Conditions, separation upon

HUMIC Acid. Humic acid did not contribute detectable impurities to the eluates of blank parfait columns. This result was apparently due to the insolubility of humate in the organic solvents used to elute the Teflon and ion-exchange beds and the inability of the humate to volatilize in the GC. Humic acid did, however, distribute itself throughout the parfait column, as indicated by the observation of color entering the column effluent, F7. When 16 mg of humate in 8 L of synthetic hard water was passed through a parfait column having the Teflon bed divided into three sequential 50-mL beds, 8.9 , 5.0 , and 2.9 of the total humate were found in the aqueous phases that separated upon elution of these beds, as indicated by absorbance at 200 nm. The column effluent from this experiment contained 5.1 of the humate applied. The majority of the humate applied was found as color adsorbed to PTFE, and it did not elute into methylene chloride. Conditions to elute it from PTFE were not explored. 

Separation upon conditions This separation strategy entails that the system under Condition 1 exhibits property (-I-P), and under Condition 2 it exhibits property (-P). An excellent example is Transitions lenses with a light-sensitive photochromic coating. The lenses are light or dark depending on the amount of UV radiation present (Exhibit 24.3). 

Miss Frush and IsbelF used crystalline heptaacetyl-a-neolactosyl chloride in the Konigs-Knorr reaction under conditions identical with those described for pentaacetyl-a-D-(a)-guloheptosyl bromide, with the exception that the reaction time was increased to seventy-two hours. Acid and alkaline hydrolysis of the reaction solution showed that only about 70% of the original sugar was present, and that this was almost completely in the form of the orthoester. By extraction of the silver residues with chloroform, a halogen-free sirup was obtained, from which short rectangular crystals separated upon addition of methyl alcohol. This substance was methyl /3-neolactoside heptaacetate, which exhibited the expected normal behavior. 

Coacervation, as defined by International Union of Pure and Applied Chemistry (lUPAC), is the separation into two liquid phases in colloidal systems. The phase more concentrated in colloid component is the coacervate, and the other phase is the equilibrium solution. It is to be distinguished from precipitation which is observed in the form of coagulum or floes in colloidally unstable systems. The term coacervation was coined in 1929 by Bungenberg de Jong and Kruyt to describe a process in which aqueous colloid solutions separate, upon alteration of the thermodynamic condition of state, into two immiscible liquid layers, one rich in colloid, i.e., the coacervate, and the other containing little colloid. ... 

The critical point obtained from the Flory-Huggins equation can well explain the critical condition for phase separation upon temperature drop. This critical point is... 

For the PIM to be cast successfully, the components must be miscible with each other in each specific formulation. Poorly miscible formulations will phase-separate upon drying and suffer from poor extractive performance. Poorly designed formulations offen result in brittle and inhomogeneous membranes. PIM components may be miscible only in limited, specific formulations, or only in the presence of particular modifiers or plasticizers. Similarly, the formulation of a PIM composition must be appropriate for its intended application - for example, CTA can undergo hydrolysis in strongly acidic or alkaline solutions and is therefore an inappropriate base polymer for these conditions. This means that PIM development typically includes a significant period of optimizing the composition of the PIM formulation. 

The dry, ignited oxide, Sb203, is only slightly soluble in HNO3 the moist, freshly precipitated oxide, however, dissolves readily in the dilute or concentrated acid, warm or cold. Under certain conditions of concentration a portion of the antimony separates upon standing as a white crystalline precipitate. 

The range of systems that have been studied by force field methods is extremely varied. Some force fields liave been developed to study just one atomic or molecular sp>ecies under a wider range of conditions. For example, the chlorine model of Rodger, Stone and TUdesley [Rodger et al 1988] can be used to study the solid, liquid and gaseous phases. This is an anisotropic site model, in which the interaction between a pair of sites on two molecules dep>ends not only upon the separation between the sites (as in an isotropic model such as the Lennard-Jones model) but also upon the orientation of the site-site vector with resp>ect to the bond vectors of the two molecules. The model includes an electrostatic component which contciins dipwle-dipole, dipole-quadrupole and quadrupole-quadrupole terms, and the van der Waals contribution is modelled using a Buckingham-like function. 

This substance (dA, I A) contains a free carboxyl group and is treated in warm acetone solution with an equimolecular quantity of the optically active base brucine (IB) upon cooling, the brucine salt (dA, IB) separates out first in a moderately pure condition, whilst the brucine salt (lA, IB) remains in solution ... 

Biomolecule Separations. Advances in chemical separation techniques such as capillary zone electrophoresis (cze) and sedimentation field flow fractionation (sfff) allow for the isolation of nanogram quantities of amino acids and proteins, as weU as the characterization of large biomolecules (63—68) (see Biopolymers, analytical techniques). The two aforementioned techniques, as weU as chromatography and centrifugation, ate all based upon the differential migration of materials. Trends in the area of separations are toward the manipulation of smaller sample volumes, more rapid purification and analysis of materials, higher resolution of complex mixtures, milder conditions, and higher recovery (69). 

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