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Perfluorooctanoic acid (PFOA) contamination in water sources poses significant environmental and health concerns. The kinetic, equilibrium, and thermodynamic features of PFOA adsorption in the existence of natural organic matter (NOM) were thoroughly investigated in this work using granular activated carbon (GAC) modified by dielectric barrier discharge (DBD) plasma. The impacts of DBD plasma parameters on the adsorption process were systematically examined. The results demonstrated that GAC modified by DBD plasma exhibited enhanced adsorption performance for PFOA, even in the presence of NOM. The optimal condition for plasma-treated GAC was achieved with 20 min of plasma treatment time and 100 W of plasma power, resulting in 92% PFOA removal efficiency in deionized water (DIW) and 97% removal efficiency in Chao Phraya River water (CPRW). A kinetic investigation using the pseudo-first-order model (PFOM), the pseudo-second-order model (PSOM), and the Elovich model (EM) indicated that plasma treatment time and NOM presence influenced the adsorption capacity and rate constants of PFOA with the PSOM having emerged as the most fitting kinetic model. The Langmuir isotherm model indicates monolayer adsorption of PFOA on plasma-treated GAC, with higher maximum adsorption capacity while NOM is present. The Redlich–Peterson and Sips isotherm models indicated varying adsorption capacity and heterogeneity in the adsorption system. The Sips model was determined as the most fitting isotherm model. Furthermore, the favorable and spontaneous character of PFOA adsorption onto plasma-treated GAC was validated by thermodynamic analysis, with endothermic heat absorption during the process. Overall, this comprehensive investigation provides valuable insights into the adsorption characteristics of PFOA in the existence of NOM using GAC modified by DBD plasma. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge (DBD) plasma surface modification has certain aging effect. This article studies the aging effect of plasma (DBD) on the surface modification of carbon fibers. The test results show that plasma (DBD) treatment reduces the impurity particles on the surface of carbon fibers and makes the surface texture coarser. In addition, there is no significant change. After plasma (DBD) treatment, the content of C–O–C, C–O and C=O on the surface of carbon fibers increased from 3.20%, 7.76% and 1.64% to 7.06%, 21.50 and 6.08%, respectively. This is due to the high-energy particle bombardment of the fiber surface, which forms activated carbon atoms on the surface. The free electrons of these activated carbon atoms combine with ionized oxygen in the air. However, with the passage of time, the content of C–O–C, C–O and C=O gradually decreases to 3.31%, 8.57% and 1.77%, respectively. This is because some functional groups formed on the treated carbon fiber surface are not firmly bound, and some of these functional groups containing O2 groups will combine with surrounding substances through irreversible chemical oxidation reactions to produce CO2, which leaves the carbon fiber surface as a gas. The treated carbon fibers will immediately become hydrophilic, and the water contact angle decreases from 148.71° to 0°. With the passage of time, the water contact angle gradually increases to 118.16°, and the hydrophobicity recovers. [ABSTRACT FROM AUTHOR]

Perfluorooctanoic acid (PFOA) contamination in water sources poses significant environmental and health concerns. The kinetic, equilibrium, and thermodynamic features of PFOA adsorption in the existence of natural organic matter (NOM) were thoroughly investigated in this work using granular activated carbon (GAC) modified by dielectric barrier discharge (DBD) plasma. The impacts of DBD plasma parameters on the adsorption process were systematically examined. The results demonstrated that GAC modified by DBD plasma exhibited enhanced adsorption performance for PFOA, even in the presence of NOM. The optimal condition for plasma-treated GAC was achieved with 20 min of plasma treatment time and 100 W of plasma power, resulting in 92% PFOA removal efficiency in deionized water (DIW) and 97% removal efficiency in Chao Phraya River water (CPRW). A kinetic investigation using the pseudo-first-order model (PFOM), the pseudo-second-order model (PSOM), and the Elovich model (EM) indicated that plasma treatment time and NOM presence influenced the adsorption capacity and rate constants of PFOA with the PSOM having emerged as the most fitting kinetic model. The Langmuir isotherm model indicates monolayer adsorption of PFOA on plasma-treated GAC, with higher maximum adsorption capacity while NOM is present. The Redlich–Peterson and Sips isotherm models indicated varying adsorption capacity and heterogeneity in the adsorption system. The Sips model was determined as the most fitting isotherm model. Furthermore, the favorable and spontaneous character of PFOA adsorption onto plasma-treated GAC was validated by thermodynamic analysis, with endothermic heat absorption during the process. Overall, this comprehensive investigation provides valuable insights into the adsorption characteristics of PFOA in the existence of NOM using GAC modified by DBD plasma.

The effect of argon (Ar) and oxygen (O2) gases as well as the treatment times on the properties of modified bamboo fibers using dielectric barrier discharge (DBD) plasma at generated power of 180 W were investigated. The plasma treatment of bamboo fibers with inert gases leads to the generation of ions and radicals on the fiber surface. Fourier transform-infrared spectroscopy (FTIR) confirmed that the functional groups of lignin and hemicellulose were reduced owing to the removal of the amorphous portion of the fibers by plasma etching. X-ray diffraction analysis (XRD) results in an increased crystallinity percentage. X-ray photoelectron spectroscopy (XPS) results showed the oxygen/carbon (O/C) atomic concentration ratio increased with increasing treatment time. The fiber weight loss percentage increased with increased treatment time. Scanning electron microscopy (SEM) images showed that partial etching of the fiber surface led to a higher surface roughness and area and that the Ar + O2 gas plasma treatment provided more surface etching than the Ar gas treatment because of the oxidation reaction of the O2 plasma. The mechanical properties of fiber-reinforced epoxy (FRE) matrix composites revealed that the F(tr)RE-Ar (30) samples showed a high tensile strength, whereas the mechanical properties of the F(tr)RE-Ar + O2 sample decreased with increased treatment time. [ABSTRACT FROM AUTHOR]

This paper reports the use of dielectric barrier discharge (15.65 kV, 50 Hz) produced in an air and argon environment at atmospheric pressure to modify the surface of Nylon 6. Power dissipation in air and argon DBD was determined to be 14.60 W and 12.00 W, respectively. Similarly, the average density and temperature of an electron in air DBD were found to be 1.74 ×1011 cm-3 and 1.31 eV, respectively, while the values were 2.50 ×1011 cm-3 and 0.68 eV in argon DBD. The water contact angle (WCA) was measured to confirm the enhancement in wettability. On treating the sample with air DBD for 15 minutes, the contact angle reduced from 134.07° ± 3.20° to 89.11° ± 3.06° while it was reduced to 82.74° ± 4.20° within 1 minute using argon. The study found that treating a hydrophobic sample of Nylon 6 with DBD for a certain period of time transformed it into a hydrophilic one, and extending the treatment time further enhanced its wettability. The use of argon DBD was found to be more effective than air DBD in altering the surface properties of the sample, as the sample became hydrophilic after only one minute of treatment with argon DBD and completely wettable after three minutes. The findings suggest that air and argon DBD have potential applications in modifying the surface properties of Nylon 6, which could have practical implications in the production of textiles, membranes, and other materials.

Perfluorooctanoic acid (PFOA), a widely used perfluorinated alkyl substance (PFAS), poses significant environmental and health risks. This study investigates PFOA adsorption in the existence of natural organic matter (NOM) using granular activated carbon (GAC) modified with dielectric barrier discharge (DBD) plasma. PFOA’s amphiphilic structure, characterized by a hydrophilic carboxyl group head and a hydrophobic perfluorinated tail, contributes to its versatility and persistence. The selection of the Chao Phraya River (CPR) water as the NOM source, captures the complexity of a major water body subjected to diverse pollution sources. The results were analyzed through the Toth and Temkin isotherm models. Application of the Toth isotherm model reveals enhanced PFOA adsorption capacity in CPR water compared to DI water, emphasizing the influence of NOM. The Temkin isotherm analysis further characterizes the strength and efficiency of the adsorption process, highlighting a stronger interaction between PFOA and plasma-modified GAC in CPR water. The study indicates that the adsorption process in CPR water may be more influenced by PFOA surface coverage on the GAC surface in the presence of NOM. Overall, this research contributes valuable insights into pollutant removal strategies, highlighting the potential of DBD plasma-modified GAC in addressing PFOA contamination challenges in water systems.

A hybrid dielectric barrier discharge (DBD) plasma‐catalysis system is an effective way to catalyze the conversion of small molecules such as carbon dioxide. Until now, ABO3 perovskite catalyst used for CO2 hydrogenation to light hydrocarbons reaction has been rarely reported. Herein, the lanthanum nickel perovskite‐type catalysts named as La0.8A'0.2NiO3±δ (A' represents for Ca, Ce, Pr, Sr) are prepared by a modified nitrate citric acid method, and the influence of A‐site substitution on catalytic performance is investigated. The reactivity results show that the substitution of A‐site can improve CO2 conversion and C2–4 (hydrocarbons containing C2–C4) selectivity in varying degrees. Compared to LaNiO3 catalyst, the La0.8Ca0.2NiO3±δ catalyst has CO2 conversion increased from 72.6% to 82.3%, and C2–4 selectivity from 5.8% to 8.5%. The superior performance can be put down to the formation of smaller Ni particle size on La0.8Ca0.2NiO3±δ catalyst, which promotes the activation of H2. Additionally, the sufficient oxygen vacancies on La0.8Ca0.2NiO3±δ provide more active sites for CO2 adsorption and then enhance CO2 conversion. The hybrid DBD plasma‐catalysis system is proved effective for CO2 hydrogenation, and the idea of using A‐site substitution would serve as a guide for the modification of perovskite‐type ABO3 catalysts. [ABSTRACT FROM AUTHOR]

The effect of argon (Ar) and oxygen (O2) gases as well as the treatment times on the properties of modified bamboo fibers using dielectric barrier discharge (DBD) plasma at generated power of 180 W were investigated. The plasma treatment of bamboo fibers with inert gases leads to the generation of ions and radicals on the fiber surface. Fourier transform-infrared spectroscopy (FTIR) confirmed that the functional groups of lignin and hemicellulose were reduced owing to the removal of the amorphous portion of the fibers by plasma etching. X-ray diffraction analysis (XRD) results in an increased crystallinity percentage. X-ray photoelectron spectroscopy (XPS) results showed the oxygen/carbon (O/C) atomic concentration ratio increased with increasing treatment time. The fiber weight loss percentage increased with increased treatment time. Scanning electron microscopy (SEM) images showed that partial etching of the fiber surface led to a higher surface roughness and area and that the Ar + O2 gas plasma treatment provided more surface etching than the Ar gas treatment because of the oxidation reaction of the O2 plasma. The mechanical properties of fiber-reinforced epoxy (FRE) matrix composites revealed that the F(tr)RE-Ar (30) samples showed a high tensile strength, whereas the mechanical properties of the F(tr)RE-Ar + O2 sample decreased with increased treatment time.

In this study, we investigated the decomposition characteristics of n-hexane by a dielectric barrier discharge (DBD) plasma. In order to accomplish this, the factors influencing these decomposition characteristics such as background gases (air, N2, and He), residence time (1–10 s), initial n-hexane concentration (10–50 ppm), relative humidity (2.5%, 40%, and 70%), and power (50–80 W) were evaluated. As a result, the decomposition efficiency of n-hexane at N2 atmosphere was found to be lower than those at air and He atmosphere. The removal efficiency of n-hexane was increased when the residence time, relative humidity, and power increased, and when the initial concentration decreased. The concentrations of CO, CO2, and aerosol increased as the specific energy density increased. However, the O3 level increased up to a certain point, then decreased. Various hydrocarbons such as acetone, pentanal, nonanal, etc. were also detected as by-products and their decomposition and recombination pathways were suggested. [ABSTRACT FROM AUTHOR]

This work develops a tube-based dielectric barrier discharge (DBD) plasma treatment for improving the performance of the slippery coating layers on medical catheters. The raw materials of the polymer catheters usually exhibit hydrophobic surface property and need a hydrophilic slippery coating layer for reducing the friction during catheter insertion. However, the high friction force may cause an uncomfortable feeling or even the infective or thrombosis injuries on the epithelium. This study develops an atmospheric tube-based DBD plasma for treating the surface of the plastic catheter for enhancing the coating performance of the slippery layer coating on medical catheters. The tube-based DBD plasma system is a semiclose and co-axial concentric circles system composed of a glass tube as the DBD layer and the inner supporting hook for catheter production as the center electrode for DBD discharges. The treatment for the inner and outer catheter tube can be achieved simultaneously with a small carrier flow rate of 30–100 sccm. Results show that the contact angles of these catheter tubes are significantly reduced after plasma treatment and the hydrophilicity of the treated surface maintains 57% for more than 30 min after the treatments. The catheters with different plasma treatments are coated with the commercial slippery layer and tested the kinetic friction under the ASTM D1894 standard. The kinetic friction test indicates that the catheters with plasma treatment exhibit lower kinetic friction force, indicating that lower friction during catheter medical insertion operations. The experimental results have shown that the medical catheter treated by the developed tube-based DBD plasma can be effectively modified and facilitated in the subsequent coating process. [ABSTRACT FROM AUTHOR]

The experimental results of dielectric barrier discharge (DBD) plasma treatment on barley (Hordeum Valgare L cv. Yusef) seed germination and seedling growth are analyzed and presented. The seeds were exposed to DBD plasma with 40-, 80-, and 120-W powers for 15 s. All treatments showed positive effects on seed germination, seedling growth, and vigor index. The scanning electron microscope (SEM) images and water imbibition evaluations of plasma-treated seeds revealed that the treatments improved water absorption in the seeds. Similar positive improvements were observed for the plasma-treated seeds in the seedling stage. The best germination characteristics were obtained in 80-W DBD plasma, which included an 18.28% increment in total germination percentage, and 13.35%, 66.83%, 38.55%, and 31.93% increment on the seed germination potential, vigor index, shoot height, and root length, respectively. Moreover, the seed germination of the plasma-treated barley was studied after 2, 7, 14, and 30 days of storage, which indicated the desirable effect of plasma over the storage time. It is concluded that the use of cold plasma can significantly improve the germination and seedling growth of barley seeds. [ABSTRACT FROM AUTHOR]

Tetracycline is one of the widely used antibiotic drugs, but it also causes severe water pollution. This research applied a pulsed dielectric barrier discharge (DBD) plasma reactor of coaxial configuration with a screw-type high-voltage electrode to treat tetracycline in an aqueous solution, which was recycled to flow over the surface of the inner electrode. The effects of discharge voltage, initial concentration, and pH value of tetracycline on the degradation efficiency, total organic carbon (TOC) removal rate, kinetic rate constant (${k}$), and energy efficiency were investigated. The results show that 92.3% degradation efficiency and 65.01% TOC removal rate of tetracycline were achieved at the initial concentration of 50 mg/L, corresponding to the energy efficiency of 20.24 g/(kW $\cdot \text{h}$). The tetracycline degradation efficiencies were dependent on the initial concentration from 5 to 75 mg/L, which led to the decrease of the degradation kinetic rate constant from 0.518 to 0.077 min $^{-1}$. The TOC removal rate of tetracycline was strongly enhanced at higher pH values from 1.5 to 10.5, with the optimum value at 7.5. The intermediate products of tetracycline produced by the plasma treatment were analyzed by liquid chromatography mass spectrometry (LC-MS), which show that the aromatic ring, amino group, and the double bonds were mainly attacked by the hydroxyl radical and other reactive oxygen species. A possible degradation pathway has also been proposed. [ABSTRACT FROM AUTHOR]

This paper studies the efficacy of a dielectric barrier discharge (DBD) plasma generator with circular and square electrodes with stainless steel and copper materials in the reduction of microbial contamination in herbs. Four types of electrodes are used: copper and stainless-steel square electrodes of the size 110×110 mm² and circular electrodes with a 94 mm diameter. The voltage supplied to plasma generator varies between 5 - 15 kV and the frequency is between 1 - 7 kHz. Licorice (Glycyrrhiza glabra Linn.) and sappan tree (Ceasalpinia sappan Linn.) herb powders were packed in polyethylene bags of the size 89×89 mm² and tested for microbial contamination before and after the plasma irradiation. The samples were treated with plasma for 5, 10, 15, 20, 25 and 30 min. The results indicated that plasma treatment of 30 min is the most effective time for reducing in the aerobic plate count and yeast and mold count of licorice herb powder. This plasma treatment condition effectively reduced initial the aerobic plate count and yeast and mold count from 8.00×104 to 1.30×10³ CFU/g and 4.20×10² to 8.0×10 CFU/g, respectively. Escherichia coli were not founded in the control sample and plasma treatment samples (MPN/g < 3.0). The results revealed that plasma treatment reduced microbial contamination to acceptable levels in herb seasoning as indicated in TCP 1380/2550. In sappan tree powder, plasma irradiation also effectively reduced artificially contaminated of Bacillus subtilis in sappan herb. [ABSTRACT FROM AUTHOR]

To improve resin efficiency in plywood production, the veneer surface was modified by dielectric barrier discharge (DBD) plasma and the resin was applied by air spray atomization. The droplet size and coverage of resin droplets were evaluated by image analysis. This novel approach improved the resin efficiency. The shear strength of the produced plywood was improved along with a higher gluing speed. The surface energy of poplar veneer altered after plasma treatment, resulting in an increased size of resin droplets and increased resin coverage. Plywood produced at a plasma-processing power of 4.5 kW exhibited the highest shear strength and a 6 kW plasma-processing power did not bring about advantages. Under these circumstances, the lowest amount of resin necessary for fabricating quality products can be reduced to 50 g m−2. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge (DBD) plasma at atmospheric pressure in air was applied to a poplar veneer surface. Effects of plasma processing rate on surface morphology, chemical property, and surface wettability of the poplar veneer were investigated. The adhesion strength of urea formaldehyde (UF) glued plywood manufactured from the modified veneer was also studied. Atomic force microscopy (AFM), electron spin-resonance spectroscopy (ESR), X-ray photoelectron spectroscopy (XPS), contact angle tests, and shear strength tests were carried out. AFM indicated that the surface roughness increased after plasma treatment and was the maximum at a processing rate of 14 m/min. Both ESR and XPS tests showed more oxygen accumulation on the wood surface, forming various oxygen-containing chemical groups. Contact angle tests showed better wetting at a decreased plasma processing rate. Consequently, the adhesion strength of plywood increased after plasma treatment and showed higher strength at lower processing rates.

Magnetic pulse compression (MPC) systems are suitable for generating dielectric barrier discharges (DBDs) owing to their capability of producing high-amplitude, short pulse voltage waves. This paper proposes a high-frequency, bipolar magnetic compression system to study DBD plasma characteristics. First, the principle of bipolar MPC is explained [a bipolar MPC system comprises a full bridge inverter circuit, pulse transformer (PT), and magnetic switch (MS)]. Additionally, the design of the PT and MS is described. Then, the waveform of the resistive load is tested and compared with PSpice simulation results. It was found that the nanosecond pulse generator produces a pulse on a resistor with an amplitude of 0–13 kV, a rise time of approximately 100 ns, and a repetition frequency of 0 to several kHz. Finally, this paper studies the plasma characteristics under the application of a high-frequency bipolar pulse, and the charge–voltage Lissajous figure of the discharge waveform is analyzed. Combining discharge photographs and theoretical calculation results yields the relationship between the discharge characteristics and the frequency, which enriches the theoretical study of high-frequency bipolar discharges. [ABSTRACT FROM AUTHOR]

Biomass is frequently used to produce CO and H 2 together with undesirable by-products containing CO 2 and liquid tar by pyrolysis and gasification. This leads to decreased energy efficiency and increased maintenance costs. This study investigated the reforming of biogas and tar, respectively, using non-thermal plasma featuring dielectric barrier discharge (DBD). The gas surrogates studied were CH 4 and CO 2 , and toluene was used as a substitute for tar. During reforming of biogas, CO or H 2 was added to the CH 4 and CO 2 to investigate their effects on CH 4 and CO 2 conversion. Both the discharge power and gas components influenced the conversion of CH 4 and CO 2 . The conversion efficiency of CH 4 and CO 2 and the selectivity of H 2 and CO both increased with the discharge power while reforming the mixture of CH 4 and CO 2 . The maximum conversion efficiency of CH 4 and CO 2 and selectivity of CO and H 2 were obtained with a CH 4 :CO 2 ratio of 1:2. During reforming of toluene, the conversion efficiency of toluene reached a maximum value of 90% and the production yields of H 2 , CO, and CO 2 reached respective maximums of 0.79, 2.24, and 1.51 mol/mol-toluene at a discharge power of 90 W and temperature of 300 °C. Higher temperatures of 400–500 °C did not favour toluene destruction due to the thermal breakdown of the quartz dielectric and the rapid decrease in the discharging intensity. In addition, reaction mechanism for reforming of both biogas and toluene was proposed to improve our understanding of the reforming process in DBD plasma. [ABSTRACT FROM AUTHOR]

Effects of carrier gas composition (N 2 /air) on NH 3 production, energy efficiency regarding NH 3 production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an Al 2 O 3 -packed dielectric barrier discharge (DBD) reactor at room temperature. Results show that the presence of O 2 in the carrier gas accelerates the conversion of urea but leads to less generation of NH 3 . The final yield of NH 3 in the gas phase decreased from 70.5%, 78.7%, 66.6% and 67.2% to 54.1%, 51.7%, 49.6% and 53.4% for applied voltages of 17, 19, 21 and 23 kV, respectively when air was used as the carrier gas instead of N 2 . From the viewpoint of energy savings, however, air carrier gas is better than N 2 due to reduced energy consumption and increased energy efficiency for decomposition of a fixed amount of urea. Carrier gas composition has little influence on the major decomposition pathways of urea under the synergetic effects of plasma and Al 2 O 3 catalyst to give NH 3 and CO 2 as the main products. Compared to a small amount of N 2 O formed with N 2 as the carrier gas, however, more byproducts including N 2 O and NO 2 in the gas phase and NH 4 NO 3 in solid deposits were produced with air as the carrier gas, probably due to the unproductive consumption of NH 3 , the possible intermediate HNCO and even urea by the abundant active oxygen species and nitrogen oxides generated in air-DBD plasma. [ABSTRACT FROM AUTHOR]

This study focused on sterilization methods for the reduction of microorganisms on perilla leaves by cylinder type Dielectric Barrier Discharge (DBD) plasma with underwater bubbler treatment. S. aureus and E. coli in a suspension were reduced to less than 3.4 and 0.5 log CFU/ml after the plasma treatment for 3 min, respectively. On the perilla leaves, they were also reduced to 4.8 and 1.6 log CFU/ml after the plasma treatment, respectively. The S. aureus and E. coli bacterial cell wall was damaged by the plasma treatment evident by scanning electron microscopic analysis. The observed infrared bands of the FTIR spectra demonstrated changes in protein, lipid, polysaccharide, polyphosphate group and other carbohydrate functionalities of plasma treated bacteria and untreated bacterial cell membranes. The degradation of the constituent bonds of the bacterial cell membrane by RONS generated from plasma destroys the DNA, RNA, and proteins within the cell, and may eventually cause cell death. In this study, H 2 O 2 (13.68 μM) and NO 3 (138 μM), which are the main factors generated by plasma, proved to have a bactericidal effect by inducing lipid peroxidation of bacterial cell membranes. In conclusion, cylinder type DBD plasma with underwater bubbler can be used as an environmentally friendly food disinfection device in cleaning processes of the food industry. [ABSTRACT FROM AUTHOR]

The effects of dielectric barrier discharge (DBD) plasma on the film cooling effectiveness of a 30-degree slot was experimentally investigated in a low-speed wind tunnel. The pressure sensitive paint (PSP) technique was used to measure the film cooling effectiveness, and two blowing ratios (0.5 and 1.0) were tested. A sinusoidal waveform with a 1-kHz frequency was supplied to the exposed electrode. Two input voltages (6 and 7 kV) and two exposed electrode locations were considered. The results showed that the film cooling effectiveness of the slot was higher for the blowing ratio of the 1.0 case than that for the blowing ratio of the 0.5 case regardless of plasma operation. The higher input voltage case (7 kV) showed higher film cooling effectiveness than the lower input voltage case (6 kV). The improvement in film cooling effectiveness facilitated by the DBD plasma was more significant when the coolant had less momentum. The maximum improvement of the area averaged film cooling effectiveness was 2.3% for the case with the exposed electrode located at the slot exit and a blowing ratio of 0.5. [ABSTRACT FROM AUTHOR]

This paper studies the processing of poly(dimethylsiloxane) (PDMS) surfaces using dielectric barrier discharge (DBD) plasma in two different assemblies, one using the primary plasma jet obtained from a conventional DBD and the other using a DBD plasma jet transfer. The evolution of water contact angle in the function of plasma processing time and in the function of aging time as well as the changes in the surface roughness of PDMS samples for both plasma treatments have been studied. The vibrational and rotational temperatures are compared for both plasmas and for the first time the vibrational temperature ( \textT\mathrm { {vib}}) for the transferred plasma jet has been shown to be higher as compared with the primary jet. The increment in the \textT\mathrm { {vib}} value seems to be the main reason for the improvements in adhesion properties and surface wettability for the transferred plasma jet. Possible explanations for the increase in the vibrational temperature are presented. [ABSTRACT FROM AUTHOR]

Low-temperature plasma was used to control bacteria, endotoxins and natural organic matter (NOM) in water by a dielectric barrier discharge (DBD) device. Results indicate that DBD plasma has an obvious inactivation effect on various bacteria in water. The degree of inactivation from difficult to easy is as follows: Bacillus subtilis > Escherichia coli > Staphylococcus aureus . Activated ultrapure water treated using DBD plasma exhibited a sustained sterilization effect, but this sterilization effect decreased gradually after 1 h. The total-endotoxin (free-endotoxin and bound-endotoxin) released by Escherichia coli during inactivation, as well as artificially simulated endotoxin in a control solution, was significantly controlled by DBD plasma. Both the metabolites that appeared after inactivation of microorganisms by plasma treatment, and the NOM in filtration effluent of a water treatment plant were well removed by DBD plasma if the treatment duration was sufficiently long. However, the acute toxicity increased significantly, and persisted for at least 2 h, indicating that some long-life active substances were generated during the DBD process. Therefore, the removal of bacteria, endotoxins or NOM does not mean a safe water is produced. It is also important to eliminate the toxicity and byproducts produced during water treatment for the continuous promotion and industrial application of DBD plasma. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge (DBD) plasma treatment in a larger scale, which has the potential for industrial application, was studied for modification of poplar veneer surface for enhancing its interface adhesion. Chemical property, morphology, surface wetting, adhesion property and the stability of the activation after plasma treatment were investigated. ESR, XPS, AFM, contact angle (CA), and shear strength test were carried out to evaluate the effect of plasma treatment. The following properties increased after treatment: the surface free radical concentration, O/C ratio, surface roughness of wood fiber, veneer surface wetting, and surface free energy. Consequently, the plywood composite prepared after plasma treatment showed higher adhesion strength than that prepared from untreated veneer. The best plywoods were obtained from veneers treated at processing power of 4.5 kW of DBD. The time-dependent analysis by surface wetting indicated a modified stability in the first two days after plasma treatment, after which the polar component of the surface decreased and its dispersive component kept the level observed after plasma treatment. In summary, veneer surface modification by DBD plasma is promising for industrial application. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge (DBD) plasma at atmospheric pressure in air was applied to a poplar veneer surface. Effects of plasma processing rate on surface morphology, chemical property, and surface wettability of the poplar veneer were investigated. The adhesion strength of urea formaldehyde (UF) glued plywood manufactured from the modified veneer was also studied. Atomic force microscopy (AFM), electron spinresonance spectroscopy (ESR), X-ray photoelectron spectroscopy (XPS), contact angle tests, and shear strength tests were carried out. AFM indicated that the surface roughness increased after plasma treatment and was the maximum at a processing rate of 14 m/min. Both ESR and XPS tests showed more oxygen accumulation on the wood surface, forming various oxygen-containing chemical groups. Contact angle tests showed better wetting at a decreased plasma processing rate. Consequently, the adhesion strength of plywood increased after plasma treatment and showed higher strength at lower processing rates. [ABSTRACT FROM AUTHOR]

This paper develops a novel symmetric dielectric barrier discharge (DBD) plasma as an ion source for environmental mass spectrometry (MS) applications. The conventional linear-type DBD plasma generator suffers the drawback of floating voltage at the plasma outlet. This paper develops an innovative symmetric T-shaped DBD plasma generator to produce atmospheric plasma with zero-floating potential for high-sensitivity MS analysis. By changing the geometric configuration and the drive phase of the symmetric T-shaped DBD plasma generator, the resulting symmetric structural design can fully cancel the floating potential and noise signal. Therefore, the main objective of this paper is to compare the differences between traditional linear-type DBD and the symmetric T-shaped DBD designs using MS, spectroscopy, and some basic electrical measurements. The most suitable parameters are determined by changing the electrode design, voltage, temperature, gas flow rate, diameter, and other parameters of the plasma tube. The symmetric T-shaped design generator produces the zero-potential plasma that generates fewer ambient gas molecules to form ozone, NOx, water clusters, and other strong oxidizing molecules such that less damage to the MS samples occurs. This in turn results in a less fragmented ion signal and higher sensing performance for rapid MS applications. In addition, the proposed system can directly ionize gas, liquid, and solid samples at more than 10^7 -cm ^-3 ion concentration. Results show that more information-rich spectra can be obtained with the developed symmetric T-shaped DBD plasma generator compared with the typical linear-type DBD generator. [ABSTRACT FROM PUBLISHER]

Insertion sequences (ISs) of the radiation-resistant bacterium Deinococcus geothermalis are transposed into other loci by oxidative stress through hydrogen peroxide treatment. Gamma irradiation and dielectric barrier discharge (DBD) plasma radiation are known to produce a variety of oxidative stress agents such as reactive oxygen species and reactive nitrogen species. Therefore, to determine whether the transposition of ISs was induced in D. geothermalis by both gamma irradiation and DBD plasma radiation, we selected non-pigmented mutants with disrupted target genes encoding carotenoid biosynthesis enzymes such as a phytoene synthase (dgeo _0523) and a phytoene desaturase (dgeo _0524). Different DNA-binding protein-deficient mutants exhibited novel transposition of ISs. Dps (dgeo _0257), OxyR (dgeo _1888), and the LysR (dgeo _2840) family regulator, in addition to cystine importer-disrupted and -overexpressed mutants (dgeo _1986–87 and dgeo _1985R) and wild-type D. geothermalis were tested in this study. Active IS transposition was not detected in two wild-type control species (Deinococcus radiodurans and Deinococcus radiopugnans) after phenotypic selection in gamma irradiation. Our finding demonstrated that gamma irradiation triggers the transposition of particular IS elements, especially IS Dge2 and IS Dge3 of the IS 1 family, IS Dge5 of the IS 701 family, and IS Dge6 of the IS 5 family in wild-type strain and the Δ dgeo _0257, Δ dgeo _1986–87, Δ dgeo _1985R, and Δ dgeo _2840 mutants. Furthermore, DBD plasma radiation triggered the transposition of IS Dge11 of the IS 4 family in the wild-type strain; IS Dge6 of the IS 5 family on Δ dgeo _0257, Δ dgeo _1888 and Δ dgeo _2840; IS Dge5 of the IS 701 family on Δ dgeo _0257 strain. [Display omitted] • Our finding demonstrated that gamma irradiation triggers the transposition of particular IS elements in radiation-resistant bacterium Deinococcus geothermalis. • Furthermore, DBD plasma radiation also triggered the transposition of unique IS elements in WT and taeget gene-deficient mutants. • We compare both radiations for active IS transposition using non-pigment phenotypic selection. [ABSTRACT FROM AUTHOR]

By using an atmospheric pressure microplasma jet array device driven by a.c. voltage with repetition rate of several kilohertz, we were able to inactivate the resistant Pseudomonas sp HB1 cells in aqueous solution. Measurements showed that all Pseudomonas sp. cells in a suspension of 80 mL with the concentration of ~10 CFU (Colony-Forming Units) were killed within a treatment time of 6 min. Rather than O radicals, OH radicals or charged species were supposed to play the most important role in the plasma inactivation process by this method. This design can provide an effective mode of killing the resistant microorganism in water. [ABSTRACT FROM AUTHOR]

In this paper, pulsed-power technology was applied to plasma printing, which is a maskless plasma patterning solution that is being developed for the fabrication process of printed electronics. A high-voltage pulse source was developed and applied to a high-speed plasma printer to improve the speed of plasma printing. Experiments on plasma printing were used to compare the performance of the pulse source with the currently used alternating-current source. From plasma experiments, an electrical plasma model was derived for the plasma printer. Different parameters were investigated, such as the plasma energy as a function of gap distance, applied voltage, and the total amount of plasma that was generated. From these experiments, a connection was made between the plasma energy and the print effectiveness to arrive at optimal parameter values for fast plasma printing. It was concluded that higher plasma energy leads to higher print effectiveness, which leads to an increase in plasma print speed by a factor of 10 when using the pulse source. Moreover, scaling the PlasmaPint technology to reach higher print speeds is achievable by using more print heads or print heads with more tips. [ABSTRACT FROM PUBLISHER]

Banana fibers, an environmentally friendly raw material freely available, were physically modified by atmospheric dielectric barrier discharge (DBD) plasma treatment of different dosages. The influence of the plasma treatment applied on the banana fibers was performed considering the mechanical properties, wettability, chemical composition and surface morphology. These properties were evaluated by tensile tests, static and dynamic contact angle, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, X-ray diffractometry, conductivity and pH of aqueous extract, differential scanning calorimetry and scanning electron microscopy images. We compare untreated and treated fibers with three different DBD plasma dosages. The results of this study showed considerable modifications in banana fibers when these are submitted to plasma treatment. [ABSTRACT FROM AUTHOR]

Most studies concerned with the interactions between plasma discharges and bacteria have mainly focused on the germicidal effects and inactivation mechanisms, with little attention given to the survivor bioeffects, such as changes in metabolism. This paper investigated the production of 1,3-propanediol (1,3-PD) from glycerol by Klebsiellapneumoniae after exposure to dielectric barrier discharge (DBD) plasma in air at atmospheric pressure. Increase in 1,3-PD production as determined from flask culture was dependent on treatment time, and the highest production was observed for cells that were treated with DBD plasma for 4 mm. Changes in the specific activities of the three key enzymes (glycerol dehydrogenase, glycerol dehydratase, and oxidoreductase) involved in the conversion of glycerol to 1,3-PD were detected in the extracts of treated cells. Increase in 1,3-PD production correlated with an increase in the activity levels of all three enzymes. Batch-fermentation results showed that DBD plasma-treated cells had a 59% increase in both 1,3-PD production (23.8 g/L versus 15 g/L) and productivity (1.19 g/L·h versus 015 g/L·h) over untreated cells. DBD plasma, therefore, can alter the metabolic activities of K pneumoniae, resulting in enhanced production of 1,3-PD. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-thermal plasma can effectively inactivate Microcystis aeruginosa. • Plasma significantly represses algal functions and promotes MCs release and degradation. • Reactive species and intracellular ROS for bacterial inactivation are proposed. • Reduced gene expressions contribute to inhibited algal regrowth and physiological damage of short-period DBD treatment. There are still few studies on long-term growth inhibition of cyanobacteria though direct algae inactivation by discharge plasma has been widely invetigated. In the work, a home-made DBD system was applied to investigate the immediate and long-term inactivation effect of Microcystis aeruginosa (M. aeruginosa). Owing to discharge plasma in gas–liquid interface or liquid phase, RONS including H 2 O 2 , O 3 and N O 3 - and O H radical are produced. The bactericidal effects are time-dependent and a 3.36log reduction (above 99.99%) is achieved after 10-min exposure followed by the loss of membrane integrity resulting in damaged metabolic capacity and partial RS transportation into cells. Plasma discharge also leads to increased intracellular ROS and NO aggravating inactivation efficacy in the interior structure. The concentration changes of MCs indicates a well degradation effect on MCs by DBD plasma. Moreover, growth arrest (10 day for 0.5-min and 15 day for 1-min treated samples) indicates continuous inactivation of short-period DBD. The decreased contents of photosynthetic pigments (phycobilins and Chl-a) and inhibited nutrient absorption efficiency could contribute to residual inactivation effect. The inhibited synthesis of MCs are induced by short-period plasma treatment. The comprehensive regulations of genes associated with physiological processes are potentially responsible for long-term inactivation of M. aeruginosa. This work therefore proposes a type of feasible advanced oxidation process (AOPs) to utilization of DBD plasma that achieves effective short-term and long-term inactivation efficacy of M. aeruginosa. [ABSTRACT FROM AUTHOR]

[Display omitted] • The reactor with copper foil as outer electrode and aluminum rob as inner electrode performed better on CO 2 decomposition. • DBD reactor with perovskites packed can enhance CO 2 conversion effectively. • There is a synergistic effect of perovskite catalysis and plasma discharge on CO 2 decomposition. Plasma has been widely used in wastewater treatment, material modification and biomedicine due to its unique properties. In this work, a coaxial cylindrical dielectric barrier discharge (DBD) reactor was set up to investigate the effects of electrode materials and catalyst combined with DBD plasma on CO 2 decomposition under room temperature and atmosphere pressure. The materials of inner electrode and outer electrode were investigated without catalysts packed in the reactor. It was found that the aluminum rod as inner electrode performed better than copper rod and stainless steel rod due to the moderate thermal conductivity and electrical conductivity of aluminum rod. Nevertheless, copper foil worked better as external electrode material since its higher electrical conductivity facilitated generation of high energy electrons by the high voltage between electrodes. After perovskite-type catalyst was introduced in the reactor, CO 2 conversion increased, which was attributed to the synergistic effect of perovskite combined with plasma discharge. Perovskite-type catalysts could modulate the capacitance of the reactor to make plasma discharge more uniform and increased CO 2 conversion, while plasma discharge provided high energy electrons that activated oxides sites and basic sites of perovskite-type catalysts. The maximum CO 2 conversion was 23 % and maximum energy efficiency was 2.1 % when MgTiO 3 was packed in the reactor. [ABSTRACT FROM AUTHOR]

This study investigated the effects of dielectric barrier discharge (DBD) plasma against Staphylococcus aureus and Bacillus cereus (initial inoculum of 8–9 log 10 CFU/mL) on the surface of dried blackmouth angler, and the physicochemical [pH, Hunter colors, thiobarbituric acid reactive (TBA)] and sensorial quality on the dried blackmouth angler. Reductions in S. aureus and B. cereus counts on the fillet treated with 1, 5, 10, 20 and 30 min of DBD plasma ranged from 0.10 to 1.03 log 10 CFU/g and 0.14 to 1.06 log 10 CFU/g, respectively. The D 1 and D 2 (90% and 99% reduction time) of DBD plasma for S. aureus and B. cereus by first-order kinetics were 33 and 66.88 min and 32.36 and 64.74 min, respectively. TBA values increased slightly with an increase in DBD plasma treatment times. However, differences in Hunter colors ["L", "a", and "b"] and pH of the dried blackmouth angler were not significant between the non-treated (control) and DBD plasma-treated samples. Moreover, the most sensory attributes [appearance, color, flavor, overall acceptability] were not significantly different between the non-treated and DBD plasma-treated dried blackmouth angler. However, when treated with DBD plasma for more than 20 min, the texture value decreased significantly (P < 0.05). This study indicates that 30 min of DBD plasma treatment resulted in >90% reduction of S. aureus and B. cereus without concomitant overall adverse changes in dried blackmouth angler; this approach can be considered in dried fishery food production, processing, and distribution processes to enhance dried fishery meat safety. • D 1 of DBD plasma for S. aureus and B. cereus on dried blackmouth angler were 33 and 32.36 min respectively. • D 2 of DBD plasma for S. aureus and B. cereus on dried blackmouth angler were 66.88 and 64.74 min, respectively. • TBA values increased slightly with an increase in DBD plasma treatment times. • No significant differences in pH and most sensory attributes between the non-treated and DBD plasma-treated fillets. • 30 min of DBD plasma resulted in >90% reduction of S. aureus and B. cereus without overall adverse changes. [ABSTRACT FROM AUTHOR]

The degradation of liquid phase N,N-dimethylformamide (DMF) using the dielectric barrier discharge (DBD) plasma was studied in the present study. The results showed that 1000 mg L−1 DMF could be degraded by DBD plasma under different input power, treatment time and initial pH values of aqueous solution. After 40 min with DBD plasma discharge, 52.2% degradation efficiency was achieved at DMF concentration of 1000 mg L−1 with an input power of 16.19 W under initial pH of 11.14 in aqueous solution, and the energy efficiency of the system was 13.2 mg kJ−1. The removal efficiency decreased with the presence of radical scavenger, manifesting that •OH plays a critical role in the degradation process. The value of TOC in DMF aqueous solution decreased from 790 mg L−1 to 507 mg L−1 in 40 min, which indicated that DBD plasma has the ability to mineralize a portion of DMF in liquid directly. Additionally, the analysis of FTIR, HPLC and the small molecular organic compounds before and after the DBD plasma degradation indicated that the intermediates of DMF in degradation process were N-methylformamide, methanol, formaldehyde and formic acid, which were finally mineralized into ammonia nitrogen, CO 2 and H 2 O. Moreover, the possible degradation mechanism and pathways were proposed. Image 1 • DMF in liquid phase can be degraded by DBD plasma is illustrated to be feasible. • Various operating parameters on DMF degradation were studied. • OH played a major role in the process of DMF degradation by DBD plasma treatment. • The possible degradation mechanism and pathways were proposed. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of some dielectric barrier discharge plasma reactor parameters such as dielectric conductivity and electrode gap on the plasma mode. The results show that in the shorter gap, plasma is more homogenous, and dielectric conductivity can affect on the plasma mode. [ABSTRACT FROM AUTHOR]