Showing papers on "Atmospheric pressure published in 2012"
TL;DR: In this paper, a numerical model of a surface microdischarge (SMD) in humid air at atmospheric pressure is presented, which includes over 50 species and 600 elementary reactions and consists of two coupled well-mixed regions: a discharge layer with both charged and neutral species and an afterglow region consisting only of neutral species.
Abstract: We present a numerical model of a surface microdischarge (SMD) in humid air at atmospheric pressure. Our model includes over 50 species and 600 elementary reactions and consists of two, coupled well-mixed regions: a discharge layer with both charged and neutral species and an afterglow region consisting only of neutral species. Multiple time steps employed in our model enable capturing rapid dynamic behaviour in the discharge layer as well as the relatively slow diffusion and reaction in the afterglow. A short duration, high electric field is assumed to be excited at 10 kHz in the discharge region with power density maintained at 0.05 W cm−2. Among the predicted dominant species in the afterglow are O3, N2O5, N2O, HNO3, H2, NO3, H2O2, HNO2 and NO2. The results are in qualitative agreement with Fourier transform infrared absorption spectroscopy. Our simulation results show that density of those reactive species continues to evolve significantly in time, even after ~15 min of SMD exposure. This result suggests that SMD treatments on the order of minutes or less may involve significant neutral species concentration and flux transients, potentially affecting interpretation of results.
403 citations
TL;DR: In this article, the state of the art on scientific and technologic locks, which have to be opened to consider direct atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) a viable option for industrial application, is established.
Abstract: Over the last ten years, expansion of atmospheric pressure plasma solutions for surface treatment of materials has been remarkable, however direct plasma technology for thin film deposition needs still great effort. The objective of this paper is to establish the state of the art on scientific and technologic locks, which have to be opened to consider direct atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) a viable option for industrial application. Basic scientific principles to understand and optimize an AP-PECVD process are summarized. Laboratory reactor configurations are reviewed. Reference points for the design and use of AP-PECVD reactors according to the desired thin film properties are given. Finally, solutions to avoid powder formation and to increase the thin film growth rate are discussed.
282 citations
Book•
01 Jan 2012
TL;DR: In this article, the authors present an overview of the physical properties of the Earth's surface and atmosphere, including air mass, humidity, and atmospheric stability, as well as weather patterns.
Abstract: 1. Introduction to the Atmosphere. 2. Heating Earth's Surface and Atmosphere. 3. Temperature. 4. Moisture and Atmospheric Stability. 5. Forms of Condensation and Precipitation. 6. Air Pressure and Winds. 7. Circulation of the Atmosphere. 8. Air Masses. 9. Weather Patterns. 10. Thunderstorms and Tornadoes. 11. Hurricanes. 12. Weather Analysis and Forecasting. 13. Air Pollution. 14. The Changing Climate. 15. World Climates. 16. Optical Phenomena of the Atmosphere.
252 citations
TL;DR: In this article, the influence of humid air on reactive species in radio frequency (rf)-driven atmospheric-pressure helium?oxygen mixture plasmas (He?O2, helium with 5000?ppm admixture of oxygen) for wide air impurity levels of 0?500ppm with relative humidities of from 0% to 100% was explored.
Abstract: In most applications helium-based plasma jets operate in an open-air environment. The presence of humid air in the plasma jet will influence the plasma chemistry and can lead to the production of a broader range of reactive species. We explore the influence of humid air on the reactive species in radio frequency (rf)-driven atmospheric-pressure helium?oxygen mixture plasmas (He?O2, helium with 5000?ppm admixture of oxygen) for wide air impurity levels of 0?500?ppm with relative humidities of from 0% to 100% using a zero-dimensional, time-dependent global model. Comparisons are made with experimental measurements in an rf-driven micro-scale atmospheric pressure plasma jet and with one-dimensional semi-kinetic simulations of the same plasma jet. These suggest that the plausible air impurity level is not more than hundreds of ppm in such systems. The evolution of species concentration is described for reactive oxygen species, metastable species, radical species and positively and negatively charged ions (and their clusters). Effects of the air impurity containing water humidity on electronegativity and overall plasma reactivity are clarified with particular emphasis on reactive oxygen species.
251 citations
TL;DR: Real-time mass spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further the understanding of how particles are formed through nucleation in the atmosphere.
Abstract: Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of mass spectrometry. Mass spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of mass spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time mass spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time mass spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time mass spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol mass spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties.
235 citations
Journal Article•
222 citations
TL;DR: In this article, the authors showed that graphene films synthesized by chemical-vapor-deposition enables detection of trace amounts of nitrogen dioxide (NO2) and ammonia (NH3) in air at room temperature and atmospheric pressure.
Abstract: We show that graphene films synthesized by chemical-vapor-deposition enables detection of trace amounts of nitrogen dioxide (NO2) and ammonia (NH3) in air at room temperature and atmospheric pressure. The gas species are detected by monitoring changes in electrical resistance of the graphene film due to gas adsorption. The sensor response time was inversely proportional to the gas concentration. Heating the film expelled chemisorbed molecules from the graphene surface enabling reversible operation. The detection limits of ∼100 parts-per-billion (ppb) for NO2 and ∼500 ppb for NH3 obtained using our device are markedly superior to commercially available NO2 and NH3 detectors.
206 citations
TL;DR: A scale is established on the salt cation and anion abilities to induce the formation of ionic-liquid-based ABSs, which follows the Hofmeister series, and to show that the molar entropy of hydration of the salt ions is the driving force for aqueous two-phase system formation.
Abstract: Among the numerous and interesting features of ionic liquids is their ability to form aqueous biphasic systems (ABSs) when combined with inorganic or organic salts in aqueous media. In this work, a wide range of salts was studied, aiming at gathering a detailed picture on the molecular mechanisms that govern the ability of the salt ions to induce the formation of ionic-liquid-based ABSs. For that purpose, 1-butyl-3-methylimidazolium trifluoromethanesulfonate was chosen due to its facility to undergo liquid-liquid demixing in aqueous media containing conventional salts. The corresponding ternary phase diagrams, tie-lines, and tie-line lengths were determined at 298 K and atmospheric pressure. With the large body of data measured in this work, it was possible to establish a scale on the salt cation and anion abilities to induce the formation of ionic-liquid-based ABSs, which follows the Hofmeister series, and to show that the molar entropy of hydration of the salt ions is the driving force for aqueous two-phase system formation.
177 citations
TL;DR: In this paper, a cyclometalated organoiridium complex was used as an efficient catalyst for hydrogen and formic acid in water at ambient temperature and pressure for both directions depending on pH.
Abstract: Interconversion between hydrogen and formic acid in water at ambient temperature and pressure has been made possible by using a [C,N] cyclometalated organoiridium complex, [IrIII(Cp*)(4-(1H-pyrazol-1-yl-κN2)benzoic acid-κC3)(H2O)]2SO4 [1]2·SO4, as an efficient catalyst for both directions depending on pH. Hydrogenation of carbon dioxide by hydrogen occurs in the presence of a catalytic amount of 1 under an atmospheric pressure of H2 and CO2 in weakly basic water (pH 7.5) at room temperature, whereas formic acid efficiently decomposes to afford H2 and CO2 in the presence of 1 in acidic water (pH 2.8).
177 citations
TL;DR: In this article, the conversion of CO2 to carbon monoxide (CO) and oxygen in an atmospheric pressure microwave plasma/catalyst system was investigated, where the CO2 gas was first treated with plasma alone, and then treated with a combination of plasma and rhodium (Rh) catalyst material.
Abstract: The continual and increasing use of fossil fuels throughout the world has advanced concerns of atmospheric carbon dioxide (CO2) concentrations, causing a swell of scientific interest to ease the predicted effects of global warming. This work experimentally investigates the conversion of CO2 to carbon monoxide (CO) and oxygen in an atmospheric pressure microwave plasma/catalyst system. Diagnostics such as mass spectrometry and optical emission spectroscopy are used to identify the gas species present after plasma treatment and to measure plasma temperatures. The CO2 gas is first treated with plasma alone, and is then treated with a combination of plasma and rhodium (Rh) catalyst material. While the plasma system alone is able to achieve a 20% energy efficiency, the Rh catalyst actually causes a drop in efficiency due to reverse reactions occurring on the surface. The plasma temperature measurements indicate thermal equilibrium between Tr and Tv around 6000–7000 K.
167 citations
TL;DR: In this paper, the transient, dynamic behavior of ozone production in surface microdischarge (SMD) plasma in ambient air was studied and it was shown that ozone density increases monotonically over 1000ppm for at least a few minutes when the input power is lower than ∼ 0.1 W/cm2.
Abstract: We present the transient, dynamic behavior of ozone production in surface micro-discharge (SMD) plasma in ambient air. Ultraviolet absorption spectroscopy at 254 nm was used to measure the time development of ozone density in a confined volume. We observed that ozone density increases monotonically over 1000 ppm for at least a few minutes when the input power is lower than ∼0.1 W/cm2. Interestingly, when input power is higher than ∼0.1 W/cm2, ozone density starts to decrease in a few tens of seconds at a constant power density, showing a peak ozone density. A model calculation suggests that the ozone depletion at higher power density is caused by quenching reactions with nitrogen oxides that are in turn created by vibrationally excited nitrogen molecules reacting with O atoms. The observed mode transition is significantly different from classical ozone reactors in that the transition takes place over time at a constant power. In addition, we observed a positive correlation between time-averaged ozone density and the inactivation rate of Escherichia coli on adjacent agar plates, suggesting that ozone plays a key role in inactivating bacteria under the conditions considered here.
TL;DR: The effective removal of oxygen functional groups by atomic hydrogen enables large-scale applications of GO as flexible conductors to be realized.
Abstract: Reduction of graphene oxide (GO) at low temperature and atmospheric pressure via plasma-assisted chemistry is demonstrated. Hydrogen gas is continuously dissociated in a microplasma to generate atomic hydrogen, which flows from the remote plasma to thin films of GO deposited on a substrate. Direct interaction with ions and other energetic species is avoided to mitigate ion-induced sputter removal or damage. The residual oxygen content and structure of the GO films after plasma treatment is systematically characterized at different temperatures and correlated to the conductivity of the films. For example, at 150 °C, we find that the plasma-reduced GO contains less than 12.5% oxygen and exhibits a sheet resistance of 4.77 × 104 Ω/sq, as compared with thermal reduction alone, which results in 22.9% oxygen and a sheet resistance of 2.14 × 106 Ω/sq. Overall, the effective removal of oxygen functional groups by atomic hydrogen enables large-scale applications of GO as flexible conductors to be realized.
TL;DR: In this paper, the absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF), which is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow.
Abstract: The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air–helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals.
TL;DR: The CO2 data, when corrected for simultaneously measured temperature, water vapor partial pressure, and atmospheric pressure, showed a good agreement with the data measured by a highly accurate CO2 analyzer, LI-6262, indicating that acceptable accuracy can be realized using the calibration method developed in this study.
Abstract: Many sensors have to be used simultaneously for multipoint carbon dioxide (CO2) observation. All the sensors should be calibrated in advance, but this is a time-consuming process. To seek a simplified calibration method, we used four commercial CO2 sensor models and characterized their output tendencies against ambient temperature and length of use, in addition to offset characteristics. We used four samples of standard gas with different CO2 concentrations (0, 407, 1,110, and 1,810 ppm). The outputs of K30 and AN100 models showed linear relationships with temperature and length of use. Calibration coefficients for sensor models were determined using the data from three individual sensors of the same model to minimize the relative RMS error. When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units. In particular, in the case of K30 the relative RMS error decreased from 24% to 4%. Hence, we have chosen K30 for developing a portable CO2 measurement device (10 × 10 × 15 cm, 900 g). Data of CO2 concentration, measurement time and location, temperature, humidity, and atmospheric pressure can be recorded onto a Secure Digital (SD) memory card. The CO2 concentration in a high-school lecture room was monitored with this device. The CO2 data, when corrected for simultaneously measured temperature, water vapor partial pressure, and atmospheric pressure, showed a good agreement with the data measured by a highly accurate CO2 analyzer, LI-6262. This indicates that acceptable accuracy can be realized using the calibration method developed in this study.
TL;DR: Using high-speed imaging, it is shown that surface roughness and air pressure influence both mechanisms of thin-sheet formation and ejection, and that if the air pressure is lowered, droplet ejection is suppressed not only during thin- sheet formation but also for prompt splashing.
Abstract: A liquid drop impacting a solid surface may splash either by emitting a thin liquid sheet that subsequently breaks apart or by promptly ejecting droplets from the advancing liquid-solid contact line. Using high-speed imaging, we show that surface roughness and air pressure influence both mechanisms. Roughness inhibits thin-sheet formation even though it also increases prompt splashing at the advancing contact line. If the air pressure is lowered, droplet ejection is suppressed not only during thin-sheet formation but also for prompt splashing.
01 Jan 2012
TL;DR: Plasma Bio-Decontamination Water Chemistry and Effects on Cells, and Applications of Excilamps in Microbiological and Medical Investigations, and Plasma and Electric Fields in Medicine.
Abstract: Plasma Bio-Decontamination Water Chemistry and Effects on Cells. Atmospheric Pressure Plasmas for Decontamination of Complex Medical Devices K.-D.Weltmann et al.- Characterization of Damage to Bacteria and Bio-Macromolecules caused by (V) UV Radiation and Particles Generated by a Microscale Atmospheric Pressure Plasma Jet J.-W. Lackmann et al.- Bio-Decontamination of Water and Surfaces by DC Discharges in Atmospheric Air Z. Machala et al.- Biological Decontamination Using Pulsed Filamentary Microplasma Jet R. Pothiraja et al.- The Fungal Spores Survival Under the Low-Temperature Plasma H. Souskova et al.- Plasma-Liquid Interactions: Chemistry and Antimicrobial Effects T. von Woedtke et al.- Damages of Biological Components in Bacteria and Bacteriophages Exposed to Atmospheric Non-Thermal Plasma A. Mizuno.- Investigations of Bacterial Inactivation and DNA Fragmentation Induced by Flowing Humid Argo Post-Discharge E. Odic et al.- DNA Oxidation by Reactive Oxygen Species Produced by Atmospheric Pressure Microplasmas J.S. Sousa et al.- Optical Emission Spectroscopic Evaluation of different Microwave Plasma Discharges and Its Potential Application for Sterilization Processes J.L. Hueso et al.- Plasma Biofilm Inactivation and Dentistry Applications. Battling Bacterial Biofilms with Gas Discharge Plasma A. Zelaya et al.- Inactivation of Microorganisms in Model Biofilms by an Atmospheric Pressure Pulsed Non-Thermal Plasma Yu. Akishev et al.-Low Temperature Atmospheric Argon Plasma: Diagnostics and Medical Applications S. Ermolaeva et al.- A Sub-Microsecond Pulsed Plasma jet for Endodontic Biofilm Disinfection C. Jiang et al.- Medical Plasma in Dentistry - a future Therapy for Peri-Implantitis I. Koban et al.- Inactivation of Candida Strains in Planktonic and Biofilm Forms Using a Direct Current, Atmospheric-Pressure Cold Plasma Micro-Jet W.-D. Zhu et al.- Non-Thermal Atmospheric Plasma Treatment for Deactivation of Oral Bacteria and Improvement of Dental Composite Restoration Q.S. Yu et al.- Plasma-Based UV Sterilization. Features of the Sterilization by VUV/UV Irradiation of Low-Pressure Discharge Plasma V.V. Tsiolko et al.- Applications of Excilamps in Microbiological and Medical Investigations V.F. Tarasenko et al.- Xenon Iodide Exciplex Lamp as an Efficient Source for the UV Surface cleaning and Water Decontamination M. Guivan et al.- Plasma Tissue Treatment and Wound Healing. Antisepsis of the Skin by Treatment with Tissue-Tolerable Plasma (TTP): Risk Assessment and Perspectives J. Lademann et al.- Cold Microsecond Spark Discharge Plasma Production of Active Species and their Delivery into Tissue D. Dobruynin et al.- Surface Dielectric Barrier Discharge Jet for Skin Disinfection Y. Creyghton et al.- Cold Atmospheric Plasma for Clinical Purposes - Promising Results in Patients and Future Applications G. Isbary.- Tissue Tolerable Plasma and Polihexanide: Are Synergistic Effects Possible to Promote Healing of Chronic Wounds? In Vivo and in Vitro Results C.P. Bender et al.-Helium Atmospheric Pressure Plasma jet: Diagnostics and Applications for Burned Wounds Hearling I. Topala and A. Nastuta.- Non-Equilibrium Air Plasma for Wound Bleeding Control S.P. Kuo et al.- Plasma and Electric Fields in Medicine. Subcellular Biological Effects of Nanosecond Pulsed Electric Fields J.F. Kolb and M. Stacey.- First Achievements and Opportunities for Cancer Treatment Using Non Thermal Plasma E. Robert et al.- Nitric Oxide Plasma Sources for Bio-Decontamination and Plasma Therapy V.N. Vasilets and A.B. Shekhter.- Generation of Focused Shock Waves in Water for Biomedical Applications P. Lukes et al.- DBD Plasma Assisted Silver Functionalization of Surgical Meshes J. Rahel et al.- Prospects for Treating Foods with Cold Atmospheric Gas Plasmas G. Shama and M.G. Kong.- Decontamination of Bacillus Subtilis Spores in a Sealed Package Using a Non-Thermal Plasma System K.M. Keener et al.- Impact of Atmospheric Plasma Generated by a DBD Device on Quality-Related Attributes of "Abate Fetel" Pear Fruit A. Bernardinelli et al.- Fungicidal Effects of Plasma and Radio-Wave Pre-Treatments on Seeds of Grain Crops and Legumes I. Filatova et al.- Subject Index.
TL;DR: In this article, nanosecond pulsed discharges in N2 and N2/0.9% H2O at atmospheric pressure (at 300?K) were studied with time-resolved imaging, optical emission spectroscopy and Rayleigh scattering.
Abstract: In this contribution, nanosecond pulsed discharges in N2 and N2/0.9% H2O at atmospheric pressure (at 300?K) are studied with time-resolved imaging, optical emission spectroscopy and Rayleigh scattering. A 170?ns high-voltage pulse is applied across two pin-shaped electrodes at a frequency of 1?kHz. The discharge consists of three phases: an ignition phase, a spark phase and a recombination phase. During the ignition phase the emission is mainly caused by molecular nitrogen (N2(C?B)). In the spark and recombination phase mainly atomic nitrogen emission is observed. The emission when H2O is added is very similar, except the small contribution of H? and the intensity of the molecular N2(C?B) emission is less.The gas temperature during the ignition phase is about 350 K, during the discharge the gas temperature increases and is 1??s after ignition equal to 750?K. The electron density is obtained by the broadening of the N emission line at 746?nm and, if water is added, the H? line. The electron density reaches densities up to 4???1024?m?3. Addition of water has no significant influence on the gas temperature and electron density.The diagnostics used in this study are described in detail and the validity of different techniques is compared with previously reported results of other groups.
TL;DR: In this article, a wire mesh entrained flow gasifier and a Pressurized High Temperature Entrained Flow Reactor (PiTER) were used to measure volatile yield of Rhenish lignite, a bituminous coal and German anthracite at high temperature and high pressure.
TL;DR: It was demonstrated that ion mobility-mass spectrometry using either drift tube or traveling wave ion mobility is a valuable technique for resolving subtle variations in stereochemistry among the sodium adducts of monosaccharide methyl glycosides.
Abstract: Monosaccharide structural isomers including sixteen methyl-d-glycopyranosides and four methyl-N-acetylhexosamines were subjected to ion mobility measurements by electrospray ion mobility mass spectrometry. Two ion mobility-MS systems were employed: atmospheric pressure drift tube ion mobility time-of-flight mass spectrometry and a Synapt G2 HDMS system which incorporates a low pressure traveling wave ion mobility separator. All the compounds were investigated as [M + Na]+ ions in the positive mode. A majority of the monosaccharide structural isomers exhibited different mobility drift times in either system, depending on differences in their anomeric and stereochemical configurations. In general, drift time patterns (relative drift times of isomers) matched between the two instruments. Higher resolving power was observed using the atmospheric pressure drift tube. Collision cross section values of monosaccharide structural isomers were directly calculated from the atmospheric pressure ion mobility experimen...
TL;DR: In this article, the authors compared the performance of n-octane/air and 2-methylheptane-air flames with other octane isomers, and found that the overall reactivity decreases as the extent of fuel branching increases.
TL;DR: DAPPI FTICR MS results agree with bulk elemental composition as well as functional group distributions determined by elemental analysis and solid state (13)C NMR spectroscopy, particularly for samples currently limited by solubility, separation, and sample preparation.
Abstract: We present a new method for molecular characterization of intact biochar directly, without sample preparation or pretreatment, on the basis of desorption atmospheric pressure photoionization (DAPPI) coupled to Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Conventional ionization methods (e.g., electrospray or atmospheric pressure photoionization) for characterization of natural organic matter have limited utility for the characterization of chars due to incomplete solubility in common solvents. Therefore, direct ionization techniques that do not require sample dissolution prior to analysis are ideal. Here, we apply DAPPI FTICR mass spectrometry to enable the first molecular characterization of uncharred parent oak biomass and after combustion (250 °C) or pyrolysis (400 °C). Parent oak is primarily composed of cellulose-, lignin-, and resin-like compounds. Oak combusted at 250 °C contains condensed aromatic compounds with low H/C and O/C ratios while retaining compounds with high H/C...
TL;DR: In this article, the Community Climate System Model, version 4 (CCSM4) is evaluated against observational and reanalysis datasets for the present-day (1981-2005) to evaluate surface air temperature, sea level pressure, cloud cover and phase, precipitation and evaporation, atmospheric energy budget, and lower-tropospheric stability.
Abstract: Simulation of key features of the Arctic atmosphere in the Community Climate System Model, version 4 (CCSM4) is evaluated against observational and reanalysis datasets for the present-day (1981‐2005). Surface air temperature, sea level pressure, cloud cover and phase, precipitation and evaporation, the atmospheric energy budget, and lower-tropospheric stability are evaluated. Simulated surface air temperatures are found to be slightly too cold when compared with the 40-yr ECMWF Re-Analysis (ERA-40). Spatial patterns and temporal variability are well simulated. Evaluation of the sea level pressure demonstrates some large biases, most noticeably an under simulation of the Beaufort High during spring and autumn. Monthly Arctic-wide biases of up to 13 mb are reported.Cloud cover is underpredicted for all but summermonths, and cloud phase is demonstrated to be different from observations. Despite low cloud cover, simulated all-sky liquid water pathsaretoohigh,whileicewaterpathwasgenerallytoolow.Precipitationisfoundtobeexcessiveovermuch oftheArcticcomparedtoERA-40andtheGlobalPrecipitation ClimatologyProject(GPCP) estimates.With some exceptions, evaporation is well captured by CCSM4, resulting in P 2 E estimates that are too high. CCSM4 energy budget terms show promising agreement with estimates from several sources. The most noticeable exception to this is the top of the atmosphere (TOA) fluxes that are found to be too low while surface fluxes are found to be too high during summer months. Finally, the lower troposphere is found to be too stable when compared to ERA-40 during all times of year but particularly during spring and summer months.
TL;DR: In this article, particle-in-cell simulations and semi-analytical modeling were used to investigate the electric field and ionization dynamics in capacitively coupled radio frequency (RF) atmospheric pressure microplasmas operated in helium.
Abstract: Electron heating and ionization dynamics in capacitively coupled radio frequency (RF) atmospheric pressure microplasmas operated in helium are investigated by particle-in-cell simulations and semi-analytical modeling. A strong heating of electrons and ionization in the plasma bulk due to high bulk electric fields are observed at distinct times within the RF period. Based on the model the electric field is identified to be a drift field caused by a low electrical conductivity due to the high electron?neutral collision frequency at atmospheric pressure. Thus, the ionization is mainly caused by ohmic heating in this ??-mode?. The phase of strongest bulk electric field and ionization is affected by the driving voltage amplitude. At high amplitudes, the plasma density is high, so that the sheath impedance is comparable to the bulk resistance. Thus, voltage and current are about 45? out of phase and maximum ionization is observed during sheath expansion with local maxima at the sheath edges. At low driving voltages, the plasma density is low and the discharge becomes more resistive, resulting in a smaller phase shift of about 4?. Thus, maximum ionization occurs later within the RF period with a maximum at the discharge center. Significant analogies to electronegative low-pressure macroscopic discharges operated in the drift-ambipolar mode are found, where similar mechanisms induced by a high electronegativity instead of a high collision frequency have been identified.
TL;DR: In this paper, the effects of atmospheric filament-free diffuse plasma in ambient air and oxygen by Diffuse Coplanar Surface Barrier Discharge (DCSBD) on surface of indium tin oxide (ITO) were studied.
TL;DR: In this paper, the ground state OH density is measured in high pressure plasma by laser-induced fluorescence (LIF) spectroscopy, based on the simulation of the intensity fraction of fluorescence from the laser-excited level of OH (A) in the total detected LIF signal.
Abstract: In this paper, the ground state OH density is measured in high pressure plasma by laser-induced fluorescence (LIF) spectroscopy. The OH density determination is based on the simulation of the intensity fraction of fluorescence from the laser-excited level of OH (A) in the total detected LIF signal. The validity of this approach is verified in an atmospheric pressure Ar + H2O plasma jet sustained by a 13.56 MHz power supply. The transition line P1 (4) from OH (A,v′ = 1,J′ = 3) → OH (X,v′′ = 0,J′′ = 4) is used for the LIF excitation. The absolute OH density is determined to be 2.5 × 1019 m-3 at 1 mm away from the jet nozzle. It corresponds to a dissociation of 0.06% of the water vapor in the working gas. Different mechanisms of OH (X) production in the core of the plasma jet are discussed and analyzed.
TL;DR: In this paper, a pulsed-arc atmospheric pressure plasma jet was used to grow polyacrylic acid thin films for cell adhesion using human ovarian carcinoma cells (NIH:OVCAR-3).
Abstract: Polyacrylic acid thin films have been deposited by an original and fast technique to grow organic coatings: a pulsed-arc atmospheric pressure plasma jet. Liquid acrylic acid was introduced in the nitrogen plasma jet and OES was used to measure the fragmentation of the precursor. The films were characterized by XPS, FTIR and SEM analyses before and after soaking in water. The water stability was also investigated by weight loss measurement. A high retention of carboxylic moieties, i.e. functional groups of the monomer has been observed for coatings deposited under mild conditions for the jet (low frequency and high jet speed). These films have been used for cell adhesion using human ovarian carcinoma cells (NIH:OVCAR-3). Good results have been obtained depending on the plasma parameters, showing that atmospheric pressure plasma jet is a promising technique to grow organic thin films for biomedical applications.
TL;DR: In this paper, atmospheric pressure argon plasma sintering of silver nanoparticle inks was investigated to improve the plasma Sintering process in terms of speed, substrate friendliness and technical complexity.
Abstract: Atmospheric pressure argon plasma sintering of silver nanoparticle inks was investigated to improve the plasma sintering process in terms of sintering speed, substrate friendliness and technical complexity. Sintering times were reduced to several seconds while achieving similar conductivity values of above 10% compared to bulk silver. Sintering can be carried out under ambient conditions at specific locations without exposing the entire substrate. Plasma sintering at atmospheric pressure exhibits the capability to be used in roll-to-roll production processes.
TL;DR: The kinetics of the formation of radicals in meat by high pressure processing by describing the effect of the processing conditions on the reaction rate and the energy of activation was calculated, indicating high independence on the temperature at high pressures whereas the reaction was strongly dependent at atmospheric pressure.
TL;DR: In this article, a streamer discharge model is developed to analyze the characteristics of a pulsed positive streamers discharge in point-to-plane electrodes filled with oxygen-nitrogen mixed gas at room temperature and atmospheric pressure.
Abstract: A streamer discharge model is developed to analyse the characteristics of a pulsed positive streamer discharge in point-to-plane electrodes filled with oxygen–nitrogen mixed gas at room temperature and atmospheric pressure. In this paper we study the mechanisms of O and N radical production in an atmospheric-pressure streamer discharge. To confirm the validity of the simulation model, the discharge emission of light and the discharge current are compared with experimental data at several voltages in gas mixtures with 2–20% oxygen concentrations. The calculated streak picture and the axial distribution of streamer luminous intensity are in good agreement with our previous experimental results. After demonstrating the reliability of the model, we performed a numerical study on radical production by the streamer discharge. The experimentally obtained axial distributions of oxygen radical production in O2(20%)/N2 and nitrogen radical production in O2(2%)/N2 are successfully reproduced in our simulation. For the production of nitrogen radicals, two-step dissociation through the vibrationally excited states is predominant.
TL;DR: The model describes in a self-consistent manner the gas flow and heat transfer, the in-coupling of the microwave energy into the plasma, and the reaction kinetics relevant to high-pressure argon plasma including the contribution of molecular ion species.
Abstract: A two-dimensional model of microwave-induced plasma (field frequency 2.45 GHz) in argon at atmospheric pressure is presented. The model describes in a self-consistent manner the gas flow and heat transfer, the in-coupling of the microwave energy into the plasma, and the reaction kinetics relevant to high-pressure argon plasma including the contribution of molecular ion species. The model provides the gas and electron temperature distributions, the electron, ion, and excited state number densities, and the power deposited into the plasma for given gas flow rate and temperature at the inlet, and input power of the incoming TEM microwave. For flow rate and absorbed microwave power typical for analytical applications (200-400 ml/min and 20 W), the plasma is far from thermodynamic equilibrium. The gas temperature reaches values above 2000 K in the plasma region, while the electron temperature is about 1 eV. The electron density reaches a maximum value of about 4 × 10(21) m(-3). The balance of the charged particles is essentially controlled by the kinetics of the molecular ions. For temperatures above 1200 K, quasineutrality of the plasma is provided by the atomic ions, and below 1200 K the molecular ion density exceeds the atomic ion density and a contraction of the discharge is observed. Comparison with experimental data is presented which demonstrates good quantitative and qualitative agreement.