Search Results (4,081)

Range limits are often hypothesized to arise from reduced reproductive success at distributional margins, yet direct tests integrating pollination and post-pollination processes remain uncommon. Whether reproductive failure constrains the distylous Gelsemium sempervirens at its western range edge in eastern Texas was investigated by quantifying flowering phenology, floral visitation, pollinator effectiveness, and seed fate over two flowering seasons. Flowering timing differed markedly between years due to freeze events, but flowering effort and morph synchrony remained high. Although multiple floral visitors were recorded, fruit set was overwhelmingly associated with the southeastern blueberry bee (Habropoda laboriosa), which dominated visitation and remained active throughout the flowering period. No evidence of autonomous self-pollination or breakdown of functional distyly was detected. Seed set in unattacked fruits was high and comparable to values reported from central-range populations. In contrast, post-pollination seed loss due to cryptic fruit herbivory substantially reduced seed survival, though herbivory patterns did not differ qualitatively from those documented elsewhere in the species’ range. Together, these results indicate that reproductive failure does not explain the abrupt western range limit of G. sempervirens and instead suggest that ecological transitions associated with the forest–prairie ecotone, rather than pollination or early seed development, may play a more important role in shaping the species’ distribution. Full article

In cold-region engineering, freeze–thaw (F–T) cycles act as a critical stressor on soil stability, where the recurring transition between frost heave and thaw settlement can drastically alter geotechnical properties and threaten long-term structural integrity. Yet, while the static characteristics of frozen soils are well documented, the dynamic impact of repetitive thermal cycling on long-term soil behavior remains a significant and relatively underexplored challenge in the field. This study investigates the effectiveness of polypropylene fiber (FPP) as a sustainable and environmentally benign reinforcement for high-plasticity clay. The research examines FPP’s influence on stress–axial strain relationships (unconsolidated undrained (UU) compressive strength) and its ability to mitigate frost heave and volumetric changes during F–T cycles. Laboratory-prepared FPP–clay samples were subjected to ten closed-system F–T cycles and tested using a UU triaxial machine. Results showed a 51% decrease in UU strength for unreinforced samples after ten cycles, while samples reinforced with 1% FPP exhibited only an 18.4% reduction. FPP reinforcement reduced frost heave and thaw settlement by 30% and significantly enhanced UU strength, increasing it by 60% before F–T cycles and 167% after exposure. The findings highlight FPP’s effectiveness in improving soil strength, minimizing volumetric changes, and mitigating frost-related damage, making it a viable solution for enhancing soil performance in cold regions. Full article

Tunnel lining models were cast at a 1:20 scale using four different materials: plain concrete (PC), steel fiber-reinforced concrete (SFRC), reinforced concrete (RC), and rebar-reinforced steel fiber-reinforced concrete (R/SFRC). Loading tests were performed on these models before and after freeze–thaw cycles to investigate the failure modes, analyze the mechanical behavior, and determine the optimal reinforcement scheme in this study. The results indicated that freeze–thaw cycling reduced the load-bearing capacity of tunnel linings by 12% to 28% compared to non-freeze–thaw linings. Adding steel fibers significantly enhanced the ductility of the lining models. The mechanical performance of linings with an optimal steel fiber content surpassed that of models with either increased rebar alone or steel fibers alone. In this study, an optimal combination of a 0.36% rebar ratio and a 1.5% steel fiber volume fraction effectively improved the tensile performance of the lining while reducing rebar consumption, without compromising the inherent mechanical performance of the tunnel structure. Full article

This study presents the development and experimental evaluation of an impregnation composition for cement concrete pavements aimed at improving ice-phobic performance while preserving tire–pavement adhesion characteristics. The formulation is based on a combination of keratin-containing raw materials and water-soluble polymer components. Optimization showed that a polymer concentration of 2.5% reduces concrete water absorption by 49–53% compared with untreated specimens. Freezing tests conducted at temperatures of 0 to −5 °C demonstrated an additional reduction in water absorption of treated specimens by 33–40% relative to uncoated concrete and improved resistance to ice formation. The influence of the impregnation on tire–pavement interaction was assessed using a direct shear method, revealing minor changes in friction coefficients of up to ~6% for polished and less than 1% for rough surfaces, remaining within acceptable safety limits. Wear resistance was evaluated through rolling tests with model vehicle wheels, where laboratory abrasion occurred after several thousand loading cycles, while probabilistic correction accounting for trajectory variability indicated an extension of service life to the order of tens of thousands of vehicle passes. The results confirm the potential of the keratin–polymer impregnation as an effective approach for enhancing the durability and operational safety of concrete pavements in cold climates. Full article

Precise 3D reconstruction of non-cooperative space targets is a prerequisite for active debris removal and on-orbit servicing. However, this task is impeded by severe environmental challenges. Specifically, the limited dynamic range of visible light cameras leads to frequent overexposure or underexposure under extreme space lighting. Compounded by sparse textures and strong specular reflections, these factors significantly constrain reconstruction accuracy. While existing general-purpose feed-forward models such as MapAnything offer efficient inference, their geometric recovery capabilities degrade sharply when facing significant domain shifts. To address these issues, this paper proposes an enhanced 3D reconstruction framework tailored for the space environment named In-Orbit MapAnything. First, to mitigate data scarcity, we construct a high-quality space target dataset incorporating extreme illumination characteristics, which provides comprehensive auxiliary modalities including accurate camera poses and dense point clouds. Second, we propose the SatMap-Adapter module to mitigate feature degradation caused by severe specular reflections. This architecture employs a hierarchical cascade sampling strategy to align multi-level backbone features and utilizes a lightweight adaptive fusion module to dynamically integrate shallow photometric cues, intermediate structural information, and deep semantic features. Finally, we employ a weight-decomposed low-rank adaptation strategy to achieve parameter-efficient fine-tuning while strictly freezing the pre-trained backbone. Experimental results demonstrate that the proposed method decreases the absolute relative error and Chamfer distance by 15.23% and 20.02% respectively compared to the baseline MapAnything model, while maintaining a rapid inference speed. The proposed approach effectively suppresses reconstruction noise on metallic surfaces and recovers fine geometric structures, validating the effectiveness of our feature-enhanced framework in extreme space environments. Full article

Drying significantly influences the quality of micellar casein (MC) powder. This study investigated the effects of three pre-freezing temperatures (−20 °C, −80 °C, and liquid nitrogen) prior to freeze drying on the structure and rennet-induced gelation properties of MC powder. The results showed that as the pretreatment temperature decreased, the degree of disruption to the secondary and tertiary protein structures was reduced, while the particle size gradually increased. In terms of rennet-induced gel properties, the untreated raw MC consistently outperformed all MC powder samples. Among the MC powders, the sample pre-frozen at −80 °C and then freeze-dried (FD-80) exhibited the highest gel strength and a relatively shorter rennet coagulation time. The observed microstructures of the rennet-induced gel were consistent with the rheological results, showing that samples with smaller particle sizes formed more regular and compact gel networks. In conclusion, the MC powder prepared via pre-freezing at −80 °C and then freeze-drying better preserved protein structure and demonstrated superior rennet-induced gel properties, which were closely related to particle size. This study provides theoretical insights for the application of MC powder in products such as cheese, processed cheese, and protein-fortified foods. Full article

Repetitive temperature fluctuations during transportation and storage promote ice crystal formation in salmon flesh, leading to protein denaturation, lipid oxidation, and quality loss. Tuna skin, a major by-product of tuna processing, is a potential source of antifreeze peptides (AFPs) but remains underutilized. This study examined the cryoprotective effects of tuna skin-derived AFPs on salmon cubes subjected to repeated freeze–thaw cycles. Cubes treated with AFPs from three groups of protein hydrolysates prepared using trypsin, pepsin, or neutral protease were evaluated for texture, color, water holding capacity (WHC), volatile odor profiles, protein conformation, biochemical indices, and microstructure. AFP treatment improved textural properties, maintained color stability, and reduced thawing, cooking, and centrifugal losses. The neutral protease-treated group exhibited the optimal cryoprotective ability and it also limited aldehyde and sulfide accumulation, preserved the retention rate of α-helix structure at 49% which was higher than 39% in controls, and enhanced Ca²⁺-ATPase activity to 1.75 μmol Pi·mg⁻¹·h⁻¹ with a 45.8% increase compared to controls, and significantly inhibited protein and lipid oxidation. Microstructural analysis showed compact fibers and intact sarcolemma in the neutral protease-treated group samples, contrasting with severe disruption in controls. This study showed that tuna skin AFPs mitigate freeze–thaw damage in salmon cubes by stabilizing proteins and reducing oxidative deterioration, highlighting their potential as natural, healthy cryoprotectants for seafood preservation, meeting the growing demand of the food industry for clean-label, low-calorie preservation solutions, while advancing the circular economy of aquatic processing via the valorization of tuna skin by-products for high-value seafood applications. Full article

To address the engineering problems of high cement content, high brittleness, and weak frost resistance of cement-improved loess in the seasonal frozen soil area of Northwest China, F1 ion curing agent (F1) and cement composite improved loess (FCIL) were used in this paper. Through unconfined compressive (UC) strength tests, consolidated undrained (CU) triaxial shear tests, and microscopic pore characteristics analysis, the mechanical properties, freeze–thaw cycle deterioration law, and microscopic pore structure of FCIL were studied. The effects of cement content (C_c), F1 dosage (C_F), number of freeze–thaw cycles (N_F-T), and confining pressure (σ₃) on the strength, deformation behavior, and pore characteristics of FCIL were analyzed. The synergistic improvement mechanism of FCIL, as well as the freeze–thaw damage mechanism, was elucidated. The results show that C_c is the primary factor controlling the strength of improved loess. The incorporation of F1 can further increase UCS and markedly enhance the failure strain (ε_f), thereby achieving simultaneous improvements in strength and ductility. An appropriate mix proportion was identified as C_F = 0.2 L/m³ and C_c = 6%. After 7 d curing, FCIL exhibited a UCS of 1.35 MPa, a cohesion (c) of 205 kPa, an internal friction angle (φ) of 36.2°, and ε_f 1.8 times that of loess improved with C_c = 6% cement alone. CU triaxial shear tests indicate that, under all tested conditions, the stress–strain responses of FCIL exhibit σ3-sensitive strain-softening behavior. As C_c and σ₃ increase, triaxial peak strength (q_max) and secant modulus (E₅₀) increase significantly. Compared with natural loess (NL), FCIL shows a markedly lower porosity (n), a substantial increase in the proportion of micropores, and reductions in medium and small pores. After multiple freeze–thaw cycles, the evolution of the pore structure is effectively restrained. This indicates that the combined use of F1 and cement promotes the formation of a dense layered stacking structure, significantly improves the microscopic pore-size distribution, and enhances the mechanical performance of loess under freeze–thaw environments. Full article

Climate change (CC) is widely recognized as a major human concern, affecting society across all aspects and activities. Among various economic sectors, aviation is one of the most affected due to its exposure to adverse weather events. Consequently, adaptation and mitigation actions are becoming increasingly important to reduce the negative effects of CC-driven extreme weather events on aviation operations. In this study, we analyzed 30 years of historical aerodrome meteorological routine reports (METARs) from several major Italian airports to assess multi-decadal changes in aviation weather-related hazards, based on observational evidence such as convection, visibility, and snow and freezing precipitation. Furthermore, we examined the ERA5 reanalysis dataset to assess potential anomalies in the synoptic circulation over the Euro-Mediterranean region that may drive fluctuations in local airport climatology. Our results reveal relevant trends for the considered aviation-related weather hazards, while also indicating meaningful links to variations in local and synoptic patterns. The observed increases in 500 hPa geopotential height, 850 hPa temperature, and convective available potential energy (CAPE) lead to changes in the climatology of the airports considered, including a general enhancement of thermoconvective phenomena, a reduction in events associated with synoptic-scale disturbances, an overall decrease in snowfall, and contrasting trends in fog occurrence depending on local factors. Full article

This study investigates an eco-friendly rapid-setting concrete developed for emergency repair and accelerated post-disaster reconstruction. The proposed material concept combines a low-emission multicomponent cement, CEM V/A (S-V) 42.5 N-LH/HSR/NA, with a hybrid aggregate skeleton composed of crushed granite and waste soda–lime glass, as well as a waste-derived silicate additive system based on aqueous sodium silicate, glass dust and glass powder. One reference mixture (R) and five modified mixtures (M1–M5) were designed to assess the effects of partial replacement of natural aggregate by glass aggregate and of the dosage of the silicate-based additive system on concrete performance. The experimental programme included setting time, compressive strength, splitting tensile strength, water absorption, freeze–thaw resistance and microstructural observations. Among the modified concretes, the mixture containing 5 vol.% glass aggregate (M1) showed the most favourable mechanical performance after 28 days, reaching a compressive strength of 95.1 ± 2.4 MPa and a splitting tensile strength of 4.82 ± 0.29 MPa, compared with 45.5 ± 0.8 MPa and 2.18 ± 0.11 MPa, respectively, for the reference concrete. Higher glass contents reduced strength relative to M1, but the modified mixtures still maintained satisfactory performance. The silicate-based system significantly affected setting behaviour; in mixture M5, the initial and final setting times were reduced from 380 ± 5 min and 497 ± 5 min to 213 ± 5 min and 307 ± 5 min, respectively. The results show that the combined use of CEM V cement, waste glass and silicate-based waste-derived additives can produce concretes with rapid-setting, high strength and satisfactory durability-related properties. The developed material may therefore be considered a promising solution for selected rapid-repair and reconstruction applications, particularly in lightly reinforced or unreinforced concrete elements requiring fast restoration of functionality. Full article

Background/Objectives: The aztreonam/avibactam combination represents a promising therapeutic option for severe infections caused by multidrug-resistant Gram-negative pathogens, particularly in critically ill patients. Due to marked pharmacokinetic variability and the need to achieve joint pharmacokinetic/pharmacodynamic (PK/PD) targets of both agents, therapeutic drug monitoring (TDM) may play a pivotal role in optimizing treatment. This study aimed to develop and validate two rapid, accurate, and sensitive UHPLC–qTOF MS/MS sequential methods for quantifying aztreonam and avibactam in human plasma, suitable for routine clinical TDM. Methods: Plasma concentrations were determined by means of ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC–qTOF MS/MS), operating in positive and negative electrospray ionization modes for aztreonam and avibactam, respectively. Sample preparation consisted of protein precipitation with isotopically labeled internal standards. The method’s validation was performed according to the European Medicines Agency guidelines, by assessing selectivity, linearity, precision, accuracy, recovery, matrix effects, carry-over, and stability. Clinical applicability was evaluated by reprocessing plasma samples, which were already previously collected for routine clinical practice from 20 hospitalized patients undergoing treatment with ceftazidime-avibactam plus aztreonam. Results: The methods showed excellent linearity (R² ≥ 0.999) over ranges of 0.2–100 µg/mL for aztreonam and 0.1–50 µg/mL for avibactam. Lower limits of quantification were 0.2 µg/mL and 0.1 µg/mL, respectively. Intra- and inter-day precision and accuracy met the EMA criteria at all of the quality control levels. Extraction recovery exceeded 90% for both analytes, and matrix effects were effectively compensated by internal standards. Stability testing highlighted the need for careful sample handling, particularly for aztreonam under repeated freeze–thaw conditions. Clinical application revealed substantial inter-individual variability in steady-state concentrations. Conclusions: The validated UHPLC–qTOF MS/MS assays provide robust and sensitive sequential quantification of aztreonam and avibactam in human plasma, supporting TDM-guided dose optimization in clinical practice. Full article

To reduce the production cost of ultra-high performance concrete (UHPC), this study incorporated polyacrylonitrile (PAN) fibers and coarse aggregates (CA) to develop a novel UHPC with both excellent performance and reduced cost. A two-stage mortar-concrete design approach was employed to optimize the UHPC mix proportion. First, the mortar matrix was preliminarily optimized based on particle packing theory, and its strength development mechanism was analyzed. Subsequently, response surface methodology was applied to systematically investigate the effects of PAN fiber content, CA content, and superplasticizer (SP) dosage on the slump flow, compressive strength, flexural strength, indirect tensile strength, freeze–thaw resistance, and dynamic mechanical properties of UHPC. The entropy weight method was then adopted to determine the optimal mix proportion, followed by cost estimation. The results indicate that the optimal mortar matrix composition consists of 61.4% cement, 15% silica fume, and 23.6% fly ash, achieving a flow spread of 246 mm, a compressive strength of 117.2 MPa, and a flexural strength of 24.9 MPa. When the PAN fiber content, CA content, and SP dosage were 0.5%, 20%, and 3.8%, respectively, the prepared PAN-CA UHPC(PCUHPC) exhibited the best overall performance. Compared with conventional UHPC, the material cost was reduced by 81.7%, and the compressive strength-normalized cost decreased by 75.4%. The UHPC developed in this study, characterized by outstanding performance and significant cost advantages, provides a feasible solution and theoretical support for broader engineering applications. Full article

Fiber-reinforced aerogel composites are attractive for thermal protection applications because porous polymer networks can suppress heat transfer while maintaining structural stability. In this study, carbon fiber felt was integrated with a polyimide aerogel via a freeze-drying-assisted multicycle impregnation process to achieve controlled formation of interconnected aerogel networks within the fibrous scaffold. With increasing impregnation cycles, the composites exhibited progressive microstructural densification and improved structural stability. Although bulk density increased, thermal protection performance under prolonged butane-torch exposure was significantly enhanced, showing delayed backside temperature rise and improved resistance to structural degradation compared with bare carbon felt. Post-ablation analyses revealed the formation of a micro-/nanoporous polymer-derived char layer and a multilayer thermal-resistance structure, which contributed to suppressed heat transfer during flame exposure. These results indicate that effective thermal protection in CF/PA composites is governed by dynamic microstructural evolution and char-layer formation rather than intrinsic room-temperature thermal conductivity alone. The proposed multicycle impregnation strategy provides a scalable approach for designing lightweight polymer-based thermal protection materials operating in high-temperature environments. Full article

The Mediterranean Diet (MD) is recognized for its nutritional quality, health-promoting properties, and richness in bioactive compounds, yet studies analyzing complete traditional recipes considering both extractable and non-extractable fractions are limited. This study characterized the total antioxidant capacity (TAC) and phenolic profile of 56 traditional MD recipes from eight countries, grouped into European Mediterranean (France, Italy, and Spain), African Mediterranean (Tunisia, Algeria, and Morocco), and non-Mediterranean European (Luxembourg and Germany) regions. Samples were freeze-dried and subjected to aqueous-organic extraction followed by acid hydrolysis. TAC was measured using TEAC, ORAC, and total phenolics (Folin–Ciocalteu, reflecting reducing capacity), while phenolic profiles were analyzed by HPLC-DAD. Relationships between phenolics and TAC were evaluated using linear and mixed-effects models, accounting for country-level heterogeneity. Mediterranean recipes showed higher TAC and greater phenolic diversity than non-Mediterranean recipes, with a predominance of phenolic acids, secoiridoids, and flavonoids, reflecting characteristic olive oil use. In all regions, the non-extractable fraction contributed >80% to TAC, highlighting underestimation by conventional methods and its dominant contribution to dietary antioxidant intake. TEAC was positively associated with extractable phenolics, whereas ORAC reflected country-specific culinary features independently of total phenolic content. These findings underscore the significant bioactive potential of traditional MD recipes, which can be considered functional foods, and the importance of comprehensive evaluations of both extractable and non-extractable fractions for nutritional research and dietary interventions. Full article

This study investigated the characteristics and bioactive properties of olive oils obtained from regional Nizip Yaglik (NY) and Kilis Yaglik (KY) olive varieties, encapsulated using maltodextrin (MD) and whey protein isolate (WPI) as wall materials. Olive oils were first emulsified with different WPI–MD ratios (1:1, 1:4, 1:10) and subsequently freeze-dried to produce microcapsule powders. A comprehensive evaluation was conducted, including physicochemical properties (encapsulation efficiency, moisture content, water activity, bulk density, flowability, wettability, particle size, and color), FTIR spectral profiles, morphological features, total phenolic content, and antioxidant activity. The results demonstrated that combining WPI with MD yielded high encapsulation efficiency and favorable reconstitution characteristics, effectively protecting sensitive bioactive constituents from oxidative degradation during processing and storage. Increasing the proportion of MD in the wall matrix improved emulsion stability and microencapsulation yield, while also slightly enhancing powder brightness. FTIR analyses confirmed that the fundamental chemical structure of olive oil was preserved across all formulations. The freeze-dried microcapsules displayed superior stability relative to non-encapsulated oils, retaining higher levels of phenolic compounds and antioxidant capacity. Among the formulations, elevated MD ratios enhanced powder flowability, whereas WPI played a crucial role in emulsification performance and capsule surface integrity. Overall, these findings underscore the effectiveness of MD–WPI blends as promising wall materials for the freeze-drying encapsulation of regional olive oils, offering a viable strategy to preserve their distinctive qualities and bioactive potential for functional food applications. Full article