Scattering Parameter Approach to Power MOSFET Design for EMI

Electromagnetic interference (EMI) noise byavalanche oscillations is the major barrier to improve powerdevice performance. Especially the oscillations of three-terminaldevices are more complex than two-terminal devices in point ofthe mutual relationship between devices and external circuit. Scattering parameter (S-parameter) under avalanche condition is obtained to establish stable-unstable criterion with stability factor (K-factor). The stable-unstable criterion clearly indicates the unstable frequency range with each change in MOSFET design. In addition the oscillation mechanism on power MOSFET is modeled with junction capacitance, which is the same as that of diode. For EMI suppression, resonant frequency of external circuit has to be different from unstable frequency of MOSFETs.2012 24th International Symposium on Power Semiconductor Devices and ICs (ISPSD 2012), June 3-7, 2012, Bruges, Belgiu

Large frequency dependence of lowered maximum dielectric constant temperature of LiTaO3 nanocrystals dispersed in mesoporous silicate

A large frequency dependence of the maximum dielectric constant temperature was observed for LiTaO3 nanocrystals (the diameter 20 Å) dispersed in mesoporous silicate. At the applied field frequency of 100 kHz, the maximum temperatures in the real and imaginary parts were 365 and 345 °C, respectively. The maximum temperature in the real part is apparently lower than the paraelectric–ferroelectric transition temperature (645 °C) of bulk LiTaO3. The maximum temperature in the imaginary part rose from 285 to 420 °C with increasing frequency from 10 to 1000 kHz. Since the bulk LiTaO3 shows no relaxor behavior, such superparaelectric behavior is obviously a consequence of nanominiaturization of LiTaO3 crystal and insignificant cooperative interactions between the nanoparticles

Mice Null for the Deubiquitinase USP18 Spontaneously Develop Leiomyosarcomas

USP18 (ubiquitin-specific protease 18) removes ubiquitin-like modifier interferon stimulated gene 15 (ISG15) from conjugated proteins. USP18 null mice in a FVB/N background develop tumors as early as 2 months of age. These tumors are leiomyosarcomas and thus represent a new murine model for this disease

Large frequency dependence of lowered maximum dielectric constant temperature of LiTaO3 nanocrystals dispersed in mesoporous silicate

A large frequency dependence of the maximum dielectric constant temperature was observed for LiTaO3 nanocrystals (the diameter 20 Å) dispersed in mesoporous silicate. At the applied field frequency of 100 kHz, the maximum temperatures in the real and imaginary parts were 365 and 345 °C, respectively. The maximum temperature in the real part is apparently lower than the paraelectric–ferroelectric transition temperature (645 °C) of bulk LiTaO3. The maximum temperature in the imaginary part rose from 285 to 420 °C with increasing frequency from 10 to 1000 kHz. Since the bulk LiTaO3 shows no relaxor behavior, such superparaelectric behavior is obviously a consequence of nanominiaturization of LiTaO3 crystal and insignificant cooperative interactions between the nanoparticles

Usefulness of the forced oscillation technique in assessing the therapeutic result of tracheobronchial central airway obstruction

Background: Pulmonary function tests (PFTs) comprise the traditional method for detecting central airway obstruction (CAO) and evaluating therapeutic effects, but are effort dependent. By contrast, the forced oscillation technique (FOT) is performed during tidal breathing in an effort-independent mode and is universally used to assess respiratory function in patients with chronic obstructive pulmonary disease (COPD) and asthma. We used the FOT to measure airway resistance and reactance in patients with CAO before and after interventional bronchoscopy and compared the results to data obtained using PFTs. Methods: Twelve patients with CAO were recruited from December 2013 to July 2016. The FOT, PFTs, chest computed tomography (CT), COPD Assessment Test (CAT), and the modified Medical Research Council (mMRC) dyspnea scale were employed before and after interventional bronchoscopy. The minimum airway cross-sectional area (MACSA) was calculated using a CT image calculator. Results: Of the 12 patients, 6 had tracheal obstruction and 6 had bronchial obstruction. All FOT measurements, except Delta XS, were significantly improved after interventional bronchoscopy in all cases. The significance of the improvement was greater with the FOT than PFTs. The MACSA, CAT, and mMRC dyspnea scale scores also significantly improved in all cases. Furthermore, only alteration of resistance at 20 Hz (R20) significantly correlated with the alteration of the MACSA after intervention. No significant correlations were found for PFTs. Conclusions: The FOT is suitable and convenient for assessing therapeutic results in patients with tracheobronchial CAO. The alteration of R20 is useful for estimating the airway dilation of CAO after interventional bronchoscopy. (C)2018 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.ArticleRESPIRATORY INVESTIGATION.56(3):222-229(2018)journal articl

Frequency-dependent bifurcation point between field-cooled and zero-field-cooled dielectric constant of LiTaO3 nanoparticles embedded in amorphous SiO2

Splitting between the field-cooled dielectric constant and the zero-field-cooled dielectric constant was observed for a diluted system of LiTaO3 nanoparticles (diameter 30 Å) embedded in amorphous SiO2. At the applied field frequency of 100 kHz, the real part of the field-cooled dielectric constant diverged from that of the zero-field-cooled one at 380 °C. The bifurcation point of the history-dependent dielectric constant rose from 310 to 540 °C upon increasing the field frequency from 10 to 1000 kHz. Bulk LiTaO3 powders showed no splitting in the history-dependent dielectric constant and the maximum at 645 °C in the real part of the dielectric constant, despite the variation of frequency. Both the splitting of the history-dependent dielectric constant and the frequency dependence of the bifurcation point suggest that the LiTaO3 nanoparticles with a single-domain structure were in the superparaelectric state as a consequence of insignificant cooperative interactions among the nanoparticles in the diluted system. The energy barrier of 0.9 eV separating two (+p and –p) polarization states corroborated the potential of the LiTaO3 nanoparticle for ultrahigh-density recording media applications