The applicability of near-infrared spectroscopy to determine the amount of fat in faeces has been investigated. Near-infrared spectroscopy was favourably compared with the well known titrimetric method ( Van de Kamer et al., J Biol Chem 1948; 177:347-55). A good correlation between near-infrared spectroscopy and the titrimetric method was found. The measurement of faecal fat by near-infrared spectroscopy is found to be more precise than the manual method. Moreover, near-infrared spectroscopy is shown to be a very simple and rapid method for measuring fat in faeces. However, it was shown that performing one's own calibration curve is necessary. Due to this necessity and the costs of the apparatus application of near-infrared spectroscopy is especially advantageous in laboratories with a substantial amount of samples to be analysed.

Ammonium acid fluoride (NH 4 F·xHF) has been identified as an alternative fluorinating agent for zircon, and may provide a method by which a wide variety of anhydrous metal fluorides can be synthesized. Data on the kinetics of the reaction of NH 4 F·xHF with plasma-dissociated zircon, combined with the thermodynamic parameters, are essential for the development of an industrial process for the production of a precursor for the manufacture of zirconium metal, viz. anhydrous ZrF 4 . The reaction yields (NH 4 ) 3 ZrF 7(s) and (NH 4 ) 2 SiF 6(s) , the latter forming volatile products at relatively low temperatures, affording easy separation of silicon from the zirconium compound.Another useful aspect of the process is the possibility of recycling, since the ammonia and hydrogen fluoride in the waste stream can be recombined, making them available for re-use as the acid fluoride. It was found that the reaction constant k'' varies exponentially with temperature at a set value of x, but linearly with changes in x at a set temperature. The activation energy for the digestion is between 20 and 47 kJ.mol -1 for the values of x investigated.

The separation of zirconium and hafnium, which is essential in the nuclear industry, is difficult due to the great similarities in their chemical and physical properties. In contrast to the traditional aqueous chloride separation systems, the current process focuses on dry fluoride-based technologies, which produce much lower volumes of chemical waste. In the present work, separation is achieved in both a sublimation and a desublimation step, where the Zr/Hf mole ratio varies between 160 and 245 across the length of desublimer and 86 to 40 within the sublimer. Model predictions for the sublimation/desublimation rates fit the experimental results well, with deviations becoming more apparent as sublimation proceeds. This may be attributed to crust formation preventing the system from reaching thermodynamic equilibrium. The model adequately predicts time-and temperature-dependent mole ratios of both the sublimer residue and of the desublimed mass. zirconium, hafnium, fluoride, sublimation, desublimation.

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