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Current crowding of IGBT and power diode in a chip or among chips is a barrier to the realization of highly-reliable power module and power electronics system. Current crowding occurs because of the parasitic inductance, difference of chip characteristics or temperature imbalance among chips. Although current crowding among IGBT or power diode chips has been analysed on numerical simulations, no sensor with sufficiently high special resolution and fast measurement time has yet been demonstrated. Therefore, the author developed and demonstrated 16-channel flat sensitivity sensor array for IGBT current distribution measurement. The sensor array consists of tiny-scale film sensors with analog amps and shield case against noise. The array and digital calibration method will be applied for reliability analysis, designing and screening of IGBT modules., ESREF 2015, 26th European Symposium on Reliability of Electron Devices, Failure Physics and Analysis, Oct 5-9, 2015, Centre de Congrès Pierre Baudis, Toulouse, France

The distribution and abundance of the calcium binding protein, calbindin D-28k (CB) immunoreactivity in the taste buds of the circumvallate papillae and larynx were compared between normoxic and chronically hypoxic rats (10% O2 for 8 weeks). In the normoxic rats, CB immunoreactivity was observed in some cells and fibers of the intragemmal region of the taste buds in the circumvallate papillae. In contrast, in the subgemmal region of the laryngeal taste buds, fibers but not cells were immunoreactive for CB. In chronically hypoxic rats, CB immunoreactive cells and fibers in the taste buds were decreased in the circumvallate papillae. In the laryngeal taste buds, the density of the subgemmal CB immunoreactive fibers in chronically hypoxic rats was greater than in normoxic rats. It is considered that function of the laryngeal taste buds is different from that of the lingual taste buds, so that laryngeal taste buds may be involved in chemosensation other than taste. The altered density of CB immunoreactive cells and fibers in the lingual and laryngeal taste buds is a predominant feature of hypoxic adaptation, and chronic hypoxic exposure might change the chemical sensitivity of the circumvallate papillae and larynx through the regulation of intracellular Ca2+

The distribution and abundance of substance P (SP) and calcitonin gene-related peptide (CGRP) immunoreactive nerve fibers in four different regions of the laryngeal mucosa were compared between normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO, for 3 months). In the chronically hypoxic laryngeal mucosa, the number of SP and CGRP fibers within and just beneath the epithelium, and around the laryngeal gland was increased in comparison with those in the normoxic controls. Especially in the epiglottic and arytenoid regions, the number of intraepithelial SP fibers was increased remarkably. Most intraepithelial SP and CGRP fibers penetrated into the epithelium to extend to the lumina1 surface. There was no distinct difference in the distribution and abundance of these peptidergic fibers in the mucosa of the normoxic and chronically hypoxic vocal cord regions. These results suggest that the increased density of SP and CGRP fibers within the epithelium of the upper laryngeal mucosa is a predominant feature of hypoxic adaptation, and this may be involved in airway protection, swallowing, and other functions in the chronically hypoxic environment. In addition, the increased SP and CGRP fibers around the laryngeal gland suggest an enhanced mucous secretion, and this may participate in the airway defense mechanism in low O2 conditions.

Distribution of vasoactive intestinal polypeptide (VIP)-immunoreactive nerve fibers and VIPreceptor (VIP-R)-immunoreactive sites in the human submandibular gland were examined by the peroxidaseantiperoxidase method using the specimens taken from patients that had not received radiotherapy. VIP-immunoreactive fibers were found around both serous and mucous acini, the duct system, and those around the mucous acini were more numerous than those around the serous acini. VIP-R immunoreactivity was restricted to the mucous acini and the intercalated duct segment. The serous acini, striated duct, and excretory ducts lacked VIP-R immunoreactivity. These findings suggest that the mucous acinar cells contain VIP-R, and that VIP-R-mediated VIP action is involved in regulating synthesis of viscous saliva and its release.

We monitored the current imbalance in a SiC-MOSFET chip under unclamped inductive switching condition by using our printed circuit board Rogowski coils. The current imbalance varied significantly from sample to sample. The SiC-MOSFET with a larger current imbalance was destroyed with lower avalanche current than other samples. It is assumed that the chip was destroyed due to partial temperature rise accompanying current concentration from current distribution and thermal simulation. The result shows that the current monitoring system is effective for analysis of avalanche robustness., 14th International Seminar on Power Semiconductors, August 29-31, 2018, Prague, Czech

Nasopharyngeal carcinoma (NPC) is a malignant tumor with a high incidence in east Asian countries. Inactivation of cyclin-dependent kinase (CDK) inhibitors (CKIs) and overexpression of G1 cyclin has been thought to be important for tumor development. To determine whether reduction of CKI (p16 and p27) expression was associated with NPC development, we performed immunohistochemical staining of NPC specimens from 20 patients. We found that p16 and p27 proteins were negative in 8 of 20 and 16 of 20 cases, respectively; that either p16 or p27 proteins were negative in 17 of 20; and that both p16 and p27 were negative in 7 of 20. Excepting the cases in which both CKIs were negative, negativity of p27 alone was statistically higher than that of p16 (9/20 versus 1/20, P = .022), suggesting that the reduction of p27 protein is an important event for the multi-step process of NPC development.