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759 results on '"Hirai, Makoto"'

2. Relationship between crystal orientation and energy storage capacity in WO3 photoelectrodes for water splitting.

Author

Hirai, Makoto, Tsuzuki, Keita, Tamura, Fumihiro, and Fujita, Naoyuki

Subjects
*CRYSTAL orientation, *ENERGY storage, *CRYSTAL defects, *X-ray diffraction measurement, *TUNGSTEN trioxide, *DYE-sensitized solar cells, *IRRADIATION
Abstract

For photoelectrochemical water splitting, tungsten trioxide (WO3) films with a monoclinic structure were synthesized on fluorine-doped tin oxide coated glass substrates with a vacuum evaporation method. To control the WO3 film thickness from 0.42 to 5.6 μm, the crystal orientation was intergraded from the (200) crystal plane to the (002) one. In x-ray diffraction measurements, the intensity ratio of the (002) crystal plane to the (200) one was defined as rp. In the WO3 photoelectrode with higher (002)-preferred orientation, the photocurrent continued to flow even when the incident light against the photoelectrode was completely blocked after the irradiation for 60 s. This suggests that hydrogen continues to be produced owing to the electrons charged by the formation of a hydrogen tungsten bronze (HxWO3) phase. After 72 s, the photocurrent density of the WO3 photoelectrode with rp = 42 became one-tenth of the value before the incident light was blocked. This charge release time was remarkably long compared to those of the WO3 photoelectrodes with (200)-preferred orientation and non-orientation. Therefore, it was considered that the hydrogen ion diffusion through the defects in the WO3 crystals tends to occur in the [002] crystal direction. However, the improvement in the (002)-preferred orientation can facilitate the structural change from the WO3 phase to the HxWO3 one for the entire film. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Ex vivo susceptibility of Plasmodium falciparum to antimalarial drugs in Northern Uganda

Author

Fukuda, Naoyuki, Tachibana, Shin-Ichiro, Ikeda, Mie, Sakurai-Yatsushiro, Miki, Balikagala, Betty, Katuro, Osbert T., Yamauchi, Masato, Emoto, Sakurako, Hashimoto, Muneaki, Yatsushiro, Shouki, Sekihara, Makoto, Mori, Toshiyuki, Hirai, Makoto, Opio, Walter, Obwoya, Paul S., Auma, Mary A., Anywar, Denis A., Kataoka, Masatoshi, Palacpac, Nirianne M.Q., Odongo-Aginya, Emmanuel I., Kimura, Eisaku, Ogwang, Martin, Horii, Toshihiro, and Mita, Toshihiro

Published
2021
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10. Recovery and stable persistence of chloroquine sensitivity in Plasmodium falciparum parasites after its discontinued use in Northern Uganda

Author

Balikagala, Betty, Sakurai-Yatsushiro, Miki, Tachibana, Shin-Ichiro, Ikeda, Mie, Yamauchi, Masato, Katuro, Osbert T., Ntege, Edward H., Sekihara, Makoto, Fukuda, Naoyuki, Takahashi, Nobuyuki, Yatsushiro, Shouki, Mori, Toshiyuki, Hirai, Makoto, Opio, Walter, Obwoya, Paul S., Anywar, Denis A., Auma, Mary A., Palacpac, Nirianne M. Q., Tsuboi, Takafumi, Odongo-Aginya, Emmanuel I., Kimura, Eisaku, Ogwang, Martin, Horii, Toshihiro, and Mita, Toshihiro

Published
2020
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17. Crystal facet engineering for production of TiO2/WO3 photoelectrodes with superior energy storage capacity.

Author

Hirai, Makoto, Tsuzuki, Keita, and Fujita, Naoyuki

Subjects
*PRODUCTION engineering, *ENERGY storage, *CONDUCTION bands, *VALENCE fluctuations, *THIN films
Abstract

WO3 thin films with (002)-preferred orientation showing superior electron storage capacity were prepared using a vacuum evaporation system. The electron storage capacity of the WO3 photoelectrode can be improved by controlling the crystallographic orientation of the WO3 crystals. In photoelectrochemical water splitting, the TiO2/WO3 photoelectrode exhibited a significantly higher increment in current density than the pristine WO3 photoelectrode. The charging and discharging capacities of the preferentially oriented WO3 layer can be derived in full value to introduce a TiO2 layer with a porous morphology. Moreover, because a difference in the crystal facet results in a slight change in the energy of the valence and conduction bands, it can be speculated that better separation of electron–hole pairs is achieved, leading to exposure of the (002) dominant crystal facet of WO3. [ABSTRACT FROM AUTHOR]

Published
2021
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37. Increased afternoon step count increases heart rate variability in patients with cardiovascular risk factors.

Author

Nakayama, Natsuki, Miyachi, Masahiko, Tamakoshi, Koji, Morikawa, Shuji, Negi, Koji, Watanabe, Koji, Moriwaki, Yoshimi, and Hirai, Makoto

Subjects
CARDIOVASCULAR diseases risk factors, STATISTICS, LIFESTYLES, HYPERTENSION, SCIENTIFIC observation, TIME, ACCELEROMETERS, PHYSICAL activity, PRIMARY health care, T-test (Statistics), SLEEP, WALKING, HEART beat, ELECTROCARDIOGRAPHY, CHI-squared test, DATA analysis, DATA analysis software
Abstract

Aims and objectives: The present study investigated whether morning or afternoon activity is more effective at increasing the high‐frequency (HF) index, a parasympathetic index, in patients with cardiovascular risk factors. Background: A decreased HF index, a heart rate variability (HRV) parameter, is a well‐established marker of poor cardiovascular prognosis. Because blood pressure and sympathetic tone are higher in the morning, physical activity and exercise in the afternoon has been recommended for patients with cardiovascular diseases. However, there have been no reports concerning the superior effects of afternoon exercise on parasympathetic activity and sleep. Design: This observational study was a post hoc comparison. Methods: Patients' physical activity was measured for 1 month to determine their habits. Patients' HF index was measured by 24‐h Holter electrocardiography. The study enrolled 56 patients. Each patient's morning step count (before lunch) and afternoon step count (between lunch and dinner) were compared. We adhered to the STROBE guidelines in the present study. Results: Thirty‐one patients took more steps in the morning, and 25 patients took more steps in the afternoon. The present study showed that those who took more steps in the afternoon had a significantly higher HF index during the first hour after sleep onset and during sleep than those who took more steps in the morning (p =.003,.047). Conclusions: The present study showed that those who took more steps in the afternoon had a significantly higher HF index during the first hour after sleep onset and a higher HF index during sleep than those who took more steps in the morning. Relevance to clinical practice: Exercise in the afternoon may improve the prognosis in patients with cardiovascular disease by not only preventing excessive blood pressure, afterload, and sympathetic tone but also positively influencing the parasympathetic system and sleep. [ABSTRACT FROM AUTHOR]

Published
2022
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