Kokusai Junior College

Abstract Simultaneous mass spawning is an essential reproductive strategy for maintaining zooxanthellate coral populations, but many of the details remain unclear. Most corals that participate in simultaneous mass spawning are hermaphrodites, and they release capsules (called bundles) that contain sperm and eggs. The advantage of simultaneous mass spawning is that it increases the fertilization success between colonies for sessile organisms such as corals, but while there have been many reports on the timing of spawning in previous research, there is almost no information on exactly how long these bundles are released for. In this study, we measured the duration of bundle release in the field for one species of the genus Acropora, which is a representative coral group that participates in mass spawning. The measurements were made by direct observation and estimation from continuous underwater camera footage. The results of direct observation were 9 ± 4 min (mean ± SD) in 2021 and 15 ± 6 min in 2022. The results of estimation from the underwater camera were 6 ± 2 min. These were considerably shorter than the bundle release periods obtained from observations in aquariums in the past, and it was found that bundle release is completed in a short time in the field. The results obtained in this study are considered to be useful for accurately predicting the fertilization rate in the field.

Itchy leaf (Laportea decumana) is one of the plants endemic to Eastern Indonesia. People usually use itchy leaves as an alternative treatment for pain and soreness by rubbing it on the surface of the body. Itchy leaves are very useful because they contain abundant secondary metabolites. The application of itchy leaves by rubbing can certainly affect normal skin flora such as Staphylococcus epidermidis, leading to health problems. This study aimed to investigate the effect of methanol extract of itchy leaves on the normal skin flora of S. epidermidis. This test was conducted using the disk diffusion method. The results of this study showed that all concentrations of itchy leaf extract inhibited the growth of S. epidermidis. The highest inhibitory activity was observed at 50% concentration (23.00 ± 7.20), categorized as very strong, followed by 100% concentration (15.00 ± 2.90), 25% (18.00 ± 11.3), 12.5 (13.40 ± 3.51), and 6.25 (10.40 ± 3.10), all categorized as strong. These findings indicate that the prolonged use of itchy leaves may affect the growth of normal flora, resulting in health problems. On the other hand, itchy leaves have the potential to be developed as an antibacterial agent in the future.

This study investigates the optimization of charge-trap silicon nitride (CT-SiN) for 3D NAND flash memories. We employed density functional theory (DFT) calculations and experimental analysis to identify the material properties influencing electron-trap levels, trap density, and program/erase (P/E) endurance. Our results demonstrate that a near-stoichiometric N/Si ratio of 1.13 offers the deeper electron traps and higher trap density, leading to improved P/E endurance. This study paves the way for significantly improved performance of CT-SiN in future 3D NAND devices.

This paper is part of the ACE2023 Conference Proceedings (View) Full Paper View / Download the full paper in a new tab/window

A runway foreign object debris detection system using millimeter waves in the 90 GHz band is being considered. The radar cross section of M-10 Bolt & Nut, which is important for performance evaluation, was performed by electromagnetic field analysis. The degree of influence of the microstructure of the model was investigated. The polarization dependence of horizontal and vertical polarization was also studied. In order to investigate the size dependence of RCS, EM Simulation were performed for a simple shaped cylinder. The relationship between polarization dependence of RCS and cylinder size is discussed by analyzing a simple cylinder.

Airport runway foreign debris (FOD) detection system automatically detects small debris on the airport runway. The primary sensor of the developed FOD detection system is a 90-GHz band millimeter-wave radar. The runway’s clutter could degrade detection performance. In this paper, fundamental aspects of runway clutter are studied at airport tests. Firstly, the radar’s parameters are given. The airport’s measuring conditions are then detailed. The radar cross-section measured is approximately -49 dBsm. In addition, the different clutter characteristics, changed with the center of the runway, are observed due to the runway cross-section gradient.

A corner reflector is one of the best methods to calibrate a radar system. The calibration method to calculate the radar cross section of corner reflectors for viewing arbitrary aspect angles on the airport runway is proposed. This work was conducted on a real airport environment at Kuala Lumpur International Airport (KLIA). In addition, the measurement was carried out at 93.1 GHz frequency for a Frequency Modulated Continuous Wave (FM-CW) radar detection system. The backscattering characteristics of a radar target, specific development of triangular trihedral corner reflector, standard runway slope measurement, measured theoretical maximum RCS value and experiment site evaluation are presented in this paper.

<strong class="journal-contentHeaderColor">Abstract.</strong> Human activities have caused sometimes dramatic changes to the marine environment globally and locally during the last half century. We hypothesized that the carbon and nitrogen stable isotope ratios (&delta;¹³C and &delta;¹⁵N) of the copepod <em>Calanus sinicus</em>, one of the dominant secondary producers of North Pacific coastal waters, would record anthropogenic impacts on the coastal environment of the Japan Sea. We monitored these isotope ratios during the spring at four stations in the Japan Sea from 2006 to 2020. The &delta;¹³C values ranged from &minus;24.7&thinsp;&permil; to &minus;15.0&thinsp;&permil; and decreased from the spring bloom (February/March) to the post-bloom (June/July). This monthly variation was attributed to changes in both the physiology of <em>C. sinicus</em> and phytoplankton &delta;¹³C. The negative correlation between the &delta;¹³C values of <em>C. sinicus</em> and their carbon:nitrogen ratios reflected lipid accumulation by the copepods; high &delta;¹³C values were associated with high sea surface chlorophyll <em>a</em> concentrations. The &delta;¹⁵N values ranged from 2.8&thinsp;&permil; to 8.8&thinsp;&permil;. The tendency of the &delta;¹⁵N values to increase from the bloom to post-bloom was attributable to an increase of the &delta;¹⁵N of the phytoplankton associated with nitrate depletion and Rayleigh fractionation. These monthly changes were synchronized among the four stations, but &delta;¹³C and &delta;¹⁵N differed significantly between stations. Interannual variations were statistically significant, but there were no significant monotonic trends. Interannual variations differed between &delta;¹³C and &delta;¹⁵N as well as among stations. These results suggest that local conditions rather than global-scale trends were the primary determinants of elemental cycles in this coastal ecosystem.