Rectifier Characteristics of BaSo<sub>4</sub> Precipitation Membranes

Katzir-Katchalsky, Aharon; Hirsch-Ayalon, P.; Michaeli, I.

doi:10.1002/ijch.197300034

Cited by 13 publications

(3 citation statements)

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“…A quantitative theoretical analysis of the rectification behavior of these membranes has been formulated by Katzir-Katchalsky et al (1973). In contradistinction to the previous models, consisting of fixed charges, the electrical bilayer of precipitation membranes is formed by charges which are not fixed, and can easily and reversible be desorbed, thus making deconditioning and subsequent reconditioning possible.…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Precipitation membrane effects in biologic membranes: The role of calcium

1979

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Biologic membranes display rectification of electrical current, as well as other properties, in many respects similar to precipitation membranes. The experiments reported here, performed in frog skin, show that these characteristics are dependent upon the presence of calcium. Upon elimination of calcium from the bathing solution, the property of electrical rectification is lost, the current-voltage relation assuming a linear form. Readministration of calcium brings about complete recovery of the rectification pattern. This behavior is analogous to chemical deconditioning of precipitation membranes. Our findings support the assumption that the binding of calcium in biologic membranes produces electrical effects characteristic of precipitation membranes.

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Section: Theoretical Considerationsmentioning

confidence: 99%

Precipitation membrane effects in biologic membranes: The role of calcium

1979

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“…A BaS04 zone is considered to be in its "conditioned state" when it is in contact with bulk phases containig Ba+ ) and the precipitation zone has membrane properties (i. e. characteristic values of membrane potential, non-ohmic electric current-voltage characteristics, osmotic properties). It behaves like a sandwich membrane composed of an anion and a cation exchange membrane (adsorption charge model [7,8]). The BaS04 precipitation zone looses its membrane properties and changes to a "deconditioned state" if the ions forming the precipitate are removed from the bulk phase (e. g. H20/M (BaS04)/H20; loss of positive and negative adsorption charges at the surface of the crystallites).…”

Section: Introductionmentioning

confidence: 99%

Osmotic Properties of Crystalline Inorganic Precipitation Membranes: Study of Barium Sulfate Membranes

Milz

Forke

Woermann

et al. 1991

Ber Bunsenges Phys Chem

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BaSO4 precipitation zones with membrane properties (“conditioned state”: characteristic values of membrane potential, non‐ohmic electric current‐voltage characteristic) are generated by interdiffusion of iso‐osmotic aqueous solutions of BaCl2 and Na2SO4 within cellophane skins. In the “conditioned state” they are found to be impermeable to glucose, sucrose, and raffinose. Osmotic differences of these substances between the bulk phases as well as osmotic differences of BaCl2 and Na2SO4 cause an osmotic volume flow across the precipitation zone from which the hydrodynamic permeability of the precipitation membrane imbedded within cellophane skin can be calculated. The hydrodynamic permeability of a cellophane skin containing a BaSO4 precipitation zone in its “conditioned state” is smaller by a factor of more than 10 compared with that of an untreated cellophane skin. A precipitation zone looses its characteristic properties (“deconditioned state”) if the ions forming the precipitate (Ba++, SO4–) are removed from the bulk phases. This triggers changes of the properties of the surface of the BaSO4 crystallites and Ostwald ripening processes set in. Such a precipitation zone becomes permeable to glucose, sucrose, and raffinose. In the “deconditioned state” the hydrodynamic permeability of precipitations zones approaches nearly the value of an untreated cellophane skin. Adding again Ba+ + and SO4– ions to the bulk phase regenerates the electrochemical and osmotic properties of the precipitation zone. Low angle scattering patterns of synchroton radiation of freeze dried cellulose skins containing a BaSO4 precipitation zone in its “conditioned state” are analyzed in terms of a random structure model. It is found that the correlation length of local electron density fluctuations has a value of about 6 nm. This reflects the tight packing of BaSO4 crystallites forming a precipitation zone with membrane properties.

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“…In the case of polyelectrolytes, as the electrolytic environment is changed, large conformational transitions occur, and they developed the idea that muscular contraction was due to such interactions. From these beginnings not only the field of polyelectrolyte chemistry [2][3][4][5]8,9,[14][15][16][17][18][19]24,26,27,29,30,[32][33][34][35][36][38][39][40][41]43,45,46,48,50,51,57,59,61,62,65,69,73,74,76,95,99,102,111,112,114,121,133,138,…”

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confidence: 99%

The Aharon Katchalsky Memorial Lecture1

1973

BIR

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AHARON KATZIR-KATCHALSKY was an outstanding scientist and humanist, whose objective contributions to our knowledge and understanding had long before his tragic death assured him a place in the top rank of this century. The world can ill afford to lose such minds.Not for this alone, however, is he being missed and mourned. After all, these of his contributions stand and will remain. He is being missed and mourned, by hundreds of people all over the world, for something much more personal and precious, something which each had received from him, at some encounter, at a seminar, at a public lecture, at a private discussion, something of the excitement and wonder of the intellectual pursuit which he could so magically arouse and instil.There was no occasion which Aharon Katzir failed to improve with his mind and words. Whenever he talked he aroused our intellectual curiosity, stimulated our thoughts, brought forth our interest. Activities which seemed commonplace, subjects apparently banal, he could make engage our minds. He left his audience refreshed, mentally invigorated, newly encouraged in their work, revitalized in their interest.It is Aharon Katzir who should have delivered the Plenary Lecture he anticipated to give today on biological membranes and biorheology. It is with many sad thoughts and in deep sorrow that I am speaking about his work in his place.Biorheology, movement and life had always fascinated him and the field stood close to the center of his research interests.While life is motion, the absence of motion-thermodynamic equilibrium-is death. The further we are from equilibrium, the younger we are, the more alive, the fuller of motion. Living processes should be far from equilibrium, they should override their environment, interact strongly with it, be in command. Biorheology deals with living processes, it deals with the fluid mechanical aspects of life. We could paraphrase biorheology as life, flow and deformation.In pursuing these aims the biorheologist tends to go in two directions. On the one hand, from a macroscopic point of view, he wants to understand the principles and forces which produce motion; on the other, from the microscopic point of view, he looks for interpretation in the molecular dynamics and structure of the system. This duality of approach was not always realised. The early chemists and biochemists who established the macromolecular, polymeric nature of most biological structural and chemically specific material did not at first see this as a world in motion. They were writing chemical formulas on their paper and for them these structures did not move.It was left to Werner Kuhn to establish and show that, conformationally, macromolecules 109

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Rectifier Characteristics of BaSo₄ Precipitation Membranes

Cited by 13 publications

References 9 publications

Precipitation membrane effects in biologic membranes: The role of calcium

Precipitation membrane effects in biologic membranes: The role of calcium

Osmotic Properties of Crystalline Inorganic Precipitation Membranes: Study of Barium Sulfate Membranes

The Aharon Katchalsky Memorial Lecture1

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Rectifier Characteristics of BaSo4 Precipitation Membranes

Cited by 13 publications

References 9 publications

Precipitation membrane effects in biologic membranes: The role of calcium

Precipitation membrane effects in biologic membranes: The role of calcium

Osmotic Properties of Crystalline Inorganic Precipitation Membranes: Study of Barium Sulfate Membranes

The Aharon Katchalsky Memorial Lecture1

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Rectifier Characteristics of BaSo₄ Precipitation Membranes