1. CAREER: Self-Assembly of Polyunsaturated Lipids and Cholesterol In The Cell Membrane. Linda S. Hirst, University of California-Merced, DMR 0852791 Phase separation phenomena in lipid mixtures may provide the mechanism for lipid sorting and raft formation in the living cell. Such phase separation into so called “liquid ordered (l o )” and “liquid disordered (l d )” phases can occur intrinsically in certain mixtures or as a photo-induced effect. We have recently looked at the formation of novel soft structures in lipid based materials. Forming banded lipid tubules and bilayer disc structures by inducing membrane phase separation. "Light induced Liquid Crystalline Phases in the Lipid Bilayer" J. Yuan and L.S. Hirst, Mol. Cryst. Liq. Cryst, in press (2009) "The effects of fluorescent probes on Model Membranes : Photo-induced lipid Sorting and Soft Structure Formation" L.S. Hirst and J. Yuan, Liquid Crystals 36,6, 739 (2009) "Lipid Bilayer Discs and Banded Tubules: Photo-induced Lipid Sorting in Ternary Mixtures” J. Yuan, S. M. Hira, G.F. Strouse, and L. S. Hirst,J. Am. Chem. Soc., 130 (6), 2067, (2008) These results demonstrate how photo-effects may be used to create custom lipid structures by spatially controlling membrane curvature. We have also carried out solution x-ray scattering studies at Brookhaven National Laboratory (National Synchrotron Light Source) on lipid mixtures containing cholesterol to explore the lipid raft phase diagram, developing a new technique to identify the presence of rafts in solution samples. "Studying Domain Formation in Ternary Lipid Mixtures with solution synchrotron x-ray diffraction” J. Yuan., A. Kiss, Y.H. Pramudya, L.T. Nguyen and L.S. Hirst PHYS. REV E, 79 (3) 031924 (2009) Model for the disc structure showing the distribution of the two phases and double labeled confocal images of a “disc instability” at different rotational angles confirming this structure and a phase separated lipid tubule. d f Synchrotron X-ray data (above) for cholesterol containing lipid mixtures demonstrates multiple bilayer thicknesses as rafts form at certain cholesterol concs. Below is shown a model for cholesterol distribution (blue) in the membrane at different concs.

2. CAREER: Self-Assembly of Polyunsaturated Lipids and Cholesterol In The Cell Membrane Linda S. Hirst, University of California-Merced, DMR 0852791 Softmatterworld.org website Linda Hirst is the author of the website softmatterworld.org. The goal of this site is to provide a focal point for the soft matter research community around the world and to inform students, educators and researchers of all levels about soft matter science. Soft Matter World includes all areas of soft matter physics, chemistry and materials science, covering everything from liquid crystals, polymers and gels to bio-molecular assembly and the interface between hard and soft condensed matter. This year we have developed the “highlighted research”, “highlighted research group” and a new monthly newsletter sent out to subscribers. The interactive “Google earth” map is a networking facility locating soft matter researchers and their groups around the world. Screenshots from softmatterworld.org Student Mentoring Prof. Hirst actively mentors a number of different students in her group. This year she has worked with 3 graduate students, two postdocs and five undergraduates from a variety of disciplines. The group is very diverse and typically about 50% female – very unusual for a physics group! Students working on an x-ray scattering experiment at Brookhaven Lab.