The gadolinium calcium silicates having the apatite crystal structure can accommodate a wide range of point defects, including oxygen and cation vacancies, as well as anti-site defects, depending on the Gd/Ca ratio. Compositions having only cation or oxygen vacancies were identified and the thermal diffusivity and conductivity were measured up to 1000C. All the compositions, including the stoic...

Density functional theory calculations indicate that the incorporation of V into Ti lattice positions of rutile TiO(2) leads to magnetic V(4+) species, but the extension and sign of the coupling between dopant moments confirm that ferromagnetic order cannot be reached via low-concentration doping in the non-defective oxide. Oxygen vacancies can introduce additional magnetic centres, and we show...

We are applying perturbed angular correlations (PAC) to study point defects near 111In probes in ordered B2 alloys. Systems studied include NiAl, CoAl, FeAl, CoGa and PdIn Ten different point defect configurations have been observed in annealed, quenched or mechanically-milled samples. The present status of this work is summarized. Systematics of hyperfine interactions of vacancy defects are th...

We give a parameterization, using Jacobi’s elliptic functions, of Alfred Gray’s Elliptical Catenoid and Elliptical Hellicoid that avoids some problems present in the original depiction of these surfaces.

The role of various types of defects in establishing the magnetic properties of the C60-based polymers and the single-wall carbon nanotubes is investigated. Comparing the role of carbon vacancies, and that of substitutional impurity atoms X X=N, B, O, Si, P, and S in establishing a magnetic ground state it is found that the impurity X atoms promote the spin density delocalization, whereas its l...

In this paper, we report on the refractive index changes and vacancies that are induced in silica glass by the irradiation of ultrashort laser pulses. We fabricated waveguides, couplers, and gratings by the filamentation of femtosecond laser pulses. We demonstrate the formation and the movement of sub-micrometer or nanometer vacancies, called voids. We show the formation of three-dimensional sh...

We determine the energy barrier height for the formation of positively charged phosphorus vacancies in InP~110! surfaces using the rate of formation of vacancies measured directly from scanning tunneling microscope images. We found a barrier height in the range of 1.15–1.21 eV. The barrier height decreases with increasing carrier concentration. These results are explained by a charge separation...

Background: Semi-recumbent cycling exercise has been used as a strategy to complement gait retraining in individuals with disordered walking ability. However, seated elliptical stepping might be a more potent exercise modality for this purpose. Yet, there has not been a kinematic analysis of elliptical stepping exercise, whereby the movement path is produced by a slider-crank mechanism. This st...