Plasma Treatment Research Articles

A Coherent Workflow for Elevating Transition Metal Oxide Anode Materials in Alkaline Electrolysis to Connect Insights from Micro Powder Analysis with Electrochemical Performance

Increasing environmental concerns have redirected research efforts toward sustainable energy, prominently highlighting hydrogen as a promising solution [1]. Despite considerable advancements in water electrolysis, providing efficient energy conversion and storage, there exists a gap in our comprehensive understanding of the production chain. This includes insights from commercial powder materials to electrode fabrication and their electrocatalytic behavior, representing an underexplored domain that demands closer examination.This study systematically examines transition metal oxide electrocatalysts, aiming to parameterize the process chain within the context of a coherent workflow for advancing transition metal oxide anode materials in alkaline electrolysis. This approach seeks to reveal the interdependencies and comprehend the correlations between material properties, fabrication processes, electrode structure, and the final performance of the cell. Our methodology integrates a range of complementary techniques to ensure a consistent analysis of the physical and chemical properties of the materials. Following the initial characterization of commercial micropowder through transmission electron microscopy and energy-dispersive X-ray spectroscopy, we optimized ink formulations derived from the powder using analytical centrifugation and Hansen parameter calculations [2]. Subsequently, selected inks were transferred to electrodes by coating these inks on Ni plates via ultrasonic spray deposition. We further investigated the impact of post-treatments, including vacuum annealing and surface plasma treatment, on the stability of the electrodes, particularly in terms of delamination prevention.To quantify the underlying micro features of this wide range of electrode surfaces and analyze their characteristics, we developed a framework called multistage data quantification (MSDQ). MSDQ ulitizes microscopical charcterizations such as laser microscopy and atomic force microscopy [3]. The assessed electrodes were finally tested as anodes for alkaline water electrolysis, revealing correlations between electrode properties and electrochemical activity and stability. In line with the recognized structural characteristics, our initial findings indicate that electrodes treated with plasma demonstrate reduced overpotentials and enhanced stability when compared to pristine and plasma treated electrodes, due to increased adhesion and surface properties (e.g., roughness).Our study makes a substantial contribution to the comprehensive evaluation of the alkaline water electrolysis system across its development stages, incorporating valuable insights from earlier steps to continually enhance electrode performance. Our approach is particularly advantageous in enabling the transition from laboratory-scale research to scalable processing, effectively bridging the crucial gap for practical industrial applications [4]. Ehlers, J.C., et al., "Affordable Green Hydrogen from Alkaline Water Electrolysis: Key Research Needs from an Industrial Perspective. " ACS Energy Letters, 2023. 8(3): p. 1502-1509.Bapat, S., et al., "On the state and stability of fuel cell catalyst inks. " Advanced Powder Technology, 2021. 32(10): p. 3845-3859.Jain, A., et al., "Small-Area Observations to Insight: Surface-Feature-Extrapolation of Anodes via Multistage Data Quantification. " Under review, ChemCatChemSegets, D., et al., "Accelerating CO2 electrochemical conversion towards industrial implementation." Nature communications 14.1 (2023): 7950.

(Invited) Wide Bandgap Semiconductor Homo- and Hetero-P-N Junctions

Wide bandgap (WBG) semiconductors, such as gallium nitride (GaN), gallium oxide (Ga2O3), aluminum nitride (AlN), and diamond, hold immense promise for power electronics applications by drastically reducing power loss, enhancing switching frequency, and reducing system volume. However, effective doping (p-type or n-type) remains a substantial challenge for these materials, given that the p-n junction is a fundamental building block for device design. Selective-area doping, crucial for high-performance electronic devices and integrated circuits, poses another significant obstacle.We report recent progress on selective-area doping for GaN homo-p-n junctions. Although GaN shows substantial development in both p-type and n-type doping, achieving selective doping, especially p-type, remains challenging through techniques such as ion implantation, diffusion, or in-situ doping. Our investigation delves into the challenges of p-GaN regrowth using metal-organic chemical vapor deposition (MOCVD). Interface contaminants post etching and regrowth, such as silicon (Si), carbon (C), and oxygen (O), have been systematically investigated. An optimized interface treatment has been identified to effectively reduce surface charge and, consequently, reverse leakage current to the level comparable to the as-grown p-n junction. Additionally, a novel hydrogen plasma treatment has been proposed to realize selective doping for GaN, successfully applied to p-GaN gated high electron mobility transistors (HEMTs) to improve the dynamic performance by avoiding the etching damage and edge termination for vertical GaN p-n diodes to realize high breakdown voltage.β-Ga2O3 has emerged as a standout in power electronics applications, surpassing Si (3000×), SiC (10×), and GaN (4×) in Baliga’s figure of merit. Its great potential for mass production, facilitated by the availability of high-quality and large-size wafers, significantly enhances its attractiveness. However, challenges, including the absence of p-type doping due to deep acceptor states and a flat valence band, as well as exceptionally low thermal conductivity, limit its performance at high power and temperatures. Overcoming these challenges necessitates hetero-integration with semiconductors possessing p-type characteristics and high thermal conductivity. P-type diamond stands out due to its exceptional thermal conductivity, high critical breakdown field, and well-established p-type characteristics. Moreover, since the n-type doping of diamond also poses challenges, fusing the p-type diamond and n-type Ga2O3 to create a diamond/Ga2O3 p-n-heterojunction can effectively overcome doping bottlenecks for both materials. Our successful construction of a diamond/β-Ga2O3 hetero-p-n junction through the mechanical integration of bulk p-type diamond and bulk n-type Ga2O3 presents robust electrical performance up to 125 ℃, with hysteresis lower than 0.7 V @ 1 μA. Impressively, the ideality factor of the p-n junction is remarkably low at 1.28, and the rectification ratio exceeds 108. This approach has also been applied to other hetero-p-n junctions, such as the diamond/GaN structure, demonstrating consistent robust performance. These findings underscore the significant potential of the mechanical integration approach, offering a promising avenue to simplify the fabrication process and facilitate the widespread application of WBG heterojunctions.

Passivated indium oxide thin-film transistors with high field-effect mobility (128.3 cm2 V−1 s−1) and low thermal budget (200 °C)

Here, we demonstrate a high-mobility indium oxide (In2O3) thin-film transistor (TFT) with a sputtered alumina (Al2O3) passivation layer (PVL) with a low thermal budget (200 °C). The sputtering process of the Al2O3 PVL plays a positive role in improving the field-effect mobility (µ FE) and current on/off ratio (I ON/I OFF) performance of the In2O3 TFTs. However, these enhancements are limited due to the high density of intrinsic trap defects in the In2O3 channels, as reflected in their large hysteresis and poor bias stability. Treating the In2O3 channel with oxygen (O2) plasma prior to sputtering the Al2O3 PVL results in notable improvements. Specifically, a high µ FE of 128.3 cm2V−1 s−1, a high I ON/I OFF over 106 at V DS of 0.1 V, a small hysteresis of 0.03 V, and a negligible threshold voltage shift under negative bias stress are achieved in the passivated In2O3 TFT (with O2 plasma pretreatment), representing a significant improvement compared to the passivated In2O3 TFT (without O2 plasma pretreatment) and the unpassivated In2O3 TFT. The remarkable reduction of intrinsic trap defects in the passivated In2O3 TFT compensated by O2 plasma is the primary mechanism underlying the improvement in µ FE and bias stability, as validated by x-ray photoelectron spectra, hysteresis analysis, and temperature-stress electrical characterizations. Plasma treatment effectively compensates for intrinsic trap defects in oxide semiconductor (OS) channels, when combined with sputter passivation, resulting in a significant enhancement of the overall performance of OS TFTs under low thermal budgets. This approach offers valuable insights into advancing OS TFTs with satisfactory driving capability and wide applicability.

Atmospheric Pressure Plasma Treatment of Glass Surface and Its Influence on the Reliability of Adhesive Bonding

Glass load-bearing structural elements are currently used more often in civil engineering. However, due to the brittle fracture of glass, it is necessary to design these structures with sufficient reliability. Adhesive joints have a number of advantages over mechanical connectors of glass commonly used in construction. Adhesives can eliminate thermal bridges and provide a more uniform stress distribution along the connection without weakening the bonded material.A variety of chemical methods have been developed for cleaning and activating glass surfaces prior to adhesive bonding. Recently, these methods have been substituted by glass surface cleaning and activation using ambient (humid) air plasma. Such an approach is considered much faster, technically simpler, and more environmentally friendly than the traditional chemical methods. For example, it eliminates the need for the so-called primer interlayer, where the primer is usually considered a heavy chemical with significant environmental impact.The presented work is focused on the surface activation of glass by atmospheric pressure plasma to improve adhesion using specially selected transparent adhesives. We studied Diffuse Coplanar Surface Barrier Discharge (DCSBD) plasma treatment of different float-glass, heat-treated and tempered glass surfaces in ambient air. The DCSBD plasma effect was evaluated by surface free energy and peel-test adhesion measurements. The morphological changes on the glass surface were investigated by scanning electron and atomic force microscopy. The glass-to-glass adhesion at elevated temperatures was tested with respect to the artificial ageing of adhesive bonding due to the environment. Acknowledgement: This research was supported by project LM2023039, funded by the Ministry of Education, Youth and Sports of the Czech Republic and supported by project No. GA23-06016S, funded by the Czech Science Foundation (GAČR).

Plasma-Enhanced Copper Sulfide/Oxide Electrode for Zinc-Air/Copper Dual Mode Battery

As search for novel electrochemical energy storage systems continues, metal-air batteries are one of the possible solution. Consisting of a metal anode and an air-breathing cathode, by design, they achieve much higher gravimetric energy density in theory. However, s-orbital metals suffer passivation issues and poses safety threats due to their reactivity with air and humidity. As a solution to this issue, safer d-block metals are being studied as an alternative. Zinc air batteries (ZABs) utilizes earth-abundant and cost-effective zinc as its anode, and has high theoretical capacity. At its cathode, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) occur during charging and discharge processes. Sluggish kinetics of ORR degrades the discharge performance, and is the bottleneck in commercial application of the zinc air battery. Additionally, irreversibility of the cathode reaction results in dissatisfactory retention of battery capacity. Current state-of-the-art noble metal catalysts achieves nearly 80% of the theoretical capacity. However, its cycling stability is severely limited to less than 200 cycles despite low discharge rate applied.Herein, we present a nitrogen plasma-enhanced copper sulfide/oxide catalyst (referred to as N-CuS) that exhibits good catalytic activity for its application as the air-breathing cathode for ZABs. The material is grown directly on metal foam surface using anodization, which is then treated using nitrogen plasma. Anodization creates defect-rich flakes of copper sulfide on the oxide surface, highly increasing surface area and creating the active sites. The material has good electrical conductivity and highly open porous structure that alleviates mass transport issues. Additionally, nitrogen plasma treatment further increases the surface area about 80%, and is expected to introduce nitrogen dopants to the surface, enhancing conductivity of the material. ECSA estimated by measuring Cdl shows that each process increases the ECSA by over 40 times and about 1.8 times, respectively.LSV of CuS and N-CuS half-cells have been performed to measure and compare catalytic performance of the material. N-CuS shows far higher current density and better catalytic activity (35mV less overpotential) than CuS, and higher output voltage is observed with N-CuS cells with the same current density. By assessing the GCPL (potential limited galvanostatic cycling) results, it was concluded that N-CuS requires lower charging voltage and exhibits higher discharge voltages than CuS.The overall performance was evaluated in a stack cell configuration, utilizing thin zinc foil as its anode to minimize mass error. The measured specific capacity of the cell was 789.3 mA·h·g-1, which approximately is 85% of the theoretical specific capacity of zinc-air cells (820 mA·h·g-1). This cell yields gravimetric energy density of about 666 Wh·kg-1. It is notable that these ZAB characteristics are comparable to Pt/C, the state-of-the-art catalyst as of now. N-CuS may be a viable replacement for the Pt/C electrode, resulting in the cost-saving effect. The cycling stability of both N-CuS and Pt/C-based ZAB has been assessed to show that N-CuS-based ZAB has much prolonged (more than twice the cycles) cyclability compared to Pt/C-based ZAB (Fig. S11).Additionally, ZAB constructed using N-CuS can operate in oxygen-deficient environments. As the counter reaction it utilizes redox reaction of copper oxides (Zn-Cu mode) in the substrate when operating in anaerobic conditions. The reduction of divalent and monovalent copper oxides appears as plateaus at 1.1 V and 0.8 V versus the zinc anode during GCPL. Due to this alternate reaction, the cell can operate even at low concentrations of oxygen or even in its absence.DFT calculations have been performed to elucidate the reaction mechanism and the intrinsic catalytic activity of the material, and shows nitrogen dopants improve reactivity of the active sites, thus reducing the overpotential.In summary, we have synthesized N-CuS as the OER/ORR catalyst for ZAB. Through anodization the catalyst was directly grown on the substrate and nitrogen plasma treatment further enhances the catalyst properties to render it higher surface area, conductivity, and better stability. This allows better reversibility in the OER/ORR and results in enhanced cyclability of the overall cell. The constructed RZAB exhibited high specific capacity of 789.3 mA·h·g-1, which, has higher capacity than the analogue using Pt/C catalyst. In addition, N-CuS based RZAB is capable of operating under oxygen-deficient conditions utilizing the metal oxide substrate. This allows the dual mode operation of zinc-air and zinc-copper modes, and results in a more consistent output from the RZAB, as short-term air supply issues could be buffered by this effect. Figure 1

Study of dielectric properties of polymer/air plasma treated graphene oxide nanocomposites for electronic applications

In the present study we emphasized on the dielectric properties of Ethylene Vinyl Acetate (EVA) filled with untreated and plasma-treated graphene oxide (GO). The chemical fingerprints of EVA/GO were analysed using FTIR. Decreased ID/IG ratio from 2.99 to 2.75 and 1.60 to 1.16 due to exposed plasma was confirmed by Raman spectroscopy. X-ray diffraction (XRD) disclosed the decreased degree of crystallinity. Electric properties were measured by impedance analyser, dielectric constant was increased upto 11% for untreated GO dispersion and 47% for Air treated Plasma GO dispersed EVA composites. Plasma treatment further improved the exfoliated sites of GO and induced the defects, leading to optimized dielectric properties. Improved dielectric properties of EVA/GO can provide valuable insights into the potential applications in the field of electrical connectors, film capacitors, and pseudo capacitors.

Surface modification for steel rods based on atmospheric-pressure nitrogen plasma treatment at room temperature

A surface modification process for steel rods based on atmospheric-pressure nitrogen plasma (APP) at room temperature was developed. Steel rods were irradiated with APP generated by dielectric-barrier discharge in a nitrogen atmosphere. Elemental analysis using an electron-probe microanalyzer revealed strong nitrogen signals at the top surface, which suggests the formation of a modified layer due to the generation of excited nitrogen sources by APP. However, no noticeable nitrogen diffusion into the steel was observed. This is because the excited nitrogen sources reacted with elemental iron emitted by APP and nitrides were deposited on the surface of the steel. The proposed APP treatment is a promising approach for modifying the surface of steel rods without heat treatment.

Peroxiredoxin 1 modulates oxidative stress resistance and cell apoptosis through stemness in liver cancer under non-thermal plasma treatment

The role of peroxiredoxin 1 (PRDX1), a crucial enzyme that reduces reactive oxygen and nitrogen species levels in HepG2 human hepatocellular carcinoma (HCC) cells, in the regulation of HCC cell stemness under oxidative stress and the underlying mechanisms remain largely unexplored. Here, we investigated the therapeutic potential of non-thermal plasma in targeting cancer stem cells (CSCs) in HCC, focusing on the mechanisms of resistance to oxidative stress and the role of PRDX1. By simulating oxidative stress conditions using the plasma-activated medium, we found that a reduction in PRDX1 levels resulted in a considerable increase in HepG2 cell apoptosis, suggesting that PRDX1 plays a key role in oxidative stress defense mechanisms in CSCs. Furthermore, we found that HepG2 cells had higher spheroid formation capability and increased levels of stem cell markers (CD133, c-Myc, and OCT-4), indicating strong stemness. Interestingly, PRDX1 expression was notably higher in HepG2 cells than in other HCC cell types such as Hep3B and Huh7 cells, whereas the expression levels of other PRDX family proteins (PRDX 2–6) were relatively consistent. The inhibition of PRDX1 expression and peroxidase activity by conoidin A resulted in markedly reduced stemness traits and increased cell death rate. Furthermore, in a xenograft mouse model, PRDX1 downregulation considerably inhibited the formation of solid tumors after plasma-activated medium (PAM) treatment. These findings underscore the critical role of PRDX 1 in regulating stemness and apoptosis in HCC cells under oxidative stress, highlighting PRDX1 as a promising therapeutic target for NTP-based treatment in HCC.

Influence of pre-treatment with non-thermal atmospheric pressure plasma on bond strength of TP340 titanium-PEEK direct bonding

Direct bonding of a TP340 titanium to PEEK by hot pressing via pre-treatment of non-thermal atmospheric pressure plasma jet has been demonstrated. The plasma irradiation effect on the bonding surface on the bond strength after hot pressing was investigated. The tensile shear strength of TP340-PEEK joined by hot pressing after plasma pre-treatment was measured by comparing specimens bonded using conventional hot pressing and those bonded using adhesives. The plasma treatment to the TP340 side resulted in the formation of TiO2, which is chemically fed to oxide formation due to the irradiation of oxygen radicals generated by the plasma, resulting in a bond strength of less than 1 MPa, similar to the bond strength of the untreated specimens. The plasma irradiation effect on the PEEK side on the bond strength of TP340-PEEK bonded samples was also investigated. The bonding strength was increased by plasma irradiation to PEEK. As the plasma irradiation time was increased, the bonding strength gradually increased to 9.2 MPa, which is about 19 times higher than the bonding strength without plasma irradiation. These results suggest that oxygen radicals in the atmospheric pressure RF plasma jet produced oxygen-containing surface functional groups on the PEEK surface, which increased the strength of the TP340-PEEK direct joining.

Comprehensive Review on the Impact of Chemical Composition, Plasma Treatment, and Vacuum Ultraviolet (VUV) Irradiation on the Electrical Properties of Organosilicate Films.

Organosilicate glass (OSG) films are a critical component in modern electronic devices, with their electrical properties playing a crucial role in device performance. This comprehensive review systematically examines the influence of chemical composition, vacuum ultraviolet (VUV) irradiation, and plasma treatment on the electrical properties of these films. Through an extensive survey of literature and experimental findings, we elucidate the intricate interplay between these factors and the resulting alterations in electrical conductivity, dielectric constant, and breakdown strength of OSG films. Key focus areas include the impact of diverse organic moieties incorporated into the silica matrix, the effects of VUV irradiation on film properties, and the modifications induced by various plasma treatment techniques. Furthermore, the underlying mechanisms governing these phenomena are discussed, shedding light on the complex molecular interactions and structural rearrangements occurring within OSG films under different environmental conditions. It is shown that phonon-assisted electron tunneling between adjacent neutral traps provides a more accurate description of charge transport in OSG low-k materials compared to the previously reported Fowler-Nordheim mechanism. Additionally, the quality of low-k materials significantly influences the behavior of leakage currents. Materials retaining residual porogens or adsorbed water on pore walls show electrical conductivity directly correlated with pore surface area and porosity. Conversely, porogen-free materials, developed by Urbanowicz, exhibit leakage currents that are independent of porosity. This underscores the critical importance of considering internal defects such as oxygen-deficient centers (ODC) or similar entities in understanding the electrical properties of these materials.

Guided Plasma Application in Dentistry-An Alternative to Antibiotic Therapy.

Cold atmospheric plasma (CAP) is a promising alternative to antibiotics and chemical substances in dentistry that can reduce the risk of unwanted side effects and bacterial resistance. AmbiJet is a device that can ignite and deliver plasma directly to the site of action for maximum effectiveness. The aim of the study was to investigate its antimicrobial efficacy and the possible development of bacterial resistance. The antimicrobial effect of the plasma was tested under aerobic and anaerobic conditions on bacteria (five aerobic, three anaerobic (Gram +/-)) that are relevant in dentistry. The application times varied from 1 to 7 min. Possible bacterial resistance was evaluated by repeated plasma applications (10 times in 50 days). A possible increase in temperature was measured. Plasma effectively killed 106 seeded aerobic and anaerobic bacteria after an application time of 1 min per 10 mm2. Neither the development of resistance nor an increase in temperature above 40 °C was observed, so patient discomfort can be ruled out. The plasma treatment proved to be effective under anaerobic conditions, so the influence of ROS can be questioned. Our results show that AmbiJet efficiently eliminates pathogenic oral bacteria. Therefore, it can be advocated for clinical therapeutic use.

Protein-losing enteropathy as a new phenotype in atypical hemolytic uremic syndrome caused by CD46 gene mutation.

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy. Genetic defects in the alternative complement (AP) pathway have been identified in 60-70% of individuals. Eculizumab is recommended as a first-line therapy. We collected the clinical data of a pediatric patient with aHUS accompanied by protein-losing enteropathy (PLE). Genetic testing was performed. Related literature on aHUS combined with PLE was reviewed. A 15-year-old Chinese girl was diagnosed with aHUS at 3.7years of age and experienced five episodes; her symptoms completely resolved with plasma treatment. Severe gastrointestinal symptoms and hypoalbuminemia presented after the first episode, and PLE was diagnosed. A novel homozygous CD46 variant was identified, and FACS revealed significantly decreased CD46 expression. She presented at a recent relapse with persistent GI symptoms and headache and progressed to chronic kidney failure; peritoneal dialysis was initiated. Eculizumab was given 8months after the last recurrence. Surprisingly, PLE was cured. Afterward, dialysis was discontinued, and eGFR recovered to 44.8ml/min/1.73 m2. A review of the literature indicated that PLE with thrombosis was caused by CD55 variants via hyperactivation of the AP system. We report an aHUS patient with PLE caused by CD46 variants. Symptoms of both PLE and aHUS were significantly alleviated in our patient and patients with CD55 variants treated with eculizumab, indicating that PLE was a new symptom of aHUS in our patient with a CD46 variant. Our case expands the phenotype of aHUS caused by a CD46 mutation and provides evidence of the efficacy of eculizumab after a long phase of chronic kidney failure.

Lignosulfonate-derived porous carbon via self-activation for supercapacitor electrodes

This research aims to contribute to promoting a circular economy for technical lignin derived from the pulp and paper industry and developing sustainable and environmentally friendly energy storage solutions. Lignosulfonate was used as a precursor, and a three-stage carbonization method was employed to produce the electrode material. Porous carbon was successfully prepared through a self-activation process without the use of any activating agents. The resulting porous carbon was subjected to plasma treatment and screen printing, and assembled into a supercapacitor with a PVA/H2SO4 gel electrolyte. The results showed that carbonizing temperature at 1000°C boasts the highest specific surface area of 531.158 m2/g, a maximum area capacitance of 308.21 mF/cm2, the highest energy density of 27.39 μWh/cm2, and the power density of 0.0665 mW/cm2. These impressive results demonstrate the successful development of a lignosulfonate-based supercapacitor using a clean manufacturing process. This achievement can promote the high-value applications of technical lignin.

Interface Engineering Induced Multi-Scale Self-Assembly NiFe-LDH Heterostructures for High-Performance Water Electrolysis.

Confronted with the pressing issue of energy scarcity, the development of an economical and potent bifunctional catalyst is of paramount importance. We adopt an interface engineering strategy to modify the surface of NiFe-LDH nanoplates with O2 plasma treatment. This process enhances the local electric field of NiFe-LDH, resulting in the formation of a self-assembled polycrystalline nanowire array on the nanoplate surface. After O2 plasma treatment for 30 min, the NiFe-LDH-P30 not only formed a heterostructure with rough surface, but also regulated the exposure of crystal surfaces. Due to the strong interface coupling between the self-assembled 3D nanoflowers, 2D nanoplates and 1D nanowires, the NiFe-LDH-P30 exhibits an excellent structural stability. Moreover, it demonstrated exceptional HER and OER activities in alkaline condition, achieving a low overpotentials of 154 mV and 242 mV at 10 mA cm-2, respectively. Furthermore, NiFe-LDH-P30 as the dual-electrode material for the cathode and anode in the process of water splitting results in a low voltage of 1.63 V at a current density of 10 mA cm-2. Through the strategic application of interface engineering, this work has pioneered a novel approach to the creation of transition metal-based electrocatalysts, which is benefit to a range of practical energy applications.

Cold Plasma for the Modification of the Surface Roughness of Microparticles.

Cold plasma treatment is commonly used for sterilization. However, another potential of cold plasma treatment is surface modification. To date, several efforts have been directed toward investigating the effect of cold plasma treatment in modifying the surfaces of films. Here, the impact of suspension properties and parameters of cold plasma treatment on the changes of surfaces of monodisperse polymeric microparticles is tested. The plasma treatment did not touch the surface chemistry of the monodisperse polymeric microparticles. The concentration of suspensions of 1 mg/mL was determined to relate to a stronger effect of the plasma treatment on the roughness of the microparticles. Microparticles with an average diameter of 20 μm show a roughness increase with the plasma treatment time. However, a plasma treatment time longer than 15 min damages the microparticles, as observed in particles with an average diameter of 20 and 50 μm. We finally prototyped monodisperse microparticles to deliver drugs to the nasal mucosa by studying the effect of roughness in their (undesired) self-adhesion and (desired) adhesion with tissue. A moderate roughness, with an average peak-to-valley distance of 500 nm, appears to be the most effective in reducing the detachment forces with nasal tissue by up to 5 mN.

Hydrogen permselective membrane prepared by plasma treatment of porous ceramic substrates

Abstract Demand for hydrogen is increasing as we move toward a decarbonized society. Membrane separation methods have attracted attention as a way to reduce the cost of hydrogen production. In this study, we focused on boron nitride (BN) as a chemically stable porous substrate material. CVD treatment at 250°C has been investigated for porous BN, but selectivity did not develop. Therefore, we focused on atmospheric pressure plasma as a treatment method. The objective of this study is to develop a membrane with high hydrogen selective permeance by immersion in silicon alkoxide after plasma treatment. After plasma treatment for 100 s, the H2 permeance was 3.52×10−6 [mol m−2 s−1 Pa−1] and the H2/N2 permeance ratio was 18.25. Since molecular hydrogen can pass between the BN crystal faces, it is considered that silica reacted with the hydroxy groups formed on BN by plasma treatment and blocked the space between crystals. Therefore, it is suggested that the performance of the separation membrane changes depending on the number and distribution of hydroxyl groups by plasma treatment, and further stabilization is needed.

Impact of plasma-modified pretreatment on the tensile properties of carbon fiber-reinforced epoxy composites

Abstract Low-temperature jet plasma modification technology is a surface treatment method designed to enhance the surface properties of materials without causing severe thermal damage. This technique modifies surface characteristics by creating plasma and utilizing ions and reactive groups within the plasma to chemically interact with the material’s surface. In this study, surface modification of carbon fibers was carried out by using low-temperature jet mixed oxygen plasma technology at treatment speeds of 25 mm/s, 50 mm/s, 100 mm/s, and 200 mm/s. Following the modification process, carbon fiber-reinforced epoxy composites were fabricated by using a hand-lay-up technique. Subsequently, the tensile properties of the carbon fiber composites were tested to evaluate the impact of the plasma treatment on their mechanical performance. The experimental results demonstrated a significant enhancement in the tensile properties of the composites when the carbon fibers were pretreated at a rate of 50 mm/s. This enhancement was evidenced by an impressive increase of 82.38% in tensile strength and 30.96% in tensile modulus compared to untreated samples. This signifies that low-temperature plasma treatment has a beneficial effect on enhancing the surface properties of carbon fibers and improving the performance of composites. This finding provides substantial support for the extensive application of carbon fiber composites.

Rapid susceptibility of Carbapenem resistant Pseudomonas aeruginosa and its resistance gene to non-thermal plasma treatment in a batch reactor

The critically ranked carbapenem-resistant Pseudomonas aeruginosa has been observed to infect immunocompromised patients that consume polluted waters, leading to critical infections and more hospital costs. To save lives and unburden the public health sectors of preventable costs, non-thermal plasma (NTP) technology was investigated as an alternative disinfection step that could be applied in wastewater treatment plants (WWTPs) to inactivate this bacterium and its prominent carbapenem resistance gene (blaNDM-1). Culture and molecular-based techniques were employed to confirm carbapenem resistance in P. aeruginosa (27853). Culture suspensions of carbapenem-resistant ATCC P. aeruginosa (16 h culture) were prepared from confirmed isolates and subjected to plasma treatment at varying time intervals (3 min, 6 min, 9 min, 12 min and 15 min) in triplicates. The plasma treated samples were evaluated for re-growth and the presence of blaNDM-1. The treatment resulted in a 0.68 log reduction after 3 min and the highest log reduction of ≥8 after 12 min, suggesting that plasma disinfection has a great potential to be an efficient tertiary treatment step for WWTPs. Moreover, the gel image showed that band intensity of blaNDM-1 reduced with treatment time, thereby suggesting a probable reduction of amplified genes. Notwithstanding, longer treatment time, a grounded electrode with a larger surface (≥ 40 mm diameter) and/or oxygen-containing feeding gas is warranted to completely inactivate its antibiotic resistance gene (ARG), which might be bound by biofilms as they seem to protect P. aeruginosa from the action of non-thermal plasma (NTP) disinfection.

Influence of plasma synthesis parameters on the magnetic, structural and photocatalytic properties of copper ferrite

CuFe2O4 cubic copper ferrite nanoparticles were synthesized by a new plasma method, the advantage of which is the short duration of processing and cost-effectiveness. To select optimal synthesis conditions, central compositional rotatable experimental planning was used. Using the methods of X-ray phase analysis, vibration magnetometry, electron microscopy, and UV spectroscopy, the sizes of crystallites, the intensity of peaks in X-ray diffraction patterns, dislocation density, saturation magnetization, coercive force, and the degree of degradation of 4-nitrophenol were determined. To study the effect of pH on the composition of the resulting copper ferrites, cyclic voltammetry was used. The kinetics of the ferritization process under the influence of a plasma discharge has also been studied. A mechanism for ferritization in the Cu2+-Fe2+-SO42--OH- system has been proposed.It was found that single-phase nanodispersed powders of cubic copper ferrites with a saturation magnetization Ms 78–93 Emu/g can be obtained by plasma treatment at 300 s and pH 12. Copper ferrite with an admixture of Cu2O is formed at pH = 8.The maximum values of the coercive force correspond to regimes in which the minimum dislocation density is observed. The saturation magnetization depends on the crystallite size. The crystallite size of the resulting powders is in the range of 225–500 A. The results showed that the processing time is the parameter that has the greatest impact on the structural and magnetic characteristics of copper ferrite; the pH of the reaction medium affects them to a lesser extent.

Surface treatment of artificial implants with hybrid nanolayers: results of antibacterial tests, leachates and scanning electron microscope analysis.

The aim of this study was to evaluate the antibacterial efficacy of surface-treated hernia implants modified by a hybrid nanolayer with incorporated Ag, Cu, and Zn cations using the sol-gel method. The materials (polypropylene, polyester, and polyvinylidene difluoride) were activated by vacuum plasma treatment or UV C radiation, then modified and tested for bacterial strains of Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive). The AATCC 100 (2019) method for quantitative and the ISO 20645 agar plate propagation method for qualitative evaluation of microbiological efficacy were used. The gradual release of incorporated ions was monitored over time in simulated body fluids (blood plasma, peritoneal fluid) and physiological saline using an inductively coupled plasma mass spectrometer. The thickness and the homogeneity of the layers were measured for individual random samples with scanning electron microscope analysis (SEMA) and evaluated with an elemental analysis. Qualitative and quantitative microbiological tests clearly show the great suitability of vacuum plasma and UV C with sol AD30 (dilution 1:1) surface treatment of the implants. The absolute concentration of Ag, Cu, and Zn cations in leachates was very low. SEMA showed a high degree of homogeneity of the layer and only very rare nanocracks by all tested materials appear after mechanical stress. This study confirms that surface treatment of meshes using the sol-gel method significantly increases the antibacterial properties. The nanolayers are sufficiently mechanically resistant and stable and pose no threat to health.