The phase behavior of mixed lipid dispersions representing the inner leaflet of the cell membrane has been characterized by X-ray diffraction. Aqueous dispersions of phosphatidylethanolamine:phosphatidylserine (4:1 mole/mole) have a heterogeneous structure comprising an inverted hexagonal phase H(II) and a lamellar phase. Both phases coexist in the temperature range 20-45 degrees C. The fluid-t...

The self-consistent field theory (SCFT) complemented with the Poisson-Boltzmann equation is employed to explore self-assembly of polyelectrolyte copolymers composed of charged blocks A and neutral blocks B. We have extended SCFT to dissociating triblock copolymers and demonstrated our approach on three characteristic examples: (1) diblock copolymer (AB) melt, (2) symmetric triblock copolymer (A...

Nanocrystals of hexagonal nickel carbide have been synthesized via physical vapor deposition of elemental nickel onto the surface of vertically aligned carbon nanotubes. Combining highresolution transmission electron microscopy (HRTEM) with three-dimensional atom probe tomography (3DAP) confirmed that these nanocrystals have a hexagonal structure, are enriched in carbon, and have a composition ...

A quenchable superhard high-pressure carbon phase was synthesized by cold compression of carbon nanotubes. Carbon nanotubes were placed in a diamond anvil cell, and x-ray diffraction measurements were conducted to pressures of approximately 100 GPa. A hexagonal carbon phase was formed at approximately 75 GPa and preserved at room conditions. X-ray and transmission electron microscopy electron d...

Recent publications have reported the presence of hexagonal phases in Si nanowires. Most of these reports were based on 'odd' diffraction patterns and HRTEM images—'odd' means that these images and diffraction patterns could not be obtained on perfect silicon crystals in the classical diamond cubic structure. We analyze the origin of these 'odd' patterns and images by studying the case of vario...

The ability of calcium to induce phase separation in multicomponent lipid mixtures containing various unsaturated species of acidic and neutral phospholipids has been investigated by 31P NMR, 3H NMR, and small-angle X-ray diffraction techniques. It is shown that, in unsaturated (dioleoyl-) phosphatidylglycerol (PG)/phosphatidylethanolamine (PE) (1:1) and phosphatidic acid (PA)/phosphatidylcholi...

Lyotropic liquid crystal systems, such as reversed bicontinuous cubic and hexagonal mesophases, are attracting more and more attention because of their unique microstructures and physicochemical properties. Various bioactive molecules such as chemical drugs, peptides and proteins can be solubilized in either aqueous or oil phase and be protected from hydrolysis or oxidation. Furthermore, severa...

Small angle x-ray analyses show that the shear-induced hexagonal perforated layer phase in a poly(ethylene oxide)- b-polystyrene diblock copolymer consists of trigonal (R3;m) twins and a hexagonal (P6(3)/mmc) structure, with trigonal twins being majority components. Transmission electron microscopy reveals that the hexagonal structure is generated through sequential intrinsic stacking faults on...

Hexagonal patterns of gold nanorods were made by assembling gold nanorod-coated poly(N-isopropyl acrylamide) microgels. The required population of nanorods on the microgels was achieved by attaching nanoparticle seeds on the latter and growing them to nanorods. The various materials prepared were characterized by UV-vis spectroscopy and transmission electron microscopy. Similar experiments with...

Hexagonal (Gd0.95RE0.05)PO4·nH2O nanowires ~300 nm in length and ~10 nm in diameter have been converted from (Gd0.95RE0.05)2(OH)5NO3·nH2O nanosheets (RE = Eu, Tb) in the presence of monoammonium phosphate (NH4H2PO4) and ethylene diamine tetraacetic acid (EDTA). They were characterized by X-ray diffraction, thermogravimetry, electron microscopy, and Fourier transform infrared and photoluminescen...