Chemical composition of materials

The chemical compositions of materials are usually expressed in terms of simple oxides calculated from elemental analysis determined by x-ray fluorescence. For spent foundry sand, the chemical parameters include bulk oxides mass composition, loss on ignition, and total oxygen demand. Table 4.6 lists the general chemical properties of spend foundry sand. It is shown that spent foundry sand consists primarily of silica dioxide. 

That essence (so far as I can tell) is the conception or synthesis, the design, testing, scale-up, operation, control, and optimization of commercial processes that change the state, microstructure, and, most typically, the chemical composition of materials, by physicochemical separations and above all by chemical reactions. What distinguishes chemical engineering from the other major branches of engineering is the centrality of physicochemical... 

Bartuska VJ, Maciel GE, Bolkers HI, Fleming Bl (1980) Structural studies of lignin isolation procedures by nC NMR Holzforschung 34 214-217 Dixon WT, Schaefer J, Sefcik MD, Stejskal EO, McKay RA (1981) Quantitative chemical composition of materials such as humic soils, lignins, and coals by high-resolution carbon 13 NMR J Magn Reson 45 173-176... 

Processing of research results leads to determination of the following conclusion if as a result of conducted comparative physicochemical analyses, the properties and chemical composition of material forming the evidence trace are found to be consistent with those of the reference material, then, on this basis, the materials could have a common origin. This means, in the case of analysis of samples of paint, glass, plastic and fibres, that they could have constituted a single entity before... 

The first objective for the Sojourner was to show that it could function in the little-known environment on the surface of Mars and to observe its behavior in order to make design improvements in future rovers. Sojourner moved around the immediate area of the lander, butting the APXS up against rocks. Detectors measured interactions between a radioactive source in the APXS and the surface materials by obtaining an energy spectrum of the alpha particles, protons, and x rays produced by the exposure. This instrument could determine the chemical composition of materials, including the amounts present of most major elements except hydrogen. 

Elemental analysis, determination of the chemical composition of material, is the most common type of analysis in archaeological chemistry. A variety of instruments can be used for such analyses including SEM microprobes, ICP spectrometers, mass spectrometers, CN analyzers, NAA analysis, and many others. The instruments chosen for elemental analysis depend on several factors including availability, elements of interest, the nature and size of sample, cost, turn-around time, and others. A variety of materials have been investigated with elemental analysis, almost any kind of archaeological material that exists. 

The value of computing derivative spectra to correct for non-linear baseline signals is frequently exploited in reflectance spectrometry. Rapid measurement of the chemical composition of materials and products by diffuse reflectance spectroscopy in the near-infrared (NIR) region (800-2600 nm) is routine in many industries. Because most bulk materials are not transparent the mode of measurement is generally reflectance. For powder samples the intensity of... 

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