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En analyse bromatologique, la chromatographie sur couches minces classiques a ete appliquee jusqu'alors essentiellement a des separations de composes organiques. Il n'est pas douteux cependant, que l'utilisation de couches minces d'echangeurs d'ions puisse elargir encore le domaine d'application de cette methode, tout particulierement en expertise alimentaire. La separation et la caracterisation de nombreux ions mineraux toxiques ou frauduleux, tels que Pb, Hg, Cu, As, SCN, Fe (CN)6 ..., peuvent etre realisees a l'aide de cette methode, couplee eventuellement avec les procedes classiques de mineralisation et d'extraction par solvants ou avec des methodes plus modernes, telles que la radioactivation. La chromatographie sur couches multiples juxtaposees de nature differente doit permettre de realiser en une seule operation des analyses plus completes de melanges complexes de composes mineraux et organiques, en mettant en jeu successivement des phenomenes de partage, d'adsorption ou d'echange d'ions.

The propylester of p-methoxybenzylidene-p'-amino-α-methyl-cinnamic acid was obtained in two crystalline forms, one melting into a nematic phase at 55°C and the other at 67°C. Viscosities are the same in the nematicisotropic domain in the two cases. X-ray patterns of the two forms in the solid state are different. Conditions for the transformation have been studied by differntial thermal analysis.

Resume Des separations chromatographiques d'ions mineraux ont ete realisees sur des couches minces de resines ou de cristaux echangeurs d'ions et ont permis de resoudre avec succes des melanges d'anions et de cations de proprietes voisines, tels que les halogenures, les phosphates, les alcalins ou les alcalino-terreux. A l'aide de “couces multiples”, obtenues par juxtaposition de deux ou de plusieurs couches minces d'echangeurs differents, il a ete possible de separer successivement les anions et les cations, contenus dans les melanges de sels mineraux, tels que les halogenures alcalins ou alcalino-terreux. L'utilisation de radio-isotopes comme traceurs, au cours de ces experiences, a souvent facilite la detection de certains ions et la mise au point definitive des techniques chromatographiques correspondantes.

New analytical possibilities of chromatographic thin layers on flexible plastic support The use of chromatographic thin layers on flexible supports allows one to combine the advantages of both thin-layer chromatography and paper chromatography. In the laboratory, the practical realisation of thin layers on a film of ethylene polyterephthalat allows the use of many different substrates and chromatographic techniques. Two original analytical processes are proposed: two-dimensional fractional chromatography on large homogeneous thin layers, and one- or two-dimensional fractional chromatography on plates with three layers of different kinds placed side by side.

The self‐diffusion of silver has been studied in alloys containing 0.00, 1.49, 3.69, 9.87, and 21.84 atom percent palladium at four temperatures: 715.4, 799.4, 861.8, and 942.0°C. The rate decreases with increasing palladium atom fraction according to the relation: DAg=0.270e—8.20Xe—43, 700/RT. An alternative expression is DAg=0.270e—17.75T m/T. Within experimental error, the activation energy is independent of palladium content. The rate of self‐diffusion of silver is related to the solidus line of the silver‐palladium phase diagram, and a simple corresponding states explanation is given.

Peaks of internal friction associated with dislocations were studied under the same experimental conditions between 77–700°K, in the frequency range 5–50 kHz, on various metals: Copper, Aluminum, Nickel, Zirconium, Molybdenum. Experimental results show a close relationship, characteristic of each metal, between the height of peaks and the amount of prestrain at room temperature. These relations and the influence of successive annealings after cold-work, or of the additional elements for Zirconium, confirm the consequence of internal stresses on these peaks, in accordance with the Seeger-Pare theory for Bordoni peaks, and with the Hasiguti first model for peaks observed at higher temperature.

Petit J. La première excursion géographique interuniversitaire belge. In: Annales de Géographie, t. 30, n°168, 1921. pp. 454-456.

In the practice of artificial insemination in salmonids, efficiencyis usually poor since one male is used to fertilize only a few females. Some attempts have been made to improve the efficiency of artificial insemination, either by using minute quantities of sperm or by diluting sperm. The use of small quantities of sperm allows fertilization of 24 females by one male (Nursall and Hasler, 1952). Sperm dilution, which was performed in saline by Scheuring (1925) and Nomura (1964), has been reported to improve the percentage of fertilized eggs when compared with results obtained following fertilization by pure milt (Poon and Johnson, 1970; Plosila et al., 1972). Ginsburg (1968), however showed that the dry method was the most efficient. Lately, we showed that pH and osmotic pressure were the most important parameters for the diluant (Petit et al., 1973). In this study, effects of various parameters and components of the diluant on eggs, spermatozoa and percentage of fertilization are examined.