Mechanical Behavior of Titanium Based Metal Matrix Composites Reinforced with TiC or TiB Particles under Quasi-Static and High Strain-Rate Compression.

The mechanical behavior of titanium alloys has been mostly studied in quasi-static conditions when the strain rate does not exceed 10 s, while the studies performed in dynamic settings specifically for Ti-based composites are limited. Such data are critical to prevent the "strength margin" approach, which is used to assure the part performance under dynamic conditions in the absence of relevant data. The purpose of this study was to obtain data on the mechanical behavior of Ti-based composites under dynamic condition.

Ultrahigh vacuum dc magnetron sputter-deposition of epitaxial Pd(111)/AlO(0001) thin films.

Pd(111) thin films, ∼245 nm thick, are deposited on AlO(0001) substrates at ≈0.5, where is the Pd melting point, by ultrahigh vacuum dc magnetron sputtering of Pd target in pure Ar discharges. Auger electron spectra and low-energy electron diffraction patterns acquired from the as-deposited samples reveal that the surfaces are compositionally pure 111-oriented Pd.

Monolithic InGaAs Nanowire Array Lasers on Silicon-on-Insulator Operating at Room Temperature.

Chip-scale integrated light sources are a crucial component in a broad range of photonics applications. III-V semiconductor nanowire emitters have gained attention as a fascinating approach due to their superior material properties, extremely compact size, and capability to grow directly on lattice-mismatched silicon substrates. Although there have been remarkable advances in nanowire-based emitters, their practical applications are still in the early stages due to the difficulties in integrating nanowire emitters with photonic integrated circuits.

High-Quality InAsSb Nanowires Grown by Catalyst-Free Selective-Area Metal-Organic Chemical Vapor Deposition.

We report on the first demonstration of InAs1-xSbx nanowires grown by catalyst-free selective-area metal-organic chemical vapor deposition (SA-MOCVD). Antimony composition as high as 15 % is achieved, with strong photoluminescence at all compositions. The quality of the material is assessed by comparing the photoluminescence (PL) peak full-width at half-max (fwhm) of the nanowires to that of epitaxially grown InAsSb thin films on InAs.

Distribution and chemical speciation of arsenic in ancient human hair using synchrotron radiation.

Pre-Columbian populations that inhabited the Tarapacá mid river valley in the Atacama Desert in Chile during the Middle Horizon and Late Intermediate Period (AD 500-1450) show patterns of chronic poisoning due to exposure to geogenic arsenic. Exposure of these people to arsenic was assessed using synchrotron-based elemental X-ray fluorescence mapping, X-ray absorption spectroscopy, X-ray diffraction and Fourier transform infrared spectromicroscopy measurements on ancient human hair. These combined techniques of high sensitivity and specificity enabled the discrimination between endogenous and exogenous processes that has been an analytical challenge for archeological studies and criminal investigations in which hair is used as a proxy of premortem metabolism.

Electron microscopic demonstration and evaluation of irreversible electroporation-induced nanopores on hepatocyte membranes.

Purpose: To demonstrate, evaluate, and verify the existence of irreversible electroporation (IRE)-ablation induced nanopores on the plasma membrane of hepatocytes.

Materials And Methods: On animal research committee approval, four New Zealand rabbits and two Yorkshire swine underwent IRE ablation of the liver (90 pulses, 100 μs per pulse at 2,500 V), and selected ablated liver tissues were harvested, fixed, and air-dried according to the electron microscopy (EM) protocol. A scanning electron microscope (SEM; Nova 230 NanoSEM [FEI, Hillsboro, Oregon] with 80 picoamperes and 10-kV acceleration) was used to visualize and verify IRE-created nanopores.

Three-dimensional morphology control during wet chemical synthesis of porous chromium oxide spheres.

Controlling the morphological evolution in nanostructures is essential for improving their functionality, for example, in catalysis. Here, we demonstrate, using chromium oxide as a model system, that morphologies of functional binary oxide particles can be tailored by an efficient template-free synthetic approach. We construct a morphological "phase diagram" for chromium oxide spheres that shows the evolution of size and surface roughness as a function of the precursor and urea concentrations.

Nanostructure manipulation device for transmission electron microscopy: application to titania nanoparticle chain aggregates.

Experimental difficulties in studying nanostructures stem from their small size, which limits the use of traditional techniques for measuring their physical properties. We have developed a nanostructure manipulation device to apply tension to chain aggregates mounted in a transmission electron microscope. A 1-mm-long slit was cut in the center of a lead-tin alloy disc, measuring 3 mm in diameter and 200 microm in thickness.