Search Results (2,104)

The development of carbonaceous materials such as biochar has triggered a hot spot in materials application. In this study, a new type of char carbon was developed from raw cigarette filter rods (CFRs) via a carbonization process under moderate conditions (T = 550 °C; t_res = 1 h) (CFR char carbon). The produced char was characterized by ATR-FTIR (Attenuated total reflectance—Fourier-transform infrared) spectroscopy, XRD (X-ray diffraction) analysis, GC-MS (Gas Chromatography–Mass Spectrometry), FESEM-EDS (Field-Emission Scanning Electron Microscopy—Energy-dispersive X-ray spectroscopy) technique, XPS (X-ray photoelectron spectroscopy), and N₂ adsorption/desorption (BET) measurements. The obtained carbon material is rich in oxygen-containing functional groups (i.e., C=O, C–O, –C(=O)–CH₃, C–O–C, C–OH, and O=C–O, with chemisorbed oxygen), containing significant amounts of calcium (that originates from CaCO₃) and silicon (Si), generated by reduction of SiO₂. It was found that the formation of char(C)/n-alkane composite material makes that CFR char have a high compressive strength improvement. Moderate carbonization has contributed to the creation of such material that has a fairly high specific surface area (320.93 m²/g), exhibiting a complex hierarchical structure that was characterized by composite Type I/IV(a) isotherm, associated with micro-/mesoporous carbon material. In addition, more directional extensions of this research for future work were proposed, including the implementation of electrochemical research. Full article

As a critical component in voltage–current conversion and power transmission within HVDC systems, the risk assessment of converter transformers plays a significant role in ensuring their operational safety and enhancing the reliability of the power supply. To address the issues of the incomplete characteristic parameters and limited fault data used for model training in existing transformer evaluation models, this paper develops a risk assessment model for converter transformers based on the entropy-weighted analytic hierarchy process (AHP). Firstly, in accordance with relevant standards in the power industry and existing experimental research, 14 ‘electrical–thermal–mechanical’ multi-dimensional characteristic parameters, including partial discharge, dissolved gases in oil, and hot spot temperature rise, are selected to effectively reflect the risk state of converter transformers. The risk state is then categorized into four levels. Next, the AHP, which uses a subjective weighting method, is combined with the entropy-weight method, an objective weighting approach, to construct the risk assessment model for converter transformers based on the entropy-weighted AHP. Finally, the effectiveness of the model is validated through four case studies of converter transformers. The results indicate that the risk assessment model proposed in this paper can accurately and effectively reflect the risk state of transformers at different levels, providing valuable guidance for the development of maintenance strategies for converter transformers. Full article

In this work, the single-event burnout (SEB) effect and degradation behaviors induced by heavy-ion irradiation are investigated in a 120 V-rated transverse split-gate trench (TSGT) power metal-oxide-semiconductor field-effect transistor (MOSFET). Bismuth heavy-ions are used to conduct heavy-ion irradiation tests. The experimental results show that the SEB failure threshold voltage (V_SEB) of the tested sample is 72 V, which only accounts for 52.6% of the actual breakdown voltage of the device. The V_SEB value decreased with the increase in the flux. The simulation results show that the local “hot spot” formed after the incident heavy ion is an important reason for the drain current degradation of TSGT MOSFETs. To improve the single-event effect tolerance of TSGT MOSFETs, an SEB hardening method based on process optimization is proposed in this paper, which does not require additional customized epitaxial wafers. The simulation results show that, after SEB hardening, the V_SEB is increased to 115 V, which accounts for 89.1% of the breakdown voltage. Full article

Urogenital cancer is very common in the male population of Western countries, a problem of major concern for public health systems, and a frequent test subject for oncological research. In this narrative, we identify the main hot topics for clinics and the basic science of urological cancer in the last few years (from 2021 onwards), considering the information given in the abstracts of almost 300 original articles published in outstanding journals of pathology, urology, and basic science. Once defined, for the top ten list of hot topics (the 2022 WHO update on the classification of urinary and male genital tumors, new entities in kidney cancer, urinary cancer-omics, update on the Gleason grading system, targeted therapies and other novel therapies in renal cancer, news on non-muscle invasive urothelial carcinoma, artificial intelligence in urologic cancer, intratumor heterogeneity influence in therapeutic failures in urologic neoplasms, intratumor microbiome and its influence in urologic tumor aggressiveness, and ecological principles and mathematics applied to urogenital cancer study), each issue is independently reviewed in an attempt to put together the most relevant updates and/or useful features accompanied by selected illustrations. This review article addresses some of the most interesting and current hot spots in urogenital basic cancer research and clinics and is mainly aimed toward clinicians, including pathologists, urologists, and oncologists. Readers are invited to explore each topic for further, more detailed information, in addition to the references provided. Full article

The groove parameters on the friction base of wet clutches significantly affect the temperature distribution of the steel plates. However, existing methods have not thoroughly investigated the mechanisms by which these parameters influence the thermoelastic instability of wet clutches. To address this gap, a comprehensive co-simulation model of the friction sub-multi-physical field was developed to systematically examine the effects of groove inclination, groove density, and groove depth on the surface temperature and mechanical response of the steel plates. The results indicate that both the tilt angle of the grooves and the number of grooves substantially influence the surface temperature distribution of the steel plates. Specifically, increasing the number of grooves leads to a more concentrated distribution of high-temperature hot spots in the circumferential direction, gradually transitioning the surface temperature–hot spot pattern from isolated hot spots to a more uniform high-temperature tropical distribution, which subsequently reduces the maximum surface temperature. On the other hand, increasing the groove inclination angle causes the high-temperature distribution to shift from localized hot spots to a more tropical pattern, with a relatively minor impact on the peak surface temperature. Furthermore, increasing the groove depth results in the dispersion of the high-temperature tropical zone in the circumferential direction, causing the maximum temperature to initially decrease and then increase. Full article

As a key region in China’s “dual carbon” strategy, the Yangtze River Delta region faces the dual challenge of sustaining tourism-driven economic growth and achieving significant emission reductions. Based on panel data of the Yangtze River Delta region from 2000 to 2022, this paper adopts the “bottom-up” method to measure the carbon emissions of tourism transportation. It systematically analyzes its spatiotemporal evolution, decoupling effect, and driving mechanism. The results showed that (1) regional carbon emissions showed a trend of “first rising and then decreasing”. The spatial distribution changed from “high in the east and low in the west” to central agglomeration, and the hot spots of high emissions continued to concentrate in Shanghai and its surrounding cities, reaching a peak in 2019. (2) The decoupling state is mainly weak decoupling. The environmental Kuznets curve verified that carbon emissions and the tourism economy showed an inverted U-shaped relationship, and the decoupling levels of cities were significantly different. (3) Gross Domestic Product and the scale of tourist flow of cultural facilities (grey correlation degree 0.925) are the core positive drivers. In contrast, the travel ratio (contribution value −215.9) and the scale of passenger flow in A-class scenic spots (correlation degree 0.876) are the key inhibiting factors. This paper proposes a three-pronged policy framework of “energy structure optimization—cross-city carbon compensation—cultural and tourism integration” to provide theoretical and empirical support for the low-carbon transformation of urban agglomerations. Full article

Enhanced abiotic stresses such as increased drought, elevated temperatures, salinity, and extreme weather phenomena severely affect major crops in the Mediterranean area, a ‘hot spot’ of climate change. Plants have evolved mechanisms to face stressful conditions and adapt to increased environmental pressures. Intricate molecular processes involving genetic and epigenetic factors and plant–microbe interactions have been implicated in the response and tolerance to abiotic stress. Deciphering the molecular mechanisms whereby plants perceive and respond to stress is crucial for developing strategies to counteract climate challenges. Progress in determining genes, complex gene networks, and biochemical pathways, as well as plant–microbiota crosstalk, involved in abiotic stress tolerance has been achieved through the application of molecular tools in diverse genetic resources. This knowledge could be particularly useful for accelerating plant improvement and generating resilient varieties, especially concerning woody perennial crops, where classical breeding is a lengthy and labor-intensive process. Similarly, understanding the mechanisms of plant–microbe interactions could provide insights into innovative approaches to facing stressful conditions. In this review, we provide a comprehensive overview and discuss the recent findings concerning the genetic, epigenetic, and microbial aspects shaping abiotic stress responses, in the context of enhancing resilience in important Mediterranean woody perennial fruit crops. Full article

It is well known that a number of head and neck carcinomas are associated with HRAS mutations, and that several cancers with RAS mutations, such as lung cancer, have a poor prognosis. In this study, we evaluated the frequency of HRAS mutations in head and neck carcinomas and characterized the clinical and cell biological features of carcinomas with HRAS mutations. HRAS mutations at codons 12, 13, and 61, mutational hot spots, were evaluated in tissue specimens obtained from 119 Japanese patients treated at our institution. DNA was successfully extracted from 100 specimens, and sequencing was completed. An HRAS mutation was found in 8 (8.0%) cases: 5 (6.1%) out of 82 HNSCCs and 3 (16.7%) out of 18 salivary gland carcinomas. Mutations were found at codons 12 and 61, while none were found at codon 13, which differs from previous reports. The mutation-positive cases had a relatively poor prognosis, consistent with previous reports, and were more frequently accompanied by distant metastasis. HRAS knockdown with siRNA suppressed the in vitro migration ability of HRAS mutation-positive cells but not that of HRAS mutation-negative cells. In conclusion, a positive HRAS mutation could be an indicator of distant metastasis and poor prognosis, as well as a potential therapeutic target. Full article

As an important component of terrestrial ecosystems, mountain vegetation serves as an indicator of climate change. Due to the sensitivity of the Tibetan Plateau Mountains (TPM) to climate change and their ecological fragility, their vegetation dynamics (greenness and greening) have become a hot spot issue in global environmental change. Topography is a relatively stable environmental factor that shapes vegetation by creating localized microenvironments. However, existing research primarily focuses on the effects of climate change and human activities on vegetation dynamics. Therefore, a more comprehensive understanding of the dependence of vegetation dynamics on topography is needed. To elucidate the relationship between topography and the spatial heterogeneity of vegetation dynamics, we conducted this study using the recently released high-precision Sensor-Independent Leaf Area Index product. Through long-term trend analyses and joint comparisons of multiple topographic variables, this study elucidates key patterns: (1) North-facing slopes exhibit higher vegetation greenness and stronger greening trends than south-facing slopes, whereas east- and west-facing slopes show comparable greenness but stronger greening on west-facing slopes. (2) Vegetation greenness and greening increase with slope steepness. (3) With increasing elevation, greenness decreases progressively, while greening follows a unimodal pattern—initially increasing, then decreasing, and nearing zero at high altitudes. These findings underscore the pivotal role of topography in regulating vegetation responses to climate change. This study provides new insights into the interplay between topography and vegetation dynamics, advancing our understanding of ecological processes on the TPM and informing strategies for ecosystem management under global warming. Full article

Rapid urbanization in Kathmandu Valley has strained its aquifer system, causing significant land subsidence. This study employs LiCSBAS for InSAR processing of Sentinel-1 data (2017–2024) to map subsidence-prone areas. The significant subsidence was found in northwest (Baluwatar, Samakhusi, and Manmaiju), southern (Gwarko, Patan, and Koteshwor), and northeast (Madhapur Thimi and Gathhaghar) regions with a maximum subsidence rate ~21 cm/yr. Subsidence has also expanded towards the outskirts and open areas in the eastern and southern parts of Lalitpur and Bhaktapur districts. Emerging hot spot analysis reveals a slowing subsidence trend in high-risk zones, possibly linked to the MWSP project reducing groundwater extraction from 58 MLD (2021) to 26 MLD (2024). Many subsidence-affected areas are located over the Kalimati and Gokarna Formations in highly urbanized areas. The key contributing factors to subsidence are soil compaction, excessive groundwater use, and urban sprawl encroaching open areas and recharge zones. These findings underscore the urgent need for sustainable groundwater management and land-use planning to promote urban resilience. Full article

Lung and bronchus cancer, collectively called lung cancer, remains one of the most lethal malignancies worldwide, with its incidence and mortality rates continuing to pose significant public health challenges. Numerous studies have explored various risk factors for lung cancer, including smoking, environmental pollutants, genetic predispositions, and occupational hazards. However, emerging research suggests that elevation above sea level may also influence lung and bronchus cancer prevalence and outcomes. We analyzed elevation data for 2662 contiguous U.S. counties to determine if there is a significant relationship between lung cancer and elevation. Moreover, we employed hierarchical multiple regression and a complex sample general linear model (CSGLM) to enhance the understanding of the factors influencing lung and bronchus cancer, with a particular focus on elevation. Using Local Moran’s I cluster analysis, we identified statistically significant hot spots and cold spots for the mortality rate related to lung cancer. In the hierarchical regression model, a significant correlation between lung cancer and elevation remained evident. This suggests that the risk of mortality from lung and bronchus cancer increases with decreasing elevation (R² = 0.601). Furthermore, within the CSGLM framework, an R² value of 0.763 highlighted a strong link between lung cancer mortality and elevation. This relationship remained significant even after accounting for complex sample designs and applying weight adjustments. This geographic correlation has not been documented in previous studies. Further research is necessary to elucidate the precise mechanisms through which elevation influences lung cancer biology. Full article

The vulnerability of Social–Ecological Systems (SES) is a frontier research topic in the field of geography. Research on drought vulnerability has emerged as a key area of focus in the study of SES vulnerability, and it has increasingly been recognized as a critical step in formulating policies for drought prevention and mitigation. In this study, the indicator system for drought vulnerability evaluation of SES in the Three-River Headwaters Region (TRHR) was established. This paper revealed the drought vulnerability evolution process and characteristics, and key driving indicators of SES at county-town-village spatial scales in six time periods of 1990, 2000, 2010, 2015, 2020, and 2023, and predicted the drought vulnerability of SES in 2050 under two scenarios. Results indicate that the average drought vulnerability in the TRHR decreased from 0.526 in 1990 to 0.444 in 2023. Compared to 1990, among the 82 selected towns, 85.37% experienced a decline in 2023, and among the 152 selected villages, 95.39% showed a reduction in 2023. Hot spots of drought vulnerability were concentrated in the southeast of the TRHR, while cold spots were in the northwest. From 1990 to 2000, the drought vulnerability of counties and towns in the TRHR increased, but it decreased between 2000 and 2023. In 1990, Henan County exhibited the highest drought vulnerability at the county level. Waeryi Town in Jiuzhi County had the highest vulnerability among towns, while Suojia Town in Zhidoi County had the lowest. Of the 152 selected villages, 41.45% exhibited relatively high or high levels of drought vulnerability, while 23.68% showed relatively low levels. In 2023, Jiuzhi County became the most vulnerable county, with Baiyu Town in Jiuzhi County ranking highest among towns and Suojia Town in Zhidoi County remaining the least vulnerable. At the village level, 22.37% exhibited relatively high or high vulnerability, whereas 42.11% showed relatively low or low levels. Drought disaster records, the proportion of agricultural and animal husbandry output value, the proportion of grassland, the proportion of large livestock, and the per capita disposable income surface are the key factors influencing drought vulnerability in the TRHR. By 2050, under the first scenario, the average drought vulnerability of the TRHR is projected to be 0.428, indicating a medium level, while the second scenario predicts a further reduction to 0.350, representing a relatively low level. The adaptive governance strategies to mitigate drought vulnerability in the TRHR include developing an integrated drought management system; establishing an ecological management, protection, and financial support model; and so on. Overall, this paper can provide scientific references and policy recommendations for policymakers and researchers on the aspects of drought vulnerability and sustainable development of SES. Full article

The dynamics of shallow water areas of inland lakes is closely related to the regional ecology and economy. However, it is still a challenge to extract the natural shallow water area for inland lakes using satellite images due to their rapid changes and various human demands. Therefore, we developed a new remote sensing-based method applied in Hongze Lake (one of the largest freshwater lakes in China) to first delineate the lake from the SWIR1 band of Landsat OLI imagery using cold spots in the LISA method, and then distinguish deep and shallow water areas from the G band of Landsat OLI images using hot spots with LISA after masking the lake out, and finally extracting the natural shallow water area by masking aquatic farms out from shallow water areas using farm ridge classification from NDWI images and aggregating points of farm ridges. The results show that (1) the method of this study is efficient in extracting the natural shallow water area with limited effects from aquatic vegetation; (2) water inflow (upstream water supply and precipitation) and the area of aquatic farms, the two dominant factors for the temporal changes in natural shallow water area, contributed 38.3% (positively) and 42.2% (negatively) to the decrease in the natural shallow water area during 2013–2022 in Hongze Lake; (3) the natural shallow water area of Hongze Lake decreased significantly every April as paddy rice farms withdrew a large amount of irrigation water from Hongze Lake. Our research provides a new approach to extract the natural shallow water areas of inland lakes from satellite images and demonstrates that the upstream water supply, precipitation, and agriculture demands are the three main reasons for seasonal and temporal variations in natural shallow water areas for inland lakes. Full article

The real-time temperature prediction of chips is a critical issue in the semiconductor field. As chip designs evolve towards 3D and high integration, traditional analytical methods such as finite element software and HotSpot face bottlenecks such as high difficulty in modeling, costly computation, and slow inference speeds when dealing with large-scale, multi-hotspot chip thermal analysis. To address these challenges, this paper proposes a real-time temperature prediction model for multi-core chips based on Graph Convolutional Neural Networks (GCNs) that includes the following specific steps: First, the multi-core chip and its temperature power information are represented by a graph according to the physical pattern of heat transfer; Second, three strategies—full connection, setting a truncation radius, and clustering—are proposed to construct the adjacency matrix of the graph, thus supporting the model to balance between computational complexity and accuracy; Third, the GCN model is improved by assigning learnable weights to the adjacency matrix, thereby enhancing its representational power for the temperature distribution of multiple cores. Experimental results show that, under different node numbers and distributions, our proposed method can control the Mean Squared Error (MSE) error of temperature prediction within 0.5, while the single inference time is within 2 ms, which is at least an order of magnitude faster than traditional methods such as HotSpot, meeting the requirements for real-time prediction. Full article

We investigate the resonant characteristics of planar surfaces and distinct edges of structures with the excitation of phonon-polaritons. We analyze two materials supporting phonon-polariton excitations in the mid-infrared spectrum: silicon carbide, characterized by an almost isotropic dielectric constant, and hexagonal boron nitride, notable for its pronounced anisotropy in a spectral region exhibiting hyperbolic dispersion. We formulate a theoretical framework that accurately captures the excitations of the structure involving phonon-polaritons, predicts the response in scattering-type near-field optical microscopy, and is effective for complex resonant geometries where the locations of hot spots are uncertain. We account for the tapping motion of the probe, perform analysis for different heights of the probe, and demodulate the signal using a fast Fourier transform. Using this Fourier demodulation analysis, we show that light enhancement across the entire apex is the most accurate characteristic for describing the response of all resonant excitations and hot spots. We demonstrate that computing the demodulation orders of light enhancement in the microscope probe accurately predicts its imaging. Full article