Corrigendum to“Reactive oxygen species in plasma against E.coli cells survival rate”

Recently, we found some errors in Fig. 3 of the article Chin. Phys. B 24 085201 (2015). Upon a thorough examination of the raw data materials, we confirm that the image error did not impact any of the findings and conclusions of the paper. Based on this, we have made corrections to the original article.

Experiment on inducing apoptosis of melanoma cells by micro-plasma jet

As a promising cancer treatment method,cold atmospheric plasma has received widespread attention in recent years.However,previous research has focused more on how to realize and expand the anti-cancer scope of plasma jet.There are also studies on the killing of small-scale cancer cells,but the effects of plasma jet on normal cells and normal cell clusters have been ignored.Therefore,we proposed a 50μm sized micro-plasma jet device,and used the device to treat melanoma cells(A-375)and human glial cells(HA1800)to evaluate their anti-cancer effects and effects on normal cells.The experimental results show that this kind of micro-plasma jet device can effectively inactivate cancer cells in a short period of time,while having little effect on normal cells.This work provides a certain experimental basis for the application offine plasma jet to clinically inactivate cancer cells.

A Simulator for Producing of High Flux Atomic Oxygen Beam by Using ECR Plasma Source

In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600 W was launched into the circular cavity to generate ECR (electron cyclotron resonance) plasma. The oxygen ion beam moved onto a negatively biased Mo plate under the condition of symmetry magnetic mirror field confine, then was neutralized and reflected to form oxygen atom beam. The properties of plasma density, electron temperature, plasma space potential and ion incident energy were characterized. The atomic oxygen beam flux was calibrated by measuring the mass loss rate of Kapton during the atomic oxygen exposure. The test results show that the atomic oxygen beam with flux of 1016-1017 atoms-cm-2·s-1 and energy of 5-30 eV and a cross section of φ80 mm could be obtained under the operating pressure of 10-1-10-3 Pa. Such a high flux source can provide accelerated simulation tests of materials and coatings for space applications.

Fabrication and study of supercapacitor electrodes based on oxygen plasma functionalized carbon nanotube fibers

Dry-spun Carbon Nanotube(CNT)fibers were surface-modified by atmospheric pressure oxygen plasma functionalization using a well controlled and continuous process.The fibers were characterized by scanning electron microscopy(SEM),Raman spectroscopy,and X-ray Photoelectron Spectroscopy(XPS).It was found from the conducted electrochemical measurements that the functionalized fibers showed a 132.8% increase in specific capacitance compared to non-functionalized fibers.Dye-adsorption test and the obtained Randles-Sevcik plot demonstrated that the oxygen plasma functionalized fibers exhibited increased surface area.It was further established by Brunauer-Emmett-Teller(BET)measurements that the surface area of the CNT fibers was increased from 168.22 m^2/g to 208.01 m^2/g after plasma functionalization.The pore size distribution of the fibers was also altered by this processing.The improved electrochemical data was attributed to enhanced wettability,increased surface area,and the presence of oxygen functional groups,which promoted the capacitance of the fibers.Fiber supercapacitors were fabricated from the oxygen plasma functionalized CNT fiber electrodes using different electrolyte systems.The devices with functionalized electrodes exhibited excellent cyclic stability(93.2% after 4000 cycles),flexibility,bendability,and good energy densities.At 0.5 m A/cm^2,the EMIMBF4 device revealed a specific capacitance,which is 27% and 65%greater than the specific capacitances of devices using EMIMTFSI and H2SO4 electrolytes,respectively.The practiced in this work plasma surface processing can be employed in other applications where fibers,yarns,ribbons,and sheets need to be chemically modified.

Atmospheric Pressure Cold Argon/Oxygen Plasma Jet Assisted by Preionization of Syringe Needle Electrode

An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 10^17 cm^-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.

Comparative studies on the hot corrosion behavior of air plasma spray and high velocity oxygen fuel coated Co-based L605 superalloys in a gas turbine environment

An improvement in the corrosion resistance of alloys at elevated temperature is a factor for their potential use in gas turbines. In this study, Co Ni Cr Al Y has been coated on the L605 alloy using air plasma spray(APS) and high-velocity oxygen fuel(HVOF) coating techniques to enhance its corrosion resistance. Hot corrosion studies were conducted on uncoated and coated samples in a molten salt environment at 850°C under cyclic conditions. Thermogravimetric analysis was used to determine the corrosion kinetics. The samples were subjected to scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction for further investigation. In coated samples, the formation of Al2O3 and Cr2O3 in the coating acts as a diffusion barrier that could resists the inward movement of the corrosive species present in the molten salt. Coated samples showed very less spallation, lower weight gain, less porosity, and internal oxidation as compared to uncoated sample.HVOF-coated sample showed greater corrosion resistance and inferred that this is the best technique under these conditions.

Characteristics of DBD micro-discharge at different pressure and its effect on the performance of oxygen plasma reactor

The oxygen plasma reactor based on dielectric barrier discharge principle can produce a high concentration of reactive oxygen species,which can cooperate with hydraulic cavitation gas-liquid mixer to realize the application of advanced oxidation technology in water treatment.In this technology,the work pressure of the oxygen plasma reactor is decreased by the vacuum suction effect generated in the snap-back section of the gas-liquid mixed container.In this paper,the characteristics of single micro-discharge at different pressures were investigated with the methods of discharge image,electrical characteristics and spectral diagnosis,in order to analyze the electrical characteristics and reactive oxygen species generation efficiency of oxygen plasma reactor at the pressure range from 60 kPa to 100 kPa.The study indicated that,when the pressure decreases,the duty ratio of ionization in the discharge gap and number of electrons with high energy increases,leading to a rise in reactive oxygen species production.When the oxygen reaches the maximum ionization,the concentration of reactive oxygen species is the highest.Then,the discharge intensity continues to increase,producing more heat,which will decompose the ozone and lower the production of reactive oxygen species.The oxygen plasma reactor has an optimum working pressure at different input powers,which makes the oxygen plasma reactor the most efficient in generating reactive oxygen species.

Methane conversion in the presence of oxygen under low-temperature radio frequency plasma

Methane conversion in the presence of oxygen under low-temperature radio frequency （RF） plasma was investigated.The experiment results indicated that the following four factors,i.e.,discharge voltage,discharge area,O2/CH4 molar ratio and total gas flowrate,affected remarkably the reaction performance.The optimum reaction conditions of methane conversion in the presence of O2 under RF plasma are as follows：discharge voltage 1050 V,discharge area 989.1mm 2,O2/CH4 molar ratio 1/10 and total gas flowrate 200 ml/min.A methane conversion of 91% could be reached under the optimum conditions.Oxygen is good for the breaking of C-H bonds and also acts as a sort of thinner.According to the low-temperature plasma characteristics,the macroscopic kinetics model of methane conversion in the presence of O2 under radio frequency plasma was studied.

Effect of Oxygen Plasma on Low Dielectric Constant HSQ (Hydrogensilsesquioxane) Films

The commercially available hydrogensilsesquioxane （HSQ） offers a low dielectric constant. In this paper, the impact of oxygen plasma treatment has been investigated on the low- k HSQ films. Fourier transform infrared （FTIR） spectroscopy was used to identify the network structure and cage structure of Si-O-Si bonds and other possible bonds after treatments. C-V and I-V measurements were used to determine the dielectric constant, the electronic resistivity and the breakdown electric field, respectively. The result indicates that oxygen plasma treatment will damage the HSQ films by removing the hydrogen content. Both dielectric constant and leakage current density increase significantly after oxygen plasma exposure. The dielectric constant and leakage current density can both be decreased by annealing at 350 ℃ for 1.5 h in nitrogen ambient. The reason is that the open porous of the external films can be modified and density of thin film be increased. The rough surface can be smoothed.

Quantitative Determination of Density of Ground State Atomic Oxygen from Both TALIF and Emission Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave （MW） resonant cavity. The latter operates at a frequency of 2.45 GHz inside a cell of gas conditioning at a pressure of 600 mbar, an injected air flow of 12 L/min and an input MW power of 1 kW. The first technique is based on the standard two photon absorption laser induced fluorescence （TALIF） using xenon for calibration but applied for the first time in the present post discharge hot air plasma column having a temperature of about 4500 K near the axis of the nozzle. The second diagnostic technique is an actinometry method based on optical emission spectroscopy （OES）. In this case, we compared the spectra intensities of a specific atomic oxygen line （844 nm） and the closest wavelength xenon line （823 nm）. The two lines need to be collected under absolutely the same spectroscopic parameters. The xenon emission is due to the addition of a small proportion of xenon （1% Xe） of this chemically inert gas inside the air while a further small quantity of H2 （2~） is also added in the mixture in order to collect OH（A- X） and NH（A-X） spectra without noise. The latter molecular spectra are required to estimate gas and excitation temperatures. Optical emission spectroscopy measurements, at for instance the position z=12 mm on the axis plasma column that leads to a gas measured temperature equal to 3500 K, an excitation temperature of about 9500 K and an atomic oxygen density 2.09× 1017＋ 0.2×1017 cm-3. This is in very good agreement with the TALIF measurement, which is equal to 2.0×101T cm-3.

Enhanced Work Function of Al-Doped Zinc-Oxide Thin Films by Oxygen Inductively Coupled Plasma Treatment

Al-doped zinc-oxide （AZO） thin films treated by oxygen and chlorine inductively coupled plasma （ICP） were compared. Kelvin probe （KP） and X-ray photoelectron spectroscopy （XPS） were employed to characterize the effect of treatment. The results of KP measurement show that the surface work function of AZO thin films can increase up to 5.92 eV after oxygen ICP （O-ICP）＇s treatment, which means that the work function was increased by at least 1.1 eV. However, after the treatment of chlorine ICP （CI-ICP）, the work function increased to 5.44 eV, and the increment was 0.6 eV. And 10 days later, the work function increment was still 0.4 eV after O-ICP＇s treatment, while the work function after Cl-ICP＇s treatment came back to the original value only after 48 hours. The XPS results suggested that the O-ICP treatment was more effective than CI-ICP for enhancing the work function of AZO films, which is well consistent with KP results.

Study on Bombyx mori silk treated by oxygen plasma

Study of the morphology, aggregation structure and properties ofBombyx mori silk treated by low temperature oxygen plasma showed that slight flutes appeared on the surface of Bombyx mori silk fiber and that its surface structure changed after plasma treatment. The conformation also changed and crystalline degree decreased. The stannic filling rate of treated fiber was improved. Because of etching, the weight of the fiber decreased but the breaking strength changed little after short-time treatment.

Relationship of Hyperbaric Oxygen Therapy of Acute Compartment Syndrome with Changes of Plasma Fibronectin Concentration

This report describes for the first time the effects of hyperbaric oxygen therapy with 253kPa on patients(n=24) with post - trauma acute compartment syndrome, and the relationship be-tween the prognosis of the syndrome and the changes of plasma fibronectin. Plasma fibronectin wasmeasured using single radial immunodiffusion both before and after therapy with hyperbaric oxygen,with 30 healthy people as control for plasma fibronectin. The results showed that the clinical symp-toms and signs of all 16 patients with acute compartment syndromes in early stage were significantlyimproved after 3 times of hyperbaric oxygen therapy and disappeared after 5 times withoutfasciotomy. Six patients who were treated with hyperbaric oxygen after fasciotomy showed reductionin the infection, and, edema of the injured limb However, the effects were less favorable for 2 pa-tients with necrosis although their clinical symptoms and signs were partially improved. Besides,we found that these patients’ plasma fibronectin concentrations were significantly afterhyperbaric oxygen therapy. The mean increase was 43 (18. 9％; P【0. 01), 61( 24. 7%, P【0. 01),49 (17. 2%, P【0. 01), 57 (17. 4%; P【0. 05) and 55 mg/L ( 16. 6%; P【0. 05) after 1, 2, 3, 4and 5 times of therapy, respectively. Plasma fibronectin concentrations returned to the level of thecontrols after 3 times of therapy (P】0. 05). After fourth and fifth therapy plasma fibronectin lev-els of the patients rose higher than those of the controls (P【0.05). The results suggest that hyperbaric oxygen therapy has a beneficial effect on patients withacute compartment syndrome in the early stage Hyperbaric oxygen therapy can reduce edema andskeletal muscle necrosis The method can be used to treat patients with acute compartmentsyndrome in early stage and as an effective adjunctive treatment after fasciotomy.

Effect of Oxygen on Surface Properties and Drug Release Behavior of Plasma Polymer of n-Butyl Methacrylate

The effects of oxygen on the chemical structure, morphology, hydrophilicity and drug release behavior of radio-frequency plasma poly n- butyl methacrylate （PPBMA） thin film were carded out for the first time. ATR-FTIR and XPS showed that oxygen had little influence on the chemical structure and composition of PPBMAs, which did not agree with the thought that the presence of oxygen gas would increase the oxidized carbon functionalities in the plasma polymer. SEM and static contact angle measurement indicated that in case of deposition with oxygen, the smoothness and hydrophilicity of PPBMA were dramatically improved. The drug release behavior showed that drug release from the PPBMA coating without oxygen was biphasic patterns, while from PPBMA coating with oxygen was Higuchi release. These results were helpful for the design and tailoring of the PPBMA polymer film and other of plasma polymers film, but could provide a new idea for the drug release controlled form.

Surface Properties of AZ31B Magnesium Alloy by Oxygen Plasma Immersion Ion Implantation

Oxygen plasma immersion ion implantation （PIII） has been conducted on AZ31B magnesium alloy using different bias voltages. The modified layer is mainly composed of MgO and some MgAl2O4. Results form Rutherford backscattering spectrometry （RBS） and X-ray photoelectron spectroscopy （XPS） indicate that the bias voltage has a significant impact on the structure of the films. The oxygen implant fluences and the thickness of the implanted layer increase with higher bias voltages. A high bias voltage such as 60 kV leads to an unexpected increments in the oxygen-rich layer＇s thickness compared to those of the samples implanted at 20 kV and 40 kV. The hardness is hardly enhanced by oxygen PIII. The corrosion resistance of magnesium alloy may be improved by a proper implantation voltage.

Reactive oxygen species in plasma against E.coli cells survival rate

In this paper, we report on the contrastive analysis of inactivation efficiency of E. coli cells in solution with different disinfection methods. Compared with the hydrogen peroxide solution and the ozone gas, the atmospheric-pressure He plasma can completely kill the E. coli cells in the shortest time. The inactivation efficiency of E. coli cells in solution can be well described by using the chemical reaction rate model. X-ray photoelectron spectroscopy(XPS) analysis shows that the C–O or C=O content of the inactivated E. coli cell surface by plasma is predominantly increased, indicating the quantity of oxygen-containing species in plasma is more than those of two other methods, and then the C–C or C–H bonds can be broken, leading to the etching of organic compounds. Analysis also indicates that plasma-generated species can play a crucial role in the inactivation process by their direct reactions or the decompositions of reactive species, such as ozone into OH radicals in water, then reacting with E. coli cells.

Effect of Krypton Addition on Electron Cyclotron Resonance-Radio Frequency Hybrid Oxygen Plasma for Patterning Diamond Surfaces

Electron cyclotron resonance radio frequency （ECR-rf） hybrid krypton-diluted oxygen plasmas were used to pattern the surfaces of diamond films with the assistance of a physical mask, while optical emission spectroscopy was employed to characterize the plasma. It was found that with krypton dilution the etching rate decreased, and also the aspect ratios of nanotips formed in micro-holes were significantly modified. The oxygen atomic densities were estimated by oxygen atom optical emission and argon actinometry. Under a microwave power of 300 W and rf bias of-300 V, the absolute density of ground-state oxygen atoms decreased from 1.3×10^12 cm^-3 to 1.4×10^11 cm^-3 as the krypton dilution ratio increased to 80%, accompanied by the decrease in the plasma excitation temperature. It is concluded that oxygen atoms play a dominant role in diamond etching. The relative variations in the horizontal and vertical etching rates induced by the addition of krypton are attributed to the observations of thicker nanotips at a high krypton dilution ratio.

SURFACE REARRANGEMENTS OF OXYGEN PLASMA TREATED POLYSTYRENE:SURFACE DYNAMICS AND HUMIDITY EFFECT

The time evolution of oxygen plasma treated polystyrene(PS)surfaces was investigated upon storing them in theair under controlled humidity conditions.The methods of water contact angle,X-ray photoelectron spectroscopy(XPS),sumfrequency generation(SFG)vibrational spectroscopy,and atomic force microscopy(AFM)were used to infer the surfaceproperties and structure.Chemical groups containing oxygen were formed on the PS surface with the plasma treatment,demonstrated by water contact angle and XPS.The surface polarity decayed markedly on time,as assessed by steady increasein the water contact angle as a function of storage time,from zero to around 60°.The observed decay is interpreted as arisingfrom surface rearrangement processes to burying polar groups away from the uppermost layer of the surfaces,which is incontact with air.On the other hand,XPS results show that the chemical composition in the first 3 nm surface layer isunaffected by the surface aging,and the depth profile of oxygen is essentially the same with time.A possible change of PSsurface roughness was examined by AFM,and it showed that the increase of water contact angle during surface aging couldnot be attributed to surface roughness.Thus,it is concluded that surface aging is attributable to surface reorganization andthe motion of oxygen containing groups is confined within the XPS probing depth.SFG spectroscopy,which is intrinsicallyinterface-specific,was used to detect the chemical structure of PS surface at the molecular level after various aging times.The results are interpreted as follows.During the aging of the plasma treated PS surfaces,the oxygen containing groupsundergo reorientation processes toward the polymer bulk and/or parallel to the surface,while the CH_2 moiety stands up onthe PS surface.Our results indicate that the surface configuration changes do not require large length scale segmentalmotions or migration of macromolecules.Motions that are responsible for surface configuration changes could be relativelysmall rotational motions.The aging behaviors under different relative humidity conditions were shown to be similar from18% to 91%,whereas the kinetics of surface polarity decays were faster in higher relative humidity.Here,the surfacerearrangement of polystyrene films that were previously treated by oxygen plasma and aged,and was investigated in terms ofcontact angle after the water immersion.The contact angles of the water-immersed samples were found to change andapproach the initial values before the immersion asymptotically.

Characterization of Oxygen Plasma Modified Polyimide Fibers Interfacial Adhesion Performance by Single Fiber Fragmentation Test

The application of polyimide( PI) fibers in the field of composite materials has been limited because of their smooth surface and chemical inertness. In order to overcome these problems,oxygen plasma was used to modify the surface of fibers. The single fiber fragmentation test( SFFT) was used to characterize the interfacial adhesion performance of PI fiber as a simple and accurate analysis method. It was found that the interfacial shear strength between the fiber and resin after oxygen plasma modification was increased by 54% compared to the untreated fiber. Meanwhile, the surface micromorphology,chemical composition, wettability of fibers and the interface morphology at the fiber fracture were analyzed by field emission scanning electron microscope( FESEM), X-ray photoelectron spectroscopy( XPS),contact angle measurement and polarizing microscope,respectively. All of these results demonstrated that the single fiber fragmentation test for analyzing the interfacial adhesion of PI fibers was effective.

Influence of oxygen addition on the discharge characteristics of an argon plasma jet at atmospheric pressure

Plasma jet is an important low-temperature plasma source in extensive application fields.To promote the production of active oxygen species,oxygen is often introduced into the inert working gas.However,the influence of oxygen content on the discharge characteristics of an argon plasma jet is not clear.Aim to this status,an argon plasma jet in a singleelectrode geometry is employed to investigate the influence of oxygen concentration(CO)on discharge aspects.Results indicate that with increasing CO(≤0.6%),the plume transits from a diffuse morphology to a hollow structure.Electrical and optical measurements reveal that both discharge number per voltage cycle and pulse intensity alter with varying CO.Moreover,discharge morphologies of negative and positive discharges obtained by fast photograph also shift with varying CO.Besides,optical emission spectra are collected to investigate atomic CO,electron density,and electron temperature.The results mentioned above are explained qualitatively,which are believed to be of great significance for the applications of atmospheric pressure plasma jet.