Wood constitutents

On a worldwide basis, wood constitutes an enormous, renewable raw material resource (biomass) for production of energy and chemical products. In connection with wood-processing industries large amounts of both solid residues and dissolved material remain as waste. A rational utilization of this organic waste is of utmost importance not only from the pollution point of view, but also because of the necessity of finding substitutes for products based on petroleum and other fossile raw materials, all expensive and limited in supply. 

In the period of World War I, Weizman found that by use of a special strain of bacillus the fermentation of corn gave a mixture of acetone (3 parts), n-butyl alcohol (6 parts), and ethyl alcohol (1 part). Destructive distillation of wood constituted the third major source of solvents in this period the products consisted of methyl alcohol, acetone, and acetic acid. 

Decay is not due to the chemical action of the Boil or to the fermentation of the sap, but is the result of the action of certain low forms of plant life called fungi. These consist for the most part, of very fine thread-like filaments, collectively called mycelium, which penetrate the wood in all directions. Certain substances in the wood constitute the food of the fungi. As these substances are dissolved the structure is broken down, until the wood reaches the condition commonly known as rotten. 

Waterlogged woods constitute a major fraction of all preserved samples. This predominance probably is seen both because wood degradation rates are slower in water than on land and because natural environments other than sediments are usually ephemeral over long time periods. Woods that have been recovered from water ideally would be discussed separately from those that have been preserved subaerially. This is because woods from these two different environments are subject to contrasting types of microbial degradation and spontaneous reactions with ambient chemical agents. 

Aucuparin (22 a) was first isolated from the heartwood of mountain ash (Sorbus aucuparia, Rosaceae) where it co-occurs with methoxyaucuparin (22 b). They constitute up to 1% (dry-weight) of the wood (39, 40, 83). Their structures have been firmly established by syntheses (83). The compounds have later been found to be common wood constitutents of many Sorbus spp. (H. Erdtman, T. Norin, E. von Rudloff, unpublished results). 4-Hydroxyaucuparin (22 c) has been isolated from S. aucuparia. Chromatographic studies have shown that this compound is also present in many other Sorbus spp. (B. Kimland, T. Norin, unpublished results). 

Besides the patterns described above, other modelling approaches have also been put forward, but their discussion exceeds the scope of this chapter. For example, Rector and Welty (2005) provide five different modeUing patterns, while the modelling of ISO 15926 uses property chains for modelling part-whole relations. While several modelhng solutions are proposed, it is also important to avoid confusing part-whole relations with other relations. Rector and Welty (2005) mention typical confusions with relations such as containment, membership, connections, constituents and subClassOf. For example, constituency refers to a relation without a clear part of relationship (e.g., different types of wood constitute a table) and special ODPs are offered for modelling constituency. ... 

In hardwoods, morphological structural elements in longitudinal series comprise the segmented structure termed vessel . Vessels, which are exposed in transverse section, constitute about 10-46% of the stem volume in deciduous hardwoods and are cells of relatively large diameters (50-300 p.m). Vessels have in short the appearance of open vertical tubes within the wood structure because their end walls have partially dissolved. By comparison, the hardwood vessel diameter can be as much a 10 times the diameter of a softwood fiber. 

Laminated beams (glulam), parallam (or LSL) and fingerjoints a flat pressed multilayer wood beam, thiek wood planks constituting the layers, used for structural exterior applications and bonded with PRF (phenol-resorcinol-formaldehyde) cold-setting resins, or MUF cold-setting resins, or even with certain types of polurethanes (although the use of these latter ones is only established in one country and can show creep and temperature-induced creep problems). The indi-... 

Where resorcinol adhesives are not suitable, resins can be prepared from modified resorcinol [128], Characteristic of these types of resins arc those used for tyre cord adhesives, in which a pure resorcinol-formaldehyde resin is used, or alternatively, alkyl resorcinol or oil-soluble resins suitable for rubber compounding are obtained by prereaction of resorcinol with fatty acids in the presence of sulfuric acid at high temperature followed by reaction with formaldehyde. Worldwide more than 90% of resorcinol adhesives are used as cold-setting wood adhesives. The other most notable application is as tyre cord adhesives, which constitutes less than 5% of the total use. 

Smoke - Smoke constitutes fine, solid, gasbome matters that are products of incomplete combustion of organics (wood, coal, tobacco). Smoke particles are extremely small, ranging in size from less than 0.01 /im to 1 /im. 

In addition to cedrol and pseudocedrol, cedar-wood oil contains a third alcohol, of the formula Cj5H. 40, which has been named cedrenol. This alcohol was isolated by Semmler and Mayer, who found it to exist to the extent of about 3 per cent, in the oil. It is a tricyclic unsaturated alcohol, closely related in constitution to the sesquiterpene cedrene, as shown hy the following formulae —... 

It was first artificially prepared by Tiemann from the glucoside coni-ferin, which occurs in the cambium of various coniferous woods. The constitution of vanUlin is that of methyl protocatechuic aldehyde—... 

Acetylated polysaccharides form part of the structure of wood, the acetyl radical constituting some 2-5Vo by weight of the dry wood. Hydrolysis to free acetic acid occurs in the presence of moisture at a rate varying from one species to another a wood of lower acetyl content can liberate acetic acid much faster under given conditions than another wood of higher content Small quantities of formic, propionic and butyric acids are also formed but their effects can be neglected in comparison with those of acetic acid. There is a broad, but only a broad, correlation between the corrosivity of a wood and its acidity. The chemistry of acetyl linkage in wood and of its hydrolysis has been examined in some detail. ... 

Xylan-type polysaccharides are the main hemicellulose components of secondary cell walls constituting about 20-30% of the biomass of dicotyl plants (hardwoods and herbaceous plants). In some tissues of monocotyl plants (grasses and cereals) xylans occur up to 50% [6j. Xylans are thus available in huge and replenishable amoimts as by-products from forestry, the agriculture, wood, and pulp and paper industries. Nowadays, xylans of some seaweed represent a novel biopolymer resource [4j. The diversity and complexity of xylans suggest that many useful by-products can be potentially produced and, therefore, these polysaccharides are considered as possible biopolymer raw materials for various exploitations. As a renewable resource, xylans are... 

Yee DC, JA Maynard, TK Wood (1998) Rhizoremediation of trichloroethyelene by a recombinant, root-colonizing Pseudomonas fluorescens strain expressing ort/jo-monooxygenase constitutively. Appl Environ Microbiol 64 112-118. 

More than 4,000 years old, traditional Chinese medicine continues to be widely practiced in China and in western countries. Traditional Chinese medicine teaches that good health is the result of harmony and balance between five basic elements earth, water, fire, wood and metal. Also important to health are the two types of energy Yin and Yang, constituting a vital substance that circulates through the body. Drug therapy has been one of the means used in Chinese medicine to keep these elements and the flow of energy in balance. Many of the same herbs used thousands of years ago in China could be the source of new pharmaceuticals in Western medicine... 

The greatest use of latex paints for indoor applications is based upon vinyl acetate, which constitutes 85% of the total polymer usage, the remainder being acrylates (e.g., n-butyl acrylate). For outdoors or bathroom usage, acrylates are the major components. For various applications, e.g., wood paints, styrene copolymerised with acrylates are used. Flowever, yellowing of the styrene units occurs. 

Populations of bats in Europe have been declining, and PCBs together with pesticides and wood preservatives are the suspected main causes of the decline (Fernandez et al. 1993). Three species of bats collected in Spain in 1988 to 1990 contained only a few dominant PCB congeners PCBs 138, 153, and 180 accounted for about 80% of the total PCB burden in whole bats (Fernandez et al. 1993). But the most abundant PCB congeners in brain and liver of European otters (Lutra) were in the descending order of PCBs 163, 153, 138, and 170, each constituting at least 10% of the total PCB burden (Mason and Ratford 1994). 

Heating of houses with wood, charcoal or mazut also results in formation of trace amounts of dioxins. Hazardous source of PCDD and PCDF constitutes the combustion of engine oil and gasoline with chlorine- or bromine-organic additives. Over the long period of time, pesticides containing dioxins (2,4,5-T, copper trichlorophenolate etc.) [4] were used in agriculture. 

Figure 4.9 Possible mineralogical constitution of Jingdezhen porcelain bodies. Average composition of four types of raw material are marked (Pa, Pk, Ka, Kk), and the approximate compositions of Chinese porcelains from four periods 1 = predominantly 10th to 12th Century AD 2 = 12th to 13th Century AD 3 = predominantly 14th Century AD 4 = post-17th Century AD. (From Pollard and Wood, 1986 Figure 10.7, with permission of Smithsonian Institution Scholarly Press.)...

In softwoods, the main cell type is the tracheid, which is often mistakenly referred to as a fibre. Tracheids constitute over 90% of the volume of most softwoods, and are the principal paper-making cells of softwoods. Their average length is usually between 2 and 4 mm, with a lengthrwidth ratio (aspect ratio) often in excess of 100 to 1, but there is a wide distribution of tracheid lengths, and it is possible for some to be as short as 1 mm and for others to be as long as 5 mm (Table 2.1). The lumen, or central cavity, is several times wider than the cell wall thickness. There is also a difference between spring wood (i.e. cells synthesised in the early part of the annual... 

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