Lutein is the one of the main xanthopyll pigments found in the membranes of the macula lutea of the primate vision apparatus. The two functions of lutein have been studied experimentally: protection against oxidative damage of the lipid matrix [1] and screening against excess radiation [2]. This latter function depends on the molecular organisation, i.e. orientation and aggregation of lutein. T...

The electron-hole pair created via photon absorption in organic photoconversion systems must overcome the Coulomb attraction to achieve long-range charge separation. We show that this process is facilitated through the formation of excited, delocalized band states. In our experiments on organic photovoltaic cells, these states were accessed for a short time (<1 picosecond) via infrared (IR) opt...

Small-angle X-ray scattering (SAXS) measurements reveal a striking difference in intermolecular interactions between two short highly charged peptides-deca-arginine (R10) and deca-lysine (K10). Comparison of SAXS curves at high and low salt concentration shows that R10 self-associates, while interactions between K10 chains are purely repulsive. The self-association of R10 is stronger at lower i...

Many naturally occurring peptides containing cationic and hydrophobic domains have evolved to interact with mammalian cell membranes and have been incorporated into materials for non-viral gene delivery, cancer therapy or treatment of microbial infections. Their electrostatic attraction to the negatively charged cell surface and hydrophobic interactions with the membrane lipids enable intracell...

Perforin, a pore-forming protein secreted by cytotoxic lymphocytes, is indispensable for destroying virus-infected cells and for maintaining immune homeostasis. Perforin polymerizes into transmembrane channels that inflict osmotic stress and facilitate target cell uptake of proapoptotic granzymes. Despite this, the mechanism through which perforin monomers self-associate remains unknown. Our cu...

A self-consistent density-functional approach is presented for describing the phase behaviour and interfacial tensions of van der Waals fluids represented by the hard-core Yukawa (HCY), Lennard-Jones (LJ) and square-well (SW) potentials. The excess Helmholtz energy functional is formulated in terms of a modified fundamental measure theory (MFMT) for the shortranged repulsion and a density-gradi...

Strong, short-ranged positional correlations involving counterions can induce a net attractive force between negatively charged strands of DNA and lead to the formation of ion pairs in dilute ionic solutions. However, the long range of the Coulomb interactions impedes the development of a simple local picture. We address this general problem by mapping the properties of a nonuniform system with...

Anthraquinone molecules self-assemble on a Cu(111) surface into a large two-dimensional honeycomb network (square root of 304 x square root of 304)R23 degrees with pore diameters of approximately 50 A. The spontaneous formation of a pattern containing pores roughly five times larger than the size of the constituent molecules is unprecedented. The network originates from a delicate balance betwe...

Ab initio and density functional theory calculations are used to examine complexes formed between H2CO and H2CS with 1, 2, and 3 molecules of SO2. The nature of the interactions is probed by a variety of means, including electrostatic potentials, natural bond orbital, atoms in molecules, energy decomposition, and electron density redistribution maps. The dimers are relatively strongly bound, wi...

Antiferro- and ferro-electric ordering has been discovered in orthogonal smectic phases composed of nonchiral bent-core molecules. These systems are the only proper fluid ferroelectrics confirmed experimentally so far. We consider a molecular theory of proper ferroelectric ordering in isotropic, nematic and smectic A phases and conclude that the delicate balance between the tendencies for local...