Crystals, chemistry handling

This paper will focus on the application of solid state modeling techniques to one particular particle property - crystal habit. A morphological study on the analgesic aspirin (C9H8O4) will be presented in order to assess the effects of morphology on processing, and materials handling. The crystal chemistry will be... 

In my opinion, the field of miniemulsion is still on its rise in polymer and material science since there are numerous additional possibilities both for fundamental research and application. As a vision one may think of single molecules trapped and crystallized in each small droplet, which enables new types of physico-chemical experiments and handling of complex matter [132]. Since miniemulsions allow a very convenient and effective separation of objects in compartments of the size of 30-300 nm in diameter, some general new perspectives for polymer chemistry are opened. In miniemulsion droplets, it is in principle possible to isolate complex polymers or colloids strictly from each other and to react each single molecule for itself with other components, still working with significant amounts of matter and technically relevant mass fluxes. This... 

Studies of the coordination chemistry of the actinides have been limited by a number of factors - the care needed in handling radioactive materials and the possibility of damage to human tissue from the radiation toxicity (especially Pu) the very small quantities available and very short half-lives of the later actinides radiation and heating damage to solutions and radiation damage (defects and dislocations) to crystals. 

Uranium hexachloride is a black solid melting at 177.5°. Since it is hygroscopic and reacts vigorously with water, it should be handled only in dry-boxes. The crystal structure has been determined hexagonal symmetry, space group D a-C7> (m, n = 3), with an almost perfect octahedron of chlorine atoms around each uranium atom. Uranium hexachloride can be sublimed at 75-100° at low pressures, but normally some thermal decomposition results. The ultraviolet-visible spectrum of gaseous uranium hexachloride has been determined. No fine structure was observed in the spectrum. Because previously available preparative methods were inadequate, there has been very little study of the chemistry of uranium hexachloride. It reacts with hydrogen... 

The systematic principles of boron hydride structures ahd chemistry are the principal subjects of the present review. There are several reasons why these principles became clear such a long time after the discovery of these compounds (a) most of the compounds must be handled in grease-free vacuum line systems (b) some of the boron hydrides are unstable at ordinary temperatures, explosive on contact with air, and toxic (c) the structures are based on principles, still incompletely developed, of electron-deficient compounds and (d) location of the hydrogen atoms is a crucial part of the structure determinations, unlike the situation in hydrocarbons, and had to be done for the most part in X-ray diffraction studies of single crystals grown at low temperatures. 

Trinitrophenol, also known as picric acid, is composed of yellow crystals and is a nitro hydrocarbon derivative. It is shipped with not less than 10% water as a wetted explosive. There is a severe explosion risk when shocked or heated to 572°F, and it reacts with metals or metallic salts. In addition to being flammable and explosive, it is toxic by skin absorption. Picric acid has caused disposal problems in school and other chemistry laboratories where the moisture has evaporated from the container as the material ages. When the picric acid dries out, it becomes a high explosive closely related to TNT. Picric acid has been found in various amounts in school labs across the country. In a dry condition, picric acid is dangerous and should be handled by the bomb squad. The structure and molecular formula for picric acid are shown in Figure 6.3. 

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