Biological solutions, viscosities

If the g- and hyperfine anisotropies are known from analysis of a solid-state spectrum, the line-width parameters (1, and yt can be used to compute the rotational correlation time, tr, a useful measure of freedom of motion. Line widths in ESR spectra of nitroxide spin labels, for example, have been used to probe the motional freedom of biological macromolecules.14 Since tr is related to the molecular hydrodynamic volume, Ft, and the solution viscosity, r, by a relationship introduced by Debye 15... 

Almost every biological solution of low viscosity [but also viscous biopolymers like xanthane and dilute solutions of long-chain polymers, e.g., carbox-ymethyl-cellulose (CMC), polyacrylamide (PAA), polyacrylnitrile (PAN), etc.] displays not only viscous but also viscoelastic flow behavior. These liquids are capable of storing a part of the deformation energy elastically and reversibly. They evade mechanical stress by contracting like rubber bands. This behavior causes a secondary flow that often runs contrary to the flow produced by mass forces (e.g., the liquid climbs the shaft of a stirrer, the so-called Weissenberg effect ). 

Almost every biological solution of low viscosity [but also viscous biopolymers like xanthane and dilute solutions of long-chain polymers, e.g., carboxymethyl-cellulose (CMC), polyacrylamide (PAA), and polyacrylnitrile (PAN)] displays... 

Photochromic control of the polymer properties leads to potential applications involving the mechanical properties of a solution (viscosity, photogelation), polymer fiber (extensibility, photomuscle ), or membrane (porosity). More important, however, the ability to control the activity of enzymes and other biologically important macromolecules leads to potential applications in clinical phototherapy. 

Similarly Shalumon et al. also fabricated electrospun porous poly(lactic acid) (PLA) multiscale scaffolds and evaluated their physicochemical and biological properties in detail [53]. These multiscale scaffolds were developed through a bimodal fiber fabrication system. The three main solution properties, solution viscosity, conductivity, and surface tension, were determined to be the governing... 

Results on sorption efficiency of modified particles magnetite and iron to hemoglobin in model biological liquid (Table 17.3) showed, that maximal absorptive capacity manifested Fe-particles, modified by albumin (32.6 mg/g) and dextran (25.0 mg/g). These meanings are lower than those in physiological solution. This can be explained by decreasing of the sorption processes velocity due to increasing of solution viscosity. In fact,... 

Figure 4.11 Dependence of viscosity on shear rate at different temperatures for the biological solution of sodium salt of hyaluronan at two biopolymer concentrations (2.7 and Wmg/ml)...

Polymer degradation also results from bacterial attack. Bio-polymers are susceptible to biological attack resulting in the loss of solution viscosity from the destruction of the carbohydrate backbone, which can be rapid. For this reason, the polymer Wth usually contains a bactericide, such as formaldehyde, to control bacterial growth. At one time, it was thought that bacterial attack would not be a problem in petroleum reservoirs because the organisms could not be transported through the porous rock. Unfortunately, bacterial attack has been observed in at least two field tests. 24,25... 

Initially fermentation broth has to be characterised on the viscosity of the fluid. If the presence of the biomass or cells causes trouble, they have to be removed. Tire product is stored inside the cells, the cells must be ruptured and the product must be freed. Intracellular protein can easily be precipitated, settled or filtered. In fact the product in diluted broth may not be economical enough for efficient recovery. Enrichment of the product from the bioreactor effluents for increasing product concentration may reduce the cost of product recovery. There are several economical methods for pure product recovery, such as crystallisation of the product from the concentrated broth or liquid phase. Even small amounts of cellular proteins can be lyophilised or dried from crude solution of biological products such as hormone or enzymes.2,3... 

Chen R.H., Tsaih M.L. 1998. Effect of temperature on the intrinsic viscosity and conformation of chitosans in dilute HCl solution. International Journal of Biological Macromolecules 23,135-141. 

Harding, Stephen E. 1997b. The Viscosity Intrinsic of Biological Macromolecules. Progress in Measurement, Interpretation and Application to Structure in Dilute Solution. Progress in Biophysical Molecules Biological 68, 207-262. 

Monkos K. 1996. Viscosity of bovine serum albumin aqueous solutions as a function of temperature and concentration. International Journal of Biological Macromolecules 18, 61-68. 

Aqueous standard solutions are a source of certain difficulties In electrothermal atomic absorption spectrometry of trace metals In biological fluids The viscosities and surface tensions of aqueous standard solutions are substantially less than the viscosities and surface tensions of serum, blood and other proteln-contalnlng fluids These factors Introduce volumetric disparities In pipetting of standard solutions and body fluids, and also cause differences In penetration of these liquids Into porous graphite tubes or rods Preliminary treatment of porous graphite with xylene may help to minimize the differences of liquid penetration (53,67) A more satisfactory solution of this problem Is preparation of standards In aqueous solutions of metal-free dextran (50-60 g/llter), as first proposed by Pekarek et al ( ) for the standardization of serum chromium analyses This practice has been used successfully by the present author for standardization of analyses of serum nickel The standard solutions which are prepared In aqueous dextran resemble serum In regard to viscosity and surface tension Introduction of dextran-contalnlng standard solutions Is an Important contribution to electrothermal atomic absorption analysis of trace metals In body fluids. 

Finally, for biological molecules that are macromolecules, such as most proteins, Eq. (4.23) can also be used to relate the relative viscosity to the intrinsic viscosity of the solution and the macromolecule concentration ... 

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