membrane-Fixed Ion Pairing and Donnan Equilibrium in Charged Membranes We have studied theoretically the effects of counterion-membrane-fixed ion pairing on the Donnan equilibrium in charged membranes with low dielectric constant regions. Second, we calculate the membrane effective charge concentration and the ionic activity coefficients by using a simple model of ion pairing based on the Fuoss approach for contact ion pairs in electrolyte solutions with a correction term for the entropy change of the counterion undergoing ion pairing. Though it seems established that membrane inhomogeneity is the mainly responsible for the deviations from the ideal Donnan equilibrium observed experimentally in charged membranes, the theoretical approach presented here can be useful for those cases where conclusive experimental evidence for ion pairing exists. pubs.acs.org /cgi-bin/abstract.cgi/jpcbfk/1997/101/i10/abs/jp962601b.html   (214 words)

Assignment #11: due April 19, 2004 Measurements on living, eukaryotic cells show some strong deviations from those Donnan equilibrium relations. If ions aren’t in equilibrium, there must be ion currents flowing right through the membrane. The transmembrane sodium-potassium ion pump regulates ion concentrations in living eukaryotic cells to prevent an osmotic catastrophe. physics.syr.edu /courses/PHY315.05Spring/PHY315S05_assign11.htm   (242 words)

Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations We have studied theoretically the effects of counterion-membrane-fixed ion pairing on the Donnan equilibrium in charged membranes with low dielectric constant regions. First, the formal relationship between the ionic activity coefficients in the membrane and the membrane effective charge concentration is established by comparing the results obtained from a model based on the ideal Donnan equilibrium extended to account for the ion pairing effect with results obtained from a thermodynamic formalism including ionic activities instead of concentrations. Though it seems established that membrane inhomogeneity is mainly responsible for the deviations from the ideal Donnan equilibrium observed experimentally in charged membranes, the theoretical approach presented here can be useful for those cases where conclusive experimental evidence for ion pairing exists. www.osti.gov /energycitations/product.biblio.jsp?osti_id=501898   (345 words)

Electrochemistry D The concept of the Donnan potential is analogous to that of the equilibrium electrode potential. The overall result will be that the net movement of the sodium ions into the lower concentration solution will slow and eventually stop when the two opposing forces are equal end the two opposing fluxes are equal. In this so called "Donnan equilibrium," the diffusional flux of the sodium ions in one direction will be equal to the electromigrational flux in the opposite direction, resulting in net zero mass transport and zero charge transport. www.corrosion-doctors.org /Dictionary/Dictionary-D.htm   (2066 words)

New insights into the pathophysiology of the dysnatremias: a quantitative analysis -- Nguyen and Kurtz 287 (2): F172 -- ... equilibrium and that TBW is passively distributed in proportion In the absence of Gibbs-Donnan equilibrium, the [Na pw Nguyen MK and Kurtz I. Determinants of the plasma water sodium concentration as reflected in the Edelman equation: role of osmotic and Gibbs-Donnan equilibrium. ajprenal.physiology.org /cgi/content/full/287/2/F172   (4991 words)

Quantitative interrelationship between Gibbs-Donnan equilibrium, osmolality of body fluid compartments, and plasma ... Quantitative interrelationship between Gibbs-Donnan equilibrium, osmolality of body fluid compartments, and plasma water sodium concentration -- Nguyen and Kurtz 100 (4): 1293 -- Journal of Applied Physiology Articles by Nguyen, M. Articles by Kurtz, I. Quantitative interrelationship between Gibbs-Donnan equilibrium, osmolality of body fluid compartments, and plasma water sodium concentration equilibrium, the osmolality of body fluid compartments, and jap.physiology.org /cgi/content/abstract/100/4/1293   (312 words)

Sect. 7, Ch. 2: Plasma Colloid Osmotic Pressure and The Donnan Equilibrium   (Site not responding. Last check: 2007-10-13) Due to the Donnan equilibrium the plasma colloid osmotic pressure may be as much as 50% higher than that calculated based on plasma protein concentration alone. This occurs because the negatively changed proteins restrict an equivalent number of cations to the plasma compartment. Because they are retained in the PV by the protein these cations are osmotically effective across the capillary membrane and increase the protein oncotic pressure. www.lib.mcg.edu /edu/eshuphysio/program/section7/7ch02/7ch02p26.htm   (189 words)

Hollow Polyelectrolyte Shells: Exclusion of Polymers and Donnan Equilibrium Hollow Polyelectrolyte Shells: Exclusion of Polymers and Donnan Equilibrium By means of adding PSS in acidic form to the bulk solution, a Donnan equilibrium between the bulk and internal solution encapsulated within the capsules was created. The developed shell system represents a novel class of stable colloids combining the compartmentalization of an aqueous solution with the possibility of creating pH differences on the micrometer scale. pubs.acs.org /cgi-bin/abstract.cgi/jpcbfk/1999/103/i31/abs/jp990095v.html   (244 words)

Donnan potentials from striated muscle liquid crystals. Sarcomere length dependence. -- Aldoroty et al. 47 (1): 89 -- ... Donnan potentials from A-bands and I-bands were measured as were used in conjunction with Donnan equilibrium theory to calculate equilibrium theory, an algorithm was developed to predict A-band www.biophysj.org /cgi/content/abstract/47/1/89   (132 words)

donnan - OneLook Dictionary Search Donnan : Columbia Gazetteer of North America [home, info] Donnan : Stedman's Online Medical Dictionary, 27th Edition [home, info] Phrases that include donnan: donnan equilibrium, gibbs donnan equilibrium, donnan frederick, eilean donnan, gibbs donnan e, more... www.onelook.com /?w=donnan   (115 words)

The Donnan Equilibrium: A Theoretical Study of the Effects of Interionic Forces -- Stell and Joslin 50 (5): 855 -- ...   (Site not responding. Last check: 2007-10-13) The Donnan Equilibrium: A Theoretical Study of the Effects of Interionic Forces -- Stell and Joslin 50 (5): 855 -- Biophysical Journal Articles by Stell, G. Articles by Joslin, C. The Donnan Equilibrium that characterize this equilibrium, the osmotic pressure established www.biophysj.org /cgi/content/abstract/50/5/855   (157 words)

Amazon.com: "The Donnan": Key Phrase page   (Site not responding. Last check: 2007-10-13) The Donnan equilibrium system in muscle 33 fact maintain a perfect selectivity for potassium over the whole concentration range, and that the... Key Phrases in this book: Drosophila Shaker, The Donnan, sodium hypothesis, frog muscle fibres, arginine phosphate, squid giant axon, membrane capacity, striation pattern, pacemaker potential, sodium permeability, myelinated nerve fibre, frog nerve, filament theory, isometric tension, neighbouring nodes, squid axon, sodium conductance, myelinated fibre, ionic movements, potassium permeability, intercalated discs ( Donnan Ringtones -- Download Complimentary donnan ringtones Instantly. amazon.com /phrase/The-Donnan   (208 words)

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