The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
An adjective describing anything that consists of, or relates to, particles. The term was formerly used in laboratory slang to stand for "particulate matter," but this use has nearly disappeared since its repudiation by the Environmental Protection Agency (EPA). The term particulate matter, which often means the particle content of a given volume of air, is used as a more inclusive variant of "particles."
Typical atmospheric particulate matter may comprise three populations of particles according to size. The smallest of these is found only near sources, since the particles rapidly aggregate to larger sizes. The upper size limit for these particles is near 0.1 micrometer (1 micrometer = 1 μm = 0.001 mm). Number concentrations can be quite high. This population is referred to as the nuclei mode of particles. The next larger size class, which begins at a diameter of about 0.1 μm and extends to about 2.0 μm, is called the accumulation mode, since once in the air it tends to remain for days; number concentrations have become low enough that agglomeration is slow, and settling velocities are very small. The sum of the nuclei mode and the accumulation mode is called the fine particles. These are characteristically formed by condensation from the gas phase, or by agglomeration of particles formed from the gas phase. The final particle population in air is called the coarse mode, or simply the coarse particles. These are of any size larger than about 2 μm (about 1/10,000 inch), and are formed by mechanical grinding of larger masses of matter. Coarse particles are usually particles of local soil or rocks.