Color oxidation

Gr. neos, new, and didymos, twin) In 1841, Mosander, extracted from cerite a new rose-colored oxide, which he believed contained a new element. He named the element didymium, as it was an inseparable twin brother of lanthanum. In 1885 von Welsbach separated didymium into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. While the free metal is in misch metal, long known and used as a pyrophoric alloy for light flints, the element was not isolated in relatively pure form until 1925. Neodymium is present in misch metal to the extent of about 18%. It is present in the minerals monazite and bastnasite, which are principal sources of rare-earth metals. 

Elemental chemical analysis provides information regarding the formulation and coloring oxides of glazes and glasses. Energy-dispersive x-ray fluorescence spectrometry is very convenient. However, using this technique the analysis for elements of low atomic numbers is quite difficult, even when vacuum or helium paths are used. The electron-beam microprobe has proven to be an extremely useful tool for this purpose (106). Emission spectroscopy and activation analysis have also been appHed successfully in these studies (101). 

Various methods can be used to analy2e succinic acid and succinic anhydride, depending on the characteristics of the material. Methods generally used to control specifications of pure products include acidimetric titration for total acidity or purity comparison with Pt—Co standard calibrated solutions for color oxidation with potassium permanganate for unsaturated compounds subtracting from the total acidity the anhydride content measured by titration with morpholine for content of free acid in the anhydride atomic absorption or plasma spectroscopy for metals titration with AgNO or BaCl2 for chlorides and sulfates, respectively and comparison of the color of the sulfide solution of the metals with that of a solution with a known Pb content for heavy metals. 

Properties. Uranium metal is a dense, bright silvery, ductile, and malleable metal. Uranium is highly electropositive, resembling magnesium, and tarnishes rapidly on exposure to air. Even a poHshed surface becomes coated with a dark-colored oxide layer in a short time upon exposure to air. At elevated temperatures, uranium metal reacts with most common metals and refractories. Finely divided uranium reacts, even at room temperature, with all components of the atmosphere except the noble gases. The silvery luster of freshly cleaned uranium metal is rapidly converted first to a golden yellow, and then to a black oxide—nitride film within three to four days. Powdered uranium is usually pyrophoric, an important safety consideration in the machining of uranium parts. The corrosion characteristics of uranium have been discussed in detail (28). 

These compounds are used most frequentiy in combination with hindered phenols for a broad range of apphcations in mbber and plastics. They are also able to suppress color development caused by oxidation of the substrate and the phenoHc antioxidant. Unlike phenols and secondary aromatic amines, phosphoms-based stabilizers generally do not develop colored oxidation products. 

Numerous workers126-132 have combined PB with the conducting polymer polyaniline in complementary ECDs that exhibit deep blue-to-light green electrochromism. Electrochromic compatibility is obtained by combining the colored oxidized state of the polymer1 with the blue PB, and the bleached reduced state of the polymer with PG (Equation (17)) ... 

Terbium - the atomic number is 65 and the chemical symbol is Tb. The name derives from the village of Ytterby in Sweden, where the mineral ytterbite (the source of terbium) was first found. It was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander in 1843 in an yttrium salt, which he resolved into three elements. He called one yttrium, a rose colored salt he called terbium and a deep yellow peroxide he called erbium. The chemist Berlin detected only two earths in yttrium, i.e., yttrium and the rose colored oxide he called erbium. In 1862, the Swiss chemist Marc Delafontaine reexamined yttrium and found the yellow peroxide. Since the name erbium had now been assigned to the rose colored oxide, he initially called the element mosandrum (after Mosander) but he later reintroduced the name terbium for the yellow peroxide. Thus the original names given to erbium and terbium samples are now switched. Since Bunsen spectroscopically examined Mosander s erbium (now terbium) sample and declared that it was a mixture, the question of who actually discovered terbium, Mosander or Delafontaine remains unresolved to this day. 

Lube oil solvent refining includes a collection of subprocesses improving the quality of lubricating oil stock. The raffinate or refined lube oils obtain improved viscosity, color, oxidation resistance, and temperature characteristics. A particular solvent is selected to obtain the desired quality raffinate. The solvents include furfural, phenol, sulfm dioxide, and propane. 

The element was discovered hy von Welshach in 1885 after he succeeded in fractionating ammonium didymium nitrate, thus splitting didymia into two new rare earths. Earlier, in 1841, Mosander extracted a rose-colored oxide from cerite, which he named didymium and which actually was a mixture of two rare earth elements. These two new elements were named hy von Welshach as praseodymia (green twin) and neodymia (new twin). 

Neoc ym1utn oxide, which Is used as a coloring oxide in hand crafted glass, is also used in doping laser glasses which is another growing field. 

In 1841 Mosander had treated lanthana with dilute nitric acid, and had extracted from it a new rose-colored oxide, which he believed contained a new element. He named the new metal didymium because, as he said, it seemed to be an inseparable twin brother of lanthanum (27, 29, 46). 

Bricks. When mixed with clay to make bricks, petroleum coke assists in burning the brick. It acts as a reducing agent for some of the colored oxides in the clay, giving a brick with improved color. When coal coke is used in the same way, the ash in the coke may flux with some of the clay, giving an undesirable product (16). 

When the coloring oxides employed are such that they are not injuriously affected by the oxides of lead and of bismuth, the flux is usually composed of the following ingredients —... 

Although most of the experiments were carried out using p-xylene as substrate, several exploratory runs were made using other aromatic hydrocarbons. These are summarized in Table I. Maximum yields were not determined. Alkylnaphthalenes gave highly colored oxidates, from which only small amounts of naphthoic and naphthalic acids could be isolated. Oxidation of anthracene gave virtually quantitative yields of anthraquinone under extremely mild conditions (10). 

Copper and gold bronze pigments are not as colorfast as aluminum pigments because they decompose to produce colored oxides and corrosion products. However, stabilized pigments (e.g., with a silica coating) are also available for critical applications in binders with high acid values or that react with copper or zinc. 

If a dark colored oxide is being treated, the reaction is easily followed by the change in color of the mixture. The heating should be continued until test portions are completely soluble or the test solutions show only slight opalescence. This usually requires from 1 to 3 hours. 

Invertase (EC 3.2.1.26) catalyzes the hydrolysis of P-fructofuranosides and has been used in analytical chemistry (biosensors), in confectionary, and in the production of inverted syrup (1). Invert sugar syrup, which can be obtained by acid or enzymatic hydrolysis of sucrose, is a valuable commercial product especially in countries where the main sources of sugar are beet or cane. With acid hydrolysis, the final syrup is often contaminated with colored oxidation compounds, which arise from cyclization of hex-oses at low pH and high temperatures (2-4). Such a problem does not occur... 

Colored oxide films were observed to have formed on columbium after... 

Lithium nitrate is soluble in water and is highly hygroscopic. Its only use is as a flame-coloring oxidizer in pyrotechnical formulations. 

Strontium nitrate is used in pyrotechnics as a flame-coloring oxidizer for red-colored fireworks. 

Bleaching can be carried out by a colored oxidant which is reduced by the silver metal to colorless compounds. This is the basis of the dye-bleach process. The overall reaction may be written as Eq. (97). 

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