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Bismuth Heterocycles
Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs naturally, and its sulfide and oxide forms are important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery-white color when freshly produced. Surface oxidation generally gives samples of the metal a somewhat rosy cast. Further oxidation under heat can give bismuth a vividly iridescent appearance due to thin-film interference. Bismuth is both the most diamagnetic element and one of the least thermally conductive metals known. Bismuth was long considered the element with the highest atomic mass whose nuclei do not spontaneously decay. However, in 2003 it was discovered to be extremely weakly radioactive. The metal's only primordial isotope, bismuth-209, experiences alpha decay at such a minute rate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Element
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler substances by any chemical reaction. The number of protons in the nucleus is the defining property of an element, and is referred to as its atomic number (represented by the symbol ''Z'') – all atoms with the same atomic number are atoms of the same element. Almost all of the baryonic matter of the universe is composed of chemical elements (among rare exceptions are neutron stars). When different elements undergo chemical reactions, atoms are rearranged into new compounds held together by chemical bonds. Only a minority of elements, such as silver and gold, are found uncombined as relatively pure native element minerals. Nearly all other naturally occurring elements occur in the Earth as compounds or mixtures. Air is primarily a mixture o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha decay ( ), beta decay ( ), and gamma decay ( ), all of which involve emitting one or more particles. The weak force is the mechanism that is responsible for beta decay, while the other two are governed by the electromagnetism and nuclear force. A fourth type of common decay is electron capture, in which an unstable nucleus captures an inner electron from one of the electron shells. The loss of that electron from the shell results in a cascade of electrons dropping down to that lower shell resulting in emission of discrete X-rays from the transitions. A common example is iodine-125 commonly used in medical settings. Radioactive decay is a stochastic (i.e. random) process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
20th Century
The 20th (twentieth) century began on January 1, 1901 ( MCMI), and ended on December 31, 2000 ( MM). The 20th century was dominated by significant events that defined the modern era: Spanish flu pandemic, World War I and World War II, nuclear weapons, nuclear power and space exploration, nationalism and decolonization, technological advances, and the Cold War and post-Cold War conflicts. These reshaped the political and social structure of the globe. The 20th century saw a massive transformation of humanity's relationship with the natural world. Global population, sea level rise, and ecological collapses increased while competition for land and dwindling resources accelerated deforestation, water depletion, and the mass extinction of many of the world's species and decline in the population of others. Global heating increased the risk of extreme weather conditions. Additional themes include intergovernmental organizations and cultural homogenization through developments in em ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Remediation
Environmental remediation deals with the removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water. Remedial action is generally subject to an array of regulatory requirements, and may also be based on assessments of human health and ecological risks where no legislative standards exist, or where standards are advisory. Remediation standards In the United States, the most comprehensive set of Preliminary Remediation Goals (PRGs) is from the Environmental Protection Agency (EPA) ''Regional Screening Levels'' (RSLs). A set of standards used in Europe exists and is often called the Dutch standards. The European Union (EU) is rapidly moving towards Europe-wide standards, although most of the industrialised nations in Europe have their own standards at present. In Canada, most standards for remediation are set by the provinces individually, but the Canadian Council of Ministers of the Environment provides guidance at a federa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Poisoning
Lead poisoning, also known as plumbism and saturnism, is a type of metal poisoning caused by lead in the body. The brain is the most sensitive. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertility, and tingling in the hands and feet. It causes almost 10% of intellectual disability of otherwise unknown cause and can result in behavioral problems. Some of the effects are permanent. In severe cases, anemia, seizures, coma, or death may occur. Exposure to lead can occur by contaminated air, water, dust, food, or consumer products. Lead poisoning poses a significantly increased risk to children as they are far more likely to ingest lead indirectly by chewing on toys or other objects that are coated in lead paint. The amount of lead that can be absorbed by children is also higher than that of adults. Exposure at work is a common cause of lead poisoning in adults with certain occupations at particular risk. Diagnosis is typically by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell ( cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage. A central concept of toxicology is that the effects of a toxicant are dose-dependent; even water can lead to water intoxication when taken in too high a dose, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect. Toxicity is species-specific, making cross-species analysis problematic. Newer paradigms and metrics are evolving to bypas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diarrhea
Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin with loss of the normal stretchiness of the skin and irritable behaviour. This can progress to decreased urination, loss of skin color, a fast heart rate, and a decrease in responsiveness as it becomes more severe. Loose but non-watery stools in babies who are exclusively breastfed, however, are normal. The most common cause is an infection of the intestines due to either a virus, bacterium, or parasite—a condition also known as gastroenteritis. These infections are often acquired from food or water that has been contaminated by feces, or directly from another person who is infected. The three types of diarrhea are: short duration watery diarrhea, short duration bloody diarrhea, and persistent diarrhea (lasting more than two weeks, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth Subsalicylate
Bismuth subsalicylate, sold generically as pink bismuth and under the brand names Pepto-Bismol and BisBacter, is an antacid medication used to treat temporary discomforts of the stomach and gastrointestinal tract, such as nausea, heartburn, indigestion, upset stomach, and diarrhea. Bismuth subsalicylate has the empirical chemical formula of C7H5BiO4, and it is a colloidal substance obtained by hydrolysis of bismuth salicylate (Bi(C6H4(OH)CO2)3). Medical uses As a derivative of salicylic acid, bismuth subsalicylate displays anti-inflammatory and bactericidal action. It also acts as an antacid. Adverse effects There are some adverse effects. It can cause a black tongue and black stools in some users of the drug when it combines with trace amounts of sulfur in saliva and the colon to form bismuth sulfide. Bismuth sulfide is a highly insoluble black salt, and the discoloration seen is temporary and harmless. Long-term use (greater than six weeks) may lead to accumulation and tox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Latin
New Latin (also called Neo-Latin or Modern Latin) is the revival of Literary Latin used in original, scholarly, and scientific works since about 1500. Modern scholarly and technical nomenclature, such as in zoological and botanical taxonomy and international scientific vocabulary, draws extensively from New Latin vocabulary, often in the form of classical or neoclassical compounds. New Latin includes extensive new word formation. As a language for full expression in prose or poetry, however, it is often distinguished from its successor, Contemporary Latin. Extent Classicists use the term "Neo-Latin" to describe the Latin that developed in Renaissance Italy as a result of renewed interest in classical civilization in the 14th and 15th centuries. Neo-Latin also describes the use of the Latin language for any purpose, scientific or literary, during and after the Renaissance. The beginning of the period cannot be precisely identified; however, the spread of secular education, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
16th Century
The 16th century begins with the Julian year 1501 ( MDI) and ends with either the Julian or the Gregorian year 1600 ( MDC) (depending on the reckoning used; the Gregorian calendar introduced a lapse of 10 days in October 1582). The 16th century is regarded by historians as the century which saw the rise of Western civilization and the Islamic gunpowder empires. The Renaissance in Italy and Europe saw the emergence of important artists, authors and scientists, and led to the foundation of important subjects which include accounting and political science. Copernicus proposed the heliocentric universe, which was met with strong resistance, and Tycho Brahe refuted the theory of celestial spheres through observational measurement of the 1572 appearance of a Milky Way supernova. These events directly challenged the long-held notion of an immutable universe supported by Ptolemy and Aristotle, and led to major revolutions in astronomy and science. Galileo Galilei became a champion o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Age Of The Universe
In physical cosmology, the age of the universe is the time elapsed since the Big Bang. Astronomers have derived two different measurements of the age of the universe: a measurement based on direct observations of an early state of the universe, which indicate an age of billion years as interpreted with the Lambda-CDM concordance model as of 2018; and a measurement based on the observations of the local, modern universe, which suggest a younger age. The uncertainty of the first kind of measurement has been narrowed down to 20 million years, based on a number of studies which all show similar figures for the age and which include studies of the microwave background radiation by the ''Planck'' spacecraft, the Wilkinson Microwave Anisotropy Probe and other space probes. Measurements of the cosmic background radiation give the cooling time of the universe since the Big Bang, and measurements of the expansion rate of the universe can be used to calculate its approxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive. The term is also used more generally to characterize any type of exponential (or, rarely, non-exponential) decay. For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time. The original term, ''half-life period'', dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to ''half-life'' in the early 1950s. Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206. Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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