N-Methylmorpholine-N-oxide ring cleavage registration by ESR under heating conditions of the Lyocell process.

Thermal cleavage processes of N-methylmorpholine-N-oxide monohydrate (NMMO) were observed in pure NMMO as well as in cellulose/NMMO solutions by ESR at temperatures of the industrial Lyocell process ( approximately 370K). Generated radicals were attributed to the alkylnitroxyl type radicals -CH(2)-NO-CH(3) in NMMO and additional (and dominated) -CH(2)-NO-CH(2)- in cellulose/NMMO solutions. Formation of both radical types formed due to NMMO ring scission is suggested.

Electron spin resonance study of radicals generated in cellulose/N-methylmorpholine solutions after flash photolysis at 77 K.

The processes of radical formation in N-methylmorpholine-N-oxide monohydrate (NMMO) and cellulose/NMMO solutions were studied by ESR at 77 K under high-power UV (lambda = 248 nm) excimer laser flash photolysis. Radicals mainly generated were attributed to the nitroxide type radicals -CH2-NO*-CH2- and -CH2-NO*-CH3 at the first step and methyl *CH3 and formyl *CHO radicals at the second step of the photoreaction. Kinetic studies of these radicals revealed that formation and recombination rates of the radicals depend on the cellulose concentration in cellulose/NMMO solutions and the concentration of additional ingredients, e.g. Fe(II) and propyl gallate. Even at frozen state temperature, acceleration or quenching of radical reaction processes was found. The proposed scheme of UV light-induced NMMO degradation during irradiation based on ESR data correlates well with independently obtained results based on high-performance liquid chromatography (HPLC). The analysis of degradation products by HPLC, e.g. aminoethanol and acetaldehyde, supports the assumption concerning a radical-initiated ring opening of NMMO.

[Comparative morphological studies of the structure of the articular disk of the temporomandibular joint]. / Vergleichend-morphologische Untersuchungen über die Struktur des Discus articularis des Kiefergelenkes.

Articular disks (DA) of mandibular articulations of several types of animals of different ages and both sexes (herbivora, carnivora, rodents and omnivora) were studied. Comparative macroscopy emphasized similarities with the DA of humans and other omnivora, as well as some peculiarities. DA is ellyptical in herbivora; its upper surface is divided into two facets by a transversal crest. DA is pinkish and square in carnivora; its posterior part is lacking. DA is half-moonish and white-nacreous in rodents; its upper surface presents a longitudinal crest. Microscopy evidenced some differences: the collagen fibrils are dominating in herbivora, while in carnivora the elastic ones. The rodents present rare elastic fibers; these animals and the ruminants show capillaries in the central part of the DA, while in other animals these are absent. Cells are mainly located in the upper superficial layers of DA. Relationships between form, histological structure and functions, mainly regarding the mastication types, are discussed.