Trees resistant

Silvicultural Treatments. Preventive silviculture should be practiced (16) to promote individual tree resistance to bark beetle attack by (1) favoring the most resistant species ... 

Stephen FM, Paine TD (1985) Seasonal patterns of host tree resistance to fungal associates of the southern pine beetle. Z Ang Ent 99 113-122... 

The responsible allergens belong to the class of sesquiterpenoid mansonones, of which mansonone A, a red ortho-quinone is the main (strong) sensitiser (Schulz et al. 1979). Interestingly, some of these quinones, e.g. mansonone E and F, occur in the elm species Ulmus hollandica)y making the tree resistant to the Dutch elm disease. 

Timber behaves better in compression and bending, the way in which trees resist their... 

Tests on Cable Constructions. The Association of Edison Illumination Companies (AEIC) has approved an accelerated cable hfe test in which typical underground distribution power cables can be statistically compared based on their resistance to water treeing (number of days to fail). The comparison can be made by varying the type of insulation and/or other cable layers in an environment that contains hot water (90°C) under 8V/fi (200 V/mil) voltage stresses (four times the typical power cables operating voltages). 

The first clues to the treatment of scurvy occurred in 1535—1536 when Jacques Cartier, on advice from Newfoundland Indians, fed his crew an extract from spmce tree needles to cure an epidemic. Various physicians were recommending the use of citms fmits to cure scurvy in the mid-sixteenth century. Two hundred years later, in 1753, it was proved by Dr. James Lind, in his famous clinical experiment, that scurvy was associated with diet and caused by lack of fresh vegetables. He also demonstrated that oranges and lemons were the most effective cure against this disease. In 1753, inM Treatise on the Scurvy[ Lind pubhshed his results and recommendations (7). Eorty-two years later, in 1795, the British Navy included lemon juice in seamen s diets, resulting in the familiar nickname "limeys" for British seamen. Evidence has shown that even with undefined scorbutic symptoms, vitamin C levels can be low, and can cause marked diminution in resistance to infections and slow healing of wounds. 

Just under the bark of a tree is a thin layer of cells, not visible to the naked eye, called the cambium. Here, cells divide and eventually differentiate to form bark tissue outside of the cambium and wood or xylem tissue iaside of the cambium. This newly formed wood on the iaside contains many living cells and conducts sap upward ia the tree, and hence, is called sapwood. Eventually, the inner sapwood cells become iaactive and are transformed iato heartwood. This transformation is often accompanied by the formation of extractives that darken the wood, make it less porous, and sometimes provide more resistance to decay. 

Extractives and Ash. The amount of extractives in wood varies from 5 to 20% by weight and includes a wide variety of organic chemicals (11). Many of these function as intermediates in tree metaboUsm as energy reserves or participate in the tree s defense mechanism against microbiological attack. The extractives contribute to wood properties such as color, odor, and decay resistance. 

Although rubber originally meant a natural thermoset material obtained from a rubber tree, with the development of plastics it identifies a thermoset elastomer (TSE) or thermoplastic elastomer (TPE) material. Different properties identify the elastomers such as strength and stiffness, abrasion resistance, solvent resistance, shock and... 

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