Osmotic ionic

Selunger, O. Z. and Nordrum, L. M. (1969) A regional study of some osmotic, ionic and age factors affecting the stability of cerebral lysosomes. J. Neurochem., 16, 1219-1229. 

In principle, simulation teclmiques can be used, and Monte Carlo simulations of the primitive model of electrolyte solutions have appeared since the 1960s. Results for the osmotic coefficients are given for comparison in table A2.4.4 together with results from the MSA, PY and HNC approaches. The primitive model is clearly deficient for values of r. close to the closest distance of approach of the ions. Many years ago, Gurney [H] noted that when two ions are close enough together for their solvation sheaths to overlap, some solvent molecules become freed from ionic attraction and are effectively returned to the bulk [12]. 

Total Salinity. The salinity control of oil-base mud is very important for stabilizing water-sensitive shales and clays. Depending upon the ionic concentration of the shale waters and of the mud water phase, an osmotic flow of pure water from the weaker salt concentration (in shale) to the stronger salt concentration (in mud) will occur. This may cause a dehydration of the shale and, consequently, affect its stabilization. 

When an ionic solution contains neutral molecules, their presence may be inferred from the osmotic and thermodynamic properties of the solution. In addition there are two important effects that disclose the presence of neutral molecules (1) in many cases the absorption spectrum for visible or ultraviolet light is different for a neutral molecule in solution and for the ions into which it dissociates (2) historically, it has been mainly the electrical conductivity of solutions that has been studied to elucidate the relation between weak and strong electrolytes. For each ionic solution the conductivity problem may be stated as follows in this solution is it true that at any moment every ion responds to the applied field as a free ion, or must we say that a certain fraction of the solute fails to respond to the field as free ions, either because it consists of neutral undissociated molecules, or for some other reason ... 

The effect of water salinity on crop growth is largely of osmotic nature. Osmotic pressure is related to the total salt concentration rather than the concentration of individual ionic elements. Salinity is commonly expressed as the electric conductivity of the irrigation water. Salt concentration can be determined by Total Dissolved Solids (TDS) or by Electrical Conductivity (EC). Under a water scarcity condition, salt tolerance of agricultural crops will be the primordial parameter when the quality of irrigation water is implicated for the integrated water resources management [10]. 

As has been reviewed extensively elsewhere (Wyn Jones Pollard, 1983), the evidence from many eukaryotic cells and eubacteria suggests common ionic and osmotic characteristics in the cytoplasm of cells, espe-cialy a high selectivity and similar ionic strength giving... 

Wyn Jones, R.G., Brady, C.J. Speirs, J. (1979). Ionic and osmotic relations in plant cells. In Recent Advances in the Biochemistry of Cereals, ed. D.L. Laidman and R.G. Wyn Jones, pp. 63-103. London Academic Press. 

Cells exposed to excessive levels of salinity have to acquire essential nutrients from a milieu with a preponderance of ions that are potentially toxic and non-essential. In this ionic environment the success of a plant cell will require intracellular tolerance and/or specific acquisition of nutrients essential for normal metabolic functioning. The cell is also exposed to an unfavourable water balance with an absolute requirement to maintain an internal osmotic regulation that favours uptake of water into the cell (Stavarek Rains, 1984 ). 

Weisbart, M. and Eeiner, D. (1974). Sublethal effect of DDT on osmotic and ionic regnlation by goldfish Carassius auratus. Canadian Journal of Zoology—Revue Canadienne De Zoologie 52, 739-744. 

Osmotic pressure effects can be substantial. For example, the waters of the oceans contain dissolved salts at a total ionic molarity of about 1.13 M. The osmotic pressure of ocean water can be calculated ... 

It remains to evaluate the quantity c — Cs. Since an explicit general solution is not to be had, we resort to the consideration of special cases. First, suppose that the external electrolyte concentration Cs is very small compared with the concentration ic /z- of the ge-gen ions belonging to the polymer and occurring in the gel. Then the second term in the left-hand member of Eq. (45) may be neglected in comparison with the first. Furthermore, the very large ionic osmotic pressures developed in such cases will cause V2m to be very small, thus justifying adoption of the dilute solution approximations (see, for example, Eq. 40) for the right-hand member. The equilibrium relation reduces in this case to... 

D. J. Wright and D. R. Newall, Nitrogen excretion, osmotic and ionic regulation in nematodes. The Organisation of Nematodes (N. A. Croll, ed.). Academic Press, London, UK. 1976. p. 163. 

Lactulose is the foundation of pharmacologic therapy to prevent and treat hepatic encephalopathy. It is a non-digestible synthetic disaccharide laxative that is hydrolyzed in the gut to an osmotically-active compound that draws water into the colon and stimulates defecation. Lactulose also lowers colonic pH, which favors the conversion of ammonia (NH3) to ammonium (NHf).48 Ammonium is ionic and cannot cross back into systemic circulation it is eliminated in the feces. Lactulose is usually initiated at 15 to 30 mL two to three times per day and titrated to a therapeutic goal of two to four soft bowel movements daily.20 49 50... 

It is important that injectable solutions that are to be given intravenously are isotonic, or nearly so. Because of osmotic pressure changes and the resultant exchange of ionic species across red blood cell membranes, nonisotonic solutions, particularly if given in quantities larger than 100 mL, can cause hemolysis or cre-nation of red blood cells (owing to hypotonic or hypertonic solutions, respectively). Dextrose, sodium chloride, or potassium chloride is commonly used to achieve isotonicity in a parenteral formula. 

Ionic strength Basic pH T —> swelling 4 Ionic strength T —> osmotic pressure inside... 

According to Flory s theory [20], the osmotic pressure due to ionic distribution n is given by the following equation,... 

Cell membranes or synthetic lipid vesicles with normal low permeability to water will, if reconstituted with AQP1, absorb water, swell and burst upon exposure to hypo-osmotic solutions. The water permeability of membranes containing AQP 1 can be about 100 times greater than that of membranes without aquaporins. The water permeability conferred by AQP1 (about 3 billion water molecules per subunit per second) is reversibly inhibited by Hg2+, exhibits low activation energy and is not accompanied by ionic currents or translocation of any other solutes, ions or protons. Thus, the movement of water through aquaporins is an example of facilitated diffusion, in this case driven by osmotic gradients. 

The ideality of the solvent in aqueous electrolyte solutions is commonly tabulated in terms of the osmotic coefficient 0 (e.g., Pitzer and Brewer, 1961, p. 321 Denbigh, 1971, p. 288), which assumes a value of unity in an ideal dilute solution under standard conditions. By analogy to a solution of a single salt, the water activity can be determined from the osmotic coefficient and the stoichiometric ionic strength Is according to,... 

Potts, W. T. W. and Parry, G. (1964). Osmotic and Ionic Regulation in Animals. Pergamon Press, Oxford. 

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