Based on first-principles density-functional calculations, we present the structure and diffusion of boron in amorphous silica, as well as in crystalline silica for comparison purpose. We find that incorporation of a boron atom into the amorphous silica matrix results in various minimum-energy configurations with and without oxygen deficient centers, and also the B-related defects can undergo i...

Surface defects are known to dominate both the electronic and chemical properties of metal oxide surfaces, an object of much study for use in catalytic processes. In order to study surface chemistry in detail, an ultra-high vacuum (UHV) chamber was designed to combine a LEED and STM system. Construction is underway, with a reported initial base pressure of 10−9 Torr revealing no major leaks. On...

In tissue with a distinct orientation of the oxygen supplying structures, the capillaries, a mathematical description of oxygen transport is feasible in terms of two-dimensional diffusion in a plane perpendicular to the capillaries. Muscle tissue is an example of a highly anisotropic tissue. With some additional simplifying assumptions, a solution can be constructed in terms of capillary source...

Oxygen permeability and water diffusion characteristics were determined for several types of hydroxyethyl-methacrylate hydrophilic contact lenses and a silicone contact lens material. A twoto fourfold difference in the diffusion rates for capillary flow of water was found among the different hydrophilic lenses. Oxygen permeability studies demonstrate that the hydrophilic lenses are capable of t...

We report on the mechanism and energy barrier for oxygen diffusion in tetragonal La(2)CoO(4+δ). The first principles-based calculations in the Density Functional Theory (DFT) formalism were performed to precisely describe the dominant migration paths for the interstitial oxygen atom in La(2)CoO(4+δ). Atomistic simulations using molecular dynamics (MD) were performed to quantify the temperature ...

Myoglobin, an intracellular iron containing protein that binds oxygen reversibly, has been shown in model systems to facilitate the diffusion of oxygen and thereby maintain the mechanical function of exercising canine skeletal muscle and of hypoxic benthic fish hearts. Since no such role has yet been established for mammalian cardiac muscle small diameter (less than or equal to 0.70 mm) isolate...

We report on the mechanism and energy barrier for oxygen diffusion in tetragonal La2CoO4+d. The first principles-based calculations in the Density Functional Theory (DFT) formalism were performed to precisely describe the dominant migration paths for the interstitial oxygen atom in La2CoO4+d. Atomistic simulations using molecular dynamics (MD) were performed to quantify the temperature dependen...

The problem of how oxygen is transferred from lung alveoli to blood was considered in 1909 by Christian Bohr,' who used the calculus to develop the appropriate equation for the diffusion of oxygen from alveoli into blood and presented a graphical solution. In this way, the integrated mean oxygen pressure gradient causing oxygen transfer across the alveolar membranet was obtainable and, in addit...

Using density functional theory (DFT) calculations, we investigated oxygen vacancy diffusion and aggregation in relation to dielectric breakdown in amorphous silicon dioxide (a-SiO2). Our calculations indicate the existence of favourable sites for the formation of vacancy dimers and trimers in the amorphous network with maximum binding energies of approximately 0.13 eV and 0.18 eV, respectively...

The study of cardiac energetics commonly involves the use of isolated muscle preparations (papillary muscles or trabeculae carneae). Their contractile performance has been observed to vary inversely with thickness. This inverse dependence has been attributed, almost without exception, to inadequate diffusion of oxygen into the centers of muscles of large diameter. It is thus commonly hypothesiz...