scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1943 ◽  
Vol 26 (3) ◽  
pp. 309-323 ◽  
Author(s):  
Karl Sollner ◽  
Charles W. Carr
Keyword(s):  
Structural Theory ◽  
Electrochemical Activity ◽  
Electrical Behavior ◽  
Phase Theory ◽  
Varying Thickness ◽  
Maximum Value ◽  
Electrochemically Active ◽  
Concentration Potential ◽  
Characteristic Concentration ◽  
Constant Maximum

1. Experiments were carried out to decide whether or not the electromotive properties of dried collodion membranes depend upon their thickness. 2. A number of dried collodion membranes of varying thickness, 3–160 µ, were prepared from collodion preparations of different electrochemical activity. The characteristic concentration potentials across them were measured and the means of these values determined for each thickness. 3. The characteristic concentration potentials across dried collodion membranes are a function of their thickness. The thinnest membranes yield in all cases the lowest concentration potentials; increasingly thicker membranes give increasingly higher potential values, until a constant value is reached which is characteristic of the particular collodion preparation used. With electrochemically active collodion, characteristic concentration potentials approaching the thermodynamically possible maximum are obtained with membranes of only 10 µ thickness, thinner membranes giving appreciably lower values. With two rather inactive commercial collodion preparations the characteristic concentration potential increases from about 30 mv. for membranes 3 µ thick to about 42 mv. for 20 µ membranes; still thicker membranes do not show a significant increase in the potential values. With a highly purified collodion preparation the constant maximum value was found to be about 32 mv., 4 µ thick membranes giving only about 22 mv. 4. These results do not support the homogeneous phase theory as applied to the dried collodion membrane. They are readily compatible with the micellar-structural theory. Several special possible cases of the latter as applied to the dried collodion membrane are discussed.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1944 ◽  
Vol 28 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Karl Sollner ◽  
Charles W. Carr
Keyword(s):  
Experimental Data ◽  
Electrochemical Activity ◽  
Structural Factors ◽  
Electrical Behavior ◽  
Base Exchange ◽  
Basic Assumptions ◽  
Potentiometric Selectivity ◽  
Concentration Potential ◽  
Order Of Magnitude ◽  
Concentration Levels

1. The Teorell, Meyer-Sievers theory characterizes the electrochemical behavior of membranes by their selectivity constant "Ap" which is derived conventionally from concentration potential measurements at various concentration levels. The selectivity constant may, however, be derived also from entirely independent, different experimental data, namely base exchange studies. The constants arrived at in this second way are designated as "Ab." The selectivity constants derived by these two methods must be in reasonable, at least semiquantitative agreement if the basic assumptions of the theory are correct. 2. The selectivity constants Ap and Ab were determined for eleven different sets of membranes of different electrochemical activity and of different (8.2 to 80 volume per cent) water content. 3. The potentiometric selectivity constants Ap are in most cases several orders of magnitude greater than the corresponding Ab values. With membranes of great porosity and high electrochemical activity the Ab values approach at least in order of magnitude the Ap values. 4. It is concluded that the unexpectedly large discrepancy between the Ap and Ab values is due to some inherent weakness of the Teorell, Meyer-Sievers theory, most likely to its neglect of any structural factors.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1942 ◽  
Vol 26 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Karl Sollner ◽  
Charles W. Carr
Keyword(s):  
Oxidation State ◽  
Maximum Concentration ◽  
Structural Theory ◽  
Experimental Results ◽  
Phase Solubility ◽  
Electrical Behavior ◽  
Solution State ◽  
Homogeneous Phase ◽  
Characteristic Concentration ◽  
Strong Electrolytes

1. Experiments were carried out to decide whether a homogeneous phase (solubility) theory or a micellar-structural theory more adequately describes the behavior of dried collodion membranes with solutions of strong electrolytes. 2. A number of dried collodion membranes were prepared from an electrochemically inactive collodion preparation (state I); the characteristic concentration potentials across them were low, about 30 mv. The membranes were activated by oxidation (state II) to give maximum or nearly maximum concentration potentials (about 50 mv.). The oxidized membranes are dried, dissolved in alcohol-ether, and a new set of dry collodion membranes prepared from this solution (state III). The concentration potentials across these membranes are low. 3. Since the properties of a homogeneous phase should not be influenced by a rearrangement of its constituent particles, the experimental results do not support a homogeneous phase (solubility) theory, but they agree with the predictions of the micellar-structural theory. The characteristic behavior of dried collodion membranes in solutions of strong inorganic electrolytes is therefore due to the micellar character of its interstices.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1944 ◽  
Vol 27 (5) ◽  
pp. 433-449 ◽  
Author(s):  
Karl Sollner ◽  
Joan Anderman
Keyword(s):  
Solvent Mixture ◽  
Exchange Capacity ◽  
Acid Number ◽  
Electrochemical Activity ◽  
Time Base ◽  
Equivalent Weight ◽  
Base Exchange ◽  
Electrochemically Active ◽  
Organic Solvent Mixture ◽  
High Base

1. The electrochemical behavior ("activity") of collodion membranes depends upon acidic, dissociable groups located in the interstices of the membranes. The active groups can be determined by base exchange measurements. High base exchange capacity is always found with preparations of great "electrochemical activity;" medium and low base exchange capacities occur with electrochemically active as well as with inactive preparations. The observed base exchange capacity is determined by two factors: the inherent acidity of the collodion (its mean equivalent weight) and the submicroscopic micellar structure of the collodion. A comparison of the base exchange capacity of various collodion preparations and their inherent acidities therefore allows certain conclusions to be drawn concerning the relative availability of the micellar surfaces in the different preparations. 2. The inherent acidity of various collodion preparations, their "acid number," was determined by electrometric titration. Collodion in the acidic state, i.e. after exchange of all other cations for H+ ions, was titrated in an organic solvent mixture with alcoholic KOH using a quinhydrone electrode. Details of the experimental procedure are given in the paper. The acid numbers, expressed in milliliters of 0.01 N KOH per gram dry collodion, vary from 1.0 for a highly purified collodion preparation of very low electrochemical activity to 3.3 for a highly oxidized sample of very high activity. Acid numbers of about 1.5 (corresponding to an equivalent weight of about 67,000) are found both with inactive commercial and with fairly active oxidized preparations. The base exchange capacity of the same preparations in the fibrous state as measured after 48 hours of exchange time varies from 0.0013 ml. 0.01 N NaOH per gm. dry collodion for the most inactive preparation up to 0.26 ml. 0.01 N NaOH per gm. for the most active preparation. Thus the acid numbers over the whole range investigated differ only in the ratio of 1:3.3, whereas the base exchange values differ in the range of 1:200. 3. In the inactive preparation only one in 770 acid groups is available for base exchange, in the most active collodion one group in 13; values between these extremes are found with commercial and alcohol purified oxidized preparations. 4. The high base exchange capacity of the electrochemically active preparations is not so much due to their higher acid number as to their more open structure. This difference in structure is ascribed to the presence of a small fraction of low molecular weight material which inhibits normal formation and arrangement of the micelles. 5. Short time base exchange experiments with fibrous collodion indicate that the number of acid groups available for the typical electrochemical membrane functions may be estimated to be about 50 to 1000 times less numerous than those found in the 48 hour base exchange experiments. It is estimated that in membranes prepared even from the most active collodion not more than one in 500 acid groups may be available for the typical membrane functions; with the less active preparations this ratio is estimated to be as high as one in 1,000,000 or more.

scholarly journals Transformation Pathways of Reductones in the Advanced Maillard Reaction

2009 ◽  
Vol 27 (Special Issue 1) ◽  
pp. S149-S152 ◽  
Author(s):  
M. Konečný ◽  
K. Cejpek ◽  
L. Čechovská ◽  
J. Velíšek
Keyword(s):  
Maillard Reaction ◽  
Binary Systems ◽  
Amperometric Detection ◽  
Electrochemical Activity ◽  
Active Compounds ◽  
Condensation Products ◽  
Hplc System ◽  
Electrochemically Active ◽  
Transformation Pathways ◽  
Unknown Structure

The transformation of methylene-active reducing Maillard intermediates 4-hydroxy-5-methyl-2<I>H</I>-furan-3-one (norfuraneol, 1) and 2,3-dihydro-3,5-dihydroxy-6-methyl-4<I>H</I>-pyran-4-one (DDMP) was studied in heated (at 70–95°C up to 2 h) model aqueous binary systems containing various reactive carbonyl Maillard intermediates. Among them, furan-2-carbaldehyde and its derivatives 5-hydroxymethylfuran-2-carbaldehyde and pyrrol-2-carbaldehyde react intensely with the above reductones resulting in significant formation of consecutive reducing products. The active products formation and changes in total electrochemical activity were evaluated by using HPLC system with amperometric detection. The active products are consisted of primary reductone-carbaldehyde adducts (2a, b) that dehydrate to major active stereoisomeric condensation products (3a, b). The latter are hydrolysed to still electrochemically active compounds (4a, b) with yet unknown structure. Norfuraneol is transformed by 67–94% after 2 h heating at 95°C and pH 7 depending on a carbaldehyde, while DDMP react much slowly. Up to 42% of the initial norfuraneol electrochemical activity remains retained in the consecutive products depending on time and carbaldehyde involved.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1945 ◽  
Vol 28 (3) ◽  
pp. 179-185 ◽  
Author(s):  
Charles W. Carr ◽  
Harry P. Gregor ◽  
Karl Sollner
Keyword(s):  
Protamine Sulfate ◽  
Electrical Behavior ◽  
Regular Shape ◽  
Characteristic Concentration ◽  
Rotating Tubes

The technique of Abrams and Sollner for the preparation of electropositive dried protamine collodion membranes has been improved. Porous collodion membranes cast on the outside of rotating tubes are treated for 48 hours with a solution of 2 per cent protamine sulfate buffered at pH 11. After being washed thoroughly the membranes are dried in air for several hours, soaked in water for several hours, and removed from the tubes. Further drying in air but without support shrinks the membranes slightly. The resulting membranes are designated "permselective" or "megapermselective" protamine collodion membranes. These membranes regularly give characteristic concentration potentials of –52 to –53 mv. and (in 0.1 M KCl) resistance of 0.5 to 15 ohms per membrane of 50 cm.2 area. This resistance is several orders of magnitude smaller than that of the conventional dyestuff- and alkaloid-impregnated positive membranes. The megapermselective protamine collodion membranes can be kept either dry or in water for prolonged periods without detectable deterioration. They are quite smooth, have a regular shape, and stand considerable handling without breakage. The megapermselective protamine collodion membranes are the electropositive analogues of the electronegative megapermselective collodion membranes described by Carr and Sollner.

The Filter-Feeding of Artemia

1963 ◽  
Vol 40 (1) ◽  
pp. 195-205
Author(s):  
M. R. REEVE
Keyword(s):  
Cell Size ◽  
Filtration Rate ◽  
Cell Concentration ◽  
Ingestion Rate ◽  
Plant Cells ◽  
A Value ◽  
Maximum Value ◽  
Pure Cultures ◽  
Constant Maximum ◽  
Maximum Ingestion Rate

1. The rates of filtration and of ingestion have been studied in Artemia of different ages feeding on pure cultures of plant cells of three different species, the concentrations of cells being varied over two orders of magnitude. 2. The animal is capable of regulating its rate of feeding in such a way that, as the cell concentration increases, the filtration rate maintains a constant maximum value while the ingestion rate increases. When the concentration reaches a value at which a constant maximum ingestion rate is attained, the filtration rate falls off. 3. In older animals the maximum ingestion rate is reached at a lower cell concentration than in younger animals. 4. The maximum filtration rate is independent of cell size. The maximum ingestion rate is inversely related to cell size, the total volume of cells ingested being the same for three species of plant cells. 5. The means whereby the animal maintains a maximum rate of total volume of cells ingested per unit time, irrespective of their size, has been investigated and is discussed.

Application of the Hydrodynamic-Structural Theory of Non-Newtonian Flow to Suspensions which Exhibit Moderate Shear Thickening with Particular Reference to “Dilatant” Vinyl Plastisols

1967 ◽  
Vol 40 (4) ◽  
pp. 1270-1280
Author(s):  
T. Gillespie
Keyword(s):  
Shear Rate ◽  
Vinyl Chloride ◽  
Shear Thickening ◽  
Structural Theory ◽  
Flow Data ◽  
Structural Viscosity ◽  
Newtonian Flow ◽  
Poly Vinyl Chloride ◽  
Maximum Value ◽  
Porous Poly

Abstract A general equation, derived in previous work, fits flow data for moderately shear thickening dispersions of poly (vinyl chloride) particles in an oil. The theory on which the equation is based predicts that the number of structural links in a disperse system can increase with increasing shear rate without shear thickening, provided n∞/n0&lt;2, where n∞ and n0 are the number of links per cubic centimeter at infinite shear rate and zero shear rate, respectively. This could account for the unexplained occurrence of “volume dilatancy” without “rheological dilatancy” previously reported in the literature. When n∞/n0&lt;2, viscosity increases with increasing shear rate to a maximum value and then the viscosity decreases with further increase in shear rate. This effect is explained as a competition between increase in the number of links with increasing shear rate and decrease in link lifetime with increasing shear rate. Aging of vinyl plastisols is examined and found to involve changes in both hydrodynamic and structural viscosity which can be explained by absorption of oil into the porous poly (vinyl chloride) particles.

The Changing Adult: An Integrated Approach

1984 ◽  
Vol 65 (3) ◽  
pp. 162-171
Author(s):  
V. Lois Erickson ◽  
Joshua Martin
Keyword(s):  
Adult Development ◽  
Integrated Approach ◽  
Structural Theory ◽  
Phase Theory

Although phase theory and structural theory both contribute to understanding adult development, each theory presents only a limited picture of the complexity of the changing adult. This article proposes an integration of the theories as an improved guide for practice.

Production and Electrochemical Characterization of Nickel Based Composite Coatings Containing Chromium Group Metal and Silicon Powders

2015 ◽  
Vol 228 ◽  
pp. 219-224
Author(s):  
Magdalena Popczyk ◽  
Julian Kubisztal ◽  
Bożena Łosiewicz ◽  
A. Budniok
Keyword(s):  
Steady State ◽  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Active Surface ◽  
Electrochemical Activity ◽  
Active Surface Area ◽  
Electrochemically Active ◽  
Electrochemically Active Surface

The Ni+Cr+Si, Ni+Mo+Si and Ni+W+Si composite coatings were obtained by electrodeposition of crystalline nickel from an electrolyte containing suspension of suitable metallic and non-metallic components (Cr, Mo, W and Si). These coatings were obtained galvanostatically at the current density of jdep = -0.100 A cm-2 and at the temperature of 338 K. Chemical composition of the coatings was determined by energy dispersive spectroscopy (EDS). The electrochemical activity of these electrocatalysts was studied in the process of hydrogen evolution reaction (HER) in 5 M KOH solution using steady-state polarization and electrochemical impedance spectroscopy (EIS) methods. The kinetic parameters of the HER on particular electrode materials were determined. It was found that Ni+Mo+Si composite coatings are characterized by enhanced electrochemical activity towards the HER as compared with Ni+W+Si and Ni+Cr+Si coatings due to the presence of Mo and increase in electrochemically active surface area.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1942 ◽  
Vol 25 (3) ◽  
pp. 411-429 ◽  
Author(s):  
Karl Sollner ◽  
Charles W. Carr ◽  
Irving Abrams
Keyword(s):  
Quantitative Measure ◽  
Exchange Capacity ◽  
Electrochemical Activity ◽  
Electrical Behavior ◽  
Exchange Method ◽  
Base Exchange ◽  
High Base ◽  
Different Origins ◽  
Theoretical Considerations ◽  
Exchange Properties

1. Theoretical considerations lead to the conclusion that dissociable acidic groups present to a varying extent in different collodion preparations determine the electrochemical behavior of membranes cast from these preparations. It is further reasoned that the base exchange capacity of the collodion surfaces is the true quantitative measure of the abundance of the dissociable groups. 2. The concept of base exchange capacity and the base exchange method are discussed. The conditions which allow a purposeful application of the latter are stated. 3. The base exchange properties of a number of fibrous collodion preparations of different origins and after various types of treatment, having widely varying electrochemical activities, are determined. 4. With the chemical (titration) and physical (electrometric) methods employed, no regular correlation can be found between electrochemical activity and base exchange. The base exchange capacity which is necessary to cause even great electrochemical activity of collodion is extremely small. 5. Measurable to high base exchange capacity always seems to be associated with good or high electrochemical activity; but base exchange capacity too low to be definitely measurable with the available methods may be found with collodion preparations of high as well as with preparations of low electrochemical activity. 6. The bearing of these results upon the problem of the spatial and electrical structure of the collodion membrane is indicated briefly.

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