Low molecular weight organic

Oxidation first produces soluble oxygenated compounds of molecular weights between 500 and 3000 that increase the viscosity of oil then they polymerize, precipitate, and form deposits. Oxidation also causes formation of low molecular weight organic acids which are very corrosive to metals. 

Under favorable conditions, low molecular weight organics may polymerize on surface of adsorbent (dialkenes, 1-alkenes, alkynes, conjugated double-bond systems, and epoxides are especially susceptible to this behavior). 

PAG sludge can be regenerated by wet air oxidation (WAO) or by a multiple-hearth furnace. Capacity losses might be high in WAO, particulady with low molecular weight organics. Weight loss in a furnace may exceed 20%. 

Direct Metal Reaction. The DMR process is carried out over a catalyst with fatty acids ia a melted state or dissolved ia hydrocarbons. The acid reacts directiy with the metal, suppHed ia a finely divided state, produciag the metal soap and ia some cases hydrogen. Catalysts iaclude water, aUphatic alcohols, and low molecular-weight organic acids. 

Short-chain and low molecular weight organic acids, such as acetic acid and formic acid, can be formed by certain bacteria. The resulting organic acid salts are not easily detected without specialized analytical equipment in a laboratory. 

Acidolysis is a similar weathering reaction to hydrolysis in that is used to weather minerals, but in this case the source of is not water but organic or inorganic acids. Humic and fulvic acids (discussed in Section 8.3.2), carbonic acid, nitric or sulfuric acid, and low-molecular-weight organic acids such as oxalic acid can all provide H to weather minerals. All of these acids occur naturally in soils in addition nitric and sulfuric acid can be added to soil by acid pollution. The organic acids are prevalent in the... 

The chemical composition of biological objects is extremely complex. They contain the macromolecules of proteins, lipids, and many other substances in addition to low-molecular-weight organic and inorganic compounds. Different external effects can produce both quantitative and qualitative composition changes some substances disappear and/or others appear. Some substances that are essential for the functioning of the cells or of the entire organism are present in very small concentrations, lO Mand less. 

Del Nozal, M. J., Bernal, J. L., Diego, J. C., Gomez, L. A., and Higes, M. (2003a). HPLC determination of low molecular weight organic acids in honey with series-coupled ion-exdusion columns. /. Liq. Chromatogr. Relat. Technol. 26,1231-1253. 

F. S. Zhang, J. Ma, and Y. P, Cao, Phosphorus deficiency enhances root exudation of low-molecular weight organic acids and utilization of sparingly soluble inorganic phosphates by radish (Raphanus. sativus L.) and rape Bra.ssica napus L.) plants. 

L. Strom, T. Olsson, and G. Tyler, Differences between calcifuge and acidifuge plants in root exudation of low molecular weight organic acids. Plant Soil 167 239 (1994). 

G. Cieslinski, K. C. J. Van Rees, A. M. Szmigielska, G. S. R. Krishnamurti, and P. M. Huang. Low-molecular-weight organic acids in rhizosphere soils of durum wheat and their effect on cadmium bioaccumulation. Plant Soil 203 109 (1998). 

Gross differences have been ob.served in the amounts of fixed carbon released by annuals and perennials (47), with annuals releasing much less C than perennials. This effect may in part be due to perennials having to invest more of their assimilates to survive year round. Between more closely related plants, several studies have reported that both the quantity and quality of root exudates vary between plant species (39,48,49). In addition, it is also recognized that different cultivars of the same species may vary in their root exudation patterns. For example, Cieslinski et al. (50) quantified low-molecular-weight organic acids released... 

Renella G., Landi L., Nannipieri P. Degradation of low molecular weight organic acids complxed with heavy metals in soil. Geoderma 2004 122 311-315. 

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