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Sample records for remote plasma enhanced

  1. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber

    SciTech Connect

    Dechana, A.; Thamboon, P.; Boonyawan, D.

    2014-10-15

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al{sub 2}O{sub 3} layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al{sub 2}O{sub 3} films—analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques—will be discussed.

  2. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber.

    PubMed

    Dechana, A; Thamboon, P; Boonyawan, D

    2014-10-01

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al2O3 layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al2O3 films-analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques-will be discussed.

  3. Characterization of Thermal and Photo-Enhanced Remote Plasma Etching of Gallium Arsenide and Indium Phosphide

    NASA Astrophysics Data System (ADS)

    Lishan, David George

    The desire to shrink dimensions and improve performance of devices has focused attention on fabrication processes that induce a minimum of material damage. A technique which accomplishes this goal involves the utilization of remote plasma etching. In this work, the design of a flexible, high vacuum, remote plasma dry etch processing chamber with multiple in situ analytical capabilities is described. With this new chamber, a systematic study of temperature and flux dependence using hydrogen chloride (HCl) and chlorine (Cl_2) to etch GaAs and InP is performed. Reactant flux limited etching was observed using HCl. These results agree qualitatively with thermodynamic predictions and provide a more complete understanding of reactant flux and product desorption dynamics. Along with the insight into the mechanisms associated with halogen etching of III-V materials, the control, low damage, and material selectivity aspects of remote plasma etching are discussed using as examples, photochemical enhanced etching, fabrication of quantum wires, and in situ real time current monitoring.

  4. Ag films grown by remote plasma enhanced atomic layer deposition on different substrates

    SciTech Connect

    Amusan, Akinwumi A. Kalkofen, Bodo; Burte, Edmund P.; Gargouri, Hassan; Wandel, Klaus; Pinnow, Cay; Lisker, Marco

    2016-01-15

    Silver (Ag) layers were deposited by remote plasma enhanced atomic layer deposition (PALD) using Ag(fod)(PEt{sub 3}) (fod = 2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) as precursor and hydrogen plasma on silicon substrate covered with thin films of SiO{sub 2}, TiN, Ti/TiN, Co, Ni, and W at different deposition temperatures from 70  to 200 °C. The deposited silver films were analyzed by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive x-ray spectroscopy, four point probe measurement, ellipsometric measurement, x-ray fluorescence (XRF), and x-ray diffraction (XRD). XPS revealed pure Ag with carbon and oxygen contamination close to the detection limit after 30 s argon sputtering for depositions made at 120 and 200 °C substrate temperatures. However, an oxygen contamination was detected in the Ag film deposited at 70 °C after 12 s argon sputtering. A resistivity of 5.7 × 10{sup −6} Ω cm was obtained for approximately 97 nm Ag film on SiO{sub 2}/Si substrate. The thickness was determined from the SEM cross section on the SiO{sub 2}/Si substrate and also compared with XRF measurements. Polycrystalline cubic Ag reflections were identified from XRD for PALD Ag films deposited at 120 and 200 °C. Compared to W surface, where poor adhesion of the films was found, Co, Ni, TiN, Ti/TiN and SiO{sub 2} surfaces had better adhesion for silver films as revealed by SEM, TEM, and AFM images.

  5. Automation of a remote plasma-enhanced chemical vapor deposition system using LabVIEW

    NASA Astrophysics Data System (ADS)

    Sharma, Rajan; Fretwell, John L.; Vaihinger, Jochen; Banerjee, Sanjay K.

    1997-08-01

    The remote plasma-enhanced chemical vapor deposition (RPCVD) system is an experimental low temperature Si/Si-Ge epitaxy system. This paper describes an integrated hardware/software automation package developed for the RPCVD system. Aspects of the system controlled by the package include pneumatic gas valves, mass flow controllers (MFCs), and a temperature controller. The package was developed on an Apple Quadra 950 platform using LabVIEWTM 3.1 and associated data acquisition and control hardware supplied by National Instruments and other vendors. The software interface allows the user to operate the system through a virtual control panel which displays critical system parameters such as chamber pressure, chamber temperature and gas flow rates, along with the states of the gas valves and the MFCs. The system can also be run in the recipe mode, in which a sequence of steps are read in from an ExcelTM file. A simulation routine scans each recipe for possible errors such as violation of valve interlocks while the recipe is being loaded. All actions, whether in the manual mode or the recipe mode, are recorded in a log file. Finally, since many of the gases used in the RPCVD process are toxic and/or flammable, there is an emphasis on safety in the entire control scheme. A safety monitor routine constantly checks for valve interlocks and pressure-valve interlocks. Upon detecting an illegal state, it automatically takes necessary action to bring the system into a safe state. In addition to these software safety features, there are also hardware interlocks to deal with such situations as power outages.

  6. Enhanced dielectric deposition on single-layer MoS2 with low damage using remote N2 plasma treatment.

    PubMed

    Qian, Qingkai; Zhang, Zhaofu; Hua, Mengyuan; Tang, Gaofei; Lei, Jiacheng; Lan, Feifei; Xu, Yongkuan; Yan, Ruyue; Chen, Kevin J

    2017-04-28

    Using remote N2 plasma treatment to promote dielectric deposition on the dangling-bond free MoS2 is explored for the first time. The N2 plasma induced damages are systematically studied by the defect-sensitive acoustic-phonon Raman of single-layer MoS2, with samples undergoing O2 plasma treatment as a comparison. O2 plasma treatment causes defects in MoS2 mainly by oxidizing MoS2 along the already defective sites (most likely the flake edges), which results in the layer oxidation of MoS2. In contrast, N2 plasma causes defects in MoS2 mainly by straining and mechanically distorting the MoS2 layers first. Owing to the relatively strong MoS2-substrate interaction and chemical inertness of MoS2 in N2 plasma, single-layer MoS2 shows great stability in N2 plasma and only stable point defects are introduced after long-duration N2 plasma exposure. Considering the enormous vulnerability of single-layer MoS2 in O2 plasma and the excellent stability of single-layer MoS2 in N2 plasma, the remote N2 plasma treatment shows great advantage as surface functionalization to promote dielectric deposition on single-layer MoS2.

  7. Remote plasma processing of thin film materials

    NASA Astrophysics Data System (ADS)

    Kastenmeier, Bernd E. E.

    1999-09-01

    In this thesis, phenomena and mechanisms of remote plasma processes are investigated. The plasmas are spatially separated from the sample surface. Chemically reactive species are produced in the discharge region from rather inert feed gases. They exit the discharge region and travel in the afterglow towards the reaction chamber, where primarily neutral species arrive. The interaction with the sample surface is purely chemical. The absence of direct plasma surface interactions distinguishes remote plasma Chemical Dry Etching (CDE) from other etch processes like Reactive Ion Etching (RIE) or Inductively Coupled Plasma (ICP) etching. The etch reactions in CDE are isotropic, potentially offer great etch rate ratios and minimize substrate damage due to the absence of direct plasma-surface interactions. However, some materials like silicon dioxide (SiO2) or fluorocarbon deposits are difficult to remove because of the lack of activation energy otherwise provided by ion bombardment. In CDE, rates can be enhanced by the introduction of a new reaction pathway. Remote plasma CDE of silicon nitride (Si3N4) is an example for increasing the overall reaction rate by introducing a new reaction channel. Typically, the Si3N4 surface is exposed to the fluorine rich afterglow of a fluorocarbon, nitrogen trifluoride (NF 3) or sulfur hexafluoride (SF6) based discharge. We find that the Si3N4 etch rate is dramatically enhanced when Nitric Oxide (NO) is present in the afterglow as compared to the case in which only fluorine is present. Presented here are detailed analyses of the etching of Si3N 4 and SiO2 in different chemistries. Several experimental techniques are employed to investigate the composition of the plasma and the afterglow, the surface modifications and the etch rates for tetrafluoromethane (CF4) and NF3 based processes. These measurements establish the effect of NO on the Si3N4 etch rate. The dominant mechanism for the etch rate enhancement is shown by mass spectrometry

  8. Low-temperature remote plasma enhanced atomic layer deposition of ZrO2/zircone nanolaminate film for efficient encapsulation of flexible organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Chen, Zheng; Wang, Haoran; Wang, Xiao; Chen, Ping; Liu, Yunfei; Zhao, Hongyu; Zhao, Yi; Duan, Yu

    2017-01-01

    Encapsulation is essential to protect the air-sensitive components of organic light-emitting diodes (OLEDs) such as active layers and cathode electrodes. In this study, hybrid zirconium inorganic/organic nanolaminates were fabricated using remote plasma enhanced atomic layer deposition (PEALD) and molecular layer deposition at a low temperature. The nanolaminate serves as a thin-film encapsulation layer for OLEDs. The reaction mechanism of PEALD process was investigated using an in-situ quartz crystal microbalance (QCM) and in-situ quadrupole mass spectrometer (QMS). The bonds present in the films were determined by Fourier transform infrared spectroscopy. The primary reaction byproducts in PEALD, such as CO, CO2, NO, H2O, as well as the related fragments during the O2 plasma process were characterized using the QMS, indicating a combustion-like reaction process. The self-limiting nature and growth mechanisms of the ZrO2 during the complex surface chemical reaction of the ligand and O2 plasma were monitored using the QCM. The remote PEALD ZrO2/zircone nanolaminate structure prolonged the transmission path of water vapor and smooth surface morphology. Consequently, the water barrier properties were significantly improved (reaching 3.078 × 10‑5 g/m2/day). This study also shows that flexible OLEDs can be successfully encapsulated to achieve a significantly longer lifetime.

  9. Low-temperature remote plasma enhanced atomic layer deposition of ZrO2/zircone nanolaminate film for efficient encapsulation of flexible organic light-emitting diodes

    PubMed Central

    Chen, Zheng; Wang, Haoran; Wang, Xiao; Chen, Ping; Liu, Yunfei; Zhao, Hongyu; Zhao, Yi; Duan, Yu

    2017-01-01

    Encapsulation is essential to protect the air-sensitive components of organic light-emitting diodes (OLEDs) such as active layers and cathode electrodes. In this study, hybrid zirconium inorganic/organic nanolaminates were fabricated using remote plasma enhanced atomic layer deposition (PEALD) and molecular layer deposition at a low temperature. The nanolaminate serves as a thin-film encapsulation layer for OLEDs. The reaction mechanism of PEALD process was investigated using an in-situ quartz crystal microbalance (QCM) and in-situ quadrupole mass spectrometer (QMS). The bonds present in the films were determined by Fourier transform infrared spectroscopy. The primary reaction byproducts in PEALD, such as CO, CO2, NO, H2O, as well as the related fragments during the O2 plasma process were characterized using the QMS, indicating a combustion-like reaction process. The self-limiting nature and growth mechanisms of the ZrO2 during the complex surface chemical reaction of the ligand and O2 plasma were monitored using the QCM. The remote PEALD ZrO2/zircone nanolaminate structure prolonged the transmission path of water vapor and smooth surface morphology. Consequently, the water barrier properties were significantly improved (reaching 3.078 × 10−5 g/m2/day). This study also shows that flexible OLEDs can be successfully encapsulated to achieve a significantly longer lifetime. PMID:28059160

  10. Fundamental studies of defect generation in amorphous silicon alloys grown by remote plasma-enhanced chemical-vapor deposition (Remote PECVD)

    SciTech Connect

    Lucovsky, G.; Nemanich, R.J.; Bernholc, J.; Whitten, J.; Wang, C.; Davidson, B.; Williams, M.; Lee, D.; Bjorkman, C.; Jing, Z. )

    1993-01-01

    We demonstrated that the remote PECVD process can be used to deposit heavily doped n-type and p-type a-Si:H thin films. We optimized conditions for depositing undoped, near-intrinsic and heavily doped thin films of [mu]c(microcrystalline)-Si by remote PECVD. We extended the remote PECVD process to the deposition of undoped and doped a-Si,C:H and [mu]c-Si,C alloy films. We analyzed transport data for the dark conductivity in undoped and doped a-Si:H, a-Si,C:H, [mu]c-Si and [mu]c-Si,C films. We studied the properties of doped a-Si:H and [mu]c-Si in MOS capacitors using [approximately]10 [Omega]-cm p-type crystalline substrates and thermally grown Si0[sub 2] dielectric layers. We collaborated with a group at RWTH in Aachen, Germany, and studied the contributions of process induced defect states to the recombination of photogenerated electron pairs. We applied a tight-binding model to Si-Bethe lattice structures to investigate the effects of bond angle, and dihedral angle disorder. We used ab initio and empirical calculations to study non-random bonding arrangements in a-Si,O:H and doped a-Si:H films.

  11. In situ spectroscopic ellipsometry growth studies on the Al-doped ZnO films deposited by remote plasma-enhanced metalorganic chemical vapor deposition

    SciTech Connect

    Volintiru, I.; Creatore, M.; Sanden, M. C. M. van de

    2008-02-01

    In situ spectroscopic ellipsometry (SE) was applied to study the pyramidlike and pillarlike growth of Al doped ZnO (AZO) films deposited by means of remote plasma-enhanced metalorganic chemical vapor deposition for transparent conductive oxide applications. Real time SE studies in the visible region allowed discerning between the two growth modes by addressing the time evolution of the bulk and surface roughness layer thickness. While the pillarlike mode is characterized by a constant growth rate, a slower rate in the initial stage (up to 150-200 nm film thickness), compared to the bulk, is observed for the growth of pyramidlike AZO films. The two modes differ also in terms of surface roughness development: a saturation behavior is observed for film thickness above 150-200 nm in the case of the pyramidlike films, while a slow linear increase with film thickness characterizes the pillarlike mode. By extending the SE analysis of the AZO films to the near infrared region, valuable information about the in grain properties could be extracted: excellent in grain mobility values, i.e., larger than 100 and 50 cm{sup 2}/V s, are determined for the pyramidlike and pillarlike AZO layers, respectively. The comparison between the outcome of the in situ real time SE studies and the ex situ electrical and chemical characterization highlights the limitations in the electron transport occurring in both types of films and allows one to address routes toward further improvement in AZO conductivity.

  12. Evolution of the electrical and structural properties during the growth of Al doped ZnO films by remote plasma-enhanced metalorganic chemical vapor deposition

    SciTech Connect

    Volintiru, I.; Creatore, M.; Kniknie, B. J.; Spee, C. I. M. A.; Sanden, M. C. M. van de

    2007-08-15

    Al-doped zinc oxide (AZO) films were deposited by means of remote plasma-enhanced metalorganic chemical vapor deposition from oxygen/diethylzinc/trimethylaluminum mixtures. The electrical, structural (crystallinity and morphology), and chemical properties of the deposited films were investigated using Hall, four point probe, x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), electron recoil detection (ERD), Rutherford backscattering (RBS), and time of flight secondary ion mass spectrometry (TOF-SIMS), respectively. We found that the working pressure plays an important role in controlling the sheet resistance R{sub s} and roughness development during film growth. At 1.5 mbar the AZO films are highly conductive (R{sub s}<6 {omega}/{open_square} for a film thickness above 1200 nm) and very rough (>4% of the film thickness), however, they are characterized by a large sheet resistance gradient with increasing film thickness. By decreasing the pressure from 1.5 to 0.38 mbar, the gradient is significantly reduced and the films become smoother, but the sheet resistance increases (R{sub s}{approx_equal}100 {omega}/{open_square} for a film thickness of 1000 nm). The sheet resistance gradient and the surface roughness development correlate with the grain size evolution, as determined from the AFM and SEM analyses, indicating the transition from pyramid-like at 1.5 mbar to pillar-like growth mode at 0.38 mbar. The change in plasma chemistry/growth precursors caused by the variation in pressure leads to different concentration and activation efficiency of Al dopant in the zinc oxide films. On the basis of the experimental evidence, a valid route for further improving the conductivity of the AZO film is found, i.e., increasing the grain size at the initial stage of film growth.

  13. Holographic enhanced remote sensing system

    NASA Technical Reports Server (NTRS)

    Iavecchia, Helene P.; Gaynor, Edwin S.; Huff, Lloyd; Rhodes, William T.; Rothenheber, Edward H.

    1990-01-01

    The Holographic Enhanced Remote Sensing System (HERSS) consists of three primary subsystems: (1) an Image Acquisition System (IAS); (2) a Digital Image Processing System (DIPS); and (3) a Holographic Generation System (HGS) which multiply exposes a thermoplastic recording medium with sequential 2-D depth slices that are displayed on a Spatial Light Modulator (SLM). Full-parallax holograms were successfully generated by superimposing SLM images onto the thermoplastic and photopolymer. An improved HGS configuration utilizes the phase conjugate recording configuration, the 3-SLM-stacking technique, and the photopolymer. The holographic volume size is currently limited to the physical size of the SLM. A larger-format SLM is necessary to meet the desired 6 inch holographic volume. A photopolymer with an increased photospeed is required to ultimately meet a display update rate of less than 30 seconds. It is projected that the latter two technology developments will occur in the near future. While the IAS and DIPS subsystems were unable to meet NASA goals, an alternative technology is now available to perform the IAS/DIPS functions. Specifically, a laser range scanner can be utilized to build the HGS numerical database of the objects at the remote work site.

  14. Studies of Wettability of Medical PVC by Remote Nitrogen Plasma

    NASA Astrophysics Data System (ADS)

    Li, Ru; Chen, Jierong

    2006-05-01

    The effects of remote nitrogen plasma and nitrogen plasma on medical PVC's surface modification are studied. The surface properties are characterized by the contact angle measurement, X-ray photoelectron spectroscopy and scanning electron microscopy. Results show that the remote nitrogen plasma treatments modify the PVC surface in both morphology and composition and the treatment by the remote nitrogen plasma in PVC surface modification is more effective than that by the nitrogen plasma. Remote nitrogen plasma can modify the surface more uniformly. After the PVC surface is treated for 2 min by remote nitrogen plasma, the [w(O)+ w(N)]/w(C)] value increases from 0.13 to 0.51 and the water contact angle decreases from 89o to 18o.

  15. Flood Management Enhancement Using Remotely Sensed Data

    NASA Technical Reports Server (NTRS)

    Romanowski, Gregory J.

    1997-01-01

    SENTAR, Inc., entered into a cooperative agreement with NASA Goddard Space Flight Center (GSFC) in December 1994. The intent of the NASA Cooperative Agreement was to stimulate broad public use, via the Internet, of the very large remote sensing databases maintained by NASA and other agencies, thus stimulating U.S. economic growth, improving the quality of life, and contributing to the implementation of a National Information Infrastructure. SENTAR headed a team of collaborating organizations in meeting the goals of this project. SENTAR's teammates were the NASA Marshall Space Flight Center (MSFC) Global Hydrology and Climate Center (GHCC), the U.S. Army Space and Strategic Defense Command (USASSDC), and the Alabama Emergency Management Agency (EMA). For this cooperative agreement, SENTAR and its teammates accessed remotely sensed data in the Distributed Active Archive Centers, and other available sources, for use in enhancing the present capabilities for flood disaster management by the Alabama EMA. The project developed a prototype software system for addressing prediction, warning, and damage assessment for floods, though it currently focuses on assessment. The objectives of the prototype system were to demonstrate the added value of remote sensing data for emergency management operations during floods and the ability of the Internet to provide the primary communications medium for the system. To help achieve these objectives, SENTAR developed an integrated interface for the emergency operations staff to simplify acquiring and manipulating source data and data products for use in generating new data products. The prototype system establishes a systems infrastructure designed to expand to include future flood-related data and models or to include other disasters with their associated remote sensing data requirements and distributed data sources. This report covers the specific work performed during the seventh, and final, milestone period of the project, which

  16. Diagnostic enhancements for plasma processing

    SciTech Connect

    Selwyn, G.S.; Henins, I.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Funds obtained under this project were used to enhance the diagnostic capabilities of the plasma-processing program in the Physics Division at LANL and include successful development and implementation of in-situ Raman spectroscopy and infrared emission spectroscopy. These methods were used to detect the presence and nature of ground-state and electronically excited molecular oxygen formed in an atmospheric-pressure, nonthermal plasma source used for environmental, industrial and decontamination applications.

  17. Fundamental studies of defect generation in amorphous silicon alloys grown by remote plasma-enhanced chemical-vapor deposition. Final subcontract report, 1 July 1989--31 December 1992

    SciTech Connect

    Lucovsky, G.

    1993-08-01

    This report describes research to reduce the intrinsic bonding defects in amorphous and microcrystalline Si alloys by controlling the bonding chemistry and the microstructure via the deposition process reactions. The specific approach was to use remote plasma-enhanced, chemical-vapor deposition (PECVD) and reactive magnetron sputtering to limit the multiplicity of deposition inaction pathways, and thereby gain increased control over the thin-film chemistry and microstrucre. The research included (1) the deposition of amorphous and microcrystalline Si alloy materials by the PECVD process and by reactive magnetron sputtering, and (2) the evaluation of the material properties of these films for potential applications in PV devices. The focus of the research was on pining a fundamental understanding of the relationships between deposition reaction pathways, the bonding of dopant and alloy atoms, and the electrical provides of importance for PV applications. This involved studying the factors that contribute to defect generation and to defect removal and/or neutralization. In addition to the experimental studies, the research also included theoretical and modeling studies aimed at understanding the relationships between local atomic arrangements of Si and alloy atoms, and the electrical, optical, vibrational, and defect properties.

  18. Fundamental studies of defect generation in amorphous silicon alloys grown by remote plasma-enhanced chemical-vapor deposition (Remote PECVD). Annual subcontract report, 1 September 1990--31 August 1991

    SciTech Connect

    Lucovsky, G.; Nemanich, R.J.; Bernholc, J.; Whitten, J.; Wang, C.; Davidson, B.; Williams, M.; Lee, D.; Bjorkman, C.; Jing, Z.

    1993-01-01

    We demonstrated that the remote PECVD process can be used to deposit heavily doped n-type and p-type a-Si:H thin films. We optimized conditions for depositing undoped, near-intrinsic and heavily doped thin films of {mu}c(microcrystalline)-Si by remote PECVD. We extended the remote PECVD process to the deposition of undoped and doped a-Si,C:H and {mu}c-Si,C alloy films. We analyzed transport data for the dark conductivity in undoped and doped a-Si:H, a-Si,C:H, {mu}c-Si and {mu}c-Si,C films. We studied the properties of doped a-Si:H and {mu}c-Si in MOS capacitors using {approximately}10 {Omega}-cm p-type crystalline substrates and thermally grown Si0{sub 2} dielectric layers. We collaborated with a group at RWTH in Aachen, Germany, and studied the contributions of process induced defect states to the recombination of photogenerated electron pairs. We applied a tight-binding model to Si-Bethe lattice structures to investigate the effects of bond angle, and dihedral angle disorder. We used ab initio and empirical calculations to study non-random bonding arrangements in a-Si,O:H and doped a-Si:H films.

  19. Interactive computer-enhanced remote viewing system

    SciTech Connect

    Tourtellott, J.A.; Wagner, J.F.

    1995-10-01

    Remediation activities such as decontamination and decommissioning (D&D) typically involve materials and activities hazardous to humans. Robots are an attractive way to conduct such remediation, but for efficiency they need a good three-dimensional (3-D) computer model of the task space where they are to function. This model can be created from engineering plans and architectural drawings and from empirical data gathered by various sensors at the site. The model is used to plan robotic tasks and verify that selected paths are clear of obstacles. This report describes the development of an Interactive Computer-Enhanced Remote Viewing System (ICERVS), a software system to provide a reliable geometric description of a robotic task space, and enable robotic remediation to be conducted more effectively and more economically.

  20. Remote Sensing of Inner Heliospheric Plasmas

    DTIC Science & Technology

    1992-12-15

    Colloquium 133 held in Iguazu , Argentina 2-6 August, 1991, Z. Svestka, B.V. Jackson and M.E. Machado, eds. Springer-Verlag, Heidelberg, (1992) (pg. 322 - 328...Physics, 399, the proceedings of IAU Colloquium 133 held in Iguazu , Argentina 2-6 August, 1991, Z. Svestka, B.V. Jackson and M.E. Machado, eds...133 on Eruptive Solar Flares held in Iguazu , Argentina 2-6 Au- gust (1991). 9. Jackson, B.V. "Remote Sensing Observations of Mass Ejections and Shocks

  1. Remote Sensing of Inner Heliospheric Plasmas

    DTIC Science & Technology

    1991-11-14

    Solar Mass Ejection hnager in Low-Earth Orbit", in press in the IAU Colloquium 133 proceedings on Eruptive Solar Flares held in Iguazu , Argentina 2-6...Colloquium 133 proceedings on Eruptive Solar Flares held in Iguazu , Argentina 2-6 August (1991) (10 pages). + Work In Progress 1. Jackson, B.V. and H.R...34, presented at IAU Colloquium 133 on Eruptive Solar Flares held in Iguazu , Argentina 2-6 August (1991). 9. Jackson, B.V. "Remote Sensing Observations of

  2. Feedback enhanced plasma spray tool

    DOEpatents

    Gevelber, Michael Alan; Wroblewski, Donald Edward; Fincke, James Russell; Swank, William David; Haggard, Delon C.; Bewley, Randy Lee

    2005-11-22

    An improved automatic feedback control scheme enhances plasma spraying of powdered material through reduction of process variability and providing better ability to engineer coating structure. The present inventors discovered that controlling centroid position of the spatial distribution along with other output parameters, such as particle temperature, particle velocity, and molten mass flux rate, vastly increases control over the sprayed coating structure, including vertical and horizontal cracks, voids, and porosity. It also allows improved control over graded layers or compositionally varying layers of material, reduces variations, including variation in coating thickness, and allows increasing deposition rate. Various measurement and system control schemes are provided.

  3. Interactive computer-enhanced remote viewing system

    SciTech Connect

    Tourtellott, J.A.; Wagner, J.F.

    1995-12-01

    Remediation activities such as decontamination and decommissioning (D&D) typically involve materials and activities hazardous to humans. Robots are an attractive way to conduct such remediation, but for efficiency they need a good three-dimensional (3-D) computer model of the task space where they are to function. This model can be created from engineering plans and architectural drawings and from empirical data gathered by various sensors at the site. The model is used to plan robotic tasks and verify that selected paths am clear of obstacles. This need for a task space model is most pronounced in the remediation of obsolete production facilities and underground storage tanks. Production facilities at many sites contain compact process machinery and systems that were used to produce weapons grade material. For many such systems, a complex maze of pipes (with potentially dangerous contents) must be removed, and this represents a significant D&D challenge. In an analogous way, the underground storage tanks at sites such as Hanford represent a challenge because of their limited entry and the tumbled profusion of in-tank hardware. In response to this need, the Interactive Computer-Enhanced Remote Viewing System (ICERVS) is being designed as a software system to: (1) Provide a reliable geometric description of a robotic task space, and (2) Enable robotic remediation to be conducted more effectively and more economically than with available techniques. A system such as ICERVS is needed because of the problems discussed below.

  4. Remote network control plasma diagnostic system for Tokamak T-10

    NASA Astrophysics Data System (ADS)

    Troynov, V. I.; Zimin, A. M.; Krupin, V. A.; Notkin, G. E.; Nurgaliev, M. R.

    2016-09-01

    The parameters of molecular plasma in closed magnetic trap is studied in this paper. Using the system of molecular diagnostics, which was designed by the authors on the «Tokamak T-10» facility, the radiation of hydrogen isotopes at the plasma edge is investigated. The scheme of optical radiation registration within visible spectrum is described. For visualization, identification and processing of registered molecular spectra a new software is developed using MatLab environment. The software also includes electronic atlas of electronic-vibrational-rotational transitions for molecules of protium and deuterium. To register radiation from limiter cross-section a network control system is designed using the means of the Internet/Intranet. Remote control system diagram and methods are given. The examples of web-interfaces for working out equipment control scenarios and viewing of results are provided. After test run in Intranet, the remote diagnostic system will be accessible through Internet.

  5. Generation and remote delivery of plasma activated species

    NASA Astrophysics Data System (ADS)

    Maguire, Paul; Mahony, Charles; Kelsey, Colin; Rutherford, David; Mariotti, Davide; Macias-Montero, Manuel; Perez-Martin, Fatima; Diver, Declan

    2016-09-01

    Plasma interactions with microdroplets offer new opportunities to deliver active chemical agents and nanoparticles to remote substrates downstream with many potential applications from cancer theranostics and wound healing in biomedicine, gentle food decontamination and seed germination in plasma agriculture to catalyst production and photonic structures fabrication, among others. We demonstrate plasma-liquid based pristine nanomaterials synthesis in flight and subsequent delivery up to 120mm from the atmospheric pressure plasma source. Monosized and non-aggregating metal nanoparticles are formed in the rf plasma in less than 100us, representing an increase in precursor reduction rate that is many (>4) orders of magnitude faster than that observed with standard colloidal chemistry or via high energy radiolytic techniques. Also the collection and purification limitations of the latter are avoided. Plasma activated liquid including OH radicals and H2O2 are transported over 120mm and have demonstrated high efficacy bacterial decontamination. These results will be compared with charge species and radical transport from the rf plasma without microdroplets. Reaction models based on high solvated surface electron concentrations will be presented. Funding from EPSRC acknowledged (Grants EP/K006088/1 and EP/K006142/1).

  6. Permanent magnet electron cyclotron resonance plasma source with remote window

    SciTech Connect

    Berry, L.A.; Gorbatkin, S.M. )

    1995-03-01

    An electron cyclotron resonance (ECR) plasma has been used in conjunction with a solid metal sputter target for Cu deposition over 200 mm diameters. The goal is to develop a deposition system and process suitable for filling submicron, high-aspect ratio ULSI features. The system uses a permanent magnet for creation of the magnetic field necessary for ECR, and is significantly more compact than systems equipped with electromagnets. A custom launcher design allows remote microwave injection with the microwave entrance window shielded from the copper flux. When microwaves are introduced at an angle with respect to the plasma, high electron densities can be produced with a plasma frequency significantly greater than the electron cyclotron frequency. Copper deposition rates of 1000 A/min have been achieved.

  7. Parametric investigations of plasma characteristics in a remote inductively coupled plasma system

    NASA Astrophysics Data System (ADS)

    Shukla, Prasoon; Roy, Abhra; Jain, Kunal; Bhoj, Ananth

    2016-09-01

    Designing a remote plasma system involves source chamber sizing, selection of coils and/or electrodes to power the plasma, designing the downstream tubes, selection of materials used in the source and downstream regions, locations of inlets and outlets and finally optimizing the process parameter space of pressure, gas flow rates and power delivery. Simulations can aid in spatial and temporal plasma characterization in what are often inaccessible locations for experimental probes in the source chamber. In this paper, we report on simulations of a remote inductively coupled Argon plasma system using the modeling platform CFD-ACE +. The coupled multiphysics model description successfully address flow, chemistry, electromagnetics, heat transfer and plasma transport in the remote plasma system. The SimManager tool enables easy setup of parametric simulations to investigate the effect of varying the pressure, power, frequency, flow rates and downstream tube lengths. It can also enable the automatic solution of the varied parameters to optimize a user-defined objective function, which may be the integral ion and radical fluxes at the wafer. The fast run time coupled with the parametric and optimization capabilities can add significant insight and value in design and optimization.

  8. Comparison of Plasma Activation of Thin Water Layers by Direct and Remote Plasma Sources

    NASA Astrophysics Data System (ADS)

    Kushner, Mark

    2014-10-01

    Plasma activation of liquids is now being investigated for a variety of biomedical applications. The plasma sources used for this activation can be generally classified as direct (the plasma is in contact with the surface of the liquid) or remote (the plasma does not directly touch the liquid). The direct plasma source may be a dielectric barrier discharge (DBD) where the surface of the liquid is a floating electrode or a plasma jet in which the ionization wave forming the plasma plume reaches the liquid. The remote plasma source may be a DBD with electrodes electrically isolated from the liquid or a plasma jet in which the ionization wave in the plume does not reach the liquid. In this paper, a comparison of activation of thin water layers on top of tissue, as might be encountered in wound healing, will be discussed using results from numerical investigations. We used the modeling platform nonPDPSIM to simulate direct plasma activation of thin water layers using DBDs and remote activation using plasma jets using up to hundreds of pulses. The DBDs are sustained in humid air while the plasma jets consist of He/O2 mixtures flowed into humid air. For similar number of pulses and energy deposition, the direct DBD plasma sources produce more acidification and higher production of nitrates/nitrites in the liquid. This is due to the accumulation of NxOy plasma jets, the convective flow removes many of these species prior to their diffusing into the water or reacting to form higher nitrogen oxides. This latter effect is sensitive to the repetition rate which determines whether reactive species formed during prior pulses overlap with newly produced reactive species. in the gas phase. In the plasma jets, the convective flow removes many of these species prior to their diffusing into the water or reacting to form higher nitrogen oxides. This latter effect is sensitive to the repetition rate which determines whether reactive species formed during prior pulses overlap with

  9. Enhancement of remote sensing through microwave technology

    NASA Technical Reports Server (NTRS)

    Cehelsky, M.; Kiebler, J.

    1980-01-01

    This overview begins with a brief look at remote sensing to date, focusing on the state of the art and the benefits that have been derived from it. Current and future microwave sensing developments are discussed pointing out special advantages and capabilities and noting the anticipated benefits. The frequency requirements of microwave sensing are outlined and the particular need to both allocate, and when necessary, protect active and passive operational sensing frequencies is emphasized.

  10. Sunrise enhancement of equatorial vertical plasma drift

    NASA Astrophysics Data System (ADS)

    Liu, Libo; Zhang, Ruilong; Le, Huijun

    2016-04-01

    Sunrise enhancement in vertical plasma drift over equatorial regions is not discernible in the statistical picture compared with the significant enhancement during dusk hours. In this report, it is the first time to investigate the occurrence of the dawn enhancement in the equatorial ionospheric vertical plasma drift from ROCSAT-1 observations during geomagnetic quiet times. The dawn enhancements occur most frequently in June solstice and least frequently in December solstice. The statistical survey shows that the occurrence depends on the magnetic declination. The enhancement has the strongest amplitude in regions near 320° longitude and peaks during June solstice. The dawn enhancement reaches its peak after the sunrise in conjugated E regions. Furthermore, it is found that the dawn enhancement is closely related to the difference between the sunrise times in the conjugated E regions (sunrise time lag). The dawn enhancement occurs easily in regions with a large sunrise time lag. Moreover, we will report the effects of the sunrise enhancement of vertical plasma drift on the equatorial ionosphere as indicated from the observations and model simulations. We thanks National Central University of Taiwan providing the ROCSAT-1 data. The Ap and F107 indices are obtained from the National Geophysical Data Center (http://spidr.ngdc.noaa.gov/spidr/). This research is supported by National Natural Science Foundation of China (41231065), the Chinese Academy of Sciences project (KZZD-EW-01-3), National Key Basic Research Program of China (2012CB825604) and National Natural Science Foundation of China (41321003).

  11. Remote limb ischemic conditioning enhances motor learning in healthy humans.

    PubMed

    Cherry-Allen, Kendra M; Gidday, Jeff M; Lee, Jin-Moo; Hershey, Tamara; Lang, Catherine E

    2015-06-01

    Brief bouts of sublethal ischemia have been shown to protect exposed tissue (ischemic conditioning) and tissues at remote sites (remote ischemic conditioning) against subsequent ischemic challenges. Given that the mechanisms of this protective phenomenon are multifactorial and epigenetic, we postulated that remote limb ischemic conditioning (RLIC) might enhance mechanisms responsible for neural plasticity, and thereby facilitate learning. Specifically, we hypothesized that conditioning of the nervous system with RLIC, achieved through brief repetitive limb ischemia prior to training, would facilitate the neurophysiological processes of learning, thus making training more effective and more long-lasting. Eighteen healthy adults participated in this study; nine were randomly allocated to RLIC and nine to sham conditioning. All subjects underwent seven consecutive weekday sessions and 2-wk and 4-wk follow-up sessions. We found that RLIC resulted in significantly greater motor learning and longer retention of motor performance gains in healthy adults. Changes in motor performance do not appear to be due to a generalized increase in muscle activation or muscle strength and were not associated with changes in serum brain-derived neurotrophic factor (BDNF) concentration. Of note, RLIC did not enhance cognitive learning on a hippocampus-dependent task. While future research is needed to establish optimal conditioning and training parameters, this inexpensive, clinically feasible paradigm might ultimately be implemented to enhance motor learning in individuals undergoing neuromuscular rehabilitation for brain injury and other pathological conditions.

  12. Remote limb ischemic conditioning enhances motor learning in healthy humans

    PubMed Central

    Cherry-Allen, Kendra M.; Gidday, Jeff M.; Lee, Jin-Moo; Hershey, Tamara

    2015-01-01

    Brief bouts of sublethal ischemia have been shown to protect exposed tissue (ischemic conditioning) and tissues at remote sites (remote ischemic conditioning) against subsequent ischemic challenges. Given that the mechanisms of this protective phenomenon are multifactorial and epigenetic, we postulated that remote limb ischemic conditioning (RLIC) might enhance mechanisms responsible for neural plasticity, and thereby facilitate learning. Specifically, we hypothesized that conditioning of the nervous system with RLIC, achieved through brief repetitive limb ischemia prior to training, would facilitate the neurophysiological processes of learning, thus making training more effective and more long-lasting. Eighteen healthy adults participated in this study; nine were randomly allocated to RLIC and nine to sham conditioning. All subjects underwent seven consecutive weekday sessions and 2-wk and 4-wk follow-up sessions. We found that RLIC resulted in significantly greater motor learning and longer retention of motor performance gains in healthy adults. Changes in motor performance do not appear to be due to a generalized increase in muscle activation or muscle strength and were not associated with changes in serum brain-derived neurotrophic factor (BDNF) concentration. Of note, RLIC did not enhance cognitive learning on a hippocampus-dependent task. While future research is needed to establish optimal conditioning and training parameters, this inexpensive, clinically feasible paradigm might ultimately be implemented to enhance motor learning in individuals undergoing neuromuscular rehabilitation for brain injury and other pathological conditions. PMID:25867743

  13. Low resistance tunnel junctions with remote plasma underoxidized thick barriers

    SciTech Connect

    Ferreira, R.; Freitas, P.P.; MacKenzie, M.; Chapman, J.N.

    2005-05-15

    Low resistance tunnel junctions suitable for >200 Gb/inch{sup 2} read heads require RxA<1 {omega}{mu}m{sup 2} and TMR>10%, usually achieved by natural oxidation with tAl<0.7 nm barriers. This paper shows that as-deposited junctions with competitive electrical and magnetic properties can be produced starting from 0.9 nm Al barriers and remote plasma oxidation in ion beam-deposited stacks using Co{sub 73.8}Fe{sub 16.2}B{sub 10} electrodes. TMR{approx}20% for RxA{approx}2-15 {omega}{mu}m{sup 2} is obtained, while in the RxA{approx}40-140 {omega}{mu}m{sup 2} range TMR can reach 40%-45%, in as-deposited samples. A limited number of junctions exhibits considerably lower RxA values with respect to the average while keeping similar MR (down to 0.44 {omega}{mu}m{sup 2} with 20% and down to 2.2 {omega}{mu}m{sup 2} with 51%)

  14. Enhanced networked server management with random remote backups

    NASA Astrophysics Data System (ADS)

    Kim, Song-Kyoo

    2003-08-01

    In this paper, the model is focused on available server management in network environments. The (remote) backup servers are hooked up by VPN (Virtual Private Network) and replace broken main severs immediately. A virtual private network (VPN) is a way to use a public network infrastructure and hooks up long-distance servers within a single network infrastructure. The servers can be represent as "machines" and then the system deals with main unreliable and random auxiliary spare (remote backup) machines. When the system performs a mandatory routine maintenance, auxiliary machines are being used for backups during idle periods. Unlike other existing models, the availability of auxiliary machines is changed for each activation in this enhanced model. Analytically tractable results are obtained by using several mathematical techniques and the results are demonstrated in the framework of optimized networked server allocation problems.

  15. Surface-enhanced Raman fiberoptic sensors for remote monitoring

    SciTech Connect

    Stokes, D.L.; Alarie, J.P.; Vo-Dinh, T.

    1995-09-01

    A new sensor design for remote surface-enhanced Raman scattering (SERS) measurements has been developed for environmental applications. The design features the modification of an optical fiber using layers of alumina microparticles and silver coatings for inducing the SERS effect at the sensing probe. A single fiber carries both the laser excitation and the SERS signal radiation, keeping optical parameters at the remote tip simple and consistent. The small tip size achievable with this configuration also demonstrates potential of this new design as a microsensor for in-situ measurement in microenvironments. Details of sensor tip fabrication and optical system design are described. SERS spectra of aqueous environmental samples acquired in-situ using the SERS sensor are also presented to illustrate the effectiveness of the SERS sensor.

  16. Neoclassical transport in enhanced confinement toroidal plasmas

    SciTech Connect

    Lin, Z.; Tang, W.M.; Lee, W.W.

    1996-11-01

    It has recently been reported that ion thermal transport levels in enhanced confinement tokamak plasmas have been observed to fall below the irreducible minimum level predicted by standard neoclassical theory. This apparent contradiction is resolved in the present analysis by relaxing the basic neoclassical assumption that the ions orbital excursions are much smaller than the local toroidal minor radius and the equilibrium scale lengths of the system.

  17. Combustion Enhancement with a Silent Discharge Plasma

    NASA Astrophysics Data System (ADS)

    Rosocha, Louis

    2003-10-01

    It is well known that the application of an external electric field to a flame can affect its propagation speed, stability, and combustion chemistry (Lawton & Weinberg 1969). External electrodes, arc discharges, and plasma jets have been employed to allow combustible gas mixtures to operate outside their flammability limits by gas heating, injection of free radicals, and field-promoted flame stabilization (Yagodnikov & Voronetskii 1994). Other investigators have carried out experiments with silent electrical discharges applied to propagating flames (Inomata et al 1983, Kim et al 2003). These have demonstrated that the flame propagation velocity is actually decreased (combustion retarded) when a silent discharge is applied directly to the flame region, but that the flame propagation velocity is increased (combustion promoted) when a silent discharge is applied to the unburned gas mixture upstream of a flame. Two other recent works have considered the possibility of combustion enhancement in aircraft gas turbine engine combustor mixers by using a plasma-generating fuel nozzle, that employs an electric-arc or microwave plasma generator, to produce dissociated fuel or ionized fuel (Johnson et al 2001); and pulsed corona-enhanced detonation of fuel-air mixtures in jet engines (Wang et al 2003). In contrast to these prior works, we have employed a silent discharge plasma (SDP) reactor to break up large fuel molecules into smaller molecules and create free radicals or other active species in a gas stream before the fuel is mixed with an oxidizer and combusted. In experiments reported here, a cylindrical SDP reactor was used to 'activate' propane before mixing it with air and igniting the combustible gas mixture. With the plasma, the physical appearance of the flame changes and substantial changes in mass spectrometer fragmentation peaks are observed (e.g., propane fragments decrease and water and carbon dioxide increase). This indicates that the combustion process is

  18. Physics-electrical hybrid model for real time impedance matching and remote plasma characterization in RF plasma sources

    SciTech Connect

    Sudhir, Dass Bandyopadhyay, M.; Chakraborty, A.

    2016-02-15

    Plasma characterization and impedance matching are an integral part of any radio frequency (RF) based plasma source. In long pulse operation, particularly in high power operation where plasma load may vary due to different reasons (e.g. pressure and power), online tuning of impedance matching circuit and remote plasma density estimation are very useful. In some cases, due to remote interfaces, radio activation and, due to maintenance issues, power probes are not allowed to be incorporated in the ion source design for plasma characterization. Therefore, for characterization and impedance matching, more remote schemes are envisaged. Two such schemes by the same authors are suggested in these regards, which are based on air core transformer model of inductive coupled plasma (ICP) [M. Bandyopadhyay et al., Nucl. Fusion 55, 033017 (2015); D. Sudhir et al., Rev. Sci. Instrum. 85, 013510 (2014)]. However, the influence of the RF field interaction with the plasma to determine its impedance, a physics code HELIC [D. Arnush, Phys. Plasmas 7, 3042 (2000)] is coupled with the transformer model. This model can be useful for both types of RF sources, i.e., ICP and helicon sources.

  19. Physics-electrical hybrid model for real time impedance matching and remote plasma characterization in RF plasma sources

    NASA Astrophysics Data System (ADS)

    Sudhir, Dass; Bandyopadhyay, M.; Chakraborty, A.

    2016-02-01

    Plasma characterization and impedance matching are an integral part of any radio frequency (RF) based plasma source. In long pulse operation, particularly in high power operation where plasma load may vary due to different reasons (e.g. pressure and power), online tuning of impedance matching circuit and remote plasma density estimation are very useful. In some cases, due to remote interfaces, radio activation and, due to maintenance issues, power probes are not allowed to be incorporated in the ion source design for plasma characterization. Therefore, for characterization and impedance matching, more remote schemes are envisaged. Two such schemes by the same authors are suggested in these regards, which are based on air core transformer model of inductive coupled plasma (ICP) [M. Bandyopadhyay et al., Nucl. Fusion 55, 033017 (2015); D. Sudhir et al., Rev. Sci. Instrum. 85, 013510 (2014)]. However, the influence of the RF field interaction with the plasma to determine its impedance, a physics code HELIC [D. Arnush, Phys. Plasmas 7, 3042 (2000)] is coupled with the transformer model. This model can be useful for both types of RF sources, i.e., ICP and helicon sources.

  20. Physics-electrical hybrid model for real time impedance matching and remote plasma characterization in RF plasma sources.

    PubMed

    Sudhir, Dass; Bandyopadhyay, M; Chakraborty, A

    2016-02-01

    Plasma characterization and impedance matching are an integral part of any radio frequency (RF) based plasma source. In long pulse operation, particularly in high power operation where plasma load may vary due to different reasons (e.g. pressure and power), online tuning of impedance matching circuit and remote plasma density estimation are very useful. In some cases, due to remote interfaces, radio activation and, due to maintenance issues, power probes are not allowed to be incorporated in the ion source design for plasma characterization. Therefore, for characterization and impedance matching, more remote schemes are envisaged. Two such schemes by the same authors are suggested in these regards, which are based on air core transformer model of inductive coupled plasma (ICP) [M. Bandyopadhyay et al., Nucl. Fusion 55, 033017 (2015); D. Sudhir et al., Rev. Sci. Instrum. 85, 013510 (2014)]. However, the influence of the RF field interaction with the plasma to determine its impedance, a physics code HELIC [D. Arnush, Phys. Plasmas 7, 3042 (2000)] is coupled with the transformer model. This model can be useful for both types of RF sources, i.e., ICP and helicon sources.

  1. Enhancing fieldwork learning using blended learning, GIS and remote supervision

    NASA Astrophysics Data System (ADS)

    Marra, Wouter A.; Alberti, Koko; Karssenberg, Derek

    2015-04-01

    Fieldwork is an important part of education in geosciences and essential to put theoretical knowledge into an authentic context. Fieldwork as teaching tool can take place in various forms, such as field-tutorial, excursion, or supervised research. Current challenges with fieldwork in education are to incorporate state-of-the art methods for digital data collection, on-site GIS-analysis and providing high-quality feedback to large groups of students in the field. We present a case on first-year earth-sciences fieldwork with approximately 80 students in the French Alps focused on geological and geomorphological mapping. Here, students work in couples and each couple maps their own fieldwork area to reconstruct the formative history. We present several major improvements for this fieldwork using a blended-learning approach, relying on open source software only. An important enhancement to the French Alps fieldwork is improving students' preparation. In a GIS environment, students explore their fieldwork areas using existing remote sensing data, a digital elevation model and derivatives to formulate testable hypotheses before the actual fieldwork. The advantage of this is that the students already know their area when arriving in the field, have started to apply the empirical cycle prior to their field visit, and are therefore eager to investigate their own research questions. During the fieldwork, students store and analyze their field observations in the same GIS environment. This enables them to get a better overview of their own collected data, and to integrate existing data sources also used in the preparation phase. This results in a quicker and enhanced understanding by the students. To enable remote access to observational data collected by students, the students synchronize their data daily with a webserver running a web map application. Supervisors can review students' progress remotely, examine and evaluate their observations in a GIS, and provide

  2. The enhancement mechanism of thin plasma layer on antenna radiation

    SciTech Connect

    Wang, Chunsheng Jiang, Binhao; Li, Xueai

    2015-03-09

    A model of plasma-antenna is carried out to study the radiation enhancement mechanism of antenna covered by thin plasma layer. The results show when the radiation intensity achieves maximum, a region of equal electric field is formed due to the reflection of electric field at the interface of plasma and air. The plasma layer acted as an extension of the antenna. Furthermore, the shape of plasma layer is changed to verify the effect of plasma boundary on antenna radiation. The study shows the effect of thin plasma layer on electromagnetic field and provides a type of plasma antenna.

  3. The α and γ plasma modes in plasma-enhanced atomic layer deposition with O2–N2 capacitive discharges

    NASA Astrophysics Data System (ADS)

    Napari, M.; Tarvainen, O.; Kinnunen, S.; Arstila, K.; Julin, J.; Fjellvåg, Ø. S.; Weibye, K.; Nilsen, O.; Sajavaara, T.

    2017-03-01

    Two distinguishable plasma modes in the O2–N2 radio frequency capacitively coupled plasma (CCP) used in remote plasma-enhanced atomic layer deposition (PEALD) were observed. Optical emission spectroscopy and spectra interpretation with rate coefficient analysis of the relevant processes were used to connect the detected modes to the α and γ modes of the CCP discharge. To investigate the effect of the plasma modes on the PEALD film growth, ZnO and TiO2 films were deposited using both modes and compared to the films deposited using direct plasma. The growth rate, thickness uniformity, elemental composition, and crystallinity of the films were found to correlate with the deposition mode. In remote CCP operations the transition to the γ mode can result in a parasitic discharge leading to uncontrollable film growth and thus limit the operation parameters of the capacitive discharge in the PEALD applications.

  4. [Improvement of PVC bio-carrier surface property by remote plasma].

    PubMed

    Li, Ru; Chen, Jie-Rong; Chen, Jun; Yao, Xin

    2006-01-01

    The effects of various remote plasma, such as Ar, He, O2 and N2 on PVC bio-carrier surface modification were studied. The surface properties were characterized by the contact angle measurement and X-ray photoelectron spectroscopy (XPS). The role of all kinds of active species such as electrons, ions and free radicals involved in plasma surface modification were evaluated. Results show that the remote plasma treatments modify the PVC surface in both wettability and composition, the (O + N)/C of PVC surface increases from 7% to 22%, and the water contact angle decreases from 97 degrees to 15 degrees. The optimal results was achieved when plasma treatment parameters were set, that is treatment time 3 min, Ar flux at 20 cm3/s, power at 60W, sample position of 40 cm. The results show that the modified PVC Bio-carrier adhesion rate and capacity on the modified surface are greatly increased.

  5. Remote sensing of plasma injection and acceleration phenomena

    NASA Technical Reports Server (NTRS)

    Burch, J. L.

    1985-01-01

    Dynamics Explorer-1 High Altitude Plasma Instrument data have been used to investigate the injection of magnetosheath plasma into the polar cusp, the injection of auroral ion beams into the magnetosphere, and the acceleration of electrons transverse to the magnetic field direction, and the results are discussed. In the case of polar cusp plasmas, it is found that injection occurs at the high-latitude magnetopause, at geocentric distances near eight earth radii. In the case of auroral ion beams it is determined that ion bands are not produced by equatorial injection from the plasma sheet, but by the upward acceleration of ions from auroral acceleration regions. Finally, conical electron distributions are found to be consistent with transverse acceleration at altitudes of a thousand or more km, within or below the magnetic-field-aligned potential drops of the auroral acceleration regions.

  6. Low-Temperature Silicon Epitaxy by Remote, Plasma - Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Habermehl, Scott Dwight

    The dynamics of low temperature Si homoepitaxial and heteroepitaxial growth, by remote plasma enhanced chemical vapor deposition, RPECVD, have been investigated. For the critical step of pre-deposition surface preparation of Si(100) surfaces, the attributes of remote plasma generated atomic H are compared to results obtained with a rapid thermal desorption, RTD, technique and a hybrid H-plasma/RTD technique. Auger electron spectroscopy, AES, and electron diffraction analysis indicate the hybrid technique to be very effective at surface passivation, while the RTD process promotes the formation of SiC precipitates, which induce defective epitaxial growth. For GaP and GaAs substrates, the use of atomic H exposure is investigated as a surface passivation technique. AES shows this technique to be effective at producing atomically clean surfaces. For processing at 400^circrm C, the GaAs(100) surface is observed to reconstruct to a c(8 x 2)Ga symmetry while, at 530^ circrm C the vicinal GaP(100) surface, miscut 10^circ , is observed to reconstruct to a (1 x n) type symmetry; an unreconstructed (1 x 1) symmetry is observed for GaP(111). Differences in the efficiency with which native oxides are removed from the surface are attributed to variations in the local atomic bonding order of group V oxides. The microstructure of homoepitaxial Si films, deposited at temperatures of 25-450^circ rm C and pressures of 50-500 mTorr, is catalogued. Optimized conditions for the deposition of low defect, single crystal films are identified. The existence of two pressure dependent regimes for process activation are observed. In-situ mass spectral analysis indicates that the plasma afterglow is dominated by monosilane ions below 200 mTorr, while above 200 mTorr, low mass rm H_{x} ^+ (x = 1,2,3) and rm HHe^+ ions dominate. Consideration of the growth rate data indicates that downstream dissociative silane ionization, in the lower pressure regime, is responsible for an enhanced surface H

  7. Remote Plasma Oxidation and Atomic Layer Etching of MoS2.

    PubMed

    Zhu, Hui; Qin, Xiaoye; Cheng, Lanxia; Azcatl, Angelica; Kim, Jiyoung; Wallace, Robert M

    2016-07-27

    Exfoliated molybdenum disulfide (MoS2) is shown to chemically oxidize in a layered manner upon exposure to a remote O2 plasma. X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and atomic force microscopy (AFM) are employed to characterize the surface chemistry, structure, and topography of the oxidation process and indicate that the oxidation mainly occurs on the topmost layer without altering the chemical composition of underlying layer. The formation of S-O bonds upon short, remote plasma exposure pins the surface Fermi level to the conduction band edge, while the MoOx formation at high temperature modulates the Fermi level toward the valence band through band alignment. A uniform coverage of monolayer amorphous MoO3 is obtained after 5 min or longer remote O2 plasma exposure at 200 °C, and the MoO3 can be completely removed by annealing at 500 °C, leaving a clean ordered MoS2 lattice structure as verified by XPS, LEED, AFM, and scanning tunneling microscopy. This work shows that a remote O2 plasma can be useful for both surface functionalization and a controlled thinning method for MoS2 device fabrication processes.

  8. Enhancement of terahertz wave generation from laser induced plasma

    SciTech Connect

    Xie Xu; Xu Jingzhou; Dai Jianming; Zhang, X.-C.

    2007-04-02

    It is well known that air plasma induced by ultrashort laser pulses emits broadband terahertz waves. The authors report the study of terahertz wave generation from the laser induced plasma where there is a preexisting plasma background. When a laser beam from a Ti:sapphire amplifier is used to generate a terahertz wave, enhancement of the generation is observed if there is another laser beam creating a plasma background. The enhancement of the terahertz wave amplitude lasts hundreds of picoseconds after the preionized background is created, with a maximum enhancement up to 250% observed.

  9. Space Plasma Studies by In-Situ and Remote Measurements

    DTIC Science & Technology

    2007-11-02

    Awarded by Lenin Prize (highest in USSR). 1962 Plasma experiments aboard KOSMOS 2, evidence of the lack of charged particles thermodynamic equilibrium...ionosphere of Venus. 1970- 1979 Ionospheric experiments aboard COSMOS 378, INTERCOSMOS 8,10,12,14,18,19 and KOSMOS 900. 1970- 1981 Series of in

  10. Hydrogen desorption kinetics for aqueous hydrogen fluoride and remote hydrogen plasma processed silicon (001) surfaces

    SciTech Connect

    King, Sean W. Davis, Robert F.; Carter, Richard J.; Schneider, Thomas P.; Nemanich, Robert J.

    2015-09-15

    The desorption kinetics of molecular hydrogen (H{sub 2}) from silicon (001) surfaces exposed to aqueous hydrogen fluoride and remote hydrogen plasmas were examined using temperature programmed desorption. Multiple H{sub 2} desorption states were observed and attributed to surface monohydride (SiH), di/trihydride (SiH{sub 2/3}), and hydroxide (SiOH) species, subsurface hydrogen trapped at defects, and hydrogen evolved during the desorption of surface oxides. The observed surface hydride species were dependent on the surface temperature during hydrogen plasma exposure with mono, di, and trihydride species being observed after low temperature exposure (150 °C), while predominantly monohydride species were observed after higher temperature exposure (450 °C). The ratio of surface versus subsurface H{sub 2} desorption was also found to be dependent on the substrate temperature with 150 °C remote hydrogen plasma exposure generally leading to more H{sub 2} evolved from subsurface states and 450 °C exposure leading to more H{sub 2} desorption from surface SiH{sub x} species. Additional surface desorption states were observed, which were attributed to H{sub 2} desorption from Si (111) facets formed as a result of surface etching by the remote hydrogen plasma or aqueous hydrogen fluoride treatment. The kinetics of surface H{sub 2} desorption were found to be in excellent agreement with prior investigations of silicon surfaces exposed to thermally generated atomic hydrogen.

  11. Remote operation of the GOLEM tokamak with hydrogen and helium plasmas

    NASA Astrophysics Data System (ADS)

    Svoboda, V.; Dvornova, A.; Dejarnac, R.; Prochazka, M.; Zaprianov, S.; Akhmethanov, R.; Bogdanova, M.; Dimitrova, M.; Dimitrov, Zh; Grover, O.; Hlavata, L.; Ivanov, K.; Kruglov, K.; Marinova, P.; Masherov, P.; Mogulkin, A.; Mlynar, J.; Stockel, J.; Volynets, A.

    2016-10-01

    The GOLEM tokamak was operated remotely via Internet connection during the 6th International Workshop and Summer School on Plasma Physics. Performances of hydrogen and helium discharges are compared in this paper. It is found, at similar vacuum conditions, that helium discharges are shorter but the breakdown of the working gas can be quite easily achieved at almost the same loop voltage. The plasma current in helium discharges is slightly lower than in the case of hydrogen. Turbulent fluctuations of the floating potential measured by means of an array of Langmuir probes reveal a noticeably different character in the two discharges.

  12. Hippocampal neurogenesis enhancers promote forgetting of remote fear memory after hippocampal reactivation by retrieval.

    PubMed

    Ishikawa, Rie; Fukushima, Hotaka; Frankland, Paul W; Kida, Satoshi

    2016-09-26

    Forgetting of recent fear memory is promoted by treatment with memantine (MEM), which increases hippocampal neurogenesis. The approaches for treatment of post-traumatic stress disorder (PTSD) using rodent models have focused on the extinction and reconsolidation of recent, but not remote, memories. Here we show that, following prolonged re-exposure to the conditioning context, enhancers of hippocampal neurogenesis, including MEM, promote forgetting of remote contextual fear memory. However, these interventions are ineffective following shorter re-exposures. Importantly, we find that long, but not short re-exposures activate gene expression in the hippocampus and induce hippocampus-dependent reconsolidation of remote contextual fear memory. Furthermore, remote memory retrieval becomes hippocampus-dependent after the long-time recall, suggesting that remote fear memory returns to a hippocampus dependent state after the long-time recall, thereby allowing enhanced forgetting by increased hippocampal neurogenesis. Forgetting of traumatic memory may contribute to the development of PTSD treatment.

  13. Enhanced laser beam coupling to a plasma

    DOEpatents

    Steiger, Arno D.; Woods, Cornelius H.

    1976-01-01

    Density perturbations are induced in a heated plasma by means of a pair of oppositely directed, polarized laser beams of the same frequency. The wavelength of the density perturbations is equal to one half the wavelength of the laser beams. A third laser beam is linearly polarized and directed at the perturbed plasma along a line that is perpendicular to the direction of the two opposed beams. The electric field of the third beam is oriented to lie in the plane containing the three beams. The frequency of the third beam is chosen to cause it to interact resonantly with the plasma density perturbations, thereby efficiently coupling the energy of the third beam to the plasma.

  14. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    SciTech Connect

    Timofeev, I. V.; Annenkov, V. V.; Arzhannikov, A. V.

    2015-11-15

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.

  15. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    NASA Astrophysics Data System (ADS)

    Timofeev, I. V.; Annenkov, V. V.; Arzhannikov, A. V.

    2015-11-01

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.

  16. Dielectric properties in microwave remote plasma sustained in argon: Expanding plasma conditions

    SciTech Connect

    Jauberteau, J. L.; Jauberteau, I.

    2012-11-15

    This work is devoted to the study of the relative permittivity in argon expanding plasma produced below a microwave discharge sustained in a quartz tube and working at 2.45 GHz. We discuss results and explain the microwave propagation within the reactor, outside the quartz tube. It is shown that at low pressures (133 Pa) and at powers ranging from 100 W to 400 W, the wave frequency remains lower than the plasma frequency anywhere in the expanding plasma. Under these conditions, the real part of the relative permittivity is negative and the wave is reflected. Surprisingly, in these conditions, the plasma is produced inside and outside the quartz tube, below the wave launcher. This effect can be explained considering a surface wave propagating at the surface of the quartz tube then into the reactor, on the external surface of the expanding plasma below the quartz tube.

  17. Diagnostics of N2 Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

    NASA Astrophysics Data System (ADS)

    Saloum, S.; Naddaf, M.; Alkhaled, B.

    2008-02-01

    N2-x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 <= x <= 80), at a constant applied RF power of 300 W. N2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I_N/I_{N_2} of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N2 second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N2, with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N_{2}^{+} density varies between 5 × 109 and 1.4 × 1010 cm-3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B 2Σ+-X 2Σ+) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

  18. The dawn enhancement of the equatorial ionospheric vertical plasma drift

    NASA Astrophysics Data System (ADS)

    Zhang, Ruilong; Liu, Libo; Chen, Yiding; Le, Huijun

    2015-12-01

    Previous studies have reported that a dawn enhancement does not present in the statistical picture of the equatorial ionospheric vertical plasma drift, while it clearly shows in case measurements. In this statistical study, it is the first time to investigate the occurrence of the dawn enhancement in the equatorial ionospheric vertical plasma drift from ROCSAT-1 observations during geomagnetic quiet times. The dawn enhancements occur most frequently in June solstice and least frequently in December solstice. The statistical survey shows that the occurrence depends on the magnetic declination. The enhancement has the strongest amplitude in regions near 320° longitude and peaks during June solstice. The dawn enhancement reaches its peak after the sunrise in conjugated E regions. Furthermore, it is found that the dawn enhancement is closely related to the difference between the sunrise times in the conjugated E regions (sunrise time lag). The dawn enhancement occurs easily in regions with a large sunrise time lag.

  19. Toroidal plasma enhanced CVD of diamond films

    SciTech Connect

    Zvanya, John Cullen, Christopher Morris, Thomas Krchnavek, Robert R.; Holber, William Basnett, Andrew Basnett, Robert; Hettinger, Jeffrey

    2014-09-01

    An inductively coupled toroidal plasma source is used as an alternative to microwave plasmas for chemical vapor deposition of diamond films. The source, operating at a frequency of 400 kHz, synthesizes diamond films from a mixture of argon, methane, and hydrogen. The toroidal design has been adapted to create a highly efficient environment for diamond film deposition: high gas temperature and a short distance from the sample to the plasma core. Using a toroidal plasma geometry operating in the medium frequency band allows for efficient (≈90%) coupling of AC line power to the plasma and a scalable path to high-power and large-area operation. In test runs, the source generates a high flux of atomic hydrogen over a large area, which is favorable for diamond film growth. Using a deposition temperature of 900–1050 °C and a source to sample distance of 0.1–2.0 cm, diamond films are deposited onto silicon substrates. The results showed that the deposition rate of the diamond films could be controlled using the sample temperature and source to sample spacing. The results also show the films exhibit good-quality polycrystalline diamond as verified by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. The scanning electron microscopy and x-ray diffraction results show that the samples exhibit diamond (111) and diamond (022) crystallites. The Raman results show that the sp{sup 3} peak has a narrow spectral width (FWHM 12 ± 0.5 cm{sup −1}) and that negligible amounts of the sp{sup 2} band are present, indicating good-quality diamond films.

  20. The application of image enhancement techniques to remote manipulator operation

    NASA Technical Reports Server (NTRS)

    Gonzalez, R. C.

    1974-01-01

    Methods of image enhancement which can be used by an operator who is not experienced with the mechanisms of enhancement to obtain satisfactory results were designed and implemented. Investigation of transformations which operate directly on the image domain resulted in a new technique of contrast enhancement. Transformations on the Fourier transform of the original image, including such techniques as homomorphic filtering, were also investigated. The methods of communication between the enhancement system and the computer operator were analyzed, and a language was developed for use in image enhancement. A working enhancement system was then created, and is included.

  1. Optimization of hollow cathode discharge electrode for damage free remote plasma removal process for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Cho, Tae S.; Han, Qing; Yang, Dongqing; Park, Soonam; Lubomirsky, Dima; Venkataraman, Shankar

    2016-05-01

    Cone-shaped hollow cathode electrode configuration for a damage free remote plasma removal process has been optimized for given pressures based on Paschen characteristic curves, voltage-current characteristics and time-resolved discharge observations as well as oxide film removal performances. Remote plasmas have been generated in two types of cone-shaped electrodes with mixtures of He, NF3, and NH3 for pressure range of 1-30 Torr. Paschen characteristic curves and voltage-current (V-I) characteristics define an operating pressure for low breakdown voltage and the hollow cathode effect to minimize the particles. Sinusoidal voltage waveform and asymmetry electrode configuration alternate the glow discharge and hollow cathode discharge modes in a cycle. The current and infrared emission intensity from the glow discharge increases together for both cone-shaped electrodes with increasing pressure, whereas the hollow cathode discharge plasma emits strong infrared only when pD condition is satisfied. For the wide cone electrode configuration, high voltage operation at higher pressure results in particle contamination on the processed wafer by high energy ion bombardment. Operating at optimum pressure for a given electrode configuration shows faster oxide etch rate with better uniformity over a whole 300 mm wafer.

  2. Mobile setup for synchrotron based in situ characterization during thermal and plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Dendooven, Jolien; Solano, Eduardo; Minjauw, Matthias M.; Van de Kerckhove, Kevin; Coati, Alessandro; Fonda, Emiliano; Portale, Giuseppe; Garreau, Yves; Detavernier, Christophe

    2016-11-01

    We report the design of a mobile setup for synchrotron based in situ studies during atomic layer processing. The system was designed to facilitate in situ grazing incidence small angle x-ray scattering (GISAXS), x-ray fluorescence (XRF), and x-ray absorption spectroscopy measurements at synchrotron facilities. The setup consists of a compact high vacuum pump-type reactor for atomic layer deposition (ALD). The presence of a remote radio frequency plasma source enables in situ experiments during both thermal as well as plasma-enhanced ALD. The system has been successfully installed at different beam line end stations at the European Synchrotron Radiation Facility and SOLEIL synchrotrons. Examples are discussed of in situ GISAXS and XRF measurements during thermal and plasma-enhanced ALD growth of ruthenium from RuO4 (ToRuS™, Air Liquide) and H2 or H2 plasma, providing insights in the nucleation behavior of these processes.

  3. Mobile setup for synchrotron based in situ characterization during thermal and plasma-enhanced atomic layer deposition.

    PubMed

    Dendooven, Jolien; Solano, Eduardo; Minjauw, Matthias M; Van de Kerckhove, Kevin; Coati, Alessandro; Fonda, Emiliano; Portale, Giuseppe; Garreau, Yves; Detavernier, Christophe

    2016-11-01

    We report the design of a mobile setup for synchrotron based in situ studies during atomic layer processing. The system was designed to facilitate in situ grazing incidence small angle x-ray scattering (GISAXS), x-ray fluorescence (XRF), and x-ray absorption spectroscopy measurements at synchrotron facilities. The setup consists of a compact high vacuum pump-type reactor for atomic layer deposition (ALD). The presence of a remote radio frequency plasma source enables in situ experiments during both thermal as well as plasma-enhanced ALD. The system has been successfully installed at different beam line end stations at the European Synchrotron Radiation Facility and SOLEIL synchrotrons. Examples are discussed of in situ GISAXS and XRF measurements during thermal and plasma-enhanced ALD growth of ruthenium from RuO4 (ToRuS™, Air Liquide) and H2 or H2 plasma, providing insights in the nucleation behavior of these processes.

  4. Patterning of graphene for flexible electronics with remote atmospheric-pressure plasma using dielectric barrier

    NASA Astrophysics Data System (ADS)

    Kim, Duk Jae; Park, Jeongwon; Geon Han, Jeon

    2016-08-01

    We show results of the patterning of graphene layers on poly(ethylene terephthalate) (PET) films through remote atmospheric-pressure dielectric barrier discharge plasma. The size of plasma discharge electrodes was adjusted for large-area and role-to-role-type substrates. Optical emission spectroscopy (OES) was used to analyze the characteristics of charge species in atmospheric-pressure plasma. The OES emission intensity of the O2* peaks (248.8 and 259.3 nm) shows the highest value at the ratio of \\text{N}2:\\text{clean dry air (CDA)} = 100:1 due to the highest plasma discharge. The PET surface roughness and hydrophilic behavior were controlled with CDA flow rate during the process. Although the atmospheric-pressure plasma treatment of the PET film led to an increase in the FT-IR intensity of C-O bonding at 1240 cm-1, the peak intensity at 1710 cm-1 (C=O bonding) decreased. The patterning of graphene layers was confirmed by scanning electron microscopy and Raman spectroscopy.

  5. Enhanced endotoxin effects in plasma fibronectin-deficient rats.

    PubMed Central

    Yoder, M C; Kilpatrick-Smith, L; Arbittier, D; Douglas, S D; Polin, R A

    1987-01-01

    Immunoreactive plasma fibronectin depletion has been associated with the presence of collagen-fibronectin complexes in patients after trauma and in animal models of traumatic and burn injuries. However, the role of plasma fibronectin in the development of sepsis after traumatic and burn injuries in patients is unknown. Treatment of patients and animals with purified human plasma fibronectin ameliorates some of the clinical and metabolic effects of systemic endotoxemia. We report that the induction of immunoreactive plasma fibronectin deficiency by gelatin infusion is associated with enhanced effects of intraperitoneal Escherichia coli endotoxin injection. We have observed a significant increase in the concentrations of ammonia in plasma of treated rats compared with those in control rats administered the same dose of endotoxin. PMID:3298066

  6. Extraction characteristics of a low-energy ion beam system with a remote plasma chamber

    SciTech Connect

    Vasquez, M. R.; Wada, M.

    2016-02-15

    Low-energy argon beams were extracted from a dual-chamber ion source system. The first chamber is a quartz cylinder where dense inductively coupled plasmas were produced using 13.56 MHz radio frequency (rf) power. The discharge was driven into an adjacent chamber which acts as a reservoir for ion beam extraction using a dual-electrode extractor configuration. Extraction of ions from the second chamber with energies in the 100 eV range was achieved while minimizing fluctuations induced by the rf signal. A custom-built retarding potential analyzer was used to analyze the effectiveness of ion beam transport using the remote plasma chamber. Well-defined beams were extracted between 60 and 100 V extraction potentials at 50–100 W rf powers. An increase in rf power resulted in an increase in average ion energy, increase in ion current density while the energy spread remains constant.

  7. Enhance and Test the Remote Seismic Terminal. Volume I

    DTIC Science & Technology

    1983-01-01

    I4C 1iPTA Jul ion Drl ti *v, r r c? 1:ZS:54z 21:55:54.50 21:56:00.00 SRS time assigned to the beginning of the above data A758: 524r 4E44 4F55 5420...Introduct ion The Remote S e ism ic T e rm i nal (R’ST) has been described elsewhere C 1 3. B r ie f1y , i t i s a mi cr o comP ut e r-based work s...every deonons Ira t ion of ’he HST the first question to be asked w4a s "C an I hook th is t h ing u p t o a s e 1smon.,ete cr ? ".Th e u nizt t o b e

  8. Wave enhancement of electron runaway rate in a collisional plasma

    SciTech Connect

    An, Z.; Liu, C.; Lee, Y.; Boyd, D.

    1982-06-01

    The effects of plasma waves on the electron runaway production rate is studied. For a wave packet with a one-dimensional spectrum directed along the electric field and with a phase velocity range containing the critical velocity v/sub c/ for runaway, the runaway production rate is found to be enhanced by many orders of magnitude. For an isotropic wave spectrum, however, the runaway production rate is reduced because of the wave-enhanced pitch angle scattering.

  9. Device performance of in situ steam generated gate dielectric nitrided by remote plasma nitridation

    NASA Astrophysics Data System (ADS)

    Al-Shareef, H. N.; Karamcheti, A.; Luo, T. Y.; Bersuker, G.; Brown, G. A.; Murto, R. W.; Jackson, M. D.; Huff, H. R.; Kraus, P.; Lopes, D.; Olsen, C.; Miner, G.

    2001-06-01

    In situ steam generated (ISSG) oxides have recently attracted interest for use as gate dielectrics because of their demonstrated reliability improvement over oxides formed by dry oxidation. [G. Minor, G. Xing, H. S. Joo, E. Sanchez, Y. Yokota, C. Chen, D. Lopes, and A. Balakrishna, Electrochem. Soc. Symp. Proc. 99-10, 3 (1999); T. Y. Luo, H. N. Al-Shareef, G. A. Brown, M. Laughery, V. Watt, A. Karamcheti, M. D. Jackson, and H. R. Huff, Proc. SPIE 4181, 220 (2000).] We show in this letter that nitridation of ISSG oxide using a remote plasma decreases the gate leakage current of ISSG oxide by an order of magnitude without significantly degrading transistor performance. In particular, it is shown that the peak normalized transconductance of n-channel devices with an ISSG oxide gate dielectric decreases by only 4% and the normalized drive current by only 3% after remote plasma nitridation (RPN). In addition, it is shown that the reliability of the ISSG oxide exhibits only a small degradation after RPN. These observations suggest that the ISSG/RPN process holds promise for gate dielectric applications.

  10. Remote sensing of plasma motion and turbulence near the Alfvén surface

    NASA Astrophysics Data System (ADS)

    DeForest, C. E.

    2015-12-01

    Despite a rich nearly-century-long history, Thomson scattering has not been fully exploited as a remote-sensing tool in the corona and nascent solar wind. In particular, stable deep-space coronagraphs such as SOHO/LASCO and STEREO/SECCHI enable time-dependent, photometric analyses that transcend basic feature tracking and brightness estimation. These techniques offer direct insight into the plasma conditions in the outer corona. In particular, fluctuations in the outer coronal brightness comprise both the familiar inhomogeneous "blobs" of material first tracked quantitatively with SOHO/LASCO, and also a recently-discovered compressive wave field that permits remote probing of the plasma even though individual wave fronts do not stand out visually. I will discuss recent and current measurements of this wave field in the outer corona as a means to probe outer coronal heating and wind acceleration near the transition from corona to heliosphere (known as the Alfvén surface); and present current results from a study of the transition from mostly smooth to mostly turbulent flow in the nascent solar wind.

  11. Remote plasma assisted growth of graphene films: structure and physical properties

    NASA Astrophysics Data System (ADS)

    Rouvimov, Sergei; Nandamuri, Gopichand; Solanki, Raj

    2010-03-01

    The unique electrical properties of graphene, in particular ballistic transport and tunable transport properties have opened up exciting possibilities for this material as a replacement for silicon [1-2]. While graphene is commonly produced in research laboratories by mechanical exfoliation of highly oriented pyrolytic graphite, mass production of graphene-based devices requires technological approach to synthesize thin graphene films such as chemical vapor deposition. In present work, single and multiple layers of graphene films were grown on (111) oriented single crystals of nickel and polycrystalline nickel films using remote plasma assisted chemical vapor deposition. Remote plasma was employed to eliminate the effect of the electrical field on the orientation of the grown graphene films, as well as reduce the growth temperature compared to conventional chemical vapor deposition. The electrical and optical properties, including high resolution transmission electron microscopy of these films, suggest that this approach is both versatile and scalable for potential large area optoelectronic applications. [4pt] [1] T. Ohta, et al. Science 2006, 313, 951- 954 [0pt] [2] Y. B, Zhang, et al. Nature 2005, 438, 201- 204

  12. Enhanced magnetic ionization in hydrogen reflex discharge plasma source

    SciTech Connect

    Toader, E.I.; Covlea, V.N.

    2005-03-01

    The effect of enhanced magnetic ionization on the external and internal parameters of a high-density, low pressure reflex plasma source operating in hydrogen is studied. The Langmuir probe method and Druyvesteyn procedure coupled with suitable software are used to measure the internal parameters. The bulk plasma region is free of an electric field and presents a high degree of uniformity. The electron energy distribution function is bi-Maxwellian with a dip/shoulder structure around 5.5 eV, independent of external parameters and radial position. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the electron density n{sub e} is as high as 10{sup 18} m{sup -3}, and the electron temperature T{sub e} is as low as a few tens of an electron volt, for dissipated energy of tens of Watts. The bulk plasma density scales with the dissipated power.

  13. Enhancement of Space Plasma Images by Complex Wavelets

    NASA Astrophysics Data System (ADS)

    Souza, Vitor Moura; Domingues, Margarete Oliveira; Mendes, Odim; Pagamisse, Aylton; Stenborg, Guillermo Adrian

    2015-10-01

    The Sun is a natural laboratory for plasma processes. A myriad of instruments aboard satellites and on ground record(ed) the plasma emission in different ranges of the electromagnetic spectrum to help understand such processes. In particular, in the outer part of the solar atmosphere, the solar corona, we can observe a multitude of electrodynamical phenomena. There, the faint corona emission and the associated dynamic plasma structures (e.g., coronal mass ejections—CMEs) recorded in white-light images can be used as basis for some insight of this physical scenario. In order to characterize the dynamics and morphology of such structures in a better way, it seems crucial that some features of those images should be enhanced. To deal with this need, a new approach using a complex wavelet transform methodology was developed. With the proposed methodology, we can highlight the plasma ejections improving the identification of those structures.

  14. Inductively-coupled-plasma-induced electret enhancement for triboelectric nanogenerators.

    PubMed

    Liu, Long; Tang, Wei; Wang, Zhong Lin

    2017-01-20

    Polyethylene terephthalate (PET) films' electret property was significantly enhanced after being treated with inductively coupled plasma (ICP). Based on this modified material, the triboelectric nanogenerators' (TENGs) transferred charges remained at 68.6% of the initial value after 400 000 cycles of contact-separation process, which was about three times that of the untreated samples.

  15. Inductively-coupled-plasma-induced electret enhancement for triboelectric nanogenerators

    NASA Astrophysics Data System (ADS)

    Liu, Long; Tang, Wei; Wang, Zhong Lin

    2017-01-01

    Polyethylene terephthalate (PET) films’ electret property was significantly enhanced after being treated with inductively coupled plasma (ICP). Based on this modified material, the triboelectric nanogenerators’ (TENGs) transferred charges remained at 68.6% of the initial value after 400 000 cycles of contact-separation process, which was about three times that of the untreated samples.

  16. On the generation of magnetic field enhanced microwave plasma line

    NASA Astrophysics Data System (ADS)

    Chen, Longwei; Zhao, Ying; Wu, Kenan; Wang, Qi; Meng, Yuedong; Ren, Zhaoxing

    2016-12-01

    Microwave linear plasmas sustained by surface waves have attracted much attention due to the potential abilities to generate large-scale and uniform non-equilibrium plasmas. An external magnetic field was generally applied to enhance and stabilize plasma sources because the magnetic field decreased the electron losses on the wall. The effects of magnetic field on the generation and propagation mechanisms of the microwave plasma were tentatively investigated based on a 2-D numerical model combining a coupled system of Maxwell's equations and continuity equations. The mobility of electrons and effective electric conductivity of the plasma were considered as a full tensor in the presence of magnetic field. Numerical results indicate that both cases of magnetic field in the axial-direction and radial-direction benefit the generation of a high-density plasma; the former one allows the microwave to propagate longer in the axis direction compared to the latter one. The time-averaged power flow density and the amplitude of the electric field on the inner rod of coaxial waveguide attenuate with the propagation of the microwave for both cases of with and without external magnetic field. The attenuation becomes smaller in the presence of appropriately higher axial-direction magnetic field, which allows more microwave energies to transmit along the axial direction. Meanwhile, the anisotropic properties of the plasma, like electron mobility, in the presence of the magnetic field confine more charged particles in the direction of the magnetic field line.

  17. Using ICT to Enhance Curriculum Opportunities for Students in Rural and Remote Schools

    ERIC Educational Resources Information Center

    White, Bruce

    2010-01-01

    South Australian rural and remote schools have been using a variety of Information and Communication Technologies (ICT) to enhance curriculum opportunities for students whose teachers are at a different campus or different school, or who are out of the school for extended periods of time undertaking courses, such as, Vocational Education and…

  18. Equatorial plasma bubbles with enhanced ion and electron temperatures

    NASA Astrophysics Data System (ADS)

    Park, Jaeheung; Min, Kyoung Wook; Kim, Vitaly P.; Kil, Hyosub; Su, Shin-Yi; Chao, Chi Kuang; Lee, Jae-Jin

    2008-09-01

    While the ion and electron temperatures inside equatorial plasma bubbles (EPBs) are normally lower than those in an ambient plasma, bubbles with enhanced temperatures (BETs) are found occasionally in the topside ionosphere. Here we report the characteristics of BETs identified from observations of the first Republic of China Satellite (ROCSAT-1), the first Korea Multi-purpose Satellite (KOMPSAT-1), and the Defense Meteorological Satellite Program (DMSP) F15 during the solar maximum period between 2000 and 2001. The oxygen ion fraction inside the BETs, which was no lower than that of the ambient ionosphere, was similar to the case of ordinary low-temperature EPBs. These observations indicate that the BETs and low-temperature EPBs detected on the topside were produced by the upward drift of low-density plasma from lower altitudes. The feature that distinguishes BETs from normal EPBs is the occurrence of an unusually fast poleward field-aligned plasma flow relative to the ambient plasma. The BETs occurred preferentially around geomagnetic latitudes of 10° in the summer hemisphere, where the ambient ion and electron temperatures are lower than those in the conjugate winter hemisphere. The occurrence of BETs did not show any notable dependence on geomagnetic activities. The characteristics of the BETs suggest that the BETs were produced by adiabatic plasma heating associated with a fast poleward oxygen ion transport along magnetic flux tubes.

  19. Plasma density enhancement at the Comet Halley diamagnetic cavity boundary

    NASA Technical Reports Server (NTRS)

    Keller, C. N.; Cravens, T. E.

    1990-01-01

    A one-dimensional single-fluid MHD model was used by Cravens (1989) to predict the existence of a narrow (50 km) layer of enhanced plasma density at the boundary of the Comet Halley diamagnetic cavity. The existence of such a layer was confirmed by measurements made by the Giotto ion mass spectrometer (Goldstein et al., 1989). Here, the time-dependent coupled continuity equations are solved for several species including H3O(+), H2O(+), OH(+), O(+), NH4(+), NH3(+), CH4(+), and CH3(+). For several ion species, factors affecting the magnitude of this enhancement and its relationship to the thickness of the transition layer are investigated. For example, ion species with short chemical lifetimes are shown to have smaller density enhancements than species with longer lifetimes. The cometocentric distance of the cavity boundary also strongly affects the magnitude of the density enhancement; the enhancement increases with increasing distance.

  20. Elemental abundances of flaring solar plasma - Enhanced neon and sulfur

    NASA Technical Reports Server (NTRS)

    Schmelz, J. T.

    1993-01-01

    Elemental abundances of two flares observed with the SMM Flat Crystal Spectrometer are compared and contrasted. The first had a gradual rise and a slow decay, while the second was much more impulsive. Simultaneous spectra of seven bright soft X-ray resonance lines provide information over a broad temperature range and are available throughout both flares, making these events unique in the SMM data base. For the first flare, the plasma seemed to be characterized by coronal abundances but, for the second, the plasma composition could not be coronal, photospheric, or a linear combination of both. A good differential emission measure fit required enhanced neon such that Ne/O = 0.32 +/- 0.02, a value which is inconsistent with the current models of coronal abundances based on the elemental first-ionization potential. Similar values of enhanced neon are found for flaring plasma observed by the SMM gamma-ray spectrometer, in (He-3)-rich solar energetic particle events, and in the decay phase of several long duration soft X-ray events. Sulfur is also enhanced in the impulsive flare, but not as dramatically as neon. These events are compared with two models which attempt to explain the enhanced values of neon and sulfur.

  1. Radio frequency plasma power dependence of the moisture permeation barrier characteristics of Al{sub 2}O{sub 3} films deposited by remote plasma atomic layer deposition

    SciTech Connect

    Jung, Hyunsoo; Choi, Hagyoung; Lee, Sanghun; Jeon, Heeyoung; Jeon, Hyeongtag

    2013-11-07

    In the present study, we investigated the gas and moisture permeation barrier properties of Al{sub 2}O{sub 3} films deposited on polyethersulfone films (PES) by capacitively coupled plasma (CCP) type Remote Plasma Atomic Layer Deposition (RPALD) at Radio Frequency (RF) plasma powers ranging from 100 W to 400 W in 100 W increments using Trimethylaluminum [TMA, Al(CH{sub 3}){sub 3}] as the Al source and O{sub 2} plasma as the reactant. To study the gas and moisture permeation barrier properties of 100-nm-thick Al{sub 2}O{sub 3} at various plasma powers, the Water Vapor Transmission Rate (WVTR) was measured using an electrical Ca degradation test. WVTR decreased as plasma power increased with WVTR values for 400 W and 100 W of 2.6 × 10{sup −4} gm{sup −2}day{sup −1} and 1.2 × 10{sup −3} gm{sup −2}day{sup −1}, respectively. The trends for life time, Al-O and O-H bond, density, and stoichiometry were similar to that of WVTR with improvement associated with increasing plasma power. Further, among plasma power ranging from 100 W to 400 W, the highest power of 400 W resulted in the best moisture permeation barrier properties. This result was attributed to differences in volume and amount of ion and radical fluxes, to join the ALD process, generated by O{sub 2} plasma as the plasma power changed during ALD process, which was determined using a plasma diagnosis technique called the Floating Harmonic Method (FHM). Plasma diagnosis by FHM revealed an increase in ion flux with increasing plasma power. With respect to the ALD process, our results indicated that higher plasma power generated increased ion and radical flux compared with lower plasma power. Thus, a higher plasma power provides the best gas and moisture permeation barrier properties.

  2. Enhancing Cold Atmospheric Plasma Treatment Efficiency for Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Cheng, Xiaoqian

    To improve efficiency and safety of anti-cancer therapies the researchers and clinicians alike are prompted to develop targeted combined therapies that especially minimize damage to healthy tissues while eradicating the body of cancerous tissues. Previous research in cold atmospheric plasma (CAP) and cancer cell interaction has repeatedly proven that cold plasma induced cell death. In this study, we seek to integrate the medical application of CAP. We proposed and implemented 3 novel ideas to enhance efficacy and selectivity of cancer therapy. It is postulated that the reactive oxygen species (ROS) and reactive nitrogen species (RNS) play a major role in the CAP cancer therapy. We determined a mechanism of CAP therapy on glioblastoma cells (U87) through an understanding of the composition of CAP, including output voltage, treatment time, and gas flow-rate. We varied the characteristics of the cold plasma in order to obtain different major species (such as O, OH, N2+, and N2 lines). "plasma dosage" D ~ Q * V * t. is defined, where D is the entire "plasma dosage"; Q is the flow rate of feeding gas; V is output voltage; t is treatment time. The proper CAP dosage caused 3-fold cell death in the U87 cells compared to the normal human astrocytes E6/E7 cells. We demonstrated there is a synergy between AuNPS and CAP in cancer therapy. Specifically, the concentration of AuNPs plays an important role on plasma therapy. At an optimal concentration, gold nanoparticles can significantly induce U87 cell death up to a 30% overall increase compared to the control group with the same plasma dosage but no AuNPs applied. The ROS intensity of the corresponding conditions has a reversed trend compared to cell viability. This matches with the theory that intracellular ROS accumulation results in oxidative stress, which further changes the intracellular pathways, causing damage to the proteins, lipids and DNA. Our results show that this synergy has great potential in improving the

  3. High-density formation of Ta nanodot induced by remote hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Wang, Yaping; Takeuchi, Daichi; Ohta, Akio; Ikeda, Mitsuhisa; Makihara, Katsunori; Miyazaki, Seiichi

    2017-01-01

    We have studied the formation of Ta nanodots (NDs) on thermally grown SiO2/Si by exposing a thin metal layer to a remote H2 plasma (H2-RP) without external heating. Atomic force microscopy (AFM) analyses show that a combination of a Ge (˜30.0 nm)/Ta (˜2.0 nm) bilayer stack with subsequent H2-RP exposure is effective for forming electrically isolated Ta NDs with an areal dot density as high as ˜1011 cm-2, where the Ge layer plays an important role as a barrier layer against the oxidation of the ultrathin Ta layer surface. The change in the chemical structure of the Ge/Ta bilayer stack on SiO2/Si upon Ta ND formation by H2-RP exposure is investigated by hard X-ray photoemission spectroscopy (HAXPES) and X-ray photoelectron spectroscopy (XPS).

  4. Plasma induced by resonance enhanced multiphoton ionization in inert gas

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2007-12-15

    We present a detailed model for the evolution of resonance enhanced multiphoton ionization (REMPI) produced plasma during and after the ionizing laser pulse in inert gas (argon, as an example) at arbitrary pressures. Our theory includes the complete process of the REMPI plasma generation and losses, together with the changing gas thermodynamic parameters. The model shows that the plasma expansion follows a classical ambipolar diffusion and that gas heating results in a weak shock or acoustic wave. The gas becomes involved in the motion not only from the pressure gradient due to the heating, but also from the momentum transfer from the charged particles to gas atoms. The time dependence of the total number of electrons computed in theory matches closely with the results of coherent microwave scattering experiments.

  5. Enhancement of pulverized coal combustion by plasma technology

    SciTech Connect

    Gorokhovski, M.A.; Jankoski, Z.; Lockwood, F.C.; Karpenko, E.I.; Messerle, V.E.; Ustimenko, A.B.

    2007-07-01

    Plasma-assisted pulverized coal combustion is a promising technology for thermal power plants (TPP). This article reports one- and three- dimensional numerical simulations, as well as laboratory and industrial measurements of coal combustion using a plasma-fuel system (PFS). The chemical kinetic and fluid mechanics involved in this technology are analysed. The results show that a PFS, can be used to promote early ignition and enhanced stabilization of a pulverized coal flame. It is shown that this technology, in addition to enhancing the combustion efficiency of the flame, reduces harmful emissions from power coals of all ranks (brown, bituminous, anthracite and their mixtures). Data summarising the experience of 27 pulverized coal boilers in 16 thermal power plants in several countries (Russia, Kazakhstan, Korea, Ukraine, Slovakia, Mongolia and China), embracing steam productivities from 75 to 670 tons per hour (TPH), are presented. Finally, the practical computation of the characteristics of the PFS, as function of coal properties, is discussed.

  6. Plasma enhanced atomic layer deposition of silicon nitride using neopentasilane

    SciTech Connect

    Weeks, Stephen Nowling, Greg; Fuchigami, Nobi; Bowes, Michael; Littau, Karl

    2016-01-15

    Progress in transistor scaling has increased the demands on the material properties of silicon nitride (SiN{sub x}) thin films used in device fabrication and at the same time placed stringent restrictions on the deposition conditions employed. Recently, low temperature plasma enhanced atomic layer deposition has emerged as a viable technique for depositing these films with a thermal budget compatible with semiconductor processing at sub-32 nm technology nodes. For these depositions, it is desirable to use precursors that are free from carbon and halogens that can incorporate into the film. Beyond this, it is necessary to develop processing schemes that minimize the wet etch rate of the film as it will be subjected to wet chemical processing in subsequent fabrication steps. In this work, the authors introduce low temperature deposition of SiN{sub x} using neopentasilane [NPS, (SiH{sub 3}){sub 4}Si] in a plasma enhanced atomic layer deposition process with a direct N{sub 2} plasma. The growth with NPS is compared to a more common precursor, trisilylamine [TSA, (SiH{sub 3}){sub 3 }N] at identical process conditions. The wet etch rates of the films deposited with NPS are characterized at different plasma conditions and the impact of ion energy is discussed.

  7. Plasma-enhanced chemical vapor deposition of tungsten films

    NASA Astrophysics Data System (ADS)

    Chu, J. K.; Tang, C. C.; Hess, D. W.

    1982-07-01

    High-purity films of tungsten are deposited from tungsten hexafluoride and hydrogen using plasma-enhanced deposition (PED). At 400 °C deposition temperature, resistivities of ˜40 μΩ cm are attained. After annealing at 1100 °C, the resistivity falls to ˜7 μΩ cm. Below 400 °C, the as-deposited film stress is <6×109 dynes/cm2. Tensile, unlike tungsten, molybdenum films deposited by PED displayed high resistivities.

  8. Enhanced chromium adsorption capacity via plasma modification of natural zeolites

    NASA Astrophysics Data System (ADS)

    Cagomoc, Charisse Marie D.; Vasquez, Magdaleno R., Jr.

    2017-01-01

    Natural zeolites such as mordenite are excellent adsorbents for heavy metals. To enhance the adsorption capacity of zeolite, sodium-exchanged samples were irradiated with 13.56 MHz capacitively coupled radio frequency (RF) argon gas discharge. Hexavalent chromium [Cr(VI)] was used as the test heavy metal. Pristine and plasma-treated zeolite samples were soaked in 50 mg/L Cr solution and the amount of adsorbed Cr(VI) on the zeolites was calculated at predetermined time intervals. Compared with untreated zeolite samples, initial Cr(VI) uptake was 70% higher for plasma-treated zeolite granules (50 W 30 min) after 1 h of soaking. After 24 h, all plasma-treated zeolites showed increased Cr(VI) uptake. For a 2- to 4-month period, Cr(VI) uptake increased about 130% compared with untreated zeolite granules. X-ray diffraction analyses between untreated and treated zeolite samples revealed no major difference in terms of its crystal structure. However, for plasma-treated samples, an increase in the number of surface defects was observed from scanning electron microscopy images. This increase in the number of surface defects induced by plasma exposure played a crucial role in increasing the number of active sorption sites on the zeolite surface.

  9. Combustion Enhancement Using a Silent Discharge Plasma Reactor

    NASA Astrophysics Data System (ADS)

    Rosocha, Louis; Platts, David; Coates, Don; Stange, Sy

    2003-10-01

    Electric fields affect flame propagation speed, stability, and combustion chemistry. External electrodes, arc discharges, and plasma jets have been used to combust gas mixtures outside their flammability limits. Experiments with silent electrical discharges (SEDs) and propagating flames have shown that flame propagation velocity is actually decreased (combustion retarded) when an SED is applied directly to the flame region, but velocity is increased (combustion promoted) when applied to the unburned gas mixture upstream of a flame. More recent work has proposed electric arc/microwave-driven plasma-generating fuel nozzles to produce dissociated fuel or ionized fuel for aircraft gas turbine engine combustor mixers. In contrast to prior works, we have used a silent discharge plasma (SDP) reactor to break up large fuel molecules into smaller molecules and create free radicals/active species in a gas stream before the fuel is mixed with an oxidizer and combusted. A cylindrical SDP reactor was used to 'activate' propane before mixing it with air and igniting the combustible gas mixture. With the plasma, the physical appearance of the flame changes and substantial changes in mass spectrometer fragmentation peaks for fuel and combustion products are observed (i.e., combustion is enhanced). Results of changes in the degree of combustion will be discussed in terms of variations in the plasma specific energy.

  10. Front surface structured targets for enhancing laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Snyder, Joseph; George, Kevin; Ji, Liangliang; Yalamanchili, Sasir; Simonoff, Ethan; Cochran, Ginevra; Daskalova, Rebecca; Poole, Patrick; Willis, Christopher; Lewis, Nathan; Schumacher, Douglass

    2016-10-01

    We present recent progress made using front surface structured interfaces for enhancing ultrashort, relativistic laser-plasma interactions. Structured targets can increase laser absorption and enhance ion acceleration through a number of mechanisms such as direct laser acceleration and laser guiding. We detail experimental results obtained at the Scarlet laser facility on hollow, micron-scale plasma channels for enhancing electron acceleration. These targets show a greater than three times enhancement in the electron cutoff energy as well as an increased slope temperature for the electron distribution when compared to a flat interface. Using three-dimensional particle-in-cell (PIC) simulations, we have modeled the interaction to give insight into the physical processes responsible for the enhancement. Furthermore, we have used PIC simulations to design structures that are more advantageous for ion acceleration. Such targets necessitate advanced target fabrication methods and we describe techniques used to manufacture optimized structures, including vapor-liquid-solid growth, cryogenic etching, and 3D printing using two-photon-polymerization. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-14-1-0085.

  11. Observations of Low-Latitude Plasma Density Enhancements and their Associated Plasma Drifts

    NASA Technical Reports Server (NTRS)

    Klenzing, J. H.; Rowland, D. E.; Pfaff, R. F.; Le, G.; Freudenreich, H.; Haaser, R. A.; Burrell, A. G.; Stoneback, R. A.; Coley, W. R.; Heelis, R. A.

    2011-01-01

    Plasma density structures are frequently encountered in the nighttime low-latitude ionosphere by probes on the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. Of particular interest to us here are plasma density enhancements, which are typically observed +/- 15 deg away from the magnetic equator. The low inclination of the C/NOFS satellite offers an unprecedented opportunity to examine these structures and their associated electric fields and plasma velocities, including their field-aligned components, along an east-west trajectory. Among other observations, the data reveal a clear asymmetry in the velocity structure within and around these density enhancements. Previous observations have shown that the peak change in drift velocity associated with a density enhancement occurs simultaneously both perpendicular and parallel to the magnetic field, while the 1results in this paper show that the peak change in parallel fl ow typically occurs 25-100 km to the east of the peak perpendicular ow. We discuss this and other aspects of the observations in relation to the characteristics of the plasma depletions formed near the magnetic equator detected by the same probes on the C/NOFS satellite and to previous observations and theories.

  12. Exploring the Human Plasma Proteome for Humoral Mediators of Remote Ischemic Preconditioning - A Word of Caution

    PubMed Central

    Helgeland, Erik; Breivik, Lars Ertesvåg; Vaudel, Marc; Svendsen, Øyvind Sverre; Garberg, Hilde; Nordrehaug, Jan Erik; Berven, Frode Steingrimsen; Jonassen, Anne Kristine

    2014-01-01

    Despite major advances in early revascularization techniques, cardiovascular diseases are still the leading cause of death worldwide, and myocardial infarctions contribute heavily to this. Over the past decades, it has become apparent that reperfusion of blood to a previously ischemic area of the heart causes damage in and of itself, and that this ischemia reperfusion induced injury can be reduced by up to 50% by mechanical manipulation of the blood flow to the heart. The recent discovery of remote ischemic preconditioning (RIPC) provides a non-invasive approach of inducing this cardioprotection at a distance. Finding its endogenous mediators and their operative mode is an important step toward increasing the ischemic tolerance. The release of humoral factor(s) upon RIPC was recently demonstrated and several candidate proteins were published as possible mediators of the cardioprotection. Before clinical applicability, these potential biomarkers and their efficiency must be validated, a task made challenging by the large heterogeneity in reported data and results. Here, in an attempt to reproduce and provide more experimental data on these mediators, we conducted an unbiased in-depth analysis of the human plasma proteome before and after RIPC. From the 68 protein markers reported in the literature, only 28 could be mapped to manually reviewed (Swiss-Prot) protein sequences. 23 of them were monitored in our untargeted experiment. However, their significant regulation could not be reproducibly estimated. In fact, among the 394 plasma proteins we accurately quantified, no significant regulation could be confidently and reproducibly assessed. This indicates that it is difficult to both monitor and reproduce published data from experiments exploring for RIPC induced plasma proteomic regulations, and suggests that further work should be directed towards small humoral factors. To simplify this task, we made our proteomic dataset available via ProteomeXchange, where

  13. Integrated computer-enhanced remote viewing system. Quarterly report No. 2, January--March 1993

    SciTech Connect

    Not Available

    1993-05-03

    The Interactive, Computer-Enhanced, Remote Viewing System (ICERVS) is a system designed to provide a reliable geometric description of a robotic task space in a fashion that enables robotic remediation to be carried out more efficiently and economically than with present systems. The key elements are a faithful way to store empirical data and a friendly user interface that provides an operator with timely access to all that is known about a scene.

  14. Enhanced plasma current collection from weakly conducting solar array blankets

    NASA Technical Reports Server (NTRS)

    Hillard, G. Barry

    1993-01-01

    Among the solar cell technologies to be tested in space as part of the Solar Array Module Plasma Interactions Experiment (SAMPIE) will be the Advanced Photovoltaic Solar Array (APSA). Several prototype twelve cell coupons were built for NASA using different blanket materials and mounting techniques. The first conforms to the baseline design for APSA which calls for the cells to be mounted on a carbon loaded Kapton blanket to control charging in GEO. When deployed, this design has a flexible blanket supported around the edges. A second coupon was built with the cells mounted on Kapton-H, which was in turn cemented to a solid aluminum substrate. A final coupon was identical to the latter but used germanium coated Kapton to control atomic oxygen attack in LEO. Ground testing of these coupons in a plasma chamber showed considerable differences in plasma current collection. The Kapton-H coupon demonstrated current collection consistent with exposed interconnects and some degree of cell snapover. The other two coupons experienced anomalously large collection currents. This behavior is believed to be a consequence of enhanced plasma sheaths supported by the weakly conducting carbon and germanium used in these coupons. The results reported here are the first experimental evidence that the use of such materials can result in power losses to high voltage space power systems.

  15. Silver-enhanced radial immunodiffusion assay of plasma apolipoproteins.

    PubMed

    Ishida, B Y; Paigen, B

    1992-07-01

    Silver-staining of immunoprecipitates extends the sensitivity of the radial immunodiffusion assay by tenfold. This modification permits the quantification of apolipoproteins A-I, A-II, C, and E at levels of 0.2-1.0 mg/dl in plasma samples at a sensitivity threshold of 10 ng. The silver-enhanced radial immunodiffusion method is readily adapted from the standard method, simple and inexpensive to perform, and does not require costly instrumentation. These advantages make the modified RID assay an attractive alternative to other forms of immunoassay.

  16. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers

    NASA Technical Reports Server (NTRS)

    Matthews, Kristopher; Cruden, Brett A.; Chen, Bin; Meyyappan, M.; Delzeit, Lance

    2002-01-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  17. Enhancing the Teaching of Digital Processing of Remote Sensing Image Course through Geospatial Web Processing Services

    NASA Astrophysics Data System (ADS)

    di, L.; Deng, M.

    2010-12-01

    Remote sensing (RS) is an essential method to collect data for Earth science research. Huge amount of remote sensing data, most of them in the image form, have been acquired. Almost all geography departments in the world offer courses in digital processing of remote sensing images. Such courses place emphasis on how to digitally process large amount of multi-source images for solving real world problems. However, due to the diversity and complexity of RS images and the shortcomings of current data and processing infrastructure, obstacles for effectively teaching such courses still remain. The major obstacles include 1) difficulties in finding, accessing, integrating and using massive RS images by students and educators, and 2) inadequate processing functions and computing facilities for students to freely explore the massive data. Recent development in geospatial Web processing service systems, which make massive data, computing powers, and processing capabilities to average Internet users anywhere in the world, promises the removal of the obstacles. The GeoBrain system developed by CSISS is an example of such systems. All functions available in GRASS Open Source GIS have been implemented as Web services in GeoBrain. Petabytes of remote sensing images in NASA data centers, the USGS Landsat data archive, and NOAA CLASS are accessible transparently and processable through GeoBrain. The GeoBrain system is operated on a high performance cluster server with large disk storage and fast Internet connection. All GeoBrain capabilities can be accessed by any Internet-connected Web browser. Dozens of universities have used GeoBrain as an ideal platform to support data-intensive remote sensing education. This presentation gives a specific example of using GeoBrain geoprocessing services to enhance the teaching of GGS 588, Digital Remote Sensing taught at the Department of Geography and Geoinformation Science, George Mason University. The course uses the textbook "Introductory

  18. Tungsten Deposition on Graphite using Plasma Enhanced Chemical Vapour Deposition.

    NASA Astrophysics Data System (ADS)

    Sharma, Uttam; Chauhan, Sachin S.; Sharma, Jayshree; Sanyasi, A. K.; Ghosh, J.; Choudhary, K. K.; Ghosh, S. K.

    2016-10-01

    The tokamak concept is the frontrunner for achieving controlled thermonuclear reaction on earth, an environment friendly way to solve future energy crisis. Although much progress has been made in controlling the heated fusion plasmas (temperature ∼ 150 million degrees) in tokamaks, technological issues related to plasma wall interaction topic still need focused attention. In future, reactor grade tokamak operational scenarios, the reactor wall and target plates are expected to experience a heat load of 10 MW/m2 and even more during the unfortunate events of ELM's and disruptions. Tungsten remains a suitable choice for the wall and target plates. It can withstand high temperatures, its ductile to brittle temperature is fairly low and it has low sputtering yield and low fuel retention capabilities. However, it is difficult to machine tungsten and hence usages of tungsten coated surfaces are mostly desirable. To produce tungsten coated graphite tiles for the above-mentioned purpose, a coating reactor has been designed, developed and made operational at the SVITS, Indore. Tungsten coating on graphite has been attempted and successfully carried out by using radio frequency induced plasma enhanced chemical vapour deposition (rf -PECVD) for the first time in India. Tungsten hexa-fluoride has been used as a pre-cursor gas. Energy Dispersive X-ray spectroscopy (EDS) clearly showed the presence of tungsten coating on the graphite samples. This paper presents the details of successful operation and achievement of tungsten coating in the reactor at SVITS.

  19. Carbon Nanotubes/Nanofibers by Plasma Enhanced Chemical Vapour Deposition

    NASA Technical Reports Server (NTRS)

    Teo, K. B. K.; Hash, D. B.; Bell, M. S.; Chhowalla, M.; Cruden, B. A.; Amaratunga, G. A. J.; Meyyappan, M.; Milne, W. I.

    2005-01-01

    Plasma enhanced chemical vapour deposition (PECVD) has been recently used for the production of vertically aligned carbon nanotubedfibers (CN) directly on substrates. These structures are potentially important technologically as electron field emitters (e.g. microguns, microwave amplifiers, displays), nanoelectrodes for sensors, filter media, superhydrophobic surfaces and thermal interface materials for microelectronics. A parametric study on the growth of CN grown by glow discharge dc-PECVD is presented. In this technique, a substrate containing thin film Ni catalyst is exposed to C2H2 and NH3 gases at 700 C. Without plasma, this process is essentially thermal CVD which produces curly spaghetti-like CN as seen in Fig. 1 (a). With the plasma generated by biasing the substrate at -6OOV, we observed that the CN align vertically during growth as shown in Fig. l(b), and that the magnitude of the applied substrate bias affects the degree of alignment. The thickness of the thin film Ni catalyst was found to determine the average diameter and inversely the length of the CN. The yield and density of the CN were controlled by the use of different diffusion barrier materials under the Ni catalyst. Patterned CN growth [Fig. l(c)], with la variation in CN diameter of 4.1% and 6.3% respectively, is achieved by lithographically defining the Ni thin film prior to growth. The shape of the structures could be varied from very straight nanotube-like to conical tip-like nanofibers by increasing the ratio of C2H2 in the gas flow. Due to the plasma decomposition of C2H2, amorphous carbon (a-C) is an undesirable byproduct which could coat the substrate during CN growth. Using a combination of depth profiled Auger electron spectroscopy to study the substrate and in-situ mass spectroscopy to examine gas phase neutrals and ions, the optimal conditions for a-C free growth of CN is determined.

  20. Novel atmospheric plasma enhanced chitosan nanofiber/gauze composite wound dressings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electrospun chitosan nanofibers were deposited onto atmospheric plasma treated cotton gauze to create a novel composite bandage with higher adhesion, better handling properties, enhanced bioactivity, and moisture management. Plasma treatment of the gauze substrate was performed to improve the durabi...

  1. Enhanced remote earthquake triggering at fluid injection sites in the Midwestern U.S

    NASA Astrophysics Data System (ADS)

    van der Elst, N.; Savage, H. M.; Keranen, K. M.; Abers, G. A.

    2013-12-01

    A dramatic increase in seismicity in the Midwestern United States may be related to increased deep wastewater injection. We systematically examined sites of potential anthropogenic seismicity for evidence of remote earthquake triggering, which could indicate high fluid pressure and critically stressed faults. Using a cross-correlation method to enhance earthquake catalogs for individual TA stations, we found that regions of anthropogenic seismicity are also susceptible to earthquake triggering from natural transient stresses carried by seismic waves of large remote earthquakes. We detected triggered earthquakes following the three largest dynamic strain events since 2010, showing triggering by the 2010 Mw 8.8 Maule, Chile, earthquake at Prague, OK, and Trinidad, CO, and triggering by the 2011 Mw 9.1 Tohoku-Oki earthquake at Snyder, TX. Each of these sites hosted larger earthquakes (Mw 4.5-5.7) within the next 6 to 20 months. Enhanced triggering susceptibility could therefore be an advance indicator that fluid injection has brought the regional fault system to a critical state. Remote triggering is strongest at sites where the onset of seismicity lagged injection by many years, and where high swarm activity had not yet begun. The sites that triggered during the 2010 Chile earthquake did not trigger in the subsequent 2011 Tohoku earthquake, which suggests the importance of local conditions or a long recharge period for the triggering mechanism. By analogy with natural dynamic triggering at hydrothermal sites, we invoke a mechanism involving fracture unclogging or dynamic permeability enhancement, in which the seismic waves alter subsurface fluid flow and accelerate pressure changes on already critically stressed faults.

  2. Remote excitation-tip-enhanced Raman scattering microscopy using silver nanowire

    NASA Astrophysics Data System (ADS)

    Fujita, Yasuhiko; Walke, Peter; De Feyter, Steven; Uji-i, Hiroshi

    2016-08-01

    Tip-enhanced Raman scattering (TERS) microscopy is a promising technique for use in surface analysis, allowing both topographic and spectroscopic information to be obtained simultaneously at a scale below 10 nm. One proposed method to further improve spatial resolution is the use of propagating surface plasmons as an excitation light source (i.e., remote excitation). However, this requires a specialized tip that can only be fabricated via expensive procedures, such as electron-beam lithography. Here, we propose a new method for fabricating silver nanowire-based tips that are suitable for remote excitation-TERS, removing the need for such techniques. A silver nanowire was fixed onto a tungsten-tip using a micromanipulator, before gold nanoparticles were attached in a site-specific manner using AC-dielectrophoresis. All the processes were completed using an optical microscope in the ambient. The background intensities in TERS spectra were suppressed with remote excitation relative to the conventional excitation configuration, indicating an increase in TERS sensitivity.

  3. Interactive Computer-Enhanced Remote Viewing System (ICERVS): Final report, November 1994--September 1996

    SciTech Connect

    1997-05-01

    The Interactive Computer-Enhanced Remote Viewing System (ICERVS) is a software tool for complex three-dimensional (3-D) visualization and modeling. Its primary purpose is to facilitate the use of robotic and telerobotic systems in remote and/or hazardous environments, where spatial information is provided by 3-D mapping sensors. ICERVS provides a robust, interactive system for viewing sensor data in 3-D and combines this with interactive geometric modeling capabilities that allow an operator to construct CAD models to match the remote environment. Part I of this report traces the development of ICERVS through three evolutionary phases: (1) development of first-generation software to render orthogonal view displays and wireframe models; (2) expansion of this software to include interactive viewpoint control, surface-shaded graphics, material (scalar and nonscalar) property data, cut/slice planes, color and visibility mapping, and generalized object models; (3) demonstration of ICERVS as a tool for the remediation of underground storage tanks (USTs) and the dismantlement of contaminated processing facilities. Part II of this report details the software design of ICERVS, with particular emphasis on its object-oriented architecture and user interface.

  4. 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

  5. Resonant enhancement for amplitude-modulated laser filament induced magnetic field in an inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Annou, R.; Tripathi, V. K.; Srivastava, M. P.

    1996-09-01

    The Tripathi-Liu [Phys. Plasmas 1, 990 (1994)] model of magnetic-field generation due to an amplitude-modulated laser in a plasma is revisited. At plasma resonance, where modulation frequency equals the plasma frequency, significant enhancement in the magnetic field is seen. The magnetic field is found to scale directly with laser intensity and plasma frequency, while scaling inversely with laser spot size.

  6. A new perspective on remote Saddle Sine and Cosine coils technique for determination of tokamak plasma equilibrium status

    NASA Astrophysics Data System (ADS)

    Salar Elahi, A.; Ghoranneviss, M.

    In this contribution we have presented a new perspective for determination of tokamak plasma column shift based on remote multipole moments technique. First, we presented analytical details for using this technique. Then principle of different models based on this technique for design and fabrication of a six coils will be presented: four modified Rogowski coil (two Cosine coils and two Sine coils) and two Saddle coils (Saddle Sine coil (SSC) and Saddle Cosine coil (SCC)). Also, in order to comparison of results the flux loops technique is used. Because of continuous measurements of magnetic field distribution around the tokamak plasma using multipole coils, this technique give us more reliable information about the plasma current displacement.

  7. GPs with enhanced surgical skills: a questionable solution for remote surgical services

    PubMed Central

    Vinden, Christopher; Ott, Michael C.

    2015-01-01

    Summary The Canadian College of Family Physicians recently decided to recognize family physicians with enhanced surgical skills (ESS) and has proposed a 1-year curriculum of surgical training. The purpose of this initiative is to bring or enhance surgical services to remote and underserviced areas. We feel that this proposed curriculum is overly ambitious and unrealistic and that it is unlikely to produce surgeons, or a system, capable of delivering high-quality surgical services. The convergence of a new training curriculum for general surgeons, coupled with the current oversupply of surgeons, provide an alternate pathway to meet the needs of these communities. A long-term solution will also require alternate funding models, a sophisticated and coordinated national locum service and a national review of the population and infrastructure requirements necessary for both sustainable resident surgical services and surgical outreach services. PMID:26574827

  8. Plasma Enhanced Growth of Carbon Nanotubes For Ultrasensitive Biosensors

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Li, J.; Ye, Q.; Koehne, J.; Chen, H.; Meyyappan, M.

    2004-01-01

    The multitude of considerations facing nanostructure growth and integration lends itself to combinatorial optimization approaches. Rapid optimization becomes even more important with wafer-scale growth and integration processes. Here we discuss methodology for developing plasma enhanced CVD growth techniques for achieving individual, vertically aligned carbon nanostructures that show excellent properties as ultrasensitive electrodes for nucleic acid detection. We utilize high throughput strategies for optimizing the upstream and downstream processing and integration of carbon nanotube electrodes as functional elements in various device types. An overview of ultrasensitive carbon nanotube based sensor arrays for electrochemical biosensing applications and the high throughput methodology utilized to combine novel electrode technology with conventional MEMS processing will be presented.

  9. Plasma Enhanced Growth of Carbon Nanotubes For Ultrasensitive Biosensors

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Meyyappan, M.

    2004-01-01

    The multitude of considerations facing nanostructure growth and integration lends itself to combinatorial optimization approaches. Rapid optimization becomes even more important with wafer-scale growth and integration processes. Here we discuss methodology for developing plasma enhanced CVD growth techniques for achieving individual, vertically aligned carbon nanostructures that show excellent properties as ultrasensitive electrodes for nucleic acid detection. We utilize high throughput strategies for optimizing the upstream and downstream processing and integration of carbon nanotube electrodes as functional elements in various device types. An overview of ultrasensitive carbon nanotube based sensor arrays for electrochemical bio-sensing applications and the high throughput methodology utilized to combine novel electrode technology with conventional MEMS processing will be presented.

  10. A phagocytosis-enhancing factor in human plasma.

    PubMed Central

    Gigli, I; Wintroub, B U; Goetzl, E J

    1976-01-01

    A phagocytosis-enhancing factor (PEF) with the capacity to stimulate the ingestion of sensitized sheep erythrocytes by human polymorphonuclear and mononuclear leucocytes has been isolated from human plasma by chromatography on DEAE-cellulose and filtration on Sephadex G-150 and Sephadex G-100. PEF is a protein of approximately 70,000 molecular weight which is susceptible to inactivation by heating at 60 degrees or by tryptic digestion. PEF promotes phagocytosis of erythrocytes sensitized with intact 7S antibody or bearing the C3b complement fragment, but not of unsensitized erythrocytes or erythrocytes sensitized with 19S antibody. The specificity of PEF interaction with target erythrocytes and the persistence of its stimulatory effect after the target cells are washed suggest that it promotes phagocytosis by an action on the erythrocytes. PMID:1027715

  11. Mercury's Plasma Mantle during Solar Wind Dynamical Pressure Enhancements

    NASA Astrophysics Data System (ADS)

    Delcourt, D.; Seki, K.; Terada, N.; Moore, T. E.

    2014-12-01

    Because of the weak planetary magnetic field as well as proximity to the Sun, the magnetosphere of Mercury is very dynamical and at times subjected to prominent compression. Recent observations from MESSENGER reveal that during events of enhanced solar wind dynamical pressure, the subsolar magnetopause may actually be pushed until the immediate vicinity of the planet surface. Using three-dimensional single-particle simulations, we examine the dynamics of solar wind originating protons during such events. We show that these impulsive events can lead to substantial (several hundreds of eVs or a few keVs) H+ energization in the plasma mantle. Unlike ions with large mass-to-charge ratios (e.g., Na+ of planetary origin), H+ are transported adiabatically during these events, their energization being due to the ExB convection surge. MESSENGER observations of the plasma mantle show repeated evidences of such a transient H+ energization which may follow from the variable character of Mercury's magnetosphere.

  12. Plasma enhanced metalorganic chemical vapor deposition of amorphous aluminum nitride

    NASA Astrophysics Data System (ADS)

    Harris, H.; Biswas, N.; Temkin, H.; Gangopadhyay, S.; Strathman, M.

    2001-12-01

    Plasma enhanced deposition of amorphous aluminum nitride (AlN) using trimethylaluminum, hydrogen, and nitrogen was performed in a capacitively coupled plasma system. Temperature was varied from 350 to 550 °C, and pressure dependence of the film structure was investigated. Films were characterized by Fourier transform infrared, Rutherford backscattering (RBS), ellipsometry, and x-ray diffraction (XRD). The films are amorphous in nature, as indicated by XRD. Variations in the refractive index were observed in ellipsometric measurements, which is explained by the incorporation of carbon in the films, and confirmed by RBS. Capacitance-voltage, conductance-voltage (G-V), and current-voltage measurements were performed to reveal bulk and interface electrical properties. The electrical properties showed marked dependence on processing conditions of the AlN films. Clear peaks as observed in the G-V characteristics indicated that the losses are predominantly due to interface states. The interface state density ranged between 1010 and 1011eV-1 cm-2. Annealing in hydrogen resulted in lowering of interface state density values.

  13. Plasma-Sprayed Titanium Patterns for Enhancing Early Cell Responses

    NASA Astrophysics Data System (ADS)

    Shi, Yunqi; Xie, Youtao; Pan, Houhua; Zheng, Xuebin; Huang, Liping; Ji, Fang; Li, Kai

    2016-06-01

    Titanium coating has been widely used as a biocompatible metal in biomedical applications. However, the early cell responses and long-term fixation of titanium implants are not satisfied. To obviate these defects, in this paper, micro-post arrays with various widths (150-1000 μm) and intervals (100-300 μm) were fabricated on the titanium substrate by template-assisted plasma spraying technology. In vitro cell culture experiments showed that MC3T3-E1 cells exhibited significantly higher osteogenic differentiation as well as slightly improved adhesion and proliferation on the micro-patterned coatings compared with the traditional one. The cell number on the pattern with 1000 µm width reached 130% after 6 days of incubation, and the expressions of osteopontin (OPN) as well as osteocalcin (OC) were doubled. No obvious difference was found in cell adhesion on various size patterns. The present micro-patterned coatings proposed a new modification method for the traditional plasma spraying technology to enhance the early cell responses and convenience for the bone in-growth.

  14. Remote sensing image enhancement based on the combination of nonsubsampled shearlet transform and guided filtering

    NASA Astrophysics Data System (ADS)

    Lv, Duliang; Jia, Zhenhong; Yang, Jie; Kasabov, Nikola

    2016-10-01

    Aiming at the characteristics of remote sensing images with low-contrast, weak edge preservation, and poor resolution textual information, an image enhancement method that combines nonsubsampled shearlet transform (NSST) and guided filtering is presented. First, histogram equalization is applied to the remote sensing image. Second, the image is decomposed into a low frequency component and several high frequency components by NSST. Then, a linear stretch is adopted for the coefficients of the low-frequency component to improve the contrast of the original image; the threshold method is used to restrain the noise in the high-frequency components, then guided filtering is used for dealing with the high-frequency components, improving the detail information and edge-gradient retention ability. Finally, the final enhanced image is reconstructed by applying the inverse NSST to the processed low- and high-frequency components. The results show that the algorithm can significantly improve the visual impression of the image. Compared with the proposed algorithms in recent years, the average gradient and information entropy are significantly improved and the running time is shortened.

  15. Mechanism of Growth Enhancement of Plants Induced by Active Species in Plasmas

    NASA Astrophysics Data System (ADS)

    Watanabe, Satoshi; Ono, Reoto; Hayashi, Nobuya

    2015-09-01

    Plant growth enhances when seeds are irradiated by plasma. However the mechanism of the growth enhancement by plasma has not been clarified. In this study, growth enhancement of plants using various active species and variation of plant cells are investigated. RF plasma is generated under conditions where pressure is 60 Pa and input electrical power is 60 W. Irradiation period varies from 0 (control) to 75 min. Air plasma shows maximum growth of plants with irradiation period of 60 min on the other hand, oxygen plasma shows the maximum growth with irradiation period of 15 min. From change of gaseous species and pressure dependence, growth enhancing factor is expected to be active oxygen species produced in plasma. According to gene expression analysis of Arabidopsis, there are two speculated mechanism of plant growth enhancement. The first is acceleration of cell cycle by gene expressions of photosynthesis and glycolytic pathway, and the second is increase of cell size via plant hormone production.

  16. Hyperspectral Remote Sensing and Ecological Modeling Research and Education at Mid America Remote Sensing Center (MARC): Field and Laboratory Enhancement

    NASA Technical Reports Server (NTRS)

    Cetin, Haluk

    1999-01-01

    The purpose of this project was to establish a new hyperspectral remote sensing laboratory at the Mid-America Remote sensing Center (MARC), dedicated to in situ and laboratory measurements of environmental samples and to the manipulation, analysis, and storage of remotely sensed data for environmental monitoring and research in ecological modeling using hyperspectral remote sensing at MARC, one of three research facilities of the Center of Reservoir Research at Murray State University (MSU), a Kentucky Commonwealth Center of Excellence. The equipment purchased, a FieldSpec FR portable spectroradiometer and peripherals, and ENVI hyperspectral data processing software, allowed MARC to provide hands-on experience, education, and training for the students of the Department of Geosciences in quantitative remote sensing using hyperspectral data, Geographic Information System (GIS), digital image processing (DIP), computer, geological and geophysical mapping; to provide field support to the researchers and students collecting in situ and laboratory measurements of environmental data; to create a spectral library of the cover types and to establish a World Wide Web server to provide the spectral library to other academic, state and Federal institutions. Much of the research will soon be published in scientific journals. A World Wide Web page has been created at the web site of MARC. Results of this project are grouped in two categories, education and research accomplishments. The Principal Investigator (PI) modified remote sensing and DIP courses to introduce students to ii situ field spectra and laboratory remote sensing studies for environmental monitoring in the region by using the new equipment in the courses. The PI collected in situ measurements using the spectroradiometer for the ER-2 mission to Puerto Rico project for the Moderate Resolution Imaging Spectrometer (MODIS) Airborne Simulator (MAS). Currently MARC is mapping water quality in Kentucky Lake and

  17. Optimisation of amorphous zinc tin oxide thin film transistors by remote-plasma reactive sputtering

    NASA Astrophysics Data System (ADS)

    Niang, K. M.; Cho, J.; Heffernan, S.; Milne, W. I.; Flewitt, A. J.

    2016-08-01

    The influence of the stoichiometry of amorphous zinc tin oxide (a-ZTO) thin films used as the semiconducting channel in thin film transistors (TFTs) is investigated. A-ZTO has been deposited using remote-plasma reactive sputtering from zinc:tin metal alloy targets with 10%, 33%, and 50% Sn at. %. Optimisations of thin films are performed by varying the oxygen flow, which is used as the reactive gas. The structural, optical, and electrical properties are investigated for the optimised films, which, after a post-deposition annealing at 500 °C in air, are also incorporated as the channel layer in TFTs. The optical band gap of a-ZTO films slightly increases from 3.5 to 3.8 eV with increasing tin content, with an average transmission ˜90% in the visible range. The surface roughness and crystallographic properties of the films are very similar before and after annealing. An a-ZTO TFT produced from the 10% Sn target shows a threshold voltage of 8 V, a switching ratio of 108, a sub-threshold slope of 0.55 V dec-1, and a field effect mobility of 15 cm2 V-1 s-1, which is a sharp increase from 0.8 cm2 V-1 s-1 obtained in a reference ZnO TFT. For TFTs produced from the 33% Sn target, the mobility is further increased to 21 cm2 V-1 s-1, but the sub-threshold slope is slightly deteriorated to 0.65 V dec-1. For TFTs produced from the 50% Sn target, the devices can no longer be switched off (i.e., there is no channel depletion). The effect of tin content on the TFT electrical performance is explained in the light of preferential sputtering encountered in reactive sputtering, which resulted in films sputtered from 10% and 33% Sn to be stoichiometrically close to the common Zn2SnO4 and ZnSnO3 phases.

  18. Hydrogen desorption from hydrogen fluoride and remote hydrogen plasma cleaned silicon carbide (0001) surfaces

    SciTech Connect

    King, Sean W. Tanaka, Satoru; Davis, Robert F.; Nemanich, Robert J.

    2015-09-15

    Due to the extreme chemical inertness of silicon carbide (SiC), in-situ thermal desorption is commonly utilized as a means to remove surface contamination prior to initiating critical semiconductor processing steps such as epitaxy, gate dielectric formation, and contact metallization. In-situ thermal desorption and silicon sublimation has also recently become a popular method for epitaxial growth of mono and few layer graphene. Accordingly, numerous thermal desorption experiments of various processed silicon carbide surfaces have been performed, but have ignored the presence of hydrogen, which is ubiquitous throughout semiconductor processing. In this regard, the authors have performed a combined temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) investigation of the desorption of molecular hydrogen (H{sub 2}) and various other oxygen, carbon, and fluorine related species from ex-situ aqueous hydrogen fluoride (HF) and in-situ remote hydrogen plasma cleaned 6H-SiC (0001) surfaces. Using XPS, the authors observed that temperatures on the order of 700–1000 °C are needed to fully desorb C-H, C-O and Si-O species from these surfaces. However, using TPD, the authors observed H{sub 2} desorption at both lower temperatures (200–550 °C) as well as higher temperatures (>700 °C). The low temperature H{sub 2} desorption was deconvoluted into multiple desorption states that, based on similarities to H{sub 2} desorption from Si (111), were attributed to silicon mono, di, and trihydride surface species as well as hydrogen trapped by subsurface defects, steps, or dopants. The higher temperature H{sub 2} desorption was similarly attributed to H{sub 2} evolved from surface O-H groups at ∼750 °C as well as the liberation of H{sub 2} during Si-O desorption at temperatures >800 °C. These results indicate that while ex-situ aqueous HF processed 6H-SiC (0001) surfaces annealed at <700 °C remain terminated by some surface C–O and

  19. The Role of Plasma in Plasma Enhanced Chemical Vapour Deposition of Nanostructure Growth

    NASA Technical Reports Server (NTRS)

    Hash, David B.; Meyyappan, M.; Teo, Kenneth B. K.; Lacerda, Rodrigo G.; Rupesinghe, Nalin L.

    2004-01-01

    Chemical vapour deposition (CVD) has become the preferred process for high yield growth of carbon nanotubes and nanofibres because of its ability to pattern growth through lithographic positioning of transition metal catalysts on substrates. Many potential applications of nanotubes such as field emitters [1] require not only patterned growth but also vertical alignment. Some degree of ali,ment in thermal CVD processes can be obtained when carbon nanotubes are grown closely together as a result of van der Waals interactions. The ali,onment however is marginal, and the van der Waals prerequisite makes growth of freestanding nanofibres with thermal CVD unrealizable. The application of electric fields as a means of ali,onment has been shown to overcome this limitation [2-5], and highly aligned nanostructures can be grown if electric fields on the order of 0.5 V/microns are employed. Plasma enhanced CVD in various configurations including dc, rf, microwave, inductive and electron cyclotron resonance has been pursued as a means of enabling alignment in the CVD process. However, the sheath fields for the non-dc sources are in general not sufficient for a high degree of ali,pment and an additional dc bias is usually applied to the growth substrate. This begs the question as to the actual role of the plasma. It is clear that the plasma itself is not required for aligned growth as references [3] and [4] employed fields through small applied voltages (3-20 V) across very small electrode spacings (10-100 microns) and thus avoided striking a discharge.

  20. Remote plasma cleaning of optical surfaces: Cleaning rates of different carbon allotropes as a function of RF powers and distances

    NASA Astrophysics Data System (ADS)

    Cuxart, M. González; Reyes-Herrera, J.; Šics, I.; Goñi, A. R.; Fernandez, H. Moreno; Carlino, V.; Pellegrin, E.

    2016-01-01

    An extended study on an advanced method for the cleaning of carbon contaminations from large optical surfaces using a remote inductively coupled low-pressure RF plasma source (GV10x DownStream Asher) is reported. Technical and scientific features of this scaled up cleaning process are analysed, such as the cleaning efficiency for different carbon allotropes (amorphous and diamond-like carbon) as a function of feedstock gas, RF power (from 30 to 300 W), and source-object distances (415 to 840 mm). The underlying physical phenomena for these functional dependences are discussed.

  1. Growth Enhancement of Radish Sprouts Induced by Low Pressure O2 Radio Frequency Discharge Plasma Irradiation

    NASA Astrophysics Data System (ADS)

    Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu; Hayashi, Nobuya

    2012-01-01

    We studied growth enhancement of radish sprouts (Raphanus sativus L.) induced by low pressure O2 radio frequency (RF) discharge plasma irradiation. The average length of radish sprouts cultivated for 7 days after O2 plasma irradiation is 30-60% greater than that without irradiation. O2 plasma irradiation does not affect seed germination. The experimental results reveal that oxygen related radicals strongly enhance growth, whereas ions and photons do not.

  2. Strongly Enhanced Laser Absorption and Electron Acceleration via Resonant Excitation of Surface Plasma Waves

    NASA Astrophysics Data System (ADS)

    Raynaud, M.; Riconda, C.; Adam, J. C.; Heron, A.

    2010-02-01

    The possibility of creating enhanced fast electron bunches via the excitation of surface plasma waves (SPW) in laser overdense plasma interaction has been investigated by mean of relativistic one dimension motion of a test electron in the field of the surface plasma wave study and with two-dimensional (2D) Particle-In-Cell (PIC) numerical simulations. Strong electron acceleration together with a dramatic increase, up to 70%, of light absorption by the plasma is observed.

  3. Enhanced ionospheric plasma bubble generation in more active ITCZ

    NASA Astrophysics Data System (ADS)

    Li, Guozhu; Otsuka, Yuichi; Ning, Baiqi; Abdu, M. A.; Yamamoto, M.; Wan, Weixing; Liu, Libo; Abadi, Prayitno

    2016-03-01

    A close link between the atmospheric Intertropical Convergence Zone (ITCZ) and ionospheric plasma bubble has been proposed since the last century. But this relationship has often appeared to be less than convincing due to the simultaneous roles played by several other factors in shaping the global distribution of ionospheric bubbles. From simultaneous collaborative radar multibeam steering measurements at Kototabang (0.2°S, 100.3°E) and Sanya (18.4°N, 109.6°E), conducted during September-October of 2012 and 2013, we find that the total numbers of nights with bubble (i.e., occurrence rates) at the two closely located longitudes (Kototabang and Sanya) are comparable. But interestingly, the total number of nights with locally generated bubble (i.e., generation rate) over Kototabang is clearly more than that over Sanya. Further analysis reveals that a more active ITCZ is situated around the longitude of Kototabang. We surmise that the enhanced ionospheric bubble generation at Kototabang longitude could be caused by a higher gravity wave activity associated with the more active ITCZ.

  4. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    NASA Astrophysics Data System (ADS)

    Kaklamani, Georgia; Bowen, James; Mehrban, Nazia; Dong, Hanshan; Grover, Liam M.; Stamboulis, Artemis

    2013-05-01

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N2/H2 ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of Csbnd N, Cdbnd N, and Ctbnd N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  5. Characterization of plasma-enhanced atomic layer deposition of Al{sub 2}O{sub 3} using dimethylaluminum isopropoxide

    SciTech Connect

    Yang, Jialing; Eller, Brianna S.; Nemanich, Robert J.; Kaur, Manpuneet

    2014-03-15

    In this research, Al{sub 2}O{sub 3} films were grown by remote plasma-enhanced atomic layer deposition using a nonpyrophoric precursor, dimethylaluminum isopropoxide (DMAI), and oxygen plasma. After optimization, the growth rate was determined to be ∼1.5 Å/cycle within a growth window of 25–220 °C; the higher growth rate than reported for thermal atomic layer deposition was ascribed to the higher reactivity of the plasma species compared with H{sub 2}O and the adsorption of active oxygen at the surface, which was residual from the oxygen plasma exposure. Both effects enhance DMAI chemisorption and increase the saturation density. In addition, a longer oxygen plasma time was required at room temperature to complete the reaction and decrease the carbon contamination below the detection limit of x-ray photoemission spectroscopy. The properties of the subsequent Al{sub 2}O{sub 3} films were measured for different temperatures. When deposited at 25 °C and 200 °C, the Al{sub 2}O{sub 3} films demonstrated a single Al-O bonding state as measured by x-ray photoemission spectroscopy, a similar band gap of 6.8±0.2 eV as determined by energy loss spectroscopy, a similar index of refraction of 1.62±0.02 as determined by spectroscopic ellipsometry, and uniform growth with a similar surface roughness before and after growth as confirmed by atomic force microscopy. However, the room temperature deposited Al{sub 2}O{sub 3} films had a lower mass density (2.7 g/cm{sup 3} compared with 3.0 g/cm{sup 3}) and a higher atomic ratio of O to Al (2.1 compared with 1.6) as indicated by x-ray reflectivity and Rutherford backscattering spectroscopy, respectively.

  6. Backward Lasing of Air plasma pumped by Circularly polarized femtosecond pulses for the saKe of remote sensing (BLACK).

    PubMed

    Ding, Pengji; Mitryukovskiy, Sergey; Houard, Aurélien; Oliva, Eduardo; Couairon, Arnaud; Mysyrowicz, André; Liu, Yi

    2014-12-01

    Recently, S. Mitryukovskiy et al. presented experimental evidence showing that backward Amplified Spontaneous Emission (ASE) at 337 nm can be obtained from plasma filaments in nitrogen gas pumped by circularly polarized 800 nm femtosecond pulses (Opt. Express, 22, 12750 (2014)). Here, we report that a seed pulse injected in the backward direction can be amplified by ~200 times inside this plasma amplifier. The amplified 337 nm radiation can be either linearly or circularly polarized, dictated by the seeding pulse, which is distinct from the non-polarized nature of the ASE. We performed comprehensive measurements of the spatial profile, optical gain dynamics, and seed pulse energy dependence of this amplification process. These measurements allow us to deduce the pulse duration of the ASE and the amplified 337 nm radiation as well as the corresponding laser intensity inside the plasma amplifier. It indicates that the amplification is largely in the unsaturated regime and that further improvement of laser energy is possible. Moreover, we observed optical gain in plasma created in ambient air. This represents an important step towards future applications exploiting backward lasing for remote atmospheric sensing.

  7. Plasma torch for ignition, flameholding and enhancement of combustion in high speed flows

    NASA Technical Reports Server (NTRS)

    O'Brien, Walter F. (Inventor); Billingsley, Matthew C. (Inventor); Sanders, Darius D. (Inventor); Schetz, Joseph A. (Inventor)

    2009-01-01

    Preheating of fuel and injection into a plasma torch plume fro adjacent the plasma torch plume provides for only ignition with reduced delay but improved fuel-air mixing and fuel atomization as well as combustion reaction enhancement. Heat exchange also reduced erosion of the anode of the plasma torch. Fuel mixing atomization, fuel mixture distribution enhancement and combustion reaction enhancement are improved by unsteady plasma torch energization, integral formation of the heat exchanger, fuel injection nozzle and plasma torch anode in a more compact, low-profile arrangement which is not intrusive on a highspeed air flow with which the invention is particularly effective and further enhanced by use of nitrogen as a feedstock material and inclusion of high pressure gases in the fuel to cause effervescence during injection.

  8. Plasma enhanced C1 chemistry for green technology

    NASA Astrophysics Data System (ADS)

    Nozaki, Tomohiro

    2013-09-01

    Plasma catalysis is one of the innovative next generation green technologies that meet the needs for energy and materials conservation as well as environmental protection. Non-thermal plasma uniquely generates reactive species independently of reaction temperature, and these species are used to initiate chemical reactions at unexpectedly lower temperatures than normal thermochemical reactions. Non-thermal plasma thus broadens the operation window of existing chemical conversion processes, and ultimately allows modification of the process parameters to minimize energy and material consumption. We have been specifically focusing on dielectric barrier discharge (DBD) as one of the viable non-thermal plasma sources for practical fuel reforming. In the presentation, room temperature one-step conversion of methane to methanol and hydrogen using a miniaturized DBD reactor (microplasma reactor) is highlighted. The practical impact of plasma technology on existing C1-chemistry is introduced, and then unique characteristics of plasma fuel reforming such as non-equilibrium product distribution is discussed.

  9. Astragaloside IV enhances cardioprotection of remote ischemic conditioning after acute myocardial infarction in rats

    PubMed Central

    Cheng, Songyi; Yu, Peng; Yang, Li; Shi, Haibo; He, Anxia; Chen, Hanyu; Han, Jie; Xie, Liang; Chen, Jiandong; Chen, Xiaohu

    2016-01-01

    Background: Remote ischemic conditioning (RIC) has been shown to be a practical method for protecting the heart from ischemic/reperfusion (I/R) injury. In the present study, we investigated whether or not the combination of RIC and Astragaloside IV (AS-IV) could improve cardioprotection against acute myocardial infarction (AMI)-induced heart failure (HF) when compared with individual treatments. Material and Methods: A rat model of AMI was established via permanent ligation of the left anterior descending coronary artery (LAD). Postoperatively, the rats were randomly grouped into a sham group (n=10), a model group (n=15), an AS-IV alone group (n=15), an RIC alone group (n=15) and a combined treatment group (AS-IV+RIC; n=15). All treatments were administered for 2 weeks. Results: After treatment for 2 weeks, the survival rate was improved, the cardiac function was preserved and the infarcted size was limited in AS-IV alone and RIC alone treatment groups compared to the model group, whereas the combined treatment yielded the most optimal protective effects. Additional studies suggested that AS-IV enhanced the cardioprotective effects of RIC by alleviating myocardial fibrosis, suppressing inflammation, attenuating apoptosis and ameliorating impairment of the myocardial ultrastructural. Conclusion: AS-IV enhances the cardioprotective effects of RIC against AMI-induced HF and ventricular remodeling, which represents a potential therapeutic approach for preserving cardiac function and improving the prognosis of AMI. PMID:27904669

  10. Field-enhanced electrodes for additive-injection non-thermal plasma (NTP) processor

    DOEpatents

    Rosocha, Louis A.; Ferreri, Vincent; Kim, Yongho

    2009-04-21

    The present invention comprises a field enhanced electrode package for use in a non-thermal plasma processor. The field enhanced electrode package includes a high voltage electrode and a field-enhancing electrode with a dielectric material layer disposed in-between the high voltage electrode and the field-enhancing electrode. The field-enhancing electrode features at least one raised section that includes at least one injection hole that allows plasma discharge streamers to occur primarily within an injected additive gas.

  11. Plasma from human volunteers subjected to remote ischemic preconditioning protects human endothelial cells from hypoxia-induced cell damage.

    PubMed

    Weber, Nina C; Riedemann, Isabelle; Smit, Kirsten F; Zitta, Karina; van de Vondervoort, Djai; Zuurbier, Coert J; Hollmann, Markus W; Preckel, Benedikt; Albrecht, Martin

    2015-03-01

    Short repeated cycles of peripheral ischemia/reperfusion (I/R) can protect distant organs from subsequent prolonged I/R injury; a phenomenon known as remote ischemic preconditioning (RIPC). A RIPC-mediated release of humoral factors might play a key role in this protection and vascular endothelial cells are potential targets for these secreted factors. In the present study, RIPC-plasma obtained from healthy male volunteers was tested for its ability to protect human umbilical endothelial cells (HUVEC) from hypoxia-induced cell damage. 10 healthy male volunteers were subjected to a RIPC-protocol consisting of 4 × 5 min inflation/deflation of a blood pressure cuff located at the upper arm. Plasma was collected before (T0; control), directly after (T1) and 1 h after (T2) the RIPC procedure. HUVEC were subjected to 24 h hypoxia damage and simultaneously incubated with 5% of the respective RIPC-plasma. Cell damage was evaluated by lactate dehydrogenase (LDH)-measurements. Western blot experiments of hypoxia inducible factor 1 alpha (HIF1alpha), phosphorylated signal transducer and activator of transcription 5 (STAT5), protein kinase B (AKT) and extracellular signal-related kinase 1/2 (ERK-1/2) were performed. Furthermore, the concentrations of hVEGF were evaluated in the RIPC-plasma by sandwich ELISA. Hypoxia-induced cell damage was significantly reduced by plasma T1 (p = 0.02 vs T0). The protective effect of plasma T1 was accompanied by an augmentation of the intracellular HIF1alpha (p = 0.01 vs T0) and increased phosphorylation of ERK-1/2 (p = 0.03 vs T0). Phosphorylation of AKT and STAT5 remained unchanged. Analysis of the protective RIPC-plasma T1 showed significantly reduced levels of hVEGF (p = 0.01 vs T0). RIPC plasma protects endothelial cells from hypoxia-induced cell damage and humoral mediators as well as intracellular HIF1alpha may be involved.

  12. Compression enhancement by current stepping in a multicascade liner gas-puff Z-pinch plasma

    NASA Astrophysics Data System (ADS)

    Khattak, N. A. D.; Ahmad, Zahoor; Zakaullah, M.; Murtaza, G.

    2008-04-01

    Plasma dynamics of a liner consisting of two or three annular cascade gas-puffs with entrained axial magnetic field is studied using the modified snow-plow model. The current stepping technique (Les 1984 J. Phys. D: Appl. Phys. 17 733) is employed to enhance compression of the imploding plasma. A small-diameter low-voltage-driven system of imploding plasma is considered in order to work out the possibility of the highest gain, in terms of plasma parameters and radiation yield with a relatively simple and compact system. Our numerical results demonstrate that current stepping enhances the plasma compression, yielding high values of the plasma parameters and compressed magnetic field Bz (in magnitudes), if the switching time for the additional current is properly synchronized.

  13. Preferential acceleration and magnetic field enhancement in plasmas with e+/e- beam injection

    NASA Astrophysics Data System (ADS)

    Huynh, Cong Tuan; Ryu, Chang-Mo

    2016-03-01

    A theoretical model of current filaments predicting preferential acceleration/deceleration and magnetic field enhancement in a plasma with e+/e- beam injection is presented. When the e+/e- beams are injected into a plasma, current filaments are formed. The beam particles are accelerated or decelerated depending on the types of current filaments in which they are trapped. It is found that in the electron/ion ambient plasma, the e+ beam particles are preferentially accelerated, while the e- beam particles are preferentially decelerated. The preferential particle acceleration/deceleration is absent when the ambient plasma is the e+/e- plasma. We also find that the particle momentum decrease can explain the magnetic field increase during the development of Weibel/filamentation instability. Supporting simulation results of particle acceleration/deceleration and magnetic field enhancement are presented. Our findings can be applied to a wide range of astrophysical plasmas with the e+/e- beam injection.

  14. ICRF-enhanced plasma potentials in the SOL of Alcator C-Mod

    SciTech Connect

    Ochoukov, R.; Whyte, D. G.; Brunner, D.; LaBombard, B.; Lipschultz, B.; Terry, J. L.; Wukitch, S. J.; D'Ippolito, D. A.; Myra, J. R.

    2014-02-12

    We performed an extensive survey of the plasma potential in the scrape-off layer (SOL) of Ion Cyclotron Range-of Frequencies (ICRF)-heated discharges on Alcator C-Mod. Our results show that plasma potentials are enhanced in the presence of ICRF power and plasma potential values of >100 V are often observed. Such potentials are high enough to induce sputtering of high-Z molybdenum (Mo) plasma facing components by deuterium ions on C-Mod. For comparison, the plasma potential in Ohmic discharges is typically less than 10 V, well below the threshold needed to induce Mo sputtering by deuterium ions. ICRF-enhanced plasma potentials are observed in the SOL regions that both magnetically map and do not map to active ICRF antennas. Regions that magnetically map to active ICRF antennas are accessible to slow waves directly launched by the antennas and these regions experience plasma potential enhancement that is partially consistent with the slow wave rectification mechanism. One of the most defining features of the slow wave rectification is a threshold appearance of significant plasma potentials (>100 V) when the dimensionless rectification parameter Λ{sub −o} is above unity and this trend is observed experimentally. We also observe ICRF-enhanced plasma potentials >100 V in regions that do not magnetically map to the active antennas and, hence, are not accessible for slow waves launched directly by the active antennas. However, unabsorbed fast waves can reach these regions. The general trend that we observe in these 'un-mapped' regions is that the plasma potential scales with the strength of the local RF wave fields with the fast wave polarization and the highest plasma potentials are observed in discharges with the highest levels of unabsorbed ICRF power. Similarly, we find that core Mo levels scale with the level of unabsorbed ICRF power suggesting a link between plasma potentials in the SOL and the strength of the impurity source.

  15. Carbon nanofiber growth in plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Denysenko, I.; Ostrikov, K.; Cvelbar, U.; Mozetic, M.; Azarenkov, N. A.

    2008-10-01

    A theoretical model to describe the plasma-assisted growth of carbon nanofibers (CNFs) is proposed. Using the model, the plasma-related effects on the nanofiber growth parameters, such as the growth rate due to surface and bulk diffusion, the effective carbon flux to the catalyst surface, the characteristic residence time and diffusion length of carbon atoms on the catalyst surface, and the surface coverages, have been studied. The dependence of these parameters on the catalyst surface temperature and ion and etching gas fluxes to the catalyst surface is quantified. The optimum conditions under which a low-temperature plasma environment can benefit the CNF growth are formulated. These results are in good agreement with the available experimental data on CNF growth and can be used for optimizing synthesis of related nanoassemblies in low-temperature plasma-assisted nanofabrication.

  16. Plasma-induced polymerization for enhancing paper hydrophobicity.

    PubMed

    Song, Zhaoping; Tang, Jiebin; Li, Junrong; Xiao, Huining

    2013-01-30

    Hydrophobic modification of cellulose fibers was conducted via plasma-induced polymerization in an attempt to graft the hydrophobic polymer chains on paper surface, this increasing the hydrophobicity of paper. Two hydrophobic monomers, butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA), were grafted on cellulose fibers, induced by atmospheric cold plasma. Various influencing factors associated with the plasma-induced grafting were investigated. Contact-angle measurement, Fourier Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to ascertain the occurrence of the grafting and characterized the changes of the cellulose fiber after modification. The results showed that the hydrophobicity of the modified paper sheet was improved significantly after the plasma-induced grafting. The water contact angle on the paper surface reached up to 130°. The morphological differences between modified and unmodified samples were also revealed by SEM observation. The resulting paper is promising as a green-based packaging material.

  17. Plasma-enhanced atomic layer deposition: a gas-phase route to hydrophilic, glueable polytetrafluoroethylene.

    PubMed

    Roy, Amit K; Dendooven, Jolien; Deduytsche, Davy; Devloo-Casier, Kilian; Ragaert, Kim; Cardon, Ludwig; Detavernier, Christophe

    2015-02-28

    This communication reports an approach based on plasma-enhanced atomic layer deposition of aluminium oxide for the functionalization of polytetrafluoroethylene (PTFE or "Teflon") surfaces. Alternating exposure of PTFE to oxygen plasma and trimethylaluminium causes a permanent hydrophilic effect, and a more than 10-fold improvement of the "glueability" of PTFE to aluminium.

  18. Elastic waves and plasma - a new era of enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Pashchenko, A. F.; Ageev, P. G.

    2016-06-01

    New technology of enhanced oil recovery - plasma pulse treatment is described. The basic problems of residual oil recovery observed, taking in consideration elastic properties of a reservoir and dominant frequencies of a stratum. Numerical estimates of major parameters of an impact to the reservoir while plasma pulse treatment obtained. Positive results of PPT application introduced.

  19. Enhanced betatron X-rays from axially modulated plasma wakefields

    SciTech Connect

    Palastro, J. P.; Kaganovich, D.; Gordon, D.

    2015-06-15

    In the cavitation regime of plasma-based accelerators, a population of high-energy electrons trailing the driver can undergo betatron motion. The motion results in X-ray emission, but the brilliance and photon energy are limited by the electrons' initial transverse coordinate. To overcome this, we exploit parametrically unstable betatron motion in a cavitated, axially modulated plasma. Theory and simulations are presented showing that the unstable oscillations increase both the total X-ray energy and average photon energy.

  20. Plasma-Enhanced Copolymerization of Amino Acid and Synthetic Monomers

    DTIC Science & Technology

    2011-12-16

    the pure titania film was measured at 3.6 nm, which is much larger than that measured for the organic and biological plasma- deposited films and larger...valence state of the titanium atom, allowing for an increased number of bonding sites for oxygen, which creates titania molecules with a 2:1...the titania as well as expected byproduct from the dissociation of the TTIP monomer during the plasma deposition. Overall, the FTIR results discussed

  1. Integrated computer-enhanced remote viewing system. Quarterly report Number 5, October 1993--December 1993

    SciTech Connect

    1994-02-22

    The Interactive, Computer-Enhanced, Remote Viewing System (ICERVS) is a system designed to provide a reliable geometric description of a robotic task space in a fashion that enables robotic remediation to be carried out more efficiently and economically that with present systems. The key elements are a faithful way to store empirical data and a friendly user interface that provides an operator with timely access to all that is known about a scene. ICERVS will help an operator to analyze a scene and generate additional geometric data for automating significant portions of the remediation activity. Features that enable this include the following: storage and display of empirical sensor data; ability to update segments of the geometric description of the task space; side-by-side comparisons of a live TV scene and a computer generated view of the same scene; ability to create and display computer models of perceived objects in the task space, together with textual comments, and easy export of data to robotic world models for robot guidance.

  2. Enhancing computer literacy and information retrieval skills: A rural and remote nursing and midwifery workforce study.

    PubMed

    Mills, Jane; Francis, Karen; McLeod, Margaret; Al-Motlaq, Mohammad

    2015-01-01

    Nurses and midwives collectively, represent the largest workforce category in rural and remote areas of Australia. Maintaining currency of practice and attaining annual licensure with the Australian Health Practitioners Regulatory Authority (AHPRA) present challenges for individual nurses and midwives and for their health service managers. Engagement with information and communication technologies, in order for geographically isolated clinicians to access ongoing education and training, is considered a useful strategy to address such challenges. This paper presents a pre- and post-test study design. It examines the impact of an online continuing professional development (CPD) program on Australian rural nurses and midwives. The aims of the program were to increase basic skill acquisition in the utilisation of common computer software, the use of the Internet and the enhancement of email communication. Findings from the study demonstrate that participants who complete a relevant CPD program gain confidence in the use of information and communication technologies. Further, increased confidence leads to increased access to contemporary, reliable and important health care information on the Internet, in addition to clinicians adopting email as a regular method of communication. Health care employers commonly assume employees are skilled users of information and communication technologies. However, findings from this study contradict such assumptions. It is argued in the recommendations that health care employees should be given regular access to CPD programs designed to introduce them to information and communication technologies. Developing knowledge and skills in this area has the potential to improve staff productivity, raise health care standards and improve patient outcomes.

  3. Integrated Computer-Enhanced Remote Viewing System. Quarterly report number 4, July--October 1993

    SciTech Connect

    Not Available

    1993-11-30

    The Interactive, Computer-Enhanced, Remote Viewing System (ICERVS) is a system designed to provide a reliable geometric description of a robotic task space in a fashion that enables robotic remediation to be carried out more efficiently and economically than with present systems. The key elements are a faithful way to store empirical data and a friendly user interface that provides an operator with timely access to all that is known about a scene. The development of ICERVS is to occur in three phases. Phase 1 will focus on the development of the Data Library, which contains the geometric data about the task space and the objects in it, and the Toolkit, which includes the mechanisms for manipulating and displaying both empirical and model data. Phase 2 will concentrate on integrating these subsystems with a sensor subsystem into one working system. Some additional functionality will be incorporated in the Data Library and Toolkit subsystems. Phase 3 will expand the configuration to meet the needs of a full scale demonstration of the interactive mapping of some waste site to be identified. The second Phase of the ICERVS project consists of nine tasks. Significant efforts were devoted to the completion of Task 1: Intermediate System Design, and Task 3: Computer Upgrade. This report describes progress in these two tasks.

  4. A performance enhanced user-space remote procedure call on InfiniBand

    NASA Astrophysics Data System (ADS)

    Ming, Liang; Feng, Dan; Wang, Fang; Chen, Qi; Li, Yang; Wan, Yong; Zhou, Jun

    2011-11-01

    Remote Procedure Call (RPC) is widely used for constructing distributed, client-server based applications. Many distributed file systems, such as Lustre, pNFS, Panasas File System, Google File System use the RPC to exchange data and metadata between client nodes and server nodes. We have built a distribute file system called Cappella to meet the next generation high performance computing requirement, which uses the RPC as the communication protocol. But as we deployed the user-space open source RPC on our system, we found that it can't take full advantage of our 40 Gb/s InfiniBand network. This paper shared the problem that we observed during our RPC deployment and proposed a multithread method to enhance the performance of user-space RPC. And we also implemented a Socket Direct Protocol (SDP) based RPC protocol to use the RDMA capability of InfiniBand to transport data. And the experiments showed that our multi-thread user-space RPC had improved the performance over 60%.

  5. Plasma-enhanced microwave solid-state synthesis of cadmium sulfide: reaction mechanism and optical properties.

    PubMed

    Du, Ke-zhao; Chaturvedi, Apoorva; Wang, Xing-zhi; Zhao, Yi; Zhang, Ke-ke; Iqbal Bakti Utama, M; Hu, Peng; Jiang, Hui; Xiong, Qi-hua; Kloc, Christian

    2015-08-14

    CdS synthesis by plasma-enhanced microwave physical vapor transport (PMPVT) has been developed in this work. The photoluminescence (PL), absorbance, Raman spectra and the mechanism of CdS crystal growth have been investigated. Furthermore, plasma-enhanced microwave chemical vapour transport (PMCVT) synthesis of CdS with additional chemical transport agents has been explored. In addition, other II-VI chalcogenides were also synthesized by PMPVT.

  6. Effects of remote hydrogen plasma on chemical bonding features and electronic states of 4H-SiC(0001) surface

    NASA Astrophysics Data System (ADS)

    Truyen, Nguyen Xuan; Ohta, Akio; Makihara, Katsunori; Ikeda, Mitsuhisa; Miyazaki, Seiichi

    2017-01-01

    We have demonstrated a novel dry cleaning process for the 4H-SiC surface using remote hydrogen plasma (H2-RP). The effects of H2-RP exposure on the chemical structures and electronic states of the wet-cleaned 4H-SiC surface have been evaluated by X-ray photoelectron spectroscopy (XPS) and total photoelectron yield spectroscopy (PYS). XPS shows that H2-RP exposure is effective in removing contaminants from the 4H-SiC surface. PYS indicates that the defect states at the surface are generated after the H2-RP exposure and such generated defect states are drastically decreased by annealing at 850 °C. The combination of H2-RP exposure with the subsequent annealing is found to be effective in 4H-SiC surface cleaning.

  7. Using In Situ and Remote Sensing Data to Model the Plasma Flow throughout the Heliosphere

    NASA Astrophysics Data System (ADS)

    Kim, T. K.; Pogorelov, N. V.; Arge, C. N.; Jackson, B. V.; Kryukov, I.; Manoharan, P. K.; Tropf, D.; Yu, H. S.; Zank, G. P.

    2015-12-01

    The solar wind is a turbulent medium with physical properties fluctuating on multiple scales. We model three-dimensional solar wind plasma flow using our own software, Multi-Scale Fluid-Kinetic Simulation Suite, which, in addition to the thermal solar wind plasma, takes into account charge exchange of solar wind protons with interstellar neutral atoms and treats nonthermal ions (pickup ions, PUIs) born during this process as a separate fluid. Additionally, our model includes a description of turbulence generated by PUIs. For this investigation, we run our model using plasma and turbulence parameters from OMNI data as time-dependent boundary conditions at 1 AU for the Reynolds-averaged MHD equations and investigate the evolution of plasma and turbulent fluctuations along the trajectory of the New Horizons spacecraft, which recently passed by Pluto nearly ten years after launch. We also present solar wind simulations starting at 0.1 AU outwards using interplanetary scintillation data as boundary conditions. Simulations are compared with OMNI and STEREO data. The purpose of this study is to create a time-dependent solar wind model capable of reproducing the plasma flow, magnetic field, and turbulence along the trajectories of Solar Probe Plus and Solar Orbiter.

  8. Proliferation-Related Activity in Endothelial Cells Is Enhanced by Micropower Plasma

    PubMed Central

    Suzuki, Kotaro

    2016-01-01

    Nonthermal plasma has received a lot of attention as a medical treatment technique in recent years. It can easily create various reactive chemical species (ROS) and is harmless to living body. Although plasma at gas-liquid interface has a potential for a biomedical application, the interactions between the gas-liquid plasma and living cells remain unclear. Here, we show characteristics of a micropower plasma with 0.018 W of the power input, generated at gas-liquid interface. We also provide the evidence of plasma-induced enhancement in proliferation activity of endothelial cells. The plasma produced H2O2, HNO2, and HNO3 in phosphate buffered saline containing Mg++ and Ca++ (PBS(+)), and their concentration increased linearly during 600-second discharge. The value of pH in PBS(+) against the plasma discharge time was stable at about 7.0. Temperature in PBS(+) rose monotonically, and its rise was up to 0.8°C at the bottom of a cell-cultured dish by the plasma discharge for 600 s. Short-time treatment of the plasma enhanced proliferation activity of endothelial cells. In contrast, the treatment of H2O2 does not enhance the cell proliferation. Thus, the ROS production and the nuclear factor-kappa B (NF-κB) activation due to the plasma treatment might be related to enhancement of the cell proliferation. Our results may potentially provide the basis for developing the biomedical applications using the gas-liquid plasma. PMID:28058258

  9. Interactive Online Tools for Enhancing Student Learning Experiences in Remote Sensing

    ERIC Educational Resources Information Center

    Joyce, Karen E.; Boitshwarelo, Bopelo; Phinn, Stuart R.; Hill, Greg J. E.; Kelly, Gail D.

    2014-01-01

    The rapid growth in Information and Communications Technologies usage in higher education has provided immense opportunities to foster effective student learning experiences in geography. In particular, remote sensing lends itself to the creative utilization of multimedia technologies. This paper presents a case study of a remote sensing computer…

  10. Diagnostic for Plasma Enhanced Chemical Vapor Deposition and Etch Systems

    NASA Technical Reports Server (NTRS)

    Cappelli, Mark A.

    1999-01-01

    In order to meet NASA's requirements for the rapid development and validation of future generation electronic devices as well as associated materials and processes, enabling technologies ion the processing of semiconductor materials arising from understanding etch chemistries are being developed through a research collaboration between Stanford University and NASA-Ames Research Center, Although a great deal of laboratory-scale research has been performed on many of materials processing plasmas, little is known about the gas-phase and surface chemical reactions that are critical in many etch and deposition processes, and how these reactions are influenced by the variation in operating conditions. In addition, many plasma-based processes suffer from stability and reliability problems leading to a compromise in performance and a potentially increased cost for the semiconductor manufacturing industry. Such a lack of understanding has hindered the development of process models that can aid in the scaling and improvement of plasma etch and deposition systems. The research described involves the study of plasmas used in semiconductor processes. An inductively coupled plasma (ICP) source in place of the standard upper electrode assembly of the Gaseous Electronics Conference (GEC) radio-frequency (RF) Reference Cell is used to investigate the discharge characteristics and chemistries. This ICP source generates plasmas with higher electron densities (approximately 10(exp 12)/cu cm) and lower operating pressures (approximately 7 mTorr) than obtainable with the original parallel-plate version of the GEC Cell. This expanded operating regime is more relevant to new generations of industrial plasma systems being used by the microelectronics industry. The motivation for this study is to develop an understanding of the physical phenomena involved in plasma processing and to measure much needed fundamental parameters, such as gas-phase and surface reaction rates. species

  11. Using Plasma Physics to Enhance the High School Physics Curriculu

    NASA Astrophysics Data System (ADS)

    Wise, J.; Buck, M.; Gekelman, W.; Buck, R.; Spahn, C.; Walker, C.; Layton, W.

    2001-10-01

    Faculty and student members of the Los Angeles Physics Teachers Alliance Group (LAPTAG) have constructed a plasma machine on the ULCA. Dr. Gekelman, the faculty advisor, provides information and materials on plasma physics via the Web and lectures to high school faculty and students. Faculty members then transfer the information to students at their respective schools and schedule time for experiments on the machine. A lab manual and curricular materials suitable for high school students is being developed using a lab based, discovery approach. The manual is available as a pdf document on the LAPTAG website (http://coke.physics.ucla.edu/laptag/plasma_exp.dir/laptag_plasma.htm). Introducing plasma physics into the high school curriculum provides a 20th century application of classical physics concepts that support and motivate student interest in physics. Students from LAPTAG schools use state-of-the-art computers, software, and equipment to perform developed labs and to design experiments of their own. Collaboration exists between students and faculty from different schools and the university. Learning physics concepts takes place in the context of a "science community" that realistically demonstrates the scientific process to students.

  12. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  13. A theoretical model for the temporal evolution of HF-enhanced plasma lines

    NASA Technical Reports Server (NTRS)

    Kuo, S. P.; Ho, A. Y.; Lee, M. C.; Djuth, F. T.

    1990-01-01

    The HF-enhanced plasma lines (HFPLs) observed in the Arecibo heating experiments refer to the radar returns at frequencies near the sum and difference of the radar frequency and the HF-heatear frequency. Those enhanced spectral lines are caused by backscatter of radar signals from parametrically excited plasma waves having a wavenumber of 18 n. A nonlinear theory was developed to describe the temporal evolution of those specified plasma waves and their originating altitude interval of HFPLs observed at Arecibo, Puerto Rico are explained. The theoretical resultsagree well with the observation (Djuth and Sulzer, 1989).

  14. Plasmas in Multiphase Media: Bubble Enhanced Discharges in Liquids and Plasma/Liquid Phase Boundaries

    SciTech Connect

    Kushner, Mark Jay

    2014-07-10

    In this research project, the interaction of atmospheric pressure plasmas with multi-phase media was computationally investigated. Multi-phase media includes liquids, particles, complex materials and porous surfaces. Although this investigation addressed fundamental plasma transport and chemical processes, the outcomes directly and beneficially affected applications including biotechnology, medicine and environmental remediation (e.g., water purification). During this project, we made advances in our understanding of the interaction of atmospheric pressure plasmas in the form of dielectric barrier discharges and plasma jets with organic materials and liquids. We also made advances in our ability to use computer modeling to represent these complex processes. We determined the method that atmospheric pressure plasmas flow along solid and liquid surfaces, and through endoscopic like tubes, deliver optical and high energy ion activation energy to organic and liquid surfaces, and produce reactivity in thin liquid layers, as might cover a wound. We determined the mechanisms whereby plasmas can deliver activation energy to the inside of liquids by sustaining plasmas in bubbles. These findings are important to the advancement of new technology areas such as plasma medicine

  15. Enhanced acceleration of injected electrons in a laser-beat-wave-induced plasma channel.

    PubMed

    Tochitsky, S Ya; Narang, R; Filip, C V; Musumeci, P; Clayton, C E; Yoder, R B; Marsh, K A; Rosenzweig, J B; Pellegrini, C; Joshi, C

    2004-03-05

    Enhanced energy gain of externally injected electrons by a approximately 3 cm long, high-gradient relativistic plasma wave (RPW) is demonstrated. Using a CO2 laser beat wave of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-induced defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser-beat-wave-induced plasma channel.

  16. An enhancement of plasma density by neutral gas injection observed in SEPAC Spacelab-1 experiment

    NASA Technical Reports Server (NTRS)

    Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Obayashi, T.; Kubota, S.; Roberts, W. T.; Reasoner, D. L.; Taylor, W. W. L.; Williamson, P. R.

    1985-01-01

    An enhancement of plasma density observed during a neutral gas injection in Space Experiments with Particle Accelerators by the Space Shuttle/Spacelab-1 is presented. When a plume of nitrogen gas was injected from the orbiter into space, a large amount of plasma was detected by an onboard plasma probe. The observed density often increased beyond the background plasma density and was strongly dependent on the attitude of the orbiter with respect to the velocity vector. This effect has been explained by a collisional interaction between the injected gas molecules and the ionospheric ions relatively drifting at the orbital speed.

  17. Electric field enhanced conductivity in strongly coupled dense metal plasma

    SciTech Connect

    Stephens, J.; Neuber, A.

    2012-06-15

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field ({approx}6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  18. Electric field enhanced conductivity in strongly coupled dense metal plasma

    NASA Astrophysics Data System (ADS)

    Stephens, J.; Neuber, A.

    2012-06-01

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field (˜6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  19. Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol

    SciTech Connect

    Campo, Teresa; Cotto, María; Márquez, Francisco; Elizalde, Eduardo; Morant, Carmen

    2016-03-01

    A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plasma blue flash is required for obtaining graphene flakes. The synthesized graphene was characterized by different techniques, showing the presence of non-oxidized graphene with high purity.

  20. Surface plasma treatment of poly(caprolactone) micro, nano, and multiscale fibrous scaffolds for enhanced osteoconductivity.

    PubMed

    Sankar, Deepthi; Shalumon, K T; Chennazhi, K P; Menon, Deepthy; Jayakumar, R

    2014-06-01

    In this study, poly(caprolactone) (PCL) was electrospun to nano, micro, and multiscale (micro-nano) fibers, which were then subjected to low pressure argon and nitrogen plasma treatment. The electrospun fibers contain microfibers of diameter 8-10 μm and nanofibers of diameter 200-300 nm. Characterization of the plasma-treated fibers showed that treatment using less oxidizing gas like nitrogen and inert gas like argon functionalize the surface with polar groups that significantly modify the properties of the scaffold. Highly hydrophobic PCL fibrous scaffolds were rendered hydrophilic, with significantly improved biomineralization after the plasma treatment. While plasma treatment on micro and multiscale fibers enhanced their protein adsorption, cell attachment, spreading, elongation, and proliferation, nanofibers showed remarkably improved cell attachment. The applicability of plasma-treated electrospun fibers for differentiation of mesenchymal stem cell toward osteogenic lineage was also studied. Accelerated differentiation toward osteoblast lineage, with maximum alkaline phosphatase (ALP) activity in 14 days was achieved in plasma-treated fibers. Another remarkable outcome was the enhanced ALP activity of the microfibers after plasma treatment, compared with multiscale and nanofibers. Alizarin red staining further confirmed the mineralization of the plasma-treated scaffolds, indicative of maturation of the differentiated cells. This work thus concentrates on harnessing the potential of plasma treatment, for improving the osteoconductivity of fibrous scaffolds, which could be used for bone tissue engineering/regenerative medicine.

  1. Nuclear Fusion Within Extremely Dense Plasma Enhanced by Quantum Particle Waves

    NASA Astrophysics Data System (ADS)

    Miao, Feng; Zheng, Xianjun; Deng, Baiquan

    2015-05-01

    Quantum effects play an enhancement role in p-p chain reactions occurring within stars. Such an enhancement is quantified by a wave penetration factor that is proportional to the density of the participating fuel particles. This leads to an innovative theory for dense plasma, and its result shows good agreement with independent data derived from the solar energy output. An analysis of the first Z-pinch machine in mankind's history exhibiting neutron emission leads to a derived deuterium plasma beam density greater than that of water, with plasma velocities exceeding 10000 km/s. Fusion power could be achieved by the intersection of four such pinched plasma beams with powerful head-on collisions in their common focal region due to the beam and target enhanced reaction. supported by the Fund for the Construction of Graduate Degree of China (No. 2014XWD-S0805)

  2. A physical model of radiated enhancement of plasma-surrounded antenna

    SciTech Connect

    Gao, Xiaotian; Wang, Chunsheng Jiang, Binhao; Zhang, Zhonglin

    2014-09-15

    A phenomenon that the radiated power may be enhanced when an antenna is surrounded by a finite plasma shell has been found in numerical and experimental studies. In this paper, a physical model was built to express the mechanism of the radiated enhancement. In this model, the plasma shell is treated as a parallel connection of a capacitance and a conductance whose parameters change with the system parameters (plasma density, collision frequency, and antenna frequency). So, the radiated enhancement can be explained by the resonance between the plasma shell and the infinite free space. Furthermore, the effects of system parameters on the radiated power are given and effects corresponding to mechanisms are performed based on the physical model.

  3. Storm-enhanced plasma density features investigated during the Bastille Day Superstorm

    NASA Astrophysics Data System (ADS)

    Horvath, Ildiko; Lovell, Brian C.

    2010-06-01

    Field-aligned passes track true profiles. Such Defense Meteorological Satellite Program passes permitted investigating storm-enhanced plasma density (SED) feature development during the Bastille Day Superstorm in a comprehensive way. We tracked equatorial ionization anomaly (EIA) and SED features and their underlying forward fountain circulation and downward SED plume plasma flows, respectively. Northward subauroral polarization stream E fields detaching plasma and producing SED plumes were also detected. We assessed the effects of South Atlantic Magnetic Anomaly and summer-to-winter interhemispheric plasma flows on the EIA and found a southward dipping gradient in drift/flow when no storm/evening-related fountain strengthening occurred. We investigated the relative importance of different plasma sources in SED development. An extremely large plasma enhancement seen over Florida at 2200 UT on 15 July 2000 was a SED feature that was tracked by many GPS total electron content (TEC) maps as a 200 TEC unit (TECU) enhancement. We tracked its equally large conjugate pair over Trelew (Argentine Patagonia) and unraveled their development. Their underlying SED plume supplied most of the plasma. Appearing between these two SED features, a small and highly asymmetrical EIA offered on each side a low baseline upon which the downward streaming SED plume plasma piled up. Contradicting a currently accepted explanation, there was no enhanced fountain action detected to contribute 150 TECU to the 200 TECU. Later (˜2400 UT), there was enhanced fountain action, but SED plume contribution still dominated. Proven by observational evidence, SED development is a complex process of SED plume plasma flows and equatorward wind effects that cannot be described by one single explanation.

  4. Atmospheric Plasma-Enhanced Soft Hydrolysis of Southern Pine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The production of fermentable sugars from southern pine using atmospheric plasma (AP) was studied. AP processing in the dielectric barrier discharge (DBD) configuration was coupled with acid hydrolysis in an effort to determine how AP can impact a standard conversion technique. The effects of plas...

  5. Role of plasma enhanced atomic layer deposition reactor wall conditions on radical and ion substrate fluxes

    SciTech Connect

    Sowa, Mark J.

    2014-01-15

    Chamber wall conditions, such as wall temperature and film deposits, have long been known to influence plasma source performance on thin film processing equipment. Plasma physical characteristics depend on conductive/insulating properties of chamber walls. Radical fluxes depend on plasma characteristics as well as wall recombination rates, which can be wall material and temperature dependent. Variations in substrate delivery of plasma generated species (radicals, ions, etc.) impact the resulting etch or deposition process resulting in process drift. Plasma enhanced atomic layer deposition is known to depend strongly on substrate radical flux, but film properties can be influenced by other plasma generated phenomena, such as ion bombardment. In this paper, the chamber wall conditions on a plasma enhanced atomic layer deposition process are investigated. The downstream oxygen radical and ion fluxes from an inductively coupled plasma source are indirectly monitored in temperature controlled (25–190 °C) stainless steel and quartz reactors over a range of oxygen flow rates. Etch rates of a photoresist coated quartz crystal microbalance are used to study the oxygen radical flux dependence on reactor characteristics. Plasma density estimates from Langmuir probe ion saturation current measurements are used to study the ion flux dependence on reactor characteristics. Reactor temperature was not found to impact radical and ion fluxes substantially. Radical and ion fluxes were higher for quartz walls compared to stainless steel walls over all oxygen flow rates considered. The radical flux to ion flux ratio is likely to be a critical parameter for the deposition of consistent film properties. Reactor wall material, gas flow rate/pressure, and distance from the plasma source all impact the radical to ion flux ratio. These results indicate maintaining chamber wall conditions will be important for delivering consistent results from plasma enhanced atomic layer deposition

  6. Improved integration of ultra-thin high-k dielectrics in few-layer MoS2 FET by remote forming gas plasma pretreatment

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Zhang, Tian-Bao; Yang, Wen; Zhu, Hao; Chen, Lin; Sun, Qing-Qing; Zhang, David Wei

    2017-01-01

    The effective and high-quality integration of high-k dielectrics on two-dimensional (2D) crystals is essential to the device structure engineering and performance improvement of field-effect transistor (FET) based on the 2D semiconductors. We report a 2D MoS2 transistor with ultra-thin Al2O3 top-gate dielectric (6.1 nm) and extremely low leakage current. Remote forming gas plasma pretreatment was carried out prior to the atomic layer deposition, providing nucleation sites with the physically adsorbed ions on the MoS2 surface. The top gate MoS2 FET exhibited excellent electrical performance, including high on/off current ratio over 109, subthreshold swing of 85 mV/decade and field-effect mobility of 45.03 cm2/V s. Top gate leakage current less than 0.08 pA/μm2 at 4 MV/cm has been obtained, which is the smallest compared with the reported top-gated MoS2 transistors. Such an optimized integration of high-k dielectric in 2D semiconductor FET with enhanced performance is very attractive, and it paves the way towards the realization of more advanced 2D nanoelectronic devices and integrated circuits.

  7. Remote detection of the maximum altitude of equatorial ionospheric plasma bubbles

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1981-01-01

    Nearly 200 post-sunset low-altitude passes of the Alouette 2 and ISIS 1 satellites near the dip equator are studied in order to find the maximum ionospheric plasma bubble altitudes, which are determined by calculating the apex altitude of the magnetic field line passing through the satellite when it is immersed in a bubble. The calculations are made only upon the observation of conjugate hemisphere ionospheric echoes, which result from ducted HF sounder signals that are guided along field-aligned irregularities within the plasma depletion. The maximum bubble altitudes corresponding to the three longitude sectors centered on zero deg, 75 deg W, and 105 deg E, are found to often exceed 1000 km, but seldom 3000 km. The electron density depletions within these field-aligned bubbles, as measured at the point of satellite encounter with the topside ionosphere, are generally less than a factor of two but may exceed a factor of ten.

  8. Enhanced biocompatibility of TiO2 surfaces by highly reactive plasma

    NASA Astrophysics Data System (ADS)

    Junkar, Ita; Kulkarni, Mukta; Drašler, Barbara; Rugelj, Neža; Recek, Nina; Drobne, Damjana; Kovač, Janez; Humpolicek, Petr; Iglič, Aleš; Mozetič, Miran

    2016-06-01

    In the present study the biological response to various nanotopographic features after gaseous plasma treatment were studied. The usefulness of nanostructured surfaces for implantable materials has already been acknowledged, while less is known on the combined effect of nanostructured plasma modified surfaces. In the present work the influence of oxygen plasma treatment on nanostructured titanium oxide (TiO2) surfaces was studied. Characterization of the TiO2 surface chemical composition and morphological features was analyzed after plasma modification by x-ray photoelectron spectroscopy and by scanning electron microscopy while surface wettability was studied with measuring the water contact angle. Cell adhesion and morphology was assessed from images taken with scanning electron microscopy, whereas cell viability was measured with a calorimetric assay. The obtained results showed that oxygen plasma treatment of TiO2 nanotube surfaces significantly influences the adhesion and morphology of osteoblast-like cells in comparison to untreated nanostructured surfaces. Marked changes in surface composition of plasma treated surfaces were observed, as plasma treatment removed hydrocarbon contamination and removed fluorine impurities, which were present due to the electrochemical anodization process. However no differences in wettability of untreated and plasma treated surfaces were noticed. Treatment with oxygen plasma stimulated osteoblast-like cell adhesion and spreading on the nanostructured surface, suggesting the possible use of oxygen plasma surface treatment to enhance osteoblast-like cell response.

  9. Elemental mass spectroscopy of remote surfaces from laser-induced plasmas

    NASA Technical Reports Server (NTRS)

    Situ, W.; DeYoung, R. J.

    1994-01-01

    The elemental mass analysis of laser-produced ions from Al, Cu, Ge, Ag, and a lunar simulant target when irradiated by a 400-mJ, 8-ns, Nd: YAG laser at 1 x 10(exp 9) W/cm(exp 2), is reported. Ions traveled down a 11.1-m evacuated tube to an ion-trap 1-m time-of-flight (TOF) mass spectrometer where an elemental mass spectrum was recorded. The amount of target material removed per laser pulse and the ionization fraction were measured. The ion spatial distribution was measured at 11.1-m distance and found to be near a fourth-power cosine distribution. These results indicate the ability to mass analyze a surface over a distance of many kilometers for lunar and asteroid surface elemental mass analysis by a remote satellite or lunar rover.

  10. Enhancement of Capabilities in Hyperspectral and Radar Remote Sensing for Environmental Assessment and Monitoring

    NASA Technical Reports Server (NTRS)

    Hepner, George F.

    1999-01-01

    The University of Utah, Department of Geography has developed a research and instructional program in satellite remote sensing and image processing. The University requested funds for the purchase of software licenses, mass storage for massive hyperspectral imager data sets, upgrades for the central data server to handle the additional storage capacity, a spectroradiometer for field data collection. These purchases have been made. This equipment will support research in one of the newest and most rapidly expanding areas of remote sensing.

  11. Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol

    DOE PAGES

    Campo, Teresa; Cotto, María; Márquez, Francisco; ...

    2016-03-01

    A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plasma blue flash is required for obtaining graphene flakes. The synthesized graphene was characterized by different techniques, showing the presence of non-oxidized graphenemore » with high purity.« less

  12. Plasma-enhanced mixing and flameholding in supersonic flow

    PubMed Central

    Firsov, Alexander; Savelkin, Konstantin V.; Yarantsev, Dmitry A.; Leonov, Sergey B.

    2015-01-01

    The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure Pst=160–250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of Wpl=3–24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air–fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. PMID:26170434

  13. Plasma-enhanced mixing and flameholding in supersonic flow.

    PubMed

    Firsov, Alexander; Savelkin, Konstantin V; Yarantsev, Dmitry A; Leonov, Sergey B

    2015-08-13

    The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure P(st)=160-250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of W(pl)=3-24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air-fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation.

  14. Large plasma density enhancements occurring in the northern polar region during the 6 April 2000 superstorm

    NASA Astrophysics Data System (ADS)

    Horvath, Ildiko; Lovell, Brian C.

    2014-06-01

    We focus on the ionospheric response of northern high-latitude region to the 6 April 2000 superstorm and aim to investigate how the storm-enhanced density (SED) plume plasma became distributed in the regions of auroral zone and polar cap plus to study the resultant ionospheric features and their development. Multi-instrument observational results combined with model-generated, two-cell convection maps permitted identifying the high-density plasma's origin and the underlying plasma transportation processes. Results show the plasma density feature of polar cap enhancement (PCE; ~600 × 103 i+/cm3) appearing for 7 h during the main phase and characterized by increases reaching up to 6 times of the quiet time values. Meanwhile, strong westward convections (~17,500 m/s) created low plasma densities in a wider region of the dusk cell. Oppositely, small (~750 m/s) but rigorous westward drifts drove the SED plume plasma through the auroral zone, wherein plasma densities doubled. As the SED plume plasma traveled along the convection streamlines and entered the polar cap, a continuous enhancement of the tongue of ionization (TOI) developed under steady convection conditions. However, convection changes caused slow convections and flow stagnations and thus segmented the TOI feature by locally depleting the plasma in the affected regions of the auroral zone and polar cap. From the strong correspondence of polar cap potential drop and subauroral polarization stream (SAPS), we conclude that the SAPS E-field strength remained strong, and under its prolonged influence, the SED plume provided a continuous supply of downward flowing high-density plasma for the development and maintenance of PCEs.

  15. Whistler wave-induced ionospheric plasma turbulence: Source mechanisms and remote sensing

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Rooker, L. A.; Whitehurst, L. N.; Lee, M. C.; Ross, L. M.; Sulzer, M. P.; Gonzalez, S.; Tepley, C.; Aponte, N.; See, B. Z.; Hu, K. P.

    2013-10-01

    We report a series of experiments conducted at Arecibo Observatory in the past, aimed at the investigation of 40.75 kHz whistler wave interactions with ionospheric plasmas and the inner radiation belts at L=1.35. The whistler waves are launched from a Naval transmitter (code-named NAU) operating in Aguadilla, Puerto Rico at the frequency and power of 40.75 kHz and 100 kW, respectively. Arecibo radar, CADI, and optical instruments were used to monitor the background ionospheric conditions and detect the induced ionospheric plasma effects. Four-wave interaction processes produced by whistler waves in the ionosphere can excite lower hybrid waves, which can accelerate ionospheric electrons. Furthermore, whistler waves propagating into the magnetosphere can trigger precipitation of energetic electrons from the radiation belts. Radar and optical measurements can distinguish wave-wave and wave-particle interaction processes occurring at different altitudes. Electron acceleration by different mechanisms can be verified from the radar measurements of plasma lines. To facilitate the coupling of NAU-launched 40.75 kHz whistler waves into the ionosphere, we can rely on naturally occurring spread F irregularities to serve as ionospheric ducts. We can also use HF wave-created ducts/artificial waveguides, as demonstrated in our earlier Arecibo experiments and recent Gakona experiments at HAARP. The newly constructed Arecibo HF heater will be employed in our future experiments, which can extend the study of whistler wave interactions with the ionosphere and the magnetosphere/radiation belts as well as the whistler wave conjugate propagation between Arecibo and Puerto Madryn, Argentina.

  16. Plasma-enhanced atomic layer deposition of silicon dioxide films using plasma-activated triisopropylsilane as a precursor

    SciTech Connect

    Jeon, Ki-Moon; Shin, Jae-Su; Yun, Ju-Young; Jun Lee, Sang; Kang, Sang-Woo

    2014-05-15

    The plasma-enhanced atomic layer deposition (PEALD) process was developed as a growth technique of SiO{sub 2} thin films using a plasma-activated triisopropylsilane [TIPS, ((iPr){sub 3}SiH)] precursor. TIPS was activated by an argon plasma at the precursor injection stage of the process. Using the activated TIPS, it was possible to control the growth rate per cycle of the deposited films by adjusting the plasma ignition time. The PEALD technique allowed deposition of SiO{sub 2} films at temperatures as low as 50 °C without carbon impurities. In addition, films obtained with plasma ignition times of 3 s and 10 s had similar values of root-mean-square surface roughness. In order to evaluate the suitability of TIPS as a precursor for low-temperature deposition of SiO{sub 2} films, the vapor pressure of TIPS was measured. The thermal stability and the reactivity of the gas-phase TIPS with respect to water vapor were also investigated by analyzing the intensity changes of the C–H and Si–H peaks in the Fourier-transform infrared spectrum of TIPS.

  17. Experimental Verification on Remote Detectability of Concealed Radioactive Material Based on the Plasma Discharge Delay Time using High-Power Millimeter-Wave

    NASA Astrophysics Data System (ADS)

    Kim, Dongsung; Yu, Dongho; Sawant, Ashwini; Choe, Mun Seok; Lee, Ingeun; Choi, Eunmi

    2016-10-01

    We experimentally demonstrate a remote detection method of a radioactive source by plasma breakdown using high-power millimeter-wave source, gyrotron. A number of free electrons near the radioactive source are much higher than those of without the radioactive source (roughly 10 particles/cm3) owing to the interaction of air molecules and strong gamma rays generated by radioactive material. The RF wave beam is focused in ambient air, and the plasmas discharge occurs involving random delay time which means a time interval between the RF wave and a fluorescent light caused by the plasma. We observed that the delay time decreased significantly due to the high density of free electrons in Ar plasma with an existence of Co60 radioactive material. This technique of delay time measurement shows 1000 times more sensitive than a method of detectable mass equation to identify the existence of radioactive source remotely. It is the first experimental verification of radioactive material detection using a high power gyrotron. This study shows that a remote detection of radioactive material based on analysis of precise delay time measurement could be feasible by using a high power millimeter/THz wave gyrotron. NRF-2013R1A1A2061062, NRF-2012-Global Ph.D. Fellowship Program.

  18. Langmuir probe study of an inductively coupled magnetic-pole-enhanced helium plasma

    NASA Astrophysics Data System (ADS)

    Younus, Maria; Rehman, N. U.; Shafiq, M.; Naeem, M.; Zaka-ul-Islam, M.; Zakaullah, M.

    2017-03-01

    This study reports the effects of RF power and filling gas pressure variation on the plasma parameters, including the electron number density n e , electron temperature T e , plasma potential V p , skin depth δ, and electron energy probability functions (EEPFs) in a low-pressure inductively coupled helium plasma source with magnetic pole enhancement. An RF compensated Langmuir probe is used to measure these plasma parameters. It is observed that the electron number density increases with both the RF power and the filling gas pressure. Conversely, the electron temperature decreases with increasing RF power and gas pressure. It is also noted that, at low RF powers and gas pressures, the EEPFs are non-Maxwellian, while at RF powers of ≥50 W, they evolve into a Maxwellian distribution. The dependences of the skin depth and plasma potential on the RF power are also studied and show a decreasing trend.

  19. Enhancement of photocatalytic activity of TiO2 by plasma irradiation

    NASA Astrophysics Data System (ADS)

    Kajita, Shin; Yoshida, Tomoko; Ohno, Noriyasu; Ishida, Tomoya; Kitaoka, Daiki

    2016-10-01

    In this study, plasma irradiations to titanium were conducted to enhance the photocatalytic activity of titanium oxide. When titanium is exposed to He plasmas, various morphology changes occur as forming nano-bubbles near the surface. Photocatalytic activity of the oxidized helium plasma irradiated titanium samples with nano-cones and microstructures were assessed by the hydrogen production from aqueous methanol solution. It is shown that the He plasma irradiation increases the photocatalytic activity more than double. Moreover, nitrogen mixture plasma irradiation to titanium (oxide) was conducted for doping nitrogen, which has been regarded as method to create visible light reactivity. It is shown from X-ray photoelectron spectroscopy (XPS) analysis that nitrogen doping has been successfully conducted under specific conditions.

  20. Hyaluronan production enhances shedding of plasma membrane-derived microvesicles.

    PubMed

    Rilla, Kirsi; Pasonen-Seppänen, Sanna; Deen, Ashik J; Koistinen, Ville V T; Wojciechowski, Sara; Oikari, Sanna; Kärnä, Riikka; Bart, Genevieve; Törrönen, Kari; Tammi, Raija H; Tammi, Markku I

    2013-08-01

    Many cell types secrete plasma membrane-bound microvesicles, suggested to play an important role in tissue morphogenesis, wound healing, and cancer spreading. However, the mechanisms of their formation have remained largely unknown. It was found that the tips of long microvilli induced in cells by overexpression of hyaluronan synthase 3 (HAS3) were detach into the culture medium as microvesicles. Moreover, several cell types with naturally active hyaluronan synthesis released high numbers of plasma membrane-derived vesicles, and inhibition of hyaluronan synthesis reduced their formation. The vesicles contained HAS, and were covered with a thick hyaluronan coat, a part of which was retained even after purification with high-speed centrifugation. HAS3 overexpressing MDCK cells cultured in a 3-D matrix as epithelial cysts released large amounts of HAS- and hyaluronan-positive vesicles from their basal surfaces into the extracellular matrix. As far as we know, hyaluronan synthesis is one of the first molecular mechanisms shown to stimulate the production of microvesicles. The microvesicles have a potential to deliver the hyaluronan synthase machinery and membrane and cytoplasmic materials to other cells, influencing tissue regeneration, inflammation and tumor progression.

  1. Enhancement of Limb Growth by Non-Thermal Plasma Generated Reactive Species

    NASA Astrophysics Data System (ADS)

    Shainsky, N.; Steinbeck, M.; Fridman, G.; Fridman, A.; Friedman, G.; Freeman, T.

    2013-09-01

    Introduction: The goal of this investigation was to examine the effect of Dielectric Barrier Discharge plasma on mouse autopod differentiation and growth. In this study we hypothesized that NT-plasma can be used to promote redox dependent changes in differentiation pathways and enhance developmental signaling? Methods: Approximately 1 hour after isolation, NT-plasma or sham plasma treatment was applied to the right or left limb, respectively. The medium was changed daily thereafter for the 4-6 days of culture. NT-plasma treatment: pulsed (1000 Hz) voltage of 17 - 25 kV magnitude (peak to peak), a 1 μs pulse width and a rise time of 5 V/ns between the quartz-insulated high voltage electrode and the sample undergoing treatment. Results: A single 10 second NT-plasma treatment promoted development of mouse autopods as compared to the sham control contralateral limb. NT-plasma accelerated digit growth in both E14.5 and E12.5 autopods. Inhibitors were used to determine the role of ROS and RNS in mediating NT-plasma accelerated autopod development. Treatment with these agents stunted autopod morphogenesis NT-plasma treatment partially rescued development. Discussion: Our findings highlight the capability of NT-plasma to activate ROS-dependent cell signaling cascades within developing autopod tissue. In fact, the effect of NT-plasma may indeed extend beyond ROS sensitive signaling as NT-plasma exposure seems to stimulate some growth even in the presence of antioxidant induced stunting. This work was supported by NIH Grants 1 R01 EB 013011 - 01 (Freeman and G. Fridman).

  2. Variation of antioxidative activity and growth enhancement of Brassicaceae induced by low-pressure oxygen plasma

    NASA Astrophysics Data System (ADS)

    Ono, Reoto; Hayashi, Nobuya

    2015-06-01

    The mechanism of growth enhancement induced by active oxygen species generated in an oxygen plasma is investigated. The plant growth enhancement induced by the active oxygen species would relate to an antioxidative activity, which is one of the biological responses. The amount of generated active oxygen species is varied by the oxygen gas pressure in a low-pressure RF glow discharge plasma. The antioxidative activity of sprouts of Brassicaceae induced by the oxygen plasma is maximized at pressures between 30 and 40 Pa, whereas the antioxidative activity becomes small at around 60 and 80 Pa. The pressure dependence of the antioxidative activity of sprout stems is opposite to that of the stem length of the sprouts. The growth enhancement would be induced by the increase in the concentration of active oxygen species in plants owing to the decrease in the amount of antioxidative substances.

  3. Enhanced electromagnetic emission from plasmas containing positive dust grains and electrons

    NASA Astrophysics Data System (ADS)

    Shukla, P. K.; Shukla, Nitin; Stenflo, L.

    2007-05-01

    Large amplitude high-frequency (HF) electromagnetic (EM) waves can scatter off dust-acoustic waves in plasmas containing positive dust grains and electrons, and can thus be responsible for HF enhanced electromagnetic emissions (EEE). An expression for the ensemble average of the squared HF-EEE vector potential is therefore derived, following the standard parametric interaction formalism and adopting the Rostoker superposition principle. The results should be useful for deducing the dust plasma parameters (e.g. the dust number density and dust charge) in situ, and HF intense EM beams can thus be used for diagnosis of positive dust-electron plasmas in space and laboratories.

  4. Enhancement of NOx and hydrocarbon conversion in plasma-activated catalysis

    NASA Astrophysics Data System (ADS)

    Graham, Bill; Adress, Wahmeed; Goguet, Alexandre; Yang, Hui; De Rosa, Fabio; Hardacre, Christopher; Stere, Cristina

    2016-09-01

    Atmospheric pressure, non-thermal plasma-activated-catalysis is showing real promise in a number of applications. Here we report on how electrical, visible and FTIR spectroscopy and mass spectroscopy measurements in a kHz atmospheric pressure He plasma jet coupled with a Ag/Al2O3 catalyst allowed us produce and confirm a strong enhancement of both NOx and hydrocarbon conversion at a measured gas temperature of <= 250° C. How these and other measurements have provided an insight into the fundamental physical and chemical processes in the plasma environment that have helped us move to a more efficient system and other processes will be discussed.

  5. Extension of Plasma Source Ion Implantation to Ion Beam Enhanced Deposition

    DTIC Science & Technology

    1989-10-05

    22, 90 (1989). Nitriding/ Carburizing , Cincinnati, Ohio, Septem- 51. M. A. Lieberman, "Model of Plasma Immersion Ion ber 16-20, 1989. Implantation...TYPE AND OATES COVERED 1990 Final I Feb 89 - 31 Jul 89 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Extension of Plasma Source Ion Implantation to Ion Beam...UL NSN 7540-01.280-5500 Standard Form 298 (Rev 2-89) *’@Krab OV ANSI St 139-IS t9-0 Extension of Plasma Source Ion Implantation to Ion Beam Enhanced

  6. Atmospheric pressure plasma enhanced spatial ALD of silver

    SciTech Connect

    Bruele, Fieke J. van den Smets, Mireille; Illiberi, Andrea; Poodt, Paul; Buskens, Pascal; Roozeboom, Fred

    2015-01-15

    The authors have investigated the growth of thin silver films using a unique combination of atmospheric process elements: spatial atomic layer deposition and an atmospheric pressure surface dielectric barrier discharge plasma source. Silver films were grown on top of Si substrates with good purity as revealed by resistivity values as low as 18 μΩ cm and C- and F-levels below detection limits of energy dispersive x-ray analysis. The growth of the silver films starts through the nucleation of islands that subsequently coalesce. The authors show that the surface island morphology is dependent on surface diffusion, which can be controlled by temperature within the deposition temperature range of 100–120 °C.

  7. Remote sensing of the Io torus plasma ribbon using natural radio occultation of the Jovian radio emissions

    NASA Astrophysics Data System (ADS)

    Boudjada, M. Y.; Galopeau, P. H. M.; Sawas, S.; Lammer, H.

    2014-09-01

    We study the Jovian hectometric (HOM) emissions recorded by the RPWS (Radio and Plasma Wave Science) experiment onboard the Cassini spacecraft during its Jupiter flyby. We analyze the attenuation band associated with the intensity extinction of HOM radiation. This phenomenon is interpreted as a refraction effect of the Jovian hectometric emission inside the Io plasma torus. This attenuation band was regularly observed during periods of more than 5 months, from the beginning of October 2000 to the end of March 2001. We estimate for this period the variation of the electron density versus the central meridian longitude (CML). We find a clear local time dependence. Hence the electron density was not higher than 5.0 × 104 cm-3 during 2 months, when the spacecraft approached the planet on the dayside. In the late afternoon and evening sectors, the electron density increases to 1.5 × 105 cm-3 and reach a higher value at some specific occasions. Additionally, we show that ultraviolet and hectometric wavelength observations have common features related to the morphology of the Io plasma torus. The maxima of enhancements/attenuations of UV/HOM observations occur close to the longitudes of the tip of the magnetic dipole in the southern hemisphere (20° CML) and in the northern hemisphere (200° CML), respectively. This is a significant indication about the importance of the Jovian magnetic field as a physical parameter in the coupling process between Jupiter and the Io satellite.

  8. Preliminary Investigation of High-K Materials -Tio2 Doped Ta2o5 Films by Remote Plasma Ald

    NASA Astrophysics Data System (ADS)

    Fang, Q.; Hodson, C.; Liu, M.; Fang, Z. W.; Potter, R.; Gunn, R.

    (TiO2)x(Ta2O5)1-x (x is up to 0.45) films deposited by a remote plasma atomic layer deposition (ALD) are reported in this work. The growth rates of the ALD films measured by ellipsometer are in a range of 0.8 - 1.06 Å/cycle at a deposition temperature of 300°C, depending on Ti/(Ti+Ta) ratio. In order to evaluate the high-k materials of Ti-doped Ta2O5 films, EDX and AES were used for determining the composition of the films. The thickness and optical properties of the films were measured by a spectral ellipsometer and CV-measurement was applied for testing the electrical property of the film. Furthermore, the effects of thermal annealing and in-situ O2-oxidation on thickness, refractive index and electrical property of (TiO2)x(Ta2O5)1-x films are also discussed.

  9. A Service-Learning Immersion in a Remote Aboriginal Community: Enhancing Pre-Service Teacher Education

    ERIC Educational Resources Information Center

    Lavery, Shane; Cain, Glenda; Hampton, Patrick

    2014-01-01

    This article examines a service-learning immersion undertaken by pre-service primary teachers in a remote indigenous community and school in Western Australia. The article initially presents the purpose and significance for the immersion in the light of the Australian National Professional Standards for Teachers. The article subsequently outlines…

  10. Gas Diffusion Barriers Prepared by Spatial Atmospheric Pressure Plasma Enhanced ALD.

    PubMed

    Hoffmann, Lukas; Theirich, Detlef; Pack, Sven; Kocak, Firat; Schlamm, Daniel; Hasselmann, Tim; Fahl, Henry; Räupke, André; Gargouri, Hassan; Riedl, Thomas

    2017-02-01

    In this work, we report on aluminum oxide (Al2O3) gas permeation barriers prepared by spatial ALD (SALD) at atmospheric pressure. We compare the growth characteristics and layer properties using trimethylaluminum (TMA) in combination with an Ar/O2 remote atmospheric pressure plasma for different substrate velocities and different temperatures. The resulting Al2O3 films show ultralow water vapor transmission rates (WVTR) on the order of 10(-6) gm(-2)d(-1). In notable contrast, plasma based layers already show good barrier properties at low deposition temperatures (75 °C), while water based processes require a growth temperature above 100 °C to achieve equally low WVTRs. The activation energy for the water permeation mechanism was determined to be 62 kJ/mol.

  11. Modeling the transition of the inner plasma sheet from weak to enhanced convection

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Ping; Lyons, Larry R.; Chen, Margaret W.; Toffoletto, Frank R.

    2004-12-01

    We seek to determine whether the adiabatic plasma transport and energization resulting from electric and magnetic drift can quantitatively account for the plasma sheet under weak and enhanced convection observed by Geotail presented in the companion paper [, 2004]. We use a modified Magnetospheric Specification Model to simulate the dynamics and distributions of protons originating from the deep tail and low-latitude boundary layer (LLBL) under an assigned, slowly increasing convection electric field. The magnetic field is Tsyganenko 96 model, modified so that force balance is maintained along the midnight meridian. Our simulation results reproduce well the observed radial profiles and magnitudes of pressure and magnetic field. The changes of these parameters with convection strength are also well reproduced, indicating that the electric and magnetic drift control the large-scale structure of the plasma sheet. The plasma flows near midnight are diverted toward dusk by diamagnetic drift. We obtain a steady state plasma sheet under strong and steady convection, showing that magnetic drift and field line stretching bring the plasma sheet away from possible convection disruption. The protons from the LLBL strongly affect the plasma sheet density and temperature during quiet times but not during enhanced convection. For the same cross-polar cap potential, stronger shielding of the convection electric field results in smaller energization. The penetration electric field is important in moving the plasma sheet to smaller geocentric radial distance. Our results suggest that the frozen-in condition E = -v × B is not valid in the inner plasma sheet because of strong diamagnetic drift.

  12. Control of interface nanoscale structure created by plasma-enhanced chemical vapor deposition.

    PubMed

    Peri, Someswara R; Akgun, Bulent; Satija, Sushil K; Jiang, Hao; Enlow, Jesse; Bunning, Timothy J; Foster, Mark D

    2011-09-01

    Tailoring the structure of films deposited by plasma-enhanced chemical vapor deposition (PECVD) to specific applications requires a depth-resolved understanding of how the interface structures in such films are impacted by variations in deposition parameters such as feed position and plasma power. Analysis of complementary X-ray and neutron reflectivity (XR, NR) data provide a rich picture of changes in structure with feed position and plasma power, with those changes resolved on the nanoscale. For plasma-polymerized octafluorocyclobutane (PP-OFCB) films, a region of distinct chemical composition and lower cross-link density is found at the substrate interface for the range of processing conditions studied and a surface layer of lower cross-link density also appears when plasma power exceeds 40 W. Varying the distance of the feed from the plasma impacts the degree of cross-linking in the film center, thickness of the surface layer, and thickness of the transition region at the substrate. Deposition at the highest power, 65 W, both enhances cross-linking and creates loose fragments with fluorine content higher than the average. The thickness of the low cross-link density region at the air interface plays an important role in determining the width of the interface built with a layer subsequently deposited atop the first.

  13. Experimental investigation of lift enhancement for flying wing aircraft using nanosecond DBD plasma actuators

    NASA Astrophysics Data System (ADS)

    Junkai, YAO; Danjie, ZHOU; Haibo, HE; Chengjun, HE; Zhiwei, SHI; Hai, DU

    2017-04-01

    The effects of the arrangement position and control parameters of nanosecond dielectric barrier discharge (NS-DBD) plasma actuators on lift enhancement for flying wing aircraft were investigated through wind tunnel experiments at a flow speed of 25 m s‑1. The aerodynamic forces and moments were obtained by a six-component balance at angles of attack ranging from ‑4° to 28°. The lift, drag and pitching moment coefficients were compared for the cases with and without plasma control. The results revealed that the maximum control effect was achieved by placing the actuator at the leading edge of the inner and middle wing, for which the maximum lift coefficient increased by 37.8% and the stall angle of attack was postponed by 8° compared with the plasma-off case. The effects of modulation frequency and discharge voltage were also investigated. The results revealed that the lift enhancement effect of the NS-DBD plasma actuators was strongly influenced by the modulation frequency. Significant control effects were obtained at f = 70 Hz, corresponding to F + ≈ 1. The result for the pitching moment coefficient demonstrated that the plasma actuator can induce the reattachment of the separation flows when it is actuated. However, the results indicated that the discharge voltage had a negligible influence on the lift enhancement effect.

  14. Removal of seminal plasma enhances membrane stability on fresh and cooled stallion spermatozoa.

    PubMed

    Barrier-Battut, I; Bonnet, C; Giraudo, A; Dubois, C; Caillaud, M; Vidament, M

    2013-02-01

    Fertility is reduced after semen cooling for a considerable number of stallions. The main hypotheses include alterations in plasma membrane following cooling and deleterious influence of seminal plasma. However, interindividual variability is controversial. We hypothesized that the removal of seminal plasma could enhance motility in some 'poor cooler' stallions, but could also affect, negatively or positively, membrane quality in some stallions. This study examined the effect of centrifugation, followed or not by removal of seminal plasma, on parameters indicating semen quality after 48 h at 4 °C: motility, plasma membrane integrity as evaluated by hypo-osmotic swelling test, acrosome integrity and response to a pharmacological induction of acrosome reaction using ionophore A23187. Sixty-six ejaculates from 14 stallions were used, including stallions showing high or low sperm motility after cooled storage. Centrifugation without removal of seminal plasma did not affect sperm parameters. Removal of seminal plasma did not affect motility, but significantly stabilized sperm membranes, as demonstrated by a higher response to the osmotic challenge, and a reduced reactivity of the acrosome. Moreover, for the same semen sample, the response to an induction of acrosome reaction was significantly higher when the induction was performed in the presence of seminal plasma, compared with the induction in the absence of seminal plasma. This was observed both for fresh and cooled semen. When the induction of acrosome reaction with ionophore A23187 is used to evaluate sperm quality, care must therefore be taken to standardize the proportion of seminal plasma between samples. For the 10 stallions serving at least 25 mares, the only variable significantly correlated with fertility was motility. The influence of membrane stabilization regarding fertility requires further investigations.

  15. Localized microwave pulsed plasmas for ignition and flame front enhancement

    NASA Astrophysics Data System (ADS)

    Michael, James Bennett

    Modern combustor technologies require the ability to match operational parameters to rapidly changing demands. Challenges include variable power output requirements, variations in air and fuel streams, the requirement for rapid and well-controlled ignition, and the need for reliability at low fuel mixture fractions. Work on subcritical microwave coupling to flames and to weakly ionized laser-generated plasmas has been undertaken to investigate the potential for pulsed microwaves to allow rapid combustion control, volumetric ignition, and leaner combustion. Two strategies are investigated. First, subcritical microwaves are coupled to femtosecond laser-generated ionization to ignite methane/air mixtures in a quasi-volumetric fashion. Total energy levels are comparable to the total minimum ignition energies for laser and spark discharges, but the combined strategy allows a 90 percent reduction in the required laser energy. In addition, well-defined multi-dimensional ignition patterns are designated with multiple laser passes. Second, microwave pulse coupling to laminar flame fronts is achieved through interaction with chemiionization-produced electrons in the reaction zone. This energy deposition remains well-localized for a single microwave pulse, resulting in rapid temperature rises of greater than 200 K and maintaining flame propagation in extremely lean methane/air mixtures. The lean flammability limit in methane/air mixtures with microwave coupling has been decreased from an equivalence ratio 0.6 to 0.3. Additionally, a diagnostic technique for laser tagging of nitrogen for velocity measurements is presented. The femtosecond laser electronic excitation tagging (FLEET) technique utilizes a 120 fs laser to dissociate nitrogen along a laser line. The relatively long-lived emission from recombining nitrogen atoms is imaged with a delayed and fast-gated camera to measure instantaneous velocities. The emission strength and lifetime in air and pure nitrogen allow

  16. Evolution of plasma parameters in an Ar-N2/He inductive plasma source with magnetic pole enhancement

    NASA Astrophysics Data System (ADS)

    Maria, Younus; N, U. Rehman; M, Shafiq; M, Naeem; M, Zaka-Ul-Islam; M, Zakaullah

    2017-02-01

    Magnetic pole enhanced inductively coupled plasmas (MaPE-ICPs) are a promising source for plasma-based etching and have a wide range of material processing applications. In the present study Langmuir probe and optical emission spectroscopy were used to monitor the evolution of plasma parameters in a MaPE-ICP Ar-N2/He mixture plasma. Electron density ({n}{{e}}) and temperature ({T}{{e}}), excitation temperature ({T}{{exc}}), plasma potential ({V}{{p}}), skin depth (δ ) and the evolution of the electron energy probability function (EEPF) are reported as a function of radiofrequency (RF) power, pressure and argon concentration in the mixture. It is observed that {n}{{e}} increases while {T}{{e}} decreases with increase in RF power and argon concentration in the mixture. The emission intensity of the argon line at 750.4 nm is also used to monitor the variation of the ‘high-energy tail’ of the EEPF with RF power and gas pressure. The EEPF has a ‘bi-Maxwellian’ distribution at low RF powers and higher pressure in a pure {{{N}}}2 discharge. However, it evolves into a ‘Maxwellian’ distribution at RF powers greater than 70 W for pure {{{N}}}2, and at 50 W for higher argon concentrations in the mixture. The effect of argon concentration on the temperatures of two electron groups in the ‘bi-Maxwellian’ EEPF is examined. The temperature of the low-energy electron group {T}{{L}} shows a decreasing trend with argon addition until the ‘thermalization’ of the two temperatures occurs, while the temperature of high-energy electrons {T}{{H}} decreases continuously.

  17. Plasma-Enhanced Chemical Vapor Deposition of SiOx Films Using Electron Beam Generated Plasmas

    DTIC Science & Technology

    2009-09-28

    special relation to the substrate or e-beam. A total flow of 100 sccm was used in all cases . For the gas flows mentioned above, the individual flows...beam generated plasmas. In this case , molecular hydrogen, formed primarily by recombination of atomic hydrogen on system walls, will not be...the films was large (> 130 nm/min), which implied a high porosity for all cases except for low TEOS flow (≤ 2 sccm) at the higher (300 °C) temperature

  18. Growing aluminum nitride films by Plasma-Enhanced Atomic Layer Deposition at low temperatures

    NASA Astrophysics Data System (ADS)

    Tarala, V. A.; Altakhov, A. S.; Martens, V. Ya; Lisitsyn, S. V.

    2015-11-01

    Aluminum nitride films have been grown by Plasma-Enhanced Atomic Layer Deposition method. It was found that at temperatures of 250 °C and 280 °C increase of the plasma exposure step duration over 6 s, as well as increase of reactor purge step duration over 1 s does not affect the growth rate, however, it affects the microstructure of the films. It was found that crystalline aluminum nitride films deposit with plasma exposure duration over 10 s and the reactor purging over 10 s. When the temperature drops the increase of reactor purge step duration and plasma exposure step duration over 20 s is required for crystalline AlN film growth.

  19. Patterning and Characterization of Carbon Nanotubes Grown in a Microwave Plasma Enhanced Chemical Vapor Deposition Chamber

    DTIC Science & Technology

    2009-03-01

    determined optically through scanning electron microscope images. carbon nanotubes, field emission, microwave plasma enhanced chemical vapor deposition U U U...PECVD) 13 2.3 Carbon Nanotube Properties . . . . . . . . . . . . . . . 22 2.4 Applications of Carbon Nanotubes . . . . . . . . . . . . 24 2.4.1...Multi-walled Carbon Nanotube . . . . . . . . . . . . . . . 6 TEM Transmission Electron Microscope . . . . . . . . . . . . . 6 SWCNT Single-walled Carbon

  20. Growth enhancement effects of radish sprouts: atmospheric pressure plasma irradiation vs. heat shock

    NASA Astrophysics Data System (ADS)

    Sarinont, T.; Amano, T.; Kitazaki, S.; Koga, K.; Uchida, G.; Shiratani, M.; Hayashi, N.

    2014-06-01

    We compare growth enhancement effects due to atmospheric air dielectric barrier discharge plasma irradiation and heat shock to seeds of radish sprouts (Raphanus sativus L.). Interactions between radicals and seeds in a short duration of 3 min. lead to the growth enhancement of radish sprouts in a long term of 7 days and the maximum average length is 3.7 times as long as that of control. The growth enhancement effects become gradually weak with time, and hence the ratio of the average length for plasma irradiation to that for control decreases from 3.7 for the first day to 1.3 for 7 day. The average length for heat shock of 60°C for 10 min. and 100°C for 3 min. is longer than that for control, and the maximum average length is 1.3 times as long as that of control. Heat shock has little contribution to the growth enhancement due to plasma irradiation, because the maximum temperature due to plasma irradiation is less than 60°C.

  1. Enhancement of KSTAR plasma control for expanding operational space

    NASA Astrophysics Data System (ADS)

    Hahn, Sang-Hee; Jeon, Y. M.; Han, H.; Ahn, H. S.; Kim, J.; Kim, Y. J.; Joung, M.; Woo, M. H.; Mueller, D.; Eidietis, N. W.; Lanctot, M.; Humphreys, D. A.; Hyatt, A. W.; Welander, A. S.; Walker, M. L.; Kolemen, E.; Park, Y. S.; Sabbagh, S. A.

    2015-11-01

    In order to expand the operational space with stationary high performances, new approaches on the magnetic control design are necessary. A few examples on recent achievements at KSTAr are presented here: The Introduction of the in-vessel radial control (IRC) provides a fundamental change on baseline axisymmetric magnetic controls. Analysis on dedicated simulations/experiments for the vertical stabilization control margin gave an insight for improvement of the vertical position control. In order to enhance flexibility on the non-axisymmetric 3D field physics studies, the KSTAR RMP coil systems have been upgraded in 2015 provide more variety on the available 3D field profile. Integration of real-time heating device control enabled more elaborate kinetic controls since 2013. Real-time TM suppression is introduced as an example of the integrated control, which will be linked to stability control in the high-beta regime relevant to ITER success.

  2. Remote use of distributed robotics resources to enhance technology development and insertion

    SciTech Connect

    Harrigan, R.W.; McDonald, M.J.; Davies, B.R.

    1994-04-01

    This paper describes Virtual Collaborative Environments (VCEs), an information architecture that enables remote sharing of mechatronic (intelligent electrochemical devices) resources. This architecture will leverage the proposed National Information Infrastructure (NII) or Information Highway to share valuable resources and reduce product-to-market cycles. Benefits of sharing mechatronic resources with VCEs are explored. An existing prototype VCE is described and experimental and illustrative results from using the prototype VCE system are discussed.

  3. Enhancing psychosocial care for people with cancer in rural communities: what can remote counselling offer?

    PubMed

    Shepherd, Louise; Goldstein, David; Olver, Ian; Parle, Michael

    2008-08-01

    Rural cancer patients are often disadvantaged in access to psychological services. We reviewed remote counselling research for psychological support using telephone, videoconferencing, and the Internet as a potential solution. Telephone counselling is the most extensively researched, while there are encouraging findings in emerging research about videoconferencing and Internet-based psychological care. Where no face-to-face psychological service exists, these technologies are promising, yet unproven. Less variable methods are needed to better assess the technology and therapeutic approach for stronger evidence.

  4. Effects of ROS and RNS in non-equilibrium plasma enhanced oxidizing and nitriding

    NASA Astrophysics Data System (ADS)

    Datsyuk, Vitaly; Izmailov, Igor; Naumov, Vadym; Khomich, Vladimir; Tsiolko, Vyacheslav

    2016-09-01

    Plasma enhanced oxidizing and nitriding processes are of great interest for physics and applications. However, despite all advances in plasma technology, mechanisms of non-equilibrium plasma chemistry are not quite clear, particularly concerning reactive oxygen and nitrogen species (ROS/RNS) in metastable states. We tried to study this matter more detail. Experiments were done in a low temperature magnetron with a non-self-sustained glow discharge in oxygen/nitrogen/argon mixtures, employing electrical and optical diagnostics. Measurements showed that plasma processing is accompanied by the formation of electronically excited particles ROS/RNS. Computer modeling by using 0D-kinetic and 1D-fluid models including ionization, excitation, dissociation-recombination, vibrational relaxation, collisional quenching and radiation revealed the most probable mechanisms of plasma-chemical transformations. Effects of metastables of singlet oxygen O2*(a,b)and nitrogen N2*(A)as well as small but important radicals O*(1 D), N*(2 D) were also examined. Our study confirms the role of ROS/RNS in plasma kinetics and indicates the way toward more efficient oxygen and nitrogen plasma processing.

  5. Cavity-enhanced absorption spectroscopy to characterize atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    van Helden, Jean-Pierre; Nave, Andy; Reuter, Stephan; Roepcke, Juergen; Gianella, Michele; Ritchie, Grant

    2016-09-01

    Non-equilibrium atmospheric pressure plasma jets gain more and more interest as their technological applications increase in diverse fields such as material processing and plasma medicine. Hence, it is essential to diagnose the fluxes of the species generated by these plasma sources to identify relevant fundamental processes and to improve process efficiency. Especially for a comprehensive understanding of the kinetics of the transient species involved, high precision measurements of reactive molecular precursors, free radicals and to identify of any short lived species are of crucial importance. However, the detection of transient species in these type of plasmas poses a challenge for diagnostic techniques as the plasmas typically have small dimensions and high density gradients in space and time. We have overcome these limitations by using cavity-enhanced absorption spectroscopy (CEAS). In this contribution, the latest results concerning the detection of transient species in two types of plasma jets employing CEAS in the near- and mid-infrared spectral range will be presented. We will show that with these methods spatially resolved investigations of concentrations in the mm sized effluent of the plasma jet can be achieved.

  6. Enhanced electrocatalytic activity of CoTMPP-based catalysts for PEMFCs by plasma treatment

    NASA Astrophysics Data System (ADS)

    Savastenko, N. A.; Brüser, V.; Brüser, M.; Anklam, K.; Kutschera, S.; Steffen, H.; Schmuhl, A.

    In this work, we developed a methodology of plasma-enhanced preparation of CoTMPP (tetramethoxyphenylporphyrin)-based electrocatalysts. A series of CoTMPP-based electrocatalysts were deposited on the porous gas diffusion substrate (titanium fibre felt) using plasma-enhanced impregnation method. Impregnated 1.5 mg cm -2 CoTMPP/Ti catalysts were treated by dielectric barrier discharge (DBD) plasma in Ar or N 2 atmosphere. Additionally, the pretreatment methods were utilized to improve the adhesion of CoTMPP on the diffusion layer surface. The plasma pretreatment methods included the a-C:H-layers deposition followed by an Ar:O 2 radio frequency (RF) plasma functionalization. The latter approach led to the formation of specific oxygen surface groups that influenced the catalysts activity. Obtained catalysts were compared in terms of activity, stability and structure. The catalytic activity for hydrogen peroxide (H 2O 2) reduction was tested in a proton exchange membrane fuel cell (PEMFC) using hydrogen peroxide on the cathode side. Surface elemental analysis and structure of catalysts were examined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Our contribution shows the potential of a plasma treatment in the preparation of electrocatalysts for hydrogen peroxide reduction reaction in a PEMFC. Under the conditions of this study, improvement of the PEMFC performance up to 30% was achievable by a deposition of CoTMPP on the titanium diffusion substrate followed by plasma treatment. The large differences in catalytic activity of CoTMPP/Ti were observed, depending on the plasma treatment applied to the catalysts during their preparation.

  7. Security analysis and enhancements of an effective biometric-based remote user authentication scheme using smart cards.

    PubMed

    An, Younghwa

    2012-01-01

    Recently, many biometrics-based user authentication schemes using smart cards have been proposed to improve the security weaknesses in user authentication system. In 2011, Das proposed an efficient biometric-based remote user authentication scheme using smart cards that can provide strong authentication and mutual authentication. In this paper, we analyze the security of Das's authentication scheme, and we have shown that Das's authentication scheme is still insecure against the various attacks. Also, we proposed the enhanced scheme to remove these security problems of Das's authentication scheme, even if the secret information stored in the smart card is revealed to an attacker. As a result of security analysis, we can see that the enhanced scheme is secure against the user impersonation attack, the server masquerading attack, the password guessing attack, and the insider attack and provides mutual authentication between the user and the server.

  8. Chip, a widely expressed chromosomal protein required for segmentation and activity of a remote wing margin enhancer in Drosophila

    PubMed Central

    Morcillo, Patrick; Rosen, Christina; Baylies, Mary K.; Dorsett, Dale

    1997-01-01

    The mechanisms allowing remote enhancers to regulate promoters several kilobase pairs away are unknown but are blocked by the Drosophila suppressor of Hairy-wing protein (Suhw) that binds to gypsy retrovirus insertions between enhancers and promoters. Suhw bound to a gypsy insertion in the cut gene also appears to act interchromosomally to antagonize enhancer–promoter interactions on the homologous chromosome when activity of the Chip gene is reduced. This implicates Chip in enhancer–promoter communication. We cloned Chip and find that it encodes a homolog of the recently discovered mouse Nli/Ldb1/Clim-2 and Xenopus Xldb1 proteins that bind nuclear LIM domain proteins. Chip protein interacts with the LIM domains in the Apterous homeodomain protein, and Chip interacts genetically with apterous, showing that these interactions are important for Apterous function in vivo. Importantly, Chip also appears to have broad functions beyond interactions with LIM domain proteins. Chip is present in all nuclei examined and at numerous sites along the salivary gland polytene chromosomes. Embryos without Chip activity lack segments and show abnormal gap and pair–rule gene expression, although no LIM domain proteins are known to regulate segmentation. We conclude that Chip is a ubiquitous chromosomal factor required for normal expression of diverse genes at many stages of development. We suggest that Chip cooperates with different LIM domain proteins and other factors to structurally support remote enhancer–promoter interactions. PMID:9334334

  9. Modeling the inner plasma sheet pressure and magnetic field under enhanced convection

    NASA Astrophysics Data System (ADS)

    Wang, C.; Lyons, L.; Chen, M.; Wolf, R.

    In order to understand the evolution of the proton pressure and magnetic field in the inner plasma sheet from quiet to disturbed times, we incorporate a modified version of the Magnetospheric Specification Model with a modified version of the Tsyganenko 96 magnetic field model to self-consistently simulate protons and magnetic field under an increasing convection electric field with two-dimensional force balance maintained along the midnight meridian. The local-time dependent proton differential fluxes assigned to the model boundary are mixture of hot plasma from the distant tail and cooler plasma from the low latitude boundary layer and are constructed based on Geotail observations and the results of the finite-tail-width- convection model. We previously used this model to simulate the inner plasma sheet under weak convection corresponding to a cross polar-cap potential drop ( PC) equal to 26 kV and obtained two-dimensional quiet time equilibrium for proton and magnetic field that agrees well with observations both qualitatively and quantitatively. We start our simulation for enhanced convection with this quiet time equilibrium and time independent boundary particle sources and increase thePC steadily from 26 kV to 146 kV in 5 hours. The simulations are also run to steady states separately by keepingP C constant after it is increased to 98 and to 146 kV. The magnitude of the simulated proton pressure and its increase from quiet to moderate activity ( P C = 98 kV) are consistent with most observations. Our results at high activity (P C = 146 kV) underestimate the observed pressure, a disagreement that indicates possible dependence of the boundary particle sources on activity. The pressure equatorial profiles show a dawn dusk asymmetry as a result of stronger enhancement on the dusk side than on the dawn side as convection is increased. The equatorial m gnetic field strength decreases more in the near-Eartha plasma sheet than at larger radial distances as theP C

  10. Enhanced electron-hole plasma stimulated emission in optically pumped gallium nitride nanopillars

    NASA Astrophysics Data System (ADS)

    Lo, M.-H.; Cheng, Y.-J.; Kuo, H.-C.; Wang, S.-C.

    2011-03-01

    An enhanced stimulated emission was observed in optically pumped GaN nanopillars. The nanopillars were fabricated from an epitaxial wafer by patterned pillar etching followed by crystalline regrowth. Under optical excitation, a strong redshifted stimulated emission peak emerged from a broad spontaneous emission background. The emission is attributed to the electron-hole plasma gain at high carrier density. The emission slope efficiency was greatly enhanced by 20 times compared with a GaN substrate under the same pumping condition. The enhancement is attributed to the better photon and gain interaction from the multiple scattering of photons among nanopillars.

  11. Enhancement of Fluorescence-Based Sandwich Immunoassay Using Multilayered Microplates Modified with Plasma-Polymerized Films.

    PubMed

    Yano, Kazuyoshi; Iwasaki, Akira

    2016-12-25

    A functional modification of the surface of a 96-well microplate coupled with a thin layer deposition technique is demonstrated for enhanced fluorescence-based sandwich immunoassays. The plasma polymerization technique enabling the deposition of organic thin films was employed for the modification of the well surface of a microplate. A silver layer and a plasma-polymerized film were consecutively deposited on the microplate as a metal mirror and the optical interference layer, respectively. When Cy3-labeled antibody was applied to the wells of the resulting multilayered microplate without any immobilization step, greatly enhanced fluorescence was observed compared with that obtained with the unmodified one. The same effect could be also exhibited for an immunoassay targeting antigen directly adsorbed on the multilayered microplate. Furthermore, a sandwich immunoassay for the detection of interleukin 2 (IL-2) was performed with the multilayered microplates, resulting in specific and 88-fold-enhanced fluorescence detection.

  12. Enhancement of plasma illumination characteristics of few-layer graphene-diamond nanorods hybrid

    NASA Astrophysics Data System (ADS)

    Jothiramalingam Sankaran, Kamatchi; Yeh, Chien-Jui; Drijkoningen, Sien; Pobedinskas, Paulius; Van Bael, Marlies K.; Leou, Keh-Chyang; Lin, I.-Nan; Haenen, Ken

    2017-02-01

    Few-layer graphene (FLG) was catalytically formed on vertically aligned diamond nanorods (DNRs) by a high temperature annealing process. The presence of 4-5 layers of FLG on DNRs was confirmed by transmission electron microscopic studies. It enhances the field electron emission (FEE) behavior of the DNRs. The FLG-DNRs show excellent FEE characteristics with a low turn-on field of 4.21 V μm-1 and a large field enhancement factor of 3480. Moreover, using FLG-DNRs as cathode markedly enhances the plasma illumination behavior of a microplasma device, viz not only the plasma current density is increased, but also the robustness of the devices is improved.

  13. Enhancement of plasma illumination characteristics of few-layer graphene-diamond nanorods hybrid.

    PubMed

    Sankaran, Kamatchi Jothiramalingam; Yeh, Chien-Jui; Drijkoningen, Sien; Pobedinskas, Paulius; Van Bael, Marlies K; Leou, Keh-Chyang; Lin, I-Nan; Haenen, Ken

    2017-02-10

    Few-layer graphene (FLG) was catalytically formed on vertically aligned diamond nanorods (DNRs) by a high temperature annealing process. The presence of 4-5 layers of FLG on DNRs was confirmed by transmission electron microscopic studies. It enhances the field electron emission (FEE) behavior of the DNRs. The FLG-DNRs show excellent FEE characteristics with a low turn-on field of 4.21 V μm(-1) and a large field enhancement factor of 3480. Moreover, using FLG-DNRs as cathode markedly enhances the plasma illumination behavior of a microplasma device, viz not only the plasma current density is increased, but also the robustness of the devices is improved.

  14. Enhancement of Fluorescence-Based Sandwich Immunoassay Using Multilayered Microplates Modified with Plasma-Polymerized Films

    PubMed Central

    Yano, Kazuyoshi; Iwasaki, Akira

    2016-01-01

    A functional modification of the surface of a 96-well microplate coupled with a thin layer deposition technique is demonstrated for enhanced fluorescence-based sandwich immunoassays. The plasma polymerization technique enabling the deposition of organic thin films was employed for the modification of the well surface of a microplate. A silver layer and a plasma-polymerized film were consecutively deposited on the microplate as a metal mirror and the optical interference layer, respectively. When Cy3-labeled antibody was applied to the wells of the resulting multilayered microplate without any immobilization step, greatly enhanced fluorescence was observed compared with that obtained with the unmodified one. The same effect could be also exhibited for an immunoassay targeting antigen directly adsorbed on the multilayered microplate. Furthermore, a sandwich immunoassay for the detection of interleukin 2 (IL-2) was performed with the multilayered microplates, resulting in specific and 88-fold–enhanced fluorescence detection. PMID:28029144

  15. Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF{sub 6} based plasmas

    SciTech Connect

    Perros, Alexander; Bosund, Markus; Sajavaara, Timo; Laitinen, Mikko; Sainiemi, Lauri; Huhtio, Teppo; Lipsanen, Harri

    2012-01-15

    The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 deg. C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF{sub 6} and O{sub 2} under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film's removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film removal because the film was inert to the SF{sub x}{sup +} and O{sup +} chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF{sub 6} based plasma etch applications, such as through-wafer etching, or when oxide films are not suitable.

  16. Rice (Oryza sativa L.) Seed Sterilization and Germination Enhancement via Atmospheric Hybrid Nonthermal Discharge Plasma.

    PubMed

    Khamsen, Natthaporn; Onwimol, Damrongvudhi; Teerakawanich, Nithiphat; Dechanupaprittha, Sanchai; Kanokbannakorn, Weerawoot; Hongesombut, Komsan; Srisonphan, Siwapon

    2016-08-03

    We designed a system to produce atmospheric hybrid cold-discharge plasma (HCP) based on microcorona discharge on a single dielectric barrier and applied it to inactivate microorganisms that commonly attach the rice seed husk. The cold-plasma treatment modified the surface of the rice seeds, resulting in accelerated germination and enhanced water imbibition. The treatment can operate under air-based ambient conditions without the need for a vacuum. The cold-plasma treatment completely inactivated pathogenic fungi and other microorganisms, enhancing the germination percentage and seedling quality. The final germination percentage of the treated rice seeds was ∼98%, whereas that of the nontreated seeds was ∼90%. Microcorona discharge on a single dielectric barrier provides a nonaggressive cold plasma that can be applied to organic materials without causing thermal and electrical damage. The hybrid nonthermal plasma is cost effective and consumes relatively little power, making it suitable for the surface sterilization and disinfection of organic and biological materials with large-scale compatibility.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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.

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

    PubMed

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

    2016-07-01

    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.

  19. 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

  20. Enhancing Remotely Sensed TIR Data for Public Health Applications: Is West Nile Virus Heat-Related?

    NASA Astrophysics Data System (ADS)

    Weng, Q.; Liu, H.; Jiang, Y.

    2014-12-01

    Public health studies often require thermal infrared (TIR) images at both high temporal and spatial resolution to retrieve LST. However, currently, no single satellite sensors can deliver TIR data at both high temporal and spatial resolution. This technological limitation prevents the wide usage of remote sensing data in epidemiological studies. To solve this issue, we have developed a few image fusion techniques to generate high temporally-resolved image data. We downscaled GOES LST data to 15-minute 1-km resolution to assess community-based heat-related risk in Los Angeles County, California and simulated ASTER datasets by fusing ASTER and MODIS data to derive biophysical variables, including LST, NDVI, and normalized difference water index, to examine the effects of those environmental characteristics on WNV outbreak and dissemination. A spatio-temporal analysis of WNV outbreak and dissemination was conducted by synthesizing the remote sensing variables and mosquito surveillance data, and by focusing on WNV risk areas in July through September due to data sufficiency of mosquito pools. Moderate- and high-risk areas of WNV infections in mosquitoes were identified for five epidemiological weeks. These identified WNV-risk areas were then collocated in GIS with heat hazard, exposure, and vulnerability maps to answer the question of whether WNV is a heat related virus. The results show that elevation and built-up conditions were negatively associated with the WNV propagation, while LST positively correlated with the viral transmission. NDVI was not significantly associated with WNV transmission. San Fernando Valley was found to be the most vulnerable to mosquito infections of WNV. This research provides important insights into how high temporal resolution remote sensing imagery may be used to study time-dependant events in public health, especially in the operational surveillance and control of vector-borne, water-borne, or other epidemic diseases.

  1. Improved film quality of plasma enhanced atomic layer deposition SiO{sub 2} using plasma treatment cycle

    SciTech Connect

    Kim, Haiwon; Chung, Ilsub; Kim, Seokyun; Shin, Seungwoo; Jung, Wooduck; Hwang, Ryong; Jeong, Choonsik; Hwang, Hanna

    2015-01-15

    Chemical, physical, and electrical characteristics of high quality silicon dioxide (SiO{sub 2}) films grown using low temperature plasma enhanced atomic layer deposition (PE-ALD) have been investigated as a buffer layer for three dimensional vertical NAND flash memory devices. The comparative angle resolved x-ray photoelectron spectroscopy studies show the plasma treatment cycle causes to shift the core level binding energy (chemical shifts) in the SiO{sub 2} film. The wet etch rates with respect to plasma treatment cycle times were varied due to curing of the SiO{sub 2} network defects by Ar{sup +} ions and oxygen radicals. It is assumed that the angle between the bonds linking SiO{sub 4} tetrahedra is a critical point understanding the variation in wet etch rate of SiO{sub 2}. The features of wet etch rate of low temperature high quality SiO{sub 2} demonstrated lower than high temperature low-pressure chemical vapor deposition (LP-CVD) SiO{sub 2} values. In addition, the better step-coverage compared to that of the LP-CVD SiO{sub 2} film was achieved from the deep trench structure having the 20:1 aspect ratio. PE-ALD SiO{sub 2} with plasma treatment cycle showed excellent I–V properties with higher breakdown voltage compared to LP-CVD SiO{sub 2} and similar to the thermal SiO{sub 2} carrier transport plot.

  2. The role of in situ reforming in plasma enhanced ultra lean premixed methane/air flames

    SciTech Connect

    Kim, Wookyung; Godfrey Mungal, M.; Cappelli, Mark A.

    2010-02-15

    This paper describes a mechanism for the stabilization of ultra lean premixed methane/air flames by pulsed nonequilibrium plasma enhancement. It is shown that the pulsed discharge plasma produces a cool ({proportional_to}500-600 K) stream of relatively stable intermediate species including hydrogen (H{sub 2}) and carbon monoxide (CO), which play a central role in enhancing flame stability. This stream is readily visualized by ultraviolet emission from electronically excited hydroxyl (OH) radicals. The rotational and vibrational temperature of this ''preflame'' are determined from its emission spectrum. Qualitative imaging of the overall flame structure is obtained by planar laser-induced fluorescence measurements of OH. Preflame nitric oxide (NO) concentrations are determined by gas sampling chromatography. A simple numerical model of this plasma enhanced premixed flame is proposed that includes the generation of the preflame through plasma activation, and predicts the formation of a dual flame structure that arises when the preflame serves to pilot the combustion of the surrounding non-activated premixed flow. The calculation represents the plasma through its ability to produce an initial radical yield, which serves as a boundary condition for conventional flame simulations. The simulations also capture the presence of the preflame and the dual flame structure, and predict preflame levels of NO comparable to those measured. A subsequent pseudo-sensitivity analysis of the preflame shows that flame stability is most sensitive to the concentrations of H{sub 2} and CO in the preflame. As a consequence of the role of H{sub 2} and CO in enhancing the flame stability, the blowout limit extensions of methane/air and hydrogen/air mixtures in the absence/presence of a discharge are investigated experimentally. For methane/air mixtures, the blowout limit of the current burner is extended by {proportional_to}10% in the presence of a discharge while comparable studies carried

  3. Plasma enhanced atomic layer batch processing of aluminum doped titanium dioxide

    SciTech Connect

    Lehnert, Wolfgang; Ruhl, Guenther; Gschwandtner, Alexander

    2012-01-15

    Among many promising high-k dielectrics, TiO{sub 2} is an interesting candidate because of its relatively high k value of over 40 and its easy integration into existing semiconductor manufacturing schemes. The most critical issues of TiO{sub 2} are its low electrical stability and its high leakage current density. However, doping TiO{sub 2} with Al has shown to yield significant improvement of layer quality on Ru electrodes [S. K. Kim et al., Adv. Mater. 20, 1429 (2008)]. In this work we investigated if atomic layer deposition (ALD) of Al doped TiO{sub 2} is feasible in a batch system. Electrical characterizations were done using common electrode materials like TiN, TaN, or W. Additionally, the effect of plasma enhanced processing in this reactor was studied. For this investigation a production batch ALD furnace has been retrofitted with a plasma source which can be used for post deposition anneals with oxygen radicals as well as for directly plasma enhanced ALD. After evaluation of several Ti precursors a deposition process for AlTiO{sub x} with excellent film thickness and composition uniformity was developed. The effects of post deposition anneals, Al{sub 2}O{sub 3} interlayers between electrode and TiO{sub 2}, Al doping concentration, plasma enhanced deposition and electrode material type on leakage current density are shown. An optimized AlTiO{sub x} deposition process on TaN electrodes yields to leakage current density of 5 x 10{sup -7} A/cm{sup 2} at 2 V and k values of about 35. Thus, it could be demonstrated that a plasma enhanced batch ALD process for Al doped TiO{sub 2} is feasible with acceptable leakage current density on a standard electrode material.

  4. Growth mechanism of carbon nanotubes grown by microwave-plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Okai, M.; Muneyoshi, T.; Yaguchi, T.; Sasaki, S.; Shinohara, H.

    2001-11-01

    To understand the growth mechanism of carbon nanotubes, we have investigated the initial stage of carbon nanotube growth by microwave-plasma-enhanced CVD on a metal substrate. Metal droplets with diameters of 20-180 nm appeared on the substrate surface after plasma cleaning. These metal droplets operate as a catalyst for the growth of carbon nanotubes. The grown nanotubes had a piled-cone structure with metal particles at the top. The diameters of the carbon nanotubes ranged from 60 to 80 nm and the metal particles at the top were the same sizes.

  5. Contact potential induced enhancement of magnetization in polyaniline coated nanomagnetic iron oxides by plasma polymerization

    NASA Astrophysics Data System (ADS)

    Sethulakshmi, N.; Sooraj, V.; Sajeev, U. S.; Nair, Swapna S.; Narayanan, T. N.; Joy, Lija K.; Joy, P. A.; Ajayan, P. M.; Anantharaman, M. R.

    2013-10-01

    The present work derives motivation from the so called surface/interfacial magnetism in core shell structures and commercial samples of Fe3O4 and γ Fe2O3 with sizes ranging from 20 to 30 nm were coated with polyaniline using plasma polymerization and studied. The High Resolution Transmission Electron Microscopy images indicate a core shell structure after polyaniline coating and exhibited an increase in saturation magnetization by 2 emu/g. For confirmation, plasma polymerization was performed on maghemite nanoparticles which also exhibited an increase in saturation magnetization. This enhanced magnetization is rather surprising and the reason is found to be an interfacial phenomenon resulting from a contact potential.

  6. Surface cleaning for enhanced adhesion to packaging surfaces: Effect of oxygen and ammonia plasma

    SciTech Connect

    Gaddam, Sneha; Dong, Bin; Driver, Marcus; Kelber, Jeffry; Kazi, Haseeb

    2015-03-15

    The effects of direct plasma chemistries on carbon removal from silicon nitride (SiN{sub x}) and oxynitride (SiO{sub x}N{sub y}) surfaces have been studied by in-situ x-ray photoelectron spectroscopy (XPS) and ex-situ contact angle measurements. The data indicate that O{sub 2} and NH{sub 3} capacitively coupled plasmas are effective at removing adventitious carbon from silicon nitride (SiN{sub x}) and Si oxynitride (SiO{sub x}N{sub y}) surfaces. O{sub 2} plasma treatment results in the formation of a silica overlayer. In contrast, the exposure to NH{sub 3} plasma results in negligible additional oxidation of the SiN{sub x} or SiO{sub x}N{sub y} surface. Ex-situ contact angle measurements show that SiN{sub x} and SiO{sub x}N{sub y} surfaces exposed to oxygen plasma are initially more hydrophilic than surfaces exposed to NH{sub 3} plasma, indicating that the O{sub 2} plasma-induced SiO{sub 2} overlayer is highly reactive toward ambient. At longer ambient exposures (≳10 h), however, surfaces treated by either O{sub 2} or NH{sub 3} plasma exhibit similar steady state contact angles, correlated with rapid uptake of adventitious carbon, as determined by XPS. Surface passivation by exposure to molecular hydrogen prior to ambient exposure significantly retards the increase in contact angle upon exposure to ambient. The results suggest a practical route to enhancing the time available for effective bonding to surfaces in microelectronics packaging applications.

  7. Proposal of New Precursors for Plasma-Enhanced Chemical Vapor Deposition of SiOCH Low-k Films with Plasma Damage Resistance

    NASA Astrophysics Data System (ADS)

    Yoshi Ohashi,; Nobuo Tajima,; Yonghua Xu,; Takeshi Kada,; Shuji Nagano,; Hideharu Shimizu,; Satoshi Hasaka,

    2010-05-01

    We propose new precursors for bulk low-k films with plasma damage resistance. Our newly designed precursors contain long-chain hydrocarbon groups such as i-butyl and n-propyl groups. Using these precursors, we successfully produced films containing Si-CH2-Si groups by plasma-enhanced chemical vapor deposition (PECVD). The plasma damage resistance of these films under NH3 plasma treatment was studied. It was found that the increase in the k-value (Δ k) is smaller in films with more Si-CH2-Si groups.

  8. Proposal of New Precursors for Plasma-Enhanced Chemical Vapor Deposition of SiOCH Low-k Films with Plasma Damage Resistance

    NASA Astrophysics Data System (ADS)

    Ohashi, Yoshi; Tajima, Nobuo; Xu, Yonghua; Kada, Takeshi; Nagano, Shuji; Shimizu, Hideharu; Hasaka, Satoshi

    2010-05-01

    We propose new precursors for bulk low-k films with plasma damage resistance. Our newly designed precursors contain long-chain hydrocarbon groups such as i-butyl and n-propyl groups. Using these precursors, we successfully produced films containing Si-CH2-Si groups by plasma-enhanced chemical vapor deposition (PECVD). The plasma damage resistance of these films under NH3 plasma treatment was studied. It was found that the increase in the k-value (Δk) is smaller in films with more Si-CH2-Si groups.

  9. Plasma-Treated Microplates with Enhanced Protein Recoveries and Minimized Extractables

    PubMed Central

    Weikart, Christopher M.; Klibanov, Alexander M.; Breeland, Adam P.; Taha, Ahmad H.; Maurer, Brian R.; Martin, Steven P.

    2016-01-01

    SiO2 Medical Products, Inc. (SiO) has developed a proprietary technology that greatly enhances protein recoveries and reduces extractables from commercial microplates used for bioanalytical assays and storage of biologics. SiO technology is based on plasma treatment that chemically modifies the surface of polypropylene with predominantly hydrogen-bond-acceptor uncharged polar groups. The resultant surface resists nonspecific protein adsorption over a wide range of protein concentrations, thereby eliminating the need to passivate (and hence potentially contaminate) the microplates with blocking proteins. High shelf-life stability and cleanliness of the plasma-treated microplates have been demonstrated using five different proteins for two common microplate formats. The protein recovery performance of plasma-treated microplates is found to be higher compared with commercial low-protein-binding microplates. PMID:27651466

  10. Application of surface-enhanced Raman in skin cancer by plasma

    NASA Astrophysics Data System (ADS)

    Yin, W. Z.; Guo, Z. Y.; Zhuang, Z. F.; Liu, S. H.; Xiong, K.; Chen, S. J.

    2012-05-01

    We have developed a mouse squamous cell carcinomas (SCC) model by diniethylbenzanthracene (DMBA) and ultraviolet (UVB). A silver colloid as SERS-active substrates is used for detecting the blood plasma of mouse. The relative intensity of the band at 942 and 1499 cm-1 is higher in SCC model than in healthy one. Therefore, it can be used as an important "fingerprint" in order to diagnose these diseases. Results show us how to get high signal-to-noise ratio of biological macromolecules surface-enhanced Raman scattering spectra in blood plasma. And also offer useful help for understanding the rich molecular structure information in biological tissues. It provides a molecular spectroscopy way for early detection of disease in blood plasma.

  11. Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study

    SciTech Connect

    Sowińska, Małgorzata Henkel, Karsten; Schmeißer, Dieter; Kärkkänen, Irina; Schneidewind, Jessica; Naumann, Franziska; Gruska, Bernd; Gargouri, Hassan

    2016-01-15

    The process parameters' impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiO{sub x}N{sub y}) films was studied. Titanium(IV)isopropoxide in combination with NH{sub 3} plasma and tetrakis(dimethylamino)titanium by applying N{sub 2} plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current–voltage: I-V and capacitance–voltage: C-V) methods. The O/N ratio in the TiO{sub x}N{sub y} films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film properties can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination.

  12. Electron heating and control of electron energy distribution for the enhancement of the plasma ashing processing

    NASA Astrophysics Data System (ADS)

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-04-01

    Control of the electron energy distribution function (EEDF) is investigated through applying an inductive field in oxygen capacitively coupled plasma (CCP). With the addition of a small amount of antenna coil power to the CCP, low energy electrons are effectively heated and the EEDF is controlled. This method is applied to the ashing process of the photoresistor (PR). It is revealed that the ashing rate of the PR is significantly increased due to O radicals produced by the controlled EEDF, even though the ion density/energy flux is not increased. The roles of the power transfer mode in the electron heating and plasma control are also presented in the hybrid plasma source with inductive and capacitive fields. This work provides a route to enhance or control the processing result.

  13. Cold atmospheric pressure gas plasma enhances the wear performance of ultra-high molecular weight polyethylene.

    PubMed

    Perni, Stefano; Kong, Michael G; Prokopovich, Polina

    2012-03-01

    Ultra-high molecular weight polyethylene (UHMWPE) is frequently employed in joint replacements because of its high biocompatibility; however, this material does not exhibit particularly strong wear performance, thus potentially reducing the longevity of such devices. Numerous techniques have been investigated to increase the resistance to wear of UHMWPE, but they are all based on expensive machinery and require a high level of safety precautions. Cold atmospheric pressure gas plasma treatment is an inexpensive process that has been used as a surface modification method and as a sterilization technique. We demonstrate for the first time that a helium/oxygen cold atmospheric pressure gas plasma can be used to enhance the wear performance of UHMWPE without affecting the cytocompatibility of the material. The exposure to a cold atmospheric pressure gas plasma results in a greater level of crosslinking of the polyethylene chains. As a consequence of the higher crosslinking, the material stiffness of the treated surface is increased.

  14. Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

    NASA Astrophysics Data System (ADS)

    Lupina, G.; Strobel, C.; Dabrowski, J.; Lippert, G.; Kitzmann, J.; Krause, H. M.; Wenger, Ch.; Lukosius, M.; Wolff, A.; Albert, M.; Bartha, J. W.

    2016-05-01

    Plasma-enhanced chemical vapor deposition of thin a-Si:H layers on transferred large area graphene is investigated. Radio frequency (RF, 13.56 MHz) and very high frequency (VHF, 140 MHz) plasma processes are compared. Both methods provide conformal coating of graphene with Si layers as thin as 20 nm without any additional seed layer. The RF plasma process results in amorphization of the graphene layer. In contrast, the VHF process keeps the high crystalline quality of the graphene layer almost intact. Correlation analysis of Raman 2D and G band positions indicates that Si deposition induces reduction of the initial doping in graphene and an increase of compressive strain. Upon rapid thermal annealing, the amorphous Si layer undergoes dehydrogenation and transformation into a polycrystalline film, whereby a high crystalline quality of graphene is preserved.

  15. LED lamp or bulb with remote phosphor and diffuser configuration with enhanced scattering properties

    DOEpatents

    Tong, Tao; Le Toquin, Ronan; Keller, Bernd; Tarsa, Eric; Youmans, Mark; Lowes, Theodore; Medendorp, Jr., Nicholas W; Van De Ven, Antony; Negley, Gerald

    2014-11-11

    An LED lamp or bulb is disclosed that comprises a light source, a heat sink structure and an optical cavity. The optical cavity comprises a phosphor carrier having a conversions material and arranged over an opening to the cavity. The phosphor carrier comprises a thermally conductive transparent material and is thermally coupled to the heat sink structure. An LED based light source is mounted in the optical cavity remote to the phosphor carrier with light from the light source passing through the phosphor carrier. A diffuser dome is included that is mounted over the optical cavity, with light from the optical cavity passing through the diffuser dome. The properties of the diffuser, such as geometry, scattering properties of the scattering layer, surface roughness or smoothness, and spatial distribution of the scattering layer properties may be used to control various lamp properties such as color uniformity and light intensity distribution as a function of viewing angle.

  16. Nasopharyngeal cancer detection based on blood plasma surface-enhanced Raman spectroscopy and multivariate analysis.

    PubMed

    Feng, Shangyuan; Chen, Rong; Lin, Juqiang; Pan, Jianji; Chen, Guannan; Li, Yongzeng; Cheng, Min; Huang, Zufang; Chen, Jiesi; Zeng, Haishan

    2010-07-15

    A surface-enhanced Raman spectroscopy (SERS) method was developed for blood plasma biochemical analysis for the first time with the aim to develop a simple blood test for non-invasive nasopharyngeal cancer detection. Silver nanoparticles (Ag NP) as the SERS-active nanostructures were directly mixed with blood plasma to enhance the Raman scattering signals of various biomolecular constituents such as proteins, lipids, and nucleic acids. High quality SERS spectrum from blood plasma-Ag NP mixture can be obtained within 10s using a Renishaw micro-Raman system. SERS measurements were performed on two groups of blood plasma samples: one group from patients (n=43) with pathologically confirmed nasopharyngeal carcinomas (WHO type I, II, and III) and the other group from healthy volunteers (control subjects, n=33). Tentative assignments of the Raman bands in the measured SERS spectra suggest interesting cancer specific biomolecular differences, including an increase in the relative amounts of nucleic acid, collagen, phospholipids and phenylalanine and a decrease in the percentage of amino acids and saccharide contents in the blood plasma of nasopharyngeal cancer patients as compared to that of healthy subjects. Principal component analysis (PCA) of the measured SERS spectra separated the spectral features of the two groups into two distinct clusters with little overlaps. Linear discriminate analysis (LDA) based on the PCA generated features differentiated the nasopharyngeal cancer SERS spectra from normal SERS spectra with high sensitivity (90.7%) and specificity (100%). The results from this exploratory study demonstrated great potentials for developing SERS blood plasma analysis into a novel clinical tool for non-invasive detection of nasopharyngeal cancers.

  17. Remote ischemic postconditioning enhances cell retention in the myocardium after intravenous administration of bone marrow mesenchymal stromal cells.

    PubMed

    Jiang, Qin; Song, Peng; Wang, Enshi; Li, Jun; Hu, Shengshou; Zhang, Hao

    2013-03-01

    Efficacy of intravenous administration of mesenchymal stromal cells (MSCs) for myocardial infarction (MI) is limited by low cell retention in the damaged myocardium. Previous studies indicated that remote ischemic conditioning could protect against ischemia-reperfusion-induced injury by release of various cytokines including stromal cell derived factor-1 alpha (SDF-1α). However, whether remote ischemic postconditioning (RIPostC) can also enhance the retention of infused cells in the myocardium by activating MSC homing is unclear. In this study, RIPostC was induced with 4cycles of 5min occlusion and reperfusion of the abdominal aorta in female Sprague-Dawley (SD) rats which underwent ligation of the coronary artery 1week previously. Cytokine levels in serum and myocardium were evaluated by enzyme-linked immunosorbent assay (ELISA) at 1, 6, 24 and 48h after RIPostC. Then, a total of 4×10(6) male MSCs were infused intravenously at 24h after RIPostC. The number of survived cells in the myocardium was evaluated by real-time polymerase chain reaction analysis for Y chromosome and the heart function was evaluated by echocardiography at 1month after cell infusion. Furthermore, 10μg/kg rabbit anti-rat CXCR4 polyclonal antibody was injected intraperitoneally to prove the role of SDF-1α for RIPostC. RIPostC induced an increase in SDF-1α in serum at 1h and enhanced SDF-1α transcription and protein synthesis in the myocardium at 24h after the procedure. 1month after cell transplantation, RIPostC significantly increased MSC myocardial retention by 79.1±12.3% and thereby contributed to enhanced cardiac function in comparison with cell transplantation without RIPostC. Furthermore, blockade with a CXCR4-specific antibody after RIPostC markedly attenuated the enhancement of therapeutic efficacy. We conclude that RIPostC activated SDF-1α expression and enhanced retention of the infused MSCs in the injured myocardium. Priming of the heart with RIPostC might be a novel

  18. Delta(9)-tetrahydrocannabinol enhances an increase of plasma corticosterone levels induced by forced swim-stress.

    PubMed

    Sano, Kazunori; Koushi, Emi; Irie, Keiichi; Higuchi, Sei; Tsuchihashi, Ryota; Kinjo, Junei; Egashira, Nobuaki; Oishi, Ryozo; Uchida, Naoki; Nagai, Hiroshi; Nishimura, Ryoji; Tanaka, Hiroyuki; Morimoto, Satoshi; Mishima, Kenichi; Iwasaki, Katsunori; Fujiwara, Michihiro

    2009-12-01

    The present study was designed to determine the effect of delta(9)-tetrahydrocannabinol (THC) on susceptibility to stress. We reported that THC significantly prolonged the immobility time during the forced swim-stress. The selective cannabinoid CB(1) receptor antagonist O-2050 significantly reduced the enhancement of immobility by THC. We investigated the effect of THC on levels of stress hormone corticosterone under non-stress and forced swim-stress conditions. THC did not affect plasma corticosterone levels under non-stress conditions. However, THC, together with forced swim-stress, significantly increased plasma corticosterone levels. This effect was inhibited by O-2050. This evidence suggests that THC, under stressful conditions, enhances the susceptibility of the hypothalamus-pituitary-adrenal-axis to stress via the CB(1) receptor, thereby increasing the risk of depression.

  19. Enhanced Biological Behavior of In Vitro Human Gingival Fibroblasts on Cold Plasma-Treated Zirconia

    PubMed Central

    Zheng, Miao; Yang, Yang; Liu, Xiao-Qiang; Liu, Ming-Yue; Zhang, Xiao-Fei; Wang, Xin; Li, He-Ping; Tan, Jian-Guo

    2015-01-01

    Objective To evaluate whether atmospheric-pressure dielectric-barrier-discharge plasma treatment of zirconia enhances its biocompatibility with human gingival fibroblasts. Materials and Methods The zirconia disks were divided into four groups and treated using helium atmospheric-pressure dielectric-barrier-discharge plasmas for 30, 60 or 90 s or left untreated. The surface morphology, wettability and chemical elements were analyzed. Fibroblasts density, morphology, morphometry and attachment-related genes expression were measured at different time points from 3 to 72 h. Results After plasma treatment, the surface morphology and roughness remained the same, while the contact angle decreased from 78.31° to 43.71°, and the surface C/O ratio decreased from 3.17 to 0.89. The surficial areas and perimeters of HGFs were increased two-fold in the treated groups at 3 h. Fibroblasts density increased on treated disks at all time points, especially the ones treated for 60 s. Attachment-related genes in the groups treated for 30 and 60 s were significantly higher at 3 and 24 h. Conclusion The helium atmospheric-pressure dielectric-barrier-discharge plasma treatment enhances the biological behavior of fibroblasts on zirconia by increasing the expression of attachment-related genes within 24 h and promoting the cell density during longer culture times. Wettability of zirconia, an important physicochemical property, has a vital influence on the cell behaviors. PMID:26461253

  20. Polystyrene as a model system to probe the impact of ambient gas chemistry on polymer surface modifications using remote atmospheric pressure plasma under well-controlled conditions.

    PubMed

    Bartis, Elliot A J; Luan, Pingshan; Knoll, Andrew J; Hart, Connor; Seog, Joonil; Oehrlein, Gottlieb S

    2015-06-30

    An atmospheric pressure plasma jet (APPJ) was used to treat polystyrene (PS) films under remote conditions where neither the plume nor visible afterglow interacts with the film surface. Carefully controlled conditions were achieved by mounting the APPJ inside a vacuum chamber interfaced to a UHV surface analysis system. PS was chosen as a model system as it contains neither oxygen nor nitrogen, has been extensively studied, and provides insight into how the aromatic structures widespread in biological systems are modified by atmospheric plasma. These remote treatments cause negligible etching and surface roughening, which is promising for treatment of sensitive materials. The surface chemistry was measured by X-ray photoelectron spectroscopy to evaluate how ambient chemistry, feed gas chemistry, and plasma-ambient interaction impact the formation of specific moieties. A variety of oxidized carbon species and low concentrations of NOx species were measured after APPJ treatment. In the remote conditions used in this work, modifications are not attributed to short-lived species, e.g., O atoms. It was found that O3 does not correlate with modifications, suggesting that other long-lived species such as singlet delta oxygen or NOx are important. Indeed, surface-bound NO3 was observed after treatment, which must originate from gas phase NOx as neither N nor O are found in the pristine film. By varying the ambient and feed gas chemistry to produce O-rich and O-poor conditions, a possible correlation between the oxygen and nitrogen composition was established. When oxygen is present in the feed gas or ambient, high levels of oxidation with low concentrations of NO3 on the surface were observed. For O-poor conditions, NO and NO2 were measured, suggesting that these species contribute to the oxidation process, but are easily oxidized when oxygen is present. That is, surface oxidation limits and competes with surface nitridation. Overall, surface oxidation takes place easily

  1. Enhanced thermoelectric performance of spark plasma sintered copper-deficient nanostructured copper selenide

    NASA Astrophysics Data System (ADS)

    Tyagi, Kriti; Gahtori, Bhasker; Bathula, Sivaiah; Jayasimhadri, M.; Singh, Niraj Kumar; Sharma, Sakshi; Haranath, D.; Srivastava, A. K.; Dhar, Ajay

    2015-06-01

    We report the thermoelectric properties of nanostructured Cu-deficient Cu2Se, which was synthesized by high energy ball milling followed by spark plasma sintering. Our method obtained a significant enhancement in the thermoelectric figure of merit (ZT), i.e., ~1.4 at 973 K, which was ~30% higher than its bulk counterpart. This enhancement in the thermoelectric performance was due mainly to a significant reduction in the lattice thermal conductivity, which was attributed to enhanced phonon scattering at various length scales by nanoscale defects as well as abundant nanograin boundaries. The nanoscale defects were characterized by transmission electron microscopy of the nanostructured Cu2-xSe samples, which formed the basis of the ZT enhancement.

  2. ZnO nanorod growth by plasma-enhanced vapor phase transport with different growth durations

    SciTech Connect

    Kim, Chang-Yong; Oh, Hee-bong; Ryu, Hyukhyun; Yun, Jondo; Lee, Won-Jae

    2014-09-01

    In this study, the structural properties of ZnO nanostructures grown by plasma-enhanced vapor phase transport (PEVPT) were investigated. Plasma-treated oxygen gas was used as the oxygen source for the ZnO growth. The structural properties of ZnO nanostructures grown for different durations were measured by scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. The authors comprehensively analyzed the growth of the ZnO nanostructures with different growth durations both with and without the use of plasma-treated oxygen gas. It was found that PEVPT has a significant influence on the growth of the ZnO nanorods. PEVPT with plasma-treated oxygen gas facilitated the generation of nucleation sites, and the resulting ZnO nanorod structures were more vertical than those prepared by conventional VPT without plasma-treated oxygen gas. As a result, the ZnO nanostructures grown using PEVPT showed improved structural properties compared to those prepared by the conventional VPT method.

  3. Plasma-enhanced synthesis of bactericidal quaternary ammonium thin layers on stainless steel and cellulose surfaces.

    PubMed

    Jampala, Soujanya N; Sarmadi, M; Somers, E B; Wong, A C L; Denes, F S

    2008-08-19

    We have investigated bottom-up chemical synthesis of quaternary ammonium (QA) groups exhibiting antibacterial properties on stainless steel (SS) and filter paper surfaces via nonequilibrium, low-pressure plasma-enhanced functionalization. Ethylenediamine (ED) plasma under suitable conditions generated films rich in secondary and tertiary amines. These functional structures were covalently attached to the SS surface by treating SS with O 2 and hexamethyldisiloxane plasma prior to ED plasma treatment. QA structures were formed by reaction of the plasma-deposited amines with hexyl bromide and subsequently with methyl iodide. Structural compositions were examined by electron spectroscopy for chemical analysis and Fourier transform infrared spectroscopy, and surface topography was investigated with atomic force microscopy and water contact angle measurements. Modified SS surfaces exhibited greater than a 99.9% decrease in Staphylococcus aureus counts and 98% in the case of Klebsiella pneumoniae. The porous filter paper surfaces with immobilized QA groups inactivated 98.7% and 96.8% of S. aureus and K. pneumoniae, respectively. This technique will open up a novel way for the synthesis of stable and very efficient bactericidal surfaces with potential applications in development of advanced medical devices and implants with antimicrobial surfaces.

  4. Plasma-enhanced synthesis of surfaces that kill bacteria on contact

    NASA Astrophysics Data System (ADS)

    Jampala, Soujanya Naga

    High incidences of microbial contamination and infections are a major concern in all existing and evolving technologies of medicine and biology. The propensity towards infections is directly related to bacterial colonization and biofilms on surfaces. This dissertation presents the development of surfaces that can kill bacteria on contact by using cold plasma technology. Quaternary ammonium (QA) groups are known to exhibit antibacterial characteristics in water-based environments. To overcome the limitations of residual toxicity, alternative strategies involving covalent attachment of QA groups to metallic and cellulosic surfaces have been developed. Low pressure, non-equilibrium plasma-enhanced functionalization and subsequent ex situ chemical reactions were designed for step-by-step "bottom-up" chemical synthesis of QA groups covalently anchored to surfaces. The plasma processes under selected discharge parameters generated structure- and functionality-controlled crosslinked networks of macromolecular layers with high concentrations of reactive amine groups. Subsequent derivatization of the plasma-deposited films with alkyl halides yielded surface-bound QA groups rendering surfaces with high bactericidal efficacy against Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae. Stainless steel and cotton surfaces sequentially treated with ethylene diamine plasma, n-hexyl bromide and methyl iodide exhibited at least 99.9% and 98% kill of S. aureus and K. pneumoniae respectively. The influence of chemical architecture of QA groups with different alkyl substituents on the efficacy of bactericidal surfaces was quantified. Results from this work will permit the development of novel plasma-aided technologies for the synthesis of antibacterial surfaces with potential biomedical applications. The cold plasma approach can be used on any solid material surfaces including polymers, metals, ceramics and semiconductors.

  5. Enhancing surface functionality of reduced graphene oxide biosensors by oxygen plasma treatment for Alzheimer's disease diagnosis.

    PubMed

    Chae, Myung-Sic; Kim, Jinsik; Jeong, Dahye; Kim, YoungSoo; Roh, Jee Hoon; Lee, Sung Min; Heo, Youhee; Kang, Ji Yoon; Lee, Jeong Hoon; Yoon, Dae Sung; Kim, Tae Geun; Chang, Suk Tai; Hwang, Kyo Seon

    2017-06-15

    We performed oxygen plasma treatment on reduced graphene oxide (rGO) to improve its surface reactivity with respect to biomolecular interactions. Oxygen-plasma-treated rGO surfaces were employed as reactive interfaces for the detection of amyloid-beta (Aβ) peptides, the pathological hallmarks of Alzheimer's disease (AD), as the target analytes. By measuring the changes in electrical characteristics and confirmation through topographic analysis, the oxygen-plasma-treated rGO sensors had enhanced surface functionality for better antibody immobilization and sensing performance, with a 3.33-fold steeper slope for the electrical responses versus analyte concentration curve (logarithmic scale) compared to the untreated. The elicited biomolecular reactivity of the rGO surfaces with the oxygen plasma treatment remained at 46-51% of the initial value even after aging for 6h in ambient conditions. This phenomenon was also confirmed by pretreating the rGO surfaces with a blocking agent and subsequently subjecting them to antibody immobilization. Finally, the feasibility of the oxygen-plasma-treated rGO sensors as a diagnostic tool was evaluated with clinical samples of neural-derived exosomal Aβ peptides extracted from apparent AD patients and normal controls (NC). In contrast to the untreated sensors (p=0.0460), the oxygen-plasma-treated rGO sensors showed a significant p-value in the identification of clinical samples of AD and NC subjects (p<0.001). These results suggest that oxygen plasma treatment improves sensor performance without complicated fabrication procedures and should aid in the development of novel diagnostic tools based on carbon nanomaterials.

  6. Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas

    SciTech Connect

    Singh, S. C. Fallon, C.; Hayden, P.; Yeates, P.; Costello, J. T.; Mujawar, M.

    2014-09-15

    Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

  7. Modeling the inner plasma sheet protons and magnetic field under enhanced convection

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Ping; Lyons, Larry R.; Chen, Margaret W.; Wolf, Richard A.; Toffoletto, Frank R.

    2003-02-01

    In order to understand the evolution of the protons and magnetic field in the inner plasma sheet from quiet to disturbed conditions, we incorporate a modified version of the Magnetospheric Specification Model (MSM) with a modified version of the Tsyganenko 96 (T96) magnetic field model to simulate the protons and magnetic field under an increasing convection electric field with two-dimensional (2-D) force balance maintained along the midnight meridian. The local time dependent proton differential fluxes assigned to the model boundary are a mixture of hot plasma from the mantle and cooler plasma from the low latitude boundary layer (LLBL). We previously used this model to simulate the inner plasma sheet under weak convection corresponding to a cross polar cap potential drop (ΔΦPC) equal to 26 kV and obtained 2-D quiet time equilibrium for proton and magnetic field that agrees well with observations. We start our simulation for enhanced convection with this quiet time equilibrium and time-independent boundary particle sources and increase ΔΦPC steadily from 26 to 146 kV in 5 hours. Simulations are also run separately to steady states by keeping ΔΦPC constant after it is increased to 98 and 146 kV. The magnitudes of proton pressure, number density, and temperature and their increase from quiet to moderate activity (ΔΦPC = 98 kV) are consistent with most observations. Our simulation at high activity (ΔΦPC = 146 kV) underestimates the observed pressure and temperature. This disagreement indicates possible dependence of the boundary particle sources on activity and possible effects of solar wind dynamic pressure enhancements that have not yet been included in our simulation. The simulated equatorial pressures and temperatures show stronger enhancement on the dusk side than on the dawn side as convection is increased, while density profiles show an increase on the dawn side and a decrease on the dusk side. The simulated proton flow speed at the equatorial plane

  8. Enhanced algorithm performance for land cover classification from remotely sensed data using bagging and boosting

    USGS Publications Warehouse

    Chan, J.C.-W.; Huang, C.; DeFries, R.

    2001-01-01

    Two ensemble methods, bagging and boosting, were investigated for improving algorithm performance. Our results confirmed the theoretical explanation [1] that bagging improves unstable, but not stable, learning algorithms. While boosting enhanced accuracy of a weak learner, its behavior is subject to the characteristics of each learning algorithm.

  9. Suppression of hydrogenated carbon film deposition and hydrogen isotope retention by nitrogen addition into cold remote H/D and CH4 mixture plasmas

    NASA Astrophysics Data System (ADS)

    Iida, K.; Notani, M.; Uesugi, Y.; Tanaka, Y.; Ishijima, T.

    2015-08-01

    Control of tritium retention and its removal from the first wall of future fusion devices are one of the most crucial issues for safety and effective use for fuel. Nitrogen addition into remote edge plasmas has been considered and tested as an effective method for suppression of carbon film deposition and reduction of hydrogen isotope absorption in the deposited films. In this paper we have investigated the scavenger effects of nitrogen injected into low temperature D2/CH4 plasmas on hydrogenated carbon film growth using a small helical device. The result of the deposition shows that the key reactive particles with CN and ND(H) bonds to suppression of hydrogenated carbon film growth and hydrogen isotope absorption are much slowly generated compared with hydrocarbon particles such as CD(H)x and C2D(H)x. This may be due to the slow atomic nitrogen diffusion into hydrogenated carbon layer and the chemical equilibrium between nitrogen absorption.

  10. Enhancing Access to Land Remote Sensing Data through Mainstream Social Media Channels

    NASA Astrophysics Data System (ADS)

    Sohre, T.; Maiersperger, T.

    2011-12-01

    Social media tools are changing the way that people discover information, communicate, and collaborate. Government agencies supporting the Land Remote Sensing user community have begun taking advantage of standard social media tools and capabilities. National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) data centers have started providing outreach utilizing services including Facebook, Twitter, and YouTube videos. Really Simple Syndication (RSS) Feeds have become more standard means of sharing information, and a DataCasting tool was created as a NASA Technology Infusion effort to make RSS-based technology for accessing Earth Science information available. The United States Geological Survey (USGS) has also started using social media to allow the community access to news feeds and real-time earthquake alerts; listen to podcasts; get updates on new USGS publications, videos, and photographs; and more. Twitter feeds have been implemented in 2011 for the USGS Land Cover and Landsat user communities. In early 2011, the NASA Land Processes Distributed Active Archive Center (LP DAAC) user working group suggested the investigation of concepts for creating and distributing "bundles" of data, which would aggregate theme-based data sets from multiple sources. The LP DAAC is planning to explore the use of standard social bookmarking tools to support community developed bundles through the use of tools such as Delicious, Digg, or StumbleUpon. This concept would allow science users to organize and discover common links to data resources based on community developed tags, or a folksonomy. There are challenges that will need to be addressed such as maintaining the quality of tags but a social bookmarking system may have advantages over traditional search engines or formal ontologies for identifying and labeling various data sets relevant to a theme. As classification is done by the community of scientists who understand the data, the tagged data sets

  11. Organic acids enhanced decoloration of azo dye in gas phase surface discharge plasma system.

    PubMed

    Wang, Tiecheng; Qu, Guangzhou; Ren, Jingyu; Sun, Qiuhong; Liang, Dongli; Hu, Shibin

    2016-01-25

    A gas phase surface discharge plasma combined with organic acids system was developed to enhance active species mass transfer and dye-containing wastewater treatment efficacy, with Acid Orange II (AO7) as the model pollutant. The effects of discharge voltage and various organic acid additives (acetic acid, lactic acid and nonoic acid) on AO7 decoloration efficiency were evaluated. The experimental results showed that an AO7 decoloration efficiency of approximately 69.0% was obtained within 4 min of discharge plasma treatment without organic acid addition, which was improved to 82.8%, 83.5% and 88.6% within the same treatment time with the addition of acetic acid, lactic acid and nonoic acid, respectively. The enhancement effects on AO7 decoloration efficiency could be attributed to the decrease in aqueous surface tension, improvement in bubble distribution and shape, and increase in ozone equivalent concentration. The AO7 wastewater was biodegradable after discharge plasma treatment with the addition of organic acid. AO7 decomposition intermediates were analyzed by UV-vis spectrometry and GC-MS; 2-naphthol, 1,4-benzoquinone, phthalic anhydride, coumarin, 1,2-naphthoquinone, and 2-formyl-benzoic acid were detected. A possible pathway for AO7 decomposition in this system was proposed.

  12. 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.

  13. Plasma-enhanced regenerable 5,5-dimethylhydantoin (DMH) antibacterial finishing for cotton fabric

    NASA Astrophysics Data System (ADS)

    Zhou, Chang-E.; Kan, Chi-Wai

    2015-02-01

    In this study, atmospheric pressure nitrogen plasma treatment was applied to cotton fabrics in the coating process of cotton fabric coated with 5,5-dimethylhydantoin (DMH) with the aim to enhance the adhesion of DMH and antibacterial property. Then chlorine was introduced into nitrogen-containing groups on the coated cotton fabrics in order to make it antibacterial by chlorination with sodium hypochlorite. The antibacterial property, rechargeability and stability of the coated cotton fabrics were investigated. FTIR, UV and SEM were used to evaluate the surface properties, including the existence of DMH on cotton fabrics, the content of DMH on cotton fabrics and the surface topography of cotton fabrics after modification. The results showed that nitrogen plasma treatment introduces nitrogen-containing groups into cotton fabrics and enhances the adhesion of DMH on the fabrics, and introduction of chlorine on the coated fabrics inhibits bacteria, Staphylococcus aureus (S. aureus), effectively and the antibacterial property is regenerable. Therefore, the antibacterial finishing of cotton fabrics coated with DMH with the aid of nitrogen plasma treatment achieves good effect.

  14. Environmental and economic performance of plasma gasification in Enhanced Landfill Mining.

    PubMed

    Danthurebandara, Maheshi; Van Passel, Steven; Vanderreydt, Ive; Van Acker, Karel

    2015-11-01

    This paper describes an environmental and economic assessment of plasma gasification, one of the viable candidates for the valorisation of refuse derived fuel from Enhanced Landfill Mining. The study is based on life cycle assessment and life cycle costing. Plasma gasification is benchmarked against conventional incineration, and the study indicates that the process could have significant impact on climate change, human toxicity, particulate matter formation, metal depletion and fossil depletion. Flue gas emission, oxygen usage and disposal of residues (plasmastone) are the major environmental burdens, while electricity production and metal recovery represent the major benefits. Reductions in burdens and improvements in benefits are found when the plasmastone is valorised in building materials instead of landfilling. The study indicates that the overall environmental performance of plasma gasification is better than incineration. The study confirms a trade-off between the environmental and economic performance of the discussed scenarios. Net electrical efficiency and investment cost of the plasma gasification process and the selling price of the products are the major economic drivers.

  15. Model of enhanced energy deposition in a Z-pinch plasma

    SciTech Connect

    Velikovich, A. L.; Davis, J.; Thornhill, J. W.; Giuliani, J. L. Jr.; Rudakov, L. I.; Deeney, C.

    2000-08-01

    In numerous experiments, magnetic energy coupled to strongly radiating Z-pinch plasmas exceeds the thermalized kinetic energy, sometimes by a factor of 2-3. An analytical model describing this additional energy deposition based on the concept of macroscopic magnetohydrodynamic (MHD) turbulent pinch heating proposed by Rudakov and Sudan [Phys. Reports 283, 253 (1997)] is presented. The pinch plasma is modeled as a foam-like medium saturated with toroidal ''magnetic bubbles'' produced by the development of surface m=0 Rayleigh-Taylor and MHD instabilities. As the bubbles converge to the pinch axis, their magnetic energy is converted to thermal energy of the plasma through pdV work. Explicit formulas for the average dissipation rate of this process and the corresponding contribution to the resistance of the load, which compare favorably to the experimental data and simulation results, are presented. The possibility of using this enhanced (relative to Ohmic heating) dissipation mechanism to power novel plasma radiation sources and produce high K-shell yields using long current rise time machines is discussed. (c) 2000 American Institute of Physics.

  16. Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

    PubMed Central

    Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf , Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning. PMID:28053312

  17. Modeling of Sheath Ion-Molecule Reactions in Plasma Enhanced Chemical Vapor Deposition of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hash, David B.; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    In many plasma simulations, ion-molecule reactions are modeled using ion energy independent reaction rate coefficients that are taken from low temperature selected-ion flow tube experiments. Only exothermic or nearly thermoneutral reactions are considered. This is appropriate for plasma applications such as high-density plasma sources in which sheaths are collisionless and ion temperatures 111 the bulk p!asma do not deviate significantly from the gas temperature. However, for applications at high pressure and large sheath voltages, this assumption does not hold as the sheaths are collisional and ions gain significant energy in the sheaths from Joule heating. Ion temperatures and thus reaction rates vary significantly across the discharge, and endothermic reactions become important in the sheaths. One such application is plasma enhanced chemical vapor deposition of carbon nanotubes in which dc discharges are struck at pressures between 1-20 Torr with applied voltages in the range of 500-700 V. The present work investigates The importance of the inclusion of ion energy dependent ion-molecule reaction rates and the role of collision induced dissociation in generating radicals from the feedstock used in carbon nanotube growth.

  18. Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

    NASA Astrophysics Data System (ADS)

    Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf, Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning.

  19. Polyimide surface modification by using microwave plasma for adhesion enhancement of Cu electroless plating.

    PubMed

    Cho, Sang-Jin; Nguyen, Trieu; Boo, Jin-Hyo

    2011-06-01

    Microwave (MW) plasma was applied to the surface of polyimide (PI) films as a treatment to enhance the adhesion between copper deposition layer and PI surface for electroless plating. The influences of nitrogen MW plasma treatment on chemical composition of the PI surface were investigated by using X-Ray photoelectron spectroscopy (XPS). The wettability was also investigated by water contact angle measurement. The surface morphologies of PI films before and after treatment were characterized with atomic force microscopy (AFM). The contact angle results show that was dramatically decreased to 16.1 degrees at the optimal treatment condition from 72.1 degrees (untreated PI). However, the root mean square (RMS) roughness of treated PI film was almost unchanged. The AFM roughness was stayed from 1.0 to 1.2 with/without plasma treatment. XPS data show a nitrogen increase when PI films exposed to N2 MW plasma. Electroless copper depositions were carried out with the free-formaldehyde method using glyoxylic acid as the reducing reagent and mixture palladium chloride, tin chloride as activation solution. Adhesion property between polyimide surface and copper layer was investigated by tape test.

  20. Deposition of electrochromic tungsten oxide thin films by plasma-enhanced chemical vapor deposition

    SciTech Connect

    Henley, W.B.; Sacks, G.J.

    1997-03-01

    Use of plasma-enhanced chemical vapor deposition (PECVD) for electrochromic WO{sub 3} film deposition is investigated. Oxygen, hydrogen, and tungsten hexafluoride were used as source gases. Reactant gas flow was investigated to determine the effect on film characteristics. High quality optical films were obtained at deposition rates on the order of 100 {angstrom}/s. Higher deposition rates were attainable but film quality and optical coherence degraded. Atomic emission spectroscopy (AES), was used to provide an in situ assessment of the plasma deposition chemistry. Through AES, it is shown that the hydrogen gas flow is essential to the deposition of the WO{sub 3} film. Oxygen gas flow and tungsten hexafluoride gas flow must be approximately equal for high quality films.

  1. Enhancement of wave growth for warm plasmas with a high-energy tail distribution

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Summers, Danny

    1991-01-01

    The classical linear theory of electromagnetic wave growth in a warm plasma is considered for waves propagating parallel to a uniform ambient magnetic field. Wave-growth rates are calculated for ion-driven right-hand mode waves for Kappa and Maxwellian particle distribution functions and for various values of the spectral index, the temperature anisotropy, and the ratio of plasma pressure to magnetic pressure appropriate to the solar wind. When the anisotropy is low the wave growth is limited to frequencies below the proton gyrofrequency and the growth rate increases dramatically as the spectral index is reduced. The growth rate for any Kappa distribution greatly exceeds that for a Maxwellian with the same bulk properties. For large thermal anisotropy the growth rate from either distribution is greatly enhanced. The growth rates from a Kappa distribution are generally larger than for a Maxwellian distribution, and significant wave growth occurs over a broader range of frequencies.

  2. Solar wind plasma profiles during interplanetary field enhancements (IFEs): Consistent with charged-dust pickup

    NASA Astrophysics Data System (ADS)

    Lai, H. R.; Wei, H. Y.; Russell, C. T.

    2013-06-01

    The solar wind contains many magnetic structures, and most of them have identifiable correlated changes in the flowing plasma. However, the very characteristic rise and fall of the magnetic field in an interplanetary field enhancement has no clear solar wind counterpart. It appears to be a pure magnetic ``barrier'' that transfers solar wind momentum to charged dust produced in collisions of interplanetary bodies in the size range of tens to hundreds of meters. This transfer lifts the fine scale dust out of the Sun's gravitational well. We demonstrate the lack of field-plasma correlation with several examples from spacecraft records as well as show an ensemble average velocity profile during IFEs which is consistent with our IFE formation hypothesis.

  3. Improved ion implant fluence uniformity in hydrogen enhanced glow discharge plasma immersion ion implantation into silicon

    SciTech Connect

    Luo, J.; Li, L. H. E-mail: paul.chu@cityu.edu.hk; Liu, H. T.; Xu, Y.; Zuo, X. J.; Zhu, P. Z.; Ma, Y. F.; Yu, K. M.; Fu, Ricky K. Y.; Chu, Paul K. E-mail: paul.chu@cityu.edu.hk

    2014-06-15

    Enhanced glow discharge plasma immersion ion implantation does not require an external plasma source but ion focusing affects the lateral ion fluence uniformity, thereby hampering its use in high-fluence hydrogen ion implantation for thin film transfer and fabrication of silicon-on-insulator. Insertion of a metal ring between the sample stage and glass chamber improves the ion uniformity and reduces the ion fluence non-uniformity as the cathode voltage is raised. Two-dimensional multiple-grid particle-in-cell simulation confirms that the variation of electric field inside the chamber leads to mitigation of the ion focusing phenomenon and the results are corroborated experimentally by hydrogen forward scattering.

  4. Growing oriented AlN films on sapphire substrates by plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Tarala, V. A.; Altakhov, A. S.; Ambartsumov, M. G.; Martens, V. Ya.

    2017-01-01

    The possibility of growing oriented AlN films on Al2O3 substrates at temperatures below 300°C by plasma-enhanced atomic layer deposition was examined. The samples were subjected to X-ray phase analysis and ellipsometry. It was demonstrated that the refraction index of films deposited with plasma exposures longer than 20 s was 2.03 ± 0.03. The (0002) and (0004) reflections at 2Θ angles of 35.7° and 75.9° were present in the X-ray diffraction patterns of these samples. These reflections are typical of the hexagonal AlN polytype. The full width at half maximum of the rocking curve of reflection (0002) in the best sample was 162 ± 11 arcsec.

  5. Disruption of Autoregulatory Feedback by a Mutation in a Remote, Ultraconserved PAX6 Enhancer Causes Aniridia

    PubMed Central

    Bhatia, Shipra; Bengani, Hemant; Fish, Margaret; Brown, Alison; Divizia, Maria Teresa; de Marco, Riccardo; Damante, Guiseppe; Grainger, Robert; van Heyningen, Veronica; Kleinjan, Dirk A.

    2013-01-01

    The strictly regulated expression of most pleiotropic developmental control genes is critically dependent on the activity of long-range cis-regulatory elements. This was revealed by the identification of individuals with a genetic condition lacking coding-region mutations in the gene commonly associated with the disease but having a variety of nearby chromosomal abnormalities, collectively described as cis-ruption disease cases. The congenital eye malformation aniridia is caused by haploinsufficiency of the developmental regulator PAX6. We discovered a de novo point mutation in an ultraconserved cis-element located 150 kb downstream from PAX6 in an affected individual with intact coding region and chromosomal locus. The element SIMO acts as a strong enhancer in developing ocular structures. The mutation disrupts an autoregulatory PAX6 binding site, causing loss of enhancer activity, resulting in defective maintenance of PAX6 expression. These findings reveal a distinct regulatory mechanism for genetic disease by disruption of an autoregulatory feedback loop critical for maintenance of gene expression through development. PMID:24290376

  6. Enhanced ion acceleration in the transition regime from opaque to transparent plasmas

    NASA Astrophysics Data System (ADS)

    Mishra, Rohini; Fiuza, Frederico; Glenzer, Siegfried

    2016-10-01

    Using Particle-in-Cell (PIC) simulations, we investigate ion acceleration in high-intensity laser-plasma interactions in for targets that become laser transparent to the laser during the interaction process. A theoretical model is developed to derive an optimal target electron areal density `n.L' as a function of laser normalized intensity and the pulse duration in the laser transparent regime. A large schematic parametric scan for a wide range of target electron density (n) and thickness (L) is performed and shown to be consistent with analytical prediction. Our simulations show that iIon acceleration in optimal conditions relies on the re-heating of the expanding sheath electrons by the laser and enhancing enhancement of the Target Normal Sheath Acceleration (TNSA) electric field after the plasma becomes transparent to the laser light. This enhanced TNSA field decays slower compared to conventional TNSA resulting in significantly higher proton energies. Our results open the way to the exploration of optimized ion acceleration in the transparency regime, not only with nm-scale foils but also with recently developed micron-scale hydrogen jets. This work was supported by the DOE Office of Science, Fusion Energy Science (FWP 100182).

  7. Enhanced monolithic diffraction gratings with high efficiency and reduced polarization sensitivity for remote sensing applications

    NASA Astrophysics Data System (ADS)

    Triebel, Peter; Diehl, Torsten; Moeller, Tobias; Gatto, Alexandre; Pesch, Alexander; Erdmann, Lars H.; Burkhardt, Matthias; Kalies, Alexander

    2015-10-01

    Spectral imaging systems lead to enhanced sensing properties when the sensing system provides sufficient spectral resolution to identify materials from its spectral reflectance signature. The performance of diffraction gratings provides an initial way to improve instrumental resolution. Thus, subsequent manufacturing techniques of high quality gratings are essential to significantly improve the spectral performance. The ZEISS unique technology of manufacturing real-blazed profiles and as well as lamellar profiles comprising transparent substrates is well suited for the production of transmission gratings. In order to reduce high order aberrations, aspherical and free-form surfaces can be alternatively processed to allow more degrees of freedom in the optical design of spectroscopic instruments with less optical elements and therefore size and weight advantages. Prism substrates were used to manufacture monolithic GRISM elements for UV to IR spectral range. Many years of expertise in the research and development of optical coatings enable high transmission anti-reflection coatings from the DUV to the NIR. ZEISS has developed specially adapted coating processes (Ion beam sputtering, ion-assisted deposition and so on) for maintaining the micro-structure of blazed gratings in particular. Besides of transmission gratings, numerous spectrometer setups (e.g. Offner, Rowland circle, Czerny-Turner system layout) working on the optical design principles of reflection gratings. This technology steps can be applied to manufacture high quality reflection gratings from the EUV to the IR applications with an outstanding level of low stray light and ghost diffraction order by employing a combination of holography and reactive ion beam etching together with the in-house coating capabilities. We report on results of transmission gratings on plane and curved substrates and GRISM elements with enhanced efficiency of the grating itself combined with low scattered light in the angular

  8. Plasma-enhanced chemical vapor deposition of β-tungsten, a metastable phase

    NASA Astrophysics Data System (ADS)

    Tang, C. C.; Hess, D. W.

    1984-09-01

    Plasma-enhanced chemical vapor deposition of a metastable phase of tungsten ( β-W) is performed using tungsten hexafluoride and hydrogen as source gases. At 350 °C, the as-deposited resistivity of these films is ˜50 μΩ cm. After heat treatments between 650 and 750 °C in forming gas, the resistivity drops below 11 μΩ cm. Concomitant with this resistivity change is a phase change to α-W, the equilibrium, body-centered-cubic form.

  9. Amorphous hollow carbon spheres synthesized using radio frequency plasma-enhanced chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Yang, G. M.; Xu, Q.; Tian, H. W.; Wang, X.; Zheng, W. T.

    2008-10-01

    We report a method to synthesize amorphous hollow carbon spheres, with diameters ranging from 100 to 800 nm, which are dispersed among bent graphitized carbon nanotubes using radio frequency plasma-enhanced chemical vapour deposition in mixed CH4/H2 gases. The products are characterized by techniques including scanning electron microscopy, energy-dispersive x-ray spectroscopy, Raman spectroscopy and transmission electron microscopy. It is found that MgO and Ni nanoparticles together with hydrogen play important roles in the formation of the spheres. A possible formation mechanism for the carbon composites has been proposed.

  10. Enhanced nonlinearity of the propagation constant of a long-range surface-plasma wave

    SciTech Connect

    Sarid, D.; Deck, R.T.; Fasano, J.J.

    1982-10-01

    We calculate the power-dependent propagation constant of a surface-plasma wave as a function of the thickness of the metal film on which it propagates when the metal film is bounded by a nonlinear semiconductor. In the case of a Cu film bounded by InSb at a wavelength of approx.5 ..mu..m and a temperature of 5 K, we find that the effect of the nonlinearity on the propagation constant is enhanced by a factor of 10 as the metal thickness decreases from 120 to 15 nm.

  11. Structure of carbon nanotubes grown by microwave-plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Okai, M.; Muneyoshi, T.; Yaguchi, T.; Sasaki, S.

    2000-11-01

    Carbon nanotubes grown on a Ni substrate and an Fe-Ni-Cr alloy substrate by plasma-enhanced chemical vapor deposition were investigated by transmission electron microscope (TEM) and energy dispersive x-ray (EDX) analysis. TEM showed that the nanotubes on both substrates have a piled-cone structure with metal particles on top which determine the diameter of the nanotubes. Their diameter ranges from 60 to 80 nm. Moreover, EDX showed that the metal particles are composed of Ni when the nanotubes are grown on Ni substrate and of Fe and Ni in the case of the Fe-Ni-Cr alloy substrate.

  12. Properties of Plasma Enhanced Chemical Vapor Deposition Barrier Coatings and Encapsulated Polymer Solar Cells

    NASA Astrophysics Data System (ADS)

    Qi, Lei; Zhang, Chunmei; Chen, Qiang

    2014-01-01

    In this paper, we report silicon oxide coatings deposited by plasma enhanced chemical vapor deposition technology (PECVD) on 125 μm polyethyleneterephthalate (PET) surfaces for the purpose of the shelf lifetime extension of sealed polymer solar cells. After optimization of the processing parameters, we achieved a water vapor transmission rate (WVTR) of ca. 10-3 g/m2/day with the oxygen transmission rate (OTR) less than 0.05 cc/m2/day, and succeeded in extending the shelf lifetime to about 400 h in encapsulated solar cells. And then the chemical structure of coatings related to the properties of encapsulated cell was investigated in detail.

  13. Microstructural modification of nc-Si/SiOx films during plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhang, X. W.

    2005-07-01

    Nanocrystalline-silicon embedded silicon oxide films are prepared by plasma-enhanced chemical vapor deposition (PECVD) at 300 °C without post-heat treatment. Measurements of XPS, IR, XRD, and HREM are performed. Microstructural modifications are found occurring throughout the film deposition. The silica network with a high oxide state is suggested to be formed directly under the abduction of the former deposited layer, rather than processing repeatedly from the original low-oxide state of silica. Nanocrystalline silicon particles with a size of 6-10 nm are embedded in the SiOx film matrix, indicating the potential application in Si-based optoelectronic integrity.

  14. Laughter counteracts enhancement of plasma neurotrophin levels and allergic skin wheal responses by mobile phone-mediated stress.

    PubMed

    Kimata, Hajime

    2004-01-01

    Laughter caused by viewing a comic video (Rowan Atkinson's The Best Bits of Mr. Bean) reduced the plasma nerve growth factor, neurotrophin-3 levels, and allergic skin wheal responses in patients with atopic dermatitis, whereas viewing a nonhumorous video (weather information) failed to do so. In contrast, stress induced by writing mail on a mobile phone enhanced the plasma nerve growth factor, neurotrophin-3 levels, and allergic skin wheal responses. However, previewing the comic video counteracted mobile phone-mediated enhancement of plasma neurotrophins or allergic skin wheal responses, whereas previewing the weather information failed to do so. Taken together, these results suggest that, in patients with atopic dermatitis, writing mail on a mobile phone causes stress and enhances allergic responses with a concomitant increase in plasma neurotrophins that are counteracted by laughter. These results may be useful in the study of pathophysiology and treatment of atopic dermatitis.

  15. Development and Characterization of a Hybrid Atmospheric Pressure Plasma Electrospinning System for Nanofiber Enhancement

    NASA Astrophysics Data System (ADS)

    Nowak, Joshua Michael

    A hybrid atmospheric pressure-electrospinning plasma system was developed to be used for the production of nanofibers and enhance their performance for various applications. Electrospun nanofibers are excellent candidates for protective clothing in the field of chemical and biological warfare defense; however, nanofibers are structurally weak and easily abrade and tear. They can be strengthened through the support of a substrate fabric, but they do not adhere well to substrates. Through the use of the developed hybrid system with either pure He or He/O2 (99/1) feed gas, adherence to the substrate along with abrasion and flex resistance were improved. The plasma source was diagnosed electrically, thermally, and optically. An equivalent circuit model was developed for non-thermal, highly collisional plasmas that can solve for average electron temperature and electron number density. The obtained temperatures (~ 3eV) correlate very well with the results of a neutral Bremsstrahlung continuum matching technique that was also employed. Using the temperatures and number densities obtained from the circuit model and the optical spectroscopy, a global chemical kinetics code was written in order to solve for radical and ion concentrations. This code shows that there are significant concentrations of oxygen radicals present. The XPS analysis confirmed that there was an increase of surface oxygen from 11.1% up to 16.6% for the He/O2 plasma and that the C-O bonding, which was not present in the control samples, has increased to 45.4%. The adhesive strength to the substrate has a significant increase of 81% for helium plasma and 144% for He/O2 plasma; however, these values remain below the desired values for protective clothing applications. The hybrid system displayed the ability to oxygenate nanofibers as they are being electrospun and shows the feasibility of making other surface modifications. The developed circuit model and chemical kinetics code both show promise as tools

  16. Portable nanosecond pulsed air plasma jet

    SciTech Connect

    Walsh, J. L.; Kong, M. G.

    2011-08-22

    Low-temperature atmospheric pressure plasmas are of great importance in many emerging biomedical and materials processing applications. The redundancy of a vacuum system opens the gateway for highly portable plasma systems, for which air ideally becomes the plasma-forming gas and remote plasma processing is preferred to ensure electrical safety. Typically, the gas temperature observed in air plasma greatly exceeds that suitable for the processing of thermally liable materials; a large plasma-sample distance offers a potential solution but suffers from a diluted downstream plasma chemistry. This Letter reports a highly portable air plasma jet system which delivers enhanced downstream chemistry without compromising the low temperature nature of the discharge, thus forming the basis of a powerful tool for emerging mobile plasma applications.

  17. Plasma-assisted nitrogen doping of VACNTs for efficiently enhancing the supercapacitor performance

    NASA Astrophysics Data System (ADS)

    Mashayekhi, Alireza; Hosseini, Seyed Mahmoud; Hassanpour Amiri, Morteza; Namdar, Naser; Sanaee, Zeinab

    2016-06-01

    Nitrogen doping of vertically aligned carbon nanotubes (VACNTs) using plasma-enhanced chemical vapour deposition has been investigated to improve the supercapacitance performance of CNTs. Incorporating electrochemical measurements on the open-ended nitrogen-doped CNTs, showed the achievement of 6 times improvement in the capacitance value. For nitrogen-doped CNTs on silicon substrate, specific capacitance of 60 F g-1 was obtained in 0.5 M KCl solution, with capacity retention ratio above 90 % after cycled at 0.1 A g-1 for 5000 cycles. Using this sample, a symmetric supercapacitance was fabricated which showed the power density of 37.5 kW kg-1. The facile fabrication approach and its excellent capacitance improvement, propose it as an efficient technique for enhancing the supercapacitance performance of the carbon-based electrodes.

  18. Plasma Creatine Kinetics After Ingestion of Microencapsulated Creatine Monohydrate with Enhanced Stability in Aqueous Solutions.

    PubMed

    Hone, Michelle; Kent, Robert M; Scotto di Palumbo, Alessandro; Bleiel, Sinead B; De Vito, Giuseppe; Egan, Brendan

    2017-07-04

    Creatine monohydrate represents one of the largest sports supplement markets. Enhancing creatine (CRE) stability in aqueous solutions, such as with microencapsulation, represents innovation potential. Ten physically active male volunteers were randomly assigned in a double-blind design to either placebo (PLA) (3-g maltodextrin; n = 5) or microencapsulated CRE (3-g creatine monohydrate; n = 5) conditions. Experimental conditions involved ingestion of the samples in a 70-mL ready-to-drink format. CRE was delivered in a novel microencapsulation matrix material consisting entirely of hydrolyzed milk protein. Three hours after ingestion, plasma creatine concentrations were unchanged during PLA, and averaged ∼45 μM. During CRE, plasma creatine concentration peaked after 30 min at 101.6 ± 14.9 μM (p < 0.05), representing a 2.3-fold increase over PLA. Thereafter, plasma creatine concentration gradually trended downwards but remained significantly elevated (∼50% above resting levels) 3 hr after ingestion. These results demonstrate that the microencapsulated form of creatine monohydrate reported herein remains bioavailable when delivered in aqueous conditions, and has potential utility in ready-to-drink formulations for creatine supplementation.

  19. Enhancement of photovoltaic response in multilayer MoS2 induced by plasma doping.

    PubMed

    Wi, Sungjin; Kim, Hyunsoo; Chen, Mikai; Nam, Hongsuk; Guo, L Jay; Meyhofer, Edgar; Liang, Xiaogan

    2014-05-27

    Layered transition-metal dichalcogenides hold promise for making ultrathin-film photovoltaic devices with a combination of excellent photovoltaic performance, superior flexibility, long lifetime, and low manufacturing cost. Engineering the proper band structures of such layered materials is essential to realize such potential. Here, we present a plasma-assisted doping approach for significantly improving the photovoltaic response in multilayer MoS2. In this work, we fabricated and characterized photovoltaic devices with a vertically stacked indium tin oxide electrode/multilayer MoS2/metal electrode structure. Utilizing a plasma-induced p-doping approach, we are able to form p-n junctions in MoS2 layers that facilitate the collection of photogenerated carriers, enhance the photovoltages, and decrease reverse dark currents. Using plasma-assisted doping processes, we have demonstrated MoS2-based photovoltaic devices exhibiting very high short-circuit photocurrent density values up to 20.9 mA/cm(2) and reasonably good power-conversion efficiencies up to 2.8% under AM1.5G illumination, as well as high external quantum efficiencies. We believe that this work provides important scientific insights for leveraging the optoelectronic properties of emerging atomically layered two-dimensional materials for photovoltaic and other optoelectronic applications.

  20. Hole injection enhancement in organic light emitting devices using plasma treated graphene oxide

    NASA Astrophysics Data System (ADS)

    Jesuraj, P. Justin; Parameshwari, R.; Kanthasamy, K.; Koch, J.; Pfnür, H.; Jeganathan, K.

    2017-03-01

    The hole injection layer (HIL) with high work function (WF) is desirable to reduce the injection barrier between anode and hole transport layer in organic light emitting devices (OLED). Here, we report a novel approach to tune the WF of graphene oxide (GO) using oxygen and hydrogen plasma treatment and its hole injection properties in OLEDs. The mild exposure of oxygen plasma on GO (O2-GO) significantly reduces the injection barrier by increasing the WF of anode (4.98 eV) through expansion of Csbnd O bonds. In contrast, the hole injection barrier was drastically increased for hydrogen plasma treated GO (H2-GO) layers as the WF is lowered by the contraction of Csbnd O bond. By employing active O2-GO as HIL in OLEDs found to exhibit superior current efficiency of 4.2 cd/A as compared to 3.3 cd/A for pristine GO. Further, the high injection efficiency of O2-GO infused hole only device can be attributed to the improved energy level matching. Ultraviolet and X-ray photoelectron spectroscopy were used to correlate the WF of HIL infused anode towards the enhanced performance of OLEDs with their capricious content of Csbnd O in GO matrix.

  1. Fluorinated carboxylic membranes deposited by plasma enhanced chemical vapour deposition for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Thery, J.; Martin, S.; Faucheux, V.; Le Van Jodin, L.; Truffier-Boutry, D.; Martinent, A.; Laurent, J.-Y.

    Among the fuel cell technologies, the polymer electrolyte membrane fuel cells (PEMFCs) are particularly promising because they are energy-efficient, clean, and fuel-flexible (i.e., can use hydrogen or methanol). The great majority of PEM fuel cells rely on a polymer electrolyte from the family of perfluorosulfonic acid membranes, nevertheless alternative materials are currently being developed, mainly to offer the alternative workout techniques which are required for the portable energy sources. Plasma polymerization represents a good solution, as it offers the possibility to deposit thin layer with an accurate and homogeneous thickness, even on 3D surfaces. In this paper, we present the results for the growth of proton conductive fluoro carboxylic membranes elaborated by plasma enhanced chemical vapour deposition. These membranes present conductivity values of the same order than the one of Nafion ®. The properties of the membrane, such as the chemical composition, the ionic conductivity, the swelling behaviour and the permeability were correlated to the plasma process parameters. The membranes were integrated in fuel cells on porous substrates and we present here the results regarding the barrier effect and the power output. Barrier effect similar to those of 40 μm Nafion ® layers was reached for 10 μm thick carboxylic membranes. Power outputs around 3 mW cm -2 were measured. We discuss the results regarding the gas barrier effect and the power outputs.

  2. Refraction-Enhanced X-ray Radiography for Inertial Confinement Fusion and Laser-Produced Plasma Applications

    SciTech Connect

    Koch, J A; Landen, O L; Kozioziemski, B J; Izumi, N; Dewald, E L; Salmonson, J D; Hammel, B A

    2008-08-26

    We explore various laser-produced plasma and inertial-confinement fusion (ICF) applications of phase-contrast x-ray radiography, and we show how the main features of these enhancements can be considered from a geometrical optics perspective as refraction enhancements. This perspective simplifies the analysis, and often permits simple analytical formulae to be derived that predict the enhancements. We explore a raytrace approach to various material interface applications, and we explore a more general example of refractive bending of x-rays by an implosion plasma. We find that refraction-enhanced x-ray radiography of implosions may provide a means to quantify density differences across shock fronts as well as density variations caused by local heating due to high-Z dopants. We also point out that refractive bending by implosions plasmas can blur fine radiograph features, and can also provide misleading contrast information in area-backlit pinhole imaging experiments unless its effects are taken into consideration.

  3. Mechanisms of bacterial inactivation in the liquid phase induced by a remote RF cold atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    van Gils, C. A. J.; Hofmann, S.; Boekema, B. K. H. L.; Brandenburg, R.; Bruggeman, P. J.

    2013-05-01

    A radio-frequency atmospheric pressure argon plasma jet is used for the inactivation of bacteria (Pseudomonas aeruginosa) in solutions. The source is characterized by measurements of power dissipation, gas temperature, absolute UV irradiance as well as mass spectrometry measurements of emitted ions. The plasma-induced liquid chemistry is studied by performing liquid ion chromatography and hydrogen peroxide concentration measurements on treated distilled water samples. Additionally, a quantitative estimation of an extensive liquid chemistry induced by the plasma is made by solution kinetics calculations. The role of the different active components of the plasma is evaluated based on either measurements, as mentioned above, or estimations based on published data of measurements of those components. For the experimental conditions being considered in this work, it is shown that the bactericidal effect can be solely ascribed to plasma-induced liquid chemistry, leading to the production of stable and transient chemical species. It is shown that HNO2, ONOO- and H2O2 are present in the liquid phase in similar quantities to concentrations which are reported in the literature to cause bacterial inactivation. The importance of plasma-induced chemistry at the gas-liquid interface is illustrated and discussed in detail.

  4. Characterization of TiO x film prepared by plasma enhanced chemical vapor deposition using a multi-jet hollow cathode plasma source

    NASA Astrophysics Data System (ADS)

    Nakamura, Masatoshi; Korzec, Dariusz; Aoki, Toru; Engemann, Jurgen; Hatanaka, Yoshinori

    2001-05-01

    The high rate deposition of TiO x film at low temperature was achieved by plasma enhanced chemical vapor deposition (PECVD) using titanium tetraisopropoxide (TTIP) as a source material. The multi-jet hollow cathode plasma source was used to generate the high-density plasma, which was showered toward the substrate. The emission spectra suggest that oxygen radicals play an important role for dissociation of the source material and for yielding the precursors. The high deposition rate up to 50 nm/min was achieved by this process. The as-deposited films are completely amorphous. They consist of structures with complex bondings including both tetrahedral and octahedral components. Though they have such complex bondings, the hydrophilicity of the PECVD film is excellent comparing to that of the annealed crystalline anatase structure. It seems that the PECVD using the multi-jet plasma source is promising for fabrication of hydrophilic TiO x films in low-temperature process.

  5. Growth of Er-doped silicon using metalorganics by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Andry, P. S.; Varhue, W. J.; Ladipo, F.; Ahmed, K.; Adams, E.; Lavoie, M.; Klein, P. B.; Hengehold, R.; Hunter, J.

    1996-07-01

    Epitaxial growth of Er-doped silicon films has been performed by plasma-enhanced chemical vapor deposition at low temperature (430 °C) using an electron cyclotron resonance source. The goal was to incorporate an optically active center, erbium surrounded by nitrogen, through the use of the metalorganic compound tris (bis trimethyl silyl amido) erbium. Films were analyzed by Rutherford backscattering spectrometry, secondary ion mass spectroscopy, and high resolution x-ray diffraction. The characteristic 1.54 μm emission was observed by photoluminescence spectroscopy. Previous attempts to incorporate the complex (ErO6) using tris (2,2,6,6-tetramethyl- 3,5-heptanedionato) erbium (III) indicated that excessive carbon contamination lowered epitaxial quality and reduced photoluminescent intensity. In this study, chemical analysis of the films also revealed a large carbon concentration, however, the effect on epitaxial quality was much less destructive. A factorial design experiment was performed whose analysis identified the key processing parameters leading to high quality luminescent films. Hydrogen was found to be a major cause of crystal quality degradation in our metalorganic plasma-enhanced process.

  6. Plasma Surface Functionalized Polyetheretherketone for Enhanced Osseo-Integration at Bone-Implant Interface.

    PubMed

    Zhao, Ying; Wong, Hoi Man; Lui, So Ching; Chong, Eva Y W; Wu, Guosong; Zhao, Xiaoli; Wang, Chong; Pan, Haobo; Cheung, Kenneth M C; Wu, Shuilin; Chu, Paul K; Yeung, Kelvin W K

    2016-02-17

    This study aims at improving osseo-integration at the bone-implant interface of polyetheretherketone (PEEK) by water (H2O) and ammonia (NH3) plasma immersion ion implantation (PIII). The pertinent surface characteristics including surface energy, roughness, morphology, and chemical composition are investigated systematically and the in vitro biological performance is evaluated by cell adhesion and proliferation, alkaline phosphatase (ALP) activity, real-time RT-PCR evaluation, and mineralization tests. In vivo osseo-integration is examined via implanting samples into the distal femur of the rats. The hydrophilicity, surface roughness, cell adhesion, and proliferation, ALP activity, and osteogenic differentiation after H2O PIII or NH3 PIII are improved significantly. Furthermore, substantially enhanced osseo-integration is achieved in vivo. Nonline-of-sight plasma surface functionalization, which is particularly suitable for biomedical implants with an irregular geometry, does not alter the bulk compressive yield strength and elastic modulus of the materials. Consequently, the favorable bulk attributes of PEEK are preserved while the surface biological properties are enhanced thus boding well for wider orthopedic application of the biopolymer.

  7. Instability-Enhanced Collisional Friction Determines the Bohm Criterion in Multiple-Ion-Species Plasmas

    NASA Astrophysics Data System (ADS)

    Baalrud, S. D.; Hegna, C. C.; Callen, J. D.

    2009-11-01

    Ion-ion streaming instabilities are excited in the presheath region of plasmas with multiple ion species if the ions are much colder than the electrons. Streaming instabilities onset when the relative fluid flow between ion species exceeds a critical speed, δVc, of order the ion thermal speeds. Using a generalized Lenard-Balescu theory that accounts for instability-enhanced collective responses [1], one is able to show the instabilities rapidly enhance the collisional friction between ion species far beyond the contribution from Coulomb collisions alone. This strong frictional force determines the relative fluid speed between species. When this condition is combined with the Bohm criterion generalized for multiple ion species, the fluid speed of each ion species is determined at the sheath edge. For each species, this speed differs from the common ``system'' sound speed by a factor that depends on the species concentrations, masses and δVc.[4pt] [1] S.D. Baalrud, J.D. Callen, and C.C. Hegna, Phys. Plasmas 15, 092111 (2008).

  8. Gamma-hydroxybutyrate enhances mood and prosocial behavior without affecting plasma oxytocin and testosterone.

    PubMed

    Bosch, Oliver G; Eisenegger, Christoph; Gertsch, Jürg; von Rotz, Robin; Dornbierer, Dario; Gachet, M Salomé; Heinrichs, Markus; Wetter, Thomas C; Seifritz, Erich; Quednow, Boris B

    2015-12-01

    Gamma-hydroxybutyrate (GHB) is a GHB-/GABAB-receptor agonist. Reports from GHB abusers indicate euphoric, prosocial, and empathogenic effects of the drug. We measured the effects of GHB on mood, prosocial behavior, social and non-social cognition and assessed potential underlying neuroendocrine mechanisms. GHB (20mg/kg) was tested in 16 healthy males, using a randomized, placebo-controlled, cross-over design. Subjective effects on mood were assessed by visual-analogue-scales and the GHB-Specific-Questionnaire. Prosocial behavior was examined by the Charity Donation Task, the Social Value Orientation test, and the Reciprocity Task. Reaction time, memory, empathy, and theory-of-mind were also tested. Blood plasma levels of GHB, oxytocin, testosterone, progesterone, dehydroepiandrosterone (DHEA), cortisol, aldosterone, and adrenocorticotropic-hormone (ACTH) were determined. GHB showed stimulating and sedating effects, and elicited euphoria, disinhibition, and enhanced vitality. In participants with low prosociality, the drug increased donations and prosocial money distributions. In contrast, social cognitive abilities such as emotion recognition, empathy, and theory-of-mind, and basal cognitive functions were not affected. GHB increased plasma progesterone, while oxytocin and testosterone, cortisol, aldosterone, DHEA, and ACTH levels remained unaffected. GHB has mood-enhancing and prosocial effects without affecting social hormones such as oxytocin and testosterone. These data suggest a potential involvement of GHB-/GABAB-receptors and progesterone in mood and prosocial behavior.

  9. Monitoring Delamination of Plasma-Sprayed Thermal Barrier Coatings by Reflectance-Enhanced Luminescence

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Bencic, Timothy J.

    2006-01-01

    Highly scattering plasma-sprayed thermal barrier coatings (TBCs) present a challenge for optical diagnostic methods to monitor TBC delamination because scattering attenuates light transmitted through the TBC and usually degrades contrast between attached and delaminated regions of the TBC. This paper presents a new approach where reflectance-enhanced luminescence from a luminescent sublayer incorporated along the bottom of the TBC is used to identify regions of TBC delamination. Because of the higher survival rate of luminescence reflecting off the back surface of a delaminated TBC, the strong scattering exhibited by plasma-sprayed TBCs actually accentuates contrast between attached and delaminated regions by making it more likely that multiple reflections of luminescence off the back surface occur before exiting the top surface of the TBC. A freestanding coating containing sections designed to model an attached or delaminated TBC was prepared by depositing a luminescent Eu-doped or Er-doped yttria-stabilized zirconia (YSZ) luminescent layer below a plasma-sprayed undoped YSZ layer and utilizing a NiCr backing layer to represent an attached substrate. For specimens with a Eu-doped YSZ luminescent sublayer, luminescence intensity maps showed excellent contrast between unbacked and NiCr-backed sections even at a plasma-sprayed overlayer thickness of 300 m. Discernable contrast between unbacked and NiCr-backed sections was not observed for specimens with a Er-doped YSZ luminescent sublayer because luminescence from Er impurities in the undoped YSZ layer overwhelmed luminescence originating form the Er-doped YSZ sublayer.

  10. Enhancing The Mode Conversion Efficiency In JET Plasmas With Multiple Mode Conversion Layers

    NASA Astrophysics Data System (ADS)

    Van Eester, D.; Lerche, E.; Johnson, T.; Hellsten, T.; Ongena, J.; Mayoral, M.-L.; Frigione, D.; Sozzi, C.; Calabro, G.; Lennholm, M.; Beaumont, P.; Blackman, T.; Brennan, D.; Brett, A.; Cecconello, M.; Coffey, I.; Coyne, A.; Crombe, K.; Czarnecka, A.; Felton, R.; Johnson, M. Gatu; Giroud, C.; Gorini, G.; Hellesen, C.; Jacquet, P.; Kazakov, Y.; Kiptily, V.; Knipe, S.; Krasilnikov, A.; Lin, Y.; Maslov, M.; Monakhov, I.; Noble, C.; Nocente, M.; Pangioni, L.; Proverbio, I.; Stamp, M.; Studholme, W.; Tardocchi, M.; Versloot, T. W.; Vdovin, V.; Whitehurst, A.; Wooldridge, E.; Zoita, V.

    2011-12-01

    The constructive interference effect described by Fuchs et al. [1] shows that the mode conversion and thereby the overall heating efficiency can be enhanced significantly when an integer number of fast wave wavelengths can be folded in between the high field side fast wave cutoff and the ion-ion hybrid layer(s) at which the ion Bernstein or ion cyclotron waves are excited. This effect was already experimentally identified in (3He)-D plasmas [2] and was recently tested in (3He)-H JET plasmas. The latter is an `inverted' scenario, which differs significantly from the (3He)-D scenarios since the mode-conversion layer is positioned between the low field side edge of the plasma and the ion-cyclotron layer of the minority 3He ions (whereas the order in which a wave entering the plasma from the low field side encounters these layers is inverted in a `regular' scenario), and because much lower 3He concentrations are needed to achieve the mode-conversion heating regime. The presence of small amounts of 4He and D in the discharges gave rise to an additional mode conversion layer on top of the expected one associated with 3He-H, which made the interpretation of the results more complex but also more interesting: Three different regimes could be distinguished as a function of X[3He], and the differing dynamics at the various concentrations could be traced back to the presence of these two mode conversion layers and their associated fast wave cutoffs. Whereas (1-D and 2-D) numerical modeling yields quantitative information on the RF absorptivity, recent analytical work by Kazakov [3] permits to grasp the dominant underlying wave interaction physics.

  11. Practical silicon deposition rules derived from silane monitoring during plasma-enhanced chemical vapor deposition

    SciTech Connect

    Bartlome, Richard De Wolf, Stefaan; Demaurex, Bénédicte; Ballif, Christophe; Amanatides, Eleftherios; Mataras, Dimitrios

    2015-05-28

    We clarify the difference between the SiH{sub 4} consumption efficiency η and the SiH{sub 4} depletion fraction D, as measured in the pumping line and the actual reactor of an industrial plasma-enhanced chemical vapor deposition system. In the absence of significant polysilane and powder formation, η is proportional to the film growth rate. Above a certain powder formation threshold, any additional amount of SiH{sub 4} consumed translates into increased powder formation rather than into a faster growing Si film. In order to discuss a zero-dimensional analytical model and a two-dimensional numerical model, we measure η as a function of the radio frequency (RF) power density coupled into the plasma, the total gas flow rate, the input SiH{sub 4} concentration, and the reactor pressure. The adjunction of a small trimethylboron flow rate increases η and reduces the formation of powder, while the adjunction of a small disilane flow rate decreases η and favors the formation of powder. Unlike η, D is a location-dependent quantity. It is related to the SiH{sub 4} concentration in the plasma c{sub p}, and to the phase of the growing Si film, whether the substrate is glass or a c-Si wafer. In order to investigate transient effects due to the RF matching, the precoating of reactor walls, or the introduction of a purifier in the gas line, we measure the gas residence time and acquire time-resolved SiH{sub 4} density measurements throughout the ignition and the termination of a plasma.

  12. Enhanced efficiency of plasma acceleration in the laser-induced cavity pressure acceleration scheme

    NASA Astrophysics Data System (ADS)

    Badziak, J.; Rosiński, M.; Jabłoński, S.; Pisarczyk, T.; Chodukowski, T.; Parys, P.; Rączka, P.; Krousky, E.; Ullschmied, J.; Liska, R.; Kucharik, M.

    2015-01-01

    Among various methods for the acceleration of dense plasmas the mechanism called laser-induced cavity pressure acceleration (LICPA) is capable of achieving the highest energetic efficiency. In the LICPA scheme, a projectile placed in a cavity is accelerated along a guiding channel by the laser-induced thermal plasma pressure or by the radiation pressure of an intense laser radiation trapped in the cavity. This arrangement leads to a significant enhancement of the hydrodynamic or electromagnetic forces driving the projectile, relative to standard laser acceleration schemes. The aim of this paper is to review recent experimental and numerical works on LICPA with the emphasis on the acceleration of heavy plasma macroparticles and dense ion beams. The main experimental part concerns the research carried out at the kilojoule sub-nanosecond PALS laser facility in Prague. Our measurements performed at this facility, supported by advanced two-dimensional hydrodynamic simulations, have demonstrated that the LICPA accelerator working in the long-pulse hydrodynamic regime can be a highly efficient tool for the acceleration of heavy plasma macroparticles to hyper-velocities and the generation of ultra-high-pressure (>100 Mbar) shocks through the collision of the macroparticle with a solid target. The energetic efficiency of the macroparticle acceleration and the shock generation has been found to be significantly higher than that for other laser-based methods used so far. Using particle-in-cell simulations it is shown that the LICPA scheme is highly efficient also in the short-pulse high-intensity regime and, in particular, may be used for production of intense ion beams of multi-MeV to GeV ion energies with the energetic efficiency of tens of per cent, much higher than for conventional laser acceleration schemes.

  13. Enhanced Satellite Remote Sensing of Coastal Waters Using Spatially Improved Bio-Optical Products from SNPP-VIIRS

    DTIC Science & Technology

    2015-01-01

    Cambridge University Press. Kutser, T. (2009). Passive optical remote sensing of cyanobacteria and other intense phy- toplankton blooms in coastal and...M.W., Bernard, S., & Winter, K. (2010). Remote sensing of cyanobacteria - dominant algal blooms andwater quality parameters in Zeekoevlei, a small

  14. Inactivation of the Anterior Cingulate Reveals Enhanced Reliance on Cortical Networks for Remote Spatial Memory Retrieval after Sequential Memory Processing

    PubMed Central

    Wartman, Brianne C.; Gabel, Jennifer; Holahan, Matthew R.

    2014-01-01

    One system consolidation model suggests that as time passes, ensembles of cortical neurons form strong connections to represent remote memories. In this model, the anterior cingulate cortex (ACC) serves as a cortical region that represents remote memories. However, there is debate as to whether remote spatial memories go through this systems consolidation process and come to rely on the ACC. The present experiment examined whether increasing the processing demand on the hippocampus, by sequential training on two spatial tasks, would more fully engage the ACC during retrieval of a remote spatial memory. In this scenario, inactivation of the ACC at a remote time point was hypothesized to produce a severe memory deficit if rats had been trained on two, sequential spatial tasks. Rats were trained on a water maze (WM) task only or a WM task followed by a radial arm maze task. A WM probe test was given recently or remotely to all rats. Prior to the probe test, rats received an injection of saline or muscimol into the ACC. A subtle deficit in probe performance was found at the remote time point in the group trained on only one spatial task and treated with muscimol. In the group trained on two spatial tasks and treated with muscimol, a subtle deficit in probe performance was noted at the recent time point and a substantial deficit in probe performance was observed at the remote time point. c-Fos labeling in the hippocampus revealed more labeling in the CA1 region in all remotely tested groups than recently tested groups. Findings suggest that spatial remote memories come to rely more fully on the ACC when hippocampal processing requirements are increased. Results also suggest continued involvement of the hippocampus in spatial memory retrieval along with a progressive strengthening of cortical connections as time progresses. PMID:25279556

  15. Surface plasmon resonance measurement of AlOx insulating barriers in magnetic tunnel junctions formed by remote rf plasma oxidation process

    NASA Astrophysics Data System (ADS)

    Park, J. H.; Yoon, K. S.; Yang, J. Y.; Kim, E. K.; Lee, C. H.; Kim, C. O.; Hong, J. P.

    2002-09-01

    A surface plasmon resonance spectroscopy (SPRS) measurement was carried out to determine dielectric properties, oxidation states, and optimum thickness of AlOx insulating barrier in magnetic tunnel junctions. The insulating barriers were prepared as a function of oxidation time by using a remote rf plasma oxidation process. The experimental results revealed that the dielectric value and optimum thickness of the AlOx insulating barrier in our junctions were found to be 1.79+i1.77 and 11.26 A, respectively. For comparison, the magnetic tunneling junction was also fabricated using the same oxidation condition. The best magneto-resistance ratio of about 34% was observed at an optimum oxidation time of 70 s, as expected by the SPRS measurement.

  16. Film properties of low temperature HfO{sub 2} grown with H{sub 2}O, O{sub 3}, or remote O{sub 2}-plasma

    SciTech Connect

    Richter, Claudia Schenk, Tony; Schroeder, Uwe; Mikolajick, Thomas

    2014-01-15

    A reduction of the deposition temperature is necessary for atomic layer deposition (ALD) on organic devices. HfO{sub 2} films were deposited by ALD on silicon substrates in a wide temperature range from 80 to 300 °C with tetrakis[ethylmethylamino]hafnium as metal precursor and H{sub 2}O, O{sub 3}, or an remote O{sub 2}-plasma as oxygen source. Growth rate and density were correlated to electrical properties like dielectric constant and leakage current of simple capacitor structures to evaluate the impact of different process conditions. Process optimizations were performed to reduce film imperfections visible at lower deposition temperatures. Additionally, the influence of postdeposition annealing on the structural and electrical properties was studied.

  17. Conception of a novel spray tower plasma-reactor in a spatial post-discharge configuration: Pollutants remote treatment.

    PubMed

    Ferhat, Mohamed Fouad; Ghezzar, Mouffok Redouane; Smaïl, Bentaïba; Guyon, Cedric; Ognier, Stéphanie; Addou, Ahmed

    2017-01-05

    This paper describes a novel gliding Arc discharge reactor producing a non-thermal plasma at atmospheric pressure in humid air. The ionized gas is generated in a spray-tower absorber for the treatment of organic pollutants. The reactor configuration enables the plasma-degradation of micro-droplets effluents in the spatial post-discharge mode. This type of design allows to exclude the direct contact between the plasma plume and the liquid to be treated in order to avoid the liquid heating and the flame extinction problems. A hydrodynamic study coupling 'Navier-Stokes' equations and those of 'Convection-Diffusion' allowed to calculate the concentration profiles and the droplet falling velocity. The stripping of phenol was studied to valid the hydrodynamic approach. Experiences and simulations showed that after 1h of treatment, only 5% of the compound was transferred into the plasma phase. The spatiality of the novel reactor allowed a degradation rate of 100% for catechol after 38min of plasma-treatment. For 4-nitrophenol, the degradation rate reached 90% after 120min. Phenol and its by-products degradation were totally degraded by combining the spatiality of the reactor and the temporal post-discharge. A degradation mechanism was proposed and a plasmachemical reaction in relation with the pernitrous acid species was confirmed.

  18. A thermocouple-based remote temperature controller of an electrically floated sample to study plasma CVD growth of carbon nanotube

    NASA Astrophysics Data System (ADS)

    Miura, Takuya; Xie, Wei; Yanase, Takashi; Nagahama, Taro; Shimada, Toshihiro

    2015-09-01

    Plasma chemical vapor deposition (CVD) is now gathering attention from a novel viewpoint, because it is easy to combine plasma processes and electrochemistry by applying a bias voltage to the sample. In order to explore electrochemistry during the plasma CVD, the temperature of the sample must be controlled precisely. In traditional equipment, the sample temperature is measured by a radiation thermometer. Since emissivity of the sample surface changes in the course of the CVD growth, it is difficult to measure the exact temperature using the radiation thermometer. In this work, we developed new equipment to control the temperature of electrically floated samples by thermocouple with Wi-Fi transmission. The growth of the CNT was investigated using our plasma CVD equipment. We examined the temperature accuracy and stability controlled by the thermocouple with monitoring the radiation thermometer. We noticed that the thermocouple readings were stable, whereas the readings of the radiation thermometer changes significantly (20 °C) during plasma CVD. This result clearly shows that the sample temperature should be measured with direct connection. On the result of CVD experiment, different structures of carbon including CNT were obtained by changing the bias voltages.

  19. Enhanced generation of a second-harmonic wave in a composite of metamaterial and microwave plasma with various permittivities.

    PubMed

    Iwai, Akinori; Nakamura, Yoshihiro; Sakai, Osamu

    2015-09-01

    The generation of a second-harmonic wave, which is one typical nonlinear feature, is enhanced in a composite of plasma and metamaterial. When we generate plasma by an injection of microwaves, whose frequencies are fundamental, we observe intensified second-harmonic waves in the cases of negative-refractive-index states in which both metamaterial permeability and plasma permittivity are negative for the fundamental waves. We performed the measurements at multiple levels of microwave input power up to 300 W to regulate permittivity in the negative polarity for the fundamental wave and in the transient region, including the positive-zero-negative values, for the second-harmonic wave. We clarified that the observed enhancement results from high electron density in negative-permittivity plasma, the propagating fundamental frequency wave not being attenuated in the negative-refractive-index state, and partial phase matching between the fundamental and second-harmonic waves.

  20. Interface Electronic State Characterization of Plasma Enhanced Atomic Layer Deposited Dielectrics on GaN

    NASA Astrophysics Data System (ADS)

    Yang, Jialing

    In this dissertation, the interface chemistry and electronic structure of plasma-enhanced atomic layer deposited (PEALD) dielectrics on GaN are investigated with x-ray and ultraviolet photoemission spectroscopy (XPS and UPS). Three interrelated issues are discussed in this study: (1) PEALD dielectric growth process optimization, (2) interface electronic structure of comparative PEALD dielectrics on GaN, and (3) interface electronic structure of PEALD dielectrics on Ga- and N-face GaN. The first study involved an in-depth case study of PEALD Al2O3 growth using dimethylaluminum isopropoxide, with a special focus on oxygen plasma effects. Saturated and self-limiting growth of Al2O3 films were obtained with an enhanced growth rate within the PEALD temperature window (25--220 °C). The properties of Al2O3 deposited at various temperatures were characterized to better understand the relation between the growth parameters and film properties. In the second study, the interface electronic structures of PEALD dielectrics on Ga-face GaN films were measured. Five promising dielectrics (Al2O3, HfO2, SiO2, La2O 3, and ZnO) with a range of band gap energies were chosen. Prior to dielectric growth, a combined wet chemical and in-situ H 2/N2 plasma clean process was employed to remove the carbon contamination and prepare the surface for dielectric deposition. The surface band bending and band offsets were measured by XPS and UPS for dielectrics on GaN. The trends of the experimental band offsets on GaN were related to the dielectric band gap energies. In addition, the experimental band offsets were near the calculated values based on the charge neutrality level model. The third study focused on the effect of the polarization bound charge of the Ga- and N-face GaN on interface electronic structures. A surface pretreatment process consisting of a NH4OH wet chemical and an in-situ NH3 plasma treatment was applied to remove carbon contamination, retain monolayer oxygen coverage, and

  1. Techniques for the remote sensing of space plasma in the heliosphere via energetic neutral atoms - A review

    NASA Technical Reports Server (NTRS)

    Hsieh, K. C.; Curtis, C. C.; Fan, C. Y.; Gruntman, M. A.

    1992-01-01

    A survey is conducted for state-of-the-art techniques for detecting energetic neutral atoms (ENAs) in the 100-300 keV range, in regions from the heliospheric boundary to the auroral zones where the solar wind plays a crucial role. While ENA spectrometry allows sampling of the mass and energy distributions of a distant plasma, ENA imaging gives a global view of the structures and dynamics of an extended plasma. The ENA instrument designs discussed share many components which exhibit excellent flight performance as elements in charged-particle analyzers for space missions.

  2. Efavirenz enhances HIV-1 gag processing at the plasma membrane through Gag-Pol dimerization.

    PubMed

    Sudo, Sho; Haraguchi, Hiyori; Hirai, Yoko; Gatanaga, Hiroyuki; Sakuragi, Jun-ichi; Momose, Fumitaka; Morikawa, Yuko

    2013-03-01

    Efavirenz (EFV), a nonnucleoside reverse transcriptase (RT) inhibitor, also inhibits HIV-1 particle release through enhanced Gag/Gag-Pol processing by protease (PR). To better understand the mechanisms of the EFV-mediated enhancement of Gag processing, we examined the intracellular localization of Gag/Gag-Pol processing products and their precursors. Confocal microscopy revealed that in the presence of EFV, the N-terminal p17 matrix (p17MA) fragment was uniformly distributed at the plasma membrane (PM) but the central p24 capsid (p24CA) and the Pol-encoded RT antigens were diffusely distributed in the cytoplasm, and all of the above were observed in puncta at the PM in the absence of EFV. EFV did not impair PM targeting of Gag/Gag-Pol precursors. Membrane flotation analysis confirmed these findings. Such uniform distribution of p17MA at the PM was not seen by overexpression of Gag-Pol and was suppressed when EFV-resistant HIV-1 was used. Forster's fluorescence resonance energy transfer assay revealed that Gag-Pol precursor dimerization occurred mainly at the PM and that EFV induced a significant increase of the Gag-Pol dimerization at the PM. Gag-Pol dimerization was not enhanced when HIV-1 contained the EFV resistance mutation in RT. Bacterial two-hybrid assay showed that EFV enhanced the dimerization of PR-RT fragments and restored the dimerization impaired by the dimerization-defective mutation in the RT tryptophan repeat motif but not that impaired by the mutation at the PR dimer interface. Collectively, our data indicate that EFV enhances Gag-Pol precursor dimerization, likely after PM targeting but before complete particle assembly, resulting in uniform distribution of p17MA to and dissociation of p24CA and RT from the PM.

  3. Plasma confinement to enhance the momentum coupling coefficient in ablative laser micro-propulsion: a novel approach

    NASA Astrophysics Data System (ADS)

    Ahmad, Muhammad Raza; Jamil, Yasir; Qaiser Zakaria, M.; Hussain, Tousif; Ahmad, Riaz

    2015-07-01

    We introduce for the first time the novel idea of manipulating the momentum coupling coefficient using plasma confinement and shock wave reflection from the cavity walls. The plasma was confined using cylindrical geometries of various cavity aspect ratios to manipulate the momentum coupling coefficient (C m ). The Nd: YAG laser (532 nm, 5 ns pulse duration) was focused on the ferrite sample surface to produce plasma in a region surrounded by cylindrical cavity walls. The multiple reflections of the shockwaves from the cavity walls confined the laser-induced plasma to the central region of the cavity that subsequently resulted in a significant enhancement of the momentum coupling coefficient values. The plasma shielding effect has also been observed for particular values of laser fluencies and cavity aspect ratios. Compared with the direct ablation, the confined ablation provides an effective way to obtain high C m values.

  4. Plasma gelsolin improves lung host defense against pneumonia by enhancing macrophage NOS3 function.

    PubMed

    Yang, Zhiping; Chiou, Terry Ting-Yu; Stossel, Thomas P; Kobzik, Lester

    2015-07-01

    Plasma gelsolin (pGSN) functions as part of the "extracellular actin-scavenging system," but its potential to improve host defense against infection has not been studied. In a mouse model of primary pneumococcal pneumonia, recombinant human pGSN (rhu-pGSN) caused enhanced bacterial clearance, reduced acute inflammation, and improved survival. In vitro, rhu-pGSN rapidly improved lung macrophage uptake and killing of bacteria (Streptococcus pneumoniae, Escherichia coli, and Francisella tularensis). pGSN triggers activating phosphorylation (Ser(1177)) of macrophage nitric oxide synthase type III (NOS3), an enzyme with important bactericidal functions in lung macrophages. rhu-pGSN failed to enhance bacterial killing by NOS3(-/-) macrophages in vitro or bacterial clearance in NOS3(-/-) mice in vivo. Prophylaxis with immunomodulators may be especially relevant for patients at risk for secondary bacterial pneumonia, e.g., after influenza. Treatment of mice with pGSN challenged with pneumococci on postinfluenza day 7 (the peak of enhanced susceptibility to secondary infection) caused a ∼15-fold improvement in bacterial clearance, reduced acute neutrophilic inflammation, and markedly improved survival, even without antibiotic therapy. pGSN is a potential immunomodulator for improving lung host defense against primary and secondary bacterial pneumonia.

  5. Characteristics of silicon nitride deposited by VHF (162 MHz)-plasma enhanced chemical vapor deposition using a multi-tile push-pull plasma source

    NASA Astrophysics Data System (ADS)

    Kim, Ki Seok; Sirse, Nishant; Kim, Ki Hyun; Rogers Ellingboe, Albert; Kim, Kyong Nam; Yeom, Geun Young

    2016-10-01

    To prevent moisture and oxygen permeation into flexible organic electronic devices formed on substrates, the deposition of an inorganic diffusion barrier material such as SiN x is important for thin film encapsulation. In this study, by a very high frequency (162 MHz) plasma-enhanced chemical vapor deposition (VHF-PECVD) using a multi-tile push-pull plasma source, SiN x layers were deposited with a gas mixture of NH3/SiH4 with/without N2 and the characteristics of the plasma and the deposited SiN x film as the thin film barrier were investigated. Compared to a lower frequency (60 MHz) plasma, the VHF (162 MHz) multi-tile push-pull plasma showed a lower electron temperature, a higher vibrational temperature, and higher N2 dissociation for an N2 plasma. When a SiN x layer was deposited with a mixture of NH3/SiH4 with N2 at a low temperature of 100 °C, a stoichiometric amorphous Si3N4 layer with very low Si-H bonding could be deposited. The 300 nm thick SiN x film exhibited a low water vapor transmission rate of 1.18  ×  10-4 g (m2 · d)-1, in addition to an optical transmittance of higher than 90%.

  6. Enhancement of cholesteryl ester transfer in plasma by hormone-replacement therapy.

    PubMed

    Ritsch, Andreas; Kaser, Susanne; Volgger, Birgit; Abfalter, Elisabeth; Sturm, Wolfgang; Gänzer, Hannes; Föger, Bernhard; Kirchmair, Rudolf; Ebenbichler, Christoph; Patsch, Josef R

    2002-05-01

    To study possible mechanisms for the suggested protective effect of hormone-replacement therapy (HRT) with respect to cardiovascular disease we investigated lipoprotein parameters, mass and activity of lipoprotein-metabolizing enzymes, magnitude of postprandial lipemia, and vascular endothelial function in 13 postmenopausal women. All patients were examined before and 3 months after implementation of HRT with estrogen alone (group A, n = 6) or estrogen plus gestagen (group B, n = 7). HRT (groups A and B) resulted in enhanced total transfer of cholesteryl ester (CE) from high-density lipoprotein (HDL) to apolipoprotein B (apoB)-containing lipoproteins (56% +/- 11.45% v 50.82% +/- 13.68%, P <.05) and increased apoA-I plasma concentration (171 +/- 30 v 147 +/- 22 mg/dL, P <.05). Fasting triglycerides (TG) were increased (134 +/- 40 v 115 +/- 39 mg/dL, P <.05). In group A patients the magnitude of postprandial lipemia increased significantly (1,737 +/- 756 v 1,475 +/- 930 mg TG/dL plasma/8 h, P <.05) without any change in lipoprotein lipase (LPL) activity, but with a concomitant decrease in low-density lipoprotein (LDL) size. In both groups flow-mediated dilation (FMD) reflecting vascular endothelial function was not influenced, suggesting that HRT may not directly affect vascular function but rather alters lipoprotein metabolism. The increase of apoA-I was not accompanied by an equivalent rise of HDL cholesterol. Based on the present data this finding can be readily explained by an increase in CE transfer from HDL to TG-rich lipoproteins, which is not due to increased cholesteryl ester transfer protein (CETP) plasma levels, but rather reflects an increase in fasting and postprandial TG. In conclusion, the net effect of accelerated CE transfer due to HRT depends on the balance of proatherogenic aspects, like the generation of small dense LDL, and antiatherogenic aspects, like the stimulation of reverse cholesterol transport.

  7. Simultaneous measurements of HF-enhanced plasma waves and artificial field-aligned irregularities at Arecibo

    SciTech Connect

    Noble, S.T. ); Djuth, F.T. )

    1990-09-01

    Two radar systems with beams intersecting in the HF-modified F region were used to simultaneously measure HF-enhanced plasma lines (HFPLs) and artificial geomagnetic field-aligned irregularities (AFAIs). The Arecibo 430-MHz radar was used for the HFPL observations, and a portable 49.92-MHz backscatter radar was deployed on the island of Guadeloupe to monitor the AFAIs. The experiment was desgined to examine the degree to which HF-induced plasma turbulence influences the development of AFAIs. When the HF beam is stepped up in power, sustained HFPLs and AFAIs are first observed at the same HF power level, indicating that ponderomotively driven instabilities may be involved in the early time development of AFAIs. As the HF power is increased, the HFPL backscatter power begins to saturate at {approximately}70 MW effective radiated power (ERP). However, the backscatter from AFAIs is linearly dependent on HF power, even at the highest (120 MW ERP) HF power levels available at Arecibo. This suggests that additional processes may contribute to the development of AFAIs. For example, ponderomotively driven instabilities may give rise to weak geomagnetic field-aligned irregularities that are subsequently driven unstable by processes excited near the upper hybrid resonance. It is also likely that AFAIs greatly impact the development of HF-induced plasma turbulence at late times (>1 s) following HF turn-on. Once the ionosphere is preconditioned by high-power HF modifications, AFAIs and HFPLs can be simultaneously sustained at a much lower HF power level than that needed to originally excite them. The nature of the preconditioning process is currently not well understood. New theoretical initiatives are clearly needed to guide future experimental activity in this area.

  8. Al{sub 2}O{sub 3} multi-density layer structure as a moisture permeation barrier deposited by radio frequency remote plasma atomic layer deposition

    SciTech Connect

    Jung, Hyunsoo; Jeon, Heeyoung; Choi, Hagyoung; Ham, Giyul; Shin, Seokyoon; Jeon, Hyeongtag

    2014-02-21

    Al{sub 2}O{sub 3} films deposited by remote plasma atomic layer deposition have been used for thin film encapsulation of organic light emitting diode. In this study, a multi-density layer structure consisting of two Al{sub 2}O{sub 3} layers with different densities are deposited with different deposition conditions of O{sub 2} plasma reactant time. This structure improves moisture permeation barrier characteristics, as confirmed by a water vapor transmission rate (WVTR) test. The lowest WVTR of the multi-density layer structure was 4.7 × 10{sup −5} gm{sup −2} day{sup −1}, which is one order of magnitude less than WVTR for the reference single-density Al{sub 2}O{sub 3} layer. This improvement is attributed to the location mismatch of paths for atmospheric gases, such as O{sub 2} and H{sub 2}O, in the film due to different densities in the layers. This mechanism is analyzed by high resolution transmission electron microscopy, elastic recoil detection, and angle resolved X-ray photoelectron spectroscopy. These results confirmed that the multi-density layer structure exhibits very good characteristics as an encapsulation layer via location mismatch of paths for H{sub 2}O and O{sub 2} between the two layers.

  9. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography

    NASA Astrophysics Data System (ADS)

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-01

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga+ ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90–210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  10. Robust Ultralow-k Dielectric (Fluorocarbon) Deposition by Microwave Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yoshiyuki; Miyatani, Kotaro; Kobayashi, Yasuo; Kawamura, Kohei; Nemoto, Takenao; Nakamura, Masahiro; Matsumoto, Hirokazu; Ito, Azumi; Shirotori, Akihide; Nozawa, Toshihisa; Matsuoka, Takaaki

    2012-05-01

    A robust fluorocarbon film was successfully deposited on a substrate at a temperature above 400 °C by the new microwave plasma-enhanced chemical vapor deposition (MWPE-CVD) method using the linear C5F8 precursor instead of a conventional cyclic C5F8 one. The fluorocarbon performed keeping the dielectric constant low as a value of 2.25 by controlling the molecular structure forming cross-linked poly(tetrafluoroethylene) (PTFE) chains with configurational carbon atoms. The novel fluorocarbon demonstrates less fluorine degassing at an elevated temperature, with high mechanical strength and without degradation of adhesion of the fluorocarbon film to SiCN and SiOx stacked films after thermal stress at 400 °C and 1 atm N2 for 1 h. Consequently, this robust fluorocarbon film is considered a promising candidate for general porous silicon materials with applications to practical integration processes as an interlayer dielectric.

  11. Low temperature plasma-enhanced ALD enables cost-effective spacer defined double patterning (SDDP)

    NASA Astrophysics Data System (ADS)

    Beynet, Julien; Wong, Patrick; Miller, Andy; Locorotondo, Sabrina; Vangoidsenhoven, Diziana; Yoon, Tae-Ho; Demand, Marc; Park, Hyung-Sang; Vandeweyer, Tom; Sprey, Hessel; Yoo, Yong-Min; Maenhoudt, Mireille

    2009-12-01

    The inherent advantages of the Plasma-Enhanced Atomic Layer Deposition (PEALD) technology--excellent conformality and within wafer uniformity, no loading effect--overcome the limitations in this domain of the standard PECVD technique for spacer deposition. The low temperature process capability of PEALD silicon oxide enables direct spacer deposition on photoresist, thus suppressing the need of a patterned template hardmask to design the spacers. By decreasing the number of deposition and patterning steps, this so-called Direct Spacer Defined Double Patterning (DSDDP) integration reduces cost and complexity of the conventional SDDP approach. A successful integration is reported for 32 nm half-pitch polysilicon lines. The performances are promising, especially from the lines, which result from the PEALD spacers: Critical Dimension Uniformity (CDU) of 1.3 nm and Line Width Roughness (LWR) of 2.0 nm.

  12. Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

    SciTech Connect

    Li Jiangling; Su Shi; Kundrat, Vojtech; Abbot, Andrew M.; Ye, Haitao; Zhou Lei; Mushtaq, Fajer; Ouyang Defang; James, David; Roberts, Darren

    2013-01-14

    We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.

  13. Enhancement of the fibrinolytic activity in plasma by oral administration of nattokinase.

    PubMed

    Sumi, H; Hamada, H; Nakanishi, K; Hiratani, H

    1990-01-01

    The existence of a potent fibrinolytic enzyme (nattokinase, NK) in the traditional fermented food called 'natto', was reported by us previously. It was confirmed that oral administration of NK (or natto) produced a mild and frequent enhancement of the fibrinolytic activity in the plasma, as indicated by the fibrinolytic parameters, and the production of tissue plasminogen activator. NK capsules were also administered orally to dogs with experimentally induced thrombosis, and lysis of the thrombi was observed by angiography. The results obtained suggest that NK represents a possible drug for use not only in the treatment of embolism but also in the prevention of the disease, since NK has a proven safety and can be massproduced.

  14. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography.

    PubMed

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-24

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga(+) ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90-210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  15. Large Enhancement in High-Energy Photoionization of Fe XVII and Missing Continuum Plasma Opacity.

    PubMed

    Nahar, Sultana N; Pradhan, Anil K

    2016-06-10

    Aimed at solving the outstanding problem of solar opacity, and radiation transport plasma models in general, we report substantial photoabsorption in the high-energy regime due to atomic core photoexcitations not heretofore considered. In extensive R-matrix calculations of unprecedented complexity for an important iron ion Fe xvii (Fe^{16+}), with a wave function expansion of 99 Fe xviii (Fe^{17+}) LS core states from n≤4 complexes (equivalent to 218 fine structure levels), we find (i) up to orders of magnitude enhancement in background photoionization cross sections, in addition to strongly peaked photo-excitation-of-core resonances not considered in current opacity models, and ii) demonstrate convergence with respect to successive core excitations. The resulting increase in the monochromatic continuum, and 35% in the Rosseland mean opacity, are compared with the "higher-than-predicted" iron opacity measured at the Sandia Z-pinch fusion device at solar interior conditions.

  16. Large Enhancement in High-Energy Photoionization of Fe XVII and Missing Continuum Plasma Opacity

    NASA Astrophysics Data System (ADS)

    Nahar, Sultana N.; Pradhan, Anil K.

    2016-06-01

    Aimed at solving the outstanding problem of solar opacity, and radiation transport plasma models in general, we report substantial photoabsorption in the high-energy regime due to atomic core photoexcitations not heretofore considered. In extensive R -matrix calculations of unprecedented complexity for an important iron ion Fe xvii (Fe16 + ), with a wave function expansion of 99 Fe xviii (Fe17 + ) LS core states from n ≤4 complexes (equivalent to 218 fine structure levels), we find (i) up to orders of magnitude enhancement in background photoionization cross sections, in addition to strongly peaked photo-excitation-of-core resonances not considered in current opacity models, and ii) demonstrate convergence with respect to successive core excitations. The resulting increase in the monochromatic continuum, and 35% in the Rosseland mean opacity, are compared with the "higher-than-predicted" iron opacity measured at the Sandia Z -pinch fusion device at solar interior conditions.

  17. Plasma-Enhanced Pulsed Laser Deposition of Wide Bandgap Nitrides for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Triplett, G. E., Jr.; Durbin, S. M.

    2004-01-01

    The need for a reliable, inexpensive technology for small-scale space power applications where photovoltaic or chemical battery approaches are not feasible has prompted renewed interest in radioisotope-based energy conversion devices. Although a number of devices have been developed using a variety of semiconductors, the single most limiting factor remains the overall lifetime of the radioisotope battery. Recent advances in growth techniques for ultra-wide bandgap III-nitride semiconductors provide the means to explore a new group of materials with the promise of significant radiation resistance. Additional benefits resulting from the use of ultra-wide bandgap materials include a reduction in leakage current and higher operating voltage without a loss of energy transfer efficiency. This paper describes the development of a novel plasma-enhanced pulsed laser deposition system for the growth of cubic boron nitride semiconducting thin films, which will be used to construct pn junction devices for alphavoltaic applications.

  18. 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.

  19. Enhancement of X-ray Production in Z-Pinch Plasmas Using Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Edison, N. S.; Etlicher, B.; Attelan, S.; Rouillé, C.; Chuvatin, A. S.; Aliaga, R.

    1994-03-01

    We are investigating the effects of an axial magnetic field to stabilize an aluminum vapor z-pinch. An aluminum plasma jet is created from an exploding foil in a DC magnetic field (Bz0 ≤ 300 G). The applied field is small compared to the azimuthal field, Bz0 ≫ Bϑ, and is intended to reduce the growth of instabilities during the compression phase. The pinch is driven by a 2 Ω, 0.1 TW generator (250 kA in 80 ns). Additionally, a micron sized wire may be placed on the pinch axis leading to the plasma-on-wire (POW) configuration. Qualitatively, increasing the axial magnetic field improves the pinch with the m=1 instabilities becoming negligible for fields higher than 150 G. We find that the externally applied fields can enhance x-ray production up to a critical field. Above this critical field x-ray emission decreases even though the pulse length of the radiation may still be increasing. As the applied field increases, the period of x-ray emission increases with the harder spectrum affected the least. The x-ray yield peaks for the POW and Al jet alone configurations at 150 G and 50 G respectively. Diagnostics include filtered PIN x-ray diodes, time-resolved schlieren photography, and time-integrated multiple filtered pinholes. We will present the results comparing the POW and aluminum jet configurations described above.

  20. Enhanced osteoblast responses to poly ether ether ketone surface modified by water plasma immersion ion implantation.

    PubMed

    Wang, Heying; Lu, Tao; Meng, Fanhao; Zhu, Hongqin; Liu, Xuanyong

    2014-05-01

    Poly ether ether ketone (PEEK) offers a set of characteristics superior for human implants; however, its application is limited by the bio-inert surface property. In this work, PEEK surface was modified using single step plasma immersion ion implantation (PIII) treatment with a gas mixture of water vapor as a plasma resource and argon as an ionization assistant. Field emission scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy were used to investigate the microstructure and composition of the modified PEEK surface. The water contact angle and zeta-potential of the surfaces were also measured. Osteoblast precursor cells MC3T3-E1 and rat bone mesenchymal stem cells were cultured on the PEEK samples to evaluate their cytocompatibility. The obtained results show that the hydroxyl groups as well as a "ravined structure" are constructed on water PIII modified PEEK. Compared with pristine PEEK, the water PIII treated PEEK is more favorable for osteoblast adhesion, spreading and proliferation, besides, early osteogenic differentiation indicated by the alkaline phosphatase activity is also up-regulated. Our study illustrates enhanced osteoblast responses to the PEEK surface modified by water PIII, which gives positive information in terms of future biomedical applications.

  1. Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride Using a Novel Silylamine Precursor.

    PubMed

    Park, Jae-Min; Jang, Se Jin; Yusup, Luchana L; Lee, Won-Jun; Lee, Sang-Ick

    2016-08-17

    We report the plasma-enhanced atomic layer deposition (PEALD) of silicon nitride thin film using a silylamine compound as the silicon precursor. A series of silylamine compounds were designed by replacing SiH3 groups in trisilylamine by dimethylaminomethylsilyl or trimethylsilyl groups to obtain sufficient thermal stability. The silylamine compounds were synthesized through redistribution, amino-substitution, lithiation, and silylation reactions. Among them, bis(dimethylaminomethylsilyl)trimethylsilyl amine (C9H29N3Si3, DTDN2-H2) was selected as the silicon precursor because of the lowest bond dissociation energy and sufficient vapor pressures. The energies for adsorption and reaction of DTDN2-H2 with the silicon nitride surface were also calculated by density functional theory. PEALD silicon nitride thin films were prepared using DTDN2-H2 and N2 plasma. The PEALD process window was between 250 and 400 °C with a growth rate of 0.36 Å/cycle. The best film quality was obtained at 400 °C with a RF power of 100 W. The PEALD film prepared showed good bottom and sidewall coverages of ∼80% and ∼73%, respectively, on a trench-patterned wafer with an aspect ratio of 5.5.

  2. Influence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon

    PubMed Central

    Chen, Wanghua; Cariou, Romain; Hamon, Gwenaëlle; Léal, Ronan; Maurice, Jean-Luc; Cabarrocas, Pere Roca i

    2017-01-01

    Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C. PMID:28262840

  3. Vitamin C Pretreatment Enhances the Antibacterial Effect of Cold Atmospheric Plasma.

    PubMed

    Helgadóttir, Saga; Pandit, Santosh; Mokkapati, Venkata R S S; Westerlund, Fredrik; Apell, Peter; Mijakovic, Ivan

    2017-01-01

    Bacterial biofilms are three-dimensional structures containing bacterial cells enveloped in a protective polymeric matrix, which renders them highly resistant to antibiotics and the human immune system. Therefore, the capacity to make biofilms is considered as a major virulence factor for pathogenic bacteria. Cold Atmospheric Plasma (CAP) is known to be quite efficient in eradicating planktonic bacteria, but its effectiveness against biofilms has not been thoroughly investigated. The goal of this study was to evaluate the effect of exposure of CAP against mature biofilm for different time intervals and to evaluate the effect of combined treatment with vitamin C. We demonstrate that CAP is not very effective against 48 h mature bacterial biofilms of several common opportunistic pathogens: Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. However, if bacterial biofilms are pre-treated with vitamin C for 15 min before exposure to CAP, a significantly stronger bactericidal effect can be obtained. Vitamin C pretreatment enhances the bactericidal effect of cold plasma by reducing the viability from 10 to 2% in E. coli biofilm, 50 to 11% in P. aeruginosa, and 61 to 18% in S. epidermidis biofilm. Since it is not feasible to use extended CAP treatments in medical practice, we argue that the pre-treatment of infectious lesions with vitamin C prior to CAP exposure can be a viable route for efficient eradication of bacterial biofilms in many different applications.

  4. Vitamin C Pretreatment Enhances the Antibacterial Effect of Cold Atmospheric Plasma

    PubMed Central

    Helgadóttir, Saga; Pandit, Santosh; Mokkapati, Venkata R. S. S.; Westerlund, Fredrik; Apell, Peter; Mijakovic, Ivan

    2017-01-01

    Bacterial biofilms are three-dimensional structures containing bacterial cells enveloped in a protective polymeric matrix, which renders them highly resistant to antibiotics and the human immune system. Therefore, the capacity to make biofilms is considered as a major virulence factor for pathogenic bacteria. Cold Atmospheric Plasma (CAP) is known to be quite efficient in eradicating planktonic bacteria, but its effectiveness against biofilms has not been thoroughly investigated. The goal of this study was to evaluate the effect of exposure of CAP against mature biofilm for different time intervals and to evaluate the effect of combined treatment with vitamin C. We demonstrate that CAP is not very effective against 48 h mature bacterial biofilms of several common opportunistic pathogens: Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. However, if bacterial biofilms are pre-treated with vitamin C for 15 min before exposure to CAP, a significantly stronger bactericidal effect can be obtained. Vitamin C pretreatment enhances the bactericidal effect of cold plasma by reducing the viability from 10 to 2% in E. coli biofilm, 50 to 11% in P. aeruginosa, and 61 to 18% in S. epidermidis biofilm. Since it is not feasible to use extended CAP treatments in medical practice, we argue that the pre-treatment of infectious lesions with vitamin C prior to CAP exposure can be a viable route for efficient eradication of bacterial biofilms in many different applications. PMID:28275584

  5. Plasma-enhanced atomic layer deposition for plasmonic TiN

    NASA Astrophysics Data System (ADS)

    Otto, Lauren M.; Hammack, Aaron T.; Aloni, Shaul; Ogletree, D. Frank; Olynick, Deirdre L.; Dhuey, Scott; Stadler, Bethanie J. H.; Schwartzberg, Adam M.

    2016-09-01

    This work presents the low temperature plasma-enhanced atomic layer deposition (PE-ALD) of TiN, a promising plasmonic synthetic metal. The plasmonics community has immediate needs for alternatives to traditional plasmonic materials (e.g. Ag and Au), which lack chemical, thermal, and mechanical stability. Plasmonic alloys and synthetic metals have significantly improved stability, but their growth can require high-temperatures (>400 °C), and it is difficult to control the thickness and directionality of the resulting film, especially on technologically important substrates. Such issues prevent the application of alternative plasmonic materials for both fundamental studies and large-scale industrial applications. Alternatively, PE-ALD allows for conformal deposition on a variety of substrates with consistent material properties. This conformal coating will allow the creation of exotic three-dimensional structures, and low-temperature deposition techniques will provide unrestricted usage across a variety of platforms. The characterization of this new plasmonic material was performed with in-situ spectroscopic ellipsometry as well as Auger electron spectroscopy for analysis of TiN film sensitivity to oxide cross-contamination. Plasmonic TiN films were fabricated, and a chlorine plasma etch was found to pattern two dimensional gratings as a test structure. Optical measurements of 900 nm period gratings showed reasonable agreement with theoretical modeling of the fabricated structures, indicating that ellipsometry models of the TiN were indeed accurate.

  6. Facile plasma-enhanced deposition of ultrathin crosslinked amino acid films for conformal biometallization.

    PubMed

    Anderson, Kyle D; Slocik, Joseph M; McConney, Michael E; Enlow, Jesse O; Jakubiak, Rachel; Bunning, Timothy J; Naik, Rajesh R; Tsukruk, Vladimir V

    2009-03-01

    A novel method for the facile fabrication of conformal, ultrathin, and uniform synthetic amino acid coatings on a variety of practical surfaces by plasma-enhanced chemical vapor deposition is introduced. Tyrosine, which is utilized as an agent to reduce gold nanoparticles from solution, is sublimed into the plasma field and directly deposited on a variety of substrates to form a homogeneous, conformal, and robust polyamino acid coating in a one-step, solvent-free process. This approach is applicable to many practical surfaces and allows surface-induced biometallization while avoiding multiple wet-chemistry treatments that can damage many soft materials. Moreover, by placing a mask over the substrate during deposition, the tyrosine coating can be micropatterned. Upon its exposure to a solution of gold chloride, a network of gold nanoparticles forms on the surface, replicating the initial micropattern. This method of templated biometallization is adaptable to a variety of practical inorganic and organic substrates, such as silicon, glass, nitrocellulose, polystyrene, polydimethylsiloxane, polytetrafluoroethylene, polyethylene, and woven silk fibers. No special pretreatment is necessary, and the technique results in a rapid, conformal amino acid coating that can be utilized for further biometallization.

  7. Growth of ultrananocrystalline diamond film by DC Arcjet plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, G. C.; Li, B.; Yan, Z. Q.; Liu, J.; Lu, F. X.; Ye, H.

    2012-06-01

    Self-standing diamond films were grown by DC Arcjet plasma enhanced chemical vapor deposition (CVD). The feed gasses were Ar/H2/CH4, in which the flow ratio of CH4 to H2 (F/F) was varied from 5% to 20%. Two distinct morphologies were observed by scanning electron microscope (SEM), i.e. the "pineapple-like" morphology and the "cauliflower-like" morphology. It was found that the morphologies of the as-grown films are strongly dependent on the flow ratio of CH4 to H2 in the feed gasses. High resolution transmission electron microscope (HRTEM) survey results revealed that there were nanocrystalline grains within the "pineapple-like" films whilst there were ultrananocrystalline grains within "cauliflower-like" films. X-ray diffraction (XRD) results suggested that (110) crystalline plane was the dominant surface in the "cauliflower-like" films whilst (100) crystalline plane was the dominant surface in the "pineapple-like" films. Raman spectroscopy revealed that nanostructured carbon features could be observed in both types of films. Plasma diagnosis was carried out in order to understand the morphology dependent growth mechanism. It could be concluded that the film morphology was strongly influenced by the density of gas phases. The gradient of C2 radical was found to be different along the growth direction under the different growth conditions.

  8. Passivation of aluminum nanoparticles by plasma-enhanced chemical vapor deposition for energetic nanomaterials.

    PubMed

    Shahravan, Anaram; Desai, Tapan; Matsoukas, Themis

    2014-05-28

    We have produced passivating coatings on 80-nm aluminum particles by plasma-enhanced chemical vapor deposition (PECVD). Three organic precursors--isopropyl alcohol, toluene, and perfluorodecalin--were used to fabricate thin films with thicknesses ranging from 5 nm to 30 nm. The coated samples and one untreated sample were exposed to 85% humidity at 25 °C for two months, and the active Al content was determined by thermogravimetric analysis (TGA) in the presence of oxygen. The results were compared with an uncoated sample stored in a glovebox under argon for the same period. We find that all three coatings provide protection against humidity, compared to the control, and their efficacy ranks in the following order: isopropyl alcohol < toluene < perfluorodecalin. This order also correlates with increasing water contact angle of the three solid coatings. The amount of heat released in the oxidation, measured by differential scanning calorimetry (DSC), was found to increase in the same order. Perfluorodecalin resulted in providing the best protection, and it produced the maximum enthalpy of combustion, ΔH = 4.65 kJ/g. This value is higher than that of uncoated aluminum stored in the glovebox, indicating that the coatings promote more complete oxidation of the core. Overall, we conclude that the plasma polymer coatings of this study are suitable passivating thin film for aluminum nanoparticles by providing protection against oxidation while facilitating the complete oxidation of the metallic core at elevated temperature.

  9. Functional beverage of Garcinia mangostana (mangosteen) enhances plasma antioxidant capacity in healthy adults

    PubMed Central

    Xie, Zhuohong; Sintara, Marsha; Chang, Tony; Ou, Boxin

    2015-01-01

    This study was to investigate the absorption and antioxidant effect of a mangosteen-based functional beverage in humans. The beverage contained mangosteen, aloe vera, green tea, and multivitamins. A randomized, double-blind, placebo-controlled clinical trial was conducted with generally healthy male and female subjects between 18 and 60 years of age. Ten men and 10 women participated in this study. Participants were randomly divided into two groups, treatment and placebo group. Participants received either a daily single dose (245 mL) of the beverage or a placebo. Blood samples were collected from each participant at time points 0, 1, 2, 4, and 6 h. The plasma samples were analyzed by LC/MS for α-mangostin and vitamins B2 and B5. Results indicated that the three analytes were bioavailable, with observed Cmax at around 1 h. The antioxidant capacity measured with the oxygen radical absorbance capacity (ORAC) assay was increased with a maximum effect of 60% after 1 h, and the elevated antioxidant level lasted at least 6 h. This study demonstrated the bioavailability of α-mangostin and B vitamins from a xanthone-rich beverage and the mechanisms of the increase in plasma antioxidant may be direct effects from antioxidants, enhancement of endogenous antioxidant activity through activation of Nrf2 pathway, and synergism of the antioxidants. PMID:25649891

  10. Conformal encapsulation of three-dimensional, bioresorbable polymeric scaffolds using plasma-enhanced chemical vapor deposition.

    PubMed

    Hawker, Morgan J; Pegalajar-Jurado, Adoracion; Fisher, Ellen R

    2014-10-21

    Bioresorbable polymers such as poly(ε-caprolactone) (PCL) have a multitude of potential biomaterial applications such as controlled-release drug delivery and regenerative tissue engineering. For such biological applications, the fabrication of porous three-dimensional bioresorbable materials with tunable surface chemistry is critical to maximize their surface-to-volume ratio, mimic the extracellular matrix, and increase drug-loading capacity. Here, two different fluorocarbon (FC) precursors (octofluoropropane (C3F8) and hexafluoropropylene oxide (HFPO)) were used to deposit FC films on PCL scaffolds using plasma-enhanced chemical vapor deposition (PECVD). These two coating systems were chosen with the intent of modifying the scaffold surfaces to be bio-nonreactive while maintaining desirable bulk properties of the scaffold. X-ray photoelectron spectroscopy showed high-CF2 content films were deposited on both the exterior and interior of PCL scaffolds and that deposition behavior is PECVD system specific. Scanning electron microscopy data confirmed that FC film deposition yielded conformal rather than blanket coatings as the porous scaffold structure was maintained after plasma treatment. Treated scaffolds seeded with human dermal fibroblasts (HDF) demonstrate that the cells do not attach after 72 h and that the scaffolds are noncytotoxic to HDF. This work demonstrates conformal FC coatings can be deposited on 3D polymeric scaffolds using PECVD to fabricate 3D bio-nonreactive materials.

  11. Influence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon

    NASA Astrophysics Data System (ADS)

    Chen, Wanghua; Cariou, Romain; Hamon, Gwenaëlle; Léal, Ronan; Maurice, Jean-Luc; Cabarrocas, Pere Roca I.

    2017-03-01

    Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C.

  12. Enhancement of the maximum proton energy by funnel-geometry target in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Yang, Peng; Fan, Dapeng; Li, Yuxiao

    2016-09-01

    Enhancement of the maximum proton energy using a funnel-geometry target is demonstrated through particle simulations of laser-plasma interactions. When an intense short-pulse laser illuminate a thin foil target, the foil electrons are pushed by the laser ponderomotive force, and then form an electron cloud at the target rear surface. The electron cloud generates a strong electrostatic field, which accelerates the protons to high energies. If there is a hole in the rear of target, the shape of the electron cloud and the distribution of the protons will be affected by the protuberant part of the hole. In this paper, a funnel-geometry target is proposed to improve the maximum proton energy. Using particle-in-cell 2-dimensional simulations, the transverse electric field generated by the side wall of four different holes are calculated, and protons inside holes are restricted to specific shapes by these field. In the funnel-geometry target, more protons are restricted near the center of the longitudinal accelerating electric field, thus protons experiencing longer accelerating time and distance in the sheath field compared with that in a traditional cylinder hole target. Accordingly, more and higher energy protons are produced from the funnel-geometry target. The maximum proton energy is improved by about 4 MeV compared with a traditional cylinder-shaped hole target. The funnel-geometry target serves as a new method to improve the maximum proton energy in laser-plasma interactions.

  13. A mathematical model and simulation results of plasma enhanced chemical vapor deposition of silicon nitride films

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2015-01-01

    We developed a mathematical model of Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon nitride thin films from SiH4-NH3-N2-Ar mixture, an important application in modern materials science. Our multiphysics model describes gas dynamics, chemical physics, plasma physics and electrodynamics. The PECVD technology is inherently multiscale, from macroscale processes in the chemical reactor to atomic-scale surface chemistry. Our macroscale model is based on Navier-Stokes equations for a transient laminar flow of a compressible chemically reacting gas mixture, together with the mass transfer and energy balance equations, Poisson equation for electric potential, electrons and ions balance equations. The chemical kinetics model includes 24 species and 58 reactions: 37 in the gas phase and 21 on the surface. A deposition model consists of three stages: adsorption to the surface, diffusion along the surface and embedding of products into the substrate. A new model has been validated on experimental results obtained with the "Plasmalab System 100" reactor. We present the mathematical model and simulation results investigating the influence of flow rate and source gas proportion on silicon nitride film growth rate and chemical composition.

  14. The effect of oxygen flow rate and radio frequency plasma power on cubic ZnMgO ultraviolet sensors grown by plasma-enhanced molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Casey Boutwell, R.; Wei, Ming; Schoenfeld, Winston V.

    2013-07-01

    Cubic Zn1-xMgxO thin films were produced by Plasma-Enhanced Molecular Beam Epitaxy. Oxygen flow rate and applied Radio-Frequency (RF) plasma power were varied to investigate the impact on film growth and optoelectronic device performance. Solar-blind and visible-blind detectors were fabricated with metal-semiconductor-metal interdigitated Ni/Mg/Au contacts and responsivity is compared under different growth conditions. Increasing oxygen flow rate and RF plasma power increased Zn incorporation in the film, which leads to phase segregation at relatively high Zn/Mg ratio. Responsivity as high as 61 A/W was measured in phase-segregated ZnMgO visible-blind detectors.

  15. Plasma-enhanced atomic layer deposition and etching of high-k gadolinium oxide

    SciTech Connect

    Vitale, Steven A.; Wyatt, Peter W.; Hodson, Chris J.

    2012-01-15

    Atomic layer deposition (ALD) of high-quality gadolinium oxide thin films is achieved using Gd(iPrCp){sub 3} and O{sub 2} plasma. Gd{sub 2}O{sub 3} growth is observed from 150 to 350 deg. C, though the optical properties of the film improve at higher temperature. True layer-by-layer ALD growth of Gd{sub 2}O{sub 3} occurred in a relatively narrow window of temperature and precursor dose. A saturated growth rate of 1.4 A/cycle was observed at 250 deg. C. As the temperature increases, high-quality films are deposited, but the growth mechanism appears to become CVD-like, indicating the onset of precursor decomposition. At 250 deg. C, the refractive index of the film is stable at {approx}1.80 regardless of other deposition conditions, and the measured dispersion characteristics are comparable to those of bulk Gd{sub 2}O{sub 3}. XPS data show that the O/Gd ratio is oxygen deficient at 1.3, and that it is also very hygroscopic. The plasma etching rate of the ALD Gd{sub 2}O{sub 3} film in a high-density helicon reactor is very low. Little difference is observed in etching rate between Cl{sub 2} and pure Ar plasmas, suggesting that physical sputtering dominates the etching. A threshold bias power exists below which etching does not occur; thus it may be possible to etch a metal gate material and stop easily on the Gd{sub 2}O{sub 3} gate dielectric. The Gd{sub 2}O{sub 3} film has a dielectric constant of about 16, exhibits low C-V hysteresis, and allows a 50 x reduction in gate leakage compared to SiO{sub 2}. However, the plasma enhanced atomic layer deposition (PE-ALD) process causes formation of an {approx}1.8 nm SiO{sub 2} interfacial layer, and generates a fixed charge of -1.21 x 10{sup 12} cm{sup -2}, both of which may limit use of PE-ALD Gd{sub 2}O{sub 3} as a gate dielectric.

  16. Moisture barrier and chemical corrosion protection of silver-based telescope mirrors using aluminum oxide films by plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Fryauf, David M.; Phillips, Andrew C.; Kobayashi, Nobuhiko P.

    2013-09-01

    An urgent demand remains in astronomy for high-reflectivity silver mirrors that can withstand years of exposure in observatory environments. The University of California Observatories Astronomical Coatings Lab has undertaken development of protected silver coatings suitable for telescope mirrors that maintain high reflectivity at wavelengths from 340 nm through the mid-infrared spectrum. We present initial results of an investigation into whether plasma-enhanced atomic layer deposition (PEALD) can produce superior protective layers of transparent dielectrics. Several novel coating recipes have been developed with ion-assisted electron beam deposition (IAEBD) of materials including yttrium fluoride, and oxides of yttrium, hafnium, and titanium. Samples of these mirror coatings were covered with conformal layers of aluminum oxide (AlOx) deposited by PEALD using trimethylaluminum as a metal precursor and oxygen as an oxidant gas activated by remote plasma. Samples of coating recipes with and without PEALD oxide undergo aggressive environmental testing, including high temperature/high humidity (HTHH), in which samples were exposed to an environment of 80% humidity at 80°C for ten days in a simple test set-up. HTHH testing show visible results suggesting that the PEALD oxide offers enhanced robust protection against chemical corrosion and moisture from an accelerated aging environment. Mirror samples are further characterized by reflectivity/absorption and atomic force microscopy before and after deposition of oxide coatings. AlOx is suitable for many applications and has been the initial material choice for this study, although we also tried TiOx and HfOx. Further experimentation based on these initial results is on-going.

  17. Evidence and effects of the sunrise enhancement of the equatorial vertical plasma drift in the F region ionosphere

    NASA Astrophysics Data System (ADS)

    Zhang, Ruilong; Liu, Libo; Le, Huijun; Chen, Yiding

    2016-05-01

    Recent studies based on the satellite observations demonstrated that the equatorial vertical plasma drift can also enhance near sunrise in a way similar to the prereversal enhancement. However, it is not clear whether the signature of this sunrise enhancement appears in observations with other sounding techniques. In this work, we explore the Jicamarca (12°S, 283.2°E) incoherent scatter radar measurements to present the evidence of sunrise enhancement in vertical plasma drift on 12 May and 10 June 2004, which are under magnetically quiet and solar minimum conditions. The effects of the sunrise enhancement on the ionosphere are, for the first time, investigated by analyzing the ionograms recorded by the Digisonde Portable Sounder at Jicamarca and conducting the Theoretical Ionospheric Model of the Earth in Institute of Geology and Geophysics, Chinese Academy of Sciences. The observations showed that, during the sunrise enhancement, the F2 layer peak height is lifted remarkably, and the F2 layer peak density and bottomside electron density tend to decrease compared to the days without sunrise enhancements. The simulations indicated that the sunrise enhancement drift can lift the equatorial ionosphere to higher heights and distort the equatorial electron density profiles. What is more, the simulations display an F3 layer in the equatorial F region during the sunrise enhancement, and a new F2 layer develops at lower altitudes under the jointed control of the usual photochemical and dynamical processes.

  18. Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium

    PubMed Central

    Zhu, Wei; Teel, George; O’Brien, Christopher M; Zhuang, Taisen; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium’s osseointegration involves inducing bio-mimetic nanotopography to enhance cell–implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications. PMID:26677327

  19. Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium.

    PubMed

    Zhu, Wei; Teel, George; O'Brien, Christopher M; Zhuang, Taisen; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium's osseointegration involves inducing bio-mimetic nanotopography to enhance cell-implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications.

  20. Myristic acid-modified thymopentin for enhanced plasma stability and immune-modulating activity.

    PubMed

    Tan, Yuanyan; Wang, Wei; Wu, Chunlei; Pan, Zhengyin; Yao, Guiyang; Fang, Lijing; Su, Wu

    2017-03-30

    Natural albumin ligand (fatty acids)-conjugated peptides can rapidly bind to circulating albumin and form complexes to control the release of peptides. The purpose of this study was to prolong the half-life and immune-modulating effects of thymopentin (TP5) by using the albumin binding strategy. We synthesized myristic acid-modified TP5 (TP5-MA) by conjugating a myristic acid-acylated lysine to a permissive site of TP5, which improved the albumin binding affinity of TP5-MA and dramatically enhanced its stability in human plasma. We observed well-preserved bioactivities of TP5-MA in RAW264.7 macrophages using a tumor necrosis factor (TNF)-α stimulation assay. Moreover, the prolonged immune-modulating effect of TP5-MA was confirmed by the normalized CD4(+)/CD8(+) ratio in immune-depressed rat models, which resulted in a reduced administration frequency (twice per week). In general, the enhanced pharmacokinetic and pharmacodynamic properties of TP5-MA make it a promising product for the treatment of immunodeficiency diseases.

  1. The Role of Plasmas on Enhanced O2+ Loss at Mars

    NASA Astrophysics Data System (ADS)

    Ergun, Robert; Andersson, Laila; Woodson, Adam; Fowler, Chris; Weber, Tristan; Delory, Greg; Andrews, David; Eriksson, Anders; Mooroka, Mitchico; Stweart, Ian; Mahaffy, Paul; Jakosky, Bruce

    2016-04-01

    Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures in Mars' day side ionosphere above ~180 km in altitude. Correspondingly, measurements from Neutral Gas and Ion Mass Spectrometer indicate significant abundances of O2+ up to ~500 km in altitude, suggesting that O2+ may be a principal ion loss mechanism of oxygen. In this article, we investigate the effects of the higher electron temperature (which results from electron heating) and ion heating on ion outflow and loss. Numerical solutions show that plasma processes including ion heating and higher electron temperature may greatly increase O2+ loss at Mars. In particular, enhanced Te in Mars' ionosphere just above the exobase creates a substantial ambipolar electric field, which draws ions out of the region allowing for enhanced escape. With active solar wind, electron and ion heating, direct O2+ loss could match or exceed loss via dissociative recombination of O2+. These results suggest that direct loss of O2+ may have played a significant role in the loss of oxygen at Mars.

  2. Enhanced nonlinear interaction of powerful electromagnetic waves with ionospheric plasma near the second electron gyroharmonic

    SciTech Connect

    Istomin, Ya. N.; Leyser, T. B.

    2013-05-15

    Plasma experiments in which a powerful electromagnetic pump wave is transmitted into the ionosphere from the ground give access to a rich range of phenomena, including gyroharmonic effects when the pump frequency is near an harmonic of the ionospheric electron gyrofrequency. For pump frequencies close to the second gyroharmonic, experiments show a strong enhancement, as observed in radar scatter from pump-induced geomagnetic field-aligned density striations and optical emissions. This is in contrast to the case at the third harmonic and higher at which most of the effects are instead suppressed. We show theoretically that electrostatic oscillations can be localized in density inhomogeneities associated with small scale striations. The localized field is a mixture of the electron Bernstein and upper hybrid modes when the pump frequency is near the second gyroharmonic. The coupling of the modes is enabled by a symmetry feature of the linear electron Bernstein and upper hybrid dispersion properties that occur only near the second gyroharmonic. Electron acceleration inside the density inhomogeneities by localized azimuthal electrostatic oscillations is more efficient near the second gyroharmonic than at higher frequencies, consistent with the observed enhancements.

  3. Enhanced thermoelectric properties of bismuth sulfide polycrystals prepared by mechanical alloying and spark plasma sintering

    SciTech Connect

    Zhao Lidong; Zhang Boping Liu Weishu; Zhang Hailong; Li Jingfeng

    2008-12-15

    Bismuth sulfide powders were synthesized by mechanical alloying (MA) and then consolidated by spark plasma sintering (SPS) technique. In order to improve the electrical transport properties of bismuth sulfides, the carrier concentration was optimized by modifying chemical composition of sulfur through producing sulfur vacancies, and the carrier mobility was enhanced by a two-step SPS as a hot-forging process through increasing grain orientation. The electrical resistivity of bismuth sulfides was reduced to 10{sup -4} from 10{sup -2} {omega} m by optimizing sulfur content, and further lowered by hot-forging, whereby the power factor was significantly increased from 91 to 254 {mu}W/mK{sup 2}. The hot-forged Bi{sub 2}S{sub 2.90} sample showed the highest ZT=0.11 (at 523 K), which is higher than the reported value. The present work revealed that bismuth sulfide compounds as a promising candidate of thermoelectric materials can be synthesized by a simple process. - Abstract: Electrical properties of bismuth sulfides were improved by optimizing carrier concentration through modifying compositions of sulfur and enhancing carrier mobility through SPSed hot-forging. The ZT value of 0.11 was obtained, which is the maximum reported so far . Display Omitted.

  4. Moisture barrier properties of thin organic-inorganic multilayers prepared by plasma-enhanced ALD and CVD in one reactor

    NASA Astrophysics Data System (ADS)

    Bülow, Tim; Gargouri, Hassan; Siebert, Mirko; Rudolph, Rolf; Johannes, Hans-Hermann; Kowalsky, Wolfgang

    2014-05-01

    A widely used application of the atomic layer deposition (ALD) and chemical vapour deposition (CVD) methods is the preparation of permeation barrier layers against water vapour. Especially in the field of organic electronics, these films are highly demanded as such devices are very sensitive to moisture and oxygen. In this work, multilayers of aluminium oxide (AlO x ) and plasma polymer (PP) were coated on polyethylene naphthalate substrates by plasma-enhanced ALD and plasma-enhanced CVD at 80℃ in the same reactor, respectively. As precursor, trimethylaluminium was used together with oxygen radicals in order to prepare AlO x , and benzene served as precursor to deposit the PP. This hybrid structure allows the decoupling of defects between the single AlO x layers and extends the permeation path for water molecules towards the entire barrier film. Furthermore, the combination of two plasma techniques in a single reactor system enables short process times without vacuum breaks. Single aluminium oxide films by plasma-enhanced ALD were compared to thermally grown layers and showed a significantly better barrier performance. The water vapour transmission rate (WVTR) was determined by means of electrical calcium tests. For a multilayer with 3.5 dyads of 25-nm AlO x and 125-nm PP, a WVTR of 1.2 × 10 -3 g m -2 d -1 at 60℃ and 90% relative humidity could be observed.

  5. Effect of oxygen plasma on field emission characteristics of single-wall carbon nanotubes grown by plasma enhanced chemical vapour deposition system

    SciTech Connect

    Kumar, Avshish; Parveen, Shama; Husain, Samina; Ali, Javid; Zulfequar, Mohammad; Harsh; Husain, Mushahid

    2014-02-28

    Field emission properties of single wall carbon nanotubes (SWCNTs) grown on iron catalyst film by plasma enhanced chemical vapour deposition system were studied in diode configuration. The results were analysed in the framework of Fowler-Nordheim theory. The grown SWCNTs were found to be excellent field emitters, having emission current density higher than 20 mA/cm{sup 2} at a turn-on field of 1.3 V/μm. The as grown SWCNTs were further treated with Oxygen (O{sub 2}) plasma for 5 min and again field emission characteristics were measured. The O{sub 2} plasma treated SWCNTs have shown dramatic improvement in their field emission properties with emission current density of 111 mA/cm{sup 2} at a much lower turn on field of 0.8 V/μm. The as grown as well as plasma treated SWCNTs were also characterized by various techniques, such as scanning electron microscopy, high resolution transmission electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy before and after O{sub 2} plasma treatment and the findings are being reported in this paper.

  6. Polyethylene Oxide Films Polymerized by Radio Frequency Plasma-Enhanced Chemical Vapour Phase Deposition and Its Adsorption Behaviour of Platelet-Rich Plasma

    NASA Astrophysics Data System (ADS)

    Hu, Wen-Juan; Xie, Fen-Yan; Chen, Qiang; Weng, Jing

    2008-10-01

    We present polyethylene oxide (PEO) functional films polymerized by rf plasma-enhanced vapour chemical deposition (rf-PECVD) on p-Si (100) surface with precursor ethylene glycol dimethyl ether (EGDME) and diluted Ar in pulsed plasma mode. The influences of discharge parameters on the film properties and compounds are investigated. The film structure is analysed by Fourier transform infrared (FTIR) spectroscopy. The water contact angle measurement and atomic force microscope (AFM) are employed to examine the surface polarity and to detect surface morphology, respectively. It is concluded that the smaller duty cycle in pulsed plasma mode contributes to the rich C-O-C (EO) group on the surfaces. As an application, the adsorption behaviour of platelet-rich plasma on plasma polymerization films performed in-vitro is explored. The shapes of attached cells are studied in detail by an optic invert microscope, which clarifies that high-density C-O-C groups on surfaces are responsible for non-fouling adsorption behaviour of the PEO films.

  7. Equatorial broad plasma depletions associated with the evening prereversal enhancement and plasma bubbles during the 17 March 2015 storm

    NASA Astrophysics Data System (ADS)

    Kil, Hyosub; Lee, Woo Kyoung; Paxton, Larry J.; Hairston, Marc R.; Jee, Geonhwa

    2016-10-01

    Broad plasma depletions (BPDs) in the equatorial F region represent plasma depletions whose longitudinal and latitudinal scales are much greater than those of normal plasma bubbles. This study investigates the characteristics and origin of BPDs using the coincident ionospheric observations by the Communication/Navigation Outage Forecasting System, Defense Meteorological Satellite Program, and Swarm satellites during the 2015 St. Patrick's Day (17 March) storm. Two types of BPDs were detected before midnight during the main phase of the storm. One type of BPDs showed a gradual plasma density variation (Type 1), and the other type of BPDs showed a steep density gradient (Type 2) at the walls of BPDs. The Type 1 BPDs were detected with no signature of plasma bubbles nearby, whereas the Type 2 BPDs were accompanied by bubbles. The formation of the Type 1 BPDs is attributed to the uplift of the bottomside of the F region above the satellite altitude by the action of storm-induced electric fields. The steep walls of Type 2 BPDs are associated with the ionospheric uplift and the spatial discontinuity of the ionosphere produced by bubbles. The detection of BPDs that are more than 15° wide in latitude by the polar orbit Swarm satellites arises from the elongation of bubbles along the magnetic field lines and the alignment of the elongation with the plane of the orbit.

  8. Plasma enhancement of in vitro attachment of rat bone-marrow-derived stem cells on cross-linked gelatin films.

    PubMed

    Prasertsung, I; Kanokpanont, S; Mongkolnavin, R; Wong, C S; Panpranot, J; Damrongsakkul, S

    2012-01-01

    In this work, nitrogen, oxygen and air glow discharges powered by 50 Hz AC power supply are used for the treatment of type-A gelatin film cross-linked by a dehydrothermal (DHT) process. The properties of cross-linked gelatin were characterized by contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) analysis. The results showed that the water contact angle of gelatin films decrease with increasing plasma treatment time. The treatment of nitrogen, oxygen and air plasma up to 30 s had no effects on the surface roughness of the gelatin film as revealed by AFM results. The XPS analysis showed that the N-containing functional groups generated by nitrogen and air plasma, and O-containing functional groups generated by oxygen and air plasmas were incorporated onto the film surface, the functional groups were found to increase with increasing treatment time. An in vitro test using rat bone-marrow-mesenchym-derived stem cells (MSCs) revealed that the number of cells attached on plasma-treated gelatin films was significantly increased compared to untreated samples. The best enhancement of cell attachment was noticed when the film was treated with nitrogen plasma for 15-30 s, oxygen plasma for 3 s, and air plasma for 9 s. In addition, among the three types of plasmas used, nitrogen plasma treatment gave the best MSCs attachment on the gelatin surface. The results suggest that a type-A gelatin film with water contact angle of 27-28° and an O/N ratio of 1.4 is most suitable for MSCs attachment.

  9. Organo-Chlorinated Thin Films Deposited by Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition for Adhesion Enhancement between Rubber and Zinc-Plated Steel Monofilaments.

    PubMed

    Vandenabeele, Cédric; Bulou, Simon; Maurau, Rémy; Siffer, Frederic; Belmonte, Thierry; Choquet, Patrick

    2015-07-08

    A continuous-flow plasma process working at atmospheric pressure is developed to enhance the adhesion between a rubber compound and a zinc-plated steel monofilament, with the long-term objective to find a potential alternative to the electrolytic brass plating process, which is currently used in tire industry. For this purpose, a highly efficient tubular dielectric barrier discharge reactor is built to allow the continuous treatment of "endless" cylindrical substrates. The best treatment conditions found regarding adhesion are Ar/O2 plasma pretreatment, followed by the deposition from dichloromethane of a 75 nm-thick organo-chlorinated plasma polymerized thin film. Ar/O2 pretreatment allows the removal of organic residues, coming from drawing lubricants, and induces external growth of zinc oxide. The plasma layer has to be preferably deposited at low power to conserve sufficient hydrocarbon moieties. Surface analyses reveal the complex chemical mechanism behind the establishment of strong adhesion levels, more than five times higher after the plasma treatment. During the vulcanization step, superficial ZnO reacts with the chlorinated species of the thin film and is converted into porous and granular bump-shaped ZnwOxHyClz nanostructures. Together, rubber additives diffuse through the plasma layer and lead to the formation of zinc sulfide on the substrate surface. Hence, two distinct interfaces, rubber/thin film and thin film/substrate, are established. On the basis of these observations, hypotheses explaining the high bonding strength results are formulated.

  10. Label-free surface-enhanced Raman spectroscopy for detection of colorectal cancer and precursor lesions using blood plasma

    PubMed Central

    Feng, Shangyuan; Wang, Wenbo; Tai, Isabella T.; Chen, Guannan; Chen, Rong; Zeng, Haishan

    2015-01-01

    Fecal based tests have limited diagnostic values in detecting adenomatous polyps, the precursor lesions to colorectal cancer (CRC). Surface enhanced Raman spectroscopy (SERS) using silver nanoparticles as substrate is a multiplexed analytical technique capable of detecting biomolecules with high sensitivity. This study utilizes SERS to analyze blood plasma for detecting both CRC and adenomatous polyps for the first time. Blood plasma samples are collected from healthy control subjects and patients diagnosed with adenomas and CRC. Using a real-time Raman system, SERS spectra for blood plasma samples are measured in 1 s. The collected SERS spectra are analyzed with partial least squares-discriminant analysis. Classification of normal versus CRC plus adenomatous polyps achieved diagnostic sensitivity of 86.4% and specificity of 80%. The results suggest that blood plasma SERS analysis could be a potential screening test to detect both CRC and adenomas. PMID:26417518

  11. Detection of HO2 in an atmospheric pressure plasma jet using optical feedback cavity-enhanced absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Gianella, Michele; Reuter, Stephan; Lawry Aguila, Ana; Ritchie, Grant A. D.; van Helden, Jean-Pierre H.

    2016-11-01

    Cold non-equilibrium atmospheric pressure plasma jets are increasingly applied in material processing and plasma medicine. However, their small dimensions make diagnosing the fluxes of generated species a challenge. Here we report on the detection of the hydroperoxyl radical, HO2, in the effluent of a plasma jet by the use of optical feedback cavity-enhanced absorption spectroscopy. The spectrometer has a minimum detectable absorption coefficient {α }\\min of 2.25× {10}-10 cm-1 with a 100 second acquisition, equivalent to 5.5× {10}12 {{cm}}-3 of HO2 (under ideal conditions). Concentrations in the range of (3.1-7.8) × 1013 cm-3 were inferred in the 4 mm wide effluent of the plasma jet.

  12. Plasma enhanced chemical vapor deposition (PECVD) method of forming vanadium oxide films and vanadium oxide thin-films prepared thereby

    DOEpatents

    Zhang, Ji-Guang; Tracy, C. Edwin; Benson, David K.; Turner, John A.; Liu, Ping

    2000-01-01

    A method is disclosed of forming a vanadium oxide film on a substrate utilizing plasma enhanced chemical vapor deposition. The method includes positioning a substrate within a plasma reaction chamber and then forming a precursor gas comprised of a vanadium-containing chloride gas in an inert carrier gas. This precursor gas is then mixed with selected amounts of hydrogen and oxygen and directed into the reaction chamber. The amounts of precursor gas, oxygen and hydrogen are selected to optimize the final properties of the vanadium oxide film An rf plasma is generated within the reaction chamber to chemically react the precursor gas with the hydrogen and the oxygen to cause deposition of a vanadium oxide film on the substrate while the chamber deposition pressure is maintained at about one torr or less. Finally, the byproduct gases are removed from the plasma reaction chamber.

  13. Label-free surface-enhanced Raman spectroscopy for detection of colorectal cancer and precursor lesions using blood plasma.

    PubMed

    Feng, Shangyuan; Wang, Wenbo; Tai, Isabella T; Chen, Guannan; Chen, Rong; Zeng, Haishan

    2015-09-01

    Fecal based tests have limited diagnostic values in detecting adenomatous polyps, the precursor lesions to colorectal cancer (CRC). Surface enhanced Raman spectroscopy (SERS) using silver nanoparticles as substrate is a multiplexed analytical technique capable of detecting biomolecules with high sensitivity. This study utilizes SERS to analyze blood plasma for detecting both CRC and adenomatous polyps for the first time. Blood plasma samples are collected from healthy control subjects and patients diagnosed with adenomas and CRC. Using a real-time Raman system, SERS spectra for blood plasma samples are measured in 1 s. The collected SERS spectra are analyzed with partial least squares-discriminant analysis. Classification of normal versus CRC plus adenomatous polyps achieved diagnostic sensitivity of 86.4% and specificity of 80%. The results suggest that blood plasma SERS analysis could be a potential screening test to detect both CRC and adenomas.

  14. Development of a Ge/GaAs HMT (High Mobility Transistor) Technology Based on Plasma Enhanced Chemical Vapor Deposition

    DTIC Science & Technology

    1989-11-01

    R SEARCH TRIANGLE INSTITUTE RTI/3628/89-3QTR November 1089 0 00 DEVELOPMENT OF A Ge/GaAs [MT TECHNOLCGY JBASED ON PLASMA-ENHANCED CHEMICAL VAPOR DE...N00014- 86-C-0838 during:the period -from I July 1080 to 30 September 1089 . Funding is being provided by the Strateg’c Defense Initiative under the

  15. N-linked glycan truncation causes enhanced clearance of plasma-derived von Willebrand factor.

    PubMed

    O'Sullivan, J M; Aguila, S; McRae, E; Ward, S E; Rawley, O; Fallon, P G; Brophy, T M; Preston, R J S; Brady, L; Sheils, O; Chion, A; O'Donnell, J S

    2016-12-01

    Essentials von Willebrands factor (VWF) glycosylation plays a key role in modulating in vivo clearance. VWF glycoforms were used to examine the role of specific glycan moieties in regulating clearance. Reduction in sialylation resulted in enhanced VWF clearance through asialoglycoprotein receptor. Progressive VWF N-linked glycan trimming resulted in increased macrophage-mediated clearance. Click to hear Dr Denis discuss clearance of von Willebrand factor in a free presentation from the ISTH Academy SUMMARY: Background Enhanced von Willebrand factor (VWF) clearance is important in the etiology of both type 1 and type 2 von Willebrand disease (VWD). In addition, previous studies have demonstrated that VWF glycans play a key role in regulating in vivo clearance. However, the molecular mechanisms underlying VWF clearance remain poorly understood. Objective To define the molecular mechanisms through which VWF N-linked glycan structures influence in vivo clearance. Methods By use of a series of exoglycosidases, different plasma-derived VWF (pd-VWF) glycoforms were generated. In vivo clearance of these glycoforms was then assessed in VWF(-/-) mice in the presence or absence of inhibitors of asialoglycoprotein receptor (ASGPR), or following clodronate-induced macrophage depletion. Results Reduced amounts of N-linked and O-linked sialylation resulted in enhanced pd-VWF clearance modulated via ASGPR. In addition to this role of terminal sialylation, we further observed that progressive N-linked glycan trimming also resulted in markedly enhanced VWF clearance. Furthermore, these additional N-linked glycan effects on clearance were ASGPR-independent, and instead involved enhanced macrophage clearance that was mediated, at least in part, through LDL receptor-related protein 1. Conclusion The carbohydrate determinants expressed on VWF regulate susceptibility to proteolysis by ADAMTS-13. In addition, our findings now further demonstrate that non-sialic acid carbohydrate

  16. Gastric cancer detection based on blood plasma surface-enhanced Raman spectroscopy excited by polarized laser light.

    PubMed

    Feng, Shangyuan; Chen, Rong; Lin, Juqiang; Pan, Jianji; Wu, Yanan; Li, Yongzeng; Chen, Jiesi; Zeng, Haishan

    2011-03-15

    We have recently applied surface-enhanced Raman spectroscopy (SERS) for blood plasma analysis for non-invasive nasopharyngeal cancer detection and obtained good preliminary results. The aim of this study was to develop a more robust SERS spectroscopy based blood plasma analysis method for non-invasive gastric cancer detection. The effect of different laser polarizations (non-polarized, linear-polarized, right-handed circularly polarized, and left-handed circularly polarized) on blood plasma SERS spectroscopy was explored for the first time. Silver nanoparticles as the SERS-substrate were directly mixed with blood plasma to enhance the Raman scattering of various biomolecular constituents. High quality SERS spectra were obtained using a fiber optic probe and a dispersive type near infrared Raman system. Blood plasma samples from gastric cancer patients (n=32) and healthy subjects (n=33) were analyzed. The diagnostic performance for differentiating gastric cancer plasma from normal plasma was evaluated. Principal component analysis combined with linear discriminant analysis (LDA) of the obtained spectral data was used to develop diagnostic algorithms. Classification results obtained from cross-validation of the LDA model based on the four spectral data sets of different laser polarizations demonstrated different diagnostic sensitivities and specificities: 71.9% and 72.7% for non-polarized laser excitation, 75% and 87.9% for linear-polarized laser excitation, 81.3% and 78.8% for right-handed circularly polarized laser excitation, 100% and 97% for left-handed circularly polarized laser excitation. The results from this exploratory study demonstrated that plasma SERS spectroscopy with left-handed circularly polarized laser excitation has great promise of becoming a clinically useful diagnostic tool for non-invasive gastric cancer detection.

  17. A solid-state nuclear magnetic resonance study of post-plasma reactions in organosilicone microwave plasma-enhanced chemical vapor deposition (PECVD) coatings.

    PubMed

    Hall, Colin J; Ponnusamy, Thirunavukkarasu; Murphy, Peter J; Lindberg, Mats; Antzutkin, Oleg N; Griesser, Hans J

    2014-06-11

    Plasma-polymerized organosilicone coatings can be used to impart abrasion resistance and barrier properties to plastic substrates such as polycarbonate. Coating rates suitable for industrial-scale deposition, up to 100 nm/s, can be achieved through the use of microwave plasma-enhanced chemical vapor deposition (PECVD), with optimal process vapors such as tetramethyldisiloxane (TMDSO) and oxygen. However, it has been found that under certain deposition conditions, such coatings are subject to post-plasma changes; crazing or cracking can occur anytime from days to months after deposition. To understand the cause of the crazing and its dependence on processing plasma parameters, the effects of post-plasma reactions on the chemical bonding structure of coatings deposited with varying TMDSO-to-O2 ratios was studied with (29)Si and (13)C solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) using both single-pulse and cross-polarization techniques. The coatings showed complex chemical compositions significantly altered from the parent monomer. (29)Si MAS NMR spectra revealed four main groups of resonance lines, which correspond to four siloxane moieties (i.e., mono (M), di (D), tri (T), and quaternary (Q)) and how they are bound to oxygen. Quantitative measurements showed that the ratio of TMDSO to oxygen could shift the chemical structure of the coating from 39% to 55% in Q-type bonds and from 28% to 16% for D-type bonds. Post-plasma reactions were found to produce changes in relative intensities of (29)Si resonance lines. The NMR data were complemented by Fourier transform infrared (FTIR) spectroscopy. Together, these techniques have shown that the bonding environment of Si is drastically altered by varying the TMDSO-to-O2 ratio during PECVD, and that post-plasma reactions increase the cross-link density of the silicon-oxygen network. It appears that Si-H and Si-OH chemical groups are the most susceptible to post-plasma reactions. Coatings produced at a

  18. Structure Analyses of Organic Thin Films Prepared by a Plasma Enhanced Vacuum Evaporation

    NASA Astrophysics Data System (ADS)

    Sugimoto, Ryousuke; Osada, Kousuke; Kurata, Masahiko; Matsumoto, Hiroyuki; Iwamori, Satoru; Noda, Kazutoshi

    Organic thin films were prepared with pyromellitic dianhydride (PMDA) and oxydianiline (ODA) by vacuum evaporation with or without argon plasma, and molecular structures and surface morphologies of the PMDA, ODA, polyamic acid (PAA) and polyimide (PI) thin films were analyzed. The surface roughness decreased due to the plasma during the deposition. Oxygen content of the PMDA thin film prepared with the plasma decreased compared to that without the plasma. However, the PMDA thin film prepared with the plasma had a hydrophilic surface compared to that without the plasma. All of these organic thin films prepared with the plasma had hydrophilic surfaces compared to those without the plasma. Surface roughness of these thin films has a smaller effect on the wettability than hydrophilic moieties.

  19. Re-Heating Effect on the Enhancement of Plasma Emission Generated from Fe Under Femtosecond Double-Pulse Laser Irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Chen, Anmin; Li, Suyu; Sui, Laizhi; Liu, Dunli; Li, Shuchang; Li, He; Jiang, Yuanfei; Jin, Mingxing

    2016-12-01

    In this paper, we present a study on the effect of inter-pulse delay using femtosecond double-pulse laser-induced breakdown spectroscopy in a collinear geometry. The temporal evolution of spectral intensity is performed for the lines of Fe I 423.60 nm, Fe I 425.08 nm and Fe I 427.18 nm. It is found that, by selecting appropriate inter-pulse delay, the signal enhancement can be significantly increased compared with the single-pulse case. A three-fold enhancement in the current experiment is obtained. The plasma temperature and electron density are also investigated based on the theory of Boltzmann plot and Stark broadening. We attribute the main mechanism for emission enhancement to the plasma re-heating effect. supported by the National Basic Research Program of China (No. 2013CB922200), the China Postdoctoral Science Foundation (No. 2014M551169), National Natural Science Foundation of China (Nos. 11674128, 11474129 and 11504129)

  20. Gain enhancement plasma-loaded FEL in the presence of beat waves

    SciTech Connect

    Shamamian, A.H.; Gevorgian, L.A.

    1995-12-31

    An expression for the dielectric permittivity of underdense plasma interacting with laser beat waves is derived. It is shown that the presence of beat waves in plasma results in an effective growth of the plasma frequency. The FEL Gain is investigated in the case when the frequency of soft photons weakly depending on the electron beam energy and the synchronism condition is maintained. It is shown that the plasma beat waves lead to the essential increase in FEL gain.

  1. Remote automatic plasma arc-closure welding of a dry-storage canister for spent nuclear fuel and high-level radioactive waste

    SciTech Connect

    Sprecace, R.P.; Blankenship, W.P.

    1982-12-31

    A carbon steel storage canister has been designed for the dry encapsulation of spent nuclear fuel assemblies or of logs of vitrified high level radioactive waste. The canister design is in conformance with the requirements of the ASME Code, Section III, Division 1 for a Class 3 vessel. The canisters will be loaded and sealed as part of a completely remote process sequence to be performed in the hot bay of an experimental encapsulation facility at the Nevada Test Site. The final closure to be made is a full penetration butt weld between the canister body, a 12.75-in O.D. x 0.25-in wall pipe, and a mating semiellipsoidal closure lid. Due to a combination of design, application and facility constraints, the closure weld must be made in the 2G position (canister vertical). The plasma arc welding system is described, and the final welding procedure is described and discussed in detail. Several aspects and results of the procedure development activity, which are of both specific and general interest, are highlighted; these include: The critical welding torch features which must be exactly controlled to permit reproducible energy input to, and gas stream interaction with, the weld puddle. A comparison of results using automatic arc voltage control with those obtained using a mechanically fixed initial arc gap. The optimization of a keyhole initiation procedure. A comparison of results using an autogenous keyhole closure procedure with those obtained using a filler metal addition. The sensitivity of the welding process and procedure to variations in joint configuration and dimensions and to variations in base metal chemistry. Finally, the advantages and disadvantages of the plasma arc process for this application are summarized from the current viewpoint, and the applicability of this process to other similar applications is briefly indicated.

  2. Antibody-dependent enhancement of simian immunodeficiency virus (SIV) infection in vitro by plasma from SIV-infected rhesus macaques.

    PubMed Central

    Montefiori, D C; Robinson, W E; Hirsch, V M; Modliszewski, A; Mitchell, W M; Johnson, P R

    1990-01-01

    Plasma from two rhesus macaques (Macaca mulatta) experimentally infected with the simian immunodeficiency virus (SIV; isolate SIVmac251) enhanced SIVmac infection of a human CD4+ lymphoblastoid cell line, MT-2. Prechallenge plasma samples from these animals and serum from SIV-negative macaques did not enhance infection. Compared with controls, infection enhancement was characterized by the rapid appearance of syncytium formation (3 to 4 days sooner), reverse transcriptase release (10-fold increase), and cytopathic effect (60% cell killing). Enhancement of activity was dependent on the presence of diluted, fresh SIV-negative macaque serum as a source of complement. A requirement for complement was shown by the absence of enhancement in heat-inactivated serum and by dose-dependent inhibition of enhancement in the presence of polyclonal antibody to monkey complement component C3. Monoclonal antibody to CD4 (OKT4a) blocked enhancement completely, while monoclonal antibody to the human complement component C3d receptor CR2 (OKB7) reduced enhancement by greater than 50%, indicating a requirement for CD4 and CR2 in mediating this phenomenon. SIV infection-enhancing activity appeared in macaques soon after experimental inoculation (28 days). The titer increased over time and peaked just prior to the death of both macaques from opportunistic infections and lymphoma. In vitro SIV infection enhancement is nearly identical to the in vitro complement-mediated, antibody-dependent enhancing (C'-ADE) activity observed in human immunodeficiency virus-positive human sera (Robinson et al., Lancet i:790-794, 1988; Robinson et al., J. Acq. Immun. Def. Synd. 2:33-42, 1989). These observations validate the macaque-SIV model for studies of C'-ADE. Images PMID:2152808

  3. Enhanced performance of the microalga Chlorella sorokiniana remotely induced by the plant growth-promoting bacteria Azospirillum brasilense and Bacillus pumilus.

    PubMed

    Amavizca, Edgar; Bashan, Yoav; Ryu, Choong-Min; Farag, Mohamed A; Bebout, Brad M; de-Bashan, Luz E

    2017-02-01

    Remote effects (occurring without physical contact) of two plant growth-promoting bacteria (PGPB) Azospirillum brasilense Cd and Bacilus pumilus ES4 on growth of the green microalga Chlorella sorokiniana UTEX 2714 were studied. The two PGPB remotely enhanced the growth of the microalga, up to six-fold, and its cell volume by about three-fold. In addition to phenotypic changes, both bacteria remotely induced increases in the amounts of total lipids, total carbohydrates, and chlorophyll a in the cells of the microalga, indicating an alteration of the microalga's physiology. The two bacteria produced large amounts of volatile compounds, including CO2, and the known plant growth-promoting volatile 2,3-butanediol and acetoin. Several other volatiles having biological functions in other organisms, as well as numerous volatile compounds with undefined biological roles, were detected. Together, these bacteria-derived volatiles can positively affect growth and metabolic parameters in green microalgae without physical attachment of the bacteria to the microalgae. This is a new paradigm on how PGPB promote growth of microalgae which may serve to improve performance of Chlorella spp. for biotechnological applications.

  4. Enhanced performance of the microalga Chlorella sorokiniana remotely induced by the plant growth-promoting bacteria Azospirillum brasilense and Bacillus pumilus

    PubMed Central

    Amavizca, Edgar; Bashan, Yoav; Ryu, Choong-Min; Farag, Mohamed A.; Bebout, Brad M.; de-Bashan, Luz E.

    2017-01-01

    Remote effects (occurring without physical contact) of two plant growth-promoting bacteria (PGPB) Azospirillum brasilense Cd and Bacilus pumilus ES4 on growth of the green microalga Chlorella sorokiniana UTEX 2714 were studied. The two PGPB remotely enhanced the growth of the microalga, up to six-fold, and its cell volume by about three-fold. In addition to phenotypic changes, both bacteria remotely induced increases in the amounts of total lipids, total carbohydrates, and chlorophyll a in the cells of the microalga, indicating an alteration of the microalga’s physiology. The two bacteria produced large amounts of volatile compounds, including CO2, and the known plant growth-promoting volatile 2,3-butanediol and acetoin. Several other volatiles having biological functions in other organisms, as well as numerous volatile compounds with undefined biological roles, were detected. Together, these bacteria-derived volatiles can positively affect growth and metabolic parameters in green microalgae without physical attachment of the bacteria to the microalgae. This is a new paradigm on how PGPB promote growth of microalgae which may serve to improve performance of Chlorella spp. for biotechnological applications. PMID:28145473

  5. Enhanced nonlinear iterative techniques applied to a non-equilibrium plasma flow

    SciTech Connect

    Knoll, D.A.; McHugh, P.R.

    1996-12-31

    We study the application of enhanced nonlinear iterative methods to the steady-state solution of a system of two-dimensional convection-diffusion-reaction partial differential equations that describe the partially-ionized plasma flow in the boundary layer of a tokamak fusion reactor. This system of equations is characterized by multiple time and spatial scales, and contains highly anisotropic transport coefficients due to a strong imposed magnetic field. We use Newton`s method to linearize the nonlinear system of equations resulting from an implicit, finite volume discretization of the governing partial differential equations, on a staggered Cartesian mesh. The resulting linear systems are neither symmetric nor positive definite, and are poorly conditioned. Preconditioned Krylov iterative techniques are employed to solve these linear systems. We investigate both a modified and a matrix-free Newton-Krylov implementation, with the goal of reducing CPU cost associated with the numerical formation of the Jacobian. A combination of a damped iteration, one-way multigrid and a pseudo-transient continuation technique are used to enhance global nonlinear convergence and CPU efficiency. GMRES is employed as the Krylov method with Incomplete Lower-Upper(ILU) factorization preconditioning. The goal is to construct a combination of nonlinear and linear iterative techniques for this complex physical problem that optimizes trade-offs between robustness, CPU time, memory requirements, and code complexity. It is shown that a one-way multigrid implementation provides significant CPU savings for fine grid calculations. Performance comparisons of the modified Newton-Krylov and matrix-free Newton-Krylov algorithms will be presented.

  6. Enhanced photocatalytic performance in atomic layer deposition grown TiO{sub 2} thin films via hydrogen plasma treatment

    SciTech Connect

    Sasinska, Alexander; Singh, Trilok; Wang, Shuangzhou; Mathur, Sanjay; Kraehnert, Ralph

    2015-01-15

    The authors report the effect of hydrogen plasma treatment on TiO{sub 2} thin films grown by atomic layer deposition as an effective approach for modifying the photoanode materials in order to enhance their photoelectrochemical performance. Hydrogen plasma treated TiO{sub 2} thin films showed an improved absorption in the visible spectrum probably due to surface reduction. XPS analysis confirmed the formation of Ti{sup 3+} states upon plasma treatment. Hydrogen plasma treatment of TiO{sub 2} films enhanced the measured photocurrent densities by a factor of 8 (1 mA/cm{sup 2} at 0.8 V versus normal hydrogen electrode) when compared to untreated TiO{sub 2} (0.12 mA/cm{sup 2}). The enhancement in photocurrent is attributed to the formation of localized electronic states in mid band-gap region, which facilitate efficient separation and transportation of photo excited charge carriers in the UV region of electromagnetic spectrum.

  7. Comparison of gate dielectric plasma damage from plasma-enhanced atomic layer deposited and magnetron sputtered TiN metal gates

    SciTech Connect

    Brennan, Christopher J.; Neumann, Christopher M.; Vitale, Steven A.

    2015-07-28

    Fully depleted silicon-on-insulator transistors were fabricated using two different metal gate deposition mechanisms to compare plasma damage effects on gate oxide quality. Devices fabricated with both plasma-enhanced atomic-layer-deposited (PE-ALD) TiN gates and magnetron plasma sputtered TiN gates showed very good electrostatics and short-channel characteristics. However, the gate oxide quality was markedly better for PE-ALD TiN. A significant reduction in interface state density was inferred from capacitance-voltage measurements as well as a 1200× reduction in gate leakage current. A high-power magnetron plasma source produces a much higher energetic ion and vacuum ultra-violet (VUV) photon flux to the wafer compared to a low-power inductively coupled PE-ALD source. The ion and VUV photons produce defect states in the bulk of the gate oxide as well as at the oxide-silicon interface, causing higher leakage and potential reliability degradation.

  8. Electron heating and control of electron energy distribution in hybrid plasma source for the enhancement of the plasma ashing processing

    NASA Astrophysics Data System (ADS)

    Lee, Hyo-Chang; Chung, Chin-Wook

    2015-09-01

    In this study, control of the electron energy distribution function (EEDF) is investigated in hybrid plasma source with inductive and capacitive fields. With the addition of a small amount of antenna coil power to the capacitive discharge, low energy electrons are effectively heated and the EEDF is controlled. This method is applied to the ashing process of the photoresistor (PR). It is revealed that the ashing rate of the PR is significantly increased due to O radicals produced by the controlled EEDF, even though the ion density/energy flux is not increased. The roles of the power transfer mode, the electron heating, and the discharge parameters are also presented in the hybrid plasma source. This work can be used to an inter-ashing method during etching process.

  9. Electrical resistivity change in Al:ZnO thin films dynamically deposited by bipolar pulsed direct-current sputtering and a remote plasma source

    SciTech Connect

    Yang, Wonkyun; Joo, Junghoon

    2010-07-15

    The Al-doped ZnO (AZO) thin films for a transparent conducting oxide in solar cell devices were deposited by bipolar pulsed dc magnetron sputtering. This work was performed in an in-line type system and investigated AZO films in a static deposition mode and dynamic one, which is more important in the practical fields. Because of this dynamic deposition process, the zigzagged columnar structure was observed. This resulted in the decreasing electrical property, optical properties, and surface roughness. As a deposition in the dynamic mode, the resistivity increased from 1.64x10{sup -3} to 2.50x10{sup -3} {Omega} cm, as compared to that in the static mode, and the transmittance also decreased from 83.9% to 78.3%. To recover the disadvantage, a remote plasma source (RPS) was supported between the substrate and target for reducing zigzagged formation during the deposition. The deposition rate decreased by using RPS, but the electrical and optical properties of films got better than only dynamic mode. The resistivity and transmittance in the dynamic mode using RPS were 2.1x10{sup -3} {Omega} cm and 85.5%, respectively. In this study, the authors found the possibility to advance the electrical and optical properties of AZO thin films in the industry mode.

  10. Epitaxial growth of GaN by radical-enhanced metalorganic chemical vapor deposition (REMOCVD) in the downflow of a very high frequency (VHF) N2/H2 excited plasma - effect of TMG flow rate and VHF power

    NASA Astrophysics Data System (ADS)

    Lu, Yi; Kondo, Hiroki; Ishikawa, Kenji; Oda, Osamu; Takeda, Keigo; Sekine, Makoto; Amano, Hiroshi; Hori, Masaru

    2014-04-01

    Gallium nitride (GaN) films have been grown by using our newly developed Radical-Enhanced Metalorganic Chemical Vapor Deposition (REMOCVD) system. This system has three features: (1) application of very high frequency (60 MHz) power in order to increase the plasma density, (2) introduction of H2 gas together with N2 gas in the plasma discharge region to generate not only nitrogen radicals but also active NHx molecules, and (3) radical supply under remote plasma arrangement with suppression of charged ions and photons by employing a Faraday cage. Using this new system, we have studied the effect of the trimethylgallium (TMG) source flow rate and of the plasma generation power on the GaN crystal quality by using scanning electron microscopy (SEM) and double crystal X-ray diffraction (XRD). We found that this REMOCVD allowed the growth of epitaxial GaN films of the wurtzite structure of (0001) orientation on sapphire substrates with a high growth rate of 0.42 μm/h at a low temperature of 800 °C. The present REMOCVD is a promising method for GaN growth at relatively low temperature and without using costly ammonia gas.

  11. Chain Assemblies from Nanoparticles Synthesized by Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition: The Computational View.

    PubMed

    Mishin, Maxim V; Zamotin, Kirill Y; Protopopova, Vera S; Alexandrov, Sergey E

    2015-12-01

    This article refers to the computational study of nanoparticle self-organization on the solid-state substrate surface with consideration of the experimental results, when nanoparticles were synthesised during atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD). The experimental study of silicon dioxide nanoparticle synthesis by AP-PECVD demonstrated that all deposit volume consists of tangled chains of nanoparticles. In certain cases, micron-sized fractals are formed from tangled chains due to deposit rearrangement. This work is focused on the study of tangled chain formation only. In order to reveal their formation mechanism, a physico-mathematical model was developed. The suggested model was based on the motion equation solution for charged and neutral nanoparticles in the potential fields with the use of the empirical interaction potentials. In addition, the computational simulation was carried out based on the suggested model. As a result, the influence of such experimental parameters as deposition duration, particle charge, gas flow velocity, and angle of gas flow was found. It was demonstrated that electrical charges carried by nanoparticles from the discharge area are not responsible for the formation of tangled chains from nanoparticles, whereas nanoparticle kinetic energy plays a crucial role in deposit morphology and density. The computational results were consistent with experimental results.

  12. Phthalate degradation by glow discharge plasma enhanced with pyrite in aqueous solution.

    PubMed

    Shen, Chensi; Wu, Shaoshuai; Chen, Hui; Rashid, Sadia; Wen, Yuezhong

    2016-09-01

    In order to prevent health risk from potential exposures to phthalates, a glow discharge plasma (GDP) process was applied for phthalate degradation in aqueous solution. The results revealed that the phthalate derivatives 4-hydroxyphthalic acid, 4-methylphthalic acid and 4-tert-butylphthalic anhydride could be degraded efficiently in GDP process (498 V, 0.2 A) with high removal efficiencies of over 99% in 60 minutes. Additionally, pyrite as a promising heterogeneous iron source in the Fenton reaction was found to be favorable for GDP process. The phthalate degradation reaction could be significantly enhanced by the continuous formation of •OH and the inhibition of the quenching reaction in the pyrite Fenton system due to the constant dissolution of Fe(II) from pyrite surface. Meanwhile, the initial pH value showed little impact on the degradation of phthalates and the energy efficiency of GDP system for phthalate degradation ranged between 0.280 × 10(-9) and 1.210 × 10(-9) mol/J, which is similar to the GDP system with phenol, bisphenol A and methyl tert-butyl ether as the substrates. Further, the X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy analyses indicated that the pyrite was relatively stable in GDP system and there was no obvious polymeric compound formed on the catalyst surface. Overall, this GDP process offers high removal efficiency, simple technology, considerable energy efficiency and the applicability to salt-containing phthalate wastewater.

  13. Preparation Of Electrochromic Metal Oxide Films By Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Benson, D. K.; Tracy, C. E.; Svensson, J. S. E. M.; Liebert, B. E.

    1987-11-01

    Laboratory procedures have been developed for depositing thin films of electrochromic metal oxides by plasma-enhanced chemical vapor deposition (PE-CVD). In this process, vapor phase reactants, such as tungsten hexafluotIde, are mixed with oxygen and excited by RF energy at a frequency of 13.56 MHz and power levels up to≍1W/cm2 substrate area. Large rates of oxide deposition have been achieved (> 8 nm/s) making this process a candidate for high-speed coating of large area substrates, such as window glass. Amorphous WO1 films prepared by PE-CVD have been shown to have electrochromic responses virtually identical to films prepared by vacuum evaporation. The lithium ion diffusion rate, for example, is approximately 1.3 x 10-11 cm2 /s at x = 0.03 in LixWO3 prepared by PE-CVD. On the other hand, molybdenum oxide films and mixed molybdenum/tungsten oxide films prepared by PE-CVD from the hexafluorides differ markedly from vacuum evaporated films. Their electrochromic responses are spectrally different and are much slower. Lithium ion diffusion rates in such Mo03 films are lower by about three orders of magnitude. These differences are tentatively attributed to a large fraction of fluorine (Mo:F ratios of the order of 2:1) which are incorporated into the molybdenum and mixed oxides, but are not incorporated into the tungsten oxides.

  14. Current transport mechanisms in plasma-enhanced atomic layer deposited AlN thin films

    SciTech Connect

    Altuntas, Halit E-mail: biyikli@unam.bilkent.edu.tr; Ozgit-Akgun, Cagla; Donmez, Inci; Biyikli, Necmi E-mail: biyikli@unam.bilkent.edu.tr

    2015-04-21

    Here, we report on the current transport mechanisms in AlN thin films deposited at a low temperature (i.e., 200 °C) on p-type Si substrates by plasma-enhanced atomic layer deposition. Structural characterization of the deposited AlN was carried out using grazing-incidence X-ray diffraction, revealing polycrystalline films with a wurtzite (hexagonal) structure. Al/AlN/ p-Si metal-insulator-semiconductor (MIS) capacitor structures were fabricated and investigated under negative bias by performing current-voltage measurements. As a function of the applied electric field, different types of current transport mechanisms were observed; i.e., ohmic conduction (15.2–21.5 MV/m), Schottky emission (23.6–39.5 MV/m), Frenkel-Poole emission (63.8–211.8 MV/m), trap-assisted tunneling (226–280 MV/m), and Fowler-Nordheim tunneling (290–447 MV/m). Electrical properties of the insulating AlN layer and the fabricated Al/AlN/p-Si MIS capacitor structure such as dielectric constant, flat-band voltage, effective charge density, and threshold voltage were also determined from the capacitance-voltage measurements.

  15. Boron nitride nanowalls: low-temperature plasma-enhanced chemical vapor deposition synthesis and optical properties.

    PubMed

    Merenkov, Ivan S; Kosinova, Marina L; Maximovskii, Eugene A

    2017-05-05

    Hexagonal boron nitride (h-BN) nanowalls (BNNWs) were synthesized by plasma-enhanced chemical vapor deposition (PECVD) from a borazine (B3N3H6) and ammonia (NH3) gas mixture at a low temperature range of 400 °C-600 °C on GaAs(100) substrates. The effect of the synthesis temperature on the structure and surface morphology of h-BN films was investigated. The length and thickness of the h-BN nanowalls were in the ranges of 50-200 nm and 15-30 nm, respectively. Transmission electron microscope images showed the obtained BNNWs were composed of layered non-equiaxed h-BN nanocrystallites 5-10 nm in size. The parallel-aligned h-BN layers as an interfacial layer were observed between the film and GaAs(100) substrate. BNNWs demonstrate strong blue light emission, high transparency (>90%) both in visible and infrared spectral regions and are promising for optical applications. The present results enable a convenient growth of BNNWs at low temperatures.

  16. Characterization of diamond-like nanocomposite thin films grown by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Santra, T. S.; Liu, C. H.; Bhattacharyya, T. K.; Patel, P.; Barik, T. K.

    2010-06-01

    Diamond-like nanocomposite (DLN) thin films, comprising the networks of a-C:H and a-Si:O were deposited on pyrex glass or silicon substrate using gas precursors (e.g., hexamethyldisilane, hexamethyldisiloxane, hexamethyldisilazane, or their different combinations) mixed with argon gas, by plasma enhanced chemical vapor deposition technique. Surface morphology of DLN films was analyzed by atomic force microscopy. High-resolution transmission electron microscopic result shows that the films contain nanoparticles within the amorphous structure. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) were used to determine the structural change within the DLN films. The hardness and friction coefficient of the films were measured by nanoindentation and scratch test techniques, respectively. FTIR and XPS studies show the presence of CC, CH, SiC, and SiH bonds in the a-C:H and a-Si:O networks. Using Raman spectroscopy, we also found that the hardness of the DLN films varies with the intensity ratio ID/IG. Finally, we observed that the DLN films has a better performance compared to DLC, when it comes to properties like high hardness, high modulus of elasticity, low surface roughness and low friction coefficient. These characteristics are the critical components in microelectromechanical systems (MEMS) and emerging nanoelectromechanical systems (NEMS).

  17. Chromium functionalized diglyme plasma polymer coating enhances enzyme-linked immunosorbent assay performance.

    PubMed

    Welch, Nicholas G; Madiona, Robert M T; Easton, Christopher D; Scoble, Judith A; Jones, Robert T; Muir, Benjamin W; Pigram, Paul J

    2016-11-10

    Ensuring the optimum orientation, conformation, and density of substrate-bound antibodies is critical for the success of sandwich enzyme-linked immunosorbent assays (ELISAs). In this work, the authors utilize a diethylene glycol dimethyl ether plasma polymer (DGpp) coating, functionalized with chromium within a 96 well plate for the enhanced immobilization of a capture antibody. For an equivalent amount of bound antibody, a tenfold improvement in the ELISA signal intensity is obtained on the DGpp after incubation with chromium, indicative of improved orientation on this surface. Time-of-flight secondary-ion-mass-spectrometry (ToF-SIMS) and principal component analysis were used to probe the molecular species at the surface and showed ion fragments related to lysine, methionine, histidine, and arginine coupled to chromium indicating candidate antibody binding sites. A combined x-ray photoelectron spectroscopy and ToF-SIMS analysis provided a surface molecular characterization that demonstrates antibody binding via the chromium complex. The DGpp+Cr surface treatment holds great promise for improving the efficacy of ELISAs.

  18. Surface modification of silicon-containing fluorocarbon films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Jin, Yoonyoung; Desta, Yohannes; Goettert, Jost; Lee, G. S.; Ajmera, P. K.

    2005-07-01

    Surface modification of silicon-containing fluorocarbon (SiCF) films achieved by wet chemical treatments and through x-ray irradiation is examined. The SiCF films were prepared by plasma-enhanced chemical vapor deposition, using gas precursors of tetrafluoromethane and disilane. As-deposited SiCF film composition was analyzed by x-ray photoelectron spectroscopy. Surface modification of SiCF films utilizing n-lithiodiaminoethane wet chemical treatment is discussed. Sessile water-drop contact angle changed from 95°+/-2° before treatment to 32°+/-2° after treatment, indicating a change in the film surface characteristics from hydrophobic to hydrophilic. For x-ray irradiation on the SiCF film with a dose of 27.4 kJ/cm3, the contact angle of the sessile water drop changed from 95°+/-2° before radiation to 39°+/-3° after x-ray exposure. The effect of x-ray exposure on chemical bond structure of SiCF films is studied using Fourier transform infrared measurements. Electroless Cu deposition was performed to test the applicability of the surface modified films. The x-ray irradiation method offers a unique advantage in making possible surface modification in a localized area of high-aspect-ratio microstructures. Fabrication of a Ti-membrane x-ray mask is introduced here for selective surface modification using x-ray irradiation.

  19. New diagnostic methods for laser plasma- and microwave-enhanced combustion

    PubMed Central

    Miles, Richard B; Michael, James B; Limbach, Christopher M; McGuire, Sean D; Chng, Tat Loon; Edwards, Matthew R; DeLuca, Nicholas J; Shneider, Mikhail N; Dogariu, Arthur

    2015-01-01

    The study of pulsed laser- and microwave-induced plasma interactions with atmospheric and higher pressure combusting gases requires rapid diagnostic methods that are capable of determining the mechanisms by which these interactions are taking place. New rapid diagnostics are presented here extending the capabilities of Rayleigh and Thomson scattering and resonance-enhanced multi-photon ionization (REMPI) detection and introducing femtosecond laser-induced velocity and temperature profile imaging. Spectrally filtered Rayleigh scattering provides a method for the planar imaging of temperature fields for constant pressure interactions and line imaging of velocity, temperature and density profiles. Depolarization of Rayleigh scattering provides a measure of the dissociation fraction, and multi-wavelength line imaging enables the separation of Thomson scattering from Rayleigh scattering. Radar REMPI takes advantage of high-frequency microwave scattering from the region of laser-selected species ionization to extend REMPI to atmospheric pressures and implement it as a stand-off detection method for atomic and molecular species in combusting environments. Femtosecond laser electronic excitation tagging (FLEET) generates highly excited molecular species and dissociation through the focal zone of the laser. The prompt fluorescence from excited molecular species yields temperature profiles, and the delayed fluorescence from recombining atomic fragments yields velocity profiles. PMID:26170432

  20. Structural and optical properties of silicon nanocrystals grown by plasma-enhanced chemical vapor deposition.

    PubMed

    Prakash, G V; Daldosso, N; Degoli, E; Iacona, F; Cazzanelli, M; Gaburro, Z; Pucker, G; Dalba, P; Rocca, F; Ceretta Moreira, E; Franzò, G; Pacifici, D; Priolo, F; Arcangeli, C; Filonov, A B; Ossicini, S; Pavesi, L

    2001-06-01

    Silicon nanocrystals (Si-nc) embedded in SiO2 matrix have been prepared by high temperature thermal annealing (1000-1250 degrees C) of substoichiometric SiOx films deposited by plasma-enhanced chemical vapor deposition (PECVD). Different techniques have been used to examine the optical and structural properties of Si-nc. Transmission electron microscopy analysis shows the formation of nanocrystals whose sizes are dependent on annealing conditions and deposition parameters. The spectral positions of room temperature photoluminescence are systematically blue shifted with reduction in the size of Si-nc obtained by decreasing the annealing temperature or the Si content during the PECVD deposition. A similar trend has been found in optical absorption measurements. X-ray absorption fine structure measurements indicate the presence of an intermediate region between the Si-nc and the SiO2 matrix that participates in the light emission process. Theoretical observations reported here support these findings. All these efforts allow us to study the link between dimensionality, optical properties, and the local environment of Si-nc and the surrounding SiO2 matrix.

  1. Hydrazine-enhanced NO conversion in a pulsed corona discharge plasma (PCDP) reactor: Behaviors and mechanism

    NASA Astrophysics Data System (ADS)

    Hong, Liu; Chen, De-Zhen; Yin, Li-Jie; Chen, Hui; Wang, Du; Hu, Yu-Yan

    2016-09-01

    The NO conversion efficiency in a pulsed corona discharge plasma (PCDP) reactor in the presence of a new additive, hydrazine hydrate (N2H4.H2O), was studied, and the reaction mechanism was analyzed. The NO conversion efficiency reached 62.5%, and the NO conversion Energy Yield (EY) reached 20.9 gNO/kWh, which is higher than that obtained using water or ammonia additives under the same conditions. The predominant elementary reactions and radicals, as well as the mechanism by which the additive enhanced the NO conversion process, were determined by comparing experimental data with theoretical simulation results and by performing a sensitivity analysis. After the addition of N2H4.H2O, the N2H4 reacts with radicals generated in the PCDP reactor to form a large quantity of strongly reducing species with NH2 as the predominant component, which can directly reduce NO to N2 and effectively prevent the generation of N2O. Compared with the traditional PCDP-based De-NOx process in which nitric acid is generated by oxidation with an additional neutralization step required, this new PCDP-based De-NOx process with N2H4.H2O addition is superior because NO is mostly reduced to N2. The study provides a basis for the application of N2H4.H2O as a synergist to improve NO abatement in a PCDP reactor.

  2. Thermal Conductivity of Nanocrystalline Silicon Prepared by Plasma-Enhanced Chemical-Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Jugdersuren, Battogtokh; Liu, Xiao; Kearney, Brian; Queen, Daniel; Metcalf, Thomas; Culbertson, James; Chervin, Christopher; Katz, Michael; Stroud, Rhonda

    Nanocrystallization by ball milling has been used successfully to reduce the thermal conductivity of silicon-germanium alloys (SiGe) and turn them into useful thermoelectric materials at a temperature of a few hundred degrees C. Currently the smallest grain sizes in nanocrystalline SiGe are in the 10 nm range. Germanium is added to scatter short wavelength phonons by impurity scattering. In this work, we report a record low thermal conductivity in nanocrystalline silicon prepared by plasma-enhanced chemical-vapor deposition. By varying hydrogen to silane ratio, we can vary the average grain sizes from greater than 10 nm down to 3 nm, as determined by both the high resolution transmission electron microscopy and X-ray diffraction. The values of thermal conductivity, as measured by the 3 ω technique, can be correspondingly modulated from that of ball-milled nanocrystalline SiGe to a record low level of 0.3 W/mK at room temperature. This low thermal conductivity is only about 1/3 of the minimum thermal conductivity limit of silicon. Possible causes of such a large reduction are discussed. Work supported by the Office of Naval Research.

  3. Optimization of silicon oxynitrides by plasma-enhanced chemical vapor deposition for an interferometric biosensor

    NASA Astrophysics Data System (ADS)

    Choo, Sung Joong; Lee, Byung-Chul; Lee, Sang-Myung; Park, Jung Ho; Shin, Hyun-Joon

    2009-09-01

    In this paper, silicon oxynitride layers deposited with different plasma-enhanced chemical vapor deposition (PECVD) conditions were fabricated and optimized, in order to make an interferometric sensor for detecting biochemical reactions. For the optimization of PECVD silicon oxynitride layers, the influence of the N2O/SiH4 gas flow ratio was investigated. RF power in the PEVCD process was also adjusted under the optimized N2O/SiH4 gas flow ratio. The optimized silicon oxynitride layer was deposited with 15 W in chamber under 25/150 sccm of N2O/SiH4 gas flow rates. The clad layer was deposited with 20 W in chamber under 400/150 sccm of N2O/SiH4 gas flow condition. An integrated Mach-Zehnder interferometric biosensor based on optical waveguide technology was fabricated under the optimized PECVD conditions. The adsorption reaction between bovine serum albumin (BSA) and the silicon oxynitride surface was performed and verified with this device.

  4. Use of plasma enhanced ALD to construct efficient interference filters for astronomy in the FUV

    NASA Astrophysics Data System (ADS)

    Scowen, Paul A.; Nemanich, Robert; Eller, Brianna; Yu, Hongbin; Mooney, Tom; Beasley, Matt

    2016-07-01

    Over the past few years the advent of atomic layer deposition (ALD) technology has opened new capabilities to the field of coatings deposition for use in optical elements. At the same time, there have been major advances in both optical designs and detector technologies that can provide orders of magnitude improvement in throughput in the far ultraviolet (FUV) and near ultraviolet (NUV) passbands. Recent review work has shown that a veritable revolution is about to happen in astronomical diagnostic work for targets ranging from protostellar and protoplanetary systems, to the intergalactic medium that feeds gas supplies for galactic star formation, and supernovae and hot gas from star forming regions that determine galaxy formation feedback. These diagnostics are rooted in access to a forest of emission and absorption lines in the ultraviolet (UV)[1], and all that prevents this advance is the lack of throughput in such systems, even in space-based conditions. We outline an approach to use a range of materials to implement stable optical layers suitable for protective overcoats with high UV reflectivity and unprecedented uniformity, and use that capability to leverage innovative ultraviolet/optical filter construction to enable astronomical science. These materials will be deposited in a multilayer format over a metal base to produce a stable construct. Specifically, we will employ the use of PEALD (plasma-enhanced atomic layer deposition) methods for the deposition and construction of reflective layers that can be used to construct unprecedented filter designs for use in the ultraviolet.

  5. A plasma protein corona enhances the biocompatibility of Au@Fe3O4 Janus particles.

    PubMed

    Landgraf, Lisa; Christner, Carolin; Storck, Wiebke; Schick, Isabel; Krumbein, Ines; Dähring, Heidi; Haedicke, Katja; Heinz-Herrmann, Karl; Teichgräber, Ulf; Reichenbach, Jürgen R; Tremel, Wolfgang; Tenzer, Stefan; Hilger, Ingrid

    2015-11-01

    Au@Fe3O4 Janus particles (JPs) are heteroparticles with discrete domains defined by different materials. Their tunable composition and morphology confer multimodal and versatile capabilities for use as contrast agents and drug carriers in future medicine. Au@Fe3O4 JPs have colloidal properties and surface characteristics leading to interactions with proteins in biological fluids. The resulting protein adsorption layer ("protein corona") critically affects their interaction with living matter. Although Au@Fe3O4 JPs displayed good biocompatibility in a standardized in vitro situation, an in-depth characterization of the protein corona is of prime importance to unravel underlying mechanisms affecting their pathophysiology and biodistribution in vitro and in vivo. Here, we comparatively analyzed the human plasma corona of Au-thiol@Fe3O4-SiO2-PEG JPs (NH2-functionalized and non-functionalized) and spherical magnetite (Fe3O4-SiO2-PEG) particles and investigated its effects on colloidal stability, biocompatibility and cellular uptake. Label-free quantitative proteomic analyses revealed that complex coronas including almost 180 different proteins were formed within only one minute. Remarkably, in contrast to spherical magnetite particles with surface NH2 groups, the Janus structure prevented aggregation and the adhesion of opsonins. This resulted in an enhanced biocompatibility of corona sheathed JPs compared to spherical magnetite particles and corona-free JPs.

  6. HIV-1 enhancing effect of prostatic acid phosphatase peptides is reduced in human seminal plasma.

    PubMed

    Martellini, Julie A; Cole, Amy L; Svoboda, Pavel; Stuchlik, Olga; Chen, Li-Mei; Chai, Karl X; Gangrade, Bhushan K; Sørensen, Ole E; Pohl, Jan; Cole, Alexander M

    2011-01-20

    We recently reported that HIV-1 infection can be inhibited by innate antimicrobial components of human seminal plasma (SP). Conversely, naturally occurring peptidic fragments from the SP-derived prostatic acid phosphatase (PAP) have been reported to form amyloid fibrils called "SEVI" and enhance HIV-1 infection in vitro. In order to understand the biological consequence of this proviral effect, we extended these studies in the presence of human SP. PAP-derived peptides were agitated to form SEVI and incubated in the presence or absence of SP. While PAP-derived peptides and SEVI alone were proviral, the presence of 1% SP ablated their proviral activity in several different anti-HIV-1 assays. The anti-HIV-1 activity of SP was concentration dependent and was reduced following filtration. Supraphysiological concentrations of PAP peptides and SEVI incubated with diluted SP were degraded within hours, with SP exhibiting proteolytic activity at dilutions as high as 1:200. Sub-physiological concentrations of two prominent proteases of SP, prostate-specific antigen (PSA) and matriptase, could degrade physiological and supraphysiological concentrations of PAP peptides and SEVI. While human SP is a complex biological fluid, containing both antiviral and proviral factors, our results suggest that PAP peptides and SEVI may be subject to naturally occurring proteolytic components capable of reducing their proviral activity.

  7. Study of strong enhancement of synchrotron radiation via surface plasma waves excitation by particle-in-cell simulations

    SciTech Connect

    Pan, K. Q.; Zheng, C. Y. Cao, L. H.; He, X. T.; Wu, Dong; Liu, Z. J.

    2015-11-02

    Synchrotron radiation is strongly enhanced by the resonant excitation of surface plasma waves (SPWs). Two-dimensional particle-in-cell simulations show that energy conversion efficiency from laser to radiation in the case of SPWs excitation is about 18.7%, which is improved by more than 2 orders of magnitude compared with that of no SPWs excitation. Besides the high energy conversion efficiency, the frequency spectrum and the angular distribution of the radiation are also improved in the case of SPWs excitation because of the quasi-static magnet field induced by surface plasma waves excitation.

  8. Label-free detection of blood plasma using silver nanoparticle based surface-enhanced Raman spectroscopy for esophageal cancer screening.

    PubMed

    Li, Duo; Feng, Shangyuan; Huang, Hao; Chen, Weisheng; Shi, Hong; Liu, Nenrong; Chen, Long; Chen, Weiwei; Yu, Yun; Chen, Rong

    2014-03-01

    A surface-enhanced Raman spectroscopy (SERS) based on silver nanoparticle technology was applied to analyze and classify human blood plasma with the aim to develop a simple and label-free blood test for esophageal cancer detection. High quality SERS spectra in the range of 400-1800 cm(-1) can be acquired from 36 esophageal cancer patients and 50 healthy volunteers' blood plasma samples. Tentative assignments of the SERS bands indicated specific biomolecular changes associated with cancer transformation, including an increase in the relative amounts of nucleic acid and phenylalanine, a decrease in the percentage of saccharide and proteins contents in the cancer blood plasma compared to that of healthy subjects. Furthermore, both SVM and PCA-LDA diagnostic algorithm were employed to analyze and classify the obtained blood plasma SERS spectra between normal and cancer plasma with a high diagnostic accuracy (around 90%). This exploratory work demonstrates that the label-free plasma SERS analysis technique in conjunction with SVM and PCA-LDA diagnostic algorithms has great potential for improving esophageal cancer detection and screening.

  9. Fabrication of metallic single electron transistors featuring plasma enhanced atomic layer deposition of tunnel barriers

    NASA Astrophysics Data System (ADS)

    Karbasian, Golnaz

    The continuing increase of the device density in integrated circuits (ICs) gives rise to the high level of power that is dissipated per unit area and consequently a high temperature in the circuits. Since temperature affects the performance and reliability of the circuits, minimization of the energy consumption in logic devices is now the center of attention. According to the International Technology Roadmaps for Semiconductors (ITRS), single electron transistors (SETs) hold the promise of achieving the lowest power of any known logic device, as low as 1x10-18 J per switching event. Moreover, SETs are the most sensitive electrometers to date, and are capable of detecting a fraction of an electron charge. Despite their low power consumption and high sensitivity for charge detection, room temperature operation of these devices is quite challenging mainly due to lithographical constraints in fabricating structures with the required dimensions of less than 10 nm. Silicon based SETs have been reported to operate at room temperature. However, they all suffer from significant variation in batch-to-batch performance, low fabrication yield, and temperature-dependent tunnel barrier height. In this project, we explored the fabrication of SETs featuring metal-insulator-metal (MIM) tunnel junctions. While Si-based SETs suffer from undesirable effect of dopants that result in irregularities in the device behavior, in metal-based SETs the device components (tunnel barrier, island, and the leads) are well-defined. Therefore, metal SETs are potentially more predictable in behavior, making them easier to incorporate into circuits, and easier to check against theoretical models. Here, the proposed fabrication method takes advantage of unique properties of chemical mechanical polishing (CMP) and plasma enhanced atomic layer deposition (PEALD). Chemical mechanical polishing provides a path for tuning the dimensions of the tunnel junctions, surpassing the limits imposed by electron beam

  10. Whistler wave radiation from a pulsed loop antenna located in a cylindrical duct with enhanced plasma density

    SciTech Connect

    Kudrin, Alexander V.; Shkokova, Natalya M.; Ferencz, Orsolya E.; Zaboronkova, Tatyana M.

    2014-11-15

    Pulsed radiation from a loop antenna located in a cylindrical duct with enhanced plasma density is studied. The radiated energy and its distribution over the spatial and frequency spectra of the excited waves are derived and analyzed as functions of the antenna and duct parameters. Numerical results referring to the case where the frequency spectrum of the antenna current is concentrated in the whistler range are reported. It is shown that under ionospheric conditions, the presence of an artificial duct with enhanced density can lead to a significant increase in the energy radiated from a pulsed loop antenna compared with the case where the same source is immersed in the surrounding uniform magnetoplasma. The results obtained can be useful in planning active ionospheric experiments with pulsed electromagnetic sources operated in the presence of artificial field-aligned plasma density irregularities that are capable of guiding whistler waves.

  11. Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

    NASA Astrophysics Data System (ADS)

    Suyanto, Hery; Pardede, Marincan; Hedwig, Rinda; Marpaung, Alion Mangasi; Ramli, Muliadi; Lie, Tjung Jie; Abdulmadjid, Syahrun Nur; Kurniawan, Koo Hendrik; Tjia, May On; Kagawa, Kiichiro

    2016-08-01

    A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns) and picosecond (ps) lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE) mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS) using He ambient gas.

  12. Spectral simulation methods for enhancing qualitative and quantitative analyses based on infrared spectroscopy and quantitative calibration methods for passive infrared remote sensing of volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Sulub, Yusuf Ismail

    Infrared spectroscopy (IR) has over the years found a myriad of applications including passive environmental remote sensing of toxic pollutants and the development of a blood glucose sensor. In this dissertation, capabilities of both these applications are further enhanced with data analysis strategies employing digital signal processing and novel simulation approaches. Both quantitative and qualitative determinations of volatile organic compounds are investigated in the passive IR remote sensing research described in this dissertation. In the quantitative work, partial least-squares (PLS) regression analysis is used to generate multivariate calibration models for passive Fourier transform IR remote sensing measurements of open-air generated vapors of ethanol in the presence methanol as an interfering species. A step-wise co-addition scheme coupled with a digital filtering approach is used to attenuate the effects of variation in optical path length or plume width. For the qualitative study, an IR imaging line scanner is used to acquire remote sensing data in both spatial and spectral domains. This technology is capable of not only identifying but also specifying the location of the sample under investigation. Successful implementation of this methodology is hampered by the huge costs incurred to conduct these experiments and the impracticality of acquiring large amounts of representative training data. To address this problem, a novel simulation approach is developed that generates training data based on synthetic analyte-active and measured analyte-inactive data. Subsequently, automated pattern classifiers are generated using piecewise linear discriminant analysis to predict the presence of the analyte signature in measured imaging data acquired in remote sensing applications. Near infrared glucose determinations based on the region of 5000--4000 cm-1 is the focus of the research in the latter part of this dissertation. A six-component aqueous matrix of glucose

  13. Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Lu, Y. F.; Tang, L. J.; Wu, Y. H.; Cho, B. J.; Xu, X. J.; Dong, J. R.; Song, W. D.

    2005-01-01

    We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiOx, 0plasma-enhanced chemical vapor deposition at different nitrous-oxide/silane flow ratios. The physical and optical properties of the SiOx films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 °C, the intermediate Si continuum in XPS spectra (referring to the suboxide) split to Si peaks corresponding to SiO2 and elemental Si. This change indicates the phase separation of the SiOx into more stable SiO2 and Si clusters. Raman, high-resolution transmission electron microscopy and optical absorption confirmed the phase separation and the formation of Si NCs in the films. The size of Si NCs increases with increasing Si concentration in the films and increasing annealing temperature. Two photoluminescence (PL) bands were observed in the films after annealing. The ultraviolet (UV)-range PL with a peak fixed at 370-380 nm is independent of Si concentration and annealing temperature, which is a characteristic of defect states. Strong PL in red range shows redshifts from ˜600 to 900 nm with increasing Si concentration and annealing temperature, which supports the quantum confinement model. After oxidation of the high-temperature annealed films, the UV PL was almost quenched while the red PL shows continuous blueshifts with increasing oxidation time. The different oxidation behaviors further relate the UV PL to the defect states and the red PL to the recombination of quantum-confined excitions.

  14. Gettering of interstitial iron in silicon by plasma-enhanced chemical vapour deposited silicon nitride films

    NASA Astrophysics Data System (ADS)

    Liu, A. Y.; Sun, C.; Markevich, V. P.; Peaker, A. R.; Murphy, J. D.; Macdonald, D.

    2016-11-01

    It is known that the interstitial iron concentration in silicon is reduced after annealing silicon wafers coated with plasma-enhanced chemical vapour deposited (PECVD) silicon nitride films. The underlying mechanism for the significant iron reduction has remained unclear and is investigated in this work. Secondary ion mass spectrometry (SIMS) depth profiling of iron is performed on annealed iron-contaminated single-crystalline silicon wafers passivated with PECVD silicon nitride films. SIMS measurements reveal a high concentration of iron uniformly distributed in the annealed silicon nitride films. This accumulation of iron in the silicon nitride film matches the interstitial iron loss in the silicon bulk. This finding conclusively shows that the interstitial iron is gettered by the silicon nitride films during annealing over a wide temperature range from 250 °C to 900 °C, via a segregation gettering effect. Further experimental evidence is presented to support this finding. Deep-level transient spectroscopy analysis shows that no new electrically active defects are formed in the silicon bulk after annealing iron-containing silicon with silicon nitride films, confirming that the interstitial iron loss is not due to a change in the chemical structure of iron related defects in the silicon bulk. In addition, once the annealed silicon nitride films are removed, subsequent high temperature processes do not result in any reappearance of iron. Finally, the experimentally measured iron decay kinetics are shown to agree with a model of iron diffusion to the surface gettering sites, indicating a diffusion-limited iron gettering process for temperatures below 700 °C. The gettering process is found to become reaction-limited at higher temperatures.

  15. Wafer-level fabrication of nanocone forests by plasma repolymerization technique for surface-enhanced Raman scattering devices

    NASA Astrophysics Data System (ADS)

    Mao, Haiyang; Huang, Chengjun; Wu, Wengang; Xue, Mei; Yang, Yudong; Xiong, Jijun; Ming, Anjie; Wang, Weibing

    2017-02-01

    This work presents a novel type of surface-enhanced Raman scattering (SERS) devices based on nanocone forests. The nanocone forests are fabricated by using a plasma repolymerization technique, which is a simple and parallel approach that has high reproducibility in wafer-level fabrication. The nanocone forest-based SERS devices exhibit an averaged enhancement factor at the order of 3 × 106, meanwhile, the relative standard deviation of Raman intensity over large areas is around 7%. These experimental results demonstrate great potential of the nanocone forest-based SERS devices in wide applications.

  16. In situ measurement of the ion incidence angle dependence of the ion-enhanced etching yield in plasma reactors

    SciTech Connect

    Belen, Rodolfo Jun; Gomez, Sergi; Kiehlbauch, Mark; Aydil, Eray S.

    2006-11-15

    The authors propose and demonstrate a technique to determine the ion incidence angle dependence of the ion-enhanced etching yield under realistic plasma conditions and in situ in an arbitrary plasma reactor. The technique is based on measuring the etch rate as a function of position along the walls of features that initially have nearly semicircular cross sections. These initial feature shapes can be easily obtained by wet or isotropic plasma etching of holes patterned through a mask. The etch rate as a function of distance along the feature profile provides the etching yield as a function of the ion incidence angle. The etch rates are measured by comparing digitized scanning electron micrograph cross sections of the features before and after plasma etching in gas mixtures of interest. The authors have applied this technique to measure the ion incidence angle dependence of the Si etching yield in HBr, Cl{sub 2}, SF{sub 6}, and NF{sub 3} plasmas and binary mixtures of SF{sub 6} and NF{sub 3} with O{sub 2}. Advantages and limitations of this method are also discussed.

  17. Surface modification of polyester fabrics by atmospheric-pressure air/He plasma for color strength and adhesion enhancement

    NASA Astrophysics Data System (ADS)

    Zhang, Chunming; Zhao, Meihua; Wang, Libing; Qu, Lijun; Men, Yajing

    2017-04-01

    Surface properties of water-based pigmented inks for ink-jet printed polyester fabrics were modified with atmospheric-pressure air/He plasma to improve the color strength and pigment adhesion of the treated surfaces. The influence of various parameters, including the surface morphology, chemical compositions, surface energy and dynamic contact angles of the control and plasma treated samples was studied. Color strength and edge definition were used to evaluate the ink-jet printing performance of fabrics. The change in pigment adhesion to polyester fibers was analyzed by SEM (scanning electron microscopy). AFM (Atomic force microscope) and XPS (X-ray photoelectron spectroscopy) analyses indicated the increase in surface roughness and the oxygen-containing polar groups(Cdbnd O, Csbnd OH and COOH) reinforced the fixation of pigments on the fiber surface. The result from this study suggested that the improved pigment color yield was clearly affected by alteration of pigment adhesion enhanced by plasma surface modification. Polyester fabrics exhibited better surface property and ink-jet printing performance after the air/He mixture plasma treatment comparing with those after air plasma treatment.

  18. Experimental test of instability enhanced collisional friction for determining ion loss in two ion species plasmas a)

    NASA Astrophysics Data System (ADS)

    Hershkowitz, N.; Yip, C.-S.; Severn, G. D.

    2011-05-01

    Recent experiments have shown that ions in weakly collisional plasmas containing two ion species of comparable densities approximately reach a common velocity at the sheath edge equal to the bulk plasma ion sound velocity. A recent theory [S. D. Baalrud, C. C. Hegna, and J. D. Callen, Phys. Rev. Lett. 103, 205002 (2009)] suggests that this is a consequence of collisional friction between the two ion species enhanced by the two stream instability. The theory finds that the difference in velocities at the sheath edge depends on the relative concentrations of the two ions. The difference in velocities is small, with both species approaching to the bulk sound velocity, when the concentrations are comparable, and is large, with each species reaching its own Bohm velocity, when the relative concentration differences are large. To test these findings, drift velocities of Ar and Xe ions were measured with laser-induced fluorescence in Ar-Xe and He-Xe plasmas and combined with ion acoustic wave and plasma potential data. In addition, electron temperature was varied by a Maxwell demon [K. R. MacKenzie et al., App. Phys. Lett. 18, 529 (1971)]. The predictions were found to be in excellent agreement with the experimental data. The generalized Bohm criterion in two ion species plasmas is also verified in a wider variety of relative ion concentrations.

  19. Procollagen C-Proteinase Enhancer 1 (PCPE-1) as a Plasma Marker of Muscle and Liver Fibrosis in Mice

    PubMed Central

    Hassoun, Eyal; Safrin, Mary; Ziv, Hana; Pri-Chen, Sarah; Kessler, Efrat

    2016-01-01

    Current non-invasive diagnostic methods of fibrosis are limited in their ability to identify early and intermediate stages of fibrosis and assess the efficacy of therapy. New biomarkers of fibrosis are therefore constantly sought for, leading us to evaluate procollagen C-proteinase enhancer 1 (PCPE-1), a fibrosis-related extracellular matrix glycoprotein, as a plasma marker of fibrosis. A sandwich ELISA that permitted accurate measurements of PCPE-1 concentrations in mouse plasma was established. Tissue fibrosis was assessed using histochemical, immunofluorescence, and immunoblotting analyses for type I collagen and PCPE-1. The normal plasma concentration of PCPE-1 in 6 weeks to 4 months old mice was ~200 ng/ml (189.5 ± 11.3 to 206.8 ± 13.8 ng/ml). PCPE-1 plasma concentrations in four and 8.5 months old mdx mice displaying fibrotic diaphragms increased 27 and 40% respectively relatively to age-matched control mice, an increase comparable to that of the N-propeptide of procollagen type III (PIIINP), a known blood marker of fibrosis. PCPE-1 plasma levels in mice with CCl4-induced liver fibrosis increased 34 to 50% relatively to respective controls and reflected the severity of the disease, namely increased gradually during the progression of fibrosis and went down to basal levels during recovery, in parallel to changes in the liver content of collagen I and PCPE-1. The results favor PCPE-1 as a potential new clinically valuable fibrosis biomarker. PMID:27458976

  20. A Pilot Study of the Effectiveness of Augmented Reality to Enhance the Use of Remote Labs in Electrical Engineering Education

    NASA Astrophysics Data System (ADS)

    Mejías Borrero, A.; Andújar Márquez, J. M.

    2012-10-01

    Lab practices are an essential part of teaching in Engineering. However, traditional laboratory lessons developed in classroom labs (CL) must be adapted to teaching and learning strategies that go far beyond the common concept of e-learning, in the sense that completely virtualized distance education disconnects teachers and students from the real world, which can generate specific problems in laboratory classes. Current proposals of virtual labs (VL) and remote labs (RL) do not either cover new needs properly or contribute remarkable improvement to traditional labs—except that they favor distance training. Therefore, online teaching and learning in lab practices demand a further step beyond current VL and RL. This paper poses a new reality and new teaching/learning concepts in the field of lab practices in engineering. The developed augmented reality-based lab system (augmented remote lab, ARL) enables teachers and students to work remotely (Internet/intranet) in current CL, including virtual elements which interact with real ones. An educational experience was conducted to assess the developed ARL with the participation of a group of 10 teachers and another group of 20 students. Both groups have completed lab practices of the contents in the subjects Digital Systems and Robotics and Industrial Automation, which belong to the second year of the new degree in Electronic Engineering (adapted to the European Space for Higher Education). The labs were carried out by means of three different possibilities: CL, VL and ARL. After completion, both groups were asked to fill in some questionnaires aimed at measuring the improvement contributed by ARL relative to CL and VL. Except in some specific questions, the opinion of teachers and students was rather similar and positive regarding the use and possibilities of ARL. Although the results are still preliminary and need further study, seems to conclude that ARL remarkably improves the possibilities of current VL and RL

  1. Selective delipidation of plasma HDL enhances reverse cholesterol transport in vivo.

    PubMed

    Sacks, Frank M; Rudel, Lawrence L; Conner, Adam; Akeefe, Hassibullah; Kostner, Gerhard; Baki, Talal; Rothblat, George; de la Llera-Moya, Margarita; Asztalos, Bela; Perlman, Timothy; Zheng, Chunyu; Alaupovic, Petar; Maltais, Jo-Ann B; Brewer, H Bryan

    2009-05-01

    Uptake of cholesterol from peripheral cells by nascent small HDL circulating in plasma is necessary to prevent atherosclerosis. This process, termed reverse cholesterol transport, produces larger cholesterol-rich HDL that transfers its cholesterol to the liver facilitating excretion. Most HDL in plasma is cholesterol-rich. We demonstrate that treating plasma with a novel selective delipidation procedure converts large to small HDL [HDL-selectively delipidated (HDL-sdl)]. HDL-sdl contains several cholesterol-depleted species resembling small alpha, prebeta-1, and other prebeta forms. Selective delipidation markedly increases efficacy of plasma to stimulate ABCA1-mediated cholesterol transfer from monocytic cells to HDL. Plasma from African Green monkeys underwent selective HDL delipidation. The delipidated plasma was reinfused into five monkeys. Prebeta-1-like HDL had a plasma residence time of 8 +/- 6 h and was converted entirely to large alpha-HDL having residence times of 13-14 h. Small alpha-HDL was converted entirely to large alpha-HDL. These findings suggest that selective HDL delipidation activates reverse cholesterol transport, in vivo and in vitro. Treatment with delipidated plasma tended to reduce diet-induced aortic atherosclerosis in monkeys measured by intravascular ultrasound. These findings link the conversion of small to large HDL, in vivo, to improvement in atherosclerosis.

  2. [Research on enhanced photocatalytic degradation of medical PVC by plasma-initiated free radicals].

    PubMed

    Li, Xiao-jing; Qiao, Guan-jun; Chen, Jie-rong

    2007-05-01

    Effects of plasma-initiated free radicals on photocatalytic degradation of medical PVC with anatase TiO2 were studied. Surface properties of PVC were characterized by the contact angle, surface tension, X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR). The results indicate that the surface free energy and wettability of plasma-treated PVC increase greatly. The contact angles of distilled water, glycerin and dihydroxyethylsulfide for the plasma-treated PVC decrease. ESR reveals radicals on the surface of the plasma-treated PVC film nearly increase ten times. Moreover, the photodegradation of the PVC-TiO2 was compared with that of plasma-treated PVC-TiO2 through performing weight loss monitoring, scanning electron microscopic (SEM) analysis. Weight-loss rate of the plasma-treated PVC-TiO2 increases 27.4% in comparison with that of PVC-TiO2 under UV irradiation for 60 hours. SEM of the plasma-treated PVC-TiO2 film shows a lot of crack on the surface after photodegradation. Plasma treatments aggravate the photocatalytic degradation of medical PVC.

  3. Self-catalysis by aminosilanes and strong surface oxidation by O2 plasma in plasma-enhanced atomic layer deposition of high-quality SiO2.

    PubMed

    Fang, Guo-Yong; Xu, Li-Na; Cao, Yan-Qiang; Wang, Lai-Guo; Wu, Di; Li, Ai-Dong

    2015-01-25

    Plasma-enhanced atomic layer deposition (PE-ALD) has been applied to prepare high-quality ultrathin films for microelectronics, catalysis, and energy applications. The possible pathways for SiO2 PE-ALD using aminosilanes and O2 plasma have been investigated by density functional theory calculations. The silane half-reaction between SiH4 and surface -OH is very difficult and requires a high activation free energy of 57.8 kcal mol(-1). The introduction of an aminosilane, such as BDMAS, can reduce the activation free energy to 11.0 kcal mol(-1) and the aminosilane plays the role of a self-catalyst in Si-O formation through the relevant half-reaction. Among the various species generated in O2 plasma, (3)O2 is inactive towards surface silane groups, similar to ordinary oxygen gas. The other three species, (1)O2, (1)O, and (3)O, can strongly oxidize surface silane groups through one-step or stepwise pathways. In the (3)O pathway, the triplet must be converted into the singlet and follow the (1)O pathway. Meanwhile, both (1)O and (3)O can decay to (1)O2 and enter into the relevant oxidation pathway. The concept of self-catalysis of aminosilanes may be invoked to design and prepare more effective Si precursors for SiO2 ALD. At the same time, the mechanism of strong surface oxidation by O2 plasma may be exploited in the PE-ALD preparation of other oxides, such as Al2O3, HfO2, ZrO2, and TiO2.

  4. Interplanetary Field Enhancements: The Interaction between Solar Wind and Interplanetary Dusty Plasma Released by Interplanetary Collisions

    NASA Astrophysics Data System (ADS)

    Lai, Hairong

    Interplanetary field enhancements (IFEs) are unique large-scale structures in the solar wind. During IFEs, the magnetic-field strength is significantly enhanced with little perturbation in the solar-wind plasma. Early studies showed that IFEs move at nearly the solar-wind speed and some IFEs detected at 0.72AU by Pioneer Venus Orbiter (PVO) are associated with material co-orbiting with asteroid Oljato. To explain the observed IFE features, we develop and test an IFE formation hypothesis: IFEs result from interactions between the solar wind and clouds of nanoscale charged dust particles released in interplanetary collisions. This hypothesis predicts that the magnetic field drapes and the solar wind slows down in the upstream. Meanwhile the observed IFE occurrence rate should be comparable with the detectable interplanetary collision rate. Based on this hypothesis, we can use the IFE occurrence to determine the spatial distribution and temporal variation of interplanetary objects which produce IFEs. To test the hypothesis, we perform a systematic survey of IFEs in the magnetic-field data from many spacecraft. Our datasets cover from 1970s to present and from inner than 0.3AU to outer than 5 AU. In total, more than 470 IFEs are identified and their occurrences show clustering features in both space and time. We use multi-spacecraft simultaneous observations to reconstruct the magnetic-field geometry and find that the magnetic field drapes in the upstream region. The results of a superposed epoch study show that the solar wind slows down in the upstream and there is a plasma depletion region near the IFE centers. In addition, the solar-wind slowdown and plasma depletion feature are more significant in larger IFEs. The mass contained in IFEs can be estimated by balancing the solar-wind pressure force exerted on the IFEs against the solar gravity. The solar-wind slowdown resultant from the estimated mass is consistent with the result in superposed epoch study. The

  5. Enhancement of Biocompatibility on Bioactive Titanium Surface by Low-Temperature Plasma Treatment

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Cheng; Cheng, Hsin-Chung; Huang, Chiung-Fang; Lin, Che-Tong; Lee, Sheng-Yang; Chen, Chin-Sung; Ou, Keng-Liang

    2005-12-01

    The surface of implantable biomaterials directly contacts the host tissue and is critical in determining biocompatibility. To improve implant integration, interfacial reactions must be controlled to minimize nonspecific adsorption of proteins, and tissue-healing phenomena can be controlled. The purpose of this study was to develop a new method of functionalizing titanium surfaces by plasma treatment. The covalent immobilization of bioactive organic molecules and the bioactivities in vitro were assessed by transmission electron microscopy (TEM), atomic force spectroscopy (AFM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay as indices of cellular cytotoxicity. Argon plasma removed all of the adsorbed contaminants and impurities. Plasma-cleaned titanium surfaces showed better bioactive performances than untreated titanium surfaces. The analytical results reveal that plasma-cleaned titanium surfaces provide a clean and reproducible starting condition for further plasma treatments to create well-controlled surface layers. Allylamine was ionized by plasma treatment, and acted as a medium to link albumin. Cells demonstrated a good spread, and a wide attachment was attained on the Albu-Ti plate. Cell attachment and growth were shown to be influenced by the surface properties. The plasma treatment process plays an important role in facilitating tissue healing. This process not only provides a clean titanium surface, but also leads to surface amination on plasma-treated titanium surfaces. Surface cleaning by ion bombardment and surface modification by plasma polymerization are believed to remove contamination on titanium surfaces and thus promote tissue healing.

  6. Enhancement of liquid treatment efficiency by microwave plasma under flow-induced reduced pressure

    NASA Astrophysics Data System (ADS)

    Ito, Michiko; Takahashi, Tomohiro; Takitou, Sho; Takashima, Seigo; Nomura, Norio; Kitagawa, Tominori; Toyoda, Hirotaka

    2017-02-01

    A new microwave plasma device system for in-line solution treatment is developed. In this system, the Venturi effect for pressure reduction is utilized for stable and effective plasma production. The decomposition of phenol solution is tested to verify the efficiency of an in-line plasma treatment system, and such a treatment system is confirmed to have a higher decomposition efficiency than our previously developed batch-type treatment system. Increases in phenol decomposition speed and decomposition energy efficiency with increasing solution flow rate are observed, which suggests the suppression of OH radical recombination and the utilization of OH radicals under flowing solution conditions.

  7. Enhancement mechanism of H- production and suitable configurations for materials processing in a magnetized sheet plasma

    NASA Astrophysics Data System (ADS)

    Ramos, Henry J.; Villamayor, Michelle Marie S.; Mella, Aubrey Faith M.; Salamania, Janella Mae R.; Villanueva, Matthew Bryan P.; Viloan, Rommel Paulo B.

    2014-08-01

    A magnetized sheet plasma ion source was developed for steady state high density plasma with strong density and high temperature gradients. This feature provides efficient formation of negative hydrogen (H-) ions over a wide beam extraction area through the electron volume process. A hexapole confinement at the cathode, addition of argon and magnesium seeding led to the increase of H- yield. The device configuration is suitable for plasma based materials processing namely, synthesis of TiN, SiH, SnO2, and the formation of advanced MAX phase materials Ti2AlC, Ti2CdC and NbAlC.

  8. Enhanced filament ablation of metals based on plasma grating in air

    SciTech Connect

    Wang, Di; Liu, Fengjiang; Ding, Liangen; Yuan, Shuai; Zeng, Heping

    2015-09-15

    We demonstrate efficient ablation of metals with filamentary plasma grating generated by two intense blue femtosecond filaments and a third focused infrared pulse. This scheme leads to significant promotion of ablation efficiency on metal targets in air in comparison with single infrared or blue filament with equal pulse energy. The reason is that the blue plasma grating firstly provides stronger intensity and a higher density of background electrons, then the delayed infrared pulse accelerates local electrons inside the plasma grating. These two processes finally results in robustly increased electron density and highly ionized metallic atoms.

  9. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    SciTech Connect

    Chen, Anmin; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Ding, Dajun; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing

    2013-10-15

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  10. Energy enhancement of proton acceleration in combinational radiation pressure and bubble by optimizing plasma density

    SciTech Connect

    Bake, Muhammad Ali; Xie Baisong; Shan Zhang; Hong Xueren; Wang Hongyu

    2012-08-15

    The combinational laser radiation pressure and plasma bubble fields to accelerate protons are researched through theoretical analysis and numerical simulations. The dephasing length of the accelerated protons bunch in the front of the bubble and the density gradient effect of background plasma on the accelerating phase are analyzed in detail theoretically. The radiation damping effect on the accelerated protons energy is also considered. And it is demonstrated by two-dimensional particle-in-cell simulations that the protons bunch energy can be increased by using the background plasma with negative density gradient. However, radiation damping makes the maximal energy of the accelerated protons a little reduction.

  11. Label-Free Optical Detection of Acute Myocardial Infarction Based on Blood Plasma Surface-Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Y. X.; Chen, M. W.; Lin, J. Y.; Lai, W. Q.; Huang, W.; Chen, H. Y.; Weng, G. X.

    2016-11-01

    This study is intended to explore the potential of silver (Ag) nanoparticle-based plasma surface-enhanced Raman spectroscopy (SERS) for providing a rapid and simple "Yes/No" assessment to detect acute myocardial infarction (AMI). A simple, rapid, and accurate method of diagnosing AMI is critical to reduce mortality and improve prognosis. Techniques such as electrocardiography examination and use of cardiac troponins have not yet met the current clinical need. Therefore, alternative approaches need to be developed. Plasma samples from 32 patients with AMI and 32 healthy control (Clt) subjects were assessed. Multivariate statistical techniques, including principal component (PC) analysis and linear discriminant analysis (PCA-LDA), were employed to develop a diagnostic algorithm for differentiating between patients with AMI and Clt subjects. Furthermore, the receiver operating characteristic was tested to evaluate the performance of the PCA-LDA algorithm for AMI detection. Each plasma sample was mixed with an equal volume of Ag colloidal solution, and the SERS measurement of each plasma sample was performed. The plasma SERS spectrum showed much stronger and sharper peaks compared with the normal Raman spectrum. Tentative assignments of Raman spectroscopy bands showed specific biomolecular (e.g., proteins, adenosine, adenine, and uric acid) changes. PC analysis and LDA were employed to discriminate patients with AMI from Clt subjects, yielding a sensitivity of 87.5% and a specificity of 93.8%. The findings of this study suggest that plasma SERS has a great potential for improving AMI in the future, and this will certainly reduce the difficulty, time to draw blood, and patients' pain to a great extent.

  12. Applications of Satellite Remote Sensing Products to Enhance and Evaluate the AIRPACT Regional Air Quality Modeling System

    NASA Astrophysics Data System (ADS)

    Herron-Thorpe, F. L.; Mount, G. H.; Emmons, L. K.; Lamb, B. K.; Jaffe, D. A.; Wigder, N. L.; Chung, S. H.; Zhang, R.; Woelfle, M.; Vaughan, J. K.; Leung, F. T.

    2013-12-01

    The WSU AIRPACT air quality modeling system for the Pacific Northwest forecasts hourly levels of aerosols and atmospheric trace gases for use in determining potential health and ecosystem impacts by air quality managers. AIRPACT uses the WRF/SMOKE/CMAQ modeling framework, derives dynamic boundary conditions from MOZART-4 forecast simulations with assimilated MOPITT CO, and uses the BlueSky framework to derive fire emissions. A suite of surface measurements and satellite-based remote sensing data products across the AIRPACT domain are used to evaluate and improve model performance. Specific investigations include anthropogenic emissions, wildfire simulations, and the effects of long-range transport on surface ozone. In this work we synthesize results for multiple comparisons of AIRPACT with satellite products such as IASI ammonia, AIRS carbon monoxide, MODIS AOD, OMI tropospheric ozone and nitrogen dioxide, and MISR plume height. Features and benefits of the newest version of AIRPACT's web-interface are also presented.

  13. Enhancement of RNA Polymerase Activity by a Factor Released by Auxin from Plasma Membrane*

    PubMed Central

    Hardin, James W.; Cherry, Joe H.; Morré, D. James; Lembi, Carole A.

    1972-01-01

    Using recently developed techniques for solubilization of RNA polymerase from soybean chromatin and isolation of plasma membrane fractions from plants we can show the presence of a transcriptional factor specifically released from the membranes by auxin, 2,4-dichlorophenoxyacetic acid. The nonauxin, 3,5-dichlorophenoxyacetic acid, does not release the factor, but subsequent exposure of the membranes to auxin results in its release. Factor activity could not be demonstrated in fractions devoid of plasma membranes. The presence of a regulatory factor for RNA polymerase associated with plant plasma membrane and specifically released by auxin provides a mechanism whereby both rapid growth responses and delayed nuclear changes could be derived from a common auxin receptor site associated with plasma membrane. Images PMID:4508307

  14. Enhancing cold atmospheric plasma treatment of cancer cells by static magnetic field.

    PubMed

    Cheng, Xiaoqian; Rajjoub, Kenan; Shashurin, Alexey; Yan, Dayun; Sherman, Jonathan H; Bian, Ka; Murad, Ferid; Keidar, Michael

    2017-01-01

    It has been reported since late 1970 that magnetic field interacts strongly with biological systems. Cold atmospheric plasma (CAP) has also been widely studied over the past few decades in physics, biology, and medicine. In this study, we propose a novel idea to combine static magnetic field (SMF) with CAP as a tool for cancer therapy. Breast cancer cells and wild type fibroblasts were cultured in 96-well plates and treated by CAP with or without SMF. Breast cancer cells MDA-MB-231 showed a significant decrease in viability after direct plasma treatment with SMF (compared to only plasma treatment). In addition, cancer cells treated by the CAP-SMF-activated medium (indirect treatment) also showed viability decrease but was slightly weaker than the direct plasma-SMF treatment. By integrating the use of SMF and CAP, we were able to discover their advantages that have yet to be utilized. Bioelectromagnetics. 38:53-62, 2017. © 2016 Wiley Periodicals, Inc.

  15. Plasma and ion beam enhanced chemical vapour deposition of diamond and diamond-like carbon

    NASA Astrophysics Data System (ADS)

    Tang, Yongji

    WC-Co cutting tools are widely used in the machining industry. The application of diamond coatings on the surfaces of the tools would prolong the cutting lifetime and improves the manufacturing efficiency. However, direct chemical vapor deposition (CVD) of diamond coatings on WC-Co suffer from severe premature adhesion failure due to interfacial graphitization induced by the binder phase Co. In this research, a combination of hydrochloric acid (HCl) and hydrogen (H2) plasma pretreatments and a novel double interlayer of carbide forming element (CFE)/Al were developed to enhance diamond nucleation and adhesion. The results showed that both the pretreatments and interlayers were effective in forming continuous and adhesive nanocrystalline diamond coatings. The method is a promising replacement of the hazardous Murakami's regent currently used in WC-Co pretreatment with a more environmental friendly approach. Apart from coatings, diamond can be fabricated into other forms of nanostructures, such as nanotips. In this work, it was demonstrated that oriented diamond nanotip arrays can be fabricated by ion beam etching of as-grown CVD diamond. The orientation of diamond nanotips can be controlled by adjusting the direction of incident ion beam. This method overcomes the limits of other techniques in producing nanotip arrays on large areas with controlled orientation. Oriented diamond nano-tip arrays have been used to produce anisotropic frictional surface, which is successfully used in ultra-precision positioning systems. Diamond-like carbon (DLC) has many properties comparable to diamond. In this thesis, the preparation of alpha-C:H thin films by end-Hall (EH) ion source and the effects of ion energy and nitrogen doping on the microstructure and mechanical properties of the as-deposited thin films were investigated. The results have demonstrated that smooth and uniform alpha-C:H and alpha-C:H:N films with large area and reasonably high hardness and Young's modulus can be

  16. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2001-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime (about 40 ps), high frequency (about 5G hz), high power bursts of low-duty factor microwaves sufficient to generate a dielectric barrier discharge and passing a gas to treated through the discharge so as to cause dissociative reduction of the exhaust gases. The invention also includes a reactor for generating the non-thermal plasma.

  17. One manufacturer's approach to using nucleic acid testing for enhanced plasma-product safety.

    PubMed

    Liss, A

    2001-04-01

    Source plasma must contain the lowest possible pathogen bioburden so as to minimize the stress placed on subsequent viral reduction steps. Differences exist between European and US criteria for developing assays used to detect these viral pathogens. The approach used by 1 plasma-product manufacturer is described here. By adding polymerase chain reaction (PCR) detection techniques for various viral pathogens (including human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus) to the plasma screening process, this manufacturer maximizes the use of cutting-edge technology for plasma product safety while satisfying both European and US criteria and requirements for this process. The protocol begins with maxipool testing and eventually identifies any specific donor plasma that might be positive in the contributing minipools. The goal is to identify reactive donors for possible periodic monitoring and to use only nonreactive donations to continue producing a particular plasma product. Controversy surrounding the use of PCR to screen emerging organisms of questionable pathogenicity or known organisms that are of minimal pathogenicity for most of the population is also discussed, and possible solutions to this debate are provided.

  18. Enhanced thermal stability of carbon nanotubes by plasma surface modification in Al2O3 composites

    NASA Astrophysics Data System (ADS)

    Cho, Hoonsung; Shi, Donglu; Guo, Yan; Lian, Jie; Ren, Zhifeng; Poudel, Bed; Song, Yi; Abot, Jandro L.; Singh, Dileep; Routbort, Jules; Wang, Lumin; Ewing, Rodney C.

    2008-10-01

    A plasma polymerization method was employed to deposit an ultrathin pyrrole film of 3 nm onto the surfaces of single wall carbon nanotubes (SWCNTs) and Al2O3 nanoparticles for developing high-strength nanocomposites. The surfaces of plasma coated SWCNTs and Al2O3 nanoparticles were studied by high resolution transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectroscopy. After sintering the SWCNTs-Al2O3 composites at different temperatures (maximum of 1200 °C), the thermal stability of plasma-coated SWCNTs was significantly increased, compared to their uncoated counterparts. After hot-press sintering, the SWCNTs without plasma coating were essentially decomposed into amorphous clusters in the composites, leading to degraded mechanical properties. However, under the same sintering conditions, the plasma surface modified SWCNTs were well preserved and distributed in the composite matrices. The effects of plasma surface coating on the thermal stability of SWCNTs and mechanical behavior of the nanocomposites are discussed.

  19. Surface-enhanced Raman spectroscopy of blood plasma and serum using Ag and Au nanoparticles: a systematic study.

    PubMed

    Bonifacio, Alois; Dalla Marta, Silvia; Spizzo, Riccardo; Cervo, Silvia; Steffan, Agostino; Colombatti, Alfonso; Sergo, Valter

    2014-04-01

    Surface-enhanced Raman spectroscopy (SERS) is a good candidate for the development of fast and easy-to-use diagnostic tools, possibly used on biofluids in point-of-care or screening tests. In particular, label-free SERS spectra of blood serum and plasma, two biofluids widely used in diagnostics, could be used as a metabolic fingerprinting approach for biomarker discovery. This study aims at a systematic evaluation of SERS spectra of blood serum and plasma, using various Ag and Au aqueous colloids, as SERS substrates, in combination with three excitation lasers of different wavelengths, ranging from the visible to the near-infrared. The analysis of the SERS spectra collected from 20 healthy subjects under a variety of experimental conditions revealed that intense and repeatable spectra are quickly obtained only if proteins are filtered out from samples, and an excitation in the near-infrared is used in combination with Ag colloids. Moreover, common plasma anticoagulants such as EDTA and citrate are found to interfere with SERS spectra; accordingly, filtered serum or heparin plasma are the samples of choice, having identical SERS spectra. Most bands observed in SERS spectra of these biofluids are assigned to uric acid, a metabolite whose blood concentration depends on factors such as sex, age, therapeutic treatments, and various pathological conditions, suggesting that, even when the right experimental conditions are chosen, great care must be taken in designing studies with the purpose of developing diagnostic tests.

  20. Steady-shear-enhanced microdiffusion with multiple time scales of confined, mesoscopic, two-dimensional dusty-plasma liquids.

    PubMed

    Io, Chong-Wai; I, Lin

    2009-09-01

    We experimentally investigate the multitime scale diffusion and the spatiotemporal behaviors of the degrees of enhancement for the longitudinal and the transverse diffusions in a confined mesoscopic quasi-two-dimensional dusty-plasma liquid sheared by two parallel counterpropagating laser beams. The steady external drive directly enhances the longitudinal cooperative hopping, associated with the shear bands that have high shear rate near boundaries. It drastically excites the slow hopping modes to high fluctuation level in the outer band region, accompanied by the enhanced superdiffusion. Through cascaded many-body interaction, the excitation flows from the outer region toward the center region, from the longitudinal modes to the transverse mode, and from the slow hopping modes to the fast caging modes, which are in better contact with the thermal bath. It causes the weaker enhancement of fluctuation level, and diffusion for the center region and the fast modes. The boundary confinement further breaks the system symmetry and enhances anisotropy. It has much stronger effect on the suppression of the transverse hopping modes than the longitudinal hopping mode. The degrees of enhancement of the fluctuations by the shear stress are highly anisotropic for the large amplitude slow modes, especially in the outer region but are more isotropic in the inner band.

  1. The properties of plasma-enhanced atomic layer deposition (ALD) ZnO thin films and comparison with thermal ALD

    NASA Astrophysics Data System (ADS)

    Kim, Doyoung; Kang, Hyemin; Kim, Jae-Min; Kim, Hyungjun

    2011-02-01

    Zinc oxide (ZnO) thin films were prepared by plasma-enhanced atomic layer deposition (PE-ALD) using oxygen plasma as a reactant and the properties were compared with those of thermal atomic layer deposition (TH-ALD) ZnO thin films. While hexagonal wurzite phase with preferential (0 0 2) orientation was obtained for both cases, significant differences were observed in various aspects of film properties including resistivity values between these two techniques. Photoluminescence (PL) measurements have shown that high resistivity of PE-ALD ZnO thin films is due to the oxygen interstitials at low growth temperature of 200 °C, whose amount decreases with increasing growth temperature. Thin film transistors (TFT) using TH- and PE-ALD ZnO as an active layer were also fabricated and the device properties were evaluated comparatively.

  2. Sticking non-stick: Surface and Structure control of Diamond-like Carbon in Plasma Enhanced Chemical Vapour Deposition

    NASA Astrophysics Data System (ADS)

    Jones, B. J.; Nelson, N.

    2016-10-01

    This short review article explores the practical use of diamond-like carbon (DLC) produced by plasma enhanced chemical vapour deposition (PECVD). Using as an example issues relating to the DLC coating of a hand-held surgical device, we draw on previous works using atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, tensiometry and electron paramagnetic resonance. Utilising data from these techniques, we examine the surface structure, substrate-film interface and thin film microstructure, such as sp2/sp3 ratio (graphitic/diamond-like bonding ratio) and sp2 clustering. We explore the variations in parameters describing these characteristics, and relate these to the final device properties such as friction, wear resistance, and diffusion barrier integrity. The material and device characteristics are linked to the initial plasma and substrate conditions.

  3. Effects of plasma-enhanced chemical vapor deposition (PECVD) on the carrier lifetime of Al2O3 passivation stack

    NASA Astrophysics Data System (ADS)

    Cho, Kuk-Hyun; Cho, Young Joon; Chang, Hyo Sik; Kim, Kyung-Joong; Song, Hee Eun

    2015-09-01

    We investigated the effect on the minority carrier lifetime of atomic layer deposition (ALD) Al2O3 passivation by a plasma-enhanced chemical vapor deposition (PECVD) SiON layer in Si/Al2O3/SiON-passivated structure. The lifetime variation of the Al2O3/SiON stack layer was found to depend on both the plasma power and the deposition temperature during the PECVD SiON process and to show better thermal stability than the Al2O3/SiNx:H stack under the same deposition conditions. The lifetime after a high-temperature firing process was improved dramatically at the PECVD deposition temperature of 200 °C. Our results provide a significant clue to reason for the improvement of the passivation performance for passivated emitter and rear contact (PERC) silicon solar cells.

  4. Enhanced active aluminum content and thermal behaviour of nano-aluminum particles passivated during synthesis using thermal plasma route

    NASA Astrophysics Data System (ADS)

    Mathe, Vikas L.; Varma, Vijay; Raut, Suyog; Nandi, Amiya Kumar; Pant, Arti; Prasanth, Hima; Pandey, R. K.; Bhoraskar, Sudha V.; Das, Asoka K.

    2016-04-01

    Here, we report synthesis and in situ passivation of aluminum nanoparticles using thermal plasma reactor. Both air and palmitc acid passivation was carried out during the synthesis in the thermal plasma reactor. The passivated nanoparticles have been characterized for their structural and morphological properties using X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. In order to understand nature of passivation vibrational spectroscopic analysis have been carried out. The enhancement in active aluminum content and shelf life for a palmitic acid passivated nano-aluminum particles in comparison to the air passivated samples and commercially available nano Al powder (ALEX) has been observed. Thermo-gravimetric analysis was used to estimate active aluminum content of all the samples under investigation. In addition cerimetric back titration method was also used to estimate AAC and the shelf life of passivated aluminum particles. Structural, microstructural and thermogravomateric analysis of four year aged passivated sample also depicts effectiveness of palmitic acid passivation.

  5. Growing c-axis oriented aluminum nitride films by Plasma-Enhanced Atomic Layer Deposition at low temperatures

    NASA Astrophysics Data System (ADS)

    Tarala, V.; Ambartsumov, M.; Altakhov, A.; Martens, V.; Shevchenko, M.

    2016-12-01

    The possibility of using plasma enhanced atomic layer deposition method for growing heteroepitaxial oriented AlN films on Si (100) and sapphire (001) substrates at temperatures less than 300 °C was investigated. The resulting samples were studied by X-ray diffraction analysis and ellipsometry. It has been shown that, ceteris paribus, AlN films grown on sapphire substrates have higher crystallinity than the samples grown on silicon wafers. With duration of plasma exposure of more than 20 s and at a temperature of 300 °C synthesized heteroepitaxial film had refractive index equal to 2.03±0.03. The X-ray diffraction scans feature (002) and (004) reflections at 2Θ equal to 35.7° and 75.9°, which are characteristic of hexagonal polytype of AlN. For the best sample, (002) reflection had full width on the half maximum of 162±11″

  6. A remote GATA2 hematopoietic enhancer drives leukemogenesis in inv(3)(q21;q26) by activating EVI1 expression

    PubMed Central

    Yamazaki, Hiromi; Suzuki, Mikiko; Otsuki, Akihito; Shimizu, Ritsuko; Bresnick, Emery H.; Engel, James Douglas; Yamamoto, Masayuki

    2014-01-01

    SUMMARY Chromosomal inversion between 3q21 and 3q26 results in high-risk acute myeloid leukemia (AML). Here, we identified a mechanism whereby a GATA2 distal hematopoietic enhancer (G2DHE or −77-kb enhancer) is brought into close proximity to the EVI1 gene in inv(3)(q21;q26) inversions, leading to leukemogenesis. We examined the contribution of G2DHE to leukemogenesis by creating a bacterial artificial chromosome (BAC) transgenic model that recapitulates the inv(3)(q21;q26) allele. Transgenic mice harboring a linked BAC developed leukemia accompanied by EVI1 overexpression, neoplasia that was not detected in mice bearing the same transgene but missing the GATA2 enhancer. These results establish the mechanistic basis underlying the pathogenesis of a severe form of leukemia through aberrant expression of the EVI1 proto-oncogene. PMID:24703906

  7. Measurements of HF-enhanced plasma and ion lines at EISCAT with high-altitude resolution

    NASA Astrophysics Data System (ADS)

    Rietveld, M. T.; Isham, B.; Kohl, H.; La Hoz, C.; Hagfors, T.

    2000-04-01

    Measurements of plasma and ion lines induced during HF ionospheric interaction experiments have been made with the European Incoherent Scatter (EISCAT) facility at Troms[do] with sufficiently high-altitude resolution to compare with theories of Langmuir turbulence. Recent Langmuir turbulence models predict a change from broad structureless spectra to line or cascade spectra within a few hundred meters for VHF (224 MHz) observations assuming typical ionospheric density gradients. In a campaign in May 1994 we found VHF spectra that were grouped into two regions separated in altitude by ~2 km, with broad, unstructured plasma line spectra in the upper region and cascade type spectra in the lower region. The ion line channels showed detectable spectra mainly in the upper altitude region, which corresponds to that which had the broad plasma lines. The background ionospheric density profile showed an unusually low plasma density gradient near the HF reflection heights, thus allowing the two regions, which are normally so close together that one only sees a transition from one type of spectra to the other, to be clearly separated in height. Thus, in the high-latitude ionosphere there can, at times, be a simultaneous existence in spatially separate regions of cavitation (often referred to as strong turbulence) and cascading (normally associated with saturated parametric decay) as predicted by some simulations. Another new feature is a height variation in the plasma line cascades with the highest-order cascades strongest at the lowest heights, in accordance with expectations based on the parametric decay instability.

  8. Enhanced adherence of mouse fibroblast and vascular cells to plasma modified polyethylene.

    PubMed

    Reznickova, Alena; Novotna, Zdenka; Kolska, Zdenka; Kasalkova, Nikola Slepickova; Rimpelova, Silvie; Svorcik, Vaclav

    2015-01-01

    Since the last decade, tissue engineering has shown a sensational promise in providing more viable alternatives to surgical procedures for harvested tissues, implants and prostheses. Biomedical polymers, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE), were activated by Ar plasma discharge. Degradation of polymer chains was examined by determination of the thickness of ablated layer. The amount of an ablated polymer layer was measured by gravimetry. Contact angle, measured by goniometry, was studied as a function of plasma exposure and post-exposure aging times. Chemical structure of modified polymers was characterized by angle resolved X-ray photoelectron spectroscopy. Surface chemistry and polarity of the samples were investigated by electrokinetic analysis. Changes in surface morphology were followed using atomic force microscopy. Cytocompatibility of plasma activated polyethylene foils was studied using two distinct model cell lines; VSMCs (vascular smooth muscle cells) as a model for vascular graft testing and connective tissue cells L929 (mouse fibroblasts) approved for standardized material cytotoxicity testing. Specifically, the cell number, morphology, and metabolic activity of the adhered and proliferated cells on the polyethylene matrices were studied in vitro. It was found that the plasma treatment caused ablation of the polymers, resulting in dramatic changes in their surface morphology and roughness. ARXPS and electrokinetic measurements revealed oxidation of the polymer surface. It was found that plasma activation has a positive effect on the adhesion and proliferation of VSMCs and L929 cells.

  9. Growth of carbon nanofibers in plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Denysenko, Igor; Ostrikov, Kostya; Tam, Eugene

    2008-10-01

    A theoretical model describing the plasma-assisted growth of carbon nanofibers with metal catalyst particles on top is proposed. Using the model, the plasma-related effects on the nanofiber growth parameters such us the surface diffusion growth rate, the effective carbon flux to the catalyst surface, the characteristic residence time and diffusion length of carbon on the catalyst surface, and the surface coverages, have been studied. It has been found how these parameters depend on the catalyst surface temperature and ion and etching gas fluxes to the catalyst surface. The optimum conditions under which a low-temperature plasma environment can benefit the carbon nanofiber growth are formulated. It has been also found how the plasma environment affects the temperature distribution over the length of the carbon nanofibers. Conditions when the temperature of the catalyst nanoparticles is higher than the temperature of the substrate holder are determined. The results here are in a good agreement with the available experimental data on the carbon nanofiber growth and can be used for optimizing synthesis of nanoassemblies in low-temperature plasma-assisted nanofabrication.

  10. Experiments and PIC simulations on liquid crystal plasma mirrors for pulse contrast enhancement

    NASA Astrophysics Data System (ADS)

    Cochran, G. E.; Poole, P. L.; Krygier, A.; Foster, P. S.; Scott, G. G.; Wilson, L. A.; Bailey, J.; Bourgeois, N.; Hernandez-Gomez, C.; Heery, R.; Purcell, J.; Neely, D.; Rajeev, P. P.; Freeman, R. R.; Schumacher, D. W.

    2016-10-01

    High pulse contrast is crucial for performing many experiments on high intensity lasers in order to minimize modification of the target surface by pre-pulse. This is often achieved through the use of solid dielectric plasma mirrors which can limit laser shot rates. Liquid crystal films, originally developed as variable thickness ion acceleration targets, have been demonstrated as effective plasma mirrors for pulse cleaning, reaching peak reflectivities over 70%. These films were used as plasma mirrors in an ion acceleration experiment on the Scarlet laser and the resultant increase in peak proton energy and change in acceleration direction will be discussed. Also presented here are novel 2D3V, LSP particle-in-cell simulations of dielectric plasma mirror operation. By including multiphoton ionization and dimensionality corrections, an excellent match to experiment is obtained over 4 decades in intensity. Analysis of pulse shortening and plasma critical surface behavior in these simulations will be discussed. Formation of thin films at 1.5 Hz will also be presented. Performed with support from the DARPA PULSE program through AMRDEC, from NNSA, and from OSC.

  11. Essential telemedicine elements (tele-ments) for connecting the academic health center and remote community providers to enhance patient care.

    PubMed

    Meyer, Brett C; Clarke, Christopher A; Troke, Tana M; Friedman, Lawrence S

    2012-08-01

    The authors draw on their experience with the University of California, San Diego Medical Center's successful enterprise-level clinical telemedicine program to present a paradigm for other academic health centers (AHCs) that wish to develop such a program. They detail key telemedicine program elements, or "tele-ments," that they consider essential to the development of a centralized, structured telemedicine program and relevant to the development of smaller programs. These tele-ments include an overall organizational vision, a centralized telemedicine infrastructure, telemedicine-specific policies and procedures, medical record documentation, relationships between the AHC clinical hub and its remote (spoke) partners, identification of and training for specialty providers, a business plan based on service agreements and/or insurance billing, and licensure/privileging. They discuss the importance of delaying equipment purchases until a plan is in place for sustaining the telemedicine enterprise and of establishing measures to define success at the outset of program development. In addition, they detail the benefits and concerns associated with telemedicine, provide a comprehensive listing of the roles and responsibilities of providers and staff involved in all aspects of telemedicine, and share samples of their program's informed consent forms and workflow checklists. Their goal is to offer support and guidance to other AHCs entering the telemedicine arena, enabling them to replicate key elements of a successful, enterprise-wide telemedicine infrastructure.

  12. Plasma treated polyethylene grafted with adhesive molecules for enhanced adhesion and growth of fibroblasts.

    PubMed

    Rimpelová, Silvie; Kasálková, Nikola Slepičková; Slepička, Petr; Lemerová, Helena; Švorčík, Václav; Ruml, Tomáš

    2013-04-01

    The cell-material interface plays a crucial role in the interaction of cells with synthetic materials for biomedical use. The application of plasma for tailoring polymer surfaces is of abiding interest and holds a great promise in biomedicine. In this paper, we describe polyethylene (PE) surface tuning by Ar plasma irradiating and subsequent grafting of the chemically active PE surface with adhesive proteins or motives to support cell attachment. These simple modifications resulted in changed polymer surface hydrophilicity, roughness and morphology, which we thoroughly characterized. The effect of our modifications on adhesion and growth was tested in vitro using mouse embryonic fibroblasts (NIH 3T3 cell line). We demonstrate that the plasma treatment of PE had a positive effect on the adhesion, spreading, homogeneity of distribution and moderately on proliferation activity of NIH 3T3 cells. This effect was even more pronounced on PE coated with biomolecules.

  13. Plasma enhanced multistate storage capability of single ZnO nanowire based memory

    SciTech Connect

    Lai, Yunfeng Xin, Pucong; Cheng, Shuying; Yu, Jinling; Zheng, Qiao

    2015-01-19

    Multiple-state storage (MSS) is common for resistive random access memory, but the effects of plasma treatment on the MSS and the switching properties have been scarcely investigated. We have demonstrated a stable four-state storage capability of single zinc oxide nanowire (ZnO NW) treated by argon plasma. The electrical switching is attributed to the electron trapping and detrapping from the oxygen vacancies (V{sub o}s). The MSS relates to the electrical-thermal induced distribution of the V{sub o}s which determines electron transport behavior to show different resistance states. Additionally, programming (set and reset) voltages decrease with plasma treatment due to the thickness modulation of the interface barrier.

  14. Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

    SciTech Connect

    Jin Seo, Hyok; Hee Lee, Mi; Kwon, Byeong-Ju; Kim, Hye-Lee; Park, Jong-Chul; Jin Lee, Seung; Kim, Bong-Jin; Wang, Kang-Kyun; Kim, Yong-Rok

    2013-08-21

    Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH{sub 2} (399.70 eV) was increased significantly and –N=CH (400.80 eV) and –NH{sub 3}{sup +} (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

  15. Combining oxygen plasma treatment with anchorage of cationized gelatin for enhancing cell affinity of poly(lactide-co-glycolide).

    PubMed

    Shen, Hong; Hu, Xixue; Yang, Fei; Bei, Jianzhong; Wang, Shenguo

    2007-10-01

    Surface characteristics greatly influence attachment and growth of cells on biomaterials. Although polylactone-type biodegradable polymers have been widely used as scaffold materials for tissue engineering, lack of cell recognition sites, poor hydrophilicity and low surface energy lead to a bad cell affinity of the polymers, which limit the usage of polymers as scaffolds in tissue engineering. In the present study, surface of poly (L-lactide-co-glycolide) (PLGA) was modified by a method of combining oxygen plasma treatment with anchorage of cationized gelatin. Modification effect of the method was compared with other methods of oxygen plasma treatment, cationized gelatin or gelatin coating and combining oxygen plasma treatment with anchorage of gelatin. The change of surface property was compared by contact angles, surface energy, X-ray photoelectron spectra (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) measurement. The optimum oxygen pretreatment time determined by surface energy was 10 min when the power was 50 W and the oxygen pressure was 20 Pa. Analysis of the stability of gelatin and cationized gelatin anchored on PLGA by XPS, ATR-FTIR, contact angles and surface energy measurement indicated the cationized gelatin was more stable than gelatin. The result using mouse NIH 3T3 fibroblasts as model cells to evaluate cell affinity in vitro showed the cationized gelatin-anchored PLGA (OCG-PLGA) was more favorable for cell attachment and growth than oxygen plasma treated PLGA (O-PLGA) and gelatin-anchored PLGA (OG-PLGA). Moreover cell affinity of OCG-PLGA could match that of collagen-anchored PLGA (AC-PLGA). So the surface modification method combining oxygen plasma treatment with anchorage of cationized gelatin provides a universally effective way to enhance cell affinity of polylactone-type biodegradable polymers.

  16. Enhanced Detection of Low-Abundance Human Plasma Proteins by Integrating Polyethylene Glycol Fractionation and Immunoaffinity Depletion

    PubMed Central

    Liu, Haipeng; Yu, Jia; Qiao, Rui; Zhou, Mi; Yang, Yongtao; Zhou, Jian; Xie, Peng

    2016-01-01

    The enormous depth complexity of the human plasma proteome poses a significant challenge for current mass spectrometry-based proteomic technologies in terms of detecting low-level proteins in plasma, which is essential for successful biomarker discovery efforts. Typically, a single-step analytical approach cannot reduce this intrinsic complexity. Current simplex immunodepletion techniques offer limited capacity for detecting low-abundance proteins, and integrated strategies are thus desirable. In this respect, we developed an improved strategy for analyzing the human plasma proteome by integrating polyethylene glycol (PEG) fractionation with immunoaffinity depletion. PEG fractionation of plasma proteins is simple, rapid, efficient, and compatible with a downstream immunodepletion step. Compared with immunodepletion alone, our integrated strategy substantially improved the proteome coverage afforded by PEG fractionation. Coupling this new protocol with liquid chromatography-tandem mass spectrometry, 135 proteins with reported normal concentrations below 100 ng/mL were confidently identified as common low-abundance proteins. A side-by-side comparison indicated that our integrated strategy was increased by average 43.0% in the identification rate of low-abundance proteins, relying on an average 65.8% increase of the corresponding unique peptides. Further investigation demonstrated that this combined strategy could effectively alleviate the signal-suppressive effects of the major high-abundance proteins by affinity depletion, especially with moderate-abundance proteins after incorporating PEG fractionation, thereby greatly enhancing the detection of low-abundance proteins. In sum, the newly developed strategy of incorporating PEG fractionation to immunodepletion methods can potentially aid in the discovery of plasma biomarkers of therapeutic and clinical interest. PMID:27832179

  17. Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

    NASA Astrophysics Data System (ADS)

    Jin Seo, Hyok; Hee Lee, Mi; Kwon, Byeong-Ju; Kim, Hye-Lee; Jin Lee, Seung; Kim, Bong-Jin; Wang, Kang-Kyun; Kim, Yong-Rok; Park, Jong-Chul

    2013-08-01

    Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH2 (399.70 eV) was increased significantly and -N=CH (400.80 eV) and -NH3+ (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

  18. Low-temperature preparation of GaN-SiO2 interfaces with low defect density. II. Remote plasma-assisted oxidation of GaN and nitrogen incorporation

    NASA Astrophysics Data System (ADS)

    Bae, Choelhwyi; Lucovsky, Gerald

    2004-11-01

    Low-temperature remote plasma-assisted oxidation and nitridation processes for interface formation and passivation have been extended from Si and SiC to GaN. The initial oxidation kinetics and chemical composition of thin interfacial oxide were determined from analysis of on-line Auger electron spectroscopy features associated with Ga, N, and O. The plasma-assisted oxidation process is self-limiting with power-law kinetics similar to those for the plasma-assisted oxidation of Si and SiC. Oxidation using O2/He plasma forms nearly pure GaOx, and oxidation using 1% N2O in N2 forms GaOxNy with small nitrogen content, ~4-7 at. %. The interface and dielectric layer quality was investigated using fabricated GaN metal-oxide-semiconductor capacitors. The lowest density of interface states was achieved with a two-step plasma-assisted oxidation and nitridation process before SiO2 deposition.

  19. Apparatus and method to enhance X-ray production in laser produced plasmas

    DOEpatents

    Augustoni, Arnold L.; Gerardo, James B.; Raymond, Thomas D.

    1992-01-01

    Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser.

  20. Apparatus and method to enhance X-ray production in laser produced plasmas

    DOEpatents

    Augustoni, A.L.; Gerardo, J.B.; Raymond, T.D.

    1992-12-29

    Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography is disclosed. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser. 8 figs.

  1. Transformation of polymer composite nanofibers to diamond fibers and films by microwave plasma-enhanced CVD process

    NASA Astrophysics Data System (ADS)

    Potocký, Š.; Ižák, T.; Rezek, B.; Tesárek, P.; Kromka, A.

    2014-09-01

    In this work, polyvinyl alcohol (PVA) fibers were used as a polymer matrix containing ultra-dispersed diamond (UDD) nanoparticles. Growth of diamond fiber-like structures and films by microwave plasma-enhanced chemical vapor deposition was studied as a function of UDD concentration in the PVA matrix. The influence of surface tension (fibers radii) for nucleation/seeding is discussed. Using a high UDD concentration in the polymer matrix lead to the formation of fiber-like structures. The composite PVA polymer nanofibers with the highest concentration of UDD nanoparticles resulted in the growth of nearly continuous diamond film at low thickness of 250 nm.

  2. Green light emission from terbium doped silicon rich silicon oxide films obtained by plasma enhanced chemical vapor deposition.

    PubMed

    Podhorodecki, A; Zatryb, G; Misiewicz, J; Wojcik, J; Wilson, P R J; Mascher, P

    2012-11-30

    The effect of silicon concentration and annealing temperature on terbium luminescence was investigated for thin silicon rich silicon oxide films. The structures were deposited by means of plasma enhanced chemical vapor deposition. The structural properties of these films were investigated by Rutherford backscattering spectrometry, transmission electron microscopy and Raman scattering. The optical properties were investigated by means of photoluminescence and photoluminescence decay spectroscopy. It was found that both the silicon concentration in the film and the annealing temperature have a strong impact on the terbium emission intensity. In this paper, we present a detailed discussion of these issues and determine the optimal silicon concentration and annealing temperature.

  3. Green light emission from terbium doped silicon rich silicon oxide films obtained by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Podhorodecki, A.; Zatryb, G.; Misiewicz, J.; Wojcik, J.; Wilson, P. R. J.; Mascher, P.

    2012-11-01

    The effect of silicon concentration and annealing temperature on terbium luminescence was investigated for thin silicon rich silicon oxide films. The structures were deposited by means of plasma enhanced chemical vapor deposition. The structural properties of these films were investigated by Rutherford backscattering spectrometry, transmission electron microscopy and Raman scattering. The optical properties were investigated by means of photoluminescence and photoluminescence decay spectroscopy. It was found that both the silicon concentration in the film and the annealing temperature have a strong impact on the terbium emission intensity. In this paper, we present a detailed discussion of these issues and determine the optimal silicon concentration and annealing temperature.

  4. Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma

    SciTech Connect

    Okada, H.; Kato, M.; Ishimaru, T.; Sekiguchi, H.; Wakahara, A.; Furukawa, M.

    2014-02-20

    Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma is investigated. Feasibility of precursors of triethylsilane (TES) and bis(dimethylamino)dimethylsilane (BDMADMS) is discussed based on a calculation of bond energies by computer simulation. Refractive indices of 1.81 and 1.71 are obtained for deposited films with TES and BDMADMS, respectively. X-ray photoelectron spectroscopy (XPS) analysis of the deposited film revealed that TES-based film coincides with the stoichiometric thermal silicon nitride.

  5. Electrochromic Devices Deposited on Low-Temperature Plastics by Plasma-Enhanced Chemical Vapor Deposition

    SciTech Connect

    Robbins, Joshua; Seman, Michael

    2005-09-20

    Electrochromic windows have been identified by the Basic energy Sciences Advisory committee as an important technology for the reduction of energy spent on heating and cooling in residential and commercial buildings. Electrochromic devices have the ability to reversibly alter their optical properties in response to a small electric field. By blocking ultraviolet and infrared radiation, while modulating the incoming visible radiation, electrochromics could reduce energy consumption by several Quads per year. This amounts to several percent of the total annual national energy expenditures. The purpose of this project was to demonstrate proof of concept for using plasma-enhanced chemical vapor deposition (PECVD) for depositing all five layers necessary for full electrochromic devices, as an alternative to sputtering techniques. The overall goal is to produce electrochromic devices on flexible polymer substrates using PECVD to significantly reduce the cost of the final product. We have successfully deposited all of the films necessary for a complete electrochromic devices using PECVD. The electrochromic layer, WO3, displayed excellent change in visible transmission with good switching times. The storage layer, V2O5, exhibited a high storage capacity and good clear state transmission. The electrolyte, Ta2O5, was shown to functional with good electrical resistivity to go along with the ability to transfer Li ions. There were issues with leakage over larger areas, which can be address with further process development. We developed a process to deposit ZnO:Ga with a sheet resistance of < 50 W/sq. with > 90% transmission. Although we were not able to deposit on polymers due to the temperatures required in combination with the inverted position of our substrates. Two types of full devices were produced. Devices with Ta2O5 were shown to be functional using small aluminum dots as the top contact. The polymer electrolyte devices were shown to have a clear state transmission of

  6. Low-dielectric-constant fluorinated diamond-like carbon thin films by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Yi, Jeong Woo

    Fluorinated amorphous carbon (a-C:F) thin films are developed for a low dielectric constant interlayer dielectric material from hexafluorobenze (C 6F6) or 1,1,1,2-tetrafluoroethane (FCH2CF 4) as the source gas and argon as the diluent gas in an asymmetric capacitively coupled rf (radio frequency) plasma reactor and an inductively coupled plasma reactor. Effects of input rf power, fluorination, applied bias voltage and post annealing on the properties of a-C:F films are investigated. For depositing a-C:F films from highly diluted C6F6 (3%) and argon (97%) in the capacitively rf plasma reactor at 150 mTorr, the dielectric constant of the film increases from 2.0 to 2.8 as the rf power is increased from 10 W to 70 W, while the optical energy gap decreases from 2.6 eV to 1.9 eV and the transparency in a ultra-violet range is degraded. At input power of 100 W, the deposited film exhibits high residual stress of 40 MPa and easily peeled off by a Scotch tape test. This is due to high self-bias voltage (-230 V) developed at the substrate holder during deposition. When depositing amorphous carbon films from tetrafluoroethane (TFE) and methane in the capacitively coupled plasma reactor, the incorporation of fluorine in the film is increased with increasing TFE fraction in the feed gas mixture. The dielectric constant of the a-C:F film deposited from pure TFE is as low as 2.3, but the film exhibits poor thermal stability while a-C:H (diamond-like carbon) film deposited from pure methane has a dielectric constant of 3.8 and shows good thermal stability up to 400°C. As the TFE content in the feed is increased, the dielectric constant and the refractive index decrease while the transparency of the film is enhanced significantly. When depositing a-C:F films from C6F6 (4 sccm) and Ar (5 sccm) in the inductively coupled rf plasma reactor, the bias voltage (from a separate 100 KHz source) applied to the substrate holder affects the film properties significantly. As the negative bias

  7. Enhanced Dispersion of TiO2 Nanoparticles in a TiO2/PEDOT:PSS Hybrid Nanocomposite via Plasma-Liquid Interactions

    PubMed Central

    Liu, Yazi; Sun, Dan; Askari, Sadegh; Patel, Jenish; Macias-Montero, Manuel; Mitra, Somak; Zhang, Richao; Lin, Wen-Feng; Mariotti, Davide; Maguire, Paul

    2015-01-01

    A facile method to synthesize a TiO2/PEDOT:PSS hybrid nanocomposite material in aqueous solution through direct current (DC) plasma processing at atmospheric pressure and room temperature has been demonstrated. The dispersion of the TiO2 nanoparticles is enhanced and TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased electrical conductivity was observed for the plasma treated TiO2/PEDOT:PSS nanocomposite. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma treated TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are proposed to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer binding. PMID:26497265

  8. Flame Propagation Enhancement by Plasma Excitation of Oxygen. Part 1. Effects of O3

    DTIC Science & Technology

    2010-01-01

    gradient, marked as A in Fig. 7, the enhancement is the largest as shown in Fig. 9. The factor of four difference in the flame speed enhancement...earlier in this section. For a small mixture fraction gradient, marked as B in Fig. 7, the local flame speed enhancement is less, approaching the...0.99 and agreed well with numerical simu- lation results, marked as C in Fig. 7. Note that the deviation be- tween experimental and numerical results

  9. Plasma-enhanced CVD preparation of isotopes of group IV and VI elements

    NASA Astrophysics Data System (ADS)

    Sennikov, P. G.; Kornev, R. A.

    2016-03-01

    The plasma-chemical reduction was studied experimentally of molybdenum, sulfur and germanium fluorides with different isotopic composition by hydrogen in plasmas sustained by inductively coupled (IC) and capacitively-coupled (CC) RF discharges. The emission spectra of plasmas recorded under different experimental conditions are discussed. Reaction mechanisms are proposed. In the case of 98MoF6 reduction in CCP, the combined radical-atomic mechanism including intermediate MoF3 resulting in bulk and powder 98Mo formation was established. In the emission spectrum of the 32SF6 + H2 system in ICP at 0.2 Torr, only lines assigned to SiF2, SiF and F2 * originating from the decomposition of 32SF6 and a fast reaction of its products with the reactor's quartz walls were observed. Due to this etching process, the yield of 32S was moderate. Increasing the pressure in the reactor above 1 Torr resulted in an increase of the 32S yield. The mechanism of 72GeF4 reduction depends on the pressure and plasma type. At 0.25 Torr in ICP, a 72Ge deposit was formed via the 72GeF radical; however, at 3.5 Torr in CCP, the mechanism changed to a molecular one. Results of the study of the structure and the isotopic and chemical purity of isotope samples obtained are briefly presented.

  10. Single dielectric barrier discharge plasma enhanced aerodynamics: physics, modeling and applications

    NASA Astrophysics Data System (ADS)

    Corke, Thomas C.; Post, Martiqua L.; Orlov, Dmitriy M.

    2009-01-01

    The term “plasma actuator” has been a part of the fluid dynamics flow control vernacular for more than a decade. A particular type of plasma actuator that has gained wide use is based on a single dielectric barrier discharge (SDBD) mechanism that has desirable features for use in air at atmospheric pressures. For these actuators, the mechanism of flow control is through a generated body force vector that couples with the momentum in the external flow. The body force can be derived from first principles and the plasma actuator effect can be easily incorporated into flow solvers so that their placement and operation can be optimized. They have been used in a wide range of applications that include bluff body wake control; lift augmentation and separation control on a variety of lifting surfaces ranging from fixed wings with various degrees of sweep, wind turbine rotors and pitching airfoils simulating helicopter rotors; flow separation and tip-casing clearance flow control to reduce losses in turbines, to control flow surge and stall in compressors; and in exciting instabilities in boundary layers at subsonic to supersonic Mach numbers for turbulent transition control. New applications continue to appear through programs in a growing number of US universities and government laboratories, as well as in Germany, France, England, Netherland, Russia, Japan and China. This paper provides an overview of the physics, design and modeling of SDBD plasma actuators. It then presents their use in a number of applications that includes both numerical flow simulations and experiments together.

  11. Enhancement of hydrophobicity and tensile strength of muga silk fiber by radiofrequency Ar plasma discharge

    NASA Astrophysics Data System (ADS)

    Gogoi, D.; Choudhury, A. J.; Chutia, J.; Pal, A. R.; Dass, N. N.; Devi, D.; Patil, D. S.

    2011-10-01

    The hydrophobicity and tensile strength of muga silk fiber are investigated using radiofrequency (RF) Ar plasma treatment at various RF powers (10-30 W) and treatment times (5-20 min). The Ar plasma is characterized using self-compensated Langmuir and emissive probe. The ion energy is observed to play an important role in determining the tensile strength and hydrophobicity of the plasma treated fibers. The chemical compositions of the fibers are observed to be affected by the increase in RF power rather than treatment time. XPS study reveals that the ions that are impinging on the substrates are mainly responsible for the cleavage of peptide bond and side chain of amino acid groups at the surface of the fibers. The observed properties (tensile strength and hydrophobicity) of the treated fibers are found to be dependent on their variation in atomic concentration and functional composition at the surfaces. All the treated muga fibers exhibit almost similar thermal behavior as compared to the virgin one. At RF power of 10 W and treatment time range of 5-20 min, the treated fibers exhibit properties similar to that of the virgin one. Higher RF power (30 W) and the increase in treatment time deteriorate the properties of the fibers due to incorporation of more surface roughness caused by sufficiently high energetic ion bombardment. The properties of the plasma treated fibers are attempted to correlate with the XPS analysis and their surface morphologies.

  12. Sensitivity Enhancement of RF Plasma Etch Endpoint Detection With K-means Cluster Analysis

    NASA Astrophysics Data System (ADS)

    Lee, Honyoung; Jang, Haegyu; Lee, Hak-Seung; Chae, Heeyeop

    2015-09-01

    Plasma etching process is the core process in semiconductor fabrication, and the etching endpoint detection is one of the essential FDC (Fault Detection and Classification) for yield management and mass production. In general, Optical emission spectrocopy (OES) has been used to detect endpoint because OES can be a non-invasive and real-time plasma monitoring tool. In OES, the trend of a few sensitive wavelengths is traced. However, in case of small-open area etch endpoint detection (ex. contact etch), it is at the boundary of the detection limit because of weak signal intensities of reaction reactants and products. Furthemore, the various materials covering the wafer such as photoresist, dielectric materials, and metals make the analysis of OES signals complicated. In this study, full spectra of optical emission signals were collected and the data were analyzed by a data-mining approach, modified K-means cluster analysis. The K-means cluster analysis is modified suitably to analyze a thousand of wavelength variables from OES. This technique can improve the sensitivity of EPD for small area oxide layer etching processes: about 1.0% oxide area. This technique is expected to be applied to various plasma monitoring applications including fault detections as well as EPD. Plasma Etch, EPD, K-means Cluster Analysis.

  13. Enhancement of carbon-steel peel adhesion to rubber blend using atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Kršková, Jana; Skácelová, Dana; Kováčik, Dušan; Ráhel', Jozef; Pret'o, Jozef; Černák, Mirko

    2016-08-01

    The surface of carbon-steel plates was modified by non-equilibrium plasma of diffuse coplanar surface barrier discharge (DCSBD) in order to improve the adhesive properties to the NR (natural rubber) green rubber compound. The effect of different treatment times as well as different input power and frequency of supplied high voltage was investigated. The samples were characterized using contact angle and surface free energy measurement, measurement of adhesive properties, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface chemical composition was studied by energy-dispersive X-ray spectroscopy (EDX). Significant increase in wettability was observed even after 2 s of plasma exposure. The surface modification was confirmed also by peel test, where the best results were obtained for 6 s of plasma treatment. In addition the ageing effect was studied to investigate the durability of modification, which is crucial for the industrial applications. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  14. Enhanced Electron Attachment to Highly-Excited Molecules and Its Applications in Pulsed Plasmas

    SciTech Connect

    Ding, W.X.; Ma, C.Y.; McCorkle, D.L.; Pinnaduwage, L.A.

    1999-06-27

    Studies conducted over the past several years have shown that electron attachment to highly-excited states of molecules have extremely large cross sections. We will discuss the implications of this for pulsed discharges used for H- generation, material processing, and plasma remediation.

  15. Channel Efficiency with Security Enhancement for Remote Condition Monitoring of Multi Machine System Using Hybrid Huffman Coding

    NASA Astrophysics Data System (ADS)

    Datta, Jinia; Chowdhuri, Sumana; Bera, Jitendranath

    2016-12-01

    This paper presents a novel scheme of remote condition monitoring of multi machine system where a secured and coded data of induction machine with different parameters is communicated between a state-of-the-art dedicated hardware Units (DHU) installed at the machine terminal and a centralized PC based machine data management (MDM) software. The DHUs are built for acquisition of different parameters from the respective machines, and hence are placed at their nearby panels in order to acquire different parameters cost effectively during their running condition. The MDM software collects these data through a communication channel where all the DHUs are networked using RS485 protocol. Before transmitting, the parameter's related data is modified with the adoption of differential pulse coded modulation (DPCM) and Huffman coding technique. It is further encrypted with a private key where different keys are used for different DHUs. In this way a data security scheme is adopted during its passage through the communication channel in order to avoid any third party attack into the channel. The hybrid mode of DPCM and Huffman coding is chosen to reduce the data packet length. A MATLAB based simulation and its practical implementation using DHUs at three machine terminals (one healthy three phase, one healthy single phase and one faulty three phase machine) proves its efficacy and usefulness for condition based maintenance of multi machine system. The data at the central control room are decrypted and decoded using MDM software. In this work it is observed that Chanel efficiency with respect to different parameter measurements has been increased very much.

  16. Enhancing Maternal and Perinatal Health in Under-Served Remote Areas in Sub-Saharan Africa: A Tanzanian Model

    PubMed Central

    Nyamtema, Angelo S.; Mwakatundu, Nguke; Dominico, Sunday; Mohamed, Hamed; Pemba, Senga; Rumanyika, Richard; Kairuki, Clementina; Kassiga, Irene; Shayo, Allan; Issa, Omary; Nzabuhakwa, Calist; Lyimo, Chagi; van Roosmalen, Jos

    2016-01-01

    Background In Tanzania, maternal mortality ratio (MMR), unmet need for emergency obstetric care and health inequities across the country are in a critical state, particularly in rural areas. This study was established to determine the feasibility and impact of decentralizing comprehensive emergency obstetric and neonatal care (CEmONC) services in underserved rural areas using associate clinicians. Methods Ten health centres (HCs) were upgraded by constructing and equipping maternity blocks, operating rooms, laboratories, staff houses and installing solar panels, standby generators and water supply systems. Twenty-three assistant medical officers (advanced level associate clinicians), and forty-four nurse-midwives and clinical officers (associate clinicians) were trained in CEmONC and anaesthesia respectively. CEmONC services were launched between 2009 and 2012. Monthly supportive supervision and clinical audits of adverse pregnancy outcomes were introduced in 2011 in these HCs and their respective district hospitals. Findings After launching CEmONC services from 2009 to 2014 institutional deliveries increased in all upgraded rural HCs. Mean numbers of monthly deliveries increased by 151% and obstetric referrals decreased from 9% to 3% (p = 0.03) in HCs. A total of 43,846 deliveries and 2,890 caesarean sections (CS) were performed in these HCs making the mean proportion of all births in EmONC facilities of 128% and mean population-based CS rate of 9%. There were 190 maternal deaths and 1,198 intrapartum and very early neonatal deaths (IVEND) in all health facilities. Generally, health centres had statistically significantly lower maternal mortality ratios and IVEND rates than district hospitals (p < 0.00 and < 0.02 respectively). Of all deaths (maternal and IVEND) 84% to 96% were considered avoidable. Conclusions These findings strongly indicate that remotely located health centres in resource limited settings hold a great potential to increase accessibility to CEm

  17. Plasma and Laser-Enhanced Deposition of Powders and Thin Films.

    NASA Astrophysics Data System (ADS)

    David, Moses

    The objective of this thesis has been the development of novel plasma and laser based techniques for the deposition and characterization of thin films and nano-scale powders. The different energy sources utilized for excitation and break -down of reactive species prior to deposition include an RF plasma discharge, an excimer laser and a CO _2 laser. Nanometer-scale (10-20 nm) powders and thin films of aluminum nitride (AlN) have been successfully deposited in a glow discharge by reacting trimethylaluminum and ammonia. Macroquantities (~800 mg/hr) of powder have been collected at the centers of two vortices around which the reactant gases swirl. Powders of AlN have large surface areas (85 m^2/g) and are free from oxygen contamination. Diamond-like-carbon (DLC) films have been deposited from ternary mixtures of butadiene, argon and hydrogen. DLC films have been etched in O _2 and CF_4/O _2 plasmas. The etching behavior was correlated with the deposition feed gas composition by combining the etch rate, bias voltage during deposition and the deposition rate into a new non-dimensional number. Two new processes for depositing copper films have been developed. The first technique involves the hydrogen plasma reduction of copper formate films and the second technique involves the reactive excimer laser ablation of copper formate. Particle forming plasmas have been characterized by measuring the light scattering intensity during the deposition of silicon nitride from silane/ammonia plasmas. Both spatial variations and transients during the plasma start -up and shut-off steps have been measured. The ultraviolet (vacuum ultraviolet and extreme ultraviolet) reflectance characteristics of AlN, DLC and SiC thin films has been measured. AlN and SiC films exhibit a relatively high (~20-40%) reflectance in the different regions of the ultraviolet spectrum. An improved algorithm has been developed for estimating thin film parameters such as thickness, refractive index, band-gap, and

  18. Effects of the growth conditions on the roughness of amorphous hydrogenated carbon films deposited by plasma enhanced chemical vapor deposition

    SciTech Connect

    Capote, G.; Prioli, R.; Freire, F. L. Jr.

    2006-11-15

    The surface roughness and scaling behavior of a-C:H films deposited by plasma enhanced chemical vapor deposition from CH{sub 4}-Ar mixtures were studied using atomic force microscopy. Raman spectroscopy gives some insights about the film microstructure. The film surface roughness is shown to decrease with the increase of deposition negative self-bias, while the presence of Ar ions enhances this effect. An analysis of the film surface and scaling behavior suggests that there is a transition of the mechanism of the film growth from a random deposition with surface diffusion process to a thermal spike based process that occurs upon the increase of the negative self-bias voltage and the argon bombardment.

  19. Highly efficient shrinkage of inverted-pyramid silicon nanopores by plasma-enhanced chemical vapor deposition technology.

    PubMed

    Wang, Yifan; Deng, Tao; Chen, Qi; Liang, Feng; Liu, Zewen

    2016-06-24

    Solid-state nanopore-based analysis systems are currently one of the most attractive and promising platforms in sensing fields. This work presents a highly efficient method to shrink inverted-pyramid silicon nanopores using plasma-enhanced chemical vapor deposition (PECVD) technology by the deposition of SiN x onto the surface of the nanopore. The contraction of the inverted-pyramid silicon nanopores when subjected to the PECVD process has been modeled and carefully analyzed, and the modeling data are in good agreement with the experimental results within a specific PECVD shrinkage period (∼0-600 s). Silicon nanopores within a 50-400 nm size range contract to sub-10 nm dimensions. Additionally, the inner structure of the nanopores after the PECVD process has been analyzed by focused ion beam cutting process. The results show an inner structure morphology change from inverted-pyramid to hourglass, which may enhance the spatial resolution of sensing devices.

  20. Ag-plasma modification enhances bone apposition around titanium dental implants: an animal study in Labrador dogs.

    PubMed

    Qiao, Shichong; Cao, Huiliang; Zhao, Xu; Lo, Hueiwen; Zhuang, Longfei; Gu, Yingxin; Shi, Junyu; Liu, Xuanyong; Lai, Hongchang

    2015-01-01

    Dental implants with proper antibacterial ability as well as ideal osseointegration are being actively pursued. The antimicrobial ability of titanium implants can be significantly enhanced via modification with silver nanoparticles (Ag NPs). However, the high mobility of Ag NPs results in their potential cytotoxicity. The silver plasma immersion ion-implantation (Ag-PIII) technique may remedy the defect. Accordingly, Ag-PIII technique was employed in this study in an attempt to reduce the mobility of Ag NPs and enhance osseointegration of sandblasted and acid-etched (SLA) dental implants. Briefly, 48 dental implants, divided equally into one control and three test groups (further treated by Ag-PIII technique with three different implantation parameters), were inserted in the mandibles of six Labrador dogs. Scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry were used to investigate the surface topography, chemical states, and silver release of SLA- and Ag-PIII-treated titanium dental implants. The implant stability quotient examination, Microcomputed tomography evaluation, histological observations, and histomorphometric analysis were performed to assess the osseointegration effect in vivo. The results demonstrated that normal soft tissue healing around dental implants was observed in all the groups, whereas the implant stability quotient values in Ag-PIII groups were higher than that in the SLA group. In addition, all the Ag-PIII groups, compared to the SLA-group, exhibited enhanced new bone formation, bone mineral density, and trabecular pattern. With regard to osteogenic indicators, the implants treated with Ag-PIII for 30 minutes and 60 minutes, with the diameter of the Ag NPs ranging from 5-25 nm, were better than those treated with Ag-PIII for 90 minutes, with the Ag NPs diameter out of that range. These results suggest that Ag-PIII technique can reduce the mobility of Ag NPs and enhance

  1. Runaway electron generation as possible trigger for enhancement of magnetohydrodynamic plasma activity and fast changes in runaway beam behavior

    SciTech Connect

    Pankratov, I. M. E-mail: rjzhou@ipp.ac.cn; Zhou, R. J. E-mail: rjzhou@ipp.ac.cn; Hu, L. Q.

    2015-07-15

    Peculiar phenomena were observed during experiments with runaway electrons: rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the electron cyclotron emission (ECE) signal (cyclotron radiation of suprathermal electrons). These phenomena were initially observed in TEXTOR (Tokamak Experiment for Technology Oriented Research), where these events only occurred in the current decay phase or in discharges with thin stable runaway beams at a q = 1 drift surface. These rapid changes in the synchrotron spot were interpreted by the TEXTOR team as a fast pitch angle scattering event. Recently, similar rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the non-thermal ECE signal were observed in the EAST (Experimental Advanced Superconducting Tokamak) runaway discharge. Runaway electrons were located around the q = 2 rational magnetic surface (ring-like runaway electron beam). During the EAST runaway discharge, stepwise ECE signal increases coincided with enhanced magnetohydrodynamic (MHD) activity. This behavior was peculiar to this shot. In this paper, we show that these non-thermal ECE step-like jumps were related to the abrupt growth of suprathermal electrons induced by bursting electric fields at reconnection events during this MHD plasma activity. Enhancement of the secondary runaway electron generation also occurred simultaneously. Local changes in the current-density gradient appeared because of local enhancement of the runaway electron generation process. These current-density gradient changes are considered to be a possible trigger for enhancement of the MHD plasma activity and the rapid changes in runaway beam behavior.

  2. Runaway electron generation as possible trigger for enhancement of magnetohydrodynamic plasma activity and fast changes in runaway beam behavior

    NASA Astrophysics Data System (ADS)

    Pankratov, I. M.; Zhou, R. J.; Hu, L. Q.

    2015-07-01

    Peculiar phenomena were observed during experiments with runaway electrons: rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the electron cyclotron emission (ECE) signal (cyclotron radiation of suprathermal electrons). These phenomena were initially observed in TEXTOR (Tokamak Experiment for Technology Oriented Research), where these events only occurred in the current decay phase or in discharges with thin stable runaway beams at a q = 1 drift surface. These rapid changes in the synchrotron spot were interpreted by the TEXTOR team as a fast pitch angle scattering event. Recently, similar rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the non-thermal ECE signal were observed in the EAST (Experimental Advanced Superconducting Tokamak) runaway discharge. Runaway electrons were located around the q = 2 rational magnetic surface (ring-like runaway electron beam). During the EAST runaway discharge, stepwise ECE signal increases coincided with enhanced magnetohydrodynamic (MHD) activity. This behavior was peculiar to this shot. In this paper, we show that these non-thermal ECE step-like jumps were related to the abrupt growth of suprathermal electrons induced by bursting electric fields at reconnection events during this MHD plasma activity. Enhancement of the secondary runaway electron generation also occurred simultaneously. Local changes in the current-density gradient appeared because of local enhancement of the runaway electron generation process. These current-density gradient changes are considered to be a possible trigger for enhancement of the MHD plasma activity and the rapid changes in runaway beam behavior.

  3. Ag-plasma modification enhances bone apposition around titanium dental implants: an animal study in Labrador dogs

    PubMed Central

    Qiao, Shichong; Cao, Huiliang; Zhao, Xu; Lo, Hueiwen; Zhuang, Longfei; Gu, Yingxin; Shi, Junyu; Liu, Xuanyong; Lai, Hongchang

    2015-01-01

    Dental implants with proper antibacterial ability as well as ideal osseointegration are being actively pursued. The antimicrobial ability of titanium implants can be significantly enhanced via modification with silver nanoparticles (Ag NPs). However, the high mobility of Ag NPs results in their potential cytotoxicity. The silver plasma immersion ion-implantation (Ag-PIII) technique may remedy the defect. Accordingly, Ag-PIII technique was employed in this study in an attempt to reduce the mobility of Ag NPs and enhance osseointegration of sandblasted and acid-etched (SLA) dental implants. Briefly, 48 dental implants, divided equally into one control and three test groups (further treated by Ag-PIII technique with three different implantation parameters), were inserted in the mandibles of six Labrador dogs. Scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry were used to investigate the surface topography, chemical states, and silver release of SLA- and Ag-PIII-treated titanium dental implants. The implant stability quotient examination, Microcomputed tomography evaluation, histological observations, and histomorphometric analysis were performed to assess the osseointegration effect in vivo. The results demonstrated that normal soft tissue healing around dental implants was observed in all the groups, whereas the implant stability quotient values in Ag-PIII groups were higher than that in the SLA group. In addition, all the Ag-PIII groups, compared to the SLA-group, exhibited enhanced new bone formation, bone mineral density, and trabecular pattern. With regard to osteogenic indicators, the implants treated with Ag-PIII for 30 minutes and 60 minutes, with the diameter of the Ag NPs ranging from 5–25 nm, were better than those treated with Ag-PIII for 90 minutes, with the Ag NPs diameter out of that range. These results suggest that Ag-PIII technique can reduce the mobility of Ag NPs and

  4. Highly uniform wafer-scale synthesis of α-MoO3 by plasma enhanced chemical vapor deposition.

    PubMed

    Kim, Hyeong-U; Son, Juhyun; Kulkarni, Atul; Ahn, Chisung; Kim, Ki Seok; Shin, Dongjoo; Yeom, Geun Yong; Kim, Taesung

    2017-04-28

    Molybdenum oxide (MoO3) has gained immense attention because of its high electron mobility, wide band gap, and excellent optical and catalytic properties. However, the synthesis of uniform and large-area MoO3 is challenging. Here, we report the synthesis of wafer-scale α-MoO3 by plasma oxidation of Mo deposited on Si/SiO2. Mo was oxidized by O2 plasma in a plasma enhanced chemical vapor deposition (PECVD) system at 150 °C. It was found that the synthesized α-MoO3 had a highly uniform crystalline structure. For the as-synthesized α-MoO3 sensor, we observed a current change when the relative humidity was increased from 11% to 95%. The sensor was exposed to different humidity levels with fast recovery time of about 8 s. Hence this feasibility study shows that MoO3 synthesized at low temperature can be utilized for gas sensing applications by adopting flexible device technology.

  5. A Revival of Waste: Atmospheric Pressure Nitrogen Plasma Jet Enhanced Jumbo Silicon/Silicon Carbide Composite in Lithium Ion Batteries.

    PubMed

    Chen, Bing-Hong; Chuang, Shang-I; Liu, Wei-Ren; Duh, Jenq-Gong

    2015-12-30

    In this study, a jumbo silicon/silicon carbide (Si/SiC) composite (JSC), a novel anode material source, was extracted from solar power industry cutting waste and used as a material for lithium-ion batteries (LIBs), instead of manufacturing the nanolized-Si. Unlike previous methods used for preventing volume expansion and solid electrolyte interphase (SEI), the approach proposed here simply entails applying surface modification to JSC-based electrodes by using nitrogen-atmospheric pressure plasma jet (N-APPJ) treatment process. Surface organic bonds were rearranged and N-doped compounds were formed on the electrodes through applying different plasma treatment durations, and the qualitative examinations of before/after plasma treatment were identified by X-ray photoelectron spectroscopy (XPS) and electron probe microanalyzer (EPMA). The surface modification resulted in the enhancement of electrochemical performance with stable capacity retention and high Coulombic efficiency. In addition, depth profile and scanning electron microscope (SEM) images were executed to determine the existence of Li-N matrix and how the nitrogen compounds change the surface conditions of the electrodes. The N-APPJ-induced rapid surface modification is a major breakthrough for processing recycled waste that can serve as anode materials for next-generation high-performance LIBs.

  6. Apparatus and method for enhanced chemical processing in high pressure and atmospheric plasmas produced by high frequency electromagnetic waves

    DOEpatents

    Efthimion, Philip C.; Helfritch, Dennis J.

    1989-11-28

    An apparatus and method for creating high temperature plasmas for enhanced chemical processing of gaseous fluids, toxic chemicals, and the like, at a wide range of pressures, especially at atmospheric and high pressures includes an electro-magnetic resonator cavity, preferably a reentrant cavity, and a wave guiding structure which connects an electro-magnetic source to the cavity. The cavity includes an intake port and an exhaust port, each having apertures in the conductive walls of the cavity sufficient for the intake of the gaseous fluids and for the discharge of the processed gaseous fluids. The apertures are sufficiently small to prevent the leakage of the electro-magnetic radiation from the cavity. Gaseous fluid flowing from the direction of the electro-magnetic source through the guiding wave structure and into the cavity acts on the plasma to push it away from the guiding wave structure and the electro-magnetic source. The gaseous fluid flow confines the high temperature plasma inside the cavity and allows complete chemical processing of the gaseous fluids at a wide range of pressures.

  7. Low-temperature SiON films deposited by plasma-enhanced atomic layer deposition method using activated silicon precursor

    SciTech Connect

    Suh, Sungin; Kim, Jun-Rae; Kim, Seongkyung; Hwang, Cheol Seong; Kim, Hyeong Joon; Ryu, Seung Wook; Cho, Seongjae

    2016-01-15

    It has not been an easy task to deposit SiN at low temperature by conventional plasma-enhanced atomic layer deposition (PE-ALD) since Si organic precursors generally have high activation energy for adsorption of the Si atoms on the Si-N networks. In this work, in order to achieve successful deposition of SiN film at low temperature, the plasma processing steps in the PE-ALD have been modified for easier activation of Si precursors. In this modification, the efficiency of chemisorption of Si precursor has been improved by additional plasma steps after purging of the Si precursor. As the result, the SiN films prepared by the modified PE-ALD processes demonstrated higher purity of Si and N atoms with unwanted impurities such as C and O having below 10 at. % and Si-rich films could be formed consequently. Also, a very high step coverage ratio of 97% was obtained. Furthermore, the process-optimized SiN film showed a permissible charge-trapping capability with a wide memory window of 3.1 V when a capacitor structure was fabricated and measured with an insertion of the SiN film as the charge-trap layer. The modified PE-ALD process using the activated Si precursor would be one of the most practical and promising solutions for SiN deposition with lower thermal budget and higher cost-effectiveness.

  8. Direct fabrication of 3D graphene on nanoporous anodic alumina by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhan, Hualin; Garrett, David J.; Apollo, Nicholas V.; Ganesan, Kumaravelu; Lau, Desmond; Prawer, Steven; Cervenka, Jiri

    2016-01-01

    High surface area electrode materials are of interest for a wide range of potential applications such as super-capacitors and electrochemical cells. This paper describes a fabrication method of three-dimensional (3D) graphene conformally coated on nanoporous insulating substrate with uniform nanopore size. 3D graphene films were formed by controlled graphitization of diamond-like amorphous carbon precursor films, deposited by plasma-enhanced chemical vapour deposition (PECVD). Plasma-assisted graphitization was found to produce better quality graphene than a simple thermal graphitization process. The resulting 3D graphene/amorphous carbon/alumina structure has a very high surface area, good electrical conductivity and exhibits excellent chemically stability, providing a good material platform for electrochemical applications. Consequently very large electrochemical capacitance values, as high as 2.1 mF for a sample of 10 mm3, were achieved. The electrochemical capacitance of the material exhibits a dependence on bias voltage, a phenomenon observed by other groups when studying graphene quantum capacitance. The plasma-assisted graphitization, which dominates the graphitization process, is analyzed and discussed in detail.

  9. Kinetic modeling of evolution of 3 + 1:Resonance enhanced multiphoton ionization plasma in argon at low pressures

    SciTech Connect

    Tholeti, Siva Sashank; Alexeenko, Alina A.; Shneider, Mikhail N.

    2014-06-15

    We present numerical kinetic modeling of generation and evolution of the plasma produced as a result of resonance enhanced multiphoton ionization (REMPI) in Argon gas. The particle-in-cell/Monte Carlo collision (PIC/MCC) simulations capture non-equilibrium effects in REMPI plasma expansion by considering the major collisional processes at the microscopic level: elastic scattering, electron impact ionization, ion charge exchange, and recombination and quenching for metastable excited atoms. The conditions in one-dimensional (1D) and two-dimensional (2D) formulations correspond to known experiments in Argon at a pressure of 5 Torr. The 1D PIC/MCC calculations are compared with the published results of local drift-diffusion model, obtained for the same conditions. It is shown that the PIC/MCC and diffusion-drift models are in qualitative and in reasonable quantitative agreement during the ambipolar expansion stage, whereas significant non-equilibrium exists during the first few 10 s of nanoseconds. 2D effects are important in the REMPI plasma expansion. The 2D PIC/MCC calculations produce significantly lower peak electron densities as compared to 1D and show a better agreement with experimentally measured microwave radiation scattering.

  10. A combination of CO2 laser and plasma surface modification of poly(etheretherketone) to enhance osteoblast response

    NASA Astrophysics Data System (ADS)

    Zheng, Yanyan; Xiong, Chengdong; Wang, Zhecun; Li, Xiaoyu; Zhang, Lifang

    2015-07-01

    Poly(etheretherketone) (PEEK) is a rigid semicrystalline polymer that combines excellent mechanical properties, broad chemical resistance and bone-like stiffness and is widely used in biomedical fields. However, the bio-inert surface of PEEK tends to hinder its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, we demonstrate a dual modification method, which combines the laser and plasma surface treatment to combine advantages of both chemical states and microstructures for osteoblasts responses. While the plasma treatment introduces surface carboxyl groups (sbnd COOH) onto PEEK surface, the laser treatment constructs microstructures over the PEEK surface. Our results indicated that sbnd COOH as well as microgrooves containing micropores or microcraters structure are constructed on PEEK surface and plasma treatment has no apparent effect on the morphology of microstructures produced by laser micromachining. Unexpectedly, the superior mechanical properties of PEEK were maintained irrespective of the treatment used. Compared to native PEEK and single treated PEEK, dual modified PEEK is more favorable for pre-osteoblasts (MC3T3-E1) adhesion, spreading and proliferation. Moreover, cell pseudopodia protrude into the micropores or microcraters, in favor of forming firmer bone-implant integration. Our study illustrates enhanced osteoblasts responses to dual treated PEEK surface, which gives beneficial information of its potential use in orthopedic or dental implants.

  11. High Fat Diet Exposure during Fetal Life Enhances Plasma and Hepatic Omega-6 Fatty Acid Profiles in Fetal Wistar Rats

    PubMed Central

    Cerf, Marlon E.; Louw, Johan; Herrera, Emilio

    2015-01-01

    Pregnant rats were fed a high fat diet (HFD) for the first (HF1), second (HF2), third (HF3) or all three weeks (HFG) of gestation. Maintenance on a HFD during specific periods of gestation was hypothesized to alter fetal glycemia, insulinemia, induce insulin resistance; and alter fetal plasma and hepatic fatty acid (FA) profiles. At day 20 of gestation, fetal plasma and hepatic FA profiles were determined by gas chromatography; body weight, fasting glycemia, insulinemia and the Homeostasis Model Assessment (HOMA-insulin resistance) were also determined. HF3 fetuses were heaviest concomitant with elevated glycemia and insulin resistance (p < 0.05). HFG fetuses had elevated plasma linoleic (18:2 n-6) and arachidonic (20:4 n-6) acid proportions (p < 0.05). In the liver, HF3 fetuses displayed elevated linoleic, eicosatrienoic (20:3 n-6) and arachidonic acid proportions (p < 0.05). HFG fetuses had reduced hepatic docosatrienoic acid (22:5 n-3) proportions (p < 0.05). High fat maintenance during the final week of fetal life enhances hepatic omega-6 FA profiles in fetuses concomitant with hyperglycemia and insulin resistance thereby presenting a metabolically compromised phenotype. PMID:26343716

  12. Direct fabrication of 3D graphene on nanoporous anodic alumina by plasma-enhanced chemical vapor deposition

    PubMed Central

    Zhan, Hualin; Garrett, David J.; Apollo, Nicholas V.; Ganesan, Kumaravelu; Lau, Desmond; Prawer, Steven; Cervenka, Jiri

    2016-01-01

    High surface area electrode materials are of interest for a wide range of potential applications such as super-capacitors and electrochemical cells. This paper describes a fabrication method of three-dimensional (3D) graphene conformally coated on nanoporous insulating substrate with uniform nanopore size. 3D graphene films were formed by controlled graphitization of diamond-like amorphous carbon precursor films, deposited by plasma-enhanced chemical vapour deposition (PECVD). Plasma-assisted graphitization was found to produce better quality graphene than a simple thermal graphitization process. The resulting 3D graphene/amorphous carbon/alumina structure has a very high surface area, good electrical conductivity and exhibits excellent chemically stability, providing a good material platform for electrochemical applications. Consequently very large electrochemical capacitance values, as high as 2.1 mF for a sample of 10 mm3, were achieved. The electrochemical capacitance of the material exhibits a dependence on bias voltage, a phenomenon observed by other groups when studying graphene quantum capacitance. The plasma-assisted graphitization, which dominates the graphitization process, is analyzed and discussed in detail. PMID:26805546

  13. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces

    NASA Astrophysics Data System (ADS)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  14. Plasma assisted fabrication of multi-layer graphene/nickel hybrid film as enhanced micro-supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Ding, Q.; Li, W. L.; Zhao, W. L.; Wang, J. Y.; Xing, Y. P.; Li, X.; Xue, T.; Qi, W.; Zhang, K. L.; Yang, Z. C.; Zhao, J. S.

    2017-03-01

    A facile synthesis strategy has been developed for fabricating multi-layer graphene/nickel hybrid film as micro-supercapacitor electrodes by using plasma enhanced chemical vapor deposition. The as-presented method is advantageous for rapid graphene growth at relatively low temperature of 650 °C. In addition, after pre-treating for the as-deposited nickel film by using argon plasma bombardment, the surface-to-volume ratio of graphene film on the treated nickel substrate is effectively increased by the increasing of surface roughness. This is demonstrated by the characterization results from transmission electron microscopy, scanning electron microscope and atomic force microscopy. Moreover, the electrochemical performance of the resultant graphene/nickel hybrid film as micro-supercapacitor working electrode was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. It was found that the increase of the surface-to-volume ratio of graphene/nickel hybrid film improved the specific capacitance of 10 times as the working electrode of micro-supercapacitor. Finally, by using comb columnar shadow mask pattern, the micro-supercapacitor full cell device was fabricated. The electrochemical performance measurements of the micro-supercapacitor devices indicate that the method presented in this study provides an effective way to fabricate micro-supercapacitor device with enhanced energy storage property.

  15. Hydrogen plasma reduced black TiO2sbnd B nanowires for enhanced photoelectrochemical water-splitting

    NASA Astrophysics Data System (ADS)

    Tian, Zhangliu; Cui, Huolei; Zhu, Guilian; Zhao, Wenli; Xu, JiJian; Shao, Feng; He, Jianqiao; Huang, Fuqiang

    2016-09-01

    Black TiO2 with various nanostructures and phase constitutions have been reported to exhibit excellent photocatalytic and photoelectrochemical (PEC) performance. Here, we report the fabrication of black nanostructured TiO2sbnd B through hydrogen plasma assisted reduction and its enhanced PEC properties for the first time. Both the obtained TiO2sbnd B and black TiO2sbnd B are single crystalline nanowires, while the black TiO2sbnd B samples exhibit much stronger visible and infrared light absorption. The optimal black TiO2sbnd B sample obtained by hydrogen plasma treatment at 425 °C yields a photocurrent density of 0.85 mA cm-2, a rather low onset potential of -0.937 VAg/AgCl and a high applied bias photon-to-current efficiency (ABPE) of 0.363%, which is far superior to the TiO2sbnd B (0.15 mA cm-2 photocurrent, -0.917 VAg/AgCl onset potential and 0.138% ABPE). The significantly enhanced PEC performance of the black TiO2sbnd B is ascribed to the introduction of moderate surface oxygen vacancies. These results indicate that the black TiO2sbnd B is a promising material for PEC application and solar energy utilization.

  16. Collisonal Friction Enhanced by Two-Stream Instabilities Determines the Bohm Criterion in Plasmas With Multiple Ion Species

    NASA Astrophysics Data System (ADS)

    Baalrud, S. D.; Hegna, C. C.; Callen, J. D.

    2009-10-01

    Ion-ion streaming instabilities are excited in the presheath region of plasmas with multiple ion species if the ions are much colder than the electrons. Streaming instabilities onset when the relative fluid flow between ion species exceeds a critical speed, δVc, of order the ion thermal speeds. Using a generalized Lenard-Balescu theory that accounts for instability-enhanced collective responses [1], one is able to show the instabilities rapidly (within a few Debye lengths) enhance the collisional friction between ion species far beyond the contribution from Coulomb collisions alone. This strong frictional force determines the relative fluid speed between species. When this condition is combined with the Bohm criterion generalized for multiple ion species, the fluid speed of each ion species is determined at the sheath edge. For each species, this speed differs from the common ``system'' sound speed by a factor that depends on the species concentration and δVc.[4pt] [1] S.D. Baalrud, J.D. Callen, and C.C. Hegna, Phys. Plasmas 15, 092111 (2008).

  17. Enhanced propagation for relativistic laser pulses in inhomogeneous plasmas using hollow channels.

    PubMed

    Fuchs, J; d'Humières, E; Sentoku, Y; Antici, P; Atzeni, S; Bandulet, H; Depierreux, S; Labaune, C; Schiavi, A

    2010-11-26

    The influence of long (several millimeters) and hollow channels, bored in inhomogeneous ionized plasma by using a long pulse laser beam, on the propagation of short, ultraintense laser pulses has been studied. Compared to the case without a channel, propagation in channels significantly improves beam transmission and maintains a beam quality close to propagation in vacuum. In addition, the growth of the forward-Raman instability is strongly reduced. These results are beneficial for the direct scheme of the fast ignitor concept of inertial confinement fusion as we demonstrate, in fast-ignition-relevant conditions, that with such channels laser energy can be carried through increasingly dense plasmas close to the fuel core with minimal losses.

  18. Localized arc filament plasma actuators for noise mitigation and mixing enhancement

    NASA Technical Reports Server (NTRS)

    Samimy, Mohammad (Inventor); Adamovich, Igor (Inventor)

    2010-01-01

    A device for controlling fluid flow. The device includes an arc generator coupled to electrodes. The electrodes are placed adjacent a fluid flowpath such that upon being energized by the arc generator, an arc filament plasma adjacent the electrodes is formed. In turn, this plasma forms a localized high temperature, high pressure perturbation in the adjacent fluid flowpath. The perturbations can be arranged to produce vortices, such as streamwise vortices, in the flowing fluid to control mixing and noise in such flows. The electrodes can further be arranged within a conduit configured to contain the flowing fluid such that when energized in a particular frequency and sequence, can excite flow instabilities in the flowing fluid. The placement of the electrodes is such that they are unobtrusive relative to the fluid flowpath being controlled.

  19. Enhancing Understanding of High Energy Density Plasmas Using Fluid Modeling with Kinetic Closures

    NASA Astrophysics Data System (ADS)

    Hansen, David; Held, Eric; Srinivasan, Bhuvana; Masti, Robert; King, Jake

    2016-10-01

    This work seeks to understand possible stabilization mechanisms of the early-time electrothermal instability in the evolution of the Rayleigh-Taylor instability in MagLIF (Magnetized Liner Inertial Fusion) experiments. Such mechanisms may include electron thermal conduction, viscosity, and large magnetic fields. Experiments have shown that the high-energy density plasmas from wire-array implosions require physics modelling that goes well beyond simple models such as ideal MHD. The plan is to develop a multi-fluid extended-MHD model that includes kinetic closures for thermal conductivity, resistivity, and viscosity using codes that are easily available to the wider research community. Such an effort would provide the community with a well-benchmarked tool capable of advanced modeling of high-energy-density plasmas.

  20. Method of plasma enhanced chemical vapor deposition of diamond using methanol-based solutions

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua (Inventor)

    2009-01-01

    Briefly described, methods of forming diamond are described. A representative method, among others, includes: providing a substrate in a reaction chamber in a non-magnetic-field microwave plasma system; introducing, in the absence of a gas stream, a liquid precursor substantially free of water and containing methanol and at least one carbon and oxygen containing compound having a carbon to oxygen ratio greater than one, into an inlet of the reaction chamber; vaporizing the liquid precursor; and subjecting the vaporized precursor, in the absence of a carrier gas and in the absence in a reactive gas, to a plasma under conditions effective to disassociate the vaporized precursor and promote diamond growth on the substrate in a pressure range from about 70 to 130 Torr.

  1. Localized arc filament plasma actuators for noise mitigation and mixing enhancement

    NASA Technical Reports Server (NTRS)

    Samimy, Mohammad (Inventor); Adamovich, Igor (Inventor)

    2008-01-01

    A device for controlling fluid flow. The device includes an arc generator coupled to electrodes. The electrodes are placed adjacent a fluid flowpath such that upon being energized by the arc generator, an arc filament plasma adjacent the electrodes is formed. In turn, this plasma forms a localized high temperature, high pressure perturbation in the adjacent fluid flowpath. The perturbations can be arranged to produce vortices, such as streamwise vortices, in the flowing fluid to control mixing and noise in such flows. The electrodes can further be arranged within a conduit configured to contain the flowing fluid such that when energized in a particular frequency and sequence, can excite flow instabilities in the flowing fluid. The placement of the electrodes is such that they are unobtrusive relative to the fluid flowpath being controlled.

  2. Growth of TiO2 with thermal and plasma enhanced atomic layer deposition.

    PubMed

    Tallarida, Massimo; Friedrich, Daniel; Städter, Matthias; Michling, Marcel; Schmeisser, Dieter

    2011-09-01

    We show a comparative study of the TiO2 ALD with TTIP and either O2 or O2-plasma on Si/SiO2 substrates. In particular we compare the surface morphology and crystalline phase by means of Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS) for different O2-plasma procedures upon changing the time between cycles and the N2-purging pressure. The AFM images show that already these parameters may induce structural changes in the TiO2 films grown by ALD, with the formation of crystallites with average lateral width varying between 15 and 80 nm. By means of XAS we also found that the crystallites have mixed anatase and rutile crystalline phases and that smaller crystallites have a greater rutile component than the larger ones.

  3. Graphene matrix for signal enhancement in ambient plasma assisted laser desorption ionization mass spectrometry.

    PubMed

    Chang, Cuilan; Li, Xianjiang; Bai, Yu; Xu, Gege; Feng, Baosheng; Liao, Yiping; Liu, Huwei

    2013-09-30

    In this work, the signal intensity of ambient plasma assisted laser desorption ionization mass spectrometry (PALDI-MS) was significantly increased with graphene as matrix. The graphene functions as a substrate to trap analytes, absorb energy from the visible laser irradiation and transfer energy to the analytes to facilitate the laser desorption process. The desorbed analytes are further ionized by helium plasma and analyzed by MS. Compared with a traditional organic matrix, α-cyano-4-hydroxycinnamic acid (CHCA), graphene exhibited much higher desorption efficiency for most of the compounds benefitting from the strong optical absorption at 532nm. The performance has been confirmed by the facile analysis of more than forty compounds with various structures. Additionally, this method was successfully applied to distinguish three kinds of Chinese tea leaves by detecting the endogenous caffeine and theanine, which proved the utility, facility and convenience of this method for rapid screening of main components in real samples.

  4. Oxygen plasma immersion ion implantation treatment to enhance data retention of tungsten nanocrystal nonvolatile memory

    SciTech Connect

    Wang, Jer-Chyi Chang, Wei-Cheng; Lai, Chao-Sung; Chang, Li-Chun; Ai, Chi-Fong; Tsai, Wen-Fa

    2014-03-15

    Data retention characteristics of tungsten nanocrystal (W-NC) memory devices using an oxygen plasma immersion ion implantation (PIII) treatment are investigated. With an increase of oxygen PIII bias voltage and treatment time, the capacitance–voltage hysteresis memory window is increased but the data retention characteristics become degraded. High-resolution transmission electron microscopy images show that this poor data retention is a result of plasma damage on the tunneling oxide layer, which can be prevented by lowering the bias voltage to 7 kV. In addition, by using the elevated temperature retention measurement technique, the effective charge trapping level of the WO{sub 3} film surrounding the W-NCs can be extracted. This measurement reveals that a higher oxygen PIII bias voltage and treatment time induces more shallow traps within the WO{sub 3} film, degrading the retention behavior of the W-NC memory.

  5. CASSIOPE Enhanced Polar Outflow Probe (e-POP) Small Satellite Mission: Space Plasma Observations and International Collaborations

    NASA Astrophysics Data System (ADS)

    Yau, A. W.; James, H. G.

    2009-06-01

    In-situ observation of the micro-scale characteristics of plasma acceleration and related outflow processes is a primary scientific target of the Canadian Enhanced Polar Outflow Probe (e-POP) small satellite mission. The e-POP instrument payload will include imaging plasma and neutral particle sensors, magnetometers, dual-frequency GPS receivers, CCD cameras, a radio wave receiver and a beacon transmitter. The imaging plasma sensors will measure particle distributions and the magnetometers will measure field-aligned currents on the time scale of 10 ms and spatial scale of ~100 m. The CCD cameras will perform auroral imaging on the time scale of 100 ms and at spatial (pixel) resolution up to 0.4 km. The GPS and radio-wave receivers will perform near real-time imaging studies of the ionosphere in conjunction with ground-based radars, and the beacon transmitter in conjunction with ground receiving stations. The e-POP payload will be flown on the Canadian CASSIOPE small satellite, which is scheduled for launch in late 2008 into a polar orbit (325×1500 km, 80° inclination). International collaboration is an important and integral part of the e-POP mission strategy. Two of the 8 e-POP science instruments will be contributed by JAXA/ISAS, Japan, and Naval Research Laboratory, USA, respectively. Many of the planned e-POP investigations will entail coordinated observations using Canadian as well as foreign ground facilities, including magnetic and optical observatories, radars and heaters, such as the HAARP facility in Alaska, the EISCAT radar, and the NSF Antarctic facility. International collaboration in these investigations is expected to significantly enhance the science returns of the e-POP mission.

  6. The osmotically and histamine-induced enhancement of the plasma vasopressin level is diminished by intracerebroventricularly administered orexin in rats.

    PubMed

    Kis, Gyöngyi K; Molnár, Andor H; Daruka, Leila; Gardi, János; Rákosi, Kinga; László, Ferenc; László, Ferenc A; Varga, Csaba

    2012-04-01

    The effects of the centrally administered neuropeptides orexin-A on water intake and vasopressin (VP) secretion were studied in male Wistar rats (180-250 g). Different doses (10, 30, and 90 μg/10 μl) of the orexins and the specific orexin receptor-1 (OX(1)) antagonist SB 408124 (30 μg/10 μl) were administered intracerebroventricularly (i.c.v.) under anaesthesia, and the water consumption was measured during 6 h. A plasma VP level elevation was induced by histamine (10 mg/kg) or 2.5% NaCl (10 ml/kg) administered intraperitoneally (i.p.). The plasma VP levels were measured by radioimmunoassay. Increased water consumption was observed after the administration of 30 μg/10 μl orexin-A. There were no changes in basal VP secretion after the administration of different doses of the orexins. A significant increase in plasma VP concentration was detected following histamine administration. After 2.5% NaCl administration, there was a moderate VP level enhancement. Intracerebroventricularly administered orexin-A (30 μg/10 μl) blocked the VP level increase induced by either histamine or 2.5% NaCl administration. The inhibitory effects were prevented by the specific OX(1) receptor antagonist. In conclusion, the orexins increased water consumption. After 30 μg/10 μl orexin-A administration, the polydipsia was more pronounced. The OX(1) receptor antagonist significantly decreased the polydipsia. Histamine or hyperosmotic VP release enhancement was blocked by previously administered orexin. This inhibition was not observed following OX(1) receptor antagonist administration. Our results suggest that the effects of the orexins on water consumption or blockade of the histamine and osmosis-induced VP level increase are mediated by the OX(1) receptor.

  7. Enhancing the plasma illumination behaviour of microplasma devices using microcrystalline/ultra-nanocrystalline hybrid diamond materials as cathodes.

    PubMed

    Chang, Tinghsun; Lou, Shiucheng; Chen, Huangchin; Chen, Chulung; Lee, Chiyoung; Tai, Nyanhwa; Lin, Inan

    2013-08-21

    The properties of capacity-type microplasma devices were significantly enhanced due to the utilisation of hybrid diamond films as cathodes. The performance of the microplasma devices was closely correlated with the electron field emission (EFE) properties of the diamond cathode materials. The nanoemitters, which were prepared by growing duplex-structured diamond films [microcrystalline diamond (MCD)/ultra-nanocrystalline diamond (UNCD)] on Si-pyramid templates via a two-step microwave plasma enhanced chemical vapour deposition (MPE-CVD) process, exhibited improved EFE properties (E0 = 5.99 V μm(-1), J(e) = 1.10 mA cm(-2) at 8.50 V μm(-1) applied field), resulting in superior microplasma device performance (with a lower threshold field of 200 V mm(-1) and a higher plasma current density of 7.80 mA cm(-2)) in comparison with UNCD film devices prepared using a single-step MPE-CVD process. The superior EFE properties of the duplex-structured MCD-UNCD films relative to those of the UNCD films can be attributed to the unique granular structure of the diamond films. High-resolution transmission electron microscopy reveals that the MCD-UNCD films consisted of abundant graphitic phases located at the periphery of large diamond aggregates and at the boundaries between the ultra-small diamond grains. The presence of the graphite phase is presumed to be the prime factor that renders these films more conductive and causes these films to exhibit higher EFE properties, thus resulting in the improved plasma illumination properties of the microplasma devices.

  8. Remote Ischemic Preconditioning Enhances the Expression of Genes Encoding Antioxidant Enzymes and Endoplasmic Reticulum Stress-Related Proteins in Rat Skeletal Muscle

    PubMed Central

    Park, Ui Jun; Kim, Hyoung Tae; Cho, Won Hyun; Park, Jae Hyoung; Jung, Hye Ra; Kim, Min Young

    2016-01-01

    Purpose: Ischemic preconditioning (IPC), including remote IPC (rIPC) and direct IPC (dIPC), is a promising method to decrease ischemia-reperfusion (IR) injury. This study tested the effect of both rIPC and dIPC on the genes for antioxidant enzymes and endoplasmic reticulum (ER) stress-related proteins. Materials and Methods: Twenty rats were randomly divided into the control and study groups. In the control group (n=10), the right hind limb was sham-operated. The left hind limb (IscR) of the control group underwent IR injury without IPC. In the study group (n=10), the right hind limb received IR injury after 3 cycles of rIPC. The IscR received IR injury after 3 cycles of dIPC. Gene expression was analyzed by Quantitative real-time polymerase chain reaction from the anterior tibialis muscle. Results: The expression of the antioxidant enzyme genes including glutathione peroxidase (GPx), superoxide dismutase (SOD) 1 and catalase (CAT) were significantly reduced in IscR compared with sham treatment. In comparison with IscR, rIPC enhanced the expression of GPx, SOD2, and CAT genes. dIPC enhanced the expression of SOD2 and CAT genes. The expression of SOD2 genes was consistently higher in rIPC than in dIPC, but the difference was only significant for SOD2. The expression of genes for ER stress-related proteins tended to be reduced in IscR in comparison with sham treatment. However, the difference was only significant for C/EBP homologous protein (CHOP). In comparison with IscR, rIPC significantly up-regulated activating transcription factor 4 and CHOP, whereas dIPC up-regulated CHOP. Conclusion: Both rIPC and dIPC enhanced expression of genes for antioxidant enzymes and ER stress-related proteins. PMID:28042553

  9. Plasma-enhanced gasification of low-grade coals for compact power plants

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.; Hong, Yong C.; Shin, Dong H.; Lee, Bong J.

    2011-10-01

    A high temperature of a steam torch ensures an efficient gasification of low-grade coals, which is comparable to that of high-grade coals. Therefore, the coal gasification system energized by microwaves can serve as a moderately sized power plant due to its compact and lightweight design. This plasma power plant of low-grade coals would be useful in rural or sparsely populated areas without access to a national power grid.

  10. Enhancement of Combustion and Flame Stabilization Using Transient Non-Equilibrium Plasma

    DTIC Science & Technology

    2007-03-31

    were several possible outcomes: a.) successful ignition kernel evolution to a large flame; b.) extinction of the ignition kernel ; and c.) a self...extinguishing outward propagating flame. The successful transition from an ignition kernel to a propagating flame was strongly dependent on the transport...properties of the fuel-air mixture (Lewis number) and the radiation Fig. 56 Ignition kernel heat loss from the hot ignition kernel (by the plasma

  11. Nanosecond Plasma Enhanced H2/O2/N2 Premixed Flat Flames

    DTIC Science & Technology

    2014-01-01

    a function of height above the burner surface. As shown in Fig. 1b, the configuration referred to as “direct flame coupling” ( DFC ) is...single exponential decay and the radiative lifetime is taken from German [14]. For the spatially-resolved measurements, only one time delay ( t =8 µs...between the plasma discharge and the Nd:YAG laser is reported. This  t corresponds to the time delay after which the largest increase of OH (due to

  12. Plasma-enhanced etching of tungsten, tungsten silicide, and molybdenum in chlorine-containing discharges

    SciTech Connect

    Fischl, D.S.

    1988-01-01

    Thin films of tungsten, tungsten silicide, and molybdenum were etched both within and downstream from Cl{sub 2} discharges. Without a discharge, molecular chlorine did not etch the films. Experimental conditions ranged from 0.1 to 1.0 Torr pressure, 30 to 180{degree}C electrode temperature, 0.2 to 1.0 W/cm{sup 2} power density, and 3 to 200 sccm flow rate. In-discharge etch rates varied from 10 to 90 nm/min for tungsten (W), 10 to 450 nm/min for tungsten silicide (WSi{sub x}), and 1 to 8 nm/min for molybdenum (Mo). Small additions of BCl{sub 3}, during W and WSi{sub x} etching, significantly increased the etch rates and improved the reproducibility. When samples were positioned downstream from a Cl{sub 2} discharge, etching proceeded solely by chemical reaction of the film with chlorine atoms. Downstream and in-plasma tungsten etch rates were approximately equal at 110{degree}C, but the chlorine atom etch rate dropped more rapidly than the in-plasma etch rate as temperature decreased. In contrast, molybdenum etched faster by atoms alone than in the plasma, although atom etching was not observed below 100{degree}C. Reactions of tungsten with a modulated beam of chlorine atoms and molecules were also studied.

  13. Enhancement of plasma burn-through simulation and validation in JET

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Tae; Fundamenski, W.; Sips, A. C. C.; Contributors, EFDA-JET

    2012-10-01

    In this paper, new models for a plasma burn-through simulation using the DYON code are introduced in detail, and the quantitative validation of the simulation results against JET data is presented for the first time. In order to calculate the particle confinement time, a dynamic effective connection length model including an eddy current effect is used assuming ambipolar transonic transport and the Bohm diffusion model for parallel and perpendicular particle losses, respectively. Plasma-surface interaction effects are treated with an impurity sputtering yield and an exponential saturation model of the deuterium recycling coefficient. The rate and power coefficients in the Atomic Data and Analysis Structure (ADAS) package are adopted to solve energy and particle balance. The neutral screening effects are taken into account according to particle species, and the sophisticated energy and particle balances are presented. The new burn-through simulation shows good agreement against carbon-wall JET data. This indicates that the burn-through simulation can be applied to investigate the key aspect of physics in plasma burn-through and to perform a predictive simulation for ITER start-up.

  14. Plasma enhancement of femtosecond laser-induced electromagnetic pulses at metal and dielectric surfaces

    NASA Astrophysics Data System (ADS)

    Varma, Sanjay; Spicer, Jane; Brawley, Benjamin; Miragliotta, Joseph

    2014-05-01

    In a previous report, we have shown that the long wavelength, electromagnetic-pulsed (EMP) energy generated by ultrashort (38 fs) laser pulse ablation of a metal target is enhanced by an order of magnitude due to a preplasma generated by a different, 14-ns-long laser pulse. Here, we further investigate this EMP enhancement effect in a 2- to 16-GHz microwave region with different target materials and laser parameters. Specifically, we show a greater than two orders of magnitude enhancement to the EMP energy when the nanosecond and ultrashort laser pulses are coincident on a glass target, and greater than one order of magnitude enhancement when the pulses are coincident on a copper target.

  15. Method for generating a highly reactive plasma for exhaust gas after treatment and enhanced catalyst reactivity

    SciTech Connect

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2000-07-01

    This patent application describes a method and apparatus of exhaust gas remediation that enhance the reactivity of the material catalysts found within catalytic converters of cars, trucks, and power stations.

  16. Comment on 'Shock-wave-induced enhancement of optical emission in nitrogen afterglow plasma'

    SciTech Connect

    Naidis, G. V.

    2007-01-15

    Sieffert et al. [Phys. Rev. E 72, 066402 (2005)] have recently presented experimental results on optical emission enhancement at the front of shockwaves propagating in nitrogen afterglow. They claim that their results point to local heating of electrons at the shock front. In this Comment it is shown that the observed emission enhancement can be explained on the basis of a commonly accepted model of nitrogen discharge and afterglow, so that the use of unfounded assumption of local electron heating is not required.

  17. Shock-wave-induced enhancement of optical emission in nitrogen afterglow plasma

    SciTech Connect

    Siefert, N.; Ganguly, B.N.; Bletzinger, P.

    2005-12-15

    This paper reports measurements of optical emission enhancement at the shock front of Mach 1.5 to Mach 3.5 shockwaves propagating in the afterglow of a 0.75 Torr nitrogen glow discharge. Electrically-generated shocks pass through the afterglow and create noticeable enhancements of the B {sup 3}{pi}{sub g}-A {sup 3}{sigma}{sub u}{sup +} and C {sup 3}{pi}{sub u}-B {sup 3}{pi}{sub g} transitions of nitrogen. Under our discharge conditions, the electron Debye length was approximately the same magnitude as the shock thickness; this allows the possibility of a space-charge region extending beyond the neutral shockwave discontinuity. Previous researchers have measured enhancement in the B {sup 3}{pi}{sub g}-A {sup 3}{sigma}{sub u}{sup +} optical emission at the shock front, but only in the active discharge. Fibers connected to photomultipler tubes measure the optical emission from the discharge. Laser deflection measures the shock velocity. The data reveals that the emission enhancement increases with Mach number, and also indicates that the emission enhancement decreases exponentially with time in the afterglow. Since the discharge voltage has already been shut off, the energy needed to create the emission enhancement cannot come from the power supply. We conclude that under our discharge conditions there is an increase in the already non-equilibrium energy of the electrons at the shock front via a shockwave-induced strong double layer.

  18. Enhancement of antioxidant effects of naringin after atmospheric pressure dielectric barrier discharge plasma treatment.

    PubMed

    Kim, Tae Hoon; Jang, Soo Jeung; Chung, Hyung-Wook; Kim, Hyun-Joo; Yong, Hae In; Choe, Wonho; Jo, Cheorun

    2015-03-15

    Naringin is the natural chief bitter flavonoid found in Citrus species. Herein, bitter naringin was treated with atmospheric pressure plasma to afford two new converted flavonoids, narinplasmins A (2) and B (3), along with the known compound, 2R-naringin. The structures of the two new naringin derivatives were elucidated on the basis of spectroscopic methods. The antioxidant activity of all isolates was evaluated based on 1,1-diphenyl-2-picrylhydrazyl and peroxynitrite (ONOO(-)) scavenging assays. The new flavanone glycoside 2 containing a methoxyalkyl group exhibited significantly improved antioxidant properties in these assays relative to the parent naringin.

  19. Optical emission study of a doped diamond deposition process by plasma enhanced chemical vapor deposition

    SciTech Connect

    Rayar, M.; Supiot, P.; Veis, P.; Gicquel, A.

    2008-08-01

    Standard H{sub 2}/CH{sub 4}/B{sub 2}H{sub 6} plasmas (99% of H{sub 2} and 1% of CH{sub 4}, with 0-100 ppm of B{sub 2}H{sub 6} added) used for doped diamond film growth are studied by optical emission spectroscopy in order to gain a better understanding of the influence of boron species on the gas phase chemistry. Only two boron species are detected under our experimental conditions (9/15/23 W cm{sup -3} average microwave power density values), and the emission spectra used for studies reported here are B({sup 2}S{sub 1/2}-{sup 2}P{sub 1/2,3/2}{sup 0}) and BH[A {sup 1}{pi}-X {sup 1}{sigma}{sup +}(0,0)]. Variations of their respective emission intensities as a function of the ratio B/C, the boron to carbon ratio in the gas mixture, are reported. We confirmed that the plasma parameters (T{sub g}, T{sub e}, and n{sub e}) are not affected by the introduction of diborane, and the number densities of B atoms and BH radical species were estimated from experimental measurements. The results are compared to those obtained from a zero-dimensional chemical kinetic model where two groups of reactions are considered: (1) BH{sub x}+H{r_reversible}BH{sub x-1}+H{sub 2} (x=1-3) by analogy with the well-known equilibrium CH{sub x}+H set of reactions, which occurs, in particular, in diamond deposition reactors; and (2) from conventional organic chemistry, the set of reactions involving boron species: BH{sub x}+C{sub 2}H{sub 2} (x=0-1). The results clearly show that the model based on hydrogen and boron hydrides reactions alone is not consistent with the experimental results, while it is so when taking into account both sets of reactions. Once an upper limit for the boron species number densities has been estimated, axial profiles are calculated on the basis of the plasma model results obtained previously in Laboratoire d'Ingenierie des Materiaux et des Hautes Pressions, and significant differences in trends for different boron species are found. At the plasma-to-substrate boundary

  20. Optical emission study of a doped diamond deposition process by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Rayar, M.; Supiot, P.; Veis, P.; Gicquel, A.

    2008-08-01

    Standard H2/CH4/B2H6 plasmas (99% of H2 and 1% of CH4, with 0-100ppm of B2H6 added) used for doped diamond film growth are studied by optical emission spectroscopy in order to gain a better understanding of the influence of boron species on the gas phase chemistry. Only two boron species are detected under our experimental conditions (9/15/23Wcm-3 average microwave power density values), and the emission spectra used for studies reported here are B(S1/22-P1/2,3/202) and BH [AΠ1-XΣ+1(0,0)]. Variations of their respective emission intensities as a function of the ratio B /C, the boron to carbon ratio in the gas mixture, are reported. We confirmed that the plasma parameters (Tg, Te, and ne) are not affected by the introduction of diborane, and the number densities of B atoms and BH radical species were estimated from experimental measurements. The results are compared to those obtained from a zero-dimensional chemical kinetic model where two groups of reactions are considered: (1) BHx+H ↔BHx -1+H2 (x=1-3) by analogy with the well-known equilibrium CHx+H set of reactions, which occurs, in particular, in diamond deposition reactors; and (2) from conventional organic chemistry, the set o