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Tree stump, about 37 years after falling. After a tree has been cut and has fallen, the stump or tree stump is usually a small remaining portion of the trunk with the roots still in the ground. Stumps may show the age-defining rings of a tree. The study of these rings is known as dendrochronology. Stump sculpture by German artist Eberhard Bosslet
Chemical nomenclature, replete as it is with compounds with very complex names, is a repository for some names that may be considered unusual. A browse through the Physical Constants of Organic Compounds in the CRC Handbook of Chemistry and Physics (a fundamental resource) will reveal not just the whimsical work of chemists, but the sometimes peculiar compound names that occur as the ...
2,4-Dichlorophenoxyacetic acid is an organic compound with the chemical formula Cl 2 C 6 H 3 OCH 2 CO 2 H.It is usually referred to by its ISO common name 2,4-D. [4] It is a systemic herbicide that kills most broadleaf weeds by causing uncontrolled growth, but most grasses such as cereals, lawn turf, and grassland are relatively unaffected.
Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula K N O 3. It is a potassium salt of nitric acid. This salt consists of potassium cations K + and nitrate anions NO − 3, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter (or nitre outside the US). [5]
Preventive cultural practices—Selecting varieties best for local growing conditions and maintaining healthy crops is the first line of defense. Plant quarantine and 'cultural techniques' such as crop sanitation are next, e.g., removal of diseased plants, and cleaning pruning shears to prevent spread of infections.
The stump is the base of the trunk and the attached woody roots. Tree stumps and roots are extracted using a hydraulic head on a tracked excavator or with a mechanical head equipped by a special tool for tractors. Stump harvesting is expected to provide an increasing component of the woody material required by the woody biomass power sector in ...
Pyrolysis of lignin from gymnosperms gives more guaiacol, resulting from removal of the propenyl group of coniferyl alcohol. These lignins are said to have a high guaiacyl (or G) content. In contrast, lignins derived from sinapyl alcohol affords syringol. A high syringyl (or S) content is indicative of lignin from angiosperms. [10]
The physical properties of any material are determined by its chemical structure. Wood contains an abundance of chemical groups called free hydroxyls. Free hydroxyl groups readily absorb and release water according to changes in the climatic conditions to which they are exposed. This is the main reason why wood's dimensional stability is ...