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SummaryFouling caused by sweet whey, milk, artificial ultrafiltrate, phosphate and calcium solution and prote in solutions was studied in weil defined hydrodynamic (flow rate: 0.096 m.s -1) and thermal conditions (temperatures ranging from 25 to 88 "C with a standard value of 72 "C ; temperature difference with the heat carrier fluid : 0, 5 or 10 "C) using a laboratory fouling deviee. Deposits were assessed quantitatively by weighing and qualitatively by Auger electron spectrocopy, X photoelectron spectroscopy and infrared spectroscopy. These spectra gave evidence for three main groups of compounds:proteins, phosphates and lipids as weil as the corresponding atoms (calcium, phosphorus, nitrogen and carbon). These findings suggest a fouling mechanism based on calcium phosphate building-up, with various structures ranging from simple weil crystallized phases «< phosphate + calcium» solution) to much more complex phases including carboxylate groups ; the latter are present in substances as different as citrate (artificial ultrafiltrate and whey) or proteins (soluble or caseins). In the case of milk and whey, proteins participate in the formation of the first fouling layers. Thus, the best way of preventing fouling seems to be the inhibition of calcium phosphate formation.

Energy distribution curves of photoemitted electrons are obtained for SnSe thin polycrystallino films in the 10 to 40 eV energy range. The method of preparation of the sample under ultrahigh vacuum conditions is described and the synthesis of the initial material. The quality of the sample is checked by Auger analysis which reveals a weak reactivity of the material. The EDC's show structures appearing a t 0.9, 2.1 to 2.7, 3.9, 7.4 eV below the top of the valence band. Also the Sn 4d levels are investigated. The 4d(5/2) is found a t 24.3 eV and the 4d(3/2) a t 25.3 eV below the top of the valence band. Structures in the EDC's are compared with those of existing similar works and are interpreted by means of theoretical bands scheme.Les courbes de distribution CnergCtique des Blectrons photoBmis ont 6tk obtenues pour des couches minces polycristallines de SnSe dans la rkgion 10 8, 40 eV. Nous dCcrivons la mCthode de pr6paration de 1'6chantillon sous ultra-vide et la synthhe du matkriau de d6part. La qualit6 de l'kchantillon est contr6lBe par analyse Auger qui rBvde une faible rkactivitk dn matkriau. Les EDC montrent des structures apparaissant L 0,9; 2,l 8, 2,7; 3,9; 7,4 eV en dessous du haut de la bande de valence. Nous avons aussi BtudiC les niveaux 4d de 1'6tain. Nous nvons trouvB les 4d(5/2) a 24,3 eV et les 4d(3/2) A 25,3 eV en dessous du sommet de la bande de valence. Les structures dans les EDC sont comparbes avec celles de travaux similaires existant et sont interprBtkes nu moyen de schkmas dea bandes thhoriques. l)

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