Non-thermal Atmospheric Plasma Research Articles

Simple synthesis of ultrafine amorphous silicon carbide nanoparticles by atmospheric plasmas

An atmospheric non-thermal arc plasma source based on magnetically stabilized gliding arc discharge was developed for the continuous preparation of ultrafine amorphous silicon carbide (a-SiC) nanoparticles via hexamethyldisilane decomposition. Results showed that the as-synthesized products were a mix of a-SiC nanoparticles and free carbon excess. The average particle size of nanoparticles was about 9 nm, and there were abundant functional groups and oxidized overlayers on the surface of the nanoparticles. Photoluminescence properties revealed the a-SiC nanoparticles had strong blue-green light emission under the excitation of 340–420 nm, which was possibly related to the surface functional groups, oxidized overlayers and quantum confinement effect due to ultrafine size. Correlations between the arc current and the crystal structure of the product indicated that the low input energy favored the synthesis of a-SiC nanoparticles, while the high input energy promotedthetransition from amorphous structure to β-SiC.

Applications of Non-thermal Atmospheric Plasma in Restorative Dentistry: A Narrative Review

Plasma-related technologies are essential in modern industries. Recently, plasma has attracted increasedattention in the biomedical field. Non-thermal plasma (NTP) is widely used for various therapeuticapplications in health care. Particularly in dentistry, this paper supplies an essential knowledge of plasmaand a narrative review of plasma uses in restorative dentistry. There have been efforts to use NTP technologyin restorative dentistry involving modifications of dental surfaces, adhesion, treatment of dental caries, andtooth bleaching. Although various investigations were in the recent stages, the prospective value of NTPfor dental uses has been occured. To extende the scope of plasma approaches and put suitable research topractical use, interdisciplinary research with the participation of dental professionals is recommended.

Applications of Non-thermal Atmospheric Plasma in Restorative Dentistry: A Narrative Review

Plasma-related technologies are essential in modern industries. Recently, plasma has attracted increasedattention in the biomedical field. Non-thermal plasma (NTP) is widely used for various therapeuticapplications in health care. Particularly in dentistry, this paper supplies an essential knowledge of plasmaand a narrative review of plasma uses in restorative dentistry. There have been efforts to use NTP technologyin restorative dentistry involving modifications of dental surfaces, adhesion, treatment of dental caries, andtooth bleaching. Although various investigations were in the recent stages, the prospective value of NTPfor dental uses has been occured. To extende the scope of plasma approaches and put suitable research topractical use, interdisciplinary research with the participation of dental professionals is recommended.

Investigation of non-thermal atmospheric plasma for the degradation of avermectin solution

Increasing concern with regard to food safety in the presence of pesticide residues (PRs) on the surface of agricultural products has resulted in the rapid development of practical degrading technologies for corresponding PRs. In this paper, an unconventional method of degrading pesticides, non-thermal atmospheric plasma (NTAP), was proposed to degrade the avermectin (AVM) in aqueous solution. Optical emission spectroscopy shows that NTAP, consisting of filamentary streamers, contains a variety of reactive oxygen species (ROS) that may interact with AVM. The high-performance liquid chromatography (HPLC)-MS/MS results indicate that the efficiency of AVM degradation seriously depends on multiple operation parameters of the NTAP, including the applied voltage, treatment time and gas flow rate. The maximum degradation rate of AVM was observed to be 97.47% after 240 s exposure under NTAP with an applied voltage of 18 kV and gas flow rate of 1 l min−1. Molecular dynamics simulation based on a reactive force field for the interaction between O (ground state atomic oxygen) and AVM was performed to analyze the underpinning mechanisms. The simulation result shows the possible pathways of the NTAP-generated O degrading AVM by destroying the glycosyl group or fracturing the ester group.

The Whitening Effect and Histological Safety of Nonthermal Atmospheric Plasma Inducing Tooth Bleaching.

Various light sources have been applied to enhance the bleaching effect. This study was to identify the histological evaluation in oral soft tissues, as well as tooth color change after tooth bleaching by nonthermal atmospheric pressure plasma (NAPP). Nine New Zealand adult female rabbits were randomly divided into three groups (n = 3): group 1 received no treatment; group 2 was treated with NAPP and 15% carbamide peroxide (CP), which contains 5.4% H2O2, and group 3 was treated with 15% CP without NAPP. Color change (ΔE) was measured using the Shade Eye NCC colorimeter. Animals were euthanized one day later to analyze the histological responses occurring in oral soft tissues, including pulp, gingiva, tongue, buccal mucosa, and hard and soft palates. Changes in all samples were analyzed by hematoxylin and eosin staining and Masson’s trichrome. Teeth treated with plasma showed higher ΔE than that obtained with bleaching agents alone. Overall, the histological characteristics observed no appreciable changes. The combinational treatment of plasma had not indicated inflammatory responses as well as thermal damages. NAPP did not cause histological damage in oral soft tissues during tooth bleaching. We suggest that NAPP could be a novel alternative energy source to conventional light sources for tooth bleaching.

Synthesis of ultrafine silicon carbide nanoparticles using nonthermal arc plasma at atmospheric pressure

AbstractIt remains a significant challenge for the scalable production of ultrafine silicon carbide (SiC) nanoparticles with sizes smaller than 10 nm. In this work, a novel process based on atmospheric nonthermal arc plasma was proposed for the continuous synthesis of ultrafine SiC nanoparticles. This low‐cost and scalable technique allows preparation of SiC nanoparticles with small size (5–9 nm) and narrow size distribution via hexamethyldisilane (HMDS) decomposition in an argon/hydrogen plasma environment. The as‐synthesized products were carbon‐rich β‐SiC nanoparticles with plentiful functional groups on the surface. The addition of hydrogen in plasma gas can tune the product characteristics, such as decreasing particle size, improving crystallinity, and reducing carbon and oxygen contents. Moreover, the as‐prepared β‐SiC nanoparticles had a high band gap (around 2.5 eV), and their photoluminescence peak showed an obvious blueshift relative to that of bulk β‐SiC, which was mainly attributed to the quantum confinement effect induced by their ultrafine size. According to the spectral information of arc plasma, the formation of SiC nanoparticles in the plasma was discussed.

Potential application of non-thermal atmospheric plasma in reducing the activity of Pseudomonas-secreted proteases in milk

Application of non-thermal atmospheric plasma was examined against the activity of Pseudomonas-secreted proteases in milk. UHT milk samples were inoculated with crude extract of Pseudomonas-secreted proteases and treated in atmospheric plasma discharge system. Evaluation of the progress in protein hydrolysis of plasma-treated and non-treated milk samples revealed that the degree of hydrolysis was lower in plasma-treated milk samples. The longer the plasma treatment time, the lower the degree of hydrolysis during storage. Furthermore, plasma-induced changes in milk proteins and volatile compounds were also evaluated. Caseins, whey proteins, aldehydes, ketones, free fatty acids and hydrocarbons were all affected by plasma discharge. The amount of increase or decrease in these components was dependent on the duration of plasma treatment. Overall, this method is a promising approach that could be used to inactivate bacterial hydrolytic enzymes in milk.

Non-thermal atmospheric plasma reactor design for fine powder processing and starch modification

In this article, non-thermal plasma technology at atmospheric pressure for fine powder processing was investigated. A common potato starch was modified within Argon plasma to produce a commercial well-known modified starch known as HT drilling starch. A theoretical model was developed for possible future scale-up of the designed suitable plasma reactor in the emerging field of plasma modification of starch. The model predicts the incipient condition for full fluidization of the solid particles within the plasma fluid. This condition led to maximum interaction between the plasma species and the starch granules. The predicted incipient full fluidization velocity in the model was in consistent with required experimental flow conditions for producing the desired modified starch. Since the plasma modified starch was used as an adhesion additive, the known characteristics in the oil & gas-well drilling fluid such as Fluid-Loss (F.L) and viscosity were reduced more than 30% and 10%, respectively.

Soybean Oil and Nonthermal Plasma Pretreatment to Dye Para‐Aramid Woven Fabrics with Disperse Dye Using a Glycerol‐Based Dye Bath

AbstractHigh‐performance para‐aramid fibers offer a number of uses as strong, lightweight materials for protective vests, helmets, tires, and other applications. The chemically inert nature of the fibers makes them difficult to dye or durably print by conventional dyeing techniques for textiles, and solution dyeing during production of the fibers can limit the color of para‐aramid fabrics to the color of the spun yarn prior to weaving or knitting and thereby limit the practical applications of these textiles as protective outerwear. This study presents a new method developed to improve the dyeing of woven para‐aramid fabrics with a disperse dye. Specifically, sequential experimentation proves the beneficial effects of first soaking para‐aramid fabrics in soybean oil followed by surface treatment with atmospheric nonthermal plasma and using glycerol as the dispersant and sodium chloride as an electrolyte without the addition of other auxiliary chemicals. Under the optimized treatment conditions of this study, the color strength (K/S value) of dyed para‐aramid fabrics increased to 3.89 from 0.35 of the untreated samples as determined from spectral analysis of the sample reflectance in the visible range. Fourier transform infrared spectroscopy analysis revealed that the high content of unsaturated fatty acids in soybean oil and their interaction with reactive species in the ambient nonthermal plasma were the primary factors for improving the color strength of the dyed para‐aramid fabrics.

Effect of Non-Thermal Atmospheric Plasma on Micro-Tensile Bond Strength at Adhesive/Dentin Interface: A Systematic Review.

Objective: The objective of this review was to evaluate the effect of non-thermal atmospheric plasma (NTAP) on adhesives resin–dentin micro-tensile bond strength (μTBS) in previously published studies. Methods: Electronic search was conducted using the Medline, Cochrane library, and Scopus databases. The included studies were laboratory studies that investigated the effect of NTAP on adhesives μTBS to coronal dentin. Studies that evaluated the effect of NTAP on bond strength to indirect substrates, enamel or root dentin, were excluded. The methodological quality of included studies was assessed. Results: Thirteen studies were included in this systematic review. All the included studies were considered to have a medium risk of bias. NTAP significantly improved μTBS at 24 h or after short-term aging in five studies (38.5%) and both immediate and after long-term aging in 5 studies (38.5%). In two studies (15.4%), NTAP resulted in a short-term material-dependent effect that was not stable after long-term aging. Interestingly, in one study (7.7%), NTAP had a positive effect only in the etch-and-rinse (ER) mode after long-term aging. Conclusion: Within the limitations of this systematic review, NTAP application could enhance resin–dentin μTBS of ER adhesives or universal adhesives (UAs) applied in the ER mode. In the ER mode, the rewetting step after NTAP seems to be unnecessary. Because of the limited information currently available in the literature, further studies are required to evaluate the effect of the NTAP application on self-etch (SE) adhesives or UAs applied in the SE mode.

Adhesion of Resin Cement to Zirconia Using Argon Plasma and Primer.

To evaluate the effectiveness of nonthermal atmospheric plasma (NTAP) and priming on the shear bond strength (SBS) of a resin cement to two zirconia ceramics after 24 hours and 1 year of water storage. A total of 120 plates (9 x 7 x 2 mm) were obtained from two types of zirconia (Katana, Kuraray Noritake; and ZirCAD, Ivoclar Vivadent) plates randomly divided into 12 groups (n = 10 each). Zirconia ceramic plates were submitted to the following treatments: (1) untreated (control); (2) treated with ZPrime Plus (Bisco Dental) primer; (3) NTAP (Surface Plasma Tool Model SAP, Surface Engineering and Plasma Solution) application for 10 seconds; (4) NTAP for 30 seconds; (5) NTAP for 10 seconds followed by priming; and (6) NTAP for 30 seconds followed by priming. Two silicone molds (2.37-mm diameter x 2-mm height) were positioned on the treated surface of each zirconia plate, and the resin cement (Panavia F 2.0, Kuraray Noritake) was manipulated and inserted into the molds. After light activation, two resin cement cylinders (specimens) were obtained from each plate. One specimen was tested after 24 hours, and the other after 1 year. The shear load was applied to the base of the resin cement cylinders until failure. Data were analyzed using three-way ANOVA and post hoc Tukey test (α = .05). NTAP application alone (groups 3 and 4) increased SBS compared to the control group only at 24 hours. After 1 year, the NTAP/primer combination showed higher SBS than the other groups. Water storage for 1 year reduced the bond strength for all groups. NTAP, combined or not combined with primer, had a beneficial effect on adhesion after 24 hours and after 1 year. Water storage negatively influenced the adhesion in all groups.

In vitro study of non-thermal atmospheric plasma influencing the surface properties of dentin

Objective: To study the influence of non-thermal atmospheric pressure plasma (NTAPP) on dentine surface temperature, wettability and morphology of collagen fibrils under different treatment condition. Methods: Helium was used as the operating gas at the flow rate of 3, 4, 5 L/min respectively. The plasma jet was operated at various input power of 8, 9, 10, 11 W. Thermal accumulation on human dentine surface (6 specimens per group, acquired from Department of Stomatology, The First Affiliated Hospital of Xi'an Medical University and Department of Stomatology, The Second Affiliated Hospital of Xi'an Medical University) of each group was measured continuously at 5 s intervals for 60 s by infrared thermography. Mean values were calculated and temperature curves were drawn. Dentine surface contact angles were measured after NTAPP treatment for 5, 10, 15, 20 s with gas flow rate and input power described above. The micro structure of the collagen fibrils of the negative control group (without NTAPP treatment) and NTAPP treatment groups (5 L/min gas flow rate, input power of 8, 9, 10, 11 W and treating time for 5, 10, 15, 20 s) was observed by field emission scanning electron microscopy (FE-SEM). All data were analyzed by SPSS 18.0. Results: Input power, gas flow and treatment time all showed significant influences on dentine surface temperature and wettability (P<0.01). Dentine temperature rose along with time. The greater input power was, the higher dentine temperature was. The greater gas flow rate was, the faster the temperature rose. Dentine surface temperature reached the highest point of (35.10±0.24) ℃ with NTAPP treatment for 60 s, at input power of 11 W and flow rate of 5 L/min. The contact angles of each experimental group decreased with time, and significant differences were found in the contact angles between the experimental groups and the negative control group (75.57°±1.45°). The contact angles showed a decreasing trend as the input power and the gas flow rate increased. The contact angles reached the lowest point of 13.19°±2.01° with NTAPP treatment for 20 s, at input power of 10 W and flow rate of 5 L/min. The FE-SEM results showed that, along with the increase of input power and extension of time, the demineralized collagen fibrils were destroyed in varying degrees. The collagen fibrils were curled, fractured, fused, and even disappeared. Conclusions: NTAPP could significantly increase the surface temperature, modify dentine wettability and alter the micro structure, which was significantly influenced by input power, gas flow rate and treating time.

Non-Thermal Methods for Ensuring the Microbiological Quality and Safety of Seafood

A literature search and systematic review were conducted to present and discuss the most recent research studies for the past twenty years on the application of non-thermal methods for ensuring the microbiological safety and quality of fish and seafood. This review presents the principles and reveals the potential benefits of high hydrostatic pressure processing (HHP), ultrasounds (US), non-thermal atmospheric plasma (NTAP), pulsed electric fields (PEF), and electrolyzed water (EW) as alternative methods to conventional heat treatments. Some of these methods have already been adopted by the seafood industry, while others show promising results in inactivating microbial contaminants or spoilage bacteria from solid or liquid seafood products without affecting the biochemical or sensory quality. The main applications and mechanisms of action for each emerging technology are being discussed. Each of these technologies has a specific mode of microbial inactivation and a specific range of use. Thus, their knowledge is important to design a practical application plan focusing on producing safer, qualitative seafood products with added value following today’s consumers’ needs.

The Influence of Atmospheric Non-thermal Plasma on Jasmine Rice Seed Enhancements

This work aims to study the influence of atmospheric non-thermal plasma on the enhancement of early growth jasmine rice seeds. Air plasma has been generated by a multi-pin plasma generator at the supplied source voltage of 18, 22, 26, and 30 kV and has been exposed on target seeds for 60, 300, and 600 s. After the treatment process, the jasmine rice seeds have been cultivated in the soil for 10 days. All the plasma-treated samples have shown higher germination rates up to 22% than the one of the control sample. Moreover, the protein content in pre-germinated brown jasmine rice affected by plasma treatment has been also studied. From the experimental results, it could be confirmed that the overall protein content in plasma-treated brown jasmine rice seeds has been higher than the one of the control groups. Based on the finding in this work, it could be confirmed that the application of plasma has improved not only the germination and the growth of jasmine rice seeds but also the protein content of pre-germinated brown jasmine rice seeds.

Effect of nonthermal atmospheric plasma on the shear bond strength of composite resin after using different tooth-whitening systems: An in vitro study.

Aim:We aimed to evaluate the effect of nonthermal atmospheric plasma (NTAP) on the bond strength of composite resin after using different tooth-whitening systems.Methods:Eighty maxillary central incisors (n = 80) were divided into two groups based on the tooth-whitening procedure used – Group 1: bleaching (Pola Office, USA), Group 2: microabrasion (Opalustre, Australia). The samples were subdivided into four groups depending on the surface treatments – Group A: control (no surface treatment), Group B: plasma, Group C: antioxidant (sodium ascorbate), and Group D: buffering agent (sodium bicarbonate). After the surface treatments, the specimens were stored in artificial saliva for 24 h and composite resin was bonded to the labial surface of the teeth perpendicular to the long axis. The samples were then subjected to shear bond strength test under the universal testing machine.Statistical Analysis:The results received from shear bond strength analysis were subjected to statistical analysis using a two-way ANOVA test, independent t-test, and Tukey's multiple post hoc tests. The P value set was <0.05.Results:The highest mean bond strength value was seen in Group 2B (NTAP treatment after microabrasion) followed by Group 1B (NTAP treatment after bleaching). Mean shear bond strength values have suggested a statistically significant difference between all the other groups (P < 0.05) except between Groups 1A, 2A and 1D, 2D.Conclusions:Within the limitations of the current in vitro study, bleaching and microabrasion followed by surface treatment using NTAP showed the highest bond strength than other groups.

Non-thermal plasma treatment of cellulosic biopolymer to enhance its surface property for various applications: A review

Abstract Plasma technology applied to biopolymers industries is a dry and environment-friendly process for achieving surface alteration without altering its bulk properties. Two kinds of plasma are primarily used; thermal (hot) and non-thermal (cold). Thermal plasma has a temperature of the order of 1000 K on the other hand cold plasma is maintained around room temperature. Non-thermal atmospheric plasmas are ideal for biopolymers materials because they are heat sensitive and are applicable to continuous processes. For achieving desirable changes on the surface topography of biopolymer, correct understanding of chemical and physical nature of plasma is required. Various cellulosic biopolymers like cotton fibre, banana fibre, linen fibre have a wide range of industrial applications. Among overall applications of cellulosic biopolymers, surface modification is of profound importance as it improves various properties such as softness, roughness, crystallinity, lubricity, dye-ability, antimicrobial tendency and wettability.

Hydroamination of ethylene with NH3 induced by non-thermal atmospheric plasma

We show here that non-thermal atmospheric plasma induces the cleavage of the N–H bond of NH3 to form aminium radicals, which then add onto ethylene to form ethylamine in 17% yield.

Effects of Nonthermal Atmospheric Pressure Plasma Jet on Human Dental Pulp Stem Cells

The effects of a nonthermal atmospheric plasma jet with argon and argon/oxygen (Ar/O&lt;sub&gt;2&lt;/sub&gt;) gases on live human dental pulp stem cells (hDPSCs) were studied to verify tooth vitality in the pulp-capping process. Using MTT assay, the surviving hDPSCs after plasma jet exposure for 1, 2, and 3 min were counted. First, for the pulsed plasma jet the frequency varied from 10 to 50 kHz for 5 groups with Ar and 5 groups with Ar/O&lt;sub&gt;2&lt;/sub&gt; plasma jet. Later, with the alternating current (AC) plasma jet, the voltage was changed between 5.5 and 16.05 kV for 13 groups. The cells in the control group were only exposed to Ar and Ar/O&lt;sub&gt;2&lt;/sub&gt; gases. To control thermal damage to hDPSCs, optical emission spectroscopy was used. For data analysis, the ANOVA repeated measure was used. There were significant differences between the various frequencies and exposure durations (&lt;i&gt;p&lt;/i&gt; &amp;#60; 0.05) for the Ar plasma. For the Ar/O&lt;sub&gt;2&lt;/sub&gt; gas, there were significant differences between frequencies (&lt;i&gt;p&lt;/i&gt; &amp;#60; 0.001). For the AC plasma jet with Ar gas, there were significant differences between voltages (&lt;i&gt;p&lt;/i&gt; &amp;#60; 0.001). At the higher pulsed jet frequencies, temperatures increased. Eventually, the suitable durations for root canal disinfection and hDPSC survival with the Ar pulsed jet were 2 and 3 min at 10 and 30 kHz, respectively. Since cold plasma disinfection keeps hDPSCs alive, it can be helpful in promoting tooth survival and durability for pulp capping in clinical treatments.

Effect of nonthermal atmospheric plasma on the push-out bond strength of epoxy resin-based and bioceramic root canal sealers: An in vitro study.

Aim:The aim of this study was to evaluate the effect of nonthermal atmospheric plasma (NTAP) on the bond strength of epoxy resin-based and bioceramic root canal sealers.Materials and Methods:Freshly extracted forty (n = 40) single-rooted mandibular premolar teeth were divided into four groups (n = 10) based on the sealer used and NTAP application – Group 1: Epoxy resin-based sealer (AH Plus) without NTAP application, Group 2: Epoxy resin-based sealer (AH Plus) with NTAP application for 30 s, Group 3: Bioceramic sealer (BioRoot RCS) without NTAP application, and Group 4: Bioceramic sealer (BioRoot RCS) with NTAP application for 30 s. After NTAP application in Groups 2 and 4, all the samples were obturated using sealers according to their grouping protocols. Two-millimeter slices were obtained from each sample using hard tissue microtome, which were subjected to push-out bond strength (PBS) under the universal testing machine. Data were subjected to statistical analysis using one-way analysis of variance followed by the Post hoc tukey test. The level of statistical significance was set at P < 0.05.Results:The PBS values were observed to be significantly higher in bioceramic sealer with NTAP application (Group 4) followed by epoxy resin-based sealer with NTAP application (Group 2).Conclusion:NTAP application enhanced the PBS of bioceramic (BioRoot RCS) and epoxy resin-based (AH Plus) sealers compared to their control groups.

The Effect of Packing Material Properties on Tars Removal by Plasma Catalysis

Plasma catalysis has been utilized in many environmental applications for removal of various hydrocarbons including tars. The aim of this work was to study the tars removal process by atmospheric pressure DBD non-thermal plasma generated in combination with packing materials of various composition and catalytic activity (TiO2, Pt/γAl2O3, BaTiO3, γAl2O3, ZrO2, glass beads), dielectric constant (5–4000), shape (spherical and cylindrical pellets and beads), size (3–5 mm in diameter, 3–8 mm in length), and specific surface area (37–150 m2/g). Naphthalene was chosen as a model tar compound. The experiments were performed at a temperature of 100 °C and a naphthalene initial concentration of approx. 3000 ppm, i.e., under conditions that are usually less favorable to achieve high removal efficiencies. For a given specific input energy of 320 J/L, naphthalene removal efficiency followed a sequence: TiO2 &gt; Pt/γAl2O3 &gt; ZrO2 &gt; γAl2O3 &gt; glass beads &gt; BaTiO3 &gt; plasma only. The efficiency increased with the increasing specific surface area of a given packing material, while its shape and size were also found to be important. By-products of naphthalene decomposition were analyzed by means of FTIR spectrometry and surface of packing materials by SEM analysis.