Dilute-solution effect

If water movement in the membrane is also to be considered, then one way to do this is to again use the Nernst—Planck equation. Because water has a zero valence, eq 29 reduces to Pick s law, eq 17. However, it is also well documented that, as the protons move across the membrane, they induce a flow of water in the same direction. Technically, this electroosmotic flow is a result of the proton—water interaction and is not a dilute solution effect, since the membrane is taken to be the solvent. As shown in the next section, the electroosmotic flux is proportional to the current density and can be added to the diffusive flux to get the overall flux of water... 

Volume from which a macromolecule in a dilute solution effectively excludes all other macromolecules. 

The effect of ions on denaturation temperatures is well-studied for dilute solutions. Effects related to the Hoffineister series are apparent. Unfortunately, no systematic studies of ions on protein glass transitions are available, and it cannot be assumed that these will have a neghgible effect on the materials properties during extrusion. 

Khouryieh H. A., Herald T. J., Aramouni R, Alavi S. 2007. Intrinsic viscosity and viscoelastic properties of xanthan/guar mixtures in dilute solutions Effect of salt concentration on the polymer interactions. Fond Res. Int. 40, 883-893. 

Figure 9-2 includes the spinodals calculated by the hybrid theory. If we compare the curves for b — 0.5 with those for 6 = 00, we see thtit the new theory substantially improves agreement with experiment, especially at low and P. This improvement owes much to the P dependence of Q, i.e., the fact that the dilute regime persists up to a higher concentration as P is lowered. In what follows, all that is associated with this dependence is referred to as the dilute-solution effect. 

Nies et al. [27] modified eq 2.5 of Koningsveld and Kleintjens by adding a term representing the dilute-solution effect and moreover by allowing a to vary with T and P. Their proposed expression for g was... 

The first and second rows in eq 2.19 represent the concentrated- and dilute-solution effects, respectively. Thus we see that J depends on P in the concentrated regime, as x does. This is expected, because F is related to x by... 

There remain three parameters (xo, a and c) which had to be fitted in the same way as in the first case with Eg = 0. As one can see in Fig. 3, the nearly linear part of the cloud-point curve can be described in a satisfactory manner only if chemical polydispersity is taken properly into account. The prediction of the threshold temperature is not quite satisfactorily made by the dilute solution effect not considered here. The agreement between calculation and experiment remains unsatisfactory in the region above the critical concentration. However, if the simplicity of the assumption introduced above into the G -model and We(rB, Yg) is allowed for, we may not except a description correct for the shoulder appearing in the experimental cloud-point curve. 

Table 6 Heats of neutralisation (excluding dilution/solution effects)...

Horn, A. F. and Merrill, E. W., Extensional flow-induced chain scission of macromolecules in dilute solution Effect of solvent power in a mixed solvent system, Polym. Commun. 25 172 (1987). 

Reagent A is particularly useful for the treatment of the lower aliphatic aldehydes and ketones which are soluble in water cf. acetaldehyde, p. 342 acetone, p. 346). The Recent is a very dilute solution of the dinitrophenylhydrazine, and therefore is used more to detect the presence of a carbonyl group in a compound than to isolate sufficient of the hydrazone for effective recrystallisation and melting-point determination. 

The state of aqueous solutions of nitric acid In strongly acidic solutions water is a weaker base than its behaviour in dilute solutions would predict, for it is almost unprotonated in concentrated nitric acid, and only partially protonated in concentrated sulphuric acid. The addition of water to nitric acid affects the equilibrium leading to the formation of the nitronium and nitrate ions ( 2.2.1). The intensity of the peak in the Raman spectrum associated with the nitronium ion decreases with the progressive addition of water, and the peak is absent from the spectrum of solutions containing more than about 5% of water a similar effect has been observed in the infra-red spectrum. ... 

The continued effectiveness of the nitronium ion in relatively dilute solutions has been indicated by comparing the dependence of the rates on the concentration of sulphuric acid, with the acidity-dependence of the ionisation of model compounds. The (formerly or Cq) acidity... 

Auto-association of A-4-thiazoline-2-thione and 4-alkyl derivatives has been deduced from infrared spectra of diluted solutions in carbon tetrachloride (58. 77). Results are interpretated (77) in terms of an equilibrium between monomer and cyclic dimer. The association constants are strongly dependent on the electronic and steric effects of the alkyl substituents in the 4- and 5-positions, respectively. This behavior is well shown if one compares the results for the unsubstituted compound (K - 1200 M" ,). 4-methyl-A-4-thiazoline-2-thione K = 2200 M ). and 5-methyl-4-r-butyl-A-4-thiazoline-2-thione K=120 M ) (58). 

Hydrogen bonding to a carbonyl group causes a shift to lower frequency of 40 to 60 cm k Acids, amides, enolized /3-keto carbonyl systems, and o-hydroxyphenol and o-aminophenyl carbonyl compounds show this effect. All carbonyl compounds tend to give slightly lower values for the carbonyl stretching frequency in the solid state compared with the value for dilute solutions. 

Dilute solutions of nominally 0.001 M NaOH and HGl are used to demonstrate the effect of an indicator s color transition range on titration error. Potentiometric titration curves are measured, and the indicator s color transition range is noted. Titration errors are calculated using the volume of titrant needed to effect the first color change and for a complete color change. 

Criticize or defend the following proposition In dilute solutions, branching affects viscosity only inasmuch as the branched molecule has a more compact shape. At higher concentrations, the effect of branching is closer to a bulk effect. 

When B = 0, the solution behaves ideally, at least through second-order effects. This means that deviations from ideality might be observed at still higher concentrations, but that the van t Hoff equation applies at least in dilute solutions for systems with B = 0. 

In the derivation of both Eqs. (9.4) and (9.9), the disturbance of the flow streamlines is assumed to be produced by a single particle. This is the origin of the limitation to dilute solutions in the Einstein theory, where the net effect of an array of spheres is treated as the sum of the individual nonoverlapping disturbances. When more than one sphere is involved, the same limitation applies to Stokes law also. In both cases contributions from the walls of the container are also assumed to be absent. 

We assume that the observed interference is the cumulative effect of the contributions of the individual polymer molecules and that solute-solute interactions do not enter the picture. This effectively limits the model to dilute solutions. This restriction is not particularly troublesome, since our development of the Rayleigh theory also assumes dilute solutions. 

Hydrogen fluoride or compounds that can produce it and fluorine-containing oxidizers should be handled with adequate safety equipment and extreme care by weU-trained personnel. Often the effect of skin exposure is not immediately evident, especially when dilute solutions are handled. Pain may develop several hours later. 

Mild exposure to HF via inhalation can irritate the nose, throat, and respiratory system. The onset of symptoms may be delayed for several hours. Severe exposure via inhalation can cause nose and throat bums, lung inflammation, and pulmonary edema, and can also result in other systemic effects including hypocalcemia (depletion of body calcium levels), which if not promptly treated can be fatal. Permissible air concentrations are (42) OSHA PEL, 3 ppm (2.0 mg/m ) as E OSHA STEL, 6 ppm (5.2 mg/m ) as E and ACGIH TLV, 3 ppm (2.6 mg/m ) as E. Ingestion can cause severe mouth, throat, and stomach bums, and maybe fatal. Hypocalcemia is possible even if exposure consists of small amounts or dilute solutions of HE. 

Both Hquid HE and the vapor can cause severe skin bums which may not be immediately painful or visible. HE can penetrate skin and attack underlying tissues, and large (over 160 cm ) bums may cause hypocalcemia and other systemic effects which may be fatal. Even very dilute solutions may cause bums. Both Hquid and vapor can cause irritation to the eyes, corneal bums, and conjunctivitis. 

The ultimate fate of the oxygen-centered radicals generated from alkyl hydroperoxides depends on the decomposition environment. In vinyl monomers, hydroperoxides can be used as efficient sources of free radicals because vinyl monomers generally are efficient radical scavengers which effectively suppress induced decomposition. When induced decomposition occurs, the hydroperoxide is decomposed with no net increase of radicals in the system (see eqs. 8, 9, and 10). Hydroperoxides usually are not effective free-radical initiators since radical-induced decompositions significantly decrease the efficiency of radical generation. Thermal decomposition-rate studies in dilute solutions show that alkyl hydroperoxides have 10-h HLTs of 133—172°C. 

Generally for dilute solutions (<1 2% of feed), unless molecular sieving effect also present. 

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