In the Hokuriku area of Japan, surge arresters are commonly installed on pole-mounted switches as lightning protection measures. This paper examines a rationalization measure to reduce the withstand capability of surge arresters used for switch protection. Using lightning surge simulations, the failure probability of surge arresters caused by direct lightning strikes to distribution lines is analyzed, and the effectiveness of the rationalization measure is evaluated based on the analytical results. The study shows the following findings. (1) Telecommunication wires commonly installed on actual distribution lines have the effect of reducing the failure probability of surge arresters. On distribution lines equipped with an overhead ground wire, the presence of a telecommunication wire reduces the failure probability of surge arresters to approximately 20%. (2) When the withstand capability of surge arresters used for switch protection is reduced to one half, the failure probability of surge arresters on distribution lines with an overhead ground wire increases by approximately 1.9 times. However, this failure probability is still approximately 30-40% lower than that of surge arresters installed on non-terminal or terminal poles. (3) If the proposed rationalization measure is fully implemented in actual distribution lines in the Hokuriku area, it is estimated that the increase in lightning-induced failures of surge arresters would be very small, at approximately 5%.
Peridotites exposed in the southern Mariana Trench provide a rare opportunity to investigate mantle processes operating at the interface between arc and back-arc tectonic domains. This study presents petrographic observations and major element mineral chemistry of 41 depleted mantle harzburgites collected from three sites (Sites A-C) in the southern Mariana Trench. Site A is located on the east-facing slope of the West Santa Rosa Bank Fault, whereas Sites B and C are situated on the southern slope of the South Mariana Forearc Ridge along the eastern side of the Challenger Deep. The harzburgites exhibit variable microstructures ranging from coarse-grained (>1 mm) to medium-grained (<1 mm) to small-grained (>0.1 mm) textures, with or without porphyroclasts, and commonly contain amphibole associated with orthopyroxene and spinel. Olivine Mg# (Mg/[Mg + Fe]) (0.902-0.925) and spinel Cr# (Cr/[Cr + Al]) (0.304-0.720) indicate a wide range of mantle depletion across the three sites. Based on the integrated chemical characteristics of olivine, spinel, and amphibole, the harzburgites are classified into three distinct compositional trends (Trends 1-3). Trend 1 is characterized by high olivine Mg# (similar to 0.925), high spinel Cr# (>0.6), low TiO2 contents (<0.1 wt%), and K2O-enriched but TiO2-poor amphibole (TiO2/K2O < similar to 0.5), consistent with strongly depleted forearc mantle modified by slab-derived hydrous melts or fluids. In contrast, Trend 2 is defined by relatively high olivine Mg# (>similar to 0.91), lower spinel Cr# (<0.6), slightly higher TiO2 contents (up to similar to 0.2 wt%), and amphibole moderately enriched in both K2O and TiO2 (TiO2/K2O = 1-4), recording an intermediate geochemical signature that cannot be uniquely attributed to a purely forearc origin. Trend 3 is characterized by lower olivine Mg# (similar to 0.90), lower spinel Cr# (<0.6), distinctly higher TiO2 contents (up to similar to 0.8 wt%), and TiO2-rich but K2O-poor amphibole (TiO2/K2O > 4), indicating a back-arc mantle origin related to decompression melting. Trends 1 and 2 occur in harzburgites from Sites B and C of the South Mariana Forearc Ridge, whereas Trend 3 is exclusively identified in harzburgites from Site A of the West Santa Rosa Bank Fault, highlighting the juxtaposition of forearc-type, transitional, and back-arc-type mantle domains within a single forearc region.
Li4SiO4 is considered as one of the most promising tritium breeding materials for fusion reactor blankets due to its excellent tritium release performance and good chemical stability. To solve the dilemma of high sintering temperature and limited mechanical performance of conventional Li4SiO4 ceramic pebbles, the non-hydrolytic sol-gel (NHSG) route was employed to produce highly reactive ceramic powders. The NHSG-derived powders showed a low phase-formation temperature (similar to 550 degrees C) and a fine particle size (similar to about 300 nm), enabling the preparation of single-phase Li4SiO4 to take place at only 700 degrees C. The Li4SiO4 ceramic pebbles fabricated from these powders reached the relative density of 89.1%, the grain size of 3.3 & micro;m, and the crushing load of 54.4 N after sintering at 1000 degrees C for 2 h. Moreover, the tritium release results showed that the Li4SiO4 ceramic pebbles exhibited HTO and HT signals, and the release temperature of HTO was only 711K, which was lower than that reported in the literature. These results demonstrate that the NHSG process offers an energy-efficient pathway to fabricate the high-purity, high-reactivity Li4SiO4 ceramic pebbles with superior sintering and tritium release performance. These findings present a promising alternative technical route toward solid tritium breeding material in the future.
We investigated the optical properties of a lead-iodide 2D perovskite, ( C 12 H 25 N H 3 ) 2 P b I 4 , incorporating a fullerene derivative in its organic barrier layers. The observation of distinct exciton peaks confirmed that the 2D layered structure was maintained even after fullerene intercalation. Furthermore, time-resolved photoluminescence measurements showed that the exciton lifetime shortened with increasing fullerene content. This reduction in lifetime suggests the possibility that the intercalated fullerenes extract electrons from the inorganic quantum wells. These findings provide useful insights for the design of functional perovskite optoelectronic materials.
Staphylococcus aureus is a bacterium present on the human skin and produces enterotoxins (SEs) when it grows in food, resulting in toxin-type food poisoning. The SEs and virulence factors from S. aureus, which are considered encapsulated and concentrated in membrane vesicles (MVs) composed of the bacterium's own cell membrane, reach host target cells and trigger inflammation. This study was conducted to investigate the effects of acetic acid, used as a food additive, on the expression of virulence factors and MV-induced inflammation in S. aureus. Results showed that 40 mM acetic acid inhibited the production of staphylococcal enterotoxin A (SEA). When S. aureus was cultured in broth containing 40 mM acetic acid, the levels of SEA and several cargo proteins in generated MVs reduced. MVs prepared by adding acetic acid also reduced the expression levels of inflammation-related genes in immortalized human keratinocytes. Therefore, acetic acid may inhibit staphylococcal food poisoning and inflammation by altering the properties of MVs from S. aureus.
