Mechanochemical polymerization of lactide is carried out by using ball milling. Mechanical energy from collisions between the balls and the vessel efficiently promotes an organic-base-mediated metal- and solvent-free solid-state polymerization. Investigation of the parameters of the ball-milling synthesis revealed that the degree of lactide ring-opening polymerization could be modulated by the ball-milling time, vibration frequency, mass of the ball media, and liquid-assisted grinding. Liquid-assisted grinding was found to be an especially important factor for achieving a high degree of mechanochemical polymerization. Although polymer-chain scission from the strong collision energy prevented mechanical-force-driven high-molecular-weight polymer synthesis, the addition of only a small amount of liquid enabled sufficient energy dissipation and poly(lactic acid) was thereby obtained with a molecular weight of over 1×10 g mol .

Using nationally representative data from the 2008-2011 KNHANES, low pulmonary function was found to be associated with low muscle mass in community-dwelling older Korean adults.

Excited radical ions are interesting reactive intermediates owing to powerful redox reactivities, which are applicable to various reactions. Although their reactivities have been examined for many years, their dynamics are not well-defined. In this study, we examined intermolecular and intramolecular electron transfer (ET) processes from excited radical anions of naphthalene-1,4,5,8-tetracarboxydiimide (NDI(•-)*). Intermolecular ET processes between NDI(•-)* and various electron acceptors were confirmed by transient absorption measurements during laser flash photolysis of NDI(•-) generated by pulse radiolysis. Although three different imide compounds were employed as acceptors for NDI(•-)*, the bimolecular ET rate constants were similar in each acceptor, indicating that ET is not the rate-determining step. Intramolecular ET processes were examined by applying femtosecond laser flash photolysis to two series of dyad compounds, where NDI was selectively reduced chemically. The distance dependence of the ET rate constants was described by a β value of 0.3 Å(-1), which is similar or slightly smaller than the reported values for donor-acceptor dyads with phenylene spacers. Furthermore, by applying the Marcus theory to the driving force dependence of the ET rate constants, the electronic coupling for the present ET processes was determined.

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