Lateral spreads

Nuclear-physical methods ai e the basic ones in controlling environmental pollution which results from nucleai -power complexes and power plants work. Oil and gas production leads to the extraction of radio nuclides of natural origin in considerable amounts, which later spread from oil-slimes and water wastes in the neighborhoods of oil and gas producing entei prises. Similaidy, toxic and radioactive elements can pollute environment in case of mineral deposits extraction. 

The spatial resolution in quantitative analysis is defined by how large a particle must be to obtain the required analytical accuracy, and this depends upon the spatial distribution of X-ray production in the analysed region. The volume under the incident electron beam which emits characteristic X-rays for analysis is known as the interaction volume. The shape of the interaction volume depends on the energy of the incident electrons and the atomic number of the specimen, it is roughly spherical, as shown in Figure 5.7, with the lateral spread of the electron beam increasing with the depth of penetration. 

The spatial resolution of X-ray analysis carried out in the EPMA is limited to the size of the sampling volume, which is around 1 pm3. There may be many important features of a specimen which are smaller than 1 pm, and one way of overcoming the problem is by the use of thin specimens. We have seen (Figure 5.7) that the lateral spread of the electron beam increases with depth of penetration, so that in a sufficiently thin specimen the beam spread is much less. We will therefore next consider the analysis of thin foil specimens in the TEM. 

May cause a lateral spread of dissolved or separate phase contaminant plume Contamination may be transferred from groundwater to die vadose zone Has limited applicability at sites with confined aquifers Low soil permeability or other heterogeneous conditions may reduce effectiveness... 

Has the potential to cause a lateral spread of dissolved or separate phase contaminant plumes. 

As the aspect ratio increases the number of terraces observed decreases, whilst the heights of terraces remain constant. The lateral spread of terraces increases as the aspect ratio increases. A greater number of terrace terminations are also observed when the aspect ratio of crystals increases. 

In early phases of PD, dopamine loss affects primarily the posterior putamen (the striatal motor area) but later spreads to involve other nigrostriatal regions. In later stages, more widespread dopamine loss and neuronal degeneration in non-dopaminergic systems, such as the locus coeruleus and the raphe nuclei may account for some of the non-motor aspects of PD. 

Diffusion and mass transfer effects cause the dimensions of the separated spots to increase in all directions as elution proceeds, in much the same way as concentration profiles become Gaussian in column separations (p. 86). Multiple path, molecular diffusion and mass transfer effects all contribute to spreading along the direction of flow but only the first two cause lateral spreading. Consequently, the initially circular spots become progressively elliptical in the direction of flow. Efficiency and resolution are thus impaired. Elution must be halted before the solvent front reaches the opposite edge of the plate as the distance it has moved must be measured in order to calculate the retardation factors (Rf values) of separated components (p. 86). 

Fan spray atomizers have been widely used in the spray coating industry (Fig. 2.5), in some small annular gas turbine combustors, and in other special applications that require a narrow elliptical spray pattern rather than the normal circular pattern. In particular, fan spray atomizers are ideal for small annular combustors because they can produce a good lateral spread of fuel, allowing to minimize the number of injection ports. 

A prime determinant of the absorption rate from an SC injection is the total surface area over which the absorption can occur. Although the subcutaneous tissues are somewhat loose and moderate amounts of fluid can be administered, the normal connective tissue matrix prevents indefinite lateral spread of the injected solution. These barriers may be overcome by agents that break down mucopolysaccharides of the connective tissue matrix the resulting spread of injected solution leads to a much faster absorption rate. 

Where the source is limited or ceases, capillary spreading eventually slows until further migration is limited and equilibrium is reached. This stable condition is attained when the leading edge of the laterally spreading light LNAPL fails to be... 

Comparative studies on the bioavailability of three different tretinoin gel formulations showed that the dimensions of the sampling area may play a critical role in determining the extent of dermal drug uptake [33, 34], If, by lateral spreading, a substance is distributed over an area sufficiently larger than the sampling area, significant proportions of compound will not be recovered and hence permeability will be underestimated. 

In this regime the multiple nucleation of stems is so prohfic [Fig. 1.15(growth rate is exactly of the same form as in regime 1... 

For a well-controlled 3D exposure, it is necessary to control the light intensity distribution at the focus, which is described by the point-spread function (PSF). Even for tight, aberration-free focusing, the axial spreading of PSF is larger than the lateral spreading [40] ... 

All naturally occurring steroids, and the overwhelming majority of those used as drugs, comprise single enantiomers. When written as in the flow schemes that follow, the diagrams depict the absolute configuration. Substiments below the plane of these rather flat molecules are named a while those above that face are named (3, a convention that later spread to many other strucmral classes. 

Local accumulation of dirt on a steel structure in a damp environment is enough to set up an anodic area underneath it by excluding air. Similarly, chipped paintwork results in lateral spreading of anodic areas under the paintwork, radially outward from the chips. At the chipped site, air has relatively free access to the metal, but under the paint the oxygen is excluded and anodic activity becomes intense, spreading under the paint and leaving a trail of rust behind where air has slowly diffused in to oxidize the Fe2+(aq). 

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