Numerical calculation of ion runaway distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Embréus, O.; Stahl, A.; Hirvijoki, E.

2015-05-15

Ions accelerated by electric fields (so-called runaway ions) in plasmas may explain observations in solar flares and fusion experiments; however, limitations of previous analytic work have prevented definite conclusions. In this work, we describe a numerical solver of the 2D non-relativistic linearized Fokker-Planck equation for ions. It solves the initial value problem in velocity space with a spectral-Eulerian discretization scheme, allowing arbitrary plasma composition and time-varying electric fields and background plasma parameters. The numerical ion distribution function is then used to consider the conditions for runaway ion acceleration in solar flares and tokamak plasmas. Typical time scales and electric fieldsmore » required for ion acceleration are determined for various plasma compositions, ion species, and temperatures, and the potential for excitation of toroidal Alfvén eigenmodes during tokamak disruptions is considered.« less

An experiment to measure the mass density of a plasma armature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, J.W.; Thomas, K.A.; Clothiaux, E.J.

1991-01-01

In this paper a diagnostic technique for determining the mass density, and possibly the plasma composition, of the plasma armature in the MIDI-3 free-running arc device is described. The armature consists primarily of the components of polythylene and copper, and it can reach velocities in excess of 8 km/sec. The approach in this proof-of-principle experiment utilizes a flash x-ray source with x rays having energies from 3 keV to 20 keV, an elliptical x-ray crystal spectrometer, and an appropriate detector array and data acquisition system.

Plasma gasification of refuse derived fuel in a single-stage system using different gasifying agents.

PubMed

Agon, N; Hrabovský, M; Chumak, O; Hlína, M; Kopecký, V; Masláni, A; Bosmans, A; Helsen, L; Skoblja, S; Van Oost, G; Vierendeels, J

2016-01-01

The renewable evolution in the energy industry and the depletion of natural resources are putting pressure on the waste industry to shift towards flexible treatment technologies with efficient materials and/or energy recovery. In this context, a thermochemical conversion method of recent interest is plasma gasification, which is capable of producing syngas from a wide variety of waste streams. The produced syngas can be valorized for both energetic (heat and/or electricity) and chemical (ammonia, hydrogen or liquid hydrocarbons) end-purposes. This paper evaluates the performance of experiments on a single-stage plasma gasification system for the treatment of refuse-derived fuel (RDF) from excavated waste. A comparative analysis of the syngas characteristics and process yields was done for seven cases with different types of gasifying agents (CO2+O2, H2O, CO2+H2O and O2+H2O). The syngas compositions were compared to the thermodynamic equilibrium compositions and the performance of the single-stage plasma gasification of RDF was compared to that of similar experiments with biomass and to the performance of a two-stage plasma gasification process with RDF. The temperature range of the experiment was from 1400 to 1600 K and for all cases, a medium calorific value syngas was produced with lower heating values up to 10.9 MJ/Nm(3), low levels of tar, high levels of CO and H2 and which composition was in good agreement to the equilibrium composition. The carbon conversion efficiency ranged from 80% to 100% and maximum cold gas efficiency and mechanical gasification efficiency of respectively 56% and 95%, were registered. Overall, the treatment of RDF proved to be less performant than that of biomass in the same system. Compared to a two-stage plasma gasification system, the produced syngas from the single-stage reactor showed more favourable characteristics, while the recovery of the solid residue as a vitrified slag is an advantage of the two-stage set-up. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analysis of data from the plasma composition experiment on the International Sun-Earth Explorer (ISEE 1)

NASA Technical Reports Server (NTRS)

Lennartsson, O. W.

1994-01-01

The Lockheed plasma composition experiment on the ISEE 1 spacecraft has provided one of the largest and most varied sets of data on earth's energetic plasma environment, covering both the solar wind, well beyond the bow shock, and the near equatorial magnetosphere to a distance of almost 23 earth radii. This report is an overview of the last four years of data analysis and archiving. The archiving for NSSDC includes most data obtained during the initial 28-months of instrument operation, from early November 1977 through the end of February 1980. The data products are a combination of spectra (mass and energy angle) and velocity moments. A copy of the data user's guide and examples of the data products are attached as appendix A. The data analysis covers three major areas: solar wind ions upstream and downstream of the day side bowshock, especially He(++) ions; terrestrial ions flowing upward from the auroral regions, especially H(+), O(+), and He(+) ions; and ions of both solar and terrestrial origins in the tail plasma sheet and lobe regions. Copies of publications are attached.

Influence of grinding on service properties of VT-22 powder applied in additive technologies

NASA Astrophysics Data System (ADS)

Zakharov, M. N.; Rybalko, O. F.; Romanova, O. V.; Gelchinskiy, B. R.; Il'inykh, S. A.; Krashaninin, V. A.

2017-01-01

Powder of titanium alloy (VT-22) produced by plasma-spraying was subjected to grinding to obtain powder with size less 100 microns. These powders were sprayed by plasma unit using two types of gases, namely, air and air with methane (spraying in water and sputtering of coating on steel support). Influence of grinding time on yield of powder of required fraction was studied. Morphology and phase composition of the grinded powder and plasma sprayed one were under investigation. In the result of experiments, it appears that the grinding time genuinely influences the chemical and phase compositions, but there is no effect on physical-processing properties. For powders after plasma spraying some changes of non-metal elements content were detected by chemical analysis. Using gaseous mixture of air and methane in plasma spraying unit leads to formation of a new phase in the powder according X-ray diffraction data.

AMPTE/CCE observations of the plasma composition below 17 keV during the September 4, 1984 magnetic storm

NASA Technical Reports Server (NTRS)

Shelley, E. G.; Klumpar, D. M.; Peterson, W. K.; Ghielmetti, A.; Balsiger, H.; Geiss, J.; Rosenbauer, H.

1985-01-01

Observations from the Hot Plasma Composition Experiment on the AMPTE/CCE spacecraft during the magnetic storm of 4-5 September 1984 reveal that significant injection of ions of terrestrial origin accompanied the storm development. The compression of the magnetosphere at storm sudden commencement carried the magnetopause inside the CCE orbit clearly revealing the shocked solar wind plasma. A build up of suprathermal ions is observed near the plasmapause during the storm main phase and recovery phase. Pitch angle distributions in the ring current during the main phase show differences between H(+) and O(+) that suggest mass dependent injection, transport and/or loss processes.

Dynamics Explorer 1: Energetic Ion Composition Spectrometer (EICS)

NASA Technical Reports Server (NTRS)

Shelley, E. G.; Peterson, W. K.; Collin, H. L.

1994-01-01

The Energetic Ion Composition Spectrometer (EICS) experiment was selected as part of the Dynamics Explorer (DE) Program. One of the primary goals of the DE program was to investigate in detail the plasma physics processes responsible for energizing thermal (approximately 1 eV) ionospheric ions and transporting them to the earth's plasma sheet and distant polar cap. The results of the EICS data analysis (including support of other investigators) and of the archiving efforts supported by this contract are summarized in this document. Also reported are some aspects of our operational support activities.

Preliminary design of laser-induced breakdown spectroscopy for proto-Material Plasma Exposure eXperiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, G., E-mail: shawgc@ornl.gov; University of Tennessee, Knoxville, Tennessee 37996; Martin, M. Z.

2014-11-15

Laser-induced breakdown spectroscopy (LIBS) is a technique for measuring surface matter composition. LIBS is performed by focusing laser radiation onto a target surface, ablating the surface, forming a plasma, and analyzing the light produced. LIBS surface analysis is a possible diagnostic for characterizing plasma-facing materials in ITER. Oak Ridge National Laboratory has enabled the initial installation of a laser-induced breakdown spectroscopy diagnostic on the prototype Material-Plasma Exposure eXperiment (Proto-MPEX), which strives to mimic the conditions found at the surface of the ITER divertor. This paper will discuss the LIBS implementation on Proto-MPEX, preliminary design of the fiber optic LIBS collectionmore » probe, and the expected results.« less

Spacelab mission 2: Experimental descriptions

NASA Technical Reports Server (NTRS)

Clifton, K. S. (Editor)

1982-01-01

The second Spacelab Mission and the 12 multidisciplinary experiments selected to fly on board are described. These experiments include the following: vitamin D metabolities and bone demineralization; interaction of oxygen and gravity influenced lignification; ejectable plasma diagnostics package; plasma depletion experiments for ionospheric and radio astronomical studies; small helium cooled IR telescope; elemental composition and energy spectra of cosmic ray nuclei; hard X-ray imaging of clusters of galaxies and other extended X-ray sources; solar magnetic and velocity field measurement system; solar coronal helium abundance Spacelab experiment; solar UV high resolution telescope and spectroraph; solar UV spectral irradiance monitor; and properties of superfluid helium in zero-G.

The Transport of Solar Ions Through the Earth's Magnetosphere

NASA Technical Reports Server (NTRS)

Lennartsson, O. W.

1999-01-01

This report covers the initial phase of an investigation that was originally selected by NASA Headquarters for funding by a grant but was later transferred to NASA GSFC for continued funding under a new and separate contract. The principal objective of the investigation, led by Dr. O.W. Lennartsson, is to extract information about the solar origin plasma in Earth's magnetosphere, specifically about the entry and transport of this plasma, using energetic (10 eV/e to 18 keV/e) ion composition data from the Lockheed Plasma Composition Experiment on the NASA/ESA International Sun-Earth Explorer One (ISEE 1) satellite. These data were acquired many years ago, from November 1977 through March of 1982, but, because of subsequent failures of similar experiments on several other spacecraft, they are still the only substantial ion composition data available from Earth's magnetotail, beyond 10 R(sub E), in the critically important sub-kev to keV energy range. All of the Lockheed data now exist in a compacted scientific format, suitable for large-scale statistical investigations, which has been archived both at Lockheed Martin in Palo Alto and at the National Space Science Data Center (NSSDC) in Greenbelt. The completion of the archiving, by processing the remaining half of the data, was made possible by separate funding through a temporary NASA program for data restoration and was given priority over the data analysis by a no-cost extension of the subject grant. By chance, the period of performance coincided with an international study of source and loss processes of magnetospheric plasma, sponsored by the International Space Science Institute (ISSI) in Bern, Switzerland, for which Dr. Lennartsson was invited to serve as one of 12 co-chairs. This study meshed well with the continued analysis of the NASA/Lockheed ISEE ion composition data and provided a natural forum for a broader discussion of the results from this unique experiment. What follows is arranged, for the most part, in the context of the ISSI project.

Ion plasma deposition of oxide films with graded-stoichiometry composition: Experiment and simulation

NASA Astrophysics Data System (ADS)

Volpyas, V. A.; Tumarkin, A. V.; Mikhailov, A. K.; Kozyrev, A. B.; Platonov, R. A.

2016-07-01

A method of ion plasma deposition is proposed for obtaining thin multicomponent films with continuously graded composition in depth of the film. The desired composition-depth profile is obtained by varying the working gas pressure during deposition in the presence of an additional adsorbing screen in the drift space between a sputtered target and substrate. Efficiency of the proposed method is confirmed by Monte Carlo simulation of the deposition of thin films of Ba x Sr1- x TiO3 (BSTO) solid solution. It is demonstrated that, during sputtering of a Ba0.3Sr0.7TiO3 target, the parameter of composition stoichiometry in the growing BSTO film varies in the interval of x = 0.3-0.65 when the gas pressure is changed within 2-60 Pa.

Theory and experiments characterizing hypervelocity impact plasmas on biased spacecraft materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Nicolas; Close, Sigrid; Goel, Ashish

2013-03-15

Space weather including solar activity and background plasma sets up spacecraft conditions that can magnify the threat from hypervelocity impacts. Hypervelocity impactors include both meteoroids, traveling between 11 and 72 km/s, and orbital debris, with typical impact speeds of 10 km/s. When an impactor encounters a spacecraft, its kinetic energy is converted over a very short timescale into energy of vaporization and ionization, resulting in a small, dense plasma. This plasma can produce radio frequency (RF) emission, causing electrical anomalies within the spacecraft. In order to study this phenomenon, we conducted ground-based experiments to study hypervelocity impact plasmas using amore » Van de Graaff dust accelerator. Iron projectiles ranging from 10{sup -16} g to 10{sup -11} g were fired at speeds of up to 70 km/s into a variety of target materials under a range of surface charging conditions representative of space weather effects. Impact plasmas associated with bare metal targets as well as spacecraft materials were studied. Plasma expansion models were developed to determine the composition and temperature of the impact plasma, shedding light on the plasma dynamics that can lead to spacecraft electrical anomalies. The dependence of these plasma properties on target material, impact speed, and surface charge was analyzed. Our work includes three major results. First, the initial temperature of the impact plasma is at least an order of magnitude lower than previously reported, providing conditions more favorable for sustained RF emission. Second, the composition of impact plasmas from glass targets, unlike that of impact plasmas from tungsten, has low dependence on impact speed, indicating a charge production mechanism that is significant down to orbital debris speeds. Finally, negative ion formation has a strong dependence on target material. These new results can inform the design and operation of spacecraft in order to mitigate future impact-related space weather anomalies and failures.« less

Theory and experiments characterizing hypervelocity impact plasmas on biased spacecraft materials

NASA Astrophysics Data System (ADS)

Lee, Nicolas; Close, Sigrid; Goel, Ashish; Lauben, David; Linscott, Ivan; Johnson, Theresa; Strauss, David; Bugiel, Sebastian; Mocker, Anna; Srama, Ralf

2013-03-01

Space weather including solar activity and background plasma sets up spacecraft conditions that can magnify the threat from hypervelocity impacts. Hypervelocity impactors include both meteoroids, traveling between 11 and 72 km/s, and orbital debris, with typical impact speeds of 10 km/s. When an impactor encounters a spacecraft, its kinetic energy is converted over a very short timescale into energy of vaporization and ionization, resulting in a small, dense plasma. This plasma can produce radio frequency (RF) emission, causing electrical anomalies within the spacecraft. In order to study this phenomenon, we conducted ground-based experiments to study hypervelocity impact plasmas using a Van de Graaff dust accelerator. Iron projectiles ranging from 10-16 g to 10-11 g were fired at speeds of up to 70 km/s into a variety of target materials under a range of surface charging conditions representative of space weather effects. Impact plasmas associated with bare metal targets as well as spacecraft materials were studied. Plasma expansion models were developed to determine the composition and temperature of the impact plasma, shedding light on the plasma dynamics that can lead to spacecraft electrical anomalies. The dependence of these plasma properties on target material, impact speed, and surface charge was analyzed. Our work includes three major results. First, the initial temperature of the impact plasma is at least an order of magnitude lower than previously reported, providing conditions more favorable for sustained RF emission. Second, the composition of impact plasmas from glass targets, unlike that of impact plasmas from tungsten, has low dependence on impact speed, indicating a charge production mechanism that is significant down to orbital debris speeds. Finally, negative ion formation has a strong dependence on target material. These new results can inform the design and operation of spacecraft in order to mitigate future impact-related space weather anomalies and failures.

Determination of plasma displacement based on eddy current diagnostics for the Keda Torus eXperiment

NASA Astrophysics Data System (ADS)

Tu, Cui; Li, Hong; Liu, Adi; Li, Zichao; Zhang, Yuan; You, Wei; Tan, Mingsheng; Luo, Bing; Adil, Yolbarsop; Hu, Jintong; Wu, Yanqi; Yan, Wentan; Xie, Jinlin; Lan, Tao; Mao, Wenzhe; Ding, Weixing; Xiao, Chijin; Zhuang, Ge; Liu, Wandong

2017-10-01

The measurement of plasma displacement is one of the most basic diagnostic tools in the study of plasma equilibrium and control in a toroidal magnetic confinement configuration. During pulse discharge, the eddy current induced in the vacuum vessel and shell will produce an additional magnetic field at the plasma boundary, which will have a significant impact on the measurement of plasma displacement using magnetic probes. In the newly built Keda Torus eXperiment (KTX) reversed field pinch device, the eddy current in the composite shell can be obtained at a high spatial resolution. This device offers a new way to determine the plasma displacement for KTX through the multipole moment expansion of the eddy current, which can be obtained by unique probe arrays installed on the inner and outer surfaces of the composite shell. In an ideal conductor shell approximation, the method of multipole moment expansion of the poloidal eddy current for measuring the plasma displacement in toroidal coordinates, is more accurate than the previous method based on symmetrical magnetic probes, which yielded results in cylindrical coordinates. Through an analytical analysis of many current filaments and numerical simulations of the current distribution in toroidal coordinates, the scaling relation between the first moment of the eddy current and the center of gravity of the plasma current is obtained. In addition, the origin of the multipole moment expansion of the eddy current in KTX is retrieved simultaneously. Preliminary data on the plasma displacement have been collected using these two methods during short pulse discharges in the KTX device, and the results of the two methods are in reasonable agreement.

Tantalum-tungsten oxide thermite composites prepared by sol-gel synthesis and spark plasma sintering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuntz, Joshua D.; Gash, Alexander E.; Cervantes, Octavio G.

2010-08-15

Energetic composite powders consisting of sol-gel derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and the results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High-Pressure Spark Plasma Sintering (HPSPS) technique, on the sol-gel derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The sol-gel derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta-WO{sub 3}) energetic composite was consolidated to a density of 9.17 g cm{sup -3}more » or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy. (author)« less

Tantalum-Tungsten Oxide Thermite Composite Prepared by Sol-Gel Synthesis and Spark Plasma Sintering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cervantes, O; Kuntz, J; Gash, A

2009-02-13

Energetic composite powders consisting of sol-gel derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the sol-gel derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The sol-gel derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO{sub 3}) energetic composite was consolidated to a density of 9.17more » g.cm{sup -3} or 93% relative density. In addition those parts were consolidated without significant pre-reaction of the constituents, thus the sample retained its stored chemical energy.« less

Quantitative evaluation of the mechanical strength of titanium/composite bonding using laser-generated shock waves

NASA Astrophysics Data System (ADS)

Ducousso, M.; Bardy, S.; Rouchausse, Y.; Bergara, T.; Jenson, F.; Berthe, L.; Videau, L.; Cuvillier, N.

2018-03-01

Intense acoustic shock waves were applied to evaluate the mechanical strength of structural epoxy bonds between a TA6V4 titanium alloy and a 3D woven carbon/epoxy composite material. Two bond types with different mechanical strengths were obtained from two different adhesive reticulations, at 50% and 90% of conversion, resulting in longitudinal static strengths of 10 and 39 MPa and transverse strengths of 15 and 35 MPa, respectively. The GPa shock waves were generated using ns-scale intense laser pulses and reaction principles to a confined plasma expansion. Simulations taking into account the laser-matter interaction, plasma relaxation, and non-linear shock wave propagation were conducted to aid interpretation of the experiments. Good correlations were obtained between the experiments and the simulation and between different measurement methods of the mechanical strength (normalized tests vs laser-generated shock waves). Such results open the door toward certification of structural bonding.

Intrinsic stability of Brassicaceae plasma membrane in relation to changes in proteins and lipids as a response to salinity.

PubMed

Chalbi, Najla; Martínez-Ballesta, Ma Carmen; Youssef, Nabil Ben; Carvajal, Micaela

2015-03-01

Changes in plasma membrane lipids, such as sterols and fatty acids, have been observed as a result of salt stress. These alterations, together with modification of the plasma membrane protein profile, confer changes in the physical properties of the membrane to be taken into account for biotechnological uses. In our experiments, the relationship between lipids and proteins in three different Brassicaceae species differing in salinity tolerance (Brassica oleracea, B. napus and Cakile maritima) and the final plasma membrane stability were studied. The observed changes in the sterol (mainly an increase in sitosterol) and fatty acid composition (increase in RUFA) in each species led to physical adaptation of the plasma membrane to salt stress. The in vitro vesicles stability was higher in the less tolerant (B. oleracea) plants together with low lipoxygenase activity. These results indicate that the proteins/lipids ratio and lipid composition is an important aspect to take into account for the use of natural vesicles in plant biotechnology. Copyright © 2014 Elsevier GmbH. All rights reserved.

Efficient replacement of plasma membrane outer leaflet phospholipids and sphingolipids in cells with exogenous lipids

PubMed Central

Kim, JiHyun; Huang, Zhen; St. Clair, Johnna R.; Brown, Deborah A.; London, Erwin

2016-01-01

Our understanding of membranes and membrane lipid function has lagged far behind that of nucleic acids and proteins, largely because it is difficult to manipulate cellular membrane lipid composition. To help solve this problem, we show that methyl-α-cyclodextrin (MαCD)-catalyzed lipid exchange can be used to maximally replace the sphingolipids and phospholipids in the outer leaflet of the plasma membrane of living mammalian cells with exogenous lipids, including unnatural lipids. In addition, lipid exchange experiments revealed that 70–80% of cell sphingomyelin resided in the plasma membrane outer leaflet; the asymmetry of metabolically active cells was similar to that previously defined for erythrocytes, as judged by outer leaflet lipid composition; and plasma membrane outer leaflet phosphatidylcholine had a significantly lower level of unsaturation than phosphatidylcholine in the remainder of the cell. The data also provided a rough estimate for the total cellular lipids residing in the plasma membrane (about half). In addition to such lipidomics applications, the exchange method should have wide potential for investigations of lipid function and modification of cellular behavior by modification of lipids. PMID:27872310

Efficient replacement of plasma membrane outer leaflet phospholipids and sphingolipids in cells with exogenous lipids.

PubMed

Li, Guangtao; Kim, JiHyun; Huang, Zhen; St Clair, Johnna R; Brown, Deborah A; London, Erwin

2016-12-06

Our understanding of membranes and membrane lipid function has lagged far behind that of nucleic acids and proteins, largely because it is difficult to manipulate cellular membrane lipid composition. To help solve this problem, we show that methyl-α-cyclodextrin (MαCD)-catalyzed lipid exchange can be used to maximally replace the sphingolipids and phospholipids in the outer leaflet of the plasma membrane of living mammalian cells with exogenous lipids, including unnatural lipids. In addition, lipid exchange experiments revealed that 70-80% of cell sphingomyelin resided in the plasma membrane outer leaflet; the asymmetry of metabolically active cells was similar to that previously defined for erythrocytes, as judged by outer leaflet lipid composition; and plasma membrane outer leaflet phosphatidylcholine had a significantly lower level of unsaturation than phosphatidylcholine in the remainder of the cell. The data also provided a rough estimate for the total cellular lipids residing in the plasma membrane (about half). In addition to such lipidomics applications, the exchange method should have wide potential for investigations of lipid function and modification of cellular behavior by modification of lipids.

[Bonding strength of resin and tooth enamel after teeth bleaching with cold plasma].

PubMed

Zhu, Meng-meng; Wang, Guo-min; Sun, Ke; Li, Ying-long; Pan, Jie

2016-02-18

To investigate the immediate bond strength and surface structure of resin and the tooth enamel which treated by cold plasma. In the study, 40 bovine incisors were divided into two equal parts. In this sense, all enamel adhesive samples were prepared and then randomly divided into 4 groups (n =20). group 1: acid + single bond 2+resin composite (control group); group 2:beyond bleaching+ acid+single bond 2+resin composite; group 3: treated by cold plasma for 5 minutes+ acid+single bond 2+resin composite; group 4: treated by cold plasma for 5 minutes+single bond 2+resin composite. Single bond 2 bonding system and Filtek Z250 resin were used in this experiment. The shear bond strength was tested by universal testing machine. The surface of the enamel in different processes was observed by scanning electron microscope (SEM). Statistical analyses by the single factor analysis of variance and multiple pairwise comparisons were performed with SPSS 17.0 . The shear bond strength of group 4 (8.60 MPa) was significantly lower than that of the other three groups (P<0.05). The shear bond strength of group 2 (17.89 MPa) was higher than that of group 4, but lower than group 1 and group 3 (P<0.05).There was no significant difference between group 1 (34.82 MPa) and group 3 (34.69 MPa). Scanning electron microscope indicated that the enamel treated by cold plasma had slight molten form, which was different from etched enamel surface.The fractured surface of group 3 was mix fracture, which was similar to the control group (group 1). Compared with the conventional clinic bleaching, immediate bond strength of resin-enamel that treated by cold plasma has not been affected.

A review of low density porous materials used in laser plasma experiments

NASA Astrophysics Data System (ADS)

Nagai, Keiji; Musgrave, Christopher S. A.; Nazarov, Wigen

2018-03-01

This review describes and categorizes the synthesis and properties of low density porous materials, which are commonly referred to as foams and are utilized for laser plasma experiments. By focusing a high-power laser on a small target composed of these materials, high energy and density states can be produced. In the past decade or so, various new target fabrication techniques have been developed by many laboratories that use high energy lasers and consequently, many publications and reviews followed these developments. However, the emphasis so far has been on targets that did not utilize low density porous materials. This review therefore, attempts to redress this balance and endeavors to review low density materials used in laser plasma experiments in recent years. The emphasis of this review will be on aspects of low density materials that are of relevance to high energy laser plasma experiments. Aspects of low density materials such as densities, elemental compositions, macroscopic structures, nanostructures, and characterization of these materials will be covered. Also, there will be a brief mention of how these aspects affect the results in laser plasma experiments and the constrictions that these requirements put on the fabrication of low density materials relevant to this field. This review is written from the chemists' point of view to aid physicists and the new comers to this field.

Inductively coupled plasma-mass spectrometry as an element-specific detector for field-flow fractionation particle separation

USGS Publications Warehouse

Taylor, Howard E.; Garbarino, John R.; Murphy, Deirdre M.; Beckett, Ronald

1992-01-01

An inductively coupled plasma-mass spectrometer was used for the quantitative measurement of trace elements In specific,submicrometer size-fraction particulates, separated by sedimentation field-flow fractionation. Fractions were collected from the eluent of the field-flow fractionation centrifuge and nebulized, with a Babington-type pneumatic nebulizer, into an argon inductively coupled plasma-mass spectrometer. Measured Ion currents were used to quantify the major, minor, and trace element composition of the size-separated colloidal (< 1-microm diameter) particulates. The composition of surface-water suspended matter collected from the Yarra and Darling rivers in Australia is presented to illustrate the usefulness of this tool for characterizing environmental materials. An adsorption experiment was performed using cadmium lon to demonstrate the utility for studying the processes of trace metal-suspended sediment interactions and contaminant transport in natural aquatic systems.

Effect of Atmospheric Pressure Plasma Treatment on Surface Characteristics and Adhesive Bond Quality of Peel Ply Prepared Composites

NASA Astrophysics Data System (ADS)

Tracey, Ashley C.

The purpose of this research was to investigate if atmospheric pressure plasma treatment could modify peel ply prepared composite surfaces to create strong adhesive bonds. Two peel ply surface preparation composite systems previously shown to create weak bonds (low fracture energy and adhesion failure) that were potential candidates for plasma treatment were Toray T800/3900-2 carbon fiber reinforced polymer (CFRP) prepared with Precision Fabrics Group, Inc. (PFG) 52006 nylon peel ply and Hexcel T300/F155 CFRP prepared with PFG 60001 polyester peel ply. It was hypothesized that atmospheric pressure plasma treatment could functionalize and/or remove peel ply remnants left on the CFRP surfaces upon peel ply removal. Surface characterization measurements and double cantilever beam (DCB) testing were used to determine the effects of atmospheric pressure plasma treatment on surface characteristics and bond quality of peel ply prepared CFRP composites. Previous research showed that Toray T800/3900-2 carbon fiber reinforced epoxy composites prepared with PFG 52006 peel ply and bonded with Cytec MetlBond 1515-3M structural film adhesive failed in adhesion at low fracture energies when tested in the DCB configuration. Previous research also showed that DCB samples made of Hexcel T300/F155 carbon fiber reinforced epoxy composites prepared with PFG 60001 peel ply and bonded with Henkel Hysol EA 9696 structural film adhesive failed in adhesion at low fracture energies. Recent research suggested that plasma treatment could be able to activate these "un-bondable" surfaces and result in good adhesive bonds. Nylon peel ply prepared 177 °C cure and polyester peel ply prepared 127 °C cure CFRP laminates were treated with atmospheric pressure plasma after peel ply removal prior to bonding. Atmospheric pressure plasma treatment was capable of significantly increasing fracture energies and changing failure modes. For Toray T800/3900-2 laminates prepared with PFG 52006 and bonded with MetlBond 1515-3M, plasma treatment increased fracture energies from 460 J/m 2. Atmospheric pressure plasma treatment also increased fracture energies of Hexcel T300/F155 laminates prepared with PFG 60001 and bonded with EA 9696 from 1500 J/m2. It was demonstrated that atmospheric pressure plasma treatment was able to transform poor bonding surfaces into acceptable ones by reversing the negative effects of incorrect peel ply usage. To determine if the primary reason for adhesion was functionalization or removal, a number of experiments were performed. Surface characteristics of peel ply only and plasma treated samples were determined using contact angle (CA) measurements, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). CA was used to assess solid surface energy that was useful to determine wetting of the adhesive on the adherend, one requirement of adhesion. FTIR and XPS were used to analyze composite surface chemistry, including the identification of functional groups that were a product of atmospheric pressure plasma treatment, as well as contaminants that can inhibit adhesive bonding. SEM was used to capture surface morphology to identify peel ply remnants and whether these remnants were physically removed or modified due to plasma treatment. This research supported that atmospheric pressure plasma treatment resulted in adhesion primarily due to functionalization of peel ply remnants, though a removal mechanism was not disproven. It was also shown that surface energy exhibited potential for predicting adhesion. Lastly, this research indicated that plasma treatment is a robust surface preparation, as strong bonds were observed up to 30 days after treatment.

Plasma observations near Jupiter - Initial results from Voyager 2

NASA Technical Reports Server (NTRS)

Bridge, H. S.; Belcher, J. W.; Lazarus, A. J.; Sullivan, J. D.; Bagenal, F.; Mcnutt, R. L., Jr.; Ogilvie, K. W.; Scudder, J. D.; Sittler, E. D.; Vasyliunas, V. M.

1979-01-01

A preliminary report is presented of the results obtained by the Voyager 2 plasma experiment during the encounter of Voyager 2 with Jupiter from about 100 Jupiter radii before periapsis to about 300 Jupiter radii after periapsis, the instrument being identical to that on Voyager 1. The discussion covers the following: (1) the crossings of the bow shock and magnetopause observed on the inbound and outbound passes; (2) the radial variation of plasma properties in the magnetosphere; (3) variations in plasma properties near Ganymede; (4) corotation and composition of the plasma in the dayside magnetosphere; and (5) plasma sheet crossings observed on the inbound and outbound passes. From the planetary spin modulation of the plasma-electron intensity it is inferred that the plasma sheet is centered at the dipole magnetic equator out to a distance of 40-50 Jupiter radii and deviates from it toward the rotational equator at larger distances.

Optimizing the vacuum plasma spray deposition of metal, ceramic, and cermet coatings using designed experiments

NASA Astrophysics Data System (ADS)

Kingswell, R.; Scott, K. T.; Wassell, L. L.

1993-06-01

The vacuum plasma spray (VPS) deposition of metal, ceramic, and cermet coatings has been investigated using designed statistical experiments. Processing conditions that were considered likely to have a significant influence on the melting characteristics of the precursor powders and hence deposition efficiency were incorporated into full and fractional factorial experimental designs. The processing of an alumina powder was very sensitive to variations in the deposition conditions, particularly the injection velocity of the powder into the plasma flame, the plasma gas composition, and the power supplied to the gun. Using a combination of full and fractional factorial experimental designs, it was possible to rapidly identify the important spraying variables and adjust these to produce a deposition efficiency approaching 80 percent. The deposition of a nickel-base alloy metal powder was less sensitive to processing conditions. Generally, however, a high degree of particle melting was achieved for a wide range of spray conditions. Preliminary experiments performed using a tungsten carbide/cobalt cermet powder indicated that spray efficiency was not sensitive to deposition conditions. However, microstructural analysis revealed considerable variations in the degree of tungsten carbide dissolution. The structure and properties of the optimized coatings produced in the factorial experiments are also discussed.

Measuring the Silver Composition of Nanocolloids by Inductively Coupled Plasma-Optical Emission Spectroscopy: A Laboratory Experiment for Chemistry and Engineering Students

ERIC Educational Resources Information Center

Brittle, Seth W.; Baker, Joshua D.; Dorney, Kevin M.; Dagher, Jessica M.; Ebrahimian, Tala; Higgins, Steven R.; Pavel Sizemore, Ioana E.

2015-01-01

The increased worldwide exploitation of nanomaterials has reinforced the importance of introducing nanoscale aspects into the undergraduate and graduate curriculum. To meet this need, a novel nano-laboratory module was developed and successfully performed by science and engineering students. The main goal of the experiment was to accurately…

Effect of weakly ionized plasma on osmotic pressure on cell membranes in a saline

NASA Astrophysics Data System (ADS)

Shneider, M. N.; Pekker, M.

2018-05-01

In this paper, attention is drawn to the importance of accounting for osmotic pressure when analyzing physiological effects on cellular structures in plasma medicine. Interaction of a weakly ionized plasma jet with a saline solution leads to detectable changes in the saline's ion-molecular composition and hence changes in the osmotic pressure. This, in turn, leads to a stretching or compression of the membrane, depending on the difference of total external and internal pressures. The selective effect of plasma on cells, observed in experiments, is associated with the change in the mechanical properties of membranes (and thereby, a weakening of their protective properties). Corresponding estimates are given in the article.

Effects of oxygen plasma treatment power on Aramid fiber III/BMI composite humidity resistance properties

NASA Astrophysics Data System (ADS)

Wang, Jing; Shi, Chen; Feng, Jiayue; Long, Xi; Meng, Lingzhi; Ren, Hang

2018-01-01

The effects of oxygen plasma treatment power on Aramid Fiber III chemical structure and its reinforced bismaleimides (BMI) composite humidity resistance properties were investigated in this work. The aramid fiber III chemical structure under different plasma treatment power were measured by FTIR. The composite bending strength and interlinear shear strength with different plasma treatment power before and after absorption water were tested respectively. The composite rupture morphology was observed by SEM. The FTIR results showed that oxygen plasma treatment do not change the fiber bulk chemical structure. The composite humidity resistance of bending strength and interlinear shear strength are similar for untreated and plasma treated samples. The retention rate of composite bending strength and interlinear shear strength are about 75% and 94%, respectively. The composite rupture mode turns to be the fiber failure after water absorption.

Solar Wind Characteristics from SOHO-Sun-Ulysses Quadrature Observations

NASA Technical Reports Server (NTRS)

Poletto, Giannina; Suess, Steve T.; Six, N. Frank (Technical Monitor)

2002-01-01

Over the past few years, we have been running SOHO (Solar and Heliospheric Observatory)-Sun-Ulysses quadrature campaigns, aimed at comparing the plasma properties at coronal altitudes with plasma properties at interplanetary distances. Coronal plasma has been observed by SOHO experiments: mainly, we used LASCO (Large Angle and Spectrometric Coronagraph Experiment) data to understand the overall coronal configuration at the time of quadratures and analyzed SUMER (Solar Ultraviolet Measurements of Emitted Radiation), CDS (Coronal Diagnostic Spectrometer) and UVCS (Ultraviolet Coronagraph Spectrometer) data to derive its physical characteristics. At interplanetary distances, SWICS (Solar Wind Ion Composition Spectrometer) and SWOOPS (Solar Wind Observation over the Poles of the Sun) aboard Ulysses provided us with interplanetary plasma data. Here we report on results from some of the campaigns. We notice that, depending on the geometry of the quadrature, i.e. on whether the radial to Ulysses traverses the corona at high or low latitudes, we are able to study different kinds of solar wind. In particular, a comparison between low-latitude and high-latitude wind, allowed us to provide evidence for differences in the acceleration of polar, fast plasma and equatorial, slow plasma: the latter occurring at higher levels and through a more extended region than fast wind. These properties are shared by both the proton and heavy ions outflows. Quadrature observations may provide useful information also on coronal vs. in situ elemental composition. To this end, we analyzed spectra taken in the corona, at altitudes ranging between approx. 1.02 and 2.2 solar radii, and derived the abundances of a number of ions, including oxygen and iron. Values of the O/Fe ratio, at coronal levels, have been compared with measurements of this ratio made by SWICS at interplanetary distances. Our results are compared with previous findings and predictions from modeling efforts.

Effects of atmospheric air plasma treatment on interfacial properties of PBO fiber reinforced composites

NASA Astrophysics Data System (ADS)

Zhang, Chengshuang; Li, Cuiyun; Wang, Baiya; Wang, Bin; Cui, Hong

2013-07-01

Poly(p-phenylene benzobisoxazole) (PBO) fiber was modified by atmospheric air plasma treatment. The effects of plasma treatment power and speed on both surface properties of PBO fibers and interfacial properties of PBO/epoxy composites were investigated. Surface chemical composition of PBO fibers were analyzed by X-ray photoelectron spectroscopy (XPS). Surface morphologies of the fibers and interface structures of the composites were examined using scanning electron microscopy (SEM). Interfacial adhesion property of the composites was evaluated by interlaminar shear strength (ILSS). Mechanical properties of PBO multifilament were measured by universal testing machine. The results indicate that atmospheric air plasma treatment introduced some polar or oxygen-containing groups to PBO fiber surfaces, enhanced surface roughness and changed surface morphologies of PBO fibers by plasma etching and oxidative reactions. The plasma treatment also improved interfacial adhesion of PBO/epoxy composites but has little effect on tensile properties of PBO multifilament. The ILSS of PBO/epoxy composites increased to 40.0 MPa after atmospheric air plasma treatment with plasma treatment power of 300 W and treatment speed of 6 m/min.

Origins of Energetic Ions in the Earth's Magnetosheath

NASA Technical Reports Server (NTRS)

Fuselter, S. A.; Shelley, E. G.; Klumpar, D. M.

1992-01-01

The analysis and interpretation of the combined scientific data from the Hot Plasma Composition Experiment (HPCE) and the Charge Energy Mass (CHEM) spectrometer on the Active Mesospheric Particle Tracer Experiment (AMPTE) Charge Composition Explorer (CCE) spacecraft are discussed. These combined data sets have and will be used to survey the energetic ion environment in the Earth's magnetosheath to determine the origins and relative strengths of the energetic ion populations found there. A computer code was developed to analyze and interpret the data sets. The focus of the first year was on the determination of the contribution of leaked magnetospheric protons to the total energetic proton population. Emphasis was placed on intervals when the AMPTE spacecraft was in the plasma depletion layer because it was argued that in this region, only the leaked population contributes to the energetic ion population. Manipulation of the CHEM data and comparison of the CHEM and HPCE data over their common energy range near the magnetopause also contributed directly to a second study of that region.

[System of ns time-resolved spectroscopy diagnosis and radioprotection].

PubMed

Yao, Wei-Bo; Guo, Jian-Ming; Zhang, Yong-min; Tang, Jun-Ping; Cheng, Liang; Xu, Qi-fuo

2014-06-01

Cathode plasma of high current electron beam diode is an important research on high power microwave and strong pulsed radio accelerator. It is a reliable method to study cathode plasma by diagnosing the cathode plasma parameters with non-contact spectroscopy measurement system. The present paper introduced the work principle, system composition and performance of the nanosecond (ns) time-resolved spectroscopy diagnosis system. Furthermore, it introduced the implementing method and the temporal relation of lower jitter synchronous trigger system. Simultaneously, the authors designed electromagnetic and radio shield room to protect the diagnosis system due to the high electromagnetic and high X-ray and γ-ray radiation, which seriously interferes with the system. Time-resolved spectroscopy experiment on brass (H62) cathode shows that, the element and matter composition of cathode plasma is clearly increase with the increase in the diode pulsed voltage and current magnitude. The spectroscopy diagnosis system could be of up to 10 ns time resolve capability. It's least is 2 ns. Synchronous trigger system's jitter is less than 4 ns. The spectroscopy diagnosis system will open a new way to study the cathode emission mechanism in depth.

LIBS spectra of multi-component Al, Fe, Cu alloys and composite materials used for selected elements of armament and munition

NASA Astrophysics Data System (ADS)

Ostrowski, R.; Skrzeczanowski, W.; Rycyk, A.; CzyŻ, K.; Sarzyński, A.; Strzelec, M.; Jach, K.; Świerczyński, R.

2017-10-01

Spectral investigations in the UV-VIS range of selected Al, Cu, and Fe alloys and composite materials were performed using LIBS technique. The investigated objects were typical rifle cartridges, mortars, rocket launchers and samples of different type steel, Cu and Al alloys, as well as composite materials of special chemical composition. Two Nd:YAG lasers were applied: a short 4 ns, 60 mJ Brio Quantel/BigSky laser (1064 nm) and a long pulse 200/400 (up to 1000) µs ({ 2/4 up to 10 J) laser (1064 nm) constructed at the Institute of Optoelectronics MUT. This spectrochemical analysis was possible for Al, Cu, and Fe alloys objects for both lasers, and in case of composites only if the samples were irradiated by short laser pulse since in the experiment with the long pulse, all composite materials spectra, in general, were very similar to each other - they imitated a grey/black body spectra. For metal alloys in experiments with a short laser pulse only atomic spectra were observed while for long microsecond laser pulses molecular transitions have been registered for Al alloys. Electron temperatures of plasma created on different materials for short and long laser pulses were found on the base of Boltzmann plots. Temperatures are clearly higher for plasmas generated with a short laser pulse which results from much higher laser power density on the sample surface for short pulse and not from fluence which is 20-40 times larger for long pulse.

Thermospheric neutral density estimates from heater-induced ion up-flow at EISCAT

NASA Astrophysics Data System (ADS)

Kosch, Michael; Ogawa, Yasunobu; Yamazaki, Yosuke; Vickers, Hannah; Blagoveshchenskaya, Nataly

We exploit a recently-developed technique to estimate the upper thermospheric neutral density using measurements of ionospheric plasma parameters made by the EISCAT UHF radar during ionospheric modification experiments. Heating the electrons changes the balance between upward plasma pressure gradient and downward gravity, resulting in ion up-flow up to ~200 m/s. This field-aligned flow is retarded by collisions, which is directly related to the neutral density. Whilst the ion up-flow is consistent with the plasma pressure gradient, the estimated thermospheric neutral density depends on the assumed composition, which varies with altitude. Results in the topside ionosphere are presented.

Feed supplementation of Lactobacillus plantarum PCA 236 modulates gut microbiota and milk fatty acid composition in dairy goats--a preliminary study.

PubMed

Maragkoudakis, Petros A; Mountzouris, Konstantinos C; Rosu, Craita; Zoumpopoulou, Georgia; Papadimitriou, Konstantinos; Dalaka, Eleni; Hadjipetrou, Andreas; Theofanous, Giorgos; Strozzi, Gian Paolo; Carlini, Nancy; Zervas, George; Tsakalidou, Effie

2010-07-31

This study aimed to evaluate the potential of a promising Lactobacillus plantarum isolate (PCA 236) from cheese as a probiotic feed supplement in lactating goats. The ability of L. plantarum to survive transit through the goat gastrointestinal tract and to modulate selected constituents of the gut microbiota composition, monitored at faecal level was assessed. In addition, L. plantarum effects on plasma immunoglobulins and antioxidant capacity of the animals as well as on the milk fatty acid composition were determined. For the purpose of the experiment a field study was designed, involving 24 dairy goats of the Damascus breed, kept in a sheep and goat dairy farm. The goats were divided in terms of body weight in two treatments of 12 goats each, namely: control (CON) without addition of L. plantarum and probiotic (PRO) treatment with in feed administration of L. plantarum so that the goats would intake 12 log CFU/day. The experiment lasted 5 weeks and at weekly time intervals individual faecal, blood and milk samples were collected and analysed. All faecal samples were examined for the presence of L. plantarum PCA 236. In addition, the culturable population levels of mesophilic aerobes, coliforms lactic acid bacteria (LAB), Streptococcus, Enterococcus, mesophilic anaerobes, Clostridium and Bacteroides in faeces were also determined by enumeration on specific culture media. In parallel, plasma IgA, IgM and IgG and antioxidant capacity of plasma and milk were determined. No adverse effects were observed in the animals receiving the lactobacillus during the experiment. Lactobacillus plantarum PCA 236 was recovered in the faeces of all animals in the PRO treatment. In addition, PRO treatment resulted in a significant (P

A constitutive model for developing blood clots with various compositions and their nonlinear viscoelastic behavior.

PubMed

van Kempen, Thomas H S; Donders, Wouter P; van de Vosse, Frans N; Peters, Gerrit W M

2016-04-01

The mechanical properties determine to a large extent the functioning of a blood clot. These properties depend on the composition of the clot and have been related to many diseases. However, the various involved components and their complex interactions make it difficult at this stage to fully understand and predict properties as a function of the components. Therefore, in this study, a constitutive model is developed that describes the viscoelastic behavior of blood clots with various compositions. Hereto, clots are formed from whole blood, platelet-rich plasma and platelet-poor plasma to study the influence of red blood cells, platelets and fibrin, respectively. Rheological experiments are performed to probe the mechanical behavior of the clots during their formation. The nonlinear viscoelastic behavior of the mature clots is characterized using a large amplitude oscillatory shear deformation. The model is based on a generalized Maxwell model that accurately describes the results for the different rheological experiments by making the moduli and viscosities a function of time and the past and current deformation. Using the same model with different parameter values enables a description of clots with different compositions. A sensitivity analysis is applied to study the influence of parameter variations on the model output. The relative simplicity and flexibility make the model suitable for numerical simulations of blood clots and other materials showing similar behavior.

The eddy current probe array for Keda Torus eXperiment.

PubMed

Li, Zichao; Li, Hong; Tu, Cui; Hu, Jintong; You, Wei; Luo, Bing; Tan, Mingsheng; Adil, Yolbarsop; Wu, Yanqi; Shen, Biao; Xiao, Bingjia; Zhang, Ping; Mao, Wenzhe; Wang, Hai; Wen, Xiaohui; Zhou, Haiyang; Xie, Jinlin; Lan, Tao; Liu, Adi; Ding, Weixing; Xiao, Chijin; Liu, Wandong

2016-11-01

In a reversed field pinch device, the conductive shell is placed as close as possible to the plasma so as to balance the plasma during discharge. Plasma instabilities such as the resistive wall mode and certain tearing modes, which restrain the plasma high parameter operation, respond closely with conditions in the wall, in essence the eddy current present. Also, the effect of eddy currents induced by the external coils cannot be ignored when active control is applied to control instabilities. One diagnostic tool, an eddy current probe array, detects the eddy current in the composite shell. Magnetic probes measuring differences between the inner and outer magnetic fields enable estimates of the amplitude and angle of these eddy currents. Along with measurements of currents through the copper bolts connecting the poloidal shield copper shells, we can obtain the eddy currents over the entire shell. Magnetic field and eddy current resolutions approach 2 G and 6 A, respectively. Additionally, the vortex electric field can be obtained by eddy current probes. As the conductivity of the composite shell is high, the eddy current probe array is very sensitive to the electric field and has a resolution of 0.2 mV/cm. In a bench test experiment using a 1/4 vacuum vessel, measurements of the induced eddy currents are compared with simulation results based on a 3D electromagnetic model. The preliminary data of the eddy currents have been detected during discharges in a Keda Torus eXperiment device. The typical value of toroidal and poloidal eddy currents across the magnetic probe coverage rectangular area could reach 3.0 kA and 1.3 kA, respectively.

Antifouling coatings via plasma polymerization and atom transfer radical polymerization on thin film composite membranes for reverse osmosis

NASA Astrophysics Data System (ADS)

Hirsch, Ulrike; Ruehl, Marco; Teuscher, Nico; Heilmann, Andreas

2018-04-01

A major drawback to otherwise highly efficient membrane-based desalination techniques like reverse osmosis (RO) is the susceptibility of the membranes to biofouling. In this work, a combination of plasma activation, plasma bromination and surface-initiated atom transfer radical polymerization (si-ATRP) of hydrophilic and zwitterionic monomers, namely hydroxyethyl methacrylate (HEMA), 2-methacryloyloxyethyl phosphorylcholine (MPC) and [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), was applied to generate non-specific, anti-adhesive coatings on thin film composite (TFC) membranes. The antifouling effect of the coatings was shown by short-time batch as well as long-time steady state cultivation experiments with the microorganism Pseudomonas fluorescens. It could be shown that plasma functionalization and polymerization is possible on delicate thin film composite membranes without restricting their filtration performance. All modified membranes showed an increased resistance towards the adhesion of Pseudomonas fluorescens. On average, the biofilm coverage was reduced by 51.4-12.6% (for HEMA, SBMA, and MPC), the highest reduction was monitored for MPC with a biofilm reduction by 85.4%. The hydrophilic coatings applied did not only suppress the adhesion of Pseudomonas fluorescens, but also significantly increase the permeate flux of the membranes relative to uncoated membranes. The stability of the coatings was however not ideal and will have to be improved for future commercial use.

Improved mechanical performance of PBO fiber-reinforced bismaleimide composite using mixed O2/Ar plasma

NASA Astrophysics Data System (ADS)

Liu, Dong; Chen, Ping; Yu, Qi; Ma, Keming; Ding, Zhenfeng

2014-06-01

The mixed O2/Ar plasma was employed to enhance mechanical properties of the PBO/bismaleimide composite. The interlaminar shear strength was improved to 61.6 MPa or by 38.1%, but the composite brittleness increased. The plasma gas compositions exhibited notable effects on the interfacial adhesion strength. XPS results suggested that the mixed plasma presented higher activation effects on the surface chemical compositions than pure gas plasmas and a larger number of oxygen atoms and hydrophilic groups were introduced on the fiber surface due to the synergy effect, but the synergy effect was considerably performed only within the O2 percentage range of 40-60%. The fibers surface was increasingly etched with growing the O2 contents in the plasma, deteriorating the fibers tensile strength. SEM micrographs demonstrated that the composite shear fracture changed from debonding to cohesive failure in the matrices, and the improving mechanisms were discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desai, M. I.; McComas, D. J.; Allegrini, F.

We have developed a novel concept for a Compact Dual Ion Composition Experiment (CoDICE) that simultaneously provides high quality plasma and energetic ion composition measurements over 6 decades in ion energy in a wide variety of space plasma environments. CoDICE measures the two critical ion populations in space plasmas: (1) mass and ionic charge state composition and 3D velocity and angular distributions of ∼10 eV/q–40 keV/q plasma ions—CoDICE-Lo and (2) mass composition, energy spectra, and angular distributions of ∼30 keV–10 MeV energetic ions—CoDICE-Hi. CoDICE uses a common, integrated Time-of-Flight (TOF) versus residual energy (E) subsystem for measuring the two distinctmore » ion populations. This paper describes the CoDICE design concept, and presents results of the laboratory tests of the TOF portion of the TOF vs. E subsystem, focusing specifically on (1) investigation of spill-over and contamination rates on the start and stop microchannel plate (MCP) anodes vs. secondary electron steering and focusing voltages, scanned around their corresponding model-optimized values, (2) TOF measurements and resolution and angular resolution, and (3) cross-contamination of the start and stop MCPs’ singles rates from CoDICE-Lo and -Hi, and (4) energy resolution of avalanche photodiodes near the lower end of the CoDICE-Lo energy range. We also discuss physical effects that could impact the performance of the TOF vs. E subsystem in a flight instrument. Finally, we discuss advantages of the CoDICE design concept by comparing with capabilities and resources of existing flight instruments.« less

Fatty acid composition of plasma lipids and erythrocyte membranes during simulated extravehicular activity

NASA Astrophysics Data System (ADS)

Skedina, M. A.; Katuntsev, V. P.; Buravkova, L. B.; Naidina, V. P.

Ten subjects (from 27 to 41 years) have been participated in 32 experiments. They were decompressed from ground level to 40-35 kPa in altitude chamber when breathed 100% oxygen by mask and performed repeated cycles of exercises (3.0 Kcal/min). The intervals between decompressions were 3-5 days. Plasma lipid and erythrocyte membrane fatty acid composition was evaluated in the fasting venous blood before and immediately after hypobaric exposure. There were 7 cases decompression sickness (DCS). Venous gas bubbles (GB) were detected in 27 cases (84.4%). Any significant changes in the fatty acid composition of erythrocyte membranes and plasma didn't practically induce after the first decompression. However, by the beginning of the second decompression the total lipid level in erythrocyte membranes decreased from 54.6 mg% to 40.4 mg% in group with DCS symptoms and from 51.2 mg% to 35.2 mg% (p < 0.05) without DCS symptoms. In group with DCS symptoms a tendency to increased level of saturated fatty acids in erythrocyte membranes (16:0, 18:0), the level of the polyunsaturated linoleic fatty acid (18:2) and arachidonic acid (20:4) tended to be decreased by the beginning of the second decompression. Insignificant changes in blood plasma fatty acid composition was observed in both groups. The obtained biochemical data that indicated the simulated extravehicular activity (EVA) condition is accompanied by the certain changes in the blood lipid metabolism, structural and functional state of erythrocyte membranes, which are reversible. The most pronounced changes are found in subjects with DCS symptoms.

Fatty acid composition of plasma lipids and erythrocyte membranes during simulated extravehicular activity.

PubMed

Skedina, M A; Katuntsev, V P; Buravkova, L B; Naidina, V P

1998-01-01

Ten subjects (from 27 to 41 years) have been participated in 32 experiments. They were decompressed from ground level to 40-35 kPa in altitude chamber when breathed 100% oxygen by mask and performed repeated cycles of exercises (3.0 Kcal/min). The intervals between decompressions were 3-5 days. Plasma lipid and erythrocyte membrane fatty acid composition was evaluated in the fasting venous blood before and immediately after hypobaric exposure. There were 7 cases decompression sickness (DCS). Venous gas bubbles (GB) were detected in 27 cases (84.4%). Any significant changes in the fatty acid composition of erythrocyte membranes and plasma didn't practically induce after the first decompression. However, by the beginning of the second decompression the total lipid level in erythrocyte membranes decreased from 54.6 mg% to 40.4 mg% in group with DCS symptoms and from 51.2 mg% to 35.2 mg% (p<0.05) without DCS symptoms. In group with DCS symptoms a tendency to increased level of saturated fatty acids in erythrocyte membranes (16:0, 18:0), the level of the polyunsaturated linoleic fatty acid (18:2) and arachidonic acid (20:4) tended to be decreased by the beginning of the second decompression. Insignificant changes in blood plasma fatty acid composition was observed in both groups. The obtained biochemical data that indicated the simulated extravehicular activity (EVA) condition is accompanied by the certain changes in the blood lipid metabolism, structural and functional state of erythrocyte membranes, which are reversible. The most pronounced changes are found in subjects with DCS symptoms.

Behavior of graphite under heat load and in contact with a hydrogen plasma

NASA Astrophysics Data System (ADS)

Bohdansky, J.; Croessmann, C. D.; Linke, J.; McDonald, J. M.; Morse, D. H.; Pontau, A. E.; Watson, R. D.; Whitley, J. B.; Goebel, D. M.; Hirooka, Y.; Leung, K.; Conn, R. W.; Roth, J.; Ottenberger, W.; Kotzlowski, H. E.

1987-05-01

Graphite is extensively used in large tokamaks today. In these machines the material is exposed to vacuum, to intense heat loads, and to the edge plasma. The use of graphite in such machines, therefore, depends on the outgassing behavior, the heat shock resistance, and thermochemical properties in a hydrogen plasma. Investigations of these properties made at different laboratories are described here. Experiments conducted at Sandia National Laboratories (SNL), Livermore, and the Max-Planck-Institut für Plasmaphysik (IPP) in Garching showed that the outgassing behavior of fine-grain reactor-grade graphite and carbon fiber composites depends on the pretreatment (manufacturing and/or storage). However, after proper outgassing the samples tested behave similarly in the case of fine-grain graphite, but the outgassing remains high for the carbon fiber composites. Heat shock tests have been made with the Electron Beam Test System (EBTS) at SNL, Albuquerque. Directly cooled graphite samples (FE 159 graphite brazed onto Mo tubes) showed no failure at a heat load of 700 W/cm 2, 20 s; or 10 kW, 1 s. Thermal erosion due to sublimination and particle emission from the graphite surface was observed. This effect is related to the surface temperature and becomes significant at temperatures above 2500°K. Fourteen different types of graphite were tested; the main differences among these samples were the different surface temperatures obtained under the same heating conditions. Cracking due to heat shocks was observed in some of the samples, but none of the carbon fiber composites failed. Thermochemical properties have been tested in the PISCES plasma generator at UCLA for ion energies of around 100 eV. The formation of C-H compounds was observed spectroscopically at sample temperatures of around 600°C. However, this chemical reaction did not lead to erosion as observed in beam experiments but to a drastic change of the surface structure due to redeposition. Carbon-hydrogen lines were still observed at sample temperatures of around 100°C. Under these conditions the erosion yield is high and in agreement with those measured in beam experiments.

The Thermal Ion Dynamics Experiment and Plasma Source Instrument

NASA Technical Reports Server (NTRS)

Moore, T. E.; Chappell, C. R.; Chandler, M. O.; Fields, S. A.; Pollock, C. J.; Reasoner, D. L.; Young, D. T.; Burch, J. L.; Eaker, N.; Waite, J. H., Jr.;

ICPP: Charge and Density Coupling in Nonideal Plasmas

NASA Astrophysics Data System (ADS)

Fortov, V. E.

2000-10-01

Plasmas with Strong Coulomb Interaction (SCI) are found in astrophysics, planetary physics, inertial confinement fusion, advanced energetics and elsewhere[1]. SCI plasmas can be achieved in: I Dusty plasmas, II Shock-compressed plasmas. I. SCI in low-density dusty (colloidal) plasmas arises from the high charge of micron-size macroparticles[2]. Experiments use glow and inductive RF discharges, combustion flames of gas and solid propellant, ultraviolet light beams, and radioactive decay fluxes. Liquid- and solid-like structures are seen, and phase diagrams and transitions investigated by experiment and simulation. Zero-g experiments on space station Mir and in aircraft clarified the gravity effect on plasma crystal formation. II. Plasma SCI can arise in shock compression of solid and porous metals, noble gases, hydrogen, sulphur, and iodine at megabar pressures [3,4], using high explosive drive. Phase diagram regions were examined, where thermal and pressure ionization exist. Multiple-shock-compressed hydrogen can show metal-like conductivity from pressure ionization. The ``metal-to-dielectric" transition in shock-compressed lithium at 0.5 Mbar was detected and analyzed. Thermodynamics, equation of state, plasma composition, electrical and radiative properties show SCI suppression of discrete electron spectra and strong lowering of ionization potentials, evoking the ``confined-atom" model[5] for SCI and other models[6]. [1] V.E.Fortov, I.T.Yakubov, Physics of Nonideal Plasmas, Hemisphere, N.Y.-London (1989). [2] V.E.Fortov, A.P.Nefedov, O.F.Petrov, Soviet Physics-Uspekhy, 167(1997)1215. [3] V.Gryaznov, I.Iosilevsky, V.Fortov, Contrib. Plasma Physics, 39(1999)89. [4] V.Ya.Temovoi, A.S. Filimonov, V.E.Fortov et al. Proc. XXXVI EHPRG Meeting, Catania, Italy (1998). [5] V.K.Gryaznov, M.V.Zhernokletov et al. Zh. Exp. Teor. Fiz. (Soviet JETP) 78(1980) 573. [6] V.Ebeling, A.Foerster, V.Fortov et al. Thermodynamical Properties of Hot Dense Plasmas, Teubner Verlaggeselschaft , Berlin-Stuttgart, 1991.

Lunar plasma measurement by MAP-PACE onboard KAGUYA (SELENE)

NASA Astrophysics Data System (ADS)

Saito, Yoshifumi

Low energy charged particles around the Moon were vigorously observed by Moon orbiting satellites and plasma instrumentation placed on the lunar surface in 1960s and 1970s. Though there were some satellites that explored the Moon afterwards, most of them were dedicated to the global mapping of the lunar surface. KAGUYA(SELENE) is a Japanese lunar orbiter that studies the origin and evolution of the Moon by means of global mapping of element abundances, mineralogical composition, and surface geographical mapping from 100km altitude. KAGUYA was successfully launched on 14 September 2007 by HIIA launch vehicle from Tanegashima Space Center in Japan. KAGUYA was inserted into a circular lunar polar orbit of 100km altitude and started continuous observation in mid-December 2007. One of the fourteen science instruments MAP-PACE (MAgnetic field and Plasma experiment - Plasma energy Angle and Composition Experiment) was developed for the comprehensive three-dimensional plasma measurement around the Moon. MAP-PACE consists of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). ESA-S1 and S2 measure the distribution function of low energy electrons below 15keV. IMA and IEA measure the distribution function of low energy ions below 28keV/q. IMA has an ability to discriminate the ion mass with high mass resolution. PACE sensors have been measuring solar wind, plasmas in the wake region of the Moon and plasmas in the Earth's magnetosphere. ESA sensors have discovered electron heating over magnetic anomalies on the lunar surface. ESA sensors have also observed electrons accelerated from the lunar surface in the wake region. PACE ion sensors have discovered new features of low energy ions around the Moon. IMA has discovered the existence of alkali ions that are originated from the lunar surface or lunar atmosphere and are picked up by the solar wind. IEA and IMA sensors discovered solar wind reflection by the Moon. PACE ion sensors also discovered that ions are rarefied over the magnetic anomaly on the lunar surface while electrons are heated. MAP-PACE has been revealing unexpectedly active plasma environment around the Moon.

Exciton fission in monolayer transition metal dichalcogenide semiconductors.

PubMed

Steinhoff, A; Florian, M; Rösner, M; Schönhoff, G; Wehling, T O; Jahnke, F

2017-10-27

When electron-hole pairs are excited in a semiconductor, it is a priori not clear if they form a plasma of unbound fermionic particles or a gas of composite bosons called excitons. Usually, the exciton phase is associated with low temperatures. In atomically thin transition metal dichalcogenide semiconductors, excitons are particularly important even at room temperature due to strong Coulomb interaction and a large exciton density of states. Using state-of-the-art many-body theory, we show that the thermodynamic fission-fusion balance of excitons and electron-hole plasma can be efficiently tuned via the dielectric environment as well as charge carrier doping. We propose the observation of these effects by studying exciton satellites in photoemission and tunneling spectroscopy, which present direct solid-state counterparts of high-energy collider experiments on the induced fission of composite particles.

Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Ballenthin, J. O.; Baumgardner, J. L.; Bhatt, A.; Boyd, I. D.; Burt, J. M.; Caton, R. G.; Coster, A.; Erickson, P. J.; Huba, J. D.;

The Evolution of the Plasma Sheet Ion Composition: Storms and Recoveries: Plasma Sheet Ion Composition

DOE PAGES

Denton, M. H.; Thomsen, M. F.; Reeves, G. D.; ...

2017-10-03

The ion plasma sheet (~few hundred eV to ~few 10s keV) is usually dominated by H + ions. Here, changes in ion composition within the plasma sheet are explored both during individual events, and statistically during 54 calm-to-storm events and during 21 active-to-calm events. Ion composition data from the HOPE (Helium, Oxygen, Proton, Electron) instruments onboard Van Allen Probes satellites provide exceptional spatial and temporal resolution of the H +, O +, and He + ion fluxes in the plasma sheet. H+ shown to be the dominant ion in the plasma sheet in the calm-to-storm transition. However, the energy-flux ofmore » each ion changes in a quasi-linear manner during extended calm intervals. Heavy ions (O + and He +) become increasingly important during such periods as charge-exchange reactions result in faster loss for H + than for O + or He +. Results confirm previous investigations showing that the ion composition of the plasma sheet can be largely understood (and predicted) during calm intervals from knowledge of: (a) the composition of previously injected plasma at the onset of calm conditions, and (b) use of simple drift-physics models combined with calculations of charge-exchange losses.« less

The Evolution of the Plasma Sheet Ion Composition: Storms and Recoveries: Plasma Sheet Ion Composition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denton, M. H.; Thomsen, M. F.; Reeves, G. D.

The ion plasma sheet (~few hundred eV to ~few 10s keV) is usually dominated by H + ions. Here, changes in ion composition within the plasma sheet are explored both during individual events, and statistically during 54 calm-to-storm events and during 21 active-to-calm events. Ion composition data from the HOPE (Helium, Oxygen, Proton, Electron) instruments onboard Van Allen Probes satellites provide exceptional spatial and temporal resolution of the H +, O +, and He + ion fluxes in the plasma sheet. H+ shown to be the dominant ion in the plasma sheet in the calm-to-storm transition. However, the energy-flux ofmore » each ion changes in a quasi-linear manner during extended calm intervals. Heavy ions (O + and He +) become increasingly important during such periods as charge-exchange reactions result in faster loss for H + than for O + or He +. Results confirm previous investigations showing that the ion composition of the plasma sheet can be largely understood (and predicted) during calm intervals from knowledge of: (a) the composition of previously injected plasma at the onset of calm conditions, and (b) use of simple drift-physics models combined with calculations of charge-exchange losses.« less

Sexually dimorphic brain fatty acid composition in low and high fat diet-fed mice.

PubMed

Rodriguez-Navas, Carlos; Morselli, Eugenia; Clegg, Deborah J

2016-08-01

In this study, we analyzed the fatty acid profile of brains and plasma from male and female mice fed chow or a western-style high fat diet (WD) for 16 weeks to determine if males and females process fatty acids differently. Based on the differences in fatty acids observed in vivo, we performed in vitro experiments on N43 hypothalamic neuronal cells to begin to elucidate how the fatty acid milieu may impact brain inflammation. Using a comprehensive mass spectrometry fatty acid analysis, which includes a profile for 52 different fatty acid isomers, we assayed the plasma and brain fatty acid composition of age-matched male and female mice maintained on chow or a WD. Additionally, using the same techniques, we determined the fatty acid composition of N43 hypothalamic cells following exposure to palmitic and linoleic acid, alone or in combination. Our data demonstrate there is a sexual dimorphism in brain fatty acid content both following the consumption of the chow diet, as well as the WD, with males having an increased percentage of saturated fatty acids and reductions in ω6-polyunsaturated fatty acids when compared to females. Interestingly, we did not observe a sexual dimorphism in fatty acid content in the plasma of the same mice. Furthermore, exposure of N43 cells to the ω6-PUFA linoleic acid, which is higher in female brains when compared to males, reduces palmitic acid-induced inflammation. Our data suggest male and female brains, and not plasma, differ in their fatty acid profile. This is the first time, to our knowledge, lipidomic analyses has been used to directly test the hypothesis there is a sexual dimorphism in brain and plasma fatty acid composition following consumption of the chow diet, as well as following exposure to the WD.

Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

NASA Astrophysics Data System (ADS)

Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

2016-10-01

Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

Sweat Facilitated Amino Acid Losses in Male Athletes during Exercise at 32-34°C.

PubMed

Dunstan, R Hugh; Sparkes, Diane L; Dascombe, Benjamin J; Macdonald, Margaret M; Evans, Craig A; Stevens, Christopher J; Crompton, Marcus J; Gottfries, Johan; Franks, Jesse; Murphy, Grace; Wood, Ryan; Roberts, Timothy K

2016-01-01

Sweat contains amino acids and electrolytes derived from plasma and athletes can lose 1-2L of sweat per hour during exercise. Sweat may also contain contributions of amino acids as well as urea, sodium and potassium from the natural moisturizing factors (NMF) produced in the stratum corneum. In preliminary experiments, one participant was tested on three separate occasions to compare sweat composition with surface water washings from the same area of skin to assess contributions from NMF. Two participants performed a 40 minute self-paced cycle session with sweat collected from cleansed skin at regular intervals to assess the contributions to the sweat load from NMF over the period of exercise. The main study investigated sweat amino acid composition collected from nineteen male athletes following standardised endurance exercise regimes at 32-34°C and 20-30% RH. Plasma was also collected from ten of the athletes to compare sweat and plasma composition of amino acids. The amino acid profiles of the skin washings were similar to the sweat, suggesting that the NMF could contribute certain amino acids into sweat. Since the sweat collected from athletes contained some amino acid contributions from the skin, this fluid was subsequently referred to as "faux" sweat. Samples taken over 40 minutes of exercise showed that these contributions diminished over time and were minimal at 35 minutes. In the main study, the faux sweat samples collected from the athletes with minimal NMF contributions, were characterised by relatively high levels of serine, histidine, ornithine, glycine and alanine compared with the corresponding levels measured in the plasma. Aspartic acid was detected in faux sweat but not in the plasma. Glutamine and proline were lower in the faux sweat than plasma in all the athletes. Three phenotypic groups of athletes were defined based on faux sweat volumes and composition profiles of amino acids with varying relative abundances of histidine, serine, glycine and ornithine. It was concluded that for some individuals, faux sweat resulting from exercise at 32-34°C and 20-30% RH posed a potentially significant source of amino acid loss.

Sweat Facilitated Amino Acid Losses in Male Athletes during Exercise at 32-34°C

PubMed Central

Dunstan, R. Hugh; Sparkes, Diane L.; Dascombe, Benjamin J.; Macdonald, Margaret M.; Evans, Craig A.; Stevens, Christopher J.; Crompton, Marcus J.; Gottfries, Johan; Franks, Jesse; Murphy, Grace; Wood, Ryan; Roberts, Timothy K.

2016-01-01

Sweat contains amino acids and electrolytes derived from plasma and athletes can lose 1-2L of sweat per hour during exercise. Sweat may also contain contributions of amino acids as well as urea, sodium and potassium from the natural moisturizing factors (NMF) produced in the stratum corneum. In preliminary experiments, one participant was tested on three separate occasions to compare sweat composition with surface water washings from the same area of skin to assess contributions from NMF. Two participants performed a 40 minute self-paced cycle session with sweat collected from cleansed skin at regular intervals to assess the contributions to the sweat load from NMF over the period of exercise. The main study investigated sweat amino acid composition collected from nineteen male athletes following standardised endurance exercise regimes at 32–34°C and 20–30% RH. Plasma was also collected from ten of the athletes to compare sweat and plasma composition of amino acids. The amino acid profiles of the skin washings were similar to the sweat, suggesting that the NMF could contribute certain amino acids into sweat. Since the sweat collected from athletes contained some amino acid contributions from the skin, this fluid was subsequently referred to as “faux” sweat. Samples taken over 40 minutes of exercise showed that these contributions diminished over time and were minimal at 35 minutes. In the main study, the faux sweat samples collected from the athletes with minimal NMF contributions, were characterised by relatively high levels of serine, histidine, ornithine, glycine and alanine compared with the corresponding levels measured in the plasma. Aspartic acid was detected in faux sweat but not in the plasma. Glutamine and proline were lower in the faux sweat than plasma in all the athletes. Three phenotypic groups of athletes were defined based on faux sweat volumes and composition profiles of amino acids with varying relative abundances of histidine, serine, glycine and ornithine. It was concluded that for some individuals, faux sweat resulting from exercise at 32–34°C and 20–30% RH posed a potentially significant source of amino acid loss. PMID:27936120

In situ measurement of gas composition changes in radio frequency plasmas using a quartz sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Atsushi; Nonaka, Hidehiko

2009-09-15

A simple method using a quartz sensor (Q-sensor) was developed to observe gas composition changes in radio frequency (rf) plasmas. The output depends on the gases' absolute pressure, molecular weight, and viscosity. The pressure-normalized quartz sensor output depends only on the molecular weight and viscosity of the gas. Consequently, gas composition changes can be detected in the plasmas if a sensor can be used in the plasmas. Influences imparted by the plasmas on the sensor, such as those by reactive particles (e.g., radicals and ions), excited species, electrons, temperature, and electric potentials during measurements were investigated to test the applicabilitymore » of this quartz sensor measurement to plasma. The Q-sensor measurement results for rf plasmas with argon, hydrogen, and their mixtures are reproducible, demonstrating that the Q-sensor measurement is applicable for plasmas. In this work, pressure- and temperature-normalized Q-sensor output (NQO) were used to obtain the gas composition information of plasma. Temperature-normalization of the Q-sensor output enabled quartz sensor measurements near plasma electrodes, where the quartz sensor temperature increases. The changes in NQO agreed with results obtained by gas analysis using a quadrupole mass spectrometer. Results confirmed that the change in NQO is mainly attributable to changes in the densities and kinds of gas molecules in the plasma gas phase, not by other extrinsic influences of plasma. For argon, hydrogen, and argon-hydrogen plasmas, these changes correspond to reduction in nitrogen, production of carbon monoxide, and dissociation of hydrogen molecules, respectively. These changes in NQO qualitatively and somewhat quantitatively agreed with results obtained using gas analysis, indicting that the measurement has a potential application to obtain the gas composition in plasmas without disturbing industrial plasma processes.« less

Empirical Modeling of ICMEs Using ACE/SWICS Ionic Distributions

NASA Astrophysics Data System (ADS)

Rivera, Y.; Landi, E.; Lepri, S. T.; Gilbert, J. A.

2017-12-01

Coronal Mass Ejections (CMEs) are some of the largest, most energetic events in the solar system releasing an immense amount of plasma and magnetic field into the Heliosphere. The Earth-bound plasma plays a large role in space weather, causing geomagnetic storms that can damage space and ground based instrumentation. As a CME is released, the plasma experiences heating, expansion and acceleration; however, the physical mechanism supplying the heating as it lifts out of the corona still remains uncertain. From previous work we know the ionic composition of solar ejecta undergoes a gradual transition to a state where ionization and recombination processes become ineffective rendering the ionic composition static along its trajectory. This property makes them a good indicator of thermal conditions in the corona, where the CME plasma likely receives most of its heating. We model this so-called `freeze-in' process in Earth-directed CMEs using an ionization code to empirically determine the electron temperature, density and bulk velocity. `Frozen-in' ions from an ensemble of independently modeled plasmas within the CME are added together to fit the full range of observational ionic abundances collected by ACE/SWICS during ICME events. The models derived using this method are used to estimate the CME energy budget to determine a heating rate used to compare with a variety of heating mechanisms that can sustain the required heating with a compatible timescale.

Formation of Equiaxed Alpha and Titanium Nitride Precipitates in Spark Plasma Sintered TiB/Ti-6Al-4V Composites (Preprint)

DTIC Science & Technology

2012-08-01

AFRL-RX-WP-TP-2012-0372 FORMATION OF EQUIAXED ALPHA AND TITANIUM NITRIDE PRECIPITATES IN SPARK PLASMA SINTERED TiB/Ti-6Al-4V COMPOSITES...ALPHA AND TITANIUM NITRIDE PRECIPITATES IN SPARK PLASMA SINTERED TiB/Ti-6Al-4V COMPOSITES (PREPRINT) 5a. CONTRACT NUMBER FA8650-08-C-5226 5b...distribution of TiN precipitates, as revealed by TEM studies. 15. SUBJECT TERMS Ti-6Al-4V; TiB; TiN; Spark Plasma Sintering ; Composite; α/β phase

Injector design for liner-on-target gas-puff experiments

NASA Astrophysics Data System (ADS)

Valenzuela, J. C.; Krasheninnikov, I.; Conti, F.; Wessel, F.; Fadeev, V.; Narkis, J.; Ross, M. P.; Rahman, H. U.; Ruskov, E.; Beg, F. N.

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ˜1 cm radius gas profile that satisfies the theoretical requirement for best performance on ˜1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Injector design for liner-on-target gas-puff experiments.

PubMed

Valenzuela, J C; Krasheninnikov, I; Conti, F; Wessel, F; Fadeev, V; Narkis, J; Ross, M P; Rahman, H U; Ruskov, E; Beg, F N

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ∼1 cm radius gas profile that satisfies the theoretical requirement for best performance on ∼1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Metal impurity fluxes and plasma-surface interactions in EXTRAP T2R

NASA Astrophysics Data System (ADS)

Bergsåker, H.; Menmuir, S.; Rachlew, E.; Brunsell, P. R.; Frassinetti, L.; Drake, J. R.

2008-03-01

The EXTRAP T2R is a large aspect ratio Reversed Field Pinch device. The main focus of interest for the experiments is the active feedback control of resistive wall modes [1]. With feedback it has been possible to prolong plasma discharges in T2R from about 20 ms to nearly 100 ms. In a series of experiments in T2R, in H- and D- plasmas with and without feedback, quantitative spectroscopy and passive collector probes have been used to study the flux of metal impurities. Time resolved spectroscopic measurements of Cr and Mo lines showed large metal release towards discharge termination without feedback. Discharge integrated fluxes of Cr, Fe, Ni and Mo were also measured with collector probes at wall position. Reasonable quantitative agreement was found between the spectroscopic and collector probe measurements. The roles of sputtering, thermal evaporation and arcing in impurity production are evaluated based on the composition of the measured impurity flux.

Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited).

PubMed

Valdivia, M P; Stutman, D; Stoeckl, C; Mileham, C; Begishev, I A; Theobald, W; Bromage, J; Regan, S P; Klein, S R; Muñoz-Cordovez, G; Vescovi, M; Valenzuela-Villaseca, V; Veloso, F

2016-11-01

Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Talbot-Lau X-ray Deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments

DOE PAGES

Valdivia, M. P.; Stutman, D.; Stoeckl, C.; ...

2016-04-21

Talbot-Lau X-ray Deflectometry has been developed as an electron density diagnostic for High Energy Density plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping was demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moire pattern formation and grating survival was also observed using a copper x-pinch driven at 400 kA, ~1 kA/ns. Lastly, these results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Analytical pyrolysis experiments of Titan aerosol analogues in preparation for the Cassini Huygens mission

NASA Technical Reports Server (NTRS)

Ehrenfreund, P.; Boon, J. J.; Commandeur, J.; Sagan, C.; Thompson, W. R.; Khare, B.

1995-01-01

Comparative pyrolysis mass spectrometric data of Titan aerosol analogs, called 'tholins', are presented. The Titan tholins were produced in the laboratory at Cornell by irradiation of simulated Titan atmospheres with high energy electrons in plasma discharge. Mass-spectrometry measurements were performed at FOM of the solid phase of various tholins by Curie-point pyrolysis Gas-Chromatography/Mass-Spectrometry (GCMS) and by temperature resolved in-source Pyrolysis Mass-Spectrometry to reveal the composition and evolution temperature of the dissociation products. The results presented here are used to further define the ACP (Aerosol Collector Pyrolyser)-GCMS experiment and provide a basis for modelling of aerosol composition on Titan and for the iterpretation of Titan atmosphere data from the Huygens probe in the future.

Experimental investigation of differential confinement effects in a rotating helicon plasma

NASA Astrophysics Data System (ADS)

Gueroult, Renaud; Evans, Eugene; Zweben, Stewart J.; Fisch, Nathaniel J.; Levinton, Fred

2014-10-01

Although plasmas have long been considered for isotope separation, challenges presented by nuclear waste remediation and nuclear spent fuel reprocessing have recently sparked a renewed interest for high-throughput plasma based mass separation techniques. Different filter concepts relying on rotating plasmas have been proposed to address these needs. However, one of the challenges common to these concepts is the need to control the plasma rotation profile, which is generally assumed to be provided by means of dedicated electrodes. An experimental effort aiming to evaluate the practicality of these plasma filter concepts has recently been started at PPPL. For this purpose, a linear helicon plasma source is used in combination with concentric ring electrodes. Preliminary biasing experiments results indicate floating potential profiles locally suitable for mass discrimination for different gas mixtures (Ar/Ne, Ar/N2, Ar/Kr). Radially resolved spectroscopic measurements and neutral gas composition analysis at two different axial positions are being planned to assess the mass separation effect. Work supported by US DOE under Contract No. DE-AC02-09CH11466.

Composition of plasma and atheromatous plaque among coronary artery disease subjects consuming coconut oil or sunflower oil as the cooking medium.

PubMed

Palazhy, Sabitha; Kamath, Prakash; Rajesh, P C; Vaidyanathan, Kannan; Nair, Shiv K; Vasudevan, D M

2012-12-01

Coconut oil, which is rich in medium-chain saturated fatty acids, is the principal cooking medium of the people of Kerala, India. Replacement of saturated fat with polyunsaturated fat is effective in reducing serum cholesterol levels. However, the effect of substituting coconut oil with sunflower oil on the fatty acid composition of plaque has not been thoroughly investigated. We therefore evaluated and compared the fatty acid composition of plasma and plaque among subjects consuming coconut oil or sunflower oil as the cooking medium. Endarterectomy samples and plasma samples were obtained from subjects who underwent coronary artery bypass grafts (n = 71). The subjects were grouped based on the type of oil they were using as their cooking medium (coconut oil or sunflower oil). The fatty acid composition in the plaques and the plasma was determined by HPLC and the data were analyzed statistically. Sunflower oil consumers had elevated concentrations of linoleic acid (p = 0.001) in plasma, while coconut oil users had higher myristic acid levels (p = 0.011) in plasma. Medium-chain fatty acids did not differ significantly between the two groups in the plasma. Medium-chain fatty acids were detected in the plaques in both groups of subjects. In contrast to previous reports, long-chain saturated fatty acids dominated the lipid content of plaque in this population, and the fatty acid composition of plaque was not significantly different between the two groups. No correlation between fatty acids of plasma and plaque was observed in either group. A change in cooking medium, although it altered the plasma fatty acid composition, was not reflected in the plaque composition.

In Situ Nanocalorimetric Investigations of Plasma Assisted Deposited Poly(ethylene oxide)-like Films by Specific Heat Spectroscopy.

PubMed

Madkou, Sherif; Melnichu, Iurii; Choukourov, Andrei; Krakovsky, Ivan; Biederman, Hynek; Schönhals, Andreas

2016-04-28

In recent years, highly cross-linked plasma polymers have started to unveil their potential in numerous biomedical applications in thin-film form. However, conventional diagnostic methods often fail due to their diverse molecular dynamics conformations. Here, glassy dynamics and the melting transition of thin PEO-like plasma assisted deposited (ppPEO) films (thickness 100 nm) were in situ studied by a combination of specific heat spectroscopy, utilizing a pJ/K sensitive ac-calorimeter chip, and composition analytical techniques. Different cross-linking densities were obtained by different plasma powers during the deposition of the films. Glassy dynamics were observed for all values of the plasma power. It was found that the glassy dynamics slows down with increasing the plasma power. Moreover, the underlying relaxation time spectra broaden indicating that the molecular motions become more heterogeneous with increasing plasma power. In a second set of the experiment, the melting behavior of the ppPEO films was studied. The melting temperature of ppPEO was found to decrease with increasing plasma power. This was explained by a decrease of the order in the crystals due to formation of chemical defects during the plasma process.

Effects of oxygen plasma treatment on domestic aramid fiber III reinforced bismaleimide composite interfacial properties

NASA Astrophysics Data System (ADS)

Shi, Chen; Wang, Jing; Chen, Ping; Feng, Jiayue; Cui, Jinyuan; Yang, Faze

2017-12-01

Domestic Aramid Fiber III (DAF III) was modified by oxygen plasma treatment. The fiber surface characteristics was observed by Scanning Electron Microscopy. The results showed that oxygen plasma treatment changed surface morphologies. The effects of oxygen plasma treatment on DAF III reinforced bismaleimides (BMI) composite bending and interfacial properties were investigated, respectively. The ILSS value increased from 49.3 MPa to 56.0 MPa (by 13.5%) after oxygen plasma treatment. The bending strength changed a little. Furthermore, the composite rupture mode changed from interfacial rupture to fiber or resin bulk rupture.

Addressing the challenges of plasma-surface interactions in NSTX-U*

DOE PAGES

Kaita, Robert; Abrams, Tyler; Jaworski, Michael; ...

2015-04-01

The importance of conditioning plasma-facing components (PFCs) has long been recognized as a critical element in obtaining high-performance plasmas in magnetic confinement devices. Lithium coatings, for example, have been used for decades for conditioning PFCs. Since the initial studies on the Tokamak Fusion Test Reactor, experiments on devices with different aspect ratios and magnetic geometries like the National Spherical Torus Experiment (NSTX) continue to show the relationship between lithium PFCs and good confinement and stability. While such results are promising, their empirical nature do not reflect the detailed relationship between PFCs and the dynamic conditions that occur in the tokamakmore » environment. A first step developing an understanding such complexity will be taken in the upgrade to NSTX (NSTX-U) that is nearing completion. New measurement capabilities include the Materials Analysis and Particle Probe (MAPP) for in situ surface analysis of samples exposed to tokamak plasmas. The OEDGE suite of codes, for example, will provide a new way to model the underlying mechanisms for such material migration in NSTX-U. This will lead to a better understanding of how plasma-facing surfaces evolve during a shot, and how the composition of the plasma facing surface influences the discharge performance we observe. This paper will provide an overview of these capabilities, and highlight their importance for NSTX-U plans to transition from carbon to high-Z PFCs.« less

Application of atmospheric pressure plasma in polymer and composite adhesion

NASA Astrophysics Data System (ADS)

Yu, Hang

An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and carboxyl groups, on the polymer surface after plasma treatment. The resulting strength of the bond based on lap-shear and T-peel tests correlates well with the concentration of oxygen on the polymer surface. The failure modes observed for lap-shear and T-peel tests changed from interfacial to cohesive after the plasma activation. Treating carbon-fiber-reinforced epoxy composites with the atmospheric plasma resulted in the removal of fluorinated contaminants in shallow surface layers. For contaminants that diffused deeply into the composite surface, mechanical abrasion was needed in addition to the plasma treatment to remove the impurities. While cleaning the composite, plasma also generated active oxygen groups on the substrate surface. The presence of these groups improved the adhesive bonding strength of the composite even in the presence of residual fluorine contaminants. Thus, it was speculated that plasma treatment can promote better polymer adhesion with or without fluorine contamination. Carbon nanotube sheets were also treated by the helium oxygen plasma, and the CNT surface turn from super hydrophobic to hydrophilic after a few seconds of exposure. The nanotube surface contained 15% of oxygen in the form of hydroxyl groups. Chemical coupling agents were added to the plasma activated CNT surfaces in order to crosslink the CNTs and to create bonding sites for the resin matrix. Stretched, activated and functionalized CNT was cured with dicyclopentadiene (DCPD) to produce a sheet composite with a tensile strength of 636 MPa, a modulus of 28 GPa, and a density of 1.4 g/cm 3. This may be compared to aerospace-grade aluminum with tensile strength of 572 MPa, modulus of 72 GPa, and density of 2.7 g/cm3. This work demonstrates that new high-strength composite can be produced with the use of atmospheric plasma activation and chemical crosslinking of the fiber matrix.

Latitudinal distribution of the Jovian plasma sheet ions observed by Juno JADE-I

NASA Astrophysics Data System (ADS)

Kim, T. K. H.; Valek, P. W.; McComas, D. J.; Allegrini, F.; Bagenal, F.; Bolton, S. J.; Connerney, J. E. P.; Ebert, R. W.; Levin, S.; Louarn, P.; Pollock, C. J.; Ranquist, D. A.; Szalay, J.; Thomsen, M. F.; Wilson, R. J.

2017-12-01

The Jovian plasma sheet is a region where the centrifugal force dominates the heavy ion plasma. Properties of the plasma sheet ions near the equatorial plane have been studied with in-situ measurements from the Pioneer, Voyager, and Galileo spacecraft. However, the ion properties for the off-equator regions are not well known due to the limited measurements. Juno is the first polar orbiting spacecraft that can investigate the high latitude region of the Jovian magnetosphere. With Juno's unique trajectory, we will investigate the latitudinal distribution of the Jovian plasma sheet ions using measurements from the Jovian Auroral Distributions Experiment Ion sensor (JADE-I). JADE-I measures an ion's energy-per-charge (E/Q) from 0.01 keV/q to 46.2 keV/q with an electrostatic analyzer (ESA) and a mass-per-charge (M/Q) up to 64 amu/q with a carbon-foil-based time-of-flight (TOF) mass spectrometer. We have shown that the ambiguity between and (both have M/Q of 16) can be resolved in JADE-I using a semi-empirical simulation tool based on carbon foil effects (i.e., charge state modification, angular scattering, and energy loss) from incident ions passing through the TOF mass spectrometer. Based on the simulation results, we have developed an Ion Composition Analysis Tool (ICAT) that determines ion composition at each energy step of JADE-I (total of 64 steps). The velocity distribution for each ion species can be obtained from the ion composition as a function of each energy step. Since there is an ambipolar electric field due to mobile electrons and equatorially confined heavy ions, we expect to see acceleration along the field line. This study will show the species separated velocity distribution at various latitudes to investigate how the plasma sheet ions evolve along the field line.

Thermally conductive tough flexible elastomers as composite of slide-ring materials and surface modified boron nitride particles via plasma in solution

NASA Astrophysics Data System (ADS)

Goto, Taku; Iida, Masaki; Tan, Helen; Liu, Chang; Mayumi, Koichi; Maeda, Rina; Kitahara, Koichi; Hatakeyama, Kazuto; Ito, Tsuyohito; Shimizu, Yoshiki; Yokoyama, Hideaki; Kimura, Kaoru; Ito, Kohzo; Hakuta, Yukiya; Terashima, Kazuo

2018-03-01

We have developed a thermally conductive flexible elastomer as a composite material with slide-ring (SR) materials and boron nitride (BN) particles surface-modified via plasma in solution. This composite shows excellent properties as a flexible insulator for thermal management. Surface modification of BN particles using plasma in solution increases the tensile strength, extension ratio at break, toughness, and rubber characteristics of the composites, compared to SR and non-modified BN, while the Young's modulus values are identical. Furthermore, the thermal conductivity also improved as a result of plasma surface modification.

Plasma-induced grafting of acrylic acid on bentonite for the removal of U(VI) from aqueous solution

NASA Astrophysics Data System (ADS)

Hongshan, ZHU; Shengxia, DUAN; Lei, CHEN; Ahmed, ALSAEDI; Tasawar, HAYAT; Jiaxing, LI

2017-11-01

Fabrication of reusable adsorbents with satisfactory adsorption capacity and using environment-friendly preparation processes is required for the environment-related applications. In this study, acrylic acid (AA) was grafted onto bentonite (BT) to generate an AA-graft-BT (AA-g-BT) composite using a plasma-induced grafting technique considered to be an environment-friendly method. The as-prepared composite was characterized by scanning electron microscopy, x-ray powder diffraction, thermal gravity analysis, Fourier transform infrared spectroscopy and Barrett-Emmett-Teller analysis, demonstrating the successful grafting of AA onto BT. In addition, the removal of uranium(VI) (U(VI)) from contaminated aqueous solutions was examined using the as-prepared composite. The influencing factors, including contact time, pH value, ionic strength, temperature, and initial concentration, for the removal of U(VI) were investigated by batch experiments. The experimental process fitted best with the pseudo-second-order kinetic and the Langmuir models. Moreover, thermodynamic investigation revealed a spontaneous and endothermic process. Compared with previous adsorbents, AA-g-BT has potential practical applications in treating U(VI)-contaminated solutions.

Dentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restoration

PubMed Central

Ritts, Andy Charles; Li, Hao; Yu, Qingsong; Xu, Changqi; Yao, Xiaomei; Hong, Liang; Wang, Yong

2010-01-01

The objective of this study is to investigate the treatment effects of non-thermal atmospheric gas plasmas on dentin surfaces for composite restoration. Extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. The dentin surfaces were treated by using a non-thermal atmospheric argon plasma brush for various durations. The molecular changes of the dentin surfaces were analyzed using FTIR/ATR and an increase in carbonyl groups on dentin surfaces was detected with plasma treated dentin. Adper Single Bond Plus adhesive and Filtek Z250 dental composite were applied as directed. To evaluate the dentin/composite interfacial bonding, the teeth thus prepared were sectioned into micro-bars as the specimens for tensile test. Student Newman Keuls tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment. However, the bonding strength to plasma treated inner dentin did not show any improvement. It was found that plasma treatment of peripheral dentin surface up to 100 s gave an increase in interfacial bonding strength, while a prolong plasma treatment of dentin surfaces, e.g., 5 min treatments, showed a decrease in interfacial bonding strength. PMID:20831586

Onlay bone augmentation on mouse calvarial bone using a hydroxyapatite/collagen composite material with total blood or platelet-rich plasma.

PubMed

Ohba, Seigo; Sumita, Yoshinori; Umebayashi, Mayumi; Yoshimura, Hitoshi; Yoshida, Hisato; Matsuda, Shinpei; Kimura, Hideki; Asahina, Izumi; Sano, Kazuo

2016-01-01

The aim of this study was to assess newly formed onlay bone on mouse calvarial bone using a new artificial bone material, a hydroxyapatite/collagen composite, with total blood or platelet-rich plasma. The hydroxyapatite/collagen composite material with normal saline, total blood or platelet-rich plasma was transplanted on mouse calvarial bone. The mice were sacrificed and the specimens were harvested four weeks after surgery. The newly formed bone area was measured on hematoxylin and eosin stained specimens using Image J software. The hydroxyapatite/collagen composite materials with total blood or platelet-rich plasma induced a significantly greater amount of newly formed bone than that with normal saline. Moreover, bone marrow was observed four weeks after surgery in the transplanted materials with total blood or platelet-rich plasma but not with normal saline. However, there were no significant differences in the amount of newly formed bone between materials used with total blood versus platelet-rich plasma. The hydroxyapatite/collagen composite material was valid for onlay bone augmentation and this material should be soaked in total blood or platelet-rich plasma prior to transplantation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurements of ion velocity separation and ionization in multi-species plasma shocks

NASA Astrophysics Data System (ADS)

Rinderknecht, Hans G.; Park, H.-S.; Ross, J. S.; Amendt, P. A.; Wilks, S. C.; Katz, J.; Hoffman, N. M.; Kagan, G.; Vold, E. L.; Keenan, B. D.; Simakov, A. N.; Chacón, L.

2018-05-01

The ion velocity structure of a strong collisional shock front in a plasma with multiple ion species is directly probed in laser-driven shock-tube experiments. Thomson scattering of a 263.25 nm probe beam is used to diagnose ion composition, temperature, and flow velocity in strong shocks ( M ˜6 ) propagating through low-density ( ρ˜0.1 mg/cc) plasmas composed of mixtures of hydrogen (98%) and neon (2%). Within the preheat region of the shock front, two velocity populations of ions are observed, a characteristic feature of strong plasma shocks. The ionization state of the Ne is observed to change within the shock front, demonstrating an ionization-timescale effect on the shock front structure. The forward-streaming proton feature is shown to be unexpectedly cool compared to predictions from ion Fokker-Planck simulations; the neon ionization gradient is evaluated as a possible cause.

Adhesion enhancement of Al coatings on carbon/epoxy composite surfaces by atmospheric plasma

NASA Astrophysics Data System (ADS)

Coulon, J. F.; Tournerie, N.; Maillard, H.

2013-10-01

Adhesion strengths between aluminium thin film coatings and manufactured carbon/epoxy composite surfaces were measured by assessing fracture tensile strengths using pull-off tests. The effect of the substrate roughness (nm to μm) of these composite surfaces on adhesion was studied by examining the surface free energies and adhesion strengths. The adhesion strengths of the coatings varied significantly. To improve the coating adhesion, each composite surface was treated with atmospheric plasma prior to deposition, which resulted in an increase in the surface free energy from approximately 40 mJ/m2 to 70 mJ/m2 because the plasma pretreatment led to the formation of hydrophilic Csbnd O and Cdbnd O bonds on the composite surfaces, as demonstrated by X-ray photoelectron spectroscopy analyses. The adhesion strengths of the coatings were enhanced for all surface roughnesses studied. In our study, the effect of mechanical adhesion due to roughness was separated from the effect of modifying the chemical bonds with plasma activation. The adhesion ability of the pure resin was relatively weak. Increasing the surface roughness largely improved the adhesion of the resin surface. Plasma treatment of the pure resin also increased the surface adhesion. Our study shows that plasma activation effectively enhances the adhesion of manufactured composites, even when the surface roughness is on the order of microns. The ageing of the surface activation was also investigated, and the results demonstrate that atmospheric plasma has potential for use in the pretreatment of composite materials.

Simulations of controlled spectral emission of Al plasmas generated by temporally tailored laser irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colombier, J. P.; Guillermin, M.; Garrelie, F.

2010-10-08

Hydrodynamics simulations and irradiation experiments were performed to correlate ul-trashort intensity envelopes of the laser fields and thermodynamical states reached by the emerging plasma phase in ablation regimes. We discuss the efficiency of energy coupling as a function of different intensity envelopes and the resulting temperature, density and ionization states since the energy delivery rate is an essential factor that predetermines the material thermodynamic evolution. Subsequently, we examine the plasma composition in calculating the proportion of neutral/ion species typical of LIBS signals and comparing it with neutral/ion ratios given by experimental results. Moreover, the calculations allow to investigate the efficiencymore » of nanoparticles generation from materials subjected to different heating rates. These can be related to hydrodynamic ejection of nanosized liquid layers upon the action of mechanic waves. With support from numerical simulations of the hydrodynamic advance of the excited matter, experiments revealed that mastering intensity envelopes of ultrashort laser pulse leads to further control on the ablation products. Emerging plasma phase in a hot state generates specific spectral emission patterns that can serve as indicators for its controlled formation and kinetic evolution.« less

Boron and silicon: Effects on growth, plasma lipids, urinary cyclic AMP and bone and brain mineral composition of male rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seaborn, C.D.; Nielsen, F.H.

1994-06-01

Because boron resembles silicon in its chemical properties, an experiment was performed to determine if excessive dietary boron would affect the response to silicon deprivation and, conversely, if silicon would influence the effects of an excessive intake of boron. Male weanling Sprague-Dawley rats were assigned to groups of 6 or 12 in a two-by-two factorially arranged experiment. Supplemented to a ground corn/casein diet containing 1.2 [mu]g silicon and 3 [mu]g boron per gram were silicon as sodium metasilicate at 0 or 50 [mu]g/g and boron as orthoboric acid at 0 or 500 [mu]g/g diet. At nine weeks, animals fed highmore » dietary boron had significantly decreased final body weights, liver-weight-to-body-weight ratios, urinary cAMP concentrations, plasma triglyceride, cholesterol, glycine, valine, leucine, and lysine concentrations and skull copper, sodium, and manganese concentrations. High dietary boron also significantly increased brain-weight-to-body-weight ratios, magnesium concentrations of femur, brain, and plasma, zinc concentration of femur, and iron concentration of skull. The bone mineral findings suggest that excess dietary boron exerts subtle effects on bone composition. Dietary silicon affected blood urea nitrogen, hematocrit, hemoglobin, and the concentrations of plasma threonine and aspartic acid in animals fed excess boron. Depression of the testes-weight-to-body-weight ratio of animals fed 500 [mu]g boron per gram diet was most marked in animals not fed silicon. Although excessive dietary boron did not markedly enhanced the response of rats to silicon deprivation, dietary silicon affected their response to high dietary boron. Thus, dietary silicon apparently can influence boron toxicity.« less

Production of continuous glass fiber using lunar simulant

NASA Technical Reports Server (NTRS)

Tucker, Dennis S.; Ethridge, Edwin C.; Curreri, Peter A.

1991-01-01

The processing parameters and mechanical properties of glass fibers pulled from simulated lunar basalt are tested. The simulant was prepared using a plasma technique. The composition is representative of a low titanium mare basalt (Apollo sample 10084). Lunar gravity experiments are to be performed utilizing parabolic aircraft free-fall maneuvers which yield 30 seconds of 1/6-g per maneuver.

Skylab

NASA Image and Video Library

1973-01-01

This chart describes Skylab's Extreme Ultraviolet (XUV) Coronal Spectroheliograph, one of the eight Apollo Telescope Mount facilities. It was designed to sequentially photograph the solar chromosphere and corona in selected ultraviolet wavelengths . The instrument also obtained information about composition, temperature, energy conversion and transfer, and plasma processes of the chromosphere and lower corona. The Marshall Space Flight Center had program management responsibility for the development of Skylab hardware and experiments.

Characterization of Mullite-Zirconia Composite Processed by Non-Transferred and Transferred Arc Plasma

NASA Astrophysics Data System (ADS)

Yugeswaran, S.; Selvarajan, V.; Lusvarghi, L.; I. Y. Tok, A.; D. Siva Rama, Krishna

2009-04-01

The arc plasma melting technique is a simple method to synthesize high temperature reaction composites. In this study, mullite-zirconia composite was synthesized by transferred and non-transferred arc plasma melting, and the results were compared. A mixture of alumina and zircon powders with a mole ratio of 3: 2 were ball milled for four hours and melted for two minutes in the transferred and non-transferred mode of plasma arcs. Argon and air were used as plasma forming gases. The phase and microstructural formation of melted samples were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The microstructure of the composites was found to be affected by the mode of melting. In transferred arc melting, zirconia flowers with uniform lines along with mullite whiskers were obtained. In the case of non-transferred arc plasma melting, mullite whiskers along with star shape zirconia were formed. Differential thermal analysis (DTA) of the synthesized mullite-zirconia composites provided a deeper understanding of the mechanisms of mullite formation during the two different processes.

Relation Between the Arc-Root Fluctuations, the Cold Boundary Layer Thickness and the Particle Thermal Treatment

NASA Astrophysics Data System (ADS)

Noguès, E.; Fauchais, P.; Vardelle, M.; Granger, P.

2007-12-01

In plasma spraying, the arc-root fluctuations, modifying the length and characteristics of the plasma jet, have an important influence on particle thermal treatment. These voltage fluctuations are strongly linked to the thickness of the cold boundary layer (CBL), surrounding the arc column. This thickness depends on the plasma spray parameters (composition and plasma forming gas mass flow rate, arc current, etc.) and the plasma torch design (anode-nozzle internal diameter and shape, etc.). In order to determine the influence of these different spray parameters on the CBL properties and voltage fluctuations, experiments were performed with two different plasma torches from Sulzer Metco. The first one is a PTF4 torch with a cylindrical anode-nozzle, working with Ar-H2 plasma gas mixtures and the second one is a 3MB torch with either a conical or a cylindrical anode-nozzle, working with N2-H2 plasma gas mixtures. Moreover, arc voltage fluctuations influence on particle thermal treatment was studied through the measurements of transient temperature and velocity of particles, issued from an yttria partially stabilized zirconia powder with a size distribution between 5 and 25 μm.

Spark plasma sintering of silicon carbide, multi-walled carbon nanotube and graphene reinforced zirconium diboride ceramic composite

NASA Astrophysics Data System (ADS)

Balaraman Yadhukulakrishnan, Govindaraajan

Scope and Method of Study: Space vehicles re-entering the earth's atmosphere experience very high temperatures due to aerodynamic heating. Ultra-high temperature ceramics (UHTC) with melting point higher than 3200°C are promising materials for thermal protection systems of such space vehicles re-entering the earth's atmosphere. Among several UHTC systems ZrB2 based ceramic composites are particularly important for thermal protection systems due to their better mechanical and thermoelectric properties and high oxidation resistance. In this study spark plasma sintering of SiC, carbon nanotubes (CNT) and graphene nano platelets (GNP) reinforced ZrB2 ultra-high temperature ceramic matrix composites is reported. Findings and Conclusions: Systematic investigations on the effect of reinforcement type (SiC, CNTs and GNP) and content (10-40 vol.% SiC, 2-6 vol.% CNTs and 2-6 vol.% GNP) on densification behavior, microstructure development, and mechanical properties (microhardness, bi-axial flexural strength, and indentation fracture toughness) are reported. With the similar SPS parameters near-full densification (>99% relative density) was achieved with 10-40 vol.% SiC, 4-6 vol.% CNT reinforced composites. Highly dense composites were obtained in 4-6 vol.% GNP reinforced composites. The SiC, CNT and GNP reinforcement improved the indentation fracture toughness of the composites through a range of toughening mechanisms, including particle shearing, crack deflection at the particle-matrix interface, and grain pull-outs for ZrB2-SiC composites, CNT pull-outs and crack deflection in ZrB2-CNT composites and crack deflection, crack bridging and GNP sheet pull-out for ZrB2 -GNP composites.

Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valdivia, M. P., E-mail: mpvaldivia@pha.jhu.edu; Stutman, D.; Stoeckl, C.

2016-11-15

Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25–29 J, 8–30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Diffusion in plasma: The Hall effect, compositional waves, and chemical spots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urpin, V., E-mail: Vadim.urpin@uv.es

2017-03-15

Diffusion caused by a combined influence of the electric current and Hall effect is considered, and it is argued that such diffusion can form inhomogeneities of a chemical composition in plasma. The considered mechanism can be responsible for the formation of element spots in laboratory and astrophysical plasmas. This current-driven diffusion can be accompanied by propagation of a particular type of waves in which the impurity number density oscillates alone. These compositional waves exist if the magnetic pressure in plasma is much greater than the gas pressure.

Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas

NASA Astrophysics Data System (ADS)

Goel, A.; Tarantino, P. M.; Lauben, D. S.; Close, S.

2015-04-01

An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments.

Effects of Electric Discharge Plasma Treatment on the Thermal Conductivity of Polymer-Metal Nitride/Carbide Composites

NASA Astrophysics Data System (ADS)

Parali, Levent; Kurbanov, Mirza A.; Bayramov, Azad A.; Tatardar, Farida N.; Sultanakhmedova, Ramazanova I.; Xanlar, Huseynova Gulnara

2015-11-01

High-density polymer composites with semiconductor or dielectric fillers such as aluminum nitride (AIN), aluminum oxide (Al2O3), titanium carbide (TiC), titanium nitride (TiN), boron nitride (BN), silicon nitride (Si3N4), and titanium carbonitride (TiCN) were prepared by the hot pressing method. Each powder phase of the composites was exposed to an electric discharge plasma process before composite formation. The effects of the electric discharge plasma process and the filler content (volume fraction) on the thermal conductivity, volt-ampere characteristics, thermally stimulated depolarization current, as well as electrical and mechanical strength were investigated. The results of the study indicate that, with increasing filler volume fraction, the thermal conductivity of the samples also increased. Furthermore, the thermal conductivity, and electrophysical and mechanical properties of the high-density polyethylene + 70% BN composite modified using the electric discharge plasma showed improvement when compared with that without electric discharge plasma treatment.

Survey of Voyager plasma science ions at Jupiter: 1. Analysis method

NASA Astrophysics Data System (ADS)

Bagenal, F.; Dougherty, L. P.; Bodisch, K. M.; Richardson, J. D.; Belcher, J. M.

2017-08-01

The Voyagers 1 and 2 spacecraft flew by Jupiter in March and July of 1979, respectively. The Plasma Science instrument (PLS) acquired detailed measurements of the plasma environment in the equatorial region of the magnetosphere between 4.9 and 4 RJ. While bulk plasma properties such as charge density, ion temperature, and bulk flow were reasonably well determined, the ion composition was only well constrained in occasional regions of cold plasma. The ion data obtained by the PLS instrument have been reanalyzed using physical chemistry models to constrain the composition and reduce the number of free parameters, particularly in regions of hotter plasma. This paper describes the method used for fitting the plasma data and presents the results versus time. Two companion papers describe the composition of heavy ions and present analysis of protons plus other minor ions.

Sulphur tracer experiments in laboratory animals using 34S-labelled yeast.

PubMed

Martínez-Sierra, J Giner; Moreno Sanz, F; Herrero Espílez, P; Marchante Gayón, J M; Rodríguez Fernández, J; García Alonso, J I

2013-03-01

We have evaluated the use of (34)S-labelled yeast to perform sulphur metabolic tracer experiments in laboratory animals. The proof of principle work included the selection of the culture conditions for the preparation of sulphur labelled yeast, the study of the suitability of this labelled yeast as sulphur source for tracer studies using in vitro gastrointestinal digestion and the administration of the (34)S-labelled yeast to laboratory animals to follow the fate and distribution of (34)S in the organism. For in vitro gastrointestinal digestion, the combination of sodium dodecyl sulphate-polyacrylamide gel electrophoresis and high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS) showed that labelled methionine, cysteine and other low molecular weight sulphur-containing biomolecules were the major components in the digested extracts of the labelled yeast. Next, in vivo kinetic experiments were performed in healthy Wistar rats after the oral administration of (34)S-labelled yeast. The isotopic composition of total sulphur in tissues, urine and faeces was measured by double-focusing inductively coupled plasma mass spectrometry after microwave digestion. It was observed that measurable isotopic enrichments were detected in all samples. Finally, initial investigations on sulphur isotopic composition of serum and urine samples by HPLC-ICP-MS have been carried out. For serum samples, no conclusive data were obtained. Interestingly, chromatographic analysis of urine samples showed differential isotope enrichment for several sulphur-containing biomolecules.

Microwave and plasma-assisted modification of composite fiber surface topography

DOEpatents

Paulauskas, Felix L [Knoxville, TN; White, Terry L [Knoxville, TN; Bigelow, Timothy S [Knoxville, TN

2003-02-04

The present invention introduces a novel method for producing an undulated surface on composite fibers using plasma technology and microwave radiation. The undulated surface improves the mechanical interlocking of the fibers to composite resins and enhances the mechanical strength and interfacial sheer strength of the composites in which they are introduced.

Ion composition and temperature in the topside ionosphere.

NASA Technical Reports Server (NTRS)

Brace, L. H.; Dunham, G. S.; Mayr, H. G.

1967-01-01

Particle and energy continuity equations derived and solved by computer method ion composition and plasma temperature measured by Explorer XXII PARTICLE and energy continuity equations derived and solved by computer method for ion composition and plasma temperature measured by Explorer XXII

Normalization of laser-induced breakdown spectroscopy spectra using a plastic optical fiber light collector and acoustic sensor device.

PubMed

Anabitarte, Francisco; Rodríguez-Cobo, Luis; López-Higuera, José-Miguel; Cobo, Adolfo

2012-12-01

To estimate the acoustic plasma energy in laser-induced breakdown spectroscopy (LIBS) experiments, a light collecting and acoustic sensing device based on a coil of plastic optical fiber (POF) is proposed. The speckle perturbation induced by the plasma acoustic energy was monitored using a CCD camera placed at the end of a coil of multimode POF and processed with an intraimage contrast ratio method. The results were successfully verified with the acoustic energy measured by a reference microphone. The proposed device is useful for normalizing LIBS spectra, enabling a better estimation of the sample's chemical composition.

Transport mechanisms through PE-CVD coatings: influence of temperature, coating properties and defects on permeation of water vapour

NASA Astrophysics Data System (ADS)

Kirchheim, Dennis; Jaritz, Montgomery; Mitschker, Felix; Gebhard, Maximilian; Brochhagen, Markus; Hopmann, Christian; Böke, Marc; Devi, Anjana; Awakowicz, Peter; Dahlmann, Rainer

2017-03-01

Gas transport mechanisms through plastics are usually described by the temperature-dependent Arrhenius-model and compositions of several plastic layers are represented by the CLT. When it comes to thin films such as plasma-enhanced chemical vapour deposition (PE-CVD) or plasma-enhanced atomic layer deposition (PE-ALD) coatings on substrates of polymeric material, a universal model is lacking. While existing models describe diffusion through defects, these models presume that permeation does not occur by other means of transport mechanisms. This paper correlates the existing transport models with data from water vapour transmission experiments.

Lipomobilization in periparturient dairy cows influences the composition of plasma nonesterified fatty acids and leukocyte phospholipid fatty acids.

PubMed

Contreras, G A; O'Boyle, N J; Herdt, T H; Sordillo, L M

2010-06-01

The periparturient period is characterized by sudden changes in metabolic and immune cell functions that predispose dairy cows to increased incidence of disease. Metabolic changes include alterations in the energy balance that lead to increased lipomobilization with consequent elevation of plasma nonesterified fatty acids (NEFA) concentrations. The objective of this study was to establish the influence of lipomobilization on fatty acid profiles within plasma lipid fractions and leukocyte phospholipid composition. Blood samples from 10 dairy cows were collected at 14 and 7 d before due date, at calving, and at 7, 14, and 30 d after calving. Total lipids and lipid fractions were extracted from plasma and peripheral blood mononuclear cells. The degree of lipomobilization was characterized by measurement of plasma NEFA concentrations. The fatty acid profile of plasma NEFA, plasma phospholipids, and leukocyte phospholipids differed from the composition of total lipids in plasma, where linoleic acid was the most common fatty acid. Around parturition and during early lactation, the proportion of palmitic acid significantly increased in the plasma NEFA and phospholipid fractions with a concomitant increase in the phospholipid fatty acid profile of leukocytes. In contrast, the phospholipid fraction of long-chain polyunsaturated fatty acids in leukocytes was diminished during the periparturient period, especially during the first 2 wk following parturition. This study showed that the composition of total plasma lipids does not necessarily reflect the NEFA and phospholipid fractions in periparturient dairy cows. These findings are significant because it is the plasma phospholipid fraction that contributes to fatty acid composition of membrane phospholipids. Increased availability of certain saturated fatty acids in the NEFA phospholipid fractions may contribute to altered leukocyte functions during the periparturient period. 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Correlation between the plasma characteristics and the surface chemistry of plasma-treated polymers through partial least-squares analysis.

PubMed

Mavadat, Maryam; Ghasemzadeh-Barvarz, Massoud; Turgeon, Stéphane; Duchesne, Carl; Laroche, Gaétan

2013-12-23

We investigated the effect of various plasma parameters (relative density of atomic N and H, plasma temperature, and vibrational temperature) and process conditions (pressure and H2/(N2 + H2) ratio) on the chemical composition of modified poly(tetrafluoroethylene) (PTFE). The plasma parameters were measured by means of near-infrared (NIR) and UV-visible emission spectroscopy with and without actinometry. The process conditions of the N2-H2 microwave discharges were set at various pressures ranging from 100 to 2000 mTorr and H2/(N2+H2) gas mixture ratios between 0 and 0.4. The surface chemical composition of the modified polymers was determined by X-ray photoelectron spectroscopy (XPS). A mathematical model was constructed using the partial least-squares regression algorithm to correlate the plasma information (process condition and plasma parameters as determined by emission spectroscopy) with the modified surface characteristics. To construct the model, a set of data input variables containing process conditions and plasma parameters were generated, as well as a response matrix containing the surface composition of the polymer. This model was used to predict the composition of PTFE surfaces subjected to N2-H2 plasma treatment. Contrary to what is generally accepted in the literature, the present data demonstrate that hydrogen is not directly involved in the defluorination of the surface but rather produces atomic nitrogen and/or NH radicals that are shown to be at the origin of fluorine atom removal from the polymer surface. The results show that process conditions alone do not suffice in predicting the surface chemical composition and that the plasma characteristics, which cannot be easily correlated with these conditions, should be considered. Process optimization and control would benefit from plasma diagnostics, particularly infrared emission spectroscopy.

Influence of Atmospheric Pressure and Composition on LIBS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hatch, Jeremy J.; Scott, Jill R.; Effenberger, A. J. Jr.

2014-03-01

Most LIBS experiments are conducted at standard atmospheric pressure in air. However, there are LIBS studies that vary the pressure and composition of the gas. These studies have provided insights into fundamentals of the mechanisms that lead to the emission and methods for improving the quality of LIBS spectra. These atmospheric studies are difficult because the effects of pressure and gas composition and interconnected, making interpretation of the results difficult. The influence of pressures below and above 760 Torr have been explored. Performing LIBS on a surface at reduced pressures (<760 Torr) can result in enhanced spectra due to highermore » resolution, increased intensity, improved signal-to-noise (S/N), and increased ablation. Lower pressures produce increased resolution because the line width in LIBS spectra is predominantly due to Stark and Doppler broadening. Stark broadening is primarily caused from collisions between electrons and atoms, while Doppler broadening is proportional to the plasma temperature. Close examination using a high resolution spectrometer reveals that spectra show significant peak broadening and self-absorption as pressures increase, especially for pressures >760 Torr. During LIBS plasma expansion, energy is lost to the surrounding atmosphere, which reduces the lifetime of the laser plasma. Therefore, reducing the pressure increases the lifetime of the plasma, allowing more light from the laser plasma to be collected; thus, increasing the observed signal intensity. However, if pressures are too low (<10 Torr), then there is a steep drop in LIBS spectral intensity. This loss in intensity is mostly due to a disordered plasma that results from the lack of sufficient atmosphere to provide adequate confinement. At reduced pressures, the plasma expands into a less dense atmosphere, which results in a less dense shock wave. The reduced density in the shock wave results in reduced plasma shielding, allowing more photons to reach the sample. Increasing the number of photons interacting with the sample surface results in increased ablation, which can lead to increased intensity. The composition of the background gas has been shown to greatly influence the observed LIBS spectra by altering the plasma temperature, electron density, mass removal, and plasma shielding that impact the emission intensity and peak resolution. It has been reported that atmospheric Ar results in the highest plasma temperature and electron density, while a He atmosphere results in the lowest plasma temperatures and electron density. Studying temporal data, it was also found that Ar had the slowest decay of both electron density and plasma temperature, while He had the fastest decay in both parameters. The higher plasma temperature and electron density results in an increase in line broadenin, or poor resolution, for Ar compared to He. A rapidly developing LIBS plasma with a sufficient amount of electrons can absorb a significant portion of the laser pulse through inverse Bremsstahlung. Ar (15.8 eV ) is more easily ionized than He (24.4 eV). The breakdown threshold for He at 760 Torr is approximately 3 times greater than Ar and approximately 5 times greater at 100 Torr. The lower breakdown threshold in Ar, compared to He, creates an environment favorable for plasma shielding, which reduces sample vaporization and leads to a weaker LIBS signal.« less

Mechanical and thermal properties of short-coirfiber-reinforced natural rubber/polyethylene composites

NASA Astrophysics Data System (ADS)

Xu, Zh. H.; Kong, Zh. N.

2014-07-01

Natural rubber (NR) and polyethylene (PE) composites were compounded with chemically treated coir fibers by using a heated two-roll mill. Two chemical treatments of the fibers — by silane and sodium hydroxide — were carried out to improve the interfacial adhesion between them and the polyethylene matrix. The mechanical properties of the composites obtained were evaluated and compared with those made from a neat polymer and untreated fibers. The mechanical properties of the composites, such as the tensile strength, Young's modulus, and the elongation at break, were examined, and their shrinkage and flame retardant characteristics were measured. From these experiments, the effect of plasma treatment on the mechanical-physical behavior of coconut-fiberreinforced NR/PE composites was identified. In addition, their thermal characteristics were evaluated, and the results showed a slight decrease in them with increasing content of coir fibers.

Hemocompatible polyethersulfone/polyurethane composite membrane for high-performance antifouling and antithrombotic dialyzer.

PubMed

Yin, Zehua; Cheng, Chong; Qin, Hui; Nie, Chuanxiong; He, Chao; Zhao, Changsheng

2015-01-01

Researches on blood purification membranes are fuelled by diverse clinical needs, such as hemodialysis, hemodiafiltration, hemofiltration, plasmapheresis, and plasma collection. To approach high-performance dialyzer, the integrated antifouling and antithrombotic properties are highly necessary for the design/modification of advanced artificial membranes. In this study, we propose and demonstrate that the physical blend of triblock polyurethane (PU) and polyethersulfone (PES) may advance the performance of hemodialysis membranes with greatly enhanced blood compatibility. It was found that the triblock PU could be blended with PES at high ratio owing to their excellent miscibility. The surfaces of the PES/PU composite membranes were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurement, and surface ζ-potentials. The results indicated that the membrane surfaces were assembled with hydrophilic segregation layer owing to the migration of amphiphilic PU segments during membrane preparation, which might confer the composite membranes with superior hemocompatibility. The cross-section scanning electron microscopy images of the composite membranes exhibited structure transformation from finger-like structure to sponge-like structure, which indicated that the composite membrane had tunable porosity and permeability. The further ultrafiltration experiments indicated that the composite membranes showed increased permeability and excellent antifouling ability. The blood compatibility observation indicated that PES/PU composite membranes owned decreased protein adsorption, suppressed platelet adhesion, and prolonged plasma recalcification time. These results indicated that the PES/PU composite membranes exhibited enhanced antifouling and antithrombotic properties than the pristine PES membrane. The strategy may forward the fabrication of blood compatible composite membranes for clinical blood dialysis by using the various functional miscible polymers. © 2014 Wiley Periodicals, Inc.

New Horizons at Pluto

NASA Technical Reports Server (NTRS)

2007-01-01

Artist's concept of the New Horizons spacecraft as it approaches Pluto and its largest moon, Charon, in July 2015. The craft's miniature cameras, radio science experiment, ultraviolet and infrared spectrometers and space plasma experiments will characterize the global geology and geomorphology of Pluto and Charon, map their surface compositions and temperatures, and examine Pluto's atmosphere in detail. The spacecraft's most prominent design feature is a nearly 7-foot (2.1-meter) dish antenna, through which it will communicate with Earth from as far as 4.7 billion miles (7.5 billion kilometers) away.

Non-thermal Atmospheric Plasma Treatment for Deactivation of Oral Bacteria and Improvement of Dental Composite Restoration

NASA Astrophysics Data System (ADS)

Yu, Qing Song; Li, H.; Ritts, A. C.; Yang, B.; Chen, M.; Hong, L.; Xu, C.; Yao, X.; Wang, Y.

This paper reviews our recent research results of using non-thermal ­atmospheric plasmas for oral bacterial deactivation and for composite restoration improvement. Oral bacteria of Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. The plasma exposure time for a 99.9999% cell reduction was less than 15 s for S. mutans and within 5 min for L. acidophilus. To evaluate the dentin/composite interfacial bonding, extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. After dental composite application and light curing, the teeth were then sectioned into micro-bars as the specimens for microtensile test. Student Newman Keuls (SNK) tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment of the dentin surfaces. These findings indicated that non-thermal atmospheric plasma technology is very promising for dental clinical applications.

Treatment of refractory powders by a novel, high enthalpy dc plasma

NASA Astrophysics Data System (ADS)

Pershin, L.; Mitrasinovic, A.; Mostaghimi, J.

2013-06-01

Thermophysical properties of CO2-CH4 mixtures at high temperatures are very attractive for materials processing. In comparison with argon, at the same temperature, such a mixture possesses much higher enthalpy and higher thermal conductivity. At high temperatures, CO2-CH4 mixture has a complex composition with strong presence of CO which, in the case of powder treatment, could reduce oxidation. In this work, a dc plasma torch with graphite cathode was used to study the effect of plasma gas composition on spheroidization of tungsten carbide and alumina powders. Two different gas compositions were used to generate the plasma while the torch current was kept at 300 A. Various techniques were employed to assess the average concentration of carbides and oxides and the final shape of the treated powders. Process parameters such as input power and plasma gas composition allow controlling the degree of powder oxidation and spheroidization of high melting point ceramic powders.

Ion bombardment experiments suggesting an origin for organic particles in pre-cometary and cometary ices

NASA Technical Reports Server (NTRS)

Wdowiak, Thomas J.; Robinson, Edward L.; Flickinger, Gregory C.; Boyd, David A.

1989-01-01

During the Giotto and Vega encounters with Comet Halley both organic particles called CHON and energetic ions were detected. The acceleration of ions to hundreds of keV in the vicinity of the bow shock and near the nucleus may be a demonstration of a situation occurring in the early solar system (perhaps during the T Tauri stage) that led to the formation of organic particles only now released. Utilizing a Van de Graaff accelerator and a target chamber having cryogenic and mass spectrometer capabilities, frozen gases were bombarded at 10 K with 175 keV protons with the result that fluffy solid material remains after sublimation of the ice. Initial experiments were carried out with a gas mixture in parts of 170 carbon monoxide, 170 argon, 25 water, 20 nitrogen, and 15 methane formulated to reflect an interstellar composition in experiments involving the freezing out of the products of a plasma. The plasma experiments resulted in a varnish-like film residue that exhibited luminescence when excited with ultraviolet radiation, while the ion bombardment created particulate material that was not luminescent.

Plasma chemistry for inorganic materials

NASA Technical Reports Server (NTRS)

Matsumoto, O.

1980-01-01

Practical application of plasma chemistry to the development of inorganic materials using both low temperature and warm plasmas are summarized. Topics cover: the surface nitrification and oxidation of metals; chemical vapor deposition; formation of minute oxide particles; the composition of oxides from chloride vapor; the composition of carbides and nitrides; freezing high temperature phases by plasma arc welding and plasma jet; use of plasma in the development of a substitute for petroleum; the production of silicon for use in solar cell batteries; and insulating the inner surface of nuclear fusion reactor walls.

Synthesis and Characterization of Novel Compound Clusters

DTIC Science & Technology

1997-08-26

also be intrinsically stable, they cannot be formed by this plasma chemistry presumably because the metals are less reactive. Plasma chemistry reactions...samples without the presence of hydrogen. Vaporization of these composite samples produces the metal carbide clusters in many cases where plasma chemistry does...antimony or bismuth cannot be produced by the hydrocarbon plasma chemistry method, but they are produced readily from composite sample (metal film on

Mechanical properties of epoxy composites with plasma-modified rice-husk-derived nanosilica

NASA Astrophysics Data System (ADS)

Hubilla, Fatima Athena D.; Panghulan, Glenson R.; Pechardo, Jason; Vasquez, Magdaleno R., Jr.

2018-01-01

In this study, we explored the use of rice-husk-derived nanosilica (nSiO2) as fillers in epoxy resins. The nSiO2 was irradiated with a capacitively coupled 13.56 MHz radio frequency (RF) plasma using an admixture of argon (Ar) and hexamethyldisiloxane (HMDSO) or 1,7-octadiene (OD) monomers. The plasma-polymerized nSiO2 was loaded at various concentrations (1-5%) into the epoxy matrix. Surface hydrophobicity of the plasma-treated nSiO2-filled composites increased, which is attributed to the attachment of functional groups from the monomer gases on the silica surface. Microhardness increased by at least 10% upon the inclusion of plasma-modified nSiO2 compared with pristine nSiO2-epoxy composites. Likewise, hardness increased with increasing loading volume, with the HMDSO-treated silica composite recording the highest increase. Elastic moduli of the composites also showed an increase of at least 14% compared with untreated nSiO2-filled composites. This work demonstrated the use of rice husk, an agricultural waste, as a nSiO2 source for epoxy resin fillers.

A study on porous super austenitic stainless steel coating for improvement of bone ingrowth

NASA Astrophysics Data System (ADS)

Oh, Keun Taek; Park, Yong Soo

1998-02-01

In this study, the prostheses were provided with the bone ingrowth site by coating the super stainless steel powder on the same substrate (S32050) using plasma spraying method. Plasma current and powder feed rate varied in this study based on the optimum conditions of previous experiments. The optimum conditions for satisfying the requirements of the porous coatings were found. The characteristics of the coatings were observed according to the experimental parameters. It was found that plasma current influenced the chemical composition (the oxides, Cr component), melting and flattening degree of the sprayed particle (surface roughness, thickness of the splat, pores) and corrosion -resistance. The powder feed rate also influenced the coating thickness and efficiency. The amount of Cr was increased, but Ni, Mo, Fe were decreased with plasma current. An increase of Cr in the coating surface corresponded to an increase in the amount of the formed oxides. The coated specimen in 400A had a high corrosion-resistance owing to a dense coating. The coated specimen in 500A formed many types of oxides. In 300A current, the coating was rough with many pores, and corrosion-resistance of the coating showed a large variation according to the oxidation and compositional change. Specifically at 100 g/min powder feed rate in a 300A current, the coating was rough and porous, nevertheless, it had high corrosion resistance.

Plasma Polypyrrole Coated Hybrid Composites with Improved Mechanical and Electrical Properties for Aerospace Applications

NASA Astrophysics Data System (ADS)

Yavuz, Hande; Bai, Jinbo

2018-06-01

This paper deals with the dielectric barrier discharge assisted continuous plasma polypyrrole deposition on CNT-grafted carbon fibers for conductive composite applications. The simultaneous effects of three controllable factors have been studied on the electrical resistivity (ER) of these two material systems based on multivariate experimental design methodology. A posterior probability referring to Benjamini-Hochberg (BH) false discovery rate was explored as multiple testing corrections of the t-test p values. BH significance threshold of 0.05 was produced truly statistically significant coefficients to describe ER of two material systems. A group of plasma modified samples was chosen to be used for composite manufacturing to drive an assessment of interlaminar shear properties under static loading. Transversal and longitudinal electrical resistivity (DC, ω =0) of composite samples were studied to compare both the effects of CNT grafting and plasma modification on ER of resultant composites.

Plasma Polypyrrole Coated Hybrid Composites with Improved Mechanical and Electrical Properties for Aerospace Applications

NASA Astrophysics Data System (ADS)

Yavuz, Hande; Bai, Jinbo

2017-09-01

This paper deals with the dielectric barrier discharge assisted continuous plasma polypyrrole deposition on CNT-grafted carbon fibers for conductive composite applications. The simultaneous effects of three controllable factors have been studied on the electrical resistivity (ER) of these two material systems based on multivariate experimental design methodology. A posterior probability referring to Benjamini-Hochberg (BH) false discovery rate was explored as multiple testing corrections of the t-test p values. BH significance threshold of 0.05 was produced truly statistically significant coefficients to describe ER of two material systems. A group of plasma modified samples was chosen to be used for composite manufacturing to drive an assessment of interlaminar shear properties under static loading. Transversal and longitudinal electrical resistivity (DC, ω =0) of composite samples were studied to compare both the effects of CNT grafting and plasma modification on ER of resultant composites.

Structure and characteristics of functional powder composite materials obtained by spark plasma sintering

NASA Astrophysics Data System (ADS)

Oglezneva, S. A.; Kachenyuk, M. N.; Kulmeteva, V. B.; Ogleznev, N. B.

2017-07-01

The article describes the results of spark plasma sintering of ceramic materials based on titanium carbide, titanium carbosilicide, ceramic composite materials based on zirconium oxide, strengthened by carbon nanostructures and composite materials of electrotechnical purpose based on copper with addition of carbon structures and titanium carbosilicide. The research shows that the spark plasma sintering can achieve relative density of the material up to 98%. The effect of sintering temperature on the phase composition, density and porosity of the final product has been studied. It was found that with addition of carbon nanostructures the relative density and hardness decrease, but the fracture strength of ZrO2 increases up to times 2. The relative erosion resistance of the electrodes made of composite copper-based powder materials, obtained by spark plasma sintering during electroerosion treatment of tool steel exceeds that parameter of pure copper up to times 15.

Synthesis, Consolidation and Characterization of Sol-gel Derived Tantalum-Tungsten Oxide Thermite Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cervantes, O

2010-06-01

Energetic composite powders consisting of sol-gel (SG) derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the SG derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The SG derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO3) energetic composite was consolidated to a density of 9.17 g·cm-3more » or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy.« less

Relationship between plasma adropin levels and body composition and lipid characteristics amongst young adolescents in Taiwan.

PubMed

Chang, Jin-Biou; Chu, Nain-Feng; Lin, Fu-Huang; Hsu, Jhu-Ting; Chen, Pi-Yun

Adropin is a 76 amino acid peptide hormone with a molecular weight of 4999.9Da that may be associated with energy homeostasis, insulin resistance and lipid metabolism in mice and human. There is only a few studies that examine plasma adropin levels and body composition in children. This study is to evaluate the relationship between plasma adropin levels, body composition and lipid variables amongst young adolescents in Taiwan. We examined 492 adolescents (269 females and 223 males) ranging from 12 to 15 years old, with a mean age of 13.6 years. Body composition was measured using impedance method by Tanita-BC418. Plasma lipid variables were measured using standard methods and plasma adropin levels were measured using the ELISA method. There was no significant difference in plasma adropin levels between males and females (3.52 vs. 3.58ng/ml). Plasma adropin levels were negatively correlated with fat free mass (r=-0.12, p<0.01). More interestingly, children with higher plasma adropin levels had lower waist-to-hip ratios (WHR) and lower body fat percentage by mass. Furthermore, there is no difference in lipid profiles in high vs. low adropin subjects. Plasma adropin levels are not consistency associated with body composition and no association with lipid variables amongst Taiwanese adolescents. The role of adropin in the development of obesity is still not clear, and further studies are need especially for children. Copyright © 2017 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

Hemocompatibility and cytocompatibility of pristine and plasma-treated silver-zeolite-chitosan composites

NASA Astrophysics Data System (ADS)

Taaca, Kathrina Lois M.; Vasquez, Magdaleno R.

2018-02-01

Silver-exchanged zeolite-chitosan (AgZ-Ch) composites with varying AgZ content were prepared by solvent casting and modified under argon (Ar) plasma excited by a 13.56 MHz radio frequency (RF) power source. Silver (Ag) was successfully incorporated in a natural zeolite host without losing its antibacterial activity against Escherichia coli and Staphylococcus aureus. The AgZ particles were incorporated into a chitosan matrix without making significant changes in the matrix structure. The composites also exhibited antibacterial sensitivity due to the inclusion of AgZ. Plasma treatment enhanced the surface wettability of polar and nonpolar test liquids of the composites. The average increase in total surface free energy after treatment was around 49% with the polar component having a significant change. Cytocompatibility tests showed at least 87% cell viability for pristine and plasma-treated composites comparable with supplemented RPMI as positive control. Hemocompatibility tests revealed that pristine composites does not promote hemolysis and the blood clotting ability is less than 10 min. Coupled with antibacterial property, the fabricated composites have promising biomedical applications.

Artificial ionospheric modification: The Metal Oxide Space Cloud experiment

NASA Astrophysics Data System (ADS)

Caton, Ronald G.; Pedersen, Todd R.; Groves, Keith M.; Hines, Jack; Cannon, Paul S.; Jackson-Booth, Natasha; Parris, Richard T.; Holmes, Jeffrey M.; Su, Yi-Jiun; Mishin, Evgeny V.; Roddy, Patrick A.; Viggiano, Albert A.; Shuman, Nicholas S.; Ard, Shaun G.; Bernhardt, Paul A.; Siefring, Carl L.; Retterer, John; Kudeki, Erhan; Reyes, Pablo M.

2017-05-01

Clouds of vaporized samarium (Sm) were released during sounding rocket flights from the Reagan Test Site, Kwajalein Atoll in May 2013 as part of the Metal Oxide Space Cloud (MOSC) experiment. A network of ground-based sensors observed the resulting clouds from five locations in the Republic of the Marshall Islands. Of primary interest was an examination of the extent to which a tailored radio frequency (RF) propagation environment could be generated through artificial ionospheric modification. The MOSC experiment consisted of launches near dusk on two separate evenings each releasing 6 kg of Sm vapor at altitudes near 170 km and 180 km. Localized plasma clouds were generated through a combination of photoionization and chemi-ionization (Sm + O → SmO+ + e-) processes producing signatures visible in optical sensors, incoherent scatter radar, and in high-frequency (HF) diagnostics. Here we present an overview of the experiment payloads, document the flight characteristics, and describe the experimental measurements conducted throughout the 2 week launch window. Multi-instrument analysis including incoherent scatter observations, HF soundings, RF beacon measurements, and optical data provided the opportunity for a comprehensive characterization of the physical, spectral, and plasma density composition of the artificial plasma clouds as a function of space and time. A series of companion papers submitted along with this experimental overview provide more detail on the individual elements for interested readers.

Anomalously high potentials observed on ISEE

NASA Technical Reports Server (NTRS)

Whipple, E. C.; Krinsky, I. S.; Torbert, R. B.; Olsen, R. C.

1985-01-01

Data from two electric field experiments and from the plasma composition experiment on ISEE-1 are used to show that the spacecraft charged to close to -70 V in sunlight at 0700 UT on March 17, 1978. Data from the electron spectrometer experiment show that there was a potential barrier of -10 to -20 V about the spacecraft during this event. The potential barrier was effective in turning back emitted photoelectrons to the spacecraft. The stringent electrostatic cleanliness specifications imposed on ISEE make the presence of differential charging unlikely. Modeling of this event is required to determine if the barrier was produced by the presence of space charge.

High heat flux composites for plasma-facing materials

NASA Astrophysics Data System (ADS)

Ting, J.-M.; Lake, M. L.

1994-09-01

Vapor grown carbon fiber (VGCF) has been shown to have the highest thermal conductivity of all carbon fiber currently available. This property holds potential of increasing the thickness and longevity of fusion reactor plasma-facing materials. The use of VGCF as a reinforcement in carbon/carbon composites has been explored, as well as methods of joining these plasma-facing materials to copper alloy heat pipes. In extensive study of VGCF/carbon matrix composites, the influence of fiber volume fraction, density, densification method, and heat treatment on composite properties were investigated. Joining of VGCF/carbon composites to copper and beryllium to copper using a novel alloying method was studied. The joint interface was examined by RBS analysis and thermal conductance.

Strength of the phase change materials on loading with the products of electric explosion of conductors

NASA Astrophysics Data System (ADS)

Savenkov, Georgiy; Morozov, Viktor; Kats, Victor

2018-05-01

Results of the experimentation on the destruction of the phase change materials (beeswax and paraffin) by the electric explosion of conductors are presented. The process of the explosion of copper and nickel titanium wires in both pure PCM and its mixture with nonosized additives of cuprous oxide is analyzed. The effect of this additive on the process of the expansion of the electric-discharge plasma during the electric explosion of conductors and on the strength of composite materials is demonstrated. The piezoprobe-based method of measurement of the radial pressure during samples destruction is developed. The experiments made it possible to determine the dimensions of the melting channel formed inside the samples during the explosion and the subsequent expansion of the electric-discharge plasma. The experiments are performed on the generator of short-term high-voltage pulses capable to shape the voltage of (10-24) kV.

Reactive Spark Plasma Sintering (SPS) of Nitride Reinforced Titanium Alloy Composites (Postprint)

DTIC Science & Technology

2014-08-15

AFRL-RX-WP-JA-2014-0177 REACTIVE SPARK PLASMA SINTERING (SPS) OF NITRIDE REINFORCED TITANIUM ALLOY COMPOSITES (POSTPRINT) Jaimie S...titanium–vanadium alloys, has been achieved by introducing reactive nitrogen gas during the spark plasma sintering (SPS) of blended titanium and...lcomReactive spark plasma sintering (SPS) of nitride reinforced titanium alloy compositeshttp://dx.doi.org/10.1016/j.jallcom.2014.08.049 0925-8388

The effect of oxygen-plasma treatment on Kevlar fibers and the properties of Kevlar fibers/bismaleimide composites

NASA Astrophysics Data System (ADS)

Su, Min; Gu, Aijuan; Liang, Guozheng; Yuan, Li

2011-02-01

The effect of oxygen-plasma treatment for Kevlar fibers on the interfacial adhesion and typical macro-properties of Kevlar fiber/bismaleimide composites was intensively studied. It is found that oxygen-plasma treatment significantly affects the interfacial adhesion by changing the chemistry and morphology of the surfaces of the fibers, and thus leading to improved interlaminar shear strength, water resistance and dielectric properties of the composites. However, the improvement is closely related to the treatment power and time. The best condition for treating Kevlar fiber is 70 W for 5 min. Oxygen-plasma treatment provides an effective technique for overcoming the poor interfacial adhesion of Kevlar fiber based composites, and thus showing great potential in fabricating high performance copper clad laminates.

Uteroplacental insufficiency reduces rat plasma leptin concentrations and alters placental leptin transporters: ameliorated with enhanced milk intake and nutrition

PubMed Central

Briffa, Jessica F.; O'Dowd, Rachael; Moritz, Karen M.; Romano, Tania; Jedwab, Lisa R.; McAinch, Andrew J.; Hryciw, Deanne H.

2017-01-01

Key points Uteroplacental insufficiency compromises maternal mammary development, milk production and pup organ development; this is ameliorated by cross‐fostering, which improves pup growth and organ development and prevents adult diseases in growth‐restricted (Restricted) offspring by enhancing postnatal nutrition.Leptin is transported to the fetus from the mother by the placenta; we report reduced plasma leptin concentrations in Restricted fetuses associated with sex‐specific alterations in placental leptin transporter expression.Pup plasma leptin concentrations were also reduced during suckling, which may suggest reduced milk leptin transport or leptin reabsorption.Mothers suckled by Restricted pups had impaired mammary development and changes in milk fatty acid composition with no alterations in milk leptin; cross‐fostering restored pup plasma leptin concentrations, which may be correlated to improved milk composition and intake.Increased plasma leptin and altered milk fatty acid composition in Restricted pups suckling mothers with normal lactation may improve postnatal growth and prevent adult diseases. Abstract Uteroplacental insufficiency reduces birth weight and adversely affects fetal organ development, increasing adult disease risk. Cross‐fostering improves postnatal nutrition and restores these deficits. Mothers with growth‐restricted pups have compromised milk production and composition; however, the impact cross‐fostering has on milk production and composition is unknown. Plasma leptin concentrations peak during the completion of organogenesis, which occurs postnatally in rats. Leptin is transferred to the fetus via the placenta and to the pup via the lactating mammary gland. This study investigated the effect of uteroplacental insufficiency on pup plasma leptin concentrations and placental leptin transporters. We additionally examined whether cross‐fostering improves mammary development, milk composition and pup plasma leptin concentrations. Fetal growth restriction was induced by bilateral uterine vessel ligation surgery on gestation day 18 in Wistar Kyoto rats (termed uteroplacental insufficiency surgery mothers). Growth‐restricted (Restricted) fetuses had reduced plasma leptin concentrations, persisting throughout lactation, and sex‐specific alterations in placental leptin transporters. Mothers suckled by Restricted pups had impaired mammary development, altered milk fatty acid composition and increased plasma leptin concentrations, despite no changes in milk leptin. Milk intake was reduced in Restricted pups suckling uteroplacental insufficiency surgery mothers compared to Restricted pups suckling sham‐operated mothers. Cross‐fostering Restricted pups onto a sham‐operated mother improved postnatal growth and restored plasma leptin concentrations compared to Restricted pups suckling uteroplacental insufficiency surgery mothers. Uteroplacental insufficiency alters leptin homeostasis. This is ameliorated with cross‐fostering and enhanced milk fatty acid composition and consumption, which may protect the pups from developing adverse health conditions in adulthood. PMID:28369926

Orange peel + nanostructured zero-valent-iron composite for the removal of hexavalent chromium in water

NASA Astrophysics Data System (ADS)

Olea-Mejía, O.; Cabral-Prieto, A.; Salcedo-Castillo, U.; López-Tellez, G.; Olea-Cardoso, O.; López-Castañares, R.

2017-11-01

In this work we used the Pulsed Plasma in Liquid technique to synthesize zero-valent iron nanostructures. We used a DC Power Source to produce such plasma on water and methanol. The obtained particles were characterized by TEM to determine their shape and size and Mossbauer Spectroscopy to investigate the chemical state of the iron present. We found that 80% of the particles produced in water are composed of metallic iron and when methanol is used 97% of the particles are metallic iron. Once the Fe colloid was formed, orange skin was impregnated with these nanostructures for the removal of in water solution. The Cr(VI) removal experiments were done in a batch system in the presence of the composites at an inicial concentration of 50 ppm of Cr(VI). When using the iron nanostructures supported on the orange peel, the percentage of removal is 100% in the case of nanostructures formed in water and 96% when obtained in methanol.

Conical pitch angle distributions of very low-energy ion fluxes observed by ISEE 1

NASA Technical Reports Server (NTRS)

Horwitz, J. L.; Baugher, C. R.; Chappell, C. R.; Shelley, E. G.; Young, D. T.

1982-01-01

Observations are presented of conical distributions of low-energy ion fluxes from throughout the magnetosphere. The data were provided by the plasma composition experiment (PCE) on ISEE 1. ISEE 1 was launched in October 1977 into a highly elliptical orbit with a 30 deg inclination to the equator and 22.5 earth radii apogee. Particular attention is given to data taken when the instrument was in its thermal plasma mode, sampling ions in the energy per charge range 0-100 eV/e. Attention is given to examples of conical distributions in 0- to 100-eV/e ions, the occurrence of conical distributions of 0- to 100-eV ions in local time-geocentric distance and latitude-geocentric distance coordinates, the cone angles in 0- to 100-eV ion conics, Kp distributions of 0- to 100-eV ion conics, and some compositional aspects of 0- to 100-eV ion conics.

Multicomponent plasma expansion into vacuum with non-Maxwellian electrons

NASA Astrophysics Data System (ADS)

Elkamash, Ibrahem; Kourakis, Ioannis

2016-10-01

The expansion of a collisionless plasma into vacuum has been widely studied since the early works of Gurevich et al and Allen and coworkers. It has received momentum in recent years, in particular in the context of ultraintense laser pulse interaction with a solid target, in an effort to elucidate the generation of high energy ion beams. In most present day experiments, laser produced plasmas contain several ion species, due to increasingly complicated composite targets. Anderson et al have studied the isothermal expansion of a two-ion-species plasma. As in most earlier works, the electrons were assumed to be isothermal throughout the expansion. However, in more realistic situations, the evolution of laser produced plasmas into vacuum is mainly governed by nonthermal electrons. These electrons are characterized by particle distribution functions with high energy tails, which may significantly deviate from the Maxwellian distribution. In this paper, we present a theoretical model for plasma expansion of two component plasma with nonthermal electrons, modelled by a kappa-type distribution. The superthermal effect on the ion density, velocity and the electric field is investigated. It is shown that energetic electrons have a significant effecton the expansion dynamics of the plasma. This work was supported from CPP/QUB funding. One of us (I.S. Elkamash) acknowledges financial support by an Egyptian Government fellowship.

Air plasma spray processing and electrochemical characterization of Cu-SDC coatings for use in solid oxide fuel cell anodes

NASA Astrophysics Data System (ADS)

Benoved, Nir; Kesler, O.

Air plasma spraying has been used to produce porous composite anodes based on Ce 0.8Sm 0.2O 1.9 (SDC) and Cu for use in solid oxide fuel cells (SOFCs). Preliminarily, a range of plasma conditions has been examined for the production of composite coatings from pre-mixed SDC and CuO powders. Plasma gas compositions were varied to obtain a range of plasma temperatures. After reduction in H 2, coatings were characterized for composition and microstructure using EDX and SEM. As a result of these tests, symmetrical sintered electrolyte-supported anode-anode cells were fabricated by air plasma spraying of the anodes, followed by in situ reduction of the CuO to Cu. Full cells deposited on SS430 porous substrates were then produced in one integrated process. Fine CuO and SDC powders have been used to produce homogeneously mixed anode coatings with higher surface area microstructures, resulting in area-specific polarization resistances of 4.8 Ω cm 2 in impedance tests in hydrogen at 712 °C.

Restoration and Archiving of Data from the Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE 1)

NASA Technical Reports Server (NTRS)

Lennartsson, O. W.

1997-01-01

The objective of this project has been to complete the archiving of energetic (10 eV/epsilon - 18 keV/epsilon) ion composition data from the Lockheed Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE 1) satellite, using a particular data format that had previously been approved by NASA and the NSSDC. That same format, a combination of ion velocity moments and differential flux spectra, had been used in 1991 to archive, at the NSSDC, the first 28 months (the "Prime" period of ISEE investigations) of data from the Lockheed instrument under NASA Contract NAS5-33047. With the completion of this project, the almost 4 1/2-year time span of these unique data is now covered by a very compact set, approximately 1 gigabyte in total, of electronic files with physical quantities, all in ASCII. The files are organized by data type and time of data acquisition, in Universal Time, and named according to year and day of year. Each calendar day has five separate files (five types of data), the lengths of which vary from day to day, depending on the instrument mode of operation. The data format and file structure are described in detail in appendices 1 and 2. The physical medium consists of high-density (6250 cpi) 9-track magnetic tapes, complemented by a set of hardcopy line plots of certain plasma parameters. In this case there are five tapes, to be added to the six previous ones from 1991, and 25 booklets of plots, one per month, to be added to the previous 28. The tapes, including an extra standard-density (1600 cpi) tape with electronic versions of the Data User's Guide and self-guiding VAX/VMS command files, and the hardcopy plots are being boxed for shipment to the NSSDC.

Composition of hot ions /0.1-16 keV/e/ as observed by the GEOS and ISEE mass spectrometers and inferences for the origin and circulation of magnetospheric plasmas

NASA Technical Reports Server (NTRS)

Balsiger, H.

1981-01-01

The composition of hot magnetospheric plasma through different regions of the magnetosphere is described on the basis of mass spectrometer measurements by the GEOS 1, GEOS 2, and ISEE-1 spacecraft. Coordinated composition measurements on the different spacecraft also provide information on the spatial and temporal characteristics of the plasma during storms. Data on ion origins are also provided.

Saturn's Magnetospheric Plasma Flow Encountered by Titan

NASA Astrophysics Data System (ADS)

Sillanpää, I.

2017-09-01

Titan has been a major target of the ending Cassini mission to Saturn. 126 flybys have sampled, measured and observed a variety of Titan's features and processes from the surface features to atmospheric composition and upper atmospheric processes. Titan's interaction with the magnetospheric plasma flow it is mostly embedded in is highly dependent on the characteristics of the ambient plasma. The density, velocity and even the composition of the plasma flow can have great variance from flyby to flyby. Our purpose is the present the plasma flow conditions for all over 70 flybys of which we have Cassini Plasma Spectrometer (CAPS) measurements.

Effects of feedstock availability on the negative ion behavior in a C{sub 4}F{sub 8} inductively coupled plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Shu-Xia; Research group PLASMANT, Dept. Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp; Gao, Fei

2015-07-21

In this paper, the negative ion behavior in a C{sub 4}F{sub 8} inductively coupled plasma (ICP) is investigated using a hybrid model. The model predicts a non-monotonic variation of the total negative ion density with power at low pressure (10–30 mTorr), and this trend agrees well with experiments that were carried out in many fluorocarbon (fc) ICP sources, like C{sub 2}F{sub 6}, CHF{sub 3}, and C{sub 4}F{sub 8}. This behavior is explained by the availability of feedstock C{sub 4}F{sub 8} gas as a source of the negative ions, as well as by the presence of low energy electrons due tomore » vibrational excitation at low power. The maximum of the negative ion density shifts to low power values upon decreasing pressure, because of the more pronounced depletion of C{sub 4}F{sub 8} molecules, and at high pressure (∼50 mTorr), the anion density continuously increases with power, which is similar to fc CCP sources. Furthermore, the negative ion composition is identified in this paper. Our work demonstrates that for a clear understanding of the negative ion behavior in radio frequency C{sub 4}F{sub 8} plasma sources, one needs to take into account many factors, like the attachment characteristics, the anion composition, the spatial profiles, and the reactor configuration. Finally, a detailed comparison of our simulation results with experiments is conducted.« less

Skylab

NASA Image and Video Library

1971-04-01

This photograph shows Skylab's Extreme Ultraviolet (XUV) Spectroheliograph during an acceptance test and checkout procedures in April 1971. The unit was an Apollo Telescope Mount (ATM) instrument designed to sequentially photograph the solar chromosphere and corona in selected ultraviolet wavelengths. The instrument also obtained information about composition, temperature, energy conversion and transfer, and plasma processes of the chromosphere and lower corona. The Marshall Space Flight Center had program management responsibility for the development of Skylab hardware and experiments.

Atomic and Molecular Spectroscopic Studies of the DIII-D Neutral Beam Ion Source and Neutralizer

NASA Astrophysics Data System (ADS)

Crowley, B.; Rauch, J.; Scoville, J. T.; Sharma, S. K.; Choksi, B.

2015-11-01

The neutral beam system is interesting in that it comprises two distinct low temperature plasmas. Firstly, the ion source is typically a filament or RF driven plasma from which ions are extracted by a high voltage accelerator grid system. Secondly the neutralizer is essentially a low temperature plasma system with the beam serving as the primary ionization source and the neutralizer walls serving as conducting boundaries. Atomic spectroscopy of Doppler shifted D-alpha light emanating from the fast atoms is studied to determine the composition of the source and the divergence of the beam. Molecular spectroscopy involves measuring fine structure in electron-vibrational rotational bands. The technique has applications in low temperature plasmas and here it is used to determine gas temperature in the neutralizer. We describe the experimental set-up and the physics model used to relate the spectroscopic data to the plasma parameters and we present results of recent experiments exploring how to increase neutralization efficiency. Supported by the US DOE under DE-FC02-04ER54698.

Effects of Ambient Humidity on Plant Growth Enhancement by Atmospheric Air Plasma Irradiation to Plant Seeds

NASA Astrophysics Data System (ADS)

Sarinont, Thapanut; Amano, Takaaki; Koga, Kazunori; Shiratani, Masaharu

2015-09-01

Humidity is an important factor for plasma-bio applications because composition of species generated by atmospheric pressure plasmas significantly depends on the humidity. Here we have examined effects of humidity on the growth enhancement to study the mechanism. Experiments were carried out with a scalable DBD device. 10 seeds of Raphanus sativus L. were set for x = 5 mm and y = 3 mm below the electrodes. The humidity Hair was 10 - 90 %Rh. The ratio of length of plants with plasma irradiation to that of control increases from 1.2 for Hair = 10 %Rh to 2.5 for Hair = 50 %Rh. The ratio is 2.5 for Hair = 50-90 %Rh. This humidity dependence is similar to the humidity dependence of O2+-H2O,H3O*, NO2--H2Oand NO3--H2Odensities, whereas it is different from that of other species such as O3, NO, and so on. The similarity gives information on key species for the growth enhancement.

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

NASA Astrophysics Data System (ADS)

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Neutron-Irradiated Samples as Test Materials for MPEX

DOE PAGES

Ellis, Ronald James; Rapp, Juergen

2015-10-09

Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of themore » samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.« less

Assembling a supercapacitor electrode with dual metal oxides and activated carbon using a liquid phase plasma.

PubMed

Ki, Seo Jin; Jeon, Ki-Joon; Park, Young-Kwon; Park, Hyunwoong; Jeong, Sangmin; Lee, Heon; Jung, Sang-Chul

2017-12-01

Developing supercapacitor electrodes at an affordable cost while improving their energy and/or power density values is still a challenging task. This study introduced a recipe which assembled a novel electrode composite using a liquid phase plasma that was applied to a reactant solution containing an activated carbon (AC) powder with dual metal precursors of iron and manganese. A comparison was made between the composites doped with single and dual metal components as well as among those synthesized under different precursor concentrations and plasma durations. The results showed that increasing the precursor concentration and plasma duration raised the content of both metal oxides in the composites, whereas the deposition conditions were more favorable to iron oxide than manganese oxide, due to its higher standard potential. The composite treated with the longest plasma duration and highest manganese concentration was superior to the others in terms of cyclic stability and equivalent series resistance. In addition, the new composite selected out of them showed better electrochemical performance than the raw AC material only and even two types of single metal-based composites, owing largely to the synergistic effect of the two metal oxides. Therefore, the proposed methodology can be used to modify existing and future composite electrodes to improve their performance with relatively cheap host and guest materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface modification of argon/oxygen plasma treated vulcanized ethylene propylene diene polymethylene surfaces for improved adhesion with natural rubber

NASA Astrophysics Data System (ADS)

Basak, Ganesh C.; Bandyopadhyay, Abhijit; Neogi, Sudarsan; Bhowmick, Anil K.

2011-01-01

Vulcanized ethylene propylene diene polymethylene (EPDM) rubber surface was treated in a radio frequency capacitatively coupled low pressure argon/oxygen plasma to improve adhesion with compounded natural rubber (NR) during co-vulcanization. The plasma modified surfaces were analyzed by means of contact angle measurement, surface energy, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray sulfur mapping and atomic force microscopy. Several experimental variables such as plasma power, length of exposure time and composition of the argon-oxygen gas mixture were considered. It was delineated that plasma treatment changed both surface composition and roughness, and consequently increased peel strength. The change in surface composition was mainly ascribed to the formation of C-O and -Cdbnd O functional groups on the vulcanized surfaces. A maximum of 98% improvement in peel strength was observed after plasma treatment.

Detecting negative ions on board small satellites

NASA Astrophysics Data System (ADS)

Lepri, S. T.; Raines, J. M.; Gilbert, J. A.; Cutler, J.; Panning, M.; Zurbuchen, T. H.

2017-04-01

Recent measurements near comets, planets, and their satellites have shown that heavy ions, energetic neutral atoms, molecular ions, and charged dust contain a wealth of information about the origin, evolution, and interaction of celestial bodies with their space environment. Using highly sensitive plasma instruments, positively charged heavy ions have been used to trace exospheric and surface composition of comets, planets, and satellites as well as the composition of interplanetary and interstellar dust. While positive ions dominate throughout the heliosphere, negative ions are also produced from surface interactions. In fact, laboratory experiments have shown that oxygen released from rocky surfaces is mostly negatively charged. Negative ions and negatively charged nanograins have been detected with plasma electron analyzers in several different environments (e.g., by Cassini and Rosetta), though more extensive studies have been challenging without instrumentation dedicated to negative ions. We discuss an adaptation of the Fast Imaging Plasma Spectrometer (FIPS) flown on MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) for the measurement of negatively charged particles. MESSENGER/FIPS successfully measured the plasma environment of Mercury from 2011 until 2015, when the mission ended, and has been used to map multiple ion species (H+ through Na+ and beyond) throughout Mercury's space environment. Modifications to the existing instrument design fits within a 3U CubeSat volume and would provide a low mass, low power instrument, ideal for future CubeSat or distributed sensor missions seeking, for the first time, to characterize the contribution of negative particles in the heliospheric plasmas near the planets, moons, comets, and other sources.

Removal of NO in NO/N2, NO/N2/O2, NO/CH4/N2, and NO/CH4/O2/N2 systems by flowing microwave discharges.

PubMed

Hueso, José L; Gonzalez-Elipe, Agustín R; Cotrino, José; Caballero, Alfonso

2007-02-15

In this paper, continuing previous work, we report on experiments carried out to investigate the removal of NO from simulated flue gas in nonthermal plasmas. The plasma-induced decomposition of small concentrations of NO in N2 used as the carrier gas and O2 and CH4 as minority components has been studied in a surface wave discharge induced with a surfatron launcher. The reaction products and efficiency have been monitored by mass spectrometry as a function of the composition of the mixture. NO is effectively decomposed into N2 and O2 even in the presence of O2, provided always that enough CH4 is also present in the mixture. Other majority products of the plasma reactions under these conditions are NH3, CO, and H2. In the absence of O2, decomposition of NO also occurs, although in that case HCN accompanies the other reaction products as a majority component. The plasma for the different reaction mixtures has been characterized by optical emission spectroscopy. Intermediate excited species of NO*, C*, CN*, NH*, and CH* have been monitored depending on the gas mixture. The type of species detected and their evolution with the gas composition are in agreement with the reaction products detected in each case. The observations by mass spectrometry and optical emission spectroscopy are in agreement with the kinetic reaction models available in literature for simple plasma reactions in simple reaction mixtures.

Effects of dietary excesses of branched-chain amino acids on the metabolism and tissue composition of lake trout (Salvelinus namaycush)

USGS Publications Warehouse

Hughes, S.G.; Rumsey, G.L.; Nesheim, M.C.

1984-01-01

1. Excesses of either leucine, isoleucine or valine were fed in separate experiments to determine if the branched-chain amino acid antagonism reported in other animals occur in trout (Salvelinus namaycush).2. Parameters measured include growth rate, feed utilization efficiency, plasma and muscle-free amino acids, carcass composition and branched-chain amino acid aminotransferase.3. Dietary excesses of leucine or isoleucine caused an increase in the valine requirement.4. The inability of leucine and isoleucine supplementations to ameliorate the effects of excess dietary valine are interpreted as a valine toxicity rather than an antagonism.

Optical characterization of composite layers prepared by plasma polymerization

NASA Astrophysics Data System (ADS)

Radeva, E.; Hikov, T.; Mitev, D.; Stroescu, H.; Nicolescu, M.; Gartner, M.; Presker, R.; Pramatarova, L.

2016-02-01

Thin composite layers from polymer/nanoparticles (Ag-nanoparticles and detonation nanodiamonds) were prepared by plasma polymerization process on the base of hexamethyldisiloxane. The variation of the layer composition was achieved by changing the type of nanoparticles. The optical measurement techniques used were UV-VIS-NIR ellipsometry (SE), Fourier-transformed infrared spectroscopy (FTIR) and Raman spectroscopy. The values of the refractive index determined are in the range 1.30 to 1.42. All samples are transparent with transmission between 85-95% and very smooth. The change in Raman and FTIR spectra of the composites verify the expected bonding between polymer and diamond nanoparticles due to the penetration of the fillers in the polymer matrix. The comparison of the spectra of the corresponding NH3 plasma treated composites revealed that the composite surface becomes more hydrophilic. The obtained results indicate that preparation of layers with desired compositions is possible at a precise control of the detonation nanodiamond materials.

Surface martensitization of Carbon steel using Arc Plasma Sintering

NASA Astrophysics Data System (ADS)

Wahyudi, Haris; Dimyati, Arbi; Sebayang, Darwin

2018-03-01

In this paper new technology of surface structure modification of steel by short plasma exposure in Arc Plasma Sintering (APS) device is presented. APS is an apparatus working based on plasma generated by DC pulsed current originally used for synthesizing materials via sintering and melting. Plasma exposure in APS was applied into the specimens for 1 and 3 seconds which generate temperature approximately about 1300-1500°C. The SUP9, pearlitic carbon steel samples were used. The hardness, hardening depth and microstructure of the specimens have been investigated by Vickers micro hardness test and Scanning Electron Microscopy (SEM) supported by Energy Dispersive X-Ray Spectroscopy (EDX). The results have showed that the mechanical property was significantly improved due to the formation of single martensitic structures as identified by SEM. The hardness of treated surface evaluated by Vickers hardness test showed significant improvement nearly three time from 190 VHN before to 524 VHN after treatment. Furthermore, EDX confirmed that the formation of martensite layer occurred without altering its composition. The APS also produced uniform hardened layer up to 250 μm. The experiment has demonstrated that arc plasma process was successfully improved the mechanical properties of steel in relatively very short time.

The Food Environment, Preference, and Experience Modulate the Effects of Exendin-4 on Food Intake and Reward.

PubMed

Mella, Ricardo; Schmidt, Camila B; Romagnoli, Pierre-Paul; Teske, Jennifer A; Perez-Leighton, Claudio

2017-11-01

The obesogenic food environment facilitates access to multiple palatable foods. Exendin-4 (EX4) is a glucagon-like peptide 1 receptor (GLP1R) agonist that inhibits food intake and has been proposed as an obesity therapy. This study tested whether the composition of the food environment and experience with palatable foods modulate the effects of EX4 on food intake and reward. Mice fed a cafeteria (CAF) or control diet were tested for the anorectic effects of EX4 when simultaneously offered foods of varying individual preference and in a conditioned place preference (CPP) test for chocolate. Plasma glucagon-like peptide 1 (GLP1) and hypothalamic GLP1R mRNA were analyzed post mortem. Mice fed a CAF diet developed individual food preference patterns. Offering mice either novel or highly preferred foods decreased the potency of EX4 to inhibit food intake compared to low preference foods or chow. Compared to the control diet, CAF diet intake blocked the decrease in chocolate CPP caused by EX4 and decreased the expression of hypothalamic GLP1R mRNA without altering the plasma GLP1 concentration. The composition of the food environment, food preference, and experience modulate the ability of EX4 to inhibit food intake and reward. These data highlight the significance of modeling the complexity of the human food environment in preclinical obesity studies. © 2017 The Obesity Society.

Influence of atmospheric plasma on physicochemical properties of vapor-grown graphite nanofibers.

PubMed

Seo, Min-Kang; Park, Soo-Jin; Lee, Sang-Kwan

2005-05-01

Vapor-grown graphite nanofibers (GNFs) were modified by plasma treatments using low-pressure plasmas with different gases (Ar gas only and/or Ar/O2 gases), flow rates, pressures, and powers. Surface characterizations and morphologies of the GNFs after plasma treatment were investigated by X-ray photoelectron spectroscopy (XPS), contact angle, titration, and transmission electron microscopy (TEM) measurements. Also, the investigation of thermomechanical behavior and impact strengths of the GNFs/epoxy composites was performed by dynamic-mechanical thermal analysis (DMTA) and Izod impact testing, respectively. The plasma treatment of the fibers changed the surface morphologies by forming a layer with a thickness on the order of 1 nm, mainly consisting of oxygen functional groups such as hydroxyl, carbonyl, and carboxyl groups. After functionalization of the complete surfaces, further plasma treatment did not enhance the superficial oxygen content but slightly changed the portions of the functional groups. Also, the composites with plasma-treated GNFs showed an increase in T(g) and impact strength compared to the composites containing the same amount of plasma-untreated GNFs.

Impact of low-temperature plasmas on Deinococcus radiodurans and biomolecules

NASA Technical Reports Server (NTRS)

Mogul, Rakesh; Bol'shakov, Alexander A.; Chan, Suzanne L.; Stevens, Ramsey M.; Khare, Bishun N.; Meyyappan, M.; Trent, Jonathan D.

2003-01-01

The effects of cold plasma on Deinococcus radiodurans, plasmid DNA, and model proteins were assessed using microbiological, spectrometric, and biochemical techniques. In low power O(2) plasma (approximately 25 W, approximately 45 mTorr, 90 min), D. radiodurans, a radiation-resistant bacterium, showed a 99.999% reduction in bioburden. In higher power O(2) plasma (100 W and 500 mTorr), the reduction rate increased about 10-fold and observation by atomic force microscopy showed significant damage to the cell. Damage to cellular lipids, proteins, and chromosome was indicated by losses of infrared spectroscopic peaks at 2930, 1651, 1538, and 1245 cm(-1), respectively. In vitro experiments show that O(2) plasmas induce DNA strand scissions and cross-linking as well as reduction of enzyme activity. The observed degradation and removal of biomolecules was power-dependent. Exposures to 200 W at 500 mTorr removed biomolecules to below detection limits in 60 s. Emission spectroscopy indicated that D. radiodurans cells were volatilized into CO(2), CO, N(2), and H(2)O, confirming that these plasmas were removing complex biological matter from surfaces. A CO(2) plasma was not as effective as the O(2) plasma, indicating the importance of plasma composition and the dominant role of chemical degradation. Together, these findings have implications for NASA planetary protection schemes and for the contamination of Mars.

Metabolomic Quality Assessment of EDTA Plasma and Serum Samples.

PubMed

Malm, Linus; Tybring, Gunnel; Moritz, Thomas; Landin, Britta; Galli, Joakim

2016-10-01

Handling and processing of blood can significantly alter the molecular composition and consistency of biobank samples and can have a major impact on the identification of biomarkers. It is thus crucial to identify tools to determine the quality of samples to be used in biomarker discovery studies. In this study, a non-targeted gas chromatography/time-of-flight mass spectrometry (GC-TOFMS) metabolomic strategy was used with the aim of identifying quality markers for serum and plasma biobank collections lacking proper documentation of preanalytical handling. The effect of postcentrifugation delay was examined in serum stored in tubes with gel separation plugs and ethylenediaminetetraacetic acid (EDTA) plasma in tubes with or without gel separation plugs. The change in metabolic pattern was negligible in all sample types processed within 3 hours after centrifugation regardless of whether the samples were kept at 4°C or 22°C. After 8 and 24 hours postcentrifugation delay before aliquoting, there was a pronounced increase in the number of affected metabolites, as well as in the magnitude of the observed changes. No protective effect on the metabolites was observed in gel-separated EDTA plasma samples. In a separate series of experiments, lactate and glucose levels were determined in plasma to estimate the effect of precentrifugation delay. This separate experiment indicates that the lactate to glucose ratio may serve as a marker to identify samples with delayed time to centrifugation. Although our data from the untargeted GC-TOFMS analysis did not identify any specific markers, we conclude that plasma and serum metabolic profiles remain quite stable when plasma and serum are centrifuged and separated from the blood cells within 3 hours.

Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

2017-12-01

Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

Effects of retinoids on differentiation, lipid metabolism, epidermal growth factor, and low-density lipoprotein binding in squamous carcinoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponec, M.; Weerheim, A.; Havekes, L.

The relationship among keratinocyte differentiation capacity, lipid synthesis, low-density lipoprotein (LDL) metabolism, plasma membrane composition, and epidermal growth factor (EGF) binding has been studied in SCC-12F2 cells. The differentiation capacity of the cells, i.e., ionophore-induced cornified envelope formation, was inhibited by various retinoids and stimulated by hydrocortisone. Retinoids that caused a significant reduction of cornified envelope formation, i.e., retinoic acid and 13-cis-retinoic acid, caused only minor changes in lipid synthesis and plasma membrane composition. Arotinoid ethylsulfone, having a minor effect on cornified envelope formation, caused a drastic inhibition of cholesterol synthesis resulting in changes in the plasma membrane composition. Hydrocortisonemore » stimulated cornified envelope formation but had only minor effects on lipid synthesis and plasma membrane composition. Of all retinoids tested, only arotinoid ethylsulfone caused a drastic increase in EGF binding, while hydrocortisone had no effect. These results clearly demonstrate that the plasma membrane composition is not related to keratinocyte differentiation capacity, but most likely does determine EGF binding. Furthermore, EGF binding does not determine keratinocyte differentiation capacity.« less

SCATHA (Spacecraft Charging AT High Altitudes) Plasma Interaction Experiment: SC-3 High Energy Particle Spectrometer; SC-8 Energetic Ion Composition Experiment.

DTIC Science & Technology

1984-11-30

fluxes have been processed into a computer data base, ready for further analysis. This data base has been the starting point for several of the above...distance from the point of observation. One very common distribution consists of field-aligned ions at energies below several keV, with more energetic...BE DOW POINTS EVERY 16 SM. IN THE SECOND M, ijv.sTIGA . (3) TE FLASMA AND FIE.D COIDITIS THE ELOCTY FILIE IS LOCKED IN OW OF FOUR .fiHAT PRODUCEE TW

Effects of graphene plates' adoption on the microstructure, mechanical properties, and in vivo biocompatibility of calcium silicate coating.

PubMed

Xie, Youtao; Li, Hongqin; Ding, Chuanxian; Zheng, Xuebin; Li, Kai

2015-01-01

Calcium silicate (CS) ceramic is a good coating candidate for biomedical implants to improve biocompatibility and accelerate early osseointegration. However, the poor fracture toughness and wear resistance of this ceramic material restricts the long-term performance of implants. In this study, graphene plates (GPs) were used as reinforcement to improve the mechanical properties of CS coating. Composite coating containing 1.5 weight % GPs was prepared by vacuum plasma spraying technology. The good survival of the GPs in the composite coating was demonstrated by Raman analysis, although the defects of the GPs were increased after plasma spraying. Effects of the GPs' adoption on the microstructure of the coating were studied by scanning electron microscopy and transmission electron microscopy. Results showed that the GPs were homogenously distributed in the CS grains interface or enwrapped on the particles, and exhibited good wetting behavior with the CS matrix. The wear properties of the composite coating were obviously enhanced by the reinforcement of GPs. The reinforcement mechanism was attributed to the enhanced micro-hardness and interfacial bonding of the particles in the coating. In vivo experiments demonstrated that the composite coating possessed similarly good biocompatibility compared to pure CS coating. The bone-implant contact ratio reached 84.3%±7.4% for GPs/CS coating and 79.6%±9.4% for CS coating after 3 months' implantation.

Effects of graphene plates’ adoption on the microstructure, mechanical properties, and in vivo biocompatibility of calcium silicate coating

PubMed Central

Xie, Youtao; Li, Hongqin; Ding, Chuanxian; Zheng, Xuebin; Li, Kai

2015-01-01

Calcium silicate (CS) ceramic is a good coating candidate for biomedical implants to improve biocompatibility and accelerate early osseointegration. However, the poor fracture toughness and wear resistance of this ceramic material restricts the long-term performance of implants. In this study, graphene plates (GPs) were used as reinforcement to improve the mechanical properties of CS coating. Composite coating containing 1.5 weight % GPs was prepared by vacuum plasma spraying technology. The good survival of the GPs in the composite coating was demonstrated by Raman analysis, although the defects of the GPs were increased after plasma spraying. Effects of the GPs’ adoption on the microstructure of the coating were studied by scanning electron microscopy and transmission electron microscopy. Results showed that the GPs were homogenously distributed in the CS grains interface or enwrapped on the particles, and exhibited good wetting behavior with the CS matrix. The wear properties of the composite coating were obviously enhanced by the reinforcement of GPs. The reinforcement mechanism was attributed to the enhanced micro-hardness and interfacial bonding of the particles in the coating. In vivo experiments demonstrated that the composite coating possessed similarly good biocompatibility compared to pure CS coating. The bone-implant contact ratio reached 84.3%±7.4% for GPs/CS coating and 79.6%±9.4% for CS coating after 3 months’ implantation. PMID:26089662

Stratospheric experiments on curing of composite materials

NASA Astrophysics Data System (ADS)

Chudinov, Viacheslav; Kondyurin, Alexey; Svistkov, Alexander L.; Efremov, Denis; Demin, Anton; Terpugov, Viktor; Rusakov, Sergey

2016-07-01

Future space exploration requires a large light-weight structure for habitats, greenhouses, space bases, space factories and other constructions. A new approach enabling large-size constructions in space relies on the use of the technology of polymerization of fiber-filled composites with a curable polymer matrix applied in the free space environment on Erath orbit. In orbit, the material is exposed to high vacuum, dramatic temperature changes, plasma of free space due to cosmic rays, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The development of appropriate polymer matrix composites requires an understanding of the chemical processes of polymer matrix curing under the specific free space conditions to be encountered. The goal of the stratospheric flight experiment is an investigation of the effect of the stratospheric conditions on the uncured polymer matrix of the composite material. The unique combination of low residual pressure, high intensity UV radiation including short-wave UV component, cosmic rays and other aspects associated with solar irradiation strongly influences the chemical processes in polymeric materials. We have done the stratospheric flight experiments with uncured composites (prepreg). A balloon with payload equipped with heater, temperature/pressure/irradiation sensors, microprocessor, carrying the samples of uncured prepreg has been launched to stratosphere of 25-30 km altitude. After the flight, the samples have been tested with FTIR, gel-fraction, tensile test and DMA. The effect of cosmic radiation has been observed. The composite was successfully cured during the stratospheric flight. The study was supported by RFBR grants 12-08-00970 and 14-08-96011.

Layered plasma polymer composite membranes

DOEpatents

Babcock, Walter C.

1994-01-01

Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

Layered plasma polymer composite membranes

DOEpatents

Babcock, W.C.

1994-10-11

Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is [>=]2 and is the number of selective layers. 2 figs.

Morphological and compositional study of 238U thin film targets for nuclear experiments

NASA Astrophysics Data System (ADS)

Sibbens, Goedele; Ernstberger, Markus; Gouder, Thomas; Marouli, Maria; Moens, André; Seibert, Alice; Vanleeuw, David; Zúñiga, Martin Vargas; Wiss, Thierry; Zampella, Mariavittoria; Zuleger, Evelyn

2018-05-01

The uncertainty in neutron cross section values strongly depends on the quality and characteristics of the deposited actinide films which are used as "targets" in the nuclear experiments. Until recently, at the Joint Research Centre in Geel (JRC-Geel), mass and areal densities of actinide layers were determined by measuring activity (using alpha-particle counting), isotopic composition (using thermal ionisation mass spectrometry) and diameter. In this study a series of 238U deposits, prepared by molecular plating and vacuum deposition on different substrates, were characterized with additional non-destructive and destructive analysis techniques. The quality of the deposits was investigated by autoradiography, high-resolution alpha-particle spectrometry, and scanning electron microscopy. The elemental composition was determined by x-ray photoelectron spectroscopy and inductively coupled plasma mass spectrometry. The latter technique was also applied on the U3O8 starting material and the converted UF4 powder. This paper compares the quality and morphology of deposited 238U films prepared by molecular plating and vacuum deposition on various backings, including their elemental composition determined by different characterization techniques. Also discussed are problems in target preparation and characterization.

Laser induced breakdown spectroscopy on meteorites

NASA Astrophysics Data System (ADS)

de Giacomo, A.; Dell'Aglio, M.; de Pascale, O.; Longo, S.; Capitelli, M.

2007-12-01

The classification of meteorites when geological analysis is unfeasible is generally made by the spectral line emission ratio of some characteristic elements. Indeed when a meteorite impacts Earth's atmosphere, hot plasma is generated, as a consequence of the braking effect of air, with the consequent ablation of the falling body. Usually, by the plasma emission spectrum, the meteorite composition is determined, assuming the Boltzmann equilibrium. The plasma generated during Laser Induced Breakdown Spectroscopy (LIBS) experiment shows similar characteristics and allows one to verify the mentioned method with higher accuracy. On the other hand the study of Laser Induced Breakdown Spectroscopy on meteorite can be useful for both improving meteorite classification methods and developing on-flight techniques for asteroid investigation. In this paper certified meteorites belonging to different typologies have been investigated by LIBS: Dofhar 461 (lunar meteorite), Chondrite L6 (stony meteorite), Dofhar 019 (Mars meteorite) and Sikhote Alin (irony meteorite).

Plasma contactor research - 1991

NASA Technical Reports Server (NTRS)

Buchholtz, Brett; Williams, John D.; Wilbur, Paul J.

1992-01-01

A report describing the operating principles of hollow-cathode-based plasma contactors emitting or collecting electrons from an ambient plasma is summarized. Preliminary experiments conducted to determine the noise generated by these plasma contactors in the emission-current return line and in the plasma near it are described. These noise data are measured as current fluctuations in the return line and to the Langmuir probe and then analyzed using a fast Fourier transform technique. The spectral compositions of the data are characterized using power spectral density plots which are examined to identify possible noise source(s) and production mechanism(s). The precautions taken in the construction and calibration of the instrumentation to assure adequate frequency response are described. Experimental results show that line-current noise levels are typically 2 percent of the electron current being emitted or collected. However, noise levels increase to as much as 20 percent of the electron current at a few electron-collection operating conditions. The frequencies associated with most of the noise were harmonics of the 60 Hz input to system power supplies. Plasma noise had characteristics similar in magnitude and frequency to those for the return-line noise, but they contained additional features at frequencies considered to be related to ion-acoustic instabilities. Also discussed is a new probe positioning system built to facilitate future plasma-contractor research.

Multiphase-Multifunctional Ceramic Coatings

DTIC Science & Technology

2013-06-30

were conducted at 1200-1600° C from 10-24 h. Densification of powders in the pyrochlore-fuorite system was also performed by Spark Plasma Sintering ...capability with emphasis on improving toughness and phase stability. The primary goal was clearly accomplished by developing an instrumented air plasma ...composition. Coating compositions were synthesized by atmospheric plasma spray (APS) at CINVESTAV facilities, and dense monolithic counterparts were

Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

PubMed Central

Reis, Rackel; Dumée, Ludovic F.; Tardy, Blaise L.; Dagastine, Raymond; Orbell, John D.; Schutz, Jürg A.; Duke, Mikel C.

2016-01-01

Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties. PMID:27363670

Ion Composition in Saturn's Plasma Environment: Early Results from the Cassini Plasma Spectrometer

NASA Technical Reports Server (NTRS)

Reisenfeld, D. B.; Baragiola, R. A.; Crary, F. J.; Coates, A. J.; Goldstein, R.; Hill, T. W.; Johnson, R. E.; McComas, D. J.; Sittler, E. C.; Shappirio, M. D.

2005-01-01

Prior to Cassini s arrival at Saturn, most of what was known about the composition of the plasma in Saturn s environment was derived from limited measurements by Pioneer 11 and Voyager 1 and 2 in 1979-1981[1-3]. The measurements reported here were made by the Cassini Plasma Spectrometer (CAPS) [4] during the first two Cassini orbits, including the closest approach to Saturn and the rings during the tour, and a close flyby of Titan. The CAPS instrument resolves ion energy/charge from 1 V to 50 kV and ion mass/charge from 1 to approx.100 amu/e, and it measures electron energy from 1 eV to 28 keV. Initial composition measurements of Saturn s magnetosphere show that protons dominate outside approx.8 R(sub s), while inside this radius the plasma is dominated by a mix of water-derived ions and N(+). Over the A and B rings a plasma layer is observed composed of O2(+) and O(+) . The close passage near Titan shows a rich network of both positive and negative molecular ions. We report preliminary analysis of these and other composition findings.

Dietary fat and not calcium supplementation or dairy product consumption is associated with changes in anthropometrics during a randomized, placebo-controlled energy-restriction trial.

PubMed

Smilowitz, Jennifer T; Wiest, Michelle M; Teegarden, Dorothy; Zemel, Michael B; German, J Bruce; Van Loan, Marta D

2011-10-05

Insufficient calcium intake has been proposed to cause unbalanced energy partitioning leading to obesity. However, weight loss interventions including dietary calcium or dairy product consumption have not reported changes in lipid metabolism measured by the plasma lipidome. The objective of this study was to determine the relationships between dairy product or supplemental calcium intake with changes in the plasma lipidome and body composition during energy restriction. A secondary objective of this study was to explore the relationships among calculated macronutrient composition of the energy restricted diet to changes in the plasma lipidome, and body composition during energy restriction. Overweight adults (n = 61) were randomized into one of three intervention groups including a deficit of 500kcal/d: 1) placebo; 2) 900 mg/d calcium supplement; and 3) 3-4 servings of dairy products/d plus a placebo supplement. Plasma fatty acid methyl esters of cholesterol ester, diacylglycerol, free fatty acids, lysophosphatidylcholine, phosphatidylcholine, phosphatidylethanolamine and triacylglycerol were quantified by capillary gas chromatography. After adjustments for energy and protein (g/d) intake, there was no significant effect of treatment on changes in weight, waist circumference or body composition. Plasma lipidome did not differ among dietary treatment groups. Stepwise regression identified correlations between reported intake of monounsaturated fat (% of energy) and changes in % lean mass (r = -0.44, P < 0.01) and % body fat (r = 0.48, P < 0.001). Polyunsaturated fat intake was associated with the % change in waist circumference (r = 0.44, P < 0.01). Dietary saturated fat was not associated with any changes in anthropometrics or the plasma lipidome. Dairy product consumption or calcium supplementation during energy restriction over the course of 12 weeks did not affect plasma lipids. Independent of calcium and dairy product consumption, short-term energy restriction altered body composition. Reported dietary fat composition of energy restricted diets was associated with the degree of change in body composition in these overweight and obese individuals.

Feasibility of Plasma Treated Clay in Clay/Polymer Nanocomposites Powders for use Laser Sintering (LS)

NASA Astrophysics Data System (ADS)

Almansoori, Alaa; Seabright, Ryan; Majewski, C.; Rodenburg, C.

2017-05-01

The addition of small quantities of nano-clay to nylon is known to improve mechanical properties of the resulting nano-composite. However, achieving a uniform dispersion and distribution of the clay within the base polymer can prove difficult. A demonstration of the fabrication and characterization of plasma-treated organoclay/Nylon12 nanocomposite was carried out with the aim of achieving better dispersion of clay platelets on the Nylon12 particle surface. Air-plasma etching was used to enhance the compatibility between clays and polymers to ensure a uniform clay dispersion in composite powders. Downward heat sintering (DHS) in a hot press is used to process neat and composite powders into tensile and XRD specimens. Morphological studies using Low Voltage Scanning Electron Microscopy (LV-SEM) were undertaken to characterize the fracture surfaces and clay dispersion in powders and final composite specimens. Thermogravimetric analysis (TGA) testing performed that the etched clay (EC) is more stable than the nonetched clay (NEC), even at higher temperatures. The influence of the clay ratio and the clay plasma treatment process on the mechanical properties of the nanocomposites was studied by tensile testing. The composite fabricated from (3% EC/N12) powder showed ~19 % improvement in elastic modulus while the composite made from (3% NEC/N12) powder was improved by only 14%). Most notably however is that the variation between tests is strongly reduced when etch clay is used in the composite. We attribute this to a more uniform distribution and better dispersion of the plasma treated clay within polymer powders and ultimately the composite.

Plasma composition in Jupiter's magnetosphere - Initial results from the Solar Wind Ion Composition Spectrometer

NASA Technical Reports Server (NTRS)

Geiss, J.; Gloeckler, G.; Balsiger, H.; Fisk, L. A.; Galvin, A. B.; Gliem, F.; Hamilton, D. C.; Ipavich, F. M.; Livi, S.; Mall, U.

1992-01-01

The ion composition in the Jovian environment was investigated with the Solar Wind Ion Composition Spectrometer on board Ulysses. A hot tenuous plasma was observed throughout the outer and middle magnetosphere. In some regions two thermally different components were identified. Oxygen and sulfur ions with several different charge states, from the volcanic satellite Io, make the largest contribution to the mass density of the hot plasma, even at high latitude. Solar wind particles were observed in all regions investigated. Ions from Jupiter's ionosphere were abundant in the middle magnetosphere, particularly in the high-latitude region on the dusk side, which was traversed for the first time.

Understanding the Kinetics of Protein-Nanoparticle Corona Formation.

PubMed

Vilanova, Oriol; Mittag, Judith J; Kelly, Philip M; Milani, Silvia; Dawson, Kenneth A; Rädler, Joachim O; Franzese, Giancarlo

2016-12-27

When a pristine nanoparticle (NP) encounters a biological fluid, biomolecules spontaneously form adsorption layers around the NP, called "protein corona". The corona composition depends on the time-dependent environmental conditions and determines the NP's fate within living organisms. Understanding how the corona evolves is fundamental in nanotoxicology as well as medical applications. However, the process of corona formation is challenging due to the large number of molecules involved and to the large span of relevant time scales ranging from 100 μs, hard to probe in experiments, to hours, out of reach of all-atoms simulations. Here we combine experiments, simulations, and theory to study (i) the corona kinetics (over 10 -3 -10 3 s) and (ii) its final composition for silica NPs in a model plasma made of three blood proteins (human serum albumin, transferrin, and fibrinogen). When computer simulations are calibrated by experimental protein-NP binding affinities measured in single-protein solutions, the theoretical model correctly reproduces competitive protein replacement as proven by independent experiments. When we change the order of administration of the three proteins, we observe a memory effect in the final corona composition that we can explain within our model. Our combined experimental and computational approach is a step toward the development of systematic prediction and control of protein-NP corona composition based on a hierarchy of equilibrium protein binding constants.

Compact NE213 neutron spectrometer with high energy resolution for fusion applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimbal, A.; Reginatto, M.; Schuhmacher, H.

Neutron spectrometry is a tool for obtaining important information on the fuel ion composition, velocity distribution and temperature of fusion plasmas. A compact NE213 liquid scintillator, fully characterized at Physikalisch-Technische Bundesanstalt, was installed and operated at the Joint European Torus (JET) during two experimental campaigns (C8-2002 and trace tritium experiment-TTE 2003). The results show that this system can operate in a real fusion experiment as a neutron (1.5 MeV

STS-46 plasma composition measurements using the EOIM-3 mass spectrometer

NASA Technical Reports Server (NTRS)

Hunton, Donald E.; Trzcinski, Edmund; Gosselin, Roger; Koontz, Steven; Leger, Lubert; Visentine, James T.

1995-01-01

One of the active instruments incorporated into the Evaluation of Oxygen Interactions with Materials - 3 experiment was a quadrupole mass spectrometer. The primary objectives for this instrument, which was built by the Air Force Phillips Laboratory and was a veteran of the STS-4 flight in 1982, were to quantify the flux of atomic oxygen striking the test surfaces in the EOIM-3 payload and to detect surface reaction products from the materials in the carousel. Other speakers in this session have covered the results of these experiments. Prior to the 40-hour-long dedicated EOIM-3 mission segment at the end of the STS-46 flight, the authors used the mass spectrometer to make measurements of ion and neutral gas composition in the shuttle environment. About 25 hours of data were collected during a variety of mission events, including Eureca deployment at high altitude and many tethered satellite system operations.

Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

PubMed

Khor, K A; Gu, Y W; Pan, D; Cheang, P

2004-08-01

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA, Ti alloy and YSZ components.

Oxygen Plasma Treatment on 3D-Printed Chitosan/Gelatin/Hydroxyapatite Scaffolds for Bone Tissue Engineering.

PubMed

Lee, Chang-Min; Yang, Seong-Won; Jung, Sang-Chul; Kim, Byung-Hoon

2017-04-01

The 3D hydroxyapatite/gelatin/chitosan composite scaffolds were fabricated by 3D printing technique. The scaffolds were treated by oxygen plasma to improve the bioactivity and its surface characterization and in vitro cell culture were investigated. The scaffolds exhibited the good porosity and interconnectivity of pores. After oxygen plasma etching, roughness and wettability on the scaffolds surface are increased. Plasma treated scaffolds showed higher proliferation than that of untreated scaffolds. Oxygen plasma treatment could be used as potential tool to enhance the biocompatibility on the 3D composite scaffolds.

A LIBS method for simultaneous monitoring of the impurities and the hydrogenic composition present in the wall of the TJ-II stellarator

DOE Office of Scientific and Technical Information (OSTI.GOV)

López-Miranda, B., E-mail: belen.lopez@ciemat.es; Zurro, B.; Baciero, A.

The study of plasma-wall interactions and impurity transport in the plasma fusion devices is critical for the development of future fusion reactors. An experiment to perform laser induced breakdown spectroscopy, using minor modifications of our existing laser blow-off impurity injection system, has been set up thus making both experiments compatible. The radiation produced by the laser pulse focused at the TJ-II wall evaporates a surface layer of deposited impurities and the subsequent radiation produced by the laser-produced plasma is collected by two separate lens and fiber combinations into two spectrometers. The first spectrometer, with low spectral resolution, records a spectrummore » from 200 to 900 nm to give a survey of impurities present in the wall. The second one, with high resolution, is tuned to the wavelengths of the Hα and Dα lines in order to resolve them and quantify the hydrogen isotopic ratio present on the surface of the wall. The alignment, calibration, and spectral analysis method will be described in detail. First experimental results obtained with this setup will be shown and its relevance for the TJ-II experimental program discussed.« less

Thermodynamic Properties and Transport Coefficients of Nitrogen, Hydrogen and Helium Plasma Mixed with Silver Vapor

NASA Astrophysics Data System (ADS)

Zhou, Xue; Cui, Xinglei; Chen, Mo; Zhai, Guofu

2016-05-01

Species composites of Ag-N2, Ag-H2 and Ag-He plasmas in the temperature range of 3,000-20,000 K and at 1 atmospheric pressure were calculated by using the minimization of Gibbs free energy. Thermodynamic properties and transport coefficients of nitrogen, hydrogen and helium plasmas mixed with a variety of silver vapor were then calculated based on the equilibrium composites and collision integral data. The calculation procedure was verified by comparing the results obtained in this paper with the published transport coefficients on the case of pure nitrogen plasma. The influences of the silver vapor concentration on composites, thermodynamic properties and transport coefficients were finally analyzed and summarized for all the three types of plasmas. Those physical properties were important for theoretical study and numerical calculation on arc plasma generated by silver-based electrodes in those gases in sealed electromagnetic relays and contacts. supported by National Natural Science Foundation of China (Nos. 51277038 and 51307030)

The effect of liquid target on a nonthermal plasma jet—imaging, electric fields, visualization of gas flow and optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Kovačević, Vesna V.; Sretenović, Goran B.; Slikboer, Elmar; Guaitella, Olivier; Sobota, Ana; Kuraica, Milorad M.

2018-02-01

The article describes the complex study of the interaction of a helium plasma jet with distilled water and saline. The discharge development, spatial distribution of the excited species, electric field measurement results and the results of the Schlieren imaging are presented. The results of the experiments showed that the plasma-liquid interaction could be prolonged with the proper choice of the gas composition between the jet nozzle and the target. This depends on the gas flow and the target distance. Increased conductivity of the liquid does not affect the discharge properties significantly. An increase of the gas flow enables an extension of the plasma duration on the liquid surface up to 10 µs, but with a moderate electric field strength in the ionization wave. In contrast, there is a significant enhancement of the electric field on the liquid surface, up to 30 kV cm-1 for low flows, but with a shorter time of the overall plasma liquid interaction. Ignition of the plasma jet induces a gas flow modification and may cause turbulences in the gas flow. A significant influence of the plasma jet causing a mixing in the liquid is also recorded and it is found that the plasma jet ignition changes the direction of the liquid circulation.

Tribological Properties of Aluminium Alloy Composites Reinforced with Multi-Layer Graphene—The Influence of Spark Plasma Texturing Process

PubMed Central

Kostecki, Marek; Woźniak, Jarosław; Cygan, Tomasz; Petrus, Mateusz; Olszyna, Andrzej

2017-01-01

Self-lubricating composites are designed to obtain materials that reduce energy consumption, improve heat dissipation between moving bodies, and eliminate the need for external lubricants. The use of a solid lubricant in bulk composite material always involves a significant reduction in its mechanical properties, which is usually not an optimal solution. The growing interest in multilayer graphene (MLG), characterised by interesting properties as a component of composites, encouraged the authors to use it as an alternative solid lubricant in aluminium matrix composites instead of graphite. Aluminium alloy 6061 matrix composite reinforced with 2–15 vol % of MLG were synthesised by the spark plasma sintering process (SPS) and its modification, spark plasma texturing (SPT), involving deformation of the pre-sintered body in a larger diameter matrix. It was found that the application of the SPT method improves the density and hardness of the composites, resulting in improved tribological properties, particularly in the higher load regime. PMID:28796172

Effect of subchronic zinc toxicity on rat salivary glands and serum composition.

PubMed

Mizari, Nazer; Hirbod-Mobarakeh, Armin; Shahinpour, Shervin; Ghalichi-Tabriz, Mostafa; Beigy, Maani; Yamini, Ali; Dehpour, Ahmad Reza

2012-11-01

Zinc plays an important role in a wide variety of metabolic processes in animal systems. The role of zinc in preservative treatment, fungicidal action and medicine, and addition of supplementary zinc have increased the probability of zinc toxicity, specially the chronic type. It is known that the composition and quantity of saliva influence the oral health. Regarding people's exposure to zinc in routine life and the importance of saliva, our purpose was to investigate the effects of oral zinc intoxication on secretory function in rat salivary glands and also on serum composition. In this study, there were five groups of female rats. Four groups received zinc acetate dehydrate through their drinking water. After 3 months of experiment, the chemical characteristics and flow rate of saliva and weight of salivary glands were determined. The effects of zinc on hematological and chemical factors of plasma were assessed too. Flow rate of submandibular glands was significantly lower in experimental groups and there were significant changes in Na(+), Ca(2+) and K(+) concentration both in saliva and in plasma. The serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, glucose levels in the plasma and urine creatinine levels were also altered in experimental groups in comparison with the control group. Our results show that zinc toxicity will affect the quantity and quality of saliva probably through changes in the various neurologic pathways to the salivary glands or effects on acinar cells of the salivary glands. Furthermore, our results showed that zinc toxicity will affect the liver and renal function.

Comparative metabolomics in vegans and omnivores reveal constraints on diet-dependent gut microbiota metabolite production

PubMed Central

Wu, Gary D; Compher, Charlene; Chen, Eric Z; Smith, Sarah A; Shah, Rachana D; Bittinger, Kyle; Chehoud, Christel; Albenberg, Lindsey G; Nessel, Lisa; Gilroy, Erin; Star, Julie; Weljie, Aalim M; Flint, Harry J; Metz, David C; Bennett, Michael J; Li, Hongzhe; Bushman, Frederic D; Lewis, James D

2015-01-01

Objective The consumption of an agrarian diet is associated with a reduced risk for many diseases associated with a ‘Westernised’ lifestyle. Studies suggest that diet affects the gut microbiota, which subsequently influences the metabolome, thereby connecting diet, microbiota and health. However, the degree to which diet influences the composition of the gut microbiota is controversial. Murine models and studies comparing the gut microbiota in humans residing in agrarian versus Western societies suggest that the influence is large. To separate global environmental influences from dietary influences, we characterised the gut microbiota and the host metabolome of individuals consuming an agrarian diet in Western society. Design and results Using 16S rRNA-tagged sequencing as well as plasma and urinary metabolomic platforms, we compared measures of dietary intake, gut microbiota composition and the plasma metabolome between healthy human vegans and omnivores, sampled in an urban USA environment. Plasma metabolome of vegans differed markedly from omnivores but the gut microbiota was surprisingly similar. Unlike prior studies of individuals living in agrarian societies, higher consumption of fermentable substrate in vegans was not associated with higher levels of faecal short chain fatty acids, a finding confirmed in a 10-day controlled feeding experiment. Similarly, the proportion of vegans capable of producing equol, a soy-based gut microbiota metabolite, was less than that was reported in Asian societies despite the high consumption of soy-based products. Conclusions Evidently, residence in globally distinct societies helps determine the composition of the gut microbiota that, in turn, influences the production of diet-dependent gut microbial metabolites. PMID:25431456

Rocket-borne thermal plasma instrument "MIPEX" for the ionosphere D, E layer in-situ measurements

NASA Astrophysics Data System (ADS)

Fang, H. K.; Chen, A. B. C.; Lin, C. C. H.; Wu, T. J.; Liu, K. S.; Chuang, C. W.

2017-12-01

In this presentation, the design concepts, performances and status of a thermal plasma particle instrument package "Mesosphere and Ionosphere Plasma Exploration complex (MIPEX)", which is going to be installed onboard a NSPO-funded hybrid rocket, to investigate the electrodynamic processes in ionosphere D, E layers above Taiwan are reported. MIPEX is capable of measuring plasma characteristics including ion temperature, ion composition, ion drift, electron temperature and plasma density at densities as low as 1-10 cm-1. This instrument package consists of an improved retarding potential analyzer with a channel electron multiplier (CEM), a simplified ion drift meter and a planar Langmuir probe. To achieve the working atmospheric pressure of CEM at the height of lower D layer ( 70km), a portable vacuum pump is also placed in the package. A prototype set of the MIPEX has been developed and tested in the Space Plasma Operation Chamber (SPOC) at NCKU, where in ionospheric plasma is generated by back-diffusion plasma sources. A plasma density of 10-106 cm-1, ion temperature of 300-1500 K and electron temperature of 1000-3000K is measured and verified. Limited by the flight platform and the performance of the instruments, the in-situ plasma measurements at the Mesosphere and lower Thermosphere is very challenging and rare. MIPEX is capable of extending the altitude of the effective plasma measurement down to 70 km height and this experiment can provide unique high-quality data of the plasma environment to explore the ion distribution and the electrodynamic processes in the Ionosphere D, E layers at dusk.

Alteration in lipid composition of plasma membranes of sensitive and resistant Guerin carcinoma cells due to the action of free and liposomal form of cisplatin.

PubMed

Naleskina, L A; Todor, I N; Nosko, M M; Lukianova, N Y; Pivnyuk, V M; Chekhun, V F

2013-09-01

To study in vivo changes of lipid composition of plasma membranes of sensitive and resistant to cisplatin Guerin carcinoma cells under influence of free and liposomal cisplatin forms. The isolation of plasma membranes from parental (sensitive) and resistant to cisplatin Guerin carcinoma cells was by differential ultracentrifugation in sucrose density gradient. Lipids were detected by method of thin-layer chromatography. It was determined that more effective action of cisplatin liposomal form on resistant cells is associated with essential abnormalities of conformation of plasma membrane due to change of lipid components and architectonics of rafts. It results in the increase of membrane fluidity. Reconstructions in lipid composition of plasma membranes of cisplatin-resistant Guerin carcinoma cells provide more intensive delivery of drug into the cells, increase of its concentration and more effective interaction with cellular structural elements.

Short communication: Effect of a citrus extract in lactating dairy cows.

PubMed

Ying, Y; Niu, M; Clarke, A R; Harvatine, K J

2017-07-01

Dry matter intake is a main driver of energy balance in lactating dairy cows, and some plant extracts have been commercially fed to dairy cows to stimulate feed intake. Citrus extracts contain several bioactive components and have been shown to modify metabolism in other animal models. Our hypothesis was that a citrus extract would increase dry matter intake. Two experiments were conducted to determine the effect of a citrus extract on intake and milk production in lactating dairy cows. In experiment one, 11 early-lactation dairy cows (experiment 1; 77 ± 15 d in milk, mean ± standard deviation) were used in a switchback design, and in experiment two, 15 mid-lactation Holstein cows (experiment 2; 157 ± 44 d in milk, mean ± standard deviation) were used in a crossover design. In both experiments, treatments were control (no supplement) or a citrus extract (4 g/d in experiment 1 and 4.5 g/d in experiment 2). Treatment periods were 21 and 14 d in experiment 1 and experiment 2, respectively, with the final 7 d used for sample and data collection. No effect was observed for treatment on dry matter intake, feeding behavior, milk yield, milk fat yield, milk protein yield, or milk composition in either experiment. Treatment also had no effect on milk trans fatty acid profile, but the extract increased total 16 carbon fatty acids 0.9 and 0.6 percentage points in experiment 1 and experiment 2, respectively. Plasma nonesterified fatty acids were decreased 6 h after feeding in both experiments (11.1 and 16.0 μEq/L in experiment 1 and experiment 2, respectively). Plasma insulin was increased 1 h before feeding compared with the control in experiment 1 (3.36 vs. 2.13 µIU/mL) and tended to increase 1.79 units 1 h before feeding in experiment 2. The citrus extract had no effect on feed intake or milk production at the dose investigated, but changed plasma insulin and nonesterified fatty acids, indicating some metabolic effects requiring further investigation. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Plasma-Sprayed Ti6Al4V Alloy Composite Coatings Reinforced with In Situ Formed TiB-TiN

NASA Astrophysics Data System (ADS)

Anand, Akrity; Das, Mitun; Kundu, Biswanath; Balla, Vamsi Krishna; Bodhak, Subhadip; Gangadharan, S.

2017-12-01

Plasma spraying was used to deposit premixed Ti6Al4V + 15 wt.% BN powder on titanium substrate to fabricate Ti6Al4V matrix composite coatings reinforced with in situ synthesized TiB-TiN. The formation of in situ TiB-TiN reinforcements increased with plasma power. The in situ reaction appears to be complete under present experimental conditions but with considerable oxidation of Ti in the composite coatings. The hardness of composite coatings was 7 times higher (855HV), and the in vitro wear rate (2.4 × 10-5 mm3/N m) was one order of magnitude less than that of titanium substrate. However, the microstructural non-uniformity decreased the corrosion resistance of these composite coatings in Hank's balanced salt solution.

Effects of feeding omega-3-fatty acids on fatty acid composition and quality of bovine sperm and on antioxidative capacity of bovine seminal plasma.

PubMed

Gürler, Hakan; Calisici, Oguz; Calisici, Duygu; Bollwein, Heinrich

2015-09-01

The aim of the present study was to examine the effects of feeding alpha-linolenic (ALA) acid on fatty acid composition and quality of bovine sperm and on antioxidative capacity of seminal plasma. Nine bulls (ALA bulls) were fed with 800 g rumen-resistant linseed oil with a content of 50% linolenic acid and eight bulls with 400 g palmitic acid (PA bulls). Sperm quality was evaluated for plasma membrane and acrosome intact sperm (PMAI), the amount of membrane lipid peroxidation (LPO), and the percentage of sperm with a high DNA fragmentation index (DFI). Fatty acid content of sperm was determined using gas chromatography. Total antioxidant capacity, glutathione peroxidase, and superoxide dismutase activity were determined in seminal plasma. Feeding ALA increased (P < 0.05) the docosahexaenoic acid (DHA) content in bulls whereas in PA bulls did not change. PMAI increased after cryopreservation in ALA bulls as well as in PA bulls during the experiment period (P < 0.005). LPO of sperm directly after thawing did not change during the study period in ALA group, but decreased in PA group (P < 0.006). After 3h of incubation LPO increased in the ALA group (P < 0.02), while LPO did not differ between phases within groups. In conclusion, feeding of neither saturated nor polyunsaturated fatty acids affect the antioxidant levels in seminal plasma. Both saturated as well as polyunsaturated fatty acids had positive effects on quality of cryopreserved bovine sperm, although the content of docosahexaenoic acid in sperm membranes increased only in ALA bulls. Copyright © 2015 Elsevier B.V. All rights reserved.

Pulsed Plasma Thruster Plume Study: Symmetry and Impact on Spacecraft Surfaces

NASA Technical Reports Server (NTRS)

Arrington, Lynn A.; Marrese, Colleen M.; Blandino, John J.

2000-01-01

Twenty-four witness plates were positioned on perpendicular arrays near a breadboard Pulsed Plasma Thruster (PPT) to collect plume constituents for analysis. Over one million shots were fired during the experiment at 43 J using fluorocarbon polymer propellant. The asymmetry of the film deposition on the witness plates was investigated with mass and thickness measurements and correlated with off-axis thrust vector measurements. The composition of the films was determined. The transmittance and reflectance of the films were measured and the absorption coefficients were calculated in the wavelength range from 350 to 1200 mn. These data were applied to calculate the loss in signal intensity through the films, which will impact the visibility of spaceborne interferometer systems positioned by these thrusters.

Laboratory analogues simulating Titan's atmospheric aerosols: Compared chemical compositions of grains and thin films

NASA Astrophysics Data System (ADS)

Carrasco, Nathalie; Jomard, François; Vigneron, Jackie; Etcheberry, Arnaud; Cernogora, Guy

2016-09-01

Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere. The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. The main parameter probed is the CH4/N2 ratio to explore various possible chemical regimes. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions could be explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes. The higher nitrogen content in the grains possibly involves a higher optical absorption than the one measured on the films, with a possible impact on Titan's radiative models.

Controlled synthesis of germanium nanoparticles by nonthermal plasmas

NASA Astrophysics Data System (ADS)

Ahadi, Amir Mohammad; Hunter, Katharine I.; Kramer, Nicolaas J.; Strunskus, Thomas; Kersten, Holger; Faupel, Franz; Kortshagen, Uwe R.

2016-02-01

The size, composition, and crystallinity of plasma produced nanoparticles are crucial factors for their physical and chemical properties. Here, we investigate the role of the process gas composition, particularly the hydrogen (H2) flow rate, on germanium (Ge) nanoparticles synthesized from a chlorinated precursor by nonthermal plasma. We demonstrate that the gas composition can significantly change the nanoparticle size and also adjust the surface chemistry by altering the dominant reaction mechanisms. A red shift of the Ge-Clx infrared absorptions with increasing H2 flow indicates a weakening of the Ge-Clx bonds at high H2 content. Furthermore, by changing the gas composition, the nanoparticles microstructure can be controlled from mostly amorphous at high hydrogen flow to diamond cubic crystalline at low hydrogen flow.

Oxygen plasma treatment and deposition of CN{sub x} on a fluorinated polymer matrix composite for improved erosion resistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muratore, C.; Korenyi-Both, A.; Bultman, J. E.

2007-07-15

The use of polymer matrix composites in aerospace propulsion applications is currently limited by insufficient resistance to erosion by abrasive media. Erosion resistant coatings may provide necessary protection; however, adhesion to many high temperature polymer matrix composite (PMC) materials is poor. A low pressure oxygen plasma treatment process was developed to improve adhesion of CN{sub x} coatings to a carbon reinforced, fluorinated polymer matrix composite. Fullerene-like CN{sub x} was selected as an erosion resistant coating for its high hardness-to-elastic modulus ratio and elastic resilience which were expected to reduce erosion from media incident at different angles (normal or glancing) relativemore » to the surface. In situ x-ray photoelectron spectroscopy was used to evaluate the effect of the plasma treatment on surface chemistry, and electron microscopy was used to identify changes in the surface morphology of the PMC substrate after plasma exposure. The fluorine concentration at the surface was significantly reduced and the carbon fibers were exposed after plasma treatment. CN{sub x} coatings were then deposited on oxygen treated PMC substrates. Qualitative tests demonstrated that plasma treatment improved coating adhesion resulting in an erosion resistance improvement of a factor of 2 compared to untreated coated composite substrates. The combination of PMC pretreatment and coating with CN{sub x} reduced the erosion rate by an order of magnitude for normally incident particles.« less

Randomized Double-Blind Placebo-Controlled Trial of Powdered Brassica rapa Ethanol Extract on Alteration of Body Composition and Plasma Lipid and Adipocytokine Profiles in Overweight Subjects

PubMed Central

Jeon, Seon-Min; Kim, Ji-Eun; Shin, Su-kyung; Kwon, Eun-young; Jung, Un Ju; Baek, Nam-In; Lee, Kyung-Tae; Jeong, Tae-Sook; Chung, Hae-Gon

2013-01-01

Abstract We evaluated the effects of Brassica rapa ethanol extract (BREE) on body composition and plasma lipid profiles through a randomized, double-blind, and placebo-controlled trial in overweight subjects. Fifty-eight overweight participants (age 20–50 years, body mass index23.0–24.9) were randomly assigned to two groups and served BREE (2 g/day) or placebo (starch, 2 g/day) for 10 weeks. Body compositions, nutrients intake, plasma lipids, adipocytokines, and hepatotoxicity biomarkers were assessed in all subjects at baseline and after 10 weeks of supplementation. The plasma total cholesterol (total-C) concentration was significantly increased after 10 weeks compared to the baseline in both groups. However, BREE supplementation significantly increased the high-density lipoprotein cholesterol (HDL-C) concentration and significantly reduced the total-C/HDL-C ratio, free fatty acid, and adipsin levels after 10 weeks. No significant differences were observed in body compositions, fasting blood glucose, plasma adipocytokines except adipsin, and aspartate aminotransferase and alanine aminotransferase activities between before and after trial within groups as well as between the two groups. The supplementation of BREE partially improves plasma lipid metabolism in overweight subjects without adverse effects. PMID:23342969

Hydrolysis of hemicellulose to produce fermentable monosaccharides by plasma acid.

PubMed

Wang, Ying; Yuan, Bo; Ji, Yingchao; Li, Hong

2013-09-12

In this paper, plasma acid was obtained by treating distilled water with dielectric barrier discharge to hydrolyze hemicellulose. The orthogonal experiment L₂₅(5(6)) was used to optimize such hydrolysis conditions. The total reducing sugar (TRS) was measured by the DNS method. To determine whether the oligosaccharide existed in the hydrolysis products, it was hydrolyzed by sulfuric acid for a second time following the same procedure as reported earlier. The monosaccharide compositions of the hydrolyzed sample were analyzed by high-performance liquid chromatography (HPLC) and Fourier transformed infrared spectroscopy (FTIR). The results showed that pH 2.81 of plasma acid, 100 °C and 50 min were assigned as an optimal hydrolysis condition by plasma acid. Under this condition, the hemicellulose was hydrolyzed completely to produce monosaccharides including xylose, glucose, and galactose with the mole ratio being 17:3:1. The yields of xylose, glucose, and galactose were 38.67%, 9.28% and 3.09%, respectively. Compared with the hemicellulose hydrolysis results by sulfuric acid, it is concluded that plasma acid is an environmental-friendly and efficient method to explore and hydrolyze the hemicellulose existed in biomass. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study of Mechanisms of Filamentary Pulse Electric Discharge Interaction with Gaseous Flow of Nonuniform Composition

DTIC Science & Technology

2013-06-01

dynamic and localization in subsonic and supersonic airflow also at presence of second gas jet and spray jet of liquid hydrocarbons. The experiments...the specific localization of pulse filamentary discharge in vicinity of boundary between two gases and between liquid spray and gas . The...17, 1, 2010 3. M. A. Deminsky, I. V. Kochetov, S. B. Leonov, А. P. Napartovich, “Modeling of plasma assisted combustion in premixed supersonic gas

The M16 mouse: an outbred animal model of early onset polygenic obesity and diabesity.

PubMed

Allan, Mark F; Eisen, Eugene J; Pomp, Daniel

2004-09-01

To characterize the phenotypic consequences of long-term selective breeding for rapid weight gain, with an emphasis on obesity and obesity-induced diabetes (diabesity). M16 is the result of long-term selection for 3- to 6-week weight gain from an ICR base population. Experiment 1 characterized males from both lines for body weights (3, 6, and 8 weeks), feed (4 to 8 weeks) and H(2)O (6 to 8 weeks) consumption, and heat loss, body composition, and levels of several plasma proteins at 8 weeks of age. Experiment 2 characterized differences between lines for both sexes at three ages (6, 8, and 16 weeks) and fed two diets (high and normal fat). Body weight, composition, blood glucose, and plasma insulin and leptin levels were evaluated after an 8-hour fast. At all ages measured, M16 mice were heavier, fatter, hyperphagic, hyperinsulinemic, and hyperleptinemic relative to ICR. M16 males and females were hyperglycemic relative to ICR, with 56% and 22% higher fasted blood glucose levels at 8 weeks of age. M16 mice represent an outbred animal model to facilitate gene discovery and pathway regulation controlling early onset polygenic obesity and type 2 diabetic phenotypes. Phenotypes prevalent in the M16 model, with obesity and diabesity exhibited at a young age, closely mirror current trends in human populations.

In–Depth Characterization of Viral Isolates from Plasma and Cells Compared with Plasma Circulating Quasispecies in Early HIV-1 Infection

PubMed Central

Erkizia, Itziar; Pino, Maria; Pou, Christian; Paredes, Roger; Clotet, Bonaventura; Martinez-Picado, Javier; Prado, Julia G.

2012-01-01

Background The use of in vitro models to unravel the phenotypic characteristics of circulating viral variants is key to understanding HIV-1 pathogenesis but limited by the availability of primary viral isolates from biological samples. However, overall in vivo genetic variability of HIV-1 within a subject may not be reflected in the viable viral population obtained after isolation. Although several studies have tried to determine whether viral populations expanded in vitro are representative of in vivo findings, the answer remains unclear due to the reduced number of clonal sequences analyzed or samples compared. In order to overcome previous experimental limitations, here we applied Deep Pyrosequencing (DPS) technology in combination with phenotypic experiments to analyze and compare with unprecedented detail the composition of viral isolates and in vivo quasispecies. Methodology/Principal Findings We amplified by DPS HIV-1 genomic regions covering gag, protease, integrase and env-V3 to characterize paired isolates from plasma and peripheral blood mononuclear cells and compare them with total plasma viral RNA in four recently HIV-1 infected subjects. Our study demonstrated the presence of unique haplotypes scattered between sample types with conservation of major variants. In addition, no differences in intra- and inter-population encoded protein variability were found between the different types of isolates or when these were compared to plasma viral RNA within subjects. Additionally, in vitro experiments demonstrated phenotypic similarities in terms of replicative capacity and co-receptor usage between viral isolates and plasma viral RNA. Conclusion This study is the first in-depth comparison and characterization of viral isolates from different sources and plasma circulating quasispecies using DPS in recently HIV-1 infected subjects. Our data supports the use of primary isolates regardless of their plasma or cellular origin to define genetic variability and biological traits of circulating HIV-1 quasispecies. PMID:22393441

Definition of acceptance criteria for the ITER divertor plasma-facing components through systematic experimental analysis

NASA Astrophysics Data System (ADS)

Escourbiac, F.; Richou, M.; Guigon, R.; Constans, S.; Durocher, A.; Merola, M.; Schlosser, J.; Riccardi, B.; Grosman, A.

2009-12-01

Experience has shown that a critical part of the high-heat flux (HHF) plasma-facing component (PFC) is the armour to heat sink bond. An experimental study was performed in order to define acceptance criteria with regards to thermal hydraulics and fatigue performance of the International Thermonuclear Experimental Reactor (ITER) divertor PFCs. This study, which includes the manufacturing of samples with calibrated artificial defects relevant to the divertor design, is reported in this paper. In particular, it was concluded that defects detectable with non-destructive examination (NDE) techniques appeared to be acceptable during HHF experiments relevant to heat fluxes expected in the ITER divertor. On the basis of these results, a set of acceptance criteria was proposed and applied to the European vertical target medium-size qualification prototype: 98% of the inspected carbon fibre composite (CFC) monoblocks and 100% of tungsten (W) monoblock and flat tiles elements (i.e. 80% of the full units) were declared acceptable.

Volume Measurements of Laser-generated Pits for In Situ Geochronology using KArLE (Potassium-Argon Laser Experiment)

NASA Technical Reports Server (NTRS)

French, R. A.; Cohen, B. A.; Miller, J. S.

2014-01-01

The Potassium-Argon Laser Experiment( KArLE), is composed of two main instruments: a spectrometer as part of the Laser-Induced Breakdown Spectroscopy (LIBS) method and a Mass Spectrometer (MS). The LIBS laser ablates a sample and creates a plasma cloud, generating a pit in the sample. The LIBS plasma is measured for K abundance in weight percent and the released gas is measured using the MS, which calculates Ar abundance in mols. To relate the K and Ar measurements, total mass of the ablated sample is needed but can be difficult to directly measure. Instead, density and volume are used to calculate mass, where density is calculated based on the elemental composition of the rock (from the emission spectrum) and volume is determined by pit morphology. This study aims to reduce the uncertainty for KArLE by analyzing pit volume relationships in several analog materials and comparing methods of pit volume measurements and their associated uncertainties.

Contributions to process monitoring by laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Rusak, David Alexander

1998-12-01

When a pulsed laser of sufficient energy and pulse duration is brought to a focus, multi-photon ionization creates free electrons in the focal volume. These electrons are accelerated in a process known as inverse Bremsstrahlung and cause collisional ionization of species in the focal volume. More charge carriers are produced and the process continues for the duration of the laser pulse. The manifestation of this process is a visible spark or plasma which typically lasts for tens of microseconds. This laser-induced plasma can serve as a source in an atomic emission experiment. Because the composition of the plasma is determined in large part by the environment in which it forms, elements in the laser target can be determined spectroscopically. The goal of a laser-induced breakdown spectroscopy (LIBS) experiment is to establish a relationship between the concentration of an element of interest in the target and the intensity of light emitted from the laser-induced plasma at a wavelength characteristic of that element. Because LIBS requires only optical access to the sample and can perform elemental determinations in solids, liquids, or gases with little sample preparation, there is interest in using it as an on-line technique for process monitoring in a number of industrial applications. However, before the technique becomes useful in industrial applications, many issues regarding instrumentation and data analysis need to be addressed in the lab. The first two chapters of this dissertation provide, respectively, the basics of the atomic emission experiment and a background of laser-induced breakdown spectroscopy. The next two chapters examine the effect of target water content on the laser-induced plasma and the use of LIBS for analysis of aqueous samples. Chapter 5 describes construction of a fiber optic LIBS probe and its use to study temporal electron number density evolution in plasmas formed on different metals. Chapter 6 is a study of excitation, vibrational, and rotational temperatures in plasmas formed by ultraviolet and infrared laser beams. The last chapter is a brief assessment of classification software for analysis of LIBS data and a discussion of future work.

Studies on the preparation and plasma spherodization of yttrium aluminosilicate glass microspheres for their potential application in liver brachytherapy

NASA Astrophysics Data System (ADS)

Sreekumar, K. P.; Saxena, S. K.; Kumar, Yogendra; Thiyagarajan, T. K.; Dash, Ashutosh; Ananthapadmanabhan, P. V.; Venkatesh, Meera

2010-02-01

Plasma spheroidization exploits the high temperature and high enthalpy available in the thermal plasma jet to melt irregularly shaped powder particles and quench them to get dense spherical particles. Plasma spheroidization is a versatile process and can be applied to metals, ceramics, alloys and composites to obtain fine spherical powders. Radioactive microspheres incorporated with high energetic beta emitting radioisotopes have been reported to be useful in the palliative treatment of liver cancer. These powders are to be prepared in closer range of near spherical morphology in the size range 20-35 microns. Inactive glass samples were prepared by heating the pre-calculated amount of glass forming ingredients in a recrystallized alumina crucible. The glass was formed by keeping the glass forming ingredients at 1700°C for a period of three hours to form a homogeneous melt. After cooling, the glass was recovered from the crucible by crushing and was subsequently powdered mechanically with the help of mortar and pestle. This powder was used as the feed stock for plasma spheroidization using an indigenously developed 40 kW plasma spray system. Experiments were carried out at various operating parameters. The operating parameters were optimised to get spheroidised particles. The powder was sieved to get the required size range before irradiation.

Optimization and Validation of a Sensitive Method for HPLC-PDA Simultaneous Determination of Torasemide and Spironolactone in Human Plasma using Central Composite Design.

PubMed

Subramanian, Venkatesan; Nagappan, Kannappan; Sandeep Mannemala, Sai

2015-01-01

A sensitive, accurate, precise and rapid HPLC-PDA method was developed and validated for the simultaneous determination of torasemide and spironolactone in human plasma using Design of experiments. Central composite design was used to optimize the method using content of acetonitrile, concentration of buffer and pH of mobile phase as independent variables, while the retention factor of spironolactone, resolution between torasemide and phenobarbitone; and retention time of phenobarbitone were chosen as dependent variables. The chromatographic separation was achieved on Phenomenex C(18) column and the mobile phase comprising 20 mM potassium dihydrogen ortho phosphate buffer (pH-3.2) and acetonitrile in 82.5:17.5 v/v pumped at a flow rate of 1.0 mL min(-1). The method was validated according to USFDA guidelines in terms of selectivity, linearity, accuracy, precision, recovery and stability. The limit of quantitation values were 80 and 50 ng mL(-1) for torasemide and spironolactone respectively. Furthermore, the sensitivity and simplicity of the method suggests the validity of method for routine clinical studies.

Liquid chromatography/mass spectrometry-based plasma metabolic profiling study of escitalopram in subjects with major depressive disorder.

PubMed

Bandu, Raju; Lee, Hyun Jeong; Lee, Hyeong Min; Ha, Tae Hyon; Lee, Heon-Jeong; Kim, Se Joo; Ha, Kyooseob; Kim, Kwang Pyo

2018-05-01

Liquid chromatography-mass spectrometry (LC-MS) method revealed the plasma metabolite profiles in major depressive disorder patients treated with escitalopram (ECTP) (n = 7). Depression severity was assessed according to the 17-item Hamilton Depression Rating Scale. Metabolic profiles were derived from major depressive disorder subject blood samples collected after ECTP treatment. Blood plasma was separated and processed in order to effectively extract metabolites, which were then analyzed using LC-MS. We identified 19 metabolites and elucidated their structures using LC-tandem MS (LC-MS/MS) combined with elemental compositions derived from accurate mass measurements. We further used online H/D exchange experiments to verify the structural elucidations of each metabolite. Identifying molecular metabolites may provide critical insights into the pharmacological and clinical effects of ECTP treatment and may also provide useful information informing the development of new antidepressant treatments. These detailed plasma metabolite analyses may also be used to identify optimal dose concentrations in psychopharmacotherapeutic treatment through drug monitoring, as well as forming the basis for response predictions in depressed subjects. Copyright © 2018 John Wiley & Sons, Ltd.

The determination of micro-arc plasma composition and properties of nanoparticles formed during cathodic plasma electrolysis of 304 stainless steel

NASA Astrophysics Data System (ADS)

Jovović, Jovica; Stojadinović, Stevan; Vasilić, Rastko; Tadić, Nenad; Šišović, Nikola M.

2017-05-01

This paper presents the research focused on the determination of micro-arc plasma composition during cathodic plasma electrolysis of AISI304 stainless steel in water solution of sodium hydroxide. The complex line shape of several Fe I spectral lines was observed and, by means of a dedicated fitting procedure based on the spectral line broadening theory and H2O thermal decomposition data, the mole fraction of micro-arc plasma constituents (H2, Fe, O, H, H2O, and OH) was determined. Subsequent characterization of the cathodic plasma electrolysis product formed during the process revealed that it consists of Fe-nanoparticles with median diameter of approximately 60 nm.

Optimization of air plasma reconversion of UF6 to UO2 based on thermodynamic calculations

NASA Astrophysics Data System (ADS)

Tundeshev, Nikolay; Karengin, Alexander; Shamanin, Igor

2018-03-01

The possibility of plasma-chemical conversion of depleted uranium-235 hexafluoride (DUHF) in air plasma in the form of gas-air mixtures with hydrogen is considered in the paper. Calculation of burning parameters of gas-air mixtures is carried out and the compositions of mixtures obtained via energy-efficient conversion of DUHF in air plasma are determined. With the help of plasma-chemical conversion, thermodynamic modeling optimal composition of UF6-H2-Air mixtures and its burning parameters, the modes for production of uranium dioxide in the condensed phase are determined. The results of the conducted researches can be used for creation of technology for plasma-chemical conversion of DUHF in the form of air-gas mixtures with hydrogen.

Arginine supplementation modulates pig plasma lipids, but not hepatic fatty acids, depending on dietary protein level with or without leucine.

PubMed

Madeira, Marta Sofia Morgado Dos Santos; Rolo, Eva Sofia Alves; Pires, Virgínia Maria Rico; Alfaia, Cristina Maria Riscado Pereira Mateus; Coelho, Diogo Francisco Maurício; Lopes, Paula Alexandra Antunes Brás; Martins, Susana Isabel Vargas; Pinto, Rui Manuel Amaro; Prates, José António Mestre

2017-05-30

In the present study, the effect of arginine and leucine supplementation, and dietary protein level, were investigated in commercial crossbred pigs to clarify their individual or combined impact on plasma metabolites, hepatic fatty acid composition and mRNA levels of lipid sensitive factors. The experiment was conducted on fifty-four entire male pigs (Duroc × Pietrain × Large White × Landrace crossbred) from 59 to 92 kg of live weight. Each pig was randomly assigned to one of six experimental treatments (n = 9). The treatments followed a 2 × 3 factorial arrangement, providing two levels of arginine supplementation (0 vs. 1%) and three levels of basal diet (normal protein diet, NPD; reduced protein diet, RPD; reduced protein diet with 2% of leucine, RPDL). Significant interactions between arginine supplementation and protein level were observed across plasma lipids. While dietary arginine increased total lipids, total cholesterol, HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol and triacylglycerols in NPD, the inverse effect was observed in RPD. Overall, dietary treatments had a minor impact on hepatic fatty acid composition. RPD increased 18:1c9 fatty acid while the combination of leucine and RPD reduced 18:0 fatty acid. Arginine supplementation increased the gene expression of FABP1, which contributes for triacylglycerols synthesis without affecting hepatic fatty acids content. RPD, with or without leucine addition, upregulated the lipogenic gene CEBPA but downregulated the fat oxidation gene LPIN1. Arginine supplementation was responsible for a modulated effect on plasma lipids, which is dependent on dietary protein level. It consistently increased lipaemia in NPD, while reducing the correspondent metabolites in RPD. In contrast, arginine had no major impact, neither on hepatic fatty acids content nor on fatty acid composition. Likewise, leucine supplementation of RPD, regardless the presence of arginine, promoted no changes on total fatty acids in the liver. Ultimately, arginine, leucine and dietary protein reduction seem to be unrelated with fatty liver development.

Dietary fat and the diabetic state alter insulin binding and the fatty acyl composition of the adipocyte plasma membrane.

PubMed Central

Field, C J; Ryan, E A; Thomson, A B; Clandinin, M T

1988-01-01

Control and diabetic rats were fed on semi-purified high-fat diets providing a polyunsaturated/saturated fatty acid ratio (P/S) of 1.0 or 0.25, to examine the effect of diet on the fatty acid composition of major phospholipids of the adipocyte plasma membrane. Feeding the high-P/S diet (P/S = 1.0) compared with the low-P/S diet (P/S = 0.25) increased the content of polyunsaturated fatty acids in membrane phospholipids in both control and diabetic animals. The diabetic state decreased the content of polyunsaturated fatty acids, particularly arachidonic acid, in adipocyte membrane phospholipids. The decrease in arachidonic acid in membrane phospholipids of diabetic animals tended to be normalized to within the control values when high-P/S diets were given. For control animals, altered plasma-membrane composition was associated with change in insulin binding, suggesting that change in plasma-membrane composition may have physiological consequences for insulin-stimulated functions in the adipocyte. PMID:3052424

Wave Effects Related to Altitude Variations in the Ion Composition of the Ionosphere

NASA Astrophysics Data System (ADS)

Vavilov, D. I.; Shklyar, D. R.

2016-12-01

Properties of the waves, which can propagate in a magnetized plasma in the frequency range below the proton gyrofrequency, depend strongly on the ion composition of the plasma. Addition of a new sort of ions leads to the appearance of a new resonance frequency, at which the refractive index becomes infinite, and a new cutoff frequency, at which the refractive index becomes zero. In this case, the topology of frequency dependence of the squared refractive index changes. Specifically, a new oscillation branch appears, which is located above the cutoff frequency. A question arises whether these oscillations are excited if radiation with the corresponding frequency, which propagates in a different mode, is present in the plasma. A linear transformation of the waves is another important effect, which is related to variations in the ion plasma composition. These two issues, which are directly related to the theory of formation of proton whistlers in the ionosphere, where the ion composition varies with altitude, are considered in this work.

Dietary fat and not calcium supplementation or dairy product consumption is associated with changes in anthropometrics during a randomized, placebo-controlled energy-restriction trial

PubMed Central

2011-01-01

Insufficient calcium intake has been proposed to cause unbalanced energy partitioning leading to obesity. However, weight loss interventions including dietary calcium or dairy product consumption have not reported changes in lipid metabolism measured by the plasma lipidome. Methods The objective of this study was to determine the relationships between dairy product or supplemental calcium intake with changes in the plasma lipidome and body composition during energy restriction. A secondary objective of this study was to explore the relationships among calculated macronutrient composition of the energy restricted diet to changes in the plasma lipidome, and body composition during energy restriction. Overweight adults (n = 61) were randomized into one of three intervention groups including a deficit of 500kcal/d: 1) placebo; 2) 900 mg/d calcium supplement; and 3) 3-4 servings of dairy products/d plus a placebo supplement. Plasma fatty acid methyl esters of cholesterol ester, diacylglycerol, free fatty acids, lysophosphatidylcholine, phosphatidylcholine, phosphatidylethanolamine and triacylglycerol were quantified by capillary gas chromatography. Results After adjustments for energy and protein (g/d) intake, there was no significant effect of treatment on changes in weight, waist circumference or body composition. Plasma lipidome did not differ among dietary treatment groups. Stepwise regression identified correlations between reported intake of monounsaturated fat (% of energy) and changes in % lean mass (r = -0.44, P < 0.01) and % body fat (r = 0.48, P < 0.001). Polyunsaturated fat intake was associated with the % change in waist circumference (r = 0.44, P < 0.01). Dietary saturated fat was not associated with any changes in anthropometrics or the plasma lipidome. Conclusions Dairy product consumption or calcium supplementation during energy restriction over the course of 12 weeks did not affect plasma lipids. Independent of calcium and dairy product consumption, short-term energy restriction altered body composition. Reported dietary fat composition of energy restricted diets was associated with the degree of change in body composition in these overweight and obese individuals. PMID:21970320

Permeability of boric acid across lipid bilayers and factors affecting it.

PubMed

Dordas, C; Brown, P H

2000-05-15

Boron enters plant roots as undissociated boric acid (H(3)BO(3)). Significant differences in B uptake are frequently observed even when plants are grown under identical conditions. It has been theorized that these differences reflect species differences in permeability coefficient of H(3)BO(3) across plasma membrane. The permeability coefficient of boric acid however, has not been experimentally determined across any artificial or plant membrane. In the experiments described here the permeability coefficient of boric acid in liposomes made of phosphatidylcholine was 4.9x10(-6) cm sec(-1), which is in good agreement with the theoretical value. The permeability coefficient varied from 7x10(-6) to 9.5x10(-9) cm sec(-1) with changes in sterols (cholesterol), the type of phospholipid head group, the length of the fatty acyl chain, and the pH of the medium. In this study we also used Arabidopsis thaliana mutants which differ in lipid composition to study the effect of lipid composition on B uptake. The chs1-1 mutant which has lower proportion of sterols shows 30% higher B uptake compared with the wild type, while the act1-1 mutant which has an increased percentage of longer fatty acids, exhibited 35% lower uptake than the wild type. Lipid composition changes in each of the remaining mutants influenced B uptake to various extents. These data suggest that lipid composition of the plasma membrane can affect total B uptake.

Ion energization in Ganymede's magnetosphere: Using multifluid simulations to interpret ion energy spectrograms

NASA Astrophysics Data System (ADS)

Paty, C.; Paterson, W.; Winglee, R.

2008-06-01

We investigate the ion population and energy distribution within Ganymede's magnetosphere by examining Ganymede's ionospheric outflow as a source of heavy (O+) and light (H+) ions and the Jovian magnetospheric plasma as an external source of heavy ions. We develop a method for examining the energy distributions of each ion species in a three-dimensional multifluid simulation in a way directly comparable to the observations of the Plasma Experiment on the Galileo spacecraft. This is used to provide new insight to the existing controversy over the composition of Ganymede's observed ionospheric outflow, and enables further examination of the energetic signatures of the ion population trapped within Ganymede's magnetosphere. The model-predicted ionospheric outflow is consistent with the in situ ion energy spectrograms observed by the Galileo Plasma Experiment at closest approach, and requires that both ionospheric H+ and O+ are present in the population of ions exiting Ganymede's ionosphere over the polar cap. The outward flux of ionospheric ions was calculated to be ~1026 ions/cm2/s, which is in agreement with independently calculated sputtering rates of Ganymede's icy surface. The modeled spectrograms define characteristic energy signatures and populations for various regions of Ganymede's magnetosphere, which illustrate the major sources of ions trapped within the magnetosphere are Ganymede's ionospheric O+ and H+. The fact that very little plasma was observed inside Ganymede's magnetosphere during the G8 flyby is attributed to the region being shadowed from the sun for ~60 h, which may indicate the importance of photoionization for sustaining Ganymede's ionospheric plasma source.

Inactivation of myeloma cancer cells by helium and argon plasma jets: The effect comparison and the key reactive species

NASA Astrophysics Data System (ADS)

Chen, Zeyu; Cui, Qingjie; Chen, Chen; Xu, Dehui; Liu, Dingxin; Chen, H. L.; Kong, Michael G.

2018-02-01

In plasma cancer therapy, the inactivation of cancer cells under plasma treatment is closely related to the reactive oxygen and nitrogen species (RONS) induced by plasmas. Quantitative study on the plasma-induced RONS that related to cancer cells apoptosis is critical for advancing the research of plasma cancer therapy. In this paper, the effects of several reactive species on the inactivation of LP-1 myeloma cancer cells are comparatively studied with variable working gas composition, surrounding gas composition, and discharge power. The results show that helium plasma jet has a higher cell inactivation efficiency than argon plasma jet under the same discharge power. By comparing the concentration of aqueous phase reactive species and the cell inactivation efficiency under different working gases and discharge powers, it is demonstrated that the inactivation efficiency of LP-1 myeloma cancer cells is strongly correlated with the concentration of peroxynitrite (ONOOH/ONOO-).

Biomolecular Effects of Cold Plasma Exposure

NASA Technical Reports Server (NTRS)

Mogul, Rakesh; Bolshakov, Alexander A.; Chan, Suzanne L.; Stevens, Ramsey D.; Khare, Bishun N.; Meyyappan, M.; Trent, Jonathan D.; DeVincenzi, D. (Technical Monitor)

2002-01-01

The effects of cold plasma exposure on Deinococcus radiodurans, plasmid DNA and model proteins were assessed using microbiological, spectrometric and biochemical techniques. Exposure of D. radiodurans, an extremely radiation resistant microbe, to O2 plasma (less than or equal to 25 W, approx. 45 mTorr, 90 min) yielded a approx. 99.999 % sterilization and the sterilization rate was increased approx. 10-fold at 100 W and 500 mTorr. AFM images shows that the exposed cells are significantly deformed and possess 50-70 nm concavities. IR analysis indicates the chemical degradation of lipids, proteins and carotenoids of the cell wall and membrane. Intracellular damage was indicated by major absorbance loss at 1245, 1651 and 1538/cm corresponding to degradation of DNA and proteins, respectively. Biochemical experiments demonstrate that plasmas induce strand scissions and crosslinking of plasmid DNA, and reduction of enzyme activity; the degradation is power dependent with total sample loss occurring in 60 s at 200 W and 500 mTorr. Emission spectroscopy shows that D. radiodurans is volatilized into CO2, CO, N2 and H2O confirming the removal of biological matter from contaminated surfaces. The O2 plasma impacts several cellular components predominantly through chemical degradation by atomic oxygen. A CO2, plasma, however, was not effective at degrading D. radiodurans, revealing the importance of plasma composition, which has implications for planetary protection and the contamination of Mars.

The value of swarm data for practical modeling of plasma devices

NASA Astrophysics Data System (ADS)

Napartovich, A. P.; Kochetov, I. V.

2011-04-01

The non-thermal plasma is a key component in gas lasers, waste gas cleaners, ozone generators, plasma igniters, flame holders, flow control in high-speed aerodynamics and other applications. The specific feature of the non-thermal plasma is its high sensitivity to variations in governing parameters (gas composition, pressure, pulse duration, E/N parameter). The reactivity of the plasma is due to the appearance of atoms and chemical radicals. For the efficient production of chemically active species high average electron energy is required, which is controlled by the balance of gain from the electric field and loss in inelastic collisions. In low-ionized plasma the electron energy distribution function is far from Maxwellian and must be found numerically for specified conditions. Numerical modeling of processes in plasma technologies requires vast databases on electron scattering cross sections to be available. The only reliable criterion for evaluations of validity of a set of cross sections for a particular species is a correct prediction of electron transport and kinetic coefficients measured in swarm experiments. This criterion is used traditionally to improve experimentally measured cross sections, as was suggested earlier by Phelps. The set of cross sections subjected to this procedure is called a self-consistent set. Nowadays, such reliable self-consistent sets are known for many species. Problems encountered in implementation of the fitting procedure and examples of its successful applications are described in the paper. .

Impact of the storm-time plasma sheet ion composition on the ring current energy density

NASA Astrophysics Data System (ADS)

Mouikis, C.; Kistler, L. M.; Petrinec, S. M.; Fuselier, S. A.; Cohen, I.

2017-12-01

The adiabatic inward transport of the night-side near-earth ( 6 Re) hot plasma sheet is the dominant contributor to the ring current pressure during storm times. During storm times, the plasma sheet composition in the 6 - 12 Re tail region changes due to O+ entry from the lobes (from the cusp) and the direct feeding from the night side auroral region. In addition, at substorm onset the plasma sheet O+ ions can be preferentially accelerated. We use MMS and observations during two magnetic storms, 5/8/2016 and 7/16/2017, to monitor the composition changes and energization in the 6 - 12 Re plasma sheet region. For both storms the MMS apogee was in the tail. In addition, we use subsequent Van Allen Probe observations (with apogee in the dawn and dusk respectively) to test if the 6-12 Re plasma sheet, observed by MMS, is a sufficient source of the O+ in the ring current. For this we will compare the phase space density (PSD) of the plasma sheet source population and the PSD of the inner magnetosphere at constant magnetic moment values as used in Kistler et al., [2016].

Effect of N{sub 2} and Ar gas on DC arc plasma generation and film composition from Ti-Al compound cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhirkov, Igor, E-mail: igozh@ifm.liu.se; Rosen, Johanna; Oks, Efim

2015-06-07

DC arc plasma from Ti, Al, and Ti{sub 1−x}Al{sub x} (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-state-resolved ion energy for Ar and N{sub 2} pressures in the range 10{sup −6} to 3 × 10{sup −2} Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathodemore » stoichiometry. Introducing N{sub 2} above ∼5 × 10{sup −3} Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N{sub 2} atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions.« less

Effect of Ti-Al cathode composition on plasma generation and plasma transport in direct current vacuum arc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhirkov, I., E-mail: igozh@ifm.liu.se; Petruhins, A.; Dahlqvist, M.

2014-03-28

DC arc plasma from Ti, Al, and Ti{sub 1-x}Al{sub x} (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes was characterized with respect to plasma chemistry and charge-state-resolved ion energy. Scanning electron microscopy, X-ray diffraction, and Energy-dispersive X-ray spectroscopy of the deposited films and the cathode surfaces were used for exploring the correlation between cathode-, plasma-, and film composition. Experimental work was performed at a base pressure of 10{sup −6} Torr, to exclude plasma-gas interaction. The plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathodemore » stoichiometry. This may be explained by presence of neutrals in the plasma/vapour phase. The average ion charge states (Ti = 2.2, Al = 1.65) were consistent with reference data for elemental cathodes, and approximately independent on the cathode composition. On the contrary, the width of the ion energy distributions (IEDs) were drastically reduced when comparing the elemental Ti and Al cathodes with Ti{sub 0.5}Al{sub 0.5}, going from ∼150 and ∼175 eV to ∼100 and ∼75 eV for Ti and Al ions, respectively. This may be explained by a reduction in electron temperature, commonly associated with the high energy tail of the IED. The average Ti and Al ion energies ranged between ∼50 and ∼61 eV, and ∼30 and ∼50 eV, respectively, for different cathode compositions. The attained energy trends were explained by the velocity rule for compound cathodes, which states that the most likely velocities of ions of different mass are equal. Hence, compared to elemental cathodes, the faster Al ions will be decelerated, and the slower Ti ions will be accelerated when originating from compound cathodes. The intensity of the macroparticle generation and thickness of the deposited films were also found to be dependent on the cathode composition. The presented results may be of importance for choice of cathodes for thin film depositions involving compound cathodes.« less

Comparing the effects of different dietary organic acids on the growth, intestinal short-chain fatty acids, and liver histopathology of red hybrid tilapia (Oreochromis sp.) and potential use of these as preservatives.

PubMed

Ebrahimi, Mahdi; Daeman, Nor Hafizah; Chong, Chou Min; Karami, Ali; Kumar, Vikas; Hoseinifar, Seyed Hossein; Romano, Nicholas

2017-08-01

Dietary organic acids are increasingly being investigated as a potential means of improving growth and nutrient utilization in aquatic animals. A 9-week study was performed to compare equal amounts (2%) of different organic acids (sodium butyrate, acetate, propionate, or formate) on the growth, muscle proximate composition, fatty acid composition, cholesterol and lipid peroxidation, differential cell counts, plasma biochemistry, intestinal short-chain fatty acid (SCFA) level, and liver histopathology to red hybrid tilapia (Oreochromis sp.) (initial mean weight of 2.87 g). A second experiment was performed to determine their effects on lipid peroxidation and trimethylamine (TMA) when added at 1% to tilapia meat and left out for 24 h. The results of the first experiment showed no treatment effect to growth, feeding efficiencies, or muscle fatty acid composition, but all dietary organic acids significantly decreased intestinal SCFA. Dietary butyrate and propionate significantly decreased muscle lipid peroxidation compared to the control group, but the dietary formate treatment had the lowest lipid peroxidation compared to all treatments. Muscle crude protein and lipid in tilapia fed the formate diet were significantly lower and higher, respectively, and showed evidence of stress based on the differential cell counts, significantly higher plasma glucose and liver glycogen, as well as inflammatory responses in the liver. Although a potential benefit of dietary organic acids was a reduction to lipid peroxidation, this could be accomplished post-harvest by direct additions to the meat. In addition, inclusions of butyrate and propionate to tilapia meat significantly decreased TMA, which might be a more cost-effective option to improve the shelf life of tilapia products.

Bio-Inspired Ceramic/Carbon Composites

DTIC Science & Technology

2013-05-01

the links between CNTs and the ceramic when the CNT is previously synthesized. Spark Plasma Sintering of SiC/CNTs composites Composites containing...5% of CVD MWCNTs and 95% of SiC nanoparticles (size  100nm) were prepared by Spark Plasma Sintering under different conditions. Table I shows the...additives when necessary (additives were added to help to improve the sintering increasing the density values), and the mixture continuously stirred until

PREFACE: Light element atom, molecule and radical behaviour in the divertor and edge plasma regions

NASA Astrophysics Data System (ADS)

Braams, Bastiaan J.; Chung, Hyun-Kung

2015-01-01

This volume of Journal of Physics: Conference Series contains contributions by participants in an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on "Light element atom, molecule and radical behaviour in the divertor and edge plasma regions" (in magnetic fusion devices). Light elements are the dominant impurity species in fusion experiments and in the near-wall plasma they occur as atoms or ions and also as hydrides and other molecules and molecular ions. Hydrogen (H or D, and T in a reactor) is the dominant species in fusion experiments, but all light elements He - O and Ne are of interest for various reasons. Helium is a product of the D+T fusion reaction and is introduced in experiments for transport studies. Lithium is used for wall coating and also as a beam diagnostic material. Beryllium is foreseen as a wall material for the ITER experiment and is used on the Joint European Torus (JET) experiment. Boron may be used as a coating material for the vessel walls. Carbon (graphite or carbon-fiber composite) is often used as the target material for wall regions subject to high heat load. Nitrogen may be used as a buffer gas for edge plasma cooling. Oxygen is a common impurity in experiments due to residual water vapor. Finally, neon is another choice as a buffer gas. Data for collisional and radiative processes involving these species are important for plasma modelling and for diagnostics. The participants in the CRP met 3 times over the years 2009-2013 for a research coordination meeting. Reports and presentation materials for these meetings are available through the web page on coordinated research projects of the (IAEA) Atomic and Molecular Data Unit [1]. Some of the numerical data generated in the course of the CRP is available through the ALADDIN database [2]. The IAEA takes the opportunity to thank the participants in the CRP for their dedicated efforts in the course of the CRP and for their contributions to this volume. The IAEA scientific officers for this project were Mr Bastiaan J. Braams and Ms Hyun-Kyung Chung. [1] See: https://www-amdis.iaea.org/CRP/ [2] See: https://www-amdis.iaea.org/ALADDIN/

Plasma-grafting polymerization on carbon fibers and its effect on their composite properties

NASA Astrophysics Data System (ADS)

Zhang, Huanxia; Li, Wei

2015-11-01

Interfacial adhesion between matrix and fibers plays a crucial role in controlling the performance of composites. Carbon fibers have the major constraint of chemical interness and hence have limited adhesion with the matrix. Surface treatment of fibers is the best solution to this problem. In this work, carbon fibers were activated by plasma and grafting polymerization. The grafting ratio of polymerization was obtained by acid-base titration. The chemical and physical changes induced by the treatments on carbon fiber surface was examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. The interfacial adhesion of CF/EP (carbon fiber/epoxy) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. Experimental results show that the grafting rate was not only the function of the plasma-treat time but also the concentration of the grafting polymerization. The oxygen-containing groups (such as Csbnd O, Cdbnd O, and Osbnd Cdbnd O) and the interfacial shear strength (IFSS) of the plasma-grafting carbon fiber increased more significantly than the carbon fiber without plasma treatment grafted with MAH. This demonstrates that the surfaces of the carbon fiber samples are more active, hydrophilic, and rough after plasma-grafting treatments using a DBD operating in ambient argon mixture with oxygen. With DBD (dielectric barrier discharges) operating in ambient argon mixture with oxygen, the more active, hydrophilic, and rough surface was obtained by the plasma-grafting treatments.

Simulations of simple linoleic acid-containing lipid membranes and models for the soybean plasma membranes.

PubMed

Zhuang, Xiaohong; Ou, Anna; Klauda, Jeffery B

2017-06-07

The all-atom CHARMM36 lipid force field (C36FF) has been tested with saturated, monounsaturated, and polyunsaturated lipids; however, it has not been validated against the 18:2 linoleoyl lipids with an unsaturated sn-1 chain. The linoleoyl lipids are common in plants and the main component of the soybean membrane. The lipid composition of soybean plasma membranes has been thoroughly characterized with experimental studies. However, there is comparatively less work done with computational modeling. Our molecular dynamics (MD) simulation results show that the pure linoleoyl lipids, 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (18:0/18:2) and 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (di-18:2), agree very well with the experiments, which demonstrates the accuracy of the C36FF for the computational study of soybean membranes. Based on the experimental composition, the soybean hypocotyl and root plasma membrane models are developed with each containing seven or eight types of linoleoyl phospholipids and two types of sterols (sitosterol and stigmasterol). MD simulations are performed to characterize soybean membranes, and the hydrogen bonds and clustering results demonstrate that the lipids prefer to interact with the lipids of the same/similar tail unsaturation. All the results suggest that these two soybean membrane models can be used as a basis for further research in soybean and higher plant membranes involving membrane-associated proteins.

Simulations of simple linoleic acid-containing lipid membranes and models for the soybean plasma membranes

NASA Astrophysics Data System (ADS)

Zhuang, Xiaohong; Ou, Anna; Klauda, Jeffery B.

2017-06-01

The all-atom CHARMM36 lipid force field (C36FF) has been tested with saturated, monounsaturated, and polyunsaturated lipids; however, it has not been validated against the 18:2 linoleoyl lipids with an unsaturated sn-1 chain. The linoleoyl lipids are common in plants and the main component of the soybean membrane. The lipid composition of soybean plasma membranes has been thoroughly characterized with experimental studies. However, there is comparatively less work done with computational modeling. Our molecular dynamics (MD) simulation results show that the pure linoleoyl lipids, 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (18:0/18:2) and 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (di-18:2), agree very well with the experiments, which demonstrates the accuracy of the C36FF for the computational study of soybean membranes. Based on the experimental composition, the soybean hypocotyl and root plasma membrane models are developed with each containing seven or eight types of linoleoyl phospholipids and two types of sterols (sitosterol and stigmasterol). MD simulations are performed to characterize soybean membranes, and the hydrogen bonds and clustering results demonstrate that the lipids prefer to interact with the lipids of the same/similar tail unsaturation. All the results suggest that these two soybean membrane models can be used as a basis for further research in soybean and higher plant membranes involving membrane-associated proteins.

Atomic precision etch using a low-electron temperature plasma

NASA Astrophysics Data System (ADS)

Dorf, L.; Wang, J.-C.; Rauf, S.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

2016-03-01

Sub-nm precision is increasingly being required of many critical plasma etching processes in the semiconductor industry. Accurate control over ion energy and ion/radical composition is needed during plasma processing to meet these stringent requirements. Described in this work is a new plasma etch system which has been designed with the requirements of atomic precision plasma processing in mind. In this system, an electron sheet beam parallel to the substrate surface produces a plasma with an order of magnitude lower electron temperature Te (~ 0.3 eV) and ion energy Ei (< 3 eV without applied bias) compared to conventional radio-frequency (RF) plasma technologies. Electron beam plasmas are characterized by higher ion-to-radical fraction compared to RF plasmas, so a separate radical source is used to provide accurate control over relative ion and radical concentrations. Another important element in this plasma system is low frequency RF bias capability which allows control of ion energy in the 2-50 eV range. Presented in this work are the results of etching of a variety of materials and structures performed in this system. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in RF plasma processing systems, even during atomic layer etch. The experiments for Si etch in Cl2 based plasmas in the aforementioned etch system show that damage can be minimized if the ion energy is kept below 10 eV. Layer-by-layer etch of Si is also demonstrated in this etch system using electrical and gas pulsing.

Effect of Si on DC arc plasma generation from Al-Cr and Al-Cr-Si cathodes used in oxygen

NASA Astrophysics Data System (ADS)

Zhirkov, I.; Landälv, L.; Göthelid, E.; Ahlgren, M.; Eklund, P.; Rosen, J.

2017-02-01

Al2O3 alloyed with Cr is an important material for the tooling industry. It can be synthesized from an arc discharge using Al-Cr cathodes in an oxygen atmosphere. Due to formation of Al-rich oxide islands on the cathode surface, the arc process stability is highly sensitive to oxygen pressure. For improved stability, the use of Al0.70Cr0.25Si0.05 cathodes has previously been suggested, where Si may reduce island formation. Here, we have investigated the effect of Si by comparing plasma generation and thin film deposition from Al0.7Cr0.3 and Al0.7Cr0.25Si0.05 cathodes. Plasma ion composition, ion energies, ion charge states, neutral species, droplet formation, and film composition have been characterized at different O2 flow rates for arc currents of 60 and 90 A. Si and related compounds are detected in plasma ions and in plasma neutrals. Scanning electron microscopy and energy dispersive X-ray analysis show that the cathode composition and the film composition are the same, with Si present in droplets as well. The effect of Si on the process stability, ion energies, and ion charge states is found to be negligible compared to that of the arc current. The latter is identified as the most relevant parameter for tuning the properties of the reactive discharge. The present work increases the fundamental understanding of plasma generation in a reactive atmosphere, and provides input for the choice of cathode composition and process parameters in reactive DC arc synthesis.

Structure and microhardness of the plasma sprayed composite coatings after combined treatment

NASA Astrophysics Data System (ADS)

Ivannikov, A. Yu; Kalita, V. I.; Komlev, D. I.; Radyuk, A. A.; Bagmutov, V. P.; Zakharov, I. N.; Parshev, S. N.; Denisevich, D. S.

2018-04-01

The principal aim of this study was to evaluate the effect of combination of electromechanical treatment (EMT) and ultrasonic treatment on structure and microhardness of air plasma sprayed composite coatings from Ni–20Cr alloy and R6M5 high speed steel (HSS). The results of the microstructural studies showed fundamental changes of the treated by the EMT plasma sprayed coating with the formation of nanostructured crystalline phases. As a consequence of the coating thus formed, the number of pores in the coating structure reduced from 10.0±1.5% to 2.0±0.5%, the surface microhardness increased from 3100±500 MPa to 7900±400 MPa. Additional ultrasonic treatment on the selected mode decreased surface waviness, which was formed on the surface of the plasma sprayed composite coatings after the EMT. The obtained results revealed the high potential of the combined treatment for post-treatment of the plasma sprayed coatings.

Deposition of Composite LSCF-SDC and SSC-SDC Cathodes by Axial-Injection Plasma Spraying

NASA Astrophysics Data System (ADS)

Harris, Jeffrey; Qureshi, Musab; Kesler, Olivera

2012-06-01

The performance of solid oxide fuel cell cathodes can be improved by increasing the number of electrochemical reaction sites, by controlling microstructures, or by using composite materials that consist of an ionic conductor and a mixed ionic and electronic conductor. LSCF (La0.6Sr0.4Co0.2Fe0.8O3-δ) and SSC (Sm0.5Sr0.5CoO3) cathodes were manufactured by axial-injection atmospheric plasma spraying, and composite cathodes were fabricated by mixing SDC (Ce0.8Sm0.2O1.9) into the feedstock powders. The plasma power was varied by changing the proportion of nitrogen in the plasma gas. The microstructures of cathodes produced with different plasma powers were characterized by scanning electron microscopy and gas permeation measurements. The deposition efficiencies of these cathodes were calculated based on the mass of the sprayed cathode. Particle surface temperatures were measured in-flight to enhance understanding of the relationship between spray parameters, microstructure, and deposition efficiency.

Performance of PRP Associated with Porous Chitosan as a Composite Scaffold for Regenerative Medicine

PubMed Central

Shimojo, Andréa Arruda Martins; Perez, Amanda Gomes Marcelino; Galdames, Sofia Elisa Moraga; Brissac, Isabela Cambraia de Souza; Santana, Maria Helena Andrade

2015-01-01

This study aimed to evaluate the in vitro performance of activated platelet-rich plasma associated with porous sponges of chitosan as a composite scaffold for proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells. The sponges were prepared by controlled freezing (−20, −80, or −196°C) and lyophilization of chitosan solutions (1, 2, or 3% w/v). The platelet-rich plasma was obtained from controlled centrifugation of whole blood and activated with calcium and autologous serum. The composite scaffolds were prepared by embedding the sponges with the activated platelet-rich plasma. The results showed the performance of the scaffolds was superior to that of activated platelet-rich plasma alone, in terms of delaying the release of growth factors and increased proliferation of the stem cells. The best preparation conditions of chitosan composite scaffolds that coordinated the physicochemical and mechanical properties and cell proliferation were 3% (w/v) chitosan and a −20°C freezing temperature, while −196°C favored osteogenic differentiation. Although the composite scaffolds are promising for regenerative medicine, the structures require stabilization to prevent the collapse observed after five days. PMID:25821851

Spectroscopy peculiarities of thermal plasma of electric arc discharge between electrodes with Zn admixtures

NASA Astrophysics Data System (ADS)

Semenyshyn, R. V.; Veklich, A. N.; Babich, I. L.; Boretskij, V. F.

2014-10-01

Plasma of the free burning electric arc between Ag-SnO2-ZnO composite electrodes as well as brass electrodes were investigated. The plasma temperature distributions were obtained by Boltzmann plot method involving Cu I, Ag I or Zn I spectral line emissions. The electron density distributions were obtained from the width and from absolute intensity of spectral lines. The laser absorption spectroscopy was used for measurement of copper atom concentration in plasma. Plasma equilibrium composition was calculated using two independent groups of experimental values (temperature and copper atom concentration, temperature and electron density). It was found that plasma of the free burning electric arc between brass electrodes is in local thermodynamical equilibrium. The experimental verification of the spectroscopic data of Zn I spectral lines was carried out.

Plasma surface modification of nanofiltration (NF) thin-film composite (TFC) membranes to improve anti organic fouling

NASA Astrophysics Data System (ADS)

Kim, Eun-Sik; Yu, Qingsong; Deng, Baolin

2011-09-01

Commercial nanofiltration (NF) thin-film composite (TFC) membranes were treated by low-pressure NH3 plasma, and the effects of the plasma treatment were investigated in terms of the membrane hydrophilicity, pure water flux, salt rejection, protein adsorption, and humic acid fouling. Experimental results indicated that the membrane surface hydrophilicity was increased by the plasma treatment, and changes in the hydrophilicity as well as membrane performance including permeate flux and fouling varied with the original membrane characteristics (e.g., roughness and hydrophilicity). Water flux of plasma treated membranes was the highest with 10 min and 90 W of plasma treatment, and salt rejection was mainly affected by the intensity of the plasma power. Results of bovine serum albumin (BSA) adsorption demonstrated that the protein adsorption decreased with increasing plasma treatment time. The plasma treatment that resulted in more negatively charged surfaces could also better prevent Aldrich humic acid (AHA) attachment on the membrane surface.

Feasibility Study for a Plasma Dynamo Facility to Investigate Fundamental Processes in Plasma Astrophysics. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forest, Cary B.

The scientific equipment purchased on this grant was used on the Plasma Dynamo Prototype Experiment as part of Professor Forest's feasibility study for determining if it would be worthwhile to propose building a larger plasma physics experiment to investigate various fundamental processes in plasma astrophysics. The initial research on the Plasma Dynamo Prototype Experiment was successful so Professor Forest and Professor Ellen Zweibel at UW-Madison submitted an NSF Major Research Instrumentation proposal titled "ARRA MRI: Development of a Plasma Dynamo Facility for Experimental Investigations of Fundamental Processes in Plasma Astrophysics." They received funding for this project and the Plasma Dynamomore » Facility also known as the "Madison Plasma Dynamo Experiment" was constructed. This experiment achieved its first plasma in the fall of 2012 and U.S. Dept. of Energy Grant No. DE-SC0008709 "Experimental Studies of Plasma Dynamos," now supports the research.« less

Comparative metabolomics in vegans and omnivores reveal constraints on diet-dependent gut microbiota metabolite production.

PubMed

Wu, Gary D; Compher, Charlene; Chen, Eric Z; Smith, Sarah A; Shah, Rachana D; Bittinger, Kyle; Chehoud, Christel; Albenberg, Lindsey G; Nessel, Lisa; Gilroy, Erin; Star, Julie; Weljie, Aalim M; Flint, Harry J; Metz, David C; Bennett, Michael J; Li, Hongzhe; Bushman, Frederic D; Lewis, James D

2016-01-01

The consumption of an agrarian diet is associated with a reduced risk for many diseases associated with a 'Westernised' lifestyle. Studies suggest that diet affects the gut microbiota, which subsequently influences the metabolome, thereby connecting diet, microbiota and health. However, the degree to which diet influences the composition of the gut microbiota is controversial. Murine models and studies comparing the gut microbiota in humans residing in agrarian versus Western societies suggest that the influence is large. To separate global environmental influences from dietary influences, we characterised the gut microbiota and the host metabolome of individuals consuming an agrarian diet in Western society. Using 16S rRNA-tagged sequencing as well as plasma and urinary metabolomic platforms, we compared measures of dietary intake, gut microbiota composition and the plasma metabolome between healthy human vegans and omnivores, sampled in an urban USA environment. Plasma metabolome of vegans differed markedly from omnivores but the gut microbiota was surprisingly similar. Unlike prior studies of individuals living in agrarian societies, higher consumption of fermentable substrate in vegans was not associated with higher levels of faecal short chain fatty acids, a finding confirmed in a 10-day controlled feeding experiment. Similarly, the proportion of vegans capable of producing equol, a soy-based gut microbiota metabolite, was less than that was reported in Asian societies despite the high consumption of soy-based products. Evidently, residence in globally distinct societies helps determine the composition of the gut microbiota that, in turn, influences the production of diet-dependent gut microbial metabolites. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Improved pharmacokinetics and reduced toxicity of brucine after encapsulation into stealth liposomes: role of phosphatidylcholine

PubMed Central

Chen, Jun; Yan, Guo-jun; Hu, Rong-rong; Gu, Qian-wen; Chen, Ming-lei; Gu, Wei; Chen, Zhi-peng; Cai, Bao-chang

2012-01-01

Objective: Brucine was encapsulated into stealth liposomes using the ammonium sulfate gradient method to improve therapeutic index. Materials and methods: Four brucine stealth liposomal formulations were prepared, which were made from different phosphatidylcholines (PCs) with different phase transition temperatures (Tm). The PCs used were soy phosphatidylcholine (SPC), dipalmitoyl phosphatidylcholine (DPPC), hydrogenated soy phosphatidylcholine (HSPC), and distearoyl phosphatidylcholine (DSPC). The stabilities, pharmacokinetics, and toxicities of these liposomal formulations were evaluated and compared. Results: Size, zeta potential, and entrapment efficiency of brucine-loaded stealth liposomes (BSL) were not influenced by PC composition. In vitro release studies revealed that drug release rate increased with decreased Tm of PCs, especially with the presence of rat plasma. After intravenous administration, the area under the curve (AUC) values of BSL-SPC, BSL-DPPC, BSL-HSPC, and BSL-DSPC in plasma were 7.71, 9.24, 53.83, and 56.83-fold as large as that of free brucine, respectively. The LD50 values of brucine solution, BSL-SPC, BSL-DPPC, BSL-HSPC, and BSL-DSPC following intravenous injection were 13.17, 37.30, 37.69, 51.18, and 52.86 mg/kg, respectively. It was found in calcein retention experiments that the order of calcein retention in rat plasma was SPC < DPPC << HSPC < DSPC stealth liposomes. Conclusion: PC composition could exert significant influence on the stabilities, pharmacokinetics, and toxicities of brucine-loaded stealth liposomes. DSPC or HSPC with Tm above 50°C should be used to prepare the stealth liposomal formulation for the intravenous delivery of brucine. However, it was found in the present paper that the pharmacokinetics and toxicity of BSL were not influenced by the PC composition when the Tm of the PC was in the range of −20°C to 41°C. PMID:22904620

Conditions for the formation of various surface-plasma states upon quasi-steady-state exposure to CO2 laser radiation

NASA Astrophysics Data System (ADS)

Danshchikov, E. V.; Dymshakov, V. A.; Lebedev, F. V.; Riazanov, A. V.

1985-09-01

Experiments were carried out to study the conditions for the formation of an erosion flame in a target vapor on the surface of various metals during quasi-steady-state exposure to CO2 laser radiation. The duration of the CO2 laser pulses was 1 ms. The composition of the metal target specimens and the locations of the focusing spots are given in a table, together with the ambient gas pressures. The formation of an optical discharge in the ambient gas near the surface of the metal target specimens is described in detail. Some fundamental relationships between the laser parameters and the plasma characteristics of the different metal specimens are discussed on the basis of the experimental data.

Energy resolved actinometry for simultaneous measurement of atomic oxygen densities and local mean electron energies in radio-frequency driven plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greb, Arthur, E-mail: ag941@york.ac.uk; Niemi, Kari; O'Connell, Deborah

2014-12-08

A diagnostic method for the simultaneous determination of atomic oxygen densities and mean electron energies is demonstrated for an atmospheric pressure radio-frequency plasma jet. The proposed method is based on phase resolved optical emission measurements of the direct and dissociative electron-impact excitation dynamics of three distinct emission lines, namely, Ar 750.4 nm, O 777.4 nm, and O 844.6 nm. The energy dependence of these lines serves as basis for analysis by taking into account two line ratios. In this frame, the method is highly adaptable with regard to pressure and gas composition. Results are benchmarked against independent numerical simulations and two-photon absorption laser-inducedmore » fluorescence experiments.« less

Complete positive ion, electron, and ram negative ion measurements near Comet Halley (COPERNIC) plasma experiment for the European Giotto Mission

NASA Technical Reports Server (NTRS)

Lin, Robert P.

1988-01-01

Participation of U.S. scientists on the COPERNIC (COmplete Positive ions, Electrons and Ram Negative Ion measurements near Comet Halley) plasma experiment on the Giotto mission is described. The experiment consisted of two detectors: the EESA (electron electrostatic analyzer) which provided three-dimensional measurements of the distribution of electrons from 10 eV to 30 keV, and the PICCA (positive ion cluster composition analyzer) which provided mass analysis of positively charged cold cometary ions from mass 10 to 210 amu. In addition, a small 3 deg wide sector of the EESA looking in the ram direction was devoted to the detection of negatively charged cold cometary ions. Both detectors operated perfectly up to near closest approach (approx. 600 km) to Halley, but impacts of dust particles and neutral gas on the spacecraft contaminated parts of the data during the last few minutes. Although no flight hardware was fabricated in the U.S., The U.S. made very significant contributions to the hardware design, ground support equipment (GSE) design and fabrication, and flight and data reduction software required for the experiment, and also participated fully in the data reduction and analysis, and theoretical modeling and interpretation. Cometary data analysis is presented.

Minimally-invasive Laser Ablation Inductively Coupled Plasma Mass Spectrometry analysis of model ancient copper alloys

NASA Astrophysics Data System (ADS)

Walaszek, Damian; Senn, Marianne; Wichser, Adrian; Faller, Markus; Wagner, Barbara; Bulska, Ewa; Ulrich, Andrea

2014-09-01

This work describes an evaluation of a strategy for multi-elemental analysis of typical ancient bronzes (copper, lead bronze and tin bronze) by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS).The samples originating from archeological experiments on ancient metal smelting processes using direct reduction in a ‘bloomery’ furnace as well as historical casting techniques were investigated with the use of the previously proposed analytical procedure, including metallurgical observation and preliminary visual estimation of the homogeneity of the samples. The results of LA-ICPMS analysis were compared to the results of bulk composition obtained by X-ray fluorescence spectrometry (XRF) and by inductively coupled plasma mass spectrometry (ICPMS) after acid digestion. These results were coherent for most of the elements confirming the usefulness of the proposed analytical procedure, however the reliability of the quantitative information about the content of the most heterogeneously distributed elements was also discussed in more detail.

Surface changes of biopolymers PHB and PLLA induced by Ar+ plasma treatment and wet etching

NASA Astrophysics Data System (ADS)

Slepičková Kasálková, N.; Slepička, P.; Sajdl, P.; Švorčík, V.

2014-08-01

Polymers, especially group of biopolymers find potential application in a wide range of disciplines due to their biodegradability. In biomedical applications these materials can be used as a scaffold or matrix. In this work, the influence of the Ar+ plasma treatment and subsequent wet etching (acetone/water) on the surface properties of polymers were studied. Two biopolymers - polyhydroxybutyrate with 8% polyhydroxyvalerate (PHB) and poly-L-lactic acid (PLLA) were used in these experiments. Modified surface layers were analyzed by different methods. Surface wettability was characterized by determination of water contact angle. Changes in elemental composition of modified surfaces were performed by X-ray Photoelectron Spectroscopy (XPS). Surface morphology and roughness was examined using Atomic Force Microscopy (AFM). Gravimetry method was used to study the mass loss. It was found that the modification from both with plasma and wet etching leads to dramatic changes of surface properties (surface chemistry, morphology and roughness). Rate of changes of these features strongly depends on the modification parameters.

Simulation and experimental verification of silicon dioxide deposition by PECVD

NASA Astrophysics Data System (ADS)

Xu, Qing; Li, Yu-Xing; Li, Xiao-Ning; Wang, Jia-Bin; Yang, Fan; Yang, Yi; Ren, Tian-Ling

2017-02-01

Deposition of silicon dioxide in high-density plasma is an important process in integrated circuit manufacturing. A software named CFD-ACE was used to simulate the mechanism of plasma in the chamber of plasma enhanced chemical vapor deposition (PECVD) system, and the evolution of the feature profile was simulated based on CFD-TOPO. Simulation and experiment of silicon dioxide that deposited in SiH4/N2O mixture by PECVD system was researched. The particle density, energy and angular distribution in the chamber were simulated and discussed. We also studied how the depth/width ratio affected the step coverage of the trench and analyzed the deposition rate of silicon dioxide on the feature scale. X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition of thin films. Images of the feature profiles were taken by scanning electron microscope (SEM). The simulation results were in good agreement with experimental, which could guide the semiconductor device manufacture.

Changes of composition and microstructure of joint interface of tungsten coated carbon by high heat flux

NASA Astrophysics Data System (ADS)

Tokunaga, K.; Matsubara, T.; Miyamoto, Y.; Takao, Y.; Yoshida, N.; Noda, N.; Kubota, Y.; Sogabe, T.; Kato, T.; Plöchl, L.

2000-12-01

Tungsten coatings of 0.5 and 1 mm thickness were successfully deposited by the vacuum plasma spraying (VPS) technique on carbon/carbon fiber composite (CFC), CX-2002U and isotropic fine grained graphite, IG-430U. High heat flux experiments by irradiation of electron beam with uniform profile were performed on the coated samples in order to prove the suitability and load limit of such coating materials. The cross-sectional composition and structure of the interface of VPS-W and carbon material samples were investigated. Compositional analyses showed that the Re/W multi-layer acts as diffusion barrier for carbon and suppresses tungsten carbide formation in the VPS-W layer at high temperature about 1300°C. Microstructure of the joint interface of the sample changed in the case of a peak temperature of about 2800°C. The multi-layer structure completely disappeared and compositional distribution was almost uniform in the interface of the sample after melting and resolidification. The diffusion barrier for carbon is not expected to act in this stage.

Plasma Spraying of Ceramics with Particular Difficulties in Processing

NASA Astrophysics Data System (ADS)

Mauer, G.; Schlegel, N.; Guignard, A.; Jarligo, M. O.; Rezanka, S.; Hospach, A.; Vaßen, R.

2015-01-01

Emerging new applications and growing demands of plasma-sprayed coatings initiate the development of new materials. Regarding ceramics, often complex compositions are employed to achieve advanced material properties, e.g., high thermal stability, low thermal conductivity, high electronic and ionic conductivity as well as specific thermo-mechanical properties and microstructures. Such materials however, often involve particular difficulties in processing by plasma spraying. The inhomogeneous dissociation and evaporation behavior of individual constituents can lead to changes of the chemical composition and the formation of secondary phases in the deposited coatings. Hence, undesired effects on the coating characteristics are encountered. In this work, examples of such challenging materials are investigated, namely pyrochlores applied for thermal barrier coatings as well as perovskites for gas separation membranes. In particular, new plasma spray processes like suspension plasma spraying and plasma spray-physical vapor deposition are considered. In some cases, plasma diagnostics are applied to analyze the processing conditions.

Influence of boar breeds or hybrid genetic composition on semen quality and seminal plasma biochemical variables.

PubMed

Žaja, Ivona Žura; Samardžija, Marko; Vince, Silvijo; Majić-Balić, Ivanka; Vilić, Marinko; Đuričić, Dražen; Milinković-Tur, Suzana

2016-01-01

The enzyme concentrations of seminal plasma are important for spermatozoa metabolism and function in boars. The need has arisen for introducing a biochemical evaluation of semen, along with the usual standard semen analyses. There are no data on the influence of boar breeds on the seminal plasma biochemical variables investigated in this study. Therefore, the objective was to determine the influence of breed and hybrid genetic composition of boars on semen quality and seminal plasma biochemical variables. Semen samples of 27 boars (Swedish Landrace, German Landrace, Large White, Pietrain and Pig Improvement Company hybrid-PIC-hybrid), aged between 1.5 and 3 years, were collected. After evaluation of semen quality, the seminal plasma was separated from the spermatozoa by centrifugation of semen. The seminal plasma was subjected to spectrophotometric analysis to determine alkaline phosphatase (ALP), acid phosphatase (ACP), γ-glutamyltransferase (GGT), creatine kinase (CK) and lactate dehydrogenase (LDH) and to atomic absorption spectrophotometric analysis to measure the concentration of calcium and magnesium. Conventional semen quality variables differed depending on breed and PIC-hybrid genetic composition, though these differences were typically insignificant. In the seminal plasma, significant differences were determined in enzyme activity (ALP, GGT, CK and LDH) and in calcium concentration among boars of different breeds. There are, therefore, differences in semen quality and significant differences in the seminal plasma biochemical variables among boars of different breeds and PIC-hybrid genetic composition. The data and differences in semen variables detected in the present study provide knowledge for enhancing evaluation and monitoring of boar reproductive potential, semen quality and explain the potential causes of boar infertility. Copyright © 2015 Elsevier B.V. All rights reserved.

Impact of Near-Earth Plasma Sheet Dynamics on the Ring Current Composition

NASA Astrophysics Data System (ADS)

Kistler, L. M.; Mouikis, C.; Menz, A.; Spence, H. E.; Mitchell, D. G.; Gkioulidou, M.; Lanzerotti, L. J.; Skoug, R. M.; Larsen, B.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.

2014-12-01

How the dynamics in the near-earth plasma sheet affects the heavy ion content, and therefore the ion pressure, of the ring current in Earth's magnetosphere is an outstanding question. Substorms accelerate plasma in the near-earth region and drive outflow from the aurora, and both these processes can preferentially enhance the population of heavy ions in this region. These heavy ions are then driven into the inner magnetosphere during storms. Thus understanding how the composition of the ring current changes requires simultaneous observations in the near-earth plasma sheet and in the inner magnetosphere. We use data from the CODIF instrument on Cluster and HOPE, RBSPICE, and MagEIS instruments on the Van Allen Probes to study the acceleration and transport of ions from the plasma sheet into the ring current. During the main phase of a geomagnetic storm on Aug 4-6, 2013, the Cluster spacecraft were moving inbound in the midnight central plasma sheet, while the apogees of the two Van Allen Probes were located on the duskside. The Cluster spacecraft measure the composition and spectral changes in the plasma sheet, while the Van Allen Probes measure the ions that reach the inner magnetosphere. A strong increase in 1-40 keV O+ was observed at the Cluster location during the storm main phase, and the Van Allen Probes observed both H+ and O+ being driven deep into the inner magnetosphere. By comparing the variations in phase space density (PSD) vs. magnetic moment at the Cluster and the Van Allen Probes locations, we examine how the composition changes non-adiabatically in the near-earth plasma sheet, and how those changes are propagated into the inner magnetosphere, populating the hto ion ring current.

Plasma Methods of Obtainment of Multifunctional Composite Materials, Dispersion-Hardened by Nanoparticles

NASA Astrophysics Data System (ADS)

Sizonenko, O. N.; Grigoryev, E. G.; Pristash, N. S.; Zaichenko, A. D.; Torpakov, A. S.; Lypian, Ye. V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.

2017-09-01

High voltage electric discharge (HVED) in disperse system "hydrocarbon liquid - powder" due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. Spark plasma sintering (SPS) of powder mixtures allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10-20 %), hardness and wear-resistance (by 30-60 %) of obtained materials.

Adaptive plasma for cancer therapy: physics, mechanism and applications

NASA Astrophysics Data System (ADS)

Keidar, Michael

2017-10-01

One of the most promising applications of cold atmospheric plasma (CAP) is the cancer therapy. The uniqueness of plasma is in its ability to change composition in situ. Plasma self-organization could lead to formation of coherent plasma structures. These coherent structures tend to modulate plasma chemistry and composition, including reactive species, the electric field and charged particles. Formation of coherent plasma structures allows the plasma to adapt to external boundary conditions, such as different cells types and their contextual tissues. In this talk we will explore possibilities and opportunities that the adaptive plasma therapeutic system might offer. We shall define such an adaptive system as a plasma device that is able to adjust the plasma composition to obtain optimal desirable outcomes through its interaction with cells and tissues. The efficacy of cold plasma in a pre-clinical model of various cancer types such as lung, bladder, breast, head, neck, brain and skin has been demonstrated. Both in-vitro and in-vivo studies revealed that cold plasmas selectively kill cancer cells. Recently mechanism of plasma selectivity based on aquaporin hypothesis has been proposed. Aquaporins (AQPs) are the confirmed membrane channels of H2O2 and other large molecules. We have demonstrated that the anti-cancer capacity of plasma could be inhibited by silencing the expression of AQPs. Additional possible cell feedback mechanism was recently discovered. It is associated with production of reactive species during direct CAP treatment by cancer cells. Selective production of hydrogen peroxide by different cells can lead to adaptation of chemistry at the plasma-cell interface based on the cellular input. In particular we have found that the discharge voltage is an important factor affecting the ratio of reactive oxygen species to reactive nitrogen species in the gas phase and this correlates well with effect of hydrogen peroxide production by cells. This work was supported by a National Science Foundation, Grant No. 1465061.

Experiment to Form and Characterize a Section of a Spherically Imploding Plasma Liner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, S. C.; Langendorf, S. J.; Yates, K. C.

Here, we describe an experiment to form and characterize a section of a spherically imploding plasma liner by merging six supersonic plasma jets that are launched by newly designed contoured-gap coaxial plasma guns. This experiment is a prelude to forming a fully spherical imploding plasma liner using many dozens of plasma guns, as a standoff driver for plasma-jet-driven magneto-inertial fusion. The objectives of the six-jet experiments are to assess the evolution and scalings of liner Mach number and uniformity, which are important metrics for spherically imploding plasma liners to compress magnetized target plasmas to fusion conditions. Lastly, this article describesmore » the design of the coaxial plasma guns, experimental characterization of the plasma jets, six-jet experimental setup and diagnostics, initial diagnostic data from three- and six-jet experiments, and the high-level objectives of associated numerical modeling.« less

Experiment to Form and Characterize a Section of a Spherically Imploding Plasma Liner

DOE PAGES

Hsu, S. C.; Langendorf, S. J.; Yates, K. C.; ...

2017-12-18

Here, we describe an experiment to form and characterize a section of a spherically imploding plasma liner by merging six supersonic plasma jets that are launched by newly designed contoured-gap coaxial plasma guns. This experiment is a prelude to forming a fully spherical imploding plasma liner using many dozens of plasma guns, as a standoff driver for plasma-jet-driven magneto-inertial fusion. The objectives of the six-jet experiments are to assess the evolution and scalings of liner Mach number and uniformity, which are important metrics for spherically imploding plasma liners to compress magnetized target plasmas to fusion conditions. Lastly, this article describesmore » the design of the coaxial plasma guns, experimental characterization of the plasma jets, six-jet experimental setup and diagnostics, initial diagnostic data from three- and six-jet experiments, and the high-level objectives of associated numerical modeling.« less

Microwave plasma CVD of NANO structured tin/carbon composites

DOEpatents

Marcinek, Marek [Warszawa, PL; Kostecki, Robert [Lafayette, CA

2012-07-17

A method for forming a graphitic tin-carbon composite at low temperatures is described. The method involves using microwave radiation to produce a neutral gas plasma in a reactor cell. At least one organo tin precursor material in the reactor cell forms a tin-carbon film on a supporting substrate disposed in the cell under influence of the plasma. The three dimensional carbon matrix material with embedded tin nanoparticles can be used as an electrode in lithium-ion batteries.

Research into properties of wear resistant ceramic metal plasma coatings

NASA Astrophysics Data System (ADS)

Ivancivsky, V. V.; Skeeba, V. Yu; Zverev, E. A.; Vakhrushev, N. V.; Parts, K. A.

2018-03-01

The study considers one of the promising ways to improve the quality of wear resistant plasma ceramic coatings by implementing various powder mixtures. The authors present the study results of the nickel-ceramic and cobalt-ceramic coating properties and describe the specific character of the investigated coatings composition. The paper presents the results of the coating microhardness, chemical and adhesive strength studies. The authors conducted wear resistance tests of composite coatings in comparison with the plasma coatings of initial powder components.

Research Progress in Plasma arc welding of Magnesium Alloys and Magnesium Matrix Composites

NASA Astrophysics Data System (ADS)

Hui, Li; Yang, Zou; Yongbo, Li; Lei, Jiao; Ruijun, Hou

2017-11-01

Magnesium alloys and magnesium matrix composites by means of its excellent performance have wide application prospect in electronics, automotive, biotechnology, aerospace field, and welding technology has become a key of restricting its application. This paper describes the welding characteristics of magnesium, the obvious advantages in the application and the domestic and foreign research advance technology of plasma arc welding of magnesium, and summarizes the existing problems and development trends of plasma arc welding technology of magnesium.

Effect of dietary fat source on lipoprotein composition and plasma lipid concentrations in pigs.

PubMed

Faidley, T D; Luhman, C M; Galloway, S T; Foley, M K; Beitz, D C

1990-10-01

Most studies of the effects of dietary fat sources on plasma lipid components have used diets with extreme fat compositions; the current study was designed to more nearly mimic human dietary fat intake. Young growing pigs were fed diets containing either 20 or 40% of energy as soy oil, beef tallow or a 50/50 blend of soy oil and tallow. Different dietary fats did not affect concentrations of cholesterol, triacylglycerol or protein in plasma or major lipoprotein fractions. The concentration of phospholipid was less in plasma and in very low density lipoproteins with soy oil feeding than with tallow feeding. The weight percentage of cholesteryl ester in the low density lipoprotein fraction tended to be greater with 40% than with 20% tallow and tended to be less with 40% than with 20% soy oil. Phospholipid as a weight percentage of low density lipoprotein was least in pigs fed soy oil. Tallow feeding increased the percentage of myristic, palmitic, palmitoleic and oleic acids in plasma, relative to both other groups. Soy oil feeding increased the percentage of linoleic and linolenic acids. These moderate diets were not hypercholesterolemic, but they did alter plasma fatty acid composition and phospholipid concentrations in plasma and very low density lipoprotein.

Influence of hydrophilic pre-treatment on resin bonding to zirconia ceramics.

PubMed

Noro, Akio; Kameyama, Atsushi; Haruyama, Akiko; Takahashi, Toshiyuki

2015-01-01

Atmospheric plasma or ultraviolet (UV) treatment alters the surface characteristics of tetragonal zirconia polycrystal (TZP), increasing its hydrophilicity by reducing the contact angle against water to zero. This suggests that such treatment would increase the wettability of bonding resin. The purpose of this study was to determine how increasing the hydrophilicity of TZP through plasma irradiation, UV treatment, or application of ceramic primer affected initial bonding with resin composites. Here, the effect of each pre-treatment on the hydrophilicity of TZP surfaces was determined by evaluating change in shear bond strength. Plasma irradiation, UV, or ceramic primer pre-treatment showed no significant effect on bonding strength between TZP surfaces and resin composites. In addition, alumina blasting yielded no significant increase in bond strength. Plasma irradiation, UV treatment, or ceramic primer pre-treatment did not lead to significant increase in bond strength between TZP and resin composites.

Fuel Retention Improvement at High Temperatures in Tungsten-Uranium Dioxide Dispersion Fuel Elements by Plasma-Spray Cladding

NASA Technical Reports Server (NTRS)

Grisaffe, Salvatore J.; Caves, Robert M.

1964-01-01

An investigation was undertaken to determine the feasibility of depositing integrally bonded plasma-sprayed tungsten coatings onto 80-volume-percent tungsten - 20-volume-percent uranium dioxide composites. These composites were face clad with thin tungsten foil to inhibit uranium dioxide loss at elevated temperatures, but loss at the unclad edges was still significant. By preheating the composite substrates to approximately 3700 degrees F in a nitrogen environment, metallurgically bonded tungsten coatings could be obtained directly by plasma spraying. Furthermore, even though these coatings were thin and somewhat porous, they greatly inhibited the loss of uranium dioxide. For example, a specimen that was face clad but had no edge cladding lost 5.8 percent uranium dioxide after 2 hours at 4750 dgrees F in flowing hydrogen. A similar specimen with plasma-spray-coated edges, however, lost only 0.75 percent uranium dioxide under the same testing conditions.

Tungsten-microdiamond composites for plasma facing components

NASA Astrophysics Data System (ADS)

Livramento, V.; Nunes, D.; Correia, J. B.; Carvalho, P. A.; Mardolcar, U.; Mateus, R.; Hanada, K.; Shohoji, N.; Fernandes, H.; Silva, C.; Alves, E.

2011-09-01

Tungsten is considered as one of promising candidate materials for plasma facing component in nuclear fusion reactors due to its resistance to sputtering and high melting point. High thermal conductivity is also a prerequisite for plasma facing components under the unique service environment of fusion reactor characterised by the massive heat load, especially in the divertor area. The feasibility of mechanical alloying of nanodiamond and tungsten, and the consolidation of the composite powders with Spark Plasma Sintering (SPS) was previously demonstrated. In the present research we report on the use of microdiamond instead of nanodiamond in such composites. Microdiamond is more favourable than nanodiamond in view of phonon transport performance leading to better thermal conductivity. However, there is a trade off between densification and thermal conductivity as the SPS temperature increases tungsten carbide formation from microdiamond is accelerated inevitably while the consolidation density would rise.

Plasma modification of sisal and high-density polyethylene composites : effect on mechanical properties

Treesearch

A.R. Martin; S. Manolache; L.H.C. Mattoso; R.M. Rowell; F. Denes

2000-01-01

Sisal fibers and finely powdered high-density polyethylene were surface functionalized using dichlorosilane (DS) under R-F plasma conditions to improve interfacial adhesion between the two dissimilar substrates. The functionalized polyethylene (70%) and sisal (30%) were compounded on four different ways using thermokinetic mixer and injected molded into composites...

Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process

NASA Astrophysics Data System (ADS)

Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

2017-11-01

The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

Development of a Cr-Based Hard Composite Processed by Spark Plasma Sintering

NASA Astrophysics Data System (ADS)

García-Junceda, A.; Sáez, I.; Deng, X. X.; Torralba, J. M.

2018-04-01

This investigation analyzes the feasibility of processing a composite material comprising WC particles randomly dispersed in a matrix in which Cr is the main metallic binder. Thus, a new composite material is processed using a commercial, economic, and easily available Cr-based alloy, assuming that there is a certain Cr solubility in the WC particles acting as reinforcement. The processing route followed includes mechanical milling of the powders and consolidation by spark plasma sintering.

Mucin and carbon nanotube-based biosensor for detection of glucose in human plasma.

PubMed

Comba, Fausto N; Romero, Marcelo R; Garay, Fernando S; Baruzzi, Ana M

2018-06-01

This work reports an amperometric enzyme-electrode prepared with glucose oxidase, which have been immobilized by a cross-linking step with glutaraldehyde in a mixture containing albumin and a novel carbon nanotubes-mucin composite (CNT-muc). The obtained hydrogel matrix was trapped between two polycarbonate membranes and then fixed at the surface of a Pt working electrode. The developed biosensor was optimized by evaluating different compositions and the analytical properties of an enzymatic matrix with CNT-muc. Then, the performance of the resulting enzymatic matrix was evaluated for direct glucose quantification in human blood plasma. The novel CNT-muc composite provided a sensitivity of 0.44 ± 0.01 mA M -1 and a response time of 28 ± 2 s. These values were respectively 20% higher and 40% shorter than those obtained with a sandwich-type biosensor prepared without CNT. Additionally, CNT-muc based biosensor exhibited more than 3 orders of magnitude of linear dynamic calibration range and a detection limit of 3 μM. The short-term and long-term stabilities of the biosensors were also examined and excellent results were obtained through successive experiments performed within the first 60 days from their preparation. Finally, the storage stability was remarkable during the first 300 days. Copyright © 2018 Elsevier Inc. All rights reserved.

Composition of highly concentrated silicate electrolytes and ultrasound influencing the plasma electrolytic oxidation of magnesium

NASA Astrophysics Data System (ADS)

Simchen, F.; Rymer, L.-M.; Sieber, M.; Lampke, T.

2017-03-01

Magnesium and its alloys are increasingly in use as lightweight construction materials. However, their inappropriate corrosion and wear resistance often prevent their direct practical use. The plasma electrolytic oxidation (PEO) is a promising, environmentally friendly method to improve the surface characteristics of magnesium materials by the formation of oxide coatings. These PEO layers contain components of the applied electrolyte and can be shifted in their composition by increasing the concentration of the electrolyte constituents. Therefore, in contrast to the use of conventional low concentrated electrolytes, the process results in more stable protective coatings, in which electrolyte species are the dominating constitutes. In the present work, the influence of the composition of highly concentrated alkaline silicate electrolytes with additives of phosphate and glycerol on the quality of PEO layers on the magnesium alloy AZ31 was examined. The effect of ultrasound coupled into the electrolyte bath was also considered. The process was monitored by recording the electrical process variables with a transient recorder and by observation of the discharge phenomena on the sample surface with a camera. The study was conducted on the basis of a design of experiments. The effects of the process parameter variation are considered with regard to the coatings thickness, hardness and corrosion resistance. Information about the statistical significance of the effects of the parameters on the considered properties is obtained by an analysis of variance (ANOVA).

Mathematical modeling of chemical composition modification and etching of polymers under the atomic oxygen influence

NASA Astrophysics Data System (ADS)

Chirskaia, Natalia; Novikov, Lev; Voronina, Ekaterina

2016-07-01

Atomic oxygen (AO) of the upper atmosphere is one of the most important space factors that can cause degradation of spacecraft surface. In our previous mathematical model the Monte Carlo method and the "large particles" approximation were used for simulating processes of polymer etching under the influence of AO [1]. The interaction of enlarged AO particles with the polymer was described in terms of probabilities of reactions such as etching of polymer and specular and diffuse scattering of the AO particles on polymer. The effects of atomic oxygen on protected polymers and microfiller containing composites were simulated. The simulation results were in quite good agreement with the results of laboratory experiments on magnetoplasmadynamic accelerator of the oxygen plasma of SINP MSU [2]. In this paper we present a new model that describes the reactions of AO interactions with polymeric materials in more detail. Reactions of formation and further emission of chemical compounds such as CO, CO _{2}, H _{2}O, etc. cause the modification of the chemical composition of the polymer and change the probabilities of its consequent interaction with the AO. The simulation results are compared with the results of previous simulation and with the results of laboratory experiments. The reasons for the differences between the results of natural experiments on spacecraft, laboratory experiments and simulations are discussed. N. Chirskaya, M. Samokhina, Computer modeling of polymer structures degradation under the atomic oxygen exposure, WDS'12 Proceedings of Contributed Papers: Part III - Physics, Matfyzpress Prague, 2012, pp. 30-35. E. Voronina, L. Novikov, V. Chernik, N. Chirskaya, K. Vernigorov, G. Bondarenko, and A. Gaidar, Mathematical and experimental simulation of impact of atomic oxygen of the earth's upper atmosphere on nanostructures and polymer composites, Inorganic Materials: Applied Research, 2012, vol. 3, no. 2, pp. 95-101.

Titan Ion Composition at Magnetosphere-Ionosphere Transition Region

NASA Technical Reports Server (NTRS)

Sittler, Edward C.; Hartle, R. E.; Shappirio, M.; Simpson, D. J.; COoper, J. F.; Burger, M. H.; Johnson, R. E.; Bertucci, C.; Luhman, J. G.; Ledvina, S. A.;

Pulsed plasma polymerization for controlling shrinkage and surface composition of nanopores

NASA Astrophysics Data System (ADS)

Asghar, Waseem; Ilyas, Azhar; Deshmukh, Rajendra R.; Sumitsawan, Sulak; Timmons, Richard B.; Iqbal, Samir M.

2011-07-01

Solid-state nanopores have emerged as sensors for single molecules and these have been employed to examine the biophysical properties of an increasingly large variety of biomolecules. Herein we describe a novel and facile approach to precisely adjust the pore size, while simultaneously controlling the surface chemical composition of the solid-state nanopores. Specifically, nanopores fabricated using standard ion beam technology are shrunk to the requisite molecular dimensions via the deposition of highly conformal pulsed plasma generated thin polymeric films. The plasma treatment process provides accurate control of the pore size as the conformal film deposition depends linearly on the deposition time. Simultaneously, the pore and channel chemical compositions are controlled by appropriate selection of the gaseous monomer and plasma conditions employed in the deposition of the polymer films. The controlled pore shrinkage is characterized with high resolution AFM, and the film chemistry of the plasma generated polymers is analyzed with FTIR and XPS. The stability and practical utility of this new approach is demonstrated by successful single molecule sensing of double-stranded DNA. The process offers a viable new advance in the fabrication of tailored nanopores, in terms of both the pore size and surface composition, for usage in a wide range of emerging applications.

A C8-Modified Graphene@mSiO2 Composites Based Method for Quantification of Gallic Acid in Rat Plasma after Oral Administration of Changtai Granule and Its Application to Pharmacokinetics.

PubMed

Xu, Chen; Yu, Yingjia; Ling, Li; Wang, Yang; Zhang, Jundong; Li, Yan; Duan, Gengli

2017-01-01

A rapid, effective extraction technique has been established for measuring the gallic acid in rat plasma by using sandwich-structured graphene/mesoporous silica composites with C 8 -modified interior pore-walls as adsorbent. The unique characteristics of the graphene-silica composites excluded large molecules, like proteins, from the mesopore channels as a result of size exclusion effect, leading to a direct extraction of drug molecules from protein-rich biological samples such as plasma without any other pretreatment procedure. Followed by elution and centrifugation, the gallic acid-absorbed composites were rapidly isolated before LC-MS/MS. Serving as a reliable tool for analysis of Traditional Chinese Medicine: Changtai Granule, the newly developed method was fully validated and successfully applied in the pharmacokinetic study of gallic acid in rat plasma. Extraction recovery, matrix effect and stability were satisfactory in rat plasma. According to the results of pharmacokinetic studies, Changtai Granule exhibited greater adsorption, distribution and clearance properties of gallic acid in the treatment of ulcerative colitis. Hence, this study may offer a valuable alternative to simplify and speed up sample preparation, and be useful for clinical studies of related preparations.

Photometric analysis of a space shuttle water venting

NASA Technical Reports Server (NTRS)

Viereck, R. A.; Murad, E.; Pike, C. P.; Kofsky, I. L.; Trowbridge, C. A.; Rall, D. L. A.; Satayesh, A.; Berk, A.; Elgin, J. B.

1991-01-01

Presented here is a preliminary interpretation of a recent experiment conducted on Space Shuttle Discovery (Mission STS 29) in which a stream of liquid supply water was vented into space at twilight. The data consist of video images of the sunlight-scattering water/ice particle cloud that formed, taken by visible light-sensitive intensified cameras both onboard the spacecraft and at the AMOS ground station near the trajectory's nadir. This experiment was undertaken to study the phenomenology of water columns injected into the low-Earth orbital environment, and to provide information about the lifetime of ice particles that may recontact Space Shuttle orbits later. The findings about the composition of the cloud have relevance to ionospheric plasma depletion experiments and to the dynamics of the interaction of orbiting spacecraft with the environment.

Measurement realities of current collection in dynamic space plasma environments

NASA Technical Reports Server (NTRS)

Szuszczewicz, Edward P.

1990-01-01

Theories which describe currents collected by conducting and non-conducting bodies immersed in plasmas have many of their concepts based upon the fundamentals of sheath-potential distributions and charged-particle behavior in superimposed electric and magnetic fields. Those current-collecting bodies (or electrodes) may be Langmuir probes, electric field detectors, aperture plates on ion mass spectrometers and retarding potential analyzers, or spacecraft and their rigid and tethered appendages. Often the models are incomplete in representing the conditions under which the current-voltage characteristics of the electrode and its system are to be measured. In such cases, the experimenter must carefully take into account magnetic field effects and particle anisotropies, perturbations caused by the current collection process itself and contamination on electrode surfaces, the complexities of non-Maxwellian plasma distributions, and the temporal variability of the local plasma density, temperature, composition and fields. This set of variables is by no means all-inclusive, but it represents a collection of circumstances guaranteed to accompany experiments involving energetic particle beams, plasma discharges, chemical releases, wave injection and various events of controlled and uncontrolled spacecraft charging. Here, an attempt is made to synopsize these diagnostic challenges and frame them within a perspective that focuses on the physics under investigation and the requirements on the parameters to be measured. Examples include laboratory and spaceborne applications, with specific interest in dynamic and unstable plasma environments.

Effect of different monosaccharides and disaccharides on boar sperm quality after cryopreservation.

PubMed

Gómez-Fernández, José; Gómez-Izquierdo, Emilio; Tomás, Cristina; Mocé, Eva; de Mercado, Eduardo

2012-07-01

The aim of the present study was to evaluate the cryoprotectant effect of different non-permeating sugars for boar sperm. Pooled semen from three boars was used for the experiments. In the first experiment, the sperm quality of boar sperm cryopreserved with an egg-yolk based extender supplemented with different monosaccharides (glucose, galactose or fructose) was compared to a control cryopreserved in lactose-egg yolk extender. In the second experiment, the effect of five disaccharides (lactose, sucrose, lactulose, trehalose or melibiose) on boar sperm cryosurvival was studied. Several sperm quality parameters were assessed by flow cytometry in samples incubated for 30 and 150 min at 37°C after thawing: percentages of sperm with intact plasma membrane (SIPM), sperm presenting high plasma membrane fluidity (HPMF), sperm with intracellular reactive oxygen substances production (IROSP) and apoptotic sperm (AS). In addition, the percentages of total motile (TMS) and progressively motile sperm (PMS) were assessed at the same incubation times with a computer-assisted sperm analysis system. Freezing extenders supplemented with each of the monosaccharide presented smaller cryoprotective effect than the control extender supplemented with lactose (P<0.05). However, from the three monosaccharides tested, glucose provided the best sperm quality after freezing-thawing. With respect to the disaccharides studied, samples frozen with the extender supplemented with lactulose exhibited in general the lowest sperm quality, except for the percentage of capacitated sperm, which was highest (P<0.05) in the samples cryopreserved with the trehalose extender. Our results suggest that disaccharides have higher cryoprotective effect than monosaccharides, although the monosaccharide composition of the disaccharides is also important, since the best results were obtained with those disaccharides presenting glucose in their composition. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis and characterization of aluminium–alumina micro- and nano-composites by spark plasma sintering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dash, K., E-mail: khushbudash@gmail.com; Chaira, D.; Ray, B.C.

Graphical abstract: The evolution of microstructure by varying the particle size of reinforcement in the matrix employing spark plasma sintering has been demonstrated here in Al–Al{sub 2}O{sub 3} system. An emphasis has been laid on varying the reinforcement particle size and evaluating the microstructural morphologies and their implications on mechanical performance of the composites. Nanocomposites of 0.5, 1, 3, 5, 7 volume % alumina (average size < 50 nm) reinforced in aluminium matrix were fabricated by powder metallurgy route using spark plasma sintering technique technique at a temperature of 773 K and pressure of 50 MPa. Another set of specimensmore » having composition 1, 5, 20 vol.% of alumina (average size ∼ 10 μm) had been fabricated to compare the physical as well as mechanical attributes of the microcomposite as well as the nanocomposites. These micro- and nano-composites have been characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy followed by density, microhardness and nanoindentation measurements. The alumina nanoparticles revealed an interface showing appreciable physical intimacy with the aluminium matrix compared to that of the alumina microparticles. The interfacial integrity in case of nanocomposites is better than in the microcomposite which has been studied using microscopic techniques. Spark plasma sintering imparts enhanced densification as well as matrix-reinforcement proximity which has been corroborated with the experimental results. - Highlights: • The Al–Al{sub 2}O{sub 3} micro- and nano-composites fabricated by spark plasma sintering. • Better matrix-reinforcement integrity in nanocomposites than microcomposites. • Spark plasma sintering method results in higher density and hardness values. • High density and hardness values of nanocomposites than microcomposites. • High dislocation density in spark plasma sintered Al–Al{sub 2}O{sub 3} composites. - Abstract: In the present study, an emphasis has been laid on evaluation of the microstructural morphologies and their implications on mechanical performance of the composites by varying the reinforcement particle size. Nanocomposites of 0.5, 1, 3, 5, 7 volume % alumina (average size < 50 nm) and microcomposites of 1, 5, 20 volume % of alumina (average size ∼ 10 μm) reinforced in aluminium matrix were fabricated by spark plasma sintering technique at a temperature of 773 K and pressure of 50 MPa. These micro- and nano-composites have been characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy followed by density, microhardness and nanoindentation hardness measurements. The alumina nanoparticles revealed appreciable physical intimacy with the aluminium matrix than that of alumina microparticles. The highest nanohardness recorded 0.85 GPa and 99% densification for 7 and 1 vol.% Al–Al{sub 2}O{sub 3} nancomposites respectively. Spark plasma sintering imparts enhanced densification and matrix-reinforcement proximity which have been corroborated with the experimental results.« less

Electron-ion hybrid instability experiment upgrades to the Auburn Linear Experiment for Instability Studies.

PubMed

DuBois, A M; Arnold, I; Thomas, E; Tejero, E; Amatucci, W E

2013-04-01

The Auburn Linear EXperiment for Instability Studies (ALEXIS) is a laboratory plasma physics experiment used to study spatially inhomogeneous flows in a magnetized cylindrical plasma column that are driven by crossed electric (E) and magnetic (B) fields. ALEXIS was recently upgraded to include a small, secondary plasma source for a new dual source, interpenetrating plasma experiment. Using two plasma sources allows for highly localized electric fields to be made at the boundary of the two plasmas, inducing strong E × B velocity shear in the plasma, which can give rise to a regime of instabilities that have not previously been studied in ALEXIS. The dual plasma configuration makes it possible to have independent control over the velocity shear and the density gradient. This paper discusses the recent addition of the secondary plasma source to ALEXIS, as well as the plasma diagnostics used to measure electric fields and electron densities.

A Physics Exploratory Experiment on Plasma Liner Formation

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Knapp, Charles E.; Kirkpatrick, Ronald C.; Siemon, Richard E.; Turchi, Peter

2002-01-01

Momentum flux for imploding a target plasma in magnetized target fusion (MTF) may be delivered by an array of plasma guns launching plasma jets that would merge to form an imploding plasma shell (liner). In this paper, we examine what would be a worthwhile experiment to do in order to explore the dynamics of merging plasma jets to form a plasma liner as a first step in establishing an experimental database for plasma-jets driven magnetized target fusion (PJETS-MTF). Using past experience in fusion energy research as a model, we envisage a four-phase program to advance the art of PJETS-MTF to fusion breakeven Q is approximately 1). The experiment (PLX (Plasma Liner Physics Exploratory Experiment)) described in this paper serves as Phase I of this four-phase program. The logic underlying the selection of the experimental parameters is presented. The experiment consists of using twelve plasma guns arranged in a circle, launching plasma jets towards the center of a vacuum chamber. The velocity of the plasma jets chosen is 200 km/s, and each jet is to carry a mass of 0.2 mg - 0.4 mg. A candidate plasma accelerator for launching these jets consists of a coaxial plasma gun of the Marshall type.

Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franz, Robert; Polcik, Peter; Anders, André

The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr 2+ ions were dominating in Ar and N 2 and Cr + in O 2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ionsmore » that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O 2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.« less

Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

DOE PAGES

Franz, Robert; Polcik, Peter; Anders, André

2015-06-01

The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr 2+ ions were dominating in Ar and N 2 and Cr + in O 2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ionsmore » that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O 2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.« less

Preparation of a bonelike apatite-polymer fiber composite using a simple biomimetic process.

PubMed

Yokoyama, Yoshiro; Oyane, Ayako; Ito, Atsuo

2008-08-01

A bonelike apatite-polymer fiber composite may be useful as an implant material to replace bone, the enthesis of a tendon, and the joint part of a ligament. We treated an ethylene-vinyl alcohol copolymer (EVOH) plate and knitted EVOH fibers with an oxygen plasma to produce oxygen-containing functional groups on their surfaces. The plasma-treated samples were alternately dipped in alcoholic calcium and phosphate ion solutions three times to deposit apatite precursors onto their surfaces. The surface-modified samples formed a dense and uniform bonelike surface apatite layer after immersion for 24 h in a simulated body fluid with ion concentrations approximately equal to those of human blood plasma. The adhesive strength between the apatite layer and the sample's surface increased with increasing power density of the oxygen plasma. The apatite-EVOH fiber composite obtained by our process has similarities to natural bone in that apatite crystals are deposited on organic polymer fibers. The resulting composite would possess osteoconductivity due to the apatite phase. With proper polymer selection and optimized synthesis techniques, a composite could be made that would have bonelike mechanical properties. Hence, the present surface modification and coating process would be a promising route to obtain new implant materials with bonelike mechanical properties and osteoconductivity. (c) 2007 Wiley Periodicals, Inc.

Properties of thermal air plasma with admixing of copper and carbon

NASA Astrophysics Data System (ADS)

Fesenko, S.; Veklich, A.; Boretskij, V.; Cressault, Y.; Gleizes, A.; Teulet, Ph

2014-11-01

This paper deals with investigations of air plasma with admixing of copper and carbon. Model plasma source unit with real breaking arc was used for the simulation of real discharges, which can be occurred during sliding of Cu-C composite electrodes on copper wire at electromotive vehicles. The complex technique of plasma property studies is developed. From one hand, the radial profiles of temperature and electron density in plasma of electric arc discharge in air between Cu-C composite and copper electrodes in air flow were measured by optical spectroscopy techniques. From another hand, the radial profiles of electric conductivity of plasma mixture were calculated by solution of energy balance equation. It was assumed that the thermal conductivity of air plasma is not depending on copper or carbon vapor admixtures. The electron density is obtained from electric conductivity profiles by calculation in assumption of local thermodynamic equilibrium in plasma. Computed in such way radial profiles of electron density in plasma of electric arc discharge in air between copper electrodes were compared with experimentally measured profiles. It is concluded that developed techniques of plasma diagnostics can be reasonably used in investigations of thermal plasma with copper and carbon vapors.

Production of Sn/SnO2/MWCNT composites by plasma oxidation after thermal evaporation from pure Sn targets onto buckypapers.

PubMed

Alaf, M; Gultekin, D; Akbulut, H

2012-12-01

In this study, tin/tinoxide/multi oxide/multi walled carbon nano tube (Sn/SnO2/MWCNT) composites were produced by thermal evaporation and then subsequent plasma oxidation. Buckypapers having controlled porosity were prepared by vacuum filtration from functionalized MWCNTs. Pure metallic tin was thermally evaporated on the buckypapers in argon atmosphere with different thicknesses. It was determined that the evaporated pure tin nano crystals were mechanically penetrated into pores of buckypaper to form a nanocomposite. The tin/MWCNT composites were subjected to plasma oxidation process at oxygen/argon gas mixture. Three different plasma oxidation times (30, 45 and 60 minutes) were used to investigate oxidation and physical and microstructural properties. The effect of coating thickness and oxidation time was investigated to understand the effect of process parameters on the Sn and SnO2 phases after plasma oxidation. Quantitative phase analysis was performed in order to determine the relative phase amounts. The structural properties were studied by field-emission gun scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD).

Associations between a fatty acid desaturase gene polymorphism and blood arachidonic acid compositions in Japanese elderly.

PubMed

Horiguchi, Sayaka; Nakayama, Kazuhiro; Iwamoto, Sadahiko; Ishijima, Akiko; Minezaki, Takayuki; Baba, Mamiko; Kontai, Yoshiko; Horikawa, Chika; Kawashima, Hiroshi; Shibata, Hiroshi; Kagawa, Yasuo; Kawabata, Terue

2016-02-01

We investigated whether the single nucleotide polymorphism rs174547 (T/C) of the fatty acid desaturase-1 gene, FADS1, is associated with changes in erythrocyte membrane and plasma phospholipid (PL) long-chain polyunsaturated fatty acid (LCPUFA) composition in elderly Japanese participants (n=124; 65 years or older; self-feeding and oral intake). The rs174547 C-allele carriers had significantly lower arachidonic acid (ARA; n-6 PUFA) and higher linoleic acid (LA, n-6 PUFA precursor) levels in erythrocyte membrane and plasma PL (15% and 6% ARA reduction, respectively, per C-allele), suggesting a low LA to ARA conversion rate in erythrocyte membrane and plasma PL of C-allele carriers. α-linolenic acid (n-3 PUFA precursor) levels were higher in the plasma PL of C-allele carriers, whereas levels of the n-3 LCPUFAs eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) were unchanged in erythrocyte membrane and plasma PL. Thus, rs174547 genotypes were significantly associated with different ARA compositions of the blood of elderly Japanese. Copyright © 2015 Elsevier Ltd. All rights reserved.

Role of red cells and plasma composition on blood sessile droplet evaporation

NASA Astrophysics Data System (ADS)

Lanotte, Luca; Laux, Didier; Charlot, Benoît; Abkarian, Manouk

2017-11-01

The morphology of dried blood droplets derives from the deposition of red cells, the main components of their solute phase. Up to now, evaporation-induced convective flows were supposed to be at the base of red cell distribution in blood samples. Here, we present a direct visualization by videomicroscopy of the internal dynamics in desiccating blood droplets, focusing on the role of cell concentration and plasma composition. We show that in diluted suspensions, the convection is promoted by the rich molecular composition of plasma, whereas it is replaced by an outward red blood cell displacement front at higher hematocrits. We also evaluate by ultrasounds the effect of red cell deposition on the temporal evolution of sample rigidity and adhesiveness.

Scanning probe microscopy for the analysis of composite Ti/hydrocarbon plasma polymer thin films

NASA Astrophysics Data System (ADS)

Choukourov, A.; Grinevich, A.; Slavinska, D.; Biederman, H.; Saito, N.; Takai, O.

2008-03-01

Composite Ti/hydrocarbon plasma polymer films with different Ti concentration were deposited on silicon by dc magnetron sputtering of titanium in an atmosphere of argon and hexane. As measured by Kelvin force microscopy and visco-elastic atomic force microscopy, respectively, surface potential and hardness increase with increasing Ti content. Adhesion force to silicon and to fibrinogen molecules was stronger for the Ti-rich films as evaluated from the AFM force-distance curves. Fibrinogen forms a very soft layer on these composites with part of the protein molecules embedded in the outermost region of the plasma polymer. An increase of the surface charge due to fibrinogen adsorption has been observed and attributed to positively charged αC domains of fibrinogen molecule.

Encapsulated fish oil enriched in alpha-tocopherol alters plasma phospholipid and mononuclear cell fatty acid compositions but not mononuclear cell functions.

PubMed

Yaqoob, P; Pala, H S; Cortina-Borja, M; Newsholme, E A; Calder, P C

2000-03-01

Several studies have reported that dietary fish oil (FO) supplementation alters cytokine production and other functional activities of peripheral blood mononuclear cells (PBMC). However, few of these studies have been placebo controlled and few have related the functional changes to alterations in PBMC fatty acid composition Healthy subjects supplemented their diets with 9 g day-1 of encapsulated placebo oil (3 : 1 mix of coconut and soybean oils), olive oil (OO), safflower oil (SO), evening primrose oil (EPO) or FO [providing 2.1 g eicosapentaenoic acid (EPA) plus 1.1 g docosahexaenoic acid (DHA) per day] for 12 weeks; the capsules also provided 205 mg alpha-tocopherol per day. Blood was sampled at 4-weekly intervals and plasma and PBMC prepared. Plasma phospholipid and PBMC fatty acid composition, plasma alpha-tocopherol and thiobarbituric acid-reactive substance concentrations, plasma total antioxidant capacity, the proportions of different PBMC subsets, the proportions of PBMC expressing the adhesion molecules CD2, CD11b and CD54, and PBMC functions (lymphocyte proliferation, natural killer cell activity, cytokine production) were measured. All measurements were repeated after a 'washout' period of 8 weeks. The placebo, OO and SO capsules had no effect on plasma phospholipid or PBMC fatty acid composition. The proportion of dihomo-gamma-linolenic acid in plasma phospholipids was elevated in subjects taking EPO and was decreased in subjects taking FO. There was no appearance of gamma-linolenic acid in the plasma phospholipids or PBMC in subjects taking EPO. There was a marked increase in the proportion of EPA in the plasma phospholipids (10-fold) and PBMC (four-fold) of subjects taking FO supplements; this increase was maximal after 4 weeks of supplementation. There was an increase in the proportion of DHA in plasma phospholipids and PBMC, and an approximately 20% decrease in the proportion of arachidonic acid in plasma phospholipids and PBMC, during FO supplementation. Plasma concentrations of alpha-tocopherol were significantly elevated during supplementation in all subjects and returned to baseline values after the washout period. There were no effects of supplementation with any of the capsules on total plasma antioxidant activity or plasma thiobarbituric acid-reactive substances or on the proportion of different PBMC subsets, on the proportion of PBMC expressing adhesion molecules, on natural killer cell activity, on the proliferation of mitogen-stimulated whole blood cultures or PBMC, or on the ex vivo production of a range of cytokines by whole blood cultures or PBMC cultures stimulated by either concanavalin A or lipopolysaccharide. Supplementation of the diet with 3.2 g EPA plus DHA per day markedly alters plasma phospholipid and PBMC fatty acid compositions. The lack of effect of FO upon PBMC functions may relate to the level of alpha-tocopherol included in the supplements.

plasmatis Center for Innovation Competence: Controlling reactive component output of atmospheric pressure plasmas in plasma medicine

NASA Astrophysics Data System (ADS)

Reuter, Stephan

2012-10-01

The novel approach of using plasmas in order to alter the local chemistry of cells and cell environment presents a significant development in biomedical applications. The plasmatis center for innovation competence at the INP Greifswald e.V. performs fundamental research in plasma medicine in two interdisciplinary research groups. The aim of our plasma physics research group ``Extracellular Effects'' is (a) quantitative space and time resolved diagnostics and modelling of plasmas and liquids to determine distribution and composition of reactive species (b) to control the plasma and apply differing plasma source concepts in order to produce a tailored output of reactive components and design the chemical composition of the liquids/cellular environment and (c) to identify and understand the interaction mechanisms of plasmas with liquids and biological systems. Methods to characterize the plasma generated reactive species from plasma-, gas- and liquid phase and their biological effects will be presented. The diagnostic spectrum ranges from absorption/emission/laser spectroscopy and molecular beam mass spectrometry to electron paramagnetic resonance spectroscopy and cell biological diagnostic techniques. Concluding, a presentation will be given of the comprehensive approach to plasma medicine in Greifswald where the applied and clinical research of the Campus PlasmaMed association is combined with the fundamental research at plasmatis center.

Development of the symmetrical laser shock test for weak bond inspection.

NASA Astrophysics Data System (ADS)

Sagnard, Maxime; Berthe, Laurent; Ecault, Romain; Touchard, Fabienne; Boustie, Michel

2017-06-01

This paper presents the LAser Shock Adhesion Test (LASAT) using symmetrical laser shocks. The study is part of ComBoNDT European project that develops new Non-Destructive Tests (NDT) to assess adherence properties of bonded composite structures. This NDT technique relies on the creation of a plasma on both side of the sample using two lasers. The plasma expands and generates shockwaves inside the material. When combined, the shockwaves create a local tensile strength. Properly set, this stress can be used to test interfaces adherence. Numerous experiments have shown that this adaptive technique can discriminate a good bond from a weak one, without damaging the composite structure. Weak bonds are usually created by contaminated surfaces (residues of release agent, finger prints, ...) and were artificially recreated for ComBoNDT test samples. Numerical simulations are being developed as well, to improve the comprehension of the physical phenomenon. And ultimately, using these numerical results, one should be able to find the correct laser parameters (intensity, laser spot diameter) to generate the right tensile strength at the desired location. This project has received funding from the European Union's Horizon 2020 research and innovation program under Grant agreement N 63649.

X-ray diffraction analysis of hydroxyapatite-coated in different plasma gas atmosphere on Ti and Ti-6Al-4V

PubMed Central

Kotian, Ravindra; Rao, P. Prasad; Madhyastha, Prashanthi

2017-01-01

Objective: The aim is to study the effect of plasma working gas on composition, crystallinity, and microstructure of hydroxyapatite (HA) coated on Ti and Ti-6Al-4V metal substrates. Materials and Methods: Ti and Ti-6Al-4V metal substrates were coated with HA by plasma spray using four plasma gas atmospheres of argon, argon/hydrogen, nitrogen, and nitrogen/hydrogen. The degree of crystallinity, the phases present, and microstructure of HA coating were characterized using X-ray diffraction and scanning electron microscopy. Results: Variation in crystallinity and the microstructure of HA coating on plasma gas atmosphere was observed. Micro-cracks due to thermal stresses and shift in the 2θ angle of HA compared to feedstock was seen. Conclusion: Plasma gas atmosphere has a significant influence on composition, crystallinity, and micro-cracks of HA-coated dental implants. PMID:29279668

Effect of therapeutic concentration of lithium on live HEK293 cells; increase of Na+/K+-ATPase, change of overall protein composition and alteration of surface layer of plasma membrane.

PubMed

Vosahlikova, Miroslava; Ujcikova, Hana; Chernyavskiy, Oleksandr; Brejchova, Jana; Roubalova, Lenka; Alda, Martin; Svoboda, Petr

2017-05-01

The effect of long-term exposure of live cells to lithium cations (Li) was studied in HEK293 cells cultivated in the presence of 1mM LiCl for 7 or 21days. The alteration of Na + /K + -ATPase level, protein composition and biophysical state of plasma membrane was determined with the aim to characterize the physiological state of Li-treated cells. Na + /K + -ATPase level was determined by [ 3 H]ouabain binding and immunoblot assays. Overall protein composition was determined by 2D electrophoresis followed by proteomic analysis by MALDI-TOF MS/MS and LFQ. Li interaction with plasma membrane was characterized by fluorescent probes DPH, TMA-DPH and Laurdan. Na + /K + -ATPase was increased in plasma membranes isolated from cells exposed to Li. Identification of Li-altered proteins by 2D electrophoresis, MALDI-TOF MS/MS and LFQ suggests a change of energy metabolism in mitochondria and cytosol and alteration of cell homeostasis of calcium. Measurement of Laurdan generalized polarization indicated a significant alteration of surface layer of isolated plasma membranes prepared from both types of Li-treated cells. Prolonged exposure of HEK293 cells to 1mM LiCl results in up-regulation of Na + /K + -ATPase expression, reorganization of overall cellular metabolism and alteration of the surface layer/polar head-group region of isolated plasma membranes. Our findings demonstrate adaptation of live HEK293 cell metabolism to prolonged exposure to therapeutic concentration of Li manifested as up-regulation of Na + /K + -ATPase expression, alteration of protein composition and change of the surface layer of plasma membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

Photon calorimeter

DOEpatents

Chow, Tze-Show

1988-04-22

A photon calorimeter is provided that comprises a laminar substrate that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating, that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions, are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly. 4 figs.

Effect of Electron Beam Freeform Fabrication (EBF3) Processing Parameters on Composition of Ti-6-4

NASA Technical Reports Server (NTRS)

Lach, Cynthia L.; Taminger, Karen; Schuszler, A. Bud, II; Sankaran, Sankara; Ehlers, Helen; Nasserrafi, Rahbar; Woods, Bryan

2007-01-01

The Electron Beam Freeform Fabrication (EBF3) process developed at NASA Langley Research Center was evaluated using a design of experiments approach to determine the effect of processing parameters on the composition and geometry of Ti-6-4 deposits. The effects of three processing parameters: beam power, translation speed, and wire feed rate, were investigated by varying one while keeping the remaining parameters constant. A three-factorial, three-level, fully balanced mutually orthogonal array (L27) design of experiments approach was used to examine the effects of low, medium, and high settings for the processing parameters on the chemistry, geometry, and quality of the resulting deposits. Single bead high deposits were fabricated and evaluated for 27 experimental conditions. Loss of aluminum in Ti-6-4 was observed in EBF3 processing due to selective vaporization of the aluminum from the sustained molten pool in the vacuum environment; therefore, the chemistries of the deposits were measured and compared with the composition of the initial wire and base plate to determine if the loss of aluminum could be minimized through careful selection of processing parameters. The influence of processing parameters and coupling between these parameters on bulk composition, measured by Direct Current Plasma (DCP), local microchemistries determined by Wavelength Dispersive Spectrometry (WDS), and deposit geometry will also be discussed.

The Giotto electron plasma experiment

NASA Technical Reports Server (NTRS)

Reme, H.; Cotin, F.; Cros, A.; Medale, J. L.; Sauvaud, J. A.

1987-01-01

The RPA-Copernic experiment aboard Giotto is described. The experiment is designed to measure the three-dimensional distributions of electrons between 10 eV and 30 keV (by the RPA-1 EESA spectrometer) and the composition and distribution, close to the comet, of thermal positive ions in the mass range 10-213 amu (by the RPA-2 PICCA electrostatic mass analyzer). Three microprocessors interface RPA-1 EESA with RPA-2 PICCA and with the spacecraft and perform extensive onboard data processing. The experiment was operated successfully aboard the spacecraft in September 1985 during the encounter of Giotto with the comet Halley. The results provided by the EESA-1 indicate that the solar wind interaction with the comet Halley forms a well-defined bow shock with features quite different from the features of the comet Giacobini-Zinner bow shock; the data also showed a presence of accelerated keV electrons at the cometary bow shock, upstream and in the transition region.

Identification of Interplanetary Coronal Mass Ejections at 1 AU Using Multiple Solar Wind Plasma Composition Anomalies

NASA Technical Reports Server (NTRS)

Richardson, I. G.; Cane, H. V.

2004-01-01

We investigate the use of multiple simultaneous solar wind plasma compositional anomalies, relative to the composition of the ambient solar wind, for identifying interplanetary coronal mass ejection (ICME) plasma. We first summarize the characteristics of several solar wind plasma composition signatures (O(+7)/O(+6), Mg/O, Ne/O, Fe charge states, He/p) observed by the ACE and WIND spacecraft within the ICMEs during 1996 - 2002 identsed by Cane and Richardson. We then develop a set of simple criteria that may be used to identify such compositional anomalies, and hence potential ICMEs. To distinguish these anomalies from the normal variations seen in ambient solar wind composition, which depend on the wind speed, we compare observed compositional signatures with those 'expected' in ambient solar wind with the same solar wind speed. This method identifies anomalies more effectively than the use of fixed thresholds. The occurrence rates of individual composition anomalies within ICMEs range from approx. 70% for enhanced iron and oxygen charge states to approx. 30% for enhanced He/p (> 0.06) and Ne/O, and are generally higher in magnetic clouds than other ICMEs. Intervals of multiple anomalies are usually associated with ICMEs, and provide a basis for the identification of the majority of ICMEs. We estimate that Cane and Richardson, who did not refer to composition data, probably identitied approx. 90% of the ICMEs present. However, around 10% of their ICMEs have weak compositional anomalies, suggesting that the presence of such signatures does not provide a necessary requirement for an ICME. We note a remarkably similar correlation between the Mg/O and O(7)/O(6) ratios in hourly-averaged data both within ICMEs and the ambient solar wind. This 'universal' relationship suggests that a similar process (such as minor ion heating by waves inside coronal magnetic field loops) produces the first-ionization potential bias and ion freezing-in temperatures in the source regions of both ICMEs and the ambient solar wind.

Thermodynamic properties and transport coefficients of two-temperature helium thermal plasmas

NASA Astrophysics Data System (ADS)

Guo, Xiaoxue; Murphy, Anthony B.; Li, Xingwen

2017-03-01

Helium thermal plasmas are in widespread use in arc welding and many other industrial applications. Simulation of these processes relies on accurate plasma property data, such as plasma composition, thermodynamic properties and transport coefficients. Departures from LTE (local thermodynamic equilibrium) generally occur in some regions of helium plasmas. In this paper, properties are calculated allowing for different values of the electron temperature, T e, and heavy-species temperature, T h, at atmospheric pressure from 300 K to 30 000 K. The plasma composition is first calculated using the mass action law, and the two-temperature thermodynamic properties are then derived. The viscosity, diffusion coefficients, electrical conductivity and thermal conductivity of the two-temperature helium thermal plasma are obtained using a recently-developed method that retains coupling between electrons and heavy species by including the electron-heavy-species collision term in the heavy-species Boltzmann equation. It is shown that the viscosity and the diffusion coefficients strongly depend on non-equilibrium ratio θ (θ ={{T}\\text{e}}/{{T}\\text{h}} ), through the plasma composition and the collision integrals. The electrical conductivity, which depends on the electron number density and ordinary diffusion coefficients, and the thermal conductivity have similar dependencies. The choice of definition of the Debye length is shown to affect the electrical conductivity significantly for θ  >  1. By comparing with literature data, it is shown that the coupling between electrons and heavy species has a significant influence on the electrical conductivity, but not on the viscosity. Plasma properties are tabulated in the supplementary data.

Effects of gas temperature in the plasma layer on RONS generation in array-type dielectric barrier discharge at atmospheric pressure

NASA Astrophysics Data System (ADS)

Yoon, Sung-Young; Yi, Changho; Eom, Sangheum; Park, Seungil; Kim, Seong Bong; Ryu, Seungmin; Yoo, Suk Jae

2017-12-01

In this work, we studied the control of plasma-produced species under a fixed gas composition (i.e., ambient air) in a 10 kHz-driven array-type dielectric barrier atmospheric-pressure plasma discharge. Instead of the gas composition, only the gas velocity was controlled. Thus, the plasma-maintenance cost was considerably lower than methods such as external N2 or O2 injection. The plasma-produced species were monitored using Fourier transformed infrared spectroscopy. The discharge properties were measured using a voltage probe, current probe, infrared camera, and optical emission spectroscopy. The results showed that the major plasma products largely depend on the gas temperature in the plasma discharge layer. The gas temperature in the plasma discharge layer was significantly different to the temperature of the ceramic adjacent to the plasma discharge layer, even in the small discharge power density of ˜15 W/cm2 or ˜100 W/cm3. Because the vibrational excitation of N2 was suppressed by the higher gas flow, the major plasma-produced species shifted from NOx in low flow to O3 in high flow.

Differences in the protein composition of bovine retinal rod outer segment disk and plasma membranes isolated by a ricin-gold-dextran density perturbation method

PubMed Central

1987-01-01

The plasma membrane and disk membranes of bovine retinal rod outer segments (ROS) have been purified by a novel density-gradient perturbation method for analysis of their protein compositions. Purified ROS were treated with neuraminidase to expose galactose residues on plasma membrane-specific glycoproteins and labeled with ricin-gold-dextran particles. After the ROS were lysed in hypotonic buffer, the plasma membrane was dissociated from the disks by either mild trypsin digestion or prolonged exposure to low ionic strength buffer. The dense ricin-gold-dextran-labeled plasma membrane was separated from disks by sucrose gradient centrifugation. Electron microscopy was used to follow this fractionation procedure. The dense red pellet primarily consisted of inverted plasma membrane vesicles containing gold particles; the membrane fraction of density 1.13 g/cc consisted of unlabeled intact disks and vesicles. Ricin-binding studies indicated that the plasma membrane from trypsin-treated ROS was purified between 10-15-fold. The protein composition of plasma membranes and disks was significantly different as analyzed by SDS gels and Western blots labeled with lectins and monoclonal antibodies. ROS plasma membrane exhibited three major proteins of 36 (rhodopsin), 38, and 52 kD, three ricin-binding glycoproteins of 230, 160, and 110 kD, and numerous minor proteins in the range of 14-270 kD. In disk membranes rhodopsin appeared as the only major protein. A 220-kD concanavalin A-binding glycoprotein and peripherin, a rim-specific protein, were also present along with minor proteins of 43 and 57-63 kD. Radioimmune assays indicated that the ROS plasma membrane contained about half as much rhodopsin as disk membranes. PMID:2447095

Assessing the electrochemical performance of a supercapacitor electrode made of copper oxide and activated carbon using liquid phase plasma

NASA Astrophysics Data System (ADS)

Ki, Seo Jin; Lee, Heon; Park, Young-Kwon; Kim, Sun-Jae; An, Kay-Hyeok; Jung, Sang-Chul

2018-07-01

Successful modification of surface properties of a nanocomposite electrode is prerequisite to enhancing the overall performance of electrochemical supercapacitors. The present study was designed to describe the microstructural and electrochemical characteristics of a new composite electrode assembled by activated carbon (AC) powder (as a host) and copper precursor (as a guest) using liquid phase plasma. The fabrication processes were conducted by changing plasma discharge time from 30 to 90 min in the presence and absence of (thermal) oxidation. We observed that merging plasma and oxidation treatments raised the content of copper oxide nanoparticles precipitated (evenly) on the AC surface, along with oxygen. A mixed valence state of copper oxides (in the forms of Cuo, Cu2O, and CuO) was found in different composites with and without oxidation, where CuO and Cuo affected a specific capacitance in positive and negative ways, respectively. This led to the difference of electrochemical stability and resistance among the assembled composites. For instance, the best cycling performance was observed in the plasma-treated composite for 90 min with oxidation, whereas that of 60 min without oxidation recorded the lowest resistance. Therefore, a proper balance between the capacitance and resistance appears to be required for effective fabrication of the supercapacitor electrode, specifically in cases involving copper oxides.

Plasma methods of obtainment of multifunctional composite materials, dispersion-hardened by nanoparticles

NASA Astrophysics Data System (ADS)

Sizonenko, O. N.; Grigoryev, E. G.; Zaichenko, A. D.; Pristash, N. S.; Torpakov, A. S.; Lipyan, Ye V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.

2016-04-01

The new approach in developed plasma methods consists in that dispersionhardening additives (TiC, TiB2 in particular) are not mechanically added to powder mixture as additional component, as in conventional methods, but are instead synthesized during high voltage electric discharges (HVED) in disperse system “hydrocarbon liquid - powder” preservation of ultrafine structure is ensured due to use of spark plasma sintering (SPS) as a consolidation method. HVED in disperse system “hydrocarbon liquid - powder” due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. SPS is the passage of pulsed current (superposition of direct and alternating current) through powder with the simultaneous mechanical compressing. The formation of plasma is initiated in gaseous phase that fills gaps between particles. SPS allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10 - 20%), hardness and wear-resistance (by 30 - 60%) of obtained materials.

Ceramic thermal barrier coatings for commercial gas turbine engines

NASA Technical Reports Server (NTRS)

Meier, Susan Manning; Gupta, Dinesh K.; Sheffler, Keith D.

1991-01-01

The paper provides an overview of the short history, current status, and future prospects of ceramic thermal barrier coatings for gas turbine engines. Particular attention is given to plasma-sprayed and electron beam-physical vapor deposited yttria-stabilized (7 wt pct Y2O3) zirconia systems. Recent advances include improvements in the spallation life of thermal barrier coatings, improved bond coat composition and spraying techniques, and improved component design. The discussion also covers field experience, life prediction modeling, and future directions in ceramic coatings in relation to gas turbine engine design.

Experimental results of near real-time protection system for plasma facing components in Wendelstein 7-X at GLADIS

NASA Astrophysics Data System (ADS)

Ali, A.; Jakubowski, M.; Greuner, H.; Böswirth, B.; Moncada, V.; Sitjes, A. Puig; Neu, R.; Pedersen, T. S.; the W7-X Team

2017-12-01

One of the aims of stellarator Wendelstein 7-X (W7-X), is to investigate steady state operation, for which power exhaust is an important issue. The predominant fraction of the energy lost from the confined plasma region will be absorbed by an island divertors, which is designed for 10 {{MWm}}-2 steady state operation. In order to protect the divertor targets from overheating, 10 state-of-the-art infrared endoscopes will be installed at W7-X. In this work, we present the experimental results obtained at the high heat flux test facility GLADIS (Garching LArge DIvertor Sample test facility in IPP Garching) [1] during tests of a new plasma facing components (PFCs) protection algorithm designed for W7-X. The GLADIS device is equipped with two ion beams that can generate a heat load in the range from 3 MWm-2 to 55 MWm-2. The algorithms developed at W7-X to detect defects and hot spots are based on the analysis of surface temperature evolution and are adapted to work in near real-time. The aim of this work was to test the near real-time algorithms in conditions close to those expected in W7-X. The experiments were performed on W7-X pre-series tiles to detect CFC/Cu delaminations. For detection of surface layers, carbon fiber composite (CFC) blocks from the divertor of the Wendelstein 7-AS stellarator were used to observe temporal behavior of fully developed surface layers. These layers of re-deposited materials, like carbon, boron, oxygen and iron, were formed during the W7-AS operation. A detailed analysis of the composition and their thermal response to high heat fluxes (HHF) are described in [2]. The experiments indicate that the automatic detection of critical events works according to W7-X PFC protection requirements.

Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process.

PubMed

Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

2017-11-25

The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

Characterization of Ni-YSZ anodes for solid oxide fuel cells fabricated by suspension plasma spraying with axial feedstock injection

NASA Astrophysics Data System (ADS)

Metcalfe, Craig; Kuhn, Joel; Kesler, Olivera

2013-12-01

Composite Ni-Y0.15Zr0.85O1.925 anodes were fabricated by axial-injection suspension plasma spraying in open atmosphere conditions. The composition of the anode is controllable by adjustment of the plasma gas composition, stand-off distance, and suspension feed rate. The total porosity is controllable through the addition of carbon black to the suspension as a sacrificial pore-forming material as well as by adjustment of the suspension feed rate. The size of the NiO particles in suspension affects both the composition and total porosity, with larger NiO particles leading to increased Ni content and porosity in the deposited coatings. The surface roughness increases with a decrease of the in-flight droplet momentum, which results from both smaller NiO particles in suspension and the addition of low density pore-forming materials. A solid oxide fuel cell was fabricated with both electrodes and electrolyte fabricated by axial-injection plasma spraying. Peak power densities of 0.718 W cm-2 and 1.13 W cm-2 at 750 °C and 850 °C, respectively, were achieved.

Effects of active flux on plasma behavior and weld shape in laser welding of X5CrNi189 stainless steel

NASA Astrophysics Data System (ADS)

Dai, Hongbin; Peng, Jun

2016-11-01

In this paper, stainless steel was welded by active flux-aided laser welding method. The effects of single active flux (Cr2O3, SiO2 and TiO2) and composite active flux on laser welding were studied. In the welding process, laser plasma behavior was recorded by a high-speed imaging system. The results show that, with the addition of active flux, the absorption of laser energy and melting efficiency increase. In the laser power of 750 W, effects of active flux on weld depth to width ratio are given by the order: composite active flux > SiO2 > Cr2O3 > TiO2. The effect of composite active flux is the most significant and it can increase the weld depth to width ratio to 85%. Active flux can restrict the laser plasma. With the addition of composite active flux, the projected area of laser plasma obtained obviously reduced, and it can be reduced by 41.39%. Active flux cannot obviously change the main components in weld zone, but can change the grains of austenite and ferrite.

Electron-Beam Atomic Spectroscopy for In Situ Measurements of Melt Composition for Refractory Metals: Analysis of Fundamental Physics and Plasma Models

NASA Astrophysics Data System (ADS)

Gasper, Paul Joseph; Apelian, Diran

2015-04-01

Electron-beam (EB) melting is used for the processing of refractory metals, such as Ta, Nb, Mo, and W. These metals have high value and are critical to many industries, including the semiconductor, aerospace, and nuclear industries. EB melting can also purify secondary feedstock, enabling the recovery and recycling of these materials. Currently, there is no method for measuring melt composition in situ during EB melting. Optical emission spectroscopy of the plasma generated by EB impact with vapor above the melt, a technique here termed electron-beam atomic spectroscopy, can be used to measure melt composition in situ, allowing for analysis of melt dynamics, facilitating improvement of EB melting processes and aiding recycling and recovery of these critical and high-value metals. This paper reviews the physics of the plasma generation by EB impact by characterizing the densities and energies of electrons, ions, and neutrals, and describing the interactions between them. Then several plasma models are introduced and their suitability to this application analyzed. Lastly, a potential method for calibration-free composition measurement is described and the challenges for implementation addressed.

Plasma etching a ceramic composite. [evaluating microstructure

NASA Technical Reports Server (NTRS)

Hull, David R.; Leonhardt, Todd A.; Sanders, William A.

1992-01-01

Plasma etching is found to be a superior metallographic technique for evaluating the microstructure of a ceramic matrix composite. The ceramic composite studied is composed of silicon carbide whiskers (SiC(sub W)) in a matrix of silicon nitride (Si3N4), glass, and pores. All four constituents are important in evaluating the microstructure of the composite. Conventionally prepared samples, both as-polished or polished and etched with molten salt, do not allow all four constituents to be observed in one specimen. As-polished specimens allow examination of the glass phase and porosity, while molten salt etching reveals the Si3N4 grain size by removing the glass phase. However, the latter obscures the porosity. Neither technique allows the SiC(sub W) to be distinguished from the Si3N4. Plasma etching with CF4 + 4 percent O2 selectively attacks the Si3N4 grains, leaving SiC(sub W) and glass in relief, while not disturbing the pores. An artifact of the plasma etching reaction is the deposition of a thin layer of carbon on Si3N4, allowing Si3N4 grains to be distinguished from SiC(sub W) by back scattered electron imaging.

Formation of Plasma Around a Small Meteoroid: Simulation and Theory

NASA Astrophysics Data System (ADS)

Sugar, G.; Oppenheim, M. M.; Dimant, Y. S.; Close, S.

2018-05-01

High-power large-aperture radars detect meteors by reflecting radio waves off dense plasma that surrounds a hypersonic meteoroid as it ablates in the Earth's atmosphere. If the plasma density profile around the meteoroid is known, the plasma's radar cross section can be used to estimate meteoroid properties such as mass, density, and composition. This paper presents head echo plasma density distributions obtained via two numerical simulations of a small ablating meteoroid and compares the results to an analytical solution found in Dimant and Oppenheim (2017a, https://doi.org/10.1002/2017JA023960, 2017b, https://doi.org/10.1002/2017JA023963). The first simulation allows ablated meteoroid particles to experience only a single collision to match an assumption in the analytical solution, while the second is a more realistic simulation by allowing multiple collisions. The simulation and analytical results exhibit similar plasma density distributions. At distances much less than λT, the average distance an ablated particle travels from the meteoroid before a collision with an atmospheric particle, the plasma density falls off as 1/R, where R is the distance from the meteoroid center. At distances substantially greater than λT, the plasma density profile has an angular dependence, falling off as 1/R2 directly behind the meteoroid, 1/R3 in a plane perpendicular to the meteoroid's path that contains the meteoroid center, and exp[-1.5(R/λT2/3)]/R in front of the meteoroid. When used for calculating meteoroid masses, this new plasma density model can give masses that are orders of magnitude different than masses calculated from a spherically symmetric Gaussian distribution, which has been used to calculate masses in the past.

Mineral-Based Coating of Plasma-Treated Carbon Fibre Rovings for Carbon Concrete Composites with Enhanced Mechanical Performance.

PubMed

Schneider, Kai; Lieboldt, Matthias; Liebscher, Marco; Fröhlich, Maik; Hempel, Simone; Butler, Marko; Schröfl, Christof; Mechtcherine, Viktor

2017-03-29

Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving.

Mineral-Based Coating of Plasma-Treated Carbon Fibre Rovings for Carbon Concrete Composites with Enhanced Mechanical Performance

PubMed Central

Schneider, Kai; Lieboldt, Matthias; Liebscher, Marco; Fröhlich, Maik; Hempel, Simone; Butler, Marko; Schröfl, Christof; Mechtcherine, Viktor

2017-01-01

Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving. PMID:28772719

Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability.

PubMed

Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong

2003-08-15

Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.

Spatial-temporal diagnostics of the system of a plasma stream interacting with a surface of heat resistant material

NASA Astrophysics Data System (ADS)

Chinnov, V. F.; Sargsyan, M. A.; Gadzhiev, M. Kh; Khromov, M. A.; Kavyrshin, D. I.; Chistolinov, A. V.

2018-01-01

In an automated measuring complex using optical and spectral methods the spatial and temporal changes in the parameters and composition of nitrogen plasma jet were investigated. The plasma jet was flowing out of the nozzle of the plasma torch with 10-12 kK temperature and acting on the sample of MPG-6 graphite. Due to the heating of the sample to the temperatures of 2.5-3 kK the influence of the sublimating material of the sample on the plasma composition and temperature in the near-surface region of the sample was investigated. An original method based on the analysis of movement of optical inhomogeneities in the plasma flow was used to estimate the plasma jet velocity in the region where it interacts with the sample. The combined analysis of the results of two-positioning video recordings opens up the possibility of determining spatial-temporal distributions of the plasma jet velocities, in medium and high pressure environments, in the ranges from few to thousands of m/s and 3-15 kK temperatures.

Kinetics and Chemistry of Ionization Wave Discharges Propagating Over Dielectric Surfaces

NASA Astrophysics Data System (ADS)

Petrishchev, Vitaly

Experimental studies of near-surface ionization wave electric discharges generated by high peak voltage (20-30 kV), nanosecond duration pulses (full width at half-maximum 50-100 ns) of positive and negative polarity and propagating over dielectric surfaces have been performed. A novel way to sustain diffuse, reproducible, ns pulse surface plasmas at a liquid-vapor interface is demonstrated at buffer gas pressures ranging from 10 to 200 Torr. Generation of surface ionization waves well reproduced shot-to-shot and sustaining diffuse near-surface plasmas is one of the principal advantages of the use of ns pulse discharge waveforms. This makes possible characterization of these plasmas in repetitively pulsed experiments. Numerous applications of these plasmas include low-temperature plasma assisted combustion, plasma fuel reforming, plasma flow control, plasma materials processing, agriculture, biology, and medicine. The objectives of the present work are (i) to demonstrate that surface ionization wave discharge plasmas sustained at a liquid-vapor interface can be used as an experimental platform for studies of near-surface plasma chemical reaction kinetics, at the conditions when the interface acts as a high-yield source of radical species, and (ii) to obtain quantitative insight into dynamics, kinetics and chemistry of surface ionization wave discharges and provide experimental data for validation of kinetic models, to assess their predictive capability. Generation of the initial radical pool may trigger a number of plasma chemical processes leading to formation of a variety of stable product species, depending on the initial composition of the liquid and the buffer gas flow. One of the products formed and detected during surface plasma / liquid water interaction is hydroxyl radical, which is closely relevant to applications of plasmas for biology and medicine. The present work includes detailed studies of surface ionization wave discharges sustained in different buffer gases over solid and liquid dielectric surfaces, such as quartz, distilled water, saline solution, and alcohols, over a wide range of pressures. Specific experiments include: measurements of ionization wave speed; plasma emission imaging using a ns gate camera; detection of surface discharge plasma chemistry products using Fourier transform infrared absorption spectroscopy; surface charge dynamics on short (ns) and long (hundreds of mus) time scales; time-resolved electron density and electron temperature measurements in a ns pulse surface discharge in helium by Thomson scattering; spatially-resolved absolute OH and H atom concentration measurements in ns pulse discharges over distilled water by single-photon and two-photon Laser Induced Fluorescence; and schlieren imaging of perturbations generated by a ns pulse dielectric barrier discharge in a surface plasma actuator in quiescent atmospheric pressure air.

The effect of lanthanum on the fabrication of ZrB{sub 2}-ZrC composites by spark plasma sintering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Kyoung Hun; Shim, Kwang Bo

2003-01-15

The effect of the addition of the rare earth element, lanthanum, on the sintering characteristics of ZrB{sub 2}-ZrC composites has been analyzed during a spark plasma sintering (SPS) process. Microscopic observation confirmed that lanthanum accelerated mass transport by the formation of the liquid phase between the particles induced by the spark plasma in the initial stage of the SPS process, and then these were recrystallized to form a lanthanum-containing secondary phase at the grain boundaries and at the grain boundary triple junctions. In spite of the strong covalent bonding characteristics of the ZrB{sub 2}-ZrC composite there are many well-developed dislocationmore » structures observed. The fracture toughness of the lanthanum-containing ZrB{sub 2}-ZrC is about 2.56 MPa m{sup 1/2}, which is comparable to that of the pure composite. Therefore, it is concluded that lanthanum is very effective as a sintering aid for the ZrB{sub 2}-ZrC composite without any degradation of the mechanical properties.« less

Microwave plasma synthesis of Si/Ge and Si/WSi2 nanoparticles for thermoelectric applications

NASA Astrophysics Data System (ADS)

Petermann, Nils; Schneider, Tom; Stötzel, Julia; Stein, Niklas; Weise, Claudia; Wlokas, Irenäus; Schierning, Gabi; Wiggers, Hartmut

2015-08-01

The utilization of microwave-based plasma systems enables a contamination-free synthesis of highly specific nanoparticles in the gas phase. A reactor setup allowing stable, long-term operation was developed with the support of computational fluid dynamics. This paper highlights the prospects of gas-phase plasma synthesis to produce specific materials for bulk thermoelectrics. Taking advantage of specific plasma reactor properties such as Coulomb repulsion in combination with gas temperatures considerably higher than 1000 K, spherical and non-aggregated nanoparticles of multiple compositions are accessible. Different strategies towards various nanostructured composites and alloys are discussed. It is shown that, based on doped silicon/germanium alloys and composites, thermoelectric materials with zT values up to almost unity can be synthesized in one step. First experimental results concerning silicon/tungsten silicide thermoelectrics applying the nanoparticle-in-alloy idea are presented indicating that this concept might work. However, it is found that tungsten silicides show a surprising sinter activity more than 1000 K below their melting temperature.

Changes in plasma membrane lipids, aquaporins and proton pump of broccoli roots, as an adaptation mechanism to salinity.

PubMed

López-Pérez, Luis; Martínez-Ballesta, María Del Carmen; Maurel, Christophe; Carvajal, Micaela

2009-03-01

Salinity stress is known to modify the plasma membrane lipid and protein composition of plant cells. In this work, we determined the effects of salt stress on the lipid composition of broccoli root plasma membrane vesicles and investigated how these changes could affect water transport via aquaporins. Brassica oleracea L. var. Italica plants treated with different levels of NaCl (0, 40 or 80mM) showed significant differences in sterol and fatty acid levels. Salinity increased linoleic (18:2) and linolenic (18:3) acids and stigmasterol, but decreased palmitoleic (16:1) and oleic (18:1) acids and sitosterol. Also, the unsaturation index increased with salinity. Salinity increased the expression of aquaporins of the PIP1 and PIP2 subfamilies and the activity of the plasma membrane H(+)-ATPase. However, there was no effect of NaCl on water permeability (P(f)) values of root plasma membrane vesicles, as determined by stopped-flow light scattering. The counteracting changes in lipid composition and aquaporin expression observed in NaCl-treated plants could allow to maintain the membrane permeability to water and a higher H(+)-ATPase activity, thereby helping to reduce partially the Na(+) concentration in the cytoplasm of the cell while maintaining water uptake via cell-to-cell pathways. We propose that the modification of lipid composition could affect membrane stability and the abundance or activity of plasma membrane proteins such as aquaporins or H(+)-ATPase. This would provide a mechanism for controlling water permeability and for acclimation to salinity stress.

Information-theoretic measures of hydrogen-like ions in weakly coupled Debye plasmas

NASA Astrophysics Data System (ADS)

Zan, Li Rong; Jiao, Li Guang; Ma, Jia; Ho, Yew Kam

2017-12-01

Recent development of information theory provides researchers an alternative and useful tool to quantitatively investigate the variation of the electronic structure when atoms interact with the external environment. In this work, we make systematic studies on the information-theoretic measures for hydrogen-like ions immersed in weakly coupled plasmas modeled by Debye-Hückel potential. Shannon entropy, Fisher information, and Fisher-Shannon complexity in both position and momentum spaces are quantified in high accuracy for the hydrogen atom in a large number of stationary states. The plasma screening effect on embedded atoms can significantly affect the electronic density distributions, in both conjugate spaces, and it is quantified by the variation of information quantities. It is shown that the composite quantities (the Shannon entropy sum and the Fisher information product in combined spaces and Fisher-Shannon complexity in individual space) give a more comprehensive description of the atomic structure information than single ones. The nodes of wave functions play a significant role in the changes of composite information quantities caused by plasmas. With the continuously increasing screening strength, all composite quantities in circular states increase monotonously, while in higher-lying excited states where nodal structures exist, they first decrease to a minimum and then increase rapidly before the bound state approaches the continuum limit. The minimum represents the most reduction of uncertainty properties of the atom in plasmas. The lower bounds for the uncertainty product of the system based on composite information quantities are discussed. Our research presents a comprehensive survey in the investigation of information-theoretic measures for simple atoms embedded in Debye model plasmas.

Effect of composition gradient on magnetothermal instability modified by shear and rotation

NASA Astrophysics Data System (ADS)

Gupta, Himanshu; Chaudhuri, Anya; Sadhukhan, Shubhadeep; Chakraborty, Sagar

2018-02-01

We model the intracluster medium as a weakly collisional plasma that is a binary mixture of the hydrogen and the helium ions, along with free electrons. When, owing to the helium sedimentation, the gradient of the mean-molecular weight (or equivalently, composition or helium ions' concentration) of the plasma is not negligible, it can have appreciable influence on the stability criteria of the thermal convective instabilities, e.g. the heat-flux-buoyancy instability and the magnetothermal instability (MTI). These instabilities are consequences of the anisotropic heat conduction occurring preferentially along the magnetic field lines. In this paper, without ignoring the magnetic tension, we first present the mathematical criterion for the onset of composition gradient modified MTI. Subsequently, we relax the commonly adopted equilibrium state in which the plasma is at rest, and assume that the plasma is in a sheared state which may be due to differential rotation. We discuss how the concentration gradient affects the coupling between the Kelvin-Helmholtz instability and the MTI in rendering the plasma unstable or stable. We derive exact stability criterion by working with the sharp boundary case in which the physical variables - temperature, mean-molecular weight, density and magnetic field - change discontinuously from one constant value to another on crossing the boundary. Finally, we perform the linear stability analysis for the case of the differentially rotating plasma that is thermally and compositionally stratified as well. By assuming axisymmetric perturbations, we find the corresponding dispersion relation and the explicit mathematical expression determining the onset of the modified MTI.

Effect of reinforcement phase on the mechanical property of tungsten nanocomposite synthesized by spark plasma sintering

DOE PAGES

Lee, Jin -Kyu; Kim, Song -Yi; Ott, Ryan T.; ...

2015-07-15

Nanostructured tungsten composites were fabricated by spark plasma sintering of nanostructured composite powders. The composite powders, which were synthesized by mechanical milling of tungsten and Ni-based alloy powders, are comprised of alternating layers of tungsten and metallic glass several hundred nanometers in size. The mechanical behavior of the nanostructured W composite is similar to pure tungsten, however, in contrast to monolithic pure tungsten, some macroscopic compressive plasticity accompanies the enhanced maximum strength up to 2.4 GPa by introducing reinforcement. As a result, we have found that the mechanical properties of the composites strongly depend on the uniformity of the nano-grainedmore » tungsten matrix and reinforcement phase distribution.« less

Spark plasma sintering of ceramic matrix composite based on alumina, reinforced by carbon nanotubes

NASA Astrophysics Data System (ADS)

Leonov, A. A.; Khasanov, A. O.; Danchenko, V. A.; Khasanov, O. L.

2017-12-01

Alumina composites reinforced with 3 vol.% multi-walled carbon nanotubes (MWCNTs) were prepared by spark plasma sintering (SPS). The influence of sintering temperature (1400-1600 °C) on the composites microstructure and mechanical properties was investigated. Microstructure observations of the composite shows that some CNTs site along alumina grains boundary, while others embed into the alumina grains and shows that CNTs bonded strongly with the alumina matrix contributing to fracture toughness and microhardness increase. MWCNTs reinforcing mechanisms including CNT pull-out and crack deflection were directly observed by scanning electron microscope (SEM). For Al2O3/CNT composite sintered at 1600 °C, fracture toughness and microhardness are 4.93 MPa·m1/2 and 23.26 GPa respectively.

Nonlinear nature of composite structure induced by the interaction of nonplanar solitons in a nonextensive plasma

NASA Astrophysics Data System (ADS)

Han, Jiu-Ning; Luo, Jun-Hua; Liu, Zhen-Lai; Shi, Jun; Xiang, Gen-Xiang; Li, Jun-Xiu

2015-06-01

The nonlinear properties of composite structure induced by the head-on collision of electron-acoustic solitons in a general plasma composed of cold fluid electrons, hot nonextensive distributed electron, and stationary ions are studied. We have made a detailed investigation on the time-evolution process of this merged wave structure. It is found that the structure survives during some time interval, and there are obviously different for the properties of the composite structures which are induced in cylindrical and spherical geometries. Moreover, it is shown that there are both positive and negative phase shifts for each colliding soliton after the interaction. For fixed plasma parameters, the soliton received the largest phase shift in spherical geometry, followed by the cylindrical and one-dimensional planar geometries.

Geopolymers prepared from DC plasma treated air pollution control (APC) residues glass: properties and characterisation of the binder phase.

PubMed

Kourti, Ioanna; Devaraj, Amutha Rani; Bustos, Ana Guerrero; Deegan, David; Boccaccini, Aldo R; Cheeseman, Christopher R

2011-11-30

Air pollution control (APC) residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium aluminosilicate glass (APC glass). This has been used to form geopolymer-glass composites that exhibit high strength and density, low porosity, low water absorption, low leaching and high acid resistance. The composites have a microstructure consisting of un-reacted residual APC glass particles imbedded in a complex geopolymer and C-S-H gel binder phase, and behave as particle reinforced composites. The work demonstrates that materials prepared from DC plasma treated APC residues have potential to be used to form high quality pre-cast products. Copyright © 2011 Elsevier B.V. All rights reserved.

Sputtering by the Solar Wind: Effects of Variable Composition

NASA Technical Reports Server (NTRS)

Killen, R. M.; Arrell, W. M.; Sarantos, M.; Delory, G. T.

2011-01-01

It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that there is no increase in the sputtering yield caused by highly charged heavy ions for metallic and for semiconducting surfaces, but the sputter yield can be noticeably increased in the case of a good insulating surface. Recently measurements of the solar wind composition have become available. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. Whereas many previous calculations of sputtering were limited to the effects of proton bombardment. we show that the heavy ion component. especially the He++ component. can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. We will discuss sputtering of both neutrals and ions.

Deoxycholic acid modulates cell death signaling through changes in mitochondrial membrane properties[S

PubMed Central

Sousa, Tânia; Castro, Rui E.; Pinto, Sandra N.; Coutinho, Ana; Lucas, Susana D.; Moreira, Rui; Rodrigues, Cecília M. P.; Prieto, Manuel; Fernandes, Fábio

2015-01-01

Cytotoxic bile acids, such as deoxycholic acid (DCA), are responsible for hepatocyte cell death during intrahepatic cholestasis. The mechanisms responsible for this effect are unclear, and recent studies conflict, pointing to either a modulation of plasma membrane structure or mitochondrial-mediated toxicity through perturbation of mitochondrial outer membrane (MOM) properties. We conducted a comprehensive comparative study of the impact of cytotoxic and cytoprotective bile acids on the membrane structure of different cellular compartments. We show that DCA increases the plasma membrane fluidity of hepatocytes to a minor extent, and that this effect is not correlated with the incidence of apoptosis. Additionally, plasma membrane fluidity recovers to normal values over time suggesting the presence of cellular compensatory mechanisms for this perturbation. Colocalization experiments in living cells confirmed the presence of bile acids within mitochondrial membranes. Experiments with active isolated mitochondria revealed that physiologically active concentrations of DCA change MOM order in a concentration- and time-dependent manner, and that these changes preceded the mitochondrial permeability transition. Importantly, these effects are not observed on liposomes mimicking MOM lipid composition, suggesting that DCA apoptotic activity depends on features of mitochondrial membranes that are absent in protein-free mimetic liposomes, such as the double-membrane structure, lipid asymmetry, or mitochondrial protein environment. In contrast, the mechanism of action of cytoprotective bile acids is likely not associated with changes in cellular membrane structure. PMID:26351365

Low temperature alkaline pH hydrolysis of oxygen-free Titan tholins

NASA Astrophysics Data System (ADS)

Brassé, Coralie; Buch, Arnaud; Raulin, François; Coll, Patrice; Poch, Olivier; Ramirez, Sandra

2014-05-01

The largest moon of Saturn, Titan, is known for its dense, nitrogen-rich atmosphere. The organic aerosols which are produced in Titan's atmosphere are of great astrobiological interest, particularly because of their potential evolution when they reach the surface and may interact with putative ammonia-water cryomagma[1]. In this context we have followed the evolution of alkaline pH hydrolysis (25wt% ammonia-water) of Titan tholins (produced by an experimental setup using a plasma DC discharge named PLASMA) at low temperature. Urea has been identified as one of the main product of tholins hydrolysis along with several amino acids (alanine, glycine and aspartic acid). However, those molecules have also been detected in non-hydrolyzed tholins. One explanation is a possible oxygen leak in the PLASMA reactor during the tholins synthesis[2]. Following this preliminary study the synthesis protocol has been improved by isolating the whole device in a specially designed glove box which protect the PLASMA experiment from the laboratory atmosphere. Once we confirmed the non-presence of oxygen in tholins, we performed alkaline pH hydrolysis of oxygen-free tholins. Then we verify that the organic compounds cited above are still produced in-situ. Moreover, a recent study shows that the subsurface ocean may contain a lower fraction of ammonia (about 5wt% or less[3]), than the one used until now in this kind of experimental study[2, 4]. Thus, we have carried out new hydrolysis experiments which take this lower value into account. Additional studies have provided new highlights on the bulk composition of Titan for various gas species. Indeed, the observed Saturn's atmosphere enrichment constrains the composition of the planetesimals present in the feeding zone of Saturn. The enrichment in volatiles in Saturn's atmosphere has been reproduced by assuming the presence of specific gas species[5, 6], in particular CO2 and H2S. In the present study we assume that those gas species have been trapped in the likely internal ocean. Then by taking into account the plausible acid-alkaline properties of the water-ammonia ocean, we determine a new probable composition of the cryomagma which could potentially interact with deposited Titan's aerosols. They were also included in our hydrolysis experiments. Taking into account these new data, four different hydrolyses have been applied to oxygen-free tholins. For each type of hydrolysis, we also follow the influence of the hydrolysis temperature on the organic molecules production. References: [1] Mitri et al., 2008. Resurfacing of Titan by ammonia-water cryomagma. Icarus. 196, 216-224. [2] Poch et al., 2011. Production yields of organics of astrobiological interest from H2O-NH3 hydrolysis of Titan's tholins. Planetary and Space Science. 61, 114-123. [3] Tobie et al. 2012. Titan's Bulk Composition Constrained by Cassini-Huygens: implication for internal outgassing. The Astrophysical Journal. 752, 125. [4] Neish et al., 2009. Low temperature hydrolysis of laboratory tholins in ammonia-water solutions: Implications for prebiotic chemistry on Titan. Icarus. 201, 412-421. [5] Hersant et al., 2004. Enrichment in volatiles in the giant planets of the Solar System. Planetary and Space Science. 52, 623-641. [6] Hersant et al., 2008. Interpretation of the carbon abundance in Saturn measured by Cassini. Planetary and Space Science. 56, 1103-1111. Acknowledgements: We acknowledge support from the French Space Agency (CNES) and the European Space Agency (ESA).

Plasma-enhanced synthesis of green flame retardant cellulosic materials

NASA Astrophysics Data System (ADS)

Totolin, Vladimir

The natural fiber-containing fabrics and composites are more environmentally friendly, and are used in transportation (automobiles, aerospace), military applications, construction industries (ceiling paneling, partition boards), consumer products, etc. Therefore, the flammability characteristics of the composites based on polymers and natural fibers play an important role. This dissertation presents the development of plasma assisted - green flame retardant coatings for cellulosic substrates. The overall objective of this work was to generate durable flame retardant treatment on cellulosic materials. In the first approach sodium silicate layers were pre-deposited onto clean cotton substrates and cross linked using low pressure, non-equilibrium oxygen plasma. A statistical design of experiments was used to optimize the plasma parameters. The modified cotton samples were tested for flammability using an automatic 45° angle flammability test chamber. Aging tests were conducted to evaluate the coating resistance during the accelerated laundry technique. The samples revealed a high flame retardant behavior and good thermal stability proved by thermo-gravimetric analysis. In the second approach flame retardant cellulosic materials have been produced using a silicon dioxide (SiO2) network coating. SiO 2 network armor was prepared through hydrolysis and condensation of the precursor tetraethyl orthosilicate (TEOS), prior coating the substrates, and was cross linked on the surface of the substrates using atmospheric pressure plasma (APP) technique. Due to protection effects of the SiO2 network armor, the cellulosic based fibers exhibit enhanced thermal properties and improved flame retardancy. In the third approach, the TEOS/APP treatments were extended to linen fabrics. The thermal analysis showed a higher char content and a strong endothermic process of the treated samples compared with control ones, indicating a good thermal stability. Also, the surface analysis proved the existence of the silica-based coatings on all treated cellulosic substrates after intense ultrasound washes. The results obtained in this work allow us to conclude that silica-based coatings used in conjunction with plasma processes have high potential to obtain green flame retardant cellulosic materials with potential applications in the development of upholstered furniture, clothing and military applications.

Real-time measurement of size-resolved elemental composition ratio for flame synthesized composite nanoparticle aggregates using a tandem SMPS-ICP-OES

PubMed Central

Reed, Nathan; Fang, Jiaxi; Chavalmane, Sanmathi; Biswas, Pratim

2017-01-01

Composite nanoparticles find application in catalysis, drug delivery, and energy storage and require increasingly fine control of their physical properties and composition. While composite nanoparticles have been widely synthesized and characterized, little work has systematically correlated the initial concentration of precursors and the final composition of flame synthesized composite nanoparticles. This relationship is explored in a diffusion flame aerosol reactor by coupling a scanning mobility particle sizer (SMPS) with an inductively coupled plasma optical emission spectrometer (ICP-OES). A framework for studying the relationship between the initial precursor concentrations of different elements and the final nanoparticle composition is explored. The size-resolved elemental composition was measured by directly injecting size-selected fractions of aggregated magnetite and silicon dioxide composite nanoparticles into the ICP-OES plasma. This work showed a correlation between precursor molar ratio and the measured elemental ratio in the mobility size range of 50 to 140 nm. Building on previous work studying size resolved elemental composition of engineered nanoparticles, the analysis is extended to flame synthesized composite nanoparticle aggregates in this work. PMID:28435179

Real-time measurement of size-resolved elemental composition ratio for flame synthesized composite nanoparticle aggregates using a tandem SMPS-ICP-OES.

PubMed

Reed, Nathan; Fang, Jiaxi; Chavalmane, Sanmathi; Biswas, Pratim

2017-01-01

Composite nanoparticles find application in catalysis, drug delivery, and energy storage and require increasingly fine control of their physical properties and composition. While composite nanoparticles have been widely synthesized and characterized, little work has systematically correlated the initial concentration of precursors and the final composition of flame synthesized composite nanoparticles. This relationship is explored in a diffusion flame aerosol reactor by coupling a scanning mobility particle sizer (SMPS) with an inductively coupled plasma optical emission spectrometer (ICP-OES). A framework for studying the relationship between the initial precursor concentrations of different elements and the final nanoparticle composition is explored. The size-resolved elemental composition was measured by directly injecting size-selected fractions of aggregated magnetite and silicon dioxide composite nanoparticles into the ICP-OES plasma. This work showed a correlation between precursor molar ratio and the measured elemental ratio in the mobility size range of 50 to 140 nm. Building on previous work studying size resolved elemental composition of engineered nanoparticles, the analysis is extended to flame synthesized composite nanoparticle aggregates in this work.

Method for cracking hydrocarbon compositions using a submerged reactive plasma system

DOEpatents

Kong, P.C.

1997-05-06

A method is described for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap there between. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition. 6 figs.

Method for cracking hydrocarbon compositions using a submerged reactive plasma system

DOEpatents

Kong, Peter C.

1997-01-01

A method for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap therebetween. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition.

Investigation on mechanical behavior and material characteristics of various weight composition of SiCp reinforced aluminium metal matrix composite

NASA Astrophysics Data System (ADS)

Pichumani, Sivachidambaram; Srinivasan, Raghuraman; Ramamoorthi, Venkatraman

2018-02-01

Aluminium - silicon carbide (Al - SiC) metal matrix composite is produced with following wt % of SiC reinforcement (4%, 8% & 12%) using stir casting method. Mechanical testing such as micro hardness, tensile testing and bend testing were performed. Characterizations, namely micro structure, X-ray diffraction (XRD) analysis, inductive coupled plasma - optical emission spectroscopy (ICP-OES) and scanning electron microscopy (SEM) analysis, were carried out on Al - SiC composites. The presence of SiC on Al - SiC composite is confirmed through XRD technique and microstructure. The percentage of SiC was confirmed through ICP-OES technique. Increase in weight percentage of SiC tends to increase micro hardness, ultimate strength & yield strength but it reduces the bend strength and elongation (%) of the material. SEM factrography of tensile tested fractured samples of Al - 8% SiC & Al - 12% SiC showed fine dimples on fractured surface & coarse dimples fractured surface respectively. This showed significant fracture differences between Al - 8% SiC & Al - 12% SiC. From the above experiment, Al - 8% SiC had good micro hardness, ultimate strength & yield strength without significant loss in elongation (%) & bend strength.

Progress in the Development of a High Power Helicon Plasma Source for the Materials Plasma Exposure Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goulding, Richard Howell; Caughman, John B.; Rapp, Juergen

Proto-MPEX is a linear plasma device being used to study a novel RF source concept for the planned Material Plasma Exposure eXperiment (MPEX), which will address plasma-materials interaction (PMI) for nuclear fusion reactors. Plasmas are produced using a large diameter helicon source operating at a frequency of 13.56 MHz at power levels up to 120 kW. In recent experiments the helicon source has produced deuterium plasmas with densities up to ~6 × 1019 m–3 measured at a location 2 m downstream from the antenna and 0.4 m from the target. Previous plasma production experiments on Proto-MPEX have generated lower densitymore » plasmas with hollow electron temperature profiles and target power deposition peaked far off axis. The latest experiments have produced flat Te profiles with a large portion of the power deposited on the target near the axis. This and other evidence points to the excitation of a helicon mode in this case.« less

Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system.

PubMed

Grönlund, Rasmus; Lundqvist, Mats; Svanberg, Sune

2006-08-01

A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light.

Plasma membrane lipid–protein interactions affect signaling processes in sterol-biosynthesis mutants in Arabidopsis thaliana

PubMed Central

Zauber, Henrik; Burgos, Asdrubal; Garapati, Prashanth; Schulze, Waltraud X.

2014-01-01

The plasma membrane is an important organelle providing structure, signaling and transport as major biological functions. Being composed of lipids and proteins with different physicochemical properties, the biological functions of membranes depend on specific protein–protein and protein–lipid interactions. Interactions of proteins with their specific sterol and lipid environment were shown to be important factors for protein recruitment into sub-compartmental structures of the plasma membrane. System-wide implications of altered endogenous sterol levels for membrane functions in living cells were not studied in higher plant cells. In particular, little is known how alterations in membrane sterol composition affect protein and lipid organization and interaction within membranes. Here, we conducted a comparative analysis of the plasma membrane protein and lipid composition in Arabidopsis sterol-biosynthesis mutants smt1 and ugt80A2;B1. smt1 shows general alterations in sterol composition while ugt80A2;B1 is significantly impaired in sterol glycosylation. By systematically analyzing different cellular fractions and combining proteomic with lipidomic data we were able to reveal contrasting alterations in lipid–protein interactions in both mutants, with resulting differential changes in plasma membrane signaling status. PMID:24672530

A statistical anomaly indicates symbiotic origins of eukaryotic membranes

PubMed Central

Bansal, Suneyna; Mittal, Aditya

2015-01-01

Compositional analyses of nucleic acids and proteins have shed light on possible origins of living cells. In this work, rigorous compositional analyses of ∼5000 plasma membrane lipid constituents of 273 species in the three life domains (archaea, eubacteria, and eukaryotes) revealed a remarkable statistical paradox, indicating symbiotic origins of eukaryotic cells involving eubacteria. For lipids common to plasma membranes of the three domains, the number of carbon atoms in eubacteria was found to be similar to that in eukaryotes. However, mutually exclusive subsets of same data show exactly the opposite—the number of carbon atoms in lipids of eukaryotes was higher than in eubacteria. This statistical paradox, called Simpson's paradox, was absent for lipids in archaea and for lipids not common to plasma membranes of the three domains. This indicates the presence of interaction(s) and/or association(s) in lipids forming plasma membranes of eubacteria and eukaryotes but not for those in archaea. Further inspection of membrane lipid structures affecting physicochemical properties of plasma membranes provides the first evidence (to our knowledge) on the symbiotic origins of eukaryotic cells based on the “third front” (i.e., lipids) in addition to the growing compositional data from nucleic acids and proteins. PMID:25631820

Fast modification on wheat straw outer surface by water vapor plasma and its application on composite material.

PubMed

Chen, Weimin; Xu, Yicheng; Shi, Shukai; Cao, Yizhong; Chen, Minzhi; Zhou, Xiaoyan

2018-02-02

The presence of non-poplar extracts, cutin, and wax layer in the wheat straw outer surface (WOS) greatly limit its application in bio-composite preparation. In this study, a dielectric-barrier-discharge plasma using water vapor as feeding gas was used to fast modify the WOS. The morphology, free radical concentrations, surface chemical components, and contact angles of WOS before and after plasma modification were investigated. Wheat straw was further prepared into wheat straw-based composites (WSC) and its bonding strength was evaluated by a paper tension meter. The results showed that water vapor plasma leads to the appearance of surface roughness, the generation of massive free radicals, and the introduction of oxygen-containing groups. In addition, both initial and equilibrium contact angle and the surface total free energy were significantly increased after plasma modification. These results synergistically facilitate the spread and permeation of adhesive onto the WOS and thus improve the bonding strength of all prepared WSCs. A good linear relationship between bonding strength and surface roughness parameters, contact angles, and total free energy were observed. In general, this study provided a time-saving and cost-effective modification method to realize WSC manufacture.

ARO - Terrestrial Research Program, Methodologies and Protocols for Characterization of Geomaterials

DTIC Science & Technology

2015-05-14

of ice involves melting, digestion, and analysis using inductively coupled plasma – mass spectrometry (ICPMS). ICP-MS analysis established elemental...4] have distinct chemical compositions. Knowledge of the chemical composition of the mineral assemblage present in a rock is critical to...activation analysis (INAA), to inductively-coupled plasma analysis and mass spectrometry (ICP & ICP-MS), mass spectrometry (MS), and laser-ablation

Analysis and utilization of plasma treated water for food and agricultural interest

NASA Astrophysics Data System (ADS)

Park, Sanghoo; Lim, Youbong; Park, Joo Young; Choe, Wonho; Kim, Hyun-Joo; Yong, Hae In; Jo, Cheorun; Jung, Samooel

2015-09-01

Attention on aqueous chemical species produced in plasma-treated solutions through plasma-liquid interactions has been increased because of its strong relation to bio/medical and food applications. The long-lived and reactive oxygen and nitrogen species such as hydrogen peroxide, ozone, superoxide anion, and oxyacids play a crucial role in those applications. The plasma treatment brings about absorption of these species into the target liquid and also induces changes in liquid characteristics and composition via photolysis by plasma UV emission and post-discharge reactions. In this presentation, we discuss the result of our investigation of the chemical properties related to the two main oxyacids, HNO2 and HNO3, in plasma treated water (PTW). Water was treated in close proximity by our SDBD system developed specifically to meet the application requirements. The chemical properties of the solution varied gradually over the treatment time and storage time. Here we report the result of our experiment, theoretical analysis, and their consistency. Furthermore, the dependence of the nitrite ion production yield on the dissipated power, treatment time, and dielectric material will be discussed. Based on the revealed fundamental characteristics, the utilization of PTW in the meat curing process as one of the nitrite sources will be briefly demonstrated. In terms of sausage quality, there were no noticeable effects of PTW on the total aerobic bacteria counts, color, and peroxide values of sausages compared with those using celery powder and sodium nitrite.

Ionospheres of the terrestrial planets

NASA Astrophysics Data System (ADS)

Schunk, R. W.; Nagy, A. F.

1980-11-01

The theory and observations relating to the ionospheres of the terrestrial planets Venus, the earth, and Mars are reviewed. Emphasis is placed on comparing the basic differences and similarities between the planetary ionospheres. The review covers the plasma and electric-magnetic field environments that surround the planets, the theory leading to the creation and transport of ionization in the ionospheres, the relevant observations, and the most recent model calculations. The theory section includes a discussion of ambipolar diffusion in a partially ionized plasma, diffusion in a fully ionized plasma, supersonic plasma flow, photochemistry, and heating and cooling processes. The sections on observations and model calculations cover the neutral atmosphere composition, the ion composition, the electron density, and the electron, ion, and neutral temperatures.

Transmembrane voltage: Potential to induce lateral microdomains.

PubMed

Malinsky, Jan; Tanner, Widmar; Opekarova, Miroslava

2016-08-01

Lateral segregation of plasma membrane lipids is a generally accepted phenomenon. Lateral lipid microdomains of specific composition, structure and biological functions are established as a result of simultaneous action of several competing mechanisms which contribute to membrane organization. Various lines of evidence support the conclusion that among those mechanisms, the membrane potential plays significant and to some extent unique role. Above all, clear differences in the microdomain structure as revealed by fluorescence microscopy could be recognized between polarized and depolarized membranes. In addition, recent fluorescence spectroscopy experiments reported depolarization-induced changes in a membrane lipid order. In the context of earlier findings showing that plasma membranes of depolarized cells are less susceptible to detergents and the cells less sensitive to antibiotics or antimycotics treatment we discuss a model, in which membrane potential-driven re-organization of the microdomain structure contributes to maintaining membrane integrity during response to stress, pathogen attack and other challenges involving partial depolarization of the plasma membrane. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon. Copyright © 2016 Elsevier B.V. All rights reserved.

Femtosecond ablation applied to deep-drilling of hard metals

NASA Astrophysics Data System (ADS)

Bruneau, Sebastien; Hermann, Joerg; Dumitru, Gabriel; Sentis, Marc L.

2004-09-01

Mechanisms responsible for the limitation of the aspect ratio obtained by deep drilling of hard metals are investigated in the present work. Cemented carbide targets have been irradiated with laser pulses of 100 fs duration and 100 μJ maximum energy delivered by a Ti:sapphire laser system. The experiments are carried out in different gas environments (vacuum, air, helium up to atmospheric pressure) with incident laser fluences ranging from 1 to 20 Jcm-2. During deep drilling, the laser-induced ablation plume is characterized by means of in-situ plasma diagnostics. Fast imaging is used to observe the expansion behavior of the plasma plume whereas time- and space-resolved emission spectroscopy is employed to analyze the plasma composition. After irradiation, the laser-produced craters were examined by optical microscopy. A correlation between the ablation plume characteristics and the morphological changes of the mciro-holes is established. The results indicate that nanoclusters, that present a significant part of the ablated material, are responsbile for the alteration of the crater shape in the high laser fluence regime.

Multiobjective Optimization of Atmospheric Plasma Spray Process Parameters to Deposit Yttria-Stabilized Zirconia Coatings Using Response Surface Methodology

NASA Astrophysics Data System (ADS)

Ramachandran, C. S.; Balasubramanian, V.; Ananthapadmanabhan, P. V.

2011-03-01

Atmospheric plasma spraying is used extensively to make Thermal Barrier Coatings of 7-8% yttria-stabilized zirconia powders. The main problem faced in the manufacture of yttria-stabilized zirconia coatings by the atmospheric plasma spraying process is the selection of the optimum combination of input variables for achieving the required qualities of coating. This problem can be solved by the development of empirical relationships between the process parameters (input power, primary gas flow rate, stand-off distance, powder feed rate, and carrier gas flow rate) and the coating quality characteristics (deposition efficiency, tensile bond strength, lap shear bond strength, porosity, and hardness) through effective and strategic planning and the execution of experiments by response surface methodology. This article highlights the use of response surface methodology by designing a five-factor five-level central composite rotatable design matrix with full replication for planning, conduction, execution, and development of empirical relationships. Further, response surface methodology was used for the selection of optimum process parameters to achieve desired quality of yttria-stabilized zirconia coating deposits.

Photon Calorimeter

DOEpatents

Chow, Tze-Show

1989-01-01

A photon calorimeter (20, 40) is provided that comprises a laminar substrate (10, 22, 42) that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating (28, 48, 52), that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions (30, 50, 54) are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly.

Low-temperature synthesis of homogeneous solid solutions of scheelite-structured Ca 1-xSr xWO 4 and Sr 1-xBa xWO 4 nanocrystals

DOE PAGES

Culver, Sean P.; Greaney, Matthew J.; Tinoco, Antonio; ...

2015-07-24

Here, a series of compositionally complex scheelite-structured nanocrystals of the formula A 1-xA’ xWO 4 (A = Ca, Sr, Ba) have been prepared under benign synthesis conditions using the vapor diffusion sol–gel method. Discrete nanocrystals with sub-20 nm mean diameters were obtained after kinetically controlled hydro- lysis and polycondensation at room temperature, followed by composition-dependent thermal aging at or below 60 °C. Rietveld analysis of X-ray diffraction data and Raman spectroscopy verified the synthesis of continuous and phase-pure nanocrystal solid solutions across the entire composition space for A 1-xA’ xWO 4, where 0 ≤ x ≤ 1. Elemental analysis bymore » X-ray photoelectron and inductively coupled plasma- atomic emission spectroscopies demonstrated excellent agreement between the nominal and experi- mentally determined elemental stoichiometries, while energy dispersive X-ray spectroscopy illustrated good spatial elemental homogeneity within these nanocrystals synthesized under benign conditions.« less

Nanotube Production and Applications at Johnson Space Center

NASA Technical Reports Server (NTRS)

Nikolaev, Pavel; Files, Bradley; Arepalli, Sivaram; Scott, Carl; Holmes, William; Nicholson, Leonard S. (Technical Monitor)

2000-01-01

Promise of applications of carbon nanotubes has led to an intense effort at NASA/JSC, especially in the area of nanotube composites. Using the extraordinary mechanical strength of nanotubes, NASA hopes to design this revolutionary lightweight material for use in aerospace applications. Current research focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical applications. In pursuit of these goals, we have set up both laser and arc production processes for nanotubes. An in-depth diagnostic study of the plasma plume in front of the laser target has been studied to try to determine nanotube growth mechanisms. Complementary studies of characterization of nanotube product have added to knowledge of growth conditions. Results of our preliminary experiments in incorporating nanotubes into composites will be presented. Morphology and mechanical properties of the nanotubes composites will be discussed.

Effects of differently composed feeds and physical stress on plasma gastrin concentration in horses.

PubMed

Sandin, A; Girma, K; Sjöholm, B; Lindholm, A; Nilsson, G

1998-01-01

Plasma gastrin concentrations were determined in 6 Standardbreds (4 geldings and 2 mares) after 3 different meals consisting of unlimited amounts of hay (8-9 kg per horse), a restricted amount of hay (0.6 kg/100 kg body-weight) and grain (0.2 kg/100 kg body-weight) in combination or of grain alone (0.2 kg/100 kg body-weight). In another series of experiments the possible role of gastrin as a stress hormone was investigated. Plasma gastrin and cortisol concentrations were determined during fasting and compared with concentrations during hay feeding. In addition, gastrin and cortisol concentrations were determined before, during and after 2 kinds of physical exercise on a treadmill. Meal stimulation significantly increased the plasma gastrin concentration, irrespective of the meal composition. An immediate and large increase in plasma gastrin concentration was found when voluminous meals were given, whereas a small meal evoked a later onset of gastrin release, suggesting that gastric distention plays an important role in inducing gastrin release during a meal. Meals consisting of grain seem to evoke a slower onset and then a more prolonged gastrin response than a hay meal, possibly due to different emptying rates of the stomach. Nervous excitation may play a minor role in the activation of gastrin release in horses. No experimental support was obtained for the idea that gastrin acts as a stress hormone in the horse.

The Effect of Drinking on Plasma Vasopressin and Renin in Dehydrated Human Subjects

NASA Technical Reports Server (NTRS)

Geelen, G.; Keil, L. C.; Kravik, S. E.; Wade, C. E.; Thrasher, T. N.; Barnes, P. R.; Pyka, G.; Nesvig, C.; Greenleaf, J. E.

1996-01-01

Oropharyngeal mechanisms activated by drinking have been shown to induce a rapid decline in plasma vasopressin which preceeds postabsorptive changes in plasma composition in the dehydrated dog. The present study was undertaken to determine what factor(s) inhibit(s) vasopressin secretion after rehydration in water deprived human subjects. Hematocrit (Hct) and hemoglobin (Hb) were determined on the day of the experiment, together with electrolytes and osmolalities which were measured on freshly separated serum. Plasma was immediately frozen and further analyzed by radioimmunoassay for renin activity (PRA), vasopressin (AVP), and aldosterone. The data were analyzed using an analysis of variance for repeated measurements and significant differences between the dehydrated control period and various time points after the start of rehydration were determined using a multiple-range test. began and reached water replete levels 15 minutes after drinking in the absence of any detectable decline in serum sodium or osmolality, we conclude that 427 oropharyngeal factors, alone or combined with gastric distension account for the extremely rapid inhibition of AVP secretion after drinking in the water-deprived human, as has been shown to be the case in dogs. Our findings are also in agreement wiht the recent demonstration that at the onset of drinking in the dehydrated monkey, there is an abrupt fall in plasma AVP concentration associated with a considerable decrease in the firing rate of the supraoptic neurosecretory neurons.

2-heptyl-formononetin increases cholesterol and induces hepatic steatosis in mice.

PubMed

Andersen, Charlotte; Schjoldager, Janne G; Tortzen, Christian G; Vegge, Andreas; Hufeldt, Majbritt R; Skaanild, Mette T; Vogensen, Finn K; Kristiansen, Karsten; Hansen, Axel K; Nielsen, John

2013-01-01

Consumption of isoflavones may prevent adiposity, hepatic steatosis, and dyslipidaemia. However, studies in the area are few and primarily with genistein. This study investigated the effects of formononetin and its synthetic analogue, 2-heptyl-formononetin (C7F), on lipid and cholesterol metabolism in C57BL/6J mice. The mice were fed a cholesterol-enriched diet for five weeks to induce hypercholesterolemia and were then fed either the cholesterol-enriched diet or the cholesterol-enriched diet-supplemented formononetin or C7F for three weeks. Body weight and composition, glucose homeostasis, and plasma lipids were compared. In another experiment, mice were fed the above diets for five weeks, and hepatic triglyceride accumulation and gene expression and histology of adipose tissue and liver were examined. Supplementation with C7F increased plasma HDL-cholesterol thereby increasing the plasma level of total cholesterol. Supplementation with formononetin did not affect plasma cholesterol but increased plasma triglycerides levels. Supplementation with formononetin and C7F induced hepatic steatosis. However, formononetin decreased markers of inflammation and liver injury. The development of hepatic steatosis was associated with deregulated expression of hepatic genes involved in lipid and lipoprotein metabolism. In conclusion, supplementation with formononetin and C7F to a cholesterol-enriched diet adversely affected lipid and lipoprotein metabolism in C57BL/6J mice.

2-Heptyl-Formononetin Increases Cholesterol and Induces Hepatic Steatosis in Mice

PubMed Central

Andersen, Charlotte; Schjoldager, Janne G.; Tortzen, Christian G.; Vegge, Andreas; Hufeldt, Majbritt R.; Skaanild, Mette T.; Vogensen, Finn K.; Kristiansen, Karsten; Hansen, Axel K.; Nielsen, John

2013-01-01

Consumption of isoflavones may prevent adiposity, hepatic steatosis, and dyslipidaemia. However, studies in the area are few and primarily with genistein. This study investigated the effects of formononetin and its synthetic analogue, 2-heptyl-formononetin (C7F), on lipid and cholesterol metabolism in C57BL/6J mice. The mice were fed a cholesterol-enriched diet for five weeks to induce hypercholesterolemia and were then fed either the cholesterol-enriched diet or the cholesterol-enriched diet-supplemented formononetin or C7F for three weeks. Body weight and composition, glucose homeostasis, and plasma lipids were compared. In another experiment, mice were fed the above diets for five weeks, and hepatic triglyceride accumulation and gene expression and histology of adipose tissue and liver were examined. Supplementation with C7F increased plasma HDL-cholesterol thereby increasing the plasma level of total cholesterol. Supplementation with formononetin did not affect plasma cholesterol but increased plasma triglycerides levels. Supplementation with formononetin and C7F induced hepatic steatosis. However, formononetin decreased markers of inflammation and liver injury. The development of hepatic steatosis was associated with deregulated expression of hepatic genes involved in lipid and lipoprotein metabolism. In conclusion, supplementation with formononetin and C7F to a cholesterol-enriched diet adversely affected lipid and lipoprotein metabolism in C57BL/6J mice. PMID:23738334

Spacelab

NASA Image and Video Library

1985-07-01

This STS-51F mission onboard Photograph shows some of the Spacelab-2 instruments in the cargo bay of the Orbiter Challenger. The Plasma Diagnostics Package (PDP). shown at the end of the Remote Manipulator System (RMS), used instruments on a subsatellite to study natural plasma processes, orbiter-induced plasma processes, and beam plasma physics. Fourteen instruments were mounted on the PDP for measurements of various plasma characteristics. The X-ray Telescope (XRT), is at the front. The goal of this investigation was to image and examine the X-ray emissions from clusters of galaxies in order to study the mechanisms that cause high-temperature emissions and to determine the weight of galactic clusters. The Small Helium-Cooled Infrared Telescope (IRT) is at the right behind the XRT. The objective of this investigation was to measure and map diffused and discrete infrared astronomical sources while evaluating the Space Shuttle as a platform for infrared astronomy. At the same time, a new large superfluid helium dewar system for cooling the telescope was evaluated. The egg-shaped Cosmic Ray Nuclei experiment (CRNE) is shown at the rear. This investigation was to study the composition of high-energy cosmic rays by using a large instrument exposed to space for a considerable period of time. Spacelab-2 (STS-51F, 19th Shuttle mission) was launched aboard the Space Shuttle Orbiter Challenger on July 29, 1985.

Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

NASA Astrophysics Data System (ADS)

Horton, W.; Ditmire, T.; Zakharov, Yu. P.

2010-06-01

Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

[Relationship between dietary pattern and maternal state of fatty acids during pregnancy in three regions of China].

PubMed

Gao, Yixiong; Li, Yuqian; Wang, Chunrong; Li, Lixiang; Man, Qingqing; Zhang, Jian; Meng, Zhuoran

2016-05-01

To investigate the dietary pattern during pregnancy and the compositions of fatty acids of phosphatidylcholine (PC) during pregnancy in different regions of China. 35 Health women of each region were recruited from three different geographical regions in China: Jurong (an inland region close to freshwater), Rizhao (a coastal region) and Xushui (an inland region with limited access to freshwater). All women were long-term residents of their respective region. Their dietary status (including consumption frequency of food and consumption of culinary oil) during second trimester pregnancy was recorded and the fatty acid composition of PC in plasma during late pregnancy (34 weeks gestation) was quantified by GC. The consumption frequency of marine fish in Rizhao was significant higher than in other two regions. The main n-3 polyunsaturated fatty acids of PC in plasma was docosahexaenoic acid (DHA) in all regions. The composition of DHA in three regions were (3.31 +/- 0.77) %, (3.74 +/- 1.21) % and (2.44 +/- 0.63) %, respectively. The composition of DHA in Xushui was significant lower than in other two regions (P < 0.017). There was positive relationship between consumption frequency of marine fish and composition of DHA of PC in plasma (r = 0.337, P < 0.05). There was relationship between pregnant women's fatty acids composition of PC in plasma and their dietary. The consumption of food with high content of n-3 long chain polyunsaturated fatty acids during pregnancy would be more practical for DHA store of pregnant women.

Spectroscopie d'emission VUV-visible provenant de plasmas basse pression: Applications aux traitements de surfaces polymeriques

NASA Astrophysics Data System (ADS)

Fozza, Alexandru C.

The main objective of this thesis is to make a contribution to the spectroscopic study of low pressure glow discharges in the vacuum ultraviolet and to reveal the effect of this radiation on polymeric materials. This research considers the following important aspects relevant to low pressure glow discharges: (i)characterization of vacuum ultraviolet (VUV) emission of several plasmas in the wavelength range available through crystalline fluoride windows, (ii)analysis of the emission dependence on several external parameters, and (iii)study of the VUV effect, in the accessible range, on polymeric materials of interest with respect to plasma treatments. The plasmas investigated, namely, hydrogen, oxygen and their mixtures with argon, were chosen by taking into consideration the composition of the gases used in technological plasmas, and the conditions needed for polymeric material irradiation. Two separate spectrophotometric instruments, a VUV monochromator (ARC VM-502) and an optical multichannel analyzer (OMA), were used. For the chosen plasmas, we measured the variation of the intensity of the atomic lines for different gas pressures and absorbed power levels. In the case of pure gas plasmas, the pressure dependence of the atomic line intensities was attributed to changes in the electron energy distribution function (EEDF). The argon emission spectra are very sensitive to the presence of impurities. The mixture plasmas we have studied (Ar-H2 and Ar-O2) show a strong emission of atomic fines in the VUV region, stronger than those resulting from the pure molecular gases. The above mixtures show promise as photon sources for the treatment of polymer surfaces. An important external parameter for the characterization of glow discharges is the excitation frequency. The goal of the specific experiments was to directly investigate the frequency-dependence effect. The frequency-related effects on plasma emission were investigated for two plasmas: pure hydrogen and 7% H2 in Ar mixture. In the case of pure hydrogen, we observed a change from a non-stationary to a stationary electron energy distribution function. For the Ar-H2 mixture, we have shown that the EEDF is stationary and that the dissociation rate for hydrogen molecules does not depend on frequency. A difference between the excitation mechanisms of different atomic lines was proven. Among the most sensitive materials with respect to plasma generated UV radiation are polymers. We have optimized the gaseous composition for various types of VUV radiation fluxes for the photochemical treatments of polymers. We have developed a system containing a thermo-stabilized quartz crystal microbalance (QCM) and chambers for sample irradiation and gas absorption measurements. In this way we have separately measured the effects of both the active oxygen species (AO) and the VUV, as well as their synergistic actions. (Abstract shortened by UMI.)

Electromagnetic diagnostic system for the Keda Torus eXperiment

NASA Astrophysics Data System (ADS)

Tu, Cui; Liu, Adi; Li, Zichao; Tan, Mingsheng; Luo, Bing; You, Wei; Li, Chenguang; Bai, Wei; Fu, Chenshuo; Huang, Fangcheng; Xiao, Bingjia; Shen, Biao; Shi, Tonghui; Chen, Dalong; Mao, Wenzhe; Li, Hong; Xie, Jinglin; Lan, Tao; Ding, Weixing; Xiao, Chijin; Liu, Wandong

2017-09-01

A system for electromagnetic measurements was designed and installed on the Keda Torus eXperiment (KTX) reversed field pinch device last year. Although the unique double-C structure of the KTX, which allows the machine to be opened easily without disassembling the poloidal field windings, makes the convenient replacement and modification of the internal inductive coils possible, it can present difficulties in the design of flux coils and magnetic probes at the two vertical gaps. Moreover, the KTX has a composite shell consisting of a 6 mm stainless steel vacuum chamber and a 1.5 mm copper shell, which results in limited space for the installation of saddle sensors. Therefore, the double-C structure and composite shell should be considered, especially during the design and installation of the electromagnetic diagnostic system (EDS). The inner surface of the vacuum vessel includes two types of probes. One type is for the measurement of the global plasma parameters, and the other type is for studying the local behavior of the plasma and operating the new saddle coils. In addition, the probes on the outer surface of the composite shell are used for measurements of eddy currents. Finally, saddle sensors for radial field measurements for feedback control were installed between the conducting shell and the vacuum vessel. The entire system includes approximately 1100 magnetic probes, 14 flux coils, 4 ×26 ×2 saddle sensors, and 16 Rogowski coils. Considering the large number of probes and limited space available in the vacuum vessel, the miniaturization of the probes and optimization of the probe distribution are necessary. In addition, accurate calibration and careful mounting of the probes are also required. The frequency response of the designed magnetic probes is up to 200 kHz, and the resolution is 1 G. The EDS, being spherical and of high precision, is one of the most basic and effective diagnostic tools of the KTX and meets the demands imposed by requirements on basic machine operating information and future studies.

Program for plasma-sprayed self-lubricating coatings

NASA Technical Reports Server (NTRS)

Walther, G. C.

1979-01-01

A method for preparing composite powders of the three coating components was developed and a procedure that can be used in applying uniform coatings of the composite powders was demonstrated. Composite powders were prepared by adjusting particle sizes of the components and employing a small amount of monoaluminum phosphate as an inorganic binder. Quantitative microscopy (image analysis) was found to be a convenient method of characterizing the composition of the multiphase plasma-sprayed coatings. Area percentages and distribution of the components were readily obtained by this method. The adhesive strength of the coating to a nickel-chromium alloy substrate was increased by about 40 percent by a heat treatment of 20 hours at 650 C.

Cluster Models of Metal-Seeded Energetic Materials

DTIC Science & Technology

1997-01-31

cannot be formed by this plasma chemistry because the metals are less reactive. Plasma chemistry reactions for these metals lead to addition to... plasma chemistry method, but they are produced readily from composite sample (metal film on carbon rod) vaporization. Another technique we have used with

Hydrogen permeation properties of plasma-sprayed tungsten*1

NASA Astrophysics Data System (ADS)

Anderl, R. A.; Pawelko, R. J.; Hankins, M. R.; Longhurst, G. R.; Neiser, R. A.

1994-09-01

Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D 3+ ion beam with fluxes of ˜6.5 × 10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity.

The Sawtooth Oscillation Effect on Fast-Ion Energy Spectra in ITER Plasma and Neutral Particle Analyzer Measurements

NASA Astrophysics Data System (ADS)

Zaitsev, F. S.; Gorelenkov, N. N.; Petrov, M. P.; Afanasyev, V. I.; Mironov, M. I.

2018-03-01

ITER plasma with parameters close to those with the inductive scenario is considered. The distribution functions of fast ions of deuterium D and tritium T are calculated while taking into account the elastic nuclear collisions with alpha particles 4He using the code FPP-3D. The D and T energy spectra detected by the neutral-particle analyzer (NPA) are determined. The plasma mixing effect on these spectra during sawtooth oscillations is studied. It is shown that the NPA makes it possible to detect sawtooth plasma oscillations in ITER and determine the percentage composition of the D‒T mixture in it both with the presence of instabilities and without them. A conclusion is drawn on the prospects of using NPA data in automatic controllers of thermonuclear fuel isotopic composition control and plasma oscillation regulation in ITER.

Lipid Clustering Correlates with Membrane Curvature as Revealed by Molecular Simulations of Complex Lipid Bilayers

PubMed Central

Koldsø, Heidi; Shorthouse, David; Hélie, Jean; Sansom, Mark S. P.

2014-01-01

Cell membranes are complex multicomponent systems, which are highly heterogeneous in the lipid distribution and composition. To date, most molecular simulations have focussed on relatively simple lipid compositions, helping to inform our understanding of in vitro experimental studies. Here we describe on simulations of complex asymmetric plasma membrane model, which contains seven different lipids species including the glycolipid GM3 in the outer leaflet and the anionic lipid, phosphatidylinositol 4,5-bisphophate (PIP2), in the inner leaflet. Plasma membrane models consisting of 1500 lipids and resembling the in vivo composition were constructed and simulations were run for 5 µs. In these simulations the most striking feature was the formation of nano-clusters of GM3 within the outer leaflet. In simulations of protein interactions within a plasma membrane model, GM3, PIP2, and cholesterol all formed favorable interactions with the model α-helical protein. A larger scale simulation of a model plasma membrane containing 6000 lipid molecules revealed correlations between curvature of the bilayer surface and clustering of lipid molecules. In particular, the concave (when viewed from the extracellular side) regions of the bilayer surface were locally enriched in GM3. In summary, these simulations explore the nanoscale dynamics of model bilayers which mimic the in vivo lipid composition of mammalian plasma membranes, revealing emergent nanoscale membrane organization which may be coupled both to fluctuations in local membrane geometry and to interactions with proteins. PMID:25340788

Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.

PubMed

Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C

2015-07-15

Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.

Lipid clustering correlates with membrane curvature as revealed by molecular simulations of complex lipid bilayers.

PubMed

Koldsø, Heidi; Shorthouse, David; Hélie, Jean; Sansom, Mark S P

2014-10-01

Cell membranes are complex multicomponent systems, which are highly heterogeneous in the lipid distribution and composition. To date, most molecular simulations have focussed on relatively simple lipid compositions, helping to inform our understanding of in vitro experimental studies. Here we describe on simulations of complex asymmetric plasma membrane model, which contains seven different lipids species including the glycolipid GM3 in the outer leaflet and the anionic lipid, phosphatidylinositol 4,5-bisphophate (PIP2), in the inner leaflet. Plasma membrane models consisting of 1500 lipids and resembling the in vivo composition were constructed and simulations were run for 5 µs. In these simulations the most striking feature was the formation of nano-clusters of GM3 within the outer leaflet. In simulations of protein interactions within a plasma membrane model, GM3, PIP2, and cholesterol all formed favorable interactions with the model α-helical protein. A larger scale simulation of a model plasma membrane containing 6000 lipid molecules revealed correlations between curvature of the bilayer surface and clustering of lipid molecules. In particular, the concave (when viewed from the extracellular side) regions of the bilayer surface were locally enriched in GM3. In summary, these simulations explore the nanoscale dynamics of model bilayers which mimic the in vivo lipid composition of mammalian plasma membranes, revealing emergent nanoscale membrane organization which may be coupled both to fluctuations in local membrane geometry and to interactions with proteins.

Stress hysteresis and mechanical properties of plasma-enhanced chemical vapor deposited dielectric films

NASA Astrophysics Data System (ADS)

Thurn, Jeremy; Cook, Robert F.; Kamarajugadda, Mallika; Bozeman, Steven P.; Stearns, Laura C.

2004-02-01

A comprehensive survey is described of the responses of three plasma-enhanced chemical vapor deposited dielectric film systems to thermal cycling and indentation contact. All three films—silicon oxide, silicon nitride, and silicon oxy-nitride—exhibited significant nonequilibrium permanent changes in film stress on thermal cycling or annealing. The linear relationship between stress and temperature changed after the films were annealed at 300 °C, representing a structural alteration in the film reflecting a change in coefficient of thermal expansion or biaxial modulus. A double-substrate method was used to deduce both thermoelastic properties before and after the anneal of selected films and the results were compared with the modulus deconvoluted from small-scale depth-sensing indentation experiments (nanoindentation). Rutherford backscattering spectrometry and hydrogen forward scattering were used to deduce the composition of the films and it was found that all the films contained significant amounts of hydrogen.

EFFECT OF SOLID MEDIUM DURING COOLED STORAGE ON STALLION SPERM PARAMETERS.

PubMed

Santos, F C; Corcini, C D; Costa, V G; Gheller, S M; Nogueira, C E; da Rosa Curcio, B; Varel, A S

2015-01-01

Solid storage medium prevents cellular sedimentation, reduces metabolic demand via limiting movement, and avoids the modification of an extender composition in the sedimentary microenvironment. It has been proven to prolong spermatozoa viability in mammalians. This experiment aims to evaluate the effect of cool storage in solid phase extender on stallion sperms. Semen was collected from 10 Crioulo stallions (n=30) and submitted to treatments: control group (semen extender) and groups with gelatin addition in different concentrations (semen extender + 1%, 2% and 3%). Seminal analyses included motility, mitochondrial functionality, plasma membrane integrity, DNA and acrosome at 0; 24; 48 and 72 hours during cooled storage at 5 degree C. Motility, mitochondrial functionality, plasma membrane and acrosome integrity declined during storage time, with no statistical difference between treatments. DNA integrity did not significantly change during storage period. Solid medium was not harmful and did not improved stallion sperm parameters during cooled storage.

Laboratory Studies of Planetary Hazes: composition of cool exoplanet atmospheric aerosols with very high resolution mass spectrometry

NASA Astrophysics Data System (ADS)

Moran, Sarah E.; Horst, Sarah; He, Chao; Flandinet, Laurene; Moses, Julianne I.; Orthous-Daunay, Francois-Regis; Vuitton, Veronique; Wolters, Cedric; Lewis, Nikole

2017-10-01

We present first results of the composition of laboratory-produced exoplanet haze analogues. With the Planetary HAZE Research (PHAZER) Laboratory, we simulated nine exoplanet atmospheres of varying initial gas phase compositions representing increasing metallicities (100x, 1000x, and 10000x solar) and exposed them to three different temperature regimes (600, 400, and 300 K) with two different “instellation” sources (a plasma source and a UV lamp). The PHAZER exoplanet experiments simulate a temperature and atmospheric composition phase space relevant to the expected planetary yield of the Transiting Exoplanet Survey Satellite (TESS) mission as well as recently discovered potentially habitable zone exoplanets in the TRAPPIST-1, LHS-1140, and Proxima Centauri systems. Upon exposure to the energy sources, all of these experiments produced aerosol particles, which were collected in a dry nitrogen glove box and then analyzed with an LTQ Orbitrap XL™ Hybrid Ion Trap-Orbitrap Mass Spectrometer utilizing m/z ranging from 50 to 1000. The collected aerosol samples were found to contain complex organics. Constraining the composition of these aerosols allows us to better understand the photochemical and dynamical processes ongoing in exoplanet atmospheres. Moreover, these data can inform our telescope observations of exoplanets, which is of critical importance as we enter a new era of exoplanet atmosphere observation science with the upcoming launch of the James Webb Space Telescope. The molecular makeup of these haze particles provides key information for understanding exoplanet atmospheric spectra, and constraining the structure and behavior of clouds, hazes, and other aerosols is at the forefront of exoplanet atmosphere science.

Non-thermal plasma instabilities induced by deformation of the electron energy distribution function

NASA Astrophysics Data System (ADS)

Dyatko, N. A.; Kochetov, I. V.; Napartovich, A. P.

2014-08-01

Non-thermal plasma is a key component in gas lasers, microelectronics, medical applications, waste gas cleaners, ozone generators, plasma igniters, flame holders, flow control in high-speed aerodynamics and others. A specific feature of non-thermal plasma is its high sensitivity to variations in governing parameters (gas composition, pressure, pulse duration, E/N parameter). This sensitivity is due to complex deformations of the electron energy distribution function (EEDF) shape induced by variations in electric field strength, electron and ion number densities and gas excitation degree. Particular attention in this article is paid to mechanisms of instabilities based on non-linearity of plasma properties for specific conditions: gas composition, steady-state and decaying plasma produced by the electron beam, or by an electric current pulse. The following effects are analyzed: the negative differential electron conductivity; the absolute negative electron mobility; the stepwise changes of plasma properties induced by the EEDF bi-stability; thermo-current instability and the constriction of the glow discharge column in rare gases. Some of these effects were observed experimentally and some of them were theoretically predicted and still wait for experimental confirmation.

On the use of pulsed Dielectric Barrier Discharges to control the gas-phase composition of atmospheric pressure air plasmas

NASA Astrophysics Data System (ADS)

Barni, R.; Biganzoli, I.; Dell'Orto, E.; Riccardi, C.

2014-11-01

We presents results obtained from the numerical simulation of the gas-phase chemical kinetics in atmospheric pressure air non-equilibrium plasmas. In particular we have addressed the effect of pulsed operation mode of a plane dielectric barrier discharge. It was conjectured that the large difference in the time scales involved in the fast dissociation of oxygen molecules in plasma and their subsequent reactions to produce ozone and nitrogen oxides, makes the presence of a continuously repeated plasma production unnecessary and a waste of electrical power and thus efficiency. In order to test such suggestion we have performed a numerical study of the composition and the temporal evolution of the gas-phase of atmospheric pressure air non-equilibrium plasmas. Comparison with experimental findings in a dielectric barrier discharge with an electrode configuration symmetrical and almost ideally plane is briefly addressed too, using plasma diagnostics to extract the properties of the single micro-discharges and a sensor to measure the concentration of ozone produced by the plasma.

Erythrocyte sedimentation rate and fibrinogen concentration of whole blood influences the cellular composition of platelet-rich plasma obtained from centrifugation methods.

PubMed

Yin, Wenjing; Xu, Zhengliang; Sheng, Jiagen; Xie, Xuetao; Zhang, Changqing

2017-09-01

Erythrocyte sedimentation rate (ESR), which reflects the sedimentation rate of platelets, leukocytes and erythrocytes in response to centrifugal force, may influence the cellular composition of platelet-rich plasma (PRP) obtained via centrifugation methods. However, no relevant studies have substantiated this. In the present study, blood was collected from 40 healthy volunteers and used to prepare PRP with two plasma-based preparation systems [YinPRP and Plasma Rich in Growth Factor (PRGF) systems] and two buffy coat-based systems (RegenPRP and WEGOPRP systems) in a single-donor model. Volumes of PRP and platelet-poor plasma (PPP) that were removed in the preparation process were recorded. Analyses of ESR, haematocrit, C-reaction protein, coagulation, serum glucose and serum lipid of the whole blood used for PRP preparation were performed to evaluate the levels of ESR and the factors known to influence it. Whole blood analysis was performed to evaluate the cellular composition of PRP. Results demonstrated that there were marked positive correlations between the ESR of the whole blood used for PRP preparation and PPP removal efficiencies, platelet concentrations, platelet capture efficiencies and platelet enrichment factors of PRP formulations obtained from plasma-based systems, and PRP yield efficiency of RegenPRP and PPP removal efficiency of WEGOPRP. Furthermore, there were marked negative correlations between ESR and concentrations and enrichment factors of platelets, leukocytes and erythrocytes of RegenPRP. Fibrinogen concentration of the whole blood, which had a marked positive correlation with ESR, also influenced the cellular composition of PRP. These findings may increase the understanding of PRP preparation and provide substantial evidence for the individualised optimisation of PRP preparation systems used in clinical practice.

Computational modeling of joint U.S.-Russian experiments relevant to magnetic compression/magnetized target fusion (MAGO/MTF)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheehey, P.T.; Faehl, R.J.; Kirkpatrick, R.C.

1997-12-31

Magnetized Target Fusion (MTF) experiments, in which a preheated and magnetized target plasma is hydrodynamically compressed to fusion conditions, present some challenging computational modeling problems. Recently, joint experiments relevant to MTF (Russian acronym MAGO, for Magnitnoye Obzhatiye, or magnetic compression) have been performed by Los Alamos National Laboratory and the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF). Modeling of target plasmas must accurately predict plasma densities, temperatures, fields, and lifetime; dense plasma interactions with wall materials must be characterized. Modeling of magnetically driven imploding solid liners, for compression of target plasmas, must address issues such as Rayleigh-Taylor instability growthmore » in the presence of material strength, and glide plane-liner interactions. Proposed experiments involving liner-on-plasma compressions to fusion conditions will require integrated target plasma and liner calculations. Detailed comparison of the modeling results with experiment will be presented.« less

The HelCat basic plasma science device

NASA Astrophysics Data System (ADS)

Gilmore, M.; Lynn, A. G.; Desjardins, T. R.; Zhang, Y.; Watts, C.; Hsu, S. C.; Betts, S.; Kelly, R.; Schamiloglu, E.

2015-01-01

The Helicon-Cathode(HelCat) device is a medium-size linear experiment suitable for a wide range of basic plasma science experiments in areas such as electrostatic turbulence and transport, magnetic relaxation, and high power microwave (HPM)-plasma interactions. The HelCat device is based on dual plasma sources located at opposite ends of the 4 m long vacuum chamber - an RF helicon source at one end and a thermionic cathode at the other. Thirteen coils provide an axial magnetic field B >= 0.220 T that can be configured individually to give various magnetic configurations (e.g. solenoid, mirror, cusp). Additional plasma sources, such as a compact coaxial plasma gun, are also utilized in some experiments, and can be located either along the chamber for perpendicular (to the background magnetic field) plasma injection, or at one of the ends for parallel injection. Using the multiple plasma sources, a wide range of plasma parameters can be obtained. Here, the HelCat device is described in detail and some examples of results from previous and ongoing experiments are given. Additionally, examples of planned experiments and device modifications are also discussed.

The Prebiotic Inulin Aggravates Accelerated Atherosclerosis in Hypercholesterolemic APOE*3-Leiden Mice.

PubMed

Hoving, Lisa R; de Vries, Margreet R; de Jong, Rob C M; Katiraei, Saeed; Pronk, Amanda; Quax, Paul H A; van Harmelen, Vanessa; Willems van Dijk, Ko

2018-02-03

The prebiotic inulin has proven effective at lowering inflammation and plasma lipid levels. As atherosclerosis is provoked by both inflammation and hyperlipidemia, we aimed to determine the effect of inulin supplementation on atherosclerosis development in hypercholesterolemic APOE*3-Leiden ( E3L ) mice. Male E3L mice were fed a high-cholesterol (1%) diet, supplemented with or without 10% inulin for 5 weeks. At week 3, a non-constrictive cuff was placed around the right femoral artery to induce accelerated atherosclerosis. At week 5, vascular pathology was determined by lesion thickness, vascular remodeling, and lesion composition. Throughout the study, plasma lipids were measured and in week 5, blood monocyte subtypes were determined using flow cytometry analysis. In contrast to our hypothesis, inulin exacerbated atherosclerosis development, characterized by increased lesion formation and outward vascular remodeling. The lesions showed increased number of macrophages, smooth muscle cells, and collagen content. No effects on blood monocyte composition were found. Inulin significantly increased plasma total cholesterol levels and total cholesterol exposure. In conclusion, inulin aggravated accelerated atherosclerosis development in hypercholesterolemic E3L mice, accompanied by adverse lesion composition and outward remodeling. This process was not accompanied by differences in blood monocyte composition, suggesting that the aggravated atherosclerosis development was driven by increased plasma cholesterol.

The Prebiotic Inulin Aggravates Accelerated Atherosclerosis in Hypercholesterolemic APOE*3-Leiden Mice

PubMed Central

de Jong, Rob C. M.; Katiraei, Saeed; Pronk, Amanda; van Harmelen, Vanessa

2018-01-01

The prebiotic inulin has proven effective at lowering inflammation and plasma lipid levels. As atherosclerosis is provoked by both inflammation and hyperlipidemia, we aimed to determine the effect of inulin supplementation on atherosclerosis development in hypercholesterolemic APOE*3-Leiden (E3L) mice. Male E3L mice were fed a high-cholesterol (1%) diet, supplemented with or without 10% inulin for 5 weeks. At week 3, a non-constrictive cuff was placed around the right femoral artery to induce accelerated atherosclerosis. At week 5, vascular pathology was determined by lesion thickness, vascular remodeling, and lesion composition. Throughout the study, plasma lipids were measured and in week 5, blood monocyte subtypes were determined using flow cytometry analysis. In contrast to our hypothesis, inulin exacerbated atherosclerosis development, characterized by increased lesion formation and outward vascular remodeling. The lesions showed increased number of macrophages, smooth muscle cells, and collagen content. No effects on blood monocyte composition were found. Inulin significantly increased plasma total cholesterol levels and total cholesterol exposure. In conclusion, inulin aggravated accelerated atherosclerosis development in hypercholesterolemic E3L mice, accompanied by adverse lesion composition and outward remodeling. This process was not accompanied by differences in blood monocyte composition, suggesting that the aggravated atherosclerosis development was driven by increased plasma cholesterol. PMID:29401645

Air plasma spray processing and electrochemical characterization of SOFC composite cathodes

NASA Astrophysics Data System (ADS)

White, B. D.; Kesler, O.; Rose, Lars

Air plasma spraying has been used to produce porous composite cathodes containing (La 0.8Sr 0.2) 0.98MnO 3- y (LSM) and yttria-stabilized zirconia (YSZ) for use in solid oxide fuel cells (SOFCs). Preliminary investigations focused on determining the range of plasma conditions under which each of the individual materials could be successfully deposited. A range of conditions was thereby determined that was suitable for the deposition of a composite cathode from pre-mixed LSM and YSZ powders. A number of composite cathodes were produced using different combinations of parameter values within the identified range according to a Uniform Design experimental grid. Coatings were then characterized for composition and microstructure using EDX and SEM. As a result of these tests, combinations of input parameter values were identified that are best suited to the production of coatings with microstructures appropriate for use in SOFC composite cathodes. A selection of coatings representative of the types of observed microstructures were then subjected to electrochemical testing to evaluate the performance of these cathodes. From these tests, it was found that, in general, the coatings that appeared to have the most suitable microstructures also had the highest electrochemical performances, provided that the deposition efficiency of both phases was sufficiently high.

Hydrogen storage and hydrolysis properties of core-shell structured Mg-MFx (M=V, Ni, La and Ce) nano-composites prepared by arc plasma method

NASA Astrophysics Data System (ADS)

Mao, Jianfeng; Zou, Jianxin; Lu, Chong; Zeng, Xiaoqin; Ding, Wenjiang

2017-10-01

In this work, core-shell structured Mg-MFx (M = V, Ni, La and Ce) nano-composites are prepared by using arc plasma method. The particle size distribution, phase components, microstructures, hydrogen sorption properties of these composites and hydrolysis properties of their corresponding hydrogenated powders are carefully investigated. It is shown that the addition of MFx through arc plasma method can improve both the hydrogen absorption kinetics of Mg and the hydrolysis properties of corresponding hydrogenated powders. Among them, the Mg-NiF2 composite shows the best hydrogen absorption properties at relatively low temperatures, which can absorb 3.26 wt% of H2 at 373 K in 2 h. Such rapid hydrogen absorption rate is mainly due to the formation of Mg2Ni and MgF2 on Mg particles during arc evaporation and condensation. In contrast, measurements also show that the hydrogenated Mg-VF3 composite has the lowest peak desorption temperature and the fastest hydrolysis rate among all the hydrogenated Mg-MFx composites. The less agglomeration tendency of Mg particles and VO2 covered on MgH2 particles account for the reduced hydrogen desorption temperature and enhanced hydrolysis rate.

Experimental studies of radiation resistance of boron nitride, C2C ceramics Al2O3 and carbon-fiber composites using a PF-1000 plasma-focus device

NASA Astrophysics Data System (ADS)

Gribkov, V. A.; Tuniz, C.; Demina, E. V.; Dubrovsky, A. V.; Pimenov, V. N.; Maslyaev, S. V.; Gaffka, R.; Gryaznevich, M.; Skladnik-Sadowska, E.; Sadowski, M. J.; Miklaszewski, R.; Paduch, M.; Scholz, M.

2011-04-01

This paper reports on experiments undertaken to compare the radiation resistance of two types of ceramics, boron nitride (BN) and pure alumina (Al2O3), which are used in a TAEA antenna coil installed in the MAST spherical tokamak. Samples of the investigated materials (bulk BN and a 20 μm film of Al2O3 on Al substrate) were exposed on the axis of the plasma-focus PF-1000 device, which can emit intense streams of hot plasma (v≈107 cm s-1 and Npl≈1018 cm-3) and fast deuteron beams (Ei≈100 keV). The most powerful plasma-ion pulse lasted 0.2-1.0 μs and its intensity decayed in about 100 μs. The irradiation process was diagnosed using fast optical cameras, laser interferometry and optical spectrometry. Experiments were performed at power flux densities equal to 109-1010 W cm-2 or 108-109 W cm-2 during the most powerful stage of the interaction process. The irradiated specimens were investigated by means of optical microscopy and x-ray structure analysis (XRSA). It was shown that at 1010 W cm-2 pulses the Al2O3 coating was completely evaporated, whereas a surface of the BN sample became smoother than in the virgin one. A direct comparison of both samples after the action of 108 W cm-2 pulses demonstrated a wave-like structure (more distinct on Al2O3). Weighing of these samples showed, however, that the evaporation of BN was about two times stronger than that of Al2O3 in spite of the lower irradiation flux; the XRSA showed no evidence of cracking of Al2O3 after these pulses. The insulation properties of Al2O3 did not decline, and the Al2O3 coating may be potentially more beneficial, provided that it is kept below its melting point. Characteristic features of damages of a material based on the carbon-fiber composite with additions of silicium carbide (SiC; 8-40% volumetric) were also investigated. It was found that at q=109 W cm-2, the surface erosion is associated with sputtering and evaporation. The degree of this erosion depends on the fibers' orientation in relation to the direction of the plasma-ion streams, and on the percentage of the SiC admixture.

A simple model of hohlraum power balance and mitigation of SRS

DOE PAGES

Albright, Brian J.; Montgomery, David S.; Yin, Lin; ...

2016-04-01

A simple energy balance model has been obtained for laser-plasma heating in indirect drive hohlraum plasma that allows rapid temperature scaling and evolution with parameters such as plasma density and composition. Furthermore, this model enables assessment of the effects on plasma temperature of, e.g., adding high-Z dopant to the gas fill or magnetic fields.

Preparation of a porcine plasma protein composite film and its application.

PubMed

Lee, Ji-Hyun; Song, Kyung Bin

2015-01-01

To use blood released from slaughtering houses, a porcine plasma protein (PPP)/nanoclay composite film was prepared. The tensile strength and elongation at break values of the PPP composite film with 5% nanoclay were 10.01 MPa and 6.55%, respectively. The PPP composite film containing 1% grapefruit seed extract (GSE) was applied to pork meat, and the populations of inoculated Escherichia coli O157:H7 and Listeria monocytogenes in the pork meat packaged with the PPP composite film decreased by 0.8 and 1.0 log CFU/g, respectively, after 7 days of storage compared to the populations of the control. In addition, thiobarbituric acid values in the pork meat packaged with the PPP composite film were less than those of the control sample during storage. These results suggest that the PPP nanocomposite film containing 1% GSE can be used as a packaging material to maintain the quality of pork meat.

Friction and wear of plasma-sprayed coatings containing cobalt alloys from 25 deg to 650 deg in air

NASA Technical Reports Server (NTRS)

Sliney, H. E.; Jacobson, T. P.

1979-01-01

Four different compositions of self-lubricating, plasma-sprayed, composite coatings with calcium fluoride dispersed throughout cobalt alloy-silver matrices were evaluated on a friction and wear apparatus. In addition, coatings of the cobalt alloys alone and one coating with a nickel alloy-silver matrix were evaluated for comparison. The wear specimens consisted of two, diametrically opposed, flat rub shoes sliding on the coated, cylindrical surface of a rotating disk. Two of the cobalt composite coatings gave a friction coefficient of about 0.25 and low wear at room temperature, 400 and 650 C. Wear rates were lower than those of the cobalt alloys alone or the nickel alloy composite coating. However, oxidation limited the maximum useful temperature of the cobalt composite coating to about 650 C compared to about 900 C for the nickel composite coating.

Interface structure and properties of CNTs/Cu composites fabricated by electroless deposition and spark plasma sintering

NASA Astrophysics Data System (ADS)

Wang, Hu; Zhang, Zhao-Hui; Hu, Zheng-Yang; Song, Qi; Yin, Shi-Pan

2018-01-01

In this paper, we fabricated a novel copper matrix composites reinforced by carbon nanotubes (CNTs) using electroless deposition (ED) and spark plasma sintering technique. Microstructure, mechanical, electric conductivity, and thermal properties of the CNTs/Cu composites were investigated. The results show that a favorable interface containing C-O and O-Cu bond was formed between CNTs and matrix when the CNTs were coated with nano-Cu by ED method. Thus, we accomplished the uniformly dispersed CNTs in the CNTs/Cu powders and compacted composites, which eventually leads to the enhancement of the mechanical properties of the CNTs/Cu composites in the macro-scale environment. However, the interface structure can hinder the movement of carriers and free electrons and increase the interface thermal resistance, which leads to modest decrease of electrical and thermal conductivity of the CNTs/Cu composites.

Childhood obesity treatment; Effects on BMI SDS, body composition, and fasting plasma lipid concentrations.

PubMed

Nielsen, Tenna Ruest Haarmark; Fonvig, Cilius Esmann; Dahl, Maria; Mollerup, Pernille Maria; Lausten-Thomsen, Ulrik; Pedersen, Oluf; Hansen, Torben; Holm, Jens-Christian

2018-01-01

The body mass index (BMI) standard deviation score (SDS) may not adequately reflect changes in fat mass during childhood obesity treatment. This study aimed to investigate associations between BMI SDS, body composition, and fasting plasma lipid concentrations at baseline and during childhood obesity treatment. 876 children and adolescents (498 girls) with overweight/obesity, median age 11.2 years (range 1.6-21.7), and median BMI SDS 2.8 (range 1.3-5.7) were enrolled in a multidisciplinary outpatient treatment program and followed for a median of 1.8 years (range 0.4-7.4). Height and weight, body composition measured by dual-energy X-ray absorptiometry, and fasting plasma lipid concentrations were assessed at baseline and at follow-up. Lipid concentrations (total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), non-HDL, and triglycerides (TG)) were available in 469 individuals (264 girls). Linear regressions were performed to investigate the associations between BMI SDS, body composition indices, and lipid concentrations. At baseline, BMI SDS was negatively associated with concentrations of HDL (p = 6.7*10-4) and positively with TG (p = 9.7*10-6). Reductions in BMI SDS were associated with reductions in total body fat percentage (p<2*10-16) and percent truncal body fat (p<2*10-16). Furthermore, reductions in BMI SDS were associated with improvements in concentrations of TC, LDL, HDL, non-HDL, LDL/HDL-ratio, and TG (all p <0.0001). Changes in body fat percentage seemed to mediate the changes in plasma concentrations of TC, LDL, and non-HDL, but could not alone explain the changes in HDL, LDL/HDL-ratio or TG. Among 81 individuals with available lipid concentrations, who increased their BMI SDS, 61% improved their body composition, and 80% improved their lipid concentrations. Reductions in the degree of obesity during multidisciplinary childhood obesity treatment are accompanied by improvements in body composition and fasting plasma lipid concentrations. Even in individuals increasing their BMI SDS, body composition and lipid concentrations may improve.

Childhood obesity treatment; Effects on BMI SDS, body composition, and fasting plasma lipid concentrations

PubMed Central

Fonvig, Cilius Esmann; Dahl, Maria; Mollerup, Pernille Maria; Lausten-Thomsen, Ulrik; Pedersen, Oluf; Hansen, Torben; Holm, Jens-Christian

2018-01-01

Objective The body mass index (BMI) standard deviation score (SDS) may not adequately reflect changes in fat mass during childhood obesity treatment. This study aimed to investigate associations between BMI SDS, body composition, and fasting plasma lipid concentrations at baseline and during childhood obesity treatment. Methods 876 children and adolescents (498 girls) with overweight/obesity, median age 11.2 years (range 1.6–21.7), and median BMI SDS 2.8 (range 1.3–5.7) were enrolled in a multidisciplinary outpatient treatment program and followed for a median of 1.8 years (range 0.4–7.4). Height and weight, body composition measured by dual-energy X-ray absorptiometry, and fasting plasma lipid concentrations were assessed at baseline and at follow-up. Lipid concentrations (total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), non-HDL, and triglycerides (TG)) were available in 469 individuals (264 girls). Linear regressions were performed to investigate the associations between BMI SDS, body composition indices, and lipid concentrations. Results At baseline, BMI SDS was negatively associated with concentrations of HDL (p = 6.7*10−4) and positively with TG (p = 9.7*10−6). Reductions in BMI SDS were associated with reductions in total body fat percentage (p<2*10−16) and percent truncal body fat (p<2*10−16). Furthermore, reductions in BMI SDS were associated with improvements in concentrations of TC, LDL, HDL, non-HDL, LDL/HDL-ratio, and TG (all p <0.0001). Changes in body fat percentage seemed to mediate the changes in plasma concentrations of TC, LDL, and non-HDL, but could not alone explain the changes in HDL, LDL/HDL-ratio or TG. Among 81 individuals with available lipid concentrations, who increased their BMI SDS, 61% improved their body composition, and 80% improved their lipid concentrations. Conclusion Reductions in the degree of obesity during multidisciplinary childhood obesity treatment are accompanied by improvements in body composition and fasting plasma lipid concentrations. Even in individuals increasing their BMI SDS, body composition and lipid concentrations may improve. PMID:29444114

A DOE/Fusion Energy Sciences Research/Education Program at PVAMU Study of Rotamak Plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Tian-Sen; Saganti, Premkumar

During recent years (2004-2015), with DOE support, the PVAMU plasma research group accomplished new instrumentation development, conducted several new plasma experiments, and is currently poised to advance with standing-wave microwave plasma propulsion research. On the instrumentation development, the research group completed: (i) building a new plasma chamber with metal CF flanges, (ii) setting up of a 6kW/2450MHz microwave input system as an additional plasma heating source at our rotamak plasma facility, (iii) installation of one programmatic Kepco ATE 6-100DMG fast DC current supply system used in rotamak plasma shape control experiment, built a new microwave, standing-wave experiment chamber and (iv)more » established a new plasma lab with field reversal configuration capability utilizing 1MHz/200kW RF (radio frequency) wave generator. Some of the new experiments conducted in this period also include: (i) assessment of improved magnetic reconnection at field-reversed configuration (FRC) plasma, (ii) introduction of microwave heating experiments, and (iii) suppression of n = 1 tilt instability by one coil with a smaller current added inside the rotamak’s central pipe. These experiments led to publications in Physical Review Letters, Reviews of Scientific Instruments, Division of Plasma Physics (DPP) of American Physical Society (APS) Reports, Physics of Plasmas Controlled Fusion, and Physics of Plasmas (between 2004 and 2015). With these new improvements and advancements, we also initiated and accomplished design and fabrication of a plasma propulsion system. Currently, we are assembling a plasma propulsion experimental system that includes a 5kW helicon plasma source, a 25 cm diameter plasma heating chamber with 1MHz/200kW RF power rotating magnetic field, and a 60 cm diameter plasma exhaust chamber, and expect to achieve a plasma mass flow of 0.1g/s with 60km/s ejection. We anticipate several propulsion applications in near future as we advance our capabilities. Apart from scientific staff members, several students (more than ten undergraduate students and two graduate students from several engineering and science disciplines) were supported and worked on the equipment and experiments during the award period. We also anticipate that these opportunities with current expansions may result in a graduate program in plasma science and propulsion engineering disciplines. *Corresponding Author – Dr. Saganti, Regents Professor and Professor of Physics – pbsaganti@pvamu.edu« less

CHARACTERIZATION OF FATTY ACID COMPOSITION IN BONE MARROW FLUID FROM POSTMENOPAUSAL WOMEN: MODIFICATION AFTER HIP FRACTURE

PubMed Central

Miranda, Melissa; Pino, Ana María; Fuenzalida, Karen; Rosen, Clifford J.; Seitz, Germán; Rodríguez, J. Pablo

2016-01-01

Bone marrow adipose tissue (BMAT) is associated with low bone mass, although the functional consequences for skeletal maintenance of increased BMAT are currently unclear. BMAT might have a role in systemic energy metabolism, and could be an energy source as well as an endocrine organ for neighboring bone cells, releasing cytokines, adipokines and free fatty acids into the bone marrow microenvironment. The aim of the present report was to compare the fatty acid composition in the bone marrow supernatant fluid (BMSF) and blood plasma of postmenopausal women women (65 to 80 years old). BMSF was obtained after spinning the aspirated bone marrow samples; donors were classified as control, osteopenic or osteoporotic after dual-energy X-ray absorptiometry. Total lipids from human bone marrow fluid and plasma were extracted, converted to the corresponding methyl esters, and finally analyzed by a gas chromatographer coupled with a mass spectrometer. Results showed that fatty acid composition in BMSF was dynamic and distinct from blood plasma, implying significance in the locally produced lipids. The fatty acid composition in the BMSF was enriched in saturated fatty acid and decreased in unsaturated fatty acids as compared to blood plasma, but this relationship switched in women who suffered a hip fracture. On the other hand, there was no relationship between BMSF and bone mineral density. In conclusion, lipid composition of BMSF is distinct from the circulatory compartment, most likely reflecting the energy needs of the marrow compartment. PMID:27416518

First Plasma Results from the Levitated Dipole Experiment

NASA Astrophysics Data System (ADS)

Garnier, Darren T.

2005-04-01

On August 13, 2004, the first plasma physics experiments were conducted using the Levitated Dipole Experiment(LDX)http://www.psfc.mit.edu/ldx/. LDX was built at MIT's Plasma Science and Fusion Center as a joint research project of Columbia University and MIT. LDX is a first-of-its-kind experiment incorporating three superconducting magnets and exploring the physics of high-temperature plasma confined by dipole magnetic fields, similar to planetary magnetospheres. It will test recent theories that suggest that stable, high-β plasma can be confined without good curvature or magnetic shear, instead using plasma compressibility to provide stability. (Plasma β is the ratio of plasma pressure to magnetic pressure.) In initial experiments, 750 kA of current was induced in the dipole coil which was physically supported in the center of the 5 m diameter vacuum chamber. Deuterium plasma discharges, lasting from 4 to 10 seconds, were formed with multi-frequency ECRH microwave heating of up to 6.2 kW. Each plasma contained a large fraction of energetic and relativistic electrons that created a significant pressure that caused outward expansion of the magnetic field. Reconstruction of the magnetic equilibrium from external magnetic diagnostics indicate local peak plasma β 7 %. Along with an overview of the LDX device, results from numerous diagnostics operating during this initial supported campaign measuring the basic plasma parameters will be presented. In addition, observations of instabilities leading to rapid plasma loss and the effects of changing plasma compressibility will be explored.

Active experiments in space; Proceedings of the Topical Meeting of the Interdisciplinary Scientific Commission D (Meeting D3) of the COSPAR 28th Plenary Meeting, The Hague, Netherlands, June 25-July 6, 1990

NASA Astrophysics Data System (ADS)

Torbert, R.

1992-12-01

The present volume on active experiments in space discusses dynamic trapping of electrons in the Porcupine ionospheric ion beam experiment, plasma wave observations during electron gun experiments on ISEE-1, spatial coherence and electromagnetic wave generation during electron beam experiments in space, and recent experimental measurements of space platform charging at LEO altitudes. Attention is given to high voltage spheres in an unmagnetized plasma, energetic ion emission for active spacecraft control, the collective gyration of a heavy ion cloud in a magnetized plasma, and remote sensing of artificial luminous clouds by lidars. Topics addressed include modulation of the background flux of energetic particles by artificial injection, wave measurements in active experiments on plasma beam injection, field formation around negatively biased solar arrays in the LEO-plasma, and the registration of ELF waves in rocket-satellite experiments with plasma injection.

Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Halbig, Michael Charles; Puleo, Bernadette J.; Costa, Gustavo; Mccue, Terry R.

2017-01-01

This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiC-SiC Ceramic Matrix Composite (CMC) combustors particularly under the NASA Environmentally Responsible Aviation, Fundamental Aeronautics and Transformative Aeronautics Concepts Programs. The emphases have been placed on the current design challenges of the 2700-3000F capable environmental barrier coatings for low NOX emission combustors for next generation turbine engines by using advanced plasma spray based processes, and the coating processing and integration with SiC-SiC CMCs and component systems. The developments also have included candidate coating composition system designs, degradation mechanisms, performance evaluation and down-selects; the processing optimizations using TriplexPro Air Plasma Spray Low Pressure Plasma Spray (LPPS), Plasma Spray Physical Vapor Deposition and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements under the NASA development programs, as demonstrated in the simulated engine high heat flux, combustion environments, in conjunction with high heat flux, mechanical creep and fatigue loading testing conditions.

The Plasma Interaction Experiment (PIX) description and test program. [electrometers

NASA Technical Reports Server (NTRS)

Ignaczak, L. R.; Haley, F. A.; Domino, E. J.; Culp, D. H.; Shaker, F. J.

1978-01-01

The plasma interaction experiment (PIX) is a battery powered preprogrammed auxiliary payload on the LANDSAT-C launch. This experiment is part of a larger program to investigate space plasma interactions with spacecraft surfaces and components. The varying plasma densities encountered during available telemetry coverage periods are deemed sufficient to determine first order interactions between the space plasma environment and the biased experimental surfaces. The specific objectives of the PIX flight experiment are to measure the plasma coupling current and the negative voltage breakdown characteristics of a solar array segment and a gold plated steel disk. Measurements will be made over a range of surface voltages up to plus or minus kilovolt. The orbital environment will provide a range of plasma densities. The experimental surfaces will be voltage biased in a preprogrammed step sequence to optimize the data returned for each plasma region and for the available telemetry coverage.

Preliminary feasibility study of pallet-only mode for magnetospheric and plasmas in space payloads, volume 4

NASA Technical Reports Server (NTRS)

1976-01-01

Results of studies performed on the magnetospheric and plasma portion of the AMPS are presented. Magnetospheric and plasma in space experiments and instruments are described along with packaging (palletization) concepts. The described magnetospheric and plasma experiments were considered as separate entities. Instrumentation ospheric and plasma experiments were considered as separate entities. Instrumentation requirements and operations were formulated to provide sufficient data for unambiguous interpretation of results without relying upon other experiments of the series. Where ground observations are specified, an assumption was made that large-scale additions or modifications to existing facilities were not required.

Model polymer etching and surface modification by a time modulated RF plasma jet: role of atomic oxygen and water vapor

NASA Astrophysics Data System (ADS)

Luan, P.; Knoll, A. J.; Wang, H.; Kondeti, V. S. S. K.; Bruggeman, P. J.; Oehrlein, G. S.

2017-01-01

The surface interaction of a well-characterized time modulated radio frequency (RF) plasma jet with polystyrene, poly(methyl methacrylate) and poly(vinyl alcohol) as model polymers is investigated. The RF plasma jet shows fast polymer etching but mild chemical modification with a characteristic carbonate ester and NO formation on the etched surface. By varying the plasma treatment conditions including feed gas composition, environment gaseous composition, and treatment distance, we find that short lived species, especially atomic O for Ar/1% O2 and 1% air plasma and OH for Ar/1% H2O plasma, play an essential role for polymer etching. For O2 containing plasma, we find that atomic O initiates polymer etching and the etching depth mirrors the measured decay of O atoms in the gas phase as the nozzle-surface distance increases. The etching reaction probability of an O atom ranging from 10-4 to 10-3 is consistent with low pressure plasma research. We also find that adding O2 and H2O simultaneously into Ar feed gas quenches polymer etching compared to adding them separately which suggests the reduction of O and OH density in Ar/O2/H2O plasma.

Single-step generation of metal-plasma polymer multicore@shell nanoparticles from the gas phase.

PubMed

Solař, Pavel; Polonskyi, Oleksandr; Olbricht, Ansgar; Hinz, Alexander; Shelemin, Artem; Kylián, Ondřej; Choukourov, Andrei; Faupel, Franz; Biederman, Hynek

2017-08-17

Nanoparticles composed of multiple silver cores and a plasma polymer shell (multicore@shell) were prepared in a single step with a gas aggregation cluster source operating with Ar/hexamethyldisiloxane mixtures and optionally oxygen. The size distribution of the metal inclusions as well as the chemical composition and the thickness of the shells were found to be controlled by the composition of the working gas mixture. Shell matrices ranging from organosilicon plasma polymer to nearly stoichiometric SiO 2 were obtained. The method allows facile fabrication of multicore@shell nanoparticles with tailored functional properties, as demonstrated here with the optical response.

Reverse-osmosis membranes by plasma polymerization

NASA Technical Reports Server (NTRS)

Hollahan, J. R.; Wydeven, T.

1972-01-01

Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.

Using the Tritium Plasma Experiment to evaluate ITER PFC safety

NASA Astrophysics Data System (ADS)

Longhurst, Glen R.; Anderl, Robert A.; Bartlit, John R.; Causey, Rion A.; Haines, John R.

The Tritium Plasma Experiment was assembled at Sandia National Laboratories, Livermore to investigate interactions between dense plasmas at low energies and plasma-facing component materials. This apparatus has the unique capability of replicating plasma conditions in a tokamak divertor with particle flux densities of 2 x 10(exp 19) ions/((sq cm)(s)) and a plasma temperature of about 15 eV using a plasma that includes tritium. With the closure of the Tritium Research Laboratory at Livermore, the experiment was moved to the Tritium Systems Test Assembly facility at Los Alamos National Laboratory. An experimental program has been initiated there using the Tritium Plasma Experiment to examine safety issues related to tritium in plasma-facing components, particularly the ITER divertor. Those issues include tritium retention and release characteristics, tritium permeation rates and transient times to coolant streams, surface modification and erosion by the plasma, the effects of thermal loads and cycling, and particulate production. A considerable lack of data exists in these areas for many of the materials, especially beryllium, being considered for use in ITER. Not only will basic material behavior with respect to safety issues in the divertor environment be examined, but innovative techniques for optimizing performance with respect to tritium safety by material modification and process control will be investigated. Supplementary experiments will be carried out at the Idaho National Engineering Laboratory and Sandia National Laboratory to expand and clarify results obtained on the Tritium Plasma Experiment.

Studying the influence of nanodiamonds over the elasticity of polymer/nanodiamond composites for biomedical application

NASA Astrophysics Data System (ADS)

Hikov, T.; Mitev, D.; Radeva, E.; Iglic, A.; Presker, R.; Daniel, M.; Sepitka, J.; Krasteva, N.; Keremidarska, M.; Cvetanov, I.; Pramatarova, L.

2014-12-01

The combined unique properties offered by organic and inorganic constituents within a single material on a nanoscale level make nanocomposites attractive for the next generation of biocompatible materials. The composite materials of the detonation nanodiamond/polymer type possess spatial organization of components with new structural features and physical properties, as well as complex functions due to the strong synergistic effects between the nanoparticles and the polymer [1]. The plasma polymerization (PP) method was chosen to obtain composites of silicon-based polymers, in which detonation generated nanodiamond (DND) particles were incorporated. The composite layers are homogeneous, chemically resistant, thermally and mechanically stable, thus allowing a large amount of biological components to be loaded onto their surface and to be used in tissue engineering, regenerative medicine, implants, stents, biosensors and other medical and biological devices. Mesenchymal stem cells (MSCs) are the main focus of research in regenerative medicine due to their extraordinary potential to differentiate into different kinds of cells including osteoblasts, which are needed for various bone disease treatments. However, for optimal usage of MSCs knowledge about the factors that influence their initial distribution in the human system, tissue-specific activation and afterwards differentiation into osteoblasts is required. In recent studies it was found that one of these factors is the elasticity of the substrates [2]. The choice of the proper material which specifically guides the differentiation of stem cells even in the absence of growth factors is very important when building modern strategy for bone regeneration. One of the reasons for there not being many studies in this area worldwide is the lack of suitable biomaterials which support these kinds of experiments. The goal of this study is to create substrates suitable for cell culture with a range of mechanical properties (namely elasticity and hardness) using composite layers (PPHMDS-DND) of plasma polymerized (PP) hexamethyldisiloxane (HMDS) and detonation generated nanodiamond (DND). The samples' elastic modulae and hardness were measured by CSM Ultra Nanoindentation Tester.

The effect of dietary betaine in Eimeria acervulina-infected chicks.

PubMed

Matthews, J O; Southern, L L

2000-01-01

Two experiments were conducted to evaluate the effect of dietary betaine in broiler chicks with either chronic (CHR; 2.5 x 10(5) sporulated oocysts on Day 1, 4, 7, and 10) or acute (ACT; 1.0 x 10(6) sporulated oocysts on Day 1) Eimeria acervulina infections. Three hundred (Experiment 1) or 600 (Experiment 2), 4-d-old male chicks were used in the 14-d experiments. In both experiments, a 2 x 3 factorial arrangement of treatments was used: two levels of betaine (0 or 0.075%) and three levels of coccidiosis infection (uninfected, CHR, or ACT). Each treatment was replicated five (Experiment 1) or 10 (Experiment 2) times with 10 chicks per replicate. In Experiment 1, the ACT infection decreased (P < 0.01) average daily gain and gain:feed, and the CHR infection decreased (P < 0.02) average daily gain. The ACT and CHR infections decreased (P < 0.06) Day 7 plasma carotenoids and Day 14 plasma total protein, and the ACT infection also decreased (P < 0.06) Day 7 plasma total protein. Average daily gain and Day 7 plasma total protein were increased in CHR chicks fed betaine but were decreased in uninfected chicks fed betaine (CHR x betaine; P < 0.09). Chicks fed betaine had decreased (P < 0.06) Day 7 plasma carotenoids. In Experiment 2 the CHR and ACT infections decreased (P < 0.01) average daily gain, average daily feed intake, grain:feed ratio, Days 7 and 14 plasma carotenoids, and Day 7 plasma total protein. Chicks fed betaine had increased (P < 0.07) average daily gains, gain:feed ratios, and lesion scores. Day 14 plasma carotenoids and plasma total protein were decreased in uninfected chicks fed betaine but were increased in CHR chicks fed betaine (CHR x betaine; P < 0.04); plasma carotenoids also were increased in ACT chicks fed betaine (ACT x betaine; P < 0.05). Betaine did not consistently affect growth performance, plasma constituents, or lesion score in CHR or ACT coccidiosis-infected chicks.

Atomic Precision Plasma Processing - Modeling Investigations

NASA Astrophysics Data System (ADS)

Rauf, Shahid

2016-09-01

Sub-nanometer precision is increasingly being required of many critical plasma processes in the semiconductor industry. Some of these critical processes include atomic layer etch and plasma enhanced atomic layer deposition. Accurate control over ion energy and ion / radical composition is needed during plasma processing to meet the demanding atomic-precision requirements. While improvements in mainstream inductively and capacitively coupled plasmas can help achieve some of these goals, newer plasma technologies can expand the breadth of problems addressable by plasma processing. Computational modeling is used to examine issues relevant to atomic precision plasma processing in this paper. First, a molecular dynamics model is used to investigate atomic layer etch of Si and SiO2 in Cl2 and fluorocarbon plasmas. Both planar surfaces and nanoscale structures are considered. It is shown that accurate control of ion energy in the sub-50 eV range is necessary for atomic scale precision. In particular, if the ion energy is greater than 10 eV during plasma processing, several atomic layers get damaged near the surface. Low electron temperature (Te) plasmas are particularly attractive for atomic precision plasma processing due to their low plasma potential. One of the most attractive options in this regard is energetic-electron beam generated plasma, where Te <0.5 eV has been achieved in plasmas of molecular gases. These low Te plasmas are computationally examined in this paper using a hybrid fluid-kinetic model. It is shown that such plasmas not only allow for sub-5 eV ion energies, but also enable wider range of ion / radical composition. Coauthors: Jun-Chieh Wang, Jason Kenney, Ankur Agarwal, Leonid Dorf, and Ken Collins.

Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling.

PubMed

Lee, Hyo-Chang; Chung, Chin-Wook

2015-10-20

Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics.

Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling

PubMed Central

Lee, Hyo-Chang; Chung, Chin-Wook

2015-01-01

Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics. PMID:26482650

Definition Study of a Coordinated Group of Experiments to Measure and Monitor the in situ Plasma and Electromagnetic Environment of a Polar Orbiting Space Shuttle.

DTIC Science & Technology

1985-09-01

instruments should be included in the SACS package: Mass Spectrometer - The ion/neutral quadrupole mass spectrometer obtains composition measurements of...contamination. The preferred direction is into the RAM. The field-of-view is _ 200 and t ie mass range is 1 to 64 AMU.- Energetic Particle Deteotors...Dimensions Dimensions Weight Item Stowed (cm) Deployed (cm) (kg) Ejected Recovery Mass Spectrometer N/A 15x7x7 bxbx6 12.7 N/A N/A Energetic Particle Det N

Soluble Fermentable Dietary Fibre (Pectin) Decreases Caloric Intake, Adiposity and Lipidaemia in High-Fat Diet-Induced Obese Rats

PubMed Central

Adam, Clare L.; Thomson, Lynn M.; Williams, Patricia A.; Ross, Alexander W.

2015-01-01

Consumption of a high fat diet promotes obesity and poor metabolic health, both of which may be improved by decreasing caloric intake. Satiety-inducing ingredients such as dietary fibre may be beneficial and this study investigates in diet-induced obese (DIO) rats the effects of high or low fat diet with or without soluble fermentable fibre (pectin). In two independently replicated experiments, young adult male DIO rats that had been reared on high fat diet (HF; 45% energy from fat) were given HF, low fat diet (LF; 10% energy from fat), HF with 10% w/w pectin (HF+P), or LF with 10% w/w pectin (LF+P) ad libitum for 4 weeks (n = 8/group/experiment). Food intake, body weight, body composition (by magnetic resonance imaging), plasma hormones, and plasma and liver lipid concentrations were measured. Caloric intake and body weight gain were greatest in HF, lower in LF and HF+P, and lowest in the LF+P group. Body fat mass increased in HF, was maintained in LF, but decreased significantly in LF+P and HF+P groups. Final plasma leptin, insulin, total cholesterol and triglycerides were lower, and plasma satiety hormone PYY concentrations were higher, in LF+P and HF+P than in LF and HF groups, respectively. Total fat and triglyceride concentrations in liver were greatest in HF, lower in LF and HF+P, and lowest in the LF+P group. Therefore, the inclusion of soluble fibre in a high fat (or low fat) diet promoted increased satiety and decreased caloric intake, weight gain, adiposity, lipidaemia, leptinaemia and insulinaemia. These data support the potential of fermentable dietary fibre for weight loss and improving metabolic health in obesity. PMID:26447990

Association between obesity-related biomarkers and cognitive and motor development in infants.

PubMed

Camargos, Ana Cristina R; Mendonça, Vanessa A; Oliveira, Katherine S C; de Andrade, Camila Alves; Leite, Hércules Ribeiro; da Fonseca, Sueli Ferreira; Vieira, Erica Leandro Marciano; Teixeira Júnior, Antônio Lúcio; Lacerda, Ana Cristina Rodrigues

2017-05-15

This study aimed to verify the association between obesity-related biomarkers and cognitive and motor development in infants between 6 and 24 months of age. A cross-sectional study was conducted with 50 infants and plasma levels of leptin, adiponectin, resistin, soluble tumor necrosis factor receptors 1 and 2 (sTNFR1 and sTNFR2), chemokines, brain-derived neurotrophic factor (BDNF), serum cortisol and redox status were measured. The Bayley-III test was utilized to evaluate cognitive and motor development, and multiple linear stepwise regression models were performed to verify the association between selected biomarkers and cognitive and motor development. A significant association was found among plasma leptin and sTNFR1 levels with cognitive composite scores, and these two independents variables together explained 37% of the variability of cognitive composite scores (p=0.001). Only plasma sTNFR1 levels were associated and explained 24% of the variability of motor composite scores (p=0.003). Plasma levels of sTNFR1 were associated with the increase in cognitive and motor development scores in infants between 6 and 24 months of age through a mechanism not directly related to excess body weight. Moreover, increase in plasma levels of leptin reduced the cognitive development in this age range. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of tungsten fiber reinforced-tungsten/copper composite for plasma facing component

NASA Astrophysics Data System (ADS)

He, Gang; Xu, Kunyuan; Guo, Shibin; Qian, Xueqiang; Yang, Zengchao; Liu, Guanghua; Li, Jiangtao

2014-12-01

W fiber reinforced-W/Cu composite is designed as a transition layer between CuCrZr heat sink material and W plasma facing material. A novel method was developed for the preparation of W fiber reinforced-W/Cu composite by combining combustion synthesis with centrifugal infiltration. Cu melt with a transient temperature over 2000 °C produced by the thermite reaction was infiltrated into the W powder and fiber bed with the assistance of a high gravity field. It was found that the W particles were sintered and bonded to the W fibers due to the high temperature produced by the thermite reaction. The bending strength of W/Cu composite improved 12.7% through W fibers reinforcement.

Incorporation of plasma-functionalized carbon nanostructures in composite laminates for interlaminar reinforcement and delamination crack monitoring

NASA Astrophysics Data System (ADS)

Kravchenko, O. G.; Pedrazzoli, D.; Kovtun, D.; Qian, X.; Manas-Zloczower, I.

2018-01-01

A new approach employing carbon nanostructure (CNS) buckypapers (BP) was used to prepare glass fiber/epoxy composite materials with enhanced resistance to delamination along with damage monitoring capability. The CNS-BP was subjected to plasma treatment to improve its wettability by epoxy and to promote stronger interfacial bonding. An increase up to 20% in interlaminar fracture toughness in mode I and mode II was observed in composite laminates incorporating CNS BP. Morphological analysis of the fracture surfaces indicated that failure in the conductive CNS layer provided a more effective energy dissipation mechanism, resulting in interlaminar fracture toughness increase. Moreover, fracture of the conductive CNS layer enabled damage monitoring of the composite by electrical resistance measurements upon delamination. The proposed approach provides multifunctional ply interphases, allowing to couple damage monitoring with interlaminar reinforcement of composite laminates.

[Characteristics of fatty acid composition of phosphatidyl cholines and sphingomyelins of low-density lipoproteins in the plasma of native inhabitants of Chukotka].

PubMed

Gerasimova, E N; Levachev, M M; Perova, N V; Nikitin, Iu P; Ozerova, I N

1986-01-01

Contents of cholesterol, triglycerides, high density lipoproteins (HDL) cholesterol as well as phospholipid and fatty acid compositions of phosphatidyl cholines and sphingomyelins in low density lipoproteins (LDL) were studied in blood plasma of Chukot aborigenes--Eskimos as compared with Moscow inhabitants. In Eskimos content of HDL cholesterol was higher but concentration of cholesterol and triglycerides was lower in blood plasma. In LDL concentration of sphingomyelins was increased and fatty acid composition of phosphatidyl cholines and sphingomyelins was altered where amount of polyunsaturated fatty acids was elevated (20:5 + 22:5 + 22:6). The specific characteristics of the LDL phospholipids observed in Eskimos might be responsible for the higher liquid properties of the surface monolayer in the lipoproteins; this alteration might be important for the lipoprotein properties and transformation as well as for the properties of membrane-bound enzymes, for synthesis of thromboxane and prostacyclins.

Plasma deposited polymers as gas sensitive films

NASA Astrophysics Data System (ADS)

Radeva, E.; Georgieva, V.; Lazarov, J.; Vergov, L.; Donkov, N.

2012-03-01

The possibility is presented of producing thin plasma polymers with desired properties by using nanofillers. Composite films are synthesized from a mixture of hexamethyldisiloxane (HMDSO) and detonation nanodiamond particles (DNDs). The chemical structure of the composite consists of DNDs distributed in the polymer matrix. The effect of DNDs on the humidity and ammonia sorptive properties of the polymers obtained is studied by measuring the mass changes as a result of gas sorption by using a quartz crystal microbalance (QCM). The results show that, in view of building a sensing element for measuring humidity, ammonia or other gases, it is possible to maximize the sensor sensitivity to a certain gas by using an appropriate concentration of DNDs in HMDSO. Thus, a high degree of sensor sensitivity, together with short response time and minimum hysteresis, can be achieved. Composites of plasma-polymerized HMDSO with DNDs can be used as gas sensitive layers for the development of quartz resonator sensors.

Deposition of nanocomposite Cu-TiO2 using heterogeneous colliding plasmas

NASA Astrophysics Data System (ADS)

Pandey, Pramod K.; Thareja, Raj K.; Singh, Ravi Pratap; Costello, John T.

2018-03-01

The formation of CuTiO2 nanocomposites has been observed in an experiment in which laser plasma plumes of Cu and Ti collide and stagnate in an oxygen atmosphere. The inherent advantage of this technique lies in its simplicity and flexibility where laser, target composition and geometry along with ambient atmosphere are all controllable parameters through which the stoichiometry of the deposited nanocomposites may be selected. The experiment has been performed at three oxygen ambient pressures 10-4, 10-2, 100 mbar and we observe its effect on stoichiometry, and morphology of the deposited nanocomposites. Here, we show how the stoichiometry of deposited nanocomposites can be readily controlled by changing just one parameter, namely the ambient oxygen pressure. The different peaks of photoluminescence spectra λ =390{ nm}( {E=3.18{ eV}} ) corresponding to the anatase phase of TiO2, along with the peaks at λ = 483 nm ( E = 2.56 eV) and 582 nm ( E = 2.13 eV) of deposited nanocomposites, shows the doping/blending effect on the band gaps which may potentially be of value in solar cell technology. The technique can, in principle, be extended to include nanocomposites of other materials making it potentially more widely applicable.

Preparation of carbon-functionalized magnetic graphene/mesoporous silica composites for selective extraction of miglitol and voglibose in rat plasma.

PubMed

Liu, Xiaodan; Feng, Jianan; Li, Yan

2018-05-15

In this work, magnetic graphene/mesoporous silica composites with carbon-functionalized pore-walls (denoted as MG@mSiO 2 -C composites) were synthesized and applied as restricted access matrix solid phase extraction (RAM-SPE) adsorbents for the determination of miglitol and voglibose in rat plasma by LC-MS/MS. The MG@mSiO 2 -C composites were synthesized by using the template (Cetyltrimethyl Ammonium Bromide, CTAB) as carbon source with sulfuric acid pretreated. The obtained nano-composites were proven to have many unique properties such as large specific surface area of 277.1 cm 2 g -1 , uniform mesopores with average pore size of 3.35 nm, and carbon-functionalized pore-walls. Taking advantage of the hydrophilic interaction between carbon and glycans, α-glucosidase inhibitors (miglitol and voglibose) could be directly extracted from rat plasma with no need of other pre-treatment procedures. The SPE conditions such as the adsorbent amount, elution solvent type, adsorption time and elution time were optimized. For both miglitol and voglibose, good linearities of 10-2000 ng mL -1 were obtained with determination coefficients (R 2 ) > 0.99. The intra-day and inter-day RSDs were 3.3-6.9% (n = 6) and 6.0-8.0% (n = 6), respectively. The recoveries were in the range of 99.9-100.4% and the sensitivities were as low as 2-2.5 ng mL -1 (LOD). This MG@mSiO 2 -C composites-based RAM-SPE method offers high extraction efficiency for the determination of α-glucosidase inhibitor in plasma. Copyright © 2018 Elsevier B.V. All rights reserved.

Manual modification and plasma exposure of boron nitride ceramic to study Hall effect thruster plasma channel material erosion

NASA Astrophysics Data System (ADS)

Satonik, Alexander J.

Worn Hall effect thrusters (HET) show a variety of unique microstructures and elemental compositions in the boron nitride thruster channel walls. Worn thruster channels are typically created by running test thrusters in vacuum chambers for hundreds of hours. Studies were undertaken to manually modify samples of boron nitride without the use of a hall effect thruster. Samples were manually abraded with an abrasive blaster and sandpaper, in addition to a vacuum heater. Some of these samples were further exposed to a xenon plasma in a magnetron sputter device. Sandpaper and abrasive blaster tests were used to modify surface roughness values of the samples from 10,000 A to 150,000 A, matching worn thruster values. Vacuum heat treatments were performed on samples. These treatments showed the ability to modify chemical compositions of boron nitride samples, but not in a manner matching changes seen in worn thruster channels. Plasma erosion rate was shown to depend on the grade of the BN ceramic and the preparation of the surface prior to plasma exposure. Abraded samples were shown to erode 43% more than their pristine counterparts. Unique surface features and elemental compositions on the worn thruster channel samples were overwritten by new surface features on the ceramic grains. The microscope images of the ceramic surface show that the magnetron plasma source rounded the edges of the ceramic grains to closely match the worn HET surface. This effect was not as pronounced in studies of ion beam bombardment of the surface and appears to be a result of the quasi-neutral plasma environment.

[Biocompatibility of poly-L-lactic acid/Bioglass-guided bone regeneration membranes processed with oxygen plasma].

PubMed

Fang, Wei; Zeng, Shu-Guang; Gao, Wen-Feng

2015-04-01

To prepare and characterize a nano-scale fibrous hydrophilic poly-L-lactic acid/ Bioglass (PLLA/BG) composite membrane and evaluate its biocompatibility as a composite membrane for guiding bone regeneration (GBR). PLLA/BG-guided bone regeneration membrane was treated by oxygen plasma to improved its hydrophilicity. The growth of MG-63 osteoblasts on the membrane was observed using Hoechst fluorescence staining, and the biocompatibility of the membrane was evaluated by calculating the cells adhesion rate and proliferation rate. Osteogenesis of MG-63 cells was assessed by detecting alkaline phosphatase (ALP), and the formation of calcified nodules and cell morphology changes were observed using scanning electron microscope (SEM). The cell adhesion rates of PLLA/BG-guided bone regeneration membrane treated with oxygen plasma were (30.570±0.96)%, (47.27±0.78)%, and (66.78±0.69)% at 1, 3, and 6 h, respectively, significantly higher than those on PLLA membrane and untreated PLLA/BG membrane (P<0.01). The cell proliferation rates on the 3 membranes increased with time, but highest on oxygen plasma-treated PLLA/BG membrane (P<0.01). Hoechst fluorescence staining revealed that oxygen plasma treatment of the PLLA/BG membrane promoted cell adhesion. The membranes with Bioglass promoted the matrix secretion of the osteoblasts. Under SEM, the formation of calcified nodules and spindle-shaped cell morphology were observed on oxygen plasma-treated PLLA/BG membrane. Oxygen plasma-treated PLLA/BG composite membrane has good biocompatibility and can promote adhesion, proliferation and osteogenesis of the osteoblasts.

Anthocyanins do not influence long-chain n-3 fatty acid status: studies in cells, rodents and humans.

PubMed

Vauzour, David; Tejera, Noemi; O'Neill, Colette; Booz, Valeria; Jude, Baptiste; Wolf, Insa M A; Rigby, Neil; Silvan, Jose Manuel; Curtis, Peter J; Cassidy, Aedin; de Pascual-Teresa, Sonia; Rimbach, Gerald; Minihane, Anne Marie

2015-03-01

Increased tissue status of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) is associated with cardiovascular and cognitive benefits. Limited epidemiological and animal data suggest that flavonoids, and specifically anthocyanins, may increase EPA and DHA levels, potentially by increasing their synthesis from the shorter-chain n-3 PUFA, α-linolenic acid. Using complimentary cell, rodent and human studies we investigated the impact of anthocyanins and anthocyanin-rich foods/extracts on plasma and tissue EPA and DHA levels and on the expression of fatty acid desaturase 2 (FADS2), which represents the rate limiting enzymes in EPA and DHA synthesis. In experiment 1, rats were fed a standard diet containing either palm oil or rapeseed oil supplemented with pure anthocyanins for 8 weeks. Retrospective fatty acid analysis was conducted on plasma samples collected from a human randomized controlled trial where participants consumed an elderberry extract for 12 weeks (experiment 2). HepG2 cells were cultured with α-linolenic acid with or without select anthocyanins and their in vivo metabolites for 24 h and 48 h (experiment 3). The fatty acid composition of the cell membranes, plasma and liver tissues were analyzed by gas chromatography. Anthocyanins and anthocyanin-rich food intake had no significant impact on EPA or DHA status or FADS2 gene expression in any model system. These data indicate little impact of dietary anthocyanins on n-3 PUFA distribution and suggest that the increasingly recognized benefits of anthocyanins are unlikely to be the result of a beneficial impact on tissue fatty acid status. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Anthocyanins do not influence long-chain n-3 fatty acid status: studies in cells, rodents and humans☆

PubMed Central

Vauzour, David; Tejera, Noemi; O'Neill, Colette; Booz, Valeria; Jude, Baptiste; Wolf, Insa M.A.; Rigby, Neil; Silvan, Jose Manuel; Curtis, Peter J.; Cassidy, Aedin; de Pascual-Teresa, Sonia; Rimbach, Gerald; Minihane, Anne Marie

2015-01-01

Increased tissue status of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) is associated with cardiovascular and cognitive benefits. Limited epidemiological and animal data suggest that flavonoids, and specifically anthocyanins, may increase EPA and DHA levels, potentially by increasing their synthesis from the shorter-chain n-3 PUFA, α-linolenic acid. Using complimentary cell, rodent and human studies we investigated the impact of anthocyanins and anthocyanin-rich foods/extracts on plasma and tissue EPA and DHA levels and on the expression of fatty acid desaturase 2 (FADS2), which represents the rate limiting enzymes in EPA and DHA synthesis. In experiment 1, rats were fed a standard diet containing either palm oil or rapeseed oil supplemented with pure anthocyanins for 8 weeks. Retrospective fatty acid analysis was conducted on plasma samples collected from a human randomized controlled trial where participants consumed an elderberry extract for 12 weeks (experiment 2). HepG2 cells were cultured with α-linolenic acid with or without select anthocyanins and their in vivo metabolites for 24 h and 48 h (experiment 3). The fatty acid composition of the cell membranes, plasma and liver tissues were analyzed by gas chromatography. Anthocyanins and anthocyanin-rich food intake had no significant impact on EPA or DHA status or FADS2 gene expression in any model system. These data indicate little impact of dietary anthocyanins on n-3 PUFA distribution and suggest that the increasingly recognized benefits of anthocyanins are unlikely to be the result of a beneficial impact on tissue fatty acid status. PMID:25573539

Restrike Particle Beam Experiments on a Dense Plasma Focus. Opening Switch Research on a Dense Plasma Focus.

DTIC Science & Technology

1985-06-01

Research on this grant has focused on plasma focus experiments in the areas of particle beam generation and as a potential repetitive opening switch...as were scaling laws for the increase of electron energy and current with input energy. The potential of the plasma focus as an opening switch was...delay line technique. The observed frequencies were most consistent with the lower hybrid frequency. Keywords include: Dense Plasma Focus , Particle Beam Generation, Opening Switch, Load Experiments, Pulsed Power.

Space plasma branch at NRL

NASA Astrophysics Data System (ADS)

The Naval Research Laboratory (Washington, D.C.) formed the Space Plasma Branch within its Plasma Physics Division on July 1. Vithal Patel, former Program Director of Magnetospheric Physics, National Science Foundation, also joined NRL on the same date as Associate Superintendent of the Plasma Physics Division. Barret Ripin is head of the newly organized branch. The Space Plasma branch will do basic and applied space plasma research using a multidisciplinary approach. It consolidates traditional rocket and satellite space experiments, space plasma theory and computation, with laboratory space-related experiments. About 40 research scientists, postdoctoral fellows, engineers, and technicians are divided among its five sections. The Theory and Computation sections are led by Joseph Huba and Joel Fedder, the Space Experiments section is led by Paul Rodriguez, and the Pharos Laser Facility and Laser Experiments sections are headed by Charles Manka and Jacob Grun.

Overview of the Lockheed Martin Compact Fusion Reactor (CFR) Project

NASA Astrophysics Data System (ADS)

McGuire, Thomas

2017-10-01

The Lockheed Martin Compact Fusion Reactor (CFR) Program endeavors to quickly develop a compact fusion power plant with favorable commercial economics and military utility. The CFR uses a diamagnetic, high beta, magnetically encapsulated, linear ring cusp plasma confinement scheme. Major project activities will be reviewed, including the T4B and T5 plasma heating experiments. The goal of the experiments is to demonstrate a suitable plasma target for heating experiments, to characterize the behavior of plasma sources in the CFR configuration and to then heat the plasma with neutral beams, with the plasma transitioning into the high Beta confinement regime. The design and preliminary results of the experiments will be presented, including discussion of predicted behavior, plasma sources, heating mechanisms, diagnostics suite and relevant numerical modeling. ©2017 Lockheed Martin Corporation. All Rights Reserved.

Cold plasma processing of local planetary ores for oxygen and metallurgically important metals

NASA Technical Reports Server (NTRS)

Lynch, D. C.; Bullard, D.; Ortega, R.

1990-01-01

The utilization of a cold plasma in chlorination processing is described. Essential equipment and instruments were received, the experimental apparatus assembled and tested, and preliminary experiments conducted. The results of the latter lend support to the original hypothesis: a cold plasma can both significantly enhance and bias chemical reactions. In two separate experiments, a cold plasma was used to reduce TiCl4 vapor and chlorinate ilmenite. The latter, reacted in an argon-chlorine plasma, yielded oxygen. The former experiment reveals that chlorine can be recovered as HCl vapor from metal chlorides in a hydrogen plasma. Furthermore, the success of the hydrogen experiments has lead to an analysis of the feasibility of direct hydrogen reduction of metal oxides in a cold plasma. That process would produce water vapor and numerous metal by-products.

Ultraviolet spectrophotometry of comet Giacobini-Zinner during the ICE encounter. [International Cometary Explorer (ICE)

NASA Technical Reports Server (NTRS)

Ahearn, Michael F.; Mcfadden, Lucy A.; Feldman, Paul D.; Boehnhardt, Hermann; Rahe, Juergen; Festou, Michael; Brandt, John C.; Maran, Stephen P.; Niedner, Malcom B.; Smith, Andrew M.

1986-01-01

The IUE spectrophotometry of Comet P/Giacobini-Zinner was acquired in support of the International Cometary Explorer (ICE) mission. The abundances (or upper limits) of UV-active species were calculated. During the ICE encounter the H2O production rate was 3 times 10 to the 28th power/sec, + or - 50%, consistent with values derived from the ICE experiments. Comparison of the abundance of CO2(+) ions with the total electron density measured by the plasma electron experiment on ICE indicates a deficiency of ions relative to electrons indicating a population of ions not detected by remote sensing. The absence of detectable Mg(+) rules out this species as a possible ion of M/Q = 24 detected by the Ion Composition Instrument, part of the ICE complement of instruments.

Characterization of Ni-YSZ anodes for solid oxide fuel cells fabricated by solution precursor plasma spraying with axial feedstock injection

NASA Astrophysics Data System (ADS)

Metcalfe, Craig; Lay-Grindler, Elisa; Kesler, Olivera

2014-02-01

Nickel and yttria-stabilized zirconia (YSZ) anodes were fabricated by solution precursor plasma spraying (SPPS) and incorporated into metal-supported solid oxide fuel cells (SOFC). A power density of 0.45 W cm-2 at 0.7 V and a peak power density of 0.52 W cm-2 at 750 °C in humidified H2 was obtained, which are the first performance results reported for an SOFC having an anode fabricated by SPPS. The effects of solution composition, plasma gas composition, and stand-off distance on the composition of the deposited Ni-YSZ coatings by SPPS were evaluated. It was found that the addition of citric acid to the aqueous solution delayed re-solidification of NiO particles, improving the deposition efficiency and coating adhesion. The composition of the deposited coatings was found to vary with torch power. Increasing torch power led to coatings with decreasing Ni content, as a result of Ni vaporizing in-flight at stand-off distances less than 60 mm from the torch nozzle exit.

Plasma-modified graphene nanoplatelets and multiwalled carbon nanotubes as fillers for advanced rubber composites

NASA Astrophysics Data System (ADS)

Sicinski, M.; Gozdek, T.; Bielinski, D. M.; Szymanowski, H.; Kleczewska, J.; Piatkowska, A.

2015-07-01

In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers’ SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

Pre-launch simulation experiment of microwave-ionosphere nonlinear interaction rocket experiment in the space plasma chamber

NASA Astrophysics Data System (ADS)

Kaya, N.; Tsutsui, M.; Matsumoto, H.; Kimura, I.

1980-09-01

A pre-flight test experiment of a microwave-ionosphere nonlinear interaction rocket experiment (MINIX) has been carried out in a space plasma simulation chamber. Though the first rocket experiment ended up in failure because of a high voltage trouble, interesting results are observed in the pre-flight experiment. A significant microwave heating of plasma up to 300% temperature increase is observed. Strong excitations of plasma waves by the transmitted microwaves in the VLF and HF range are observed as well. These microwave effects may have to be taken into account in solar power satellite projects in the future.

Tribological properties of self-lubricating fluoride-metal composites to 900 C (1650 F): A review and some new developments

NASA Technical Reports Server (NTRS)

Sliney, H. E.; Graham, J. W.

1974-01-01

The friction and wear behavior of some fluoride-metal, self-lubricating composites are summarized. Fluoride-infiltrated sintered nickel alloy composites and plasma-sprayed, co-deposited fluoride-nickel alloy composites are described. The importance of proper surface-conditioning of the composites is stressed. Performance of fluoride-metal composites in some machine application evaluation is discussed.

"CHON" particles: The interstellar component of cometary dust

NASA Technical Reports Server (NTRS)

Lien, David J.

1998-01-01

Interstellar dust is characterized by strong absorption in the ultraviolet and the mid-IR. Current models of interstellar dust are based on three chemically distinct components: a form of carbon (usually graphite), a silicate, and a blend of polycyclic aromatic hydrocarbons or other carbonaceous material. Previous work using effective medium theories to understand the optical properties of cometary dust suggested that an amalgam of materials could reproduce the observed interstellar and cometary dust features. Recently, Lawler and Brownlee (1992) re-analyzed the PIA and PUMA-1 data sets from the Giotto flyby of P/Halley and discovered that the so-called "CHON" particles were actually composed of a blend of carbon-bearing and silicon-bearing materials. Based on effective medium theories, the absorption spectrum of such a material would display the spectral features of each of the components - strong UV absorption from the carbonaceous component and strong absorption in the IR from the silicate component. To test this idea, vapor-deposited samples were created using two different deposition techniques: sputtering with an argon RF magnetron and deposition from an argon plasma torch. Two different compositions were tested: a blend of graphite and silica in a 7:1 ratio and an amalgam of materials whose approximate composition matches the "CHON"-silicate abundances for the uncompressed PIA data set of Lawler and Brownlee: graphite, iron oxide, magnesium oxide, ammonium sulfate, calcium carbonate, and silica in mass ratios of 6:4.3:4:2.2:1:9. The samples were finely ground and pressed into 2" diameter disks using a 40 ton press. In all, four different experiments were performed: one with each of the compositions (C:SiO and "CHON") in both the RF magnetron and the plasma torch chambers. The RF magnetron created a uniform dark thin film on the substrate surface, and the plasma torch created a coating of small (<100 micron) diameter grey particles. The spectra of all four samples show a strong, broad absorption feature at around 220 nm as well as a strong but narrower absorption peak near 10 microns. The RF magnetron sputtered samples showed some sub-structure in the UV, and the peak of the absorption was shifted toward longer wavelengths. The UV absorption in the plasma torch deposited samples have no sub-structure, and the peak absorption is very near 220 nm. Strong absorption near 9 microns is seen in the spectra from both sample preparation techniques, and is consistent with the IR spectra of some terrestrial silicates. Other features, particularly at 6.2 and 8.6 microns, are seen in the interstellar medium. A strong feature near 2 microns is due to absorbed water in the sample. Based on the results of these experiments, there is evidence that a material with a composition similar to that detected in "CHON" particles in the coma of P/Halley have a spectral signature which reproduces the main absorption features of interstellar dust. This suggests that the "CHON" particles could be the interstellar component of cometary dust.

Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

2012-06-01

Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

Physics Criteria for a Subscale Plasma Liner Experiment

DOE PAGES

Hsu, Scott C.; Thio, Yong C. Francis

2018-02-02

Spherically imploding plasma liners, formed by merging hypersonic plasma jets, are a proposed standoff driver to compress magnetized target plasmas to fusion conditions (Hsu et al. in IEEE Trans Plasma Sci 40:1287, 2012). Here, in this paper, the parameter space and physics criteria are identified for a subscale, plasma-liner-formation experiment to provide data, e.g., on liner ram-pressure scaling and uniformity, that are relevant for addressing scientific issues of full-scale plasma liners required to achieve fusion conditions. Lastly, based on these criteria, we quantitatively estimate the minimum liner kinetic energy and mass needed, which informed the design of a subscale plasmamore » liner experiment now under development.« less

Physics Criteria for a Subscale Plasma Liner Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Scott C.; Thio, Yong C. Francis

Spherically imploding plasma liners, formed by merging hypersonic plasma jets, are a proposed standoff driver to compress magnetized target plasmas to fusion conditions (Hsu et al. in IEEE Trans Plasma Sci 40:1287, 2012). Here, in this paper, the parameter space and physics criteria are identified for a subscale, plasma-liner-formation experiment to provide data, e.g., on liner ram-pressure scaling and uniformity, that are relevant for addressing scientific issues of full-scale plasma liners required to achieve fusion conditions. Lastly, based on these criteria, we quantitatively estimate the minimum liner kinetic energy and mass needed, which informed the design of a subscale plasmamore » liner experiment now under development.« less

Using the tritium plasma experiment to evaluate ITER PFC safety

NASA Astrophysics Data System (ADS)

Longhurst, Glen R.; Anderl, Robert A.; Bartlit, John R.; Causey, Rion A.; Haines, John R.

1993-06-01

The Tritium Plasma Experiment was assembled at Sandia National Laboratories, Livermore and is being moved to the Tritium Systems Test Assembly facility at Los Alamos National Laboratory to investigate interactions between dense plasmas at low energies and plasma-facing component materials. This apparatus has the unique capabilty of replicating plasma conditions in a tokamak divertor with particle flux densities of 2 × 1023 ions/m2.s and a plasma temperature of about 15 eV using a plasma that includes tritium. An experimental program has been initiated using the Tritium Plasma Experiment to examine safety issues related to tritium in plasma-facing components, particularly the ITER divertor. Those issues include tritium retention and release characteristics, tritium permeation rates and transient times to coolant streams, surface modification and erosion by the plasma, the effects of thermal loads and cycling, and particulate production. An industrial consortium led by McDonnell Douglas will design and fabricate the test fixtures.

Role of Plasma Temperature and Residence Time in Stagnation Plasma Synthesis of c-BN Nanopowders

DTIC Science & Technology

2013-01-01

outer diameter of 15mm. A center injection 19 nozzle of 1.4mm diameter is implemented for precursor introduction. Plasma and sheath gas ... Gas Phase Synthesis of Nanoparticles..................................................... 5 2.2 Cubic Boron Nitride Synthesis...11 2.2.4 Effects of gas composition ............................................................................................ 11

Enhancement of Wound Healing by Non-Thermal N2/Ar Micro-Plasma Exposure in Mice with Fractional-CO2-Laser-Induced Wounds.

PubMed

Shao, Pei-Lin; Liao, Jiunn-Der; Wong, Tak-Wah; Wang, Yi-Cheng; Leu, Steve; Yip, Hon-Kan

2016-01-01

Micro-plasma is a possible alternative treatment for wound management. The effect of micro-plasma on wound healing depends on its composition and temperature. The authors previously developed a capillary-tube-based micro-plasma system that can generate micro-plasma with a high nitric oxide-containing species composition and mild working temperature. Here, the efficacy of micro-plasma treatment on wound healing in a laser-induced skin wound mouse model was investigated. A partial thickness wound was created in the back skin of each mouse and then treated with micro-plasma. Non-invasive methods, namely wound closure kinetics, optical coherence tomography (OCT), and laser Doppler scanning, were used to measure the healing efficiency in the wound area. Neo-tissue growth and the expressions of matrix metallopeptidase-3 (MMP-3) and laminin in the wound area were assessed using histological and immunohistochemistry (IHC) analysis. The results show that micro-plasma treatment promoted wound healing. Micro-plasma treatment significantly reduced the wound bed region. The OCT images and histological analysis indicates more pronounced tissue regrowth in the wound bed region after micro-plasma treatment. The laser Doppler images shows that micro-plasma treatment promoted blood flow in the wound bed region. The IHC results show that the level of laminin increased in the wound bed region after micro-plasma treatment, whereas the level of MMP-3 decreased. Based on these results, micro-plasma has potential to be used to promote the healing of skin wounds clinically.

Enhancement of Wound Healing by Non-Thermal N2/Ar Micro-Plasma Exposure in Mice with Fractional-CO2-Laser-Induced Wounds

PubMed Central

Shao, Pei-Lin; Liao, Jiunn-Der; Wong, Tak-Wah; Wang, Yi-Cheng; Leu, Steve; Yip, Hon-Kan

2016-01-01

Micro-plasma is a possible alternative treatment for wound management. The effect of micro-plasma on wound healing depends on its composition and temperature. The authors previously developed a capillary-tube-based micro-plasma system that can generate micro-plasma with a high nitric oxide-containing species composition and mild working temperature. Here, the efficacy of micro-plasma treatment on wound healing in a laser-induced skin wound mouse model was investigated. A partial thickness wound was created in the back skin of each mouse and then treated with micro-plasma. Non-invasive methods, namely wound closure kinetics, optical coherence tomography (OCT), and laser Doppler scanning, were used to measure the healing efficiency in the wound area. Neo-tissue growth and the expressions of matrix metallopeptidase-3 (MMP-3) and laminin in the wound area were assessed using histological and immunohistochemistry (IHC) analysis. The results show that micro-plasma treatment promoted wound healing. Micro-plasma treatment significantly reduced the wound bed region. The OCT images and histological analysis indicates more pronounced tissue regrowth in the wound bed region after micro-plasma treatment. The laser Doppler images shows that micro-plasma treatment promoted blood flow in the wound bed region. The IHC results show that the level of laminin increased in the wound bed region after micro-plasma treatment, whereas the level of MMP-3 decreased. Based on these results, micro-plasma has potential to be used to promote the healing of skin wounds clinically. PMID:27248979

Plasma MRI Experiments at UW-Madison

NASA Astrophysics Data System (ADS)

Flanagan, K.; Clark, M.; Desangles, V.; Siller, R.; Wallace, J.; Weisberg, D.; Forest, C. B.

2015-11-01

Experiments for driving Keplerian-like flow profiles on both the Plasma Couette Experiment Upgrade (PCX-U) and the Wisconsin Plasma Astrophysics Laboratory (WiPAL) user facility are described. Instead of driving flow at the boundaries, as is typical in many liquid metal Couette experiments, a global drive is implemented. A large radial current is drawn across a small axial field generating torque across the whole profile. This global electrically driven flow is capable of producing profiles similar to Keplerian flow. PCX-U has been purposely constructed for MRI experiments, while similar experiments on the WiPAL device show the versatility of the user facility and provide a larger plasma volume. Numerical calculations show the predicted parameter spaces for exciting the MRI in these plasmas and the equilibrium flow profiles expected. In both devices, relevant MRI parameters appear to be within reach of typical operating characteristics.

Modeling the mechanical behavior of ceramic and heterophase structures manufactured using selective laser sintering and spark plasma sintering

NASA Astrophysics Data System (ADS)

Skripnyak, Vladimir A.; Skripnyak, Evgeniya G.; Skripnyak, Vladimir V.; Vaganova, Irina K.

A model for predicting mechanical properties of ultra-high temperature ceramics and composites manufactured by selective laser sintering (SLS) and spark plasma sintering (SPS) under shock loading is presented. The model takes into account the porous structure, the specific volume and average sizes of phases, and the temperature of sintering. Residual stresses in ceramic composites reinforced with particles of refractory borides, carbides and nitrides after SLS or SPS were calculated. It is shown that the spall strength of diboride-zirconium matrix composites can be increased by the decreasing of porosity and the introduction of inclusions of specially selected refractory strengthening phases.

Lead isotopic composition of trinitite melt glass: evidence for the presence of Canadian industrial lead in the first atomic weapon test.

PubMed

Bellucci, Jeremy J; Simonetti, Antonio; Wallace, Christine; Koeman, Elizabeth C; Burns, Peter C

2013-08-06

The Pb isotopic compositions for 51 spots of melt glass in 11 samples of trinitite have been determined by laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). Trinitite glass yields a large range of Pb isotopic compositions (i.e., (206)Pb/(204)Pb = 17.08-19.04), which reflect mixing between industrial Pb from materials used in the Trinity test and natural geologic components. Areas within trinitite melt glass containing high concentrations of both Cu and Pb, which are derived from the bomb and blast site-related components, were used for delineating the Pb isotopic composition corresponding to the anthropogenic Pb component. Comparison between the isotopic composition estimated here for the industrial Pb used in the Trinity test and those from known Pb deposits worldwide indicates close agreement with ore from the Buchans mine (Newfoundland, Canada). The Buchans mine was active during the time of the Trinity test and was operated by the American Smelting and Refining Company, which could have provided the Pb used in the test. The industrial Pb used in the Trinity test materials is not documented in the literature (or declassified) but could have been present in bricks, solder, pigs, or some other anthropogenic component related to the experiment.

Drift kinetic effects on plasma response in high beta spherical tokamak experiments

NASA Astrophysics Data System (ADS)

Wang, Zhirui; Park, Jong-Kyu; Menard, Jonathan E.; Liu, Yueqiang; Kaye, Stanley M.; Gerhardt, Stefan

2018-01-01

The high β plasma response to rotating n=1 external magnetic perturbations is numerically studied and compared with the National Spherical Torus Experiment (NSTX). The hybrid magnetohydrodynamic(MHD)-kinetic modeling shows that drift kinetic effects are important in resolving the disagreement of plasma response between the ideal MHD prediction and the NSTX experimental observation when plasma pressure reaches and exceeds the no-wall limit (Troyon et al 1984 Plasma Phys. Control. Fusion 26 209). Since the external rotating fields and high plasma rotation are presented in the NSTX experiments, the importance of the resistive wall effect and plasma rotation in determining the plasma response is also identified, where the resistive wall suppresses the plasma response through the wall eddy current. The inertial energy due to plasma rotation destabilizes the plasma. The complexity of the plasma response in this study indicates that MHD modeling, including comprehensive physics, e.g. the drift kinetic effects, resistive wall and plasma rotation, are essential in order to reliably predict the plasma behavior in a high beta spherical tokamak device.

Heat insulation performance, mechanics and hydrophobic modification of cellulose-SiO2 composite aerogels.

PubMed

Shi, Jianjun; Lu, Lingbin; Guo, Wantao; Zhang, Jingying; Cao, Yang

2013-10-15

Cellulose-SiO2 composite hydrogel was prepared by combining the NaOH/thiourea/H2O solvent system and the immersion method with controlling the hydrolysis-fasculation rate of tetraethyl orthosilicate (TEOS). The hydrophobic composite aerogels were obtained through the freeze-drying technology and the cold plasma modification technology. Composite SiO2 could obviously reduce the thermal conductivity of cellulose aerogel. The thermal conductivity could be as low as 0.026 W/(mK). The thermal insulation mechanism of the aerogel material was discussed. Composite SiO2 reduced hydrophilicity of cellulose aerogel, but environmental humidity had a significant influence on heat insulation performance. After hydrophobic modification using CCl4 as plasma was conducted, the surface of composite aerogel was changed from hydrophilic to hydrophobic and water contact angle was as high as 132°. The modified composite aerogel still kept good heat insulation performance. This work provided a foundation for the possibility of applying cellulose-SiO2 composite aerogel in the insulating material field. Copyright © 2013 Elsevier Ltd. All rights reserved.

A highly stable (SnOx-Sn)@few layered graphene composite anode of sodium-ion batteries synthesized by oxygen plasma assisted milling

NASA Astrophysics Data System (ADS)

Cheng, Deliang; Liu, Jiangwen; Li, Xiang; Hu, Renzong; Zeng, Meiqing; Yang, Lichun; Zhu, Min

2017-05-01

The (SnOx-Sn)@few layered graphene ((SnOx-Sn)@FLG) composite has been synthesized by oxygen plasma-assisted milling. Owing to the synergistic effect of rapid plasma heating and ball mill grinding, SnOx (1 ≤ x ≤ 2) nanoparticles generated from the reaction of Sn with oxygen are tightly wrapped by FLG nanosheets which are simultaneously exfoliated from expanded graphite, forming secondary micro granules. Inside the granules, the small size of the SnOx nanoparticles enables the fast kinetics for Na+ transfer. The in-situ formed FLG and residual Sn nanoparticles improve the electrical conductivity of the composite, meanwhile alleviate the aggregation of SnOx nanoparticles and relieve the volume change during the cycling, which is beneficial for the cyclic stability for the Na+ storage. As an anode material for sodium-ion batteries, the (SnOx-Sn)@FLG composite exhibits a high reversible capacity of 448 mAh g-1 at a current density of 100 mA g-1 in the first cycle, with 82.6% capacity retention after 250 cycles. Even when the current density increases to 1000 mA g-1, this composite retains 316.5 mAh g-1 after 250 cycles. With superior Na+ storage stability, the (SnOx-Sn)@FLG composite can be a promising anode material for high performance sodium-ion batteries.

Pulsed plasma chemical synthesis of carbon-containing titanium and silicon oxide based nanocomposite

NASA Astrophysics Data System (ADS)

Kholodnaya, Galina; Sazonov, Roman; Ponomarev, Denis; Zhirkov, Igor

2018-03-01

The paper presents the results of the experimental investigation of the physical and chemical properties of the TixSiyCzOw composite nanopowders, which were first obtained using a pulsed plasma chemical method. The pulsed plasma chemical synthesis was achieved using a technological electron accelerator (TEA-500). The parameters of the electron beam are as follows: 400-450 keV electron energy, 60 ns half-amplitude pulse duration, up to 200 J pulse energy, and 5 cm beam diameter. The main physical and chemical properties of the obtained composites were studied (morphology, chemical, elemental and phase composition). The morphology of the TixSiyCzOw composites is multiform. There are large round particles, with an average size of above 150 nm. Besides, there are small particles (an average size is in the range of 15-40 nm). The morphology of small particles is in the form of crystallites. In the TixSiyCzOw synthesised composite, the peak with a maximum of 946 cm-1 was registered. The presence of IR radiation in this region of the spectrum is typical for the deformation of atomic oscillations in the Si‒О‒Ti bond, which indicates the formation of the solid solution. The composites consist of two crystal phases - anatase and rutile. The prevailing phase of the crystal structure is rutile.

Ion composition variety and variability around perihelion

NASA Astrophysics Data System (ADS)

Beth, Arnaud; Altwegg, Kathrin; Behar, Étienne; Broiles, Tom; Burch, Jim; Carr, Christopher; Eriksson, Anders; Galand, Marina; Goetz, Charlotte; Henri, Pierre; Heritier, Kévin; Nilsson, Hans; Odelstad, Elias; Richter, Ingo; Rubin, Martin; Vallieres, Xavier

2017-04-01

For two years, the Double Focusing Mass Spectrometer (DFMS), one of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) onboard Rosetta probed the neutral gas and the plasma composition of the comet 67P/Churyumov-Gerasimenko's coma (67P). Major ion species detected include water ions (e.g, H2O+, H3O+, HO+) observed throughout the escorting phase. The analysis of DFMS data revealed a large zoo of ion species near perihelion (summer 2015). In particular, protonated versions of high proton affinity neutrals (e.g., NH4+) were detected, but also hydrocarbon and organic ion species. Near perihelion, ion composition was also highly variable and showed interesting variations in the complexity of the observed ion species. We will first present an overview of the rich variety of ion species observed during perihelion. This study will be supported by ionospheric modeling of ion composition below the ion exobase. We will then show an intercomparison between DFMS data and Rosetta Plasma Consortium (RPC) plasma and particle data to interpret the DFMS ion composition variability. Our primary goal is to highlight any correlation between observations from these different instruments (i.e. ion composition, ion and electron number density, energy distribution, magnetic field) and to find relevant signatures of physical processes which can affect the chemistry and dynamics (e.g., acceleration and deflection) of the involved neutral and ion species.

Relationship between red cell membrane fatty acids and adipokines in individuals with varying insulin sensitivity.

PubMed

Min, Y; Lowy, C; Islam, S; Khan, F S; Swaminathan, R

2011-06-01

Plasma leptin and adiponectin, and membrane phospholipid fatty acid composition are implicated into the mechanism of insulin resistance but no clear pattern has emerged. Hence, this study examined these variables in subjects presenting to the diabetic clinic for a diagnostic glucose tolerance test. Body composition, glucose, glycated hemoglobin, insulin, leptin, adiponectin, and red cell and plasma phospholipid fatty acids were assessed from 42 normal and 28 impaired glucose tolerant subjects. Insulin sensitivity was determined by homeostatic model assessment. The plasma phosphatidylcholine fatty acid composition of the impaired glucose tolerant subjects was similar to that of normal subjects. However, the impaired glucose tolerant subjects had significantly lower linoleic (P<0.05), eicosapentaenoic (P<0.05) and docosahexaenoic (P<0.01) acids in the red cell phosphatidylcholine and phosphatidylethanolamine compared with the normal subjects. Moreover, red cell phosphatidylcholine docosahexaenoic acid correlated positively with adiponectin (r=0.290, P<0.05) but negatively with leptin (r=-0.252, P<0.05), insulin (r=-0.335, P<0.01) and insulin resistance (r=-0.322, P<0.01). Plasma triglycerides, leptin and glucose combined predicted about 60% of variation in insulin level whereas insulin was the only component that predicted the membrane fatty acids. We postulate that membrane phospholipids fatty acids have an indirect role in determining insulin concentration but insulin has a major role in determining membrane fatty acid composition.

Plasma Metamaterials for Arbitrary Complex-Amplitude Wave Filters

DTIC Science & Technology

2013-09-10

plasmas as reflectors , 4 absorbers, 4,5 and antennae 6 of electromagnetic waves. In contrast with the other materials in these devices, parameters...are controlled using launching antenna and high-power wave sources. One of the fundamental facts we have learned in microwave plasmas is that...metamaterials.” 29 In this report, we demonstrate the functional composites of plasmas and metamaterials, and the focusing point is verification of

Thermodynamic and Transport Properties of Real Air Plasma in Wide Range of Temperature and Pressure

NASA Astrophysics Data System (ADS)

Wang, Chunlin; Wu, Yi; Chen, Zhexin; Yang, Fei; Feng, Ying; Rong, Mingzhe; Zhang, Hantian

2016-07-01

Air plasma has been widely applied in industrial manufacture. In this paper, both dry and humid air plasmas' thermodynamic and transport properties are calculated in temperature 300-100000 K and pressure 0.1-100 atm. To build a more precise model of real air plasma, over 70 species are considered for composition. Two different methods, the Gibbs free energy minimization method and the mass action law method, are used to determinate the composition of the air plasma in a different temperature range. For the transport coefficients, the simplified Chapman-Enskog method developed by Devoto has been applied using the most recent collision integrals. It is found that the presence of CO2 has almost no effect on the properties of air plasma. The influence of H2O can be ignored except in low pressure air plasma, in which the saturated vapor pressure is relatively high. The results will serve as credible inputs for computational simulation of air plasma. supported by the National Key Basic Research Program of China (973 Program)(No. 2015CB251002), National Natural Science Foundation of China (Nos. 51521065, 51577145), the Science and Technology Project Funds of the Grid State Corporation (SGTYHT/13-JS-177), the Fundamental Research Funds for the Central Universities, and State Grid Corporation Project (GY71-14-004)

Ion Mass Spectroscopy for the Outer Solar System

NASA Astrophysics Data System (ADS)

Reisenfeld, D. B.; Elphic, R. C.; McComas, D. J.; Nordholt, J. E.; Steinberg, J. T.; Wiens, R. C.

2001-01-01

A proven method for determination of the exospheric and surface composition of moons and comets is ion mass spectroscopy. Ions are produced via sputtering of surface constituents by the ambient plasma (solar wind or planetary magnetospheres), and via photo- and electron impact ionization of neutral exospheric/atmospheric constituents. A promising emergent technology in the field of space-based ion mass spectrometry is the low-cost, miniaturized but high-performance ion mass spectrometer (IMS) as exhibited by the Plasma Experiment for Planetary Exploration (PEPE) on Deep Space 1 (DS-1). A technology demonstration instrument, the PEPE IMS realized a mass resolution (M/delta(M)) of approximately 10. Its energy range extends from 5 eV to 9 keV at this mass resolution, and up to 33.5 keV in a lower mass resolution mode. With minimal development, these capabilities can be greatly extended. Already, we have produced a fully functional engineering model having a M/delta(M) = 20 and an energy range extending to 18 keV in the high-mass resolution mode. Further design modifications anticipate extending the mass resolution to 30-40 while still maintaining a miniaturized design. This makes possible many more isotopic and molecular differentiations than achievable with the original PEPE design. A PEPE-class spectrometer can address a significant number of the OPP key strategic objectives. In particular, in situ cometary nucleus analysis, studies of Triton's atmospheric and surface composition, and Europa surface composition analysis, can all be performed through IMS measurements. Additional information is contained in the original extended abstract.

Dynamic determination of secondary electron emission using a calorimetric probe in a plasma immersion ion implantation experiment

NASA Astrophysics Data System (ADS)

Haase, Fabian; Manova, Darina; Hirsch, Dietmar; Mändl, Stephan; Kersten, Holger

2018-04-01

A passive thermal probe has been used to detect dynamic changes in the secondary electron emission (SEE). Oxidized and nitrided materials have been studied during argon ion sputtering in a plasma immersion ion implantation process. Identical measurements have been performed for the metallic state with high voltage pulses accelerating nitrogen ions towards the surface, supposedly forming a nitride layer. Energy flux data were combined with scanning electron microscopy images of the surface to obtain information about the actual surface composition as well as trends and changes during the process. Within the measurements, a direct comparison of the SEE within both employed ion species (argon and nitrogen) is possible while an absolute quantification is still open. Additionally, the nominal composition of the investigated oxide and nitride layers does not always correspond to stoichiometric compounds. Nevertheless, the oxides showed a remarkably higher SEE compared to the pure metals, while an indistinct behavior was observed for the nitrides: some higher, some lower than the clean metal surfaces. For the aluminum alloy AlMg3 a complex time dependent evolution was observed with consecutive oxidation/sputtering cycles leading to a very rough surface with a diminished oxide layer, leading to an almost black surface of the metal and non-reproducible changes in the SEE. The presented method is a versatile technique for measuring dynamic changes of the surface for materials commonly used in PVD processes with a time resolution of about 1 min, e.g. magnetron sputtering or HiPIMS, where changes in the target or electrode composition are occurring but cannot be measured directly.

Combined experimental and theoretical description of direct current magnetron sputtering of Al by Ar and Ar/N2 plasma

NASA Astrophysics Data System (ADS)

Trieschmann, Jan; Ries, Stefan; Bibinov, Nikita; Awakowicz, Peter; Mráz, Stanislav; Schneider, Jochen M.; Mussenbrock, Thomas

2018-05-01

Direct current magnetron sputtering of Al by Ar and Ar/N2 low pressure plasmas was characterized by experimental and theoretical means in a unified consideration. Experimentally, the plasmas were analyzed by optical emission spectroscopy, while the film deposition rate was determined by weight measurements and laser optical microscopy, and the film composition by energy dispersive x-ray spectroscopy. Theoretically, a global particle and power balance model was used to estimate the electron temperature T e and the electron density n e of the plasma at constant discharge power. In addition, the sputtering process and the transport of the sputtered atoms were described using Monte Carlo models—TRIDYN and dsmcFoam, respectively. Initially, the non-reactive situation is characterized based on deposition experiment results, which are in agreement with predictions from simulations. Subsequently, a similar study is presented for the reactive case. The influence of the N2 addition is found to be twofold, in terms of (i) the target and substrate surface conditions (e.g., sputtering, secondary electron emission, particle sticking) and (ii) the volumetric changes of the plasma density n e governing the ion flux to the surfaces (e.g., due to additional energy conversion channels). It is shown that a combined experimental/simulation approach reveals a physically coherent and, in particular, quantitative understanding of the properties (e.g., electron density and temperature, target surface nitrogen content, sputtered Al density, deposited mass) involved in the deposition process.

Wear studies on plasma-sprayed Al2O3 and 8mole% of Yttrium-stabilized ZrO2 composite coating on biomedical Ti-6Al-4V alloy for orthopedic joint application

PubMed Central

Ganapathy, Perumal; Manivasagam, Geetha; Rajamanickam, Asokamani; Natarajan, Alagumurthi

2015-01-01

This paper presents the wear characteristics of the composite ceramic coating made with Al2O3-40wt%8YSZ on the biomedical grade Ti-6Al-4V alloy (grade 5) used for total joint prosthetic components, with the aim of improving their tribological behavior. The coatings were deposited using a plasma spraying technique, and optimization of plasma parameters was performed using response surface methodology to obtain dense coating. The tribological behaviors of the coated and uncoated substrates were evaluated using a ball-on-plate sliding wear tester at 37°C in simulated body-fluid conditions. The microstructure of both the titanium alloy and coated specimen were examined using an optical microscope and scanning electron microscope. The hardness of the plasma-sprayed alumina–zirconia composite coatings was 2.5 times higher than that of the Ti-6Al-4V alloy, while the wear rate of Ti-6Al-4V alloy was 253 times higher than that of the composite-coated Ti-6Al-4V alloy. The superior wear resistance of the alumina–zirconia coated alloy is attributed to its enhanced hardness and intersplat bonding strength. Wear-track examination showed that the predominant wear mechanism of Ti-6Al-4V alloy was abrasive and adhesive wear, whereas, in the case of alumina–zirconia composite coated alloy, the wear was dominated by microchipping and microcracking. PMID:26491323

FIP BIAS EVOLUTION IN A DECAYING ACTIVE REGION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, D.; Yardley, S. L.; Driel-Gesztelyi, L. van

Solar coronal plasma composition is typically characterized by first ionization potential (FIP) bias. Using spectra obtained by Hinode’s EUV Imaging Spectrometer instrument, we present a series of large-scale, spatially resolved composition maps of active region (AR)11389. The composition maps show how FIP bias evolves within the decaying AR during the period 2012 January 4–6. Globally, FIP bias decreases throughout the AR. We analyzed areas of significant plasma composition changes within the decaying AR and found that small-scale evolution in the photospheric magnetic field is closely linked to the FIP bias evolution observed in the corona. During the AR’s decay phase,more » small bipoles emerging within supergranular cells reconnect with the pre-existing AR field, creating a pathway along which photospheric and coronal plasmas can mix. The mixing timescales are shorter than those of plasma enrichment processes. Eruptive activity also results in shifting the FIP bias closer to photospheric in the affected areas. Finally, the FIP bias still remains dominantly coronal only in a part of the AR’s high-flux density core. We conclude that in the decay phase of an AR’s lifetime, the FIP bias is becoming increasingly modulated by episodes of small-scale flux emergence, i.e., decreasing the AR’s overall FIP bias. Our results show that magnetic field evolution plays an important role in compositional changes during AR development, revealing a more complex relationship than expected from previous well-known Skylab results showing that FIP bias increases almost linearly with age in young ARs.« less

Characterization of Fatty Acid Composition in Bone Marrow Fluid From Postmenopausal Women: Modification After Hip Fracture.

PubMed

Miranda, Melissa; Pino, Ana María; Fuenzalida, Karen; Rosen, Clifford J; Seitz, Germán; Rodríguez, J Pablo

2016-10-01

Bone marrow adipose tissue (BMAT) is associated with low bone mass, although the functional consequences for skeletal maintenance of increased BMAT are currently unclear. BMAT might have a role in systemic energy metabolism, and could be an energy source as well as an endocrine organ for neighboring bone cells, releasing cytokines, adipokines and free fatty acids into the bone marrow microenvironment. The aim of the present report was to compare the fatty acid composition in the bone marrow supernatant fluid (BMSF) and blood plasma of postmenopausal women women (65-80 years old). BMSF was obtained after spinning the aspirated bone marrow samples; donors were classified as control, osteopenic or osteoporotic after dual-energy X-ray absorptiometry. Total lipids from human bone marrow fluid and plasma were extracted, converted to the corresponding methyl esters, and finally analyzed by a gas chromatographer coupled with a mass spectrometer. Results showed that fatty acid composition in BMSF was dynamic and distinct from blood plasma, implying significance in the locally produced lipids. The fatty acid composition in the BMSF was enriched in saturated fatty acid and decreased in unsaturated fatty acids as compared to blood plasma, but this relationship switched in women who suffered a hip fracture. On the other hand, there was no relationship between BMSF and bone mineral density. In conclusion, lipid composition of BMSF is distinct from the circulatory compartment, most likely reflecting the energy needs of the marrow compartment. J. Cell. Biochem. 117: 2370-2376, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

How can laboratory plasma experiments contribute to space and &astrophysics?

NASA Astrophysics Data System (ADS)

Yamada, M.

Plasma physics plays key role in a wide range of phenomena in the universe, from laboratory plasmas to the magnetosphere, the solar corona, and to the tenuous interstellar and intergalactic gas. Despite the huge difference in physical scales, there are striking similarities in plasma behavior of laboratory and space plasmas. Similar plasma physics problems have been investigated independently by both laboratory plasma physicists and astrophysicists. Since 1991, cross fertilization has been increased among laboratory plasma physicists and space physicists through meeting such as IPELS [Interrelationship between Plasma Experiments in the Laboratory and Space] meeting. The advances in laboratory plasma physics, along with the recent surge of astronomical data from satellites, make this moment ripe for research collaboration to further advance plasma physics and to obtain new understanding of key space and astrophysical phenomena. The recent NRC review of astronomy and astrophysics notes the benefit that can accrue from stronger connection to plasma physics. The present talk discusses how laboratory plasma studies can contribute to the fundamental understandings of the space and astrophysical phenomena by covering common key physics topics such as magnetic reconnection, dynamos, angular momentum transport, ion heating, and magnetic self-organization. In particular, it has recently been recognized that "physics -issue- dedicated" laboratory experiments can contribute significantly to the understanding of the fundamental physics for space-astrophysical phenomena since they can create fundamental physics processes in controlled manner and provide well-correlated plasma parameters at multiple plasma locations simultaneously. Such dedicated experiments not only can bring about better understanding of the fundamental physics processes but also can lead to findings of new physics principles as well as new ideas for fusion plasma confinement. Several dedicated experiments have provided the fundamental physics data for magnetic reconnection [1]. Linear plasma devices have been utilized to investigate Whistler waves and Alfven wave phenomena [2,3]. A rotating gallium disk experiment has been initiated to study magneto-rotational instability [4]. This talk also presents the most recent progress of these dedicated laboratory plasma research. 1. M. Yamada et al., Phys. Plasmas 4, 1936, (1997) 2. R. Stenzel, Phys. Rev. Lett. 65, 3001 (1991) 3. W. Gekelman et al, Plasma Phys. Contr. Fusion, v42, B15-B26, Suppl.12B (2000) 4. H. Ji, J. Goodman, A. Kageyama Mon. Not. R. Astron. Soc. 325, L1- (2001)

Plasma interactions determine the composition in pulsed laser deposited thin films

NASA Astrophysics Data System (ADS)

Chen, Jikun; Döbeli, Max; Stender, Dieter; Conder, Kazimierz; Wokaun, Alexander; Schneider, Christof W.; Lippert, Thomas

2014-09-01

Plasma chemistry and scattering strongly affect the congruent, elemental transfer during pulsed laser deposition of target metal species in an oxygen atmosphere. Studying the plasma properties of La0.6Sr0.4MnO3, we demonstrate for as grown La0.6Sr0.4MnO3-δ films that a congruent transfer of metallic species is achieved in two pressure windows: ˜10-3 mbar and ˜2 × 10-1 mbar. In the intermediate pressure range, La0.6Sr0.4MnO3-δ becomes cation deficient and simultaneously almost fully stoichiometric in oxygen. Important for thin film growth is the presence of negative atomic oxygen and under which conditions positive metal-oxygen ions are created in the plasma. This insight into the plasma chemistry shows why the pressure window to obtain films with a desired composition and crystalline structure is narrow and requires a careful adjustment of the process parameters.

The importance of selecting a proper biological milieu for protein corona analysis in vitro: Human plasma versus human serum.

PubMed

Mirshafiee, Vahid; Kim, Raehyun; Mahmoudi, Morteza; Kraft, Mary L

2016-06-01

Nanoparticle (NP) exposure to biological fluids in the body results in protein binding to the NP surface, which forms a protein coating that is called the "protein corona". To simplify studies of protein-NP interactions and protein corona formation, NPs are incubated with biological solutions, such as human serum or human plasma, and the effects of this exposure are characterized in vitro. Yet, how NP exposure to these two different biological milieus affects protein corona composition and cell response has not been investigated. Here, we explore the differences between the protein coronas that form when NPs are incubated in human serum versus human plasma. NP characterization indicated that NPs that were exposed to human plasma had higher amounts of proteins bound to their surfaces, and were slightly larger in size than those exposed to human serum. In addition, significant differences in corona composition were also detected with gel electrophoresis and liquid chromatography-mass spectrometry/mass spectrometry, where a higher fraction of coagulation proteins and complement factors were found on the plasma-exposed NPs. Flow cytometry and confocal microscopy showed that the uptake of plasma-exposed NPs was higher than that of serum-exposed NPs by RAW 264.7 macrophage immune cells, but not by NIH 3T3 fibroblast cells. This difference is likely due to the elevated amounts of opsonins, such as fibrinogen, on the surfaces of the NPs exposed to plasma, but not serum, because these components trigger NP internalization by immune cells. As the human plasma better mimics the composition of the in vivo environment, namely blood, in vitro protein corona studies should employ human plasma, and not human serum, so the biological phenomena that is observed is more similar to that occurring in vivo. Copyright © 2015 Elsevier Ltd. All rights reserved.

Time-Space Position of Warm Dense Matter in Laser Plasma Interaction Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, L F; Uschmann, I; Forster, E

2006-09-25

Laser plasma interaction experiments have been perform performed using an fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. Electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were cautiously compared with relevant 1D numerical simulation. Finally these results provide a first experience of searching for the time-space position of the so-called warm dense plasma in an ultra fast laser target interaction process. These experiments aim to prepare nearmore » solid-density plasmas for Thomson scattering experiments using the short wavelength free-electron laser FLASH, DESY Hamburg.« less

Dusty Plasma Effects in the Interplanetary Medium?

NASA Astrophysics Data System (ADS)

Mann, Ingrid; Issautier, Karine; Meyer-Vernet, Nicole; Le Chat, Gaétan; Czechowski, Andrzej; Zaslavsky, Arnaud; Zouganelis, Yannis; Belheouane, Soraya

Cosmic dust particles exist in a variety of compositions and sizes in the interplanetary medium. There is little direct information on the composition, but those interplanetary dust particles that are collected in the upper Earth’s atmosphere and can be studied in the laboratory typically have an irregular, sometimes porous structure on scales <100 nm. They contain magnesium-rich silicates and silicon carbide, iron-nickel and iron-sulfur compounds, calcium- and aluminum oxides, and chemical compounds that contain a large mass fraction of carbon (e.g. carbonaceous species). A fraction of the dust originates from comets, but because of their bulk material temperature of about 280 K near 1 AU, most icy compounds have disappeared. The dust particles are embedded in the solar wind, a hot plasma with at 1 AU kinetic temperatures around 100 000 K and flow direction nearly radial outward from the Sun at supersonic bulk velocities around 400 km/s. Since the dust particles carry an electric surface charge they are subject to electromagnetic forces and the nanodust particles are efficiently accelerated to velocities of order of solar wind speed. The acceleration of the nanodust is similar, but not identical to the formation of pick-up ions. The S/WAVES radio wave instrument on STEREO measured a flux of nanodust at 1 AU [1]. The nanodust probably forms in the region inward of 1 AU and is accelerated by the solar wind as discussed. We also discuss the different paths of dust - plasma interactions in the interplanetary medium and their observations with space experiments. Comparing these interactions we show that the interplanetary medium near 1 AU can in many cases be described as “dust in plasma" rather than "dusty plasma”. [1] S. Belheouane, N. Meyer-Vernet, K. Issautier, G. Le Chat, A. Zaslavsky, Y. Zouganelis, I. Mann, A. Czechowski: Dynamics of nanoparticles detected at 1 AU by S/WAVES onboard STEREO spacecraft, in this session.

Etching and oxidation of InAs in planar inductively coupled plasma

NASA Astrophysics Data System (ADS)

Dultsev, F. N.; Kesler, V. G.

2009-10-01

The surface of InAs (1 1 1)A was investigated under plasmachemical etching in the gas mixture CH 4/H 2/Ar. Etching was performed using the RF (13.56 MHz) and ICP plasma with the power 30-150 and 50-300 W, respectively; gas pressure in the reactor was 3-10 mTorr. It was demonstrated that the composition of the subsurface layer less than 5 nm thick changes during plasmachemical etching. A method of deep etching of InAs involving ICP plasma and hydrocarbon based chemistry providing the conservation of the surface relief is proposed. Optimal conditions and the composition of the gas phase for plasmachemical etching ensuring acceptable etch rates were selected.

The calculation of thermophysical properties of nickel plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apfelbaum, E. M.

2015-09-15

The thermophysical properties of Nickel plasma have been calculated for the temperatures 10–60 kK and densities less than 1 g/cm{sup 3}. These properties are the pressure, internal energy, heat capacity, and the electronic transport coefficients (electrical conductivity, thermal conductivity, and thermal power). The thermodynamic values have been calculated by means of the chemical model, which also allows one to obtain the ionic composition of considered plasma. The composition has been used to calculate the electronic transport coefficients within the relaxation time approximation. The results of the present investigation have been compared with the calculations of other researchers and available data ofmore » measurements.« less

CCE plasma wave observations during the storm of September 4, 5, 1984. [Charge Composition Explorer

NASA Technical Reports Server (NTRS)

Scarf, F. L.

1985-01-01

Near 0700 on September 4, 1984 a series of interplanetary discontinuities arrived at earth when the AMPTE Charge Composition Explorer (CCE) was near apogee. During the next few hours the spacecraft passed in and out of the magnetosheath. At the magnetopause boundary, the CCE wave instrument detected strong electron plasma oscillations, weaker electromagnetic waves at the electron plasma frequency, and broadband electrostatic waves. During the subsequent perigee passes on September 4 and 5, the wave observations of upper hybrid resonance emissions, continuum radiation, electrostatic noise bands and unusual low latitude auroral kilometic radiation were used to monitor significant variations in the magnetospheric characteristics as the main storm phases developed.

Spectral analysis of meteorites ablated in a wind tunnel

NASA Astrophysics Data System (ADS)

Drouard, A.; Vernazza, P.; Loehle, S.; Gattacceca, J.; Zander, T.; Eberhart, M.; Meindl, A.; Oefele, R.; Vaubaillon, J.; Colas, F.

2017-09-01

Recently and for the very first time, experiments simulating vaporization of a meteorite sample were performed in a wind tunnel near Stuttgart with the specific aim to record emission spectra of the vaporized material. Using a high enthalpy air plasma flow for modeling an equivalent air friction of an entry speed of about 10 km/s, three meteorite types (H, CM and HED) and two meteoritical analogues (basalt and argillite) were ablated and high resolution spectra were recorded simultaneously. After the identification of all atomic lines, we per- formed a detailed study of our spectra using two approaches: (i) by direct comparison of multiplet in- tensities between the samples and (ii) by computation of a synthetic spectrum to constrain some physical parameters (temperature, elemental abundance). Finally, we compared our results to the elemental composition of our samples and we determined how much compositional information can be retrieved for a given meteor using visible sectroscopy.

Al2O3-TiC Composite Prepared by Spark Plasma Sintering Process: Evaluation of Mechanical and Tribological Properties

NASA Astrophysics Data System (ADS)

Kumar, Rohit; Chaubey, A. K.; Bathula, Sivaiah; Prashanth, K. G.; Dhar, Ajay

2018-03-01

Al2O3-10TiC composites were synthesized by spark plasma sintering (SPS) process. Microstructural and mechanical properties of the composite reveal homogeneous distribution of the fine TiC particles in the matrix. The samples were produced with different sintering temperature, and it shows that the hardness and density gradually increases with increasing sintering temperature. Abrasion wear test result reveals that the composite sintered at 1500 °C shows high abrasion resistance (wt. loss 0.016 g) and the lowest abrasion resistance was observed for the composite sample sintered at 1100 °C (wt. loss 1.459 g). The profilometry surface roughness study shows that sample sintered at 1100 °C shows maximum roughness ( R a = 6.53 µm) compared to the sample sintered at 1500 °C ( R a = 0.66 µm) corroborating the abrasion wear test results.

ZrB2-CNTs Nanocomposites Fabricated by Spark Plasma Sintering

PubMed Central

Jin, Hua; Meng, Songhe; Xie, Weihua; Xu, Chenghai; Niu, Jiahong

2016-01-01

ZrB2-based nanocomposites with and without carbon nanotubes (CNTs) as reinforcement were prepared at 1600 °C by spark plasma sintering. The effects of CNTs on the microstructure and mechanical properties of nano-ZrB2 matrix composites were studied. The results indicated that adding CNTs can inhibit the abnormal grain growth of ZrB2 grains and improve the fracture toughness of the composites. The toughness mechanisms were crack deflection, crack bridging, debonding, and pull-out of CNTs. The experimental results of the nanograined ZrB2-CNTs composites were compared with those of the micro-grained ZrB2-CNTs composites. Due to the small size and surface effects, the nanograined ZrB2-CNTs composites exhibited stronger mechanical properties: the hardness, flexural strength and fracture toughness were 18.7 ± 0.2 GPa, 1016 ± 75 MPa, and 8.5 ± 0.4 MPa·m1/2, respectively. PMID:28774087

ZrB₂-CNTs Nanocomposites Fabricated by Spark Plasma Sintering.

PubMed

Jin, Hua; Meng, Songhe; Xie, Weihua; Xu, Chenghai; Niu, Jiahong

2016-11-29

ZrB₂-based nanocomposites with and without carbon nanotubes (CNTs) as reinforcement were prepared at 1600 °C by spark plasma sintering. The effects of CNTs on the microstructure and mechanical properties of nano-ZrB₂ matrix composites were studied. The results indicated that adding CNTs can inhibit the abnormal grain growth of ZrB₂ grains and improve the fracture toughness of the composites. The toughness mechanisms were crack deflection, crack bridging, debonding, and pull-out of CNTs. The experimental results of the nanograined ZrB₂-CNTs composites were compared with those of the micro-grained ZrB₂-CNTs composites. Due to the small size and surface effects, the nanograined ZrB₂-CNTs composites exhibited stronger mechanical properties: the hardness, flexural strength and fracture toughness were 18.7 ± 0.2 GPa, 1016 ± 75 MPa, and 8.5 ± 0.4 MPa·m 1/2 , respectively.

Contoured-gap coaxial guns for imploding plasma liner experiments

NASA Astrophysics Data System (ADS)

Witherspoon, F. D.; Case, A.; Brockington, S.; Cassibry, J. T.; Hsu, S. C.

2014-10-01

Arrays of supersonic, high momentum flux plasma jets can be used as standoff compression drivers for generating spherically imploding plasma liners for driving magneto-inertial fusion, hence the name plasma-jet-driven MIF (PJMIF). HyperV developed linear plasma jets for the Plasma Liner Experiment (PLX) at LANL where two guns were successfully tested. Further development at HyperV resulted in achieving the PLX goal of 8000 μg at 50 km/s. Prior work on contoured-gap coaxial guns demonstrated an approach to control the blowby instability and achieved substantial performance improvements. For future plasma liner experiments we propose to use contoured-gap coaxial guns with small Minirailgun injectors. We will describe such a gun for a 60-gun plasma liner experiment. Discussion topics will include impurity control, plasma jet symmetry and topology (esp. related to uniformity and compactness), velocity capability, and techniques planned for achieving gun efficiency of >50% using tailored impedance matched pulse forming networks. Mach2 and UAH SPH code simulations will be included. Work supported by US DOE DE-FG02-05ER54810.

Characterizing low-Z erosion and deposition in the DIII-D divertor using aluminum

DOE PAGES

Chrobak, Chris P.; Doerner, R. P.; Stangeby, Peter C.; ...

2017-01-28

Here, we present measurements and modeling of aluminum erosion and redeposition experiments in separate helium and deuterium low power, low density L-mode plasmas at the outer divertor strike point of DIII-D to provide a low-Z material benchmark dataset for tokamak erosion-deposition modeling codes. Coatings of Al ~100nm thick were applied to ideal (smooth) and realistic (rough) surfaces and exposed to repeat plasma discharges using the DiMES probe. Redeposition and re-erosion in all cases was primarily in the downstream toroidal field direction, evident from both in-situ spectroscopic and post-mortem non spectroscopic measurements. The gross Al erosion yield estimated from both Hemore » and D plasma exposures was ~40-70% of the expected erosion yield based on theoretical physical sputtering yields. However, the multi-step redeposition and re-erosion process, and hence the measured net erosion yield and material migration, was found to be influenced by the surface roughness and/or porosity. On rough surfaces, the fraction of the eroded Al coating found redeposited outside the original coating area was 25x higher than on smooth surfaces. The amount of Al found redeposited on the rough substrate was in fact proportional to the net eroded Al, suggesting an accumulation of deposited Al in surface pores and other areas shadowed from re-erosion. In order to determine the fraction and distribution of eroded Al returning to the surface, a simple model for erosion and redeposition was developed and fitted to the measurements. The model presented here reproduces many of the observed results in these experiments by using theoretically calculated sputtering yields, calculating surface composition changes and erosion rates in time, assuming a spatial distribution function for redepositing atoms, and accounting for deposit trapping in pores. The results of the model fits reveal that total redeposition fraction increases with higher plasma temperature (~30% for 15-18eV plasmas, and ~45% for 25-30eV plasmas), and that 50% of the atoms redepositing on rough surfaces accumulated in shadowed areas.« less

Drift kinetic effects on the plasma response in high beta spherical tokamak experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhirui; Park, Jong-Kyu; Menard, Jonathan E.

The high β plasma response to rotating n = 1 external magnetic perturbations is numerically studied and compared with the National Spherical Torus Experiment (NSTX). The hybrid magnetohydrodynamic(MHD)-kinetic modeling shows that drift kinetic effects are important in resolving the disagreement of plasma response between the ideal MHD prediction and the NSTX experimental observation when plasma pressure reaches and exceeds the no-wall limit. Since the external rotating fields and high plasma rotation are presented in the NSTX experiments, the importance of the resistive wall effect and plasma rotation in determining the plasma response is also identified, where the resistive wall suppressesmore » the plasma response through the wall eddy current. The inertial energy due to plasma rotation destabilizes the plasma. In conclusion, the complexity of the plasma response in this study indicates that MHD modeling, including comprehensive physics, e.g. the drift kinetic effects, resistive wall and plasma rotation, are essential in order to reliably predict the plasma behavior in a high beta spherical tokamak device.« less

Drift kinetic effects on the plasma response in high beta spherical tokamak experiments

DOE PAGES

Wang, Zhirui; Park, Jong-Kyu; Menard, Jonathan E.; ...

2017-09-21

The high β plasma response to rotating n = 1 external magnetic perturbations is numerically studied and compared with the National Spherical Torus Experiment (NSTX). The hybrid magnetohydrodynamic(MHD)-kinetic modeling shows that drift kinetic effects are important in resolving the disagreement of plasma response between the ideal MHD prediction and the NSTX experimental observation when plasma pressure reaches and exceeds the no-wall limit. Since the external rotating fields and high plasma rotation are presented in the NSTX experiments, the importance of the resistive wall effect and plasma rotation in determining the plasma response is also identified, where the resistive wall suppressesmore » the plasma response through the wall eddy current. The inertial energy due to plasma rotation destabilizes the plasma. In conclusion, the complexity of the plasma response in this study indicates that MHD modeling, including comprehensive physics, e.g. the drift kinetic effects, resistive wall and plasma rotation, are essential in order to reliably predict the plasma behavior in a high beta spherical tokamak device.« less

Characterizing the effects of regolith surface roughness on photoemission from surfaces in space

NASA Astrophysics Data System (ADS)

Dove, A.; Horanyi, M.; Wang, X.

2017-12-01

Surfaces of airless bodies and spacecraft in space are exposed to a variety of charging environments. A balance of currents due to plasma bombardment, photoemission, electron and ion emission and collection, and secondary electron emission determines the surface's charge. Photoelectron emission is the dominant charging process on sunlit surfaces in the inner solar system due to the intense solar UV radiation. This can result in a net positive surface potential, with a cloud of photoelectrons immediately above the surface, called the photoelectron sheath. Conversely, the unlit side of the body will charge negatively due the collection of the fast-moving solar wind electrons. The interaction of charged dust grains with these positively and negatively charged surfaces, and within the photoelectron and plasma sheaths may explain the occurrence of dust lofting, levitation and transport above the lunar surface. The surface potential of exposed objects is also dependent on the material properties of their surfaces. Composition and particle size primarily affect the quantum efficiency of photoelectron generation; however, surface roughness can also control the charging process. In order to characterize these effects, we have conducted laboratory experiments to examine the role of surface roughness in generating photoelectrons in dedicated laboratory experiments using solid and dusty surfaces of the same composition (CeO2), and initial comparisons with JSC-1 lunar simulant. Using Langmuir probe measurements, we explore the measured potentials above insulating surfaces exposed to UV and an electric field, and we show that the photoemission current from a dusty surface is largely reduced due to its higher surface roughness, which causes a significant fraction of the emitted photoelectrons to be re-absorbed within the surface. We will discuss these results in context of similar situations on planetary surfaces.

Modelling of transitions between L- and H-mode in JET high plasma current plasmas and application to ITER scenarios including tungsten behaviour

NASA Astrophysics Data System (ADS)

Koechl, F.; Loarte, A.; Parail, V.; Belo, P.; Brix, M.; Corrigan, G.; Harting, D.; Koskela, T.; Kukushkin, A. S.; Polevoi, A. R.; Romanelli, M.; Saibene, G.; Sartori, R.; Eich, T.; Contributors, JET

2017-08-01

The dynamics for the transition from L-mode to a stationary high Q DT H-mode regime in ITER is expected to be qualitatively different to present experiments. Differences may be caused by a low fuelling efficiency of recycling neutrals, that influence the post transition plasma density evolution on the one hand. On the other hand, the effect of the plasma density evolution itself both on the alpha heating power and the edge power flow required to sustain the H-mode confinement itself needs to be considered. This paper presents results of modelling studies of the transition to stationary high Q DT H-mode regime in ITER with the JINTRAC suite of codes, which include optimisation of the plasma density evolution to ensure a robust achievement of high Q DT regimes in ITER on the one hand and the avoidance of tungsten accumulation in this transient phase on the other hand. As a first step, the JINTRAC integrated models have been validated in fully predictive simulations (excluding core momentum transport which is prescribed) against core, pedestal and divertor plasma measurements in JET C-wall experiments for the transition from L-mode to stationary H-mode in partially ITER relevant conditions (highest achievable current and power, H 98,y ~ 1.0, low collisionality, comparable evolution in P net/P L-H, but different ρ *, T i/T e, Mach number and plasma composition compared to ITER expectations). The selection of transport models (core: NCLASS  +  Bohm/gyroBohm in L-mode/GLF23 in H-mode) was determined by a trade-off between model complexity and efficiency. Good agreement between code predictions and measured plasma parameters is obtained if anomalous heat and particle transport in the edge transport barrier are assumed to be reduced at different rates with increasing edge power flow normalised to the H-mode threshold; in particular the increase in edge plasma density is dominated by this edge transport reduction as the calculated neutral influx across the separatrix remains unchanged (or even slightly decreases) following the H-mode transition. JINTRAC modelling of H-mode transitions for the ITER 15 MA / 5.3 T high Q DT scenarios with the same modelling assumptions as those being derived from JET experiments has been carried out. The modelling finds that it is possible to access high Q DT conditions robustly for additional heating power levels of P AUX  ⩾  53 MW by optimising core and edge plasma fuelling in the transition from L-mode to high Q DT H-mode. An initial period of low plasma density, in which the plasma accesses the H-mode regime and the alpha heating power increases, needs to be considered after the start of the additional heating, which is then followed by a slow density ramp. Both the duration of the low density phase and the density ramp-rate depend on boundary and operational conditions and can be optimised to minimise the resistive flux consumption in this transition phase. The modelling also shows that fuelling schemes optimised for a robust access to high Q DT H-mode in ITER are also optimum for the prevention of the contamination of the core plasma by tungsten during this phase.

Effect of Spark-Plasma-Sintering Conditions on Tensile Properties of Aluminum Matrix Composites Reinforced with Multiwalled Carbon Nanotubes (MWCNTs)

NASA Astrophysics Data System (ADS)

Chen, B.; Imai, H.; Umeda, J.; Takahashi, M.; Kondoh, K.

2017-04-01

In this study, aluminum (Al) matrix composites containing 2 wt.% multiwalled carbon nanotubes (CNTs) were fabricated by powder metallurgy using high-energy ball milling (HEBM), spark plasma sintering (SPS), and subsequent hot extrusion. The effect of SPS conditions on the tensile properties of CNT/Al composites was investigated. The results showed that composites with well-dispersed CNTs and nearly full-density CNT/Al can be obtained. During HEBM, CNTs were shortened, inserted into welded Al powder particles, bonded to Al, and still stable without CNT-Al reaction. After consolidation, Al4C3 phases formed in composites under different sintering conditions. With the increase of sintering temperature and holding time, the strength decreased. Conversely, the ductility and toughness noticeably increased. As a result, a good balance between strength (367 MPa in ultimate tensile strength) and ductility (13% in elongation) was achieved in the as-extruded CNT/Al composite sintered at 630°C with a holding time of 300 min.

A comparative study of the reduction of silver and gold salts in water by a cathodic microplasma electrode

NASA Astrophysics Data System (ADS)

De Vos, Caroline; Baneton, Joffrey; Witzke, Megan; Dille, Jean; Godet, Stéphane; Gordon, Michael J.; Mohan Sankaran, R.; Reniers, François

2017-03-01

A comparative study of the reduction of aqueous silver (Ag) and gold (Au) salts to colloidal Ag and Au nanoparticles, respectively, by a gaseous, cathodic, atmospheric-pressure microplasma electrode is presented. The resulting nanoparticles (NPs) were characterized by ultraviolet-visible (UV-vis) absorption spectroscopy and transmission electron microscopy (TEM), and the aqueous solution composition before and after experiments was determined by ionic conductivity, electrochemical potential, and/or UV-vis absorption measurements. TEM showed that Ag and Au NPs were spherical and non-agglomerated when synthesized in the presence of a stabilizer, polyvinyl alcohol. The charge injected by the plasma was correlated to the maximum intensity in the absorbance spectra which in turn depends on the nanoparticle concentration. Separately, the charge injected was correlated to the metal cation concentration. Ag and Au reduction rates were found to be directly proportional to the charge injected, independent of plasma current and process time. Differences in the mechanism for Ag and Au reduction were also observed, and solution species generated by the plasma and their role in the reduction process (e.g. H2O2, electrons) is discussed.

B{sub 4}C-SiC reaction-sintered coatings on graphite plasma facing components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valentine, P.G.; Trester, P.W.; Winter, J.

1994-05-01

Boron carbide plus silicon carbide (B{sub 4}C-SiC) reaction-sintered coatings for use on graphite plasma-facing components were developed. Such coatings are of interest in TEXTOR tokamak limiter-plasma interactions as a means of reducing carbon erosion, of providing a preferred release of boron for oxygen gettering, and of investigating silicon`s effect on radiative edge phenomena. Specimens evaluated had (a) either Ringsdorfwerke EK 98 graphite or Le Carbon Lorraine felt-type AEROLOR A05 CFC substrates; (b) multiphase coatings, comprised of B{sub 4}C, Sic, and graphite; (c) nominal coating compositions of 69 wt.-% B{sub 4}C + 31 wt.-% SiC; and (d) nominal coating thicknesses betweenmore » 250 and 775 {mu}m. Coated coupons were evaluated by high heat flux experiments in the JUDITH (electron beam) test facility at KFA. Simulated disruptions, with energy densities up to 10 MJm{sup {minus}2}, and normal operation simulations, with power densities up to 12 MWm{sup {minus}2}, were conducted. The coatings remained adherent; at the highest levels tested, minor changes occurred, including localized remelting, modification of the crystallographic phases, occasional microcracking, and erosion.« less

Modulation of the Lactobacillus acidophilus La-5 lipidome by different growth conditions.

PubMed

Hansen, Marie-Louise R W; Clausen, Anders; Ejsing, Christer S; Risbo, Jens

2015-10-01

Probiotics are bacteria used in the food industry due to their potential health benefits. In this study, the plasma membrane of the probiotic Lactobacillus acidophilus La-5 was investigated using state-of-the-art high-resolution shotgun lipidomics. Comparisons of the lipidome of the plasma membrane were done after altering the fatty acid composition by supplementing L. acidophilus La-5 with saturated, mono-, di- and tri-unsaturated fatty acids during fermentation. The plasma membrane with the highest degree of saturation resulted in a lipid composition with the highest proportion of cardiolipin (CL) and lowest proportion of monolysocardiolipin (MLCL). No significant changes were found for other lipid classes. The bacteria grown with di- and tri-unsaturated fatty acids were expected to have more unsaturated plasma membranes than bacteria grown with mono-unsaturated fatty acids. This was also the case for MLCL, but the numbers of double bonds for CL were quite similar for these three samples. The results indicate that L. acidophilus La-5 possesses a molecular mechanism for remodelling and optimizing the fatty acid composition of CL and MLCL species and the molar ratio of CL and MLCL. This study contributes new knowledge on the previously uninvestigated lipidome of L. acidophilus La-5.

System and process for dissolution of solids

DOEpatents

Liezers, Martin; Farmer, III, Orville T.

2017-10-10

A system and process are disclosed for dissolution of solids and "difficult-to-dissolve" solids. A solid sample may be ablated in an ablation device to generate nanoscale particles. Nanoparticles may then swept into a coupled plasma device operating at atmospheric pressure where the solid nanoparticles are atomized. The plasma exhaust may be delivered directly into an aqueous fluid to form a solution containing the atomized and dissolved solids. The composition of the resulting solution reflects the composition of the original solid sample.

Manufacturing of composite titanium-titanium nitride coatings by reactive very low pressure plasma spraying (R-VLPPS)

NASA Astrophysics Data System (ADS)

Vautherin, B.; Planche, M.-P.; Quet, A.; Bianchi, L.; Montavon, G.

2014-11-01

Very Low Pressure Plasma Spraying (VLPPS) is an emerging spray process nowadays intensively studied by many research centers in the World. To date, studies are mostly focused on the manufacturing of ceramic or metallic coatings. None refers to composite coatings manufacturing by reactive plasma spraying under very low pressure (i.e., ~150 Pa). This paper aims at presenting the carried-out developments and some results concerning the manufacturing of composite coatings by reactive spraying. Titanium was selected as metallic material in order to deposit titanium-nitride titanium coatings (Ti-TiN). Nitrogen was used as plasma gas and was injected along an Ar-H2-N2 plasma jet via a secondary injector in order to reach the nitrogen content on the substrate surface. Thus, different kind of reactive mechanisms were highlighted. Resulting coatings were characterized by Scanning Electron Microscopy (SEM) observations. Porous microstructures are clearly identified and the deposits exhibit condensed vapours and molten particles. Glow Discharge Optical Emission Spectroscopy (GDOES) analysis evidenced nitrogen inside the deposits and X-Ray Diffraction (XRD) analysis confirmed the formation of titanium nitride phases, such as TiN and Ti2N, depending upon the location of the nitrogen injection. Microhardness values as high as 800 VHN were measured on manufactured samples (to be compared to 220 VHN for pure titanium VLPPS-manufactured coatings).

Plasma and white adipose tissue lipid composition in marmots.

PubMed

Florant, G L; Nuttle, L C; Mullinex, D E; Rintoul, D A

1990-05-01

White adipose tissue biopsies and plasma samples were obtained from hibernating yellow-bellied marmots (Marmota flaviventris) maintained in the laboratory. In addition, biopsies and plasma samples were obtained from normothermic animals in the field and laboratory. Measurement of plasma free fatty acid (FA) levels indicated that winter laboratory animals exhibited increased lipolysis. Additionally, analysis of white adipose tissue triacylglycerol revealed that the FA composition of the storage fat in animals maintained on the standard laboratory diet is remarkably simple and uniform between different adipose depots in the same animal. Three FAs (palmitic, oleic, and linoleic acids) made up greater than 95% of the total. Triene (alpha-linolenate) was found in newly captured animals, but the percentage of this FA decreased rapidly when the animals were maintained on the standard laboratory diet. Throughout the hibernation season (October to April), white adipose tissue-saturated FA percentage decreased, monoene percentage remained constant, and diene percentage increased. Analysis of plasma FA composition suggested that these animals tended to metabolize saturated FAs from stored lipid during hibernation and that dienes were mobilized briefly after the last arousal from hibernation in spring. From these observations, we hypothesize that marmots preferentially metabolize saturated fats during the hibernation period and that essential FAs of the omega 6 series tend to be metabolized more slowly than other FAs. These characteristics suggest that marmots are a valuable animal model in which to study lipid metabolism.

Diamond growth on copper rods from polymer composite nanofibres

NASA Astrophysics Data System (ADS)

Varga, M.; Potocky, S.; Tesarek, P.; Babchenko, O.; Davydova, M.; Kromka, A.

2014-09-01

The potential uses of diamond films can be found in a diverse range of industrial applications. However, deposition of diamond films onto some foreign materials is still not a simple task. Here we present the growth of adherent diamond films on copper rods with the focus on substrate pre-treatment by polyvinyl alcohol composite nanofibres. The primary role of the polymer fibres substantially act as a carbon source which enhances the diamond nucleation and accelerates a homogenous CVD growth. Diamond growth was carried out in pulsed linear antenna microwave chemical vapour deposition system, which is characterized by cold plasma due to larger distance of hot plasma region from the substrate, at various gas compositions. The large distance between plasma source and the substrate holder also allows the uniform deposition of diamond on a large number of substrates with complex geometry (3D objects) as well as for the vertically positioned substrates. Moreover, the inhomogeneity in diamond film thickness deposited on vertically positioned substrates was suppressed by using polyvinyl alcohol nanofibre textile. Combination of PVA polymer fibres use together with this unique deposition system leads to a successful overcoating of the copper rods by continuous diamond film without the film cracking or delamination. We propose that the sequence of plasma-chemical reactions enhances the transformation of certain number of carbon atoms into the sp3-bonded form which further are stabilized by atomic hydrogen coming from plasma.

Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

NASA Astrophysics Data System (ADS)

Bakhsheshi-Rad, H. R.; Hamzah, E.; Bagheriyan, S.; Daroonparvar, M.; Kasiri-Asgarani, M.; Shah, A. M.; Medraj, M.

2016-09-01

A triplex plasma (NiCoCrAlHfYSi/Al2O3·13%TiO2)/polycaprolactone composite coating was successfully deposited on a Mg-1.2Ca alloy by a combination of atmospheric plasma spraying and dip-coating techniques. The NiCoCrAlHfYSi (MCrAlHYS) coating, as the first layer, contained a large number of voids, globular porosities, and micro-cracks with a thickness of 40-50 μm, while the Al2O3·13%TiO2 coating, as the second layer, presented a unique bimodal microstructure with a thickness of 70-80 μm. The top layer was a hydrophobic polymer, which effectively sealed the porosities of plasma layers. The results of micro-hardness and bonding strength tests showed that the plasma coating presented excellent hardness (870 HV) and good bonding strength (14.8 MPa). However, the plasma/polymer coatings interface exhibited low bonding strength (8.6 MPa). The polymer coating formed thick layer (100-110 μm) that homogeneously covered the surface of the plasma layers. Contact angle measurement showed that polymer coating over plasma layers significantly decreased surface wettability. The corrosion current density ( i corr) of an uncoated sample (262.7 µA/cm2) decreased to 76.9 µA/cm2 after plasma coatings were applied. However, it was found that the i corr decreased significantly to 0.002 µA/cm2 after polymer sealing of the porous plasma layers.

Plasma contactor research, 1989

NASA Technical Reports Server (NTRS)

Williams, John D.

1990-01-01

The characteristics of double layers observed by researchers investigating magnetospheric phenomena are contrasted to those observed in plasma contacting experiments. Experiments in the electron collection mode of the plasma contacting process were performed and the results confirm a simple model of this process for current levels ranging to 3 A. Experimental results were also obtained in a study of the process of electron emission from a hollow cathode plasma contactor. High energy ions are observed coming from the cathode in addition to the electrons and a phenomenological model that suggests a mechanism by which this could occur is presented. Experimental results showing the effects of the design parameters of the ambient plasma simulator on the plasma potential, electron temperature, electron density and plasma noise levels induced in plasma contacting experiments are presented. A preferred simulator design is selected on the basis of these results.

Isotope effects on L-H threshold and confinement in tokamak plasmas

NASA Astrophysics Data System (ADS)

Maggi, C. F.; Weisen, H.; Hillesheim, J. C.; Chankin, A.; Delabie, E.; Horvath, L.; Auriemma, F.; Carvalho, I. S.; Corrigan, G.; Flanagan, J.; Garzotti, L.; Keeling, D.; King, D.; Lerche, E.; Lorenzini, R.; Maslov, M.; Menmuir, S.; Saarelma, S.; Sips, A. C. C.; Solano, E. R.; Belonohy, E.; Casson, F. J.; Challis, C.; Giroud, C.; Parail, V.; Silva, C.; Valisa, M.; Contributors, JET

2018-01-01

The dependence of plasma transport and confinement on the main hydrogenic ion isotope mass is of fundamental importance for understanding turbulent transport and, therefore, for accurate extrapolations of confinement from present tokamak experiments, which typically use a single hydrogen isotope, to burning plasmas such as ITER, which will operate in deuterium-tritium mixtures. Knowledge of the dependence of plasma properties and edge transport barrier formation on main ion species is critical in view of the initial, low-activation phase of ITER operations in hydrogen or helium and of its implications on the subsequent operation in deuterium-tritium. The favourable scaling of global energy confinement time with isotope mass, which has been observed in many tokamak experiments, remains largely unexplained theoretically. Moreover, the mass scaling observed in experiments varies depending on the plasma edge conditions. In preparation for upcoming deuterium-tritium experiments in the JET tokamak with the ITER-like Be/W Wall (JET-ILW), a thorough experimental investigation of isotope effects in hydrogen, deuterium and tritium plasmas is being carried out, in order to provide stringent tests of plasma energy, particle and momentum transport models. Recent hydrogen and deuterium isotope experiments in JET-ILW on L-H power threshold, L-mode and H-mode confinement are reviewed and discussed in the context of past and more recent isotope experiments in tokamak plasmas, highlighting common elements as well as contrasting observations that have been reported. The experimental findings are discussed in the context of fundamental aspects of plasma transport models.

Numerical-experimental analysis of a carbon-phenolic composite via plasma jet ablation test

NASA Astrophysics Data System (ADS)

Guilherme Silva Pesci, Pedro; Araújo Machado, Humberto; Silva, Homero de Paula e.; Cley Paterniani Rita, Cristian; Petraconi Filho, Gilberto; Cocchieri Botelho, Edson

2018-06-01

Materials used in space vehicles components are subjected to thermally aggressive environments when exposed to atmospheric reentry. In order to protect the payload and the vehicle itself, ablative composites are employed as TPS (Thermal Protection System). The development of TPS materials generally go through phases of obtaining, atmospheric reentry tests and comparison with a mathematical model. The state of the art presents some reentry tests in a subsonic or supersonic arc-jet facility, and a complex type of mathematical model, which normally requires large computational cost. This work presents a reliable method for estimate the performance of ablative composites, combining empirical and experimental data. Tests of composite materials used in thermal protection systems through exposure to a plasma jet are performed, where the heat fluxes emulate those present in atmospheric reentry of space vehicles components. The carbon/phenolic material samples have been performed in the hypersonic plasma tunnel of Plasma and Process Laboratory, available in Aeronautics Institute of Technology (ITA), by a plasma torch with a 50 kW DC power source. The plasma tunnel parameters were optimized to reproduce the conditions close to the critical re-entry point of the space vehicles payloads developed by the Aeronautics and Space Institute (IAE). The specimens in study were developed and manufactured in Brazil. Mass loss and specific mass loss rates of the samples and the back surface temperatures, as a function of the exposure time to the thermal flow, were determined. A computational simulation based in a two-front ablation model was performed, in order to compare the tests and the simulation results. The results allowed to estimate the ablative behavior of the tested material and to validate the theoretical model used in the computational simulation for its use in geometries close to the thermal protection systems used in the Brazilian space and suborbital vehicles.

Effect of tanniniferous Terminalia chebula extract on rumen biohydrogenation, ∆(9)-desaturase activity, CLA content and fatty acid composition in longissimus dorsi muscle of kids.

PubMed

Rana, Madhu Suman; Tyagi, A; Hossain, Sk Asraf; Tyagi, A K

2012-03-01

Conjugated linoleic acid, a fatty acid found in milk fat and ruminant meat is one of the functional food components. Modifying fatty acid composition so as to increase CLA and other beneficial PUFA/MUFA level and reducing SFA levels might be a key to enhance the neutraceutical and therapeutic value of ruminant-derived food products. In the present experiment, the effect of supplementation of polyphenol rich Terminalia chebula plant extract at different concentrations (1.06g/kg and 3.18g/kg of body weight in T1 and T2 groups, respectively) was investigated on fatty acid composition of rumen fluid, plasma, intramuscular fat and Δ9-desaturase activity in longissimus dorsi muscle of crossbred kids. Total MUFA and PUFA content in muscle were enhanced by 25 and 35%, respectively, whereas SFA was reduced by 20% thereby improving the desaturation index. Δ9-desaturase activity also increased by 47% resulting in an enhancement of total CLA content (58.73%) in muscle. Copyright © 2011 Elsevier Ltd. All rights reserved.

Simulation of uranium and plutonium oxides compounds obtained in plasma

NASA Astrophysics Data System (ADS)

Novoselov, Ivan Yu.; Karengin, Alexander G.; Babaev, Renat G.

2018-03-01

The aim of this paper is to carry out thermodynamic simulation of mixed plutonium and uranium oxides compounds obtained after plasma treatment of plutonium and uranium nitrates and to determine optimal water-salt-organic mixture composition as well as conditions for their plasma treatment (temperature, air mass fraction). Authors conclude that it needs to complete the treatment of nitric solutions in form of water-salt-organic mixtures to guarantee energy saving obtainment of oxide compounds for mixed-oxide fuel and explain the choice of chemical composition of water-salt-organic mixture. It has been confirmed that temperature of 1200 °C is optimal to practice the process. Authors have demonstrated that condensed products after plasma treatment of water-salt-organic mixture contains targeted products (uranium and plutonium oxides) and gaseous products are environmental friendly. In conclusion basic operational modes for practicing the process are showed.

Simulations of Atmospheric Plasma Arcs

NASA Astrophysics Data System (ADS)

Pearcy, Jacob; Chopra, Nirbhav; Jaworski, Michael

2017-10-01

We present the results of computer simulation of cylindrical plasma arcs with characteristics similar to those predicted to be relevant in magnetohydrodynamic (MHD) power conversion systems. These arcs, with core temperatures on the order of 1 eV, place stringent limitations on the lifetime of conventional electrodes used in such systems, suggesting that a detailed analysis of arc characteristics will be crucial in designing more robust electrode systems. Simulations utilize results from NASA's Chemical Equilibrium with Applications (CEA) program to solve the Elenbaas-Heller equation in a variety of plasma compositions, including approximations of coal-burning plasmas as well as pure gas discharges. The effect of carbon dioxide injection on arc characteristics, emulating discharges from molten carbonate salt electrodes, is also analyzed. Results include radial temperature profiles, composition maps, and current-voltage (IV) characteristics of these arcs. Work supported by DOE contract DE-AC02-09CH11466.

Composition of fatty acids in plasma and erythrocytes and eicosanoids level in patients with metabolic syndrome

PubMed Central

2011-01-01

Background Disturbances of the fatty acids composition in plasma and red blood cells and eicosanoid synthesis play an important role in the metabolic syndrome (MS) formation. Methods The observation group included 61 people with metabolic syndrome (30 patients with MS and normal levels of insulin, 31 people with MS and insulin resistance - IR). The parameters of carbohydrate and lipid metabolism in blood serum were examined. The composition of nonesterified fatty acids (NEFA), fatty acid (FA) of red blood cells lipids was analyzed by gas-liquid chromatography. Eicosanoids level in MS patients blood serum was studied by enzyme immunoassay. Results In MS patients in the absence of glucose-insulin homeostasis disturbances and in patients with IR the accumulation of polyunsaturated fatty acids (18:2 n6, 18:3 n3, 22:4 n6) and lower pool of saturated FA (12:0, 14:0, 16: 0, 17:0) in plasma were discovered. A deficit of polyunsaturated FA (18:3 n3, 20:4 n6) with a predominance of on-saturated FA (14:0, 18:0) in erythrocyte membranes was revealed. In MS patients regardless of the carbohydrate metabolism status high levels of leukotriene B4 and 6-keto-prostaglandin-F1α in serum were found. The development of IR in MS patients leads to increased synthesis of thromboxane A2. Conclusion The results revealed a disturbance in nonesterified fatty acids of plasma lipids and red blood cells, eicosanoid synthesis in MS patients. The breach of the plasma and cell membranes fatty acids compositions, synthesis of vasoactive and proinflammatory eicosanoids is an important pathogenetic part of the MS development. PMID:21595891

Translating plasma and whole blood fatty acid compositional data into the sum of eicosapentaenoic and docosahexaenoic acid in erythrocytes.

PubMed

Stark, Ken D; Aristizabal Henao, Juan J; Metherel, Adam H; Pilote, Louise

2016-01-01

Specific blood levels of eicosapentaenoic plus docosahexaenoic acid (EPA+DHA, wt% of total) in erythrocytes or "the omega-3 index" have been recommended for cardio-protection, but fatty acids are often measured in different blood fractions. The ability to estimate the % of EPA+DHA in erythrocytes from the fatty acid composition of other blood fractions would enable clinical assessments of omega-3 status when erythrocyte fractions are not available and increase the ability to compare blood levels of omega-3 fatty acids across clinical studies. The fatty acid composition of baseline plasma, erythrocytes and whole blood samples from participants (n=1104) in a prospective, multicenter study examining acute coronary syndrome were determined. The ability to predict the % of EPA+DHA in erythrocytes from other blood fractions were examined using bivariate and multiple linear regression modelling. Concordance analysis was also used to compare the actual erythrocytes EPA+DHA values to values estimated from other blood fractions. EPA+DHA in erythrocytes was significantly (p<0.001) correlated EPA+DHA in plasma (r(2)=0.54) and whole blood (r(2)=0.79). Using multiple linear regression to predict EPA+DHA in erythrocytes resulted in stronger coefficients of determination in both plasma (R(2)=0.70) and whole blood (R(2)=0.84). Concordance analyses indicated agreement between actual and estimated EPA+DHA in erythrocytes, although estimating from plasma fatty acids appears to require translation by categorization rather than by translation as continuous data. This study shows that the fatty acid composition of different blood fractions can be used to estimate erythrocyte EPA+DHA in a population with acute coronary syndrome. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hard TiCx/SiC/a-C:H nanocomposite thin films using pulsed high energy density plasma focus device

NASA Astrophysics Data System (ADS)

Umar, Z. A.; Rawat, R. S.; Tan, K. S.; Kumar, A. K.; Ahmad, R.; Hussain, T.; Kloc, C.; Chen, Z.; Shen, L.; Zhang, Z.

2013-04-01

Thin films of TiCx/SiC/a-C:H were synthesized on Si substrates using a complex mix of high energy density plasmas and instability accelerated energetic ions of filling gas species, emanated from hot and dense pinched plasma column, in dense plasma focus device. The conventional hollow copper anode of Mather type plasma focus device was replaced by solid titanium anode for synthesis of TiCx/SiC/a-C:H nanocomposite thin films using CH4:Ar admixture of (1:9, 3:7 and 5:5) for fixed 20 focus shots as well as with different number of focus shots with fixed CH4:Ar admixture ratio 3:7. XRD results showed the formation of crystalline TiCx/SiC phases for thin film synthesized using different number of focus shots with CH4:Ar admixture ratio fixed at 3:7. SEM results showed that the synthesized thin films consist of nanoparticle agglomerates and the size of agglomerates depended on the CH4:Ar admixture ratio as well as on the number of focus shots. Raman analysis showed the formation of polycrystalline/amorphous Si, SiC and a-C for different CH4:Ar ratio as well as for different number of focus shots. The XPS analysis confirmed the formation of TiCx/SiC/a-C:H composite thin film. Nanoindentation results showed that the hardness and elastic modulus values of composite thin films increased with increasing number of focus shots. Maximum values of hardness and elastic modulus at the surface of the composite thin film were found to be about 22 and 305 GPa, respectively for 30 focus shots confirming the successful synthesis of hard composite TiCx/SiC/a-C:H coatings.

Strength and failure analysis of composite-to-composite adhesive bonds with different surface treatments

NASA Astrophysics Data System (ADS)

Paranjpe, Nikhil; Alamir, Mohammed; Alonayni, Abdullah; Asmatulu, Eylem; Rahman, Muhammad M.; Asmatulu, Ramazan

2018-03-01

Adhesives are widely utilized materials in aviation, automotive, energy, defense, and marine industries. Adhesive joints are gradually supplanting mechanical fasteners because they are lightweight structures, thus making the assembly lighter and easier. They also act as a sealant to prevent a structural joint from galvanic corrosion and leakages. Adhesive bonds provide high joint strength because of the fact that the load is distributed uniformly on the joint surface, while in mechanical joints, the load is concentrated at one point, thus leading to stress at that point and in turn causing joint failures. This research concentrated on the analysis of bond strength and failure loads in adhesive joint of composite-to-composite surfaces. Different durations of plasma along with the detergent cleaning were conducted on the composite surfaces prior to the adhesive applications and curing processes. The joint strength of the composites increased about 34% when the surface was plasma treated for 12 minutes. It is concluded that the combination of different surface preparations, rather than only one type of surface treatment, provides an ideal joint quality for the composites.

A table top experiment to study plasma confined by a dipole magnet

NASA Astrophysics Data System (ADS)

Bhattacharjee, Sudeep; Baitha, Anuj Ram

2016-10-01

There has been a long quest to understand charged particle generation, confinement and underlying complex processes in a plasma confined by a dipole magnet. Our earth's magnetosphere is an example of such a naturally occurring system. A few laboratory experiments have been designed for such investigations, such as the Levitated Dipole Experiment (LDX) at MIT, the Terella experiment at Columbia university, and the Ring Trap-1 (RT-1) experiment at the University of Tokyo. However, these are large scale experiments, where the dipole magnetic field is created with superconducting coils, thereby, necessitating power supplies and stringent cryogenic requirements. We report a table top experiment to investigate important physical processes in a dipole plasma. A strong cylindrical permanent magnet, is employed to create the dipole field inside a vacuum chamber. The magnet is suspended and cooled by circulating chilled water. The plasma is heated by electromagnetic waves of 2.45 GHz and a second frequency in the range 6 - 11 GHz. Some of the initial results of measurements and numerical simulation of magnetic field, visual observations of the first plasma, and spatial measurements of plasma parameters will be presented.

Shapes of Spectral Lines of Nonuniform Plasma of Electric Arc Discharge Between Copper Electrodes

NASA Astrophysics Data System (ADS)

Babich, Ida L.; Boretskij, Viacheslav F.; Veklich, Anatoly N.

2007-09-01

The radial profiles of the temperature and electron density in the plasma of the free burning electric arc between copper electrodes are studied by optical spectroscopy techniques. The electron density and the temperature in plasma as initial parameters were used in the calculation of the plasma composition in local thermodynamic equilibrium (LTE) assumption. We used the Saha's equation for copper, nitrogen and oxygen, dissociation equation for nitrogen and oxygen, the equation of plasma electrical neutrality and Dalton's law as well. So, it would be possible to determine the amounts of metal vapours in plasma.

Erosion behavior of CVD 3C silicon carbide in inductively coupled plasmas

NASA Astrophysics Data System (ADS)

Brooks, Mitchell R.

2010-11-01

An electrostatic, capacitively coupled Planar Ion Flux (PIF) probe has been developed as a sensor for use in high volume reactive ion etch (RIE) chambers. An important factor in the design is the material used for the probe collection area that is exposed to the plasma. For use in inductively coupled plasma chambers, bulk-deposited, 3C silicon carbide (SiC) was chosen. The primary objective of this work was to characterize the erosion behavior of the probe tip throughout repeated cycling for 100 RF hours (RFH). Surface morphology, roughness, and composition were documented at the beginning and end of cycling. In addition, the mass of the probe tip was documented three times throughout the experiment. This was used to calculate the wear rate which averaged ~100 mug/RFH. Although physical and chemical mechanisms were evident, it appears that preferential sputtering at pre-existing surface defects had the greatest influence on the erosion behavior. Additionally, an investigation into the sudden abnormal electrical behavior of the probe yielded the conclusion that the added capacitance of a deposited film reduces the number of data points in the ion saturation region used to fit the experimental data. This results in excessive values for extracted plasma parameters, most notably the electron temperature. However, this is only a temporary condition if the film can be removed.

Interactions of Deuterium Plasma with Lithiated and Boronized Surfaces in NSTX-U

NASA Astrophysics Data System (ADS)

Krstic, Predrag

2015-09-01

The main research goal of the presented research has been to understand the changes in surface composition and chemistry at the nanoscopic temporal and spatial scales for long pulse Plasma Facing Components (PFCs) and link these to the overall machine performance of the National Spherical Torus Experiment Upgrade (NSTX-U). A study is presented of the lithium surface science, with atomic spatial and temporal resolutions. The dynamic surface responds and evolves in a mixed material environments (D, Li, C, B, O, Mo, W) with impingement of plasma particles in the energy range below 100 eV. The results, obtained by quantum-classical molecular dynamics, include microstructure changes, erosion, surface chemistry, deuterium implantation and permeation. Main objectives of the research are i) a comparison of Li and B deposition on carbon, ii) the role of oxygen and other impurities e.g. boron, carbon in the lithium performance, and iii) how this performance will change when lithium is applied to a high-Z refractory metal substrate (Mo, W). In addition to predicting and understanding the phenomenology of the processes, we will show plasma induced erosion of PFCs, including chemical and physical sputtering yields at various temperatures (300-700 K) as well as deuterium uptake/recycling. This work is supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Science, Award Number DE-SC0013752.

A Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) Quantitative Analysis Method Based on the Auto-Selection of an Internal Reference Line and Optimized Estimation of Plasma Temperature.

PubMed

Yang, Jianhong; Li, Xiaomeng; Xu, Jinwu; Ma, Xianghong

2018-01-01

The quantitative analysis accuracy of calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is severely affected by the self-absorption effect and estimation of plasma temperature. Herein, a CF-LIBS quantitative analysis method based on the auto-selection of internal reference line and the optimized estimation of plasma temperature is proposed. The internal reference line of each species is automatically selected from analytical lines by a programmable procedure through easily accessible parameters. Furthermore, the self-absorption effect of the internal reference line is considered during the correction procedure. To improve the analysis accuracy of CF-LIBS, the particle swarm optimization (PSO) algorithm is introduced to estimate the plasma temperature based on the calculation results from the Boltzmann plot. Thereafter, the species concentrations of a sample can be calculated according to the classical CF-LIBS method. A total of 15 certified alloy steel standard samples of known compositions and elemental weight percentages were used in the experiment. Using the proposed method, the average relative errors of Cr, Ni, and Fe calculated concentrations were 4.40%, 6.81%, and 2.29%, respectively. The quantitative results demonstrated an improvement compared with the classical CF-LIBS method and the promising potential of in situ and real-time application.

Effects of alkyl polyglycoside, a nonionic surfactant, and forage-to-concentrate ratio on rumen fermentation, amino acid composition of rumen content, bacteria and plasma in goats.

PubMed

Zeng, Bo; Tan, Zhiliang; Tang, Shaoxun; Han, Xuefeng; Tan, Chuanyan; Zhong, Rongzhen; Hea, Zhixiong; Arigbede, Oluwasanmi Moses

2011-06-01

In the present study, the effects of different forage-to-concentrate ratios (F:C) and an alkyl polyglycoside (APG) supplementation on parameters of rumen and blood metabolism were investigated in goats. A 2 x 2 factorial experiment was arranged within a 4 x 4 Latin square design (four 22-day periods), using four wether goats equipped with permanent ruminal cannulas. The experimental diets included two F:C levels (40:60 vs. 60:40), and two APG supplementation levels (None or 13 ml APG daily per animal). Rumen contents and blood samples were collected at the end of each period. Dietary F:C alteration affected plasma urea and influenced the proportions of leucine, histidine, arginine, glycine, proline, alanine, valine, phenylalanine, cysteine and tyrosine in rumen content, and the proportions of methionine, threonine and proline in solid-associated bacteria (SAB) significantly. Dietary APG decreased the proportions of valine and phenylalanine in rumen content, and the histidine content of liquid-associated bacteria. The interaction between dietary F:C and APG was significant for the proportions of glycine and alanine in rumen content, and the proportions of lysine and threonine in SAB. The proportion of lysine was greater, but the proportion of threonine was less in SAB for goats fed high F:C diet without APG supplementation. The proportions of plasma free amino acids and glucose concentration were not affected by experimental treatments. These results indicated that dietary APG addition affected the amino acid composition of the rumen content and ruminal bacteria, but this depended on the dietary F:C ratio. It is necessary to validate the effectiveness of dietary APG supplementation in further studies with more animals.

Effects of liquid chromatography mobile phases and buffer salts on phosphorus inductively coupled plasma atomic emission and mass spectrometries utilizing ultrasonic nebulization and membrane desolvation.

PubMed

Carr, John E; Kwok, Kaho; Webster, Gregory K; Carnahan, Jon W

2006-01-23

Atomic spectrometry, specifically inductively coupled plasma atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) show promise for heteroatom-based detection of pharmaceutical compounds. The combination of ultrasonic nebulization (USN) with membrane desolvation (MD) greatly enhances detection limits with these approaches. Because pharmaceutical analyses often incorporate liquid chromatography, the study herein was performed to examine the effects of solvent composition on the analytical behaviors of these approaches. The target analyte was phosphorus, introduced as phosphomycin. AES response was examined at the 253.7 nm atom line and mass 31 ions were monitored for the MS experiments. With pure aqueous solutions, detection limits of 5 ppb (0.5 ng in 0.1 mL injection volumes) were obtained with ICP-MS. The ICP-AES detection limit was 150 ppb. Solvent compositions were varied from 0 to 80% organic (acetonitrile and methanol) with nine buffers at concentrations typically used in liquid chromatography. In general, solvents and buffers had statistically significant, albeit small, effects on ICP-AES sensitivities. A few exceptions occurred in cases where typical liquid chromatography buffer concentrations produced higher mass loadings on the plasma. Indications are that isocratic separations can be reliably performed. Within reasonable accuracy tolerances, it appears that gradient chromatography can be performed without the need for signal response normalization. Organic solvent and buffer effects were more significant with ICP-MS. Sensitivities varied significantly with different buffers and organic solvent content. In these cases, gradient chromatography will require careful analytical calibration as solvent and buffer content is varied. However, for most buffer and solvent combinations, signal and detection limits are only moderately affected. Isocratic separations and detection are feasible.

Flying-fox (Pteropus spp.) sperm membrane fatty acid composition, its relationship to cold shock injury and implications for cryopreservation success.

PubMed

Melville, D F; Johnston, S D; Miller, R R

2012-12-01

The very large acrosome of Pteropus species spermatozoa is prone to damage during cooling procedures. Cryogenic succuss has been linked to membrane composition, therefore the lipid composition of five Pteropus species sperm acrosomal and plasma membranes were investigated to provide insight into reasons for cold shock susceptibility. Rapid chilling and re-warming of spermatozoa from three Pteropus species resulted in a decrease (P<0.05) in acrosomal integrity. Biochemical analysis of lipids revealed that stearic acid (18:0) was the predominant saturated fatty acid and oleic acid (18:1, n-9) the predominant unsaturated fatty acid in both acrosomal and plasma membranes. Linolenic acid (18:3, n-3) was only detected in plasma membranes of Pteropus hypomelanus and was detected in acrosomal membranes of all Pteropus spp. studied (except Pteropus giganteus). Although detected in both plasma and acrosomal membranes of Pteropus vampyrus, docosahexaenoic acid (22:6) was not detected at all in Pteropus poliocephalus, only in trace levels in the acrosomal and plasma membranes of P. giganteus and P. hypomelanus and not in acrosomal membranes of Pteropus rodricensis. No difference was seen in the levels of polyunsaturated fatty acids (PUFAs) within plasma membranes, however PUFAs were lower (P<0.05) in acrosomal membranes of P. giganteus compared with P. vampyrus. Pteropus spp. spermatozoa have a very low ratio of unsaturated/saturated membrane fatty acids (<0.5). Membranes containing more PUFAs are more fluid, so the use of cryogenic media which improves membrane fluidity should improve Pteropus spp. spermatozoal viability post-thaw. Copyright © 2012 Elsevier Inc. All rights reserved.

Post-discharge gas composition of a large-gap DBD in humid air by UV-Vis absorption spectroscopy

NASA Astrophysics Data System (ADS)

Moiseev, T.; Misra, N. N.; Patil, S.; Cullen, P. J.; Bourke, P.; Keener, K. M.; Mosnier, J. P.

2014-12-01

Large gap dielectric barrier discharges (DBD) provide non-thermal, non-equilibrium plasmas that can generate specific gas chemistry with enhanced bactericidal effects when working in humid air. The present study investigates the post-discharge gas composition of such plasmas operated in humid air using UV-Vis (200-800 nm) absorption spectroscopy. Absorbance spectra have been de-convoluted using direct deconvolution and iterative methods and results are correlated to the DBD electrical parameters. The high-voltage (56 and 70 kV rms) DBD plasma generated at 50 Hz frequency in a closed container over a 20 mm gap in air with relative humidity (RH) of 5-70% has been characterized by I-V and capacitive methods. The post-discharge gas composition at each RH is assessed by UV-Vis absorption spectroscopy for plasma exposure times of 15-120 s. The concentration of ozone and nitrogen oxides (O3, NO2, NO3, N2O4) increases with plasma exposure time but a strong decrease in [O3] levels is obtained with increase in RH. The decrease in [O3] and an abundance of nitrogen oxides is ascribed to high specific power densities in the closed container and to increasing RH levels. The absorbance residual following deconvolution shows a strong band at 230-270 nm consistent with the presence of pernitric acid (HNO4) and other HNOx (x = 1, 3) species. Humid air large gap DBD plasmas in closed containers generate along with O3, high levels of nitrogen oxides and HNOx (x = 1, 4) acids leading to increased bactericidal rates.

Effect of intravenous omega-3 fatty acid infusion and hemodialysis on fatty acid composition of free fatty acids and phospholipids in patients with end-stage renal disease.

PubMed

Madsen, Trine; Christensen, Jeppe Hagstrup; Toft, Egon; Aardestrup, Inge; Lundbye-Christensen, Søren; Schmidt, Erik B

2011-01-01

Patients treated with hemodialysis (HD) have been reported to have decreased levels of ω-3 polyunsaturated fatty acids (PUFAs) in plasma and cells. The aim of this study was to investigate the effect of ω-3 PUFAs administered intravenously during HD, as well as the effect of HD treatment, on the fatty acid composition of plasma free fatty acids (FFAs), plasma phospholipids, and platelet phospholipids. Forty-four HD patients were randomized to groups receiving either a single dose of a lipid emulsion containing 4.1 g of ω-3 PUFAs or placebo (saline) administered intravenously during HD. Blood was drawn immediately before (baseline) and after (4 hours) HD and before the next HD session (48 hours). Fatty acid composition was measured using gas chromatography. The increase in ω-3 FFAs was greater in the ω-3 PUFA group compared with the placebo group, whereas the increase in total FFAs was similar between the 2 groups. In the ω-3 PUFA group, ω-3 PUFAs in plasma phospholipids were higher after 48 hours than at baseline, and in platelet phospholipids, ω-3 PUFAs increased after 4 hours. In the placebo group, no changes were observed in ω-3 PUFAs in plasma and platelet phospholipids. Intravenous ω-3 PUFAs administered during HD caused a transient selective increase in ω-3 FFA concentration. Furthermore, ω-3 PUFAs were rapidly incorporated into platelets, and the content of ω-3 PUFAs in plasma phospholipids increased after 48 hours.

Magnetothermodynamics: measurements of the thermodynamic properties in a relaxed magnetohydrodynamic plasma

NASA Astrophysics Data System (ADS)

Kaur, M.; Barbano, L. J.; Suen-Lewis, E. M.; Shrock, J. E.; Light, A. D.; Schaffner, D. A.; Brown, M. B.; Woodruff, S.; Meyer, T.

2018-02-01

We have explored the thermodynamics of compressed magnetized plasmas in laboratory experiments and we call these studies `magnetothermodynamics'. The experiments are carried out in the Swarthmore Spheromak eXperiment device. In this device, a magnetized plasma source is located at one end and at the other end, a closed conducting can is installed. We generate parcels of magnetized plasma and observe their compression against the end wall of the conducting cylinder. The plasma parameters such as plasma density, temperature and magnetic field are measured during compression using HeNe laser interferometry, ion Doppler spectroscopy and a linear probe array, respectively. To identify the instances of ion heating during compression, a PV diagram is constructed using measured density, temperature and a proxy for the volume of the magnetized plasma. Different equations of state are analysed to evaluate the adiabatic nature of the compressed plasma. A three-dimensional resistive magnetohydrodynamic code (NIMROD) is employed to simulate the twisted Taylor states and shows stagnation against the end wall of the closed conducting can. The simulation results are consistent to what we observe in our experiments.

Surface Catalysis and Oxidation on Stagnation Point Heat Flux Measurements in High Enthalpy Arc Jets

NASA Technical Reports Server (NTRS)

Nawaz, Anuscheh; Driver, David M.; Terrazas-Salinas

2013-01-01

Heat flux sensors are routinely used in arc jet facilities to determine heat transfer rates from plasma plume. The goal of this study is to assess the impact of surface composition changes on these heat flux sensors. Surface compositions can change due to oxidation and material deposition from the arc jet. Systematic surface analyses of the sensors were conducted before and after exposure to plasma. Currently copper is commonly used as surface material. Other surface materials were studied including nickel, constantan gold, platinum and silicon dioxide. The surfaces were exposed to plasma between 0.3 seconds and 3 seconds. Surface changes due to oxidation as well as copper deposition from the arc jets were observed. Results from changes in measured heat flux as a function of surface catalycity is given, along with a first assessment of enthalpy for these measurements. The use of cupric oxide is recommended for future heat flux measurements, due to its consistent surface composition arc jets.

On the interplay of gas dynamics and the electromagnetic field in an atmospheric Ar/H2 microwave plasma torch

NASA Astrophysics Data System (ADS)

Synek, Petr; Obrusník, Adam; Hübner, Simon; Nijdam, Sander; Zajíčková, Lenka

2015-04-01

A complementary simulation and experimental study of an atmospheric pressure microwave torch operating in pure argon or argon/hydrogen mixtures is presented. The modelling part describes a numerical model coupling the gas dynamics and mixing to the electromagnetic field simulations. Since the numerical model is not fully self-consistent and requires the electron density as an input, quite extensive spatially resolved Stark broadening measurements were performed for various gas compositions and input powers. In addition, the experimental part includes Rayleigh scattering measurements, which are used for the validation of the model. The paper comments on the changes in the gas temperature and hydrogen dissociation with the gas composition and input power, showing in particular that the dependence on the gas composition is relatively strong and non-monotonic. In addition, the work provides interesting insight into the plasma sustainment mechanism by showing that the power absorption profile in the plasma has two distinct maxima: one at the nozzle tip and one further upstream.

Synthesis and characterization of in situ TiC-TiB2 composite coatings by reactive plasma spraying on a magnesium alloy

NASA Astrophysics Data System (ADS)

Zou, Binglin; Tao, Shunyan; Huang, Wenzhi; Khan, Zuhair S.; Fan, Xizhi; Gu, Lijian; Wang, Ying; Xu, Jiaying; Cai, Xiaolong; Ma, Hongmei; Cao, Xueqiang

2013-01-01

TiC-TiB2 composite coatings were successfully synthesized using the technique of reactive plasma spraying (RPS) on a magnesium alloy. Phase composition, microstructure and wear resistance of the coatings were characterized by using X-ray diffraction, scanning electron microscopy and pin-on-disk wear test, respectively. The results showed that the resultant product in the RPS coatings was composed of TiC and TiB2. Depending on the ignition of self-propagating high-temperature synthesis reaction in the agglomerate particles, the RPS coatings displayed porous and dense microstructures. The porosity of the RPS coatings, to some extent, decreased when the feed powders were plasma sprayed with Ni powders. The RPS coatings provided good wear resistance for the substrate under various loads. For high loads (e.g., ≥15 N), the wear resistance could be significantly improved by the proper addition of Ni into the RPS coatings.

Ion Composition in Titan's Exosphere from the Cassini Plasma Spectrometer

NASA Astrophysics Data System (ADS)

Woodson, A.; Smith, H. T.; Johnson, R. E.

2013-12-01

A primary goal of the Cassini mission has been to characterize the complex interaction between Saturn's magnetosphere and Titan's ionosphere. To this end, the Cassini spacecraft carries two instruments-the Ion and Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS)-capable of energy- and mass-analysis. The Ion Mass Spectrometer (IMS), one of three instruments composing CAPS, is designed to characterize diffuse plasmas throughout the magnetosphere while the INMS is optimized for measurements within Titan's upper atmosphere. As such, mass-resolved ion compositions confirming a variety of hydrocarbons and nitriles have been extracted from INMS data for numerous Titan encounters. Similar analysis of IMS data, however, has largely been resolution-limited to the identification of 'light' and 'heavy' ion groups in the wake. Herein we present a technique for extracting Dalton-resolved ion compositions from IMS spectra acquired below ~5 Titan radii. The method is then applied to data from the T40 encounter and the resulting relative abundances compared with those derived from the INMS data for the same encounter.

Composition of Plasma Formed from Hypervelocity Dust Impacts

NASA Astrophysics Data System (ADS)

Lee, N.; Close, S.; Rymer, A. M.; Mocker, A.

2012-12-01

Dust impacts can occur on all solar system bodies but are especially prevalent in the case of the Saturnian moons that are near or within the dust torus produced by Enceladus's plumes. Depending on the mass and charge on these plume particles, they will be influenced by both gravitational and electrodynamic forces, resulting in a range of possible impact speeds on the moons. The plasma formed upon impact can have very different characteristics depending on impact speed and on the electric field due to surface charging at the impact point. Through recent tests conducted at the Max Planck Institute for Nuclear Physics using a Van de Graaff dust accelerator, iron dust particles were electrostatically accelerated to speeds of 3-65 km/s and impacted on a variety of target materials including metallic and glassy surfaces. The target surfaces were connected to a biasing supply to represent surface charging effects. Because of the high specific kinetic energy of the dust particles, upon impact they vaporize along with part of the target surface and a fraction of this material is ionized forming a dense plasma. The impacts produced both positive and negative ions. We made measurements of the net current imparted by this expanding plasma at a distance of several centimeters from the impact point. By setting the bias of the target, we impose an electric field on the charge population, allowing a measurement of plasma composition through time of flight analysis. The figure shows representative measurements of the net current measured by a retarding potential analyzer (RPA) from separate 18 and 19 km/s impacts of 7 fg particles on a glassy surface that was negatively and positively biased, respectively. This target was an optical solar reflector donated by J. Likar of Lockheed Martin for these experiments. These results show that ions of both positive and negative charge can be formed through the mechanism of dust impacts, and has implications on the surface plasma environment at Enceladus and other airless bodies in the solar system. Measurements of net current from impact plasmas. The horizontal axis is normalized to particle mass based on time of flight. The red trace is from an impact on a positively biased surface, ejecting positive ions toward the sensor. The blue trace is from an impact on a negatively biased surface, ejecting electrons and negative ions toward the sensor. The first positive peak is from electrons causing secondary emission off the sensor. The subsequent negative peaks are from negative ions.

Titanium nitride plasma-chemical synthesis with titanium tetrachloride raw material in the DC plasma-arc reactor

NASA Astrophysics Data System (ADS)

Kirpichev, D. E.; Sinaiskiy, M. A.; Samokhin, A. V.; Alexeev, N. V.

2017-04-01

The possibility of plasmochemical synthesis of titanium nitride is demonstrated in the paper. Results of the thermodynamic analysis of TiCl4 - H2 - N2 system are presented; key parameters of TiN synthesis process are calculated. The influence of parameters of plasma-chemical titanium nitride synthesis process in the reactor with an arc plasmatron on characteristics on the produced powders is experimentally investigated. Structure, chemical composition and morphology dependencies on plasma jet enthalpy, stoichiometric excess of hydrogen and nitrogen in a plasma jet are determined.

Properties of Plasma Membrane from Pea Root Seedlings under Altered Gravity

NASA Astrophysics Data System (ADS)

Klymchuk, D.; Baranenko, V.; Vorobyova, T. V.; Kurylenko, I.; Chyzhykova, O.; Dubovoy, V.

In this study, the properties of pea (Pisum sativum L.) plasma membrane were examined to determine how the membrane structure and functions are regulated in response to clinorotation (2 rev/min) conditions. Membrane preparations enriched by plasma membrane vesicles were obtained by aqueous two-phase partitioning from 6-day seedling roots. The specific characteristics of H^+-ATPase, lípid composition and peroxidation intensity as well as fluidity of lipid bilayer were analysed. ATP hydrolytic activity was inhibited by ortovanadate and was insensitive to aside and nitrate in sealed plasma membrane vesicles isolated from both clinorotated and control seedlings. Plasma membrane vesicles from clinorotated seedlings in comparison to controls were characterised by increase in the total lipid/protein ratio, ATP hydrolytic activity and intensifying of lipid peroxidation. Sitosterol and campesterol were the predominant free sterol species. Clinorotated seedlings contained a slightly higher level of unsaturated fatty acid than controls. Plasma membrane vesicles were labelled with pyrene and fluorescence originating from monomeric (I_M) molecules and excimeric (I_E) aggregates were measured. The calculated I_E/I_M values were higher in clinorotated seedlings compared with controls reflecting the reduction in membrane microviscosity. The involvement of the changes in plasma membrane lipid content and composition, fluidity and H^+-ATPase activity in response of pea seedlings to altered gravity is discussed.

Process for HIP canning of composites

NASA Technical Reports Server (NTRS)

Juhas, John J. (Inventor)

1990-01-01

A single step is relied on in the canning process for hot isostatic pressing (HIP) metallurgy composites. The composites are made from arc sprayed and plasma sprayed monotape. The HIP can is of compatible refractory metal and is sealed at high vacuum and temperature. This eliminates outgassing during hot isostatic pressing.

Spark plasma sintering of pure and doped tungsten as plasma facing material

NASA Astrophysics Data System (ADS)

Autissier, E.; Richou, M.; Minier, L.; Naimi, F.; Pintsuk, G.; Bernard, F.

2014-04-01

In the current water cooled divertor concept, tungsten is an armour material and CuCrZr is a structural material. In this work, a fabrication route via a powder metallurgy process such as spark plasma sintering is proposed to fully control the microstructure of W and W composites. The effect of chemical composition (additives) and the powder grain size was investigated. To reduce the sintering temperature, W powders doped with a nano-oxide dispersion of Y2O3 are used. Consequently, the sintering temperature for W-oxide dispersed strengthened (1800 °C) is lower than for pure W powder. Edge localized mode tests were performed on pure W and compared to other preparation techniques and showed promising results.