A pulsed low resolution NMR study on crystallization and melting processes of cocoa butter
Pulsed low resolution nuclear magnetic resonance (NMR) was employed to measure the «melting» curves of different series of cocoa butter samples. The samples were prepared from completely liquid phase by cooling and tempering them at different temperatures Tc for varying time Δt. The «melting» curves were measured while keeping the sample at a fixed temperature Tm. The complex shape of each curve was interpreted in terms of cocoa butter polymorphism, and the results were compared with data obtained by other techniques available in the literature. Using just two tempering temperatures (+7 C and −18C), we were able to distinguish four solid phases and identify them with the phases II, III, IV, and V described in literature. Our data are in full agreement with literature. Several novel results have been also found. These include the kinetic constants of the melting processes of phases II and III, the rate constants of solidification of phase V, the conversion of phase III into phase IV before melting at temperatures ≥30 C, and the growth of phase V out of phase II at −18 C (including the rate constant of this process). We are convinced that NMR may serve as a principal tool in fat polymorphism investigations, especially if it is combined with other techniques such as differential scanning calorimetry. Its advantage, apart from rapidity of measurement, is the fact that the measurement itself does not interfere with the melting or solidification process studied. On the other hand, it does not distinguish in a direct way between different solid phases present in the sample; this can be done only in inference from the behavior upon melting.
Ultrasonic estimation of solid/liquid ratios in fats, oils and adipose tissue
Data are presented for the speed of transmission of pulses of 2.5 MHz ultrasound through fats and oils at temperatures in the range −50 to +110°C. It is suggested that a measurement of the speed of ultrasound (V), which is greater in solid fats (Vs) than in oils (VL), might be used to provide an estimate of the proportion of solid in a partially solidified fat. An acoustic parameter ϕ is defined such that: 
 
 
 
 
 
 
and it is suggested that ϕ might be used as a practical index for determination of the volume fraction of solid fat. This procedure might be useful under conditions unsuited to the established methods of dilatometry, calorimetry or nuclear magnetic resonance. As an example of a possible application, measurements are presented for the speed of ultrasound in pig adipose tissues selected to show a range of consistencies which, by subjective assessment and by penetrometer measurements, ranged from ‘soft’, and therefore unsuited for the manufacture of bacon, to ‘hard’. After allowing for the contribution of the fat-free tissue, it was estimated that the lipid in the tissues ranged from about 20 to 88% (by volume) solid. The variation in ϕ explained 88% of the variance in the penetrometer measurements.
Magnetic properties of Lu2Fe17 crystals
Abstract We present the results of crystal structure and magnetization studies of three single crystals grown from melts of different nominal compositions in the vicinity of the Lu2Fe17 stoichiometry. The ferromagnetic state of the crystals is strongly dependent on the real sample composition and the local atomic ordering. A drastic difference is observed in the behaviour of the ferro–antiferromagnetic transition, even in crystals for which almost identical composition and crystal parameters were determined by microprobe and X-ray analysis.