Particulate size

Crystallite Size. From the width of the peaks the computer can determine the size of the crystaUites in the sample. The smaller the crystaUite size, the broader are the diffraction peaks. This kind of analysis is important for determining particulate size of certain materials (eg, sUica) where a range of crystaUite size may be a health hazard if inhaled into the lungs. 

EPA will closely examine particulate size distribution in particulate emission trades because finer particulates disperse more widely, remain in the air longer, and frequently are associated with more adverse health effects. 

Pollutant (if particulate) Size range and distribution Particle shape Agglomeration tendencies Corrosiveness Abrasiveness Hygroscopic tendencies Stickiness InflanunabiUty Toxicity Electrical resistivity Reactivity... 

Geometrical standard deviation A measure of the range of particulate sizes present in a collection of particles. 

Maximum penetrating particle size The particulate size for which a filter has minimum removal efficiency under test conditions. 

Nephelometer A device used to determine the suspended particulate size and concentration by the scattering of light. 

Environmental Fate. It can be concluded from the transport characteristics that surface water sediment will be the repository for atmospheric and aquatic thorium. Normally, thorium compounds will not transport long distances in soil. They will persist in sediment and soil. There is a lack of data on the fate and transport of thorium and its compounds in air. Data regarding measured particulate size and deposition velocity (that determines gravitational settling rates), and knowledge of the chemical forms and the lifetime of the particles in air would be useful. 

Systems are generally limited to treating waste stream solutions and slurries containing 2 to 25% organics with a maximum particulate size of 100 p,m. 

Data reported only for 40-pm particulate size. Other particulate size burdens were monitored for information only. Data are available in original printouts. 

The images in Fig. 2.25 demonstrate the moisture/blood absorption of the absorbable polymer, and a particulate size (50-200 pm) was chosen to visibly observe and photograph the growth in size of the particulate. However, a 5-15 pm size would better coat the nonlinear surface of tissue. 

Shaw, P. J. 1994. The effect of pH, dissolved humic substances, and ionic composition on the transfer of iron and phosphate to particulate size fractions in epilimnetic lake water. Limnology and Oceanography 39 1734—1743. 

Alves, C, Pio, C, and Duarte, A. C. (2000). Particulate size distributed organic compounds in a forest atmosphere. Environ. Sci. Technol. 34,4287 4293. 

Finally, fluidized-bed mixers are rapid mixers, but cannot, of course, deal with cohesive powders or a very wide distribution of particulate sizes neither are they suitable for powder mixtures with pronounced size, density, and shape variations because of segregation problems. They generate small static electric charges. 

For TG work it is generally recommended to use as little sample as possible within the limits of resolution of the microbalance. The homogeneity of a sample can sometimes limit how little sample can be used, e.g., in case of polymeric materials. Powdered samples, of small particulate size, have the ideal form for TG studies. However, in polymer science, samples are often also in the form of films, fibres, sheets, pellets, granules or blocks. The packing density should be as uniform as possible. 

For evaluating the toxic characteristics of an inhalable material (e.g., gas, volatile chemical, or aerosol/particulate material), animals are subjected to repeated exposures after initial information on material toxicity has been obtained by acute testing. It provides information on health hazards likely to arise from repeated exposure via the inhalation route over a limited period of time. Hazards of inhaled chemicals are influenced by inherent toxicity and physical factors, such as volatility and particulate size. 

We have applied it to a determination of paraquat residues in air collected over 200 m from a spraying operation, both during and for several hours following treatment. Additionally, the method may be used to measure the quantity of paraquat associated with various particulate size fractions collected by cascade impaction. 

Clearance kinetics by the MPS are highly dependent on the physicochemical properties of the particulate, in particular on particulate size, charge and surface hydrophobicity ... 

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