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Barium Chromate
Barium chromate, is a yellow sand like powder with the formula BaCrO4. It is a known oxidizing agent and produces a green flame when heated, a result of the barium ions. History The first naturally occurring barium chromate was found in the country of Jordan. The brown crystals found perched on host rocks were named hashemite in honor of the Hashemite Kingdom of Jordan. The hashemite crystals range in color from light yellowish-brown to a darker greenish-brown and are usually less than 1mm in length. The hashemite crystals are not composed of pure barium chromate but instead contain some small sulfur content as well. The different crystals contain a range of sulfur impurities ranging from the more pure dark crystals, Ba1.00(Cr0.93, S0.07)1.00O4, to the less pure light crystals, Ba1.00(Cr0.64, S0.36)1.00O4. Hashemite was found to be an isostructural chromate analog of baryte, BaSO4. Preparation and reactions It can be synthesized by reacting barium hydroxide or barium chloride wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hashemite (mineral)
Hashemite is a very rare barium Chromate ion, chromate mineral with the formula Ba(Cr,S)O4.Hauff, P.L., Foord, E.E., and Rosenblum, S., 1983. Hashemite, Ba(Cr,S)O4, a new mineral from Jordan. American Mineralogist 68, 1223-1225. It is a representative of natural chromates - a relatively small and rare group of minerals. Hashemite is the barium-analogue of tarapacáite. It is also the chromium-analogue of baryte, and belongs to the baryte group of minerals. Hashemite is stoichiometrically similar to crocoite and chromatite. Hashemite is orthorhombic, with space group ''Pnma''. I was found together with chromium-bearing ettringite and an apatite group mineral in the Hatrurim Formation, known for the occurrence of rocks formed due to natural pyrometamorphism. Hashemite is named after the Hashemite Kingdom of Jordan. References Chromate minerals Barium minerals Orthorhombic minerals Baryte group {{mineral-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre-Auguste Renoir
Pierre-Auguste Renoir (; ; 25 February 1841 – 3 December 1919) was a French people, French artist who was a leading painter in the development of the Impressionism, Impressionist style. As a celebrator of beauty and especially femininity, feminine sensuality, it has been said that "Renoir is the final representative of a tradition which runs directly from Peter Paul Rubens, Rubens to Antoine Watteau, Watteau." He was the father of actor Pierre Renoir (1885–1952), filmmaker Jean Renoir (1894–1979) and ceramic artist Claude Renoir (1901–1969). He was the grandfather of the filmmaker Claude Renoir (1913–1993), son of Pierre. Life Youth Pierre-Auguste Renoir was born in Limoges, Haute-Vienne, France, in 1841. His father, Léonard Renoir, was a tailor of modest means, so, in 1844, Renoir's family moved to Paris in search of more favorable prospects. The location of their home, in rue d'Argenteuil in central Paris, placed Renoir in proximity to the Louvre. Although the yo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromates
Chromate salts contain the chromate anion, . Dichromate salts contain the dichromate anion, . They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromate ions can be interconvertible. Chemical properties Potassium-chromate-sample.jpg, Potassium chromate Potassium-dichromate-sample.jpg, Potassium dichromate Chromates react with hydrogen peroxide, giving products in which peroxide, , replaces one or more oxygen atoms. In acid solution the unstable blue peroxo complex Chromium(VI) oxide peroxide, , is formed; it is an uncharged covalent molecule, which may be extracted into ether. Addition of pyridine results in the formation of the more stable complex . Acid–base properties In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium. : The predominance diagram shows that the position of the equilibrium depends on both pH and the analytical concentration o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium Compounds
Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. The most common minerals of barium are barite (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3). The name ''barium'' originates from the alchemical derivative "baryta", from Greek (), meaning 'heavy'. ''Baric'' is the adjectival form of barium. Barium was identified as a new element in 1772, but not reduced to a metal until 1808 with the advent of electrolysis. Barium has few industrial applications. Historically, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes. It is a component of YBCO (high-temperature superconductors) and electroceramics, and is added to steel and cast iron to reduce the size of carbon grains within the microstructure. Barium compounds are a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. Most carcinogens act by creating mutations in DNA that disrupt a cell's normal processes for regulating growth, leading to uncontrolled cellular proliferation. This occurs when the cell's DNA repair processes fail to identify DNA damage allowing the defect to be passed down to daughter cells. The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division. The specific mechanisms for carcinogenic activity is unique to each agent and cell type. Carcinogens can be broadly categorized, however, as activation-dependent and activation-independent which relate to the agent's ability to engage dir ... [...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, bacteria, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell (biology), cell (cytotoxicity) or an organ such as the liver (hepatotoxicity). Sometimes the word is more or less synonymous with poison#Poisoning, poisoning in everyday usage. A central concept of toxicology is that the effects of a toxicant are Dose (biochemistry), 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 bypass animal testing, while maintaining the concept of toxicity endpoints. Etymology In Ancient G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytotoxic
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of drugs, e.g alcohol, and some venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'') are toxic to cells. Cell physiology Treating cells with the cytotoxic compound can result in a variety of prognoses. The cells may undergo necrosis, in which they lose membrane integrity and die rapidly as a result of cell lysis. The cells can stop actively growing and dividing (a decrease in cell viability), or the cells can activate a genetic program of controlled cell death (apoptosis). Cells undergoing necrosis typically exhibit rapid swelling, lose membrane integrity, shut down metabolism, and release their contents into the environment. Cells that undergo rapid necrosis in vitro do not have sufficient t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genotoxic
Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, but some genotoxic substances are not mutagenic. The alteration can have direct or indirect effects on the DNA: the induction of mutations, mistimed event activation, and direct DNA damage leading to mutations. The permanent, heritable changes can affect either somatic cells of the organism or germ cells to be passed on to future generations. Cells prevent expression of the genotoxic mutation by either DNA repair or apoptosis; however, the damage may not always be fixed leading to mutagenesis. To assay for genotoxic molecules, researchers assay for DNA damage in cells exposed to the toxic substrates. This DNA damage can be in the form of single- and double-strand breaks, loss of excision repair, cross-linking, alkali-labile sites, point mutations, and stru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc Chromate
Zinc chromate, Zn Cr O4, is a chemical compound, a salt containing the chromate anion, appearing as odorless yellow powder or yellow-green crystals, but, when used for coatings, pigments are often added. It is used industrially in chromate conversion coatings, having been developed by the Ford Motor Company Ford Motor Company (commonly known as Ford) is an American multinational corporation, multinational automobile manufacturer headquartered in Dearborn, Michigan, United States. It was founded by Henry Ford and incorporated on June 16, 1903. T ... in the 1920s. Production A process known as the Cronak process is used to create zinc chromate for use in industry. This process is done by putting zinc or a zinc plated metal in a solution of sodium dichromate and sulfuric acid for a few seconds. Zinc chromate can also be synthesized by using neutral potassium chromate (K2CrO4) and zinc sulfate (ZnSO4), which forms a precipitate. K2CrO4 + ZnSO4 → ZnCrO4 + K2SO4 File:Zi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claude Monet
Oscar-Claude Monet (, ; ; 14 November 1840 – 5 December 1926) was a French painter and founder of Impressionism painting who is seen as a key precursor to modernism, especially in his attempts to paint nature as he perceived it. During his long career, he was the most consistent and prolific practitioner of Impressionism's philosophy of expressing one's perceptions of nature, especially as applied to ''En plein air, ''plein air'''' (outdoor) landscape painting. The term "Impressionism" is derived from the title of his painting ''Impression, Sunrise, Impression, soleil levant'', which was exhibited in 1874 at the First Impressionist Exhibition, initiated by Monet and a number of like-minded artists as an alternative to the Salon (Paris), Salon. Monet was raised in Le Havre, Normandy, and became interested in the outdoors and drawing from an early age. Although his mother, Louise-Justine Aubrée Monet, supported his ambitions to be a painter, his father, Claude-Adolphe, disa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fumaric Acid
Fumaric acid or ''trans''-butenedioic acid is an organic compound with the formula HO2CCH=CHCO2H. A white solid, fumaric acid occurs widely in nature. It has a fruit-like taste and has been used as a food additive. Its E number is E297. The salts and esters are known as fumarates. Fumarate can also refer to the ion (in solution). Fumaric acid is the ''trans'' isomer of butenedioic acid, while maleic acid is the ''cis'' isomer. Biosynthesis and occurrence It is produced in eukaryotic organisms from succinate in complex 2 of the electron transport chain via the enzyme succinate dehydrogenase. Fumaric acid is found in fumitory (''Fumaria officinalis''), bolete mushrooms (specifically ''Boletus fomentarius var. pseudo-igniarius''), lichen, and Iceland moss. Fumarate is an intermediate in the citric acid cycle used by cells to produce energy in the form of adenosine triphosphate (ATP) from food. It is formed by the oxidation of succinate by the enzyme succinate dehydr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baryte
Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate (Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), anglesite (lead sulfate), and anhydrite (calcium sulfate). Baryte and celestine form a solid solution . Names and history The radiating form, sometimes referred to as ''Bologna Stone'', attained some notoriety among alchemists for specimens found in the 17th century near Bologna by Vincenzo Casciarolo. These became phosphorescent upon being calcined. Carl Scheele determined that baryte contained a new element in 1774, but could not isolate barium, only barium oxide. Johan Gottlieb Gahn also isolated barium oxide two years later in similar studies. Barium was first isolated by electrolysis of molten barium salts in 1808 by Sir Humphry Davy in England. The American Petroleum Institute specification API 13/ISO 13500, which governs '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
