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GaN nanorods have drawn attention as possible crystalline structures on which to form InGaN active regions for LEDs, making use of the m-planes that form the sidewalls of the rods. In this paper, we describe such nanorods as well as nanosheets with increased m-plane surface area formed on c-plane sapphire. Non polar crystalline planes on nanorods and nanosheets are expected to lead to more efficient LEDs by enabling the formation of higher efficiency nonpolar active regions in three dimensional structures. The potential for increased efficiency derives from the reduction of quantum well band structure distortion that results from their formation on non-polar planes as well as the increase in the junction active area per chip by the inherent three dimensional nature of the nanostructures. Three dimensional active areas that are an order of magnitude greater than the chip area will reduce the current density at a given drive current and reduce the effects of efficiency “droop”. This increase is expected to add to efficiency improvements that derive from quantum wells on non-polar planes.

Purpose: The aim of this prospective study was to evaluate the effectiveness of preconditioning molecular adsorbent recirculating system (MARS) treatment on patients with acute-on-chronic liver failure (AoCLF), who were awaiting living donor liver transplantation (LDLT). Patients and methods: Between January and December 2001, 10 consecutive AoCLF patients (with progressive hyperbilirubinemia (>20 mg/dl) and hepatic encephalopathy grade ≥2) were studied. MARS was used in eight of these patients who were evaluated for LDLT during 2001. Three AoCLF patients who received LDLT before clinical use of MARS were used as historical controls. Results: Because of a shortage of donors, only five out of 10 patients considered for LDLT could receive transplants. Three patients were treated with MARS for 8 h the day before receiving LDLT, and all three survived. The remaining two patients who received transplants, and who were not pretreated with MARS, died from sepsis and multi-organ failure within 2 weeks. Four of the patients who did not receive transplants because of donor shortage died despite 1 or 3 MARS treatments, however bilirubin levels and grade of encephalopathy were significantly reduced in these patients. Conclusions: Results of this small pilot study suggest that MARS, by reducing the severity of jaundice and encephalopathy, might be effective as a bridging option in AoCLF patients awaiting LDLT.

Severe plastic deformation (SPD) is an attractive processing method for refining microstructures of metallic materials to give ultrafine grain sizes within the submicrometer to even the nanometer levels. Experiments were conducted to discuss the evolution of hardness, microstructure and strain rate sensitivity, m, in a Zn-22% Al eutectoid alloy processed by high- pressure torsion (HPT). The data from microhardness and nanoindentation hardness measurements revealed that there is a significant weakening in the Zn-Al alloy during HPT despite extensive grain refinement. Excellent room-temperature (RT) plasticity was observed in the alloy after HPT from nanoindentation creep in terms of an increased value of m. The microstructural changes with increasing numbers of HPT turns show a strong correlation with the change in the m value. Moerover, the excellent RT plasticity in the alloy is discussed in terms of the enhanced level of grain boundary sliding and the evolution of microsturucture.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

We report the realization of an open cavity whispering gallery mode optical resonator, in which the circulating light traverses a free space gap. We utilize focused ion beam microfabrication to precisely cut a 10 μm wide notch into the perimeter of a crystalline disc. We have shown that this modified resonator structure supports high quality modes, and demonstrated qualify factor, Q ~/= 10(6), limited by the notch surface roughness due to the ion milling process. Furthermore, we investigated the spatial profile of the modes inside the open cavity with a microfabricated probe mechanism. This new type of resonator structure facilitates interaction of the cavity's optical field with mechanical resonators as well as individual atoms or molecules.

We demonstrate that nonpolar m-plane surfaces can be generated on uniform GaN nanosheet arrays grown vertically from the (0001)-GaN bulk material. InGaN/GaN multiple quantum wells (MQWs) grown on the facets of these nanosheets are demonstrated by cross-sectional transmission electron microscopy. Owing to the high aspect ratio of the GaN nanosheet structure, the MQWs predominantly grow on nonpolar GaN planes. The results suggest that GaN nanosheets provide a conduction path for device fabrication and also a growth template to reduce the piezoelectric field inside the active region of InGaN-based light emitting diodes.

The processing of metals through the application of high-pressure torsion (HPT) provides the potential for achieving exceptional grain refinement in bulk metals. Numerous reports are now available demonstrating the application of HPT to a range of pure metals and simple alloys. In practice, excellent grain refinement is achieved using this processing technique with the average grain size often reduced to the true nano-scale range. Contrary to the significant grain refinement achieved in metals during HPT, the models of the hardness evolution are very different depending upon the material properties. For a better understanding of the material characteristics after conventional HPT processing, this report demonstrates the hardness evolutions in simple metals including high-purity Al, commercial purity aluminum Al-1050, ZK60A magnesium alloy and Zn-22% Al eutectoid alloy after processing by HPT. Separate models of hardness evolution are described with increasing equivalent strain by HPT. Moreover, a new approach for the use of HPT is demonstrated by synthesizing an Al–Mg metal system by processing two separate commercial metals of Al-1050 and ZK60A through conventional HPT processing at room temperature.

The tensile fractures of ultrafine-grained (UFG) Al-Mg alloy with a bimodal grain size were investigated at the micro- and macroscale using transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with focused ion beam (FIB), and optical microscopy. The nanoscale voids and crack behaviors near the tensile fracture surfaces were revealed in various scale ranges and provided the evidence to determine the underlying tensile deformation and fracture mechanisms associated with the bulk bimodal metals. The bimodal grain structures exhibit unusual deformation and fracture mechanisms similar to ductile-phase toughening of brittle materials. The ductile coarse grains in the UFG matrix effectively impede propagation of microcracks, resulting in enhanced ductility and toughness while retaining high strength. In view of the observations collected, we propose a descriptive model for tensile deformation and fracture of bimodal UFG metals.