Particulate compounds

In addition to the well-characterized role of iron in catalysing redox interactions, other metallic contaminants, for example, nickel, may also contribute. In vivo toxicity studies have demonstrated the capacity of nickel particulate compounds to induce tumours following intraperitoneal injection (Pott etal., 1987). Such activity is proportional to their phagocytic uptake, and to the associated respiratory burst and generation of PMN-derived reactive oxygen metabolites (ROMs), a proposed pathogenic mechanism (Evans et al., 1992a). 

A number of significant oxygenated organic particulate compounds and gas-phase free radicals are formed by the reactions of gas-phase hydrocarbons (see Table 6-1 and (Chapter 2). The measurement methods for these substances are complicated and in the research stage. Their description is beyond the scope of this chapter. It is of major importance to develop methods for measuring hydroxyl and peroxyhydroxyl radicals, as well as the various oxygen species formed with ozone (see Chapter 12). 

Several types of particulate compounds have been studied so far. Among these are solid nanoparticles containing gadolinium complexes 98) or macro-molecular systems such as polylysine 99). 

The Isotopic Composition of Dissolved and Particulate Compounds in Ocean and Fresh Waters... 

The following section will discnss the carbon, nitrogen, oxygen, and snlfur isotope composition of dissolved and particulate compounds in ocean and fresh waters. The isotopic compositions of dissolved components in waters of different origins depend... 

Due to the extremely high boiling point of chromium, gaseous chromium is rarely encountered. Rather, chromium in the environment occurs as particle-bound chromium or chromium dissolved in droplets. As discussed in this section, chromium(VI) trioxide (chromic acid) and soluble chromium(VI) salt aerosols may produce different health effects than insoluble particulate compounds. For example, exposure to chromium(VI) trioxide results in marked damage to the nasal mucosa and perforation of the nasal septum, whereas exposure to insoluble(VI) compounds results in damage to the lower respiratory tract. 

Another study has shown a significant association between the severity of pulmonary inflammation/fibrosis induced by IP, as well as other particulate compounds including nickel oxide, nickel subsulfide, cobalt sulfate, and talc, and increased incidences of adrenal pheochromocytoma in rats (Ozaki et al. 2002). The systemic hypoxemia and reduced gas exchange induced by chronic pulmonary lesions from IP exposures may result from stimulated catecholamine secretion from the adrenal medulla and this chronic endocrine hyperactivity may lead to hyperplasia and neoplasia of the adrenal gland. 

OzAKi K, Haseman JK, Hailey JR, Maronpot RR and Nyska A (2002) Association of adrenal pheo-chromocytoma and lung pathology in inhalation studies with particulate compounds in the male F344 rat - the National Toxicology Program experience. Toxicol Pathol 30 263-270. 

Differences in transport, bioavailability and reactivity mean that the distinctions between dissolved vs. particulate and organic vs. inorganic phosphorus are important for the interpretation of environmental data. In the absence of significant advective transport, dissolved forms have a much greater mobility due to their molecular dif-fusivity. On the other hand, particulate compounds are removed from the water column... 

In 1931, Scott [S5] on the basis of compression plastomer studies suggested that rubber-particulate compounds at high loadings exhibited yield values further, he suggested the expression... 

Yeast and bacteria can produce biosurfactants, biological surfactants from various substrates including sugars, oils, alkanes and wastes [5]. Some types of biosurfactants are glycolipids, lipopeptides, phospholipids, fatty acids, neutral lipids, polymeric and particulate compounds [6]. Most are either anionic or neutral, while only a few with amine groups are cationic. The hydrophobic part of the molecule is based on long-chain fatty acids, hydroxy fatty acids or a-alkyl-jS-hydroxy fatty acids. The hydrophilic portion can be a carbohydrate, amino acid, cyclic peptide, phosphate, carboxylic acid or alcohol. 

Another common purification method is recrystallization. It is operationally simple and can be done on quantities down to the milligram scale using conventional microscale techniques and apparatus. It is relatively easy to conduct the required manipulations so as to avoid the inadvertent dispersal of particulates. Compounds sensitive to radiationgenerated oxygen radicals in solution can be protected by working under an inert gas atmosphere. ... 

Most lung diseases are eaused by inhaled particulate compounds, such as cigarette smoke, viruses, baeteria, pollen, and occupational or environmental pollutants (i.e., toxic or radioactive aerosols). An increasing number of diagnostic and especially therapeutic aerosols (bronchodilators, anti-inflammatory drugs, antibiotics,... 

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