bluuebunny/crossref_metadata_2025 huggingface dataset:
Inclusive interface design for seniors: Image‐browsing for a health information context
Authors: Given Lisa M. , Ruecker Stan , Simpson Heather , Sadler Elizabeth (Bess) , Ruskin Andrea
Published: July 2007

This study explores an image‐based retrieval interface for drug information, focusing on usability for a specific population—seniors. Qualitative, task‐based interviews examined participants' health information behaviors and documented search strategies using an existing database (www.drugs.com) and a new prototype that uses similarity‐based clustering of pill images for retrieval. Twelve participants (aged 65 and older), reflecting a diversity of backgrounds and experience with Web‐based resources, located pill information using the interfaces and discussed navigational and other search preferences. Findings point to design features (e.g., image enlargement) that meet seniors' needs in the context of other health‐related information‐seeking strategies (e.g., contacting pharmacists).
Neural tube defects, micronutrient deficiencies, and Helicobacter pylori: A new hypothesis
Authors: Felkner Marilyn , Suarez Lucina , Liszka Beata , Brender Jean D. , Canfield Mark
Published: July 2007

BACKGROUND: Previous findings for the Texas Neural Tube Defects Project suggested that while maternal access to nutrients is adequate, bioavailability of nutrients to the fetus is compromised in NTD‐affected pregnancies. Helicobacter pylori could cause nutrient loss to the fetus. Folate, B12, and ferritin are depleted in H. pylori infection; these same deficiencies are related to NTD risk. METHODS: Using H. pylori IgG ELISA Test System, we tested for H. pylori serum antibodies in participants in the population‐based case‐control study component of the Texas Neural Tube Defect Project conducted along the Texas‐Mexico border. Case‐women had pregnancies affected by NTD (anencephalus, spina bifida, encephalocele) and resided and delivered in one of the 14 Texas‐Mexico border counties from 1995 through 2000. Control‐women were study area residents delivering normal live births during the same period. RESULTS: Of 225 case‐ and 378 control‐women, 103 cases and 156 controls provided questionnaire and H. pylori antibody data. H. pylori seropositivity was modestly associated with NTD‐affected pregnancies (OR 1.4; 95% CI: 0.8–2.4). ORs of 2.0 or greater were seen in women younger than age 25 and with less than 7 years education. CONCLUSIONS: Our findings intimate that H. pylori could play a role in NTD causation in certain populations. While results did not provide compelling support for this proposal, subgroup findings prompt us to advocate an evaluation of this hypothesis in developing nations among populations with higher prevalence of H. pylori, marginal nutrient intake, and young childbearing age. Birth Defects Research (Part A), 2007. © 2007 Wiley‐Liss, Inc.
Three‐dimensional immobilization of β‐galactosidase on a silicon surface
Authors: Betancor Lorena , Luckarift Heather R. , Seo Jae H. , Brand Oliver , Spain Jim C.
Published: July 2007

Many alternative strategies to immobilize and stabilize enzymes have been investigated in recent years for applications in biosensors. The entrapment of enzymes within silica‐based nanospheres formed through silicification reactions provides high loading capacities for enzyme immobilization, resulting in high volumetric activity and enhanced mechanical stability. Here we report a strategy for chemically associating silica nanospheres containing entrapped enzyme to a silicon support. β‐galactosidase from E. coli was used as a model enzyme due to its versatility as a biosensor for lactose. The immobilization strategy resulted in a three‐dimensional network of silica attached directly at the silicon surface, providing a significant increase in surface area and a corresponding 3.5‐fold increase in enzyme loading compared to enzyme attached directly at the surface. The maximum activity recovered for a silicon square sample of 0.5 × 0.5 cm was 0.045 IU using the direct attachment of the enzyme through glutaraldehyde and 0.16 IU when using silica nanospheres. The immobilized β‐galactosidase prepared by silica deposition was stable and retained more than 80% of its initial activity after 10 days at 24°C. The ability to generate three‐dimensional structures with enhanced loading capacity for biosensing molecules offers the potential to substantially amplify biosensor sensitivity. Biotechnol. Bioeng. 2008;99: 261–267. © 2007 Wiley Periodicals, Inc.
Novel hyaluronic acid (HA) coated drug carriers (HCDCs) for human breast cancer treatment
Authors: Hyung Woochan , Ko Hyunjoo , Park Joseph , Lim Eunkyung , Park Sung Bae , Park Young‐Joon , Yoon Ho Geun , Suh Jin Suck , Haam Seungjoo , Huh Yong‐Min
Published: July 2007

Hyaluronic acid (HA) coated drug carriers (HCDCs) were successfully synthesized by chemical conjugation method for targeted delivery of doxorubicin (DOX) as a prototype anticancer drug to CD44 expressed human breast cancer cell. From XPS analysis, the HCDCs by conjugation methods demonstrated the superior HA fixation amount and colloidal stability compared with the nanoparticles by nanoprecipitation. The cytotoxicity of the HCDCs formulation accessed by the MTT assay against the higher CD44 expressed cell line (MDA‐MB‐231) and lower CD44 expressed cell line (ZR‐75‐1) human breast cancer cell lines demonstrated that the HCDCs formulation exhibited excellent tumoricidal effect and their affinity to cancer cells was predominant. The in vitro drug release profile of the HCDCs showed sustained release behavior and after 14 days, 80% of the encapsulated DOX was released due to a high release rate of DOX from HCDCs. We synthesized that HCDCs have therapeutic potentials of cancer as a target specific fashion by increasing the tumoricidal efficacy of targeted cancer cells while reducing their cytotoxicity of non‐targeted cells to minimize the side effect. Biotechnol. Bioeng. 2008;99: 442–454. © 2007 Wiley Periodicals, Inc.
Explaining the impact of ISO 14001 on emission performance: a dynamic capabilities perspective on process and learning
Authors: Russo Michael V.
Published: July 2007

I draw upon the dynamic capability model to explore how new process standards influence the ability of manufacturing facilities to improve environmental performance by reducing toxic emissions. The process standards studied are the ISO 14001 environmental management standards, in use since 1996. Hypotheses are developed to account for how early adoption of ISO 14001 and experience with the standards influence emission levels. These hypotheses are tested using a large sample of electronics manufacturing facilities and data from 1996 through 2001. Consistent with theoretical expectations, analyses show that being one of the first facilities to adopt ISO 14001 was associated with lower emissions. Further, a separate effect is due to experience: the longer a facility operated under ISO 14001, the lower its emissions. The paper discusses the implications of these results for theory and policy development. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.
Fungiform taste bud degeneration in C57BL/6J mice following chorda‐lingual nerve transection
Authors: Guagliardo Nick A. , Hill David L.
Published: July 2007

Taste buds are dependent on innervation for normal morphology and function. Fungiform taste bud degeneration after chorda tympani nerve injury has been well documented in rats, hamsters, and gerbils. The current study examines fungiform taste bud distribution and structure in adult C57BL/6J mice from both intact taste systems and after unilateral chorda‐lingual nerve transection. Fungiform taste buds were visualized and measured with the aid of cytokeratin 8. In control mice, taste buds were smaller and more abundant on the anterior tip (<1 mm) of the tongue. By 5 days after nerve transection taste buds were smaller and fewer on the side of the tongue ipsilateral to the transection and continued to decrease in both size and number until 15 days posttransection. Degenerating fungiform taste buds were smaller due to a loss of taste bud cells rather than changes in taste bud morphology. While almost all taste buds disappeared in more posterior fungiform papillae by 15 days posttransection, the anterior tip of the tongue retained nearly half of its taste buds compared to intact mice. Surviving taste buds could not be explained by an apparent innervation from the remaining intact nerves. Contralateral effects of nerve transection were also observed; taste buds were larger due to an increase in the number of taste bud cells. These data are the first to characterize adult mouse fungiform taste buds and subsequent degeneration after unilateral nerve transection. They provide the basis for more mechanistic studies in which genetically engineered mice can be used. J. Comp. Neurol. 504:206–216, 2007. © 2007 Wiley‐Liss, Inc.
Localization of arm representation in the cerebral peduncle of the non‐human primate
Authors: Morecraft Robert J. , McNeal David W. , Stilwell‐Morecraft Kimberly S. , Dvanajscak Zeljko , Ge Jizhi , Schneider Preston
Published: July 2007

Motor deficit severity and the potential for recovery in patients with brain injury depend on the integrity of descending corticofugal projections. Clinical assessment of these conditions following subtotal brain trauma requires a comprehensive understanding of the anatomical structures involved in the lesion as well as those structures that are spared. To assist in this endeavor, we investigated motor fiber organization in the crus cerebri of the cerebral peduncle (ccCP) in the rhesus monkey. Fibers originating from the arm representations of the primary (M1), supplementary (M2), rostral cingulate (M3), caudal cingulate (M4), dorsolateral pre‐ (LPMCd) and ventrolateral pre‐ (LPMCv) motor cortices were studied. The projections from the frontal and cingulate motor cortices formed descending longitudinal bundles that occupied the medial three‐fifths of the ccCP at superior and middle levels. Although considerable overlap characterized these corticofugal projections, a general topography was discernable. Fibers from M1 and M4 occupied the central subsector of the ccCP, and fibers from M3 resided medially. The main distribution of LPMCd, LPMCv, and M2 fibers occupied the centromedial region and overlapped extensively. Progressing inferiorly, all fiber bundles in the central and centromedial sectors gradually extended medially, and overlap increased. A common location of fiber passage occurred at the midbrain‐pontine isthmus where all of the fiber bundles overlapped. Our findings indicate that the widespread distribution of corticofugal motor projections may account for the favorable levels of motor recovery that accompany subtotal midbrain injury. At superior and mid‐levels of the ccCP anteromedial lesions may disrupt projections from M3, whereas anterolateral lesions may disrupt projections from M1 and M4. Fibers from M2, LPMCv, and LPMCd may be compromised to some degree in both situations. The compact and commixed nature of motor fiber organization at inferior levels and the midbrain‐pontine isthmus suggests a vulnerable region of passage for comprehensive disruption of frontal and cingulate corticofugal projection fibers. J. Comp. Neurol. 504:149–167, 2007. © 2007 Wiley‐Liss, Inc.
Midline and intralaminar thalamic connections with the orbital and medial prefrontal networks in macaque monkeys
Authors: Hsu David T. , Price Joseph L.
Published: July 2007

Although the midline and intralaminar thalamic nuclei (MITN) were long believed to project “nonspecifically,” they are now known from rat studies to have restricted connections to the prefrontal cortex. This has not been studied thoroughly in primates, however, and it is not known how MITN are associated with the “orbital” and “medial” prefrontal networks. This study examined the connections of MITN in cynomolgus monkeys (Macaca fascicularis). Experiments with retrograde and anterograde tracer injections into the orbital and medial prefrontal cortex (OMPFC) showed that MITN are strongly connected with the medial prefrontal network. The dorsal nuclei of the midline thalamus, including the paraventricular (Pa) and parataenial nuclei (Pt), had heavy connections with medial network areas 25, 32, and 14c in the subgenual region. Areas 13a and 12o, which are associated with both networks, were strongly connected with the Pt and the central intermedial nucleus, respectively. Otherwise, orbital network areas had weak connections with MITN. Anterograde tracer injections into the dorsal midline thalamus resulted in heavy terminal labeling in the medial prefrontal network, most notably in areas ventral to the genu of the corpus callosum (25, 32, and 14c), but also in adjacent areas (13a and 13b). Retrograde tracer injection into the dorsal midline labeled similar areas. The medial network, particularly the subgenual region, is involved in visceral and emotional control and has been implicated in mood disorders. The strong connections between the subgenual cortex and the Pa provide a pathway through which stress signals from the Pa may influence these prefrontal circuits. J. Comp. Neurol. 504:89–111, 2007. © 2007 Wiley‐Liss, Inc.
A rate of convergence for monotone finite difference approximations to fully nonlinear, uniformly elliptic PDEs
Authors: Caffarelli Luis A. , Souganidis Panagiotis E.
Published: July 2007

We obtain an algebraic rate of convergence for monotone and consistent finite difference approximations to Lipschitz‐continuous viscosity solutions of uniformly elliptic partial differential equations. © 2007 Wiley Periodicals, Inc.
Synthesis of general impedance with simple dc/dc converters for power processing applications
Authors: Liu J. C. P. , Tse C. K. , Poon N. K. , Pong M. H. , Lai Y. M.
Published: July 2007

A general impedance synthesizer using a minimum number of switching converters is studied in this paper. We begin with showing that any impedance can be synthesized by a circuit consisting of only two simple power converters, one storage element (e.g. capacitor) and one dissipative element (e.g. resistor) or power source. The implementation of such a circuit for synthesizing any desired impedance can be performed by (i) programming the input current given the input voltage such that the desired impedance function is achieved, (ii) controlling the amount of power dissipation (generation) in the dissipative element (source) so as to match the required active power of the impedance to be synthesized. Then, the instantaneous power will be automatically balanced by the storage element. Such impedance synthesizers find a lot of applications in power electronics. For instance, a resistance synthesizer can be used for power factor correction (PFC), a programmable capacitor or inductor synthesizer (comprising small high‐frequency converters) can be used for control applications. Copyright © 2007 John Wiley & Sons, Ltd.
Heat Transfer in Electric Arc Chamber of Linear Plasmatron
Authors: Anshakov A. S. , Lukashov V. P. , Fokin V. N.
Published: July 2007

Classification and performance capability of electric are linear plasmatrons are presented. The results of investigation into convective and radiative heat transfer in the discharge channel of a plasmatron are reported. The radiative heat transfer dominates both in the structure of heat losses and in the formation of discharge volt‐ampere characteristic at the initial region of the flow. Relations to calculate heat losses by radiation are given. Radiative convective interaction at the arc boundary is shown to play a substantial role for high‐current discharges stabilized by axial vortex gas flow. It is shown that the calculation of convective heat transfer at the turbulent region of the flow may be carried out by flow averaged parameters.
Radiative‐Convective Heat Transfer in Discharge Chamber at Turbulent Gas Flow
Authors: Rubtsov N. A. , Ogurechnikova N. M.
Published: July 2007

In the paper radiative‐convective heat transfer in electric arc flowed through by Ar in the discharge chamber is studied. The equation system for heat, mass and momentum transfer in boundary layer approximation is considered, and the turbulence model with radiation pulsation and electrodynamic values is suggested.

By solution of the equation system with the help of finite differences method distributions of temperature, heat flows and turbulent transfer coefficients over chamber length were obtained. The radiation and turbulence influence on the electric arc characteristics is analysed.
Ionization Equilibrium in Nonideal Alkali and Noble Gas Plasmas
Authors: Redmer R. , Rother T. , Schmidt K. , Kraeft W. D. , Röpke G.
Published: July 2007

Using the method of thermodynamic Green functions, a generalized Saha equation is derived which accounts for different non‐ideality effects, as, e. g., interaction between charged particles and neutral composites (atoms). The degree of ionization was calculated for the alkali metals Li—Cs and for Xe in a wide n‐T range. Furthermore, the chemical potential μ and the pressure p were determined for these elements.
Generalized Susceptibilities for a Wall‐Stabilized Electric Are Displacement
Authors: Ramos‐Barrado J. R. , Galán‐Montenegro P.
Published: July 2007

Complex susceptibilities for are displacement produced by an intermittent HF irradiation or by a time‐dependent transverse magnetic field, are defined. The analytical character of these susceptibilities is established from the development of its Kramers‐Kronig relations. Some experimental results for an are in a transverse magnetic field are shown.
The Impact of Different CO Admixtures on the Electron Kinetics in Collision Dominated RF He/CO Bulk Plasmas
Authors: Dilonardo M. , Capitelli M. , Gorse C. , Wilhelm J. , Winkler R.
Published: July 2007

Electron energy distribution functions and mean collision frequencles for the uniform bulk plasma of established rf discharges in He/CO have been obtained by solving the time dependent Boltzmann equation. The results, which are of importance for plasma processing and laser technology, show that already small CO admixtures to He remarkably changes the periodic behaviour of the energy distribution of the electrons by drastical enhancement of the collisional energy dissipation effectiveness in the mixture. These changes can be interpreted on the basis of a lumped energy dissipation frequency in all electron collisions which is determined by the atomic data of the electron collision processes as well as by the admixture fractions and which drastically increases with increasing CO admixture. The degree of modulation of the energy distribution in different parts of the electron energy space and its population on the time average at higher energies are determined by the relation between the rf field frequency and the mentioned lumped energy dissipation frequency.
Burning Voltage in Atmospheric and Vacuum Short Arcs of Vanishing Length
Authors: Vogel N.
Published: July 2007

The stepwise increase of the burning voltage of short break arcs has been found not only in a gas but also in vacuum. It is suggested that the effect is associated with the occurrence of a positive anode fall which enhances ionisation phenomena near the anode. This view is supported by the simultaneous registration of arc current, burning voltage, light emission from the anode region, of spectral lines of ions, atoms and continuum from the near anode plasma. The phenomena occur beyond a critical gap distance which can be related to the characteristic geometry of the discharge.
Vortex Flows Induced by Electric Arc
Authors: Engelsht V. S. , Nevelev D. V. , Zhajnakov A.
Published: July 2007

In this paper a mathematical model of the stationary electric arc is made on the basis of solution of radiation gas dynamics two‐dimensional equations. Numerical analysis of electric arc with small length, depending on current force, distance between electrodes, electrode behaviour and geometry, type and expenditure amount of plasma forming gas, is carried out. It is shown that under some definite conditions electric arc induces toroidal gas vortexes playing an important part in the process of heat and mass transfer in electric arc plasma.
A Second‐Order Theory for Electron Plasma Solitary Waves in a Cylindrical Waveguide
Authors: Ghosh B.
Published: July 2007

To describe the long time asymptotic behaviour of weakly nonlinear plasma waves propagating in a strongly magnetized plasmafilled cylindrical waveguide the usual KDV equation which is first order in wave amplitude is extended to second order including the effects of finite temperature, mobile ions and giving a proper treatment to the radial co‐ordinate for all possible modes of propagation. The second‐order effects on the first‐order solitary wave profile, phase speed and first order correction to the wavelength are all determined and discussed.
Nonideality Effects in Plasmas with Multiply Charged Ions
Authors: Ebeling W.
Published: July 2007

Thermodynamic functions, energy level shifts, ionization equilibria and ionization kinetics for plasmas containing ions with higher charges are investigated. It is shown that multiply charged ions lead to an essential amplification of nonideality effects.
Basic Mechanisms in Plasma Etching
Authors: Deutsch H. , Kersten H. , Rutscher A.
Published: July 2007

A summary is given on the temperature dependence and basic processes in dry etching. The basic processes as Physical and Chemical Sputtering and Surface Film Etching completed by ion or electron stimulation of gas‐surface reactions and combined with adsorption and desorption are used in modelling different types of etch characteristics. Of special interest are non‐monotoneous characteristics. For some typical examples a comparison between measured and calculated curves is given which permit the determination of some kinetic parameters as activation energies and residence times.
Effects of Trapped Ions on the Nonlinear Propagation of Modified Electron Acoustic Waves
Authors: Das U. N. , Goswami K. S. , Bujarbarua S.
Published: July 2007

Effects of trapped ions on the nonlinear propagation of modified electron acoustic waves in an unmagnetized plasma consisting of one cold and one hot components of electrons and one single species of hot ions, have been investigated in this paper. It has been shown that while rarefactive soliton solution exists in such a plasma, no double layer solution has been found to exist. The potential, velocity and width of the soliton have been calculated.
Determination of NIP‐Parameters in Terms of the Scattering Spectra Integral Characteristics
Authors: Adamjan V. M. , Tkachenko I. M.
Published: July 2007

A new plasma diagnostics method is described, based on the connection between equilibrium plasma parameters (density, temperature, electronic static local field correction, static dielectric permeability, etc.) and the frequency moments of laser scattering and electron‐energy loss spectral intensities.
Hβ‐Line Profile Measurements in Optical Discharges
Authors: Uhlenbusch J. , Viöl W.
Published: July 2007

In the electrical field of a focused beam of a high‐power DC discharge multikilohertz repetition rate Q‐switched CO2 laser a so called pulsed optical discharge (POD) can be sustained. Applying laser pulses with max. 104 pulses/s, 50 mJ/pulse, pulse length 0.2 μs, average power 500 W and peak power 250 kW, the charge carrier density of a hydrogen plasma at a pressure of several MPa produced during the laser pulse is enhanced up to about the cut‐off density at λL = 10.6 μm (≃ 1025 m−3) and the electron temperature is increased to about 105 K. The non‐ideality factor reaches about 0.2. The calibrated line intensity of the Balmer Hβ was monitored by means of an optical multichannel analyzer system with spatial, frequency and time resolution. The measurements yield Stark‐broadened Hβ‐line profiles from which, assuming partial local thermal equilibrium, the electron temperature and density can be derived. The measured asymmetry of the Hβ‐line is in rough agreement with theoretical predictions available in literature.
Stark Shift and Broadening of Hydrogen Spectral Lines
Authors: Günter S.
Published: July 2007

A Green's function approach as a many‐body treatment of the optical properties of dense plasmas is used to calculate profiles of Lyman‐α and Balmer‐α lines of hydrogen. The electron collisions are treated by an impact‐approximation. Because of a fully quantum mechanical treatment of electron collisions the integrals for shift and width do not diverge. In spite of that, we have to cut off these integrals because of an overestimation of the strong collision contributions. Effects of ions are incorporated into the Green's function concept in a quasistatic approximation using Hooper's distribution functions.
Reflectivity of Dense Plasma
Authors: Mintsev V. B. , Zaporogets Yu. B.
Published: July 2007

The results of the measurements of the reflection coefficient of the laser beam with λ = 1.06 μm from dense xenon plasma at P = 1.6–17 GPa and silicon under shock loading up to the insulator‐metal transition region at P = 10‐‐46 GPa are presented. Some properties of the optical and explosive experimental setup are described. The reflection picture and comparison of the dense plasma models with the experimental data are discussed.
The Regular Truncation Scheme of the BBGKY Hierarchy Equations for the Multi‐Component Weakly Non‐Ideal Plasma
Authors: Shapiro M. M. , Parsadanyan S. M. , Tabachnik Yu. V. , Furgel I. A. , Golosov N. S.
Published: July 2007

A regular truncation scheme in which the divergencies characteristic of the Debye truncation are removed by taking into account the shall‐range correlations. As a result, the two radii of screening the Debye radius D and √2 D appear in plasma which is not symmetrical as to its particle charges. The criterion of the applicability of this approach relates the plasma parameter to the potential depth of unlike‐charged particles interaction.
TOkamak Edge Studies with A 2D Multifluid Code
Authors: Neuhauser J. , Braams B. , Krech M. , Ritschel U. , Schneider W. , Wunderlich R.
Published: July 2007

The Garching version B2CODE87 of the multifluid tokamak edge code of B. Braams is used for edge scoping studies in a quadrupole‐type x‐point geometry representative for open divertor configurations like ASDEX‐Upgrade or ITER. Two selected topics of common interest are treated here: Edge density limit in comparison with analytic models and impurity transport in the edge region. With respect to impurity transport the results of simpler models are qualitatively recovered for various nickel source scenarios. On the other hand, the simple edge density limit predicted by analytic models for pure hydrogen plasma is not recovered. Including impurity radiation, a modified limit is obtained.
MOdelling of Impurity Generation and Transport in Scrape‐Off Layers
Authors: Kawamura T. , Ono T. , Yoshida H.
Published: July 2007

The scrape‐off layer plasma is simulated with a 2‐dimensional fluid plasma code (SLIM) and a Monte Carlo neutral transport code (DEGAS) where the two codes are made runs iteratively until almost stable results are obtained. The geometry of the scrape‐off layer is referred to a toroidal pump limiter system. In the scrape‐off plasma thus obtained, ionization of neutral impurity particles ejected from the first wall, drift motion of charged impurities along the magnetic field lines and random diffusion across the magnetic field lines are simulated by a Monte Carlo method using atomic reaction rates of relevant processes and transport coefficients in the scrape‐off layer. From the statistics on calculations of destination of many impurity particles, the screening efficiency of the scrape‐off layer for impurity penetration into the core plasma, the impurity redeposition rate on the first wall, the exhaust efficiency of impurities are quantitatively analyzed.
Stationary Study of the Boundry Plasma of Large Tokamaks with Divertor
Authors: Galkowski A. , Zagorski R.
Published: July 2007

The hydrogen plasma and impurity flows parallel to the magnetic field lines in a collissional tokamak scrape‐off layer are numerically investigated. The physical model is developed on the basis of electron‐ion fluid equations for hydrogen plasma and rate equations for impurities. A complex model valid for arbitrary concentration of impurity ions based on 21‐moment Grad approximation is used to describe transport coefficients and thermal forces. Plasma interactions with neutral particles recycling at the divertor plate are taken into account. Steady state spatial profiles of the plasma and impurity (0, C) parameters are computed using the time relaxation method Possibility of helium exhaust is investigated.
The use of Langmuir Probe Methods for Plasma Diagnostic in Middle Pressure Discharges
Authors: David P. , Sicha M. , Tichy M. , Kopiczynski T. , Zakrzewski Z.
Published: July 2007

The article attempts to summarize the most important knowledge about the analysis of a Langmuir probe at middle pressures. First it briefly reviews the recent theories which deal with interpretation of Langmuir probe data at such conditions and then it applies the theory to the measurements in a Neon discharge at pressures 1.86 and 2.46 kPa. The charged particle density and the electron temperature obtained from the same probe data using different theories is compared against each other and a satisfactory agreement is obtained. The recommended procedure of probe data interpretation is given at the end of the paper.
Propagation of a Surface Wave Sustaining a Plasma Column at Atmospheric Pressure
Authors: Moisan M. , Pantel R. , Hubert J.
Published: July 2007

The propagation of a microwave surface wave is observed along a filamentary argon plasma at atmospheric pressure. The plasma is completely sustained by the propagating wave. Although the collision frequency is about ten times the wave angular frequency, the electron density is high enough so that the resulting conductivity of the plasma filament permits the propagation of the surface wave. The wave dispersion and attenuation diagrams calculated using a cold plasma linear dielectric description are in relatively good agreement with the experimental results.
Kinetic Approach to Reaction and Diffusion in Many‐Particle Systems
Authors: Klimontovich Yu. L. , Schlanges M. , Bornath T.
Published: July 2007

A derivation of hydrodynamic equations which describe diffusion in connection with reaction processes in many‐particle systems is given on the basis of quantum kinetic theory. For this purpose kinetic equations are derived for a quantum gas with chemical reactions. Following Grad's method in a linear approximation reaction‐diffusion equations can be obtained with explicite expressions for the diffusion and reaction rate coefficients. The influence of nonideality effects in reaction‐diffusion equations is discussed.
Parametric Excitation of Electron‐Acoustic Mode in a Plasma of Two‐Temperature Electrons
Authors: Dwivedi C. B. , Asthana Meenu , Guha S.
Published: July 2007

Using hydrodynamical model of the two‐electron‐temperatere plasma, the analytical investigation of parametric instability of electron‐acoustic wave has been made. It is found that the growth rate decreases with increasing concentration ratio of the hot to the total electrons nh0/n0. The growth rate is found to be more for
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On a New Method of Determining Collision Rates for Ionization by Means of Pair Collisions and Stepwise Ionization
Authors: Wilke C. , Kablan N. , Deutsch H.
Published: July 2007

We report on a new method to determine the collision rates for ionization by means of pair collisions (Paarstöße) and stepwise ionization, respectively. This method is based on the experimental and theoretical study of the dynamical behaviour (impedance behaviour) of the positive column of a low‐current discharge at low pressure.
Absolute Electron Impact Cross Sections for Single Ionization of Metastable Atoms of H, He, Ne, Ar, Kr, Xe and Rn
Authors: Margreiter D. , Deutsch H. , Märk T. D.
Published: July 2007

Cross sections for single ionization of metastable atoms of H, He, Ne, Ar, Kr, Xe and Rn by electrons with impact energy E (threshold < E < 200 eV) are determined using a recently developed semiclassical formula. The formula consists of an energy dependent term (classical binary encounter approximation) and a term containing the weighted sum of the squared radii of maximum charge density of the outer electron subshells (Born Bethe approximation). Although this formula was originally devised and applied for ground state atoms, a comparison of the present calculations with previous calculations and measurements indicates that this formula can also be used successfully in case of metastable atoms.
Stationary Striations due to Interaction of Two Ionization Waves in Xenon Glow Discharge
Authors: Maruyama T. , Nishina S. , Kitamura H. , Itagaki K. , Mizuochi H.
Published: July 2007

Experimental observations on stationary striations in the positive column of xenon discharge are reported. Stationary striations are observed when two ionization waves exist simultaneously in the positive column at low pressure and high current region. These stationary striations are caused by nonlinear interference of two backward ionization waves of which frequencies are either equal or are in the ratio 1:2. The spatial intervals for the striated pattern are equal to the reciprocal of the difference between the wave‐numbers of two ionization waves.
Statistics of Ignition Processes in ac Plasma Displays
Authors: Roepcke J. , Zahn R.‐J.
Published: July 2007

The statistics of the ignition behaviour of discharge cells in ac plasma displays and interaction processes occurring between several ignited cells are described and interpreted with a view to basic problems of gas discharge and solid state physics. For the statistical evaluation of ignition lag values recorded by means of a computer controlled equipment the Laue distribution is used.
MAgnetically Stabilized Plasma Sources of Getter Films
Authors: Karpov D. , Saksagansky G.
Published: July 2007

Modern state and ways of development of getter film plasma sources with the magnetic stabilization (GFPS) are considered. The description of physical mechanism of the magnetic stabilization, GFPS constructions and technical characteristics, their confronting parameters and the main factors defining usage perspectives is presented.
Model Experiments on Study of the First Wall Erosion Under the Action of Vacuum Arcs
Authors: Karpov D. , Saksagansky G. , Paszti F.
Published: July 2007

With d. c. vacuum arc discharges the dependence of cathode erosion rate on the transverse magnetic field induction is non‐linear. At first erosion rate rises with the magnetic induction and then drops. The maximum erosion rate value corresponds to the magnetic induction interval (50 – 115) · 10−4 T. The range of the vacuum arc discharge maximum stability also corresponds to the same interval. When the magnetic induction rises from 2 · 10−3 up to 1.1 · 10−2 T (I = 50 A), the erosion products angular distribution monotoneously narrows and with further magnetic ficld enhancement it abruptly widens. Current rise results in increasing extension of erosion products angular distribution. Asymmetry of erosion products angular distribution does not depend on the direction of the magnetic induction vector and gradually vanishes when the magnetic induction rises up to 1 · 10−2 T and higher.
ELectron Collision Rates and Transport Coefficients of a Weakly Ionized dc Plasma in Ar/Sih4‐Mixtures
Authors: Pfau S. , Winkler R.
Published: July 2007

The paper deals with electron kinetics of a Ar/SiH4 dc plasma, using the stationary and spatially uniform Boltzmann equation. The solution of this kinetic equation has been obtained by applying higher order Legendre polynomial expansion of the electron velocity distribution. For varying mixture composition the energy distribution and relevant macroscopic quantities as mean energy, drift velocity, rate coefficients for excitation, dissociation and ionization and relevant energy transfer rates for these processes have been calculated. In particular, it has been found that a most effective activation of the feed gas occurs for SiH4 admixtures in the range from 5 to 10 per cents.
New Method for Determination of Excited State Lifetime
Authors: Becker W. , Behnke J. , Kagel H. , Leven R.
Published: July 2007

The use of optical methods for the detection of plasma waves requires the consideration of propagation properties of waves as well as the excited state lifetimes. In case of known propagation properties of waves the excited state lifetime can be determined from the frequency‐dependent decrease of the wave amplitude. The proposed technique represents a new independent method for the determination of excited state lifetimes. This paper deals with first studies on excited state lifetime based on the frequency response of the amplitude of free streaming electron waves in He‐dc‐discharges.

The results demonstrate the correctness of the idea about the decrease of wave signal in consequence of excited state lifetime.
Emissionspectroscopic Investigation of Bci3 Discharges
Authors: Breitbarth F.‐W. , Ducke E.
Published: July 2007

Radiofrequency discharges in neat BCI3 exhibit 3 broad molecular emissions with intensity maxima at about 305, 350, and 480 nm. The 350 nm system consists of a progression of bands with an average separation of about 130 cm−1. All three emissions have an identical excitation kinetics in pulse discharges and are, therefore, believed to originate from the same emitter. Arguments are given that the emitter might be electronically excited BCl2.

The dominant process of BCl(A) formation in neat BCl3 at low r.f. power is shown to be direct electron impact excitation of BCl(X). A transient excess population of BCl(A1II) in BCl3/Ar discharges is explained as due to an energy transfer from argon metastables.
Emissionspectroscopic Investigations On SiCl4 and Ccl4Si Plasmas for Etching Processes
Authors: Tiller H.‐J. , Sameith S.
Published: July 2007

The emission spectra of SiCl4‐ and CCl4/Si radio frequency discharges are analyzed. The broad emission between 310 and 360 nm is attributed to SiCl2 (Ã1B1 ‐ X1A1‐transition). The vibrational frequencies in the 1B1 state (ṽ2′) and in the 1A1 state (ṽ2″) and the energy difference between the vibrational ground states of the electronic 1B1 and 1A1 states are estimated.

Further emission analysis results in an assignment of the 400 nm system to SiCl3 or SiCl3+ resp. Experimental results of the SiCl (B2Σ− – XΠr) and SiCl (B2δ – X2Πr) emission with high resolution are given.
Energetic Characteristics of Oxygen Plasma
Authors: Arutunyan G. G. , Babalyants L. P.
Published: July 2007

A low‐temperature oxygen plasma is studied using the thermocouple, probe and spectral method in the range of 2–8 Torr pressure, 30–100 mA discharge currents, 0, 5, 10 m/s pumping velocity. The gas temperature, concentrations of electrons and oxygen atoms in the 3p5P state, and the longitudinal electric field are measured. Radial distributions of gas temperature and electron concentration are obtained. Ranges of pressures and currents are found in which considerable increases in electric field, discharge voltage, temperatures of gas and electrons are observed at pumping switched on. An estimate of the rate constant of the steplike ionization through the O2(a1Δg) state is given. The concentration of atomic oxygen in the ground state and excitation constant of the triplet O(3p5P) by electron impact are obtained from the solution of the balance equations and our experimental data.
Ordinary‐wave Propagation in Mirror‐Confined Plasmas
Authors: Saxena A. C. , Gupta G. P. , Rohatgi V. K.
Published: July 2007

The non‐relativistic dispersion relation for ordinary‐waves propagating in a hot plasma confined by magnetic mirrors is derived under small gyroradius approximation. The hot electron velocity distribution is modelled by a bi‐Maxwellian with a cutoff at the loss‐cone boundary. The dispersion relation is analyzed from propagation point of view. It is seen that the presence of loss cones in the electron velocity distribution reduces the high temperature effects in the ordinary‐wave propagation characteristics.
Gravitational Instability of a Two‐Component Viscous Plasma with Finite Conductivity Flowing Through a Porous Medium with Fir Corrections
Authors: Vaghela D. S. , Chhajlani R. K.
Published: July 2007

The gravitational instability of a two component plasma is studied to include the simultaneous effects of collisions, gyroviscosity, finite conductivity, viscosity and porosity of the medium within the framework of two‐fluid theory. From linearized equations of the system, using normal mode analysis, the dispersion relations for parallel and perpendicular directions to the magnetic field are derived and discussed. For longitudinal wave propagation it is found that the value of critical JEANS' wave number increases with increasing density and decreasing temperature of the neutral component. For transverse wave propagation the value of critical JEANS' wave number depends on gyroviscosity, ALFVÉN number, ratio of sonic speeds and densities of the two component and porosity of the medium. It is observed that the effect of magnetic field and porosity is suppressed by finite condutivity of the plasma and similarly the effect of gyroviscosity is removed by viscosity from JEANS' expression of instability.

For both the directions instability is produced when the velocity perturbations are considered parallel to wave vector. The damping effect is produced due to collisional frequency, permeability of the porous medium and viscosity. The density of the neutral component and porosity of the medium tends to destabilize the system while an increased value of FLR corrections leads the system towards stabilization.
Study of Dynamics of Plasma Produced due to Self‐Focussed Laser Beam on a Cylindrical Target
Authors: Vyas P. , Srivastava M. P.
Published: July 2007

The variation of density and flow speed of ions in a laser produced plasma as function of the intensity of the wave for different beam width parameter is studied. It is found that self‐focusing of the beam increases the density and decreases the velocity in the overdense region whereas it decreases the density and increases the velocity in the underdense region.
Non‐Equilibrium Heating of Molecular Gases
Authors: Pustogarov A. V. , Karabut A. B. , Yegorov V. E. , Kucherov Y. A. R.
Published: July 2007

The results of non‐equilibrium heating of air, carbon dioxide, nitrogen in a plasmatron with porous arc channel at intense gas blow are presented. The investigations are performed in the current range 100–500 A, at the gas pressure being higher than atmospheric. The deviation from the equilibrium conditions in the flow behind the plasmatron for air and carbon dioxide is evaluated by reaction products of nitrogen oxides synthesis and carbon dioxide conversion outputs. It is shown that these processes have non‐equilibrium mode and it can explained by an increased products output. For nitrogen the excess of the vibrational temperature Tv over the translational T is defined by the laser probe method (at T = 1500 K Tv = 3000 K).
Untersuchungen des Starkeffektes bei Hohen Feldstärken
Authors: Jäger H. , Windholz L.
Published: July 2007

Der vorliegende Artikel befaßt sich mit dem statischen Starkeffekt bei Feldstärken oberhalb von einigen hundert kV/cm. Im Vordergrund stehen dabei Untersuchungen von nicht wasserstoffähnlichen atomaren Systemen. Nach einer Beschreibung der heute verwendeten apparativen Anordnung zur Realisierung derartiger Felder wird anhand der Ergebnisse von Untersuchungen an Edelgasatomen (vorzugsweise Neon) gezeigt, wie sich auf der Basis umfangreicher experimentell gewonnener Daten allgemein gültige ‘Regeln’ über die meist sehr komplizierten Verhaltensweisen von Starkeffekt‐Niveaus aufstellen lassen. Des weiteren wird gezeigt, wie die gemessenen Verschiebungen über weite Feldstärkebereiche hin in relativ einfacher Form analytisch beschrieben und dokumentiert werden können. Darüberhinaus wird auf das Problem einer brauchbaren Nomenklatur für die Starkeffekt‐Niveaus hin‐gewiesen und vorgeschlagen, dafür jeweils einen Satz geeigneter Quantenzahlen zu verwenden. Dies setzt allerdings eine adäquate theoretische Beschreibung der jeweiligen Starkeffektzustände voraus.
Ion Flux from the Cathode Region of a Vacuum Arc
Authors: Miller H. Craig , Kutzner J.
Published: July 2007

This paper reviews the properties of the cathode ion flux generated in the vacuum arc. The structure and distribution of mass erosion from individual cathode spots and the characteristics of current carriers from the cathode region at moderate arc currents are described. An appreciable ion flux (∼10% of total arc current) is emitted from the cathode of a vacuum arc. This ion flux is strongly peaked in the direction of the anode, though some ion flux may be seen even at angles below the plane of the cathode surface. The observed spatial distribution of the ion flux is expressed quite well as an exponential function of solid angle. The ion flux is quite energetic, with average ion potentials much larger than the arc voltage, and generally contains a considerable fraction of multiply‐charged ions. The average ion potential and ion multiplicity increase significantly for cathode materials with higher arc voltages, but decrease with increasing arc current for a particular material.

The main theories concerning ion acceleration in cathode spots are the potential hump theory (PH), which assumes that all ions are created at the same potential, and the gas dynamic theory (GD), which assumes that all ions are created with the same flow velocity. Experimental data on the potentials and energies of individual ions indicates that these theories in their original forms are not quite correct, however extensions or modifications of the PH and GD theories seem very likely to be able to predict correct values for the charge states, potentials, and energies of individual ions.
Effects of Finite Magnetic Field and Ion Motion on Solitary Space Charge Waves
Authors: Ghosh B.
Published: July 2007

A KDV equation is derived to describe the weakly nonlinear behaviour of electron plasma waves propagating along a plasma‐filled cylindrical waveguide immersed in an external strong but finite axial magnetic field. Solution of the KDV equation shows that the soliton properties depend significantly on the strength of external magnetic field as well as on ion motion.
Thermal Effects on K‐dV Solitons Existing at the Critical Density of Negative Ions in Ion‐Beam Plasmas
Authors: Das G. C. , Ibohanbi‐singh K. H.
Published: July 2007

Ion‐acoustic solitons in a generalized multicomponent plasma are studied through the derivation of Korteweg‐de Vries (K‐dV) equation. The negative ions and ion‐beams play quantitatively various roles on the existence of solitons in the plasma. Especially, the critical density introduced by the negative ions exhibits the existence of a large amplitude soliton in plasmas and due to which a derivation of a modified K‐dV (mK‐dV) equation is needed. By taking the higher order nonlinearity in the plasma, the transition of the K‐dV equation to the mK‐dV equation is also shown. Moreover, various models of the plasma due to the non‐isothermality are also considered in the discussions. Further study closely related to the stability of the soliton is made and yields the salient features of the solitons.