Search Results (833)

Columnar-structured thermal barrier coatings deposited via the suspension plasma spray process have attracted significant attention due to their long thermal cycling life and high cost-effectiveness. In this work, the effects of suspension properties, including solvent type, viscosity, and particle size, on the formation of different coating microstructures were investigated via a comparative study. Two different kinds of solvents (water and ethanol) and particles of different sizes (D50 = 0.45 μm and 1.2 μm) were used to prepare suspensions for coating deposition, respectively. When using suspensions containing small-sized particles as feedstock, coatings deposited from the ethanol-based suspension showed columnar microstructures with inter-column crevices, while the water-based suspension resulted in cracked–columnar microstructures, showing a mixture of columns and cracks. When the large-sized particles were used to prepare the suspension, both the ethanol-based suspension and the water-based suspension resulted in homogeneous coating microstructures. The formation mechanism of different microstructures was investigated by modelling the diverted plasma jet and the in-flight particle movement during the impingement period. Particles smaller than 2 μm were strongly affected by the diverted plasma gas, showing obvious oblique impinging trajectories, while particles larger than 3 μm kept their original trajectories and impinged on the substrate orthogonally. The formation mechanism of different microstructures was elaborated by analyzing the impinging trajectories of particles transitioning from different suspensions. Full article

The present study presents the results of an analytical and experimental investigation on the behaviour of Al₂O₃ particles injected into the plasma jet. The dependence of the temperature of the particles and velocity profiles on particle size was estimated by numerically simulating the specific plasma jet in the plasma chemical reactor. The velocity of the particle was investigated experimentally using the ParticleMaster shadowgraphy laser imaging system. The heat flux from the plasma jet to the particles was estimated numerically, and the results were compared with the experimental measurements. Mineral fibre and granules were produced during the plasma spraying process. The studies performed showed that the interaction of the plasma jet and dispersed particles in the reactor mainly depends on the particle’s size, velocity, and temperature of the plasma flow. The modelling and measurements were performed under plasma conditions chosen below the full melting temperature of alumina to avoid particle deposition on the walls while still representative of the reactor environment where finer fractions contribute to melt and fibre formation. The heat flux to the particles inside the reactor increased with the increase in the particle-plasma mass ratio in the reactor. Full article

Non-thermal plasma has attracted strong interest in medicine and agriculture due to its ability to generate reactive oxygen and nitrogen species (RONS). These species can stimulate wound healing and seed germination, but at higher levels they induce DNA damage—useful in cancer therapy but harmful when healthy cells must be preserved. Direct study of DNA damage in cells is difficult because of repair processes and protective barriers. To address this, we applied a dual-model system combining plasmid DNA and human lymphocytes exposed to plasma from the RPS40 device. Using selective scavengers, we identified hydroxyl radicals, ozone, and reactive nitrogen species as key mediators of DNA strand breaks and structural changes. Our results support a mechanistic model in which long-lived plasma-derived species (NOx, ozone, acids) dissolve in water and subsequently generate short-lived radicals such as hydroxyl radicals and peroxynitrite. These reactive molecules then directly attack DNA. This integrated approach—linking plasmid and cellular assays with scavenger-based identification of RONS—offers a novel and cost-effective method for dissecting plasma–DNA interactions. The findings provide mechanistic insight into how plasma-activated water damages DNA, guiding the safer and more effective application of plasma technologies in biomedical and agricultural contexts. Full article

Non-thermal or cold plasma is an innovative agricultural technology used for the treatment of seeds, producing physicochemical and biochemical changes without thermal damage and stimulating germination and plant growth. The interaction of reactive species generated in cold plasma modifies the morphology of the seed surface, increasing porosity, producing microcracks, removing material or producing other physical changes, and chemically modifying it. The changes induced positively influence the rate, speed, and uniformity of germination, as it is believed that these changes take place as a result of activated metabolic pathways, regulated hormone balance, and stimulated production of enzymes involved in the mobilisation of nutrient reserves needed for seedling growth. Plasma sources, electrical parameters, feed gas, and processing time are some of the essential factors involved in tuning the effects on seeds. Optimising the outcomes and their adaptation for specific species is crucial to maximise the benefits and avoid inhibitory effects. In the frame of ecological and sustainable agriculture, with the benefits given by cold plasma, this review follows the modifications produced by different sources on the seeds, starting from morphological changes to biochemical ones, up to germination, aiming to facilitate the understanding of the interaction and outcomes. We also address the challenges, including variability of biological responses, the need for standard procedures and parameters, and development of scalable technologies. A thorough examination of the changes induced in seeds as a result of non-thermal plasma treatment not only facilitates the improvement of experimental designs and reproducibility but also plays an important role in advancing seed treatment technologies and, ultimately, enhancing crop yields in a sustainable manner. Full article

To achieve rapid screening and semi-quantitative analysis of pesticide residues in mobile laboratories and on-site tea testing, a novel method based on thermal-assisted plasma ionization–time-of-flight mass spectrometry (TAPI-TOF/MS) has been developed for the detection of 20 pesticide residues, including insecticides and fungicides, in tea. This method eliminates the need for liquid chromatography, or column connections. Instead, it utilizes the high temperature of the sample inlet and stage to fully volatilize and inject the sample. By integrating TAPI-TOF/MS with an automated pesticide residue pretreatment instrument, the entire sample extraction process can be performed automatically. The analysis time for each sample has been reduced to 1.5 min, allowing for the processing of 60 samples per batch. An accurate mass spectrometry database has been established for screening and confirmation purposes. The software automatically matches the mass spectrometry database by analyzing the measured ion mass deviation, ion abundance ratio, and the relative contribution weight of each ion, generating a qualitative score ranging from 0 to 100. The lowest concentration yielding a qualitative score of ≥75 was defined as the screening limit, which ranged from 0.10 to 5.00 mg/kg for the 20 pesticides. Within their respective linear ranges, the method demonstrated good linearity with correlation coefficients (R²) ranging from 0.983 to 0.999. The average recovery rates (n = 5) of the target pesticides ranged from 70.6% to 117.0% at the set standard concentrations, with relative standard deviations (RSD) ranging from 1.7% to 13.1%. Using this method, 15 tea samples purchased from the Rizhao market in China were analyzed. Ten samples were found to contain residues of metalaxyl or pyraclostrobin, yielding a detection rate of 66.7%. This technology provides technical support for the rapid detection and quality control of multiple pesticide residues in tea, meeting the requirements for high-throughput and on-site analysis. Full article

This research demonstrates the high efficiency of thermal plasma gasification for the treatment of simulated operational radioactive waste (SORW), representative of the low-level radioactive waste (LLW) generated in Argentina. A prototype system with a 4.8 kW plasma torch was used to process SORW composed of nitrile gloves, laboratory paper, and stable non-radioactive elements to simulate ⁶⁰Co, ⁹⁰Sr, ¹³⁷Cs, and ¹⁴⁴Ce. The process achieved vast volume reduction (99.6%), converting 5625 mL of waste into minimal volumes of four different solid residues (SR): SR1 (20 mL), SR2 (1 mL), SR3 (1 mL), and SR4 (3 mL), resulting in a volume reduction factor (VRF) of 225. Elemental analysis showed clear differences in retention behavior: excellent retention for Co (96 ± 10% inside the plasma reactor) and Ce (59 ± 6%), while more volatile Sr (39 ± 4%) and Cs (26 ± 3%). The latter were partially captured in downstream components (22.8 ± 1.1% Sr and 2.9 ± 0.15% Cs in quencher). The gases treatment system achieved >97% reduction for most plasma generated pollutants: NO_x (98.9 ± 0.6%), CO (98.2 ± 0.8%), H₂S (97.6 ± 0.6%), and H₂ (98.1 ± 0.9%), with 80.6 ± 2.5% for SO₂ and 75.0 ± 1.1% reduction for CO₂. Full article

Fermented vegetables, which are valued for their distinctive organoleptic properties and nutritional profile, are susceptible to quality deterioration during processing and storage because microorganisms inhabit vegetable raw materials. The metabolic processes of these microorganisms may induce texture degradation, chromatic alterations, flavor diminution, and spoilage. Conventional inactivation methods employing thermal sterilization or chemical preservatives achieve microbial control through nonselective inactivation, inevitably compromising the regional sensory characteristics conferred by indigenous fermentative microbiota. Recent advances in existing antimicrobial technologies offer promising alternatives for selective microbial management in fermented vegetable matrices. Existing modalities, including cold plasma, electromagnetic wave-based inactivation (e.g., photodynamic inactivation, pulsed light, catalytic infrared radiation, microwave, and radio frequency), natural essential oils, and lactic acid bacterial metabolites, demonstrate targeted pathogen inactivation while maintaining beneficial microbial consortia essential for quality preservation when properly optimized. This paper explores the applications, mechanisms, and targeted microbes of these technologies in fermented vegetable ingredients, aiming to provide a robust theoretical and practical framework for the use of selective inactivation strategies to manage the fermentation process. By assessing their impact on the initial microbial community, this review aims to guide the development of methods that ensure product safety while safeguarding the characteristic flavor and quality of fermented vegetables. Full article

Non-thermal technologies (NTTs) such as ultrasound (US), pulsed electric fields (PEF), high-pressure processing (HPP), cold plasma (CP), and pulsed light (PL) are emerging as versatile tools in food fermentation, offering microbial control and process enhancement without the detrimental heat effects of conventional methods. Operating at ambient low temperatures, these techniques preserve heat-sensitive compounds, modulate microbial activity, and improve mass transfer, enabling both quality retention and functional enrichment. Recent studies highlight their potential to stimulate metabolic pathways and enhance the release of bioactive compounds, opening new opportunities for fermented food production. The bibliometric analysis of the recent literature further reveals a growing interest in NTT applications in fermentation, with HPP and PEF showing the highest industrial maturity. Each technology exhibits distinct mechanisms and optimal niches across upstream, midstream, and downstream stages: HPP for uniform volumetric treatment, US for fermentation intensification, CP for surface-selective oxidative chemistry, PEF for membrane permeability control, and PL for rapid, residue-free decontamination. While the degree of industrial readiness varies, critical barriers such as scale-up limitations, high capital costs, energy distribution uniformity, process standardization, and techno-economic feasibility remain to be overcome. Beyond technical aspects, the successful commercialization of NTTs will also depend on addressing regulatory approval pathways, ensuring consumer trust and acceptance, and demonstrating their contribution to sustainability goals through lower energy use, reduced food waste, and environmentally responsible processing. Strategic, stand-alone, or hybrid applications of NTTs can therefore act not only as technological alternatives but also as enablers of a more sustainable, consumer-centered, and innovation-driven food system. Full article

Advanced oxidation processes (AOPs) utilising a hydroxyl radical (•OH), a strong oxidant, are seen as a promising solution for removing hazardous and recalcitrant pollutants from waste streams. Among AOPs, non-thermal plasmas, especially pulsed corona discharge (PCD), enable the abatement of hazardous volatile organic compounds (VOCs) with high energy efficiency. This study demonstrates the viability of upscaling PCD technology with water sprinkling in degrading the VOC toluene using a semi-pilot scale plasma reactor. A toluene–air mixture was treated with varying gas-phase toluene concentrations (30–100 ppm) and pulse repetition frequencies (25–800 pps), achieving toluene removal of 5–55% in PCD and an additional 10–18% in PCO, as well as excellent toluene removal energy efficiencies from 9.0 to 37.1 g kW⁻¹ h⁻¹. The process design with water sprinkling provides additional advantages compared to dry reactors—the water surface serves as a source of hydroxyl radicals and scrubs the air from degradation by-products resulting from the incomplete oxidation of target pollutants. Transformation products of toluene were identified, and an oxidation pathway via hydroxylation of the aromatic ring was suggested as the major route towards ring-opening reactions. A photocatalytic oxidation reactor with TiO₂ catalyst plates, following PCD as a post-treatment, enabled additional removal of residual contaminants, also converting residual ozone to oxygen. The PCD reactor with water sprinkling and post-plasma photocatalysis shows promising results for upscaling the process. Full article

A system-level study of a NO_x abatement process by means of non-thermal plasma (NTP) generated with dielectric barrier discharges (DBDs) is the framework of this article. With the goal of system improvement, the kinetic reaction simulation software ZdPlaskin is considered to select the most favorable operating conditions in order to optimize NO_x abatement (deNO_x). A parametric exploration of the performance, through variations in operating conditions (temperature, power injection pattern, and input gas mixture composition), requires highly numerous simulations; thus, the shortest possible computation times with robust results are of significant interest. As such, an analysis and filtering method is proposed and detailed to build a minimized chemical kinetic reaction set, allowing us to reliably analyze the impact of the selected operating conditions for the DBD reactor on treatment performance. Full article

Natural food colourants are gaining momentum in the food industry due to their clean-label appeal, safety, and potential health benefits. However, their practical application is often constrained by instability under environmental stressors such as pH fluctuations, heat, light, and oxygen. In response, both traditional and innovative strategies have emerged to improve pigment stability, with some studies reporting up to 50–80% retention of colour intensity under optimised conditions. Most existing research focuses on extraction, with limited emphasis on post-processing stability. This article reviews a wide range of food processing strategies aimed at enhancing the stability of natural pigments. It covers conventional and emerging approaches, including natural chemical stabilisers such as co-pigments, antioxidants, and metal ion chelators, physicochemical methods such as micro- and nanoencapsulation using biopolymers, and physical interventions involving drying technologies, particle size modification, and protective packaging. Modern technologies such as high-pressure processing, pulsed electric fields, ultrasound, and cold plasma are discussed as promising non-thermal alternatives, demonstrating 20–70% improvement in pigment retention compared to untreated controls. By integrating these diverse approaches, this article highlights current advancements, identifies knowledge gaps, and discusses future directions to support the development of stable, sustainable, and functional natural colourant systems for next-generation food products. Collectively, these approaches demonstrate significant potential to improve the performance and resilience of natural pigments in complex food systems. Full article

Understanding and modeling the effect of magnetic fields on flows that present separation properties, such as those over a backward-facing step (BFS), is critical due to its role in metallurgical processes, nuclear reactor cooling, plasma confinement, and biomedical applications. This study examines the hydrodynamic and magnetohydrodynamic numerical solution of an electrically conducting fluid flow in a backward-facing step (BFS) geometry under the influence of an external, uniform magnetic field applied at an angle. The novelty of this work lies in employing an in-house finite-volume solver with a collocated grid configuration that directly applies a Newton–like method, in contrast to conventional iterative approaches. The computed hydrodynamic results are validated with experimental and numerical studies for an expansion ratio of two, while the MHD case is validated for Reynolds number $Re=380$ and Stuart number $N=0.1$. One of the most important findings is the reduction in the reattachment point and simultaneous increase in pressure as the magnetic field strength is amplified. The magnetic field angle with the greatest influence is observed at $\phi =\pi /2$, where the main recirculation vortex is substantially suppressed. These results not only clarify the role of magnetic field orientation in BFS flows but also lay the foundation for future investigations of three-dimensional configurations and coupled MHD–thermal applications. Full article

This study evaluates the application of metal additive manufacturing—specifically the laser powder bed fusion (LPBF) process—for producing aluminium die-casting mould components, comparing 300-grade maraging steel inserts with conventional H13 tool steel. Efficient thermal management and mould durability are critical in aluminium injection moulding. Still, traditional machining limits the design of cooling channels, resulting in hot spots, accelerated wear, and a reduced service life. LPBF allows the fabrication of complex geometries, enabling conformal cooling channels to enhance thermal control. Component samples were manufactured using maraging steel via LPBF, machined to final dimensions, and subjected to duplex surface treatment (plasma nitriding + CrAlN PVD coating). Thermal performance, dimensional stability, mechanical properties, and wear resistance were experimentally assessed under conditions simulating industrial production. The results demonstrate that LPBF components with optimised cooling channels and surface engineering achieve higher thermal efficiency, an extended service life (up to 2.6×), improved hardness profiles (545 HV0.05 core, 1230 HV0.05 on nitrided surface and 2850 HV0.05 after PVD film deposition), and reduced maintenance frequencies compared to H13 inserts. The study confirms that additive manufacturing, combined with tailored surface treatments and optimised cooling design, overcomes the geometric and thermal limitations of conventional manufacturing, offering a reliable and productive solution for aluminium die-casting moulds. Full article

Aluminum nitride (AlN) ceramic materials have relatively low thermal conductivity and poor heat dissipation performance, and are increasingly unsuitable for high-power LED packaging. In this study, diamond films were deposited on AlN ceramic substrates by microwave plasma chemical vapor deposition (MPCVD). The effects of different process parameters on the crystal quality, surface morphology and crystal orientation of diamond films were studied, and the high thermal conductivity of diamond was used to enhance the heat dissipation ability of AlN ceramic substrates. Finally, the junction temperature and thermal resistance of LED devices packaged on AlN ceramic–diamond composite substrate, AlN ceramic substrate and aluminum substrate were tested. The experimental results show that compared with the traditional aluminum and AlN ceramic substrates, AlN ceramic–diamond composite substrates show excellent heat dissipation performance, especially under high-power conditions. Full article

In this study, the effects of plasma assistance on the electron beam physical vapour deposition (EB-PVD) process were investigated using an industrial coater (Smart Coater ALD Vacuum Technologies GmbH) equipped with a dual hollow cathode system. This configuration enabled the generation of a plasma environment during the deposition of the ceramic top coat onto a metallic substrate. The objective was to assess how plasma assistance influences the microstructure and thickness distribution of 7% wt. yttria-stabilised zirconia (YSZ) thermal barrier coatings (TBCs). Coatings were deposited with and without plasma assistance to enable a direct comparison. The thickness uniformity and columnar morphology of the 7YSZ top coats were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical properties of the deposited coatings were verified by the scratch test method. The results demonstrate that, in the presence of plasma, columnar grains become more uniformly spaced and exhibit sharper, well-defined boundaries even at reduced substrate temperatures. XRD analysis confirmed that plasma-assisted EB-PVD processes allow for maintaining the desired tetragonal phase of YSZ without inducing secondary phases or unwanted texture changes. These findings indicate that plasma-assisted EB-PVD can achieve desirable coating characteristics (uniform thickness and optimised columnar structure) more efficiently, offering potential advantages for high-temperature applications in aerospace and power-generation industries. Continued development of the EB-PVD process with the assistance of plasma generation could further improve deposition rates and TBC performance, underscoring the promising future of HC-assisted EB-PVD technology. Full article