Enzymatic Oxidative Polymerization of Phenol in an Aqueous Solution in the Presence of a Catalytic Amount of Cyclodextrin

The peroxidase‐catalyzed polymerization of phenol in aqueous solution has been examined in the presence of 2,6‐di‐O‐methyl‐α‐cyclodextrin (DM‐α‐CD). By the addition of DM‐α‐CD, the phenol was polymerized in a buffer to produce the soluble polyphenol. Only a catalytic amount of DM‐α‐CD induced the polymerization effectively. A small amount of DM‐α‐CD was contained in the polymer.     

Polyimides with alicyclic diamines. I. Syntheses and thermal properties

The polyaddition reactions of alicyclic diamines such as 1,4-diaminocyclohexane (1,4-CHDA) or 4,4′-diaminodicyclohexylmethane (DCHM) and configurational isomers of 1,4-CHDA or DCHM with tetracarboxylic aromatic anhydrides in aprotic solvents were carried out to prepare high molecular weight poly(amic acid)s. Through the thermal imidization of poly(amic acid)s, several flexible polyimide films were prepared. Because of the stiffness of the alicyclic moieties in diamines, the resulting polyimides exhibit high glass transition temperatures (220–340°C) almost similar to those for corresponding aromatic polyimides which have phenylene groups in place of cyclohexyl groups, and show good thermal stability. The partial crystallization was observed for polyimides with trans-cyclohexyl moiety during the heating in differential scanning calorimetry and ascertained by wide-angle x-ray diffraction. Thus, the inhibition of the occurrence of charge transfer in polyimides is accomplished by introducing alicyclic diamines in place of aromatic diamines without reducing their thermal stability. © 1993 John Wiley & Sons, Inc.     

Reversible photostructural change in chalcogenide glass films observed in infrared absorption spectra

Measurement of infrared absorption spectra in amorphous chalcogenide films revealed changes which can be closely related with the reversible photostructural change. The changes came out in intensity of absorption peak situated near 650 cm^-1 as well as definite change in infrared fundamental absorption peak. The absorption peak intensity near 650 cm^-1 showed considerable decrease by annealing, while it recovered initial value after light exposure. The change was shown to be in close correspondence with the well known reversible optical absorption edge shift.     

Tightness problem and stochastic evolution equation arising from fluctuation phenomena for interacting diffusions

The central limit (or fluctuation) phenomena are discussed in the interacting diffusion system. The tightness in the Kolmogorov-Prokhorov sense is proved for a sequence of distribution valued processes arising from finite particle systems. Further, the stochastic differential equation for the limit process is derived by constructing an infinite dimensional Brownian motion.     

De Rham-Hodge-Kodaire decomposition in ∞-dimensions

Dedicated to Professor Haruo Suzuki on the occasion of his sixtieth birthday     

Applications of molecular mechanics to alkyl radicals

The MM2 force field has been extended to alkyl radicals. The known structures and conformational energy relationships are well reproduced for many simple radicals, and predictions were made for 1-butyl, 2-butyl, cyclopentyl, cyclohexyl and others. Heats of formation were also studied.     

pH-Responsive shrinkage/swelling of a supramolecular hydrogel composed of two small amphiphilic molecules

A pH-responsive volume-change function was successfully introduced into a supramolecular hydrogel that contained GalNAc-appended (GalNAc=N-acetylgalactosamine) glutamate ester 1 by the simple mixing of it with an appropriate amount of 2 a or 2 b amphiphilic carboxylic acid. In the 1:1 mixture (1:2), the hydrogel swelled under neutral pH conditions, but shrank to almost half of its original volume under acidic pH conditions. The structure and pH response of the mixed hydrogel were characterized by using X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), transmission or scanning electron microscopy (TEM, SEM), and Fourier transform IR (FTIR) spectroscopy. Well-developed fibers formed a stable hydrogel by self-assembly, and under acidic conditions the charge of the carboxylic acid terminal (from the carboxylate anion) was neutralized and then these fibers became densely packed. This macroscopic pH response was also applied to the pH-triggered release of bioactive substances. In this mixed supramolecular hydrogel, the hydrogelator 1 provides a stable hydrogel structure and the additive 2 acts as a commander that is sensitive to an environmental pH signal. The present supramolecular copolymerization strategy should be useful for the construction of novel, stimuli-responsive, soft materials.