Factors Influencing Dispersion

Arvidsson, M., Merlind, P. K., Hynen, A., and Bergman, B. (2001). Identification of factors influencing dispersion in split-plot experiments. Journal of Applied Statistics, 28, 269-283. 

Sample introduction into a carrier stream generates a dispersing sample zone and each of its fluid elements is carried along at a velocity corresponding to its respective position in the stream. Convective mass transport is then a consequence of the parabolic distribution of the linear velocities of every fluid element (Fig. 3.1, upper). Diffusive mass transport is dependent mainly on the concentration differences between neighbouring fluid elements and their diffusion coefficients. Although diffusive mass transport occurs in an isotropic fashion, only its radial component is relevant as a factor influencing dispersion. 

Effectiveness of Dispersants. Dispersant effectiveness is defined as the amount of oil that the dispersant puts into the water column compared to the amount of oil that remains on the surface. In the field, effectiveness is indicated by the formation of a white to coffee-coloured plume of dispersed oil in the water column which is visible from ships and aircraft. This is shown in Figure 1. Many factors influence dispersant effectiveness, including oil composition, sea energy, state of oil weathering, the type of dispersant used and the amount applied, temperature, and salinity of the water. The most important of these is the composition of the oil, followed closely by sea energy and the amount of dispersant applied. 

Cost-effective control of dust problems arising from bulk materials handling requires an initial examination of the overall handling operations. Factors influencing dust generation and dispersion must be understood in order to achieve a proper design. 

In addition, it was concluded that the liquid-phase diffusion coefficient is the major factor influencing the value of the mass-transfer coefficient per unit area. Inasmuch as agitators operate poorly in gas-liquid dispersions, it is impractical to induce turbulence by mechanical means that exceeds gravitational forces. They conclude, therefore, that heat- and mass-transfer coefficients per unit area in gas dispersions are almost completely unaffected by the mechanical power dissipated in the system. Consequently, the total mass-transfer rate in agitated gas-liquid contacting is changed almost entirely in accordance with the interfacial area—a function of the power input. 

AJ Hickey, NM Concessio, MM Van Oort, RM Platz. Factors influencing the dispersion of dry powders as aerosols. Pharm Tech 18 58-64, 82, 1994. 

The stability constant of complexes between /1-cyclodextrine and p-nitroaniline is higher than that of aniline because the resonace charge delocalization (and London dispersion interactions) is an important factor influencing the stability of these complexes62. This behaviour parallels that of corresponding phenols. 

Desai, S. J., Simonelli, A. R, Higuchi, W. I. (1965). Investigation of factors influencing release of solid drug dispersed in inert matrices. J. Pharm. Sci., 54, 1459-1464. 

Further factors influencing rheological characterization of filled polymers include changes in the degree of filler dispersion or inter-particle structure forma-... 

The natural factors cover dispersion conditions, which are influenced by climate and (regional and local) topography, and natural PM10 sources. 

The most important factor influencing the degree of steric stabilization is the thickness of the adsorbed layer in comparison with the size of the particles [292], The term protection has also been used because the steric stabilizing effect can cause significant salt tolerance on the part of a colloidal dispersion. Some suspensions have been prepared, using high concentrations of polyelectrolytes, that are quite stable in concentrated salt solutions [49]. 

Only about 20 cases are known where the syn or anti stereochemistry of cycloadducts has been reasonably well established. FO theory correctly predicts the result in 13 out of 16 cases studied.33 Other factors influencing the relative orientation, for example dispersion forces,34 have been invoked. 

When emulsion techniques are used for microsphere preparation, a number of processing factors influences the final structure of the microspheres, e.g., the choice of solvents and surfactants, phase viscosity, the ratio of the dispersed to the continuous phase, mixing speed, processing temperature, and time. Micro-... 

When the sample is introduced into the column, usually in the form of a zone of vapor, it takes the form of a narrow band. During transit through the column, various factors influence the width of this band, which is continuously increased due to various dispersion processes. These include diffusion of the solute, resistance to mass transfer between and within phases, and the influence of flow irregularities and pertur-bations.f A simple concept, the theoretical plate, carried over from distillation processes, has been used to compare columns and account for the degree of dispersion that influences bandwidth. A chromatographic column may be considered to consist of numerous theoretical plates where the distribution of sample components between the stationary and mobile phase occurs. Hence, a measure of the efficiency of a GC column may be obtained by calculating the number of theoretical plates, N, in the column from ... 

The dissolution rate and stability ofNMs over time is another crucial issue. Kittler et al. [32] have shown that the release of silver ions from a dispersion of silver nanoparticles in water, and consequently the toxicity towards human mesenchymal stem cells, increases significantly with time. In addition, the temperature and the nature of the biological medium (e.g., the presence of salts or biomolecules) are important factors influencing the dissolution of metal nanomaterials. Unfortunately, measurement of the dissolution... 

First, the concentration of Sr, Ba, and Ti in spruce bark is relatively higher than in needles, while the latter are enriched by Ni and Zn. Second, the concentration of Zn, Ba, Cu, and Cr is higher in blueberry roots, than in the aerial parts. Third, the effect of zonal and local factors is remarkable. For instance, the Sr content in the needles and in the barks of the spruce is appreciably lower than the average content of this trace metal in the shedding of the World s coniferous trees. This should be attributed to the effect of zonal factors influencing the aetive release of this metal. At the same time, the elevated content of Pb and Zn refleets the specificity of the bedrock since the dispersed sulfide mineralization is a eharaeteristic feature of this Karelia region. 

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