Aims: To assess the prevalence and clinical significance of mediastinal emphysema (ME) after esophageal endoscopic submucosal dissection (ESD). Methods: A total of 105 patients in whom assessment of ME was prospectively carried out with multi‐detector row computed tomography (MDCT) after esophageal ESD were included in this study. ME was graded as follows: Grade‐0, no ME; Grade‐I, bubbles around the esophagus; Grade‐II, ME around the thoracic aorta; Grade‐III, ME extending around the heart or beyond the mediastinum into the neck; and Grade‐IV, ME with pneumothorax or subcutaneous emphysema. MDCT grading was compared with the finding of conventional chest X‐ray images (CXR) and clinical symptoms. Results: CXR revealed the presence of ME in 6.6% of the subjects. On MDCT, ME was recognized in 62.9% (Grade‐0, 37.1%; I, 46.7%; II, 10.5%; III, 5.7%; and IV, 0%), most (83.8%) being Grade‐I or 0. CXR was able to visualize ME of Grade‐II or greater. Exposure of the muscularis propria layer and location of the lesion were significant risk factors for development of ME of Grade‐II or greater ( P = 0.008 and P = 0.03, respectively). The duration of a fever of 37°C or higher was longer and the serum C‐reactive protein level was higher in patients with a higher grade of ME. Conclusions: MDCT revealed the occurrence of ME in 62.9% of the patients who had undergone esophageal ESD, most of which, however, was clinically silent. Exposure of the muscular layer during ESD and location of the lesion were independent risk factors for the development of ME.
In chemical mechanical polishing (CMP) process, the removal rate is affected by the actual contact conditions between the wafer and the polishing pad. Further, the free abrasives in the slurry attack the wafer at the regions of actual contact. The polishing pad is one of the most important consumable materials in CMP since the pad surface texture changes during wafer polishing and substantially influences the actual contact conditions. Therefore, methods for quantitative evaluation of the pad surface texture have been proposed by various research institutes. We have developed a novel method for the quantitative evaluation of the polishing pad surface texture; this method is based on contact image analysis using an image rotation prism. We have proposed the use of four effective evaluation parameters: the number of contact points, the contact ratio, the maximum value of the minimum spacing of the contact points, and the half-width of the peak of the spatial fast Fourier transform (FFT) of a contact image. We determine the changes in the polishing pad surface texture on the basis of the proposed evaluation parameters in serial batch polishing tests. In particular, we focus on the relationships between the proposed evaluation parameters and the removal rate, which changes with an increase in the number of batch polishing tests. The evaluation parameters are linearly correlated with the removal rate. Hence, the removal rate is improved not only with an increase of the number of contact points and the contact ratio but also with a decrease in the size of the cohesion regions and the spacing between the contact points.
Silicon carbide (SiC) attracts a lot of attention for several useful applications such as semiconductor devices and structural materials under severe conditions because of its outstanding electronic properties as well as high physical and chemical stabilities. However, it is difficult to fabricate meso- and macropores in SiC because of its inertness. In this study, macroporous SiC with a pore size of several micrometers was fabricated by anodizing SiC with point defects which were formed by high-energy Si(II) ion irradiation. This is because irradiated SiC has an electrochemical activity caused by the combination of irradiation-induced defects and dopants. This result suggests that the control of lattice defects is a promising strategy for the surface processing of SiC. We propose that this study gives a new prospect of the electrochemical activation of SiC and opens various fields of its application.
Hole-tunneling Si0.82Ge0.18/Si asymmetric-double-quantum-well resonant tunneling diodes, designed so that the energy difference between the barrier height of the collector side and the coresonance tunneling energy at the coresonance voltage became larger on the basis of the simulation results of voltage-dependent quantized-level shifts and fabricated with the growth of highly B-doped emitter and collector layers without post-annealing, exhibited a flatter surface and a higher performance with a peak current density of 73 kA cm−2 and suppressed thermionic emission with a peak-to-valley current ratio of 14.
We developed a red‐enhanced laser‐phosphor light source with quantum dot conversion layer for projector applications. This device uses dual‐layer wheel structure, in which a quantum dot layer is underneath a Ce:YAG phosphor layer. We demonstrated a high brightness and wide color gamut QD‐based light source.
