Anaerobic digestion is a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to manage waste and/or to produce fuels. Much of the fermentation used industrially to produce food and drink products, as well as home fermentation, uses anaerobic digestion. Silage is produced by anaerobic digestion.
The digestion process begins with bacterial hydrolysis of the input materials. Insoluble organic polymers, such as carbohydrates, are broken down to soluble derivatives that become available for other bacteria. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. These bacteria convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Finally, methanogens convert these products to methane and carbon dioxide. The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments.
Substance theory, or substance attribute theory, is an ontological theory about objecthood,
Substance is a key concept in ontology and metaphysics, which may be classified into monist, dualist or pluralist varieties according to how many substances or individuals are said to populate, furnish or exist in the world. According to Monistic views, such as those of stoicism and Spinoza, there is only one substance, pneuma or God, respectively. These modes of thinking are sometimes associated with the idea of immanence. Dualism sees the world as being composed of two fundamental substances, for example, the Cartesian substance dualism of mind and matter. Pluralist philosophies include Plato's Theory of Forms and Aristotle's hylomorphic categories.
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. It can be solid, liquid, gas, or plasma.
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, simple or seemingly pure substances found in nature can in fact be mixtures of chemical substances. For example, tap water may contain small amounts of dissolved sodium chloride and compounds containing iron, calcium and many other chemical substances.
The Convention on Psychotropic Substances of 1971 is a United Nations treaty designed to control psychoactive drugs such as amphetamines, barbiturates, benzodiazepines, and psychedelics signed in Vienna, Austria on 21 February 1971. The Single Convention on Narcotic Drugs of 1961 could not ban the many newly discovered psychotropics, since its scope was limited to drugs with cannabis, coca, and opium-like effects.
During the 1960s such drugs became widely available, and government authorities opposed this for numerous reasons, arguing that along with negative health effects, drug use led to lowered moral standards. The Convention, which contains import and export restrictions and other rules aimed at limiting drug use to scientific and medical purposes, came into force on 16 August 1976. As of 2013, 183 states are Parties to the treaty. Many laws have been passed to implement the Convention, including the U.S. Psychotropic Substances Act, the UK Misuse of Drugs Act 1971, and the Canadian Controlled Drugs and Substances Act. Adolf Lande, under the direction of the United Nations Office of Legal Affairs, prepared the Commentary on the Convention on Psychotropic Substances. The Commentary, published in 1976, is an invaluable aid to interpreting the treaty and constitutes a key part of its legislative history.