Equilibrium sediment volume

An extreme in sediment volume was usedt as a criterion for the effective cancellation of interparticle attraction by the continuous phase. Nylon-6,6 dispersions consisting of 1.0 g of solid in 10 ml of /2-propanol-thiodiethanol mixtures of various compositions were allowed to settle to sedimentation equilibrium. Listed here are the equilibrium sediment volumes, the volume/volume compositions, and the surface tensions of the media ... 

Sedimentation Coefficient Sedimentation Equilibrium Sediment Volume Self-Assembling Colloid... 

Bulk Properties of Suspensions Equilibrium Sediment Volume (or Height) and Redispersion... 

The sedimentation volume of a pharmaceutical suspension can be evaluated using simple, inexpensive, graduated, cylindrical graduates (100-1000 mL). It is defined as the ratio of the equilibrium volume of sediment, Vu, to the total volume of the suspension, V0. 

The colloidal stability of silica Suspensions in the present work was assessed by sediment volumes and from the optical coagulation rate constant. In the first method, 50 mg of silica was dispersed in 5 cm3 polymer solution (concentration 10-2 g cm 3) in a narrow tube and the sediment height found at equilibrium. Coagulation rates of the same systems were found by plotting reciprocal optical densities (500nm, 1cm cell) against time. When unstable dispersions were handled, the coagulation was followed in... 

Sediment volume and redispersion For sediment volume experiments a 50% w/v suspension was prepared using a 2% w/w of the polymer. 5g of the resulting suspension was added to 5 ml solutions of PEO to cover a wide concentration and the resulting suspension placed in stoppered cylinders and kept in constant temperature cabinets (25 1 C). The sediment height was followed with time for several weeks until equilibrium was reached. At this point the tubes were mechanically Inverted end-over-end and the number of revolutions required for redispersion was noted. 

Type f-Potential Relative settling rate Sediment volume in vials at equilibrium Drainage from vial Resuspendability... 

The particle size was determined using dynamic light scattering (also termed photon correlation spectroscopy PCS), using a Malvern PCS instrument. The equilibrium sediment and cream volumes were recorded using measuring cylinders at room temperature, and viscoelastic measurements were made using a Bohlin VOR rheometer. 

This chapter contains one of the more diverse assortments of topics of any chapter in the volume. In it we discuss the viscosity of polymer solutions, especially the intrinsic viscosity the diffusion and sedimentation behavior of polymers, including the equilibrium between the two and the analysis of polymers by gel permeation chromatography (GPC). At first glance these seem to be rather unrelated topics, but features they all share are a dependence on the spatial extension of the molecules in solution and applicability to molecular weight determination. 

The hydrodynamic properties of Ustilago cytochrome c were investigated by Thelander (86). He found the partial specific volume to be 0.721 ml/g and the molecular weight, by sedimentation equilibrium, to be 15,500. The latter value, although higher than that given by summation of the constituent amino acid residues (i.e., 11,877, see Table 3), indicates that the protein is monomeric. 

As shown in Fig. 3, CHEMGL considers 10 major well-mixed compartments air boundary layer, free troposphere, stratosphere, surface water, surface soil, vadose soil, sediment, ground water zone, plant foliage and plant route. In each compartment, several phases are included, for example, air, water and solids (organic matter, mineral matter). A volume fraction is used to express the ratio of the phase volume to the bulk compartment volume. Furthermore, each compartment is assumed to be a completely mixed box, which means all environmental properties and the chemical concentrations are uniform in a compartment. In addition, the environmental properties are assumed to not change with time. Other assumptions made in the model include continuous emissions to the compartments, equilibrium between different phases within each compartment and first-order irreversible loss rate within each compartment [38]. 

Sedimentation equilibrium Absolute requires only centrifuge measurements and partial specific volume of solute Time-consuming measurement and interpretation somewhat limited mol. wt. range 5... 

It is not widely appreciated that the major aspects of core histone interactions were well understood even before the development of the nucleosome model. Evidence for strong H2A H2B dimer interactions and an FI3 H4 tetramer was available in the early seventies (see Ref. [1], Chapter 2). By 1978, the rigorous sedimentation equilibrium studies from Moudrianakis laboratory had elucidated the thermodynamics of octamer formation [7]. What was missing, of course, was any structural information concerning these interactions. This was overcome by arduous X-ray diffraction studies, culminating in the elegantly detailed structures we have today [15,17,18], see also Flarp et al., this volume, p. 13. We now know how the core... 

Another technique consists of submitting the emulsion to centrifugation and determining the droplet volume fraction < / at the top (bottom) of the cream (sediment). The centrifugation typically takes several hours until the equilibrium volume fraction is achieved. After equilibration, if the droplets occupy a distance much less than that of the centrifuge lever arm, the spatial gradient in the acceleration can be neglected, and the osmotic pressure can be determined (see Fig. 4.1) ... 

Sorption has been commonly described as an equilibrium process, in which the pesticide molecules are rapidly and readily exchanged between the sediment and aqueous phases. In this approach ( ), the equilibrium water phase concentration, (expressed relative to suspension volume) is related to the sediment phase concentration, (expressed relative to dry weight sediment), through... 

You are interested in the well-being of Ampelisca abdita, living in a harbor whose sediments are contaminated with 4-nonylphenol. You remember that the lethal volume fraction of narcotic chemicals in membranes is about 0.01 L compound L I lipid. If the sediment contains 2% organic carbon by weight, and the amphipod is assumed to accumulate body burdens up to equilibrium with the sediments on which it lives, what sediment concentration of 4-nonylphenol should be deemed acceptable with respect to baseline toxicity Assume a log ,lipsw = 5.5 for 4-nonylphenol. Use Eq. 9-26c (alkylated and chlorinated benzenes ) for estimating Kioc. Compare your result with the findings of Fay et al. (2000), who observed a die-off of half the amphipods when they were exposed to about 0.16 g 4-nonylphenol - kg-1 sediment. 

Note that for the total (dissolved and particulate) concentration, Ct, the abrupt change of the solid-to-water-phase ratio, rsw (Eq. 9-15), at the sediment surface acts like a phase change. The numerical example given in Table 19.1 demonstrates that the transition from the open water column of a lake or the ocean to the sediments involves an increase of rsw by 5 to 6 orders of magnitude. Typically, in the open water, rs p is of order 10 3 kg m-3 while in the sediment column lies between 102 and 103 kg nr3. Thus, at equilibrium the total (dissolved and sorbed) concentration per unit bulk volume on either side of the interface for compounds with small to moderate solid-water distribution ratios (Ki <10 m3kg ) is approximatively given by (see Box 19.1, Eq. 4) ... 

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