Bilateral structure

Kassenback, P., Incidence of Bilateral Structure of Cotton Fibers, in First International Symposium on Cotton Textile Research, Paris, 1969, p. 455. 

An important component of cuticle is 18 - methyl - eicosanoic acid [40]. Fatty acid is bound to a protein matrix, forming a layer in the epicuticle [41,42], and this layer is referred to as F - layer [43]. The F - layer can be removed by treatment with alcoholic alkaline chlorine solution in order to enhance wettability. The cuticle and epicuticle control the rate of diffusion of dyes and other molecules onto the fibre [44]. The cortex, however, controls the bulk properties of wool and has a bilateral structure composed of two types of cells referred to as ortho and para [45,46]. The cortical cells of both are enclosed by membranes of at least three distinct layers within which the microfibrils fit. Cells of intermediate appearance and reactivity designated meso - cortical have also been reported [47]. Cortical cells on the ortho side are denti-cuticle and thin, those on the para side are polygonal and thick [47]. Fig. 1-7 illustrates the bilateral structure which is responsible for the crimp of the... 

An alternative and more likely explanation considers the bilateral structure of some keratin fibers like wool. A helical fiber will arise if opposite halves of the fiber grow at different rates or if opposite halves contract to different extents during drying. This is analogous to the way a bilateral thermostat bends with changes in temperature. 

Early studies on the fine structure of specialty animal fibers involved differential staining using dyestuffs or heavy metals, and subsequent observations were made using light microscopy. By means of these techniques, vicuna fiber was shown to have a bilateral structure [318], and mohair fiber, predominantly ortho- with some paralike material [319] (see Sections 5.2.2 and 5.2.3). Bilateral structures are also observed when wool, cashmere, camel, and alpaca (but not mohair) are treated with sodium hydroxide and examined by means of polarized light [297]. 

Camel fibers from the same fleece can exhibit both bilateral and random cell arrangements. Similar observations have been made for yak fibers, which tend to consist mainly of ortho- and mesolike cells [296]. Vicuna and guanaco exhibit bilateral structure, whereas llama and alpaca do not [296]. 

Good bulk and crimp stability can be obtained with bicomponent fibers (also known as conjugated fibers, twin fibers, or fibers of bilateral structure). The two components may lie side by side, and have a nucleus-mantle structure or a matrix-fibrillar (M/F) structure (Figure 12-10). The M/F fibers are known as matrix fibers in the United States and not as bicom-... 

Based on the discussed example parameters that influence the turbulent mixing process, it is clear that plume structure can be described in general terms, but the specific characteristics are likely to be case dependent. Nevertheless, certain characteristics, such as those employed by the odor-gated rheotaxis with bilateral comparison strategy, may be similar enough to allow animals and engineered systems to track chemical plumes for a wide range of flow conditions. 

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