Microparticles sources

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). 

This application was motivated by the potential for exploiting the LMI source s rich selection of ions and microparticles to investigate secondary ionization processes, the possibility of improving sensitivity, and the more remote prospect of achieving localized, molecular analysis of biological tissues with a finely focused ion beam. 

The suspensions induding ionized substances contain an excellent source of charged microparticles. 

Figure 7 Principle of a Monte Carlo-based approach to mathematically model polymer degradation and drug diffusion in PLGA-based microparticles. Scheme of the iimer structure of the system (one-quarter of a spherical cross section) (A) at time t = 0 (before exposure to the release medium) and (B) during dmg release. Gray, dotted, and white pixels represent nondegraded polymer, drag and pores, respectively. Source From Ref. 48.

Recent work has characterized the microparticles and identified their sotrrces other than those from the degradation of materials. For example, textile fibers, sometimes coming directly from the water of washing machines [BRO 11], are clearly identified as a source constituting a significant contribution to the sea. UNESCO also assesses that purification sludge stations are also an important sotrrce of microplastics. 

The microphase is present as a microslurry of a sparingly soluble salt reacting with a diffusing gas (Ramachandran and Sharma, 1969 Uchida et al., 1975 Sada et al., 1980 Alper et al., 1980 Alper and Deckwer, 1981 Sada and Kumazawa, 1982 Yagi and Hikita, 1987). The reactant microparticles enter the liquid film around the gas bubbles and enhance mass transfer (Figure 23.1b). Because in this case the microphase provides the reactant to the bulk, it is referred to as a source. ... 

FIGURE 6.30 Release profile of insulin-loaded microparticles in response to a glucose stimulus. Source Marek and Peppas [118], figure 7. Reproduced with permission of John Wiley Sons. 

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