Fine wool

In fine wool such as that obtained from merino sheep, the cuticle is normally one cell thick (20 x 30 x 0.5 mm, approximate dimensions) and usually constitutes about 10% by weight of the total fiber. Sections of cuticle cells show an internal series of laminations (Figs. 1 and 2) comprising outer sulfur-rich bands known as the exocuticle and inner regions of lower sulfur content called the endocuticle (13). On the exposed surface of cuticle cells, a membrane-like proteinaceous band (epicuticle) and a unique hpid component form a hydrophobic resistant barrier (14). These hpid and protein components are the functional moieties of the fiber surface and are important in fiber protection and textile processing (15). 

Wool fibers have a very complex morphological stmcture. They can be considered as biological composite materials, in which the various regions are both chemically and physically different (87). Fine wool fibers contain two types of cell those of the internal cortex and those of the external cuticle. 

The term microfibers does not refer to new chemically distinct fibers, but rather to fibers that have smaller diameters. DuPont first introduced microfibers in 1989. Microfibers have diameters that are less than typical fibers they are half the diameter of fine silk fiber, quarter the diameter of fine wool, and a hundred times finer than human hair. Denier, the weight in grams of 9000 m of a fiber, is the term used to define the diameter or fineness of a fiber. While the definition for the thickness of microfibers is varied, a typical definition is that microfibers are 0.9 denier or less. For comparison, the nylon stocking is knit from 10-15 denier fiber. 

Wool is stained less at high temperatures and longer dyeing times because the disperse dye that was initially on the wool component migrates to the PES fiber. Carrier-free dyeable PES fibers should preferably be employed these fibers are easily dyeable even at boiling temperature (see Section 4.12.2). The nature of the wool also plays a role, fine wool and reclaimed wool being more strongly soiled. 

The warmth of a fine wool cap was rarely needed in the bland San Francisco climate, and wearing a cap there became rare, even among central European immigrants. Harry Ruben apprenticed himself as a carpenter, and his family survived on the wages he made as a carpenter and fi-om the occasional sale of a cap. Even before the depression, Harry Ruben was a poor man. With the onset of the depression, construction of houses almost completely ceased, and jobs for carpenters vanished. 

Many varieties of sheep have been bred to suit particular climates, or to yield particular types of products. Probably the most widely-cultivated variety is the Merino sheep, which is commonly raised for its fine wool, and is well suited to relatively dry climates. This variety is the most common sheep raised in Australia, which is the world s leading producer of sheep and their products. 

The yak Poephagus gninniens) is a eep-like animal that is kept as livestock on highland plateaus of the Himalayas of Asia. This animal is a source of an extremely fine wool, as well as hides, meat, and milk. The related musk ox Ovibos moschatus) is a minor species of livestock that is in the initial stages of domestication for its extremely light and fine wool and its gamey meat. 

A central stream of cells interspersed with vacuoles is termed the medulla, although this medullary cell-type is not present in all mammalian fibers. In fine wools and in human hairs, the medulla is usually absent it is more prevalent in coarser fibers [11]. The characteristic features of developing medullary cells in the follicle are circular, densely stained granules (medullary granules) that form internal coatings within the membranes of mature cells [159]. In the development of medullary cells, certain arginine residues are converted to citrulline, and isopeptide bonds [E--y(glutamyl)lysine] [160] are formed. 

TEM studies of thin transverse fiber sections show that the cortical structure of cashmere is considerably different from that of fine wool [296,311,320]. Australian and Chinese cash-mere fibers display both bilateral symmetry and random cell arrangements, not only in cashmere fibers from different samples but also in fibers from the same fleece [296,311], whereas fine wool fiber exhibits bilateral asymmetry only. The variation in cortical structure among fibers from the same cashmere fleece suggests that different mechanisms may be involved in fiber formation. Cashmere cortex is composed predominantly of ortholike and mesolike cells, whereas fine wool is composed predominantly of ortho- and paracortical cells arranged bilaterally. Because of the variations observed, many transverse sections need to be examined before definitive statements can be made about the physical structure of fiber from a given cashmere sample. 

The cortical cell distribution for a range of goat fibers is shown in Table 5.2. The comparable figures for fine wool are ortho (66-68%), para (28 32%), and meso (1-4%) [108]. 

The effect of traces of copper on oat-seedlings, grown in a copper-deficient medium, is shown in Fig. 11.4. Plainly, too little copper is bad for growth, and so is too much. Until recognized as such, copper-deficiency was the cause of many a crop failure in the reclaimed areas of Holland and Denmark. Copper-deficiency in farm animals leads to anaemia, demyelination of the spinal cord, and loss of pigmentation. Excess of copper storage in the liver of sheep leads to haemolysis and death. Sheep, fed on a diet deficient in copper, lose the crimp in their wool. Because it is the crimp that makes fine wool saleable, this causes economic loss to farmers (see Fig. 11.2). 

Chitosan in gel and sponge form was prepared to deliver ovalbumin (Maxwell et al. 2006a) and a plant toxin, heliotrine antigen (Maxwell et al. 2006b), to sheep via rectal and nasal routes. Approximately 12 month old fine-wool Merino wethers, raised on pasture, were vaccinated by means of three vaccinations at three-weekly intervals (days 0, 24, and 43). Significant IgGl and IgG2 responses in local mucosal (rectal) tissue and associated lymph nodes, jejunal Peyer s patch, and mesenteric lymph nodes, as well as IgA and IgE antibody levels were obtained in aU tissues. 

Wool is sold by weight thus, allowance for uptake of water must he made. A premium is paid for fine wools and because the diameter changes with regain, diameter measurements must be made under standard conditions of temperature and humidity. 

Scott and Roberts [4] also noted that they could estimate mean fiber diameter (MFD) from NIR data. This important parameter ranges from about 18 to 45 /rm or so. To a large extent, fiber diameter indicates the end use and fine wools command higher prices. Because grinding procedures are inappropriate for wool, the sensitivity of NIR spectra to particle size, normally seen as unfortunate and undesirable, becomes an exploitable property and gives an estimate of MFD. 

Fiber length (mm) 10-60 technical fiber 450-800 elementary fiber 10-40 fine wool 55-75 coarse wool 150-300 reel silk 300-1000 m schappe silk 50-250 m... 

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