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Paul-Émile Lecoq De Boisbaudran
Paul-Émile Lecoq de Boisbaudran, also called François Lecoq de Boisbaudran (18 April 1838 – 28 May 1912), was a French chemist known for his discoveries of the chemical elements gallium, samarium and dysprosium. He developed methods for separation and purification of the rare earth elements and was one of the pioneers of the science of spectroscopy. Biography Lecoq de Boisbaudran was a member of a noble family of Huguenots from the French provinces of Poitou and Angoumois. The Huguenots were French Protestants, a population that was devastated during the French Wars of Religion (1561–1598). The Edict of Nantes (1598) granted substantial civil rights to the Huguenots even though it maintained Catholicism's position as the established religion of France. The Edict of Nantes was overturned by the Edict of Fontainebleau (1685), which officially sanctioned persecution of Protestants. The Lecoq de Boisbaudran family was of considerable fortune until the revocation of the Ed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cognac, France
Cognac (; Saintongese: ''Cougnat''; oc, Conhac ) is a commune in the Charente department, southwestern France. Administratively, the commune of Cognac is a subprefecture of the Charente department. Name The name is believed to be formed from individual masculine name -Connius, Gallic name, and the suffix -acum, which would correspond to the "domain of Connius". History The town of Cognac was unknown before the ninth century, when it was fortified. During the Hundred Years' War, the town continually changed sides, according to the tides of war. In 1526, it lent its name to the War of the League of Cognac, the military alliance established by King Francis I of France to fight against the House of Habsburg. As a benefit of the War League of Cognac, King Francis I granted to the town of Cognac the commercial right to participate in the salt trade conducted along the river, from which regional Cognac developed into a centre for the production of wine and brandy. In November 165 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Wars Of Religion
The French Wars of Religion is the term which is used in reference to a period of civil war between French Catholic Church, Catholics and Protestantism, Protestants, commonly called Huguenots, which lasted from 1562 to 1598. According to estimates, between two and four million people died from violence, famine or diseases which were directly caused by the conflict; additionally, the conflict severely damaged the power of the French monarchy. The fighting ended in 1598 when Henry of Navarre, who had converted to Catholicism in 1593, was proclaimed Henry IV of France and issued the Edict of Nantes, which granted substantial rights and freedoms to the Huguenots. However, the Catholics continued to have a hostile opinion of Protestants in general and they also continued to have a hostile opinion of him as a person, and his assassination in 1610 triggered a fresh round of Huguenot rebellions in the 1620s. Tensions between the two religions had been building since the 1530s, exacerba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. A regular octahedron is the dual polyhedron of a cube. It is a rectified tetrahedron. It is a square bipyramid in any of three orthogonal orientations. It is also a triangular antiprism in any of four orientations. An octahedron is the three-dimensional case of the more general concept of a cross polytope. A regular octahedron is a 3-ball in the Manhattan () metric. Regular octahedron Dimensions If the edge length of a regular octahedron is ''a'', the radius of a circumscribed sphere (one that touches the octahedron at all vertices) is :r_u = \frac a \approx 0.707 \cdot a and the radius of an inscribed sphere (tangent to each of the octahedron's faces) is :r_i = \frac a \approx 0.408\cdot a while the midradius, which t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anhydrous
A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achieve perfect dryness; anhydrous compounds gradually absorb water from the atmosphere so they must be stored carefully. Solids Many salts and solids can be dried using heat, or under vacuum. Desiccators can also be used to store reagents in dry conditions. Common desiccants include phosphorus pentoxide and silica gel. Chemists may also require dry glassware for sensitive reactions. This can be achieved by drying glassware in an oven, by flame, or under vacuum. Dry solids can be produced by freeze-drying, which is also known as lyophilization. Liquids or solvents In many cases, the presence of water can prevent a reaction from happening, or cause undesirable products to form. To prevent this, anhydrous solvents must be used when performi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt (chemistry)
In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively charged sodium ions and negatively charged chloride ions. The component ions in a salt compound can be either inorganic, such as chloride (Cl−), or organic, such as acetate (). Each ion can be either monatomic, such as fluoride (F−), or polyatomic, such as sulfate (). Types of salt Salts can be classified in a variety of ways. Salts that produce hydroxide ions when dissolved in water are called ''alkali salts'' and salts that produce hydrogen ions when dissolved in water are called ''acid salts''. ''Neutral salts'' are those salts that are neither acidic nor basic. Zwitterions contain an anionic and a cationic centre in the same molecule, but are not considered salts. Examples of zwitterions are amino acids, many metabolites, peptid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomorphism (crystallography)
In chemistry isomorphism has meanings both at the level of crystallography and at a molecular level. In crystallography, compounds are isomorphous if their symmetry is the same and their unit cell parameters are similar Molecules are isomorphous if they have similar shapes. The coordination complexes tris(acetylacetonato)iron (Fe(acac)3) and tris(acetylacetonato)aluminium (Al(acac)3) are isomorphous. These compounds, both of ''D''3 symmetry have very similar shapes, as determined by bond lengths and bond angles. Isomorphous compounds give rise to isomorphous crystals and form solid solutions. Historically, crystal shape was defined by measuring the angles between crystal faces with a goniometer. Whereas crystals of Fe(acac)3 are deep red and crystals of Al(acac)3 are colorless, a solid solution of the two, i.e. Fe1−xAlx(acac)3 will be deep or pale pink depending on the Fe/Al ratio, x. Double sulfates, such as Tutton's salt, with the generic formula MI2MII(SO4)2.6H2O, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersaturation
In physical chemistry, supersaturation occurs with a solution when the concentration of a solute exceeds the concentration specified by the value of solubility at equilibrium. Most commonly the term is applied to a solution of a solid in a liquid. A supersaturated solution is in a metastable state; it may be brought to equilibrium by forcing the excess of solute to separate from the solution. The term can also be applied to a mixture of gases. History Early studies of the phenomenon were conducted with sodium sulfate, also known as Glauber's Salt because, unusually, the solubility of this salt in water may decrease with increasing temperature. Early studies have been summarised by Tomlinson. It was shown that the crystallization of a supersaturated solution does not simply come from its agitation, (the previous belief) but from solid matter entering and acting as a "starting" site for crystals to form, now called "seeds". Expanding upon this, Gay-Lussac brought attention to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ankylosis
Ankylosis is a stiffness of a joint due to abnormal adhesion and rigidity of the bones of the joint, which may be the result of injury or disease. The rigidity may be complete or partial and may be due to inflammation of the tendinous or muscular structures outside the joint or of the tissues of the joint itself. When the structures outside the joint are affected, the term "false ankylosis" has been used in contradistinction to "true ankylosis", in which the disease is within the joint. When inflammation has caused the joint-ends of the bones to be fused together, the ankylosis is termed ''osseous'' or complete and is an instance of synostosis. Excision of a completely ankylosed shoulder or elbow may restore free mobility and usefulness to the limb. "Ankylosis" is also used as an anatomical term, bones being said to ankylose (or anchylose) when, from being originally distinct, they coalesce, or become so joined that no motion can take place between them. The term is from Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Laboratory
A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physicians' offices, clinics, hospitals, and regional and national referral centers. Overview The organisation and contents of laboratories are determined by the differing requirements of the specialists working within. A physics laboratory might contain a particle accelerator or vacuum chamber, while a metallurgy laboratory could have apparatus for casting or refining metals or for testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's laboratory might be a room with one-way mirrors and hidden cameras in which to observe behavior. In some laboratories, such as those commonly used by computer scientists, computers (sometimes supercomputers) are used for either simulations or the analysis of data. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autodidact
Autodidacticism (also autodidactism) or self-education (also self-learning and self-teaching) is education without the guidance of masters (such as teachers and professors) or institutions (such as schools). Generally, autodidacts are individuals who choose the subject they will study, their studying material, and the studying rhythm and time. Autodidacts may or may not have formal education, and their study may be either a complement or an alternative to formal education. Many notable contributions have been made by autodidacts. Etymology The term has its roots in the Ancient Greek words (, ) and (, ). The related term ''didacticism'' defines an artistic philosophy of education. Terminology Various terms are used to describe self-education. One such is heutagogy, coined in 2000 by Stewart Hase and Chris Kenyon of Southern Cross University in Australia; others are ''self-directed learning'' and ''self-determined learning''. In the heutagogy paradigm, a learner should be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
École Polytechnique , a Japanese video-games developer/publisher
{{disambiguation, geo ...
École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoie, a French commune * École-Valentin, a French commune in the Doubs département * Grandes écoles, higher education establishments in France * The École, a French-American bilingual school in New York City Ecole may refer to: * Ecole Software This is a list of Notability, notable video game companies that have made games for either computers (like PC or Mac), video game consoles, handheld or mobile devices, and includes companies that currently exist as well as now-defunct companies. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edict Of Fontainebleau
The Edict of Fontainebleau (22 October 1685) was an edict issued by French King Louis XIV and is also known as the Revocation of the Edict of Nantes. The Edict of Nantes (1598) had granted Huguenots the right to practice their religion without state persecution. Protestants had lost their independence in places of refuge under Cardinal Richelieu on account of their supposed insubordination, but they continued to live in comparative security and political contentment. From the outset, religious toleration in France had been a royal, rather than popular, policy. The lack of universal adherence to his religion did not sit well with Louis XIV's vision of perfected autocracy.Palmer, ''eo. loc.'' Edict of Nantes The Edict of Nantes had been issued on 13 April 1598 by Henry IV of France and granted the Calvinist Protestants of France, also known as Huguenots, substantial rights in the predominantly-Catholic state. Henry aimed at promoting civil unity by the edict. The edict treated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
