Particle Formation from Photooxidation of αpinene, Limonene, and Myrcene.

We present measurements of the effect of first-generation secondary organic aerosol (SOA) material on the growth of ∼10 nanometer diameter seed particles composed of sulfuric acid and water. Experiments were performed in an atmospheric pressure, vertically aligned flow reactor where OH was produced from HONO photolysis in the presence of either SO or a monoterpene. For typical conditions, organic compounds at ∼300 ppbv are exposed to photooxidation for a time of ∼80 s at a [OH] of about 6 × 10 cm: thus, oxidation products have minimal OH exposure.

Comparison of Line Tension Measurement Methods for Lipid Monolayers at Liquid-Liquid Coexistence.

Several methods of measuring the line tension between phase-separated liquid-ordered-liquid -disordered domains in phospholipid-cholesterol systems have been proposed. These experimental techniques are typically internally self-consistent, but the measured line tension values vary widely among these techniques. To date, no measurement of line tension has utilized multiple experimental techniques to look at the same monolayer system.

Comparison of cholesterol and 25-hydroxycholesterol in phase-separated langmuir monolayers at the air-water interface.

Langmuir monolayer studies combined with fluorescence microscopy provide powerful insights into the phase behavior of cholesterol and cholesterol analogue/phospholipid monolayer systems at the air-water interface. These studies have established the ability of cholesterol and similar molecules to condense the average molecular area of the monolayer as well as to laterally organize the monolayer into sterol-rich and sterol-poor regions. Oxysterols are one class of molecules that deserve particular attention due to their metabolic and physical effects on the membrane and the functioning of mammalian cells.