Ensemble Selection Factors

Classification of Protective Clothing Personal protective clothing includes the following  

Fully encapsulating suits Nonencapsulating suits Gloves, boots, and hoods Firefighters protective clothing Proximity, or approach clothing Blast or fragmentation suits Radiation-protective suits 

Be aware that different materials will protect against different chanicals and physical hazards. When chemical or physical hazards are present, check with the clothing manufacturer to make sure that the material selected will provide protection against the specific chemical or physical hazards in the woikplace for which they are procured (see Table 24.4). 

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So far we discussed how selectivity is influenced by altered surface compositions. We identified the ensemble effect as a geometric control factor and competitive adatom reactivity as an electronic control factor. 

For each set of initial conditions, Eqs. (4.1)-(4.3) can be solved to And X ", U ", and The initial conditions are randomly selected from known distribution functions, and we can assume that there is an infinite number of possible combinations. Each combination is called a realization of the granular flow, and the set of all possible realizations forms an ensemble. Note that, because the particles have finite size, they cannot be located at the same point thus X " 4 X for n 4 m. Also, the collision operator will generate chaotic trajectories and thus the particle positions will become uncorrelated after a relatively small number of collisions. In contrast, for particles suspended in a fluid the collisions are suppressed and correlations can be long-lived and of long range. We will make these concepts more precise when we introduce fluid-particle systems later. While the exact nature of the particle correlations is not a factor in the definition of the multi-particle joint PDF introduced below, it is important to keep in mind that they will have... 

It is not clear at this moment if the dispersion of Pd is a factor which determines the enantioselectivity of the catalyst. However, the positive effect of the heat treatment on the selectivity of most catalysts suggests that the clean Pd surface of a relatively large ensemble size is advantageous for both the modifier and substrate molecules to adsorb strongly enough. 

In February 1997, Nie and Emory were the first to report on Raman spectroscopy of single molecules adsorbed at optically selected nanoparticles [15]. For this system, giant enhancement factors of lO " to 10 had been estimated, which were substantially larger than the ensemble averaged enhancement factors. It was also important that the single-molecule SERS spectra were both more intense and more stable than single-molecule fluorescence spectra [15]. 

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