Developing world science strategies.
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Brazil↗
Biomedical subjects
Ishenkumba A Kahwa
Publications and source records attributed to Ishenkumba A Kahwa.
Formation of two diverse classes of poly(amino-alkoxide) chelates and their mononuclear and polynuclear lanthanide(III) complexes.
Factors that influence aggregation of lanthanide(III) (Ln(III)) ions to form polynuclear complexes were studied utilizing 1-aziridineethanol as a versatile source of macrocyclic and acyclic chelates. The facile ring-opening cyclo-oligomerization of 1-aziridineethanol leads to the formation of a series of polyaza cyclic oligomers (series A). In the presence of ethylenediamine, a competing N-alkylation reaction occurs to produce a new class of acyclic ligands (series B). The cyclo-oligomerization of four 1-aziridineethanol units is the most favorable process, leading to the formation of the 12-membered cyclen-type macrocycle, H(4)L(1) (1,4,7,10-tetrakis(2-hydroxyethyl)-1,4,7,10-tetraaza-cyclododecane). Ring-opening cyclo-oligomerization of 1-aziridineethanol in the presence of Ln(III) ions produces self-assembled mononuclear, tetranuclear, and pentanuclear compounds of H(4)L(1). In the presence of ethylenediamine, oligomerization of 1-aziridineethanol results in a dinuclear complex of an acyclic poly(amino-alkoxide) H(2)L(2). The coordinative unsaturation of (i) the alkoxy sites of [H(x)L(1)](x)(-)(4) (where x < 4) and (ii) Ln(III) ions in coordination numbers less than nine are critical factors in the formation of the polynuclear Ln(III) complexes. The identities of mononuclear, dinuclear, tetranuclear, and pentanuclear complexes herein discussed were established by X-ray crystallography.
Journal Article↗
Asbestos: old foe in 21st century developing countries.
While use of asbestos materials in developed nations has been decreasing because of the harmful health effects of asbestos dust mining, processing and use of the ancient material in developing countries is increasing. The regulatory mechanism for use, handling and disposal of asbestos and associated waste in developing countries are weak and information on asbestos-related diseases is scanty but emerging. We identify lack of epidemiological data on asbestos health effects as a major gap to be bridged in the promotion of occupational and environmental health in developing countries. Without data on local situations, diseases such as asbestosis and mesothelioma remain too obscure to assist the campaign for appropriate regulation of asbestos usage or attracting attention to abominable industrial practices generally.
Asbestos↗