Congo , elements

Negrel Ph, Allegre CJ, Dupre B, Lewin E (1993) Erosion sources determined by inversion of major and trace element ratios and strontium isotopic ratios in river water the Congo Basin case. Earth Planet Sci Lett 120 59-76... 

Based on the same principle, there are monomeric / -helical proteins that carry at their extremities a cluster of helical or nonrepetitive structures that could act as a capping element covering their exposed ends (Emsley et al., 1996 Lietzke et al, 1994 Petersen et al, 1997 Steinbacher et al, 1994). For example, the last 40 residues of pectate lyase C form a large loop that partially covers the surface of the /Hielix (Yoder et al, 1993). The fibrous (or otherwise elongated) domain of these natural /f-stranded proteins is not stable in isolation, as for example in the case of the P22 tailspike where bacterially expressed isolated /Hielix domain, at high concentrations, forms fibrous aggregates that bind Congo red (Schuler et al, 1999). 

Plutonium is the only transuranium element which has been found in nature. Until its properties were known it would have been impossible to detect it in the minute amounts in which it occurs, but when its behavior was understood, Seaborg and his co-workers were able to find it in pitchblende, monazite ores, and carnotite in concentrations of about one part in 1014 (63, 73, 76). Peppard and his group found it in somewhat greater amounts in pitchblende from the Belgian Congo (77). Seaborg believes that most of this plutonium arises by fission of the uranium in the ore, though other processes may also be involved (77, 78). 

The fluorochromes, Calcofluor White and Congo red bind to chitin and cellulose, while acridine orange binds to nucleic acids of the fungi. These dyes may be helpful when there is a lack of fungal elements (blastospores, hyphae or pseudohyphae) in the specimen, as even few elements are visible under the fluorescence microscope. By using specific antibodies conjugated with the fluorochromes, it should be possible to identify specific fungi. 

Cobalt ranks number 33 in abundance of the elements in the earth s crust, which contains on average 20-pg Co/g, although soil levels of up to 2000- J,g Co/g are found in Zaire and New Zealand. Significant deposits of cobalt are found in Canada, Russia, Zambia, and Congo, with these countries accounting for approximately 65% of the current total world supply. Smaller deposits are found in Cuba, New Caledonia, and Australia. Cobalt does not exist as the free metal in nature, but occurs in approximately 200 ores, of which smaltite (C0AS2), cobaltite (CoAsS), and linnaeite (C03S4) are commercially important. 

This mean value should be considered as a hrst-order approximation, because for the majority of elements, the number of analyses is small. Because our best information on trace concentrations is from humid tropical areas, the mean values proposed here are dominated by rivers such as the Amazon, Orinoco, and Congo, and may therefore be overestimates for a number of elements (such as REEs). Eor trace metals, the role of global pollution is an unresolved issue that may also contribute to enhancing the mean value proposed in Table 1 (especially for trace metals). These values compare relatively well with the previous estimates of Martin and Meybeck (1979) for selected trace elements, with the exception of lower concentrations for some metals in the present study. 

Figure 3 Dendrograms of cluster analysis of the trace-element concentrations in the dissolved load of the Congo rivers (Dupre et al, 1996) showing affinity groupings of elements.

Dupre B., Gaillardet J., and Allegre C. J. (1996) Major and trace elements of river-bome material the Congo Basin. Geochim. Cosmochim. Acta 60, 1301—1321. 

Imported Inorganic Chemical Elements, Oxides and Halogen Salts in Congo (Zaire),... 

Radium. Ra at. wt 226 (mass number of most stable isotope) at. no. 88 valence 2. A radioactive alkaline earth meta], Occurrence in earth s crust approx ]0-d% by wt. Natural isotopes 223, actinium X 224, thorium X 226 228, mesothorium 1. 22 Ra is a product of disintegration of uranium and is present in al] ores contg uranium. Separated in the form of a salt by P. and M. S. Curie from the pitchblende nf Joachimsthal, Bohemia Curie et at.. Compt. Rend. 127, 12]5 (1898). [soln of the element by electrolysis of an aq soln of radium chloride Curie, Debierne. ibid. 151, 523 (1910). 12 Ra iT, 6.7 years) produced by disintegration of thorium (I12Th) discovered in 1907 by O. Hahn in monazite residues from isolating thorium. Zaire (Congo) is the main producer of radium, Canada next. Clinical evaluation in... 

Probst, J. L., Nkounkou, R. R., Krempp, G., Bricquet, J. R, Thidbaux, J-R, OUvry, J-C. (1992). Dissolved major elements exported by the Congo and Ubangi Rivers during the period 1987-1989. Journal of Hydrology (Amsterdam), 135(1 ), 237-257. 

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