Materials Literature
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We have prepared samples of nominal type Ba 8 Cu x Ge 46− x by induction melting and solid state reaction. Analysis shows that these materials form type-I clathrates, with a copper content between x = 4.9 and 5.3, nearly independent of the starting composition. We used x-ray powder diffraction and single-crystal elect…
The microstructure in Y 2 O 3 ‐stabilized tetragonal zirconia polycrystal (Y‐TZP) sintered at 1300°–1500°C was examined to clarify the role of Y 3+ ions on grain growth and the formation of cubic phase. The grain size and the fraction of the cubic phase in Y‐TZP increased as the sintering temperature increased. Both t…
Progress in tissue-engineering research has renewed optimism about the possibility of constructing a physiologically functional blood vessel substitute in the laboratory. To this end, we have explored the use of defined mechanical stimulation to further the development of vascular tissue analogs. We now report our fin…
We present first-principles transport calculations for ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}$ using the linearized-augmented plane-wave method and the relaxation time approximation. We considered the effects of hydrostatic pressure and uniaxial stress up to 4 GPa. Doping was included for electrons and holes at levels up…
It is shown that in a heterostructure where screening is eliminated, the Ampére-Maxwell law of electrodynamics implies that a dc or ac spinomotive force can be inudced with a time rate of change of a transverse electric field, and the magnetic analog of Ampére law implies that a dc or ac spin current can generate a tr…
Challenges facing the scaling of microelectronics to sub-50 nm dimensions and the demanding material and structural requirements of integrated photonic and microelectromechanical systems suggest that alternative fabrication technologies are needed to produce nano-scale devices. Inspired by complex, functional, self-as…
Contrasting magnetic properties were obtained from bulk Mn-doped ZnO synthesized under different processing conditions. While a ferrimagnetic phase transition was observable in a Zn0.95Mn0.05O sample processed at 1170 K, no such transition was found for a sample with the same composition processed at 1370 K. The detai…
We deposited graded-index SiO2 films using glancing angle deposition to produce high-transmission antireflection coatings on glass. Because of the accurate control over the thin-film microstructure provided by this technique, we were able to create graded densities with a Gaussian profile resulting in transmission val…
This account describes the synthesis, characterization, and applications to catalysis of dendrimer-encapsulated metal nanoparticles (DEMNs). These materials are synthesized by a template approach in which metal ions are sorbed into the interior of dendrimers and then subsequently chemically reduced to yield nearly siz…
We analyzed samples of antigorite, lizardite and fibrous chrysotile, three representative minerals of the serpentine group, to determine their chemical and structural properties, and their FT-Raman spectra. The low-frequency region of the spectrum (1200– 200 cm –1 ), which corresponds to the lattice-vibration modes, w…
At high temperatures, SiC and Si 3 N 4 react with water vapor to form a SiO 2 scale. SiO 2 scales also react with water vapor to form a volatile Si(OH) 4 species. These simultaneous reactions, one forming SiO 2 and the other removing SiO 2 , are described by paralinear kinetics. A steady state, in which these reaction…
Temperature-dependent rf-ion trap mass spectrometry and first-principles simulations reveal the detailed reaction mechanism of the catalytic gas-phase oxidation of CO by free Au(2)(-) ions in the presence of O(2). A metastable intermediate with a mass of Au(2)CO(3)(-) was observed at low temperatures. Two alternative…
Current state‐of‐the‐art environmental barrier coatings (EBCs) for Si‐based ceramics consist of three layers: a silicon bond coat, an intermediate mullite (3Al 2 O 3 ·2SiO 2 ) or mullite + BSAS ((1− x )BaO· x SrO·Al 2 O 3 ·2SiO 2 , 0 ≤ x ≤ 1) layer, and a BSAS top coat. Areas of concern for long‐term durability are en…
A geometrical probability measure is proposed for calculating the effective conduction electron mean free path of an arbitrary shape convex particle. It is shown that the plasmon widths determined from this mean free path are consistent with exact quantum mechanical widths for simple particle shapes. We use the mean f…
To enhance the insulating properties of a thermal barrier coating, one has to focus on new materials with lower intrinsic thermal conductivity than established yttria‐stabilized zirconia. Substances with pyrochlore structure were investigated. Starting from lanthanum zirconate, substitutions of the lanthanum by other…
Structural investigations by using high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) of silver nanodisks with different sizes are presented. The disks have a face centered cubic (fcc) crystal structure and their flat surfaces are (111). Stacking faults parallel to t…
Wide band gap semiconductor nanostructures with near-cylindrical geometry and large dielectric constants exhibit two-dimensional ultraviolet and visible photonic confinement (i.e., waveguiding). Combined with optical gain and suitable resonant feedback, the waveguiding behavior facilitates highly directional lasing at…
PURPOSE: To label mammalian and stem cells by combining commercially available transfection agents (TAs) with superparamagnetic iron oxide (SPIO) magnetic resonance (MR) imaging contrast agents. MATERIALS AND METHODS: Three TAs were incubated with ferumoxides and MION-46L in cell culture medium at various concentratio…
The present mechanistic understanding and practical implications of carbon dioxide (CO2) corrosion of carbon and low-alloy steels in hydrocarbon production have been reviewed. This is based on the fact that CO2 corrosion is by far the most prevalent form of attack encountered in upstream operations. The intent of the…
The particular demands of aerospace engineering have spawned many of the developments in the field of adaptive structures. Shape memory alloys are particularly attractive as actuators in these types of structures due to their large strains, high specific work output and potential for structural integration. However, t…