Search Results (738)

The growing demand for sustainable and high-performance lubricants has accelerated interest in biolubricants derived from renewable feedstocks. Vegetable oils are attractive candidates due to their biodegradability, low toxicity, and favorable viscosity index. However, their application is limited by poor oxidative and thermal stability. The epoxidation of unsaturated fatty acids offers a versatile route to address these drawbacks by enhancing stability and introducing reactive epoxy groups for further functionalization. This review highlights the advances in the use of epoxidized vegetable oils (EVOs), as platforms for lubricant design. Post-epoxidation modifications, such as ring-opening reactions, crosslinking, hybridization with additives, and click-type chemistries, are critically examined with emphasis on their impact on viscosity, polarity, tribofilm formation, and overall tribological behaviour. Structure–property relationships were discussed to establish design principles linking chemical modifications with lubrication regimes, wear resistance, and film-forming ability. In addition, sustainability aspects, including biodegradability, ecotoxicity, and life cycle assessment, are reviewed to evaluate the trade-offs between performance enhancement and environmental compatibility of these modifications. Current challenges and future perspectives are outlined, including the need for standardized testing protocols, the integration of multifunctional modifications, and predictive modelling tools. By bridging molecular engineering, tribological performance, and sustainability, this review provides a roadmap for the rational design of advanced epoxidized oil-based biolubricants. Full article

The goal of the study was to identify the effects of fulvic acid (FULV) and methyl jasmonate (MEJA) in increasing the yield, alkaloid content and drought-resistance of poppy (Papaver somniferum L.). The trials were carried out in both field and controlled conditions; in the latter, with two water supply regimes (50 and 75% soil water capacity). The treatments were applied by exogenous foliar spraying. In the field experiment, we observed a 22.4% increase in yield (capsules with seeds) under of FULV and a 44.2% increase due to MEJA. The treatments could not intensify the concentration of alkaloids. Under controlled conditions, MEJA decreased total biomass but capsule yield was not lower, its proportion even increased. Antioxidant capacity (AC) and total phenolic content (TPC) increased (11 and 22%, respectively) together with proline concentration (by 134%) under dry conditions. In addition, biostimulant sprayings stimulated the AC (by 6.6% MEJA and by 11.5% FULV). FULV was effective also in graising the TPC (by 14.5%) and producing a 417% rise in the concentration of soluble sugars. Our results may contribute to the protection of poppy under drought as well as to a more detailed understanding of its stress responses. Full article

The present work consisted of a comparative analysis, followed by an extensive narrative literature review, of the structural profiles of bioactive polysaccharides from edible fruits representing different terrestrial biomes, relating them—with a focus on their monosaccharide fractions—to the abiotic variables of each biome, such as temperature, rainfall, annual water regimes, and physicochemical characteristics of the soil to provide an accurate landscape regarding the patterns and divergences surrounding the development of edible fruits around the world. The present review also provided a focus on the various analytical methods used to obtain data related to the glycosidic profile of the analyzed edible fruits, allowing for a comparison of issues relating to the biomes and the quantitative composition of the existing polysaccharides, together with the associated macromolecular parameters, such as degree of esterification, branching, and average molecular weight. From the analysis performed, recurrences of characteristics were identified in different biomes, such as high concentrations of galacturonic acid and arabinose in fruits from cold regions; abundance of xyloarabinan and galactan in fruits from arid areas; and greater branching, acetylation, and a lower degree of esterification in fruits subject to water variations that favor water retention and cell wall stability. These profiles suggest a strong association between the structure of polysaccharides and ecological adaptations that are crucial for their full development. The insights presented here are of the utmost importance in both basic and applied food science, indicating possible structural targets for selecting and engineering resistance in edible fruits under various abiotic stress conditions and guiding and providing direction for experimental studies that extend beyond classical methodologies. Full article

Co-TiO₂ materials have rich magnetic and electronic properties for advanced magnetoresistance (MR) sensing field. The non-uniform Co-TiO₂ nanocomposite films are prepared via magnetron sputtering. With substrate temperature increasing, the particles undergo agglomeration, and this non-uniform structure transits from the superparamagnetic-particle Co distribution to the particle-cluster Co distribution. Consequently, the MR decreases from 6% to 1%, owing to low resistivity. To investigate the electronic transport mechanism, the microstructural analysis and temperature-dependent fitting calculations of conduction and MR were investigated. In this study, non-uniform nanocomposite films with a broad particle size distribution were fabricated. With testing temperature decreasing, electron transport changes from higher order hopping to higher order cotunneling processes. The non-uniform films deposited at room temperature exhibited a negative MR up to 30% at 2 K, which was attributed to higher order cotunneling in the Coulomb blockade regime and explained by establishing a non-uniform multi-channel conduction model. Full article

The low hardness of copper alloys, which are the substrate material used for continuous casting molds, makes them prone to plastic deformation, wear, and high-temperature oxidation, leading to premature failure and the formation of surface defects on billets. In this work, the microstructure, phase composition, mechanical, and tribological properties of Cr₃C₂–NiCr coatings deposited by high-velocity oxy-fuel (HVOF) spraying onto copper substrates used in molds were investigated. This research was driven by the need to extend the service life of copper molds in continuous steel casting processes. It was established that spraying parameters have a decisive influence on porosity, coating thickness, microhardness, and friction behavior under conditions simulating billet contact with the working surface of the mold. Among the investigated regimes, the coating deposited at a powder feed rate of 11.39 m/s exhibited a dense lamellar structure and the highest level of microhardness. Tribological tests confirmed that this coating exhibited the lowest coefficient of friction, whereas the other coatings were characterized by higher porosity and poorer wear resistance. Thus, the results emphasize the necessity of optimizing spraying parameters to develop highly effective HVOF protective coatings for copper molds operating under extreme thermomechanical loads during steel casting. Full article

This study investigated the electrolytic-plasma hardening (EPH) of cast 20GL steel, used for railway spring beams. The main objective was to analyze the spectral characteristics of the cathodic discharge and establish correlations between the plasma parameters, processing regimes, and resulting surface properties. Optical emission spectroscopy revealed that the plasma at 260 V exhibited a high-energy state with an electron density of ~5.3 × 10¹⁶ cm⁻³ and an electron temperature of 10,031 K. Using these parameters, the heat flux from the plasma to the steel surface was estimated at ~1.5 × 10⁷ W/m², confirming that the discharge provides sufficient energy for surface austenitization. Microstructural analysis demonstrated that the electrolyte flow rate, which determines the cooling rate, is the key parameter controlling phase transformations. At low flow rates, ferrite–pearlite and bainitic structures formed, while a fully martensitic structure and maximum hardness (1046 HV) were achieved at 10 L/min. Tribological tests confirmed the superior wear resistance of the martensitic layers, showing a friction coefficient of 0.454 and a wear volume 3.4 times lower than in the as-cast state. These findings verify that EPH offers an energy-efficient, low-cost method for improving the surface performance and service life of 20GL steel components in heavy-duty railway applications. Full article

High-strength concrete (HSC) is widely used in coastal regions, but its durability and structural safety is threatened by chloride ingress in marine environments. This study investigates the effects of different curing methods, normal, steam, and high-temperature autoclave on the chloride resistance of HSC using the electric flux test. A critical chloride concentration of 4.5% was identified, and accelerated deterioration tests were conducted to evaluate mechanical properties development (compressive strength, elastic modulus, toughness, specific toughness) under the various curing conditions. Additionally, the development of hydration products and microstructural characteristics were analyzed to elucidate the mechanisms underlying the observed differences. The results indicate that steam and autoclave curing enhance cement hydration and the initial mechanical properties of HSC but also increase permeability and susceptibility to chloride ion penetration compared to normal curing. Chloride penetration was found to be most severe at moderate chloride concentrations (~4.5%), while higher concentrations resulted in reduced ion migration. Although intensive curing under elevated temperature and pressure improves early strength and stiffness, it accelerates mechanical degradation under chloride exposure, highlighting a trade-off between short-term performance and long-term durability. Full article

The risk of explosive spalling in high-strength cement-based materials during fire exposure poses a significant threat to structural integrity. To help mitigate this issue, this study explores the use of expanded polystyrene (EPS) beads as both a lightweight filler and a potential spalling-reduction agent in lightweight geopolymer and conventional cementitious mortars. Two EPS-containing mortars were developed: a lightweight alkali-activated slag (LWAS) mortar and a conventional lightweight Portland cement (LWPC) mortar, both incorporating EPS beads as a 50% volumetric replacement for sand. Specimens from both mortars were subjected to elevated temperatures of 200 °C, 400 °C, and 600 °C at a heating rate of 10 °C/min to simulate a rapid-fire scenario. Following thermal exposure, two cooling regimes were employed: gradual cooling within the furnace and rapid cooling by water immersion. Mechanical performance was evaluated through compressive, splitting tensile, and impact tests at room and elevated temperatures. Microstructural analysis was also conducted to examine internal changes and heat-induced damage. The results indicated that LWAS showed remarkable resistance to spalling, remaining intact up to 600 °C due to its nanoporous geopolymer structure, which allowed controlled steam release, while LWPC failed explosively at 550 °C despite EPS pores. At 400 °C, EPS beads enhanced thermal insulation in LWAS, lowering internal temperature by over 100 °C, but increased porosity led to faster strength loss. Both mortars gained strength at 200 °C from continued curing, yet LWAS retained strength better at high temperatures than LWPC. Microscopy revealed that EPS created beneficial fine cracks in the slag matrix but harmful voids in cement. Overall, LWAS composites offer excellent spalling resistance for fire-prone environments, though reinforcement is recommended to mitigate strength loss. Full article

Heavy-textured soils in monsoon-affected regions face challenges related to waterlogging and structural degradation, yet the long-term efficacy of biochar as a physical soil amendment under such conditions remains inadequately understood. This two-year field study (2018–2019) therefore evaluated the transient impacts of birch-derived biochar (360–380 °C pyrolysis; 0, 1, 3 kg/m²), subsurface drainage systems, and fertilizer regimes on key physical properties of Endoargic Anthrosols (clay loam) in coastal Primorsky Krai, Russia. Granulometric composition remained stable (silt loam: sand 42–48%, silt 38–44%, clay 12–16%), though drainage significantly increased the silt fraction by >7.5% (p < 0.05). Biochar induced short-term reductions in bulk density (ρ_b; max −12% at 3 kg/m², 2018) and aggregate density (ρ_a; max −9.3%, 2018), but these effects dissipated by 2019 due to tillage redistribution and monsoonal fragmentation, as verified by SEM. Total porosity fluctuated seasonally (0.50–0.65 cm³/cm³), peaking post-tillage but declining under monsoon saturation, with no significant sustained biochar contribution. Crucially, intra-aggregate pore architecture (2–50 nm) resisted amendment-induced changes; N₂ adsorption showed treatment-invariant mesopore dominance (65–75% volume; mean pore diameter 17–21 nm), attributable to biochar’s physical exclusion (>1 µm particles from sub-0.5 µm pores) and inert fragmentation. Drainage dominated structural dynamics, modulating pore volume seasonally (−15% in 2018; +18% in 2019), while organic fertilizer enhanced porosity through polysaccharide-stabilized microaggregation (+22%, 2019). We conclude that biochar’s physical benefits in clay loams under monsoon climates are transient and dose-dependent, operating primarily through inter-aggregate macroporosity rather than intra-aggregate modification, necessitating reapplication for sustained improvements. Full article

This article explores the evolving roles of Sunnī and Shīʿī political actors in the current Gaza crisis, with a focus on how Iran has come to occupy the rhetorical and symbolic space once dominated by Sunnī Arab leadership. Historically, since the establishment of Israel in 1948, Sunnī regimes positioned themselves as the primary defenders of the Palestinian cause. However, recent shifts—originating in the late 1970s and evolving into the current wave of normalization agreements between Arab states and Israel—have weakened this leadership role. In this vacuum, Iran has articulated a theological-political narrative grounded in Shīʿī doctrines of resistance, martyrdom, and moral duty toward the oppressed, reframed through Khomeinist ideology to legitimize its regional geopolitical ambitions. Drawing on political theology as a theoretical framework, this article analyzes how sacred history shapes Iran’s foreign policy discourse and legitimizes its regional role. This article argues that the current Gaza crisis illustrates a significant transformation in the religious-political landscape of the Muslim world, as Iran leverages its Shīʿī identity to assert moral and political leadership over a cause once firmly associated with Sunnī solidarity. This study concludes that Shīʿism, led by Iran, has shown unwavering support for the Palestinian cause through its backing of Hamas in its latest conflict, despite Iran’s simultaneous pursuit of wider regional drives and ideological goals. Still, Iran’s foreign policies cannot be separated from the historical incidents that gave rise to the Shīʿī tradition of protest and resistance, which remain integral to how Iran’s Shīʿism positions itself in the present conflict. Full article

Urban ecosystems are structurally and functionally distinct from their natural counterparts, with anthropogenic management potentially altering fundamental ecological processes such as seasonal community dynamics and impairing their sustainability. However, the mechanisms through which management filters plant diversity across seasons remain poorly understood. This study tested the hypothesis that management acts as an abiotic filter, dampening seasonal community variations and increasing biotic homogenization in urban green spaces. In this respect, through an intensive, multi-seasonal case study comparing two Mediterranean urban green spaces under contrasting management regimes, we analysed plant communities across 120 plots over four seasons. Results reveal a contingency cascade under management: while the species composition remains relatively stable (+26% variability, p < 0.001), the demographic success becomes more contingent (+41%, p < 0.001), and the ecological dominance becomes highly stochastic (+90%, p < 0.001). This hierarchy demonstrates that management primarily randomizes which species achieve dominance, in terms of biomass and cover, from a pool of disturbance-tolerant generalists. A 260% increase in alien and cosmopolitan species and persistent niche pre-emption dominance–diversity patterns also indicate biotic homogenization driven by management filters (mowing, trampling, irrigation, and fertilization) that favors species resistant to mechanical stresses and induces a breakdown of deterministic community assembly. These processes create spatially and temporally variable assemblages of functionally similar species, explaining both high structural variability and persistent functional redundancy. Conversely, seasonally structured, niche-based assemblies with clear dominance–diversity progressions are observed in the unmanaged area. Overall, findings demonstrate that an intensive management homogenizes urban plant communities by overriding natural seasonal filters and increasing stochasticity. The study provides a mechanistic basis for sustainable urban green space management, indicating that reduced intervention can help preserve the seasonal dynamics crucial for sustaining biodiversity and ecosystem functioning. Full article

Substantial improvements in the performance of optical interconnects based on multi-mode fibers are required to support emerging single-channel data transmission rates of 200 Gb/s and 400 Gb/s. Future optical components must combine very high modulation bandwidths—supporting signaling at 100 Gbaud and 200 Gbaud—with reduced spectral width to mitigate chromatic-dispersion-induced pulse broadening and increased brightness to further restrict flux-confining area in multi-mode fibers and thereby increase the effective modal bandwidth (EMB). A particularly promising route to improved performance within standard oxide-confined VCSEL technology is the introduction of multiple isolated or optically coupled oxide-confined apertures, which we refer to collectively as multi-aperture (MA) VCSEL arrays. We show that properly designed MA VCSELs exhibit narrow emission spectra, narrow far-field profiles and extended intrinsic modulation bandwidths, enabling longer-reach data transmission over both multi-mode (MMF) and single-mode fibers (SMF). One approach uses optically isolated apertures with lateral dimensions of approximately 2–3 µm arranged with a pitch of 10–12 µm or less. Such devices demonstrate relaxation oscillation frequencies of around 30 GHz in continuous-wave operation and intrinsic modulation bandwidths approaching 50 GHz. Compared with a conventional single-aperture VCSELs of equivalent oxide-confined area, MA designs can reduce the spectral width (root mean square values < 0.15 nm), lower series resistance (≈50 Ω) and limit junction overheating through more efficient multi-spot heat dissipation at the same total current. As each aperture lases in a single transverse mode, these devices exhibit narrow far-field patterns. In combination with well-defined spacing between emitting spots, they permit tailored restricted launch conditions in MMFs, enhancing effective modal bandwidth. In another MA approach, the apertures are optically coupled such that self-injection locking (SIL) leads to lasing in a single supermode. One may regard one of the supermodes as acting as a master mode controlling the other one. Streak-camera studies reveal post-pulse oscillations in the SIL regime at frequencies up to 100 GHz. MA VCSELs enable a favorable combination of wavelength chirp and chromatic dispersion, extending transmission distances over MMFs beyond those expected for zero-chirp sources and supporting transfer bandwidths up to 60 GHz over kilometer-length SMF links. Full article

Xylophagous insects represent a diverse group of species whose life cycles are trophically associated with wood at various stages of decomposition. In forest ecosystems, they play a pivotal role in wood degradation and biogeochemical nutrient cycling. Their remarkable adaptation to feeding on structurally complex and nutrient-poor woody substrates has been largely mediated by long-term symbiotic interactions with gut microbiota. This review synthesizes current knowledge on the molecular and ecological mechanisms underlying insect–microbiota interactions, with particular attention paid to the impact of environmental stressors—including elevated temperature, shifts in moisture regimes, and pollution—on microbial community structure and host adaptive responses. We critically evaluate the strength of evidence linking climate-driven microbiome shifts to functional consequences for the host and the ecosystem. The ecological implications of microbiota restructuring, such as impaired wood decomposition, decreased disease resistance, facilitation of xylophagous species spread, and alterations in key biotic interactions within forest biocenoses, are discussed. Particular emphasis is placed on the integration of multi-omics technologies and functional assays for a deeper, mechanistic understanding of microbiota roles. We also assess the potential and limitations of microbiome-based approaches for insect population management, with the overall goal of maintaining and enhancing the resilience of forest ecosystems under ongoing climate change. Full article

Barley (Hordeum vulgare L.) is a major fodder crop whose productivity is often reduced by phytopathogens, especially during early growth. Understanding how soil fertility management and microbial communities influence disease outcomes is critical for developing sustainable strategies that reduce fungicide dependence and enhance crop resilience. This study evaluated the resistance of the winter barley cultivar “Zemela” to powdery mildew (Blumeria graminis f. sp. hordei), brown rust (Puccinia hordei), and net blotch (Pyrenophora teres f. maculata). The crop was cultivated under two soil management systems—green manure and conventional—and five fertilisation regimes: mineral, vermicompost, combined, biochar, and control. Phytopathological assessment was integrated with functional predictions of soil microbial communities. Field trials showed high resistance to powdery mildew (RI = 95%) and brown rust (RI = 82.5%), and moderate resistance to net blotch (RI = 60%). While ANOVA indicated no significant treatment effects (p > 0.05), PCA explained 82.3% of the variance, revealing clear clustering of microbial community functions by soil management system and highlighting the strong influence of fertilisation practices on disease-related microbial dynamics. FAPROTAX analysis suggested that organic amendments enhanced antifungal functions, whereas conventional systems were dominated by nitrogen cycling. FUNGuild identified higher saprotrophic and mycorrhizal activity under organic and combined treatments, contrasting with greater pathogen abundance in conventional plots. Overall, results demonstrate that soil fertilisation practices, together with microbial functional diversity, play a central role in disease suppression and crop resilience, supporting sustainable barley production with reduced reliance on chemical inputs. Full article

Boxwood (Buxus sp.) plays a key role in historical gardens due to its evergreen foliage and resilience. However, recent outbreaks of disease caused by fungal pathogens such as Calonectria spp. (C. pseudonaviculata, C. henricotiae) and Pseudonectria spp. (P. buxi, P. foliicola), as well as pest pressures from Cydalima perspectalis, have led to significant losses. This study examined 100 boxwood plantings across the Czech Republic to evaluate pest and disease occurrence. Further, six modern boxwood cultivars from the groups of BetterBuxus^® and NewGen^® were tested in field trials under the climatic conditions of the Czech Republic, focusing on their resistance to abiotic stress and foliage color retention throughout the year. Laboratory trials confirmed all cultivars were susceptible to C. pseudonaviculata, with ‘Renaissance’ showing the slowest disease progression. Field assessments under two contrasting management regimes (“Minimalistic” and “Pampered”) indicated sporadic boxwood blight incidence but frequent Volutella blight outbreaks, particularly where plants suffered frost stress. Leaf color, an important esthetic trait, was evaluated using Munsell charts and measuring the relative chlorophyll content. ‘Skylight’ most closely matched Buxus sempervirens in the shade of green and winter color. Full article