Search Results (1,436)

The present study investigates the effect of low-temperature ion plasma nitriding on the phase composition, microstructure, tribological behavior, and corrosion resistance of 30Cr13 martensitic stainless steel. Plasma nitriding was carried out at temperatures of 400, 450, and 480 °C in a dissociated ammonia atmosphere using a pulsed DC glow discharge. The phase composition and structural evolution of the surface layer were analyzed by X-ray diffraction, while the morphology and thickness of the modified zone were examined using scanning electron microscopy. The tribological properties were evaluated under dry sliding conditions using a ball-on-disk configuration, and corrosion resistance was assessed by potentiodynamic polarization in a 3.5 wt.% NaCl solution. It was established that low-temperature ion plasma nitriding leads to the formation of nitrogen supersaturated martensite (α′N) and the nitride phase ε-(Fe_2–3)N, with their relative fraction governed by the treatment temperature. An increase in the nitriding temperature resulted in a rise in the surface’s microhardness up to 1100–1150 HV and a change in the thickness of the modified layer, reflecting nitrogen redistribution between the solid solution and nitride constituents. The predominance of the α′N phase at 400–450 °C ensured the most stable tribological behavior and reduced corrosion rate, whereas an increased fraction of ε-(Fe_2–3)N at 480 °C led to a higher microhardness and a greater abrasive wear component while maintaining satisfactory corrosion resistance. The obtained results confirm the decisive role of phase composition in the nitrided layer in determining the tribological and corrosion performance of 30Cr13 steel, and may be used for optimizing the surface hardening parameters of components operating under combined friction and corrosive environments. Full article

Kyoho grape, a leading table grape variety in China, is prone to rapid postharvest deterioration due to its soft texture and high respiration rate. Despite the use of low-temperature storage and modified atmosphere packaging (MAP), systematic studies defining the optimal combination of subzero temperature and gas composition for Kyoho grapes remain lacking. This study aimed to fill this gap by evaluating the synergistic effects of subzero temperature and MAP on quality preservation. Results demonstrated that storage at −1 °C most effectively maintained fruit firmness, stem freshness, and key biochemical components. Based on this temperature, a gas composition of 3% O₂, 15% CO₂, and 82% N₂ was identified as the most effective, extending postharvest shelf life to 54 days. Additionally, a kinetic shelf-life prediction model based on firmness changes was developed with relative errors below 10%, demonstrating high accuracy. This study establishes an integrated preservation strategy combining subzero temperature (−1 °C) and optimized MAP (3% O₂, 15% CO₂, 82% N₂) that significantly extends the shelf life of Kyoho grapes, providing a practical solution for enhancing postharvest quality. Full article

Fresh bluefin tuna is highly susceptible to quality deterioration during refrigerated storage due to lipid oxidation and microbial activity, creating a need for effective clean-label preservation strategies. This study evaluated the efficacy of natural astaxanthin as an antioxidant treatment to improve the refrigerated stability of fresh bluefin tuna (Thunnus thynnus) fillets stored under vacuum packaging (VP) or modified atmosphere packaging (MAP; 70% N₂/30% CO₂). Tuna fillets were treated by short immersion in astaxanthin solutions (10–20 mg/L), applied alone or in combination with other natural antioxidants, including ascorbic acid, and compared with a rosemary–ascorbic acid reference system. Selected treatments incorporated microencapsulated astaxanthin to enhance antioxidant stability. Quality changes were monitored during refrigerated storage (4 °C) through sensory evaluation (appearance, colour, and odour), total volatile basic nitrogen (TVBN), histamine determination, and microbiological analyses. Astaxanthin-treated samples exhibited improved colour stability, delayed sensory deterioration, and significantly lower TVBN accumulation compared with the rosemary–ascorbic acid reference treatment. Under MAP conditions, astaxanthin reduced TVBN values by approximately 20% after 12 days of storage, while microencapsulated astaxanthin combined with ascorbic acid achieved reductions of up to 30% under vacuum packaging. All selected treatments complied with regulatory microbiological and histamine limits throughout storage. These results indicate that natural astaxanthin, particularly in microencapsulated formulations, can enhance quality stability of fresh bluefin tuna when applied in combination with oxygen-limiting packaging systems under controlled refrigerated conditions. The findings provide a scientific basis for further investigation of astaxanthin-based preservation strategies in high-value seafood products. Full article

Laser processing has been widely investigated as an effective approach for improving surface properties and consolidating advanced materials, particularly complex alloys such as titanium aluminides (TiAl). In this study, laser surface remelting was applied to binary (Ti-45Al) and ternary (Ti-45Al-2Co and Ti-45Al-2Ni) alloys produced by powder metallurgy via blended elemental (BE) and pre-alloyed (PA) powder routes. Laser powers of 50 and 100 W were employed, resulting in a high-energy-density surface remelting regime applied to both green compacts and sintered samples with relatively high initial porosity, under an argon-controlled atmosphere. Microstructural and phase analyses were performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), while mechanical behavior was assessed by instrumented microindentation. Laser processing promoted the formation of a dense and homogeneous surface layer, approximately 150 μm thick, accompanied by significant microstructural refinement and enhanced hardness and elastic modulus. While rapid solidification led to crack formation in laser-treated sintered samples, the green compacts exhibited defect-free modified layers. Overall, the results demonstrate that laser surface remelting is an effective strategy for enhancing the surface integrity and mechanical performance of TiAl alloys processed by powder metallurgy. Full article

Reaction OH + HI → I + H₂O (1) is an important atmospheric process transforming inactive HI into chemically active iodine atoms. In the present work, the reaction kinetics have been studied in a discharge fast-flow reactor coupled with an electron impact ionization mass spectrometer at nearly 2 Torr total pressure of helium and over a wide temperature range, T = 225–950 K. The reaction rate constant was determined both by a relative rate method (with the OH + Br₂ reaction as a reference) and by absolute measurements carried out under pseudo-first order conditions by monitoring the OH consumption kinetics in excess of hydrogen iodide. U-shaped temperature dependence was observed for the reaction rate constant, negative at low temperatures and positive at high temperatures. Recommended expression over the 225–950 K temperature range: k₁ = 1.13 × 10⁻¹¹ exp(354/T) + 6.93 × 10⁻¹¹ exp(−1010/T) cm³ molecule⁻¹ s⁻¹ or in the form of a modified Arrhenius expression, k₁ = 4.2 × 10⁻¹² × (T/298)^1.36 exp(666/T) cm³ molecule⁻¹ s⁻¹, with a total estimated uncertainty of 15% at all temperatures. The rate constant data obtained in this study are compared with the results of previous experimental works. Full article

The influence of different gas compositions in modified atmospheric packaging (MAP) without and with chitooligosaccharide-EGCG (CE) conjugate on storage stability of Asian hard clam (HC) meat during storage at 4 °C was studied. Microbial load of HC meat was <5 log CFU/g when packaged under MAP, regardless of treatment, up to 18 days of storage, whereas control exceeded viable bacterial count (6 log CFU/g) on day 9. The lowest microbial load, volatile bases, and lipid oxidation were obtained in HC meat pretreated with 600 ppm of CE conjugate and MAP (80% CO₂/20% O₂) (MAP4-CE) (p < 0.05). Correlation heatmap analysis showed that a high-CO₂/low-O₂ atmosphere was the primary determinant of reduced Pseudomonas growth and lipid oxidation in HC meat, whereas the CE conjugate conferred only minor oxidation and nitrogenous spoilage indices. HC packed under MAP exhibited higher cooking and drip loss, along with increased toughness and firmness, irrespective of treatment. PUFA of MAP4-CE was retained during 18 days of storage. High-CO₂, with or without CE, redirected the microbial diversity toward CO₂-tolerant taxa. Overall, MAP4-CE had an extended shelf-life of at least 18 days while better preserving lipid quality and delayed growth of spoilage bacteria. Full article

Results of a methodological case study of low-level clouds in the atmosphere using a 1064 nm fiber lidar are presented. The lidar experiment was carried out in Daejeon, Republic of Korea, in January–March 2025. The study’s primary objective was to ascertain the vertical extinction coefficient profiles pertaining to tenuous, low-altitude cloud formations via implementation of a refined Sequential Lidar Signal Processing Algorithm (SLSPA). The SLSPA incorporates statistical estimation theory to assess signal and measurement error. Cloud extinction coefficient profiles are estimated within the SLSPA utilizing the modified Klett–Fernald inversion algorithm. The SLSPA adaptation is required (a) to evaluate the accuracy of Q-switch laser-based lidar sounding signal deconvolution, (b) to mitigate the impact of the lidar form factor on measurement results, (c) to account for aerosol extinction coefficient variability within the cloud in the modified inversion algorithm (MIA), and (d) to evaluate multiple scattering effect correction in the MIA. Theoretical and experimental aspects of the modified SLSPA are considered sequentially in the present work. The experimental results presented here are based on datasets sampled from the entire array of experimental data obtained during the measurement period. Full article

This study evaluated the effect of water vapor generated by fresh-cut mango (Mangifera indica) on the release of β-carotene from β-cyclodextrin complexes (β-C:β-CD) under stored Modified Atmosphere Packaging (MAP) and to demonstrate β-carotene stabilization and passive–active packaging behavior under MAP conditions. Containers with fresh-cut mangoes, with and without MAP (4% O₂, 6% CO₂, 90% N₂), were prepared for monitoring over 6 days at 4 °C. β-C:β-CD complexes were incorporated into the lids of containers. The physicochemical, relative humidity, antioxidant, erythroprotective, microbiological, and biofunctional qualities of freshly cut mangoes during storage were analyzed. Active metabolic respiration of plant tissue led to a progressive decrease in O₂ and an increase in CO₂ in sealed containers, a phenomenon intensified by cutting, high humidity, and the system’s limited gas permeability. Application of MAP effectively modulated this microenvironment, reducing respiration rate, water loss, acidification, and the degradation of bioactive compounds. Compared to treatments without MAP, mangoes stored under modified atmosphere showed greater color stability, a slower rate of change in pH and titratable acidity, less loss of antioxidant activity and phenolic compounds, and significant preservation of erythroprotective capacity. Furthermore, MAP maintained microbial counts within the limits established by current regulations until the sixth day of storage. The encapsulation of β-C in β-CD effectively protected its bioactivity from oxidation, especially under MAP, although its release into the food matrix was limited, suggesting a predominantly passive behavior of the active packaging system. Overall, the results demonstrate that the combination of MAP constitutes a promising strategy for extending the shelf life and biofunctional stability of fresh-cut mangoes and β-C into the complex. Full article

Tropical cyclones kill thousands and inflict vast destruction annually. While ocean temperatures and atmospheric conditions dominate their formation and behaviour, forests’ potential influence has received little systematic attention. This review examines whether and how forests may affect tropical cyclone frequency, intensity, and behaviour. Support varies by mechanism and stage. Post-landfall effects have the strongest support: forests slow storms, moderate wind speeds and curb flooding through enhanced soil infiltration. Forests also influence storm tracks, though magnitudes are uncertain. Pre-landfall effects are less certain. These include processes that modify offshore humidity, temperature, and aerosols. The Biotic Pump theory proposes that forest cover creates pressure gradients drawing moisture inland, reducing its availability for ocean storms. Forest influences are likely to be most evident near thresholds for storm formation or intensification, where small perturbations in conditions can alter outcomes. This context-dependency reconciles divergent findings and aids the integration of forests into climate risk assessments. Forest conservation provides clear post-landfall protection; pre-landfall effects, while uncertain, further strengthen the case for protection and highlight research priorities. Full article

The primary shelf life (PSL) of fresh vegan spinach gnocchi packaged under a modified atmosphere (MAP) was investigated. Microbiological, physicochemical, and sensory properties were monitored during storage at three temperatures (4, 8, and 12 °C). The microbial load remained below the limit considered safe (3 log CFU g⁻¹) in all samples during storage at all tested temperatures. Storage time significantly increased the hardness of uncooked gnocchi (p < 0.05) and the water absorption index (p < 0.05). Moreover, at higher storage temperatures, the kinetic rate of hardness decreased in uncooked gnocchi (0.29 N day⁻¹ at 12 °C vs. 0.35 N day⁻¹ at 4 °C). Conversely, in cooked gnocchi, as the storage temperature increased, the rate of hardness acceleration increased. The sensory analysis results varied according to storage temperature, and the Overall Quality Index (OQI), combined with principal component analysis (PCA), was used to determine PSL values. The Arrhenius relationship successfully described the temperature dependence of reaction rate constants, and the calculated Q₁₀ value (3.0) confirmed hardness as the quality attribute most affected by temperature. OQI showed a strong correlation with cooked-gnocchi hardness, and a sensory cutoff of 6.5 was established and confirmed by the sensory panel. The corresponding hardness rejection value was 12.1 N. The PSL was estimated based on sensory and texture criteria, as microbial quality was not a limiting factor. Under non-isothermal cold-chain conditions, PSL was predicted using the time–temperature tolerance (TTT) approach, yielding a value of 42 ± 3 days. Full article

Microplastics (MPs) and nanoplastics (NPs) have emerged as pervasive contaminants across diverse environments—including soil, water, and the atmosphere—posing substantial risks to resident organisms. Concurrently, alien plant invasion represents a significant driver of environmental change, introducing considerable ecological risks to terrestrial ecosystems. Synthesizing evidence from 26 original research articles, this review examines the bidirectional interactions between micro(nano)plastics (MNPs) and terrestrial invasive plants. A growing body of evidence indicates that MNPs alter the growth and performance of both invasive and native plants. In most documented cases, MNPs appear to enhance the competitive ability of invasive plants, thereby elevating invasion potential. However, counterexamples exist wherein MNPs strengthen the competitiveness of native plants, consequently mitigating invasion risk. These divergent outcomes are likely attributable to a suite of influencing factors, notably the characteristics of the MNPs (e.g., type, size, concentration), the specific invasive and native plant species involved, and variations in experimental conditions. Key mechanistic pathways involve MNPs-induced disturbances in soil microecology—particularly nutrient dynamics and rhizosphere microbiomes—and allelopathic interactions. Conversely, invasive plants may adsorb/absorb MNPs and subsequently modify their environmental fate and behaviors (e.g., degradation, transport). Finally, we delineate critical knowledge gaps and propose prioritized directions for future research. This review advances our understanding of the ecological risks associated with plant invasions in an era of pervasive MNP pollution and offers a scientific foundation for developing informed management strategies. Full article

Polar Stratospheric Clouds (PSC) have been observed by the lidar observatory at Concordia station since 2014. The Concordia lidar is one of a few primary lidar stations in Antarctica of the Network for the Detection of Atmospheric Composition Change (NDACC). The lidar system was deployed at McMurdo from 2004 to 2010 and has been upgraded before its installation at Concordia. Concordia station is one of the most favourable locations for the observation of polar stratospheric clouds, due to the limited cloud cover by tropospheric clouds and the ubiquitous presence of PSCs throughout the Antarctic winter. The PSCs observations have been synchronized with the overpasses of satellite borne lidars, CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) on the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite from 2014 to June 2023, and the Atmospheric Lidar (ATLID) on the EarthCARE (Earth, Cloud, Aerosol and Radiation Explorer) mission since September 2024. A modified v2 algorithm, used for the detection and classification of PSCs as observed by CALIOP, has been used to determine detection limits and classification criteria. This facilitates comparison with CALIOP PSC profiles during quasi-coincident overpasses of the CALIPSO with respect to Concordia station. A local PSC climatology has been produced, with typically more than 150 profiles per PSC season. Considerable inter-annual variations have been observed, mostly depending on the local temperature. The data have been used to infer a decadal trend of PSC occurrences, although the large inter-annual variability renders such an approach difficult. The occurrences of the different PSC types show a strong correlation with the local temperature and depend on the formation processes and the formation temperatures of the different PSCs. Full article

Emerging contaminants (ECs) comprise diverse pollutant classes that are increasingly detected in remote environments due to their persistence and long-range transport potential. In cold regions, atmospheric cold-trapping processes favour their accumulation in high-altitude and high-latitude snow and ice, which act as sensitive archives and secondary sources of contamination. While previous studies have addressed individual environmental compartments (e.g., snowpack, glacier ice, meltwater), focusing on specific contaminant classes, a systematic review integrating the occurrence, behaviour and impacts of major EC groups in polar and alpine snow and ice is still lacking. To fill this gap, this work synthesised current knowledge on the environmental fate of three key EC categories in the cryosphere: metals and metalloids (MMs), industrial chemicals and by-products (ICBs), and pharmaceuticals and personal care products (PPCPs). PRISMA guidelines were accurately followed for research, which was based on a Google Scholar search combining keywords on cryospheric matrices (snow, firn, ice cores), geographical regions (Arctic, Antarctic, Alps, high mountains), and contaminant classes. Of 350 records initially identified, 300 met the eligibility criteria (post-industrial snow, firn, or ice cores studies) after excluding studies focused on aerosol or meltwater-only, method-focused papers, pre-industrial datasets, urban-only investigations, and duplicates. Risk of bias was qualitatively assessed through manual screening, evaluating matrix eligibility, temporal consistency, analytical methods, detection limits, and duplicate data, with particular attention to inconsistencies in ECs classification. Strict operational definitions were therefore applied to ensure methodological coherence. Concentration data were harmonised into a standardised database, and findings were synthesised through a structured narrative supported by tabulated datasets organised by matrix and site. Overall, the evidence indicates widespread occurrence of ECs in the global cryosphere, with spatial variability linked to emission sources, long-range transport pathways, and snow physicochemical properties. Climate-change-driven alterations of snow dynamics, glacier retreat and permafrost thaw are expected to modify partitioning equilibria and enhance the secondary release of legacy and contemporary contaminants. However, significant limitations persist, including geographical gaps, variability in analytical sensitivity, lack of long-term monitoring for certain EC classes, and inconsistencies in contaminant classification frameworks. Despite these constraints, the synthesis highlights consistent emerging patterns and underscores the need to strengthen existing environmental protocols to mitigate potential risks to ecosystems and human health. Full article

This study investigated how different LED spectral compositions affect seed germination, early growth, photosynthetic efficiency, and the postharvest quality and microbiological stability of Ipomoea aquatica Forsk. cultivated in a plant factory system, aiming to propose an integrated management strategy for stable year-round production. Five LED light treatments with varying red and blue light ratios (R10, R7B3, R5B5, R3B7, and B10) were applied during cultivation. After harvest, the plants were stored under low-temperature conditions using either carton box packaging or modified atmosphere packaging (MAP) to evaluate postharvest quality and microbial changes. Germination analysis indicated that red-dominant treatments (R10 and R7B3) significantly enhanced germination percentage, rate, and uniformity. These treatments also promoted greater plant height and fresh biomass accumulation during early growth while maintaining a higher maximum quantum yield of photosystem II (Fv/Fm), indicating improved photochemical efficiency. In contrast, blue-dominant treatments led to reduced growth performance and lower Fv/Fm values. Postharvest quality and microbiological stability were more significantly affected by the packaging method than by the LED light treatment. MAP effectively minimized fresh weight loss and inhibited the growth of aerobic bacteria, Escherichia coli, total coliforms, and yeast and mold during storage. Overall, the findings demonstrate that red-centered LED spectra are optimal for enhancing early growth and physiological stability of I. aquatica, while MAP is crucial for preserving postharvest quality and microbial safety. This study underscores the synergistic potential of combining LED spectral management during cultivation with optimized packaging strategies to achieve stable year-round production and extended shelf life of I. aquatica in controlled plant factory systems. Full article

Nitrogen oxides represent a major source of concern related to atmospheric pollution, causing substantial impacts on human health. One innovative approach to reducing these emissions, and a promising alternative to conventional methods using NH₃, is selective catalytic reduction with carbon (SCR-C). The aim of this study is the development of carbon-based catalysts that are active in the reduction of NO. For that, carbon nanotubes were subjected to treatments to modify their surface chemistry, including introducing oxygen and nitrogen groups, as well as potassium (K) and copper (Cu) incorporated as metal phases. In their original form, carbon nanotubes do not exhibit catalytic activity in reducing NO. However, catalytic performance is significantly improved by the addition of surface groups and Cu. Adding K to the support notably contributes to increasing the catalytic performance. N-doped carbon nanotubes impregnated with copper and potassium (CNT_M_BM@5Cu5K) achieved complete NO reduction at 360 °C. In this catalytic system, the formation of CO₂ and N₂ was observed and CO was not identified. Furthermore, although N₂O was detected during the reaction, its amount was very low compared to the N₂ and CO₂ products. The stability of this catalyst was investigated over 87 h continuous test, revealing deactivation after 41 h of reaction. Full article