Nitrogen-based atmospheres

Nitridation characteristics are similar in behavior to that of carburization, although not as industrially common in occurrence. It is firequently observed in materials exposed in air at relative high homologous substrate temperatures, in ammonia production, and in nitrogen-based atmospheres. As with carburization atmospheres, increasing oxidation activity decreases nitridation at a given temperature. 

The stability constants821 for the 8-hydroxyquinoline (oxine) complexes have been questioned owing to the ease with which the VIV complexes undergo oxidation, even by atmospheric o2.355,687 However, adducts [VO(oxine)2L] (L = py or other nitrogen bases) were more stable towards oxidation. The Viv oxine complex gradually turns magenta black when extracted into a nonpolar solvent, indicating formation of the Vv oxine complex in air, but in... 

Scientists have learned how to control chemical reactions to produce many useful materials—nitrates and other nitrogen-based fertilizers from atmospheric nitrogen, metals from rocks, plastics and pharmaceuticals from petroleum. These materials and the thousands of others produced by chemical reactions, as well as the abundant energy released when fossil fuels take part in the chemical reaction called combustion, have dramatically improved our living conditions. 

The open end of the reaction tube is attached to an oil pump through a dust trap, and dry nitrogen is admitted at a rate such that the pressure is maintained at or below 25 mm. The bismuth(III) iodide is sublimed into the receiver end of the tube by heating with the spread burner flame and with an auxiliary Tirrill burner adjusted to maximum heat. Satisfactory progress of the sublimation is indicated by the persistence of yellowish-brown bis-muth(III) iodide vapors and by the absence of the violet color of iodine vapor. When the sublimation is complete, the tube is allowed to cool to room temperature in nitrogen at atmospheric pressure. The product is scraped from the receiver section of the tube and stored out of contact with the atmosphere. The yield is 72% based on bismuth. Anal. Calcd. for Bil3 Bi, 35.44. Found Bi, 35.42. The same result is found upon analysis of a resublimed sample of this product. 

The Archaean atmosphere-ocean system was probably less oxic than today, but supply of oxidant would have occurred nevertheless as, in an Archaean C02-based atmosphere, volcanic sulphur and nitrogen sources would have provided SO t and NO, or precursors that would have been oxidized in the atmosphere to and NO. Together with nitrogen-fixing by lightning, this would have supplied sulphate and nitrate for use by microbes living in mud that contained picoplankton debris, to sustain mats, possibly of colourless sulphur bacteria. The REE record a distant hydrothermal input, which, depending on water currents, supplied metals and perhaps episodes of reduction. 

Based on sturdy composite materials comprising metallic tungsten and aluminum nitride, we fabricated a AIN/W FGM approximately 0.5 mm thick in which the amount of metallic tungsten added was changed in stages by a normal sintering method in a nitrogen gas atmosphere ( at 1 atm ). 

Sephadex samples of approximately 1 g were weighed (1.000 g =. 5154 . 0015 meq of H) into approximately 20-25 mL of 0.05M and 0.03M NaPSS solution (mol wt 50,000 and 500,000, respectively). These samples, covered by a nitrogen gas atmosphere, were then neutralized with standard base to define an a range of study from 0.1 to 0.9. 

One of the most common technologies for the synthesis of polymer polyols by a radical mechanism is based on the stepwise addition of a mixture of vinylic monomers (polyether polyol, initiator, transfer agent (mixture I)) to a second mixture (mixture II) of polyether polyol (identical with the polyether used for mixture I) and NAD (macromer or nonreactive NAD) under a nitrogen protective atmosphere, in the polymerisation reactor at 115-... 

Tab. 3.5 Average total atmospheric input (dep.) as well as output of sulfate, nitrogen, base cations and Al in 1995-1998. From UN/ECE and EK (2001) Der Waidzustand in Europa...

Mono-axially coordinated species are most conveniently formed by the reaction of single face-hindered Fe(II) porphyrins with isocyanide in a non-coordinating solvent, such as toluene or benzene,or when four-coordinate PFe are reacted under an inert atmosphere with nitrogen bases, such as imidazoles and pyridines in the presence of isocyanide This... 

If required, for oxygen-prone, light-labile or heat-labUe compounds, the application (ATS4), development (Automated Multiple Development, AMD 2, CAM AG allows drying the plate under vacuum), and detection (TLC Scanner, CAMAG) can be performed in a dark, nitrogen-protected atmosphere. However, a column-based technique might be better suited for such compounds. 

Vacuum distillation of the atmospheric residue complements primary distillation, enabli r.ecoyery of heavy distillate cuts from atmospheric residue that will un r o further conversion or will serve as lube oil bases. The vacuum residue containing most of the crude contaminants (metals, salts, sediments, sulfur, nitrogen, asphaltenes, Conradson carbon, etc.) is used in asphalt manufacture, for heavy fuel-oil, or for feed for others conversion processes. 

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