scholarly journals THE KINETICS OF PENETRATION

1934 ◽  
Vol 17 (3) ◽  
pp. 445-467 ◽  
Author(s):  
W. J. V. Osterhout ◽  
S. E. Kamerling ◽  
W. M. Stanley
Keyword(s):  
Aqueous Solution ◽  
Aqueous Phase ◽  
Partition Coefficients ◽  
Living Cells ◽  
Organic Salts ◽  
Outward Diffusion ◽  
Factors Affecting ◽  
Unstirred Layers ◽  
Diffusion Constants ◽  
Aqueous Layer

Some of the factors affecting penetration in living cells may be advantageously studied in models in which the organic salts KG and NaG diffuse from an aqueous solution A, through a non-aqueous layer B (representing the protoplasmic surface) into an aqueous solution C (representing the sap and hence called artificial sap) where they react with CO2 to form KHCO3 and NaHCO3. Their relative proportions in C depend chiefly on the partition coefficients and on the diffusion constants in the non-aqueous layer. But the ratio is also affected by other variables, among which are the following: 1. Temperature, affecting diffusion constants and partition coefficients and altering the thickness of the unstirred layers by changing viscosity. 2. Viscosity (especially in the non-aqueous layers) which depends on temperature and the presence of solutes. 3. Rate of stirring, which affects the thickness of the unstirred layers and the transport of electrolyte in those that are stirred. 4. Shape and surface area of the non-aqueous layer. 5. Surface forces. 6. Reactions occurring at the outer surface such as loss of water by the electrolyte or its molecular association in the non-aqueous phase. The reverse processes will occur at the inner surface and here also combinations with acids or other substances in the "artificial sap" may occur. 7. Outward diffusion from the artificial sap. The outward movement of KHCO3 and NaHCO3 is small compared with the inward movement of KG and NaG when the concentrations are equal. This is because the partition coefficients3 of the bicarbonates are very low as compared with those of NaG and KG. Since CO2 and HCO3- diffuse into A and combine with KG and NaG the inward movement of potassium and sodium falls off in proportion as the concentration of KG and NaG is lessened. 8. Movement of water into the non-aqueous phase and into the artificial sap. This may have a higher temperature coefficient than the penetration of electrolytes. 9. Variation of the partition coefficients with concentration and pH. Many of these variables may occur in living cells. (It happens that the range of variation in the ratio of potassium to sodium in the models resembles that found in Valonia.)

scholarly journals THE KINETICS OF PENETRATION

1934 ◽  
Vol 17 (4) ◽  
pp. 507-516 ◽  
Author(s):  
W. J. V. Osterhout ◽  
S. E. Kamerling
Keyword(s):  
Aqueous Phase ◽  
Partition Coefficients ◽  
Organic Anion ◽  
External Solution ◽  
Living Cells ◽  
Approach To Equilibrium ◽  
Aqueous Layer ◽  
Pass Through ◽  
Kinetics Of ◽  
System Approaches

A model is described which throws light on the mechanism of accumulation. In the model used an external aqueous phase A is separated by a non-aqueous phase B (representing the protoplasm) from the artificial sap in C. A contains KOH and C contains HCl: they tend to mix by passing through the non-aqueous layer but much more KOH moves so that most of the KCl is formed in C, where the concentration of potassium becomes much greater than in A. This accumulation is only temporary for as the system approaches equilibrium the composition of A approaches identity with that of C, since all the substances present can pass through the non-aqueous layer. Such an approach to equilibrium may be compared to the death of the cell as the result of which accumulation disappears. During the earlier stages of the experiment potassium tends to go in as KOH and at the same time to go out as KCl. These opposing tendencies do not balance until the concentration of potassium inside becomes much greater than outside (hence potassium accumulates). The reason is that KCl, although its driving force be great, moves very slowly in B because its partition coefficient is low and in consequence its concentration gradient in B is small. This illustrates the importance of partition coefficients for penetration in models and in living cells. It also indicates that accumulation depends on the fact that permeability is greater for the ingoing compound of the accumulating substance than for the outgoing compound. Other things being equal, accumulation is increased by maintaining a low pH in C. Hence we may infer that anything which checks the production of acid in the living cell may be expected to check accumulation and growth. This model recalls the situation in Valonia and in most living cells where potassium accumulates as KCl, perhaps because it enters as KOH and forms KA in the sap (where A is an organic anion). In some plants potassium accumulates as KA but when HCl exists in the external solution it will tend to enter and displace the weaker acid HA (if this be carbonic it can readily escape): hence potassium may accumulate to a greater or less extent as KCl. Injury of the cell may produce a twofold effect, (1) increase of permeability, (2) lessened accumulation. The total amount of electrolyte taken up in a given time will be influenced by these factors and may be greater than normal in the injured cell or less, depending somewhat on the length of the interval of time chosen.

scholarly journals THE KINETICS OF PENETRATION

1933 ◽  
Vol 16 (3) ◽  
pp. 529-557 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Potassium Salt ◽  
Partition Coefficients ◽  
Living Cells ◽  
Constant Ratio ◽  
Ionic Activity ◽  
Activity Product ◽  
Exponential Decrease ◽  
Monomolecular Reactions ◽  
Aqueous Layer ◽  
Kinetics Of

An organic potassium salt, KG, passes from an aqueous phase, A, through a non-aqueous layer, B, into a watery solution, C. In C it reacts with CO2 to form KHCO3. The ionic activity product (K) (G) in C is thus kept at such a low level that KG continues to diffuse into C after the concentration of potassium becomes greater in C than in A. Hence potassium accumulates in C, the osmotic pressure rises, and water goes in. A steady state is eventually reached in which potassium and water enter C in a constant ratio. The rate of entrance of potassium (with no water penetrating into C) may fall off in a manner approximately exponential. But water enters and may produce an exponential decrease in concentration. This suggests that the kinetics may be treated like that of two consecutive monomolecular reactions. Calculations made on this basis agree very well with the observed values. The rate of penetration appears to be proportional to the concentration gradient of KG in the non-aqueous layer and in consequence depends upon the partition coefficients which determine this gradient. Exchange of ions (passing as such through the non-aqueous layer) does not seem to play an important rôle in the entrance of potassium. The kinetics of the model may be similar to that of living cells.

scholarly journals THE KINETICS OF PENETRATION

1932 ◽  
Vol 16 (1) ◽  
pp. 157-163 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Aqueous Solution ◽  
Steady State ◽  
Living Cell ◽  
External Solution ◽  
Living Cells ◽  
Similar Process ◽  
Alkaline Aqueous Solution ◽  
Solution Bathing ◽  
Aqueous Layer ◽  
Kinetics Of

In a model consisting of a non-aqueous layer (representing the protoplasm) placed between an inner, more acid, aqueous layer (representing the sap) and an outer, more alkaline, aqueous solution (representing the external solution bathing a living cell) the penetration of potassium creates an outwardly directed potential against which potassium continues to diffuse inward, thereby increasing the outward potential. This continues until the steady state is reached. The potassium sets up less potential in entering than in escaping and the net result is an outwardly directed potential. A similar process appears to take place in certain living cells.

scholarly journals BEHAVIOR OF WATER IN CERTAIN HETEROGENEOUS SYSTEMS

1940 ◽  
Vol 23 (3) ◽  
pp. 365-390 ◽  
Author(s):  
W. J. V. Osterhout ◽  
J. W. Murray
Keyword(s):  
Aqueous Solution ◽  
Vapor Pressure ◽  
Activity Coefficient ◽  
Aqueous Phase ◽  
Mole Fraction ◽  
Concentration Gradient ◽  
Trichloroacetic Acid ◽  
Living Cells ◽  
Circular Path ◽  
Ethylene Chloride

In various models designed to imitate living cells the surface of the protoplasm is represented by guaiacol which acts in some respects like certain protoplasmic surfaces. The behavior of water in these models presents interesting features and if these occur in vivo, as appears possible, they may help to explain some of the puzzling aspects of water relations in the living organism. When sufficient trichloroacetic acid is added to a two-phase system of water and guaiacol the two phases fuse into one. The effect of the acid is due to its attraction for water and for guaiacol. This is shown by the following facts. During the addition of the acid the mole fraction of water in the guaiacol phase increases but the activity of water in the guaiacol phase falls off. The activity coefficient of water may fall to less than one twelfth the value it had before acid was added. The behavior of guaiacol presents a similar picture. During the addition of acid the mole fraction of guaiacol in the aqueous phase increases but the activity of the guaiacol in the aqueous phase presumably decreases. Its activity coefficient calculated on this basis may fall to about one ninth of the value it had before the acid was added. Somewhat similar results are obtained when acetone is substituted for trichloroacetic acid or when ethanol is substituted for trichloroacetic acid and ethylene chloride for guaiacol. As trichloroacetic acid increases the mutual solubility of guaiacol and water we find that guaiacol saturated with water and having a high vapor pressure of water can take up water from an aqueous solution of trichloroacetic acid with a low vapor pressure of water: acid passes from the aqueous to the guaiacol phase, thus raising the vapor pressure of water in the aqueous phase and lowering it in the guaiacol phase. Diffusion experiments present some interesting features. When an aqueous solution, A, of trichloroacetic acid is separated by a layer of guaiacol, B, from distilled water, C, under certain conditions water moves from A to C. This depends on the fact that acid moves in the same direction and appears to carry water with it. Similar but less striking results were obtained with acetone diffusing through guaiacol and with ethanol diffusing through ethylene chloride. These phenomena differ from "anomalous osmosis" through solid membranes if it depends, as many suppose, on the diffusion of electrolytes through pores. We therefore suggest the term "anaphoresis" for the phenomena described here. Measurements of the mutual solubilities of water, guaiacol, and trichloroacetic acid and of water, guaiacol, and acetone are given and are discussed in relation to the diffusion experiments. To give a complete picture of the process of diffusion we need to know the activities and concentrations in all parts of the system. The difficulties of achieving this are obvious. The solubility relations are such that a concentration gradient of trichloroacetic acid in guaiacol produces a concentration gradient of water in the same direction, but the activity gradient of water is in the opposite direction. Since in certain respects guaiacol acts like some protoplasmic surfaces it seems possible that similar phenomena may occur in living cells. If so these results have an obvious bearing on the movement of water in the organism and on methods of studying permeability. It becomes necessary to know to what extent a substance entering or leaving the cell appears to carry water with it in the manner here indicated. In certain of the diffusion experiments the water takes a circular path, passing out of the dilute solution at one point and back into it (as vapor) at another. This circular path recalls the situation in the kidney where the water continually passes out of the blood into the glomerulus and tubule and then back into the blood from the tubule (where the solution is more concentrated). In both cases the circular path of the water is an essential feature.

scholarly journals KINETICS OF PENETRATION

1934 ◽  
Vol 17 (3) ◽  
pp. 469-480 ◽  
Author(s):  
W. J. V. Osterhout ◽  
S. E. Kamerling ◽  
W. M. Stanley
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Molecular Form ◽  
External Solution ◽  
Living Cells ◽  
Protoplasmic Surface ◽  
Weak Electrolytes ◽  
Ionic Mobilities ◽  
Aqueous Layer ◽  
Kinetics Of

In some living cells the order of penetration of certain cations corresponds to that of their mobilities in water. This has led to the idea that electrolytes pass chiefly as ions through the protoplasmic surface in which the order of ionic mobilities is supposed to correspond to that found in water. If this correspondence could be demonstrated it would not prove that electrolytes pass chiefly as ions through the protoplasmic surface for such a correspondence could exist if the movement were mostly in molecular form. This is clearly shown in the models here described. In these the protoplasmic surface is represented by a non-aqueous layer interposed between two aqueous phases, one representing the external solution, the other the cell sap. The order of penetration through the non-aqueous layer is Cs > Rb > K > Na > Li. This will be recognized as the order of ionic mobilities in water. Nevertheless the movement is mostly in molecular form in the nonaqueous layer (which is used in the model to represent the protoplasmic surface) since the salts are very weak electrolytes in this layer. The chief reason for this order of penetration lies in the fact that the partition coefficients exhibit the same order, that of cesium being greatest and that of lithium smallest. The partition coefficients largely control the rate of entrance since they determine the concentration gradient in the non-aqueous layer which in turn controls the process of penetration. The relative molecular mobilities (diffusion constants) in the non-aqueous layer do not differ greatly. The ionic mobilities are not known (except for K+ and Na+) but they are of negligible importance, since the movement in the non-aqueous layer is largely in molecular form. They may follow the same order as in water, in accordance with Walden's rule. Ammonium appears to enter faster than its partition coefficient would lead us to expect, which may be due to rapid penetration of NH3. This recalls the apparent rapid penetration of ammonium in living cells which has also been explained as due to the rapid penetration of NH3. Both observation and calculation indicate that the rate of penetration is not directly proportional to the partition coefficient but increases somewhat less rapidly. Many of these considerations doubtless apply to living cells.

Nitrification: an old process, a new concern

1971 ◽  
Vol 24 ◽  
Author(s):  
W. H. Verstraete
Keyword(s):  
Culture Medium ◽  
Nitrogen Sources ◽  
Living Cells ◽  
Factors Affecting ◽  
Inhibiting Effect ◽  
Proteose Peptone ◽  
Asparaginase Activity

Some  factors affecting the L-asparaginase activity of E.  aroideae were investigated. Increasing  concentrations of glucose in the culture medium had an inhibiting effect on  the production of L-asparaginase by this microorganism. Buffering of the  culture medium in order to stabilize the pH during growth resulted in a decrease  of the L-asparaginase activity. From the different nitrogen sources examined,  tryptone, proteose peptone nr 2 and nr 3 stimulated the L-asparaginase  production. Toluene treatment of the cells practically destroyed the  L-asparaginase. Acetone dried cells showed an L-asparaginase activity  comparable with the activity of living cells.

scholarly journals A rapid “on–off–on” mitochondria-targeted phosphorescent probe for selective and consecutive detection of Cu2+ and cysteine in live cells and zebrafish

RSC Advances ◽  
2021 ◽  
Vol 11 (13) ◽  
pp. 7610-7620 ◽  
Author(s):  
Peipei Deng ◽  
Yongyan Pei ◽  
Mengling Liu ◽  
Wenzhu Song ◽  
Mengru Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Living Cells ◽  
Live Cells ◽  
Mitochondria Targeting

An iridium(iii) complex-based mitochondria targeting phosphorescent probe for selectively detecting Cu2+ and Cys in aqueous solution, living cells and zebrafish has been developed.

Fabrication of monodisperse polypyrrole/SBA-15 composite for the selective removal of Cr(Ⅵ) from aqueous solutions

2021 ◽  
Author(s):  
Liang Wang ◽  
Peng Gao ◽  
Mengxin Liu ◽  
Ziqing Huang ◽  
Shixia Lan ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Adsorption Process ◽  
In Situ Polymerization ◽  
Selective Removal ◽  
Factors Affecting

Monodisperse polypyrrole/SBA-15 composite (PPy/SBA-15) was fabricated by in-situ polymerization and used for Cr(Ⅵ) adsorption from aqueous solution. PPy/SBA-15 was characterized by numerous approaches. Factors affecting the Cr(Ⅵ) adsorption process included...

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