Dental amalgams have been suspected by some medical practitioners, particularly of integrative or alternative medicine, of causing many physical and/or psychological problems. They reason that, since mercury is poisonous, so must be anything in the mouth which contains and releases mercury; hence, that amalgams in the mouth are poisonous. While amalgam fillings are universally regarded as hazardous waste outside the mouth, after removal, and as hazardous material before insertion into the mouth, the dispute rests o ...

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Dental amalgam controversy, Dental amalgam controversy - History of dental amalgam, Dental amalgam controversy - Appearance, Dental amalgam controversy - History of controversy, Dental amalgam controversy - Composition, Dental amalgam controversy - Regulation, Dental amalgam controversy - Environmental impact, Dental amalgam controversy - Amalgams and Alternative Medicine

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Krypton, a so-called noble gas due to its very low chemical reactivity, is characterized by a brilliant green and orange spectral signature. It is one of the products of uranium fission. Solidified krypton is white and crystalline with a face-centered cubic crystal structure which is a common property of all "rare gases". ...

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Krypton, Krypton - Notable characteristics, Krypton - History, Krypton - Occurrence, Krypton - Compounds, Krypton - Isotopes, Krypton - Krypton fluoride laser

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The reddish-orange color that neon emits in neon lights is widely used to make advertising signs. The word "Neon" is also used generically for these types of lights when in reality many other gases are used to produce different colors of light. Other uses: vacuum tubes high-voltage indicators, lightning arrestors, wave meter tubes, television tubes. Neon and helium are used to make a type of gas laser. Liquefied neon is commercially used as ...

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Neon, Neon - Notable characteristics, Neon - Applications, Neon - History, Neon - Occurrence, Neon - Compounds, Neon - Isotopes

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While almost all plutonium is manufactured synthetically, extremely tiny trace amounts are found naturally in uranium ores. These come about by a process of neutron capture by 238U nuclei, initially forming 239U; two subsequent beta decays then form 239Pu (with a 239Np intermediary), which has a half-life of 24,100 years. This is also the process used to manufacture 239Pu in nuclear reactors. Some traces of 244Pu remain from the birth of the solar system from waste of supernovae, because its ha ...

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Plutonium, Plutonium - Notable characteristics, Plutonium - Applications, Plutonium - History, Plutonium - Occurrence, Plutonium - Manufacture, Plutonium - Compounds, Plutonium - Allotropes, Plutonium - Isotopes, Plutonium - Precautions

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Pastel crayons or sticks, which resemble chalk, consist of pure pigment combined with an inert binder, such as gum arabic, gum tragacanth, or methyl cellulose. They are available in varying degrees of hardness, the softer varieties being wrapped in paper. The colors are simply drawn onto the artwork surface, usually paper. The available pastel media can be subdivided as follows: Hard pastels — These have a higher portion of binder and less pigment, producing a sharp drawing material that is useful for fine detail ...

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Pastel, Pastel - Media, Pastel - Artists

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Most organic solvents are flammable or highly flammable, depending on their volatility. Exceptions are some chlorinated solvents like methylene chloride and chloroform. Mixtures of solvent vapors and air can explode. Solvent vapors are heavier than air, they will sink to the bottom and can travel large distances nearly undiluted. Solvent vapors can also form in supposedly empty drums and cans, posing a flash fire hazard; hence empty containers of volatile solvents shou ...

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Solvent, Solvent - Polarity solubility and miscibility, Solvent - Protic and aprotic solvents, Solvent - Boiling point, Solvent - Density, Solvent - Chemical interactions, Solvent - Safety, Solvent - General precautions, Solvent - Properties table of common solvents

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All isotopes and compounds of plutonium are toxic and radioactive. While plutonium is sometimes described in media reports as "the most toxic substance known to man", there is general agreement among experts in the field that this is incorrect. As of 2003, there has yet to be a single human death officially attributed to plutonium exposure. Naturally-occurring radium is about 200 times more radiotoxic than plutonium, and some organic toxins like Botulin toxin are still more toxic. Botulin toxin, in particular, has ...

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Plutonium, Plutonium - Notable characteristics, Plutonium - Applications, Plutonium - History, Plutonium - Occurrence, Plutonium - Manufacture, Plutonium - Compounds, Plutonium - Allotropes, Plutonium - Isotopes, Plutonium - Precautions

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The equipment required for the gas tungsten arc welding operation includes a welding torch utilizing a nonconsumable tungsten electrode, a constant-current welding power supply, and a shielding gas source. Gas tungsten arc welding - Welding torch. GTAW welding torches are designed for either automatic or manual operation and are equipped with cooling systems using air or water. The automatic and manual torches are similar in construction, but the manual torch has a handle while the automatic torch normally ...

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Gas tungsten arc welding, Gas tungsten arc welding - Development, Gas tungsten arc welding - Operation, Gas tungsten arc welding - Safety, Gas tungsten arc welding - Applications, Gas tungsten arc welding - Quality, Gas tungsten arc welding - Equipment, Gas tungsten arc welding - Welding torch, Gas tungsten arc welding - Power supply, Gas tungsten arc welding - Electrode, Gas tungsten arc welding - Shielding gas, Gas tungsten arc welding - Materials, Gas tungsten arc welding - Aluminum and magnesium, Gas tungsten arc welding - Steels, Gas tungsten arc welding - Dissimilar metals, Gas tungsten arc welding - Process variations, Gas tungsten arc welding - Pulsed-current, Gas tungsten arc welding - Dabber, Gas tungsten arc welding - Notes

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Glass - Float annealed glass. 90% of the world's flat glass is produced by the float glass process invented in the 1950s by Sir Alastair Pilkington of Pilkington Glass, in which molten glass is poured onto one end of a molten tin bath. The glass floats on the tin, and levels out as it spreads along the bath, giving a smooth face to both sides. The glass cools and slowly solidifies as it travels over the molten tin and leaves the tin bath in a continuous ribbon. The glass is annealed by cooling in a temperatured controlled oven called a "lehr". The finishe ...

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Glass, Glass - Properties and Uses, Glass - Glass Ingredients, Glass - Glass as a polymer, Glass - Colors, Glass - History of glass, Glass - Glass tools, Glass - Glass art, Glass - Architectural glass, Glass - Float annealed glass, Glass - Sheet glass, Glass - Plate glass, Glass - Cylinder glass, Glass - Insulated glazing, Glass - Toughened glass, Glass - Laminated glass, Glass - Low-emissivity glass, Glass - Self-cleaning glass, Glass - Evacuated glazing, Glass - Glass as a liquid

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Nitrogen - Nitrogen Compounds. Molecular nitrogen in the atmosphere is relatively non-reactive, but in nature it is slowly converted into biologically (and industrially) useful compounds by some living organisms, notably certain bacteria (see Biological role below). The ability to combine or fix nitrogen is a key feature of modern industrial chemistry, where nitrogen and natural gas are converted into ammonia via the Haber process. Ammonia, in turn, can be used directly (primarily as a fertilizer), or as a precursor of many other important materials including explosives, largely via the producti ...

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Nitrogen, Nitrogen - Notable characteristics, Nitrogen - Applications, Nitrogen - Nitrogen Compounds, Nitrogen - Molecular nitrogen gas and liquid, Nitrogen - The History of Nitrogen, Nitrogen - Occurrence, Nitrogen - Compounds, Nitrogen - Biological role, Nitrogen - Isotopes, Nitrogen - Precautions

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Zeppelin - Early Zeppelin history. Count Ferdinand von Zeppelin became interested in constructing a "dirigible balloon" after the Franco-Prussian War of 1870/1871, where he witnessed the use of French balloons during the siege of Paris. He had also encountered the military use of such aircraft in 1863 during the American Civil War, in which he participated as a military observer on the side of the Union. He began to seriously pursue his project after his early retirement from the military in 1890 at the a ...

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Zeppelin, Zeppelin - Principal characteristics, Zeppelin - History of the Zeppelin, Zeppelin - Early Zeppelin history, Zeppelin - Zeppelins in World War I, Zeppelin - Zeppelin history after World War I, Zeppelin - Non-German Rigid Airships, Zeppelin - Recent developments, Zeppelin - Cultural influences

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In most places in the tropics sufficient precipitation occurs to grow enough food to feed the local population; however, it many not fall in a timely or convenient manner. Making maximum use of the water that does fall is an ongoing challenge. Water is a particularly important issue in dryland farming. The ability to collect and store water at a low cost and without damaging the environment, is what opens up deserts and other arid regions to farmers. When it rains in dryland areas, the rain storms are normally heavy, and the soil unable to absorb the large amounts of rain that comes down. This leads to ex ...

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Tropical agriculture, Tropical agriculture - Green Revolution, Tropical agriculture - Plant propagation, Tropical agriculture - Plant defenses, Tropical agriculture - Slash/mulch, Tropical agriculture - Small-scale irrigation, Tropical agriculture - Water harvesting pits, Tropical agriculture - Bucket drip irrigation, Tropical agriculture - Treadle pumps, Tropical agriculture - Pest control, Tropical agriculture - Crop rotation, Tropical agriculture - Integrated pest management, Tropical agriculture - Major constraints, Tropical agriculture - Acidic soils, Tropical agriculture - Salinization, Tropical agriculture - Day-length sensitive plants, Tropical agriculture - Pioneering crops, Tropical agriculture - Hunger season, Tropical agriculture - Major tropical food crops

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Glass - Float annealed glass. 90% of the world's flat glass is produced by the float glass process invented in the 1950s by Sir Alastair Pilkington of Pilkington Glass, in which molten glass is poured onto one end of a molten tin bath. The glass floats on the tin, and levels out as it spreads along the bath, giving a smooth face to both sides. The glass cools and slowly solidifies as it travels over the molten tin and leaves the tin bath in a continuous ribbon. The glass is annealed by cooling in a temperatured controlled oven called a "lehr". The finishe ...

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Glass, Glass - Properties and Uses, Glass - Glass Ingredients, Glass - Glass as a polymer, Glass - Colors, Glass - History of glass, Glass - Glass tools, Glass - Glass art, Glass - Architectural glass, Glass - Float annealed glass, Glass - Sheet glass, Glass - Plate glass, Glass - Cylinder glass, Glass - Insulated glazing, Glass - Toughened glass, Glass - Laminated glass, Glass - Low-emissivity glass, Glass - Self-cleaning glass, Glass - Evacuated glazing, Glass - Glass as a liquid, Glass - Evidence against glass flow

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Although electrolysis occurs in pure water, it is a very poor conductor of electricity. It is necessary to add a water-soluble electrolyte, the ions of which are harder to oxidize or reduce than water. Ions flow through the solution, thereby completing the electric circuit. 2 H2O + 2e− → H2 + 2 OH− E0red= −0.83 V 2 H2O → O2 + 4H^{See also:}

Electrolysis of water, Electrolysis of water - What is involved?, Electrolysis of water - Equipment used, Electrolysis of water - How is it possible?, Electrolysis of water - Testing the presence of oxygen and hydrogen, Electrolysis of water - Using other indicators, Electrolysis of water - Efficiency

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Like all electrochemical cells, the dry cell gets its electrical energy from an internal chemical reaction which takes the form of two half-cell reactions. The electrolyte in the cell consists of ammonium chloride, manganese(IV) oxide, finely granulated carbon and an inert filler which is usually starch. The ammonia from the ammonium ions forms the complex ion Zn(NH3)42+ with the Zn2+ preventing buildup of Zn ions which would result in r ...

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Dry cell, Dry cell - Overview, Dry cell - Usage, Dry cell - Chemistry, Dry cell - Oxidation, Dry cell - Reduction, Dry cell - Gas absorption, Dry cell - Practical considerations, Dry cell - History

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Liquid-liquid extraction - Solvation mechanism. Using solvent extraction it is possible to extract uranium, plutonium, or thorium from acid solutions. One solvent used for this purpose is the organophosphate tri-n-butyl phosphate. The PUREX process is commonly used in nuclear reprocessing uses a mixture of tri-n-butyl phosphate and an inert hydrocarbon (kerocene), the uranium(VI) are extracted from strong nitric acid and are back-extracted (stripped) using weak nitric acid. An organic soluble uranium complex [UO< ...

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Liquid-liquid extraction, Liquid-liquid extraction - Distribution ratio, Liquid-liquid extraction - One big batch of solvent or several smaller batchs ?, Liquid-liquid extraction - Separation factors, Liquid-liquid extraction - Decontamination factor, Liquid-liquid extraction - Slopes of graphs, Liquid-liquid extraction - Batchwise single stage extractions, Liquid-liquid extraction - Multistage countercurrent continuous processes, Liquid-liquid extraction - Extraction without chemical change, Liquid-liquid extraction - Extraction with chemical change, Liquid-liquid extraction - Solvation mechanism, Liquid-liquid extraction - Ion exchange mechanism, Liquid-liquid extraction - Ion pair extraction, Liquid-liquid extraction - Kinetics of extraction, Liquid-liquid extraction - Aqueous complexing agents, Liquid-liquid extraction - Industrial process design, Liquid-liquid extraction - Equipment, Liquid-liquid extraction - Terms

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To be viable, an alcohol-based fuel economy should have positive net fuel energy balance. Namely, the total fuel energy expended in producing the alcohol — including fertilizing, farming, harvesting, transport, fermentation, distillation, and distribution, as well as the fuel used in building the farm and fuel plant equipment — should not exceed the energy contents of the product. This is a controversial subject charged with potential bias. Much of it depends on what is included and what is excluded from the calculation, particula ...

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Ethanol fuel, Ethanol fuel - Ethanol fuels, Ethanol fuel - Production and Distribution, Ethanol fuel - Other alcohols, Ethanol fuel - Ethanol and hydrogen, Ethanol fuel - Alternate sources, Ethanol fuel - Net fuel energy balance, Ethanol fuel - Energy balance in the United States, Ethanol fuel - Arguments and criticisms, Ethanol fuel - Air pollution, Ethanol fuel - Fire safety, Ethanol fuel - Greenhouse gases, Ethanol fuel - Renewable resource, Ethanol fuel - Dependency on foreign oil and international crime, Ethanol fuel - Statism, Ethanol fuel - Cost, Ethanol fuel - Ethanol fuel in Colombia, Ethanol fuel - Ethanol fuel in Brazil, Ethanol fuel - Ethanol fuel in the United States, Ethanol fuel - Ethanol fuel in the Midwest, Ethanol fuel - U.S. National security

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Electrical power transmission networks are protected and controlled by high voltage breakers. The definition of "high voltage" varies but in power transmission work is usually thought to be 72,500 V or higher, according to a recent definition by the International Electrotechnical Commission (IEC). High voltage breakers are nearly always solenoid operated, with current sensing protective relays operated through current transformers. In substations the protection relay scheme can be complex, protecting equipment ...

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Circuit breaker, Circuit breaker - Low voltage European circuit breaker, Circuit breaker - Common trip breakers, Circuit breaker - Types of circuit breaker, Circuit breaker - High Voltage Circuit Breakers, Circuit breaker - Interrupting Principles for High-Voltage Circuit-Breakers, Circuit breaker - Brief History, Circuit breaker - Thermal blast chambers, Circuit breaker - Self blast chambers, Circuit breaker - Double motion of contacts, Circuit breaker - Comparison of single motion and double motion techniques, Circuit breaker - Thermal blast chamber with arc-assisted opening, Circuit breaker - Particular case of generator circuit-breakers, Circuit breaker - Evolution of tripping energy, Circuit breaker - Future perspectives, Circuit breaker - Other breakers

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Common classes of organic conductive polymers include poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, poly(aniline)s, poly(fluorene)s, polynaphthalenes, poly(p-phenylene sulfide), and poly(para-phenylene vinylene)s. Classically, these compounds are known as polyacetylene, polyaniline, etc. "blacks" or "melanins". The melanin pigment in animals is generally a mixed copolymer of polyacetylene, polypyrrole, and polyaniline. See also:

Conductive polymers, Conductive polymers - Chemistry, Conductive polymers - Doping, Conductive polymers - Conjugation, Conductive polymers - Properties, Conductive polymers - Physics, Conductive polymers - Applications

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Naturally occurring xenon is made of seven stable and two slightly radioactive isotopes. Beyond these stable forms, there are 20 unstable isotopes that have been studied. Xe-129 is produced by beta decay of I-129 (half-life: 16 million years); Xe-131m, Xe-133, Xe-133m, and Xe-135 are some of the fission products of both U-235 and Pu-239, and therefore used as indicators of nuclear explosions. The artificial isotope Xe-135 is of considerable significance in the operation of nuclear fission reactors. Xe-135 has a huge cross section for ...

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Xenon, Xenon - Notable characteristics, Xenon - Applications, Xenon - History, Xenon - Occurrence, Xenon - Compounds, Xenon - Isotopes, Xenon - Precautions

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Argon is 2.5 times as soluble in water as nitrogen which is approximately the same solubility as oxygen. This highly stable chemical element is colorless and odorless in both its liquid and gaseous forms. There are few known true chemical compounds that contain argon, which is one of the reasons it was formerly called an inert gas. The creation of argon hydrofluoride (HArF), a highly unstable compound of argon with fluorine, was reported by researchers at the University ...

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Argon, Argon - Notable characteristics, Argon - Applications, Argon - History, Argon - Occurrence, Argon - Compounds, Argon - Isotopes

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High performance liquid chromatography, usually referred to simply as HPLC, is a form of column chromatography used frequently in biochemistry and Analytical Chemistry. The analyte is forced through a column (stationary phase) by a liquid (mobile phase) at high pressure, which decreases the time the separated components remain on the stationary phase and thus the time they have to diffuse within the column. Diffusion within the column leads to broad peaks and loss of resolution. Less time on the column then translates to narrower peak ...

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Chromatography, Chromatography - History, Chromatography - Chromatography theory, Chromatography - Retention, Chromatography - Plate theory, Chromatography - Paper chromatography, Chromatography - Thin layer chromatography TLC, Chromatography - Column chromatography, Chromatography - Gas-liquid chromatography, Chromatography - Ion exchange chromatography, Chromatography - Immobilized metal ion affinity chromatography, Chromatography - High performance liquid chromatography HPLC, Chromatography - Normal phase NP liquid chromatography, Chromatography - Reversed phase RP liquid chromatography, Chromatography - Gel permeation chromatography, Chromatography - Affinity chromatography, Chromatography - Countercurrent chromatography

Read more here: » Chromatography: Encyclopedia II - Chromatography - High performance liquid chromatography HPLC