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Compact and lightweight sensors with a high-frequency resolution are required for the passive observation of atmospheric water and oxygen emission lines at a reduced cost and power consumption. A molecular assessment high-resolution observation spectrometer (MAHOS) is developed as a compact, low power, digital fast Fourier transform spectrometer to be installed on a microsatellite. MAHOS has a compact design with dimensions of 0.154 × 0.125 × 0.040 m3 and mass of 0.7 kg. It uses only a few materials including a field programmable gate array (FPGA) module with a lightweight aluminum alloy box. The highly stable spectrometer exhibits a sampling speed of 2.6624 GS/s and 16,384 frequency channels. The stability of the spectrometer is longer than 1200 s within the 1 GHz bandwidth. Thermal dissipation is achieved through a heat conductive gel filled in the gap between the most heat generating component, the FPGA and the aluminum alloy case. Results of a finite element analysis indicate that the design stiff and stable enough to survive in the launch environment. Thermal analysis indicates the durability of the system during operation. Even in space where heat dissipation is not possible, self-heating temperatures are not a problem for the FPGA. In the future, the performance of the spectrometer will be verified by conducting environmental tests.

In this study, an on-board calibration hot load (CHL) unit was developed for a terahertz sensing system (THzSens) receiver at 480 GHz to observe the emission lines of water and oxygen in the atmosphere. The compact CHL unit can be mounted on a microsatellite. We propose an accurate calibration method and a unit compact in design. We conducted experiments in order to obtain the best possible return loss value below the required −60 dB for calibration. The CHL unit uses two specular reflection absorber (SRA) plates and a radar absorbing material (RAM) as the absorber termination. The absorbers are assembled in a lightweight case made of carbon-fiber-reinforced plastics. The SRAs are placed at the Brewster angle with respect to the incident radiation to minimize reflection, which was found experimentally at 480 GHz. The CHL design is expected to have less than −78 dB reflection loss including SRA back scattering at 480 GHz. The return loss as a function of frequency for this design is below −60 dB, meeting the design requirements. Further, a compact prototype CHL was manufactured based on the proposed quasi-optical design. The new CHL for 480 GHz is 1/10 in the volume of the previous SMILES CHL for 650 GHz. The manufactured CHL prototype will be evaluated as a calibrator using the transmitter/receiver setup used in this study.

he sphericity of particles must be considered when evaluating their effects on the climate and human health. Thus, to examine this property and its controlling factors, this study measured the scattering angular distributions of both thermodenuded and non-thermodenuded individual particles with a diameter of 500 nm in real time using a home-made polar nephelometer in Nagoya, Japan. Estimating the sphericities based on the depths of the local minima in the scattering angular distributions, we found the ambient aerosols to be external mixtures of at least two types of particles, one with relatively high and the other with relatively low sphericity. Although most of the particles exhibiting high sphericity were removed as they passed through the thermodenuder, approximately one-third of the fraction exhibiting low sphericity remained. During the daytime, the proportion of the low-sphericity particles decreased, whereas the average sphericity of the high-sphericity particles increased, which can be attributed to photochemical formation and/or aging processes. On days with extremely high relative humidity, the diurnal variation in the average sphericity displayed another peak during the early morning, which may have been due to the secondary formation of nitrate., Aerosol and Air Quality Research, 20(11), pp.2474-2484; 2020

The change in the ozone production rate on reducing its precursors, namely, ozone production sensitivity, is important information for developing a strategy to reduce ozone. We expanded a conventional sensitivity analysis theory by including peroxy radical loss by uptake onto particle surfaces in the aim of examining their potential impact. We also propose a new concept of absolute sensitivity that enables us to evaluate the quantitative effectiveness of precursor reduction toward mitigating ozone production over a given period and area. This study applies the theory to observations in Tsukuba, a city in Japan. The relative sensitivity analysis shows that ozone production was more sensitive to volatile organic compounds (VOCs) in the morning and evening, and it became more sensitive to NOx in the afternoon. NO depletion was a main trigger in this sensitivity regime transition. The absolute sensitivity analysis indicates that the VOC-sensitive period in the morning determines the total ozone production sensitivity in a day. While particles did not have significant impact on regime classification in Tsukuba, they have a potential to decrease the mitigating effect of VOC reduction on ozone production and to moderate the enhancement effect of NOx reduction depending upon uptake coefficients. A further study will benefit from a combination with an observation-constrained box model simulation or chemical transport modeling system, which may provide sensitivity analysis over a large spatial and temporal range.

Despite the role of hydroxyl radical (OH) uptake onto sea-salt particles as a daytime chlorine source, affecting the chemical processes in the marine boundary layer, its uptake coefficient has not yet been confirmed by direct measurement methods. This study reports the application of a combination technique of laser flash photolysis generation and laser-induced fluorescence detection for the direct kinetic measurement of OH uptake onto deliquesced NaCl particles. The uptake coefficient was not constant and inversely depended on the initial OH concentration, indicating that the first uptake step is Langmuir-type adsorption. The resistance model, including surface processes, well reproduced the observed uptake coefficient. The model predicted an uptake coefficient for the atmospheric relevant OH concentration within the range from 0.77 to 0.95. Such values may lead to emissions of Cl2 higher than those predicted in previous studies based on other values. Hence, the proposed value may provide more reliable e...

DJ-1 is a multifunctional protein associated with Parkinson's disease and plays a significant role in protecting nerve cells from oxidative stress. DJ-1 is expressed in the skin, although its function there is unknown. In this study, we investigated DJ-1 function in keratinocytes. DJ-1 was induced by H2O2 exposure and UV irradiation in keratinocytes. DJ-1 knockdown with small interfering RNA (siRNA) increased reactive oxygen species (ROS) and lactate dehydrogenase (LDH) release after UVB irradiation, suggesting that DJ-1 reduces ROS and might protect skin cells from UV damage in vitro. To investigate the in vivo role of DJ-1 in the skin, we determined DJ-1 levels in human stratum corneum samples obtained by the tape-stripping method. DJ-1 levels in the stratum corneum (scDJ-1) correlated with total antioxidant capacity. We also examined the effect of scDJ-1 on changes in skin after UVB irradiation. DJ-1 was elevated in SC from the upper arm 1 to 2 weeks after UVB irradiation. One day after UVB irradiation, L* (brightness) and a* (redness) values, indicators of skin color, were altered regardless of scDJ-1 expression. However, these values recovered more quickly in subjects with high scDJ-1 expression than in those with low scDJ-1 expression. These data suggest that DJ-1 in skin plays a significant role in protection against UV radiation and oxidative stress, and that DJ-1 levels in the SC might be an indicator of antioxidative defense against UV-induced damage.