Single particle size sphere

Except for support effects, structure sensitivity has usually appeared in one of two aspects, variation of rate with svirface crystal face or with particle size. In ICC 1 Gwathmey reported in one of the first experiments with single crystal faces that different faces machined fi om Ni single crystal spheres catalyzed the hydrogenation of ethylene at different rates (ICC 1 paper 5). 

Figure 4. SEC calibration curve for silica sol separation (hard sphere particles, single pore size column) (1), Column PSM-1500 (8.9 fim), 30 X 0.78 cm mobile phase O.IU Na.HPO -NaH.PO, pH 8.0...

Calibration of these single-particle counters is usually carried out using monodisperse polystyrene latex or polyvinyl latex spheres, which are available in sizes from 0.1 to 3 /im and have a refractive index of 1.6 alternatively, aerosols with lower refractive indices may be generated from liquids such as dioctyl phthalate (m = 1.49). Whitby and Willeke (1979) discuss the... 

The constant coefficient, b, which is related to late surface deposition, is independent of particle composition hence, it is the same for the soil and the metal sphere populations. The coefficients, au are related to volume deposition and depend on chemical composition of the particles hence, they would be expected to be different for soil and metal sphere constituents. It would also be expected that the individual types of particles which make up a particular soil (e.g., quartz and feldspar) would exhibit different radionuclide compositions however, in the soil case the composition variation is independent of particle size so that a single average coefficient, 02,3, applies. However, the sphere/soil ratio in general varies with size, so that the radionuclide composition of the sphere population needs to be considered separately. 

As shown in Fig. E2.1(b), the effective area of a single particle in a horizontal layer is equivalent to that of an equal-sized triangle with side length of one particle diameter dv. Thus, the vertical loading on a single sphere under the bed height of 1 m is given by... 

The small-size of the activation volume suggests that the stmctural mechanism for transformation cannot be a coherent one involving the entire nanocrystal. Spread out over the entire volume of the nanocrystal, the activation volume would amount to a volume change smaller than that induced by thermal vibrations in the lattice. Therefore, a mechanism involving some fraction of a nanocrystal was considered. The nucleus was determined not to be three-dimensional, as a sphere the size of the activation volume would be less than a single unit cell. Also, activation volumes were observed to increase with increasing particle size (in the direction of... 

The simplest case to consider is the settling of a single homogeneous sphere, under gravity, in a fluid of infinite extent. Many experiments have been carried out to determine the relationship between settling velocity and particle size under these conditions and a unique relationship between drag factor (C ) and Reynolds number Re) has been found that reduces to a simple equation, known as the Stokes equation, at low Reynolds number. 

---