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.
Development of NMR: From the Early Beginnings to the Early 1990s
The sections in this article are 
 
 
1 
The Origins of NMR 
 
2 
NMR in Bulk Materials 
 
3 
NMR—A Tool for Chemical Studies 
 
4 
Further Developments in the Physics of NMR 
 
5 
NMR in Chemistry Comes of Age 
 
6 
Major Advances in NMR Technology 
 
7 
Fourier Transform NMR 
 
8 
High-Resolution NMR in Solids 
 
9 
Multinuclear Magnetic Resonance 
 
10 
Biochemical Applications of NMR 
 
11 
Two-Dimensional NMR 
 
12 
The Evolution of In Vivo NMR 
 
13 
Images by NMR 
 
14 
Protein Structures by NMR 
 
15 
NMR in Materials Science 
 
16 
Modern Biomedical Applications of NMR 
 
17 
Other Applications of NMR 
 
18 
Retrospective and Prospective 
 
19 
Acknowledgements 
 
20 
Biographical Sketches
Peritoneal eosinophils during intermittent peritoneal dialysis.
Peritoneal eosinophil counts were investigated in 61 intermittent dialysis patients over the course of 1 year. The peritoneal eosinophil percentage fell from 18 +/- 2% (mean +/- SEM) in the first 2 months of dialysis to 3 +/- 0.4% after 6 months of dialysis. Absolute eosinophils per cubic millimeter fell from 586 +/- 126 to 61 +/- 18 (p less than 0.01 for both percentage and absolute values). There was a wide range in the mean eosinophil percentages per patient in the first 6 months of dialysis (0-84%) that narrowed to 0-9% after 6 months. The majority of the high initial eosinophil counts resolved after 2 months. Peripheral eosinophilia was seen in 8 of the 10 patients with the highest mean peritoneal eosinophil percentages during the first 2 months of dialysis. Patients who developed peritonitis had a significantly lower percentage of eosinophils in the first 1.5 months of dialysis than patients who did not develop peritonitis. At the time of diagnosis of peritonitis, the peritoneal eosinophil count was near zero. 4 cases of peritoneal eosinophilia which developed after antibiotic therapy are described.