Effects of surface defects on performance of kV-class 4H-and 6H-SiC epitaxial p-n junction diodes were investigated. The perimeter recombination and generation, instead of the bulk process, are responsible for forward recombination current and reverse leakage current of the diodes, respectively. Mapping studies of surface morphological defects have revealed that triangularshaped defects severely degrade high-blocking capability of the diodes whereas shallow round pits and scratch give no direct impact. Device-killing defects in SiC epilayers are discussed based on breakdown voltage mapping. Effective minority carrier lifetimes are mainly limited not by bulk recombination but by perimeter recombination.

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Air pollution in Japan caused respiratory disease, such as chronic bronchitis and asthma, in many individuals in the 1960s. Although air pollution has decreased, many victims of air pollution-related respiratory disease are limited in their activities of daily living because of respiratory symptoms. The purpose of this study was to evaluate the efficacy of pulmonary rehabilitation in victims of air pollution-related chronic bronchitis or asthma. Subjects were enrolled in a 12-week (2-week inpatient followed by 10-week outpatient) pulmonary rehabilitation program. The program comprised conditioning, strength training, endurance training, and patient education. We assessed the Modified Medical Research Council (MMRC) dyspnea grade, pulmonary function, peripheral muscle force, incremental shuttle walk distance (ISWD), and physical activity at baseline and immediately after the program. Twenty-nine subjects (mean age 74.2 ± 10.1 years, 11 males) completed the program, including 11 subjects with COPD and 18 subjects with asthma. Following rehabilitation, the participants (n = 29) showed significant improvements in MMRC dyspnea grade, vital capacity % predicted, quadriceps force and ISWD (all P < 0.05). Sub-group analyses revealed that all these variables were significantly improved in subjects with asthma. In contrast, subjects with COPD showed significant improvements only in quadriceps force and ISWD (both P < 0.05). Thus, pulmonary rehabilitation is an effective method of improving exercise capacity and dyspnea in officially acknowledged victims of air pollution-related asthma. In conclusion, we recommend that patients with chronic bronchitis or asthma, resulting from exposure to air pollution, are referred for pulmonary rehabilitation.

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