Contaminant, origin process related

Localized NMR spectroscopy, which is often called as MRS in comparison with MRI, is not so familiar technique in food science, because a specific pulse sequence such as ISIS and a facility which can precisely follow the pulse sequence without any contamination from other position is needed for localization of position. The localized NMR is usually used together with NMR imaging. The study of solid/liquid ratios, fat structure and polymorphism and the kinetics of fat crystallization was reviewed [24], The potential of applications in food process development and control was offered. The localized spectra of sausages in areas of 0.3 mm X 0.05 mm (thickness of sample =1.5 mm) were obtained by the spin echo 2DFT method [113], in which the difference in the tissue structure was discussed with relation to the process and original materials. McCarthy et al. determined mobility of water in foams by using a localized spectroscopy [114]. T2 relaxation time varies in the foam as function of diameter and its variation was analyzed by the classic 2-state fast exchange model. 

Chemistry plays a very signiticant role in the CMP process. Several variables listed in Chapter 3, the fluid boundary layer formation at the solid-liquid interface, chemical composition of the surface being polished, the formation of the passivating layer at the solid surface caused by an oxidizer, dissolution of the solid surface or of the mechanically abraded solid fragments or atoms/molecules of the original or passivated layer, the isoelectric point (see Chapter 5) related to abrasive and solid surface charge layers, effective removal or redeposition of the polished material, polished surface contamination and post-CMP passivation, and lifetime and properties of the pad all are determined by the chemical interactions induced by the chemicals in the slurry and the solid surfaces. Thus the choice of chemicals (thus of an appropriate chemistry) in making the slurry is very important. 

Initially, the main concern with commercial PCP products was the contamination with PCDDs (albeit not TCDD) as by-products from the manufacturing process, and many of the envirotoxic effects originally attributed to PCP have been shown to be effects of the dioxins. Toxic actions directly related to PCP are uncoupling of oxidative phosphorylation resulting in increased metabolism and the breakdown of energy reserves, immunological effects, liver and kidney damage and reproductive disturbances (National Research Council, 1986 Eisler, 1989). Today the use of PCP is rather restricted, but in areas where the preparations are still in extensive use, PCP poses a threat to aquatic environments in particular. 

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