If f(r) is the number of contributions of an author or rank r, then it is shown that f(r) is proportional to r–, where >0. The model is dependent on the definitions of a contribution and rank of an author. Three estimation procedures are illustrated and four other scientific productivity studies and two data sets on Canadian Mathematicians are shown to adequately fit this rank-frequency relationship.
Authors:H. MacCordick, J.-C. Hubert, and J. Schleiffer
The absorption effect of 5% w/w non-proliferative cell suspensions of Mycobacterium smegmatis on labelled solutions of Eu3+ ions, both alone and in admixtures with Am3+, Co2+ and Cs+, was studied at pH 1.0 as a function of time and cationic concentration. For 10 M concentrations of Eu, Co and Cs, selective adsorption of the trivalent lanthanide and actinide ions was practically quantitative after 90 min; no significant adsorption was observed for cobalt and cesium ions. Column adsorption measurements with the mycobacterial biomass showed that desorption of the M3+ ions did not occur at less than 2M HCl and remained incomplete even at higher acidities.
Biosorption of Th4+ and UO
ions, both separately and in mixed equimolar ratio, was carried out using nitrate-buffered solutions of the cations at pH 1 in the presence of 5%w/w non-proliferative cell suspensions of Mycobacterium smegmatis. At equilibrium following a 3 h treatment, specific adsorption for 2 mM Th and U was, respectively, 102 and 115 mol g–1 dry biomass for individual solutions and 102 and 42 mol g–1 for the mixed 2/2 mM solution. Desorption studies of the cation-loaded biomass preparations in aqueous media and in soilbacterial suspensions within the pH range <1 to 11 showed that leaching of throium was generally less than 1% at pH 1–11 after 7 d, whereas uranium was leached to the extent of 2% at pH 1 and up to 10% under the same conditions in Th–U mixtures.