New materials capable of separating mixtures of saturated, unsaturated, and aromatic hydrocarbons can enable more efficient industrial processes and cleaner energy. Outstanding challenges in hydrocarbon separations stem from the similar structures, properties, and reactivities of the molecules comprising many of these mixtures. With high surface areas, tunable pore geometries, and adjustable su...

A Monte Carlo dynamics study of the motions of hydrocarbon chains containing cis double bonds is presented. The simulations utilize the high-coordination {2 1 0) lattice for the simultaneous representation of the tetrahedrally bonded carbon atoms and the planar unsaturated segment. Results on single chains undergoing free motion in space and tethered to an impenetrable planar interface are repo...

The interactions of various acyclic and cyclic hydrocarbons in both saturated and unsaturated forms with the carbon nanostructures (CNSs) have been explored by using density functional theory (DFT) calculations. Model systems representing armchair and zigzag carbon nanotubes (CNTs) and graphene have been considered to investigate the effect of chirality and curvature of the CNSs toward these in...

Tissues fixed in osmium tetroxide or in combined osmium and glutaraldehyde (Hinde), embedded in Spurr's medium, cut at 0-5-I mum and mounted in Farrants' gum medium containing ethyl gallate, show good staining of lipid-contaning structures (droplets of triglyceride, membranes, mitochondria, etc.) in the light microscope. Such preparations show moderate contrast in the electron microscope withou...

Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K(C), the thickness D(HH), and the orientational order parameter S(xray) of lipid bilayers. We find that the effects are different for at least three classes of phospholipids characterized by different numbers of ...

The limits of a recently proposed computer method for finding all distinct substructures of a chemical structure are systematically explored within comprehensive graph samples which serve as supersets of the graphs corresponding to saturated hydrocarbons, both acyclic (up to n = 20) and (poly)cyclic (up to n = 10). Several pairs of smallest graphs and compounds are identified that cannot be dis...

Phase separation in lipid bilayers that include negatively charged lipids is examined experimentally. We observed phase-separated structures and determined the membrane miscibility temperatures in several binary and ternary lipid mixtures of unsaturated neutral lipid, dioleoylphosphatidylcholine (DOPC), saturated neutral lipid, dipalmitoylphosphatidylcholine (DPPC), unsaturated charged lipid, d...

In this work, we developed an interatomic potential for saturated hydrocarbons using the modified embedded-atom method (MEAM), a reactive semi-empirical many-body potential based on density functional theory and pair potentials. We parameterized the potential by fitting to a large experimental and first-principles (FP) database consisting of (1) bond distances, bond angles, and atomization ener...