Search Results (10,838)

Bronze materials are indispensable across numerous industries for enhancing the durability and performance of components, primarily due to their excellent tribological properties, corrosion resistance, and machinability. This study investigates the impact of different atmospheric conditions on the properties of WAAM (wire arc additive manufacturing) cladded bronze coatings on 09G2S steel substrate. Specifically, the research examines how varying atmospheres—including ambient air (N₂/O₂, no shielding gas), pure argon (Ar), carbon dioxide (CO₂), and 82% Ar + 18% CO₂ (Ar/CO₂) mixture—influence coating defectiveness (porosity, cracks, non-uniformity), wettability (manifested as uniform layer formation and strong adhesion), and the extent of intergranular penetration (IGP), leading to the formation of characteristic infiltrated cracks or “bronze whiskers”. Modern investigative techniques such as optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were employed for comprehensive material characterization. Microhardness testing was also carried out to evaluate and confirm the homogeneity of the coating structure. The findings revealed that the bronze coatings primarily consisted of a dominant, highly textured FCC α-Cu phase and a minor BCC α-Fe phase, with Rietveld refinement quantifying a α-Fe volume fraction of ~5%, lattice parameters of a = 0.3616 nm for α-Cu and a = 0.2869 nm for α-Fe, and a modest microstrain of 0.001. The bronze coating deposited under a pure Ar atmosphere exhibited superior performance, characterized by excellent wettability, a uniform, near-defect-free structure with minimal porosity and cracks, and significantly suppressed formation of bronze whiskers, both in quantity and size. Conversely, the coating deposited without a protective atmosphere demonstrated the highest degree of defectiveness, including agglomerated pores and cracks, leading to an uneven interface and extensive whisker growth of varied morphologies. Microhardness tests confirmed that while the Ar-atmosphere coating displayed the lowest hardness (~130 HV_0.1), it maintained consistent values across the entire analyzed area, indicating structural homogeneity. These results underscore the critical role of atmosphere selection in WAAM processing for achieving high-quality bronze coatings with enhanced interfacial integrity and functional performance. Full article

Background/Objectives: Eating disorders (EDs) in adolescents are increasingly prevalent. In South Tyrol, a bilingual region in Northern Italy, not only actual gender and age prevalences can be compared to screening rates, but even the comparability of screening tools across languages can be examined. Methods: A cross-sectional analysis integrated clinical registry data with representative, online school-recruited adolescents (11 to 17) self-reports. 166 clinically diagnosed cases and 1465 screened adolescents (1246 German, 219 Italian), were examined. The SCOFF questionnaire (cutoff ≥ 2 for German and ≥3 for Italian), body mass index, body image perception, psychosocial and lifestyle indicators in proxy and self-reports were examined using descriptive statistics and logistic regression. Results: The clinical dataset for 2024 has a prevalence rate of 0.4%. The SCOFF screening tool identified symptomatic cases in 10.6%, and an age-increasing trend among females. The overall SCOFF-prevalence did not differ between language versions, although responses to individual items varied significantly. Predictors of ED included body image, psychosomatic complaints, problematic social media use, and low social support, with differences between genders. Parents tended to underestimate their children’s perception of being “too thick.” Conclusions: In early adolescence, preventive strategies are needed and targeted interventions in late adolescence. For early detection and intervention, gender-sensitive prevention and active parental involvement is needed. The SCOFF questionnaire demonstrates utility across both languages, but bilingual comparison highlights the need for culturally adapted tools and cross-language validation. Full article

Background: Eating disorders (EDs) adversely affect health and athletic performance, yet their prevalence in adolescent female team athletes is understudied. Objectives: This exploratory pilot study assessed ED presence and associated factors in female basketball players aged 10–18 years from a high-level club in Granada, Spain. Methods: This cross-sectional pilot study examined 36 participants (mean age 13.3 ± 2.2 years) who completed the Spanish Eating Disorder Examination Questionnaire (S-EDE-Q). Body composition (Tanita TBF-300), sociodemographic characteristics, and sport-related factors were recorded. Associations between these covariates and S-EDE-Q global scores (GS) were examined via linear regression. Results: A higher Global Score (GS), indicating increased ED risk, correlated significantly with several factors: Lower paternal education (primary vs. university: p < 0.005) and lower socioeconomic level. Older age (AME = 0.30; p < 0.005) and greater muscle mass (p < 0.001). National competition level (p < 0.001), being a player in the pivot position (mean GS = 1.62), and presence of sport-related medical history (mean GS = 1.07). No associations were found with sport experience or weekly training hours. Conclusions: Although the overall risk of EDs is low, the association with specific factors (sociodemographic, anthropometric, and sports-related) allows vulnerable players to be identified. Longitudinal and larger-scale research is needed to confirm these initial findings and design targeted and early prevention strategies. Full article

Aiming at the drawbacks of the classic CoCrFeNi high-entropy alloy (HEA)—low room-temperature strength and softening above 600 °C, which fail to meet strict material requirements in high-end fields like aerospace—this study used the vacuum hot-pressing sintering process to prepare CoCrFeNiTa_x HEAs (x = 0, 0.5, 1.0, 1.5, 2.0 atom, designated as H4, Ta_0.5, Ta_1.0, Ta_1.5, Ta_2.0, respectively). This process effectively inhibits Ta segregation (a key issue in casting) and facilitates the presence uniform microstructures with relative density ≥ 96%, while this study systematically investigates a broader Ta content range (x = 0–2.0 atom) to quantify phase–property evolution, differing from prior works focusing on limited Ta content or casting/spark plasma sintering (SPS). Via X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), microhardness testing, and room-temperature compression experiments, Ta’s regulatory effect on the alloy’s microstructure and mechanical properties was systematically explored. Results show all alloys have a relative density ≥ 96%, verifying the preparation process’s effectiveness. H4 exhibits a single face-centered cubic (FCC) phase. Ta addition transforms it into a “FCC + hexagonal close-packed (HCP) Laves phase” dual-phase system. Mechanically, the alloy’s inner hardness (reflecting the intrinsic property of the material) increases from 280 HV to 1080 HV, the yield strength from 760 MPa to 1750 MPa, and maximum fracture strength reaches 2280 MPa, while plasticity drops to 12%. Its strengthening mainly comes from the combined action of Ta’s solid-solution strengthening (via lattice distortion hindering dislocation motion) and the Laves phase’s second-phase strengthening (further inhibiting dislocation slip). Full article

Rationale and Objective: Medical imaging, particularly computed tomography (CT), is the largest man-made contributor to collective radiation exposure. This study compares methods for assessing CT radiation dose, focusing on thoracic examinations. Population investigated: We retrospectively analyzed 3956 non-contrast thoracic CT exams from 1553 females (mean age 70 ± 12 years) and 2403 males (mean age 69 ± 12 years). Methods: Data were acquired using a Siemens Somatom Force CT-Scanner (installed in 2015). Exposure parameters and patient somatic data were recorded and used as inputs for the Virtual Dose Simulator (VDS), which served as the gold standard for effective dose (ED^ref) measurement. Additionally, ED was calculated using two ICRP-103 K-factor methods: Shrimpton et al. (ED^shr) and Romanyukha et al. (ED^rom). Results: Regression analysis demonstrated strong linear relationships between ED^ref and both weight and BMI (R² ≥ 0.84), with ED^ref values ranging from 1.55 to 4.59 mSv. Even stronger linear relationships were observed between ED^ref and CT scanner tube current, particularly for women (R² = 0.93) and men (R² = 0.90). Similar trends emerged for dose-length product (DLP), which showed high correlations for both women (R² = 0.95) and men (R² = 0.94). Compared to VDS, ED^rom underestimated women’s doses by 10% and slightly overestimated men’s doses by 1%, while ED^shr underestimated the effective dose by 18% for women and 9% for men. Conclusion: This study demonstrates that K-factor methods provide a simple, efficient, and clinically practical approach for both individual cumulative dose monitoring (critical for patients requiring repeated imaging) and population-level dose assessment (essential for epidemiological risk evaluation). The high reliability of K-factor-based estimates, as demonstrated in this work, underscores their potential for integration into clinical practice to enhance dose optimization and patient safety. Full article

Estimated climate change scenarios demand robust coffee cultivars tolerant to supra-optimal temperatures, water deficit, diseases, and other stresses. Wild Coffea species represent important genetic resources for resilience. The study of variations in morphological structures associated with transpiration control, such as stomata, represents an important approach for identifying genotypes with greater stress tolerance. This study evaluated stomatal density and morphology in 48 wild accessions, 24 of Coffea racemosa and 24 of C. zanguebariae, from provinces of Mozambique. Leaf samples provided microscopic images to assess stomatal traits: density (SD), polar diameter (PD), equatorial diameter (ED), stomatal functionality (SF), and leaf dry mass. Principal components were analyzed for all 48 accessions and separately by species. Mean distribution independence was tested with the Mann–Whitney test (p < 0.05). Results revealed inter- and intraspecific variation. The ability to distinguish accessions varies with the set of traits and species. A significant negative correlation between ED and SF was shared by both species, suggesting a conserved functional pattern. This study discusses the differences in stomatal traits between wild and commercial coffee species and aspects related to possible alterations of stomatal structures during their adaptation to climate change. Additionally, it points to accessions with potential use in genetic breeding programs to increase stomatal function and the possible adaptation of new cultivars. Full article

Despite extensive work on FeOCl-based photocatalysts, few studies have explored rare-earth (Ce) doping to simultaneously tune bandgap, suppress charge recombination, and enhance visible light-driven persulfate (PS) activation for the degradation of emerging contaminants. This study synthesized FeOCl/Ce composite photocatalysts via a partial pyrolysis method and systematically characterized their physicochemical properties. The results show that Ce doping significantly lowers the bandgap energy of the photocatalyst, enhances its visible light absorption ability, and effectively suppresses the recombination of photogenerated electron–hole pairs, thereby markedly improving photocatalytic performance under visible light. Analyses including XRD, EDS, XPS, and FT-IR confirm that Ce is incorporated into the FeOCl matrix and modulates the radial growth behavior of FeOCl without altering its intrinsic crystal structure. Morphological observations reveal that FeOCl/Ce exhibits a uniform nanosheet layered structure, with larger particles formed by the aggregation of smaller nanosheets. The nitrogen adsorption–desorption isotherm of FeOCl/Ce shows characteristics of Type IV with a relatively small BET surface area. The broadened optical absorption edge of FeOCl/Ce and the results of PL spectra and I-T curves further confirm its enhanced visible light absorption capacity and reduced electron–hole recombination compared to pure FeOCl. At an initial caffeine (CAF) concentration of 10 μM, FeOCl/Ce dose of 0.5 g/L, PS concentration of 1 mM, and initial pH of 5.06, the FeOCl/Ce-catalyzed PS system under visible light irradiation can degrade 91.2% of CAF within 30 min. An acidic environment is more favorable for CAF degradation, while the presence of SO₄²⁻, Cl⁻, and NO₃⁻ inhibits the process performance to varying degrees, possibly due to competitive adsorption on the photocatalyst surface or quenching of reactive species. Cyclic stability tests show that FeOCl/Ce maintains good catalytic performance over multiple runs. Mechanistic analysis indicates that ^•OH and holes are the dominant reactive species for CAF degradation, while PS mainly acts as an electron acceptor to suppress electron–hole recombination. Overall, the FeOCl/Ce photocatalytic system demonstrates high efficiency, good stability, and visible light responsiveness in CAF degradation, with potential applications for removing CAF and other emerging organic pollutants from aquatic environments. Full article

Background/Objectives: We sought to determine the factors associated with Emergency Department (ED) healthcare workers (HCW) reluctance to seek, utilize, or take advantage of psychological support services during the pandemic. Methods: A 53-item survey, delivered via REDCap, was completed by ED staff in seven hospitals between 15 July 2020 and 24 August 2020. Results: 351 participants (28.7% response rate) completed the survey with 20.1% of respondents endorsing clinically significant psychiatric symptoms and 31.7% of participants endorsing burnout. 75% of those who endorsed significant emotional symptoms did not seek formal psychological support. Most of those (33/44) who did not seek support, despite anxiety and/or depression, reported experiencing practical barriers (access, cost, time, confidentiality) while emotional barriers (not wanting to acknowledge needing help; stigma; embarrassment) were endorsed by 22.7% (10/44). Conclusions: These findings offer several opportunities for intervention, including changes to workflow and culture in the ED which may address emotional barriers to self-care and pragmatic system changes that may help address practical barriers. Full article

Background: The duration of protection that COVID-19 vaccination provides against severe outcomes remains uncertain. Accurately defining this timeframe is critical for informing effective vaccination policies and booster strategies. This investigation aimed to quantify the length and durability of vaccine-conferred protection against severe disease, delivering evidence to guide public health decision-making. Methods: We conducted a multi-site cohort study to evaluate the relationship between time since last COVID-19 vaccination and the risk of severe infection among emergency department (ED) patients with a principal diagnosis of COVID-19. Vaccination status was categorized by time since the last documented dose: unvaccinated, 0–6 months, 7–12 months, 13–18 months, and 19–24 months. The primary outcome was severe COVID-19, defined as ICU admission, mechanical ventilation, or in-hospital death. Inverse Probability of Treatment Weighting (IPTW) was used to adjust for baseline confounding based on age group, sex, race, comorbidity burden, immunocompromised status, and calendar time period (pre-2023 vs. post-2023). Cox proportional hazards models were used to estimate adjusted hazard ratios (aHRs) for each vaccination interval compared to unvaccinated patients. Results: Between 1 December 2021, and 20 July 2024, 42,124 ED encounters were included in the analysis. In IPTW-weighted models, vaccination within 0–6 months (aHR 0.73, 95% CI 0.64–0.83), 7–12 months (aHR 0.72, 95% CI 0.64–0.82), and 13–18 months (aHR 0.67, 95% CI 0.57–0.79) was associated with a significantly reduced risk of severe outcomes. However, no significant protection was observed at 19–24 months (aHR 0.95, 95% CI 0.80–1.14). In age-stratified analyses, protection persisted longer in individuals aged ≥65 years than in those aged 50–64. Older age, male sex, comorbidities, and immunocompromised status were also associated with increased risk. Conclusions: COVID-19 vaccination provides sustained protection against severe outcomes for up to 18 months, after which effectiveness declines substantially. These findings support booster dose strategies based on time since last vaccination and targeted prioritization for high-risk populations. Full article

The surface of the Fe40Al5Cr0.2TiB alloy, after oxidation in steam at 700 °C, showed a varied morphology dependent on oxidation time. Initially, a fine, acicular oxide layer formed, which over time transformed into a more compact, lumpy structure corresponding to the α-Al₂O₃ phase. EDS analysis confirmed the dominance of aluminum and oxygen in the oxidation products, and XRD studies revealed the presence of the α-alumina phase. Optical profilometry revealed a significant increase in roughness parameters (R_a and R_z) after long-term exposure (2000 h), which correlates with the thickening and sinterization of the oxide layer. The obtained results indicate that in a water vapor environment, a stable α-Al₂O₃ phase can already be formed at a temperature of 700 °C, and its development leads to increased roughness. Full article

High-entropy alloys (HEAs) have recently attracted considerable attention due to their unique combination of high strength, hardness, and corrosion and wear resistance, making them promising candidates for advanced structural and functional applications. Among these, AlCoCrFeNi-based HEAs are well known for their high hardness and good wear resistance; however, their limited tribological stability under operational conditions restricts their broader application. To address this limitation, tungsten (W) was incorporated into the AlCoCrFeNi system to enhance its mechanical and tribological performance. In this study, the microstructural, mechanical, and tribological properties of AlCoCrFeNiW_x (x = 0, 0.1, 0.25, 0.5 and 1 mol) HEAs were systematically investigated. The alloys were fabricated using the vacuum arc melting method and characterized by XRD, SEM-EDS, elemental mapping, microhardness, and wear tests. The addition of W caused a shift in the 2θ ≈ 44° (110) peak toward lower angles. While the W-free alloy exhibited Body-Centered Cubic (BCC) + B2 phases, W addition led to the formation of a new W-rich phase, and at higher W contents, a pure W phase appeared. The hardness increased from 507.11 HV₁ to 651.81 HV₁ with increasing W content. Furthermore, wear resistance improved and the coefficient of friction decreased with higher W addition. When comparing the W-free alloy to the alloy with the highest W content, the wear rate decreased by approximately 1.85 times under a 2 N load and 1.89 times under a 5 N load. These results demonstrate that W addition significantly enhances the wear resistance of AlCoCrFeNi-based HEAs by nearly twofold. Full article

Fine particulate matter (PM_2.5) is a well-established health hazard, yet population-level causal evidence on the long-term effects of its chemical constituents and their interactions with environmental and socioeconomic factors remains scarce. This study leveraged quasi-experimental variation in PM_2.5 exposure across Guangdong province, China, during 2007–2018 to evaluate its causal impact on emergency department (ED) visits. We applied a Difference-in-Differences (DID) causal inference framework to obtain counterfactual estimates of long-term exposure effects and complemented this with generalized Weighted Quantile Sum (gWQS) regression to treat PM_2.5 as a complex mixture, quantify joint effects, and identify toxic components. The results showed that each interquartile increase in long-term PM_2.5 exposure was associated with a 10.2% rise in ED visits, with nitrate (weight = 0.299) and sulfate (0.294) contributing the most strongly, while organic matter exerted greater effects in less-developed regions. Temperature variation further modified these effects, with a 1 °C increase in average summer temperature associated with a 3.3% increase and a decrease in winter temperature linked to a 0.54% increase in constituent-related ED visits. Socioeconomic stratification revealed heterogeneous toxicity profiles across regions. These findings provide robust causal evidence on constituent-specific risks of PM_2.5, highlight the utility of integrating causal and mixture methods for complex exposures, and support targeted emission control and climate-adaptive strategies to protect vulnerable populations. Full article

Work investigates the doping of molybdenum oxide (MoO_x) with tungsten (W). The successful incorporation of W into the MoO_x lattice was confirmed through X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS). Structural and optical analysis revealed the presence of oxygen vacancies within the W-MoO_x film, which are known to facilitate resistive switching (RS) in memristive devices. Based on this, a flexible memristor with the structure PET/ITO/W-MoO_x/polymethyl methacrylate (PMMA)/Al was fabricated. PMMA was strategically introduced between the W-MoO_x layer and the aluminum electrode to modulate interfacial properties that influence RS behavior. The W-MoO_x/PMMA-based memristor exhibited good resistive switching characteristics, with a memory window of approximately 12 and a retention time exceeding 2 × 10⁴ s, demonstrating a non-volatile memory behavior. In the high-resistance state (HRS), the conduction mechanism under higher applied voltages follows a space-charge-limited current (SCLC) model, indicating that the RS process is primarily governed by charge trapping and de-trapping at the interface. Overall, the consistent and robust switching performance of the W-MoO_x/PMMA heterostructure underlines its potential as a reliable functional layer for next-generation resistive random-access memory (ReRAM) devices. Full article

In this work, samples of reduced graphene oxide (rGO) were prepared by treating graphite oxide (GrO) with thiourea (TU) and ascorbic acid (AA). Aerogels rGO-TU and rGO-AA were prepared using the freeze-drying method and were analyzed using X-ray diffraction, FTIR and Raman spectroscopy, ¹H and ¹³C NMR, TEM, and SEM-EDS. Based on the NMR, FTIR, SEM-EDS, and TEM data, GO with TU is reduced with simultaneous functionalization of its oxygen-containing groups. According to ¹H and ¹³C NMR data, the reduction of GO occurred simultaneously with an interaction of the amino groups of thiourea with carbonyl groups on the graphene sheets, forming an imine bond. This is evidenced by the appearance of additional signals in the ¹³C spectrum of GO-TU samples in the region of 140–230 ppm. The Boehm titration method showed that the number of oxygen-containing groups in rGO-TU aerogels decreased by about five times compared to GO. However, thiourea interacts with the GO surface, most likely due to electrostatic interaction and hydrogen bonds. The adsorption capacity of rGO-TU aerogel with respect to methylene blue (MB) after 1440 min was 60.2 mg/g, while for rGO-AA it was 71.4 mg/g. This fact indicates the importance of optimizing GO reduction to increase the number of active sites. Full article

Titanium alloy Ti-6Al-4V possesses excellent mechanical and corrosion-resistant properties; therefore, it is widely employed in aerospace, automotive, and biomedical fields. However, its poor machinability restricts traditional processing methods. To overcome this limitation, the current work presents a symmetry analysis approach to evaluate the effects of tool coating on the micro-electric discharge machining (micro-EDM) characteristics of Ti-6Al-4V. Tungsten carbide (WC) microelectrodes were fabricated in three forms: uncoated, copper-coated, and carbon-coated. The chemical vapor deposition (CVD) method was used to coat the carbon layer, and the integrity of the coating was confirmed by Energy-Dispersive X-ray Spectroscopy/Analysis (EDS/EDX). The effect of input variables—namely, voltage, capacitance, and spindle rotational speed—on two responses was studied—the machining depth (Z-axis displacement) and tool wear rate (TWR)—using a Taguchi L9 orthogonal array. Analysis conducted using Minitab statistical software 17 revealed that both voltage and capacitance contributed to the response parameters as optimized variables. The comparative study showed that the copper- and carbon-coated WC microtool could obtain a better Z coordinate and lower tool wear ratio compared with those of the uncoated tool. The findings confirm that applying thin conductive coatings to WC tools can significantly improve the stability, precision, and overall symmetry of the micro-EDM process when machining difficult-to-cut titanium alloys. Full article