Kinetics of polymerization of vinyl monomers initiated by manganese(III) acetate. I

The kinetics of thermal polymerization of acrylic acid (AA), methacrylic acid (MAA), acrylonitrile (AN), and methacryl-amide (MAM) in aqueous sulfuric acid using manganic acetate was studied. The effect of variations in [monomer], [Mn<SUP>3+</SUP>], [H<SUP>+</SUP>], μ, and temperature on the rates of monomer disappearance (R<SUB>p</SUB>), Mn<SUP>3+</SUP> disappearance (−R<SUB>m</SUB>), and the degree of polymerization (X<SUB>n</SUB>) were studied. Based on the kinetic results, a suitable reaction scheme is proposed and rate expressions are derived. The rate constants, such as k<SUB>i</SUB>, k<SUB>p</SUB>/k<SUB>t</SUB>, and thermo-dynamic parameters, corresponding to these are evaluated

Seckel syndrome: A report of a case

Seckel syndrome, first defined by Seckel in 1960, is a rare (incidence 1:10,000), genetically heterogeneous autosomal recessive disorder presenting at birth. This syndrome is characterized by a proportionate dwarfism of prenatal onset, a severe microcephaly with a "bird-headed" like appearance (beaked nose, receding forehead, prominent eyes, and micrognathia), and mental retardation. The significance of dental alterations in this syndrome resides in the defect, hypoplastic enamel, being limited to the primary dentition; in most instances the second primary molar tooth is not affected. A case of the Seckel syndrome is presented

Structure and reactivity of vinyl monomers in radical polymerization. 1. Kinetics of polymerization initiated by Manganese (III) acetate

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