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Radial Structure of Normal and Abnormal Modes of the DC glow discharge
NASA Astrophysics Data System (ADS)
As is known dc glow discharge can burn in normal and abnormal modes. The aim of our work was to study the radial distribution of plasma density in both modes. Experiments were performed in the nitrogen pressure range p = 0.1 -- 2 Torr and the dc voltage range U < 600 V. It is shown that in the normal mode the discharge occupies only a part of the cathode area and the current density radial profile has a maximum at the center of the discharge spot and then it goes down rapidly to the border of the spot. With the dc current increasing the radial current density profile becomes broader and it's maximum value higher. The maximum value of the current density approaches a constant ``normal'' value before the transition of the discharge from the normal to the abnormal mode. In the abnormal mode the radial current density has almost a uniform profile across the electrode surface and the average current density increases with the dc current increasing.
Lisovskiy, Valeriy; Kharchenko, Nadiia; Yegorenkov, Vladimir
Abnormal glow discharge detection of visible radiation.
Extension of abnormal glow discharge detection of electromagnetic radiation to visible wavelengths is observed with inexpensive commercial indicator lamps. The spectral response and mechanisms of detection are discussed and advantages over gas-filled photodiodes noted. Responses from different discharge regions are observed and their implications considered. PMID:20165225
Kopeika, N S; Rosenbaum, J; Kastner, R
Normal Mode of DC Glow Discharge
We registered the normal current density j of the dc glow discharge in the nitrogen pressure range p = 0.3 - 10 Torr and determined the quantity j/p^2. Experiments were carried out in a T-shaped tube, the cathode was located at one end of the horizontal part of T, whereas another electrode (anode at the bottom of T) was grounded. Photos were taken through a window at the opposite end of the horizontal part of T exposing the cathode and the images were digitized. According to a generally accepted opinion this quantity j/p^2 had to remain constant on varying the current I in the normal mode. This proved to be valid only for p < 1 Torr. At higher pressure values the current growth was accompanied with a decrease of the quantity j/p^2. In a plasma column of small cross section the current density is larger to compensate for the increased loss of charged particles from the discharge volume.
Doppler spectroscopy of hydrogen and deuterium Balmer alpha line in an abnormal glow discharge
Microsoft Academic Search
The results of hydrogen and deuterium Balmer alpha line shapes and line intensities study in an abnormal glow discharge are reported and analyzed. The Doppler shifts along line wings are used to determine energies of excited hydrogen and deuterium atoms. For 12 different cathodes, intensity and shape of line wings are examined and dependence upon cathode material is determined. Tentative
M. R. Gemisic Adamov; Bratislav M. Obradovic; Milorad M. Kuraica; N. Konjevic
Self-assembled growth of carbon nitride nanocones using abnormal glow discharge
Crystalline carbon nitride nanocones with intact appearances and the minimum apex diameter of 2-3 nm have been grown vertically on Co-covered Si substrates, using the direct-current abnormal glow discharge plasma-assisted chemical vapor deposition method. The abnormal glow discharges for growth of carbon nitride nanocones were carried out in the ambience of mixtures of methane and nitrogen, with a total pressure of 30 Torr and a CH4/N2 pressure ratio of 1/50. Energy-dispersive X-ray spectroscopy and selected-area electron diffraction results indicated that the as-grown carbon nitride nanocones have the atomic [C]:[N] ratio of nearly 3:4 and the crystallinity close to the ?-C3N4 structure. Based on the characterizations and analyses for the as-grown carbon nitride nanocones, two main growth ways with different Co-layer thicknesses are presented.
Xu, X. F.; Xu, N.; Hu, W.; Wu, J. D.; Shen, Y. Q.; Ying, Z. F.
Study Of Titanium Emission Spectra In N2 - H2 Abnormal DC Glow Discharge
In this paper we tried to answer why small amount of hydrogen (3 %) in a nitrogen abnormal glow discharge so strongly reduce Ti I spectral line intensities. Decreasing of Ti I line intensities in N2 - H2 discharge are compared with less pronounced decreasing of N I line intensities. Using emission spectroscopy we have observed that line intensity changes are correlated to variations in electron energy distribution function (EEDF) and change of metastable density.
Obradovic, B. M.; Cvetanovic, N.; Kuraica, M. M.
Pulsed RF discharges, glow and filamentary mode at atmospheric pressure in argon
The properties of a pulsed radio frequency capacitive discharge are investigated at atmospheric pressure in argon. The discharge can operate in two different modes: a homogeneous glow discharge or turn into filaments. By pulsing the 13.56 MHz generator both the filamentary and the glow modes can be selected depending on the pulse width and period. For a 5 �s pulse width (~70 RF cycles in the pulse), short pulse periods (less than 100 �s) result in a filamentary discharge while long pulse periods (greater than 1 ms) result in a glow discharge. Optical emission spectroscopy and power measurements were performed to estimate the plasma temperature and density. Water vapour was introduced to the discharge as a source of hydrogen and the Stark broadening of the Balmer H? line was measured to allow the plasma density to be estimated as 1015 cm-3 in the filamentary mode. The estimation of the glow mode density was based on power balance and yielded a density of 5 � 1011 cm-3. Emission line ratio measurements coupled with the Saha equation resulted in an estimate of electron temperature of approximatively 1.3 eV for the glow mode and 1.7 eV for the filaments. Using the glow mode at a duty cycle of 10% is effective in decreasing the hydrophobicity of polymer films while keeping the temperature low.
Balcon, N.; Aanesland, A.; Boswell, R.
Array of surface-confined glow discharges in atmospheric pressure helium: Modes and dynamics
Array of atmospheric pressure surface discharges confined by a two-dimensional hexagon electrode mesh is studied for its discharge modes and temporal evolution so as to a theoretical underpinning to their growing applications in medicine, aerodynamic control, and environmental remediation. Helium plasma surface-confined by one hexagon-shaped rim electrode is shown to evolve from a Townsend mode to a normal and abnormal glow mode, and its evolution develops from the rim electrodes as six individual microdischarges merging in the middle of the hexagon mesh element. Within one hexagon element, microdischarges remain largely static with the mesh electrode being the instantaneous cathode, but move towards the hexagon center when the electrode is the instantaneous anode. On the entire array electrode surface, plasma ignition is found to beat an unspecific hexagon element and then spreads to ignite surrounding hexagon elements. The spreading of microdischarges is in the form of an expanding circle at a speed of about 3 � 104 m/s, and their quenching starts in the location of the initial plasma ignition. Plasma modes influence how input electrical power is used to generate and accelerate electrons and as such the reaction chemistry, whereas plasma dynamics are central to understand and control plasma instabilities. The present study provides an important aspect of plasma physics of the atmospheric surface-confined discharge array and a theoretical underpinning to its future technological innovation.
Li, D.; Liu, D. X.; Nie, Q. Y.; Li, H. P.; Chen, H. L.; Kong, M. G.
Optical Emission Spectroscopy Of Abnormal Glow Discharge In Nitrogen-Methane Mixtures At Atmospheric Pressure
The abnormal glow discharge was studied in electrode configuration corresponding to gliding arc arrangement with interelectrode gap of 2 mm at the discharge power up to 300 W in nitrogen-methane mixtures (0.5-2.5 % of methane) at atmospheric pressure. Both gases had purity better than 99.999 % and the whole system was evacuated before measurement to suppress oxygen traces. Optical emission spectra were taken in dependence on applied power and gas mixture composition. Nitrogen and CN radical spectra as well as atomic lines of hydrogen and carbon were identified. The vibrational temperatures of 2300-8000 K were determined from the spectra of nitrogen second positive, CN violet and C2 spectral systems. Rotational temperature calculated from nitrogen second positive and CN violet 0-0 bands varied in the interval of 1200-4800 K depending on the experimental conditions.
Krcma, F.; Klohnova, K.; Polachova, L.; Horvath, G.
Excitation frequency dependent mode manipulation in radio-frequency atmospheric argon glow discharges
An experimental investigation is presented to characterize the dependence of discharge operation modes (? and ? modes) and their transition on excitation frequency in radio-frequency atmospheric argon glow discharges. The current-voltage characteristics are used to distinguish the ? and ? modes at an excitation frequency range of 5-24 MHz. The operation regime of ? mode with stable and uniform discharge in large volume is found to expand at higher excitation frequency. It is shown that, when excitation frequency is below 10 MHz, the discharge evolves directly into ? mode after gas breakdown and, when excitation frequency is above 10 MHz, the discharge operates in the coexistence mode of ? and ? after mode transition.
Zhang, Jie; Ding, Ke; Wei, Kaya; Zhang, Jing; Shi, Jianjun
CF4 decompositions using streamer- and glow-mode in dielectric barrier discharges
A Dielectric barrier discharge (DBD) is a promising candidate to remove carbon tetrafluoride (CF4) because the DBD has been successfully used for generating ozone (O3) and decomposing nitrogen oxide (NO). A streamer- and glow-mode operations of DBD were carried out in a coaxial cylinder reactor by coupling 10-kHz alternate current (ac) power. The effect of oxygen on the CF4 decompositions
Yongho Kim; Kwan-Tae Kim; Min Suk Cha; Young-Hoon Song; Seock Joon Kim
Study of the electron kinetics in abnormal dc glow discharges in oxygen by a multiterm approach and Monte Carlo simulations
The nonequilibrium properties of the electron component in gas discharge plasmas determine decisively the behavior of the whole discharge. These properties are commonly determined by solving the electron Boltzmann equation using a multiterm approximation of the Legendre polynomial expansion of the electron momentum distribution function or by performing Monte Carlo simulations. For comparative kinetic studies of spatially inhomogeneous plasmas, consistent conditions at the spatial margins of the discharge arrangement are required. Extended boundary conditions at the electron emitting cathode are represented, which are adequate for the direct comparison of multiterm Boltzmann equation calculations and Monte Carlo simulations. First results for dc discharges in oxygen at conditions typical of abnormal glow discharges are discussed. The excellent agreement between the results of both the independent kinetic approaches verifies the extended boundary conditions deduced.
Grubert, Gordon K.; Loffhagen, Detlef
Electric field distribution in the cathode-fall region of an abnormal glow discharge in hydrogen: experiment and theory
We present the results of an experimental and theoretical study of the electric field distribution in the cathode-fall (CF) region of an obstructed abnormal glow discharge in hydrogen. The distribution of electric field strength was measured using an improved Stark polarization spectroscopy technique of the hydrogen Balmer beta line profile. The developed technique extends field measurements to the low-field region while remaining in good agreement at larger field strengths with the well established Stark polarization peak separation electric field measurement technique. The experimental electric field distribution is modeled by a simple analytical formula, adopted after consideration of elementary processes relevant in the CF. It fits the experimental distribution within error bars and consequently enables determination of the CF parameters such as its thickness and the mean free path for electrons in the CF region.
Spasojevi?, Dj; Steflekova, V.; �i�ovi?, N. M.; Konjevi?, N.
Issledovanie ehnergeticheskoj funktsii raspredeleniya ionov, postupayushchikh na katod anomal'nogo tleyushchego razryada. (Investigation of the energy distribution of ions, striking the cathode in an abnormal glow discharge).
National Technical Information Service (NTIS)
The energy spectrum of ions at the cathode in an abnormal glow discharge has been investigated for gases H(sub 2), D(sub 2), He, Ar at discharge current densities j(sub a)(approx)>10mA/cm(sup 2) and gas pressures p(approx)>1 Torr. It is shown that ion ene...
A. A. Gurin K. L. Kruglikov A. Pan'kin V. M. Slobodyan
Study of nonlinear oscillations in a glow discharge plasma using empirical mode decomposition and Hilbert Huang transform
Hilbert Huang transform (HHT) based time series analysis was carried out on nonlinear floating potential fluctuations obtained from hollow cathode glow discharge plasma in the presence of anode glow. HHT was used to obtain contour plots and the presence of nonlinearity was studied. Frequency shift with time, which is a typical nonlinear behaviour, was detected from the contour plots. Various plasma parameters were measured and the concepts of correlation coefficients and the physical contribution of each intrinsic mode function have been discussed. Physically important quantities such as instantaneous energy and their uses in studying physical phenomena such as intermittency and non-stationary data have also been discussed.
Wharton, A. M.; Sekar Iyengar, A. N.; Janaki, M. S.
Nitrogen Plasma Ion Implantation of Al and Ti alloys in the High Voltage Glow Discharge Mode
Enhanced surface properties can be attained for aluminum and its alloys (mechanical and tribological) and Ti6Al4V (mainly tribological) by Plasma Immersion Ion Implantation (PIII) technique. The main problem here, more severe for Al case, is the rapid oxygen contamination even in low O partial pressure. High energy nitrogen ions during PIII are demanded for this situation, in order to enable the ions to pass through the formed oxide layer. We have developed a PIII system that can operate at energies in excess of 50keV, using a Stacked Blumlein (SB) pulser which can nominally provide up to 100 kV pulses. Initially, we are using this system in the High Voltage Glow Discharge (HVGD) mode, to implant nitrogen ions into Al5052 alloy with energies in the range of 30 to 50keV, with 1.5?s duration pulses at a repetition rate of 100Hz. AES, pin-on-disc, nanoindentation measurements are under way but x-ray diffraction results already indicated abundant formation of AlN in the surface for Al5052 treated with this HVGD mode. Our major aim in this PIII experiment is to achieve this difficult to produce stable and highly reliable AlN rich surface layer with high hardness, high corrosion resistance and very low wear rate.
Oliveira, R. M.; Ueda, M.; Rossi, J. O.; Reuther, H.; Lepienski, C. M.; Beloto, A. F.
Default Mode Network Abnormalities in Bipolar Disorder and Schizophrenia
PubMed Central
The default-mode network (DMN) consists of a set of brain areas preferentially activated during internally focused tasks. We used functional MRI to study the DMN in bipolar mania and acute schizophrenia. 17 bipolar disorder (BD), 14 schizophrenia (SZ) and 15 normal control (NC) subjects underwent 10-minute resting scans. The DMN was extracted using independent component analysis and template-matching; spatial extent and timecourse were examined. Both patient groups showed reduced DMN connectivity in the medial prefrontal cortex (mPFC) (BD:x=-2,y=54,z=-12; SZ:x=-2,y=22,z=18). BD subjects showed abnormal recruitment of parietal cortex (correlated with mania severity) while SZ subjects showed greater recruitment of the frontopolar cortex/basal ganglia. Both groups had significantly higher frequency fluctuations than controls (frequency � diagnosis:F(43,2)=3.183,p=0.05). We found ventral mPFC abnormalities in BD and dorsal mPFC abnormalities in SZ. The higher frequency of BOLD signal oscillations observed in patients suggests abnormal functional organization of circuits in both disorders. Further studies are needed to determine how these abnormalities are related to specific symptoms of each condition.
Ongur, Dost; Lundy, Miriam; Greenhouse, Ian; Shinn, Ann K.; Menon, Vinod; Cohen, Bruce M.; Renshaw, Perry F.
Abnormal activity of default mode network in GERD patients
Background Abnormal processing of esophageal sensation at the level of the central nervous system has been proven to be involved in gastroesophageal reflux disease (GERD). However, most studies were focused on the possible functions of perceptual processing related network during task status, little attention has been paid to default mode network, which has been manifested to be important in the pathogenesis of many diseases. In our study, we compared the brain activity characteristic in GERD patients with the healthy subjects (HS) at baseline, looking for whether activities of default mode network were abnormal in GERD patients and attempting to identify their possible roles in GERD. In present study, fractional amplitude of low-frequency fluctuation was adopted to detect the brain activities at baseline. Group-level analyses were conducted by one-sample t test within groups (voxel thresholds were p?0.001 and cluster level >42, corrected P?0.05) and independent-samples t test between groups (p?0.01 and cluster level >90, corrected P?0.05) using SPM5. Results The predominant activity area in both groups mainly located in default mode network such as medial superior frontal gyrus, precuneus, posterior cingulate gyrus, etc. However, the activities of precuneus and posterior cingulate gyrus were significantly lower in GERD patients than those in the HS. Conclusions The activities of precuneus and posterior cingulate gyrus of default mode network in GERD patients were significantly lower compared to the HS, suggesting abnormal activities of brain regions in default mode network may be involved in pathophysiology of GERD symptom generation.
The energy distributions of major ions in the cathode zone of a strongly abnormal nitrogen DC glow discharge
Energy distributions of N+ and N2+ ions bombarding the aluminium cathode of a glow discharge at high current densities (few mA cm?2) have been calculated and compared with experimentally determined values. The results show a high proportion of N+ compared to (N1+ + N2+) which are characteristic of a nitrogen discharge and arise from the small value of the cross-section
Z Wronski; H Murlak-Stachura
Monte Carlo simulation for excessive Balmer line broadening generated by transport of fast H Atoms in an abnormal glow discharge
Monte Carlo code for fast hydrogen atom transport and generating of excessively Doppler broadened profiles based on the collision model is presented. Results for the initial monoenergetic atom beam and for a more realistic energy distribution of H atoms are reported. Line profiles obtained from the simulation are compared to our experimentally obtained data. Initial energy distribution for atoms is approximately calculated from the measured line profiles while the initial angle distribution was taken to be cosine. Balmer alpha intensity was found to exponentially decay in the negative glow region, which concurs with the experimental results. These agreements between the simulation and experiment support the collision model for excessive line broadening.
Cvetanovi?, N.; Obradovi?, B. M.; Kuraica, M. M.
Consequences of the local-mean-energy and the local-field approximation on the similarity parameters of abnormal glow discharges
The local-mean-energy approximation and the local-field approximation are commonly applied to include the electron properties like transport and rate coefficients into a hydrodynamic description of gas discharge plasmas. Both the approaches base on the solution of the stationary, spatially homogeneous Boltzmann equation for the electron component, but the consequences of these approaches differ drastically. In particular, the similarity parameters of abnormal glow discharges can be used to illustrate the applicability of both the approximations. Additionally, the influence of rough and extended reaction kinetics has been studied. The analysis of discharges in argon and oxygen as representatives of rare and reactive gases, respectively, leads to the conclusion that the local-mean-energy approximation is to be strongly recommended for the application to hydrodynamic descriptions of discharge plasmas.
Grubert, Gordon K.; Becker, Markus M.; Loffhagen, Detlef
Organic chemistry of NH3 and HCN induced by an atmospheric abnormal glow discharge in N2-CH4 mixtures
The formation of the chemical products produced in an atmospheric glow discharge fed by a N2-CH4 gas mixture has been studied using Fourier Transform InfraRed (FTIR) and Optical Emission Spectrometry (OES). The measurements were carried out in a flowing regime at ambient temperature and pressure with CH4 concentrations ranging from 0.5% to 2%. In the recorded emission spectra the lines of the second positive system CN system and the first negative system of N2 were found to be the most intensive but atomic H?, H?, and C (247 nm) lines were also observed. FTIR-measurements revealed HCN and NH3 to be the major products of the plasma with traces of C2H2. These same molecules have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere with these smaller species believed to be the precursors of heavier organic species in Titan's atmosphere and on its surface.
Horvath, G.; Krcma, F.; Polachova, L.; Klohnova, K.; Mason, N. J.; Zahoran, M.; Matejcik, S.
AC Glow Discharge Plasma in N2O
SciTech Connect
This paper considers the optical and electrical characterization of AC glow discharge plasma in the abnormal glow mode used for optical emission spectroscopy. The total discharge current and applied voltage are measured using conventional techniques. The electrical characteristics of the planer-cathode glow discharge confirmed that the plasma is operating at abnormal discharge mode characterized by the increases in the operating voltage as the current was raised under given pressure. Optical emission spectroscopy was used to determine the main emission lines of the glow discharge plasma of N2O at pressures between 0.5 and 4.0 Torr. It shows that the discharge emission range is mainly within 300-400 nm. The emission lines correspond to NO, O2, and O{sub 2}{sup +} are the dominant lines in the glow discharge plasma in the present study. Intensity of the emission lines show linear increase with the discharge current up to 0.4 A followed by saturation at higher currents. No emission lines were observed in this work corresponding to atomic oxygen or nitrogen.
Yousif, F. B.; Martinez, H.; Robledo-Martinez, A.; Castillo, F. [Facultad de Ciencias-Universidad Autonoma del Estado de Morelos, Avenida. Universidad, no. 1001, Colonia Chamilpa, C.P. 62210, Cuernavaca, Morelos (Mexico); Centro de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos, P.O. Box 48-3, 62251, Cuernavaca, Morelos (Mexico); Universidad Autonoma Metropolitana Azcopotzalco, Mexico, D.F (Mexico); Instituto de Ciencias Nucleares, UNAM, Mexico, D.F. (Mexico)
Glowing Pickle
NSDL National Science Digital Library
In this activity, high voltage is applied across a pickle to emit a yellow glow. This activity should only be conducted by skilled adults and is best suited as a demonstration. Optional extensions to this activity include soaking the pickle for week in brine to emit a pink glow and using several pickles at once.
Doherty, Paul
Glowing Veggies.
ERIC Educational Resources Information Center
Extends the work of Weimer and Battino in electrical conductivity demonstrations creating "glowing" vegetables (see article this issue) to other vegetables and the spectra generated by other elements other than the sodium in pickle brines. Describes a study on the effect of concentration and voltage on glow intensity. (MKR)
Scharlin, Pirketta; And Others
Sputter crater formation in the case of microsecond pulsed glow discharge in a Grimm-type source. Comparison of direct current and radio frequency modes
Depth profiling with pulsed glow discharge is a promising technique. The application of pulsed voltage for sputtering reduces the sputtering rate and thermal stress and hereby improves the analysis of thin layered and thermally fragile samples. However pulsed glow discharge is not well studied and this limits its practical use. The current work deals with the questions which usually arise when the pulsed mode is applied: Which duty cycle, frequency and pulse length must be chosen to get the optimal sputtering rate and crater shape? Are the well-known sputtering effects of the continuous mode valid also for the pulsed regime? Is there any difference between dc and rf pulsing in terms of sputtering? It is found that the pulse length is a crucial parameter for the crater shape and thermal effects. Sputtering with pulsed dc and rf modes is found to be similar. The observed sputtering effects at various pulsing parameters helped to interpret and optimize the depth resolution of GD OES depth profiles.
Efimova, Varvara; Hoffmann, Volker; Eckert, J�rgen
Glowing Tonic
In this sunny day activity, learners compare how a cup of water and a cup of tonic water reflect or refract light in the sun. Learners will be surprised to observe the top of the tonic water "glowing" blue. This activity includes articles explaining the reflection and refraction of light.
America, Optical S.
Two-Dimensional Numerical Simulation of the DC Glow Discharge in the Normal Mode and with Einstein's Relation of Electron Diffusivity
This paper presents an investigation of a DC glow discharge at low pressure in the normal mode and with Einstein's relation of electron diffusivity. Two-dimensional distributions in Cartesian geometry are presented in the stationary state, including electric potential, electron and ion densities, longitudinal and transverse electrics fields as well as electron temperature. Our results are compared with those obtained in existing literature. The model used in this work is based on the first three moments of Boltzmann's equation. They serve as the continuity equation, the momentum transfer and the energy equations. The set of equations for charged particles presented in monatomic argon gas are coupled in a self-consistent way with Poisson's equation. A parametric study varying the cathode voltage, gas pressure, and secondary electron emission coefficient predicts many of the well-known features of DC discharges.
Bouchikhi, A.
Multiple solutions in the theory of dc glow discharges
Multiple steady-state solutions existing in the theory of dc glow discharges are computed for the first time. The simulations are performed in 2D in the framework of the simplest self-consistent model, which accounts for a single ion species and employs the drift-diffusion approximation. Solutions describing up to nine different modes were found in the case where losses of the ions and the electrons due to diffusion to the wall were neglected. One mode is 1D, exists at all values of the discharge current, and represents in essence the well-known solution of von Engel and Steenbeck. The other eight modes are axially symmetric, exist in limited ranges of the discharge current, and are associated with different patterns of current spots on the cathode. The mode with a spot at the centre of the cathode exhibits a well pronounced effect of normal current density. Account of diffusion losses affects the solutions dramatically: the number of solutions is reduced, a mode appears that exists at all discharge currents and comprises the Townsend, subnormal, normal and abnormal discharges. The solutions that exist in limited current ranges describe patterns, and these patterns seem to represent axially symmetric analogues of the 3D patterns observed in dc glow microdischarges in xenon.
Almeida, P. G. C.; Benilov, M. S.; Faria, M. J.
Glow plug alternator control
An apparatus for controlling the resistance of a glow plug over various operating temperature ranges of an internal combustion engine is described. The apparatus is electrically powered by a first alternator and comprises: means for determining the resistance of the glow plug, comparing the glow plug resistance with a preselected glow plug resistance, and delivering a resistance error signal in response to a difference between the compared signals; and second alternator means for delivering a voltage signal to the glow plug and controlling the glow plug's resistance relative to the preselected resistance in response to receive the resistance error signal.
Verheyen, M.R.
The effect of power balance on the heating mode transition in micro-dielectric barrier helium glow discharges
A particle-in-cell simulation has been adapted to analyze the helium discharge characteristics of a planar micro-dielectric barrier discharge with a gap distance less than 100 �m for variation of driving frequency from 10 to 500 MHz. Two scaling laws for the breakdown voltage were obtained with the change in heating mechanism from the ?- to the ?-mode with increasing frequency. The optimal condition for the efficient generation of high-density plasmas with minimized power is obtained when the ratio of ion transit time to the RF period is about 1/4, so that the secondary electrons emitted by ion bombardment on the dielectric-gap boundary are accelerated in phase with the sheath potential. Under this condition, the plasma density as well as the ion current is maximum, the displacement current and the electron current are almost the same, and the ratio of the power delivered to the plasma is 50% of the total power. At high frequencies, the collisional electron heating increases by the induced bulk electric field, enhancing excitation and elastic collisions, and thus ionization efficiency decreases while excitation efficiency increases.
Lee, Jung Yeol; Bae, Hyo Won; Lee, Hae June; Verboncoeur, John P.
Phenomena of oscillations in atmospheric pressure direct current glow discharges
Self-sustained oscillations in a dc glow discharge with a semiconductor layer at atmospheric pressure were investigated by means of a one-dimensional fluid model. It is found that the dc glow discharge initially becomes unstable in the subnormal glow region and gives rise to oscillations of plasma parameters. A variety of oscillations with one or more frequencies have been observed under different conditions. The discharge oscillates between the glow discharge mode and the Townsend discharge mode in the oscillations with large amplitude while operates in the subnormal glow discharge mode all the while in the oscillations with small amplitude. Fourier Transform spectra of oscillations reveal the transition mechanism between different oscillations. The effects of semiconductor conductivity on the oscillation frequency of the dominant mode, gas voltage, as well as the discharge current have also been analyzed.
Liu, Fu-cheng [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)] [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Yan, Wen; Wang, De-zhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
Glow in the Dark
Learners experiment to see which colors of light will cause a phosphorescent (glow-in-the-dark) material to glow. Different colors of light have different wavelengths, and different amounts of energy. Only the colors which shine with sufficient energy can charge up the phosphorescent material enough to glow in the dark. This activity starts on p.26 of the manual. This manual contains four activities related to the Spectra: The Original Laser Superhero Force comic book published by the American Physical Society.
Thompson-Flagg, Rebecca; Johnson, Kerry G.
Glowing in the Dark
In this activity, learners explore phosphorescence and how certain materials can absorb and store energy from a light source. Learners use critical thinking skills to hypothesize which type of light -- incandescent, ultraviolet, infrared or fluorescent -- will produce the brightest glow from a glow-in-the-dark star. Learners perform an experiment using cameras to observe the intensity of the resulting glow from each type of light source.
Friday, Science
Pressure and Discharge-Voltage Dependence of Self-Sustaining Pulses in Air-Glow Discharge
The details of formation of micro discharges in air-glow discharge plasma are experimentally studied. The number of micro discharges formed per second is strongly related to both pressure and discharge voltage. This number tends to show reflections of the Patchen curve as far as its pressure dependence is concerned. The discharge-voltage dependence indicates that the transition from normal to abnormal glow discharge is not a sudden one, but has its roots during the normal glow stage and is initiated by the micro discharges which can be regarded as the early stage of abnormal glow.
A. Azooz, A.; A. Al-Jawaady, Y.; T. Ali, Z.
Glow discharge detector
A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured.
Koo, Jackson C. (San Ramon, CA); Yu, Conrad M. (Antioch, CA)
Bifurcations of current transfer through a collisional sheath with ionization and self-organization on glow cathodes.
A bifurcation analysis is performed of a dc glow discharge between parallel electrodes and of a dc near-cathode space-charge sheath bordering a uniform plasma column. A model of plasma is considered with a single ion species and motion of the charged particles dominated by drift. Bifurcation points are found at which steady-state modes with spots on the cathode branch off from the abnormal mode or from the mode corresponding to the falling section of the current-density-voltage characteristic. In both discharge configurations, bifurcations in the abnormal mode have been detected; an unexpected result given that loss of stability and pattern appearance in dc gas discharges are usually associated with a negative differential resistance of the discharge. The conclusion is drawn that the two most important mechanisms governing appearance of patterns on glow cathodes, which are electrostatic mechanism and diffusion, produce competing effects: the former favors appearance of modes with multiple spots, while the latter favors appearance of a mode with one spot. This may explain the appearance in experiments of a normal spot or, alternatively, of patterns with multiple spots. PMID:18517534
Benilov, M S
Glow Discharge Microphone.
A microphone employing an electrical glow discharge as the sensing element was developed for the detection and measurement of acoustic pressure fields at ultrasonic frequencies. The construction and operating characteristics of two versions of the microph...
R. W. Hermsen W. R. Babcock
Three-dimensional volume-rendered imaging of normal and abnormal fetal fluid-filled structures using inversion mode.
A total of six normal and eight abnormal fetuses at 16-38?weeks of gestation were studied using transabdominal three-dimensional sonography with an inversion mode. In normal fetuses, the stomach, gallbladder and bladder could be depicted. In particular, peristalsis of the stomach was noted. In the case of holoprosencephaly, fused hemispheres were evident. In the case of hydrocephalus, the enlargement of ventricular cavities was noted. In the case of bilateral pleural effusion, the spatial relationship and size of the effusions were depicted. In the case of meconium peritonitis, the spatial relationship between the dilated intestines and ascites was depicted. In two cases of hydronephrosis, the dilated renal pelvis and calyces were clearly shown. In the case of multicystic dysplastic kidney, the number and size of cysts were clearly identified. In the case of left ovarian cyst, the anatomical relationships among the ovarian cyst, kidney, stomach and bladder could be easily understood. PMID:21790889
Hata, Toshiyuki; Mori, Nobuhiro; Tenkumo, Chiaki; Hanaoka, Uiko; Kanenishi, Kenji; Tanaka, Hirokazu
Abnormal functional connectivity of default mode sub-networks in autism spectrum disorder patients
Autism spectrum disorders (ASDs) are characterized by deficits in social and communication processes. Recent data suggest that altered functional connectivity (FC), i.e. synchronous brain activity, might contribute to these deficits. Of specific interest is the FC integrity of the default mode network (DMN), a network active during passive resting states and cognitive processes related to social deficits seen in ASD, e.g. Theory of Mind. We investigated the role of altered FC of default mode sub-networks (DM-SNs) in 16 patients with high-functioning ASD compared to 16 matched healthy controls of short resting fMRI scans using independent component analysis (ICA). ICA is a multivariate data-driven approach that identifies temporally coherent networks, providing a natural measure of FC. Results show that compared to controls, patients showed decreased FC between the precuneus and medial prefrontal cortex/anterior cingulate cortex, DMN core areas, and other DM-SNs areas. FC magnitude in these regions inversely correlated with the severity of patients' social and communication deficits as measured by the Autism Diagnostic Observational Schedule and the Social Responsiveness Scale. Importantly, supplemental analyses suggest that these results were independent of treatment status. These results support the hypothesis that DM-SNs under-connectivity contributes to the core deficits seen in ASD. Moreover, these data provide further support for the use of data-driven analysis with resting-state data for illuminating neural systems that differ between groups. This approach seems especially well suited for populations where compliance with and performance of active tasks might be a challenge, as it requires minimal cooperation.
Assaf, Michal; Jagannathan, Kanchana; Calhoun, Vince D.; Miller, Laura; Stevens, Michael C.; Sahl, Robert; O'Boyle, Jacqueline G.; Schultz, Robert T.; Pearlson, Godfrey D.
Acoustic Interaction with the Positive Column of a Neon Glow Discharge.
Compressive acoustic pulses were produced by an impulsive abnormal-glow discharge and the interaction of these pulses with the positive column of a dc neon glow discharge was studied. The acoustic pulses are analyzed and are found to be infinitesimal ampl...
R. D. S. Melville
Numerical Study on Glow Discharge of IEC Fusion
An inertial electrostatic confinement (IEC) fusion device is possibly used for the neutron source that has the ability to produce the neutrons of 10{sup 5}-10{sup 8}/s by the glow discharge. It works more efficiently at the condition of the high voltage and the low pressure. It, however, is difficult to keep the continuous operation at the low-pressure because the glow discharge is apt to be unstable. We have made the three-dimensional Monte Carlo PIC code including atomic processes to investigate the glow discharge. The study reveals the spatial position where the ionization occurs and numerically reproduces the discharge called 'star mode'.
Osawa, Hodaka; Tabata, Takehiro; Ohnishi, Masami [Kansai University (Japan)
Scherer, David; Sherwood, Bruce
Glow discharge mass spectrometry
Over the past twenty�years or so, glow discharge mass spectrometry (GDMS) has become the industry standard for the analysis of trace elements in metals and semiconductors. A review of its history is followed by a picture of the present situation and a look to where the future may lie. Applications are summarised, including the ability of GDMS to offer depth-resolved
Volker Hoffmann; Martin Kasik; Peter K. Robinson; Cornel Venzago
Structural and Functional Abnormalities of Default Mode Network in Minimal Hepatic Encephalopathy: A Study Combining DTI and fMRI
Background and Purpose Live failure can cause brain edema and aberrant brain function in cirrhotic patients. In particular, decreased functional connectivity within the brain default-mode network (DMN) has been recently reported in overt hepatic encephalopathy (HE) patients. However, so far, little is known about the connectivity among the DMN in the minimal HE (MHE), the mildest form of HE. Here, we combined diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) to test our hypothesis that both structural and functional connectivity within the DMN were disturbed in MHE. Materials and Methods Twenty MHE patients and 20 healthy controls participated in the study. We explored the changes of structural (path length, tracts count, fractional anisotropy [FA] and mean diffusivity [MD] derived from DTI tractography) and functional (temporal correlation coefficient derived from rs-fMRI) connectivity of the DMN in MHE patients. Pearson correlation analysis was performed between the structural/functional indices and venous blood ammonia levels/neuropsychological tests scores of patients. All thresholds were set at P<0.05, Bonferroni corrected. Results Compared to the healthy controls, MHE patients showed both decreased FA and increased MD in the tract connecting the posterior cingulate cortex/precuneus (PCC/PCUN) to left parahippocampal gyrus (PHG), and decreased functional connectivity between the PCC/PCUN and left PHG, and medial prefrontal cortex (MPFC). MD values of the tract connecting PCC/PCUN to the left PHG positively correlated to the ammonia levels, the temporal correlation coefficients between the PCC/PCUN and the MPFC showed positive correlation to the digital symbol tests scores of patients. Conclusion MHE patients have both disturbed structural and functional connectivity within the DMN. The decreased functional connectivity was also detected between some regions without abnormal structural connectivity, suggesting that the former may be more sensitive in detecting the early abnormalities of MHE. This study extends our understanding of the pathophysiology of MHE.
Zhong, Jianhui; Zheng, Gang; Wu, Shengyong; Zhang, Zhiqiang; Liao, Wei; Zhong, Yuan; Ni, Ling; Jiao, Qing; Zhang, Zongjun; Liu, Yijun; Lu, Guangming
Science Nation: Glowing Squid
In deep ocean waters, it's sometimes difficult to hide from predators. That's why so many sea creatures have evolved extraordinary methods of disguise. Cephalopods, such as octopus, squid and cuttlefish, are big on camouflage, by day or night. In fact, the Hawaiian bobtail squid has several means of stealthy self- preservation. With support from the National Science Foundation (NSF), a team from the University of Wisconsin-Madison study one bobtail squid camouflage scheme; one that glows in the dark!
Origin of the Shuttle glow
NASA Technical Reports Server (NTRS)
On a recent Shuttle mission four gases, NO, CO2, Xe, and Ne were released for a plasma experiment. Unintentionally, enough gas was scattered onto the surfaces of the Shuttle tail that when NO was released a much more intense version of Shuttle glow was observed. The other gases did not affect the normal Shuttle glow. Under normal conditions the adsorbed NO that causes the glow probably come either from the ambient atmosphere or from reactions in exhaust gases from the Shuttle thrusters.
Viereck, R. A.; Murad, Edmond; Pike, C. P.; Green, B. D.; Joshi, P.; Hieb, R.; Harbaugh, G.
Experimental investigation of hybrid-evaporation-glow discharge plasma immersion ion implantation
High-voltage pulsed glow discharge is applied to plasma immersion ion implantation (PIII). In the glow discharge, the target constitutes the cathode and the gas tube forms the anode under a relatively high working gas pressure of 0.15-0.2 Pa. The characteristics of the glow discharge and ion density are measured experimentally. Our results show resemblance to hollow-anode glow discharge and the anode fall is faster than that of general glow discharge. Because of electron focusing in the anode tube orifice, ions are ionized efficiently and most of them impact the negatively biased samples. The resulting ion current density is higher than that in other PIII modes and possible mechanisms of the glow discharge PIII are proposed and discussed.
Li, L.H.; Wu, Y.Q.; Zhang, Y.H.; Fu, Ricky K.Y.; Chu, Paul K. [Department of 702, School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)
Transition of Discharge Mode of a Local Hollow Cathode Discharge
The discharge characteristics of hollow cathode discharge in argon in a cylindrical cavity are investigated experimentally. The voltage-current (V - I) characteristics and the light emission are measured. It is found that the discharge plasma is localized inside the hollow cavity, with an extensive Faraday dark space between the cathode and the anode. The discharge develops from predischarge to abnormal glow discharge, the hollow cathode effect (HCE) and a hybrid mode as the discharge current increases. The onset of the HCE is found for the first time by the transition from abnormal glow discharge together with a significant decrease in the slope of the V - I curve which shows a positive differential resistivity. The voltage increases proportionally with the current when the HCE is reached.
Li, Shang; Ouyang, Ji-Ting; He, Feng
Cryptograpy of the Glowing Hieroglyphs.
The kirlian effect is attributed to the hypothesis that all living tissue give off its own individual glow in a high-frequency field. This glow reflects the anatomical features of the object being photographed, but is distinguished by its mobility and dyn...
Powerful glow discharge excilamp
A powerful glow discharge lamp comprising two coaxial tubes, the outer tube being optically transparent, with a cathode and anode placed at opposite ends of the tubes, the space between the tubes being filled with working gas. The electrodes are made as cylindrical tumblers placed in line to one other in such a way that one end of the cathode is inserted into the inner tube, one end of the anode coaxially covers the end of the outer tube, the inner tube penetrating and extending through the anode. The increased electrodes' surface area increases glow discharge electron current and, correspondingly, average radiation power of discharge plasma. The inner tube contains at least one cooling liquid tube placed along the axis of the inner tube along the entire lamp length to provide cathode cooling. The anode has a circumferential heat extracting radiator which removes heat from the anode. The invention is related to lighting engineering and can be applied for realization of photostimulated processes under the action of powerful radiation in required spectral range.
Tarasenko, Victor F. (Tomsk, RU); Panchenko, Aleksey N. (Tomsk, RU); Skakun, Victor S. (Tomsk, RU); Sosnin, Edward A. (Tomsk, RU); Wang, Francis T. (Danville, CA); Myers, Booth R. (Livermore, CA); Adamson, Martyn G. (Danville, CA)
SKIRT Space Shuttle glow experiment
This paper describes a spectrometer/radiometer experiment to obtain infrared, visible, and ultraviolet measurements of Space Shuttle glow. The payload, Spacecraft Kinetic Infrared Test (SKIRT), is a cryogenic circular variable filter infrared spectrometer with a number of infrared, visible, and ultraviolet radiometers covering the spectral range of 0.2-5.4 microns and 9.9-10.3 microns. It will measure Shuttle glow as a function of mission elapsed time, orbiter attitude, temperature, and orbiter events such as thruster firings. The measured data should have sufficient spectral resolution and sensitivity to identify molecular species contributing to Shuttle glow emissions. SKIRT is manifested on STS-39.
Ahmadjian, M.; Jennings, D. E.; Mumma, M. J.; Green, B. D.; Dix, B. D.; Russell, R. W.
Spectroscopic investigations of a cathode fall region of the Grimm-type glow discharge
This paper presents the results of the spectroscopic study of the cathode fall region of a plane cathode Grimm-type glow discharge in pure hydrogen and in argon with small admixtures of hydrogen. In contrast with the discharge in an argon-hydrogen mixture, the volt-ampere characteristics of the pure hydrogen discharge show a maximum typical for an abnormal glow-to-arc transition. This maximum
I. R. Videnovi?; N. Konjevi?; M. M. Kuraica
Self-Adjusting Characterization for Steady-State, Direct Current Cathode-Dominated Glow Discharge Plasmas at High Pressures
A steady-state, direct-current high-pressure CH4-H2 glow discharge in a cup-shaped cathode parallel to anode configuration is investigated by using their V�I characteristics and CCD images. The discharges display an abnormal glow feature, and an expansion of a negative glow is observed on the cathode sidewall with the increasing discharge current. There exists a dependence of voltage on gas pressure for different fixed currents. The voltage decreases with gas pressure initially, and then increases conversely, which is correlated with the glow states of the cathode sidewall. This study exhibits a self-adjusting characterization for plasmas in cathode fall, which is important for maintaining steady-state, abnormal glow discharge in a relatively high pressure range.
Ding, Fang; Zheng, Shi-Jian; Ke, Bo; Tang, Zhong-Liang; Zhang, Yi-Chuan; Yang, Kuan; Xie, Xin-Hua; Zhu, Xiao-Dong
Mechanistic investigations of shuttle glow
A series of laboratory measurements have been performed in order to provide a mechanistic interpretation for the visible shuttle glow. These studies involved interactions of an 8 km/s oxygen atom beam with both contaminant dosed surfaces and gaseous targets. We conclude that visible shuttle glow arises from surface mediated O + NO recombination via a Langmuir-Hinshelwood mechanism and that the gas-phase exchange reaction O + N2 - NO + N provides a viable source of precursor NO above surfaces oriented in the ram direction.
Caledonia, G. E.; Holtzclaw, K. W.; Krech, R. H.; Sonnenfroh, D. M.; Leone, A.; Blumberg, W. A. M.
Direct current glow discharges in atmospheric air
A microhollow cathode discharge was used as plasma cathode to sustain a stable direct current glow discharge in atmospheric pressure air. The length of the glow discharge column was varied from 1 mm to 2 cm, with the sustaining voltage increasing linearly with length. For glow discharges with currents on the order of 10 mA, the electron density in the
Abdel-Aleam H. Mohamed; R. Block; K. H. Schoenbach
GlowFit�a new tool for thermoluminescence glow-curve deconvolution
A new computer program, GlowFit, for deconvoluting first-order kinetics thermoluminescence (TL) glow-curves has been developed. A non-linear function describing a single glow-peak is fitted to experimental points using the least squares Levenberg�Marquardt method. The main advantage of GlowFit is the ability to resolve complex TL glow-curves consisting of strongly overlapping peaks, as those observed in heavily-doped LiF:Mg,Ti (MTT) detectors. This
M. Puchalska; P. Bilski
Second Workshop on Spacecraft Glow
Various aspects of space glow were considered. Results of a workshop held on May 6 to 7, 1985, at the Space Science Laboratory of NASA/Marshall Space Flight Center, Huntsville, Alabama are presented. The topics of discussion are divided as follows: (1) in situ observations; (2) theoretical calculations; (3) laboratory measurements; and (4) future experiments.
Waite, J. H., Jr. (editor); Moorehead, T. W. (editor)
Glow discharge initiation with electron gun assist
Helium glow discharge conditioning is used before every discharge in the D3-D Tokamak to desorb hydrogen and low Z impurities from the graphite and Inconel plasma facing surfaces. However high gas pressure is required to initiate each glow discharge session and this requires frequent cycling of valves to protect pressure sensitive devices. To alleviate this mechanical fatigue an electron gun assisted glow system (EAG) is being installed on the D3-D vessel to lower the initiation pressure. Through the injection of electrons the initiation pressure of the helium glow discharge has been lowered by a factor of 70, bringing the initiation pressure within a factor of 2 of the minimum sustaining pressure of the glow discharge. This might also make possible pulsed glow conditioning which would allow a lower average pressure during glow conditioning reducing the heat load on proposed cryogenic pumping panels. Experimental results of the electron assist on He glow initiation and a scaling model for the electron gun assisted glow will be presented. The electron gun can also be used as a diagnostic. Without a glow discharge, the electron gun has been pulsed into the wall and desorbed gas measured by a Residual Gas Analyzer. We are attempting to correlate the desorbed gas with recycling or vessel cleanliness.
Holtrop, K.L.; Jackson, G.L.; Schaubel, K.M.; Kellman, A.G.
[Measurement of rotational temperature in N2 DC glow discharge by optical emission spectroscopy].
Measurements of rotational temperature as low as several hundred Kelvin have been achieved using optical emission spectroscopy (OES) in nitrogen DC glow discharge. The strongest band of the first negative system of nitrogen molecule ion was chosen to determine the rotational temperature of nitrogen DC glow discharge at 4 different positions in the discharge area: back of the cathode; cathode sheath; positive column and anode glow region. In positive column the rotational temperature of N2+ increases apparently with the increasing discharge voltage from 500-1,100 V when the pressure is 10 Pa. However at pressure of 20 Pa the rotational temperature in positive column increases slightly with the increase of discharge voltage. On the contrary, the rotational temperature in cathode sheath takes reverse tendency when the discharge voltage varies from 500-1,100 V. As regard the anode glow region, the rotational temperature at 10 Pa decreases with the increase of discharge voltage, but that at the 20 Pa increases. We attribute the different changing tendencies of the rotational temperature to the different discharge status at different pressure. When the discharge voltage varies from 500 to 1,100 V, the discharge at pressure of 10 Pa is normal glow and that at 20 Pa is abnormal glow. PMID:12914187
Liu, Li-ying; Zhang, Jia-liang; Ma, Teng-cai; Deng, Xin-lu
Rotational temperature of nitrogen glow discharge obtained by optical emission spectroscopy.
Measurements of rotational temperature as low as several hundred Kelvin have been measured using optical emission spectroscopy (OES) in nitrogen direct current (DC) glow discharge. The strongest band of the first negative system of nitrogen was chosen to deduce the rotational temperature at four different positions in nitrogen DC glow discharge, the back of cathode; cathode sheath; positive column; and anode glow. In positive column the rotational temperature increased apparently with the increasing discharge voltage from 500 to 1000 V when the pressure was 10 Pa. But with pressure of 20 Pa the rotational temperature in positive column increased slightly with the increase of discharge voltage. On the contrary, the rotational temperature in cathode sheath took reverse tendencies when the discharge voltage varies from 500 to 1000 V. As regard the anode glow, the rotational temperature at 10 Pa decreased with the increase of discharge voltage, but that at pressure of 20 Pa increased. We attribute the different tendencies of the rotational temperature to the different discharge statues at different pressures. When the discharge voltage varies from 500 to 1100 V, the discharge with pressure of 10 Pa is normal glow and that with 20 Pa is abnormal glow. PMID:12164491
Zhang, Jialiang; Liu, Liying; Ma, Tengcai; Deng, Xinlu
Constricted glow discharge plasma source
A constricted glow discharge chamber and method are disclosed. The polarity and geometry of the constricted glow discharge plasma source is set so that the contamination and energy of the ions discharged from the source are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The source is suitable for applying films of nitrides such as gallium nitride and oxides such as tungsten oxide and for enriching other substances in material surfaces such as oxygen and water vapor, which are difficult process as plasma in any known devices and methods. The source can also be used to assist the deposition of films such as metal films by providing low-energy ions such as argon ions.
Anders, Andre (Albany, CA); Anders, Simone (Albany, CA); Dickinson, Michael (San Leandro, CA); Rubin, Michael (Berkeley, CA); Newman, Nathan (Winnetka, IL)
Spectral characteristics of Shuttle glow
The glowing cloud near the ram surfaces of the Space Shuttle was observed with a hand-held, intensified spectrograph operated by the astronauts from the aft-flight-deck of the Space Shuttle. The spectral measurements were made between 400 and 800 nm with a resolution of 3 nm. Analysis of the spectral response of the instrument and the transmission of the Shuttle window was performed on orbit using earth-airglow OH Meinel bands. This analysis resulted in a correction of the Shuttle glow intensity in the spectral region between 700 and 800 nm. The data presented in this report is in better agreement with laboratory measurements of the NO2 continuum.
Viereck, R. A.; Mende, S. B.; Murad, E.; Swenson, G. R.; Pike, C. P.; Culbertson, F. L.; Springer, R. C.
Glow in the Dark Slime
In this activity, create some Halloween spooky science by making glow-in-the-dark slime. Use this activity to investigate polymers and cross-linking. This activity guide includes a step-by-step instructional video. SAFETY NOTES: (1) Adult supervision is required. (2) Wearing gloves and goggles during this activity is a good idea because Borax is a poisonous, corrosive chemical. Read any safety instructions written on the container of Borax.
Center, Saint L.
Abnormal functional connectivity within the default mode network in patients with HBV-related cirrhosis without hepatic encephalopathy revealed by resting-state functional MRI.
By means of "task free" resting-state functional magnetic resonance imaging (rs-fMRI), abnormal functional connectivity (FC) of the default mode network (DMN) in cirrhotic patients with hepatic encephalopathy (HE) has been reported; however, little is known about the changes of DMN in cirrhotic patients without overt or minimal HE. The aim of this study was to investigate whether there was a disruption of the FC within the DMN in patients with hepatitis B virus (HBV)-related cirrhosis without any signs of HE. Fifty one patients with HBV-related cirrhosis without HE and 61 age- and gender-matched healthy controls underwent the rs-fMRI. Seed-based region-to-region FC was used to analyze the connectivity between each pair of regions within the DMN, including posterior cingulate cortex (PCC), medial prefrontal cortex (mPFC), hippocampal formation (HF), inferior parietal cortex (IPC), and medial temporal lobe (MTL). Pearson correlation analysis was performed between the abnormal FC strength within the DMN and venous blood ammonia levels in patients. Compared with the controls, patients with HBV-related cirrhosis without HE demonstrated significantly decreased region-to-region FC between the mPFC and bilateral MTL, right HF, and left IPC, as well as between the right MTL and left IPC, right HF, and PCC. A significant negative relationship was observed between blood ammonia levels and connectivity strength between the mPFC and left IPC in patients. These results suggest that patients with HBV-related cirrhosis without HE had disrupted functional connectivty within the DMN, even before the appearance of minimal HE. PMID:24907446
Qi, Rongfeng; Zhang, Long Jiang; Xu, Qiang; Liang, Xue; Luo, Song; Zhang, Zhiqiang; Huang, Wei; Zheng, Ling; Lu, Guang Ming
Transition to the obstructed discharge and a sharp change in the voltage-current characteristic as a result of gas heating in a short (positive-column-free) high-pressure glow discharge
The formation of a high-pressure glow discharge is studied under conditions when the discharge evolves from the normal glow to the abnormal glow. It is shown that the transition to the voltage-current characteristic of the obstructed discharge may take place as a result of heating the gas and a decrease in its density. The obstructed discharge follows the left-hand branch of the Paschen curve and features a sharp voltage rise and current density limitation.
Bogdanov, E. A.; Kudryavtsev, A. A.; Chirtsov, A. S.
Gas flow effects on the submicrosecond pulsed atmospheric pressure glow discharges
The influence of gas flow on the discharge characteristics in the submicrosecond pulsed dielectric barrier discharge at atmospheric pressure was investigated by a one-dimensional self-consistent kinetic model. The convection-transport mechanism of the plasma species caused by a longitudinal gas flow was integrated into flux equation. Two discharge current pulses, the positive one and the negative one, are operated in a normal glow mode and a subnormal glow mode, respectively. It is shown that the gas flow has a significant impact on the discharge characteristics, especially on the positive discharge pulse. The spatial distribution of electrons is affected by the gas flow through the convection transport mechanism.
Liu, Fucheng; Zhang, Dingzong; Wang, Dezhen
Glow Fast, Glow Slow: Alter the Rate of a Reaction!
Learners investigate one factor affecting reaction rates: temperature. In a darkened room, two identical lightsticks are placed in water -- one in hot water and one in cold water. The lightstick in the hot water glows brighter than the lightstick in the cold water since the light-producing reaction is faster in hot water. This activity, located on page 2 of the PDF, is one of three activities in the Take Home guide for the Chemical Reactions unit in OMSI's Chemistry Lab. Also included on the PDF are two additional activities: Cloudy Globs and Gas Production.
Industry, Oregon M.
Thermoluminescence under an exponential heating function: II. Glow-curve deconvolution of experimental glow-curves
Thermoluminescence (TL) glow-curves measured using an exponential heating function (EHF) in constant temperature hot gas readers, cannot be analysed using the existing single TL glow-peak equations derived assuming a linear heating rate. In the present work single TL glow-peak equations, which were recently derived assuming an EHF, are used to perform a computerized glow-curve deconvolution analysis of experimental glow-curves measured using a stable temperature hot gas reader. Glow-curves of the most commonly used dosimetric material LiF:Mg, Ti were analysed using the first order kinetics glow-peak equations. The glow-curves were analysed for samples that were pre-irradiation annealed at 400 �C for 1 h and 100 �C for 2 h, with and without a post-irradiation annealing at 80 �C for 1 h. TL glow-peak equations of the general order kinetics were used to analyse experimental glow-curves of the dosimetric material Li2B4O7 : Mn, Si. The results showed that the recently derived TL equations are very efficient for analysing glow-curves measured using stable temperature hot gas readers.
Kitis, G.; Chen, R.; Pagonis, V.; Carinou, E.; Ascounis, P.; Kamenopoulou, V.
APEX reveals glowing stellar nurseries
Illustrating the power of submillimetre-wavelength astronomy, an APEX image reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps that are the birthplaces of new stars. Submillimetre light is the key to revealing some of the coldest material in the Universe, such as these cold, dense clouds. Glowing Stellar Nurseries ESO PR Photo 40/08 Glowing Stellar Nurseries The region, called RCW120, is about 4200 light years from Earth, towards the constellation of Scorpius. A hot, massive star in its centre is emitting huge amounts of ultraviolet radiation, which ionises the surrounding gas, stripping the electrons from hydrogen atoms and producing the characteristic red glow of so-called H-alpha emission. As this ionised region expands into space, the associated shock wave sweeps up a layer of the surrounding cold interstellar gas and cosmic dust. This layer becomes unstable and collapses under its own gravity into dense clumps, forming cold, dense clouds of hydrogen where new stars are born. However, as the clouds are still very cold, with temperatures of around -250? Celsius, their faint heat glow can only be seen at submillimetre wavelengths. Submillimetre light is therefore vital in studying the earliest stages of the birth and life of stars. The submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope, located on the 5000 m high plateau of Chajnantor in the Chilean Atacama desert. Thanks to LABOCA's high sensitivity, astronomers were able to detect clumps of cold gas four times fainter than previously possible. Since the brightness of the clumps is a measure of their mass, this also means that astronomers can now study the formation of less massive stars than they could before. The plateau of Chajnantor is also where ESO, together with international partners, is building a next generation submillimetre telescope, ALMA, the Atacama Large Millimeter/submillimeter Array. ALMA will use over sixty 12-m antennas, linked together over distances of more than 16 km, to form a single, giant telescope. APEX is a collaboration between the Max-Planck-Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. The telescope is based on a prototype antenna constructed for the ALMA project. Operation of APEX at Chajnantor is entrusted to ESO.
Stable Operation of High Current Glow Discharges.
The cleaning of large Tokamak vessels with glow discharges as a source of H atoms is discussed, drawing on industrial experience in their use for the improvement of metal surfaces. Glow discharge is dealt with in relation to Townsend discharge and arcing....
B. Brandt
Atmospheric sampling glow discharge ionization source
An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above.
McLuckey, Scott A. (Oak Ridge, TN); Glish, Gary L. (Oak Ridge, TN)
dc glow-discharge cleaning for accelerator
Average pressure of 1 x 10/sup -11/ torr and vacuum stability are necessary for the successful operation of the proton storage rings such as ISABELLE. Vacuum degassing at high temperature and in situ bake-out will reduce the thermoout-gassing rate of the beam tubes to approx. 10/sup -13/ Tl/cm/sup 2/ sec, therefore achieving the required static pressure. The vacuum instability caused by beam-induced ion desorption can be solved by dc glow discharge cleaning. With evidence from this study, the present understanding of glow discharge in a cylindrically symmetric geometry is reviewed. Argon and argon/oxygen mixture serve as plasmas in the glow. The role of oxygen in cleaning the beam tubes during the glow discharge is demonstrated experimentally. Glow discharge cleaning with and without bake-out is also studied.
Chou, T.S.; Hseuh, H.C.
An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above. 3 figs.
McLuckey, S.A.; Glish, G.L.
Glow Plasma Discharges inside Externally Excited Porous Spherical Cavity Resonators
A porous spherical cavity resonator (PSCR) provides amplification of externally incident electric fields a resonant frequencies corresponding to discrete modes. The PSCR has a mesh surface with a large number of polygon (hexagon and pentagon) holes. The size of the holes is adjusted to maximize the Q of the resonator for production of maximum internal electrical fields. Amplification factors for a PSCR are about 1000. The high resonator Q requires precise tuning of the incident wave frequency to a resonant frequency. The PSCR is placed in a low-pressure (1 T) gas chamber and excited by an external microwave horn for a chosen spherical cavity resonator mode. At the resonant frequency, a glow discharge occurs inside the cavity producing a plasma cloud in the shape of electric field modes. Varying the neutral gas pressure inside the chamber (1) yields variations in the glow discharge light intensity and (2) affects the shapes of the plasma cloud. If the plasma frequency in the electron cloud approaches the incident wave frequency, self-action produces localized regions of dense plasmas. The PSCR apparatus can be used to study cavity resonator modes in the low pressure environment and electromagnetic wave interactions in high pressure plasmas.
Bernhardt, Paul; Fliflet, Arne
Walking abnormalities
Gait abnormalities ... of how a person walks is called the gait. Different types of walking problems occur without a ... Some walking abnormalities have been given names: Propulsive gait -- a stooped, stiff posture with the head and ...
Analytical approaches to glow discharge problems
Combined experimental, numerical and analytical approaches are presented to address actual problems of glow discharge physics. Such a synthesis is able to clarify relatively simple, qualitative, self-consistent phenomena, and should allow improvement of the existing paradigms and/or formulation of novel approaches. The following illustrative examples are discussed: Linear and non-linear diffusion in multispecies, currentless and current-carrying low-temperature plasmas. Both ambipolar diffusion and ambipolar mobility are considered. Non-local electron kinetics in radio frequency and direct current glows. Structures of the cathode and anode regions in direct current glows. .
Tsendin, L. D.
Scaling and characterization of direct current glow discharge plasma in atmospheric air
A microhollow cathode discharge was used as a plasma cathode to sustain a stable direct current glow discharge in atmospheric pressure air. The volumetric scale of glow discharge increased from the millimeter to the centimeter range by extending the plasma in lateral and axial directions. In the axial direction, the length of the glow discharge column was varied from 1 mm to 2 cm, with the sustaining voltage increasing linearly with the glow discharge column length. Extension in the lateral direction was obtained by operating discharges in parallel. The glow discharge plasma of the parallel discharge columns was found to merge when either the discharge current or the electrode gap was increased. For a glow discharge with a current on the order of 10 mA, the electron density in the glow discharge exceeded 1011 cm -3, with a peak value of 1013 cm-3 near the plasma cathode. The electron temperature in the positive column of the glow discharge was found to be in the range of 1.14 eV. The glow discharge axial gas temperature was found to have a maximum value of 2200 K close to the plasma cathode, and to decrease toward the third electrode to about 1400 K. The application of a 10 ns pulse to the glow discharge increased the electron density to 1015 cm-3 and reduced the power density by a factor of three compared to the dc discharge. The effect is assumed to be due to the nonequilibrium electron heating of the electrons without causing changes in gas temperature. The gas temperature was found to increase by only 200 K within 15 ns after the pulse, which indicated the time of energy transfer from electrons to the neutral particles. Flowing air through the hole of the microhollow cathode discharge generated a stable micro-plasma jet. The power consumption in the jet was 1 to 10 W depending on the micro-plasma discharge current. The gas temperature in the jet was controllable between 300 K to 1000 K by varying the discharge current and the flow rate. The jet changed from a laminar to a turbulent mode with an increase of the flow rate. The transition from laminar to turbulent correlated to a significant decrease in its gas temperature.
Mohamed, Abdel-Aleam Hefney
Characteristics of thermoluminescence glow curves for materials exhibiting more than one glow peak
The properties of thermoluminescence glow curves, containing one or more glow peaks, have been determined for situations where the assumptions invoked to obtain the usual first and second order kinetics do not apply. First order kinetics occurs only when retrapping is negligible. If more than one glow peak is present and retrapping occurs between different types of traps the glow peaks can be approximated, except in the wings, by the usual first and second order expressions; but often physically unrealistic parameters are obtained. These studies indicate that dating is best accomplished with minerals exhibiting first order kinetics. 6 figures, 1 table.
Levy, P.W.
Infrared spectral measurement of Space Shuttle glow
The USAF and NASA successfully conducted infrared spectral measurements of the Space Shuttle glow during STS-39. Preliminary analysis indicates that NO, NO(+), OH, and CO produce infrared glow during quiescent orbiter conditions. During orbiter thruster firings the glow intensities in the infrared are enhanced by factors of 10X and 100X with significant changes in spectral distribution. These measurements were obtained with the Spacecraft Kinetic Infrared Test payload which included a cryogenic infrared circular variable filter infrared spectrometer covering the 0.7 to 5.4 microns wavelength region. Approximately 14,000 spectra of Shuttle glow, airglow, aurora, and the orbiter environment were obtained during the eight day mission. The STS-39 Space Shuttle Discovery was launched from the NASA Kennedy Space Center on 28 April, 1991 into a 57-deg inclination circular orbit at an altitude of 260 km.
Ahmadjian, Mark; Jennings, D. E.; Mumma, M. J.; Espenak, F.; Rice, C. J.; Russell, R. W.; Green, B. D.
Stable operation of high current glow discharges
The cleaning of large Tokamak vessels with glow discharges as a source of H atoms is discussed, drawing on industrial experience in their use for the improvement of metal surfaces. Glow discharge is dealt with in relation to Townsend discharge and arcing. The stability of the glow is treated, and unipolar arcs, or cathode scintillations, are described. Similarity rules and scaling laws, used to predict the behavior of discharges when the size of the vessel or pressure are changed, are given. High temperature plasmas and cathode-fall are studied along with phenomena at the anode. The appropriateness of high current glow discharges to clean, to equalize, and to deoxidize plasma vessel surfaces is underlined.
Brandt, B.
Use of Glow Discharge in Fluidized Beds.
Static charges and agglomeration of particles in a fluidized bed system are minimized by maintaining in at least part of the bed a radio frequency glow discharge. This approach is eminently suitable for processes in which the conventional charge removing ...
T. Wydeven P. C. Wood E. V. Ballou L. A. Spitze
Analysis of Glow Discharge and Transport Phenomena in Plasma Reactors.
Mathematical models were developed to analyze the intricate physiochemical phenomena of glow discharges and to predict technologically important quantities such as etching rate, uniformity, and anisotropy. The overall modeling effort was divided into two major parts: glow discharge model and neutral transport and reaction model. The glow discharge model provided the space and time dependence of the electron density and energy, the ion density, and the potential distribution in a parallel -plate plasma reactor. The continuum model equations were solved using the method of lines with orthogonal collocation on finite elements. This algorithm permitted a parametric study of an electropositive (argon-like) and an electronegative (chlorine) discharge. The electronegative discharge exhibited much thinner sheaths, much greater potential drop and electric field strength in the bulk plasma, and severe modulation by the applied radio frequency (10MHz) of the electron energy, ionization, and excitation rate in the bulk. The neutral transport and reaction model provided the gas flow velocity, temperature, and concentration distribution of reactive radicals as a function of reactor geometry and operating conditions. The finite element method was employed to solve the model equations, and was found to be attractive especially for complex reactor geometries. Different parallel-plate reactor configurations were examined including a single-wafer etcher and a Reinberg-type multiwafer reactor. Etching of polymer or etching of silicon were used as model systems for analysis. Uniformity of etching was emphasized and design criteria were suggested to improve uniformity. In addition, optimum operating conditions that maximize the etching rate were identified. Several novel modes of operation were proposed to improve reactor performance. These included a graded gas velocity profile at the reactor inlet, and a plasma impulse mode of operation. Furthermore, a downstream etching reactor was analyzed, and a new reactor configuration was proposed to improve both the etching rate and the uniformity. (Abstract shortened with permission of author.).
Park, Sang-Kyu
Discharge characteristics of atmospheric-pressure radio-frequency glow discharges with argon/nitrogen
In this letter, atmospheric-pressure glow discharges in {gamma} mode with argon/nitrogen as the plasma-forming gas using water-cooled, bare copper electrodes driven by radio-frequency power supply at 13.56 MHz are achieved. The preliminary studies on the discharge characteristics show that, induced by the {alpha}-{gamma} coexisting mode or {gamma} mode discharge of argon, argon-nitrogen mixture with any mixing ratios, even pure nitrogen, can be employed to generate the stable {gamma} mode radio-frequency, atmospheric-pressure glow discharges and the discharge voltage rises with increasing the fraction of nitrogen in the argon-nitrogen mixture for a constant total gas flow rate.
Wang Huabo; Sun Wenting; Li Heping; Bao Chengyu; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)
A large gap of radio frequency dielectric barrier atmospheric pressure glow discharge
A large gap was acquired between electrodes (up to 5.5 mm) of Ar atmospheric pressure glow discharge in radio frequency dielectric barrier discharge (rf-DBD). The discharge of Ar plasma was characterized by I-V curve and Lissajous plot, and the effective power of the discharge was calculated based on the measured Lissajous plot and found to be higher than 90% of the input power. To gain a thorough understanding of the mechanism, the rf-DBD with a single dielectric barrier layer operating in gamma mode glow discharge of N{sub 2} plasma was diagnosed in spatial resolution through optical emission spectroscopy. It was concluded that secondary electron emission might be responsible for the sustainable glow discharge in the large gap rf-DBD plasma.
Li, B.; Chen, Q.; Liu, Z. W. [Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing 102600 (China)
A large gap was acquired between electrodes (up to 5.5 mm) of Ar atmospheric pressure glow discharge in radio frequency dielectric barrier discharge (rf-DBD). The discharge of Ar plasma was characterized by I-V curve and Lissajous plot, and the effective power of the discharge was calculated based on the measured Lissajous plot and found to be higher than 90% of the input power. To gain a thorough understanding of the mechanism, the rf-DBD with a single dielectric barrier layer operating in ? mode glow discharge of N2 plasma was diagnosed in spatial resolution through optical emission spectroscopy. It was concluded that secondary electron emission might be responsible for the sustainable glow discharge in the large gap rf-DBD plasma.
Li, B.; Chen, Q.; Liu, Z. W.
Complicated Holter tracing with an incidence of inappropriate mode switch due to sensing abnormalities in a patient with dual-chamber pacemaker.
24-hour Holter monitoring of a 59 year-old man with DDDR pacemaker (programmed mode: DDD) implanted for sick sinus syndrome with paroxysmal atrial fibrillation was performed one month after implantation, due to palpitations. Several episodes of rapid pacing of decreasing rate were detected. Intracardiac recording stored in the pacemaker memory had shown episodes of atrial lead oversensing, which led to the mode switch, resulting in DDIR mode. Signals which caused oversensing were not seen in Holter tracing. PMID:21305495
Por?ba, Ma?gorzata; Karczmarewicz, Stefan; Szwarc, Bart?omiej; Sobieszcza?ska, Ma?gorzata; Wranicz, Jerzy Krzysztof
Mass dependency of turbulent parameters in stationary glow discharge plasmas
A direct current glow discharge tube is used to determine how mass changes the effects of certain turbulence characteristics in a weakly ionized gas. Helium, neon, argon, and krypton plasmas were created, and an axial magnetic field, varied from 0.0 to 550.0 Gauss, was used to enhance mass dependent properties of turbulence. From the power spectra of light emission variations associated with velocity fluctuations, determination of mass dependency on turbulent characteristic unstable modes, energy associated with turbulence, and the rate at which energy is transferred from scale to scale are measured. The magnetic field strength is found to be too weak to overcome particle diffusion to the walls to affect the turbulence in all four types of plasmas, though mass dependency is still detected. Though the total energy and the rate at which the energy moves between scales are mass invariant, the amplitude of the instability modes that characterize each plasma are dependent on mass.
Titus, J. B.; Alexander, A. B. [Florida A and M University, Tallahassee, Florida 32310 (United States)] [Florida A and M University, Tallahassee, Florida 32310 (United States); Wiggins, D. L. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53703 (United States)] [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53703 (United States); Johnson, J. A. III [Pyramid Plasmas LLC, Lawrenceville, Georgia 30043 (United States)] [Pyramid Plasmas LLC, Lawrenceville, Georgia 30043 (United States)
Laboratory investigation of visible shuttle glow mechanisms
Laboratory experiments designed to uncover mechanistic information about the spectral and spatial characteristics of shuttle glow were conducted. The luminescence was created when a pulse of O atoms traveling at orbital velocities was directed toward NO molecules previously adsorbed to aluminum, nickel, and Z306 Chemglaz (a common baffle black) coated surfaces held at various temperatures. Spectral and spatial measurements were made using a CCD imaging spectrometer. Corroborative spectral information was recorded in separate measurements using a scanning monochromator and gated photomultiplier arrangement. The e-folding distance at several temperatures was calculated from images of the surface glow using the photometrics image processing capability of the imaging spectrometer. The e-folding distance was not altered as a function of incoming O beam velocity. The results are presented and the observations provide direct evidence that the visible shuttle glow results from recombination of oxygen atoms and surface bound NO.
Leone, A.; Swenson, G. R.; Caledonia, G. E.; Holtzclaw, K. W.
The glow discharge as an atomization and ionization device
All of our projects involve the glow discharge source as our basic research focus. Our primary effort is glow discharge mass spectrometry, but we frequently use complementary procedures such as atomic absorption and atomic emission in the glow discharge to obtain useful information about plasma processes. Our overall goal is to gain a better understanding of the glow discharge and to bring it to bear on real analytical problems.
Harrison, W.W.
Electrical properties of pulsed glow discharge Two new aspects
At the application of pulsed glow discharge (PGD) a transient power of several kW can be reached. This leads to a significant increase of the excitation and ionization efficiency of the sputtered sample atoms. Moreover, with pulsed mode temporally resolved optical emission spectrometry (OES) and mass spectrometry (MS) deliver additional information about the chemical bonds (Harrison 1998, Bengtson et al. 2000, Hang et al. 1996, Klingler et al. 1990, Lewis et al. 2001, Jackson and King 2003). However, the practical application of pulsed glow discharge (PGD) requires an understanding of the processes taking place in the pulsed system. There are some publications, where attention was paid on the voltage current characteristics and the current signal shape of PGD (King and Pan 1993, Lewis et al. 2003). Nevertheless more attention should be paid on the electrical properties of the PGD. In this work the shapes of current, voltage and emission intensity signals, obtained with two different pulse generators are compared. For better understanding of processes, taking place in the discharge the knowledge of the gas temperature is very important. Several authors have mentioned that heating of the cathode leads to changes of the voltage current curve, mainly a decrease of the current at the same voltage. This can be explained by a lower gas density at the same pressure but at higher temperatures (Chenlong et al. 1999, Tian and Chu 2001, Kasik et al. 2002). This phenomenon gives an approach to estimate the gas temperature of the plasma.
Efimova, V. V.; Voronov, M. V.; Hoffmann, V.; Eckert, J.
Magnetic and electrical properties of Fe/Si core-shell cluster assemblies prepared with double-glow-discharge sources
Using a double glow-discharge-cluster-source-system, in which one glow discharge is a dc mode and the other an rf discharge mode, Fe and Si clusters have been produced independently and deposited simultaneously on a substrate. When a separation plate is not inserted between two glow-discharge chambers, core-shell clusters are obtained: An Fe core is surrounded by small Si crystallites. The magnetization measurement indicates that the magnetic coercive force of the Fe/Si core-shell cluster assembly is much smaller than those of Fe cluster assemblies at low temperature and no shift of the field-cooled hysteresis loop related to the zero-field-cooled loop is detected, probably because Si shells prevent Fe cluster surfaces from their oxidation. The temperature dependence of electrical resistance is attributed to electron conduction via Si shell networks above 180 K, while it is attributed to variable range electron conduction between Fe clusters.
Katoh, R.; Hihara, T.; Peng, D.L.; Sumiyama, K. [Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)
NGC 3132 is a striking example of a planetary nebula. This expanding cloud of gas, surrounding a dying star, is known to amateur astronomers in the southern hemisphere as the 'Eight-Burst' or the 'Southern Ring' Nebula. The name 'planetary nebula' refers only to the round shape that many of these objects show when examined through a small visual telescope. In reality, these nebulae have little or nothing to do with planets, but are instead huge shells of gas ejected by stars as they near the ends of their lifetimes. NGC 3132 is nearly half a light year in diameter, and at a distance of about 2000 light years is one of the nearer known planetary nebulae. The gases are expanding away from the central star at a speed of 9 miles per second. This image, captured by NASA's Hubble Space Telescope, clearly shows two stars near the center of the nebula, a bright white one, and an adjacent, fainter companion to its upper right. (A third, unrelated star lies near the edge of the nebula.) The faint partner is actually the star that has ejected the nebula. This star is now smaller than our own Sun, but extremely hot. The flood of ultraviolet radiation from its surface makes the surrounding gases glow through fluorescence. The brighter star is in an earlier stage of stellar evolution, but in the future it will probably eject its own planetary nebula. In the Heritage Team's rendition of the Hubble image, the colors were chosen to represent the temperature of the gases. Blue represents the hottest gas, which is confined to the inner region of the nebula. Red represents the coolest gas, at the outer edge. The Hubble image also reveals a host of filaments, including one long one that resembles a waistband, made out of dust particles which have condensed out of the expanding gases. The dust particles are rich in elements such as carbon. Eons from now, these particles may be incorporated into new stars and planets when they form from interstellar gas and dust. Our own Sun may eject a similar planetary nebula some 6 billion years from now. Credit: Hubble Heritage Team (STScI/AURA/NASA)
Characteristics of a LaB6 hollow cathode in the glow-arc transition
A new type of a simple LaB6 hollow cathode tube allows us to have very stable discharge even in the regime of the glow-arc transition, which is commonly unstable for widely used cathode materials (Ta,W). Because of the relatively large size of our device (25 mm diameter) and the low-temperature operation (~1400 K), we were able to investigate various plasma parameters of the internal plasma in detail by using a standard Langmuir probe and an ion sampling technique with a tiny orifice (1 mm diameter) to study the ion behavior near the cathode wall. Our measurements of the electron-energy distribution function F(?), the space potential ?, the mean electron energy ?�, the electron density ne, and the sampling ion current density Ji were carried out under various discharge conditions in order to understand the basic characteristics of hollow cathode discharge. We have found that these plasma parameters show anomalous properties in the glow-arc transition: (1) The different discharge regime of hollow cathode discharge, namely the abnormal glow, the arc, and the glow-arc transition, are clearly distinguished, and the discharge voltage Vd and Ji are a unique function of the discharge current in our hollow cathode tube. (2) A distinct high-energy component appears in the range ~1-7 eV, with two types of high-energy tails. (3) The local growth of ?�, the local ionization, and appearance of the space potential hill are observed near the anode and central region of the tube. These anomalous disturbances correspond to nonuniform self-heating: the nonuniform thermionic electron-emission effect along the LaB6 hollow cathode tube in the glow-arc transition.
Tonegawa, Akira; Takayama, Kazuo
Analysis of Energetic Species Caused by Contact Glow Discharge Electrolysis in Aqueous Solution
Contact glow discharge electrolysis is a non-Faradaic electrochemical process with an abnormal relationship between the current and voltage. Hydroxyl radicals, hydrogen radicals and hydrogen peroxide can be produced under the glow discharge, which are often used to degrade organic contaminants in aqueous solution. In this study, with 4-nitrophenol taken as an example of contaminants and tert-butanol as a scavenger of hydroxyl radicals, the role of energetic species in degrading organic compounds was examined in detail. Moreover, the effects of the applied voltage, solution conductivity and pH on the formation of three energetic species were also observed. The formation rate constants of the three energetic species were calculated based on the experimental data.
Gao, Jinzhang; Wang, Aixiang; Fu, Yan; Wu, Jianlin; Ma, Dongping; Guo, Xiao; Li, Yan; Yang, Wu
Spectroscopic Study of the Negative Glow in Usual Glow and in Hollow-Cathode Discharges
The negative glow(NG) in a low pressure He and a He-Cd glow discharge was investigated by a spectroscopic method. Atomic line intensities and their excitation cross-sections were utilized to estimate the electron energy and density in the NG. In the NG, some electrons have the energies more than 100 eV and the density of low energy (30-34 eV) electrons is
Kan-ichi Fujii
Surveyor observations of lunar horizon-glow
Each of the Surveyor 7, 6, and 5 spacecraft observed a line of light along its western lunar horizon following local sunset. It has been suggested that this horizon-glow (HG) is sunlight, which is forward-scattered by dust grains (~ 10� in diam, ~ 50 grains cm-2) present in a tenuous cloud formed temporarily (? 3 h duration) just above sharp
J. J. Rennilson; D. R. Criswell
Oscillatory Phenomena in Direct Current Glow Discharges
In glow discharges having a positive column with a constant emf and a series resistance, oscillations usually are observed in tube voltage, current, and light intensity. While current and voltage oscillations represent a modulation of only a few percent, the intensity decreases to zero between maxima in the positive column, but there is an appreciable steady component near the cathode.
T. Donahue; G. H. Dieke
Atmospheric pressure radio frequency glow discharges in argon: effects of external matching circuit parameters
Numerical simulations of radio frequency atmospheric pressure argon glow discharges were performed using a one-dimensional hybrid model. The discharge simulations were carried out for a parallel plate electrode configuration with an inter-electrode gap of 1.0 mm together with an external matching circuit. The external matching circuit parameters were found to have significant effect on the discharge characteristics. The results indicate that the discharge can operate at either the ? or ? mode depending on the matching circuit parameters. The two modes of operation were found to be distinctly different. The predicted Ar* density was considered to provide qualitatively the visual appearance of the ? or ? mode discharge. The ? mode was found to have a luminous region in the center of the discharge. On the other hand, the ? mode had luminous regions very close to the electrodes which were followed by alternating dark and bright regions. The appearance of the simulated ? mode was found to resemble that of an atmospheric pressure direct current glow discharge. The predicted gas temperature indicated the ? mode to have higher gas temperature compared with the ? mode.
Farouk, Tanvir; Farouk, Bakhtier; Gutsol, Alexander; Fridman, Alexander
Characterization of a Direct-Current Glow Discharge Plasma Actuator in Low-Pressure Supersonic Flow
DOI: 10.2514\\/1.27197 An experimental study of a direct-current, nonequilibrium glow plasma discharge in the presence of a Mach 2.85 supersonic flow is presented. The discharge is generated with pinlike electrodes flush-mounted on a plane surface with sustaining currents between 25 to 300 mA. In the presence of a supersonic flow, two distinct discharge modes (diffuse and constricted) are observed depending
Jichul Shin; V. Narayanaswamy; Laxminarayan L. Raja; Noel T. Clemens
Parametric Investigations of an Atmospheric pressure Uniform Glow Discharge in helium
In the cold plasma processing field, applications of the atmospheric pressure uniform glow discharge are numerous. Among them one can mention the increase of the surface energy of materials, the cleaning and etching of surfaces, and the decontamination and sterilization. The development of the glow regime at atmospheric pressure permits to avoid the technical and economical drawbacks of low pressure glow discharge systems. It also increases the efficiency of the surface treatment as compared to the corona discharge. In these conditions, a glow regime is obtained and studied in particular experimental conditions. The working gas is helium, the frequency in the range 1-20 kHz, the gap distance of some mm and the metallic electrodes are covered by a dielectric layer. The current is characterized by one peak per half cycle and is typically in the range of a few tens of mA. Since this discharge involves complex nonlinear processes and is sensitive to the variation of its parameters, detailed experimental (Ph. Decomps (1996), PhD thesis, Universite Paul Sabatier Toulouse France, No d'ordre 2538.) and numerical studies, covering wide ranges of system parameters, were required. These investigations allowed the determination of the optimal operating conditions for which the discharge remains of the glow type, and therefore induces a better surface treatment. In this paper the detailed theory ( Ben Gadri R., Rabehi A., Massines F. and Segur P. (1994), XIIth Eur. Sect. Conf. on the At. & Mol. Phy. of Ionized Gases, The Netherlands, 23-26 August, pp. 228-229.) of the one dimensional f luid model and a parametric study of the discharge characteristics are presented. A particular attention will be given to the influence of the different system parameters on the operational mode of the discharge.
Ben Gadri, Rami
Laser Ignited Glow Discharge in Lithium Vapour
The ignition of Li glow discharge is studied for three cases of laser excitation of lithium vapour: the first resonance at 670.8 nm (2s -> 2p transition), the quasiresonant line at 460.3 nm (2p -> 4d), or the two-photon resonant line at 639.1 nm (2s -> 3d transition) below self-breakdown voltage. The conditions for laser ignition of the discharge are
Hrvoje Skenderovic; Irena Labazan; Slobodan Milosevic; Goran Pichler
On the Shuttle glow (the plasma alternative)
It is shown that the anomalous glow observed in the recent Space Shuttle flights can be attributed to a combination of beam plasma discharge and critical ionization phenomena. While the Shuttle velocity (approximately 8 km\\/s) is below the critical ionization velocity, which for oxygen is 12.7 km\\/s, specular reflection of a small fraction (2-3 percent) of ambient ions forms an
K. Papadopoulos
Use of glow discharge in fluidized beds
Static charges and agglomerization of particles in a fluidized bed systems are minimized by maintaining in at least part of the bed a radio frequency glow discharge. This approach is eminently suitable for processes in which the conventional charge removing agents, i.e., moisture or conductive particle coatings, cannot be used. The technique is applied here to the disproportionation of calcium peroxide diperoxyhydrate to yield calcium superoxide, an exceptionally water and heat sensitive reaction.
Wydeven, T.; Wood, P. C.; Ballou, E. V.; Spitze, L. A. (inventor)
On the accuracy and limitations of fluid models of the cathode region of dc glow discharges
This paper compares the performance and limitations of different models of the cathode region of cold-cathode low-pressure dc glow discharges: (i) we review known modelling approaches, (ii) develop our own simulation codes based on these approaches, (iii) perform calculations using these codes for reference sets of discharge conditions, which allows a critical comparison of the models and (iv) for a further check of the simulation results we carry out Langmuir probe measurements of electron densities in abnormal Ar glow discharges. The theoretical approaches include fluid models both neglecting and including the electron energy balance equation, as well as hybrid models, which combine the fluid treatment of slow plasma species with the kinetic simulation of fast electrons. We also test the effect of the choice of the ionization source term in fluid models. We find that the electron densities calculated from the fluid models are far (several orders of magnitude) below the experimental values even if the electron energy equation is considered in the calculations. This weakness of fluid models clearly points out the importance of an accurate calculation of the ionization source term, which can only be accomplished by a kinetic approach under the conditions of highly nonlocal electron transport in the cathode region of glow discharges. In hybrid models Monte Carlo simulation is used for this purpose, and indeed, this approach gives electron densities comparable to our experimental data.
Derzsi, A.; Hartmann, P.; Korolov, I.; Kar�csony, J.; B�n�, G.; Donk�, Z.
Helium-Glow Photometer for Picomole Analysis of Alkali Metals
The low-power electric-glow discharge in helium can excite effectively the characteristic emission lines of sodium and potassium. The helium-glow photometer used to generate the glow and measure the light is a relatively simple apparatus; it can be used to analyze samples containing 10-14 mole or more of sodium and potassium. Overall precision of the apparatus and method is 5 percent
Gerald G. Vurek; Robert L. Bowman
Evaluation of Thermal Activation Energies from Glow Curves
A new method for the evaluation of thermal activation energies from glow curves of excited crystals is described. Use is made of the symmetry of the glow peak, from which the activation energy is calculated by a simple formula: E=(qdelta)kTg2, where Tg is the peak temperature, k-Boltzmann's constant, delta-the half-width towards the falloff of the glow peak, and q-a factor
A. Halperin; A. A. Braner
A study on the equivalent electric circuit simulation model of DBD streamer and glow alternate discharge
This paper presents a dynamic simulating model of the dielectric barrier discharge (DBD), structured as an equivalent electric circuit of the streamer and glow discharge generated alternately in DBD. The main parameters of DBD have been established by means of analysing the structural characteristics of a single discharge cell. An electrical comprehensive Simulink /MATLAB model was developed in order to reveal the interaction of the adjacent two discharge cell. A series of simulations was carried out in order to estimate the key structural parameters that affect the alternate streamer and glow discharge mode. The comparison results of experimental and simulate indicate that there exists a close similarity of the current waveforms graphic. Therefore, we can grasp a deep understanding mechanism of the dielectric barrier discharge and optimize the plasma reactor.
Yao, J.; Zhang, Z. T.; Yu, Z.; Xu, S. J.; Yu, Q. X.; Zhao, J. S.
Simulations of direct-current air glow discharge at pressures {approx}1 Torr: Discharge model validation
Computational simulations of air glow discharge phenomena in the pressure range typical of plasma actuator applications for high speed flow control are presented. The model is based on a self-consistent, multispecies, and multitemperature continuum description of the plasma. A reduced air plasma model suitable for multidimensional simulations with 11 species and 21 gas phase chemical reactions is validated against experimental results in the literature. The discharge model predicts experimentally observed glow mode discharge operation, the current-voltage characteristics of the discharge, and spatial profiles of the electron temperature and positive ion number densities. For pressures of order 1 Torr, O{sub 2}{sup +} and N{sub 2}{sup +} are the dominant positive ion species in the discharge, and the concentration of O{sup -} negative ion is comparable to electron concentration. The two-dimensional structure of the discharge is predicted by the model is found to be in agreement with qualitative observations from the experiments.
Mahadevan, Shankar; Raja, Laxminarayan L. [University of Texas at Austin, Austin, Texas 78712 (United States)
Improvement of materials surface properties by rf glow discharge treatment
Materials surface properties were improved by the application of a rf glow discharge treatment for vacuum and electronic applications. The surface morphology was studied under different glow discharge treatments and it could be shown by experiments that the roughness of materials surface varied due to the glow discharge treating process and that a clean and smooth surface could be obtained after the treatment. The experimental results revealed that the outgassing rates for different gases decreased and the evacuating properties for the materials improved following the application of the glow discharge treatment.
Huang, T.B.; Chen, X.; Tian, X.Q.; Cha, L.Z. [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China)
Partially constricted glow discharge in an argon-nitrogen mixture
The characteristics of a glow discharge in Ar:N{sub 2} mixtures with a low content of nitrogen (0.02-1%) are studied experimentally. Most studies were performed at pressures higher than 10 Torr, at which the discharge constriction goes by a jump and the hysteresis effect is well pronounced. It is found that the time during which the discharge switches from the diffuse to the constricted mode (and back) can reach {approx}1 s. The transition between these modes begins with the development of a constriction at one end of the positive column. Then, the constricted part of the discharge extends toward the other end until it occupies the entire column. The reverse transition occurs in a similar way. By varying the parameters of the electric circuit during the transition, the constriction front can be stopped to form a steady-state partially constricted discharge. It is shown that this type of discharge corresponds to points lying inside the hysteresis loop of the conventional I-V characteristic measured without affecting the discharge during a transition. A comparative analysis of the discharge characteristics in Ar:N{sub 2} mixtures and in pure argon is performed.
Ionikh, Yu. Z.; Meshchanov, A. V.; Petrov, F. B. [Fock Institute of Physics, St. Petersburg State University (Russian Federation); Dyatko, N. A.; Napartovich, A. P. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)
Spectroscopic Characterization of Atmospheric Pressure Glow Plasma
The thermal structure of methane-fed dielectric barrier discharge (DBD) and atmospheric pressure glow discharge (APG) has been investigated in terms of time-averaged gas temperature profile between two parallel-plate electrodes separated by 1.0 mm. Emission spectroscopy of rotational band of CH ((0,0) 431 nm) was performed for this purpose. DBD and APG was activated by 10 kHz with 2% duty cycle pulsed voltage in order to minimize average gas temperature increase. In DBD, temperature increase of a single microdischarge, on a time average, reached 200 K. It suddenly decreased below 100 K associated with the dark space formation near dielectric barrier. Also, gas temperature in the surface discharge was fairly low because emission in these regions was limited within the initial stages of propagation, whereas energy deposition would continue until microdischarge extinction; Rotational temperature seemed to estimate far below the actual gas temperature in these regions. In APG, gas temperature was uniformly increased by positive column formation. In addition, remarkable temperature increase due to negative glow formation was obtained only near the metallic electrode. In the practical interest, we also investigated net temperature increase with high frequency operations (AC 80 kHz), which depends on not only plasma properties, but also various engineering factors such as flow field, external cooling conditions, and total input power. In DBD, gas temperature in the middle of gas gap was significantly increased with input power due to poor cooling conditions. In APG, on the contrary, gas temperature near electrodes was significantly increased associated with negative glow formation.
Okazaki, Ken
Stability of atmospheric pressure glow discharges
There has been a considerable interest in non-thermal atmospheric pressure discharges over the past decade due to increased number of industrial applications. Although non-thermal atmospheric pressure discharges have been intensively studied for the past century the clear physical picture of these discharges is far from being complete. Spontaneous transition of non-thermal atmospheric pressure discharges to thermal discharge and discharge filamentation are among least understood plasma phenomena. The discharge stability and reliable control of plasma parameters are highly desirable for numerous applications. This study focuses on stability of atmospheric pressure glow discharges with respect to filamentation and arcing. Atmospheric pressure glow discharge (APG) is the newest and the most promising addition to the family of non-thermal atmospheric pressure discharges. However this discharge is very susceptible to thermal instability which causes arcing, loss of uniformity and significant damage to electrodes. Suppression of thermal instability and effective control of discharge parameters is critical for industrial applications. A model was developed to understand transition to arc in atmospheric pressure glow discharges. APG discharges that operate in pure helium and in helium with addition of oxygen and nitrogen were considered in these studies. Simulation results indicate that arcing is the result of sheath breakdown rather than thermal instability. It was shown that although sheath breakdown is always followed by overheating the transition to arc in atmospheric glow discharges is not a result of thermal instability. In second part of this research interaction between plasma filaments in dielectric barrier discharges has been studied. This interaction is responsible for the formation of microdischarge patterns reminiscent of two-dimensional crystals. Depending on the application, microdischarge patterns may have a significant influence on DBD performance, particularly when spatial uniformity is desired. A microdischarge interaction model is proposed and a Monte-Carlo simulation of microdischarge interactions in the discharge is presented. A new method for analysis of microdischarge patterns that allow measuring the degree of pattern regularity was developed. Simulated and experimental patterns were compared using the newly developed method. Analysis of microdischarge patterns shows that regularity of the patterns increases with the number of excitation cycles used to produce the pattern.
Chirokov, Alexandre V.
Protein destruction by atmospheric pressure glow discharges
It is well established that atmospheric pressure glow discharges are capable of bacterial inactivation. Much less known is their ability to destruct infectious proteins, even though surgical instruments are often contaminated by both bacteria and proteinaceous matters. In this letter, the authors present a study of protein destruction using a low-temperature atmospheric dielectric-barrier discharge jet. Clear evidences of protein removal are presented with data of several complimentary experiments using scanning electron microscopy, electron dispersive x-ray analysis, electrophoresis, laser-induced fluorescence microscopy, and protein reduction kinetics. Considerable degradation is observed of protein fragments that remain on their substrate surface after plasma treatment.
Deng, X. T.; Shi, J. J.; Chen, H. L.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); MRC Toxicology Unit, University of Leicester, Leicester, Leicestershire LE1 9HN (United Kingdom); Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)
Physical model of spherical glow discharge stratification
A physical model of spherical glow discharge stratification is suggested where the striations represent the electric double layers, where opposite charges, initially separated in space due to fluctuations or ambipolar diffusion, are then stabilized by the specific conditions of the gas media with negative differential conductivity. These conditions appear and disappear during the discharge development owing to plasma-chemical reactions. The model has been tested using time-dependent mass-spectrometry, as well as numerical calculations of the electron transport coefficients for the observed composition.
Belikov, A. E.; Sakhapov, S. Z.
Identifying the warm glow effect in contingent valuation
This paper reports the results from a contingent valuation study designed to investigate the influence of warm glow in willingness to pay (WTP) responses. Interindividual differences in warm glow motivation are measured through a factor analysis, performed on a list of attitudinal items. The reported (WTP) measures fail to pass the scope test. Both socioeconomic variables and motivational factor scores
Paulo A. L. D. Nunes; Erik Schokkaert
Study on an atmospheric pressure glow discharge
Experiments were performed on an atmospheric pressure glow discharge (APGD) in an air gap between two dielectric barrier electrodes. While it is possible to get an APGD in a 2 mm air gap, it is possible to get only a filament discharge in a 5 mm air gap. The development of an electron avalanche in such a gap was numerically simulated. It was found that the critical applied field for a 5 mm electron avalanche to transit to a streamer is equal to 35.07 kV cm-1. This calculated critical applied field is in good agreement with the experimental one. The experimental and theoretical results confirm that only a filament discharge, rather than a glow discharge, can be produced in an atmospheric pressure air gap that is not less than 5 mm if it is not possible to lower the breakdown field of air. A resistive barrier discharge (RBD) was theoretically analysed and the development of RBD was numerically simulated. If a kilohertz discharge is required, the parameters of the resistive layer should be in the range rhovarepsilonr = (109-1011) Omega cm. APGD in a helium gap was realized using 50 Hz line power with a suitably fabricated resistive layer.
Wang, Xinxin; Li, Chengrong; Lu, Mingze; Pu, Yikang
The Glowing Eye of NGC 6751
Astronomers using NASA's Hubble Space Telescope have obtained images of the strikingly unusual planetary nebula, NGC 6751. Glowing in the constellation Aquila like a giant eye, the nebula is a cloud of gas ejected several thousand years ago from the hot star visible in its center. The Hubble observations were obtained in 1998 with the Wide Field and Planetary Camera 2 (WFPC2) by a team of astronomers led by Arsen Hajian of the U.S. Naval Observatory in Washington, DC. The Hubble Heritage team, working at the Space Telescope Science Institute in Baltimore, has prepared this color rendition by combining the Hajian team's WFPC2 images taken through three different color filters that isolate nebular gases of different temperatures. The nebula shows several remarkable and poorly understood features. Blue regions mark the hottest glowing gas, which forms a roughly circular ring around the central stellar remnant. Orange and red show the locations of cooler gas. The cool gas tends to lie in long streamers pointing away from the central star, and in a surrounding, tattered-looking ring at the outer edge of the nebula. The origin of these cooler clouds within the nebula is still uncertain, but the streamers are clear evidence that their shapes are affected by radiation and stellar winds from the hot star at the center.
Abnormal Uterine Bleeding
MENU Return to Web version Abnormal Uterine Bleeding Overview What is abnormal uterine bleeding? Abnormal uterine bleeding is any bleeding from the uterus (through your vagina) other than your normal monthly ...
"Decoking" of a "coked" zeolite catalyst in a glow discharge.
"Decoking" of a "coked" zeolite catalyst in a glow discharge in oxygen is investigated. The "decoking" process involves reactions of atomic oxygen (O atoms) with "coke" and yields gases such as CO, CO(2) as well as other gaseous products that could be easily pumped out. Three different modes of discharge were investigated including a static mode, a flowing-gas mode, and a periodic-purge mode where the oxygen and other gaseous products of the discharge were replaced by fresh O(2)gas after short but regular intervals of time. In some cases, additional heating was also used to provide base temperatures of the order of 100 degrees C to facilitate penetration of oxygen atoms into the inner layers and cages of the zeolite catalyst. This paper presents some results of spectroscopic analytical techniques used to monitor the atomization of oxygen, oxidation of "coke", and to confirm the process of "decoking". More specifically, radiation emission on the 3 s (5)S- 3p (5)P transitions of O around 777.2-777.5 nm were selected for monitoring the atomization of O(2). On the other hand, X-ray photo-electron spectroscopy (XPS) was used to determine the amount of residual carbon and extent of "decoking". Furthermore, evolution of CO and CO(2) gases as a function of time was systematically monitored in real time. For CO, the 451.1 nm band head belonging to the B(1) Sigma - A(1) Pi bands of the Angstrom system of the CO spectrum was used, while for CO(2), the band head at 353.4 nm belonging to the CO(2)(+) spectrum was used. The rates of evolution of CO and CO(2) were related to the rate of "decoking" of the catalyst. It is noted that in the periodic-purge mode, about 63% of the total yield of CO from a given sample of the catalyst appears in the first 3-min exposure to discharge whereas it takes up to 15 min to remove nearly 94% of the removable carbon under our experimental conditions. PMID:12861433
Khan, M A; Al-Jalal, A A; Bakhtiari, I A
The ignition of Li glow discharge is studied for three cases of laser excitation of lithium vapour: the first resonance at 670.8 nm (2s -> 2p transition), the quasiresonant line at 460.3 nm (2p -> 4d), or the two-photon resonant line at 639.1 nm (2s -> 3d transition) below self-breakdown voltage. The conditions for laser ignition of the discharge are described. The differences between the self-breakdown voltage and the breakdown voltage for laser initiation of the discharge are given for the different lithium number densities. We also found experimental conditions for the laser guided discharge in the dense lithium vapor. In addition we studied optogalvanic signal for the blue-green spectral region.
Skenderovic, Hrvoje; Labazan, Irena; Milosevic, Slobodan; Pichler, Goran
Probiotic bacteria induce a 'glow of health'.
Radiant skin and hair are universally recognized as indications of good health. However, this 'glow of health' display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary changes mimicking peak health and reproductive fitness characteristic of much younger animals. Eating probiotic yogurt triggered epithelial follicular anagen-phase shift with sebocytogenesis resulting in thick lustrous fur due to a bacteria-triggered interleukin-10-dependent mechanism. Aged male animals eating probiotics exhibited increased subcuticular folliculogenesis, when compared with matched controls, yielding luxuriant fur only in probiotic-fed subjects. Female animals displayed probiotic-induced hyperacidity coinciding with shinier hair, a feature that also aligns with fertility in human females. Together these data provide insights into mammalian evolution and novel strategies for integumentary health. PMID:23342023
Levkovich, Tatiana; Poutahidis, Theofilos; Smillie, Christopher; Varian, Bernard J; Ibrahim, Yassin M; Lakritz, Jessica R; Alm, Eric J; Erdman, Susan E
Shock wave propagation in glow discharges
The modification of acoustic shock wave propagation characteristics in a 25 cm long positive column low pressure (10 to 50 Torr), low current density (2 to 10 mA/cm^2) argon and N2 dc discharges have been measured by laser beam deflection technique. The simultaneous multi point shock velocity, dispersion and damping have been measured both inside and outside the glow discharge region. The local shock velocity is found to increase with the increased propagation path length through the discharge; for Mach number greater than 1.7 the upstream velocity exceeded the downstream velocity in contrast to the opposite behavior in neutral gas. The damping and dispersion are also dependent on the propagation distance. The recovery of the shock dispersion and damping in the post discharge region, for a given discharge condition, are functions of the initial Mach number. The optical measurement of the wall and the gas (rotational) temperatures suggest the observed shock features can not be solely explained by the gas heating in a self sustained discharge. The results are similar for both Ar and N2 discharges showing that vibrational excitation and relaxation are not essential^1. The explanation of the observed weak shock propagation properties in a glow discharge appears to require long range cooperative interactions that enhance heavy particle collisional energy transfer rates for the measured discharge conditions. Unlike collisional shock wave propagation in highly ionized plasmas^2,3, the exact energy coupling mechanism between the nonequilibrium weakly ionized plasma and shock is not understood. 1. A.I. Osipov and A.V. Uvarov, Sov. Phys. Usp. 35, 903 (1992) and other references there in. 2. M. Casanova, O. Larroche and J-P Matte, Phys. Rev. Lett. 67, 2143 (1991). 3. M.C.M. van de Sanden, R. van den Bercken and D.C. Schram, Plasma Sources Sci.Technol. 3, 511 (1994).
Ganguly, B. N.
Test of the accuracy of the computerized glow curve deconvolution algorithm for the analysis of thermoluminescence glow curves
The accuracy of the thermoluminescence (TL) kinetics parameters obtained using the computerized glow curve deconvolution (CGCD) algorithm was tested. The differential equation governing the electron traffic in the one trap-one recombination (OTOR) level model was solved with almost no approximation using the Fehlberg-Runge-Kutta method. A set of simulated glow peaks was generated for a wide range of kinetics parameter values. These glow peaks were then fitted using the general-order kinetics equation. Comparisons between the kinetics parameter values of the simulated glow peaks and those obtained by the CGCD method were made. The results show that the accuracy of the different kinetics parameters obtained by the CGCD method is not the same and that it varies according to the value of the kinetics order (b). The overlapping of two glow peaks with very close maximum peak positions (Tms) results in a glow peak with unexpected values for the kinetics parameters. A set of different cases of overlapping glow peaks is also discussed.
Sadek, A. M.
Vehicle/Atmosphere Interaction Glows: Far Ultraviolet, Visible, and Infrared
Spacecraft glow information has been gathered from a number of spacecraft including Atmospheric and Dynamic satellites, and Space Shuttles (numerous flights) with dedicated pallet flow observations on STS-39 (DOD) and STS-62 (NASA). In addition, a larger number of laboratory experiments with low energy oxygen beam studies have made important contributions to glow understanding. The following report provides information on three engineering models developed for spacecraft glow including the far ultraviolet to ultraviolet (1400-4000 A), and infrared (0.9-40 microns) spectral regions. The models include effects resulting from atmospheric density/altitude, spacecraft temperature, spacecraft material, and ram angle. Glow brightness would be predicted as a function of distance from surfaces for all wavelengths.
Swenson, G.
One atmosphere glow discharge structure revealed by computer modeling
A one-dimensional and self-consistent model of an atmospheric pressure, dielectric controlled, parallel-plate RF discharge is presented. The computer modeling provided information about the unexpected uniform glow structure of this discharge. The calculated parameters of the plasma, including the electric field, the potential, and the space charge density are analogous to those observed in a normal DC glow discharge. Images of
Rami B. Gadri
Spectra of Cool Flames and PreIgnition Glows
Cool flames and pre-ignition glows of rich and weak mixtures of propane with air and oxygen have been studied in a simple flow system at atmospheric pressure. In the cool-flame region the spectrum shows the usual formaldehyde emission bands, but in the pre-ignition glow near the high-temperature ignition limit the spectrum is quite different, consisting mainly of hydrocarbon flame bands,
A. G. Gaydon; N. P. W. Moore
Generation of Atmospheric-Pressure Glow Discharge and Its Applications 2.Production of Atmospheric-Pressure Glow Discharge
Atmospheric-pressure glow (APG) discharge is one of the more interesting fields of recent study owing to its possible applications in plasma processing, surface treatment, sterilization, etc. This field was developed by Okazaki and Kogoma et al. of the Sophia University group in 1988, and has spread world wide. Usually, a glow discharge is difficult to keep stable at atmospheric gas pressure because glow-to-arc transition occurs due to thermalization of the plasma. However, some methods have been presented to produce stable glow plasma at atmospheric gas pressure; 1) inserting a dielectric plate between electrodes, 2) applying pulsed voltage having a pulse width shorter than the thermalization time, 3) use of a micro-hollow cathode configuration, etc. This article describes the generation of AGP mainly using the dielectric plate. Numerical analysis based on continuity equations of charged species and Poisson's equation is also described.
Takaki, Koichi; Fujiwara, Tamiya; Tochikubo, Fumiyoshi
An atmospheric pressure glow discharge optical emission source for the direct sampling of liquid media.
A glow discharge optical emission spectroscopy (GD-OES) source that operates at atmospheric pressure is described. This device utilizes an electrolytic solution containing the analyte specimen as one of the discharge electrodes. The passage of electrical current (either electrons or positive ions) across the solution/gas phase interface causes local heating and the volatilization of the analyte species. Collisions in the discharge region immediately above the solution surface result in optical emission that is characteristic of the analyte elements. Operation of this device with the analyte solution acting as either the cathode or anode is demonstrated. Current-voltage (i-V) plots reveal abnormal glow discharge characteristics, with operating parameters being dependent on the electrolyte concentration (i.e., solution conductivity) and the gap between the solution surface and the counterelectrode. Typical conditions include discharge currents of 30-60 mA, and potentials of 500-900 V. Electrolyte solutions having pH, pNa, or pLi values of 0.5-2 and interelectrode gaps of 0.5-3 mm produce stable plasmas in which the analyte solutions flow at rates of up to 3.0 mL/min. Preliminary limits of detection are determined for the elements Na, Fe, and Pb to be in the range of 11-14 ppm (approximately 60 ng) for 5-microL sample volumes. PMID:11467534
Marcus, R K; Davis, W C
Microsecond pulsed glow discharge source in ``Element GD'' and ``VG 9000'' mass-spectrometers
Microsecond pulsed glow discharge (PGD) may consume several kW of instantaneous power that may lead to a significant increase of a sample atoms excitation and ionization efficiency. Improvement of analytical characteristics of a glow discharge source using pulsed mode of power supply is demonstrated earlier for different optical and mass spectral methods (Drobyshev, Turkin 1981, Bengtson et al. 2000, Huang et al. 1991, Hang et al. 1996, 1994, Farnsworth, Walters 1982), including fast flow ion source (Voronov, Hoffmann 2007). However, practical use of microsecond PGD is limited to scientific investigations. In this work the microsecond PGD is applied to existing commercial mass-spectrometers ``Element GD'' and ``VG 9000'' to develop a system, which can be used in commercial routine analysis. Investigations are focused on possibilities of analysis with microsecond PGD and in comparison of PGD in fast flow source (``Element GD'') and usual Grimm type source (``VG 9000''). Detection limits in DC and PGD modes are investigated and compared. The secondary discharge in Grimm type fast flow source was discovered in (Voronov, Hoffmann 2007), and it certainly exists in ``Element GD'' instrument. However, practical application of the secondary discharge for improvement of analytical properties of the instrument is not clear. To answer this question, dynamics of ions extracted from the discharge pulses is measured using earlier developed method (Voronov, Hoffmann 2007) (see the fig.). Based on the measured ion dynamics and results of the PGD numerical simulation, influence of the secondary discharge in ``Element GD'' instrument is discussed.
Voronov, M.; Hofmann, Th.; Venzago, C.
Analysing bifurcations encountered in numerical modelling of current transfer to cathodes of dc glow and arc discharges
Bifurcations and/or their consequences are frequently encountered in numerical modelling of current transfer to cathodes of gas discharges, also in apparently simple situations, and a failure to recognize and properly analyse a bifurcation may create difficulties in the modelling and hinder the understanding of numerical results and the underlying physics. This work is concerned with analysis of bifurcations that have been encountered in the modelling of steady-state current transfer to cathodes of glow and arc discharges. All basic types of steady-state bifurcations (fold, transcritical, pitchfork) have been identified and analysed. The analysis provides explanations to many results obtained in numerical modelling. In particular, it is shown that dramatic changes in patterns of current transfer to cathodes of both glow and arc discharges, described by numerical modelling, occur through perturbed transcritical bifurcations of first- and second-order contact. The analysis elucidates the reason why the mode of glow discharge associated with the falling section of the current-voltage characteristic in the solution of von Engel and Steenbeck seems not to appear in 2D numerical modelling and the subnormal and normal modes appear instead. A similar effect has been identified in numerical modelling of arc cathodes and explained.
Almeida, P. G. C.; Benilov, M. S.; Cunha, M. D.; Faria, M. J.
Plasma non-equilibrium of the DC normal glow discharges in atmospheric pressure atomic and molecular gases
Electrical and spectroscopic results of comprehensive investigations of atmospheric pressure glow discharges in helium, argon, nitrogen and air in a large current range are presented. Our attention in these investigations is mainly focused on the characterization of positive column plasmas at discharge gap of 10 mm. It was shown that helium, nitrogen and air positive columns transform from diffuse to constricted mode when discharge current increases. In argon discharge, it is constricted in the whole range of investigated currents. Reduced electric field, gas temperature, average electron energy and electron concentration were determined. The positive column plasmas of all the atmospheric pressure glow discharges studied are non-equilibrium and weakly ionized. Plasma non-equilibrium degree in atomic gases of helium and argon is essentially higher than in molecular nitrogen and air. For all gases, plasma non-equilibrium degree in a positive column decreases with discharge current increase.
Arkhipenko, V. I.; Kirillov, A. A.; Safronau, Y. A.; Simonchik, L. V.; Zgirouski, S. M.
Abnormal glow discharge in crossed electric and magnetic fields in the presence of reactive gas
The results of investigations of the low-temperature plasma at process of reactive magnetron sputtering of Ti target in the presence of reactive gas are described. Discharge volt-ampere characteristics for different schemas of reactive gas input are build. Optimal regimes of making strengthening coatings are defined. TiOx (0 < x < 2) strengthening coatings at plastics are made. Coatings showed high consumer qualities.
Luchkin, A. G.; Kashapov, N. F.; Luchkin, G. S.
A Cathode-Anode Configuration for an Abnormal Glow Discharge with Long Term Stability.
The essential feature in this cathode-anode configuration is that the wall is made up of metal rings which are insulated from each other. Sputtering cannot short the insulators. The disk cathodes can be manufactured from a variety of conducting materials....
K. H. Geissler P. A. Nichols R. A. Greenwald
Skeletal limb abnormalities
Skeletal limb abnormalities refer to a variety of bone structure problems in the arms or legs (limbs). ... Skeletal limb abnormalities are most often used to describe defects in the legs or arms that are ...
Enhanced Glow Discharge Production of Oxygen
Studies starting in late seventies have shown Mars atmosphere can be used as a feedstock for oxygen production using simple chemical processing systems during early phases of the Mars exploration program. This approach has been recognized as one of the most important in-situ resource utilization (ISRU) concepts for enabling future round trip Mars missions. It was determined a decade ago that separation of oxygen can be accomplished efficiently by permeation through a silver membrane at temperatures well below 1000 K. This process involves adsorption of atomic oxygen on the surface and its subsequent diffusion through a silver lattice via an oxygen concentration gradient. We have determined recently that glow discharge can be used to liberate atomic oxygen from Mars atmosphere and that the oxygen can be collected through a silver permeation membrane. Recently, we demonstrated a substantial increase in energy efficiency of the process by applying a radio frequency discharge in combination with a silver permeation membrane. The experiments were performed using pure carbon dioxide in the pressure range equal to Mars surface conditions. Energy efficiency was defined as the ratio of the energy required to dissociate a unit mass of oxygen from carbon dioxide to the (electrical) energy consumed by the overall system during the dissociation and collection process. The research effort, started at NASA Langley Research Center, continued with this project. Oxygen production apparatus, built and operated under the research grant NAG1-1140 was relocated to the Atomic Beams Laboratory at ODU in July 1996, being since then in fall operation.
Ash, Robert; Zhong, Shi
Boundary Phenomena in RF and DC Glow Discharge Dusty Plasmas
In experimental investigations of dusty or complex plasmas, studies have been performed primarily using dc or rf glow discharge plasmas. In spite of the similarity of the experimental parameters produced by each of these plasma generation techniques, the addition of charged microparticles to these plasmas often leads to different phenomena. This paper discusses the similarities and differences in particle transport observed at the boundary between the microparticle clouds and the surrounding plasma. Results will highlight experimental studies performed using two different dc glow discharge dusty plasma experiments - the Auburn Dusty Plasma Experiment (DPX) and the Naval Research Laboratory DUPLEX experiment - and an rf glow discharge dusty plasma experiment - the Plasma-Kristall Experiment (PKE-Nefedov) at Max-Planck-Institut f�r Extraterrestrische Physik. Sheath-like structures are observed at the particle cloud - plasma interface in all three cases.
Thomas, Edward; Amatucci, William E.; Morfill, Gregor E.
Deposition and examination of glow discharge produced a-Ge:H
This thesis presents the results of studies of the deposition and examination of amorphous hydrogenated germanium (a-Ge:H) thin films deposited from an rf glow discharge of GeH[sub 4] and H[sub 2] gases. A diode-type capacitively coupled glow discharge system was constructed. Results are presented of the measurements of film stress for a large number of a-Ge:H films. The stress is found to vary from high tensile to high compressive, and correlates with total hydrogen content, microstructure and photoconductivity. The effects of air exposure and annealing are demonstrated. Two examples are given of the effects of varying a deposition parameter on the film properties; the effects of varying the electrode gap and the power. By piecing together extensive measurements of optical, electronic and structural properties, the electrode gap study is used to demonstrate the link between structure and electronic transport, and to clarify an earlier model of a-Ge:H film structure. The results suggest a strategy for further optimization of a-Ge:H optoelectronic properties by adjusting growth conditions to reduce the formation of columnar-type microstructure. Finally, a basic examination of the GeH[sub 4] + H[sub 2] glow discharge is presented. It is determined that the discharges used to deposit a-Ge:H are in the so called [gamma] mode in which the discharge characteristics are dominated by ion-induced electron emission ([gamma] electrons) from the cathode. Using a residual gas analyzer (RGA), an examination is made of discharge chemistry which centers around a comparison of SiH[sub 4] + H[sub 2] chemistry. Significant differences between SiH[sub 4] + H[sub 2] and GeH[sub 4] + H[sub 2] chemistry are demonstrated. Measurements were then made to determine the changes which occur in the glow discharge when the electrode gap and power are varied. The results suggest that beneficial discharge chemistry is promoted by a higher kinetic energy of the electrons in the discharge.
Wickboldt, P.
Influences of impedance matching network on pulse-modulated radio frequency atmospheric pressure glow discharges
Pulse-modulated RF atmospheric pressure glow discharges (APDGs) were investigated in recent years to reduce the thermal accumulation and extend the operation region of the stable alpha glow mode. Different pulse-modulated voltage and current waveforms were acquired in previous experiments, but no attention was paid to the interpretation. We investigated this issue and associated phenomenon via positive and negative feedback effects derived from varying the series capacitor in the inversely L-shaped matching network used in our pulse-modulated RF APGD source. The evolutions of pulse-modulated RF waveforms were found to be associated with the feedback region and the pulsed plasma absorbed RF power. In the positive feedback region, pulse-modulated RF APGDs are relatively stable. In the negative feedback region, wide spikes as well as undershoots occur in RF voltage and current waveforms and the plasma absorbed RF power. In case of a high RF power discharge with a low modulation frequency, the pulse-modulated RF APGD is extinguished and re-ignited due to the enhanced undershoot during the initial pulse phase. The pulse-modulated RF APGD can transit from positive to negative feedback region in a range of series capacitance. Experimental results are discussed by the aid of equivalent circuit, negative and positive feedback effects.
Huo, W. G.; Xu, K.; Sun, B.; Ding, Z. F.
Decomposition Of Benzene By A Low Pressure Glow Discharge
Decomposition characteristics of diluted benzene with nitrogen in a low pressure DC glow discharge plasma are investigated by emission spectroscopy, mass spectrometry, infrared absorption spectroscopy, concentration measurement and gas pressure monitoring. It is likely that benzene is decomposed chiefly by electron collision, and that excite molecules of nitrogen and/or nitrogen ions do not make a large contribution to benzene destruction directly. It is found that H, H2, H3, C, CH, CH4, NH3, C2, C2H, CN, C2H2, and C2H4 are produced in the glow discharge.
Satoh, K.; Sawada, T.; Naitoh, T.; Itoh, H.; Shimozuma, M.; Tagashira, H.
Charge Transfer to MEMS Pressure Sensors By Glow Discharge Plasmas
Electrical charging resulting in temporary performance degradation of automotive MEMS pressure sensors has been observed. A method of charge transfer from the outside of a statically charged hose, along the inside the hose, through the module port, to a sensor inside the module is proposed. Specifically, the existence of a glow discharge plasma through the hose, is analyzed with respect
T. M. Betzner
Metal Mesh Smear Sampling for Glow Discharge Analytical Spectroscopy
Metal mesh smear sampling is being developed and evaluated for use in a number of glow discharge and other optical and mass spectrometric techniques. Sensitive elemental and isotopic analyses thus will be coupled with a convenient sampling scheme similar to one that is common for radiological surveys.
Shaw, R.W.; Barshick, C.M.; Ramsey, J.M.; Smith, D.H.
Evolution of nonlinear ionization wave packets excited in glow discharges
The evolution of envelope solitons of ionization wave packets with finite amplitude is observed in positive columns of He glow discharges. The wave packet excited by a high-voltage pulse divides into two or three packets with propagation along the discharge tube. The divided wave packets can be regarded as envelope solitons by evaluating the coefficients of the nonlinear Schro�dinger equation
Kazuyuki Ohe; Masashi Hashimoto
Electron Heating in Pulsed Atmospheric Pressure Glow Discharges
Atmospheric pressure glow discharges in air and noble gases have been operated by using microhollow cathode discharges as plasma cathodes [1]. In these discharges the electron energy distribution is determined by the value of the reduced electric field (E\\/N). Pulsing the discharges causes the electron energy distribution to shift into an energy range where the ionization rate increases strongly. In
Robert H. Stark; Frank Leipold; Chunqi Jiang; Hisham Merhi; Karl H. Schoenbach
High electron density, atmospheric pressure air glow discharges
The pulsed electron heating effect has been studied on an atmospheric pressure air glow discharge. Application of a high voltage pulse causes a shift in the electron energy distribution function to higher energies. This causes a temporary increase of the ionization rate and consequently an increase of the electron density. The electron density after a 10 ns pulse application to
Frank Leipold; Abdel-Aleam H. Mohamed; Karl H. Schoenbach
Computational modeling of glow discharge-induced fluid dynamics
Glow discharge at atmospheric pressure using a dielectric barrier discharge can induce fluid flow and operate as an actuator for flow control. The largely isothermal surface plasma generation realized above can modify the near-wall flow structure by means of Lorentzian collisions between the ionized fluid and the neutral fluid. Such an actuator has advantages of no moving parts, performance at
Balaji Jayaraman
DC glow discharge conditioning of remote areas in fusion devices
Various methods are used for wall conditioning of the vacuum chamber of magnetic fusion devices. Among them, direct current glow discharges in deuterium or helium are used to control the contamination of the plasma by impurities coming from the walls. However, the relatively high energy of the ions on the plasma facing components and the difficulty to extend the glow discharge in remote areas could reduce their attractiveness. We present the results from tests performed in a dedicated reactor, equipped with a narrow cylindrical duct with seven Langmuir probes. A heated cathode, biased at -40 Volts with respect to the walls, is placed inside the duct. The influence of the pressure on the penetration of the discharge into the tube is shown and discussed. Significant values of ion current and potential in the tube are obtained for pressures two orders of magnitude higher than those currently used in present Tokamaks. The effect of establishing the glow discharge between the anode and the heated cathode was studied. The heated cathode currents can be tuned in such a way that the current measured by the probe increases whereas the potential drop between the glow discharge and the wall decreases and the energy of the ions which are impinging onto the surfaces is reduced.
Douai, D.; Garnier, D.; Br�mond, S.; Grisolia, C.; Bucalossi, J.; Shigin, P.; Begrambekov, L.
Studying surface glow discharge for application in plasma aerodynamics
Surface glow discharge in nitrogen between two infinite planar electrodes occurring on the same plane has been studied in the framework of a diffusion-drift model. Based on the results of numerical simulations, the plasma structure of this discharge is analyzed and the possibility of using it in plasma aerodynamics is considered.
Tereshonok, D. V.
Circadian spontaneous bioluminescent glow and flashing of Gonyaulax polyedra
A new, fully computerized method for the measurement and analysis of dinoflagellate bioluminescence has been developed and applied to the spontaneous light emission ofGonyaulax polyedra. This light emission consists of a low-level steady glow, and occasional superimposed flashes. The instrumentation distinguishes the two components and records them separately; both exhibit circadian rhythmicity. In this paper we describe the method in
Richard Krasnow; Jay C. Dunlap; Walter Taylor; J. W. Hastings; W. Vetterling; V. Gooch
Mechanism of boriding from pastes in a glow discharge
The authors investigate the boridation of steel 45 from the standpoint of the glow-discharge dissociation of a borax paste and the plasma arc spraying of the resulting boron into the steel. The effects of process parameters on the impregnation of boron into the steel and its phase behavior in the boridation process are discussed.
Isakov, S.A.; Al'tshuler, S.A.
Degradation of Organics in a Glow Discharge Under Martian Conditions
The primary objective of this project is to understand the consequences of glow electrical discharges on the chemistry and biology of Mars. The possibility was raised some time ago that the absence of organic material and carbonaceous matter in the Martian soil samples studied by the VikinG Landers might be due in part to an intrinsic atmospheric mechanism such as glow discharge. The high probability for dust interactions during Martian dust storms and dust devils, combined with the cold, dry climate of Mars most likely results in airborne dust that is highly charged. Such high electrostatic potentials generated during dust storms on Earth are not permitted in the low-pressure CO2 environment on Mars; therefore electrostatic energy released in the form of glow discharges is a highly likely phenomenon. Since glow discharge methods are used for cleaning and sterilizing surfaces throughout industry, the idea that dust in the Martian atmosphere undergoes a cleaning action many times over geologic time scales appears to be a plausible one.
Hintze, P. E.; Calle, L. M.; Calle, C. I.; Buhler, C. R.; Trigwell, S.; Starnes, J. W.; Schuerger, A. C.
Fluorination of polymethylmethaacrylate with tetrafluoroethane using DC glow discharge plasma
Fluorination of polymer surfaces has technological applications in various fields such as microelectronics, biomaterials, textile, packing, etc. In this study PMMA surfaces were fluorinated using DC glow discharge plasma. Tetrafluoroethane was used as the fluorinating agent. On the fluorinated PMMA surface, static water contact angle, surface energy, optical transmittance (UV�vis), XPS and AFM analyses were carried out. After the fluorination
S. Guruvenket; Ganjigunte R. S. Iyer; Larisa Shestakova; Per Morgen; N. B. Larsen; G. Mohan Rao
Positive Streamers and Glows in Air and Exhaust Gases
Theoretical and experimental studies have been made of the effects of sub-microsecond voltage pulses on the plasma chemistry of real flue gases in a test cell. Chemical analysis shows that, for real flue gases, the pulsed system can remove up to 90 % of NO, and 30 % of SO_2, if a residence time of ~ 30s is used. We also find that (i) water vapour is essential to the removal of SO_2, but not for the removal of NO or NO_2; and (ii) that small quantities of N_2O are produced. The removal of SO2 is primarily due to reactions with OH radicals from water vapour, producing sulphuric acid, whereas nitrogen oxides are reduced by N atoms. When a positive voltage is abruptly applied to a point in air at atmospheric pressure, positive streamers are produced. A theory is presented for the development of the first such streamer by solving the continuity equations for electrons, positive ions and negative ions, including the effects of ionisation, attachment, recombination, electron diffusion, and photoionisation, simultaneously with Poisson's equation. With an applied voltage of 20 kV across a 50 mm gap, the streamer does not reach the cathode. When the voltage is sustained in the presence of free electrons, the electric field at the anode starts to recover until positive glow pulses develop at the anode. The presence of the positive glow corona precludes any further streamer formation; this limits the number of chemical reactions stimulated by the discharge because the positive glow is confined close to the anode. Thus, a limit is set for the voltage pulse width. A theory is also presented for the current and light pulses of positive glow corona from a point in air; results are obtained by solving the continuity equations, described above, in concentric sphere geometry. A series of ``saw--toothed'' current pulses of period ~ 1 ?s are predicted with a dc current level. Accompanying the current peaks are discrete 30 ns wide pulses of light. It is found that if, in the presence of a positive glow corona, the voltage is raised at a rate less than 1 kV/?s, the the positive glow corona adjusts to the positive glow corona conditions at a higher voltage; however, if the voltage is raised at a significantly faster rate, streamers develop and propagate out into the gap. Thus, the need for sub--microsecond voltage pulses in order to produce positive streamers can be shown theoretically, and limits determined for the rise time required for the stimulation of chemical reactions.
Morrow, R.
Apparent secondary-electron emission coefficient and the voltage-current characteristics of argon glow discharges.
The accuracy of secondary-electron emission coefficients, that are used as input data of discharge models, seriously influences the calculated discharge characteristics. As it is very difficult to consider all possible electron emission processes of a cold cathode separately, in most of the recent models an apparent secondary coefficient gamma is applied, which is often assumed to be constant, even for a wide range of discharge conditions. In contrast with this common assumption, the present calculations-based on a heavy-particle hybrid model-show that in abnormal glow discharges gamma varies considerably with changing discharge conditions: a factor of 3 change of gamma has been found in the range of reduced current densities (0.04 mA cm(-2) Torr(-2)< or =j/p(2)< or =4 mA cm(-2) Torr(-2)) covered in this study. The present simulations also confirm that ionization by heavy particles plays a significant role in the ion production at the abnormal cathode fall. Moreover, it is shown, that the fast heavy particles reflected from the cathode surface play the dominant role in the gas heating. PMID:11497705
Donk�, Z
Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol
Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure {alpha}-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.
Sun Wenting; Li Guo; Li Heping; Bao Chengyu; Wang Huabo; Zeng Shi; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)
Stimulated Electromagnetic Emission Indicator of Glow Plasma Discharges from Ionospheric HF Wave Transmissions with HAARP
High power radio waves resonantly interact with to accelerate electrons for production of artificial aurora and plasma clouds. These plasma clouds are formed when the HF frequency is tuned near a harmonic of the electron cyclotron frequency. At a narrow band resonance, large electrostatic fields are produced below the F-layer and the neutral atmosphere breaks down with a glow plasma discharge. The conditions for this resonance are given by matching the pump wave frequency and wave-number with the sum of daughter frequencies and wave-numbers for several plasma modes. The most likely plasma mode that accelerates the electrons is the electron Bernstein wave in conjunction with an ion acoustic wave. Both upper hybrid and whistler mode waves are also possible sources of electron acceleration. To determine the plasma process for electron acceleration, stimulated electromagnetic emissions are measured using ground receivers in a north-south chain from the HAARP site. Recent observations have shown that broad band spectral lines downshifted from the HF pump frequency are observed when artificial plasma clouds are formed. For HF transmissions are the 2nd, 3rd, and 4th gyro harmonic, the downshifted indicators are found 500 Hz, 20 kHz, and 140 kHz, respectively, from the pump frequency. This Indicator Mode (IM) anticipates that a plasma layer will be formed before it is recorded with an ionosonde or optical imager.
Bernhardt, P. A.; Scales, W.; Briczinski, S. J.; Fu, H.; Mahmoudian, A.; Samimi, A.
Urine - abnormal color
The usual color of urine is straw-yellow. Abnormally colored urine may be cloudy, dark, or blood-colored. ... Abnormal urine color may be caused by infection, disease, medicines, or food you eat. Cloudy or milky urine is a sign ...
Single-target DC-pulsed deposition of lead zirconate titanate thin films: Investigation of the chemical and mechanical properties by glow-discharge optical emission spectroscopy and nanoindentation
Reactive sputtering of a single metallic target in a pulsed DC mode is a promising approach for a fast and cost-efficient deposition of thin lead zirconate titanate (PZT) films on an industrial scale. Rapid depth profiling of the coatings is necessary for an efficient optimization of the process parameters. We demonstrate in this paper that glow-discharge optical emission spectroscopy is
P. Schwaller; A. Fischer; R. Thapliyal; M. Aeberhard; J. Michler; H. J. Hug
Morphological abnormalities among lampreys
USGS Publications Warehouse
The experimental control of the sea lamprey (Petromyzon marinus) in the Great Lakes has required the collection of thousands of lampreys. Representatives of each life stage of the four species of the Lake Superior basin were examined for structural abnormalities. The most common aberration was the presence of additional tails. The accessory tails were always postanal and smaller than the normal tail. The point of origin varied; the extra tails occurred on dorsal, ventral, or lateral surfaces. Some of the extra tails were misshaped and curled, but others were normal in shape and pigment pattern. Other abnormalities in larval sea lampreys were malformed or twisted tails and bodies. The cause of the structural abnormalities is unknown. The presence of extra caudal fins could be genetically controlled, or be due to partial amputation or injury followed by abnormal regeneration. Few if any lampreys with structural abnormalities live to sexual maturity.
Manion, Patrick J.
Volcanic Eruption in Java, Brilliant Sunset Glows in 1901, and Probable Glows from the Eruption in Martinique
THE brilliant sky glows and sunsets following the eruption of Krakatoa, near Java, on August 26 and 27, 1883, threw a flood of light on the movements of the upper atmosphere in a way which was probably not otherwise possible. Up to that time it had been supposed generally by meteorologists that the air forming the trade winds ascended at
Henry Helm Clayton
Abnormal menstrual periods (image)
... may have a variety of causes, such as endometrial hyperplasia, endometrial polyps, uterine fibroids, and abnormal thyroid or ... the endometrium becomes unusually thick it is called endometrial ... Hyperplasia may cause profuse or extended menstrual bleeding.
Abnormal haemoglobins: detection & characterization
Haemoglobin (Hb) abnormalities though quite frequent, are generally detected in populations during surveys and programmes run for prevention of Hb disorders. Several methods are now available for detection of Hb abnormalities. In this review, the following are discussed: (i) the methods used for characterization of haemoglobin disorders; (ii) the problems linked to diagnosis of thalassaemic trait; (iii) the strategy for detection of common Hb variants; and (iv) the difficulties in identification of rare variants. The differences between developing and industrialized countries for the strategies employed in the diagnosis of abnormal haemoglobins are considered. We mention the limits and pitfalls for each approach and the necessity to characterize the abnormalities using at least two different methods. The recommended strategy is to use a combination of cation-exchange high performance chromatography (CE-HPLC), capillary electrophoresis (CE) and when possible isoelectric focusing (IEF). Difficult cases may demand further investigations requiring specialized protein and/or molecular biology techniques.
Wajcman, Henri; Moradkhani, Kamran
Tooth - abnormal colors
Abnormal tooth color is any color other than the white to yellowish-white of normal teeth. ... things can cause tooth discoloration. The change in color may affect the entire tooth, or just appear ...
Chromosomal Abnormalities and Schizophrenia
Schizophrenia is a common and serious psychiatric illness with strong evidence for genetic causation, but no specific loci yet identified. Chromosomal abnormalities associated with schizophrenia may help to understand the genetic complexity of the illness. This paper reviews the evidence for associations between chromosomal abnormalities and schizophrenia and related disorders. The results indicate that 22q11.2 microdeletions detected by fluorescence in-situ hybridization (FISH) are significantly associated with schizophrenia. Sex chromosome abnormalities seem to be increased in schizophrenia but insufficient data are available to indicate whether schizophrenia or related disorders are increased in patients with sex chromosome aneuploidies. Other reports of chromosomal abnormalities associated with schizophrenia have the potential to be important adjuncts to linkage studies in gene localization. Advances in molecular cytogenetic techniques (i.e., FISH) have produced significant increases in rates of identified abnormalities in schizophrenia, particularly in patients with very early age at onset, learning difficulties or mental retardation, or dysmorphic features. The results emphasize the importance of considering behavioral phenotypes, including adult onset psychiatric illnesses, in genetic syndromes and the need for clinicians to actively consider identifying chromosomal abnormalities and genetic syndromes in selected psychiatric patients.
Radiation effects on ETFE polymer exposed to glow discharge
The polymer ethylenetetrafluoroethylene (ETFE) is composed of alternating ethylene and tetrafluoroethylene segments. Because it has applications in areas such as medical physics and industrial coatings, there is a great interest in surface modification studies of ETFE polymer. When this material is exposed to ionizing radiation it suffers damage that depends on the type, energy and intensity of the irradiation. In order to determine the radiation damage mechanism from exposure to low voltage plasma, ETFE films were exposed to residual gas plasma in glow discharge regime to a fluence of 2 � 10 17 ions/cm 2. Irradiated films were analyzed with optical absorption photospectrometry, Fourier transform infrared (FTIR) and Raman spectroscopy to determine the chemical nature of the structural changes caused by low energy glow discharge.
Minamisawa, Renato Amaral; Abidzina, Volha; de Almeida, Adelaide; Budak, Satilmis; Tereshko, I.; Elkin, I.; Ila, Daryush
Sensitive glow discharge ion source for aerosol and gas analysis
A high sensitivity glow discharge ion source system for analyzing particles includes an aerodynamic lens having a plurality of constrictions for receiving an aerosol including at least one analyte particle in a carrier gas and focusing the analyte particles into a collimated particle beam. A separator separates the carrier gas from the analyte particle beam, wherein the analyte particle beam or vapors derived from the analyte particle beam are selectively transmitted out of from the separator. A glow discharge ionization source includes a discharge chamber having an entrance orifice for receiving the analyte particle beam or analyte vapors, and a target electrode and discharge electrode therein. An electric field applied between the target electrode and discharge electrode generates an analyte ion stream from the analyte vapors, which is directed out of the discharge chamber through an exit orifice, such as to a mass spectrometer. High analyte sensitivity is obtained by pumping the discharge chamber exclusively through the exit orifice and the entrance orifice.
Reilly, Peter T. A. (Knoxville, TN)
Pulsed and RF glow discharge in Helium atmosphere
This paper reports the optical and electrical characterization of sinusoidal and pulse glow-discharge plasma in helium. A homogeneous type of discharge has been observed for different operating conditions in helium DBD. The image of discharges makes sure that the diffuse discharge covers the entire surface of the electrodes. Optical emission spectroscopy has been used to determine the main emission lines of the helium glow discharge plasma. The internal plasma parameters of DBDs have been investigated at different operating conditions. It has been observed that the DBDs are becoming more intense with increase in pressure and applied power. The effect of the excitation mechanism on the emission properties and discharge parameters for the helium DBD is studied experimentally and further analysed by using plasma simulation tool OOPIC-Pro.
Gulati, Pooja; Pal, U. N.; Kumar, N.; Srivastava, V.; Parkash, Ram; Vyas, Vimal
The Use of DC Glow Discharges as Undergraduate Educational Tools
Plasmas have a beguiling way of getting students excited and interested in physics. We argue that plasmas can and should be incorporated into the undergraduate curriculum as both demonstrations and advanced investigations of electromagnetism and quantum effects. Our device, based on a direct current (DC) glow discharge tube, allows for a number of experiments into topics such as electrical breakdown, spectroscopy, magnetism, and electron temperature.
Stephanie A. Wissel and Andrew Zwicker, Jerry Ross, and Sophia Gershman
Sterilization of medical productsin low-pressure glow discharges
Results are presented from experimental and theoretical studies of the sterilization of medical products by the plasmas of\\u000a dc glow discharges in different gas media. The sterilization efficiency is obtained as a function of discharge parameters.\\u000a The plasma composition in discharges in N2 and O2 is investigated under the operating conditions of a plasma sterilizer. It is shown that free
I. A. Soloshenko; V. V. Tsiolko; V. A. Khomich; A. I. Shchedrin; A. V. Ryabtsev; V. Yu. Bazhenov; I. L. Mikhno
Origin of anomalous emission in superdense glow discharge
A theory, supported by new experimental data, for recently observed anomalous large pseudospark and backlighted thyratron cathode emission into a superdense glow discharge is reported. The current density at the cathode surface, ~=10 kA\\/cm2, is produced by an ion ``beam,'' extends over a surface area of ~=1 cm2, and is orders of magnitudes larger than that of heated thermionic cathodes.
W. Hartmann; M. A. Gundersen
Nuclear product ratio for glow discharge in deuterium
New results for glow discharge in deuterium calorimetry are presented. In separate experiments a heat output five times exceeding the input electric power was observed. The result for the charged particle spectrum measurement is presented. Charged particles with energies up to 18 MeV and an average energy of 2-4 MeV were seen. Beams of gamma-rays with energies of about 200
A. B. Karabut; R. Kucherov; I. B. Savvatimova
Characterization of polymeric films produced by glow discharge
Polymeric coatings have been grown on steel 1016 substrates; the process has been performed by glow discharge in a chamber with acetylene at 1 mbar of pressure. Emission spectra have been taken during the discharge in order to identify the species of the plasma and to study plasma reactions. High-resolution atomic force microscopic (AFM) images of the coatings have been carried out. Moreover, infrared spectra were taken on the coating. .
Botero, M. A.; Devia, A.; Restrepo, E.; Alvarez, L.
Experimental control of chaos in a periodically driven glow discharge
The control of the chaotic state of ionization waves in the positive column of a periodically driven neon glow discharge is achieved by an active feedback technique based on the algorithm suggested by Ott, Grebogy, and Yorke [Phys. Rev. Lett. 64, 1196 (1990)]. Unstable periodic orbits of both low and high periodicity could be stabilized by small, time-dependent variations of the modulation amplitude.
Weltmann, K.-D.; Klinger, T.; Wilke, C.
Inception of Snapover and Gas Induced Glow Discharges
Ground based experiments of the snapover phenomenon were conducted in the large vertical simulation chamber at the Glenn Research Center (GRC) Plasma Interaction Facility (PIF). Two Penning sources provided both argon and xenon plasmas for the experiments. The sources were used to simulate a variety of ionospheric densities pertaining to a spacecraft in a Low Earth Orbital (LEO) environment. Secondary electron emission is believed responsible for dielectric surface charging, and all subsequent snapover phenomena observed. Voltage sweeps of conductor potentials versus collected current were recorded in order to examine the specific charging history of each sample. The average time constant for sample charging was estimated between 25 and 50 seconds for all samples. It appears that current drops off by approximately a factor of 3 over the charging time of the sample. All samples charged in the forward and reverse bias directions, demonstrated hysteresis. Current jumps were only observed in the forward or positive swept voltage direction. There is large dispersion in tile critical snapover potential when repeating sweeps on any one sample. The current ratio for the first snapover region jumps between 2 and 4.6 times, with a standard deviation less than 1.6. Two of the samples showed even larger current ratios. It is believed the second large snapover region is due to sample outgassing. Under certain preset conditions, namely at the higher neutral gas background pressures, a perceptible blue-green glow was observed around the conductor. The glow is believed to be a result of secondary electrons undergoing collisions with an expelled tenuous cloud of gas, that is outgassed from the sample. Spectroscopic measurements of the glow discharge were made in an attempt to identify specific lines contributing to the observed glow.
Galofaro, J. T.; Vayner, B. V.; Degroot, W. A.; Ferguson, D. C.; Thomson, C. D.; Dennison, J. R.; Davies, R. E.
Synthesis and characterization of heparinized polyurethanes using plasma glow discharge
Polyurethanes (PU) were synthesized from 4,4?-diphenylmethane diisocyanate and polytetramethylene glycol, and subsequently with ethylene diamine as a chain extender. The PU film was exposed to oxygen plasma glow discharge to produce peroxides on the surfaces. These peroxides were then used as catalysts for the copolymerization of acrylic acid (AA) and methyl acrylate (MA) in order to prepare carboxyl group-introduced PU
Jung-Sook Bae; Eun-Jin Seo; Inn-Kyu Kang
Analysis of thermoluminescent glow peaks of zoisite under beta irradiations
In this study, the thermoluminescence (TL) properties of natural crystal of zoisite were investigated after beta (90Sr) irradiation at room temperature (RT). Zoisite, of chemical formula Ca2Al3(SiO4)(Si2O7)O(OH), is found in Minas Gerais State, Brazil as natural mineral of silicate, member of the epidote group. The glow curve of a natural sample submitted to a heat treatment at 600 �C is composed of two broad peaks, centered at about 110-130 �C and another one at about 205-210 �C. A heating rate of 4 �C s-1 was used in the temperature range from RT to 300 �C. The additive dose, Tm-TSTOP thermal cleaning, initial rise, variable heating rate and computerized glow curve deconvolution methods have shown that the glow curve is a superposition of six peaks at 100, 130, 155, 175, 200 and 230 �C. The trapping parameters for the individual peaks have been calculated. The TL dose response of 130 and 200 �C peaks has a linear response. Zoisite is a candidate for a TL dosimeter because of its high sensitivity.
Ccallata, Henry Javier; Watanabe, Shigueo
Development of blood compatible materials by glow discharge-treatment
Glow discharge-treatment was applied to preparation of blood compatible materials. Plasticized polyvinylchloride (PVC) which is used for blood bags was treated in the presence of various gases or monomers. Wettability of PVC was modified by the treatment over a wide range. And leakage of plasticizer, di-(2-ethylhexyl)phthalate (DEHP), was prevented. When platelet concentrates were stored in the treated PVC bags, impairment of platelet functions was suppressed by the prevention of DEHP leakage. But platelet adhesion to the surfaces increased by the treatments. Aldehyde groups were grafted on polyethylene film (PE) by glow discharge-treatment in the presence of formaldehyde gas. Although the aldehyde-grafted PE (HCHO-PE) had higher reactivity with platelet than PE after albumin coating, it exhibited excellent antithrombogenicity after blood plasma coating. HCHO-PE adsorbed proteins with almost the same composition as blood plasma, although non-treated PE adsorbed proteins with higher fibinogen/albumin ratio. Segmented-polyurethane which is well known to exhibit good antithrombogenicity, also formed the adsorption layer having composition like that of blood plasma. These results suggest that protein layer adsorbed with blood plasma composition is hardly recognized by platelets. Glow discharge-treatment is a simple and effective method for surface modification of medical polymers.
Ishikawa, Y.; Sasakawa, S.
Study of short atmospheric pressure dc glow microdischarge in air
The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage--current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles.
Kudryavtsev, Anatoly; Bogdanov, Eugene; Chirtsov, Alexander; Emelin, Sergey
The Analysis of Main Dosimetric Glow Peaks in CaF2:Tm (TLD-300)
The thermoluminescence properties of CaF2:Tm (TLD-300) are examined in detail after ?-irradiation at room temperature. The glow curve of the sample shows two main dosimetric glow peaks: P3 (at ~150�C) and P5 (at ~250�C). The additive dose, variable heating rate, computer glow curve deconvolution, peak shape and three points methods are used to evaluate the trapping parameters, namely the order of kinetics (b), activation energy (E) and frequency factor (s) associated with the dosimetric thermoluminescent glow peaks (P3 and P5) of CaF2:Tm (TLD-300) after different dose levels with ?-irradiation.
Vural, E. Kafadar; Metin, Bedir; A. Necmeddin, Yaz?c?; T�lin, G�nal
Peculiarities of the glow-peak 5a of LiF:Mg,Ti
The glow-peak 5a of LiF:Mg,Ti is a glow-peak, with peak maximum temperature between those of glow-peaks 5 and 6. This glow-peak is not seen in the usual glow-curve, resulting after normal annealing at 400�C for 1 h and at 100�C for 2 h. However, its existence is confirmed first experimentally and then as the necessity to achieve a very good glow-curve fitting. In the present work it is found that the glow-peak 5a can be very well isolated from its neighbouring glow-peaks, after special thermal treatment between 140�C and 160�C. The isolation permits the study of its individual behaviour, which was found to have the following peculiarities. (i) This glow-peak is clearly seen only after thermal treatment between 140�C and 160�C. (ii) It appears with the same properties after both pre-irradiation and post-irradiation annealing in the above temperature region. (iii) Its activation energy was found to be above 3 eV and its frequency factor above 10 30 s -1. These values are extremely high and outside the physically accepted limits.
Kitis, G.; Otto, T.
Models of Abnormal Scarring
Keloids and hypertrophic scars are thick, raised dermal scars, caused by derailing of the normal scarring process. Extensive research on such abnormal scarring has been done; however, these being refractory disorders specific to humans, it has been difficult to establish a universal animal model. A wide variety of animal models have been used. These include the athymic mouse, rats, rabbits, and pigs. Although these models have provided valuable insight into abnormal scarring, there is currently still no ideal model. This paper reviews the models that have been developed.
Seo, Bommie F.; Lee, Jun Yong; Jung, Sung-No
Influence of driving frequency on discharge modes in a dielectric-barrier discharge with multiple current pulses
A one-dimensional self-consistent fluid model was employed to investigate the effect of the driving frequency on the discharge modes in atmospheric-pressure argon discharge with multiple current pulses. The discharge mode was discussed in detail not only at current peaks but also between two adjacent peaks. The simulation results show that different transitions between the Townsend and glow modes during the discharge take place with the driving frequency increased. A complicated transition from the Townsend mode, through glow, Townsend, and glow, and finally back to the Townsend one is found in the discharge with the driving frequency of 8 kHz. There is a tendency of transition from the Townsend to glow mode for the discharge both at the current peaks and troughs with the increasing frequency. The discharge in the half period can all along operate in the glow mode with the driving frequency high enough. This is resulted from the preservation of more electrons in the gas gap and acquisition of more electron energy from the swiftly varying electric field with the increase in driving frequency. Comparison of the spatial and temporal evolutions of the electron density at different driving frequencies indicates that the increment of the driving frequency allows the plasma chemistry to be enhanced. This electrical characteristic is important for the applications, such as surface treatment and biomedical sterilization.
Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang
Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China)] [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China); Duan, Yixiang [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China) [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119 (China); Research Center of Analytical Instrumentation, Sichuan University, Chengdu 610064 (China)
Abnormality, rationality, and sanity.
A growing body of studies suggests that neurological and mental abnormalities foster conformity to norms of rationality that are widely endorsed in economics and psychology, whereas normality stands in the way of rationality thus defined. Here, we outline the main findings of these studies, discuss their implications for experimental design, and consider how 'sane' some benchmarks of rationality really are. PMID:24055170
Hertwig, Ralph; Volz, Kirsten G
A Study of Glow Discharge Polymerization as a Means of Preparing Composite Reverse Osmosis Membranes with Ultrathin Skin.
Polymer thin film formation by glow discharge in organic vapors (glow discharge polymerization, or plasma polymerization (PP) from a monomer (3.g., styrene) produces polymers which are considerably different from those formed from the same monomer by conv...
H. Yasuda
Reproducing continuous radio blackout using glow discharge plasma
A novel plasma generator is described that offers large-scale, continuous, non-magnetized plasma with a 30-cm-diameter hollow structure, which provides a path for an electromagnetic wave. The plasma is excited by a low-pressure glow discharge, with varying electron densities ranging from 10{sup 9} to 2.5 � 10{sup 11} cm{sup ?3}. An electromagnetic wave propagation experiment reproduced a continuous radio blackout in UHF-, L-, and S-bands. The results are consistent with theoretical expectations. The proposed method is suitable in simulating a plasma sheath, and in researching communications, navigation, electromagnetic mitigations, and antenna compensation in plasma sheaths.
Xie, Kai; Li, Xiaoping; Liu, Donglin; Shao, Mingxu [School of Aerospace Science and Technology, Xidian University, Xi'an 710071 (China)] [School of Aerospace Science and Technology, Xidian University, Xi'an 710071 (China); Zhang, Hanlu [School of Communication and Information Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121 (China)] [School of Communication and Information Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121 (China)
Radial Distributions of Dusty Plasma Parameters in a Glow Discharge
A self-consistent model for radial distributions of dusty plasma parameters in a DC glow discharge based on the non-local Boltzmann equation for EEDF, the drift-diffusion equation for ions, and the Poisson equation for self-consistent electric field is presented. The results show that for the case of high dust particles density when the recombination of electrons and ions exceeds the ionization near the tube axis, radial electron and ion fluxes change their direction toward the center of the tube, and the radial electric field is reversed.
Fedoseev, A. V. [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Sukhinin, G. I. [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova Str., 2, Novosibirsk, 630090 (Russian Federation)
LANL Transfers Glowing Bio Technology to Sandia Biotech
Partnering with Los Alamos National Laboratory, an Albuquerque-based company is seeking to transform the way protein and peptide analysis is conducted around the world. Sandia Biotech is using a biological technology licensed from Los Alamos called split green fluorescent protein (sGFP), as a detecting and tracking tool for the protein and peptide industry, valuable in the fields of Alzheimer's research, drug development and other biotechnology fields using protein folding to understand protein expression and mechanisms of action. http://www.lanl.gov/news/stories/glowing-future-for-los-alamos-and-sandia-b iotech-partnership.html
Diode laser excited optogalvanic spectroscopy of glow discharges
The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining isotopic ratios of {sup 235}U/({sup 235}U + {sup 238}U) in the above samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of he measurement is discussed. Application of the GD-OGS to other f-transition elements is also described.
Barshick, C.M.; Shaw, R.W.; Post-Zwicker, A., Young, J.P.; Ramsey, J.M.
Comparative Spectroscopic Temperature Measurements In Hydrogen Hollow Cathode Glow Discharge
We report results of optical emission spectroscopy measurements of rotational Trot and translational temperature Ttr of hydrogen molecules. The light source was hollow cathode glow discharge with titanium cathode operated in hydrogen at low pressure. The rotational temperature of excited electronic states of H2 was determined either from relative line intensities of the R branch of the GK ? B band or from the Q branch of the Fulcher-a diagonal band. The population of excited energy levels, determined from relative line intensities, was used to derive ro-vibronic temperature of the ground state of hydrogen molecule.
Majstorovic, G. Lj.; �i�ovic, N. M.; Konjevic, N.
Persistence of phosphor glow in microchannel plate image intensifiers
Image intensifier tubes using microchannel plate amplification stages and phosphor output stages are being increasingly used in various detection applications. In this paper, measurements of the decay times of what are attributed to be the P20 phosphors in various image intensifiers are reported. It is found that the long tail on the decay curve of the phosphor following illumination can be a limitation for certain observations. In addition, the background level of phosphor glow (which is seen by the subsequent detection system as a light signal) continues to build with continuing illumination.
Torr, M. R.
A novel plasma generator is described that offers large-scale, continuous, non-magnetized plasma with a 30-cm-diameter hollow structure, which provides a path for an electromagnetic wave. The plasma is excited by a low-pressure glow discharge, with varying electron densities ranging from 109 to 2.5 � 1011 cm-3. An electromagnetic wave propagation experiment reproduced a continuous radio blackout in UHF-, L-, and S-bands. The results are consistent with theoretical expectations. The proposed method is suitable in simulating a plasma sheath, and in researching communications, navigation, electromagnetic mitigations, and antenna compensation in plasma sheaths.
Xie, Kai; Li, Xiaoping; Liu, Donglin; Shao, Mingxu; Zhang, Hanlu
Enhancement of loop antenna reception using glow discharge plasma core
Experimental results on the behavior of air glow dc discharge column radio frequency antenna are presented. The effect of the discharge conditions on the loop antenna gain at five radio frequencies of 9.3, 10.0, 13.6, 16.5, and 19.1 MHz are studied. Increases in the loop antenna gain of up to 5 dB are observed. The increase in gain is observed to rise with increased plasma density at the onset of the discharge approaching a saturation limit as the plasma density is increased further.
Azooz, A. A.; Al-Jawaady, Y. A.; Ali, Z. T.
Rorick, Kevin
Glow experiment documentation of OMS/RCS pods and vertical stabilizer
Glow experiment documentation of orbital maneuvering system (OMS) reaction control system (RCS) pods and vertical stabilizer shows chemoluminescent effect resulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. Image intensifier on NIKON 35mm camera used to record glow on vertical tail and OMS pods.
Glow experiment documentation of OMS/RCS pod and vertical stabilizer
Glow experiment documentation of one of the orbital maneuvering system (OMS) reaction control system (RCS) pods and a portion of the vertical stabilizer shows chemoluminescent effectresulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. The Image Intensifier on NIKON 35mm camera was used to record the glow.
Glow experiment documentation of orbital maneuvering system (OMS) reaction control system (RCS) pods and vertical stabilizer shows chemo-luminescent effect resulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. Image intensifier on NIKON 35mm camera was used to record glow on vertical tail and OMS pods.
Peculiarities of metal surface glow under YAG:Nd laser pulses
The paper deals with the study of laser-induced rising of defects onto the surface and W surface destruction. The non- thermal glow from the back, relative to the acting laser pulses, side of the sample was registered. The glow may be caused by defects rising onto the surface under considerable thermo elastic stresses in the laser effect ares.
Banishev, Alexander F.; Panchenko, Vladislav Y.; Shishkov, Alexei V.
Cerenkov glow viewing technique for spent fuel verification current status and future prospects
The Cerenkov Glow viewing technique is a simple, non-intrusive method of spent fuel verification, widely used by IAEA inspectors. In the course of 1986, Cerenkov Viewing Devices (CVDs) were used in about 179 inspections in 98 MBAs (Material Balance Areas). The two main limitations of the technique are: 1. The Cerenkov glow may be too weak to be visible in
Formation of amino acids from ammonium bicarbonate or ammonium formate by contact glow-discharge electrolysis
In this paper, we describe the formation of amino acids from ammonium bicarbonate or ammonium formate in ammoniac~tl aqueous solution by contact glow-discharge electrolysis (CGDE). CGDE is a chemical change due to the glow discharge between a solution containing various ions or substrates and the elctrode in contact with the solution [2]. Several studies have been reported recently on the
K. Harada; S. Suzuki
A survey of streamer and diffuse glow dynamics observed in sprites using telescopic imagery
While the fine structure in sprites can assume a wide variety of shapes, sizes, and timescales, certain patterns such as upward branching, downward branching, beading, columns, bidirectional streamers, and propagating large-scale diffuse glow regions are repeatedly observed. Example cases of these streamer and diffuse glow dynamics observed in sprites are presented using video data obtained by a telescopic imaging system
Elizabeth A. Gerken; Umran S. Inan
Atmospheric Pressure Transient Micro Glow Discharge Driven by Burst Pulse Generator with Nonlinear Transmission Line
Summary form only given. One of the features of microplasmas is that atmospheric pressure glow discharges (APGDs), which attract growing attention in a variety of plasma applications, are easily obtained. We reported the dc-powered microplasma in air between nozzle and mesh electrodes with miniature gas flow. Although the stable glow discharge was generated, the input power was the order of
S. Ibuka; F. Furuya; K. Ogura; K. Yasuoka; S. Ishii
Assessing the Warm Glow Effect in Contingent Valuations for Public Libraries
This article aims to present evidence of the warm glow effect in a public library setting. More specifically, it tests whether individual respondents with different values for the warm glow component report different values for their willingness to pay (WTP). The data come from a contingent valuation survey conducted on randomly selected citizens�
Lee, Soon-Jae; Chung, Hye-Kyung; Jung, Eun-Joo
Liver abnormalities in pregnancy.
Abnormalities of liver function (notably rise in alkaline phosphatase and fall in serum albumin) are common in normal pregnancy, whereas rise in serum bilirubin and aminotransferase suggest either exacerbation of underlying pre-existing liver disease, liver disease related to pregnancy or liver disease unrelated to pregnancy. Pregnant women appear to have a worse outcome when infected with Hepatitis E virus. Liver diseases associated with pregnancy include abnormalities associated hyperemesis gravidarum, acute fatty liver disease, pre-eclampsia, cholestasis of pregnancy and HELLP syndrome. Prompt investigation and diagnosis is important in ensuring a successful maternal and foetal outcome. In general, prompt delivery is the treatment of choice for acute fatty liver, pre-eclampsia and HELLP syndrome and ursodeoxycholic acid is used for cholestasis of pregnancy although it is not licenced for this indication. PMID:24090943
Than, Nwe Ni; Neuberger, James
Production of atmospheric-pressure glow discharge in nitrogen using needle-array electrode
An atmospheric pressure glow discharge was generated using a needle-array electrode in nitrogen, and the voltage-current characteristics of the glow discharge were obtained in a range from 1 mA to 60 A. A pulsed high voltage with short rise time under 10 ns was employed to generate streamer discharges simultaneously at all needle tips. The large number of streamer discharges prevented the glow-to-arc transition caused by inhomogeneous thermalization. Semiconductor opening switch diodes were employed as an opening switch to shorten the rise time. The glow voltage was almost constant until the discharge current became 0.3 A, whereas the voltage increased with the current higher than 0.3 A. Electron density and temperature in a positive column of the glow discharge at 60 A were obtained to 1.4x10{sup 12} cm{sup -3} and 1.3 eV from calculation based on nitrogen swarm data.
Takaki, K.; Hosokawa, M.; Sasaki, T.; Mukaigawa, S.; Fujiwara, T. [Department of Electrical and Electronic Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan)
Abnormal pressures as hydrodynamic phenomena
So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author
Neuzil, C. E.
Dust particle radial confinement in a dc glow discharge.
A self-consistent nonlocal model of the positive column of a dc glow discharge with dust particles is presented. Radial distributions of plasma parameters and the dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of dust particle density in a dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the dust particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and dust particle parameters are obtained. It is shown that the influence of the dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the dust cloud substantially depend on the plasma parameters outside the dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the dust cloud. PMID:23410440
Sukhinin, G I; Fedoseev, A V; Antipov, S N; Petrov, O F; Fortov, V E
Ozone generation using atmospheric pressure glow discharge in air
This paper presents results from a study into the generation of ozone by a stable atmospheric glow discharge, using dry air as the feeding gas for ozone generation. The power supply is 50 Hz ac, with the use of a perforated aluminium sheet for the electrodes and soda lime glass as a dielectric layer in a parallel-plate configuration, stabilizing the generation process and enabling ozone to be produced. The stable glow discharge spreads uniformly at a gas breakdown voltage below 4.8 kV and requires only 330 mW discharge power, with a limitation of 3 mm on the maximum gap spacing for the dry air. With the technique providing a high collision rate between the electrons and gas molecules during the discharge process, a high ozone yield is obtained. An analysis of the effect on the production rate of parameters such as the input voltage, gas flow rate and reaction chamber dimensions resulted in a highest efficiency of production of almost 350 g kWh-1 and confirms its potential as an important ozone generation technology.
Buntat, Z.; Smith, I. R.; Razali, N. A. M.
Dust particle radial confinement in a dc glow discharge
A self-consistent nonlocal model of the positive column of a dc glow discharge with dust particles is presented. Radial distributions of plasma parameters and the dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of dust particle density in a dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the dust particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and dust particle parameters are obtained. It is shown that the influence of the dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the dust cloud substantially depend on the plasma parameters outside the dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the dust cloud.
Sukhinin, G. I.; Fedoseev, A. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E.
Interaction Between Acoustic Shock Wave and Glow Discharge
We are studying the interaction between propagating acoustic planar shock wave and weakly ionized gas in a high-pressure dc glow discharge. This interaction appears to be polarity-dependent and substantially different in the positive column than in the cathode region(P. Bletzinger and B. N. Ganguly, Phys. Lett. A 258) 342 (1999).^,(S. Popovi?) and L. Vu\\vskovi?, Physics of Plasmas 6 1448 (1999).. Several agents emerging from the acoustic shock wave modify its precursor zone with respect to free stream conditions. These are fluxes of charged particles accelerated or reflected from the potential barrier in double electric layer, radiation from relaxation zone, and ion-acoustic waves. Our study attempts to provide a detailed insight into the processes initiated by these agents and to give the character and the extent of the modification. We will present a quantitative discussion of ion flux penetration in the free stream region, changes in ion composition, the ionization-recombination process, and transfer of radiation from shock layer and relaxation zone to precursor zone. The conditions in precursor region thus prepared become the initial conditions for the processes in the relaxation region. Using this approach we analyze interaction of shock wave with the negative glow, and with the positive column in the co-directional geometry.
Popovi?, S.; Vu�kovi?, L.
Demonstration of Separation Control Using Glow-Discharge Plasma Actuators
Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modem low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2%) and high (2.5%) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control.
Hultgren, Lennart S.; Ashpis, David E.
Demonstration of Separation Delay With Glow-Discharge Plasma Actuators
Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50; 000 to 300,000, covering cruise to takeoff conditions. Low (0.2%) and high (2.5%) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control.
Demonstration of Separation Delay with Glow-Discharge Plasma Actuators
Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2 percent) and high (2.5 percent) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control.
On electron bunching and stratification of glow discharges
Plasma stratification and excitation of ionization waves is one of the fundamental problems in gas discharge physics. Significant progress in this field is associated with the name of Lev Tsendin. He advocated the need for the kinetic approach to this problem contrary to the traditional hydrodynamic approach, introduced the idea of electron bunching in spatially periodic electric fields, and developed a theory of kinetic resonances for analysis of moving striations in rare gases. The present paper shows how Tsendin's ideas have been further developed and applied for understanding the nature of the well-known S-, P-, and R-striations observed in glow discharges of inert gases at low pressures and currents. We review numerical solutions of a Fokker-Planck kinetic equation in spatially periodic electric fields under the effects of elastic and inelastic collisions of electrons with atoms. We illustrate the formation of kinetic resonances at specific field periods for different shapes of injected Electron Distribution Functions (EDF). Computer simulations illustrate how self-organization of the EDFs occurs under nonlocal conditions and how Gaussian-like peaks moving along resonance trajectories are formed in a certain range of discharge conditions. The calculated EDFs agree well with the experimentally measured EDFs for the S, P, and R striations in noble gases. We discuss how kinetic resonances affect dispersion characteristics of moving striations and mention some non-linear effects associated with glow discharge stratification. We propose further studies of stratification phenomena combining physical kinetics and non-linear physics.
Golubovskii, Yuri B. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation)] [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Kolobov, Vladimir I. [CFD Research Corporation, Huntsville, Alabama 35805 (United States)] [CFD Research Corporation, Huntsville, Alabama 35805 (United States); Nekuchaev, Vladimir O. [Ukhta State Technical University, Ukhta 169300 (Russian Federation)] [Ukhta State Technical University, Ukhta 169300 (Russian Federation)
Verification of the dual integral glow analysis dosimetry system
The Dual Integral Glow Analysis (DINGA) method is a unique approach to the determination of the low-LET dose deposited within a thermoluminescent personnel dosimeter. DINGA creates its estimate of the dose deposited by utilizing the integrals of a sub-section of the glow curves obtained from opposite sides of one or more thermoluminescent detectors (TLDs) and knowledge of the TLDs thermophysical parameters. The performance of DINGA is evaluated with computational simulations for a variety of heating methods and error tolerance is also examined by introducing errors into the inputs the DINGA code. It has been found that DINGA's dose estimates are off approximately, in the worst case, the same percentage as the input parameter was varied. Experimental measurements are performed using a hot-gas heating method for large personnel doses and a laser heating method for smaller personnel doses with LiF: Mg, Ti (TLD-100) dosimeters. The dosimeters are exposed to select radiation fields generated by either certified sources or fields characterized by certified equipment. The DINGA dosimetry system is found to correctly report shallow and deep dose well within the limits required for certification by the National Voluntary Accreditation Program. The worst performance quotient is 0.19, well below the strictest limit of 0.30.
Wagner, Eric Christopher
Roentgenologic Abnormalities in Down's Syndrome.
Roentgenograms of 28 patients with Down's syndrome were reviewed with emphasis on all previously reported abnormalities and any possible additional ones. Most of the abnormalities occurred with the same frequency as previously reported, but some less freq...
T. Higuchi W. J. Russell M. Komatsuda S. Neriishi
Epilepsy and chromosomal abnormalities
Background��Many chromosomal abnormalities are associated with Central Nervous System (CNS) malformations and other neurological alterations,\\u000a among which seizures and epilepsy. Some of these show a peculiar epileptic and EEG pattern. We describe some epileptic syndromes\\u000a frequently reported in chromosomal disorders.\\u000a \\u000a \\u000a \\u000a \\u000a Methods��Detailed clinical assessment, electrophysiological studies, survey of the literature.\\u000a \\u000a \\u000a \\u000a Results��In some of these congenital syndromes the clinical presentation and EEG
Giovanni Sorge; Anna Sorge
Proposal for a workshop in the physics and application of hollow electrode glow switches
The purpose of the 1989 NATO ARW was to develop applications for and an improved understanding of the physics for high current emission and conduction observed in hollow cathode-hollow anode switches including the pseudospark and back-lighted thyratron (BLT). New applications include highly emissive cathodes for microwave devices, accelerators and free electron lasers, high power tubes, electron and ion-beams, microlithography, accelerators, and other plasma devices. Recent research has produced this new generation of gas-phase plasma switches that are characterized by very high current emission and conduction while operating in a glow mode. The cathode properties are especially remarkable - about 2 orders of magnitude larger emission than existing thermionic cathodes. Part of the meeting was devoted to understanding these properties and exploiting applications of this cathode. These results disserve study in order to understand the underlying physical mechanisms and to develop ideas and insight into future applications, and foster coherent research in this area. This meeting was also motivated by the fact that there are many new applications of these devices under consideration. These include new types of ion and electron beams for microelectronic technology, accelerators, other plasma loaded devices, plasma lenses for high energy physics, plasma accelerators, applications requiring very high cathode emission such as cathodes for pulsed accelerators, and microwave sources.
Gundersen, Martin
Composition dependence of glow peak temperature in KCl1-xBrx doped with divalent cations
Thermoluminescence measurements of bgr-irradiated Eu2+- and Ca2+-doped KCl1-xKBrx solid solutions excited at room temperature have been carried out to identify the effect of composition on the glow peaks. A typical glow peak has been distinguished for each composition. A linear dependence of its temperature on the composition x has been found. These results indicate that for divalent impurity-doped alkali halide solid solutions these glow peak temperatures are mostly dependent on the lattice constant of the host than on the size of the anion or impurity cation.
P�rez-Salas, R.; Aceves, R.; Rodr�guez-Mijangos, R.; Riveros, H. G.; Duarte, C.
Plasma stability control using dielectric barriers in radio-frequency atmospheric pressure glow discharges
It is widely accepted that electrode insulation is unnecessary for generating radio-frequency (rf) atmospheric pressure glow discharges (APGDs). It is also known that rf APGDs with large discharge current are susceptible to the glow-to-arc transition. In this letter, a computational study is presented to demonstrate that dielectric barriers provide an effective control over unlimited current growth and allow rf APGDs to be operated at very high current densities with little danger of the glow-to-arc transition. Characteristics of electrode sheaths are used to show that the stability control is achieved by forcing the plasma-containing electrode unit to acquire positive differential conductivity.
Shi, J. J.; Liu, D. W.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)
Generation of Larger Volume Glow Discharge in Microhollow Cathode Sustained Discharge with Split Third Electrodes
Enlarged-volume diffuse glow discharge at high pressures is produced by microhollow cathode sustained discharge in a split third electrode configuration. The largest span-wise expansion of the sustained glow discharge is 12 mm at 700 Torr with seven positively biased split electrodes, while with a conventional single planar third electrode the expansion is only about 2 mm. Current--voltage characteristics reveal that the whole trilayer system behaves like a normal glow discharge at third electrode currents higher than the microhollow cathode discharge current. The current distribution over the entire electrodes exhibits moderately uniform expansion in the discharge across the electrode span.
Rahman, Mohammad Towhidur; Shin, Jichul
Efficient algorithm for simulating a multidimensional glow discharge
A normal glow discharge in nitrogen between two infinite plane-parallel electrodes is simulated numerically in three dimensions in the drift-diffusion model. An algorithm is proposed that is based on solving the model equations by a hybrid of the sweep and relaxation methods and that combines a satisfactorily fast rate of convergence with the efficiency of individual iterations. The algorithm developed was used to carry out a three-dimensional simulation of a discharge in nitrogen at the pressures p = 5 and 1 Torr, the source voltage and ballast resistance being 2 kV and 300 k{Omega}, respectively. It was found that, at the pressure p = 1 Torr, the current density and charged particle densities change to a torioidal distribution in the anode region.
Petrusev, A. S.; Surzhikov, S. T. [Russian Academy of Sciences, Institute for Problems in Mechanics (Russian Federation)
TSL and fractional glow study of Ge-doped ?-quartz
Crystalline ?-quartz doped with 0.1wt% and 0.9wt% germanium was studied using TSL and FGT equipment. Sample was chosen because previously it is known that Ge in quartz is efficient trap for electrons, therefore it could be used for detection of hypothetic self-trapped hole in ?-quartz. However previous investigations of ODMR and TSL shows that in ?-quartz the hole is still mobile and trapping occurs only on defect states. The activation energies for both TSL peaks are found by fractional glow and Hoogenstraaten method. The TSL distribution changes depending on Ge concentration and also on irradiation type. The TSL peaks below 70K in quartz doped with Ge could belong to hole trapped on Ge.
Zolatarjovs, A.; Trukhin, A. N.; Smits, K.; Millers, D.
A Sample Glows as it Melts within TEMPUS
This video was taken from the first flight of the TEMPUS electromagnetic levitation furnace on the International Microgravity Laboratory-2 (STS-65, July 8-23, 1994). This view is from the furnace's upper camera and shows a sample glowing as it melts. TEMPUS (stands for Tiegelfreies Elektromagnetisches Prozessiere unter Schwerelosigkeit (containerless electromagnetic processing under weightlessness). It was developed by the German Space Agency (DARA) for flight aboard Spacelab. The DARA project scientist was Igon Egry. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). DARA and NASA are exploring the possibility of flying an advanced version of TEMPUS on the International Space Station. (200KB JPEG, 1267 x 1931 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300195.html.
Fluorination of polymer surfaces has technological applications in various fields such as microelectronics, biomaterials, textile, packing, etc. In this study PMMA surfaces were fluorinated using DC glow discharge plasma. Tetrafluoroethane was used as the fluorinating agent. On the fluorinated PMMA surface, static water contact angle, surface energy, optical transmittance (UV-vis), XPS and AFM analyses were carried out. After the fluorination PMMA surface becomes hydrophobic with water contact angle of 107� without losing optical transparency. Surface energy of fluorine plasma-treated PMMA decreased from 35 mJ/cm 2 to 21.2 mJ/cm 2. RMS roughness of the fluorinated surface was 4.01 nm and XPS studies revealed the formation of C-CF x and CF 3 groups on the PMMA surface.
Guruvenket, S.; Iyer, Ganjigunte R. S.; Shestakova, Larisa; Morgen, Per; Larsen, N. B.; Mohan Rao, G.
Regular and stochastic regimes in glow-discharge tubes
The behavior of the time-dependent portion of the current i(t) as a function of the total mean current flowing through a glow-discharge tube filled with noble gases (He, Xe, Kr) is analyzed. The experiments were carried out in dc-operated low-pressure spectroscopic lamps immersed in an electrically insulated heath bath. A dc regulated high- voltage supply was used to sustain the discharge. The data points, i(t) sampled at regular time intervals, were used to reconstruct the dynamics of the system. Evidence was found of intermixed irregular and regular regimes. The discharge in the He-filled tube exhibits a sequence of bifurcations between regular states as the current was increased reaching at the higher currents an irregular (stochastic or chaotic) regime. In Xe and Kr only the stochastic regime was observed with no trace of the regular ones.
Salas-Brito, A. L.; Robledo-Martinez, Arturo; Vargas, C. A.
Tantalum etching in fluorocarbon/oxygen rf glow discharges
Etch rates of tantalum in tetrafluoromethane-oxygen and hexafluoroethane-oxygen rf glow discharges were measured {ital in} {ital situ} as functions of pressure, reactor residence time, temperature, and applied plasma power. A dramatic increase in the etch rate was observed as the pressure increased. In addition, two distinct temperature regimes occurred in Arrhenius plots. Such data suggest strong effects due to heat of reaction in the Ta/CF{sub 4}-O{sub 2} etch system. The observed etch-rate pressure dependence can be explained by assuming first-order kinetics for the reaction of fluorine atoms with tantalum. Evidence for etch-rate quenching at high pressures due to an increase in the deposition of an inhibiting fluorocarbon surface layer is presented.
Martz, J.C.; Hess, D.W. (Department of Chemical Engineering, 201 Gilman Hall, University of California, Berkeley, California 94720 (USA)); Anderson, W.E. (Materials Science, MS E549, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA) Technology Division, MS E549, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA))
Eye movement abnormalities.
Generation and control of eye movements requires the participation of the cortex, basal ganglia, cerebellum and brainstem. The signals of this complex neural network finally converge on the ocular motoneurons of the brainstem. Infarct or hemorrhage at any level of the oculomotor system (though more frequent in the brain-stem) may give rise to a broad spectrum of eye movement abnormalities (EMAs). Consequently, neurologists and particularly stroke neurologists are routinely confronted with EMAs, some of which may be overlooked in the acute stroke setting and others that, when recognized, may have a high localizing value. The most complex EMAs are due to midbrain stroke. Horizontal gaze disorders, some of them manifesting unusual patterns, may occur in pontine stroke. Distinct varieties of nystagmus occur in cerebellar and medullary stroke. This review summarizes the most representative EMAs from the supratentorial level to the brainstem. PMID:22377853
Moncayo, Jorge; Bogousslavsky, Julien
Characterization of the glow-peak fading properties of six common thermoluminescent materials.
The pre-irradiation and post-irradiation fading rates of the thermoluminescent glow peaks of six commonly used thermoluminescent dosimeters under controlled environmental conditions over approximately 30 d are examined. Glow peaks were fit to the first-order kinetics model using a computerized glow curve deconvolution program. Dosimeters studied were LiF:Mg,Ti, CaF(2):Dy, CaF(2):Tm, CaF(2):Mn, LiF:Mg,Cu,P, and CaSO(4):Dy. LiF:Mg,Ti and LiF:Mg,Cu,P experienced significant pre-irradiation fading. All types except CaF(2):Mn experienced post-irradiation fading. Ratios of glow-peak areas were fit to exponential decay functions when possible. PMID:20554212
Harvey, John A; Haverland, Nathan P; Kearfott, Kimberlee J
Potential industrial applications of the one atmosphere uniform glow discharge plasma operating in ambient air
The majority of industrial plasma processing is conducted with glow discharges at pressures below 10 Torr. This tends to limit such applications to high value workpieces, as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharges would play a much larger industrial role if they could be generated at 1 atm and in air. The one atmosphere uniform glow discharge plasma (OAUGDP�) has these capabilities. As a normal glow discharge, the OAUGDP� can operate with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum. This paper will survey exploratory investigations at the University of Tennessee's Plasma Sciences Laboratory of seven potential industrial applications of the OAUGDP� which can be conducted at 1 atm and at room temperature with air as the working gas.
Roth, J. Reece
The majority of industrial plasma processing is conducted with glow discharges at pressures below 10 Torr. This tends to limit such applications to high value workpieces, as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharges would play a much larger industrial role if they could be generated at 1 atm and in air. The one atmosphere uniform glow discharge plasma (OAUGDP registered ) has these capabilities. As a normal glow discharge, the OAUGDP registered can operate with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum. This paper will survey exploratory investigations at the University of Tennessee's Plasma Sciences Laboratory of seven potential industrial applications of the OAUGDP registered which can be conducted at 1 atm and at room temperature with air as the working gas.
Roth, J. Reece [Plasma Sciences Laboratory, Department of Electrical and Computer Engineering, University of Tennessee, Knoxville, Tennessee 37996-2100 (United States)
Direct Gas Injection with Glow Plug Ignition. Annual Report August 1987-July 1988,
Tests on a Caterpillar 3400 Series single cylinder laboratory demonstration engine indicate that natural gas engine power and thermal efficiency comparable to a diesel are achievable by incorporating direct gas injection with glow plug ignition assist (DI...
B. G. Richards
A simple method to record thermoluminescence glow-curves between 77 and 300 K
In this work a simple method is suggested for recording thermoluminescence in the temperature region between 77 K (Liquid nitrogen temperature) and 300 K (environmental temperature). The method is based on an exponential heating scheme instead of linear heating of the sample. The experimental setup required is much simpler than that of conventional thermoluminescence readers. In the present work it was possible to measure thermoluminescence glow-curves of materials which are widely used in dosimetry, using a very simple setup. Specifically, we measured the thermoluminescence glow-curves of LiF:Mg,Ti, Al 2O 3:C and of different quartz samples, unfired and fired at very high temperatures. Furthermore, a glow-curve de-convolution analysis of the TL glow-curves of LiF:Mg,Ti and Al 2O 3:C is performed using newly developed analytical expressions describing a single TL peak obtained under an exponential heating scheme.
Kitis, G.
Kinetic parameters, bleaching and radiation response of thermoluminescence glow peaks separated by deconvolution on Korean calcite
Calcite has been of particular interest in studies of thermoluminescence (TL) because of its geological and archeological importance. Although extensive research on the TL glow curves of calcite has been conducted, most previous works have been based on the TL intensity integrated over a particular temperature range on the glow curve, without any separation of peaks. In this paper, the physical characteristics of the overlapping peaks in the TL glow curves of a calcite sample are investigated. These properties can provide useful information for determining the radiation dose absorbed to the sample in radiation dosimetry and luminescence dating research. The Tm-Tstop method is employed to identify the number of hidden glow peaks, and the kinetic parameters of each separated glow peak, including the thermal activation energy, kinetic order, and frequency factor, are evaluated using a computerized glow curve deconvolution (CGCD) method. The Tm-Tstop method indicates that the glow curve of calcite is the superposition of at least four components (P1 - P4) in the temperature range between room temperature and 450 �C. A bleaching experiment for two separated glow peaks (P3 and P4) using a solar simulator revealed that the bleaching rates of peak P3 show two exponential decays, and after bleaching, the TL intensity of peak P3 is reduced to approximately 4% of the initial value. In contrast, peak P4 is bleached exponentially to approximately 30% of the initial TL intensity and thereafter shows no detectable change in intensity. In addition, in a study of the radiation dose response of the two peaks, both peaks have a similar pattern, exhibiting a linear increment up to the maximum dose investigated, 520 Gy.
Kim, Ki-Bum; Hong, Duk-Geun
Development of a Plasma Source Using Atmospheric-Pressure Glow Discharge in Contact with Solution
A novel plasma source of atmospheric-pressure glow (APG) discharge in contact with solution is developed. Liquid paraffin consisting of hydrocarbons is used as solution for the purpose of the formation of carbon nanotubes at the gas-liquid interface, i.e., the boundary between glow discharge (gas-phase) and solution (liquid-phase) layers. We have succeeded in generating a stable APG discharge plasma in contact with liquid paraffin by using a capacitively coupled plasma method with mesh electrode.
Hirai, Kazuhiko; Okada, Takeru; Kaneko, Toshiro; Hatakeyama, Rikizo; Yoshiki, Hiroyuki
Two-dimensional, self-consistent, three-moment simulation of RF glow discharge
A two-dimensional self-consistent nonequilibrium fluid model is used to simulate radio frequency (RF) glow discharges to evaluate the quantitative effects of the radial and axial flow dynamics inside a cylindrically symmetric parallel-plate geometry. This model is based on the three moments of the Boltzmann equation and on Poisson's equation. Radial\\/axial flow dynamics of plasma in low-pressure parallel plate RF glow
Fongray Frank Young; ChwanHwa J. Wu
Two-point method for kinetic analysis of a thermoluminescence glow peak
We present a method for the estimation of defect (trap) physical parameters from thermoluminescence (TL) glow peaks. In this method, the order of kinetics b is determined using two values of TL intensity each of which corresponds to the same temperature (T-1) on two separate glow peaks of a phosphor. The two glow peaks are obtained from two aliquots of the phosphor irradiated to same dose but read out at different heating rates. The proposed method requires a minimum of only two data points in contrast to standard peak shape (PS) methods that require three points corresponding to three different temperatures on the same glow peak. Once the order of kinetics b is determined, the activation energy E is calculated by taking a second point (T-2) on any one of the two glow peaks. The values of b and E thus obtained are used to evaluate the frequency factor S'' and the number of trapped electrons before the heating begins n(o). The validity of the method was checked using two numerically generated glow peaks. For the two cases, the method reproduced the input values reasonably well. The method was also used to analyse two experimental glow peaks. The results obtained provide a reasonably good fit to the experimental data. The kinetic parameters calculated using the present technique are comparable to those calculated using PS and initial rise methods. Initial guesses can easily be obtained for E and S'' using the present technique when a glow curve is to be deconvoluted with a model consisting of many unknown parameters with E and S'' inclusive.
Ogundare, F. O.; Chithambo, M. L.
Mechanisms controlling the transition from glow silent discharge to streamer discharge in nitrogen
Low-energy dielectric-barrier controlled discharges in nitrogen are studied by undertaking electrical measurements to determine mechanisms controlling the transition from glow to streamer-like discharge. The highest and the lowest values of the frequency and the amplitude of power supply voltage leading to a glow discharge have been found dependent on the gas flow and the nature of the surface in contact
Nicolas Gherardi; Fran�oise Massines
DC atmospheric pressure glow microdischarges in the current range from microamps up to amperes
Electrical and spectroscopic results of comprehensive investigations of microdischarges in atmospheric pressure helium, argon, nitrogen and air at gaps less than 1 mm and over a large current range from microamperes up to amperes are presented. At distance shorter than 1 mm, electrodes influence the normal glow discharge structure and their electrical and optical parameters. Two oscillation discharge regimes were revealed in discharge current range comparable or less than the low-current limit of normal glow discharge.
Arkhipenko, V. I.; Kirillov, A. A.; Safronau, Y. A.; Simonchik, L. V.
41-D crew briefings on use of camera for tail glow experiment
Steve Mende briefs one of the 41-D mission specialists on the operation of a camera setup for tail glow observations (33844); Astronaut Steve A. Hawley, left is briefed by Mende on the 41-D tail glow experiment. Hawley is a mission specialist for the 41-D flight. They are examing the Nikon camera and other gear to be used in the experiment. The briefing was held in the mockup and integration lab (33845).
Comparative Study of Mg-Si Films Deposited by DC and RF Glow Discharge Sputtering
Mg-Si thin films were deposited at low substrate temperature by direct current (DC)- and radio frequency (RF)- glow discharge sputtering from targets composed of Mg and Si plates with area ratios of 25%:75% and 50%:50%. X-ray diffraction measurements clarified that films deposited by both DC- and RF- glow discharge sputtering from the target of Mg:Si =25%:75% showed the intermetallic compound
SERIKAWA Tadashi; KAWABATA Kenshi; KONDOH Katuyoshi
Discharge transitions between glow-like and filamentary in a xenon/chlorine-filled barrier discharge lamp
An asymmetric electric voltage pulse source (2-20 kHz, Vp-p: 0-20 kV) was applied to stimulate excimer radiation by a dielectric barrier discharge in a binary gas mixture of chlorine (10.8 Torr)/xenon at high pressure (~460 Torr). When the source frequency increases continuously from 2.0 to 12.0 kHz or in reverse under a fixed output voltage of Vp-p (13.8 kV), it is observed that the discharge modes excited by this pulse source transmit between glow-like and filamentary, and we observe a mixed mode with filaments randomly distributed in the diffuse-like background in the narrow frequency range 7.0-8.0 kHz. It is argued that the reasons for the discharge transition could be the frequency and the time derivative of the voltage waveform of the power source. It is also observed that there is an obvious difference in the emission spectral profiles and the energy efficiency of excimer emission for the two discharge modes.
Xu, Jinzhou; Guo, Ying; Xia, Lei; Zhang, Jing
Evaluation of nail abnormalities.
Knowledge of the anatomy and function of the nail apparatus is essential when performing the physical examination. Inspection may reveal localized nail abnormalities that should be treated, or may provide clues to an underlying systemic disease that requires further workup. Excessive keratinaceous material under the nail bed in a distal and lateral distribution should prompt an evaluation for onychomycosis. Onychomycosis may be diagnosed through potassium hydroxide examination of scrapings. If potassium hydroxide testing is negative for the condition, a nail culture or nail plate biopsy should be performed. A proliferating, erythematous, disruptive mass in the nail bed should be carefully evaluated for underlying squamous cell carcinoma. Longitudinal melanonychia (vertical nail bands) must be differentiated from subungual melanomas, which account for 50 percent of melanomas in persons with dark skin. Dystrophic longitudinal ridges and subungual hematomas are local conditions caused by trauma. Edema and erythema of the proximal and lateral nail folds are hallmark features of acute and chronic paronychia. Clubbing may suggest an underlying disease such as cirrhosis, chronic obstructive pulmonary disease, or celiac sprue. Koilonychia (spoon nail) is commonly associated with iron deficiency anemia. Splinter hemorrhages may herald endocarditis, although other causes should be considered. Beau lines can mark the onset of a severe underlying illness, whereas Muehrcke lines are associated with hypoalbuminemia. A pincer nail deformity is inherited or acquired and can be associated with beta-blocker use, psoriasis, onychomycosis, tumors of the nail apparatus, systemic lupus erythematosus, Kawasaki disease, and malignancy. PMID:22534387
Tully, Amber S; Trayes, Kathryn P; Studdiford, James S
Chromosomal abnormalities and mental illness
Linkage studies of mental illness have provided suggestive evidence of susceptibility loci over many broad chromosomal regions. Pinpointing causative gene mutations by conventional linkage strategies alone is problematic. The breakpoints of chromosomal abnormalities occurring in patients with mental illness may be more direct pointers to the relevant gene locus. Publications that describe patients where chromosomal abnormalities co-exist with mental illness
D J MacIntyre; D H R Blackwood; D J Porteous; B S Pickard; W J Muir
Abnormal pressure in hydrocarbon environments
Abnormal pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on abnormal pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of abnormally high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of abnormal pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of abnormal pressure. The association of abnormal pressures with hydrocarbon accumulations is statistically significant. Within abnormally pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and gas occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). Abnormally pressured rocks are also commonly associated with unconventional gas accumulations where the pressuring phase is gas of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.
Law, B. E.; Spencer, C. W.
Use of Atmospheric Glow Discharge Plasma to Modify Spaceport Materials
Numerous materials used in spaceport operations require stringent evaluation before they can be utilized. It is critical for insulative polymeric materials that any surface charge be dissipated as rapidly as possible to avoid Electrostatic Discharges (ESD) that could present a danger. All materials must pass the Kennedy Space Center (KSC) standard electrostatic test [1]; however several materials that are considered favorable for Space Shuttle and International Space Station use have failed. Moreover, to minimize contamination of Mars spacecraft, spacecraft are assembled under cleanroom conditions and specific cleaning and sterilizing procedures are required for all materials. However, surface characteristics of these materials may allow microbes to survive by protecting them from sterilization and cleaning techniques. In this study, an Atmospheric Pressure Glow Discharge Plasma (APGD) [2] was used to modify the surface of several materials. This allowed the materials surface to be modified in terms of hydrophilicity, roughness, and conductivity without affecting the bulk properties. The objectives of this study were to alter the surface properties of polymers for improved electrostatic dissipation characteristics, and to determine whether the consequent surface modification on spaceport materials enhanced or diminished microbial survival.
Trigwell, S.; Shuerger, A. C.; Buhler, C. R.; Calle, C. J.
Thermal mechanism of prepeak formation in Pulsed Glow Discharge
A microsecond Pulsed Glow Discharge (?s PGD) in a Grimm-type source is characterized by the so-called ``prepeak,'' which is a spike in both electrical current and emission intensity at the leading edge of the discharge pulse. The prepeak is followed by synchronized vibrations of the current and the emission. To understand the nature of these phenomena, a microphone was inserted into the discharge chamber. Acoustical waves were detected and found to be in correlation with the measured vibrations. This points to a thermal mechanism for prepeak formation: the gas is heated in the leading edge of the discharge pulse and then expanded. To prove this suggestion, a Monte-Carlo based model was developed to simulate the evolution of Ar concentration, temperature, and flow in time and space. Potentially, the model could be used for gas simulations in a wide range of different applications. Here, the model is incorporated into an existing but modified model of the ?s PGD in a Grimm-type plasma excitation source. Results of the simulations confirm that the thermal mechanism is responsible for the formation of the electrical prepeak and the pressure waves.
Voronov, Maxim; Hoffmann, Volker; Steingrobe, Tobias; Buscher, Wolfgang; Engelhard, Carsten; Storey, Andrew; Ray, Steven; Hieftje, Gary
Xenon doping of glow discharge polymer by ion implantation
We demonstrate controlled doping of a glow discharge polymer by implantation with 500 keV Xe ions at room temperature. The Xe retention exhibits a threshold behavior, with a threshold dose of {approx}2 x 10{sup 14} cm{sup -2}. Doping is accompanied by irradiation-induced changes in the polymer composition, including gradual H loss and a more complex non-monotonic behavior of the O concentration. The matrix composition saturates at C{sub 0.77}H{sub 0.22}O{sub 0.01} for Xe doses above {approx}5 x 10{sup 14} cm{sup -2} and up to the maximum dose studied (5 x 10{sup 15} cm{sup -2}). The retention mechanism is attributed to the modification of the polymer from a chain-like to clustered ring structure. The dopant profile and the elemental composition of the implanted polymer exhibit good stability upon thermal annealing up to 305 deg. C.
Shin, Swanee J.; Kucheyev, Sergei O.; Orme, Christine A.; Hamza, Alex V. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Youngblood, Kelly P.; Nikroo, Abbas; Moreno, Kari A.; Chen, Bryan [General Atomics, San Diego, California 92186 (United States)
Echocardiographic abnormalities following cardiac radiation
Five years or more after receiving cardiac radiation, 41 patients with Hodgkin's disease and seminoma in remission were subjected to echocardiography. The abnormalities detected included pericardial thickening in 70%, thickening of the aortic and/or mitral valves in 28%, right ventricular dilatation or hypokinesis in 39%, and left ventricular dysfunction in 39%. In the 23 patients treated by an upper mantle technique with shielding, the incidence of right ventricular abnormalities and valvular thickening was significantly lower than in patients treated with modified techniques. Although no symptoms were attributable to the observed abnormalities, longer follow-up time may reveal important functional implications.
Perrault, D.J.; Levy, M.; Herman, J.D.; Burns, R.J.; Bar Shlomo, B.Z.; Druck, M.N.; Wu, W.Q.; McLaughlin, P.R.; Gilbert, B.W.
Hereditary Evaluation of Multiple Developmental Abnormalities in the Havanese Dog Breed
The Havanese is a toy breed that presents with a wide range of developmental abnormalities. Skeletal defects, particularly osteochondrodysplasia (OCD), are the most frequently observed anomalies. Cataracts, liver shunts, heart murmurs, and miss- ing incisors are also common in this breed. Estimates of heritability and complex segregation analyses were carried out to evaluate modes of transmission for these abnormalities. A
ALISON N. STARR; T HOMAS R. FAMULA; N. J. Markward; J. V. Baldwin; K ARON D. FOWLER; DIANE E. KLUMB; N. L. Simpson; KEITH E. MURPHY
Effects of Cloud on Goddard Lidar Observatory for Wind (GLOW) Performance and Analysis of Associated Errors
The Goddard Lidar Observatory for Wind (GLOW), a mobile direct detection Doppler LIDAR based on molecular backscattering for measurement of wind in the troposphere and lower stratosphere region of atmosphere is operated and its errors characterized. It was operated at Howard University Beltsville Center for Climate Observation System (BCCOS) side by side with other operating instruments: the NASA/Langely Research Center Validation Lidar (VALIDAR), Leosphere WLS70, and other standard wind sensing instruments. The performance of Goddard Lidar Observatory for Wind (GLOW) is presented for various optical thicknesses of cloud conditions. It was also compared to VALIDAR under various conditions. These conditions include clear and cloudy sky regions. The performance degradation due to the presence of cirrus clouds is quantified by comparing the wind speed error to cloud thickness. The cloud thickness is quantified in terms of aerosol backscatter ratio (ASR) and cloud optical depth (COD). ASR and COD are determined from Howard University Raman Lidar (HURL) operating at the same station as GLOW. The wind speed error of GLOW was correlated with COD and aerosol backscatter ratio (ASR) which are determined from HURL data. The correlation related in a weak linear relationship. Finally, the wind speed measurements of GLOW were corrected using the quantitative relation from the correlation relations. Using ASR reduced the GLOW wind error from 19% to 8% in a thin cirrus cloud and from 58% to 28% in a relatively thick cloud. After correcting for cloud induced error, the remaining error is due to shot noise and atmospheric variability. Shot-noise error is the statistical random error of backscattered photons detected by photon multiplier tube (PMT) can only be minimized by averaging large number of data recorded. The atmospheric backscatter measured by GLOW along its line-of-sight direction is also used to analyze error due to atmospheric variability within the volume of measurement. GLOW scans in five different directions (vertical and at elevation angles of 45� in north, south, east, and west) to generate wind profiles. The non-uniformity of the atmosphere in all scanning directions is a factor contributing to the measurement error of GLOW. The atmospheric variability in the scanning region leads to difference in the intensity of backscattered signals for scanning directions. Taking the ratio of the north (east) to south (west) and comparing the statistical differences lead to a weak linear relation between atmospheric variability and line-of-sights wind speed differences. This relation was used to make correction which reduced by about 50%.
Bacha, Tulu
Thermoluminescence systems with two or more glow peaks described by anomalous kinetic parameters
The usual first and second order TL kinetic expressions are based on a number of assumptions, including the usually unstated assumption that charges released from one type of trap, giving rise to one glow peak, are not retrapped on other types of traps, associated with other glow peaks. Equations have been developed describing TL systems in which charges released from one type of trap may be retrapped in other types of traps. Called interactive kinetic equations, they are quite simple but have been studied by numerical methods. In particular, glow curves computed from the interactive kinetic equations have been regarded as data and analyzed by fitting them to the usual first and second order kinetic expressions. All of the anomalous features described above are reproduced. For example, usually the computed glow peaks are well fitted by the first and second order expressions over their upper 60 to 80% but not in the wings. This explains why the usual analysis methods, especially those utilizing peak temperature, full width, etc. appear to describe such peaks. Often unrealistic kinetic parameters are often obtained. Furthermore, the computed glow curves often reproduce the observed dependence on dose.
Argon and argon-oxygen glow discharge cleaning of the Main Ring beam pipe
This report presents the experimental results from the argon and argon-oxygen gas mixture glow discharge in the Main Ring beam pipe and is a follow-up to the proposal for vacuum improvements of the Main Ring magnets and straight sections and the warm Tevatron straight sections. Glow discharge was used in the experiment in order to clean the vacuum system instead of bakeout which could only be performed with great difficulty or not at all. It is a relatively simple and very effective method. The glow discharge occurs under specific gas pressures (10--120 mTorr) and current flows (10/sup /minus/5/ /minus/ 10/sup /minus/1/ A) through gas excitation and formation of plasma conditions. Deexcitation of the gas molecules produces visible light. Several mechanisms have been proposed to explain the glow discharge cleaning process. Ions can sputter adsorbed molecules or atoms at the cathode surface and even produce lattice damage extending several monolayers below the surface. The glow discharge has already been extensively used for vacuum improvements in accelerators. 9 refs.
Trbojevic, D.; Pastore, N.
The abnormal proximal tibiofibular joint.
Abnormalities of the proximal tibiofibular joint are infrequently encountered. Mostly instability occurs as a result of trauma. Four types of instability are distinguished: subluxation, anterolateral, posteromedial and superior dislocation. Four radiological methods designed to visualize abnormalities of the proximal tibiofibular joint are discussed. Special notice is given to the clinical relevance of a new method. Instability was demonstrated in 19 patients; 16 of these were treated by an operation. History, data obtained by physical examination and ways of treatment are discussed. PMID:6703874
Veth, R P; Kingma, L M; Nielsen, H K
Glow plasma trigger for electron cyclotron resonance ion sources
Electron cyclotron resonance ion sources (ECRISs) are particularly useful for nuclear, atomic, and high energy physics, as unique high current generators of multicharged ion beams. Plasmas of gas discharges in an open magnetic trap heated by pulsed (100 ?s and longer) high power (100 kW and higher) high-frequency (greater than 37.5 GHz) microwaves of gyrotrons is promising in the field of research in the development of electron cyclotron resonance sources for high charge state ion beams. Reaching high ion charge states requires a decrease in gas pressure in the magnetic trap, but this method leads to increases in time, in which the microwave discharge develops. The gas breakdown and microwave discharge duration becomes greater than or equal to the microwave pulse duration when the pressure is decreased. This makes reaching the critical plasma density initiate an electron cyclotron resonance (ECR) discharge during pulse of microwave gyrotron radiation with gas pressure lower than a certain threshold. In order to reduce losses of microwave power, it is necessary to shorten the time of development of the ECR discharge. For fast triggering of ECR discharge under low pressure in an ECRIS, we initially propose to fill the magnetic trap with the plasmas of auxiliary pulsed discharges in crossed ExB fields. The glow plasma trigger of ECR based on a Penning or magnetron discharge has made it possible not only to fill the trap with plasma with density of 1012 cm-3, required for a rapid increase in plasma density and finally for ECR discharge ignition, but also to initially heat the plasma electrons to Te~20 eV.
Vodopianov, A. V.; Golubev, S. V.; Izotov, I. V.; Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu.
Abnormal Position and Presentation of the Fetus
... Health Issues > Complications of Labor and Delivery 4 Abnormal Position and Presentation of the Fetus Position refers ... neck flexed, and presentation is head first. An abnormal position is facing forward, and abnormal presentations include ...
Best Magnetic Condition to Generate Hollow Cathode Glow Plasma in High Vacuum
Based on magnetron hollow cathode discharge, the magnetic condition of glow plasma generation in high vacuum, including both direction and magnitude of the applied magnetic field, is theoretically derived and experimentally evaluated in this paper. Single particle orbital theory is introduced to discuss the possibilities to generate glow plasma at gas pressure under 10-2 Pa when the magnetic field direction is parallel or perpendicular or oblique to the electric field direction. A quantitative estimation criterion of magnetic induction intensity is also proposed in theory. The comparison with experiments suggests that glow plasma in high vacuum will form more easily in oblique magnetic field condition and that the criterion is accurate enough to estimate magnetic induction intensity at a certain gas pressure.
Zhao, Xiaoling; Chen, Shixiu; Chen, Kun; Chen, Bokai
Glow phenomenon and crystallization: Evidence that they are different events for hafnium-zirconium mixed oxides
If hydrous zirconia is heated at a controlled rate, an exothermic event occurs at about 723 K. Several investigators attributed this to a 'glow phenomenon', while others termed this a 'crystallization' process. These two events occur at the same temperature (723 K) for zirconia. However, evidence is presented to show that crystallization and the glow phenomenon occur at different temperatures for hafnia and Hf/Zr mixed oxides. In the first step of the transformation, the amorphous material undergoes a crystallization process to yield small crystals which diffract X-rays and possess a high surface area. In the second transformation, these small crystals coalesce to form larger particles which contain multiple domains since the crystal size obtained from X-ray line broadening does not change significantly during the exothermic event. The present results demonstrate that crystallization and the exothermic events, commonly referred to as a glow phenomenon, may be two separate events.
Srinivasan, R.; Davis, B.H. (Univ. of Kentucky, Lexington (United States))
Physics of self-sustained oscillations in the positive glow corona
The physics of self-sustained oscillations in the phenomenon of positive glow corona is presented. The dynamics of charged-particle oscillation under static electric field has been briefly outlined; and, the resulting self-sustained current oscillations in the electrodes have been compared with the measurements from the positive glow corona experiments. The profile of self-sustained electrode current oscillations predicted by the presented theory qualitatively agrees with the experimental measurements. For instance, the experimentally observed saw-tooth shaped electrode current pulses are reproduced by the presented theory. Further, the theory correctly predicts the pulses of radiation accompanying the abrupt rises in the saw-tooth shaped current oscillations, as verified from the various glow corona experiments.
Cho, Sung Nae [Micro Devices Group, Micro Systems Laboratory, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd, Mt. 14-1 Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of)
Exploring the accuracy and reliability of plasma fluid models for direct current glow discharges
Glow discharges are of fundamental importance to a variety of industrial applications such as plasma processing, discharge lighting and plasma chemistry. Therefore, a detailed understanding of the physical phenomena that occur within glow discharges is necessary for further advances in design and optimization of relevant plasma applications. Of the various plasma modeling approaches, most use either a fluid approximation, kinetic (particle) approach, or a hybrid model. Although each method has its own set of unique advantages, recent advances in hybrid techniques have shown unique promise to maintain computational efficiency and accuracy. The validity of assumptions within the fluid and hybrid models will be established by direct comparison with results obtained in an electrostatic direct implicit particle-in-cell code (EDIPIC). The accuracy of these assumptions will also be explored within each region of a typical glow discharge and relevant theory will be discussed to explain these results.
Underwood, Thomas; Kaganovich, Igor; Khrabrov, Alexander
Removal of the codeposited carbon layer using He O glow discharge
In this study we examine the combination of a He-O glow discharge with heating as a possible technique to remove deuterium from TFTR tiles. Samples were cut from a relatively large area containing a uniform codeposited layer of deuterium and carbon. Auger/SEM was used to generate micrographs of each of the samples. The samples were also examined using Rutherford backscattering to determine the near surface composition. Individual samples were then exposed to a He-O glow discharge while being heated. After the exposure, the samples were returned for Auger/SEM and RBS of the same areas examined prior to the exposure. Comparing the samples before and after exposure revealed that the amount of the codeposited layer removed was significantly less than 1 ?m. Removal rates this low would suggest that He-O glow discharge with heating is insufficient to remove the thick layers predicted for ITER in a timely fashion.
Kunz, C. L.; Causey, R. A.; Clift, M.; Wampler, W. R.; Cowgill, D. F.
O2 and CO2 glow-discharge-assisted oxygen transport through Ag
Experiments were conducted to determine whether dissociative adsorption is a possible limitation of the oxygen permeability through Ag, using the upstream glow-discharge dissociation of O2 and CO2 to provide a gas phase source of atomic oxygen. Results suggest that the dissociative adsorption step limits the supply of oxygen atoms to the upstream side of the membrane. When the upstream O2 was replaced by an equal pressure of CO2 in absence of glow discharge, only a small permeation signal was observed; the application of the glow discharge increasded the oxygen transport flux from 3.25 x 10 to the 12th/sq cm per sec to 1.74 x 10 to the 14th/sq cm per sec. It is suggested that this method of separating O2 from a CO2-rich atmosphere may be considered for providing oxygen for the astronauts in a manned expedition to Mars.
Outlaw, R. A.
Plasma On the Rocks: DC Atmospheric-Pressure Normal Glow Plasma Enhanced by Natural Basalt Microdischarges
DC normal glow discharges at atmospheric pressure in air and other gases are of interest in plasma processing, since they eliminate the need for low-pressure technology and vacuum-compatible materials. We have found that a DC normal glow discharge in air is stabilized and enlarged by passing it through a thickness of low-porosity rock such as basalt or granite. We observe a stable positive column in air up to 15 mm long with stable striations that depend on current. The airborne portion of the discharge shows characteristics of a normal glow discharge, including relatively constant voltage as current varies. A 13-kV, 5 mA discharge between a tungsten electrode 30 mm away from the surface of a basalt sample enlarges to over 15 mm diameter at the surface. We will present still and motion photography, spectra, and I-V measurements of this phenomenon, along with a simplified theory.
Stephan, Karl; Ghimire, Sagar
Green long-after-glow luminescence of Tb3+ in Sr2SiO4
The green long-after-glow luminescence from Tb3+-doped Sr2SiO4 phosphors, which are synthesized by the high temperature solid state reaction in a reductive atmosphere, is observed in this paper. The results show that under ultraviolet excitation, the obtained phosphors produce an intense green-lighting-emission from the Tb3+, and the green-lighting long-after-glow luminescence related to Tb3+ can last half an hour after the irradiation source has been removed. Moreover, the effects of co-doping Li+, Dy3+, Er3+, Gd3+, and Yb3+ with Tb3+ on the decay properties and thermoluminescence properties are investigated to confirm the long-after-glow mechanism.
Wang, Qi; Qiu, Jian-Bei; Song, Zhi-Guo; Zhou, Da-Cheng; Xu, Xu-Hui
Gas Breakdown of Radio Frequency Glow Discharges in Helium at near Atmospheric Pressure
A one-dimensional self-consistent fluid model was developed for radio frequency glow discharge in helium at near atmospheric pressure, and was employed to study the gas breakdown characteristics in terms of breakdown voltage. The effective secondary electron emission coefficient and the effective electric field for ions were demonstrated to be important for determining the breakdown voltage of radio frequency glow discharge at near atmospheric pressure. The constant of A was estimated to be 64�4 cm-1Torr-1, which was proportional to the first Townsend coefficient and could be employed to evaluate the gas breakdown voltage. The reduction in the breakdown voltage of radio frequency glow discharge with excitation frequency was studied and attributed to the electron trapping effect in the discharge gap.
Liu, Xinkun; Xu, Jinzhou; Cui, Tongfei; Guo, Ying; Zhang, Jing; Shi, Jianjun
Oscillation modes of direct current microdischarges with parallel-plate geometry
Two different oscillation modes in microdischarge with parallel-plate geometry have been observed: relaxation oscillations with frequency range between 1.23 and 2.1 kHz and free-running oscillations with 7 kHz frequency. The oscillation modes are induced by increasing power supply voltage or discharge current. For a given power supply voltage, there is a spontaneous transition from one to other oscillation mode and vice versa. Before the transition from relaxation to free-running oscillations, the spontaneous increase of oscillation frequency of relaxation oscillations form 1.3 kHz to 2.1 kHz is measured. Fourier transform spectra of relaxation oscillations reveal chaotic behavior of microdischarges. Volt-ampere (V-A) characteristics associated with relaxation oscillations describes periodical transition between low current, diffuse discharge, and normal glow. However, free-running oscillations appear in subnormal glow only.
Stefanovic, Ilija; Kuschel, Thomas; Winter, Joerg [Institut fuer Experimentalphysik II, Ruhr-Universitaet Bochum, 44781 Bochum (Germany); Skoro, Nikola; Maric, Dragana; Petrovic, Zoran Lj [Institute of Physics, University of Belgrade, POB 68, 11080 Belgrade (Serbia)
Stefanovi?, Ilija; Kuschel, Thomas; �koro, Nikola; Mari?, Dragana; Petrovi?, Zoran Lj; Winter, J�rg
Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches
An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.
Christophorou, L.G.; Hunter, S.R.
Sterilization and plasma processing of room temperature surfaces with a one atmosphere uniform glow discharge plasma (OAUGDP)
A technique for generating active species with the one atmosphere uniform glow discharge plasma (OAUGDP) has been developed and tested in a wide range of potential plasma processing applications, including the sterilization and decontamination of surfaces. The OAUGDP is a non-thermal plasma with the classical characteristics of a low pressure DC normal glow discharge that operates in air (and other
Rami Ben Gadri; J. Reece Roth; Thomas C. Montie; Kimberly Kelly-Wintenberg; Peter P.-Y. Tsai; Dennis J. Helfritch; Paul Feldman; Daniel M. Sherman; Fuat Karakaya; Zhiyu Chen
Colour vision in the glow-worm Lampyris noctiluca (L.) (Coleoptera: Lampyridae): evidence for a green-blue chromatic mechanism
Male glow-worms Lampyris noctiluca find their bioluminescent mates at night by phototaxis. There is good evidence that location of mates by lampyrid beetles is achieved by a single spectral class of photoreceptor, whose spectral sensitivity is tuned to the bioluminescent spectrum emitted by conspecifics, and is achromatic. We ask whether glow-worm phototaxis involves interactions between two spectral classes of photoreceptor.
David Booth; Alan J. A. Stewart; Daniel Osorio
A study of glow-discharge and permeation techniques for extraterrestrial oxygen beneficiation
Extraction of oxygen from Martian atmosphere and compression of lunar oxygen can utilize stabilized zirconia electrochemical pumps. Silver membranes can be used as electrodes to increase oxygen yield at relatively low temperatures. This study has investigated oxygen permeation through Ag 0.05Zr membranes with glow-discharge assisted disassociation. Data show that the overall process is controlled by bulk diffusion but the slow dissociative adsorption onto the surface limited the overall transport substantially. With glow-discharge assisted dissociation, an order of magnitude increase in oxygen throughput can be produced at relatively low temperatures (450-550C).
Ash, R. L.; Wu, D.; Outlaw, R. A.
An experimental study on discharge mechanism of pulsed atmospheric pressure glow discharges
The discharge mechanism of pulsed atmospheric pressure glow discharges excited by the unipolar positive voltage pulses between two parallel plate electrodes with or without one dielectric barrier on the ground electrode in flowing helium has been characterized by nanosecond time resolved optical and electrical measurements. The uniform glow discharges can only be achieved when the voltage pulse duration is less than 1 {mu}s with bare electrodes. With introducing a dielectric barrier on the ground electrode, a model of electrons traveling on the background ions between two discharge events is proposed to explain the discharge mechanism and characteristics in terms of discharge ignition, discharge spatial profile and discharge current amplitude.
Huang Xiaojiang; Bao Yun [College of Science, Donghua University, Shanghai 201620 (China); Member of Magnetic Confinement Fusion Research Center, Ministry of Education of the People's Republic of China, Shanghai 201620 (China); Sun Liqun [College of Science, Donghua University, Shanghai 201620 (China); Zhang Jing; Shi, J. J. [College of Science, Donghua University, Shanghai 201620 (China); State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Member of Magnetic Confinement Fusion Research Center, Ministry of Education of the People's Republic of China, Shanghai 201620 (China)
Long range temporal correlation in the chaotic oscillations of a dc glow discharge plasma
Long range temporal correlations in the fluctuations of the plasma floating potentials (measured using a Langmuir probe) are investigated in a dc glow discharge plasma. Keeping the neutral pressure constant, the discharge voltage was varied and at the formation of the plasma, quasi periodic oscillations were excited and on further increase of the discharge voltage they became chaotic (irregular) beyond a threshold voltage. We compared the Lyapunov exponent with the Hurst exponent obtained from R/S statistics which showed an opposite behaviour at the transition point. These results are perhaps new since we have not come across such comparative analysis for chaotic oscillations in a glow discharge plasma before.
Lahiri, S. [Dinabandhu Mahavidyalaya, Bongaon, North 24 Parganas, Kolkata 743235 (India); Roychowdhury, D. [Techno India, EM4/1 Sector V, Salt Lake, Kolkata 700091 (India); Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)
Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium
In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.
Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin
Thermoluminescence response and glow curve structure of Sc2TiO5 �-irradiated.
Discandium titanate (Sc2TiO5) powder was synthesized in order to analyze its thermoluminescence (TL) response. The TL glow curve structure shows two peaks: at 453-433K and at 590-553K. The TL beta dose-response has a linear behavior over the dose range 50-500Gy. The Tstop preheat method shows five glow peaks that were taken into account to calculate the kinetic parameters using the CGCD procedure. TL results support the possible use of Sc2TiO5 as a new phosphor in high �-dose dosimetry. PMID:24698777
Mu�oz, I C; Brown, F; Dur�n-Mu�oz, H; Cruz-Zaragoza, E; Dur�n-Torres, B; Alvarez-Monta�o, V E
Complex patterns of abnormal heartbeats
Individuals having frequent abnormal heartbeats interspersed with normal heartbeats may be at an increased risk of sudden cardiac death. However, mechanistic understanding of such cardiac arrhythmias is limited. We present a visual and qualitative method to display statistical properties of abnormal heartbeats. We introduce dynamical ``heartprints'' which reveal characteristic patterns in long clinical records encompassing ~105 heartbeats and may provide information about underlying mechanisms. We test if these dynamics can be reproduced by model simulations in which abnormal heartbeats are generated (i) randomly, (ii) at a fixed time interval following a preceding normal heartbeat, or (iii) by an independent oscillator that may or may not interact with the normal heartbeat. We compare the results of these three models and test their limitations to comprehensively simulate the statistical features of selected clinical records. This work introduces methods that can be used to test mathematical models of arrhythmogenesis and to develop a new understanding of underlying electrophysiologic mechanisms of cardiac arrhythmia.
Schulte-Frohlinde, Verena; Ashkenazy, Yosef; Goldberger, Ary L.; Ivanov, Plamen Ch.; Costa, Madalena; Morley-Davies, Adrian; Stanley, H. Eugene; Glass, Leon
Individuals having frequent abnormal heartbeats interspersed with normal heartbeats may be at an increased risk of sudden cardiac death. However, mechanistic understanding of such cardiac arrhythmias is limited. We present a visual and qualitative method to display statistical properties of abnormal heartbeats. We introduce dynamical "heartprints" which reveal characteristic patterns in long clinical records encompassing approximately 10(5) heartbeats and may provide information about underlying mechanisms. We test if these dynamics can be reproduced by model simulations in which abnormal heartbeats are generated (i) randomly, (ii) at a fixed time interval following a preceding normal heartbeat, or (iii) by an independent oscillator that may or may not interact with the normal heartbeat. We compare the results of these three models and test their limitations to comprehensively simulate the statistical features of selected clinical records. This work introduces methods that can be used to test mathematical models of arrhythmogenesis and to develop a new understanding of underlying electrophysiologic mechanisms of cardiac arrhythmia.
Schulte-Frohlinde, Verena; Ashkenazy, Yosef; Goldberger, Ary L.; Ivanov, Plamen Ch; Costa, Madalena; Morley-Davies, Adrian; Stanley, H. Eugene; Glass, Leon
Immune abnormalities in myelodysplastic syndromes.
The immune states of 52 patients with myelodysplastic syndromes classified according to the FAB criteria were studied. Serum electrophoresis and immunoelectrophoresis, direct Coombs test, and tests for organ and non-organ specific antibodies were performed. Twenty six patients had immunoglobulin abnormalities: six (11.5%) had monoclonal gammopathy; 17 (32.6%) had polyclonal increases in serum immunoglobulin; while in three (5.8%) immunoglobulin concentrations were decreased. The distribution of immunoglobulin abnormalities among the five myelodysplastic syndrome subtypes was fairly uniform. Results of direct Coombs test were negative in all cases. Organ specific antibodies were not detected in any of the patients tested, although two patients were found positive for antinuclear antibodies. The presence of immunoglobulin abnormalities indicates an involvement of the lymphoplasmatic system in myelodysplastic syndromes.
Economopoulos, T; Economidou, J; Giannopoulos, G; Terzoglou, C; Papageorgiou, E; Dervenoulas, J; Arseni, P; Hadjioannou, J; Raptis, S
Craniocervical junction abnormalities in dogs.
Craniocervical junction abnormality (CJA) is a term that encompasses a number of developmental anatomical aberrations at the region of the caudal occiput and first two cervical vertebrae. Chiari-like malformation appears to be the most common CJA encountered in dogs, and there has been a tremendous amount of clinical investigation into this disorder in recent years. Other abnormalities in this region include atlanto-occipital overlap, dorsal constriction at C1/C2 and atlantoaxial instability. This review article presents an overview of the current understanding of CJA in dogs, as well as medical and surgical treatment options available. PMID:23556552
Dewey, C W; Marino, D J; Loughin, C A
The Rose-red Glow of Star Formation
The vivid red cloud in this new image from ESO's Very Large Telescope is a region of glowing hydrogen surrounding the star cluster NGC 371. This stellar nursery lies in our neighbouring galaxy, the Small Magellanic Cloud. The object dominating this image may resemble a pool of spilled blood, but rather than being associated with death, such regions of ionised hydrogen - known as HII regions - are sites of creation with high rates of recent star birth. NGC 371 is an example of this; it is an open cluster surrounded by a nebula. The stars in open clusters all originate from the same diffuse HII region, and over time the majority of the hydrogen is used up by star formation, leaving behind a shell of hydrogen such as the one in this image, along with a cluster of hot young stars. The host galaxy to NGC 371, the Small Magellanic Cloud, is a dwarf galaxy a mere 200 000 light-years away, which makes it one of the closest galaxies to the Milky Way. In addition, the Small Magellanic Cloud contains stars at all stages of their evolution; from the highly luminous young stars found in NGC 371 to supernova remnants of dead stars. These energetic youngsters emit copious amounts of ultraviolet radiation causing surrounding gas, such as leftover hydrogen from their parent nebula, to light up with a colourful glow that extends for hundreds of light-years in every direction. The phenomenon is depicted beautifully in this image, taken using the FORS1 instrument on ESO's Very Large Telescope (VLT). Open clusters are by no means rare; there are numerous fine examples in our own Milky Way. However, NGC 371 is of particular interest due to the unexpectedly large number of variable stars it contains. These are stars that change in brightness over time. A particularly interesting type of variable star, known as slowly pulsating B stars, can also be used to study the interior of stars through asteroseismology [1], and several of these have been confirmed in this cluster. Variable stars play a pivotal role in astronomy: some types are invaluable for determining distances to far-off galaxies and the age of the Universe. The data for this image were selected from the ESO archive by Manu Mejias as part of the Hidden Treasures competition [2]. Three of Manu's images made the top twenty; his picture of NGC 371 was ranked sixth in the competition. Notes [1] Asteroseismology is the study of the internal structure of pulsating stars by looking at the different frequencies at which they oscillate. This is a similar approach to the study of the structure of the Earth by looking at earthquakes and how their oscillations travel through the interior of the planet. [2] ESO's Hidden Treasures 2010 competition gave amateur astronomers the opportunity to search through ESO's vast archives of astronomical data, hoping to find a well-hidden gem that needed polishing by the entrants. Participants submitted nearly 100 entries and ten skilled people were awarded some extremely attractive prizes, including an all expenses paid trip for the overall winner to ESO's Very Large Telescope (VLT) on Cerro Paranal, in Chile, the world's most advanced optical telescope. The ten winners submitted a total of 20 images that were ranked as the highest entries in the competition out of the near 100 images. More information ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO op
Interpreting chromosomal abnormalities using Prolog.
This paper describes an expert system for interpreting the standard notation used to represent human chromosomal abnormalities, namely, the International System for Human Cytogenetic Nomenclature. Written in Prolog, this program is very powerful, easy to maintain, and portable. The system can be used as a front end to any database that employs cytogenetic notation, such as a patient registry. PMID:2185921
Cooper, G; Friedman, J M
Extracellular Matrix Abnormalities in Schizophrenia
Emerging evidence points to the involvement of the brain extracellular matrix (ECM) in the pathophysiology of schizophrenia (SZ). Abnormalities affecting several ECM components, including Reelin and chondroitin sulfate proteoglycans (CSPGs), have been described in subjects with this disease. Solid evidence supports the involvement of Reelin, an ECM glycoprotein involved in corticogenesis, synaptic functions and glutamate NMDA receptor regulation, expressed prevalently in distinct populations of GABAergic neurons, which secrete it into the ECM. Marked changes of Reelin expression in SZ have typically been reported in association with GABA-related abnormalities in subjects with SZ and bipolar disorder. Recent findings from our group point to substantial abnormalities affecting CSPGs, a main ECM component, in the amygdala and entorhinal cortex of subjects with schizophrenia, but not bipolar disorder. Striking increases of glial cells expressing CSPGs were accompanied by reductions of perineuronal nets, CSPG- and Reelin-enriched ECM aggregates enveloping distinct neuronal populations. CSPGs developmental and adult functions, including neuronal migration, axon guidance, synaptic and neurotransmission regulation are highly relevant to the pathophysiology of SZ. Together with reports of anomalies affecting several other ECM components, these findings point to the ECM as a key component of the pathology of SZ. We propose that ECM abnormalities may contribute to several aspects of the pathophysiology of this disease, including disrupted connectivity and neuronal migration, synaptic anomalies and altered GABAergic, glutamatergic and dopaminergic neurotransmission.
Berretta, Sabina
A New Approach to the Copper\\/Epoxy Joint Using Atmospheric Pressure Glow Discharge
A new approach for adhering copper to an epoxy resin was studied. In this new approach, the copper surface was first treated with hydrogen plasma generated by the atmospheric pressure glow (APG) discharge. Then a thin film of ?-aminopropyltriethoxysilane (?-APS) was formed on the treated copper surface. The copper oxide formed by air on the copper surface deteriorated the adhesion
Y. Sawada; S. Ogawa; M. Kogoma
Development of technological sources of gas ions on the basis of hollow-cathode glow discharges
Design principles and basic properties of broad-beam gas ion sources based on a low-pressure glow discharge are discussed. It is shown that properties of the discharge in a coaxial electrode structure with a hollow cathode and a rod anode in a magnetic field favor its use in sources of gas ions. Two main types of ion sources using this electrode
N. V. Gavrilov; G. A. Mesyats; G. V. Radkovski; V. V. Bersenev
Influences of gas flow on atmospheric pressure glow discharge in helium
Atmospheric pressure glow discharge (APGD) was produced in a 5-mm helium gap between two plane-parallel electrodes of 50 mm in diameter, each covered by a 1-mm thick quartz plate. The influence of the helium gas flowing in parallel through the helium gap on APGD was studied. The helium flow rate varies up to 12 liter per minute, corresponding to helium
H. Luo; Z. Liang; B. Lv; X. Wang; Z. Guan; L. Wang
Study of laser resonance ionization mass spectrometry using a glow discharge source
The mass spectra of a metal alloy sample consisting of Al, Cu and Fe were studied using both glow discharge mass spectrometry (GDMS) and resonance ionization mass spectrometry (RIMS). Particular emphasis was placed on the reduction of isobaric interferences and discrimination between those ions formed by the discharge and those formed by the laser radiation.
Xiong, X. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)]|[Eastern Analytical, Inc., College Park, MD (United States); Hutchinson, J.M.R.; Fassett, J.D.; Lucatorto, T.B.; Schima, F.J.; Bowman, W.A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Hess, K.R. [Franklin and Marshall Coll., Lancaster, PA (United States). Dept. of Chemistry
The Blue Glow from the Back Row: Live Theater and the Wireless Teen
Every year the author and his colleagues take their grade 12 English students to see four plays at one of Canada's major theaters. Chatting about the series on the last day of class, his students asked him if he had seen "the blue glow from the back row." Laughing at his bewilderment, they told him that during the performances so many students�
Richardson, John M.
Mineralization of alkylbenzenesulfonates in water by means of contact glow discharge electrolysis
Mineralization of aqueous alkylbenzenesulfonates (ABS) was investigated by means of contact glow discharge electrolysis (CGDE). Toluenesulfonic and dodecylbenzenesulfonic acids in a neutral phosphate buffer solution were smoothly degraded and eventually converted to inorganic carbon and sulfate ion when CGDE was conducted under the applied DC voltage of 500V and current of ca. 90mA. As the intermediate products, some phenolic compounds
Ryo Amano; Meguru Tezuka
The Negative Glow and Faraday Dark Space in Near-Normal Neon Discharges.
Radial and axial electrostatic probe measurements have been made of the negative glow and Faraday dark space of some weakly 'anomalous' cold cathode discharges in neon at pressures near 1 torr. These have been analyzed and discussed with the aim of extend...
R. M. Reynolds W. B. Montgomery K. G. Emeleus G. A. Woolsey
Very low pressure RF glow discharge plasma using multi-dipole surface magnetic fields
Summary form only given. It is shown that, by taking advantage of surface multidipole fields, RF glow discharges can be maintained down to pressures at least as low as 2�10-5 torr. Large effective electrode separation and good plasma uniformity can be achieved. Only one conventional electrode was used. Two different types of RF powered electrodes were explored: a conventional plate
N. Hershkowitz; M. H. Cho; A. Wendt; J. Pruski
High explosives vapor detection by atmospheric sampling glow discharge ionization/tandem mass spectrometry
The combination of atmospheric sampling glow discharge ionization with tandem mass spectrometry for the detection of traces of high explosives is described. Particular emphasis is placed on use of the quadrupole ion trap as the type of tandem mass spectrometer. Atmospheric sampling glow discharge provides a simple, rugged, and efficient means for anion formation while the quadrupole ion trap provides for efficient tandem mass spectrometry. Mass selective ion accumulation and non-specific ion activation methods can be used to overcome deleterious effects arising from ion/ion interactions. Such interactions constitute the major potential technical barrier to the use of the ion trap for real-time monitoring of targeted compounds in uncontrolled and highly variable matrices. Tailored waveforms can be used to effect both mass selective ion accumulation and ion activation. Concatenated tailored waveforms allow for both functions in a single experiment thereby providing the capability for monitoring several targeted species simultaneously. The combination of atmospheric sampling glow discharge ionization with a state-of-the-art analytical quadrupole ion trap is a highly sensitive and specific detector for traces of high explosives. The combination is also small and inexpensive relative to virtually any other form of tandem mass spectrometry. The science and technology underlying the glow discharge/ion trap combination is sufficiently mature to form the basis for an engineering effort to make the detector portable. 85 refs.
McLuckey, S.A.; Goeringer, D.E.; Asano, K.G. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.
Gaseous ion and plasma sources based on glow discharge with electron injection
High current density and simplicity of practical embodiment of the hollow cathode glow discharge favor its use in plasma and charged particle sources. Although, if operating pressure is lower than 10-4 Torr, the discharge voltage usually exceeds 1 kV. One of the possible ways of reducing the discharge voltage is to provide additional energetic electrons for the discharge plasma using
A. V. Vizir; G. Y. Yushkov; A. E. M. Oks
Boundary layer control by a one atmosphere uniform glow discharge plasma layer
Summary form only given, as follows. At the University of Tennessee's Plasma Science Laboratory, we have recently developed, with AFOSR support, a new type of uniform glow discharge plasma which is capable of operating at one atmosphere in air and other gases. This plasma is neither a corona discharge nor a filamentary (ozonizer) discharge, the more familiar plasma discharges also
Chaoyu Liu; J. Reece Roth
The evaluation of electron trapping parameters from conductivity glow curves in cadmium sulphide
An extensive experimental examination of conductivity glow curves and their analysis has been made on a variety of CdS crystals. A large number of analytical methods have been used to evaluate trap depths and capture cross sections. It is shown that it is possible to obtain consistent results and determine whether retrapping occurs provided an experimental procedure is adopted to
K. H. Nicholas; J. Woods
A glow discharge unit to render electron microscope grids and other surfaces hydrophilic
We describe the design, construction, and operation of a simple glow discharge unit that can be used to make surfaces such as carbon-coated electron microscopy grids and glass coverslips hydrophilic. The use of a vac- uum leak detector (Tesla coil) in place of a conventional high-voltage power supply and a small plastic desiccator for the vacuum chamber make the unit
Ueli Aebi; Thomas D. Pollard
On the spark to pseudoglow and glow transition mechanism and discharge detectability
The transition mechanism for spark to pseudoglow and glow discharge is examined and the attending question of discharge detectability in an electrical apparatus is considered. The effect of gap spacing or cavity diameter and overvoltage is discussed in terms of experimental observations and theoretical calculations using a two-dimensional mathematical model
R. Bartnikas; J. P. Novak
Plasma degradation of dyes in water with contact glow discharge electrolysis
Contact glow discharge electrolysis (CGDE) of two dyes, weak acid brilliant red B and weak acid flavine G, was investigated under different concentrations, temperature and mediums. From the variation of their concentration with the reaction time, it was demonstrated that the oxidation would be a first-order reaction. On the base line of UV spectra of solution in the degradation process,
Jinzhang Gao; Xiaoyan Wang; Zhongai Hu; Hualing Deng; Jingguo Hou; Xiaoquan Lu; Jingwan Kang
Space-Time Association of Auroral Glow and X Rays at Balloon Altitude
A space-time association between a widespread auroral glow over Alaska and X rays at balloon altitude on March 5, 1962, has been observed. It is estimated that electrons above 25 key contribute about I per cent of the luminous excitation on this occasion. Results. During the night of March 4-5, 1962, a balloon carrying a scintillation detector and pulse discrimination
K. A. Anderson; R. Dewitt
Crystalline structures of strongly coupled dusty plasmas in dc glow discharge strata
Strongly coupled dusty plasmas are formed by suspending micron-sized dust particles in strata of a dc glow neon discharge. We have observed for the first time an ordered structure of the negatively charged particles trapped in the strata region. Image analysis reveals the crystalline structure, which is consistent with a large value of the Coulomb coupling parameter.
Vladimir E. Fortov; Anatoli P. Nefedov; Vladimir M. Torchinsky; Vladimir I. Molotkov; Oleg F. Petrov; Alex A. Samarian; Andrew M. Lipaev; Alexei G. Khrapak
Spatio-temporal pattern formation in a lateral high-frequency glow discharge system
In a two-dimensional lateral high frequency glow discharge system pattern formation has been investigated experimentally. We observe, e.g., Turing patterns, isolated solitary like filaments, filament clusters, coexisting stationary and nonstationary structures and various kinds of rotating filamentary patterns.
E. Ammelt; D. Schweng; H.-G. Purwins
The Goddard Lidar Observatory for Wind (GLOW), a mobile direct detection Doppler LIDAR based on molecular backscattering for measurement of wind in the troposphere and lower stratosphere region of atmosphere is operated and its errors characterized. It was operated at Howard University Beltsville Center for Climate Observation System (BCCOS) side by side with other operating instruments: the NASA\\/Langely Research Center
Tulu Bacha
Glow Discharge Characteristics in Relation to Anode Size in Inertial Electrostatic Confinement Fusion
An Inertial Electrostatic Confinement Fusion device is a very simple and safe neutron source that uses a glow discharge for deuterium-deuterium fusion. The discharge characteristics of the device were studied experimentally. The relationship between gas pressure and applied voltage was examined by light changes of the device's anode size. The gas pressure ranges in which the device was able to
Hodaka Osawa; Shigehisa Yoshimura; Takehiro Tabata; Masami Ohnishi
A Study on Water Treatment Induced by Plasma with Contact Glow Discharge Electrolysis
Oxidative degradation of eight kinds of dyes induced by plasma in aqueous solution was investigated with contact glow discharge electrolysis (CGDE). It has been demonstrated that these eight dyes underwent degradation in CGDE, where Fe2+ could be utilised to raise the efficiency of degradation of dyes.
Hu, Zhong-ai; Wang, Xiao-yan; Gao, Jin-zhang; Deng, Hua-ling; Hou, Jing-guo; Lu, Xiao-quan; Kang, Jing-wan
Glow discharge optical spectroscopy depth profiles of ion implanted steel, titanium and titanium nitride coatings
The resistance of ion implanted surfaces against wear and corrosion is influenced by the chemical composition of the modified zone. It is shown that glow discharge optical spectroscopy (GDOS) is a sensitive and easily applicable technique to investigate composition depth profiles of implanted layers. Despite the layer thickness of less than 1 ?m a good resolution can be realized by
F. Seidel; H.-R Stock; P Mayr
Optimization of a Single Plasmaactuator using the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP�)
Summary form only given. Research on electrohydrodynamic (EHD) plasma actuators using the one atmosphere uniform glow discharge plasma (OAUGDPreg) is increasing at a rapid rate. These actuators are a promising flow control technology for subsonic plasma aerodynamics. Recent wind tunnel experiments showed that with the additional momentum from a single plasma actuator on the leading edge, the stall angle of
Xin Dai; J. R. Roth
Energy distribution of heavy particles generated in the cathode fall of glow discharge
The energy spectrum of ions and fast neutrals generated in the cathode fall of a glow discharge is considered on the basis of the Davis model (1963) and in the light of the Boltzmann equation. A fundamental model based on the Boltzmann equation is developed and extended to include the effects of ionization processes due to electrons and ions and
Z. Wronski; J. L. Sullivan; S. O. Saied
Studies of light emission from cathode material in the plasma phase of a glow discharge
Heavy particles bombarding the cathode surface in a glow discharge produce sputtering which liberates cathode material which then appears in the plasma phase in the vicinity of the cathode. The intensity of light emission from fundamental gas atoms depends linearly on the discharge current and this dependence can be explained if it is assumed that these intensities are proportional to
Z. Wronski; J. Sielanko; J. L. Sullivan
Energy distribution of heavy particles generated in the cathode fall of a gas mixture glow discharge
An analytical model based on the solution of the Boltzmann equation and the theory of ion avalanches has been developed for the energy distributions of ions and neutrals created in the cathode fall of a gas mixture glow discharge. The model allows the determination of the energy distributions and flux densities of all possible species, including multiply charged ions. The
Z. Wronski; J. L. Sullivan; C. G. Pearce
Chemical equilibria of rare earth oxides in glow-discharge mass spectrometry
This research centers around method development and fundamental exploration of the rare earth elements (REE) in glow discharge mass spectrometry (GDMS). The capability of GDMS to analyze directly solids materials eliminates the sample dissolution and preconcentration steps required by many other methods. The simplicity of sample preparation and instrumental operation makes GDMS a promising analytical technique for the field of
The effect of glow discharge plasma on the surface properties of Poly (ethylene terephthalate) (PET) film
In the present work, Poly (ethylene terephthalate) films have been exposed to glow discharge air plasma to improve their surface properties for technical applications. Surface energy values have been estimated using contact angle value for different exposure times and different test liquids. Surface composition and morphology of the films were analyzed by XPS and AFM. Crystallinity of the plasma treated
K. Navaneetha Pandiyaraj; V. Selvarajan; R. R. Deshmukh; Mosto Bousmina
Influence of glow cathode on parameters of ion-beam plasma
Summary form only given. The results of an experimental investigation of ion-beam plasma parameters in an ion etching technological system are presented for the case of ion beam space charge neutralization by a glow cathode-neutralizer (CN) in comparison with analogous results without CN. The measured parameters were plasma potential ?pl, neutralizing electrons energy distribution fe and temperature of its maxwellian
S. V. Dudin; A. V. Zykov; V. I. Farenik
The chemiluminescence response of neutrophils on polymer surfaces made by glow discharge plasma polymerization
Polypropylene tubes were coated with different polymers made by glow discharge plasma polymerization. Isolated human blood neutrophils were allowed to interact with the polymer surface and the chemiluminescence response of the cells was recorded as a measure of oxidative activation. The polymers represented surfaces that differed markedly with respect to charge, hardness, and wettability. We found that all polymers stimulated
Ghada Nimeri; Asa Augustinsson; BO Lassen; Olle Stendahl; Lena �hman; Hans Elwing
Oxygen gettering properties of boron film produced by diborane dc glow discharge
Boron film coated on plasma facing walls has been utilized to reduce the oxygen impurity level by the gettering action. The boron film is also useful to reduce the hydrogen recycling. In this study, the boronization was conducted by a dc glow discharge with a mixture gas of diborane and helium both for a graphite and a stainless steel (SS)
T. Hino; T. Mochizuki; Y. Hirohata; K. Tsuzuki; N. Inoue; A. Sagara; N. Noda; O. Motojima; K. Mori; T. Sogabe; K. Kuroda
Activated recombinative desorption: a potential component in mechanisms of spacecraft glow
The concept of activated recombination of atomic species on surfaces is capable of explaining the production of vibrationally and translationally excited desorbed molecular species. Equilibrium statistical mechanics predicts that the molecular quantum state distributions of desorbing molecules is a function of only the surface temperature when the adsorption probability is unity and independent of initial collision conditions. In most cases though the adsorption probability is dependent upon initial conditions such as collision energy or internal quantum state distribution of impinging molecules. From detailed balance, such dynamical behavior is reflected in the internal quantum state distribution of the desorbing molecule. A number of surface-atom recombination systems demonstrate this ''nonthermal'' behavior: H/sub 2/-Cu,N/sub 2/-Fe,CO/sub 2/-Pt, etc. It is proposed that this concept, activated recombinative desorption, may offer a common thread in proposed mechanisms of spacecraft glow. Ground-based experiments are proposed which will complement flight investigations probing the mechanism of the glow phenomenon. Using molecular beam techniques and equipment available at Los Alamos, which includes a high translational energy O-atom beam source, mass spectrometric detection of desorbed species, chemiluminescent/laser induced fluorescence detection of electronic and rovibrationally excited reaction products, and Auger detection of surface adsorbed reaction products, we propose a fundamental study of the gas-surface chemistry underlying the glow process. This would lead to the development of materials that could alter the spectral intensity and wave length distribution of the glow.
Cross, J.B.
Hydrogen absorption behavior into boron films by glow discharges in hydrogen and helium
Hydrogen absorption behavior into boron films deposited on graphite and stainless steel (SS) has been studied. Hydrogen absorption into a H-depleted boron film was investigated during a hydrogen glow discharge with pressure drop measured by a diaphragm gauge. It was found that, after strong but short time absorption at initial phase, hydrogen atoms were slowly (a few percents of injected
K. Tsuzuki; M. Natsir; N. Inoue; A. Sagara; N. Noda; O. Motojima; T. Mochizuki; T. Hino; T. Yamashina
Two-Dimensional Particle Simulation of Parallel Plate Radio-Frequency (RF) Glow Discharges.
A two-dimensional model of parallel plate RF glow discharges was developed to study discharge phenomena important in plasma assisted processing of materials. The particle-in-cell method is used to calculate the trajectories of computer particles under the...
E. J. Bennett
A Large Gap of Atmospheric Pressure RF-DBD Glow Discharges in Ar and Mixed Gases
A large gap (up to 5.5 mm) between electrodes is acquired at Ar atmospheric pressure glow discharge (APGD) in radio frequency dielectric barrier discharge (RF-DBD). The characteristics of I-V in single barrier Ar RF-DBD mixed with different ratios of O2 (0-100%) is studied in detail.
Li, Bin; Chen, Qiang; Liu, Zhong-Wei; Wang, Zheng-Duo
Modification of surface properties of polypropylene (PP) film using DC glow discharge air plasma
The industrial use of polypropylene (PP) films is limited because of undesirable properties such as poor adhesion and printability. In the present study, a DC glow discharge plasma has been used to improve the surface properties of PP films and make it useful for technical applications. The change in hydrophilicity of modified PP film surface was investigated by contact angle
K. Navaneetha Pandiyaraj; V. Selvarajan; R. R. Deshmukh; Changyou Gao
Endotoxin removal by radio frequency gas plasma (glow discharge)
Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250�C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to < 0.5 EU/ml in sterile water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR-IR measurements were repeated after employing 3-minute RFGD treatments sequentially for more than 10 cycles to observe removal of deposited matter that correlated with diminished EU titers. The results showed that 5 cycles, for a total exposure time of 15 minutes to low-temperature gas plasma, was sufficient to reduce endotoxin titers to below 0.05 EU/ml, and correlated with concurrent reduction of major endotoxin reference standard absorption bands at 3391 cm-1, 2887 cm-1, 1646 cm -1 1342 cm-1, and 1103 cm-1 to less than 0.05 Absorbance Units. Band depletion varied from 15% to 40% per 3-minute cycle of RFGD exposure, based on peak-to-peak analyses. In some cases, 100% of all applied biomass was removed within 5 sequential 3-minute RFGD cycles. The lipid ester absorption band expected at 1725 cm-1 was not detectable until after the first RFGD cycle, suggesting an unmasking of the actual bacterial endotoxin membrane induced within the gas plasma environment. Future work must determine the applicability of this low-temperature, quick depyrogenation process to medical devices of more complicated geometry than the flat surfaces tested here.
Poon, Angela
Effects of various dopants on NaCl and KCl glow curves
We have measured the thermoluminescence of a number of NaCl and KCl crystals following irradiation at ambient temperature with the same dose (10 kGy) of Co-60 ? rays. We compare the TL of pure samples and of samples doped with europium and calcium ions. In the case of NaCl, additional impurities (Ni, Pb, Sr and Cr) have been investigated. The effects of irradiation are determined using optical absorption and thermoluminescence. Factors investigated include the effects of different dopants on TL glow curves and the effects of thermal annealing samples at 400 �C before the irradiation. Changes in TL glow curves relating to changes in the state of aggregation of the impurities produced by pre-irradiation annealing are reported in this paper. Perhaps the most significant effect is a temperature shift of the main glow peak in pre-annealed compared to not pre-annealed samples in the case of Eu doped NaCl. The magnitude of the shift depends on the concentration of the Eu dopant. Shifts are also observed for Ni and Sr impurities in NaCl, but not for Ca and Cr impurities in NaCl. In the case of KCl, glow peaks generally occur at similar temperatures in doped samples and do not shift when doped samples are pre-annealed. Here the main effect of different impurities is to influence the size of the emission and not the structure of the glow curve. Results are discussed in terms of current theories of thermoluminescence.
Davidson, A. T.; Kozakiewicz, A. G.; Derry, T. E.; Comins, J. D.; Suszynska, M.
Tropospheric Wind Profiles Obtained with the GLOW Molecular Doppler Lidar during the 2002 International H2O Project
The Goddard Lidar Observatory for Winds (GLOW) is a mobile direct detection Doppler lidar system hich uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. In the spring of 2002 GLOW was deployed to the western Oklahoma profiling site (36 deg 33.500 min N, 100 deg 36.371 min W) to participate in the International H2O Project (MOP). During the MOP campaign over 240 hours of wind profiles were obtained with the GLOW lidar in support of a variety of scientific investigations.
Gentry, Bruce M.; Chen, Huailin; Li, Steven X.; Mathur, Savy Asachee; Dobler, Jeremy; Hasselbrack, William
Experimental transition delay using glow-discharge plasma actuators
In the present work plasma actuators were applied in a flat-plate boundary layer with an adverse pressure gradient to influence\\u000a the transition of the boundary layer. The first actuator downstream of the leading edge is operated in pulsed mode to introduce\\u000a perturbations into the boundary layer to promote transition. Two steady operating actuators further downstream damp the perturbations\\u000a significantly, which
Sven Grundmann; Cameron Tropea
Lymphatic abnormalities in Noonan's syndrome.
Five boys who had Noonan's syndrome and lymphatic abnormalities are reported. The youngest boy had clinical lymphoedema and the other four showed dermal backflow after interdigital injection of Patent Blue indicating impairment of flow along the superficial lymphatics. One boy had severe bilateral chylothorax. The lymphographic findings in four of these boys are reported. Patients with the Noonan syndrome frequently have oedema of the hands and feet at birth, which decreases during the first years of life [10]. It has been demonstrated by lymphography that similar peripheral oedema in patients with the Turner's syndrome is due to lymphatic hypoplasia [1, 3]. We report certain lymphatic abnormalities diagnosed by lymphography in four out of five patients with Noonan's syndrome. PMID:673526
Lanning, P; Simil�, S; Suramo, I; Paavilainen, T
A photon counting dynamic digital lock-in amplifier for background suppression in glow discharge atomic emission spectrometry
A photon counting dynamic digital lock-in amplifier, (PC-DDLIA), has been developed for the suppression of Ar lines in glow discharge lamp atomic emission spectrometry, (GDL-AES). The experimental set-up consists of a Grimm-type GDL, a prism-type scanning monochromator, photon counting electronics, an Apple Ile computer with an interface card and a computer controllable high voltage power supply. The photon counting electronics are designed to convert the photon pulses to logic pulses. A discriminator is used to reject pulses below a threshold level. The high voltage power supply is modulated with a square waveform generated from DAC and photon pulses are counted synchronously by the timer/counter chip, versatile interface adaptor (VIA-6522) on the interface card of computer. The data are analyzed in two steps. In the "learn mode", the GDL is modulated with a square waveform between 370 and 670 V and two spectra consisting of only Ar lines are obtained in a spectral window between 287.1 and 290.0 nm. A new modulation waveform is computed from these spectra which yields two overlapped spectra when the PC-DDLIA is scanned over the same spectral window. In the "analysis mode" of data acquisition, a target material with the analyte element(s) in it is used and the spectrometer is scanned with a dynamically varying rectangular waveform over the same spectral window. The net spectrum consists of pure atomic lines free from any Ar lines. The detection limit for the determination of Si (288.2 nm) in the presence of interfering Ar lines (288.1 and 288.4 nm) is found to be 0.083%, whereas suppression of Ar lines over the same spectral window lowers the detection limit to 0.013%.
G�kmen, Ali; Ulgen, Ahmet; Yal�in, ?erife
Computed tomography of thymic abnormalities.
Computed tomographic examinations of 38 patients with surgically and histologically proven diagnosis were reviewed. Twenty subjects (52%) had an invasive thymoma and 16% an hyperplasic thymus. Myasthenia gravis was present in 6 cases (16%) of thymic abnormalities, four (10.5%) with invasive thymoma and two (5%) with thymic hyperplasia. Graves' disease was also present in one case of thymic hyperplasia. We emphasize the contribution of CT to the diagnosis and the prognosis. PMID:3595619
Schnyder, P; Candardjis, G
Emission- and fluorescence-spectroscopic investigation of a glow discharge plasma: Absolute number density of radiative and nonradiative atoms in the negative glow
The excited-state atom densities in the negative glow of a direct-current glow discharge are derived from the spectral-line intensity of radiative atoms and the resonance-fluorescence photon flux of nonradiative atoms. The discharge is operated in a helium-argon gas mixture (molar fraction ratio 91:9; total gas pressure 5 Torr) at a dc current of 0.7-1.2 mA. The observations are made in the region of the maximum luminance in the cathode region, where high-energy electrons accelerated in the cathode fall are injected into the negative glow. The emission intensities of the He I, He II, Ar I, and Ar II spectral lines are measured with a calibrated tungsten ribbon lamp as an absolute spectral-radiance standard. Fluorescence photons scattered by helium and argon atoms in the metastable state and argon atoms in the resonance state are detected by the laser-induced fluorescence (LIF) method with the Rayleigh scattering of nitrogen molecules as an absolute standard of scattering cross section. The laser absorption method is incorporated to confirm the result of the LIF measurement. Excitation energies of the measured spectral lines range from 11.6 (Ar I) to 75.6 eV (He II), where the excitation energy is measured from the ground state of the neutral atom on the assumption that, in the plasma of this study, both the neutral and the ionic lines are excited by electron impact in a single-step process from the ground state of the corresponding neutral atoms. Experimental evidence is shown for the validity of this assumption.
Takubo, Y.; Sato, T.; Asaoka, N.; Kusaka, K.; Akiyama, T.; Muroo, K.; Yamamoto, M.
Selective grafting of amine groups on polyethylene by means of NH 3 ?H 2 RF glow discharges
Plasma treatments in Radio Frequency Glow Discharges fed with NH3?H2 mixtures have been performed for modifying polyethylene surfaces. Treatment kinetics and the role of species present in the\\u000a glow have been investigated. Actinometric Optical Emission Spectroscopy has been utilized as a plasma diagnostic technique.\\u000a Electron Spectroscopy for Chemical Analysis has been utilized for studying surface composition of treated substrates, which
Pietro Favia; Marco Vito Stendardo; Riccardo d'Agostino
Fabrication of functionally graded Ti(C, N)-based cermets by double-glow plasma carburization
Functionally graded Ti(C, N)-based cermets were prepared via vacuum liquid sintering and subsequent double-glow plasma carburization. The microstructure was characterized using scanning electron microscope (SEM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). It was found that a surface zone enriched in titanium, molybdenum, tungsten, carbon and nitrogen, deficient in nickel was introduced by double-glow plasma carburization. The high carbon
Zhong Jie; Zheng Yong; Yuan Quan; Zhang Yixin; Yu Lixin
Corrosion resistance properties of glow-discharge nitrided AISI 316L austenitic stainless steel in NaCl solutions
Glow-discharge nitriding treatments can modify the hardness and the corrosion resistance properties of austenitic stainless steels. The modified layer characteristics mainly depend on the treatment temperature. In the present paper the results relative to glow-discharge nitriding treatments carried out on AISI 316L austenitic stainless steel samples at temperatures ranging from 673 to 773K are reported. Treated and untreated samples were
A. Fossati; F. Borgioli; E. Galvanetto; T. Bacci
Abnormal menstruation in malaria: a short review
Malarial infection is an important tropical mosquito borne infectious disease. An important unusual manifestation of malaria\\u000a is the abnormal menstruation. In this brief review, the author will focus on the abnormal menstruation in malarial infection.
Viroj Wiwanitkit
Platelet abnormalities in muscular dystrophy.
Platelets which have complex membranes and calcium shifts similar to those in muscles were investigated in 14 patients with muscular dystrophy and 20 suitable controls. In 4 Duchenne and one limb-girdle dystrophy aggregations were done and found to be depressed with adrenaline and ADP. Electron microscopic and chemical examinations revealed an increased number of dense bodies, changed permeability and/or binding of cations and elevated intracellular calcium in all the 9 cases of Duchenne dystrophy while the 2 limb-girdle and 3 myotonic dystrophies varied. A two phase polymer separation system applied to fixed platelets of all patients and controls showed no abnormality of surface negative charge. PMID:6308847
Yarom, R; Meyer, S; More, R; Liebergall, M; Eldor, A
Foot abnormalities of wild birds
The various foot abnormalities that occur in birds, including pox, scaly-leg, bumble-foot, ergotism and freezing are reviewed. In addition, our findings at the Patuxent Wildlife Research Center include pox from dove, mockingbird, cowbird, grackle and several species of sparrows. Scaly-leg has been particularly prevalent on icterids. Bumble foot has been observed in a whistling swan and in a group of captive woodcock. Ergotism is reported from a series of captive Canada geese from North Dakota. Several drug treatments recommended by others are presented.
Herman, C.M.; Locke, L.N.; Clark, G.M.
Dynamics of an excitable glow-discharge plasma under external forcing.
Glow discharge plasma in the excitable regime shows rich dynamical behavior under external forcing. By perturbing the plasma with a subthreshold sawtooth periodic signal, we obtained small subthreshold oscillations that showed resonance with the perturbation frequency. The resonance phenomenon can be useful to estimate characteristic of an excitable system. However, for suprathreshold perturbation, frequency entrainment was observed. In this case, the system showed harmonic frequency entrainment for the perturbation frequencies greater than the characteristic frequency of the system and the excitable behavior for the perturbation frequencies well below the characteristic frequency. The experiments were performed in a glow-discharge plasma where excitability was achieved at a suitable discharge voltage and gas pressure. PMID:21230566
Nurujjaman; Iyengar, A N Sekar
Evidence for charged defects in intrinsic glow-discharge hydrogenated amorphous-silicon{endash}germanium alloys
We have applied drive-level capacitance profiling, transient photocapacitance, and junction transient photocurrent measurements to characterize the defect-state distribution for a set of device-quality glow-discharge a-Si,Ge:H films. The combination of the latter two methods can distinguish majority- from minority-carrier optical transitions. Comparing the optical spectra of intrinsic samples with those in p-type and n-type samples, we have concluded that significant densities of positively and negatively charged deep defects exist in intrinsic glow-discharge a-Si,Ge:H alloys. Our measurements also indicate how the density of these charged defects increase upon light-induced degradation and how they affect carrier recombination processes. {copyright} {ital 1998} {ital The American Physical Society}
Chen, C.; Zhong, F.; Cohen, J.D. [Department of Physics, University of Oregon, Eugene, Oregon97403 (United States)] [Department of Physics, University of Oregon, Eugene, Oregon97403 (United States); Yang, J.C.; Guha, S. [United Solar Systems Corporation, 1100 West Maple Road, Troy, Michigan48084 (United States)] [United Solar Systems Corporation, 1100 West Maple Road, Troy, Michigan48084 (United States)
OAK A271 COATING AND MANDREL EFFECTS ON FABRICATION OF GLOW DISCHARGE POLYMER NIF SCALE INDIRECT DRIVE CAPSULES. Targets for the National Ignition Facility (NIF) need to be about 200 {micro}m thick and 2 mm in diameter. These dimensions are well beyond those currently fabricated on a routine basis. They have investigated fabrication of near NIF scale targets using the depolymerizable mandrel technique. Poly-alpha-methylstyrene (PAMS) mandrels, about 2 mm in diameter, of varying qualities were coated with as much as 125 {micro}m of glow discharge polymer (GDP). The surface finish of the final shells was examined using a variety of techniques. A clear dependence of the modal spectrum of final GDP shell on the quality of the initial PAMS mandrels was observed. isolated features were found to be the greatest cause for a shell not meeting the NIF standard.
Analysis Of The Different Zones Of Glow Discharge Of Ethyl Alcohol (C2H6O)
The aim of this work is to explore the emission spectroscopy of ethyl alcohol in some regions, also is determine the result elements of the glow discharge, the spectrums were observed in a range of 200 at 1100 nm in the different zones inside of the tube at different distances of 20 and 30 cm. The elements are: in anode region C6H5 (483.02nm), CHO (519.56nm) and H2 (560.47nm), in the positive column CO2+ (315.52 y 337.00nm), O+ (357.48nm), CH+ (380.61nm) and CO+ (399.73nm); in the cathode region we observed O+ (391.19nm), CHOCHO (428.00nm), CO+ (471.12nm) and H2 (656.52nm). C6H5, CHO y H2 species occurring in all regions analyzed varying the glow discharge emission intensity.
Torres, C.; Reyes, P. G.; Mulia, J.; Castillo, F.; Mart�nez, H.
An Inertial Electrostatic Confinement Fusion device is a very simple and safe neutron source that uses a glow discharge for deuterium-deuterium fusion. The discharge characteristics of the device were studied experimentally. The relationship between gas pressure and applied voltage was examined by light changes of the device's anode size. The gas pressure ranges in which the device was able to function effectively were differed. In the case of a larger anode (300 mm in diameter), the glow discharge occurred even under a relatively low pressure of 0.7 Pa and was very stable during a long period of neutron production. The characteristics of the gas pressure-neutron yield of different size anodes were also studied experimentally. At lower gas pressure, a greater neutron yield was obtained by a larger anode.
Osawa, Hodaka; Yoshimura, Shigehisa; Tabata, Takehiro; Ohnishi, Masami
Boundary Layer Flow Control with a One Atmosphere Uniform Glow Discharge Surface Plasma
Low speed wind tunnel data have been acquired for planar panels covered by a uniform, glow-discharge surface plasma in atmospheric pressure air known as the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). Streamwise and spanwise arrays of flush, plasma-generating surface electrodes have been studied in laminar, transitional, and fully turbulent boundary layer flow. Plasma between symmetric streamwise electrode strips caused large increases in panel drag, whereas asymmetric spanwise electrode configurations produced a significant thrust. Smoke wire flow visualization and mean velocity diagnostics show the primary cause of the phenomena to be a combination of mass transport and vortical structures induced by strong paraelectric ElectroHydroDynamic (EHD) body forces on the flow.
Roth, J. Reece; Sherman, Daniel M.; Wilkinson, Stephen P.
Microdischarge-assisted ignition of dielectric-barrier high-pressure glow discharges
The ignition characteristics of dielectric-barrier high-pressure glow (DB-HPG) discharges in the presence of dc microdischarges are studied for pure helium and pure nitrogen working gases. In the presence of an array of microdischarges integrated with one of the DB-HPG electrodes, a substantial reduction of DB-HPG ignition voltage is observed for both working gases. The discharge structure within the DB-HPG volume gap is localized near the microdischarge holes when the DB-HPG first turns on in the presence of microdischarges, but subsequently expands to cover the entire volume at higher voltages for the pressures studied. The helium discharge is generally more uniform than the nitrogen gas. Our studies indicate that the localized discharge has a glow-like character rather than a Townsend- or streamer-like one.
Shin Jichul; Raja, Laxminarayan L. [Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, Texas 78712 (United States)
A self-consistent particle model for the simulation of RF glow discharges
This paper reports on a self-consistent particle model of an argon RF glow discharge that has been developed. Electric field and charged-particle density profiles determined from simulations with the RF glow discharge model are consistent with results obtained from continuum models. The average ion energy is found to vary greatly between the bulk of the discharge and sheaths, contrary to the assumption that the ion energy is uniform, as is assumed in some continuum models. The accuracy of the particle cross sections and collision representation used in the model is verified with a simplified dc model which calculates swarm parameters. Electron swarm parameters determined with this model are in excellent agreement with experimental data taken from the literature.
Trombley, H.W.; Terry, F.L. Jr.; Elta, M.E. (Michigan Univ., Ann Arbor, MI (United States). Dept. of Electrical Engineering and Computer Science)
Attenuation of single-tone ultrasound by an atmospheric glow discharge plasma barrier
Propagation of 143 kHz ultrasound through an atmospheric pressure glow discharge in air was studied experimentally. The plasma was a continuous dc discharge formed by a multipin electrode system. Distributions of the gas temperature were also obtained in and around the plasma using laser-induced Rayleigh scattering technique. Results show significant attenuation of the ultrasound by the glow discharge plasma barrier (up to -24 dB). The results indicate that sound attenuation does not depend on the thickness of the plasma and attenuation is caused primarily by reflection of the sound waves from the plasma due to the sharp gas temperatures gradients that form at the plasma boundary. These gradients can be as high as 80 K/mm.
Stepaniuk, Vadim P. [Lenterra Inc., 7 Tenney Road, West Orange, New Jersey 07052 (United States); Ioppolo, Tindaro; Oetuegen, M. Volkan [Southern Methodist University, 3101 Dyer Street, Dallas, Texas 75205 (United States); Sheverev, Valery A. [Lenterra Inc., 7 Tenney Road, West Orange, New Jersey 07052 (United States); Polytechnic Institute of NYU, 6 Metrotech Center, Brooklyn, New York 11201 (United States)
Comparison of different fluid models for the atmospheric pressure DC glow microdischarge in helium
One- and two-dimensional self-consistent fluid simulations of a DC microdischarge in helium at atmospheric pressure were performed. The plasmachemical model used includes five atomic and two molecular excited levels of helium and more than 80 reactions between them. Comparison of simulation results obtained by using this reaction set both with approach of Maxwellian and non-Maxwellian EDF with results from previous papers is presented. Simulations predict main observed properties of DC glow discharge, including formation of the normal current density when discharge occupies only part of cathode (the normal glow discharge). Gas heating was found to play an important role in shaping discharge profiles both in the cathode sheath and plasmas. Basic plasma properties such as density of charged and excited particles, electron and gas temperatures, electric field profiles etc. appeared to depend on choice of reaction set and EDF shape.
Kudryavtsev, Anatoly; Bogdanov, Eugene; Kapustin, Kirill; Chirtsov, Alexander
Characteristics of a Normal Glow Discharge Excited by DC Voltage in Atmospheric Pressure Air
Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the current-voltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.
Li, Xuechen; Zhao, Huanhuan; Jia, Pengying
The impact of light source spectral power distribution on sky glow
The effect of light source spectral power distribution on the visual brightness of anthropogenic sky glow is described. Under visual adaptation levels relevant to observing the night sky, namely with dark-adapted (scotopic) vision, blue-rich ("white") sources produce a dramatically greater sky brightness than yellow-rich sources. High correlated color temperature LEDs and metal halide sources produce a visual brightness up to 8� brighter than low-pressure sodium and 3� brighter than high-pressure sodium when matched lumen-for-lumen and observed nearby. Though the sky brightness arising from blue-rich sources decreases more strongly with distance, the visual sky glow resulting from such sources remains significantly brighter than from yellow sources out to the limits of this study at 300 km.
Luginbuhl, Christian B.; Boley, Paul A.; Davis, Donald R.
Surface modification of PDMS using atmospheric glow discharge polymerization of tetrafluoroethane for immobilization of biomolecules
In this study an atmospheric glow discharge with a fluorocarbon gas as precursor was used to modify the surface of polydimethyl siloxane (PDMS -[(CH 3) 2SiO] n-). The variation in protein immobilizing capability of PDMS was studied for different times of exposure. It was observed that the concentration of proteins adsorbed on the surface varied in an irregular manner with treatment time. The fluorination results in the formation of a thin film of fluorocarbon on the PDMS surface. The AFM and XPS data suggest that the film cracks due to stress and regains its uniformity thereafter. This Stranski-Krastanov growth model of the film was due to the high growth rate offered by atmospheric glow discharge.
Anand, V.; Ghosh, S.; Ghosh, M.; Rao, G. M.; Railkar, R.; Dighe, R. R.
SkyGlowNet: Multi-Disciplinary Independent Student Research in Environmental Light at Night Monitoring
SkyGlowNet uses Internet-enabled sky brightness meters (iSBM) to monitor sky brightness over school sites. The data are used professionally and in STEM outreach to study natural and artificial sources of sky brightness, light pollution, energy efficiency, and environmental and health impacts of artificial night lighting. The iSBM units are owned by participating institutions and managed by faculty or students via proprietary Internet links. Student data are embargoed for two semesters to allow students to analyze data and publish results, then they are moved to a common area where students from different institutions can collaborate. The iSBM units can be set to operate automatically each night. Their data include time, sky brightness, weather conditions, and other related parameters. The data stream can be viewed and processed online or downloaded for study. SkyGlowNet is a unique, multi-disciplinary, real science program aiding research for science and non-science students.
Craine, B. L.; Craine, E. R.; Culver, R. B.; DeBenedetti, J. C.; Flurchick, K. M.
Fading prediction in thermoluminescent materials using computerised glow curve deconvolution (CGCD)
The fading of three different thermoluminescent (TL) materials, CaF 2 : Tm (TLD-300), manocrystalline LiF : Mg,Ti (DTG-4) and MgB 4O 7 : Dy,Na has been studied at room temperature and at 50�C of storage. The evolution as a function of the elapsed time of the whole glow curve as well as of the individual peaks has been analysed using the Computerised Glow Curve Deconvolution (CGCD) program developed at the NTHU. The analysis allows to predict the loss of the dosimetric information and to make any correction is necessary for using the TL dosimeters in practical applications. Furthermore, it is well demonstrated that using CGCD it is not necessary to anneal the peaks having a rapid fading to avoid, then, any interfering effect on the more stable peaks.
Furetta, C.; Kuo, C. H.; Weng, P. S.
Plasma Treatment of Polyethylene Powder Particles in Hollow Cathode Glow Discharge
Polyethylen (PE) is widely used in the production of foils, insulators, packaging materials, plastic bottles etc. Untreated PE is hydrophobic due to its unpolar surface. Therefore, it is hard to print or glue PE and the surface has to be modified before converting.In the present experiments a hollow cathode glow discharge is used as plasma source which is mounted in a spiral conveyor in order to ensure a combines transport of PE powder particles. With this set-up a homogeneous surface treatment of the powder is possible while passing the glow discharge. The plasma treatment causes a remarkable enhancement of the hydrophilicity of the PE powder which can be verified by contact angle measurements and X-ray photoelectron spectroscopy.
Wolter, Matthias; Quitzau, Meike; Bornholdt, Sven; Kersten, Holger [IEAP, University Kiel, Kiel (Germany)
Asynchronous cycling as a convergence acceleration method in particle simulation of direct current glow discharges
The problem of multiple time scales in modeling plasmas by dynamical particle simulation methods, such as the particle-in-cell (PIC) method, is well known. One important cause is the large ratio of the ion and electron mass. Ways to overcome this problem are the implicit PIC, or simply, the use of a reduced ion{endash}electron mass ratio. However, these methods are not acceptable in modeling dc glow discharges by the PIC-Monte Carlo hybrid simulation technique. Therefore, a new method called {ital asynchronous cycling} was developed, which manipulates the synchronization of the electron and ion simulation cycles. It allows a 50 times faster convergence due to direct reduction of the different time scales for situations in which the changes of macroscopic quantities are slower than the ion movement. This is demonstrated by the modeling of a complete one-dimensional dc glow discharge including cathode fall, plasma bulk, and anode fall. {copyright} {ital 1997 American Institute of Physics.}
Meyer, P.; Wunner, G. [Lehrstuhl fuer Theoretische Physik I, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)] [Lehrstuhl fuer Theoretische Physik I, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)
Differentiation of Chinese liquors by using ambient glow discharge ionization mass spectrometry.
Chinese liquors are often a very important part of social event in China. Driven by high profit, some illegal traders often use inferior liquors instead of the products with high quality to cheat the customer. Therefore, it is highly required to authenticate Chinese liquors. In this paper a novel method based on ambient glow discharge ionization mass spectrometry has been developed to differentiate Chinese liquors. Volatile components from liquor samples were ionized by the plasma generated by glow discharge and then detected by a commercial linear ion trap mass spectrometer. Consequently, the fingerprint mass spectra of several Chinese liquors were obtained. Combined with principal component analysis, this new method was successfully applied to differentiate different brands of Chinese liquors without any sample pretreatment. Compared with conventional methods, this novel method has the advantages of easy operation, high speed, and high efficiency, which make it a potential tool in the fields of food safety, atmosphere chemistry. PMID:23689281
Zhen, Cheng; Zhou, Yueming; Zhang, Ning; Wang, Jiyun; Xiong, Caiqiao; Chen, Suming; Nie, Zongxiu
Very high resolution laser saturation spectroscopy in hollow-cathode and glow discharges
Doppler-free laser saturation measurements on a wide range of atomic systems demonstrate that very narrow lines, having observed widths of typically 6-10 MHz FWHM and actual homogeneous widths of 3-5 MHz, can be readily attained in a low-pressure hollow-cathode or glow discharge, provided natural broadening due to the finite lifetimes of the levels is small. The measurements also demonstrate that
D. S. Gough; P. Hannaford
Evidence for charged defects in intrinsic glow-discharge hydrogenated amorphous-silicon-germanium alloys
We have applied drive-level capacitance profiling, transient photocapacitance, and junction transient photocurrent measurements to characterize the defect-state distribution for a set of device-quality glow-discharge a-Si,Ge:H films. The combination of the latter two methods can distinguish majority- from minority-carrier optical transitions. Comparing the optical spectra of intrinsic samples with those in p-type and n-type samples, we have concluded that significant densities
Chih-Chiang Chen; Fan Zhong; J. David Cohen; Jeffrey C. Yang; Subhendu Guha
High frequency glow discharges at atmospheric pressure with micro-structured electrode arrays
Micro-structured electrode (MSE) arrays allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode widths, thicknesses and distances in the micrometre range are realized by means of modern micro-machining and galvanic techniques. The electrode distance, the gap width d, is small enough to generate sufficiently high electric field strengths to ignite
L. Baars-Hibbe; P. Sichler; C. Schrader; N. Lucas; K.-H. Gericke; S. B�ttgenbach
Optical sensing properties of CoTPP thin films deposited by glow-discharge-induced sublimation
Thin porphyrin assemblies, widely used as sensing materials in different kinds of transducers, are usually produced through chemical deposition techniques. In this work a new physical technique named glow-discharge-induced sublimation (GDS) has been employed for the production of cobalt 5,10,15,20 meso-tetraphenyl porphyrin (CoTPP) thin films. For comparison, CoTPP coatings have been also produced by vacuum evaporation and spin coating procedures.
M. Tonezzer; G. Maggioni; A. Quaranta; S. Carturan; G. Della Mea
Surface Modification of Commercial Low-Carbon Steel using Glow Discharge Nitrogen Plasma and its Characterization
Plasma nitriding under glow discharge nitrogen plasma has been undertaken on laboratory scale for surface engineering of commercial low carbon steels. The treatment has been shown to confer exceptional improvement in surface properties, viz., hardness and corrosion resistance. The results have been discussed in light of microstructural changes occurring on steel surface and its interior as a result of Fickian nitrogen diffusion and correlated with influences of nitriding-temperature and alloying elements (Mn, Nb, and Si) in steel.
Srikanth, S.; Saravanan, P.; Joseph, Alphonsa; Ravi, K.
Submicronic etching of borophosphosilicate glass using NF 3 and NF 3\\/He radio frequency glow discharge
The etching of borophosphosilicate glass (BPSG) in NF3 and NF3\\/He radio frequency (RF) glow discharge has been characterized. The etch rates, BPSG\\/resist selectivity and etch profile have been investigated along with the reactor geometry, namely the inter electrode distance, by which the process can be optimized. The results shows that the etch rates of BPSG are 650 nm\\/min at RF
N. Mekkakia Maaza; A. Boudghene Stambouli
Microstructure of thin iron carbide films prepared in a glow discharge
Thin (50�80 nm) iron carbide films were grown on carbon-coated copper grids in an r.f. glow discharge using iron pentacarbonyl and hydrogen as starting materials. The substrate temperatures were varied in the range 200�500 �C. The microstructure and phases present in these films are compared with the corresponding results previously obtained by X-ray diffraction, atomic force microscopy, scanning electron microscopy
H. Siriwardane; O. A. Pringle; J. W. Newkirk; W. J. James
Producing a Radioactive Source in a Deuterated Palladium Electrode Under Direct-Current Glow Discharge
Anomalous gamma emission was rarely observed during direct-current glow discharge in {approx}3 Torrs of deuterium gas using a deuterated palladium foil cathode. Autoradiography after the discharge experiment showed that isotopes with low- and high-energy radiation components were produced before or during the discharge. The palladium foil after the anomalous gamma-ray emission was analyzed by secondary ion mass spectroscopy, which revealed a considerable increase in the content of iron and copper on the surface.
Yamada, Hiroshi; Uchiyama, Kazuyoshi; Kawata, Nobuhiko; Kurisawa, Yoshiyuki; Nakamura, Mitsuru
Microstructure and stress in nano-crystalline diamond films deposited by DC glow discharge CVD
Direct current glow discharge (DC GD) CVD from a methane�hydrogen mixture enables deposition of a nano-crystalline carbon film of a prevailing diamond character on a pristine silicon substrate without any surface pretreatment. The deposited films were investigated by various techniques including: X-ray diffraction (XRD); high resolution transmission electron microscopy (HR TEM); and Raman spectroscopy. From the XRD analysis, development of
A. Heiman; E. Lakin; E. Zolotoyabko; A. Hoffman
Computational study of capacitively coupled high-pressure glow discharges in helium
The structure of a capacitively coupled high-pressure glow (HPG) discharge in high-purity helium is investigated using a detailed one-dimensional modeling approach. Impurity effects are modeled using trace amounts of nitrogen gas in helium. Average electron temperatures and densities for the HPG discharge are similar to their low-pressure counterpart. Helium-dimer ions dominate the discharge structure for sufficiently high-current densities, but model
Xiaohui Yuan; Laxminarayan L. Raja
Two-component plasma model for two-dimensional glow discharge in magnetic field
Theory and computational model for a glow discharge in a parallel-plate configuration with an applied transversal magnetic field is presented. The model is based on the diffusion-drift theory of gas discharge consisting of continuity and momentum conservation equations for electron and ion fluids, as well as the Poisson equation for the self-consistent electric field. Two-dimensional numerical results are obtained for
Sergey T. Surzhikov; Joseph S. Shang
Depigmented atrophic lesions in sunset glow fundi of Vogt-Koyanagi-Harada Disease
PURPOSE: Although the depigmented, small, round to oval lesions seen in the sunset glow fundi of Vogt-Koyanagi-Harada disease are considered to represent Dal�n-Fuchs nodules, there is no histopathologic evidence to support such a consideration. An attempt is made herein to clarify the nature of the atrophic lesions and distinguish them from Dal�n-Fuchs nodules seen in eyes with Vogt-Koyanagi-Harada disease.METHODS: Eyes
Hajime Inomata; Narsing A Rao
Oxygen-bonding environments in glow-discharge-deposited amorphous silicon-hydrogen alloy films
This paper presents the results of a systematic study of oxygen incorporation in a-Si:H alloys produced by the glow-discharge decomposition of SiH4, H2, and O2. We identify four oxygen-related absorption bands, at 2090, 980, 780, 500 cm-1, and show that the absorption strength in each band scales linearly with the oxygen concentration. We demonstrate that oxygen can increase the solubility
G. Lucovsky; J. Yang; S. S. Chao; J. E. Tyler; W. Czubatyj
Frequency and voltage dependence of glow and pseudoglow discharges in helium under atmospheric pressure
The pseudoglow and glow discharge behavior of a 0.5-mm metallic-dielectric electrode gap in helium under atmospheric pressure was examined as a function of ac voltage between 0.3 and 32 kHz. The number of discharge current pulses per half-cycle within the pseudoglow was found to diminish with rising frequency, as opposed to the increase observed with rising voltage. The reduction in
Ion Radu; Ray Bartnikas; Michael R. Wertheimer
Electron-impact and glow-discharge ionization LC�MS analysis of green tea tincture
A liquid chromatography�particle-beam mass spectrometer (LC�PB\\/MS) with interchangeable electron-impact (EI) and glow-discharge\\u000a (GD) ion sources was evaluated for future application in analysis of botanical extracts. In this work a green tea tincture\\u000a was characterized for a series of catechin components (catechin, epicatechin, epigallocatechin, and epigallocatechin gallate\\u000a (EGCG)) and caffeine. Special emphasis was given to EGCG and caffeine, because they are
Jacob L. Venzie; Joaudimir Castro; M. V. Balarama Krishna; Dwella M. Nelson; R. Kenneth Marcus
Spatial distribution of the neutral carboneous compounds glow in the sunward Halley comet coma
This work presents a study of the C2, C3, CH, and CN glow in the Halley�s coma in sunward direction. For that purpose, 1035 spectra in the near UV and visible region registered by the Three-Channel Spectrometer (TKS) on board Vega-2 station on 9 March 1986 are used. An improved method of the dust continuum extraction in the visible region
V. Guineva; R. Werner; P. Stoeva; I. Kostadinov
Comparative Study of Electric Field Measurement in Glow Discharges using Laser Optogalvanic Spectroscopy
The net electric field inside low-pressure glow discharges has been measured using laser optogalvanic spectroscopy of 1s2s 1S0-->np1P1 Rydberg series of atomic helium. Three different types of discharges, an inductively coupled RF discharge cell operating at 4 MHz, a homemade DC discharge cell and a commercial see-through hollow cathode lamp have been used for these studies. The Rydberg series terminates
Shahid Hussain; M. Saleem; M. A. Baig
Physics Of The Plasma-Cathode Interface Of Glow Discharge In Oxygen With Aluminium Cathode
Glow discharge in oxygen with aluminium cathode has peculiar characteristics. It works at the product (p.Lcf) of gas pressure and the cathode space length, smaller than in other cases, e.g. even Ne\\/Al discharge. Numerical modelling of electrodynamic structure of the cathode region suggests low multiplication of electron fluxes and consequently high electron emission from the ``oxidised'' cathode surface at relatively
Z. Wronski
Charge formation in polyimide films under the action of low-frequency glow-discharge plasma
The authors showed previously that treatment of the surface of PM polyimide films (produced in Russia) with a low-frequency (LF) glow-discharge plasma resulted in considerable changes in their wettability and surface energy. Similar results were also obtained abroad for Kapton films. It was shown that the formation of polar NH and OH groups (in unbound carboxyl groups) occurred in the surface layer as a result of decyclization processes. In addition, the concentration of free radicals was shown to increase. These changes in chemical structure are probably responsible for increasing the hydrophilicity of the surface of polyimide films. However, estimations showed that the concentrations of free radicals were comparatively low. Apparently, the significant changes of the polar component of the surface energy that were observed (by 2-3 orders of magnitude) cannot be fully explained by the formation of radicals. The study of the effect of LF glow discharge on polytetrafluoroethylene revealed an essential decrease of the contact angles on the film surface and formation of the surface electric charge. It was shown that the neutralization of this charge resulted in increased contact angles for polytetrafluoroethylene nearly up to the values for the original films. Thus, the charged (or electret) states appear to play an important part in modifying the energetic characteristics of the film surface in the case of polytetrafluoroethylene. Similar states may also result from the glow-discharge treatment of polyimide and play a certain part in modifying the surface characteristics of this polymer. In this work the authors carried out measurements of the charge generated in polyimide films modified with glow discharge and investigated the mechanism of charge accumulation in the samples.
Drachev, A.I.; Gil`man, A.B.; Tuzov, L.S.; Potapov, V.K. [Karpov Institute of Physical Chemistry, Moscow (Russian Federation)
Defect Structure of Glow Peak 1 in LiF:Mg,Ti (TLD-100)
The possible defect structure of peak 1 of LiF:Mg,Ti (TLD-100) was studied in the present work after different pre-irradiation heat treatments between 80�C and 150�C using the computer glow curve deconvolution (CGCD) method. It was shown that the defect structure of peak 1 is based on colloid centers, Ti+4-3O2--mixed centers and U1-centers.
Yazici, A. Necmedd�n
Inhibition of monocyte adhesion and fibrinogen adsorption on glow discharge plasma deposited tetraethylene glycol dimethyl ether
Monocytes and macrophages play important roles in host responses to implanted biomedical devices. Monocyte and macrophage interactions with biomaterial surfaces are thought to be mediated by adsorbed adhesive proteins such as fibrinogen and fibronectin. Non-fouling surfaces that minimize protein adsorption may therefore minimize monocyte adhesion, activation, and the foreign body response. Radio-frequency glow discharge plasma deposition (RF-GDPD) of tetraethylene glycol
Mingchao Shen; Y. Vickie Pan; Matthew S. Wagner; Kip D. Hauch; David G. Castner; Buddy D. Ratner; Thomas A. Horbett
[New design of Grimm-type glow discharge source for real-time sputtered depth measurement].
The crater depth value of sample surface during sputtering is important analysis information for the depth profile analysis of glow discharge spectrometry. Real-time sputtered depth measurement with Laser triangulation measurement method for glow discharge compositional analysis, effectively solves the issues of incorrect depth value calculation and complicated procedures in traditional depth analysis method. This paper presents a new Grimm-type glow discharge source for real-time sputtering depth measurement by laser displacement sensor. This GD source also ensures fine sputtering effects and ideal resolution for multi-layer structure and interface. Optical fiber is used to transmit glow spectrum signal from GD-source to multi-channel photoelectric detection system. The design for the first time accomplishes the real-time signal collection and time-based synchronization analysis for both spectrum signal and sputtering depth signal. The real-time sputtering depth measurement curve of standard samples is obtained. The design and operating principle of this new-type GD-source is described in detail. Under the sputtering conditions of 30 mA, 900 V and 20 minutes, the sputtering rates of iron-based and copper-based sample sputtered by this GD source with good depth resolution are about 10 and 55 nm x s(-1). Surface topography picture of sputtering crater and microphotograph of metal samples are provided in the paper. Low-alloy steel standard sample is tested with this new GD source, the relative standard deviation (RSD) of C, Cu, Al, Ni, Mo, Mn and V elements are less than 1.7%, while for Cr and Si elements RSDs are less than 2.6%. The result data of the testing is provided in this paper. PMID:21714279
Wan, Zhen-Zhen; Li, Xiao-Jia; Wang, Yong-Qing; Sun, Rong-Xia; Shi, Ning
Atmospheric pressure glow discharge desorption mass spectrometry for rapid screening of pesticides in food
Flowing afterglow atmospheric pressure glow discharge tandem mass spectrometry (APGD-MS\\/MS) is used for the analysis of trace amounts of pesticides in fruit juices and on fruit peel. The APGD source was rebuilt after Andradeet al. (Andradeetal.,Anal.Chem. 2008; 80: 2646-2653; 2654-2663) and mounted onto a hybrid quadrupole time-of-flight mass spectrometer. Apple, cranberry, grape and orange juices as well as fruit peel
Matthias Conradin Jecklin; Gerardo Gamez; David Touboul; Renato Zenobi
Aqueous 4-nitrophenol decomposition and hydrogen peroxide formation induced by contact glow discharge electrolysis
Liquid-phase decomposition of 4-nitrophenol (4-NP) and formation of hydrogen peroxide (H2O2) induced by contact glow discharge electrolysis (CGDE) were investigated. Experimental results showed that the decays of 4-NP and total organic carbon (TOC) obeyed the first-order and pseudo-first-order reaction kinetics, respectively. The major intermediate products were 4-nitrocatechol, hydroquinone, benzoquinone, hydroxyhydroquinone, organic acids and nitrite ion. The final products were carbon
Yongjun Liu; Degao Wang; Bing Sun; Xiaomei Zhu
Inheritance of abnormal erythrocyte cation transport in essential hypertension.
Net fluxes of sodium and potassium ions were determined in sodium-loaded, potassium-depleted erythrocytes from 370 white subjects, 194 of whom had essential hypertension or had been born to parents with essential hypertension. Findings were compared with those in 86 controls who were normotensive and did not have a family history of hypertension. Compared with controls all patients with essential hypertension had a low sodium to potassium ratio secondary to a deficit in the sodium-potassium cotransport system. A similar abnormality was found in subjects born to parents with essential hypertension, the prevalences of a deficient cotransport system in such subjects being 53.6% (52 out of 97) among those with one hypertensive parent and 73.7% (14 out of 19) among those with two hypertensive parents. Both sexes were equally affected. Studies in 14 families over two or three generations showed the erythrocyte cation abnormality in one or more members of each consecutive generation. No close association was evident between the deficient erythrocyte sodium-potassium cotransport system and either blood groups ABO, Rh, Kidd, Duffy, P, and MNS or the major histocompatibility HLA antigens. Out of 90 consecutive unrelated and normotensive white blood donors, 36 showed a low erythrocyte sodium-potassium net flux ratio. It is concluded that in white people abnormal erythrocyte cation transport is a biochemical disorder characteristic of essential hypertension and transmitted by a dominant and autosomal mode expressing a single abnormal gene. PMID:6786458
Meyer, P; Garay, R P; Nazaret, C; Dagher, G; Bellet, M; Broyer, M; Feingold, J
Net fluxes of sodium and potassium ions were determined in sodium-loaded, potassium-depleted erythrocytes from 370 white subjects, 194 of whom had essential hypertension or had been born to parents with essential hypertension. Findings were compared with those in 86 controls who were normotensive and did not have a family history of hypertension. Compared with controls all patients with essential hypertension had a low sodium to potassium ratio secondary to a deficit in the sodium-potassium cotransport system. A similar abnormality was found in subjects born to parents with essential hypertension, the prevalences of a deficient cotransport system in such subjects being 53.6% (52 out of 97) among those with one hypertensive parent and 73.7% (14 out of 19) among those with two hypertensive parents. Both sexes were equally affected. Studies in 14 families over two or three generations showed the erythrocyte cation abnormality in one or more members of each consecutive generation. No close association was evident between the deficient erythrocyte sodium-potassium cotransport system and either blood groups ABO, Rh, Kidd, Duffy, P, and MNS or the major histocompatibility HLA antigens. Out of 90 consecutive unrelated and normotensive white blood donors, 36 showed a low erythrocyte sodium-potassium net flux ratio. It is concluded that in white people abnormal erythrocyte cation transport is a biochemical disorder characteristic of essential hypertension and transmitted by a dominant and autosomal mode expressing a single abnormal gene.
[Measurement and analysis of discharge current in dielectric barrier glow discharge at atmospheric pressure].
Dielectric barrier discharge has become a hot issue in low temperature plasma research field because of wide prospect for its application in industry. In the present paper, an uniform glow discharge was realized in atmospheric pressure helium with a parallel planar dielectric barrier discharge device and an uniform plasma was generated in helium at atmospheric pressure. Electrical method was used to separate the discharge current from the total current signal and the waveform of discharge current could be obtained. The relations among the discharge current, applied voltage, gap voltage and wall charge during the uniform glow discharge were used to analyze the dynamical behavior of wall charges during their accumulation. The results show that the wall charges were mainly accumulated during the existence of discharge current pulse, while the quantity of wall charges continued to increase until the gap voltage changed its polarity after the disappearance of discharge current pulse, and finally the quantity of wall charges decreased until the next breakdown. These experimental results are important for the further study of wall charges' effect in the dielectric barrier glow discharge and its application in industry. PMID:18330271
Li, Xue-chen; Yin, Zeng-qian; Pang, Xue-xia; Li, Yong-hui; Gao, Rui-ling
The role of electronic mechanisms in surface erosion and glow phenomena
Experimental studies of desorption induced by electronic transitions (DIET) are described. Such studies are producing an increasingly complete picture of the dynamical pathways through which incident electronic energy is absorbed and rechanneled to produce macroscopic erosion and glow. These mechanistic studies can determine rate constants for erosion and glow processes in model materials and provide valuable guidance in materials selection and development. Extensive experiments with electron, photon, and heavy particle irradiation of alkali halides and other simple model materials have produced evidence showing that: (1) surface erosion, consisting primarily in the ejection or desorption of ground-state neutral atoms, occurs with large efficiencies for all irradiated species; (2) surface glow, resulting from the radiative decay of desorbed atoms, likewise occurs for all irradiating species; (3) the typical mechanism for ground-state neutral desorption is exciton formation, followed by relaxation to a permanent, mobile electronic defect which is the precursor to bond-breaking in the surface or near-surface bulk of the material; and (4) the mechanisms for excited atom formation may include curve crossing in atomic collisions, interactions with surface defect or impurity states, or defect diffusion.
Haglund, Richard F., Jr.
Mechanism behind self-sustained oscillations in direct current glow discharges and dusty plasmas
An alternative explanation to the mechanism behind self-sustained oscillations of ions in direct current (DC) glow discharges is provided. Such description is distinguished from the one provided by the fluid models, where oscillations are attributed to the positive feedback mechanism associated with photoionization of particles and photoemission of electrons from the cathode. Here, oscillations arise as consequence of interaction between an ion and the surface charges induced by it at the bounding electrodes. Such mechanism provides an elegant explanation to why self-sustained oscillations occur only in the negative resistance region of the voltage-current characteristic curve in the DC glow discharges. Furthermore, this alternative description provides an elegant explanation to the formation of plasma fireballs in the laboratory plasma. It has been found that oscillation frequencies increase with ion's surface charge density, but at the rate which is significantly slower than it does with the electric field. The presented mechanism also describes self-sustained oscillations of ions in dusty plasmas, which demonstrates that self-sustained oscillations in dusty plasmas and DC glow discharges involve common physical processes.
Cho, Sung Nae [Devices R and D Center, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., Mt. 14-1 Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of)
Atmospheric pressure glow discharge deposition of thermo-sensitive poly (N-isopropylacrylamide)
In this paper, a self-made atmospheric pressure dielectric barrier discharge reactor on intermediate frequency is brought forward and developed, which is equipped with power supply of 1-20 KHz, and the working gas is argon. The experimental results show that is a very stable and uniform atmospheric pressure glow discharge (APGD). Through a series of experiments, the waveforms of single pulse and multi-pulse glow discharge were both obtained. The voltage amplitude, discharge gap and dielectric material are studied, and the conditions of multi-pulse glow discharge are discussed as well. The novel methods of depositing poly (N-isopropylacrylamide) (PNIPAAm) coatings on the surface of glass slides and PS petri dish are provided by atmospheric pressure plasma polymerization. PNIPAAm can be obtained by plasma polymerization of N-isopropylacrylamide using the self-made equipment of atmospheric pressure plasma vapor treatment. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. SEM analysis has revealed that the PNIPAAm coatings were formed on the surface of the smooth glass slides. Further evaluation by using XPS, it has shown the presence of PNIPAAm. The wettability can be significantly modified by changing of the temperatures at above and below of the lower critical solution temperature (LCST) from the data of the contact angle test. These results have advantage for further application on the thermo-sensitive textile materials.
Shao, M.; Tang, X. L.; Wen, D.; Chen, Y.; Qiu, G.
A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning
Hydrogen- and deuterium-fueled glow discharges are used for the initial conditioning of magnetic fusion device vacuum vessels following evacuation from atmospheric pressure. Hydrogenic glow discharge conditioning (GDC) significantly reduces the near-surface concentration of simple adsorbates, such as H/sub 2/O, CO, and CH/sub 4/, and lowers ion-induced desorption coefficients by typically three orders of magnitude. The time evolution of the residual gas production observed during hydrogen-glow discharge conditioning of the carbon first-wall structure of the TFTR device is similar to the time evolution observed during hydrogen GDC of the initial first-wall configuration in TFTR, which was primarily stainless steel. Recently, helium GDC has been investigated for several wall-conditioning tasks on a number of tokamaks including TFTR. Helium GDC shows negligible impurity removal with stainless steel walls. For impurity conditioning with carbon walls, helium GDC shows significant desorption of H/sub 2/O, CO, and CO/sub 2/; however, the total desorption yield is limited to the monolayer range. In addition, helium GDC can be used to displace hydrogen isotopes from the near-surface region of carbon first-walls in order to lower hydrogenic retention and recycling. 38 refs., 6 figs.
Dylla, H.F.
Hydrogen absorption behavior into boron films deposited on graphite and stainless steel (SS) has been studied. Hydrogen absorption into a H-depleted boron film was investigated during a hydrogen glow discharge with pressure drop measured by a diaphragm gauge. It was found that, after strong but short time absorption at initial phase, hydrogen atoms were slowly (a few percents of injected H atoms) but continuously absorbed without saturation up to 3 h, which was not observed with SS liner without boron coating. Hydrogen atoms were not only desorbed but also implanted into the film during a helium glow discharge and thus, hydrogen atoms were accumulated in the film when H 2 and He discharges were repeated alternately. These accumulation effects enhanced by ions from the glow discharge were investigated quantitatively and the effect of bombarding ion species (H + or He +) was discussed. Depth profile of H atoms was measured by elastic recoil detection (ERD). The density of only near surface region was increased when the hydrogen atoms were injected. Longer time exposure to H 2 discharge resulted in increase in surface density and shift of the peak position to deeper into the film. These results were explained by diffusion of H atoms due to ion impact into the films with keeping its saturation level if we consider resolution of ERD method of 25 nm. From the results, applicability of boron film as protection layer of tritium permeation is discussed.
Tsuzuki, K.; Natsir, M.; Inoue, N.; Sagara, A.; Noda, N.; Motojima, O.; Mochizuki, T.; Hino, T.; Yamashina, T.
Hydrogen- and deuterium-fueled glow discharges are used for the initial conditioning of magnetic fusion device vacuum vessels following evacuation from atmospheric pressure. Hydrogenic glow discharge conditioning (GDC) significantly reduces the near-surface concentration of simple adsorbates such as H2O, CO, and CH4, and lowers ion-induced desorption coefficients by typically three orders of magnitude. The time evolution of the residual gas production observed during hydrogen-glow discharge conditioning of the carbon first-wall structure of the TFTR device is similar to the time evolution observed during hydrogen GDC of the initial first-wall configuration in TFTR, which was primarily stainless steel. Recently, helium GDC has been investigated for several wall-conditioning tasks on a number of tokamaks including TFTR. Helium GDC shows negligible impurity removal with stainless steel walls. For impurity conditioning with carbon walls, helium GDC shows significant desorption of H2O, CO, and CO2; however, the total desorption yield is limited to the monolayer range. In addition, helium GDC can be used to displace hydrogen isotopes from the near-surface region of carbon first-walls in order to lower hydrogenic retention and recycling.
Dylla, H. F.
Disorders caused by chromosome abnormalities
Many human genetic disorders result from unbalanced chromosome abnormalities, in which there is a net gain or loss of genetic material. Such imbalances often disrupt large numbers of dosage-sensitive, developmentally important genes and result in specific and complex phenotypes. Alternately, some chromosomal syndromes may be caused by a deletion or duplication of a single gene with pleiotropic effects. Traditionally, chromosome abnormalities were identified by visual inspection of the chromosomes under a microscope. The use of molecular cytogenetic technologies, such as fluorescence in situ hybridization and microarrays, has allowed for the identification of cryptic or submicroscopic imbalances, which are not visible under the light microscope. Microarrays have allowed for the identification of numerous new syndromes through a genotype-first approach in which patients with the same or overlapping genomic alterations are identified and then the phenotypes are described. Because many chromosomal alterations are large and encompass numerous genes, the ascertainment of individuals with overlapping deletions and varying clinical features may allow researchers to narrow the region in which to search for candidate genes.
Theisen, Aaron; Shaffer, Lisa G
Lower extremity abnormalities in children.
Rotational and angular problems are two types of lower extremity abnormalities common in children. Rotational problems include intoeing and out-toeing. Intoeing is caused by one of three types of deformity: metatarsus adductus, internal tibial torsion, and increased femoral anteversion. Out-toeing is less common than intoeing, and its causes are similar but opposite to those of intoeing. These include femoral retroversion and external tibial torsion. Angular problems include bowlegs and knock-knees. An accurate diagnosis can be made with careful history and physical examination, which includes torsional profile (a four-component composite of measurements of the lower extremities). Charts of normal values and values with two standard deviations for each component of the torsional profile are available. In most cases, the abnormality improves with time. A careful physical examination, explanation of the natural history, and serial measurements are usually reassuring to the parents. Treatment is usually conservative. Special shoes, cast, or braces are rarely beneficial and have no proven efficacy. Surgery is reserved for older children with deformity from three to four standard deviations from the normal. PMID:12924829
Sass, Pamela; Hassan, Ghinwa
Nitrile-induced behavioral abnormalities in mice.
A single oral dose of crotononitrile or 2-pentenenitrile induced behavioral abnormalities such as circling, hyperactivity and head twitching. Crotononitrile induced the abnormalities in both olive oil- and CCl4 pretreated mice, whereas 2-pentenenitrile induced the abnormalities only in CCl4-pretreated mice. Seven related compounds induced no behavioral abnormality. The head twitching by crotononitrile and 2-pentenenitrile was either reduced by treatment with serotonin and dopamine antagonists, or enhanced by a serotonin releaser, suggesting that both the serotonin and dopamine systems are involved in the behavioral abnormalities induced by these two nitriles. PMID:2616059
Tanii, H; Hayashi, M; Hashimoto, K
Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air
The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering: Volume I, Principles. Institute of Physics Publishing, Bristol and Philadelphia 1995, ISBN 0-7503-0318-2. [2] Roth, J. R. Industrial Plasma Engineering: Volume II Applications to Nonthermal Plasma Processing Institute of Physics Publishing, Bristol and Philadelphia. 2001, ISBN 0-7503-0545-2.
Reece Roth, J.
Endogenous and exogenous hydrogen influence on amorphous silicon thin films analysis by pulsed radiofrequency glow discharge optical emission spectrometry.
During the last decade the photovoltaic industry has been growing rapidly. One major strategy to reduce the production costs is the use of thin film solar cells based on hydrogenated amorphous silicon (a-Si:H). The potential of pulsed radiofrequency glow discharge coupled to optical emission spectrometry (rf-PGD-OES) for the analysis of such type of materials has been investigated in this work. It is known that when hydrogen is present in the argon discharge, even in small quantities, significant changes can occur in the emission intensities and sputtering rates measured. Therefore, a critical comparison has been carried out by rf-PGD-OES, in terms of emission intensities, penetration rates and depth resolution for two modes of hydrogen introduction in the discharge, manually external hydrogen in gaseous form (0.2% H(2)-Ar) or internal hydrogen, sputtered as a sample constituent. First, a comparative optimisation study (at 600 Pa and 50 W) was performed on conducting materials and on a silicon wafer varying the pulse parameters: pulse frequency (500 Hz-20 kHz) and duty cycle (12.5-50%). Finally, 600 Pa, 50 W, 10 kHz and 25% duty cycle were selected as the optimum conditions to analyse three types of hydrogenated samples: an intrinsic, a B-doped and a P-doped layer based on a-Si:H. Enhanced emission intensities have been measured for most elements in the presence of hydrogen (especially for silicon) despite the observed reduced sputtering rate. The influence of externally added hydrogen and that of hydrogen sputtered as sample constituent from the analysed samples has been evaluated. PMID:22244132
S�nchez, Pascal; Alberts, Deborah; Fern�ndez, Beatriz; Men�ndez, Armando; Pereiro, Rosario; Sanz-Medel, Alfredo
Biological assessment of abnormal genitalia.
Biological assessment of abnormal genitalia is based on an ordered sequence of endocrine and genetic investigations that are predicated on knowledge obtained from a suitable history and detailed examination of the external genital anatomy. Investigations are particularly relevant in 46,XY DSD where the diagnostic yield is less successful than in the 46,XX counterpart. Advantage should be taken of spontaneous activity of the pituitary-gonadal axis in early infancy rendering measurements of gonadotrophins and sex steroids by sensitive, validated assays key to assessing testicular function. Allied measurement of serum anti-M�llerian hormone completes a comprehensive testis profile of Leydig and Sertoli cell function. Genetic assessment is dominated by analysis of a plethora of genes that attempts to delineate a cause for gonadal dysgenesis. In essence, this is successful in up to 20% of cases from analysis of SRY and SF1 (NR5A1) genes. In contrast, gene mutation analysis is highly successful in 46,XY DSD due to defects in androgen synthesis or action. The era of next generation sequencing is increasingly being applied to investigate complex medical conditions of unknown cause, including DSD. The challenge for health professionals will lie in integrating vast amounts of genetic information with phenotypes and counselling families appropriately. How tissues respond to hormones is apposite to assessing the range of genital phenotypes that characterise DSD, particularly for syndromes associated with androgen resistance. In vitro methods are available to undertake quantitative and qualitative analysis of hormone action. The in vivo equivalent is some assessment of the degree of under-masculinisation in the male, such as an external masculinisation score, and measurement of the ano-genital distance. This anthropometric marker is effectively a postnatal readout of the effects of prenatal androgens acting during the masculinisation programming window. For investigation of the newborn with abnormal genitalia, a pragmatic approach can be taken to guide the clinician using appropriate algorithms. PMID:23168057
Hughes, I A; Morel, Y; McElreavey, K; Rogol, A
Abnormal iron homeostasis and neurodegeneration
Abnormal iron metabolism is observed in many neurodegenerative diseases, however, only two have shown dysregulation of brain iron homeostasis as the primary cause of neurodegeneration. Herein, we review one of these - hereditary ferritinopathy (HF) or neuroferritinopathy, which is an autosomal dominant, adult onset degenerative disease caused by mutations in the ferritin light chain (FTL) gene. HF has a clinical phenotype characterized by a progressive movement disorder, behavioral disturbances, and cognitive impairment. The main pathologic findings are cystic cavitation of the basal ganglia, the presence of ferritin inclusion bodies (IBs), and substantial iron deposition. Mutant FTL subunits have altered sequence and length but assemble into soluble 24-mers that are ultrastructurally indistinguishable from those of the wild type. Crystallography shows substantial localized disruption of the normally tiny 4-fold pores between the ferritin subunits because of unraveling of the C-termini into multiple polypeptide conformations. This structural alteration causes attenuated net iron incorporation leading to cellular iron mishandling, ferritin aggregation, and oxidative damage at physiological concentrations of iron and ascorbate. A transgenic murine model parallels several features of HF, including a progressive neurological phenotype, ferritin IB formation, and misregulation of iron metabolism. These studies provide a working hypothesis for the pathogenesis of HF by implicating (1) a loss of normal ferritin function that triggers iron accumulation and overproduction of ferritin polypeptides, and (2) a gain of toxic function through radical production, ferritin aggregation, and oxidative stress. Importantly, the finding that ferritin aggregation can be reversed by iron chelators and oxidative damage can be inhibited by radical trapping may be used for clinical investigation. This work provides new insights into the role of abnormal iron metabolism in neurodegeneration.
Muhoberac, Barry B.; Vidal, Ruben
Electrocardiographic abnormalities in patients with myotonic dystrophy.
In examining the incidence and progression of electrocardiographic abnormalities in 45 patients with myotonic dystrophy, 26 (58%) of whom at entry had at least 1 electrocardiographic abnormality, we found conduction abnormalities in 17 (38%). In 21 patients (47%), new abnormalities developed during follow-up (mean, 4.6 years). The overall incidence of electrocardiographic abnormalities increased to 78%, and the incidence of conduction defects increased to 62%. Second-degree or complete atrioventricular block did not develop in any of the patients. Pseudoinfarction patterns were common at entry and during follow-up and were not correlated with evidence of clinical coronary artery disease. There was no correlation between the presence of electrocardiographic abnormalities and apparent disease severity. Images
Florek, R. C.; Triffon, D. W.; Mann, D. E.; Ringel, S. P.; Reiter, M. J.
Preparation of amorphous carbon films using pulsed atmospheric-pressure glow discharges in a three-electrode configuration
Pulsed glow discharge plasmas at atmospheric pressure in a three-electrode configuration were developed in order to prepare large-area plasma processes for preparation of amorphous carbon films. The high-voltage, high-repetition bipolar pulse with a fast rise time was applied between parallel-plate electrodes with quartz glasses as dielectric barrier to generate the pulsed glow discharges using a mixed gas of He as a carrier gas and CH4 as a precursor. The glow-like plasma with CH radicals was extracted to the stainless-steel substrate by applying the same potential as the parallel-plate electrodes. It was confirmed that an amorphous carbon film with a length of approximately 170 mm was successfully synthesized by the pulsed glow discharges at atmospheric pressure. However, a transition of the discharge behavior to a streamer-like discharge when increasing the input power. Therefore, it is planned that ceramic plates are used as dielectric barrier with large permittivity in order to increase plasma density. In addition, the bias voltage will be independently controlled to produce a stable glow discharge.
Kikuchi, Y.; Miyamae, M.; Matsuo, Y.; Horiguchi, Y.; Nishimura, Y.; Nagata, M.; Yatsuzuka, M.
Evaluation of abnormal liver function tests.
Interpretation of abnormalities in liver function tests is a common problem faced by clinicians. This has become more common with the introduction of automated routine laboratory testing. Not all persons with one or more abnormalities in these tests actually have liver disease. The various biochemical tests, their pathophysiology, and an approach to the interpretation of abnormal liver function tests are discussed in this review. PMID:12840117
Limdi, J K; Hyde, G M
Apparatus and method for removing abnormal tissue
US Patent & Trademark Office Database
A computer assisted, minimally invasive method and apparatus for surgically removing abnormal tissue from a patient, for example, from a breast, are disclosed. The method involves imaging of the breast to locate the abnormal tissue, and determining a volume encapsulating the abnormal tissue and including a margin of healthy tissue. Based on the volume, a sequence of movements of a surgical instrument for tissue removal device is planned, so as to predictably excise the desired volume of tissue.
Abnormal T-lymphocytes in lymphomatoid papulosis
Summary��The abnormal cell population in lymphomatoid papulosis was studied by immunohistochemistry, light and electron microscopy\\u000a in five cases. It resulted in a comprehensive description of all the main variants within the abnormal cell population.\\u000a \\u000a In one of the cases an irreversible intracytoplasmic process in the abnormal lymphocytes made it possible to demonstrate the\\u000a derivation of lymphomatoid cells with cerebriform nuclei
S. C. J. van der Putte; J. Toonstra; W. A. van Vloten; J. A. M. van Unnik
Cardiac abnormalities in mixed connective tissue disease.
Sixteen patients with mixed connective tissue disease (MCTD) were studied using noninvasive cardiovascular techniques. Cardiovascular abnormalities including pericarditis, asymmetric septal hypertrophy, and LV dilatation were found in 38 percent of the study group. Borderline ECG and echocardiographic abnormalities were present in 31 percent of the study group, and the remaining 31 percent were normal by all study techniques. MCTD patients have a high prevalence of cardiovascular abnormalities when studied noninvasively. The most common clinical abnormality is a steroid-responsive pericarditis, present in 25 percent of our series. PMID:6822098
Oetgen, W J; Mutter, M L; Lawless, O J; Davia, J E
Abnormal Mitochondrial Dynamics and Neurodegenerative Diseases
Mitochondrial dysfunction is a prominent feature of various neurodegenerative diseases. A deeper understanding of the remarkably dynamic nature of mitochondria, characterized by a delicate balance of fission and fusion, has helped to fertilize a recent wave of new studies demonstrating abnormal mitochondrial dynamics in neurodegenerative diseases. This review highlights mitochondrial dysfunction and abnormal mitochondrial dynamics in Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and Huntington disease and discusses how these abnormal mitochondrial dynamics may contribute to mitochondrial and neuronal dysfunction. We propose that abnormal mitochondrial dynamics represents a key common pathway that mediates or amplifies mitochondrial dysfunction and neuronal dysfunction during the course of neurodegeneration.
Su, Bo; Wang, Xinglong; Zheng, Ling; Perry, George; Smith, Mark A.; Zhu, Xiongwei
Fetal facial abnormalities identified during obstetric sonography.
The orbits and, if readily accessible, the facial profile were visualized as part of a brief fetal anatomy survey during approximately 7100 low-risk and high-risk obstetric sonographic examinations. This examination identified 17 facial abnormalities in 11 fetuses. There were seven abnormalities of the eyes, including three instances of absence of both eyes, two of hypertelorism, one of proptosis, and one of relative prominence. There were seven abnormalities of the nose, including three instances of marked flattening, one of absence, one of a proboscis, one of a single nostril, and one of a sunken appearance. There were two abnormally small chins. There was one marked cleft that involved the nose, lip, and palate. At least two fetuses with abnormal faces were missed entirely and coexistent facial abnormalities were missed in another three fetuses. Of the 11 fetuses with facial abnormalities identified, eight had other structural abnormalities as well, and the other three had either polyhydramnios or a history of teratogen exposure. A brief facial examination done as part of the fetal anatomy survey helps to identify abnormalities in high-risk fetuses but is considerably less productive in low-risk fetuses. PMID:3543386
Hegge, F N; Prescott, G H; Watson, P T
Ultrastructural Differentiation of Abnormal Scars
Summary Aim: To evaluate the differences between keloid and hypertrophic scars by biochemical and ultrastructural techniques. Method: Over 1000 patients with different types of scars were studied and followed up for a period of 20 years. The histochemical and biochemical analysis with respect to the composition of the extracellular matrix of the dermis was conducted. At the ultrastructural level, collagen deposition and assembly were studied using electron microscopy. The rate of proliferation and metabolic activity of the dermal fibroblasts isolated from the normal skin and scar biopsies were studied to assess the cause of excess matrix deposition in scar tissues. Results: Evaluation of different types of scars showed that both keloid and hypertrophic scars have excess matrix deposition in terms of collagen and proteoglycans. Keloid shows a high amount of acid-soluble collagen. The assembly of collagen fibrils is also abnormal in keloids. Studies on the proliferation and metabolic activity showed that keloid fibroblasts have a higher rate of proliferation and metabolic activity than fibroblasts from hypertrophic scars and normal skin. Finally, keloid fibroblasts show high and intense staining for the endoplasmic reticulum, suggesting a possible reason for high activity of these fibroblasts. Conclusion: Keloids and hypertrophic scars show distinct ultrastructural patterns of both collagen deposition and assembly. These parameters could be refined by further research, and they would thus serve as a useful tool for surgeons to distinguish different types of scars and adopt suitable therapeutic strategies.
Meenakshi, J.; Jayaraman, V.; Ramakrishnan, K.M..; Babu, M.
Development of ac corona discharge modes at atmospheric pressure
Corona discharges in gases exist under several distinctive forms. In this paper, a survey study has been made of ac corona discharge modes generated in some different gases fed in a wire-duct reactor with a constant rate of flowing at atmospheric pressure. The properties of different corona modes are analyzed under some condition transitions from Trichel pulses to a steady glow. In the course of the presented experimental work, numerous apparent contradictions with earlier observations necessitated further study and are given to provide more information on the physical mechanisms of the ac corona discharges. Furthermore, we have gained insight into some new technologies and applications of the environmentally friendly corona and plasma discharges.
El-Koramy, Reda Ahmed; Yehia, Ashraf; Omer, Mohamed [Department of Physics, Faculty of Science, Assiut University, 71516 Assiut (Egypt)
Electron trapping in radio-frequency atmospheric-pressure glow discharges
In this letter, the authors present experimental evidence of electron trapping in radio-frequency (rf) atmospheric-pressure glow discharges. By linking electron density to nanosecond plasma images and optical emission spectroscopy, they show that electron trapping occurs under most discharge conditions. The level of electron trapping increases with increasing discharge current or/and increasing excitation frequency, and manifests itself in the change of the differential conductivity at the point of the gas breakdown. Finally, they demonstrate that electron trapping is largely related to whether the half rf period is shorter than the electron transition time across the electrode gap.
Liu, D. W.; Shi, J. J.; Kong, M. G.
Sharp bursts of high-flux reactive species in submicrosecond atmospheric pressure glow discharges
In this letter, the authors present an experimental study of the temporal characteristics of submicrosecond pulsed atmospheric glow discharges. Using electrical measurements and nanosecond-resolved optical emission spectroscopy, they show that a long initial period of each voltage pulse is spent building up space charges and is then followed by a large current pulse in the voltage-falling phase. Reactive plasma species such as oxygen atoms and OH radicals are produced in a train of sharp and independent pulses of 50-100 ns wide. Finally, their production is shown to increase significantly as the voltage pulse width reduces or the repetition frequency increases.
Walsh, J. L.; Kong, M. G.
Influence of discharge conditions on energetic hydrogen atoms in a glow discharge
Influence of discharge conditions on fast hydrogen atoms in glow discharge is investigated using Balmer alpha emission spectroscopy. Investigation was performed in two orthogonal directions of observation in pure hydrogen. The shapes of the profiles are examined together with the space intensity distribution of the excessively broadened Balmer alpha line. It was found that line profile, space intensity distribution, and energy distribution of exited atoms strongly depend on voltage, pressure, and the reduced electric field. This confirms that fast H atoms are generated in charge exchange processes and neutralization of ions at cathode surface and not in a non-field process.
Cvetanovic, N. [Faculty of Transport and Traffic Engineering, University of Belgrade, Vojvode Stepe 305, Belgrade 11000 (Serbia); Obradovic, B. M.; Kuraica, M. M. [Faculty of Physics, University of Belgrade, P. O. Box 368, Belgrade 11001 (Serbia)
Heat transfer between tungsten surface and glow discharge plasmas in argon and CO2
A hot-filament method is used to study the heat transfer between tungsten surface and hollow-cathode glow discharge plasmas in argon and CO2. The dependence of the electric power supplied to a tungsten wire on the discharge current is determined for argon and carbon dioxide in the temperature range between 1000 and 1700 K. A difference in heat transfer at the tungsten wire surface is found between experiments on argon and carbon dioxide. The difference is attributed to heterogeneous recombination in CO2 plasma.
Polikarpov, F. D.; Polikarpov, A. F.; Borisov, S. F.; Nikulin, S. P.; Tretnikov, P. V.
Formation of carbonic nanostructures using PECVD and glow-discharge plasma at direct current
In this research the process of formation carbonic nanostructures using low temperatures was studied. Nanostructures were formed using PECVD and glow-discharge plasma. The research was carried out at temperature range between 300�C - 700�C. The influence of Ni catalyst thickness and concentration of carbon-containing component in vapour phase on the structure of carbonic deposit was studied. Consequently we attained productive growth of both the homogeneous vertical nanotubes and graphene flakes array at low temperature (350�C). Electrophysical features of obtained structures were examined.
Gromov, D. G.; Gavrilov, S. A.; Dubkov, S. V.
Generation of O2 From CO2 by Glow Discharge And Permeation
Technique for generating supply of highly pure O2 from CO2 developed. First, atomic oxygen at useful partial pressure generated by glow-discharge dissociation of CO2. Atomic oxygen formed in vicinity of hot silver membrane and permeates through membrane to downstream region, where thermally recombined into O2 and pumped away to storage tank. Pure oxygen stored suitable for human consumption and other uses. Originally developed to convert Martian atmosphere of CO2 to O2 for astronaut consumption. Other potential applications include purification of atmospheres in Space Shuttle and Space Station Freedom. Byproduct CO must be handled by other techniques.
The preliminary study on the chemical synthesis between graphite and water by glow-discharge experiments
Glow-discharge experiments were performed against water using a graphite rod as the anode and a silver thread as the cathode under an Ar atmosphere. UV-spectrum, FT-IR, 1H-NMR spectrum and GC-MS analyses of the solutions irradiated with plasma were studied. It was found that a small amount of carbon was transferred from anode into water and some organic compounds were produced by reaction between carbon and water. Among those, formic acid, acetic acid and propanoic acid were identified as the main products.
Shi, Huai-Bin; Shao, Chun-Lin; Yu, Zeng-Liang
Ion formation processes in the afterpeak time regime of pulsed glow discharge plasmas.
The formation of ions following the termination of power in a pulsed glow discharge ion source is investigated. The populations of ionized species containing sputtered atoms M(+), M 2 (1) :, and MAr(+) are observed to maximize after the termination of discharge power. Collisions involving sputtered atoms and metastable argon atoms, Penning and associative ionization, are considered to be responsible for the formation of ions in the discharge afterpeak time regime. The domination of these ion formation processes during the afterpeak time regime is supported by the results from investigations of discharge operating parameters, metastable argon atom quenching, and ion kinetic energy distributions. PMID:24225999
Pan, C; King, F L
Influence of cathode temperature on the parameters of an atmospheric pressure dc glow discharge
It is shown that the cathode temperature has a significant influence on the properties of the cathode fall in a self-sustained, normal, dc, atmospheric pressure glow discharge in helium and, in particular, on the electric field distribution, the thickness of the cathode fall layer, the current density and the gas temperature. An increase in the cathode temperature leads to an increase in the gas temperature and cathode fall thickness, a decrease in the current density and a modification in the radial distribution of the electric field close to the cathode surface. A discussion based on a one-dimensional model of the cathode fall region including gas heating is presented.
Arkhipenko, V. I.; Kirillov, A. A.; Safronau, Ya A.; Simonchik, L. V.; Zgirouski, S. M.
Self-sustained dc atmospheric pressure normal glow discharge in helium: from microamps to amps
It has been shown that self-sustained normal dc atmospheric pressure glow discharge (APGD) in helium exists in a large range of current values from 100 �A to 10 A. The plasma of this discharge is weakly ionized (one thousandth part of a per cent) and is non-equilibrium. The plasma non-equilibrium degree in the positive column depends on the discharge current values. Parameters of the cathode region stay constant over the whole current range of normal APGD.
On the feasibility of inversion methods based on models of urban sky glow
Multi-wavelength imaging luminance photometry of sky glow provides a huge amount of information on light pollution. However, the understanding of the measured data involves the combination of different processes and data of radiation transfer, atmospheric physics and atmospheric constitution. State-of-the-art numerical radiation transfer models provide the possibility to define an inverse problem to obtain information on the emission intensity distribution of a city and perhaps the physical properties of the atmosphere. We provide numerical tests on the solvability and feasibility of such procedures.
Koll�th, Z.; Kr�nicz, B.
Simulations of self-organized filaments in a dielectric barrier glow discharge plasma
The spontaneous filamentation of a dielectric barrier glow discharge plasma (Townsend, not streamer breakdown), i.e., an instability of the homogeneous state has been simulated and understood with the help of a self-consistent two-dimensional fluid model of the discharge. The formation of self-organized or solitary filaments observed experimentally and described in previous papers can be explained in terms of electron and ion transport coefficients only, without including gas heating, plasma chemistry or surface effects. The conditions favoring the plasma filamentation are discussed.
Brauer, I.; Punset, C.; Purwins, H.-G.; Boeuf, J. P.
Characterization of Air-Nitrogen-Argon DC Glow Discharge Plasma with THz Time Domain Spectroscopy
Transmission of terahertz pulses through DC glow discharge plasma was investigated for different gases. The pressure was kept in between the range of 0.1 torr-0.5 torr and for each pressure different measurements were taken at 5 mA, 10 mA and 15 mA plasma currents. Moreover, emission spectrum of Air, N2 and Ar plasma analysis were done respectively. It was found that the transmission of terahertz pulses through nitrogen plasma was considerably affected compared to that of the argon plasma.
Karaoglan, G.; Tosun, Z.; Akbar, D.; Altan, H.
Instability of a 550Base Pair DNA Segment and Abnormal Methylation in Fragile X Syndrome
The fragile X syndrome, a common cause of inherited mental retardation, is characterized by an unusual mode of inheritance. Phenotypic expression has been linked to abnormal cytosine methylation of a single CpG island, at or very near the fragile site. Probes adjacent to this island detected very localized DNA rearrangements that consti- tuted the fragile X mutations, and whose target
I. Oberle; F. Rousseau; D. Heitz; C. Kretz; D. Devys; A. Hanauer; J. Boue; M. F. Bertheas; J. L. Mandel
Platelet abnormalities during colonic inflammation
Patients with inflammatory bowel disease (IBD) are susceptible to microvascular thrombosis and thromboembolism. The increased incidence of thrombosis is accompanied by enhanced coagulation and abnormalities in platelet function. Clinical studies have revealed thrombocytosis, alterations in platelet activation, enhanced platelet-leukocyte interactions, and elevated plasma levels of prothrombotic cytokines. This study was directed towards determining whether the thrombocytosis, altered platelet functions, and enhanced platelet-leukocyte interactions observed in IBD patients can be recapitulated in the dextran sodium sulfate (DSS) and T-cell transfer models of murine colonic inflammation. Flow cytometry was used to characterize platelet function in heparin-anticoagulated whole blood of control mice and in mice with colonic inflammation. Platelets were identified by characteristic light scattering and membrane expression of CD41. Thiazole orange (TO) labeling was used to differentiate between immature and mature platelets. Platelet activation was monitored using the expression of an activation epitope of GPIIb/IIIa integrin. The combination of CD41, CD45.2, Gr-1, F4/80 and isotype control antibodies was used to detect and quantify aggregates of leukocytes, neutrophils and monocytes with platelets. Our results indicated that colonic inflammation is associated with thrombocytosis, leukocytosis, and the appearance of immature platelets. An increased number of circulating activated platelets was detected in colitic mice, along with the formation of aggregates of leukocytes (PLA), neutrophils (PNA) and monocytes (PMA) with platelets. Selectin blockade with fucoidin inhibited DSS-induced PLA formation. The findings of this study indicate that many features of the altered platelet function detected in human IBD can be reproduced in animal models of colonic inflammation.
Yan, Serena LS.; Russell, Janice; Harris, Norman R.; Senchenkova, Elena Y.; Yildirim, Alper; Granger, D. Neil
A new look at abnormal uterine bleeding.
New universal terminology, classifications, and definitions recommended by the International Federation of Gynecology and Obstetrics and supported by the American College of Obstetricians and Gynecologists to describe abnormal uterine bleeding abnormalities in reproductive women are presented. Identification and management of anovulatory and ovulatory uterine bleeding are explored. PMID:24177024
Twiss, Janice J
Renal Tubular Abnormalities in Infants with Hydronephrosis
PurposeAbnormalities in renal tubular function have been observed in hydronephrotic urinary tract disease, resulting in metabolic acidosis, hyperkalemia and excessive free water diuresis. The frequency of these abnormalities, particularly in our infant population, was the impetus for our study.
Jayanthi Chandar; Carolyn Abitbol; Gaston Zilleruelo; Rafael Gosalbez; Brenda Montane; Jose Strauss
Retinal Circulatory Abnormalities in Type 1 Diabetes
Purpose. To quantify retinal circulatory abnormalities in patients with type 1 diabetes; to compare blood speed and blood flow in major temporal retinal arteries as well as total retinal arterial cross-section measured in patients to that measured in controls without diabetes; to determine which factors are related to the measured abnormalities within the patient group. Methods. The laser Doppler technique
Gilbert T. Feke; Sheldon M. Buzney; Hironobu Ogasawara; Naoki Fujio; Douglas G. Goger; Norman P. Spack; Kenneth H. GabbayX
Renal abnormalities and their developmental origin
Congenital abnormalities of the kidney and urinary tract (CAKUT) occur in 1 out of 500 newborns, and constitute approximately 20�30% of all anomalies identified in the prenatal period. CAKUT has a major role in renal failure, and there is increasing evidence that certain abnormalities predispose to the development of hypertension and cardiovascular disease in adult life. Moreover, defects in nephron
Andreas Schedl
Immune Abnormalities in Patients with Autism.
A study of 31 autistic patients (3-28 years old) has revealed several immune-system abnormalities, including decreased numbers of T lymphocytes and an altered ratio of helper-to-suppressor T cells. Immune-system abnormalities may be directly related to underlying biologic processes of autism or an indirect reflection of the actual pathologic�
Warren, Reed P.; And Others
Breathing abnormalities in sleep in achondroplasia
Overnight sleep studies were performed in 20 subjects with achondroplasia to document further the respiratory abnormalities present in this group. Somatosensory evoked potentials (SEPs) were recorded in 19 of the subjects to screen for the presence of brainstem abnormalities, which are one of the potential aetiological mechanisms. Fifteen children aged 1 to 14 years, and five young adults, aged 20
K A Waters; F Everett; D Sillence; E Fagan; C E Sullivan
A Cytogenetic Study of Abnormal Sexual Development.
Nineteen patients associated with sexual anomalies were studied for chromosome abnormalities. Five cases (26.3 per cent) were found to be chromosomally abnormal. They were one case of mixed gonadal dysgenesis with an XY/XO mosaicism, two cases of Klinefel...
C. C. Lin K. S. W. Kim P. Y. Wei
Severely Symptomatic Craniovertebral Junction Abnormalities in Children
Objectives: The treatment of symptomatic cranio-vertebral junction (CVJ) instability in children affected by CVJ abnormalities is a challenge. A series of severely symptomatic children has been reviewed to understand the controversial long-term effectiveness of the aggressive management of CVJ abnormalities, in terms of clinical improvement, spinal stability and growth. Methods: Three Down syndrome patients, 1 with mucopolysaccharidosis and 1 with
Carlo Giussani; Franck-Emmanuel Roux; Paolo Guerra; David Pirillo; Marco Grimaldi; Giuseppe Citerio; Erik P. Sganzerla
Myenteric plexus abnormalities associated with epiphrenic diverticula
Objective: To (1) categorize histologic esophageal myenteric plexus abnormalities in patients undergoing surgical treatment for epiphrenic diverticulum, and (2) correlate histologic changes with associated esophageal motility disorders and hiatal hernia. Methods: From January 1987 to May 2008, 40 patients had surgery for epiphrenic diverticulum. Esophageal manometry was abnormal in 29 (73%); 23 (58%) had hiatal hernia. Esophageal muscle specimens were
Thomas W. Rice; John R. Goldblum; Martha M. Yearsley; Steven S. Shay; Scott I. Reznik; Sudish C. Murthy; David P. Mason; Eugene H. Blackstone
Hereditary evaluation of multiple developmental abnormalities in the Havanese dog breed.
The Havanese is a toy breed that presents with a wide range of developmental abnormalities. Skeletal defects, particularly osteochondrodysplasia (OCD), are the most frequently observed anomalies. Cataracts, liver shunts, heart murmurs, and missing incisors are also common in this breed. Estimates of heritability and complex segregation analyses were carried out to evaluate modes of transmission for these abnormalities. A moderate heritability was identified and evidence for a single major locus was found. Novel statistical analysis methods were used to identify four traits that co-segregate: cataracts, hepatic abnormalities, OCD, and cardiac abnormalities. A canine-specific microarray was used to identify changes in gene expression in the liver that accompany the aforementioned developmental problems. One hundred and thirteen genes were found to be differentially regulated in the Havanese. PMID:17621585
Starr, Alison N; Famula, Thomas R; Markward, Nathan J; Baldwin, Joanne V; Fowler, Karon D; Klumb, Diane E; Simpson, Nancy L; Murphy, Keith E
The Presence of Normal Modes Above a Capacitive Plasma Applicator
Normal modes of standing waves in the plasma potential have been observed over the entire surface of a dual-frequency capacitive applicator immersed in an inductively-generated rf glow discharge. An emissive probe used to measure the plasma potential is located 0.95 cm above the applicator and moved by a two-dimensional drive system. The heater current to the probe is switched off during the 100 ?s measurement to eliminate uncertainties due to the heater voltage. Vp is mapped at 208 spatial locations and digitized at 1 GHz. An electrically floating probe is located 1.84 cm above the center of applicator to afford a means to generate correlation functions for the detection of waves in the low temperature plasma. The observed normal modes in potential can be expressed as summations of Bessel functions much as the vibrational modes in circular membranes and plates. The modes are most likely excited by the oscillations of the plasma-sheath interface including harmonic oscillations arising from the nonlinear mechanisms governing the sheath dynamics. As the frequency is increased, the order of the normal modes is postulated to increase as these modes are likely determined by the impedance terminating conditions on the chamber surfaces.
Gekelman, Walter; Barnes, Michael; Vincena, Steven; Pribyl, Patrick
Hydrogenated amorphous silicon and silicon germanium triple-junction solar cells at high rate using RF and VHF glow discharges
We present our recent results on a-Si:H\\/a-SiGe:H\\/a-SiGe:H triple-junction solar cells made at high deposition rates using both RF and MVHF glow discharges. The growth parameters studied are under the constraints of manufacturing feasibility so that any improvement can be transferred to manufacturing lines. Using RF glow discharge, we achieved initial active-area efficiencies of 11.4% and 12.5% on Al\\/ZnO and Ag\\/ZnO
Guozhen Yue; Baojie Yan; Jeffrey Yang; Subhendu Guha
Liver abnormalities and endocrine diseases.
The liver and its pleotropic functions play a fundamental role in regulating metabolism, and is also an inevitable target of multiple metabolic disorders. The numerous and constant relationships and feedback mechanisms between the liver and all endocrine organs is reflected by the fact that an alteration of one oftentimes results in the malfunction of the other. Hypo- and hyperthyroidism are frequently associated with hepatic alterations, and thyroid diseases must be excluded in transaminase elevation of unknown cause. Drugs such as propylthiouracil, used in the treatment of hyperthyroidism, may induce liver damage, and other drugs such as amiodarone, carbamazepine, and several chemotherapeutic agents can lead to both thyroid and liver abnormalities. Liver diseases such as hepatitis, hepatocellular carcinoma, and cirrhosis may cause altered levels of thyroid hormones, and alcoholic liver disease, both due to the noxious substance ethanol as well as to the hepatic damage it causes, may be responsible for altered thyroid function. Both excess and insufficiency of adrenal function may result in altered liver function, and adrenocortical dysfunction may be present in patients with cirrhosis, especially during episodes of decompensation. Again an important player which affects both the endocrine system and the liver, alcohol may be associated with pseudo-Cushing syndrome. Sex hormones, both intrinsic as well as extrinsically administered, have an important impact on liver function. While oestrogens are related to cholestatic liver damage, androgens are the culprit of adenomas and hepatocellular carcinoma, among others. Chronic liver disease, on the other hand, has profound repercussions on sex hormone metabolism, inducing feminization in men and infertility and amenorrhoea in women. Lastly, metabolic syndrome, the pandemia of the present and future centuries, links the spectrum of liver damage ranging from steatosis to cirrhosis, to the array of endocrine alterations that are features of the syndrome, including insulin resistance, central obesity, and hyperlipidaemia. Clinical practice must integrally evaluate the effects of the intricate and tight relationship between the liver and the endocrine system, in order to better address all manifestations, complications, and prevent deterioration of one or the other organ-system. PMID:24090942
Burra, Patrizia
Two-dimensional numerical study of atmospheric pressure glows in helium with impurities
A two-dimensional numerical model of an atmospheric pressure glow (APG) discharge was developed. The simulation of the APG in helium with some nitrogen impurities successfully reproduced the discharge evolution during the breakdown process observed in experiments. The results show that the breakdown first appears at the central region of the discharge followed by the axial and radial propagation of the ionization wave. The space charge induced electric field is the main reason for the radial propagation. Penning ionization is the dominant ionization mechanism in the discharge. It leads to an elevated pre-ionization level before the discharge pulse that is essential for maintaining a uniform discharge. Increasing the driving frequency favours a transition from a filamentary to a uniform glow discharge. An increasing number of filaments with driving frequency are observed. The coalescence of the filaments at sufficiently high frequency leads to a uniform discharge. Decreasing the dielectric permittivity of the barriers limits the discharge current and leads to a shift of the discharge towards a uniform Townsend discharge.
Zhang, P.; Kortshagen, U.
Radio-frequency powered glow discharge device and method with high voltage interface
A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components.
Duckworth, Douglas C. (Knoxville, TN); Marcus, R. Kenneth (Clemson, SC); Donohue, David L. (Vienna, AT); Lewis, Trousdale A. (Oak Ridge, TN)
Glow-discharge optical spectroscopy as a diagnostic of sputtered permalloy film composition and saturation magnetostriction
We show that the composition and saturation magnetostriction of sputtered permalloy films can be correlated with the relative intensities of iron and nickel atomic emissions from a 13.56-MHz rf glow discharge. Wavelength-resolved emission spectra as a function of discharge pressure were recorded while sputtering iron and permalloy targets. Intensities of some emission lines were highly correlated, so that their ratios were nearly independent of argon pressure. This occurred in spite of a /similar to/50-fold change in the brightness of the glow over the pressure range studied, and suggested that the stoichiometry of the sputtering target and the sputtered permalloy film can each be assessed during the sputtering process. The selection of appropriate emission lines is discussed, along with considerations of the type of equilibrium distribution prevalent in a sputtering discharge. We used five sputtering targets with different Ni/Fe ratios to grow films. The films were analyzed in terms of composition, stress, and saturation magnetostriction. Film stress was not observed to vary significantly with sputtering target composition. A high degree of correlation was observed between Fe/Ni emission intensity ratio, target composition, film composition, and saturation magnetostriction.
Page, R.H.; Gudeman, C.S.; Novotny, V.J.
Evidence for a far-ultraviolet spacecraft glow in the ROSAT Wide-Field Camera
During a 6 month all-sky survey and subsequent operations, the ROSAT Wide-Field Camera (WFC) was subject to a dominant and unexpected source of background. The contributions of the expected components are well understood, and once these are removed the residual background shows a strong correlation with the ram angle, suggesting that it may be due to a spacecraft glow phenomenon similar to that seen in other missions, most notably the Atmospheric Explorer (AE-C) and the Space Shuttle. The microchannel plate detector used in the WFC is very insensitive to photons of energy E equal to or less than 6 eV (lambda equal to or greater than 2000 A), which implies that the spacecraft glow, if it is the cause of the excess background, may lie in the ultraviolet or far-ultraviolet bands, outside the wavelength range of the majority of the previous observations. We present the results of a computer model which show that in some orientations the sensitive surfaces are `shadowed' from the ramming gases by the bulk of the spacecraft, and that in these orientations the observed background is much reduced.
West, R. G.; Sims, M. R.; Willingale, R.
Charging of dust grains in a nonequilibrium plasma of a stratified glow discharge
A theoretical model is presented that describes the charging of dust grains in the positive plasma column of a stratified glow dc discharge in argon. A one-dimensional self-consistent model is used to obtain axial profiles of the electric field, as well as the electron energy distribution function along the axis of the discharge tube. Radial profiles of the electric field are determined in the ambipolar diffusion approximation. It is assumed that, in the radial direction, the electron distribution function depends only on the total electron energy. Two-dimensional distributions of the discharge plasma parameters are calculated and used to determine the potential and charge of a test dust grain at a certain point within the discharge and the electrostatic forces acting on it. It is shown that the grain charge distribution depends strongly on the nonequilibrium electron distribution function and on the nonuniform distribution of the electric field in a stratified glow discharge. A discussion is presented on the suspension of dust grains, the separation of grains by size in the discharge striations, and a possible mechanism for the onset of vortex dust motion at the edge of a dust cloud.
Sukhinin, G. I.; Fedoseev, A. V. [Russian Academy of Sciences, Kutateladze Institute of Thermophysics, Siberian Branch (Russian Federation)
Thermoluminescence in pure LiF crystals: Glow peaks and their connection with color centers
Nominally pure LiF crystals were irradiated with the same dose (0.85 106 R) of gamma rays at ambient and low temperatures (-60 �C) and the resulting thermoluminescence (TL) is reported. Various optical and thermal treatments were applied in order to change the concentration of color centers (CCs). The effect of such treatments on the glow curves is observed. Knowing the coloration from optical transmission and photoluminescence measurements made on the same samples, we attribute many of the glow peaks (GPs) to the annealing of F center aggregates. For the present conditions of irradiation and dose, TL processes begin with decay of F3+ centers that display a GP at 164 �C. F3(R) centers follow and are responsible for GPs at 193 and 228 �C. A GP at 263 �C is ascribed to F2 centers. Several peaks at temperatures in the range of 280-380 �C are associated with impurity perturbed F centers. A GP at 410 �C is associated with a complex of aggregated F and H centers. These attributions are accomplished by means of TL spectra, optical transmission spectra, and annealing procedures, and are critically discussed. The experimental data confirm the general trend of thermal stability of CCs, which decreases by moving from simple F centers to more complex ones, and the existence of exchange dynamics among CCs.
Baldacchini, G.; Montereali, R. M.; Nichelatti, E.; Kalinov, V. S.; Voitovich, A. P.; Davidson, A. T.; Kozakiewicz, A. G.
Nominally pure LiF crystals were irradiated with the same dose (0.85 10{sup 6} R) of gamma rays at ambient and low temperatures (-60 deg. C) and the resulting thermoluminescence (TL) is reported. Various optical and thermal treatments were applied in order to change the concentration of color centers (CCs). The effect of such treatments on the glow curves is observed. Knowing the coloration from optical transmission and photoluminescence measurements made on the same samples, we attribute many of the glow peaks (GPs) to the annealing of F center aggregates. For the present conditions of irradiation and dose, TL processes begin with decay of F{sub 3}{sup +} centers that display a GP at 164 deg. C. F{sub 3}(R) centers follow and are responsible for GPs at 193 and 228 deg. C. A GP at 263 deg. C is ascribed to F{sub 2} centers. Several peaks at temperatures in the range of 280-380 deg. C are associated with impurity perturbed F centers. A GP at 410 deg. C is associated with a complex of aggregated F and H centers. These attributions are accomplished by means of TL spectra, optical transmission spectra, and annealing procedures, and are critically discussed. The experimental data confirm the general trend of thermal stability of CCs, which decreases by moving from simple F centers to more complex ones, and the existence of exchange dynamics among CCs.
Baldacchini, G.; Montereali, R. M. [Department of Physical Technologies and New Materials-Frascati Research Center, ENEA, Via E. Fermi 45, Frascati, Roma 00044 (Italy); Nichelatti, E. [Department of Physical Technologies and New Materials-Casaccia Research Center, ENEA, S. Maria di Galeria, Roma 00123 (Italy); Kalinov, V. S.; Voitovich, A. P. [Institute of Physics, Academy of Sciences of Belarus, 70 Nezavisimosti Ave., 220067 Minsk (Belarus); Davidson, A. T.; Kozakiewicz, A. G. [Department of Chemistry, University of Zululand, Kwadlangezwa 3886 (South Africa)
Liquid sampling-atmospheric pressure glow discharge ionization source for elemental mass spectrometry.
A new, low power ionization source for elemental MS analysis of aqueous solutions is described. The liquid sampling-atmospheric pressure glow discharge (LS-APGD) operates by a process wherein the surface of the liquid emanating from a 75 ?m i.d. glass capillary acts as the cathode of the direct current glow discharge. Analyte-containing solutions at a flow rate of 100 ?L min(-1) are vaporized by the passage of current, yielding gas phase solutes that are subsequently ionized in the <5 W (maximum of 60 mA and 500 V), ~1 mm(3) volume, plasma. The LS-APGD is mounted in place of the normal electrospray ionization source of a Thermo Scientific Exactive Orbitrap mass spectrometer system without any other modifications. Basic operating characteristics are described, including the role of discharge power on mass spectral composition, the ability to obtain ultrahigh resolution elemental isotopic patterns, and demonstration of potential limits of detection based on the injection of aliquots of multielement standards (S/N > 1000 for 5 ng mL(-1) Cs). While much optimization remains, it is believed that the LS-APGD ion source may present a practical alternative to high-powered (>1 kW) plasma sources typically employed in elemental mass spectrometry, particularly for those cases where costs, operational overhead, simplicity, or integrated elemental/molecular analysis considerations are important. PMID:21355580
Marcus, R Kenneth; Quarles, C Derrick; Barinaga, Charles J; Carado, Anthony J; Koppenaal, David W
Measurement of gas temperature and convection velocity profiles in a dc atmospheric glow discharge
Gas temperature and convective velocity distributions are presented for an unconfined glow discharge in air at atmospheric pressure, with electric currents ranging between 30 and 92 mA. The vertically oriented discharge was formed between a pin anode (top) and an extended cathode. The temperature and velocity profiles were measured using laser-induced Rayleigh scattering and laser Doppler anemometry techniques, respectively. The temperature field exhibited a conical shape with the radius of hot temperature zone increasing toward the anode. A maximum temperature of 2470 K was observed on the discharge axis with the discharge current of 92 mA. Air velocity measurements around the discharge demonstrated that the shape and magnitude of the temperature field are strongly affected by natural convection. Estimates indicate that convective losses may account for more than 50% of the power input into the positive column of the discharge. The measured temperature fields and convective velocity profiles provide a set of data that is important for the evaluation of dc atmospheric glow discharges in various applications such as sound manipulation and acoustic noise mitigation.
Stepaniuk, Vadim P.; Ioppolo, Tindaro; Oetuegen, M. Volkan; Sheverev, Valery A. [Lenterra Inc., 7 Tenney Road, West Orange, New Jersey 07052 (United States); Polytechnic University, 6 Metrotech Center, Brooklyn, New York 11201 (United States); Mechanical Engineering Department, Southern Methodist University, P. O. Box 750337, Dallas, Texas 75275 (United States); Polytechnic University, 6 Metrotech Center, Brooklyn, New York 11201 (United States)
OAK A271 PRODUCTION OF HIGHER STRENGTH THIN WALLED GLOW DISCHARGE POLYMER SHELLS FOR CRYOGENIC EXPERIMENTS AT OMEGA. Thin walled polymer shells are needed for OMEGA cryogenic laser experiments. These capsules need to be about 900 {micro}m in diameter and as thin as possible (approx 1-2 {micro}m), while having enough strength to be filled with DT as fast as possible to about 1000 atm. The authors have found that by optimizing the coating parameters in the glow discharge polymer (GDP) deposition system, traditionally used for making ICF targets, they can routinely make robust, {approx} 1.5 {micro}m thick, 900 {micro}m diameter GDP shells with buckle strengths of over 0.3 atm. This is twice the strength of shells made prior to the optimization and is comparable to values quoted for polyimide shells. In addition, these shells were found to be approximately three times more permeable and over 20% denser than previously made GDP shells. The combination of higher strength and permeability is ideal for direct drive cryogenic targets at OMEGA. Shells as thin as 0.5 {micro}m have been made. In this paper, the authors discuss the shell fabrication process, effects of modifying various GDP deposition parameters on shell properties and chemical composition.
The effect of OH radicals on Cr-I spectral lines emitted by DC glow discharges
The intensity distribution of the Cr-I 428.97 nm resonant and 520.60 nm non-resonant lines was studied as a function of the distance from the anode in a low pressure DC-GD fitted with a Cr metal cathode and operated in various gas atmospheres, including helium ( P = 4 mbar), ambient air and water vapor ( P = 0.8 mbar). In the helium and ambient air atmospheres, the intensity peaks occurred in the near cathode region (cathode glow) in accordance with the literature. When operated in water vapor, however, the Cr-I 428.97 nm resonant line disappeared, whereas the intensity of the non-resonant 520.60 nm line was enhanced. This result may be attributed to resonant energy transfer collisions taking place between OH radicals excited to the first vibrational level and Cr *428 atoms excited to the z 7P 0 upper level of the 428.97 nm transition. The similar gas phase composition encountered with a DC electrolyte cathode atmospheric pressure glow discharge (ELCAD) and the Cr metal cathode GD operating under a low pressure of water vapor suggests that the zero intensity of the Cr resonance lines (428.97 nm, 360.53 nm) produced in the ELCAD may be attributed to similar energy transfer processes. Our results show that the intensity of the Cr-I 520.60 nm line can be used for analytical purposes in the ELCAD.
Mezei, P.; Cserfalvi, T.; Hartmann, P.; Bencs, L.
Characterization of a glow discharge ion source for the mass spectrometric analysis of organic compounds.
A glow discharge ion source has been constructed for the mass spectrometric analysis of organic compounds. Characterization of the source has been made by studying the effect of pressure and discharge current on ionic distributions by anodic ion sampling along the discharge axis. Ion and electron densities and electronic temperatures have been calculated by using the single Langmuir probe technique to correlate the extraction efficiency with measured ion distributions and gain some insight into the ionization of organic molecules. The spectra obtained for several classes of organic compounds show that formation of parent-molecular ions by proton transfer, resulting partly from the background water molecules, is a major low energy process while charge transfer, Penning ionization, and electron ionization ace probably responsible for the fragmentation observed. The spectra result from the simultaneous occurrence of high and low energy reactions, and their structural information content is very high, yielding both molecular and extensive fragment ion information. The glow discharge ion source has proved to be essentially maintenance-free, easy to operate, stable, and can be used at reasonable mass resolution (up to 70001. The source also provides picogram range detection limits and has a linear response range of about six orders of magnitude, which makes it an interesting ion source for routine analysis. Preliminary work conducted with chromatographic interfaces indicates that its use can be easily extended to both gas and liquid chromatography. PMID:24222568
Carazzato, D; Bertrand, M J
Effect of volume and surface charges on discharge structure of glow dielectric barrier discharge
The effect of volume and surface charges on the structure of glow dielectric barrier discharge (DBD) has been investigated numerically by using two-dimensional (2D) fluid modeling. The local increase of volume or surface charges induces a kind of activation-inhibition effect, which enhances the local volume discharge and inhibits the discharge in neighborhoods, resulting in non-uniform discharge. The activation-inhibition effect due to the non-uniform volume and/or surface charges depends on the non-uniformity itself and the applied voltage. The activation-inhibition of non-uniform charges has different effects on the volume charges and the accumulated surface charges. The distribution of remaining free charges (seed electrons) in volume at the beginning of voltage pulse plays a key role for the glow DBD structure, resulting in a patterned DBD, when the seed electrons are non-uniform at higher frequency and moderate voltage or uniform DBD, when the seed electrons are uniform at lower frequency or high voltage. The distribution of surface charges is not the determining factor but a result of the formed DBD structure.
Xu, Shao-Wei; He, Feng; Wang, Yu; Li, Lulu; Ouyang, Ji-Ting
Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas
A Boltzmann plot for many iron atomic lines having excitation energies of 3.3-6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3-4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas.
Zhang, Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki
Modeling of the spatiotemporal behavior of an argon glow discharge at atmospheric pressure
The spatiotemporal behavior of gas discharges is described by means of a fluid model which comprises the coupled set of balance equations for the densities of electrons, ions and neutral particles, the electron energy balance equation as well as Poisson's equation for the electric potential. This system of equations is numerically solved using a stabilized finite element method. The discharge voltage required for the solution of Poisson's equation is determined from the solution of the external electric circuit equations taking into account the time-dependent capacity and resistance of the plasma. In the present contribution first results related to an argon plasma at atmospheric pressure in a discharge configuration designed to generate small homogeneous high-pressure glow dischargesfootnotetextW. B"otticher et al., Appl. Phys. B 54 (1992) 295 are presented. Main features of the temporal evolution of the discharge, which can be divided into Townsend, ignition, quasi-steady-state and recombination phase, are discussed. It is found that the cathode-fall thickness and current density in the quasi-steady state are of the order of the values given by the similarity laws for normal glow discharges.
Becker, Markus M.; Loffhagen, Detlef
Atmospheric pressure direct current micro glow discharge simulation: Effects of the external circuit
The effect of the external circuit on discharge conditions are not explicitly considered in most modeling studies of thermal and non-thermal plasma discharges. In this study, we investigate the effects of including the external circuit on simulation results of atmospheric pressure micro discharges. Two-dimensional simulations of DC atmospheric pressure micro glow discharges were conducted using a hybrid model. The discharge model is coupled to an external circuit model enabling to study the effect of the external circuit parameter. Simulation results were first obtained by excluding the external circuit. When included, the external circuit consisted of a ballast resistance and a parasitic capacitance connected in series and parallel in respect to the discharge. Simulations were conducted over a broad discharge current range (varying ballast resistance) and also for varying parasitic capacitance. For large ballast resistance the discharge was found to operate in the Townsend regime as a dark discharge. At smaller ballast resistance the discharge showed `normal' glow like characteristics. The simulations further indicated that for higher values of the parasitic capacitance the discharge even with a DC power supply was self oscillatory; indicating some unstable regime. The predicted results were found to be in agreement with experimental observations.
Farouk, Tanvir; Farouk, Bakhtier
Novel approach to produce polymerized hydrocarbon coatings using dielectric barrier controlled atmospheric pressure glow discharge plasma
Conventionally, low-pressure (<1 Torr) electrical discharges are used for material processing and thin-film deposition. These schemes suffer mainly due to the high cost of equipment and the complexity of operations. The atmospheric pressure glow discharge plasma is developed using a threaded styled electrode in different configurations, and these reactors are used to produce plasma polymerized coatings, required on plane substrates as self-supporting films to obtain membranes for blocking holes in cavities, and on microballoon targets, which are used as fuel containers for inertial confinement fusion, to avoid DT gas permeation. Helium gas is used as the supporting gas for formation and stabilization of atmospheric pressure glow discharge plasma reactors. Ethylene and acetylene gases are used as monomers to produce plasma polymerized hydrocarbon films. These films are characterized using scanning electron microscopy. Plasma polymerized coatings of thickness 100 nm-10 ?m with a smooth surface finish (rms<100 nm) are deposited successfully. The surface finish is further improved using a postdischarge configuration. Preliminary results are very encouraging but further progress is to be made in this area. We are also planning to extend this technique for C:H coating of microballoons, which are used as fuel containers in inertial confinement fusion.
Mishra, K. K.; Khardekar, R. K.; Singh, Rashmi; Pant, H. C.
Growth of tungsten nanoparticles in direct-current argon glow discharges
The growth of nanoparticles from the sputtering of a tungsten cathode in DC argon glow discharges is reported. The study was performed at fixed argon pressure and constant discharge current. The growth by successive agglomerations is evidenced. First, tungsten nanocrystallites agglomerate into primary particles, the most probable size of which being {approx}30 nm. Primary particles of this size are observed for all plasma durations and always remain the most numerous in the discharge. Primary particles quickly agglomerate to form particles with size up to {approx}150 nm. For short plasma duration, log-normal functions describe accurately the dust particle size distributions. On the contrary, for long discharge durations, a second hump appears in the distributions toward large particle sizes. In the meantime, the discharge voltage, electron density, and emission line intensities strongly evolve. Their evolutions can be divided in four separate phases and exhibit unusual distinctive features compared to earlier observations in discharges in which particles were growing. The evolution of the different parameters is explained by a competition between the surface state of the tungsten cathode and the influence of the growing nanoparticles. The differences with sputtering glow discharges and chemically active plasmas suggest that the nanoparticle growth and its influence on discharge parameters is system and material dependent.
Kishor Kumar, K.; Coueedel, L.; Arnas, C. [Laboratoire de Physique des Interactions Ioniques et Moleculaires, CNRS-Aix-Marseille Universite, 13397 Marseille (France)
Decomposition of toluene in a steady-state atmospheric-pressure glow discharge
Results are presented from experimental studies of decomposition of toluene (C6H5CH3) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C6H5CH3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N2: O2: H2O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C6H5CH3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C6H5CH3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.
Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.
A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components. 11 figures.
Duckworth, D.C.; Marcus, R.K.; Donohue, D.L.; Lewis, T.A.
Xu, Shao-Wei; He, Feng; Wang, Yu; Li, Lulu; Ouyang, Ji-Ting [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)] [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)
The mode-switching phenomenon of PSR B0329+54 is investigated based on the long-term monitoring from 2003 September to 2009 April made with the Urumqi 25 m radio telescope at 1540 MHz. At that frequency, the change of relative intensity between the leading and trailing components is the predominant feature of mode switching. The intensity ratios between the leading and trailing components are measured for the individual profiles averaged over a few minutes. It is found that the ratios follow normal distributions, where the abnormal mode has a greater typical width than the normal mode, indicating that the abnormal mode is less stable than the normal mode. Our data show that 84.9% of the time for PSR B0329+54 was in the normal mode and 15.1% was in the abnormal mode. From the two passages of eight-day quasi-continuous observations in 2004, supplemented by the daily data observed with the 15 m telescope at 610 MHz at Jodrell Bank Observatory, the intrinsic distributions of mode timescales are constrained with the Bayesian inference method. It is found that the gamma distribution with the shape parameter slightly smaller than 1 is favored over the normal, log-normal, and Pareto distributions. The optimal scale parameters of the gamma distribution are 31.5 minutes for the abnormal mode and 154 minutes for the normal mode. The shape parameters have very similar values, i.e., 0.75{sup +0.22}{sub -0.17} for the normal mode and 0.84{sup +0.28}{sub -0.22} for the abnormal mode, indicating that the physical mechanisms in both modes may be the same. No long-term modulation of the relative intensity ratios was found for either mode, suggesting that the mode switching was stable. The intrinsic timescale distributions, constrained for this pulsar for the first time, provide valuable information to understand the physics of mode switching.
Chen, J. L.; Wang, N.; Liu, Z. Y.; Yuan, J. P. [Xinjiang Astronomical Observatory, 150, Science-1 Street, Urumqi, Xinjiang, 830011 (China); Wang, H. G. [Center for Astrophysics, Guangzhou University, Guangzhou 510006 (China); Lyne, A. [University of Manchester, Jodrell Bank (United Kingdom); Jessner, A.; Kramer, M., E-mail: firstname.lastname@example.com [Max-Planck Institute for Radio Astronomy, Bonn 53121 (Germany)
Prothrombotic abnormalities in childhood ischaemic stroke.
Childhood ischaemic stroke, incorporating arterial ischaemic stroke and cerebral sinus venous thrombosis, is associated with significant morbidity and mortality in children. The majority of cases in children present with well-recognised risk factors. The appreciation of the role prothrombotic abnormalities have in disease states is developing rapidly. Prothrombotic abnormalities are abnormalities of the coagulation system, fibrinolytic system, endothelial cells or platelets that lead to a reduced threshold for pathological thrombus formation. Our understanding of the role of prothrombotic abnormalities in childhood ischaemic stroke is increasing and has a direct bearing on the development of effective management and prevention strategies. We provide a brief background of prothrombotic abnormalities and review the available literature on prothrombotic markers in childhood ischaemic stroke. Overall, prothrombotic abnormalities have been identified in 20-50% of children presenting with AIS and 33-99% of children with cerebral sinus venous thrombosis. There appear to be a number of associations emerging including an increased frequency of factor V Leiden mutation, elevated lipoprotein (a), protein C deficiency and antiphospholipid antibodies in children presenting with arterial ischaemic stroke. The pathogenic role of prothrombotic abnormalities as predisposing to initial and recurrent childhood ischaemic stroke is becoming increasingly evident. The impact on treatment, however, will only be clarified with carefully designed, multi-institutional prospective studies. PMID:16039697
Barnes, Chris; Deveber, Gabrielle
Sleep Physiology, Abnormal States, and Therapeutic Interventions
Sleep is essential. Unfortunately, a significant portion of the population experiences altered sleep states that often result in a multitude of health-related issues. The regulation of sleep and sleep-wake cycles is an area of intense research, and many options for treatment are available. The following review summarizes the current understanding of normal and abnormal sleep-related conditions and the available treatment options. All clinicians managing patients must recommend appropriate therapeutic interventions for abnormal sleep states. Clinicians' solid understanding of sleep physiology, abnormal sleep states, and treatments will greatly benefit patients regardless of their disease process.
Wickboldt, Alvah T.; Bowen, Alex F.; Kaye, Aaron J.; Kaye, Adam M.; Rivera Bueno, Franklin; Kaye, Alan D.
Abnormalities of the gallbladder, clinical effects.
The aim of this review of the literature was to present and discuss the anatomical and embryological basis of congenital abnormalities of the gallbladder, based on a case of volvulus. In the rare cases of ectopic gallbladder, diagnosis of a biliary disease could be difficult. In such cases surgery can also be dangerous, especially when it is associated with abnormalities of the intra-hepatic biliary and vascular tree. This study, based on the embryology of the extra hepatic bile duct, focused on the most frequent gallbladder abnormalities to keep them i