Osmotic Pressure Of Solution Research Articles

Heat, Water, and Solution Transfer in Unsaturated Porous Media: I -- Theory Development and Transport Coefficient Evaluation

A detailed theory describing the simultaneous transfer of heat, water, and solute in unsaturated porous mediais developed. The theory includes three fully-coupledpartial differential equations. Heat, water, andsolute move in the presence of temperature, T; matricpressure head, Ψ m ; solution osmotic pressure head Ψ o ; and solute concentration C gradients. Thetheory can be applied to describe the mass and energyin radioactive waste repositories, food processing,underground energy storage sites, buried electriccables positions, waste disposal sites, and inagricultural soil. Several transport coefficients forheat, water, and solute are included in the theory. The coefficients are evaluated for a silty clay loamsoil to clarify their dependence on water content (θ),T, and C. The thermal vapor diffusivity D Tv first increased as θ increased to0.22 m3/m3 then decreased with furtherincreases in θ. D Tv was 3 orders of magnitudegreater than either isothermal vapor D mv orosmotic vapor D ov , diffusivities at θ of0.20~m3/m3, T of 50°C, and C of 0.001mol/kg. All of the liquid and vapor water transport coefficients increased with increasing T. D Tv decreased with increasing C to a greater extent thanD mv and D ov . The effective thermalconductivity decreased slightly with increasing C. Thesolute diffusion coefficient D d was 6 to 7orders of magnitude greater than the thermal soluteand salt sieving diffusion coefficients at θ of0.20~m3/m3, T of 50°C, and C of 0.001 mol/kg.

Effect of Viscosity on Membrane Fluxes in Cross-Flow Ultrafiltration

Abstract For practical applications of ultrafiltration (UF), an estimation of membrane fluxes under various operational conditions is very important. This study analyzed concentration polarization (CP) as a coupled transport problem with concentration-dependent solute viscosity. Besides the effects of variable viscosity, the model includes the effects of solute osmotic pressure, solute rejection at the membrane surface, and the axial pressure drop. This provides a fundamental understanding of the effects of various operating parameters on concentration polarization and transmembrane flux. A finite-difference solution of the transport equations is presented to model the concentration polarization in a thin-channel UF system. Simulation results for ultrafiltration of Dextran T-70 show that concentration-dependent solute viscosity adversely affects the transmembrane flux and needs to be carefully considered in modeling concentration polarization in membrane filtration.

Water release associated with specific binding of gal repressor.

Water release coupled to the association of gal repressor with DNA is measured from the sensitivity of the binding constant to the solution osmotic pressure, using neutral solutes that are typically excluded from polar protein and DNA surfaces. Differences in water release for binding of repressor to different sequences are linked with differences in specificity and binding energies. With sucrose, the specific binding of repressor to operator sequences is accompanied by the release of 130 water molecules. No water release is seen for the weak, non-specific binding of repressor to poly(dI-dC).(dI-dC). A difference in the release of six water molecules is seen even for the binding of gal repressor to two different operator sequences that differ in affinity by only a factor of two.

Effect of Solution Osmotic Pressure on Cell Fusion by Poly(Ethylene Glycol)

Effects of the osmotic pressure of culture medium on the membrane fusion of L929 cells in the monolayer state were investigated using polyethylene glycol) (PEG) with the molecular weight of 3,000 at various concentrations at phosphate buffer saline (PBS). Cell incubation for fusion was performed via three stages; (1) incubation before PEG treatment (preincubation), (2) incubation in the presence of PEG (PEG incubation), and (3) incubation after PEG treatment (postincubation). The PBS concentrations half that of a isotonic solution in the pre- and postincubation stages significantly accelerated the membrane fusion, whereas cell treatment at more hypotonic or hypertonic concentrations of PBS suppressed cell fusion. This result was explained in terms of cell swelling and shrinking induced by the osmotic pressure difference, because such cell morphological changes actually occurred when the PBS concentration was varied from the isotonicity. In contrast, almost no effect of osmotic pressure on cell fusion was observed if PEG was present in the culture medium at 40 w/w% concentration, regardless of the PBS concentration.

A Study on Concentration Polarization in Ultrafiltration

Abstract A finite-difference solution of coupled transport equations for momentum and solute continuity is presented to model the concentration polarization in a tubular ultrafiltration (UF) system. The model includes the effects of solute osmotic pressure and solute rejection at the membrane surface, axial pressure drop and resistance of the gel layer. This provides a fundamental understanding of the dynamics of various operating parameters on concentration polarization and transmembrane flux. Simulation results are presented for a wide range of operating variables to show their effects on local variation of solute concentration and transmembrane flux. The numerical results were also compared with previously published experimental data, which shows that a concentration polarization model based on constant membrane permeability (usually obtained from pure water flux data) grossly overestimates the flux behavior. If the effect of gel polarization is included, the model can predict the actual permeate flux ...

Physical parameters affecting electrofusion of yeasts: ζ-potential on the surface of yeast protoplasts and osmotic pressure of the solution

Yeast electrofusion is a relatively new technique which appears to offer some advantages over conventional chemical procedures. However, various parameters were found to affect fusion efficiency. The effects of both the osmotic pressure of the solution and the ζ-potential of yeast protoplasts on electrofusion were studied in detail in this study. The optimal osmotic pressure of the sorbitol solution for stability of protoplasts was about 0.9 Osm kg −1 because over 70% of protoplasts remained intact when an intensive pulse of 7 kV cm −1 of 100 μs duration was applied. On the other hand, the optimal pressure of sorbitol for the highest fusion efficiency was 0.6-0.7 Osm kg −1 when several pulses (5.5 kV cm −1, 25 μs, 1–10 charges) were applied. In the presence of divalent cations (especially Ca 2+ and Mg 2+) at a conductivity of 40–50 μs cm −1, a remarkable increase of fusion efficiency and frequent appearance of multimembrane-fused protoplasts were observed. Under the conditions established, fusion efficiency by electrofusion was 1:50-1:100 and approximately 10,000 times higher than that achieved by chemical methods such as the polyethylene glycol procedure. The acceleration of cell fusion by both divalent cations and change of conductivity was considered due to neutralization of anion residues of suger-protein complexes on the surface of the protoplasts because the ζ-potential of protoplasts was around 0 mV under the conditions used.

Pirenzepine block of ACH-induced mucus secretion in tracheal submucosal gland cells

Muscarinic stimulation of mucus secretion, as measured by the release of [ 3H]glycoprotein, was studied in explants from the tracheal epithelium of weanling swine. The mucus glycoprotein secretion was transient, ceasing within the first 10 min of a continuous exposure to 100 μM ACh. Increasing the solution's osmotic pressure did not alter basal mucus glycoprotein secretion. Mucus glycoprotein secretion was inhibited by 2–10 μM PZP, indicating that the M 3 muscarinic receptors mediate cholinergic stimulation of mucus production.

Triphosphate Nucleoside Metabolism in Dormant and Non-Dormant Apple Embryos

Apple embryo dormancy could be easily removed not only when fruit were maintained at cold temperature but also when naked embryos were placed on a high osmotic pressure solution (mannitol). Isolated axes and cotyledons of such non-dormant embryos exhibited the ability to increase their non-adenylic triphosphate pool (NTP) when they were incubated with adenosine. This ability did not appear in embryos excised at fruit harvest time when they were dormant or when a secondary dormancy had been induced. Thus, a peculiar regulation of the non-adenylic triphosphate pool appeared in non-dormant embryos as was previously demonstrated in non-dormant tubers and buds. Guanylic pool participation to this regulation and the importance of correlations between the different organs of apple embryo are discussed.

Interaction of plasma colloid osmotic pressure and joint fluid pressure across the endothelium-synovium layer: Significance of extravascular resistance

Fluid exchanges between blood and a synovial joint cavity across two membranes in series—synovial capillary wall (fenestrated) and synovial intima (modified connective tissue). The relation between transsynovial absorption of intraarticular Krebs solution (flow Q ̇ s ) and plasma colloid osmotic pressure π p was investigated in rabbit knees perfused at constant blood pressure. Intraarticular pressure P j was independently controlled. Linear relations between transsynovial flow and plasma colloid osmotic pressure established that transsynovial flow obeys the Starling hypothesis. However osmotic conductance, d Q ̇ s dπ p , increased 3.9 times when P j was raised from 6 cm H 2O or subatmospheric pressure to 18 cm H 2O—the “yield phenomenon.” Comparison of the effects of π p and capillary pressure revealed no major change in the osmotic reflection coefficient of the blood—joint barrier to albumin upon raising P j. The large increase in osmotic conductance was predicted quantitatively by a previous model (prediction 3.8 ×) based on increases in extravascular (intimal) conductance as a function of extravascular pressure. It is argued that capillary endothelium is not the sole significant hydraulic resistance in this pathway. In the terminology of Intaglietta and de Plomb (1973) synovial capillaries are functionally intermediate between “tubes” and “tunnels.”

The regulation of turgor pressure during sucrose mobilisation and salt accumulation by excised storage-root tissue of red beet

The changes in turgor pressure that accompany the mobilisation of sucrose and accumulation of salts by excised disks of storage-root tissue of red beet (Beta vulgaris L.) have been investigated. Disks were washed in solutions containing mannitol until all of their sucrose had disappeared and then were transferred to solutions containing 5 mol·m(-3) KCl+5 mol·m(-3) NaCl in addition to the mannitol. Changes in solute contents, osmotic pressure and turgor pressure (measured with a pressure probe) were followed. As sucrose disappeared from the tissue, reducing sugars were accumulated. For disks in 200 mol·m(-3) mannitol, the final reducing-sugar concentration equalled the initial sucrose concentration so there was no change in osmotic pressure or turgor pressure. At lower mannitol concentrations, there was a decrease in tissue osmotic pressure which was caused by a turgor-driven leakage of solutes. At concentrations of mannitol greater than 200 mol·m(-3), osmotic pressure and turgor pressure increased because reducing-sugar accumulation exceeded the initial sucrose concentration. When salts were provided they were absorbed by the tissue and reducing-sugar concentrations fell. This indicated that salts were replacing sugars in the vacuole and releasing them for metabolism. The changes in salf and sugar concentrations were not equal because there was an increase in osmotic pressure and turgor pressure. The amount of salt absorbed was not affected by the external mannitol concentration, indicating that turgor pressure did not affect this process. The implications of the results for the control of turgor pressure during the mobilisation of vacuolar sucrose are discussed.

The effect of high solute concentrations on nitrification rates in soil

A short term nitrification assay ( ammonium sulphate>sorbitol up to the maximum osmotic pressure studied (25 atm). With ammonium chloride, a pressure of 3.5 atm. was sufficient to cause a 90% inhibition of nitrification rate. The inhibition produced by mixtures of ammonium chloride and sorbitol, each mixture generating an osmotic pressure of 5 atm. in the assay, was also investigated. The results suggest that inhibition by Cl-ion is disproportionate to its contribution to the osmotic pressure of the soil solution. The recovery of the nitrification rate, following exposure to high osmotic pressure solutions, was also investigated. It was found that the recovery of the nitrification rate was only partial, with the extent of the recovery diminishing as the severity of the initial osmotic stress applied increased. These results suggest that both reversible and irreversible mechanisms are involved in the inhibition of nitrification.

The effect of metals and cyanide on fertilization in rainbow trout ( Salmo gairdneri)

This paper reports a study testing the effects of several heavy metals and cyanide on fertilization in rainbow trout. Two tests were carried out. 1. (1) The gametes were exposed independently for 40 min to a test chemical added into diluents. The ovum diluent (ID) was a NaCl solution (osmotic pressure: 250 mOsm kg −1), pH 9.0, Tris 20 mM, glycine 50 mM. The spermatozoa were diluted at 10 −1 and 10 −2 and the same diluent with K + added; they were immobile in this diluent (CD). Insemination was carried out after the gametes had been washed. 2. (2) Ova and spermatozoa were mixed together in ID containing one of the chemicals to be tested (insemination test). In test 1 in which gametes were exposed over an extended time, the chemicals were only very slightly toxic to ova compared to sperm. Iron became toxic for ova at a concentration of 0.073 mg 1 −1 and the toxic thresholds of the other products were higher than 1 mg 1 −1. The chemicals had a more marked toxic effect on sperm diluted at 10 −2 in the following decreasing order (in mg 1 −1): chromium 0.005, iron 0.005, cyanide 1, zinc 20. Insemination sometimes revealed lower thresholds of toxicity: chromium 0.005, iron 0.08, cyanide 0.001, mercury > 1. Copper had a favorable effect on fertilization. The tests, and particularly the insemination test, could be used to monitor the toxic effect of chemical on a stage of the life-cycle of fish which has been little studied up to now.

Electrochemical estimation of protoplast population

The protoplast concentration of Bacillus licheniformis FDO150 was estimated with a combined electrode composed of a platinum anode, a platinum cathode and a saturated calomel electrode (S.C.E.). The anode was adjusted at +0.4 V vs. S.C.E. When the electrode was inserted in a protoplast suspension, the anodic current increased slightly. Addition of dichlorophenol-indophenol (DCIP) caused considerable increase in the output current. When protoplasts (0.5 mg ml −1 wet cells) were suspended in a high osmotic solution, the rate of current increase was 0.8 μA min −1. On the other hand, no anodic current was obtained when protoplasts were suspended in a low osmotic pressure solution. However, in the case of whole cells of B. licheniformis, an increase of anodic current was observed in a low as well as a high osmotic solution. The difference of the rates of current increase obtained both in a high and low osmotic solutions was correlated with protoplast concentration in the range from 10 −2 to 10 −5 unit, where 1 unit is defined as the frequency of osmotically sensitive cells.

Interaction of Water Supply and N in Wheat

The purpose of this study was to investigate effects of N nutrition and water stress on stomatal behavior and CO(2) exchange rate in wheat (Triticum aestivum L. cv Olaf). Wheat plants were grown hydroponically with high (100 milligrams per liter) and low (10 milligrams per liter) N. When plants were 38 days old, a 24-day water stress cycle was begun. A gradual increase in nutrient solution osmotic pressure from 0.03 to 1.95 mega Pascals was achieved by incremental additions of PEG-6,000. Plants in both N treatments adjusted osmotically, although leaf water potential was consistently lower and relative water content greater for low N plants in the first half of the stress cycle. Leaf conductance of high N plants appeared greater than that of low N plants at high water potentials, but showed greater sensitivity to reductions in water potential as indicated by earlier stomatal closure during the stress cycle. The apparent greater stomatal sensitivity of high N plants was associated with a curvilinear relationship between leaf conductance and leaf water potential; low N plants exhibited more of a threshold response. Trends in [CO(2)](INT) throughout the stress cycle indicated nonstomatal effects of water stress on CO(2) exchange rate were greater in high N plants. Although estimates of [CO(2)](INT) were generally lower in high N plants, they were relatively insensitive to leaf water potential-induced changes in leaf conductance. In contrast, [CO(2)](INT) of low N plants dropped concomitantly with leaf conductance at low leaf water potentials. Oxygen response of CO(2) exchange rate for both treatments was affected less by reductions in water potential than was CO(2) exchange rate at 2.5% O(2), suggesting that CO(2) assimilation capacity of the leaves was affected more by reductions in leaf water potential than were processes related to photorespiration.

Temperature-induced lysis of chromaffin granules provides evidence against the two-pool hypothesis of catecholamine storage

The temperature-dependent release of core constituents from isolated chromaffin granules in isotonic sucrose has been a controversial and puzzling phenomenon that has been interpreted either as selective catecholamine efflux from different catecholamine pools or as temperature-dependent lysis. We have analysed the kinetics, temperature dependence and physical basis of this process. Our results demonstrate that, upon increasing the ambient temperature, chromaffin granules show a shift in their osmotic fragility to higher osmolarities, which is linearly dependent on temperature and leads to measurable lysis in 0.26 M buffered sucrose at temperatures above 12°C. It is possible to demonstrate both protein and dopamine β-hydroxylase release when lysis as a function of temperature is measured in 0.26 M buffered sucrose. Real time measurements of the lysis kinetics were recorded on casettes and analysed by a computer program for exponential decay kinetics. It is shown that the temperature-dependent lysis proceeds in two separate phases, the fast one of which is associated with temperature-dependent shift in the osmotic fragility curve. It has no characteristics of any exponential decay kinetics. The slow phase, when followed over several hours, leads to complete lysis of the granules in a sigmoidal time course at 30°C. We conclude from the absence of exponentially that there is no basis on which to assume the existence of different catecholamine pools. The fast phase of temperature-dependent lysis can be best explained as a simple temperature-dependent increase of the granule core solution's osmotic pressure, while the slow phase is probably caused by sucrose permeation into the granules. On the basis of these results, we warn against any efflux experiments measuring the temperature-dependent transmitter release from secretory vesicles with highly concentrated core solutions.

Configurational effect on the reflection coefficient for rigid solutes in capillary pores

Osmosis-driven flow through a leaky porous membrane is analyzed by combining the relevant equations describing spatial and orientational distributions of rigid non-spherical solute particles with the equations of fluid flow in a single capillary which is very narrow compared to its length. The capillary cross-section is either circular or rectangular and connects two bulk solution reservoirs having equal pressures but unequal concentrations of solute (osmotic pressure). The objective of this analysis is to study the effect of particle and pore shape on the reflection coefficient ( σ 0). The most significant result is that for solute particles of any eccentricity from one (sphere) to infinity (needle) in either the circular or rectangular pores, σ 0 ≈ (1− K) 2, where K is the pore-bulk equilibrium partition coefficient. A corollary of this result is that, comparing solute particles of equal volume, the more elongated a solute is the higher is its reflection coefficient; furthermore, for a given solute, the reflection coefficient is higher for pores that are more eccentric compared to a circle of equal area.

Direct measurement of water capacity of Beta vulgaris storage tissue sections using a displacement transducer and resulting values for cell membrane hydraulic conductivity

The water capacity of red beet (Beta vulgaris) storage tissue is measured as a function of water potential. These measurements use a linear displacement transducer to measure equilibrium tissue section thickness as a function of bathing solution osmotic pressure. The water potential equilibration time constant of the tissue as a function of water potential is also measured, using the applied force method. The water capacity and time constant data are combined to provide values for the hydraulic conductivity of the cell membrane.

Absorption and exchange of water across rumen epithelium

The osmotic pressure of solutions in the ventral sac of the rumen of the conscious cow was varied with Na Cl or mannitol. The mucosal blood flow measured by HTO clearance was minimal when the lumen contained an isotonic solution and rose threefold when the rumen was hypo- or hypertonic to plasma by 150 mosmol/kg. Thus osmotic gradients actoss the rumen epithelium stimulated mucosal blood flow. Using osmotic gradients small enough to avoid blood flow stimulation, the net water flow could be enhanced by butyrate, a chemical stimulator of blood flow. Thus water movement was partially limited by blood flow. This implied an appreciable change in osmotic pressure of the capillary blood toward that of the rumen contents. The relative importance of blood flow, membrane permeability, and solute uptake on water transport was assessed. The osmotic pressure in the rumen was stationary when the rumen solution was distinctly hypotonic to plasma. The absorbate in the absence of an osmotic gradient was thus hypertonic. The net uptake of solute increased rapidly when the solution in the lumen was hypertonic to plasma. This gave rise to a more rapid rate of change of osmotic pressure in the rumen under this condition.

Interpretation of osmotic pressure in solutions of one and two nondiffusible components

Osmotic pressure data from aqueous solutions of nondiffusible serum albumin (BSA), chondroitin sulfate (CHS), and dextran T110 (D110), taken singly and in binary combinations, were interpreted in terms of excluded volume. The principal solvent was phosphate-buffered saline, pH 7.2, at 23 degrees C. Osmotic pressures were measured with a membrane osmometer fitted with Amicon PM-10 membranes. Data from each solution were fit by stepwise regression with a three- or four-term polynomial in integral powers of total nondiffusible solute concentration in accordance with the general solution theory of McMillan and Mayer (1945, J. Chem. Phys. 13:276) as extended by Yamakawa (1971, Modern Theory of Polymer Solutions, Harper & Row, New York). The date display a high internal consistency, and the results correlate well with published molecular weights and exclusion data where available. Number average molecular weights calculated from the "first virial coefficients" are: BSA, 67,000 +/- 11%; D110, 76,000 +/- 11%, CHS, 39,000 +/- 6%. Excluded volumes (in cubic centimeters per molecule) calculated from the "second virial coefficients" are: BSA, 0.97 X 10(-18); D110, 3.04 X 10(-18); CHS, 14.3 X 10(-18); BSA-D110, 6.8 X 10(-18); BSA-CHS, 7.8 X 10(-18). Uncertainty is about 30%. An empirical model for interpretation of calculated excluded volumes is proposed. It appears that CHS has the "largest" exclusion effect of the three molecules.

Production of energy from concentrated brines by pressure-retarded osmosis : II. Experimental results and projected energy costs

The osmotic region between ordinary osmosis and osmotic equilibrium has been examined up to osmotic pressure differences of 500 atm and hydraulic pressure differences of 90 atm. The process, called Pressure-Retarded Osmosis (PRO), appears appropriate for energy production if a high osmotic pressure solution, the permeate-receiver, and a low osmotic pressure solution, the permeate-donor, are simultaneously available, as at the Dead Sea or Great Salt Lake. The experimental work was carried out in short duration tests with “Minipermeators” containing asymmetric Du Pont Permasep B-10 hollow fibers (external skin) made at present for sea water desalination. Sodium chloride and magnesium chloride solutions were used as permeate-receivers and gave similar results at similar osmotic pressures. Dead Sea brine was extensively tested at various dilutions as a permeate-receiver. Filtered and distilled water, and solutions made from it were used as permeate-donors. p]The results could be generally correlated by assuming diffusional transport through both the skin and the porous substructure. For low osmotic pressures on the permeatedonor side (inside) of the fibers, asymmetry was as advantageous in PRO as in RO. p]From the data obtained, it was estimated that energy could be produced for about 0.07 dollars per kilowatt hour in a PRO power plant utilizing Dead Sea brine and water as permeate-receiver and donor, respectively.