Monitoring methods Light scattering

Other measurements important to visual air quality are pollutant related, i.e., the size distribution, mass concentration, and number concentration of airborne particles and their chemical composition. From the size distribution, the Mie theory of light scattering can be used to calculate the scattering coefficient (20). Table 14-2 summarizes the different types of visual monitoring methods (21). 

It is hard to And better monitoring tools than optical spectroscopy methods when high spatial and temporal resolution is required in addition to noninvasiveness. Traditionally, absorption, light scattering, chemiluminescence, and fluorescence measurements are used for this purpose (Janasek et al. 2006). Those are well-established techniques that establish a simple way of obtaining useful information. However, absorption and scattering measurements provide very little information about the chemical composition. Fluorescence spectroscopy provides more information but is... 

Critical phenomena of gels have been studied mainly by dynamic light scattering technique, which is one of the most well-established methods to study these phenomena [18-20]. Recently, the critical phenomena of gels were also studied by friction measurement [85, 86] and by calorimetry [55, 56]. In the case of these methods, the divergence of the specific heat or dissipation of the friction coefficient could be monitored as a function of an external intensive variable, such as temperature. These phenomena might be more plausible to some readers than the divergence of the scattered intensity since they can observe the critical phenomena in terms of a macroscopic physical parameter. 

A variety of instruments and techniques exist for monitoring particle size. The most widely used techniques rely on laser light scattering, as reviewed by Tadros et al. (2004). Instruments manufacturers include Nicomp, Coulter, Horiba, Sympatec, and Malvern. Electron microscopy has also been used, but artifacts introduced by Lxing techniques should be carefully controlled. Typically, emulsions produced by the methods described above yield particle sizes of 100-1000 nm particle sizes less than 200 nm are generally required for emulsions used intravenously. 

Gamblin TC, King ME, Dawson H, Vitek MP, Kuret J, Berry RW, et al. (2000) In vitro polymerization of tan protein monitored by laser light scattering method and application to the study of FTDP-17 mutants. Biochemistry 39 6136-6144 Goedert M (1993) Tau protein and the neurofibrillary pathology of Alzheimer s disease. Trends Neurosci 16 460-465... 

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