ABSTRACT
The growth of the Urban Air Mobility (UAM) industry emphasizes the need for considerable study into assembly procedures and dependability to guarantee its effective integration into air transport networks. In this context, this study seeks to evaluate the mechanical characteristics of bolted joint Carbon Fiber Reinforced Plastic (CFRP), with a particular emphasis on bearing strength. By altering the w/D (specimen width to hole diameter) and e/D (distance between hole center and specimen end to hole diameter) ratios, the study investigates how edge and end distances affect material performance. The study discovered a shift from tension to bearing failure at w/D ratios of 4.0, with maximum bearing strength decreases of 90.50% and 69.96% compared to full bearing failure. Similarly, for e/D ratios of 1.5, 2.0, and 3.0, transitioning from shear to bearing failure at 2.0 resulted in maximum bearing strength losses of 94.90% and 75.96%, respectively. Maintaining a w/D ratio of at least 6.0 and an e/D ratio of at least 3.0 is critical for maintaining maximum performance and stability in CFRP structure design.
ABSTRACT
BACKGROUND: This study aimed to examine the scale, characteristics, risk factors, and modes of transmission in a coronavirus disease 2019 (COVID-19) outbreak at a high school in Seoul, Republic of Korea. METHODS: An epidemiological survey was conducted of 1,118 confirmed cases and close contacts from a COVID-19 outbreak at an educational facility starting on May 31, 2021. In-depth interviews, online questionnaires, flow evaluations, and CCTV analyses were used to devise infection prevention measures. Behavioral and spatial risk factors were identified, and statistical significance was tested. RESULTS: Among 3rd-year students, there were 33 confirmed COVID-19 cases (9.6%). Students who used a study room in the annex building showed a statistically significant 4.3-fold elevation in their relative risk for infection compared to those who did not use the study room. Moreover, CCTV facial recognition analysis confirmed that 17.8% of 3rd-year students did not wear masks and had the lowest percentage of mask-wearers by grade. The air epidemiological survey conducted in the study room in the annex, which met the 3 criteria for a closed space, confirmed that there was only 10% natural ventilation due to the poor ventilation system. CONCLUSION: To prevent and manage the spread of COVID-19 in educational facilities, advance measures that consider the size, operation, and resources of each school are crucial. In addition, various survey methodologies should be used in future studies to quickly analyze a wider range of data that can inform an evidence-based quarantine response.
ABSTRACT
Ischemic vaso-occlusive retinopathy as an initial manifestation is rare in pediatric systemic lupus erythematosus (pSLE). A 13-year-old girl presented with two months' history of papules and crusts with fatigue, weight loss, and abrupt hair loss. Pancytopenia and findings compatible with SLE, including positive direct Coombs' test, antinuclear antibody (Ab), anti-double stranded DNA Ab, anti-Smith Ab, anti-ribonucleoprotein Ab, lupus anticoagulant, anti-ß2 glycoprotein Immunoglobulin G, and anti-cardiolipin Ab, were detected. Bi-nasal hemianopsia was detected. Initial visual acuity was hand motion in the right eye and 15/20 in the left. Fundoscopy showed massive exudation around the optic disc with macular edema, vascular sheathing with perivascular hemorrhage in the whole retina, and ghost vessels in the peripheral retina. Intravitreal triamcinolone injection and dexamethasone implant injection were administered. Visual symptoms improved but did not recover. Methylprednisolone therapy and photocoagulation improved visual acuity and fever. Early intervention for retinopathy in pSLE can help prevent vision-loss.
ABSTRACT
In November 2021, 14 international travel-related severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant of concern (VOC) patients were detected in South Korea. Epidemiologic investigation revealed community transmission of the omicron VOC. A total of 80 SARS-CoV-2 omicron VOC-positive patients were identified until December 10, 2021 and 66 of them reported no relation to the international travel. There may be more transmissions with this VOC in Korea than reported.
Subject(s)
COVID-19/transmission , SARS-CoV-2 , Travel-Related Illness , Adult , Aged , Aged, 80 and over , COVID-19/epidemiology , Female , Humans , Male , Middle Aged , Republic of Korea/epidemiology , Young AdultABSTRACT
The compounds 1,8-cineole and zerumbone (ZER) from the Cyperus rotundus rhizome along with another 11 previously identified rhizome essential oil constituents and α-humulene, which lacks the only carbonyl group present in ZER, as well as binary mixtures of ZER and seven active compounds were tested for repellency to male B. germanica. The results were compared to N,N-diethyl-3-methylbenzamide (deet). In filter-paper choice tests, ZER was the most repellent compound, and α-humulene was ineffective, which indicates that the α,ß-unsaturated carbonyl group of ZER is a prerequisite component for repellency. At 81.5 µg cm-2, enhanced repellency was produced by binary mixtures of ZER and 1,8-cineole, (+)-dihydrocarvone or (R)-(+)-limonene (70:30, 50:50 and 30:70 ratios by weight). These mixtures were very effective against male B. germanica within 24 h and were more repellent than a single compound or deet alone. The optimum ZER content was determined to be more than 50%. In Ebeling choice box tests at 652.4 µg cm-2, these compounds and deet resulted in complete repellency to intact male B. germanica, while they exhibited 35-47% repellency to antennectomized male one. Mixtures formulated from the active constituents of the C. rotundus rhizome could be useful as potential repellents for controlling B. germanica.
