The Proposed Compression Algorithm

The subject of wood chemistry or phytochemistry has developed in recent years as a distinct discipline. It is concerned with the enormous variety of organic substance that are elaborated and accumulated by woods and deals with chemical structures of these substances.

Phytochemistry in the strict sense of the word is the study of phytochemicals. Many of these are known to provide protection against insect attacks and plant diseases. They also exhibit a number of protective functions for human consumers. (Will, 1960). The medicinal value of wood extracts lies in their chemical substances that produce a definite physiological action on the human body. Therefore, there is a need to evaluate the timbers for nutrient and chemical compositions so as to determine the potential of the indigenous sources of medicine. Nigeria is rich in rare and useful woods from which important drugs could be prepared, which may serve as starting materials for the partial synthesis of some useful drugs (Agbor et al., 2004).The chemical content of a wood qualifies it for use in the pharmaceutical industries. There is a strong relationship between the properties of wood and the properties of the particular tree that yielded it. For every tree species, there is a range of density for the wood it yields. Therefore, it

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is a rough correlation between density of a wood and its strength (mechanical properties). For example, mahogany is a medium-dense hardwood which is excellent for fine furniture crafting.

Wood in the strict sense is yielded by trees, which increases in diameter by the formation, between the existing wood and the inner bark, of new woody layers which envelop the entire stem, living branches and roots. Wood has been utilized by humans since antiquity. They provided a source of many products required by early humans such as food, medicine, fuel and tools. For example, the bark of the willow trees, when chewed, was used as a painkiller in early Greece and was the precursor of the present – day aspirin. Throughout history different types of wood have served many purposes. The tough, strong, and durable white oak, for example, was a well-proven raw material for ships, bridges, cooperage, barn timbers, farm implements, rail road ties, fence posts, flooring, paneling and other products. In contrast, wood such as black walnut and cherry became primarily cabinets woods. Hickory was manufactured in tough, hard, resilient tool handles. Black walnut was used for barn timbers and tree nails. It is know that wood from trees grown in certain locations was stronger, more durable and more easily worked with tools than wood from the same species grown in other locations.

Modern wood quality research has substantiated that location and growth conditions significantly affect wood properties. In the United States more than 100 kinds of wood are available to the prospective user; but it is very unlikely that all are available in any one locality.

About 30 wood types are commonly imported in the form of logs, cants, lumber and veneer for industrial uses, the building trade and crafts. The importance of wood as a raw material supplying fiber, energy, and chemicals is similar in magnitude to its use as a solid material.

Lumber, plywood, and reconstituted boards consume about one-half of the timber harvest, usage for fibre, chemicals and fuels accounts for the remaining half. In 1990, over 55 million metric tons of pulp fiber for paper making was derived from the forest. In January 2010, Italian scientists announced that wood could be harnessed to become a bone substitute. But it is likely to take at least five years until this technique will be applied for humans. As scientists and engineers further learn and develop new techniques to extract various components from woods, or alternatively to modify wood, for example by adding components to woods. Further developments include new lignin glue applications, recyclable, food packaging, rubber tire replacement applications, anti-bacterial medical agents, and high strength fabric or composites.

Although the relative value of wood as source of energy and chemicals has varied considerably through decades, wood continues to be an important sources of specialty

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chemicals and renewable energy and may be even more important in the future (Riegal, 2005).A study by Canadian Wood Council compared the cycle impacts of three homes designed primarily with wood, steel and concrete, over the first 20 years of their life spans.

Relative to the wood design, the steel and concrete designs realize more heat or air pollution, produced more solid used more resources, require more energy emitted more green houses gases and discharge more water pollution (Riegel, 2005). When the complete life cycle is considered, including use and disposal, the great majority of the studies indicate that wood products have lower greenhouse gas emission. In the case where wood products cause greater green house gas emission than their non-wood counter parts, the cause was inappropriate post use disposal (Riegel 2005).

Wood structure is complex. The grain orientation is based on location of annular rings and can be defined as end-, edge and face grain. Wood fibers possess capillary properties and a high water-retention capacity. Kampelmacher et al., (1971), pointed out the heterogeneous structures of wood. Conductive tubules (xylem) and fibres are arranged alternatively in more or less dense arrays (annular rings). Typically, moisture conductivity is greatest from an end-grain surface, less from edge grain, and even less from face grain. According to Kampelmacher et al.

(1971), a chopping block with fibres perpendicular to the surface (end-grain) can allow for bacterial penetration several centimeters into the wood. In the studies of (Riegal, 2005) low recoveries of bacteria from laboratory contaminated wooden boards brought about questions on whether the disappearance of the bacteria meant their non-viability due to drying out or because of antibacterial properties of wood, or whether the possibility that their inaccessibility once entrapped into the wood structure was due to the sampling technique. Park & Cliver (1996), developed an innovative sampling method that made use of the capillary properties of the fibres to detect bacteria inside the wood. Unfortunately, they did not use this perfusion method to evaluate the viability of bacteria following a normal cleaning procedure, but rather to assess the use of microwave heating to kill the entrapped bacteria, which they succeeded.

Abrishami et al. (1994) showed that 88% of the cells inoculated onto dry, new wood adhered to it after 10 minutes. In fact, it was seen by scanning electron microscopy (SEM) that many bacteria were associated with the cytoplasmic regions of dried structural and vegetative elements of the xylem tissue. On the contrary, previously conditioned wood (wet), whether new or used, did not absorb the inoculums very well as the bacterial recovery was high. Moreover, Abrishami et al., (1994). demonstrated by a direct viable count-SEM method that about 75% of the cells adhering to the wood structure (new or used) were viable for up to 2 hours following

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inoculation. Based on microcosm assay on wood dust/chips and plastic pieces, they concluded these materials to have no beneficial or deleterious effect on the viability of bacterial cells, despite a noticeable reduction (31%) of cells when incubated with wood chips. The antibacterial properties of wood have therefore been questioned. Miller et al. (1996) tested 8 wood species and found that the aqueous ash extract was inhibitory to E. coli 0157:H7. Red oak and cherry extracts had a slight inhibitory activity. However, Riegal, (2005) also reported the inhibitory properties of wood, but concluded that due to extreme washing during the experiments as well as failure to extract an aqueous active compound, these properties were not due to water-soluble compounds. The findings of Galluzzo & Cliver (1996)agreed with those of Riegal (2005) as oak leachates were not bactericidal towards Salmonella enteritidis, in contrast to the oak shavings and chips tested. Even various solvent extractions were conducted on the wood, but the antibacterial effect was not diminished. A similar antibacterial effect was seen with filter paper. Their results therefore indicated that the mechanism of disappearance of Salmonella from oak was rather physical than chemical. In fact, it could be a combination of adhesion and drying effect on the cells. Carried out work on wood with pyrolysis of wood. The energy capacity of dry wood, which include both sensible heat and decomposition heat effect was measured using a differential scanning calorimeter technique. In this work the decomposition heat effect show good correlation with thermo gravimetric data obtained in the study. The work on the rate of heat and smoke characteristic of wood in Ohio State University calorimeter was done by Hao (1988). Here plywood and red oak were tested for heat change and smoke release rate under different sheet flux levels polluted and unpolluted conditions and vertical and horizontal orientation. Heat and smoke release data obtained by the method were reported. The heat release rate by thermal method are constantly lower than that by oxygen. In summary the major product from combustion of wood are CO, CO₂, and H₂O while minor or secondary products include methanol from methoxyl group of lignin and acetate acid from acetyl side-chain on hemicelluloses.