Search Results (135)

Icing on transmission lines in cold regions can cause asymmetry in the conductor cross-section. This asymmetry can lead to low-frequency, large-amplitude oscillations, posing a serious threat to the stability and safety of power transmission systems. In this study, the aerodynamic characteristics of crescent-shaped and sector-shaped iced eight-bundled conductors were systematically investigated over an angle of attack range from 0° to 180°. A combined approach involving wind tunnel tests and high-precision computational fluid dynamics (CFD) simulations was adopted. In the wind tunnel tests, static aerodynamic coefficients and dynamic time series data were obtained using a high-precision aerodynamic balance and a turbulence grid. In the CFD simulations, transient flow structures and vortex shedding mechanisms were analyzed based on the Reynolds-averaged Navier–Stokes (RANS) equations with the SST k-ω turbulence model. A comprehensive comparison between the two ice accretion geometries was conducted. The results revealed distinct aerodynamic instability mechanisms and frequency-domain characteristics. The analysis was supported by Fourier’s fourth-order harmonic decomposition and energy spectrum analysis. It was found that crescent-shaped ice, due to its streamlined leading edge, induced a dominant single vortex shedding. In this case, the first-order harmonic accounted for 67.7% of the total energy. In contrast, the prismatic shape of sector-shaped ice caused migration of the separation point and introduced broadband energy input. Stability thresholds were determined using the Den Hartog criterion. Sector-shaped iced conductors exhibited significant negative aerodynamic damping under ten distinct operating conditions. Compared to the crescent-shaped case, the instability risk range increased by 60%. The strong agreement between simulation and experimental results validated the reliability of the numerical approach. This study establishes a multiscale analytical framework for understanding galloping mechanisms of iced conductors. It also identifies early warning indicators in the frequency domain and provides essential guidance for the design of more effective anti-galloping control strategies in resilient power transmission systems. Full article

Fibromyalgia, one of the most challenging pains to treat, lacks impartial considerations for diagnosis and useful assessment. The core symptoms are persistent extensive pain accompanied by fatigue, psychological disorders, sleep disturbance, and obesity. This study aims to explore the role of cannabinoid receptor 1 (CB1) on transient receptor potential V1 (TRPV1) signaling pathways in a mouse model of fibromyalgia. This model was subjected to intermittent cold stress (ICS) to induce fibromyalgia, as measured by the nociceptive behavior determined by von Frey and Hargreaves’ tests. Our results showed a lower mechanical threshold (2.32 ± 0.12 g) and thermal latency (4.14 ± 0.26 s) in ICS-induced fibromyalgia mice. The hyperalgesia could be alleviated by 2 Hz electroacupuncture (EA) or by TRPV1 knockout. We found decreased CB1 receptors, upregulated TRPV1, and related kinases in the dorsal root ganglion, spinal cord, hypothalamus, and periaqueductal gray in fibromyalgia mice. EA reversed these effects associated with fibromyalgia, aligning with observations in Trpv1^−/− mice. Peripheral acupoint or the intracerebral ventricle injection of a CB1 agonist significantly attenuated mechanical and thermal hyperalgesia. The EA analgesic effect was reversed by a CB1 antagonist injection, suggesting the involvement of the CB1 signaling pathway. The accurate chemogenetic activation of paraventricular nucleus (PVN), which is a structure of the hypothalamus, initiated fibromyalgia pain. The chemogenetic inhibition of PVN attenuated fibromyalgia pain via the downregulation of TRPV1 pathway. Our discoveries shed light on the involvement of CB1 in the TRPV1 signaling pathway in the effects of EA in fibromyalgia, suggesting its potential as a treatment target. Full article

Supercooled droplets that collide with the windward surface of the aircraft will freeze, which results in icing on both stationary and rotating components. The ice accretion on rotating surfaces is physically different from those on stationary components. The icing phenomenon on the surface of a rotating intake cone was investigated in an icing wind tunnel, and the influence of icing conditions of supercooled large droplets on the experimental results was analyzed. In the experiments, the ice accretion of the intake cone was studied under various conditions, including rotational speed, wind speed, icing temperature, droplet diameter, and icing time. The ice shape on the surface of the intake cone is notably unique due to the influence of centrifugal force, which produces a longer feather-like ice structure that has a significant effect on the performance of the engine. The process of ice shedding caused by centrifugal force is also critical for the engine anti-icing process. Therefore, it is essential to study the icing characteristics under rotational effects during the design and verification process of engine anti-icing systems. Full article

The soybean yield per unit area in Xinjiang has reached a high level, with the crop maturing quickly because of the higher temperatures and levels of mechanization. However, environmental factors cause flowers and pods to shed easily, limiting yield potential. Efficient plant growth regulators (PGRs) used to increase crop yields have gained popularity, but their effectiveness in reducing flower and pod shedding, considering factors such as environment, crop variety, and time of spraying, remains unclear. This study investigated whether spraying several PGRs could reduce soybean flower and pod shedding. Field experiments were conducted from 2022 to 2024 in Ili, Xinjiang, China, using α-naphthaleneacetic acid (NAA), prohexadione-calcium (Pro-Ca), and iron chlorine e6 (ICE6) with foliar applications of 300, 450, and 45 g ha⁻¹ at the four-node stage (V4) and full pod stage (R4). All PGR treatments reduced flower and pod shedding over the years and resulted in an increase in the average flower and pod numbers compared to normal-growth-treated (CK) soybeans. The effective slowing of flower and pod shedding during the critical pod formation stage (R4) ensured a stable yield potential. The flower-to-pod conversion rate was higher after spraying plants with PGRs than for the CK group, and pod retention was higher at the beginning of maturity (R7). Our results demonstrated that spraying PGRs (NAA, Pro-Ca, and ICE6) effectively reduced soybean flower and pod shedding, optimized pod distribution, and increased soybean yield potential. The study findings provide a useful reference for global soybean growers to optimize planting methods. Full article

To investigate the force characteristics of phase spacers during ice-shedding galloping of transmission lines, a comprehensive finite element model for double-circuit lines on the same tower was developed. The analysis focused on the spacers’ suppression effect on galloping and the variation in their axial force. A solid finite element model of phase spacers was constructed, incorporating suspension fittings, ball eye links, and composite insulators. By using the axial force time history under galloping as excitation, the deformation and stress distribution of phase spacers, as well as stress changes in their connection fittings, were studied. The results revealed that phase spacers significantly suppress galloping, with a more pronounced effect on middle-phase conductors. Axial force fluctuates sharply due to galloping, but stabilizes over time, approaching a limit value. The ice-shedding galloping phenomenon impacts stress distribution, with the ball eye link being more susceptible to fracture. Although the ball-and-socket connection at the composite insulator stem may experience high bending stress, the overall stress distribution meets safety requirements, ensuring safe and stable transmission line operation. Full article

This paper focuses on explaining changes over time in globally sourced annual temporal data with the specific objective of identifying features in black-box models that contribute to these temporal shifts. Leveraging local explanations, a part of explainable machine learning/XAI, can yield explanations behind a country’s growth or downfall after making economic or social decisions. We employ a Local Interpretable Model-Agnostic Explanation (LIME) to shed light on national happiness indices, economic freedom, and population metrics, spanning variable time frames. Acknowledging the presence of missing values, we employ three imputation approaches to generate robust multivariate temporal datasets apt for LIME’s input requirements. Our methodology’s efficacy is substantiated through a series of empirical evaluations involving multiple datasets. These evaluations include comparative analyses against random feature selection, correlation with real-world events as explained using LIME, and validation through Individual Conditional Expectation (ICE) plots, a state-of-the-art technique proficient in feature importance detection. Full article

Background: Fibromyalgia, a chronic condition that causes long-lasting pain over several months, is a global medical issue with both personal and societal implications. It is one of the hardest types of pain to heal, given the lack of objective parameters for diagnosis and progression evaluation. The main symptoms of fibromyalgia are long-lasting widespread pain alongside with anxiety, fatigue, sleep disorders, cognitive dysfunction, and obesity. Programmed cell death 1 ligand 1 (PD-L1) has been used as a target in cancer immunotherapy. It can inhibit acute and chronic pain by suppressing nociceptive neuron activity via PD-1 receptors. Methods: The current study aimed to investigate the role of PD-L1/PD1 in a mouse fibromyalgia pain model. Mice were exposed to intermittent cold stress (ICS) to produce a murine fibromyalgia model characterized using von Frey and Hargreaves tests. Results: The ICS-induced mice fibromyalgia pain model showed mechanical (2.26 ± 0.18 g) and thermal (4.36 ± 0.31 s) hyperalgesia. Nociceptive responses could be relieved with electroacupuncture, intracerebral PD-L1 injection, or Trpv1 deletion. We also identified a lower PD-1 level in the dorsal root ganglion, spinal cord, thalamus, and somatosensory cortex. In contrast, levels of pain-related kinases increased after fibromyalgia induction, an effect which could be reversed by EA, PD-L1, or Trpv1 deletion. Conclusions: Our findings shed light on the contribution of PD-L1/PD1 to EA and fibromyalgia pain, indicating its potential as a treatment target for fibromyalgia. Full article

This study examines the trends and interannual variability of extreme precipitation in Antarctica, using six decades (1963–2023) of daily precipitation data from Russia’s Novolazarevskaya Station in East Antarctica. The results reveal declining trends in both the annual number of extreme precipitation days and the total amount of extreme precipitation, as well as a decreasing ratio of extreme to total annual precipitation. These trends are linked to changes in northward water vapor flux and enhanced downward atmospheric motion. The synoptic pattern driving extreme precipitation events is characterized by a dipole of negative and positive height anomalies to the west and east of the station, respectively, which directs southward water vapor flux into the region. Interannual variability in extreme precipitation days shows a significant correlation with the Niño 3.4 index during the austral winter semester (May–October). This relationship, weak before 1992, strengthened significantly afterward due to shifting wave patterns induced by tropical Pacific sea surface temperature anomalies. These findings shed light on how large-scale atmospheric circulation and tropical-extratropical teleconnections shape Antarctic precipitation patterns, with potential implications for ice sheet stability and regional climate variability. Full article

Icing significantly reduces the electrical performance of insulators, and grid failures caused by insulator icing are common. Currently, most research on the flashover characteristics of insulators under icing conditions focuses on artificially iced suspension insulators, with limited studies on post insulators under natural icing conditions. The shed spacing of post insulators is smaller, making them more prone to bridging by icicles in the same icing environment, which exacerbates insulation problems. Therefore, investigating the icing characteristics of post insulators is crucial. In this study, natural icing growth was observed on seven different types of post insulators at the Xuefeng Mountain Energy Equipment Safety National Observation and Research Station. The icing morphology and characteristics of these insulators were examined. The main conclusions are as follows: (1) the icing type and morphology of post insulators are influenced by meteorological conditions, with more severe icing observed on the windward side. (2) The icing mass and icicle length of the insulator increase nonlinearly with icing time. Specifically, during the glaze icing period from 0 to 8 h, the ice mass on the Type V composite post insulator was 3.89 times greater than that during the 13-to-18 h period. (3) Within the same icing cycle, the icing growth rate on composite post insulators is faster than on porcelain post insulators. (4) Compared to suspension insulators, the sheds of post insulators are more easily bridged by icicles. Notably, when the sheds of post insulators are bridged by icicles, the length of icicles on suspension insulators is only half of the gap size. Full article

Situated throughout the southeastern United States within the Laurentian craton are occurrences of various aged deposits (Late Proterozoic to Early Paleogene) that contain volcanics spanning from lamprophyres to carbonatites and basalts to rhyolites. Several are intrusive, while others have been reworked detritally, deposited as river gravels out onto the Gulf Coastal Plain. The earliest occurrence of igneous gravel clasts in the coastal plain of the lower Mississippi Valley lie along the Mississippi River’s eastern valley wall in the ancestral Mississippi River’s pre-loess terrace deposits (PLTDs). The coarse clastics of the PLTDs are dominantly chert gravels derived from Paleozoic carbonate bedrock, but also include clasts of Precambrian Sioux Quartzite, glacially faceted and striated stones, and ice-rafted boulders, which indicate a direct relationship between the PLTDs and glacial outwash during the cyclic glaciation of the Pleistocene Epoch. The PLTDs also contain the oldest known examples of igneous gravels exposed at the surface in Mississippi. An understanding of their igneous bedrock provenance and the timing of their contribution to the sedimentary record of the lower Mississippi River Valley sheds a valuable light onto the geologic history and evolution of the ancestral Mississippi River during the Pleistocene Epoch. The use of fusion inductively coupled plasma mass-spectroscopy (ICP-MS) in the identification of the igneous suites of one of the pre-loess terraces, well-delineated by geologic mapping, adds important geochemical source data from the gravel constituents for the further interpretation and correlation of the individual PLTD allounits. Gravel constituent geochemistry also offers a better understanding of the evolution of the ancestral Mississippi River watershed and the contributions of bedrock sources during Pleistocene glaciation. This petrological study suggests that the igneous gravels sampled from within the Rawhide PLTD allounit originated from the St. Francois Mountains (SFMs) in southwestern Missouri, with the implications that the SFM igneous terrain was in the direct path of the Independence “Kansan” glaciation. This could indicate a glacial extent further southwest than previously documented. Full article

Saponins are a diverse class of secondary metabolites that are often reported to exhibit a variety of pharmacological applications. While research into the elucidation and application of plant and class Holothuroidea-derived saponins (i.e., sea cucumbers) is extensive, the class Asteroidea-derived saponins (i.e., seastars) have been largely overlooked and primarily limited to elucidation. This review provides a comprehensive overview of the cytotoxic activities of asteroid-derived saponins against various cell cultures, for instance, mammalian erythrocytes, multiple microbial strains and cancer cell lines, including melanoma, breast, colon, and lung cancers. Highlighting the distinct structural variations in these saponins, this review examines their selective cytotoxicity and potency, with many demonstrating IC₅₀ values in the low micromolar range. Specific compounds, such as asterosaponins and polyhydroxylated saponins, exhibit noteworthy effects, particularly against melanoma and lung carcinoma cells, while triterpenoid saponins were found to be highly cytotoxic to both erythrocytes and fungal cells. This review also addresses gaps in the research area, including the need for additional in vitro antimicrobial studies, in vivo studies, and further exploration of their mechanisms of action. By consolidating recent findings, we have shed light on the therapeutic potential of asteroid-derived steroidal saponins in developing novel antimicrobial and anticancer agents. Full article

There has been a progressive global increase in the usage of electric vehicles in this dispensation. This is mostly due to the need to decarbonise the transport sector and mitigate the concerns of climate change and depleting oil reserves of which South Africa is not an exception. In fact, South Africa is the country with the highest CO₂ emissions in Africa and can reduce its carbon footprint by embracing green mobility. Compared to the internal combustion engine (ICE) market, the electric vehicle (EV) market in South Africa is still in its early stages, with limited local production and usage since its introduction to the country’s automotive sector in 2013. Therefore, in this study, the usage of EVs in South Africa, along with adoption rates and challenges were carried out to make a stronger case that would offer a better pathway for increased EV adoption in the country. It has been discovered that the slow adoption rate of EVs is due to factors such as EV procurement, ownership costs, vehicle parts, safety issues, battery technology, tax and import duties, load shedding, and availability of charging stations. This paper also provides insights into government policies, funding, and other efforts that can support EV adoption in the country through the analyses of primary and secondary data. The proposed strategies include the introduction of tax rebates on imported EVs, local production of EVs and their vehicle parts, retrofitting ICE vehicles to EVs, and science-informed strategies to transition from ICE to electric vehicles. Furthermore, more renewable energy grid integration and renewable energy-powered EV charging stations would also provide support for the energy required to power EVs even during load shedding. Preliminary findings from the survey also suggest that the local production of EV components and government-sponsored training programmes on various EV skills are crucial for increasing the adoption rate of EVs in the country. Full article

Phase-to-ground discharge of transmission lines due to ice cover is a common issue. To assess the risk of phase-to-ground discharge of overhead lines under complex ice-covering conditions, this study used finite element analysis to model the interaction between ground wire, conductor, and insulator. The study examined how different factors affect the minimum safe distance between the conductor and ground wire, as well as the risk coefficient of phase-to-ground discharge and the risk zone. The finding reveals that as icing thickness increases, conductor bouncing intensifies, reducing the phase-to-ground distance, and placing one half of the line span within the risk zone for the given conditions. For the same length of de-icing, the closer the de-icing region is to the midpoint, the greater is the maximum jump height of the conductor. When the span is extended to 600 m, the risk range covers approximately 70% of the total line length. Under strong winds, conductor lateral displacement increases with wind speed, which leads to a higher risk of discharge. Full article

Melatonin is a hormone naturally produced by the body that has recently been found to have antiviral properties. However, its antiviral mechanisms are not entirely understood. Using Caco-2 cells, we developed a gastrointestinal organoid model to investigate the impact of melatonin on cellular organoid culture response to Poly I:C-induced viral inflammation in the gastrointestinal tract. Melatonin was found to have different effect when applied as a pretreatment before the induction of viral inflammation or as a treatment after it. Melatonin pretreatment after Poly I:C stimulation did not protect organoids from size reduction but enhanced cell proliferation, especially when lower (1 and 10 µM) melatonin concentrations were used. On the other hand, treatment with melatonin after the induction of viral inflammation helped to maintain the size of the organoids while reducing cell proliferation. In pretreated cells, reduced IFNLR1 expression was found, while melatonin treatment increased IFNLR1 expression and reduced the production of viral cytokines, such as IFNλ1 and STAT1-3, but did not prevent from apoptosis. The findings of this study emphasize the importance of type III IFNs in antiviral defense in epithelial gastrointestinal cells and shed more light on the antiviral properties of melatonin as a potential therapeutic substance. Full article

Animal models that are susceptible to SARS-CoV-2 infection and develop clinical signs like human COVID-19 are desired to understand viral pathogenesis and develop effective medical countermeasures. The golden Syrian hamster is important for the study of SARS-CoV-2 since hamsters are naturally susceptible to SARS-CoV-2. However, infected hamsters show only limited clinical disease and resolve infection quickly. In this study, we describe development of human angiotensin-converting enzyme 2 (hACE2) transgenic hamsters as a model for COVID-19. During development of the model for SARS-CoV-2, we observed that different hACE2 transgenic hamster founder lines varied in their susceptibility to SARS-CoV-2 lethal infection. The highly susceptible hACE2 founder lines F0F35 and F0M41 rapidly progress to severe infection and death within 6 days post-infection (p.i.). Clinical signs included lethargy, weight loss, dyspnea, and mortality. Lethality was observed in a viral dose-dependent manner with a lethal dose as low as 1 × 10^0.15 CCID₅₀. In addition, virus shedding from highly susceptible lines was detected in oropharyngeal swabs on days 2–5 p.i., and virus titers were observed at 10^5.5−6.5 CCID₅₀ in lung and brain tissue by day 4 p.i.. Histopathology revealed that infected hACE2-hamsters developed rhinitis, tracheitis, bronchointerstitial pneumonia, and encephalitis. Mortality in highly susceptible hACE2-hamsters can be attributed to neurologic disease with contributions from the accompanying respiratory disease. In contrast, virus challenge of animals from less susceptible founder lines, F0M44 and F0M51, resulted in only 0–20% mortality. To demonstrate utility of this SARS-CoV-2 infection model, we determined the protective effect of the TLR3 agonist polyinosinic-polycytidylic acid (Poly (I:C)). Prophylactic treatment with Poly (I:C) significantly improved survival in highly susceptible hACE2-hamsters. In summary, our studies demonstrate that hACE2 transgenic hamsters differ in their susceptibility to SARS-CoV-2 infection, based on the transgenic hamster founder line, and that prophylactic treatment with Poly (I:C) was protective in this COVID-19 model of highly susceptible hACE2-hamsters. Full article