Dispersions total energy content

The total energy content (E) of an aqueous polysaccharide dispersion is stated in the general equation... 

The amplitude of oscillation in torque-time curve or that of the ram movement decreases as the contents becomes more homogeneous. In order to use these or total energy for deciding the endpoint, the dispersion must be examined ahead of time to assure a satisfactory result. The reproducibility in the same type mixer but different machines may be a problem. There may be a difference in the extent of wear of the rotor blades. The cooling surface may have scale build-up such that the cooling efficiency may be different. 

A diagonal scan across the surface of the window was recorded with X-ray energy dispersive spectroscopy (XEDS) in the TEM equipment. The atomic ratios of Si 0 N were found to be 43% 13% 44%, which is not the expected stoichiometry of Si02 and Si3N4 (40% 20% 40%). However, we know from the TEM images and the SIMS data shown below that the thickness of the oxide layer is 7 nm and the total window thickness is about 42 nm from which we would expect atomic ratios of 42% 8% 50%. This is most likely indicative of a native oxide present on the backside of the windows, enriching the O content of the whole film (as seen with SIMS), since the escape depth of the photons is much greater than the window thickness. 

Examples of applications of X-ray spectrometric analytical techniques to elemental determinations in a variety of materials are presented in Table 2.12. Some recent applications papers may be mentioned. Total reflection XRF has been applied by Xie et al. (1998) to the multielement analysis of Chinese tea (Camellia sinensis), and by Pet-tersson and Olsson (1998) to the trace element analysis of milligram amounts of plankton and periphyton. The review by Morita etal. (1998) on the determination of mercury species in environmental and biological samples includes XRF methods. Alvarez et al. (2000) determined heavy metals in rainwaters by APDC precipitation and energy dispersive X-ray fluorescence. Other papers report on the trace element content of colostrum milk in Brazil by XRF (da Costa etal. 2002) and on the micro-heterogeneity study of trace elements in uses, MPI-DING and NIST glass reference materials by means of synchrotron micro-XRF (Kempenaers etal. 2003). 

Rose et al. (1996) described the development of a SCP characterisation for oil and coal fuel-types, using particle chemistries determined by energy dispersive X-ray spectroscopy (EDS). This technique is described as semi-quantitative as the results are expressed as a percentage of the total of elements selected for analysis. Additionally, the EDS detector used was unable to determine elements lighter than sodium, and thus carbon and oxygen, most probably the major constituents in SCPs (c.f. traffic-derived soot Fruhstorfer Niessner, 1994), were not measurable and do not appear in the total. However, rather than being a drawback, this had a positive effect as the 17 trace elements analysed consequently appeared to be much more important to the particle composition than in reality, and it was these, rather than the carbon content, which were used in differentiating between the fuel-types. 

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