Nucleation of Surfactant-Alkane Mixed Solid Monolayer and Bilayer Domains at the Air-Water Interface.

We investigated the wetting transitions of tetradecane and hexadecane droplets in dodecyltrimethylammonium bromide (C12TAB), tetradecyltrimethylammonium bromide (C14TAB), and hexadecyltrimethylammonium bromide (C16TAB) aqueous solutions. By varying the surfactant concentration, the formation of mixed monolayers of a surfactant and an alkane was observed at the air-water interface. Depending on the combination of surfactant and alkane, these wetting monolayers underwent another thermal phase transition upon cooling either to a frozen mixed monolayer (S1) or a bilayer structure composed of a solid monolayer of a pure alkane rested on a liquid-like mixed monolayer (S2). Based on the phase diagrams determined by phase modulation ellipsometry, the difference in the morphology of the nucleated S1 and S2 phase domains was also investigated using Brewster angle microscopy. Domains of the S1 phase were relatively small and highly branched, whereas those of the S2 phase were large and circular. The difference in domain morphology was explained by the competition of the domain line tension and electrostatic dipole interactions between surfactant molecules in the domains.

Threshold dose of cow's milk in sensitization to casein higher than those of casein and ß-lactoglobulin in children with cow's milk allergy.

BACKGROUND: Recent treatment for food allergies involves the intake of allergy-causing foods at doses lower than the threshold dose determined by the oral food challenge (OFC). For a more successful treatment, it is necessary to identify a biomarker to establish safer doses of allergens in foods consumed at home. OBJECTIVE: In this study, we aim to investigate whether the pattern of sensitization to cow's milk (CM) is related to the threshold dose of CM. METHODS: Fifty patients with sensitization to casein (casein-specific IgE titer ≥ 0.7 UA/ml) and who have undergone the CM OFC test from July 2013 to July 2015 were enrolled. They were examined for the presence or absence of sensitization to ß-lactoglobulin (BLG) (BLG-specific IgE ≥ 0.7 UA/ml). They were divided into two groups, namely, the only-casein-specific IgE-positive (C) group, and both casein- and BLG-specific IgE-positive (C + B) group. RESULTS: The C group had 26 patients and the C + B group had 24. Both the CM- and casein-specific IgE titers were higher in the C + B group than in the C group. The positivity rates determined from OFC test results were 53.8 and 87.5%, and the threshold doses of CM were 88.7 and 31.1 ml in the C and C + B groups, respectively. In patients with low casein-specific IgE titers (≤ 10 UA/ml), the C + B group showed a significantly lower threshold dose of CM than the C group. CONCLUSIONS: Our results suggest that children with CM allergy sensitized to casein alone have a higher threshold dose than those sensitized to both casein and BLG.