Effects of Atmospheric Plasma Corona Discharge on Agrobacterium tumefaciens Survival

Soil-borne pathogenic microorganisms are known to cause extensive crop losses. Agrobacterium tumefaciens, a member of the Proteobacteria, causes the neoplastic crown gall disease in plants. Plant protection is mainly based on toxic chemicals that are harmful to the environment. The use of cold atmospheric-pressure plasma is an attractive method for microbial eradication. Its antimicrobial mechanism includes the formation of large quantities of reactive oxygen species (ROS). The advantages of eradicating bacteria using cold plasma are not needed for chemicals, short treatment, and environmental temperatures. This study examined the impact of plasma corona discharge exposure on A. tumefaciens viability, membrane permeability, relative cell size, and ROS formation. The results showed that 90 s of plasma exposure led to a reduction by four orders of magnitude when the initial concentration was 1 × 107 CFU/mL and in a dry environment. When the initial concentration was 1 × 106 CFU/mL, 45 s of exposure resulted in total bacterial eradication. In a liquid environment, in an initial concentration of 2.02 × 106 CFU/mL, there was no complete bacterial eradication even at the most prolonged examined exposure (90 s). The influence of plasma treatment on the membrane permeability of A. tumefaciens, and their possible recovery, were analyzed using flow cytometer analysis using propidium iodide (PI). When the plasma-treated bacteria were suspended in Luria–Bertani (LB) (rich medium), the PI-positive count of the plasma-treated bacteria after two hours was 12 ± 3.9%. At the 24th hour, this percentage was only 1.74 ± 0.6%, as the control (0.7 ± 0.1%). These results may indicate the repair of the plasma-treated bacteria that were suspended in LB. At the 24th hour, the relative cell size of the treated bacteria shifted to the right, to ~3 × 104 forward side scatter (FSC), about 0.5-fold higher than the untreated cells. Measurement of the ROS showed that the intracellular fluorescence of the 90-s plasma-treated cells led to significant fluorescence formation of 32 relative fluorescence units (RFU)/cell (9 × 104 fold, compared to the nontreated cells). This study showed that cold plasma is a useful method for A. tumefaciens eradication. The eradication mechanism involves ROS generation, membrane permeability, and changes in cell size.

Poly (N-vinylpyrrolidone) modification mitigates plasma protein corona formation on phosphomolybdate-based nanoparticles

Phosphomolybdate-based nanoparticles (PMo12-based NPs) have been commonly applied in nanomedicine. However, upon contact with biofluids, proteins are quickly adsorbed onto the NPs surface to form a protein corona, which induces the opsonization and facilitates the rapid clearance of the NPs by macrophage uptake. Herein, we introduce a family of structurally homologous PMo12-based NPs (CDS-PMo12@PVPx(x = 0 ~ 1) NPs) capping diverse content of zwitterionic polymer poly (N-vinylpyrrolidone) (PVP) to regulate the protein corona formation on PMo12-based NPs. The fluorescence quenching data indicate that the introduction of PVP effectively reduces the number of binding sites of proteins on PMo12-based NPs. Molecular docking simulations results show that the contact surface area and binding energy of proteins to CDS-PMo12@PVP1 NPs are smaller than the CDS-PMo12@PVP0 NPs. The liquid chromatography-tandem mass spectrometry (LC–MS/MS) is further applied to analyze and quantify the compositions of the human plasma corona formation on CDS-PMo12@PVPx(x = 0 ~ 1) NPs. The number of plasma protein groups adsorption on CDS-PMo12@PVP1 NPs, compared to CDS-PMo12@PVP0 NPs, decreases from 372 to 271. In addition, 76 differentially adsorption proteins are identified between CDS-PMo12@PVP0 and CDS-PMo12@PVP1 NPs, in which apolipoprotein is up-regulated in CDS-PMo12@PVP1 NPs. The apolipoprotein adsorption onto the NPs is proposed to have dysoponic activity and enhance the circulation time of NPs. Our findings demonstrate that PVP grafting on PMo12-based NPs is a promising strategy to improve the anti-biofouling property for PMo12-based nanodrug design. Graphical Abstract

Deep Penetration of UV Radiation into PMMA and Electron Acceleration in Long Plasma Channels Produced by 100 ns KrF Laser Pulses

Long (~1 mm), narrow (30−40 μm in diameter) corrugated capillary-like channels were produced in the axially symmetric 2D interaction regime of 100 ns KrF laser pulses with polymethylmethacrylate (PMMA) at intensities of up to 5 × 1012 W/cm2. The channels extended from the top of a deep (~1 mm) conical ablative crater and terminated in a 0.5 mm size crown-like pattern. The modeling experiments with preliminary drilled capillaries in PMMA targets and Monte Carlo simulations evidenced that the crown origin might be caused by high-energy (0.1–0.25 MeV) electrons, which are much higher than the electron temperature of the plasma corona ~100 eV. This indicates the presence of an unusual direct electron acceleration regime. Firstly, fast electrons are generated due to laser plasma instabilities favored by a long-length interaction of a narrow-band radiation with plasma in the crater. Then, the electrons are accelerated by an axial component of the electrical field in a plasma-filled corrugated capillary waveguide enhanced by radiation self-focusing and specular reflection at the radial plasma gradient, while channel ripples serve the slowing down of the electromagnetic wave in the phase with electrons.

Poly (N-vinylpyrrolidone) Modification Mitigates Plasma Protein Corona Formation on Phosphomolybdate-based Nanoparticles

Phosphomolybdate-based nanoparticles (PMo12-based NPs) have been commonly applied in nanomedicine. However, upon contact with biofluids, proteins are quickly adsorbed onto the NPs surface to form a protein corona, which induces the opsonization and facilitates the rapid clearance of the NPs by macrophage uptake. Herein, we introduce a family of structurally homologous PMo12-based NPs (CDS-PMo12@PVPx(x = 0 ~ 1) NPs) capping diverse content of zwitterionic polymer poly (N-vinylpyrrolidone) (PVP) to regulate the protein corona formation on PMo12-based NPs. The fluorescence quenching data indicate that the introduction of PVP effectively reduces the number of binding sites of proteins on PMo12-based NPs. Molecular docking simulations results show that the contact surface area and binding energy of proteins to CDS-PMo12@PVP1 NPs are smaller than the CDS-PMo12@PVP0 NPs. The liquid chromatography-tandem mass spectrometry (LC-MS/MS) is further applied to analyze and quantify the compositions of the human plasma corona formation on CDS-PMo12@PVPx(x = 0 ~ 1) NPs. The number of plasma protein groups adsorption on CDS-PMo12@PVP1 NPs, compared to CDS-PMo12@PVP0 NPs, decreases from 372 to 271. In addition, 76 differentially adsorption proteins are identified between CDS-PMo12@PVP0 and CDS-PMo12@PVP1 NPs, in which apolipoprotein is up-regulated in CDS-PMo12@PVP1 NPs. The apolipoprotein adsorption onto the NPs is proposed to have dysoponic activity and enhance the circulation time of NPs. Our findings demonstrate that PVP grafting on PMo12-based NPs is a promising strategy to improve the anti-biofouling property for PMo12-based nanodrug design.

A Study of Anti-Radiation Weaving Fabric with Plasma Corona Treatment

<p>In this research, Carbon black particles were applied on the woven fabric by the knife coating technique and pretreatment using plasma corona discharge to build-up conductive cotton-polyester (CVC 50%) fabric electromagnetic shielding material. This paper describes the making of anti-radiation weaving fabric using plasma technology. The anti-radiation patch was developed by first modifying the textile fabric's surface using atmospheric pressure plasma technology using tip-cylinder electrode configuration. The plasma corona discharge was generated using high voltage electricity with asymmetrical electrodes (tip and cylinder). The treated weaving fabric using plasma was then coated with carbon black ink. This research indicates that an anti-radiation weaving fabric was successfully shielded electromagnetic radiation from an electronic device.</p>

A Preliminary Study for Modification of Wetting Properties on Cotton Polyester (TC) Fabric Surface Using Atmospheric Plasma Corona Discharge Technology

Textile materials generally have intrinsic properties, such as flexibility, light volume density, strength, tenacity, comfort and softness. Based on these characteristics, the textile material is generally given a special additional function, such as hydrophobic or hydrophilic properties. The addition of these special functions to the textile industry is generally using conventional wet methods that require more energy and water as well as more chemicals need and expensive price. Plasma technology is one of the dry process technologies and it can reduce the use of chemicals that can pollute the environment. This article describes the application of atmospheric plasma corona discharge technology in the textile sector, especially its use in modifying wetting properties on the surface of polyester cotton (TC) 70%. The results showed that by varying the time of plasma treatment on 70% TC cotton polyester fabric with density of weft and warp respectively 70 strands / inch and 60 strands / inch we found that there was a change in the wetting properties of the fabric with increasing hydrophilic properties of the fabric. SEM images show the example of morphology of cotton polyester fabric surfaces treated with time of exposure by plasma at one minute (60 s) at 3 kV of output voltage as the optimal exposure time and applied voltage to enhance the wetting properties.

Numerical Characterization of Corona Spark Plugs and Its Effects on Radicals Production

A mono-dimensional code for the simulation of the effects of High Frequency Ignition systems (HFI) on the production of chemical radicals was developed and here presented. The simulations were carried out by considering the typical environmental thermodynamic conditions of a nowadays engine at full load. An electron transport model is linked with a Boltzmann solver coupled with a chemistry solver, affecting the Electron Energy Distribution Function (EEDF) in order to obtain the physical conditions leading to the production of radical components for a given fuel mixture. The transport equations for the electrons, the positive and the negative ions, and the Gauss’ law in a steady-state plasma region. Then the Boltzmann equation for the electrons, in a spatially homogeneous steady-state case, is solved in order to obtain the EEDF. Finally the chemical kinetics model is employed assuming a fuel-air mixture neglecting the fuel carbon atoms due to the assumption that electron-impact dissociation reactions, which initiate the combustion, exhibit a greater reaction rate compared to those based on hydrocarbon thermal dissociation and therefore can be neglected in this work. Results show the production of the hydrogen (H), nitrogen (N), and oxygen (O) radicals and the radius of the initial discharge under different simulated engine operating conditions characterizing the role of a plasma corona effect for the induced chemical ignition in gasoline-powered engines.

Co oxidation over alumina monolith impregnated with oxides of copper and manganese

In this work, preparation and performance of catalysts as using a simple method and highly efficient heterogeneous nanocatalyst is described. The main advantages of the reaction are high yields for the oxidation of CO at low temperature. The catalysts based-on oxides of copper and manganese supported on alumina monoliths were prepared by the different methods: plasma corona discharge and wet impregnation. Structure and physical properties of catalysts were characterized by FT-IR, XRD, TEM, EDX and TG/DTA. The results showed that the using of plasma corona discharge at atmospheric pressure in the preparation process of catalyst gives a smaller particle size, uniform dispersion when compared with the catalysts prepared by the wet impregnation methods. The catalytic activities of these catalysts were investigated for complete oxidation of carbon monoxide (3000 ppm) to carbon dioxide in the air at the atmospheric pressure. On a single oxide catalyst, 10CuO/monolith was better than 10MnO2/monolith in the same experimental condition. With multi-oxide catalysts, all catalyst samples are more active than a single-oxide catalyst in the same impregnated content. In particular, the catalyst is prepared by plasma corona discharge indicate the best oxidation capacity of carbon monoxide (CO).