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The structural integrity of nuclear fission and fusion power plant components is the focus of this research. The state of the art is using micro scale specimens milled with a focussed ion beam (FIB). Because of their very low volume such specimens can be lab tested, even when irradiated to low or medium level of activity. This offers a possibility of testing multiple specimens to investigate stochastic effects, e.g. effects of irradiation on the shift of the ductile to brittle transition. However, FIB milled specimens suffer from Ga contamination, to the degree that the validity of fracture data obtained on such specimens is questionable. We propose to use nano-additive manufacturing as an alternative to FIB for making micro scale fracture specimens. A combination of two-photon polymerization and electrodeposition and sputtering was used to manufacture micro-scale Brazilian disk fracture specimens (CBD), which are free from Ga and thus better suited for the study of irradiation effects on structural integrity. In this study Ni CBD specimens were made with 30 µm diameter and up to 13 µm thickness. The slot width varied between 1 µm to 2.9 µm width the corresponding slot length of between 7.5 µm and 8 µm. Consecutive FIB characterization shows that the specimens have polycrystalline microstructure with sub-µm grains. The work is ongoing making W CBD specimens and on reducing the slot width and using chemical vapor deposition fabrication.
A simple process sequence for fabrication of low temperature polysilicon (LTPS) TFTs with self-aligned graded LDD structure was demonstrated. The graded LDD structure was self-aligned by side-etch of Al under the photo-resist followed by excimer laser irradiation for dopant activation and laterally diffusion. The graded LDD polysilicon TFTs were suitable for high-speed operation and active matrix switches applications because they possessed low-leakage-current characteristic without sacrificing driving capability significantly and increasing overlap capacitance. The leakage current of graded LDD polysilicon TFTs at Vd = 5V and Vg = −10V could attain to below 1pA/μm without any hygrogenation process, when proper LDD length and laser activation process were applied. The on/off current ratios of these devices were also above 108. Furthermore, due to graded dopant distribution in LDD regions, the drain electric field could be reduced further, and as a result, graded LDD polysilicon TFTs provided high reliability for high voltage operation.
A high performance of wavelength 870nm resonant cavity LED (RCLED) was fabricated. The high performance of InGaAs/GaAs multiple quantum wells (MQWs) and distributed Bragg reflector (DBR) were employed to achieve the high transmission rate. Two devices A and B were fabricated in this paper. Device A has an offset of 10nm between active region gain and resonant gain, and device B without it. Due to the wavelength shift of active region gain is faster than that of DBR's resonant gain at higher temperature. Device A shows the better temperature performances than device B. A cutoff frequency of 60MHz, a low forward voltage of 1.6V, a output power of 1mW at 10mA and a output power temperature variation (ΔP/ΔT) of –0.02dBm/ °C with chip dimensions of 220um × 220um and 85um diameter emitting window are obtained.
GaN and InGaN layers were grown on annealed 20 and 50nm Al2O3/ZnO substrates by metalorganic chemical vapor deposition (MOCVD). GaN was only observed by high resolution x-ray diffraction (HRXRD) on 20 nm Al2O3/ZnO substrates. Room temperature photoluminescence (RT-PL) showed the red shift of the GaN near band-edge emission, which might be from oxygen incorporation forming a shallow donor-related level in GaN. HRXRD measurements revealed that (0002) InGaN layers were also successfully grown on 20nm Al2O3/ZnO substrates. In addition, thick InGaN layers (∼200-300nm) were successfully grown on Al2O3/ZnO and bare ZnO substrates. These results are significant as previous studies showed decomposition of the layer at InGaN thicknesses of 100nm or less.
The high sensitivity and spatial resolution enabled by two-photon excitation fluorescence lifetime imaging microscopy/fluorescence resonance energy transfer (2PE-FLIM/FRET) provide an effective approach that reveals protein-protein interactions in a single cell during stimulated exocytosis. Enhanced green fluorescence protein (EGFP)–labeled synaptosomal associated protein of 25 kDa (SNAP25A) and red fluorescence protein (mRFP)–labeled Rabphillin 3A (RPH3A) were co-expressed in PC12 cells as the FRET donor and acceptor, respectively. The FLIM images of EGFP-SNAP25A suggested that SNAP25A/RPH3A interaction was increased during exocytosis. In addition, the multidimensional (three-dimensional with time) nature of the 2PE-FLIM image datasets can also resolve the protein interactions in the z direction, and we have compared several image analysis methods to extract more accurate and detailed information from the FLIM images. Fluorescence lifetime was fitted by using one and two component analysis. The lifetime FRET efficiency was calculated by the peak lifetime (τpeak) and the left side of the half-peak width (τ1/2), respectively. The results show that FRET efficiency increased at cell surface, which suggests that SNAP25A/RPH3A interactions take place at cell surface during stimulated exocytosis. In summary, we have demonstrated that the 2PE-FLIM/FRET technique is a powerful tool to reveal dynamic SNAP25A/RPH3A interactions in single neuroendocrine cells.
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