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Rayon-derived fibers are the central constituent of reinforced carbon/carbon (RCC) composites. Optical, scanning electron, and transmission electron microscopy were used to characterize the as-fabricated fibers and the fibers after oxidation. Oxidation rates were measured with weight loss techniques in air and oxygen. The as-received fibers are ~10 μm in diameter and characterized by grooves or crenulations around the edges. Below 800 °C, in the reaction-controlled region, preferential attack began in the crenulations and appeared to occur down fissures in the fibers. 相似文献
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This work investigates the quantification of electron-phonon thermal diffuse scattering (TDS) for detection of temperature variations with nanometer spatial resolution in transmission electron microscopy (TEM). Observations of TDS intensity for (100) single crystal Si and Ge show interdependences of temperature and sample thickness which can be understood through the angular distributions of electron-phonon scattering as a function of temperature. The temperature sensitivity of the integrated TDS intensity can be of the order of 10(-3) K(-1) for Si and Ge. This shows that measurement of the TDS intensity in the TEM is a promising means for nanoscale temperature measurement; our measurements to date have demonstrated that temperature changes as small as 5 K are detectable. 相似文献
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A.J. Giles J.D. Caldwell R.E. Stahlbush B.A. Hull N.A. Mahadik O.J. Glembocki K.D. Hobart K.X. Liu 《Journal of Electronic Materials》2010,39(6):777-780
To understand the nature of various extended defects and their impact on the electronic or optoelectronic characteristics
of semiconductor devices, the investigation of spectral properties is required. However, electroluminescence spectroscopy
does not provide spatial or structural information. The lack of such information can lead to incorrect assignment of a luminescence
band and therefore misinterpretation of the nature of the emitting defect. Here we report on the collection and analysis of
real-color and spectrally selective monochromatic electroluminescence (EL) images from 4H-SiC PiN diodes. The former provides
the approximate spectral properties from the color of the various defects with high spatial resolution, while the latter enables
simultaneous collection of both structural and spectral properties from extended defects, thereby assisting in providing the
correct assignment of the various spectral features observed. This effort enabled the observation of the formation of a green
EL emission located at C-core partial dislocations (PDs) that occurred during the stacking fault (SF) expansion process. 相似文献
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The multimedia authoring research agenda today, is searching for the proverbial killer application. We believe that multimedia's killer app might already be at hand-and it's focused around audio and video clips. But researchers aren't addressing critical open research issues because of the current focus on commercially produced, feature-length videos as an experimental corpus. The article focuses on the notion of multimedia clips, and most especially their retrieval, as a key enabler for the wide adoption of multimedia. 相似文献
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Katherine L. Hull Daniel S. March Darren R. Churchward Matthew P.M. Graham‐Brown James O. Burton 《Hemodialysis international. International Symposium on Home Hemodialysis》2020,24(2):133-147
Extended‐hours hemodialysis is associated with improvements in quality of life (QoL) and mortality, but it may accelerate the loss of residual kidney function (RKF) and increase vascular access complications. Multiple established databases were systematically searched; randomized and non‐randomized studies were pooled separately. QoL outcomes were assessed using standardized mean difference (SMD), vascular access adverse events and mortality were assessed with relative risk ratios (RR). Four hundred seventy‐six patients from six trials were eligible. Data from randomized controlled trials (RCTs) could only be synthesized for vascular access adverse events and mortality, which demonstrated no significant change in vascular access adverse events (RR 1.25, 95% CI 0.88 to 1.77) or mortality (RR 2.29, 95% CI 0.60 to 8.71). Pooled data from non‐randomized trials demonstrated no significant difference in QoL (SF‐36 Physical Component Summary SMD 0.61, 95% CI ?0.10 to 1.31, SF‐36 Mental Component Summary SMD ?0.04, 95% CI ?0.61 to 0.54). RKF was assessed in one report which demonstrated a potential reduction over 12 months with extended‐hours hemodialysis. The majority of trials had high risk of bias. Extended‐hours hemodialysis was not associated with improved QoL or mortality, or increased vascular access events. Adequately powered RCTs are needed to fully assess extended‐hours hemodialysis. 相似文献