Search Results (1,896)

This paper presents a comprehensive investigation of the effects of atmospheric plasma treatment (APT) on the surface morphology, microhardness, chemical composition, and tribological performance of alloy steel used in railway applications. A novel mathematical model is proposed to describe the dependence of the maximum surface asperity height on the APT parameters and material properties. Experimental validation was performed using a series of alloy steel specimens treated under controlled APT conditions. The surfaces were characterized by roughness measurements, microhardness testing, scanning electron microscopy, and energy-dispersive spectroscopy. Tribological properties were evaluated under dry sliding conditions using ball-on-disk tests with steel counterbodies (grades 1.3529 and 1.3505). Tribological testing showed that APT leads to a 6–7% reduction in the steady-state friction coefficient, eliminates the long running-in stage, and improves stability by lowering the coefficient of variation by up to 43%. Overall, this study demonstrates that APT provides a dual benefit: improving tribological performance through surface smoothing and stabilization of the friction regime, and preserving the mechanical and chemical integrity of the material. Full article

Background: Minimally invasive aesthetic procedures using atmospheric plasma devices are increasingly applied to improve skin laxity and age-related loss of firmness. These systems generate a localized plasma arc at the tissue surface, enabling controlled and spatially confined tissue interaction; however, quantitative histological data on the extent of plasma-induced tissue effects remain limited. Materials and Methods: This ex vivo study evaluated freshly collected porcine kidney, liver, and skeletal muscle tissues (n = 3 per tissue type). Tissue sublimation defects were produced using the Plasma IQ device under conditions representative of standard clinical use, applying two predefined settings (“LOW” and “HIGH”). Immediately after treatment, specimens were fixed in 10% neutral buffered formalin and processed into formalin-fixed paraffin-embedded (FFPE) blocks. Sections were stained with hematoxylin and eosin (H&E), and the diameter and depth of the sublimation zones were measured by light microscopy. Results: Plasma IQ exposure consistently produced well-demarcated superficial sublimation defects in all tissues. The HIGH setting increased the diameter of the sublimation zones compared with the LOW setting across all tissue types, whereas the depth differences were smaller and tissue-dependent. Lesions exhibited a characteristic flattened, cone-shaped morphology, with diameter exceeding depth. No histologically detectable collateral damage was observed beyond the immediate sublimation zone. Conclusions: Atmospheric plasma treatment induces controlled and spatially confined tissue sublimation with clearly defined histological boundaries and limited penetration depth. These findings provide quantitative histological support for the localized tissue effects of plasma-based devices and their rationale in aesthetic procedures. Full article

Direct current (DC) surface flashover on polystyrene (PS) remains a critical bottleneck that impedes its reliable application in high-voltage insulation apparatus. To circumvent the protracted processing durations and stringent film-forming conditions inherent in conventional surface modification techniques, this study proposes a novel “liquid-film-assisted in situ rapid plasma curing” strategy. By harnessing atmospheric-pressure dielectric barrier discharge (DBD) technology within an argon ambient, the rapid (<6 min) and efficient deposition of a fluorosilane (FAS-13) functional coating onto the substrate was achieved. Microscopic characterizations coupled with isothermal surface potential decay (SPD) measurements reveal that this coating substantially mitigates the detrapping and surface migration of charge carriers. Macroscopic DC flashover testing corroborates that, under the optimal modification ratio, the surface breakdown voltage of PS is elevated to 14.04 kV, yielding an insulation gain of 26.94%. To elucidate the underlying physical mechanisms, density functional theory (DFT) calculations were conducted, revealing that the energy band misalignment between the wide-bandgap fluorinated layer and the substrate facilitates the construction of a high-density deep trap network (with a depth of ~0.8 eV) at the coating–substrate interface. By robustly anchoring primary electrons and inducing the formation of a homopolar space charge shielding layer, these deep traps physically arrest the evolution of the secondary electron emission avalanche (SEEA). Consequently, this work not only establishes a viable engineering framework for the rapid, large-scale surface reinforcement of DC insulation equipment but also provides profound quantum chemical insights into interfacial trap regulation within all-organic dielectrics. Full article

Data on arsenic (As) and other potentially toxic elements (PTEs) in Pakistani retail meats are limited, constraining evidence-based dietary risk assessment and management. This study aimed to determine the concentrations and profiles of As and seven other PTEs (Cr, Ni, Mn, Pb, Cd, Cu, Zn) in commonly consumed meats and to evaluate the associated non-carcinogenic health risks. Ninety-two paired liver and muscle samples from broiler chicken, goat (mutton), and beef cattle were collected from four cities across the Indus Plain and analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Dietary exposure was evaluated using estimated daily intake (EDI), target hazard quotient (THQ), and hazardous index (HI) under typical and high-consumption scenarios. Overall, Zn and Cu exhibited the highest concentrations, followed by Mn and Cr, whereas As, Pb, Ni, and Cd occurred at comparatively lower but environmentally relevant levels. Beef liver exhibited the highest contamination levels, exceeding FAO/WHO permissible limits for Pb, Cu, and Cd in up to 40% of samples. In contrast, mutton and beef muscle contained the highest As and Zn concentrations, while chicken muscle showed elevated Cr levels. Multivariate statistical analysis revealed three dominant co-variation patterns, suggesting potential contamination pathways: (i) geogenic groundwater sources enriched with As, Cr, and Ni; (ii) atmospheric and industrial dust inputs linked with Pb, Cd, and Mn; (iii) mineral-enriched feed additives potentially contributing to elevated Zn and Cu, particularly in poultry. Under high-consumption scenarios, THQ values for As, Cr, Cu, and Zn exceeded the safety threshold (THQ > 1), highlighting beef products as the dominant source of chronic dietary risk. Overall, the findings highlight pronounced tissue- and species-specific accumulation trends, and emphasizes the urgent need for stricter feed and water quality control measures to minimize dietary exposure to PTEs. Full article

The scalable production of high-quality nanoparticles is a significant challenge for advancing nanotechnology applications. This research introduces a continuous-flow liquid-plasma discharge reactor for the synthesis of silver nanoparticles at room temperature and atmospheric pressure, utilizing D-xylose as a dual-function reducing and stabilizing agent. The reactor effectively generated uniform xylose-capped silver nanoparticles (X-Ag NPs). Optimal conditions were established utilizing argon gas at a 1:100 molar ratio of Ag precursor to D-xylose, resulting in spherical X-Ag NPs with an average size of 16.89 nm, a zeta potential of −38.87 mV, and a polydispersity index of 0.22. The formation and properties of X-Ag NPs were confirmed through characterization techniques including UV-Vis spectroscopy, dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The findings demonstrate that uniform particle nucleation and growth occurred due to the homogeneous distribution of high-energy electrons and reactive gas species produced in the plasma phase. This environmentally sustainable, continuous-flow method shows considerable promise for the industrial-scale production of biomass-derived silver nanoparticles. Full article

Low-temperature atmospheric plasma (LTP) is widely used in industrial processes, such as disinfection, surface modification and wastewater treatment. The dielectric barrier discharge (DBD) is regarded as one of the most robust and reliable methods for generating LTP in ambient air. Compared to conventional AC excitation, pulsed powering offers several advantages (i.e., lower energy use and heat production). The present trend is to use short and fast pulses (in the nano- and picosecond range). In this review, the key design parameters of a DBD (barrier thickness, relative permittivity and gap distance) are discussed. Material-specific phenomena like surface charging and degradation are analyzed. The complex interactions between the pulse source and DBD are examined. By mapping the interdependencies, this review aims to support the rational design and optimization of pulsed DBD systems, and to facilitate their broader industrial use. Full article

Silica thin-film coatings used for surface protection of automotive parts are generally deposited by chemical vapor deposition (CVD). In this study, we investigated substrate pretreatment methods to improve the adhesion between a polycarbonate substrate and a silica thin film during the direct synthesis of a hard silica thin film on a polycarbonate substrate using remote atmospheric-pressure plasma CVD, without the use of an acrylic primer intermediate layer. Two types of substrate surface treatments were used: flame treatment and silicone baking. With flame treatment, the adhesion strength of the thin film was 43.5 mN, representing a 26% improvement compared to the untreated sample. With the silicone baking treatment, the adhesion strength was 42.3 mN, representing an improvement of approximately 22% compared to the untreated sample. Therefore, it is considered that the adhesion between the polycarbonate substrate and the silica thin film can be improved by controlling the state of the substrate surface through pretreatment. Full article

Capsicum L. is valued for its pungency and nutrition but is susceptible to postharvest deterioration such as weight loss, softening, and decay, leading to reduced quality and marketability. While conventional methods like refrigeration and chemical treatments extend shelf life, they raise safety and environmental concerns. Recently, environmentally friendly preservation techniques have gained attention, including physical (modified atmosphere packaging, cold storage, plasma), chemical (ozone, 1-MCP, chlorine dioxide, nano selenium), and biological (biopolymer films, essential oils, melatonin) approaches. Studies show that combining two or more methods often yields synergistic effects, outperforming individual treatments. This review systematically outlines the physiological and quality changes in postharvest capsicum fruits and summarizes recent advances in key preservation technologies, with emphasis on combined strategies. It aims to provide insights into preservation mechanisms, suggest future research directions, and support the development of safe, effective, and sustainable practices for the capsicum industry. Full article

Space weather events triggered by solar activity impact critical technologies like the Global Navigation Satellite System (GNSS) by causing atmospheric imbalances that alter ionospheric electron density. This study investigates the upper atmosphere response to the severe geomagnetic storms of October 2024, focusing on the coupling and compositional exchange between the ionosphere and thermosphere. Data were analysed from two mid-latitude African stations, Rabat (RABT) and Hermanus (HNUS), using GNSS-Total Electron Content (TEC) measurements alongside thermospheric circulation observations from NASA-GOLD and solar wind indices from OMNIWeb. The October 2024 storm, which reached a minimum Dst of −333 nT, drove a negative ionospheric storm phase marked by TEC depletions exceeding 50 TECU. This response was driven by storm-time thermospheric upwelling of N₂-rich air, which lowered the O/N₂ ratio and accelerated plasma loss via charge-exchange reactions. Furthermore, a distinct hemispheric asymmetry was observed, as the equatorward thermospheric circulation in the Northern Hemisphere arrived before that of the Southern Hemisphere. Direct post-processing of the Earth-Centred Earth-Fixed (ECEF) coordinates using RTKLIB single-point position revealed that, while positioning accuracy significantly degraded at HNUS with errors increasing by up to 270%, it counterintuitively improved at RABT, where errors reached their minimum during the main and early recovery phases of the storm. These findings highlight that the technological impact of severe space weather is determined not just by storm magnitude but by the specific sign and spatial structure of the regional ionospheric response. Full article

This study investigates how processing parameters and powder characteristics influence the mechanical performance of thermal barrier coatings (TBCs) applied to a Ti-6Al-4V alloy. Two TBCs were deposited by Atmospheric Plasma Spray (APS) using different processing conditions, feedstock characteristics, and coating thicknesses (thin and thick configurations). TBC characterization included powder size analysis, scanning electron microscopy (SEM), surface roughness, X-ray diffraction, instrumented indentation, and scratch testing. Mechanical behavior was assessed using creep testing at 125 MPa and 500 °C for coated and uncoated samples. Fracture surfaces of crept samples were analyzed by SEM and stereomicroscopy. Thicker TBC exhibited higher elastic modulus but contained microcracks and higher porosity, resulting in a higher steady-state creep rate (0.0006 h⁻¹, approximately 167% above the uncoated substrate) and reduced rupture time. Conversely, thinner TBC remained initially crack-free, promoting stress redistribution and leading to a lower creep rate (0.0002 h⁻¹, about 67% below the substrate) and delayed failure. Fractographic analysis revealed ductile fracture of Ti-6Al-4V in all conditions, indicating that coatings influenced damage accumulation rather than fracture mode. These findings underscore the combined effect of processing parameters and coating architecture on TBC performance for aerospace applications. Full article

Biomaterials play a central role in tissue engineering and regeneration by providing scaffolds that support cell adhesion, proliferation and differentiation while modulating the surrounding microenvironment. They represent promising alternatives to traditional surgical approaches that may lead to complications or tissue damage, and their performance is influenced by chemical composition, mechanical behavior, architecture and interfacial properties, all of which can be precisely tuned through advanced fabrication and surface modification strategies. This review synthesizes evidence from a comprehensive literature search across major scientific databases, focusing on highly cited studies and available clinical data, and examines natural and synthetic biomaterials, their biological responses, functional characteristics, and surface modification methods. Emphasis is placed on Cold Atmospheric Plasma (CAP), which selectively modifies the outermost nanolayer of materials, enhancing hydrophilicity, functional group density, protein adsorption and overall cell–material interactions, as well as improving drug loading capacity. The review also considers stem cell interactions with biomaterials and emerging applications of artificial intelligence (AI) for predicting performance and guiding material optimization. Overall, the analysis highlights that natural matrices provide intrinsic bioactivity, synthetic polymers offer tunable mechanics and degradation profiles, and composite systems integrate these advantages. Advances in technologies such as electrospinning and 3D/4D printing enable precise control over architecture, supporting cell colonization and vascularization. Collectively, developments in CAP treatments and AI-driven design strategies are strengthening the regenerative potential of biomaterials and advancing their clinical translation. Full article

Plasma-sprayed yttria-stabilized zirconia (YSZ) coatings are critical to enhancing the performance of thermal barrier coatings in gas turbines and aero-engines; however, their service life is significantly constrained by microstructural evolution and multi-mechanism coupling effects. Focusing on plasma spraying process routes (atmospheric plasma spraying, APS; suspension plasma spraying/solution precursor plasma spraying, SPS/SPPS; low-pressure plasma spraying, LPPS) and key process parameters as primary input variables, this review systematically analyzes their regulatory roles in microstructural characteristics such as porosity and crack density. Available studies indicate that distinct process routes give rise to pronounced structural differences: the porosity of APS coatings is 10%–20%, that of SPS/SPPS coatings is 15%–30%, and that of LPPS coatings is 1%–8%. After thermal exposure above 1100 °C, the porosity decreases to 6%–12%, 8%–18%, and 0.5%–3%, respectively, while the thermal conductivity increases to a maximum of approximately 2.5 W·m⁻¹·K⁻¹ and the Young’s modulus rises to 60–220 GPa. Further analysis reveals that mechanisms such as sintering densification, phase destabilization, thermally grown oxide (TGO) interfacial stress accumulation, and calcium–magnesium–alumino-silicate (CMAS) infiltration exert coupled amplification effects through microstructural evolution, thereby accelerating coating failure. On this basis, emerging regulation strategies are evaluated: the CMAS penetration depth of high-entropy oxides at 1300 °C for 5 h is only about 1/7 that of conventional YSZ, the thermal cycling life of self-healing coatings is enhanced by up to 4.2 times, and the crack density is reduced by approximately 35%. Finally, it is proposed that a quantitative prediction model integrating “structural parameters–evolution kinetics–service life” should be established, and that anti-sintering design, gradient structures, and functionalized systems be combined to enable the transition of YSZ coatings from empirical optimization to predictable design. Full article

Doxorubicin (DOX) is widely used in clinical chemotherapy, but its susceptibility to oxidation during the combined treatment with cold atmospheric plasma (CAP) raises concerns regarding its therapeutic efficacy. To improve drug stability and targeted delivery efficiency, this study employed classical molecular dynamics simulations to systematically investigate the mechanisms by which CAP-generated active particles and electric fields influence DOX encapsulation by carbon nanotubes (CNTs) and their transmembrane transport. Within a specific range of active particle concentrations, DOX aggregation is suppressed, enabling its spontaneous entry into CNTs for encapsulation. The CAP-induced electric field further promotes the directional migration of DOX, and once a threshold field strength is reached, the encapsulation efficiency is significantly enhanced. Moreover, an appropriate concentration of active particles can lower this threshold, enabling high encapsulation efficiency at electric field strengths as low as 0.3 V/nm. The introduction of CNTs can reduce the exposure of DOX to active particles, thereby effectively protecting it from CAP-induced oxidation. Regarding transmembrane transport, CAP-induced lipid oxidation decreases membrane structural stability, facilitating the intracellular internalization of CNTs and promoting the release of DOX within target cells. Furthermore, under the combined effects of oxidation and electric fields, the pulling force required for CNT transmembrane transport further decreases, the size of transmembrane pores increases, and the transmembrane delivery of DOX is enhanced. These results demonstrate that, under plasma synergy, CNTs exhibit significant potential in enhancing the targeted delivery of chemotherapeutic agents. This work provides important theoretical support for the application of plasma in targeted cancer therapy and offers new insights for the design of precision cancer treatment strategies. Full article

Platinum group elements (PGEs), especially platinum (Pt), palladium (Pd), and rhodium (Rh), are analyzed as emerging airborne contaminants in urban environments. This study aimed to monitor the spatial and temporal distribution of PGEs in urban air and to evaluate their potential as indicators of traffic-related emissions. The paper presents a five-year monitoring of Pt, Pd, and Rh mass concentrations in airborne particulate matter collected from three urban locations (North, Center, and South) with different traffic loads in Zagreb, Croatia. Weekly samples were digested in acid under high temperature and high pressure, and analyzed using inductively coupled plasma mass spectrometry (ICP-MS). At the monitoring location South, mass concentrations of all PGEs were generally 20–40% higher than at other locations, consistent with its higher traffic density. The PGEs showed seasonal variability, with 40–60% higher mass concentrations in winter and autumn than in spring and summer. The spatial and temporal distribution of PGE mass concentrations across urban locations demonstrates their potential as indicators of traffic-related activity. Palladium mass concentrations were consistently the highest, as a result of its increased use in modern catalytic converters. These findings underscore the relevance of long-term PGE monitoring for understanding urban atmospheric pollution dynamics within changing environmental conditions. Full article

Dental implants are widely used to replace missing teeth, but peri-implantitis remains a major biological complication associated with bacterial biofilm formation on implant surfaces. The increasing incidence of peri-implant infections underscores the need for alternative antimicrobial strategies that effectively decontaminate complex titanium implant surfaces. This study evaluated the inhibitory effect of low-temperature microwave argon plasma on bacteria in an experimental model simulating peri-implant conditions and compared the responses of microorganisms with different biological characteristics. A 3D-printed mandibular bone segment model with an inserted Straumann BLX Roxolid^® dental implant was used to reproduce the peri-implant environment. Bacterial suspensions of Streptococcus mutans NBIMCC 1786 and the extremophilic bacterium Chromohalobacter canadensis NBIMCC 9077 have been exposed to a microwave non-equilibrium argon plasma jet (2.45 GHz, atmospheric pressure) for 1–7 min. Optical density measurements and colony growth analysis were used to assess antimicrobial effects. Plasma treatment induced a pronounced reduction in bacterial growth during the early post-treatment period. In C. canadensis, growth inhibition reached a plateau (~47–55% at 24 h) regardless of exposure time. In contrast, S. mutans showed a nonlinear response, with stable inhibition after short exposures (1–3 min) and partial recovery after longer treatments (5–7 min). These findings indicate that microwave argon plasma exhibits significant antimicrobial activity under controlled in vitro conditions, although its effectiveness depends on microorganism-specific biological characteristics. Because the present model was based on simplified single-species systems, direct clinical extrapolation remains limited and should be addressed in future studies using polymicrobial peri-implant biofilm models. Full article