carrier-lifetime-measurements-semiconductors-through-microwave

Carrier Lifetime Measurements in Semiconductors through the Microwave Photoconductivity Decay Method

This work presents a protocol employing the microwave photoconductivity decay (&#956;-PCD) for measurement of the carrier lifetime in semiconductor ...

Nagoya Institute of Technology

General electric devices and ventilation systems are known to generate low frequency noise (LFN) with frequencies of <100 Hz. Previous studies showed that exposure to LFN caused impairments of balance in humans and mice during adulthood. On the other hand, a previous study showed that noise levels in the neonatal intensive care unit (NICU) were greater than those in general home or office environments. Therefore, it is possible that neonates have a potential risk to be exposed to LFN in the NICU. However, the risk of neonatal exposure to LFN remains unclear in humans and mice. In this study, male ICR mice were exposed to LFN at 100 Hz for 4 weeks after birth and then subjected to rotarod and beam crossing tests in order to assess LFN-mediated risk of imbalance during the neonatal period. Exposure to LFN at 70 dB, but not exposure to LFN up to 60 dB, during the neonatal period significantly decreased performance scores for rotarod and beam crossing tests compared to the scores of the control group. The number of calbindin-positive hair cells in the saccule and utricle was decreased in mice exposed to LFN at 70 dB for 4 weeks in the neonatal phase. Cessation of exposure for 10 weeks did not result in recovery of the decreased performance in rotarod and beam crossing tests. Thus, our results suggest that 70 dB is a possible threshold for exposure to LFN for 4 weeks during the neonatal period causing unrecoverable imbalance in mice.

Risk Assessment of Neonatal Exposure to Low Frequency Noise Based on Balance in Mice.

We have successfully demonstrated solar water splitting using a newly fabricated photoelectrochemical system with a Pt-loaded SiC photocathode, a CoO -loaded BiVO photoanode, and a perovskite solar cell. Detection of the evolved H and O with a 100 % Faradaic efficiency indicates that the observed photocurrent was used for water splitting. The solar-to-hydrogen (STH) efficiency was 0.55 % under no additional bias conditions.

Solar Water Splitting Utilizing a SiC Photocathode, a BiVO Photoanode, and a Perovskite Solar Cell.

Previous studies showed that people in urban areas are possibly exposed to 60-110 dB of low frequency noise (LFN) defined as noise of ≤100 Hz in their daily life. Previous studies also showed increased health risks by exposure to high levels (130-140 dB) of LFN in animals. However, little is known about the health effects of exposure to an ordinary level of LFN. We biochemically and immunohistochemically assessed the effects of exposure to inaudible LFN for mice (12 h/day of 100 Hz LFN at 95 dB for 5 days), at a level to which people are possibly exposed in daily life, on a murine inner ear by targeting 9 stress-reactive molecules. There was more than a 5-fold increased transcript level of heat shock protein 70 (Hsp70) in the whole inner ear exposed to LFN. However, the transcript levels of the other 8 stress-reactive molecules including Hsp27 and Hsp90 were comparable in LFN-exposed and unexposed murine inner ears. Only the transcript level of Cebpβ among the previously reported 4 transcriptional activators for Hsp70 expression was more than 3-fold increased by LFN exposure. Hsp70 transcript expression levels in the inner ears 3 days after LFN exposure were comparable to those in unexposed inner ears. The protein level of Hsp70, but not the levels of Hsp27 and Hsp90, was also increased in the vestibule by LFN exposure. However, hearing levels as well as expression levels of Hsp70 protein in the cochleae were comparable in LFN-exposed mice and unexposed mice. Our results demonstrated that the inner ear might be one of the organs that is negatively affected by stress from inaudible LFN exposure. Moreover, LFN exposure might increase Hsp70 expression level via Cebpβ in the inner ear. Thus, Hsp70 and Cebpβ levels could be candidates of biomarkers for response to LFN exposure.

Article	Year
Risk Assessment of Neonatal Exposure to Low Frequency Noise Based on Balance in Mice. Frontiers in behavioral neuroscience\| PubMed ID: 28275341	2017
Solar Water Splitting Utilizing a SiC Photocathode, a BiVO Photoanode, and a Perovskite Solar Cell. ChemSusChem\| PubMed ID: 28960942	2017
Increased expression level of Hsp70 in the inner ears of mice by exposure to low frequency noise. Hearing research\| PubMed ID: 29519617	2018

Masashi Kato

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