Particle size, statistics

Hinds WC (1982). Particle size statistics. In Aerosol Technology. Properties, Behavior and Measurement of Airborne Particles, pp. 69-103. New York, Chichester, Brisbane, Toronto, Singapore John Wiley Sons, Inc./Ltd. 

The following sections detail existing in vitro/in vivo correlations for the major aerosol modalities and, where appropriate, comparisons are made with lung model predictions. Measures of particle diameter, particle size statistics, and aerosol test methods are also discussed. Aerosol test methodologies are included in the discussion because, as described above, sizing results are highly dependent upon the method and apparatus used. The correlations that have been developed and any predictions that can be made from them are therefore specific to the use of particular experimental methods, and it is important that the applicability of the different instruments/methods be understood. 

Schaniel and coworkers studied the properties of the photoinduced ON and r/ -NO isomers in Na2[Fe(CN)5N0]-2H20 embedded in meso-pores of sihca xerogels by X-ray diffraction, steady-state low-temperature absorption, nanosecond transient absorption spectroscopy, and IR spectroscopy (34). They determined that the electronic structures and activation energies of these / -ON and tf -NO isomers were not dependent on the particle size (statistically distributed molecules or nanoparticles) and as such the isomers were essentially quasi-free inside the pores of the gel (34). 

Transmission Electron Microscopy (TEM) micrographs were taken in a JEM 100 CXI electron microscope, with an optimal resolution of 6 A. Palladium particle size statistics were estimated on at least 200 to 300 particles for PdN samples for Pd A, visible particles were scarce and the statistics had to be limited to less than 100 particles. 

The concepts described in Section 4.1 apply equally well to particle size distributions and to other quantities commonly characterized by number statistics— for example, dollars, populations, or the dimensions of machined parts. What makes particle size statistics more complicated is that we frequently measure or need to know some quantity that is proportional to particle size raised to a power (moment), such as surface area, which is proportional to d, or mass, which is proportional to d. There is no counterpart of this in number statistics, for what is the meaning of or (people) The need to use moment averages for particle statistics arises because aerosol size is frequently measured indirectly. For example, if you have a basket of apples of different sizes, you could determine the average size by measuring each apple with calipers, summing the results, and dividing by the total mun-ber of apples. This procedure is direct measurement. If, however, each apple were... 

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