Water physiologic solvent

A. The special chemical properties of water make it ideal as the main physiologic solvent for polar substances in the body. 

Living cells, among them the red blood cells, are surrounded by semipermeable membranes. The osmolarity of most cells is 0.30 osmol. For example, a 0.89% w/v NaCl solution, normally referred to as physiological saline solution, has an osmolarity of 0.30. Thus when a cell is put in physiological saline solution, the osmolarity on both sides of the membrane is the same and therefore no osmotic pressure is generated across the membrane. Such a solution is called isotonic. On the other hand, if a cell is put in water (pure solvent) or in a solution which has lower osmolarity than the cell, there will be a net flow of water into the cell driven by the osmotic pressure. Such a solution is called hypotonic. A cell placed in a hypotonic solution will swell and eventually may burst. If that happens to a red blood cell, the process is called hemolysis. In contrast, a solution with higher osmolarity than the cell is called a hypertonic solution. A cell suspended in a hypertonic solution will shrivel there is a net flow of water from the cell into the surroundings. When that happens to a red blood cell, the process is called crenation. 

Steckel et al. (105) used the ASES process to micronize several steroids and particles with the required size were obtained. No chemical decomposition was observed. The wettability of the active products was improved upon addition of a physiological surfactant to the initial solution. This is advantageous for suspensions of the drug particles in water, hydrophilic solvents, or propellants. Some modifications were brought to the conventional process. First, once the organic solution spraying has been done, the antisolvent injection is stopped and a sedimentation phase is allowed to take place this phase is claimed to increase the yield. Second, the removal of the residual... 

Solid. Isoelectric point 4.5, Soluble in water, physiological saline soln, 50% ale. Soluble in a pH 4.4 acetate buffer contg 20.5% sodium sulfate (different from LH which is inso] in this solvent). A 1 mg-% soln in saline may be kept at 60 for 30 min. In solns of pH 7-8 the activity is retained at 75 for 30 min. In 50% alcoholic soln the activity is destroyed at 60 within 15 min. 

Water-soluble Pc usually aggregate in physiological solvents even at low concentrations (dimerization constant 10 -10 M ) but they monomerize in the presence of detergents or organic solvents and in a lipophilic environment. This is of importance since only the monomeric species are photoactive [7]. 

Poly(vinyl acetate) latex paints are the first choice for interior use (149). Their abihty to protect and decorate is reinforced by several advantages belonging exclusively to latex paints they do not contain solvents so that physiological harm and fire ha2ards are eliminated they are odorless they are easy to apply with spray gun, roUer-coater, or bmsh and they dry rapidly. The paint can be thinned with water, and bmshes or coaters can be cleaned with soap and tepid water. The paint is usually dry in 20 minutes to two hours, and two coats may be applied the same day. 

The solubihty of hydrophobic substances in, or their absorbabiUty on suspended particles, on sediments, on biota, or on soil particles can be related to the solubihty of these substances in organic solvents. The solvent -octanol, CH2(CH2)yOH, is a kind of surrogate for many kinds of environmental and physiological organic substances and has become a reference phase for organic phase water partitioning of organic solutes. 

The concentration of salt in physiological systems is on the order of 150 mM, which corresponds to approximately 350 water molecules for each cation-anion pair. Eor this reason, investigations of salt effects in biological systems using detailed atomic models and molecular dynamic simulations become rapidly prohibitive, and mean-field treatments based on continuum electrostatics are advantageous. Such approximations, which were pioneered by Debye and Huckel [11], are valid at moderately low ionic concentration when core-core interactions between the mobile ions can be neglected. Briefly, the spatial density throughout the solvent is assumed to depend only on the local electrostatic poten-... 

Malonic acid ester synthesis is a classic but still one of the most important C—C bond-forming reactions, because it is widely applicable to various types of compounds and the reaction can be performed under mild conditions without special care to remove the trace amount of water and oxygen contained in the solvent. This reaction is especially useful in the synthesis of carboxylic acids. One important class of carboxylic acids is arylpropionates because optically active ones are known to have anti-inflammatory activity and other interesting physiological... 

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