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Kentaro Hayashi,Kazuhide Matsuda,Akira Takahashi,Ko Nakaya 한국대기환경학회 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.2
The present study aimed to investigate the diurnal variations in air concentrations and exchange fluxes of ammoniacal nitrogen (NHx: ammonia (NH_3) and particulate ammonium) in a subalpine deciduous forest in central Japan during a week in summer. The NH_3 concentrations (0.50 μg N m^-3 on average)showed a clear circadian variation, i.e., high and low in the daytime and nighttime, respectively. The concentration of particulate ammonium in the coarse fractions was extremely low, whereas that for the PM2.5 fraction was relatively high (0.55 μg N m^-3 on average). The main inorganic ion components of PM2.5 at the study site were ammonium and sulfate. The exchange fluxes of NHx were bidirectional. Both the maximum and minimum values occurred in the daytime, i.e., 0.39 mg N m^-2 hr^-1 of downward flux and 0.11 mg N m^-2 hr^-1 of upward flux for NH_3 and 0.25 mg N m^-2 hr^-1 of downward flux and 0.13 mg N m^-2 hr^-1 of upward flux for PM2.5 ammonium. The exchange fluxes of NHx at night could be considered as zero. The mean deposition velocity during the research period was almost zero for both NH_3 and PM2.5 ammonium. The atmosphere-forest exchange of NHx in the forest during the study period was balanced. The remarkably large deposition of NHx was attributable to meteorological events such as showers the night before that thoroughly washed the forest canopy and subsequent clear skies in the morning,which enhanced convection. The cleaning effect of rainfall and the rapid change in convection in the early morning should be monitored to evaluate and generalize the gas and particle exchange in a forest.
Kentaro Hayashi,Keisuke Ono,Kazuhide Matsuda,Takeshi Tokida,Toshihiro Hasegawa 한국대기환경학회 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.11 No.3
Nitrogen (N) is an essential macronutrient. Thus, evaluating its flows and stocks in rice paddy ecosystems provides important insights into the sustainability and environmental loads of rice production. Among the N sources of paddy fields, atmospheric deposition and irrigation inputs remain poorly understood. In particular, insufficient information is available for atmosphere-rice paddy exchange of gaseous and particulate reactive N (Nr, all N species other than molecular N) which represents the net input or output through dry deposition and emission. In this study, we assessed the N inputs via atmospheric deposition and irrigation to a Japanese rice paddy area by weekly monitoring for 2 years with special emphasis on gas and particle exchange. The rice paddy during the cropping season acted as a net emitter of ammonia (NH3) to the atmosphere regardless of the N fertilizer applications, which reduced the effects of dry deposition to the N input. Dry N deposition was quantitatively similar to wet N deposition, when subtracting the rice paddy NH3 emissions from N exchange. The annual N inputs to the rice paddy were 3.2 to 3.6 kg N ha-1 yr-1 for exchange, 8.1 to 9.8 kg N ha-1 yr-1 for wet deposition, and 11.1 to 14.5 kg N ha-1 yr-1 for irrigation. The total N input, 22.8 to 27.5 kg N ha-1 yr-1, corresponded to 38% to 55% of the N fertilizer application rate and 53% to 67% of the brown rice N uptake. Monitoring of atmospheric deposition and irrigation as N sources for rice paddies will therefore be necessary for adequate N management.
Ultrahigh-speed distributed Brillouin reflectometry
Mizuno, Yosuke,Hayashi, Neisei,Fukuda, Hideyuki,Song, Kwang Yong,Nakamura, Kentaro Nature Publishing Group 2016 Light, science & applications Vol.5 No.12
<P>Optical fibre sensors based on Brillouin scattering have been vigorously studied in the context of structural health monitoring on account of their capacity for distributed strain and temperature measurements. However, real-time distributed strain measurement has been achieved only for two-end-access systems; such systems reduce the degree of freedom in embedding the sensors into structures, and furthermore render the measurement no longer feasible when extremely high loss or breakage occurs at a point along the sensing fibre. Here, we demonstrate real-time distributed measurement with an intrinsically one-end-access reflectometry configuration by using a correlation-domain technique. In this method, the Brillouin gain spectrum is obtained at high speed using a voltage-controlled oscillator, and the Brillouin frequency shift is converted into a phase delay of a synchronous sinusoidal waveform; the phase delay is subsequently converted into a voltage, which can be directly measured. When a single-point measurement is performed at an arbitrary position, a strain sampling rate of up to 100 kHz is experimentally verified by detecting locally applied dynamic strain at 1 kHz. When distributed measurements are performed at 100 points with 10 times averaging, a repetition rate of 100 Hz is verified by tracking a mechanical wave propagating along the fibre. Some drawbacks of this ultrahigh-speed configuration, including the reduced measurement accuracy, lowered spatial resolution and limited strain dynamic range, are also discussed.</P>
( Hirotsugu Sakamoto ),( Takashi Asahara ),( Osamu Chonan ),( Norikatsu Yuki ),( Hiroyuki Mutoh ),( Shunji Hayashi ),( Hironori Yamamoto ),( Kentaro Sugano ) 대한장연구학회 2015 Intestinal Research Vol.13 No.1
Background/Aims: Caudal-related homeobox 2 (Cdx2) is expressed in the human intestinal metaplastic mucosa and induces intestinal metaplastic mucosa in the Cdx2 transgenic mouse stomach. Atrophic gastritis and intestinal metaplasia commonly lead to gastric achlorhydria, which predisposes the stomach to bacterial overgrowth. In the present study, we determined the differences in gut microbiota between normal and Cdx2 transgenic mice, using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Methods: Twelve normal (control) and 12 Cdx2 transgenic mice were sacrificed, and the gastric, jejunal, ileac, cecal and colonic mucosa, and feces were collected. To quantitate bacterial microbiota, we used real-time qRT-PCR with 16S rRNA gene-targeted, species-specific primers. Results: The total numbers of bacteria in the gastric, jejunal, ileac, cecal, and colonic mucosa of the Cdx2 transgenic mice were significantly higher than those of the normal mice. The Bacteroi-des fragilis group and also Prevotella were not detected in the stomach of the normal mice, although they were detected in the Cdx2 transgenic mice. Moreover, the Clostridium coccoides group, Clostridium leptum subgroup, Bacteroides fragilis group, and Prevotella were not detected in the jejunum or ileum of the normal mice, although they were detected in the Cdx2 transgenic mice. The fecal microbiota of the normal mice was similar to that of the Cdx2 transgenic mice. Conclusions: Our results showed the differences in composition of gut microbiota between normal and Cdx2 transgenic mice, which may be caused by the development of gastric achlorhydria and intestinal metaplasia in Cdx2 transgenic mice. (Intest Res 2015;13:39-49)