ABSTRACT
The freezing of supercooled water films on different substrates was investigated using a high-speed camera coupled to an optical microscope, obtaining details of the freezing process not described in the literature before. We observed the two well known freezing stages (fast dendritic growth and slow freezing of the water liquid left after the dendritic growth), but we separated the process into different phenomena that were studied separately: two-dimensional dendrite growth on the substrate interface, vertical dendrite growth, formation and evolution of ice domains, trapping of air bubbles and freezing of the water film surface. We found all of these processes to be dependent on both the supercooling temperature and the substrate used. Ice dendrite (or ice front) growth during the first stage was found to be dependent on thermal properties of the substrate but could not be unequivocally related to them. Finally, for low supercooling, a direct relationship was observed between the morphology of the dendrites formed in the first stage, which depends on the substrate, and the roughness and the shape of the surface of the ice, when freezing of the film was completed. This opens the possibility of using surfaces and coatings to control ice morphology beyond anti-icing properties.
ABSTRACT
On the basis of information received from 128 medical wards, the frequency of gastric analysis (test meal) used as a clinical diagnostic procedure, the spreading of the different methods and other problems connected with the examination are analysed. In about 3/4 of the institutions the test meal is performed in patients with all kinds of gastric complaint. This incidence decreases to 50% if the X-ray finding is positive. As acid-stimulants caffeine and a moderate dose of histamine are used most frequently. Of the data supplied by the test meal, the value for acid concentration (acidity) is registered by most of the examiners. The authors consider it as suprising that outdated methods such as a qualitative lactic acid assay (47%), isolation of Boas-Oppler's bacillus (25%) and of sarcinas (21%) are still in frequent use. The data are compared to the results of a similar survey made in England.
