265 relations: A Greek–English Lexicon, Adsorption, Alloy, Alpha particle, American Scientist, Ampere, Ampere balance, Antoine Lavoisier, Arthur E. Kennelly, Atmosphere (unit), Atomic clock, Atomic mass, Australia, Austria, Avogadro constant, Avoirdupois system, Becquerel, Belgium, Bell jar, Benzene, Bismuth, Boule (crystal), Brazil, British National Corpus, Caffeine, Canada, Candela, Carbon-12, Cast iron, Catalysis, Celsius, Centimetre, Centimetre–gram–second system of units, Chamois leather, Charles Maurice de Talleyrand-Périgord, China, Chirp, Clipping (morphology), Corpus of Contemporary American English, Coulomb, Credit card, Czech Republic, Czochralski process, Denmark, Density, Diamagnetism, Diamond turning, Dimensionless physical constant, Distilled water, Egypt, ..., Electric potential, Electric power, Electrical resistance and conductance, Electrical resistivity and conductivity, Electronvolt, Elementary charge, Energy, Ethanol, Ether, Farad, Federal Register, Ferme générale, Finland, Foot (unit), Force, France, French Academy of Sciences, French language, French Republican Calendar, French Revolution, Gaithersburg, Maryland, Gal (unit), Galvanic series, General Conference on Weights and Measures, Geochronology, Geoponica, Germany, Giovanni Fabbroni, Giovanni Giorgi, Gold, Grain (unit), Gram, Grave (unit), Gravimeter, Gravimetry, Gravitational field, Gravity of Earth, Gray (unit), Greenhouse gas, Half-life, Hardness, Heat capacity, Helium–neon laser, Henry (unit), Hertz, Hong Kong, Hungary, Hydrocarbon, Hydrogen, Imperial units, India, Indonesia, Inertia, Interferometry, International Bureau of Weights and Measures, International Committee for Weights and Measures, International Electrotechnical Commission, International Organization of Legal Metrology, International System of Units, Ion, Iridium, Isotope, Isotope separation, Isotopes of bismuth, Isotopes of gold, Isotopes of thorium, Israel, Italy, James Clerk Maxwell, Japan, Johnson Matthey, Joint Commission, Josephson effect, Joule, Katal, Kazakhstan, Kelvin, Kenya, Kibble balance, Kilogram-force, Koine Greek, Krypton, Lead, Litre, Louis Lefèvre‑Gineau, Lumen (unit), Lux, Magnetic hysteresis, Magnetic susceptibility, Mass, Mass spectrometry, Mass versus weight, Mercury (element), Meridian (geography), Metre, Metre Convention, Metre per second squared, Metric prefix, Metric system, Metrologia, Metrology, Mexico, Micro-g environment, Milligram per cent, Millimetre, MKS system of units, Mole (unit), Mononuclidic element, National Convention, National Institute of Standards and Technology, National Measurement and Regulation Office, National Measurement Institute, Australia, National Physical Laboratory (United Kingdom), National Research Council (Canada), Netherlands, Newcastle University, Newton (unit), Noble metal, North Korea, Norway, Nucleocosmochronology, Nuclide, Obol (coin), Office of Public Sector Information, Ohm, Osmium, Ounce, Oxford English Dictionary, Pakistan, Parts-per notation, Pascal (unit), Pavillon de Breteuil, Photon, Planck constant, Platinum, Poland, Portugal, Pound (mass), Power (physics), Pressure, Primary standard, Properties of water, Pyrophoricity, Quantum Hall effect, Quartz, Radian, Radioactive decay, Redox, Reign of Terror, Remmius Palaemon, René Just Haüy, Romania, Russia, Saint-Cloud, Sèvres, Second, Semiconductor, Serbia, SI base unit, Siemens (unit), Sievert, Significand, Silicon, Silicon dioxide, Silicon monoxide, Singapore, Slovakia, Slug (unit), South Africa, South Korea, Spain, Speed of light, Sputtering, Standard deviation, Standard gravity, Steam cleaning, Steradian, Stoichiometry, Superconductivity, Sweden, Switzerland, Table of nuclides (combined), Taiwan, Tesla (unit), Thailand, The Caravan, The Economist, Thermal conductivity, Thorium, Titanium nitride, Tonne, Torr, Traceability, Turkey, Uncertainty, United Kingdom, United States, United States Congress, United States customary units, United States Department of Commerce, Units of measurement in France, Units of measurement in France before the French Revolution, Vienna Standard Mean Ocean Water, Volatile organic compound, Volt, Watt, Wave interference, Weber (unit), Weighing scale, Weight, Weights and Measures Acts (UK), X-ray interferometer, X-ray photoelectron spectroscopy, 1795 in science, 1799 in science. Expand index (215 more) » « Shrink index
A Greek–English Lexicon, often referred to as Liddell & Scott, Liddell–Scott–Jones, or LSJ, is a standard lexicographical work of the Ancient Greek language.
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface.
An alloy is a combination of metals or of a metal and another element.
Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus.
American Scientist (informally abbreviated AmSci) is an American bimonthly science and technology magazine published since 1913 by Sigma Xi, The Scientific Research Society.
The ampere (symbol: A), often shortened to "amp",SI supports only the use of symbols and deprecates the use of abbreviations for units.
The ampere balance (also current balance or Kelvin balance) is an electromechanical apparatus used for the precise measurement of the SI unit of electric current, the ampere.
Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution;; 26 August 17438 May 1794) CNRS (Centre National de la Recherche Scientifique) was a French nobleman and chemist who was central to the 18th-century chemical revolution and who had a large influence on both the history of chemistry and the history of biology.
Arthur Edwin Kennelly (December 17, 1861 – June 18, 1939), was an Irish-American electrical engineer.
The standard atmosphere (symbol: atm) is a unit of pressure defined as.
An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.
The atomic mass (ma) is the mass of an atom.
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands.
Austria (Österreich), officially the Republic of Austria (Republik Österreich), is a federal republic and a landlocked country of over 8.8 million people in Central Europe.
In chemistry and physics, the Avogadro constant (named after scientist Amedeo Avogadro) is the number of constituent particles, usually atoms or molecules, that are contained in the amount of substance given by one mole.
The avoirdupois system (abbreviated avdp) is a measurement system of weights which uses pounds and ounces as units.
The becquerel (symbol: Bq) is the SI derived unit of radioactivity.
Belgium, officially the Kingdom of Belgium, is a country in Western Europe bordered by France, the Netherlands, Germany and Luxembourg.
A bell jar is a glass jar, similar in shape to a bell, and can be manufactured from a variety of materials (ranging from glass to different types of metals).
Benzene is an important organic chemical compound with the chemical formula C6H6.
Bismuth is a chemical element with symbol Bi and atomic number 83.
A boule is a single crystal ingot produced by synthetic means.
Brazil (Brasil), officially the Federative Republic of Brazil (República Federativa do Brasil), is the largest country in both South America and Latin America.
The British National Corpus (BNC) is a 100-million-word text corpus of samples of written and spoken English from a wide range of sources.
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class.
Canada is a country located in the northern part of North America.
The candela (or; symbol: cd) is the base unit of luminous intensity in the International System of Units (SI); that is, luminous power per unit solid angle emitted by a point light source in a particular direction.
Carbon-12 is the more abundant of the two stable isotopes of carbon (Carbon-13 being the other), amounting to 98.93% of the element carbon; its abundance is due to the triple-alpha process by which it is created in stars.
Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%.
Catalysis is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalysthttp://goldbook.iupac.org/C00876.html, which is not consumed in the catalyzed reaction and can continue to act repeatedly.
The Celsius scale, previously known as the centigrade scale, is a temperature scale used by the International System of Units (SI).
A centimetre (international spelling as used by the International Bureau of Weights and Measures; symbol cm) or centimeter (American spelling) is a unit of length in the metric system, equal to one hundredth of a metre, centi being the SI prefix for a factor of.
The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time.
Chamois leather is a type of porous leather, traditionally the skin of the chamois (Rupicapra rupicapra), a type of European mountain goat but today it is made almost exclusively from the flesh split of a sheepskin.
Charles Maurice de Talleyrand-Périgord (2 February 1754 – 17 May 1838), 1st Prince of Benevento, then 1st Prince of Talleyrand, was a laicized French bishop, politician, and diplomat.
China, officially the People's Republic of China (PRC), is a unitary one-party sovereign state in East Asia and the world's most populous country, with a population of around /1e9 round 3 billion.
A chirp is a signal in which the frequency increases (up-chirp) or decreases (down-chirp) with time.
In linguistics, clipping is the word formation process which consists in the reduction of a word to one of its parts (Marchand: 1969).
The Corpus of Contemporary American English (COCA) is 450-million-word corpus of American English.
The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge.
A credit card is a payment card issued to users (cardholders) to enable the cardholder to pay a merchant for goods and services based on the cardholder's promise to the card issuer to pay them for the amounts so paid plus the other agreed charges.
The Czech Republic (Česká republika), also known by its short-form name Czechia (Česko), is a landlocked country in Central Europe bordered by Germany to the west, Austria to the south, Slovakia to the east and Poland to the northeast.
The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors (e.g. silicon, germanium and gallium arsenide), metals (e.g. palladium, platinum, silver, gold), salts and synthetic gemstones.
Denmark (Danmark), officially the Kingdom of Denmark,Kongeriget Danmark,.
The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume.
Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force.
Diamond turning is turning with diamond as the cutting tool.
In physics, a dimensionless physical constant, sometimes called a fundamental physical constant, is a physical constant that is dimensionless.
Distilled water is water that has been boiled into steam and condensed back into liquid in a separate container.
Egypt (مِصر, مَصر, Khēmi), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia by a land bridge formed by the Sinai Peninsula.
An electric potential (also called the electric field potential, potential drop or the electrostatic potential) is the amount of work needed to move a unit positive charge from a reference point to a specific point inside the field without producing any acceleration.
Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit.
The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor.
Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is a fundamental property that quantifies how strongly a given material opposes the flow of electric current.
In physics, the electronvolt (symbol eV, also written electron-volt and electron volt) is a unit of energy equal to approximately joules (symbol J).
The elementary charge, usually denoted as or sometimes, is the electric charge carried by a single proton, or equivalently, the magnitude of the electric charge carried by a single electron, which has charge.
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
Ethanol, also called alcohol, ethyl alcohol, grain alcohol, and drinking alcohol, is a chemical compound, a simple alcohol with the chemical formula.
Ethers are a class of organic compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups.
The farad (symbol: F) is the SI derived unit of electrical capacitance, the ability of a body to store an electrical charge.
The Federal Register (FR or sometimes Fed. Reg.) is the official journal of the federal government of the United States that contains government agency rules, proposed rules, and public notices.
The ferme générale ("general farm") was, in ancien régime France, essentially an outsourced customs, excise and indirect tax operation.
Finland (Suomi; Finland), officially the Republic of Finland is a country in Northern Europe bordering the Baltic Sea, Gulf of Bothnia, and Gulf of Finland, between Norway to the north, Sweden to the northwest, and Russia to the east.
The foot (feet; abbreviation: ft; symbol: ′, the prime symbol) is a unit of length in the imperial and US customary systems of measurement.
In physics, a force is any interaction that, when unopposed, will change the motion of an object.
France, officially the French Republic (République française), is a sovereign state whose territory consists of metropolitan France in Western Europe, as well as several overseas regions and territories.
The French Academy of Sciences (French: Académie des sciences) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research.
French (le français or la langue française) is a Romance language of the Indo-European family.
The French Republican Calendar (calendrier républicain français), also commonly called the French Revolutionary Calendar (calendrier révolutionnaire français), was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871.
The French Revolution (Révolution française) was a period of far-reaching social and political upheaval in France and its colonies that lasted from 1789 until 1799.
Gaithersburg, officially the City of Gaithersburg, is a city in Montgomery County, Maryland.
The gal (symbol: Gal), sometimes called galileo after Galileo Galilei, is a unit of acceleration used extensively in the science of gravimetry.
The galvanic series (or electropotential series) determines the nobility of metals and semi-metals.
The General Conference on Weights and Measures (Conférence générale des poids et mesures – CGPM) is the supreme authority of the International Bureau of Weights and Measures (Bureau international des poids et mesures – BIPM), the inter-governmental organization established in 1875 under the terms of the Metre Convention (Convention du Mètre) through which Member States act together on matters related to measurement science and measurement standards.
Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves.
The Geoponica (also spelled Geoponika) is a twenty-book collection of agricultural lore, compiled during the 10th century in Constantinople for the Byzantine emperor Constantine VII Porphyrogenitus.
Germany (Deutschland), officially the Federal Republic of Germany (Bundesrepublik Deutschland), is a sovereign state in central-western Europe.
Giovanni Valentino Mattia Fabbroni (13 February 1752 – 17 December 1822) was an Italian naturalist, economist, agronomist and chemist.
Giovanni Giorgi (27 November 1871 – 19 August 1950) was an Italian physicist and electrical engineer who proposed the Giorgi system of measurement, the precursor to the International System of Units (SI).
Gold is a chemical element with symbol Au (from aurum) and atomic number 79, making it one of the higher atomic number elements that occur naturally.
A grain is a unit of measurement of mass, and in the troy weight, avoirdupois, and Apothecaries' system, equal to exactly.
The gram (alternative spelling: gramme; SI unit symbol: g) (Latin gramma, from Greek γράμμα, grámma) is a metric system unit of mass.
The grave was the original name of the kilogram, in an early version of the metric system between 1793 and 1795.
A gravimeter is an instrument used to measure gravitational acceleration.
Gravimetry is the measurement of the strength of a gravitational field.
In physics, a gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body.
The gravity of Earth, which is denoted by, refers to the acceleration that is imparted to objects due to the distribution of mass within Earth.
The gray (symbol: Gy) is a derived unit of ionizing radiation dose in the International System of Units (SI).
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range.
Half-life (symbol t1⁄2) is the time required for a quantity to reduce to half its initial value.
Hardness is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion.
Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to (or removed from) an object to the resulting temperature change.
A helium–neon laser or HeNe laser, is a type of gas laser whose gain medium consists of a mixture of 85% helium and 15% neon inside of a small electrical discharge.
The henry (symbol: H) is the SI derived unit of electrical inductance.
The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second.
Hong Kong (Chinese: 香港), officially the Hong Kong Special Administrative Region of the People's Republic of China, is an autonomous territory of China on the eastern side of the Pearl River estuary in East Asia.
Hungary (Magyarország) is a country in Central Europe that covers an area of in the Carpathian Basin, bordered by Slovakia to the north, Ukraine to the northeast, Austria to the northwest, Romania to the east, Serbia to the south, Croatia to the southwest, and Slovenia to the west.
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon.
Hydrogen is a chemical element with symbol H and atomic number 1.
The system of imperial units or the imperial system (also known as British Imperial or Exchequer Standards of 1825) is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced.
India (IAST), also called the Republic of India (IAST), is a country in South Asia.
Indonesia (or; Indonesian), officially the Republic of Indonesia (Republik Indonesia), is a transcontinental unitary sovereign state located mainly in Southeast Asia, with some territories in Oceania.
Inertia is the resistance of any physical object to any change in its position and state of motion.
Interferometry is a family of techniques in which waves, usually electromagnetic waves, are superimposed causing the phenomenon of interference in order to extract information.
The International Bureau of Weights and Measures (Bureau international des poids et mesures) is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.
The International Committee for Weights and Measures (abbreviated CIPM from the French Comité international des poids et mesures) consists of eighteen persons, each of a different nationality, from Member States of the Metre Convention (Convention du Mètre) appointed by the General Conference on Weights and Measures (CGPM) whose principal task is to promote worldwide uniformity in units of measurement by taking direct action or by submitting proposals to the CGPM.
The International Electrotechnical Commission (IEC; in French: Commission électrotechnique internationale) is an international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology".
The International Organization of Legal Metrology (Organisation Internationale de Métrologie Légale - OIML), is an intergovernmental organization, created in 1955 and based in Paris, to promote the global harmonization of the legal metrology procedures that underpin and facilitate international trade.
The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.
An ion is an atom or molecule that has a non-zero net electrical charge (its total number of electrons is not equal to its total number of protons).
Iridium is a chemical element with symbol Ir and atomic number 77.
Isotopes are variants of a particular chemical element which differ in neutron number.
Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes.
Bismuth (83Bi) has no stable isotopes, but does have one very long-lived isotope; thus, the standard atomic weight can be given as.
Gold (79Au) has one stable isotope, 197Au, and 36 radioisotopes, with 195Au being the most stable with a half-life of 186 days.
Although thorium (90Th) has 6 naturally occurring isotopes, none of these isotopes are stable; however, one isotope, 232Th, is relatively stable, with a half-life of 1.405×1010 years, considerably longer than the age of the Earth, and even slightly longer than the generally accepted age of the universe.
Israel, officially the State of Israel, is a country in the Middle East, on the southeastern shore of the Mediterranean Sea and the northern shore of the Red Sea.
Italy (Italia), officially the Italian Republic (Repubblica Italiana), is a sovereign state in Europe.
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish scientist in the field of mathematical physics.
Japan (日本; Nippon or Nihon; formally 日本国 or Nihon-koku, lit. "State of Japan") is a sovereign island country in East Asia.
Johnson Matthey is a British multinational speciality chemicals and sustainable technologies company headquartered in the United Kingdom.
The Joint Commission is a United States-based nonprofit tax-exempt 501(c) organization that accredits more than 21,000 US health care organizations and programs.
The Josephson effect is the phenomenon of supercurrent—i.e. a current that flows indefinitely long without any voltage applied—across a device known as a Josephson junction (JJ), which consists of two superconductors coupled by a weak link.
The joule (symbol: J) is a derived unit of energy in the International System of Units.
The katal (symbol: kat) is the SI unit of catalytic activity.
Kazakhstan (Qazaqstan,; kəzɐxˈstan), officially the Republic of Kazakhstan (Qazaqstan Respýblıkasy; Respublika Kazakhstan), is the world's largest landlocked country, and the ninth largest in the world, with an area of.
The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics.
Kenya, officially the Republic of Kenya, is a country in Africa with its capital and largest city in Nairobi.
A Kibble balance (previously watt balance) is an electromechanical weight measuring instrument that measures the weight of a test object very precisely by the strength of an electric current and a voltage.
The kilogram-force (kgf or kgF), or kilopond (kp, from Latin pondus meaning weight), is a gravitational metric unit of force.
Krypton (from translit "the hidden one") is a chemical element with symbol Kr and atomic number 36.
Lead is a chemical element with symbol Pb (from the Latin plumbum) and atomic number 82.
The litre (SI spelling) or liter (American spelling) (symbols L or l, sometimes abbreviated ltr) is an SI accepted metric system unit of volume equal to 1 cubic decimetre (dm3), 1,000 cubic centimetres (cm3) or 1/1,000 cubic metre. A cubic decimetre (or litre) occupies a volume of 10 cm×10 cm×10 cm (see figure) and is thus equal to one-thousandth of a cubic metre. The original French metric system used the litre as a base unit. The word litre is derived from an older French unit, the litron, whose name came from Greek — where it was a unit of weight, not volume — via Latin, and which equalled approximately 0.831 litres. The litre was also used in several subsequent versions of the metric system and is accepted for use with the SI,, p. 124. ("Days" and "hours" are examples of other non-SI units that SI accepts.) although not an SI unit — the SI unit of volume is the cubic metre (m3). The spelling used by the International Bureau of Weights and Measures is "litre", a spelling which is shared by almost all English-speaking countries. The spelling "liter" is predominantly used in American English. One litre of liquid water has a mass of almost exactly one kilogram, because the kilogram was originally defined in 1795 as the mass of one cubic decimetre of water at the temperature of melting ice. Subsequent redefinitions of the metre and kilogram mean that this relationship is no longer exact.
Louis Lefèvre-Gineau (7 March 1751 – 3 February 1829), born at Authe (Ardennes), was a French chemist and scientist.
The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total quantity of visible light emitted by a source.
The lux (symbol: lx) is the SI derived unit of illuminance and luminous emittance, measuring luminous flux per unit area.
Magnetic hysteresis occurs when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles align themselves with it.
In electromagnetism, the magnetic susceptibility (Latin: susceptibilis, "receptive"; denoted) is one measure of the magnetic properties of a material.
Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.
Mass spectrometry (MS) is an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio.
In common usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities.
Mercury is a chemical element with symbol Hg and atomic number 80.
A (geographical) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude.
The metre (British spelling and BIPM spelling) or meter (American spelling) (from the French unit mètre, from the Greek noun μέτρον, "measure") is the base unit of length in some metric systems, including the International System of Units (SI).
The Metre Convention (Convention du Mètre), also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations (Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Turkey, United States of America, and Venezuela).
The metre per second squared is the unit of acceleration in the International System of Units (SI).
A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit.
The metric system is an internationally adopted decimal system of measurement.
Metrologia is an international journal dealing with the scientific aspects of metrology.
Metrology is the science of measurement.
Mexico (México; Mēxihco), officially called the United Mexican States (Estados Unidos Mexicanos) is a federal republic in the southern portion of North America.
The term micro-g environment (also µg, often referred to by the term microgravity) is more or less a synonym for weightlessness and zero-g, but indicates that g-forces are not quite zero—just very small.
Milligram per cent is a traditional symbol used to denote a unit of measure of concentration.
The millimetre (International spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length.
The MKS system of units is a physical system of units that expresses any given measurement using base units of the metre, kilogram, and/or second (MKS).
The mole, symbol mol, is the SI unit of amount of substance.
A mononuclidic element or monotopic element is one of the 22 chemical elements that is found naturally on Earth essentially as a single nuclide (which may, or may not, be a stable nuclide).
The National Convention (Convention nationale) was the first government of the French Revolution, following the two-year National Constituent Assembly and the one-year Legislative Assembly.
The National Institute of Standards and Technology (NIST) is one of the oldest physical science laboratories in the United States.
The National Measurement and Regulation Office (NMRO) was an executive agency of the UK Government's Department for Business, Innovation and Skills (BIS).
The National Measurement Institute (NMI) is Australia's peak measurement body responsible for biological, chemical, legal and physical measurement and is currently administered within the Australian Government's Department of Industry.
The National Physical Laboratory (NPL) is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington, London, England.
The National Research Council (NRC, Conseil national de recherches Canada) is the primary national research and technology organization (RTO) of the Government of Canada, in science and technology research and development.
The Netherlands (Nederland), often referred to as Holland, is a country located mostly in Western Europe with a population of seventeen million.
Newcastle University (officially, the University of Newcastle upon Tyne) is a public research university in Newcastle upon Tyne in the North-East of England.
The newton (symbol: N) is the International System of Units (SI) derived unit of force.
In chemistry, the noble metals are metals that are resistant to corrosion and oxidation in moist air (unlike most base metals).
North Korea (Chosŏn'gŭl:조선; Hanja:朝鮮; Chosŏn), officially the Democratic People's Republic of Korea (abbreviated as DPRK, PRK, DPR Korea, or Korea DPR), is a country in East Asia constituting the northern part of the Korean Peninsula.
Norway (Norwegian: (Bokmål) or (Nynorsk); Norga), officially the Kingdom of Norway, is a unitary sovereign state whose territory comprises the western portion of the Scandinavian Peninsula plus the remote island of Jan Mayen and the archipelago of Svalbard.
Nucleocosmochronology or nuclear cosmochronology is a technique used to determine timescales for astrophysical objects and events.
A nuclide (from nucleus, also known as nuclear species) is an atomic species characterized by the specific constitution of its nucleus, i.e., by its number of protons Z, its number of neutrons N, and its nuclear energy state.
The obol (ὀβολός, obolos, also ὀβελός (obelós), ὀβελλός (obellós), ὀδελός (odelós). "nail, metal spit"; obolus) was a form of ancient Greek currency and weight.
The Office of Public Sector Information (OPSI) is the body responsible for the operation of Her Majesty's Stationery Office (HMSO) and of other public information services of the United Kingdom.
The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Simon Ohm.
Osmium (from Greek ὀσμή osme, "smell") is a chemical element with symbol Os and atomic number 76.
The ounce (abbreviated oz; apothecary symbol: ℥) is a unit of mass, weight, or volume used in most British derived customary systems of measurement.
The Oxford English Dictionary (OED) is the main historical dictionary of the English language, published by the Oxford University Press.
Pakistan (پاکِستان), officially the Islamic Republic of Pakistan (اِسلامی جمہوریہ پاکِستان), is a country in South Asia.
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction.
The pascal (symbol: Pa) is the SI derived unit of pressure used to quantify internal pressure, stress, Young's modulus and ultimate tensile strength.
Pavillon de Breteuil is a building located in Saint-Cloud, France near Paris.
The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles).
The Planck constant (denoted, also called Planck's constant) is a physical constant that is the quantum of action, central in quantum mechanics.
Platinum is a chemical element with symbol Pt and atomic number 78.
Poland (Polska), officially the Republic of Poland (Rzeczpospolita Polska), is a country located in Central Europe.
Portugal, officially the Portuguese Republic (República Portuguesa),In recognized minority languages of Portugal: Portugal is the oldest state in the Iberian Peninsula and one of the oldest in Europe, its territory having been continuously settled, invaded and fought over since prehistoric times.
The pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement.
In physics, power is the rate of doing work, the amount of energy transferred per unit time.
Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.
A primary standard in metrology is a standard that is sufficiently accurate such that it is not calibrated by or subordinate to other standards.
Water is a polar inorganic compound that is at room temperature a tasteless and odorless liquid, which is nearly colorless apart from an inherent hint of blue. It is by far the most studied chemical compound and is described as the "universal solvent" and the "solvent of life". It is the most abundant substance on Earth and the only common substance to exist as a solid, liquid, and gas on Earth's surface. It is also the third most abundant molecule in the universe. Water molecules form hydrogen bonds with each other and are strongly polar. This polarity allows it to separate ions in salts and strongly bond to other polar substances such as alcohols and acids, thus dissolving them. Its hydrogen bonding causes its many unique properties, such as having a solid form less dense than its liquid form, a relatively high boiling point of 100 °C for its molar mass, and a high heat capacity. Water is amphoteric, meaning that it is both an acid and a base—it produces + and - ions by self-ionization.
A pyrophoric substance (from Greek πυροφόρος, pyrophoros, "fire-bearing") ignites spontaneously in air at or below 55 °C (130 °F).
The quantum Hall effect (or integer quantum Hall effect) is a quantum-mechanical version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall conductance undergoes quantum Hall transitions to take on the quantized values where is the channel current, is the Hall voltage, is the elementary charge and is Planck's constant.
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2.
The radian (SI symbol rad) is the SI unit for measuring angles, and is the standard unit of angular measure used in many areas of mathematics.
Radioactive decay (also known as nuclear decay or radioactivity) is the process by which an unstable atomic nucleus loses energy (in terms of mass in its rest frame) by emitting radiation, such as an alpha particle, beta particle with neutrino or only a neutrino in the case of electron capture, gamma ray, or electron in the case of internal conversion.
Redox (short for reduction–oxidation reaction) (pronunciation: or) is a chemical reaction in which the oxidation states of atoms are changed.
The Reign of Terror, or The Terror (la Terreur), is the label given by some historians to a period during the French Revolution after the First French Republic was established.
Quintus Remmius Palaemon or Quintus Rhemnius Fannius Palaemon.
René Just Haüy FRS MWS FRSE (28 February 1743 – 3 June 1822) was a French priest and mineralogist, commonly styled the Abbé Haüy after he was made an honorary canon of Notre Dame.
Romania (România) is a sovereign state located at the crossroads of Central, Eastern, and Southeastern Europe.
Russia (rɐˈsʲijə), officially the Russian Federation (p), is a country in Eurasia. At, Russia is the largest country in the world by area, covering more than one-eighth of the Earth's inhabited land area, and the ninth most populous, with over 144 million people as of December 2017, excluding Crimea. About 77% of the population live in the western, European part of the country. Russia's capital Moscow is one of the largest cities in the world; other major cities include Saint Petersburg, Novosibirsk, Yekaterinburg and Nizhny Novgorod. Extending across the entirety of Northern Asia and much of Eastern Europe, Russia spans eleven time zones and incorporates a wide range of environments and landforms. From northwest to southeast, Russia shares land borders with Norway, Finland, Estonia, Latvia, Lithuania and Poland (both with Kaliningrad Oblast), Belarus, Ukraine, Georgia, Azerbaijan, Kazakhstan, China, Mongolia and North Korea. It shares maritime borders with Japan by the Sea of Okhotsk and the U.S. state of Alaska across the Bering Strait. The East Slavs emerged as a recognizable group in Europe between the 3rd and 8th centuries AD. Founded and ruled by a Varangian warrior elite and their descendants, the medieval state of Rus arose in the 9th century. In 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus' ultimately disintegrated into a number of smaller states; most of the Rus' lands were overrun by the Mongol invasion and became tributaries of the nomadic Golden Horde in the 13th century. The Grand Duchy of Moscow gradually reunified the surrounding Russian principalities, achieved independence from the Golden Horde. By the 18th century, the nation had greatly expanded through conquest, annexation, and exploration to become the Russian Empire, which was the third largest empire in history, stretching from Poland on the west to Alaska on the east. Following the Russian Revolution, the Russian Soviet Federative Socialist Republic became the largest and leading constituent of the Union of Soviet Socialist Republics, the world's first constitutionally socialist state. The Soviet Union played a decisive role in the Allied victory in World War II, and emerged as a recognized superpower and rival to the United States during the Cold War. The Soviet era saw some of the most significant technological achievements of the 20th century, including the world's first human-made satellite and the launching of the first humans in space. By the end of 1990, the Soviet Union had the world's second largest economy, largest standing military in the world and the largest stockpile of weapons of mass destruction. Following the dissolution of the Soviet Union in 1991, twelve independent republics emerged from the USSR: Russia, Ukraine, Belarus, Kazakhstan, Uzbekistan, Armenia, Azerbaijan, Georgia, Kyrgyzstan, Moldova, Tajikistan, Turkmenistan and the Baltic states regained independence: Estonia, Latvia, Lithuania; the Russian SFSR reconstituted itself as the Russian Federation and is recognized as the continuing legal personality and a successor of the Soviet Union. It is governed as a federal semi-presidential republic. The Russian economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it one of the leading producers of oil and natural gas globally. The country is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction. Russia is a great power as well as a regional power and has been characterised as a potential superpower. It is a permanent member of the United Nations Security Council and an active global partner of ASEAN, as well as a member of the G20, the Shanghai Cooperation Organisation (SCO), the Council of Europe, the Asia-Pacific Economic Cooperation (APEC), the Organization for Security and Co-operation in Europe (OSCE), and the World Trade Organization (WTO), as well as being the leading member of the Commonwealth of Independent States (CIS), the Collective Security Treaty Organization (CSTO) and one of the five members of the Eurasian Economic Union (EEU), along with Armenia, Belarus, Kazakhstan and Kyrgyzstan.
Saint-Cloud is a commune in the western suburbs of Paris, France.
Sèvres is a commune in the southwestern suburbs of Paris, France.
The second is the SI base unit of time, commonly understood and historically defined as 1/86,400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each.
A semiconductor material has an electrical conductivity value falling between that of a conductor – such as copper, gold etc.
Serbia (Србија / Srbija),Pannonian Rusyn: Сербия; Szerbia; Albanian and Romanian: Serbia; Slovak and Czech: Srbsko,; Сърбия.
The International System of Units (SI) defines seven units of measure as a basic set from which all other SI units can be derived.
The siemens (symbol: S) is the derived unit of electric conductance, electric susceptance and electric admittance in the International System of Units (SI).
The sievert (symbol: SvNot be confused with the sverdrup or the svedberg, two non-SI units that sometimes use the same symbol.) is a derived unit of ionizing radiation dose in the International System of Units (SI) and is a measure of the health effect of low levels of ionizing radiation on the human body.
The significand (also mantissa or coefficient) is part of a number in scientific notation or a floating-point number, consisting of its significant digits.
Silicon is a chemical element with symbol Si and atomic number 14.
Silicon dioxide, also known as silica (from the Latin silex), is an oxide of silicon with the chemical formula, most commonly found in nature as quartz and in various living organisms.
Silicon monoxide is the chemical compound with the formula SiO where silicon is present in the oxidation state +2.
Singapore, officially the Republic of Singapore, is a sovereign city-state and island country in Southeast Asia.
Slovakia (Slovensko), officially the Slovak Republic (Slovenská republika), is a landlocked country in Central Europe.
The slug is a derived unit of mass in the weight-based system of measures, most notably within the British Imperial measurement system and in the United States customary measures system.
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa.
South Korea, officially the Republic of Korea (대한민국; Hanja: 大韓民國; Daehan Minguk,; lit. "The Great Country of the Han People"), is a country in East Asia, constituting the southern part of the Korean Peninsula and lying east to the Asian mainland.
Spain (España), officially the Kingdom of Spain (Reino de España), is a sovereign state mostly located on the Iberian Peninsula in Europe.
The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.
Sputtering is a process whereby particles are ejected from a solid target material due to bombardment of the target by energetic particles, particularly gas ions in a laboratory.
In statistics, the standard deviation (SD, also represented by the Greek letter sigma σ or the Latin letter s) is a measure that is used to quantify the amount of variation or dispersion of a set of data values.
The standard acceleration due to gravity (or standard acceleration of free fall), sometimes abbreviated as standard gravity, usually denoted by or, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth.
Steam cleaning involves using steam for cleaning.
Stoichiometry is the calculation of reactants and products in chemical reactions.
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic flux fields occurring in certain materials, called superconductors, when cooled below a characteristic critical temperature.
Sweden (Sverige), officially the Kingdom of Sweden (Swedish), is a Scandinavian country in Northern Europe.
Switzerland, officially the Swiss Confederation, is a sovereign state in Europe.
The various tables below (scroll down) show the known isotopes of the chemical elements.
Taiwan, officially the Republic of China (ROC), is a state in East Asia.
The tesla (symbol T) is a derived unit of magnetic flux density (informally, magnetic field strength) in the International System of Units.
Thailand, officially the Kingdom of Thailand and formerly known as Siam, is a unitary state at the center of the Southeast Asian Indochinese peninsula composed of 76 provinces.
The Caravan is an Indian English-language, long-form narrative journalism magazine covering politics and culture.
The Economist is an English-language weekly magazine-format newspaper owned by the Economist Group and edited at offices in London.
Thermal conductivity (often denoted k, λ, or κ) is the property of a material to conduct heat.
Thorium is a weakly radioactive metallic chemical element with symbol Th and atomic number 90.
Titanium nitride (sometimes known as tinite) is an extremely hard ceramic material, often used as a coating on titanium alloys, steel, carbide, and aluminium components to improve the substrate's surface properties.
The tonne (Non-SI unit, symbol: t), commonly referred to as the metric ton in the United States, is a non-SI metric unit of mass equal to 1,000 kilograms;.
The torr (symbol: Torr) is a unit of pressure based on an absolute scale, now defined as exactly of a standard atmosphere (101.325 kPa).
Traceability is the capability to trace something.
Turkey (Türkiye), officially the Republic of Turkey (Türkiye Cumhuriyeti), is a transcontinental country in Eurasia, mainly in Anatolia in Western Asia, with a smaller portion on the Balkan peninsula in Southeast Europe.
Uncertainty has been called "an unintelligible expression without a straightforward description".
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed with some organisations, including the and preferring to use Britain as shorthand for Great Britain is a sovereign country in western Europe.
The United States of America (USA), commonly known as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major self-governing territories, and various possessions.
The United States Congress is the bicameral legislature of the Federal government of the United States.
United States customary units are a system of measurements commonly used in the United States.
The United States Department of Commerce is the Cabinet department of the United States government concerned with promoting economic growth.
region of southeastern France France has a unique history of units of measurement due to radical attempts to adopt a metric system following the French Revolution.
Woodcut dated 1800 illustrating the new decimal units which became the legal norm across all France on 4 November 1800 Before the French Revolution, which started in 1789, French units of measurement were based on the Carolingian system, introduced by the first Holy Roman Emperor Charlemagne which in turn were based on ancient Roman measures.
Vienna Standard Mean Ocean Water (VSMOW) is a water standard defining the isotopic composition of fresh water.
Volatile organic compounds (VOCs) are organic chemicals that have a high vapor pressure at ordinary room temperature.
The volt (symbol: V) is the derived unit for electric potential, electric potential difference (voltage), and electromotive force.
The watt (symbol: W) is a unit of power.
In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude.
In physics, the weber (symbol: Wb) is the SI unit of magnetic flux.
Weighing scales (or weigh scales or scales) are devices to measure weight.
In science and engineering, the weight of an object is related to the amount of force acting on the object, either due to gravity or to a reaction force that holds it in place.
Weights and measures acts are acts of the British Parliament determining the regulation of weights and measures.
An X-ray interferometer is analogous to a neutron interferometer.
X-ray photoelectron spectroscopy (XPS) is a surface-sensitive quantitative spectroscopic technique that measures the elemental composition at the parts per thousand range, empirical formula, chemical state and electronic state of the elements that exist within a material.
The year 1795 in science and technology involved some significant events.
The year 1799 in science and technology involved many significant events, listed below.
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