Investigation of Structure of the High-Entropy Alloy Al_0.5CoCrCuFeNi

A detailed examination of the structure of the high-entropy alloy Al_0.5CoCrCuFeNi at room temperature was carried out using different methods of optical microscopy, electron microscopy and X-ray structural analysis techniques. Numerical estimates of the dislocation density ∼5⋅10¹⁵ m⁻², the mean size of the ordered (crystalline) domains ~18 nm and lattice micro strain ∼3⋅10⁻³ were obtained through Williamson-Hall analysis of XRD patterns. The estimates of the dislocation density were found to correlate with the estimates of the total length of dislocation segments per unit volume, which effectively interact with elastic vibrations of the sample ∼4⋅10¹³ m⁻², as previously determined from acoustic relaxation measurements. This is consistent with the idea that a significant portion of dislocations are concentrated in grain boundaries, and only dislocation segments located inside grains and having a favourable orientation with respect to the direction of sound wave propagation can effectively interact with cyclic deformation of the sample.

Multi-Response Optimization of Rigid Flange Coupling Using Taguchi Design, ANOVA, and FEA in Dual Environmental Conditions

This study investigates the mechanical behaviour and optimization of rigid flange couplings operating under two distinct environmental conditions: normal atmospheric air and high-pressure oil surroundings. A Taguchi L9 orthogonal array was employed to evaluate material combinations for the shaft, flange, and bolt based on four mechanical responses: total deformation, equivalent stress, shear stress, and normal stress. Analysis of variance (ANOVA) and regression modelling were used to identify significant parameters, with flange material consistently emerging as the most influential factor. Desirability analysis was conducted to determine the optimal material configurations for each environment. Under atmospheric conditions, the combination of C30 shaft, FG200 flange, and C45 bolt achieved a composite desirability of 0.6667. In high-pressure oil conditions, the optimal configuration was C45 shaft, FG260 flange, and C45 bolt, with a desirability of 0.7185. These optimal settings, not present in the original matrix, were independently validated using finite element analysis (FEA). The comparison between regression predictions and FEA results showed strong agreement, with a maximum percentage error of 6.02%, within acceptable engineering limits. This study confirms that environmental pressure significantly influences coupling performance and that material selection should be tailored accordingly. The integration of statistical optimization and simulation offers a robust framework for designing couplings in pressure-sensitive applications.

Epithelial-Mesenchymal Niche Dysfunction in COPD: Emerging Opportunities for Targeting Cellular Plasticity and Crosstalk

Chronic obstructive pulmonary disease (COPD) is a leading cause of global morbidity and mortality, characterized by progressive airway and alveolar remodeling. The disease pathogenesis is commonly driven by chronic environmental insults, leading to airway obstruction, emphysema, and chronic bronchitis. This review synthesizes emerging evidence that altered epithelial cell behavior and dysfunctional epithelial-mesenchymal interactions serve as pivotal drivers of COPD pathogenesis, orchestrating failed repair and structural degeneration. We detail how altered responses of airway (ciliated, club, basal, goblet) and alveolar (AT1 and AT2) epithelial cells lead to cellular senescence, metaplasia, defective regeneration, and barrier disruption, acting as primary instigators of pathogenesis. We also summarize current knowledge on the mechanisms of activation and pathogenic role of mesenchymal cells, which drive peribronchiolar fibrosis, alveolar destruction, and metabolic reprogramming, alongside the compromised reparative function of mesenchymal stem cells (MSCs). We emphasize how distinct mesenchymal niches (e.g., PDGFRα^Pos MANCs, FGF10^Pos lipofibroblasts, SFRP1^Pos fibroblasts) and distinct epithelial stem/progenitor subpopulations critically contribute to pathogenesis. Key signaling pathways—including FGF10/FGFR2b, WNT, Hippo, NOTCH, and TGF-β—mediate epithelial-mesenchymal transition (EMT), stem cell niche function, and structural remodeling. By dissecting how epithelial injury responses and mesenchymal niche failure collaboratively drive COPD progression, we identify actionable targets to disrupt pathogenesis and restore endogenous repair. We propose targeting EMT, including inhibiting EMT/fibrosis, promoting alveolar regeneration, MSC-based therapies, exosome-delivered biomolecules, and precision cell transplantation strategies, as promising future therapeutic strategies.

Open Water in Winter: An Influential but Underestimated Ecosystem in Northern Boreal Mountain Regions

Patches of open water (polynyas) persist throughout six-month winters on many ice-covered lakes in boreal mountain ecoregions of northwestern North America. We explored their distribution, hydrological correlates, and the diversity of species using them from freeze-up to break-up. In headwater drainages, lakes with outflow polynyas were significantly larger than those without, but many small lakes also had polynyas. There was a consistent threshold in upstream catchment size below which outflow polynyas were absent and above which they persistently occurred in downstream lakes. Outflow polynyas depend on winter-long through-flow of water, likely maintained by the hydraulic head of higher elevation ground water in perched water tables in this region of very limited permafrost. Based on camera trapping, two species, the American dipper and river otter, used polynyas heavily throughout winter foraging. Polynyas likely provided crucial forage for at least 9 species of migratory waterfowl (Anatidae) to complete their spring migration or to prepare for reproduction on local lakes. Cameras recorded additional 5 bird and 11 mammal species, as foragers, scavengers, or incidentally. We report previously undocumented significance of these spatially-limited and seasonal polynya ecosystems in expanding the diversity of winter ecological opportunity for numerous species on small to medium-sized lakes.

Collagen Biosynthesis to Engineered Biomaterials: Molecular Design, Synthetic Strategy, and Biomedical Application

Collagen, a principal component of the extracellular matrix, provides mechanical strength and stability to tissues and organs through its structural organization. Its biocompatibility has established it as a crucial material in biomedical applications such as drug delivery systems, cell culture matrices, and tissue engineering scaffolds. However, the use of animal-derived collagen carries risks of pathogen transmission, which has driven research towards developing synthetic collagen alternatives. Advances in AI-assisted protein engineering are accelerating the design of synthetic collagens and their applications in biomaterials. This review examines collagen’s structural characteristics, biosynthesis strategies, biological activities as well as AI-assisting engineering.

From Fossil to Future: Trade, Technology and Clean Energy Transitions in High-Impact Developing Economies

This study examines the impact of economic growth, renewable energy equipment imports, and energy use on CO₂ emissions in seven developing countries over the period 2000–2021, employing second-generation panel estimators (Augmented Mean Group AMG, The Common Correlated Effects Mean Group CCEMG) that account for cross-sectional dependence and slope heterogeneity. Results show that economic growth and energy use significantly increase emissions, while renewable energy equipment imports display no direct or robust mitigating effect. This limited impact likely reflects adoption and integration challenges and the absence of complementary policies, underscoring the need for strategies that link imports to technology transfer and domestic manufacturing capacity. Granger causality tests indicate that growth and renewable energy imports drive emissions, highlighting the necessity for integrated green industrial policies, carbon pricing mechanisms, and sustainable finance instruments. These findings suggest that, for developing economies, achieving low-carbon growth requires a coordinated policy mix that aligns environmental objectives with economic development goals.

Why Watershed Ecology?

Physiopathological Insights into Atrial Fibrillation Onset through Heart Rate Variability Correlations

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with increased morbidity and mortality. Early prediction of AF episodes remains a clinical challenge. This study aimed to generate physiopathological hypotheses for AF onset by analyzing correlations among heart rate variability (HRV) parameters in patients monitored via long-term Holter ECG. We utilized the IRIDIA-AF database, comprising 1319 paroxysmal AF episodes from 872 patients. An XGBoost machine learning model was developed to predict AF onset within 24 h using short- and long-term HRV features, fragmentation indices, and non-linear metrics extracted during sinus rhythm. Model interpretation was performed using SHapley Additive exPlanations (SHAP) values, and dimensionality reduction techniques were applied for data visualization. The model achieved an area under the receiver operating characteristic curve of 0.919 and an area under the precision-recall curve of 0.919, with high accuracy, sensitivity, and specificity. Key predictive features included short-term vagal activity, HRV fragmentation indices, and non-linear parameters, highlighting the role of the autonomic nervous system in AF initiation. Our findings suggest that distinct physiological profiles, detectable via HRV, may underlie AF susceptibility and could inform personalized monitoring and prevention strategies.

The Thermal Impact of Various Pavement Materials on Outdoor Temperature in a Temperate Four-Season Climate: A Case Study of Arak City, Iran

Urban heat and oasis effects significantly alter urban microclimates due to anthropogenic heat emissions and the thermal properties of urban surfaces. This study aims to quantitatively assess the thermal effects of different pavement types on outdoor temperatures across seasonal extremes in a temperate four-season climate. Conducted in Arak city, Iran, on 22 July and 22 January 2023, this research investigates both warm and cold seasons to provide a comprehensive understanding of pavement influence on urban microclimates throughout the year. Using the ENVI-met 5.0.3 modeling software, an environmental meteorology tool for simulating urban microclimates, the thermal performance of commonly used asphalt pavement was compared with alternative materials such as basalt and light-colored concrete on Dr. Hesabi Street. Simulation results reveal that basalt and light-colored concrete pavements reduce summer cooling loads by up to 3.49 degrees Celsius (°C), enhancing pedestrian thermal comfort, but simultaneously increase winter heating demands by 1.04 °C. This balance presents an optimal scenario to minimize adverse climate effects across seasons. The findings offer valuable insights for sustainable urban planning, promoting resilient city design strategies that mitigate heat and oasis effects in diverse climates. This study contributes actionable recommendations for urban planners seeking to balance thermal performance in temperate climates with seasonal variability.

Initiation of Surface Processes by Resonance IR Laser Excitation—State and Perspectives

A possibility to initiate surface reactions by resonant IR laser radiation has been studied. Several systems have been tried, including those with linkage isomerism, such as CO bound to cations in zeolites, decomposition of adsorbed unstable molecules like ozone or HN₃, reactions of vibrationally excited molecules with coadsorbed species, or the effect of resonance excitation of hydroazide acid HN₃ upon its ability to induce the protonation of dimethylpyridine adsorbed on silanol groups of silica. In almost all the experiments, the changes caused by irradiation were weak, and isotopic selectivity was rather poor. The choice of systems and possible ways to improve their characteristics are discussed as well as the perspectives of their usage for isotope separation or other practical tasks.