Search Results (3,310)

The desert ecosystem harbors a resilient microbial community that sustains plant life under extreme stress. Understanding the endophytic microbiota of desert flora provides key insights into how these microorganisms enable plant survival and maintain ecological balance in arid landscapes. To date, the endophytic bacterial communities of dominant desert plants in the Arabian Peninsula have not been comprehensively characterized. Here, we investigated the endophytic microbiota of five co-adapted desert species, namely, Schweinfurthia papilionacea, Sesuvium verrucosum, Ochtocloa compressa, Helianthemum nummularium, and Convolvulus arvensis. These plants coexist in hyper-arid habitats and exhibit exceptional tolerance to drought, salinity, and nutrient scarcity. We hypothesized that, despite their phylogenetic divergence, these plants host functionally convergent microbial communities shaped by desert selection pressures. Using 16S rRNA gene amplicon sequencing, we obtained 3.4 million high-quality reads from 25 samples. Clustering at 97% similarity revealed 35 phyla and 17 dominant genera, highlighting notable microbial richness and ecological complexity. Alpha-diversity indices showed comparable species richness across hosts, while beta-diversity indicated community differentiation driven by environmental filtering. The dominant phyla included Pseudomonadota, Actinomycetota, Cyanobacteriota, and Bacillota, reflecting microbial adaptation to extreme desert conditions. Functional pathway prediction revealed enrichment of genes associated with DNA repair and protein turnover, suggesting metabolic flexibility and enhanced survival under stress. Overall, this study provides a comparative metagenomic insight into the endophytic bacterial communities of five desert plant species, uncovering a consistent pattern of functional convergence across diverse hosts. The findings suggest the presence of shared functional traits among the endophytic microbiota examined here, offering preliminary evidence for microbial contributions to plant resilience in arid environments. Full article

Aviation heavy-fuel piston engines are widely used in UAVs, general aviation, and military platforms due to their fuel efficiency and adaptability. However, emissions of NO_x, PM, and other pollutants pose significant environmental challenges. This paper reviews emission-reduction strategies, including combustion-chamber optimization, fuel-injection control, alternative fuels, and exhaust after-treatment technologies. Research indicates that optimizing combustion-chamber geometry, high-pressure common-rail injection, and turbulence enhancement improve combustion efficiency and reduce emissions. Biofuels, synthetic aviation fuels (SAF), and hydrogen-based fuels demonstrate strong potential for low-carbon emissions, while after-treatment technologies such as SCR, DPF, and EGR effectively mitigate NO_x and PM emissions. Despite technological advancements, challenges remain in balancing combustion efficiency with NO_x control and ensuring compatibility between EGR and combustion stability. Future advancements in intelligent combustion control, novel catalytic materials, low-temperature combustion, and high-efficiency after-treatment systems will drive aviation diesel engines toward lower emissions, higher efficiency, and greater intelligence, contributing to the green and sustainable transformation of aviation propulsion systems. Full article

Sewage sludge management remains a critical challenge in Greece, where increasing regulatory pressure, environmental constraints, and limited stakeholder participation complicate regional decision-making. In particular, the revision of regional Waste Management Plans requires decision-support approaches that are both technically robust and socially legitimate. This study develops and applies a participatory, data-driven multi-criteria decision analysis framework to evaluate sustainable sewage sludge management strategies in the Region of Eastern Macedonia and Thrace. The framework combines structured stakeholder participation with quantitative performance assessment, enabling transparent, reproducible, and systematic comparison of alternative sewage sludge management options. Four realistic sludge management alternatives—composting fr agriculture, forestry use, land restoration, and thermal drying with energy recovery were assessed against fifteen economic, environmental, and social sub-criteria. Data were collected through structured questionnaires administered to forty-four representatives from five stakeholder groups: utilities (water and sewerage service providers), local authorities, scientists/experts, end-users, and citizens. Group preferences were aggregated using equal group weighting to ensure balanced representation. The results show that environmental and economic criteria outweigh social aspects. The highest mean weights were assigned to compliance with environmental requirements for products derived from the disposal method (0.105) and compliance with stricter national environmental legislation (0.104), followed by energy intensity (0.097), installation cost (0.065), and operation and maintenance (O&M) cost (0.061). Overall rankings identified composting and thermal drying as the most preferred options, followed by land restoration and forestry use; sensitivity analysis (±10% variation in sub-criterion weights) confirmed ranking stability. The proposed framework enhances decision transparency by embedding measurable criteria and stakeholder inputs within a structured analytical process. From a policy perspective, it addresses participation gaps in Greek waste planning and offers a transferable decision-support tool for future regional planning. Further extensions may include integration with life cycle assessment and cost–benefit analysis to support adaptive updates under circular economy objectives. Full article

To evaluate the effectiveness of an adaptive physical education (APE) program using VR technologies, we studied the physical development and vitality indicators of college female students in two groups: those with and without functional health limitations (N = 70 each). Students with disabilities were randomly divided into experimental and control groups of 35 people each. The experimental group participated in physical education classes using VR. The health assessment included heart rate, blood pressure, and subjective health assessments. Physical development was assessed by the biological age index (BAI) by Voitenko, static balance duration, and breath-holding time. Psychological activity was assessed using the Mindfulness Attention Awareness Scale (MAAS), the Rezapkina Vitality Test, and the Subjective Vitality Scale (SVS). The delayed effect was assessed using a questionnaire. Students with functional impairments initially demonstrated a significant decrease in overall vitality, physical activity duration, and more negative health self-perception. After the virtual reality sessions, they showed a restoration of physical development and vitality indicators to levels close to healthy, as well as a decrease in BAI. The delayed effect was confirmed after three months. The use of virtual reality technologies in the APE program effectively improves the physical development and activity (vitality) of students with functional health impairments. Full article

Reliable and energy-efficient capacity control in high-pressure single-rotor screw compressors requires precise regulation of adjustable ring mechanisms operating under combined gas and thermal loading. Thermo-mechanical deformation, friction-induced torque demand, and stress concentration near discharge windows significantly influence structural integrity, clearance stability, and actuation performance. This study presents an integrated thermo-structural and analytical investigation of a regulating ring system with a hydraulic wedge-groove drive concept. Three groups of geometric variants (nine configurations total) were analyzed using coupled Steady-State Thermal and Static Structural finite element modeling in ANSYS 19.2. Thermal asymmetry between suction (22 °C) and discharge (120 °C) regions produced peak thermally induced deformation of 0.17–0.18 mm, consuming up to 60–70% of nominal operating clearance. Neglecting thermal effects underestimated peak thermally induced structural deformation of the regulating ring by 12–15%. Among the configurations, variant 2b provided the most balanced response, reducing peak equivalent stress by 12–15% and required actuation torque by 8–11%. An analytical model for friction torque and driving force was derived based on distributed contact pressure. The results reveal quadratic sensitivity of torque to contact radius and strong dependence on groove geometry. The proposed framework supports reliable clearance design and efficient actuation in heavy-duty rotating machinery. Full article

A common solution for reducing the tonal noise annoyance caused by fans is to change the circumferential blade spacing from even to uneven. However, this technique requires predictive tools to simulate and assess their acoustic performance at a lower cost compared to experimental tests, which remain very costly. In this study, a hybrid analytic/numeric (HAN) approach for predicting the tonal noise of fans is proposed. It is based on the acoustic interference law, which is applied to the sound pressure generated by each blade, and Computational Aeroacoustics (CAA). This model allows for the analytical construction of a fan’s acoustic pressure spectrum from the numerically computed response of a single blade, significantly reducing computation time. An optimization procedure is then implemented to minimize the prominence of tonal noise peaks, where the decision variables are the blades’ angular positions and the constraints are rotor balance and the minimum angular distance between adjacent blades. The results show that the developed method may help designers reduce tonal noise annoyance by optimizing blade spacing. Full article

This study numerically investigates heat transfer and thermodynamic behavior in twisted square and rectangular air ducts while keeping a constant hydraulic diameter (D_h = 30 mm). Three aspect ratios are considered (AR = 1.00, 0.75, and 0.50). The heated test section (900 mm) is divided into three equal segments, and three pitch patterns are examined: a uniform pitch (400–400–400 mm, P444) and two axial gradients (300–400–500 mm, P345; 500–400–300 mm, P543). All results are compared to a standard reference, the straight square duct (SD-AR1.00), to ensure fair comparisons across all cases with Reynolds numbers between 5000 and 20,000. Among the twisted ducts, the strongest rectangularity combined with the increasing pitch sequence, TSD-AR0.50-P345, provides the best overall balance. Its heat transfer rises from Nu = 39.39 to 88.62, giving Nu/Nu₀ = 1.493 → 1.433, while the pressure penalty increases to f/f₀ = 1.345 → 1.405. Under cube-root weighting of friction, this case maintains the highest thermal performance factor, TPF = 1.352 at Re = 5000 and TPF = 1.279 at Re = 20,000. Second-law trends support the same ranking: exergy destruction decreases from 12.81 W (baseline) to 8.44 W at Re = 5000 (≈34% reduction) and from 6.54 W to 4.84 W at Re = 20,000 (≈26% reduction). The Bejan number remains high at low Reynolds numbers (≈0.998), indicating heat-transfer irreversibility dominance, but drops at higher Reynolds numbers (≈0.87) as frictional effects become more important. In general, the results show that adding a small axial pitch increase to rectangularity can improve near-wall mixing while reducing losses downstream. This leads to a clear improvement in both first-law performance and exergy-based measures. Full article

This study investigates the genetic diversity, population structure, and adaptive differentiation of Yunnan native cattle (YNC) using whole-genome SNP data from 457 individuals, representing eight cattle populations and two closely related bovine species (Zhongdian yak and Dulong gayal). Genetic diversity analyses revealed a distinct latitudinal gradient from north to south, with the highest diversity observed in the northern Diqing (DQC) and Zhaotong (ZTC) populations. The observed population structure was largely consistent with geographic distribution, identifying distinct ancestral components and complex admixture patterns. Genome-wide selective sweep scans revealed several key candidate genes underlying local adaptation. Notably, GRIA4 and DUOXA2 were associated with cold tolerance in northern populations, and ST3GAL3 and MST1 were implicated in heat stress adaptation in southern populations. Genome-wide balancing selection analyses further detected significant loci, such as MGST1 and SLC36A1, where divergent haplotype frequencies reflected differential selective pressures on milk-related traits between northern and southern populations. Additionally, we detected signals of historical introgression from Zhongdian yak into DQC cattle, highlighting the introgressed gene SLIT3 as a potential candidate associated with high-altitude thermogenesis. Collectively, these results provide a comprehensive genomic framework for the management and conservation of indigenous bovine genetic resources in Southwest China. Full article

Background/Objectives: Although prescribing physical activity (PA) is a well-established preventive strategy in primary health care (PHC), its ethical implications remain under-researched. This study examines how general practitioners (GPs) and nurses experience, interpret, and manage ethical tensions in PAP. Methods: A qualitative study was conducted with 28 PHC professionals (13 GPs, 15 nurses) from rural and urban centers in Toledo, Spain (M = 18.4 years of experience). Data were collected through semi-structured interviews and analyzed using reflexive thematic analysis. Beauchamp and Childress’ four-principles framework was applied abductively to synthesize ethical conflicts and coping strategies. Results: Two main themes emerged: (1) Ethical conflicts in PAP, characterized by tensions between autonomy and paternalism, and the challenge of balancing beneficence with non-maleficence under institutional pressures; and (2) Professional coping strategies, where clinicians used relational care, individualized tailoring, and interprofessional collaboration to mitigate moral distress. Results indicated that clinical codes, such as “unrealistic goals” or “institutional pressure,” often overlapped across multiple ethical principles, necessitating a nuanced, multi-dimensional approach to counseling. Conclusions: PAP is not a neutral clinical task but an ethically grounded practice constrained by structural and organizational factors. To move toward safe and equitable health promotion, PAP must be conceptualized as a relational intervention. We propose an Ethical Reflective Tool and a conceptual framework to support clinical reflection, enhance professional accountability, and guide policy-level support for preventive care in PHC. Full article

As an efficient solid–liquid separation device, the hydrocyclone is widely applied in various industrial fields such as coal preparation and oil impurity removal, and its classification performance directly determines the efficiency of industrial separation operations., As the core separation zone of the hydrocyclone, the cone segment, its structure and the number of cone angles directly affect the flow field distribution characteristics and particle classification performance of the hydrocyclone. To reveal the regulation mechanism of the combined cone angles on the classification performance of hydrocyclones, numerical analysis and experimental verification methods were adopted to investigate the internal flow field and classification performance of hydrocyclones under different cone angle combinations. The evolution laws of velocity field, pressure field, turbulence characteristics, and particle classification effect under different configurations were systematically explored. The results show that the basic characteristics of the core flow field of the hydrocyclone do not change essentially with the increase in the number of cone segments, but the amplitude, distribution, and stability of flow field parameters are significantly regulated. The three-cone configuration achieves the optimal flow field synergy effect: the amplitude of the high turbulence intensity zone is lower and concentrated near the central axis; the zero-velocity envelope surface is stably maintained at approximately 8 mm in the core separation zone; and the full axial fluctuation of the air core is gentle, which effectively inhibits random particle diffusion and flow pattern mixing. In terms of separation performance, the three-cone configuration exhibits the highest classification efficiency in the core range of sub-coarse particles (10~30 μm), with the cut size (approximately 17.5 μm) in a reasonable range, the steepness index reaching a peak value (approximately 0.55), and the pressure drop (approximately 1.8 × 10⁵ Pa) and split ratio (2.8%) achieving synergistic optimization, balancing separation accuracy and energy consumption control. The single-cone configuration causes flow field disturbance due to the one-time contraction of the flow channel, while the four-cone configuration falls into the dilemma of “high pressure drop–marginal performance gain”, and neither achieves optimal performance. The regulation law of the number of cone segments revealed in this study provides a scientific basis for the structural optimization and engineering application of multi-cone hydrocyclones, and is of great significance for improving the particle classification efficiency in fields such as wastewater treatment and mineral processing. Full article

Silicon carbide (SiC) ceramics are among the most attractive materials for lightweight armor because they combine low density (3.0–3.2 g/cm³), high hardness, and high thermal and chemical stability; however, their densification remains challenging because of strong covalent bonding and low self-diffusion. This review analyzes the main sintering routes used for armor-grade SiC ceramics, including solid-state sintering, liquid-phase sintering, hot pressing, gas-pressure sintering, hot-isostatic pressing, ultra-high-pressure sintering, two-step sintering, and spark plasma sintering, together with additive systems based on B, C, Al₂O₃, Y₂O₃, MgO, CaO, and rare-earth oxides. Reported data show that solid-state sintering typically requires 2100–2300 °C and yields 90–95% relative density, whereas hot pressing and liquid-phase sintering achieve 96–99% density at lower temperatures, generally with a flexural strength of 350–800 MPa, fracture toughness of 3.5–7.0 MPa·m^1/2, and hardness of 20–30 GPa. Among the reviewed methods, spark plasma sintering provides near-theoretical density (≥99%) together with the most favorable combination of strength (up to 850 MPa) and hardness (up to 35 GPa). Overall, liquid-phase sintering and spark plasma sintering offer the most favorable balance between densification, microstructural control, and armor-relevant mechanical performance. Full article

This paper investigates the interaction between fiscal policy and non-performing loans (NPLs), a nexus often overlooked in banking stability literature. By proposing a generalized theoretical framework that augments the industrial organization (IO) theory of banking with liquidity preference theory, this study explains why a fiscal contraction (an improvement in the primary balance from deficit toward surplus) can decrease NPLs in a bank’s portfolio. Using bank-level quarterly data from Guyana (2009: Q4 to 2024: Q4) and a Panel Autoregressive Distributed Lag Pooled Mean Group (ARDL-PMG) model, we find that a fiscal contraction reduces NPLs in the long run. Specifically, a one-percentage-point improvement in the seasonally adjusted primary balance (as a % of GDP) is associated with a 0.473 percentage point decrease in NPLs in the long run. This finding contrasts with the existing literature, which often suggests that fiscal consolidations increase credit risk. In the short run, however, the results indicate a divergent effect where fiscal contractions lead to a temporary increase in NPLs, with a coefficient of 0.103, likely because of immediate pressure on borrower debt-service capacity. This study contributes to the literature by extending the IO theory of banking to the fiscal policy–NPL relationship in a developing, resource-rich economy. Notably, while higher oil prices and bank efficiency significantly lower NPLs, traditional macroeconomic drivers such as GDP growth, inflation, and the real effective exchange rate—as well as the COVID-19 pandemic—are found to be statistically insignificant in this framework. Full article

DOC coupled with SCR represents a key technological approach for reducing gaseous pollutant emissions from diesel engines. Based on engine bench testing using a light-duty diesel engine as a prototype, this study investigates the impact of DOC coupled with SCR at different catalyst loadings on diesel engine emission characteristics. Results indicate that higher DOC loadings lead to greater exhaust backpressure losses, with a maximum pressure difference reaching 4.3 kPa. The temperature difference across the DOC was minimally affected by catalyst loading. Higher DOC loading enhanced catalytic activity toward CO and THC. At medium-to-low loads, this effect was pronounced, while at high loads, the influence of catalyst loading diminished. Higher DOC loading enhances NO oxidation capacity. Under external characteristic conditions, elevated engine exhaust temperatures maximize post-DOC NO₂ formation, increasing post-DOC NO₂ production by over 100%. These findings provide useful guidance for optimizing diesel aftertreatment systems to achieve a better balance between pollutant reduction, energy consumption, and environmental sustainability, thereby supporting the sustainable development of cleaner diesel engine technologies. Full article

To investigate how the content of silica fume (SF) influences the performance of foam concrete (FC) after high-temperature exposure and the underlying mechanisms, this study prepared standard FC cube specimens with SF contents of 0%, 0.15%, 0.2%, 0.25%, and 0.3%. The working properties of the material at room temperature were systematically tested, and the mass loss, residual compressive strength, failure mode, microstructure and acoustic emission (AE) data at different temperatures (100 °C, 200 °C, 300 °C and 400 °C) were analyzed. The test results indicate that increasing the SF content reduces the fluidity of the fresh paste yet significantly enhances the compressive strength and lowers the water absorption of FC at room temperature. After high-temperature exposure, the effect of SF exhibits a dual character: at 200 °C and below, SF effectively mitigates the performance degradation of FC. However, when the temperature reaches 300–400 °C, specimens with an excessively high SF content (e.g., 0.3%) experience rapidly built-up internal steam pressure that cannot escape in time, which triggers the formation and propagation of a microcrack network and leads to a sharp drop in strength. Based on AE detection and scanning electron microscopy (SEM) image analysis, the failure process of silica fume foam concrete (SFFC) proceeds through three stages: free water evaporation at low temperatures, dehydration shrinkage of the C-S-H gel at medium temperatures, and finally, structural failure marked by the collapse of the C-S-H gel network at high temperatures. This study indicates that an SF content of 0.25% allows FC to achieve an optimal balance between mechanical properties and high-temperature stability. The findings provide a theoretical basis for optimizing FC mix proportions and enhancing fire prevention design. Full article