Secondary wall definition

A / -D-glucan has been isolated from the cell walls of 3-day-old, mung-bean hypocotyls.76 Extracts of cell walls of older hypocotyls were deficient in this polysaccharide. The glucan contained 3-linked and 4-linked glucopyranosyl residues in the molar ratio of 1.0 1.7. However, the hypocotyl tissue from which the glucan was extracted contained both primary and secondary walls, and therefore, the polymer cannot be definitely characterized as a primary cell-wall component. 

An elementary reaction is defined as a reaction that takes place as written in the reaction scheme. We will here distinguish between a truly elementary reaction, where the reaction takes place in isolation without any secondary collisions, and the traditional definition of an elementary reaction, where inelastic collisions among the molecules in the reaction scheme (or with container walls) can take place. 

The x-ray approach has few peers as regards nondestructive definition of structure at the secondary level. Although microscopy is more direct, the preparative problems and necessary subjectiveness in the interpretation of photo- and electron micrographs make absolutely necessary the joint use of the two techniques. The work of Preston and his school on the structural polysaccharides of plants is a good example of how the two techniques should be combined. A rough textural model of the molecular architecture of a cell wall of a plant is capable of quantitative and detailed definition by means of the complete, wide and small angle, x-ray scattering curve. This application is, perhaps, one of the potentially more fruitful, areas of future study it is part of the major, solid-state... 

Each trench has its own story. The historical evolution of the studied fault segment is hidden on the trench wall exposures. Even though there are some definite event structures for different fault types, all fault-related structures can be classified under two major titles (a) on-fault (primary) and (b) off-fault (secondary or indirect) structures (Fig. 7). On-fault structures are mostly preferred in trench studies, due to the ambiguous nature of off-fault structures. 

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