Forces osmotic

The quantity of water is two to three times the weight of the hides. The salt from the cure dissolves in the water and the reverse of the curing takes place. The water is drawn into the hides by osmotic forces. The concentration of the salt solution is about 3-5 g/lOO mL. At this concentration some of the soluble proteins disperse. The soak water removes the salt, some proteins, some loose fat, blood, dirt, and manure. 

Electrostatic Repulsive Forces. As the distance between two approaching particles decreases, their electrical double layers begin to overlap. As a first approximation, the potential energy of the two overlapping double layers is additive, which is a repulsive term since the process increases total energy. Electrostatic repulsion can also be considered as an osmotic force, due to the compression of ions between particles and the tendency of water to flow in to counteract the increased ion concentration. 

If the dmg itself cannot provide the osmotic driving force, then a push-puU design of the osmotic system is available with other salts as the osmotic force. This system is schematized in Eigure 5. The outer surface is a rigid semi-permeable membrane that surrounds the osmotic layer of salt (propeUant). Inside the osmotic layer is a compressible membrane that surrounds the dmg solution. As the salt layer sweUs with water, the inner membrane compresses and pushes out the dmg solution. 

For the chain (homogenous) consisting of one con-former, osmotic forces are similar to the ones stretching the molecule by the ends. Then, labor of the distance being estimated at constant temperature T , one can estimate 5ch value from the condition = F AR = T ASch)- If a more accurate estimation of the distance change valRe between the ends is required, one may calculate the R value, taking into account the distribution function of the distances between the ends R. The value of the mean-square distances between the ends of the chain, being stretched by forces, applied to the ends equals [14] ... 

A general case of heat transfer under the conditions of combined action of electro-osmotic forces and imposed pressure gradient was considered by Chakra-borty (2006). The analysis showed that in this case the Nusselt number depends not only on parameters z and S, but also on an additional dimensionless group, which is a measure of the relative significance of the pressure gradient and osmotic forces. 

Solutes must also enter to provide the metabolites for cell wall synthesis and to maintain the osmotic forces necessary to drive enlargement. A restricted supply of water might induce changes in any of these processes. 

We may point out parenthetically that it is usually customary to attribute the expansion to electrostatic repulsions between the net (positive) charges on the polymer molecule which are uncompensated due to loss of counter-ions to the outer solution. It may be shown that the osmotic force owing to the excess of mobile ions within the molecule must be equal to the force of electrostatic repulsion when the molecule is in equilibrium with its surroundings. Hence either point of view is equally satisfactory in principle. The two are, of course, mutually related no net charge would develop in the molecule were it not for the mobile counter-ions, and no excess of mobile ions would be retained to exert an osmotic pressure if it were not for the charges on them. 

Osmotic pressure results from the difference in concentration between the boimd but mobile coimterions within the polyion and the free counterions outside it. The concentration of counterions is greater within the polyion so that solvent molecules tend to enter this region. The osmotic force is proportional to the difference n—n where n equals the total number of counterions or the number of ionizable groups on the polyion. 

Ion binding reduces the repulsive forces between the charged groups on the polyanion but, unless the counterions are site-bound, the repulsive osmotic forces are not affected. At full neutralization the coulombic forces along the polymer chain become zero. However, the polymer does not contract, because the osmotic forces remain unless, of course, all the cations become site-bound. (Of course, in the case of a free weak acid the concentration of mobile hydrogen ions is very small and the polymer adopts a compact form.)... 

Figure 6.22 The efTect of water on a poor example of a dental silicate cement. An osmotic force causes blistering and disintegration (Wilson Batchelor, 1967a).

Soluble macromolecules permeate the endothelial barrier more readily than particulate macromolecules. The rate of movement of fluid across the endothelium appears to be directly related to the difference between the hydrostatic and osmotic forces. 

Molecular attraction (surface tension, adsorptive, diffusive, and osmotic forces)... 

Explain how hydrostatic forces and osmotic forces regulate the bulk flow of fluid across the capillary wall... 

Plasma colloid osmotic pressure is generated by proteins in the plasma that cannot cross the capillary wall. These proteins exert an osmotic force, pulling fluid into the capillary. In fact, the plasma colloid osmotic pressure, which is about 28 mmHg, is the only force holding fluid within the capillaries. Interstitial fluid colloid osmotic pressure is generated by the small amount of plasma proteins that leaks into the interstitial space. Because these proteins... 

Figure 15.7 Starling principle a summary of forces determining the bulk flow of fluid across the wall of a capillary. Hydrostatic forces include capillary pressure (Pc) and interstitial fluid pressure (PJ. Capillary pressure pushes fluid out of the capillary. Interstitial fluid pressure is negative and acts as a suction pulling fluid out of the capillary. Osmotic forces include plasma colloid osmotic pressure (np) and interstitial fluid colloid osmotic pressure (n,). These forces are caused by proteins that pull fluid toward them. The sum of these four forces results in net filtration of fluid at the arteriolar end of the capillary (where Pc is high) and net reabsorption of fluid at the venular end of the capillary (where Pc is low).

Albumin is the most abundant (about 55%) of the plasma proteins. An important function of albumin is to bind with various molecules in the blood and serve as a carrier protein, transporting these substances throughout the circulation. Substances that bind with albumin include hormones amino acids fatty acids bile salts and vitamins. Albumin also serves as an osmotic regulator. Because capillary walls are impermeable to plasma proteins, these molecules exert a powerful osmotic force on water in the blood. In fact, the plasma colloid osmotic pressure exerted by plasma proteins is the only force that retains water within the vascular compartment and therefore maintains blood volume (see Chapter 15). Albumin is synthesized in the liver. 

Plasma colloid osmotic pressure nGC) is generated by the plasma proteins. These proteins exert an osmotic force on the fluid, which opposes filtration... 

The reptation model for polymer diffusion would predict that the thickness of the gel phase reflects the dynamics of disentanglement. The important factors here are chain length, solvent quality and temperature since they affect the dimensions of the polymer coils in the gel phase. The precursor phase, on the other hand, depends upon solvency and temperature only through the osmotic force it can generate in the system and the viscoelastic response of the system in the region of the front. These factors should be independent of the PMMA molecular weight. 

The use of sub-micrometer channels and detection by confocal fluorescence microscopy is an interesting alternative, which should allow precise control of the movement of single molecules by electrokinetic or electro-osmotic forces . ... 

The base resin contains a styrene-divinylbenzene polymer, DVB. If styrene alone were used, the long chains it formed would disperse in organic solvents. The divinylbenzene provides cross-linking between the chains. When the cross-linked structure is immersed in an organic solvent, dispersion takes place only to the point at which the osmotic force of solvation is balanced by the restraining force of the stretched polymer structure. 

Coulombic, van der Waals, entropic and osmotic forces are coupled in a nontrivial way and give rise to important charge regulation in polyelectrolyte systems. The salt concentration is also an important factor to define the structure and thermodynamic properties of polyelectrolyte solutions. In weak polyelectrolytes the ionization equilibrium is also coupled to these interactions and thus the pKof ionizable groups depends on the organization of the interface and differs from that for the isolated molecule. 

At the boundary between the inner and outer stripes of the outer medulla, the proximal tubule empties into the thin descending limb of Henle s loop. Water is extracted from the descending limb of this loop by osmotic forces found in the hypertonic medullary interstitium. As in the proximal tubule, impermeant luminal solutes such as mannitol oppose this water extraction. The thin ascending limb is relatively water-impermeable. 

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