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Chemexper Chemical Directory catalogue chemicals CASno Structure SMILES "ChemExper". Chemxpert Database Chemxpert Chemical Database small molecules database buyers,suppliers "ChemxpertDB". 10,00000 Chemical Book East West University: commercially available compounds CASno, suppliers, properties "Chemical Book". 200,000 Chemical Register
Age and origin of the source material determine the chemical structure of humic substances. In general, humic substances derived from soil and peat (which takes hundreds to thousands of years to form) have higher molecular weight, higher amounts of O and N, more carbohydrate units, and fewer polyaromatic units than humic substances derived from ...
Expansive clay, also called expansive soil, is a clay soil prone to large volume changes (swelling and shrinking) directly related to changes in water content. [1] Soils with a high content of expansive minerals can form deep cracks in drier seasons or years; such soils are called vertisols.
chemical file format An MDL Molfile is a file format for holding information about the atoms, bonds, connectivity and coordinates of a molecule. The molfile consists of some header information, the Connection Table (CT) containing atom info, then bond connections and types, followed by sections for more complex information.
Most research on anthropogenic soils describes specific aspects of their biology, chemistry or physical properties, cultural heritage and human geography, erosion, wastes, pollution, fertilizer management, and taxonomy. Very few of them, [3] [4] [5] try to answer to the question: How fast do they start pedogenesis (viz., differentiating horizons)?
Due to the physical and chemical properties of some clays [4] (such as the Lias Group) large swelling occurs when water is absorbed. Conversely when the water dries up these clays contract (shrink). The presence of these clay minerals is what allows soils to have the capacity to shrink and swell.
An anthrosol (or anthropogenic soil) in the World Reference Base for Soil Resources (WRB) [1] is a type of soil that has been formed or heavily modified due to long-term human activity, such as from irrigation, addition of organic waste or wet-field cultivation used to create paddy fields.