WorldWideScience

Sample records for plasma thermal stabilization

  1. Stability of thermal modes in cool prominence plasmas

    CERN Document Server

    Soler, Roberto; Parenti, Susanna

    2012-01-01

    Context: Magnetohydrodynamic thermal modes may play an important role in the formation, plasma condensation, and evolution of solar prominences. Unstable thermal modes due to unbalance between radiative losses and heating can lead to rapid plasma cooling and condensation. An accurate description of the radiative loss function is therefore crucial for this process. Aims: We study the stability of thermal modes in unbounded and uniform plasmas with properties akin to those in solar prominences. Effects due to partial ionization are taken into account. Three different parametrizations of the radiative loss function are used. Methods: By means of a normal mode analysis, we investigate linear nonadiabatic perturbations superimposed on the equilibrium state. We find an approximate instability criterion for thermal modes, while the exact linear growth rate is obtained by numerically solving the general dispersion relation. The stability of thermal disturbances is compared for the three different loss functions consi...

  2. PLASMA THERMAL BARRIER COATINGS BASED ON ZIRCONIUM DIOXIDE WITH HIGH THERMAL STABILITY

    Directory of Open Access Journals (Sweden)

    O. G. Devoino

    2015-01-01

    Full Text Available The paper presents optimization of  processes for obtaining maximum content of tetragonal phase in the initial material and thermal barrier coatings (TBC based on zirconium dioxide and hafnium oxide.  Results of the investigations on phase composition of oxide HfO2 – ZrO2 – Y2O3  system have been given in the paper. The system represents  a microstructure which is similar to  zirconia dioxide and  transformed for its application at 1300 °C. The paper explains a mechanism of hafnium oxide influence on formation of the given microstructure. The research methodology has been based on complex metallography, X – ray diffraction and electron microscopic investigations of  structural elements of the composite plasma coating HfO2 – ZrO2 – Y2O system.In order to stabilize zirconium dioxide  dopant oxide should not only have an appropriate size of  metal ion, but also form a solid solution with the zirconia. This condition severely limits the number of possible stabilizers. In fact, such stabilization is possible only with the help of rare earth oxides (Y2O3, Yb2O3, CeO2, HfO2. Chemical purity of the applied materials plays a significant role for obtaining high-quality thermal barrier coatings. Hafnium oxide has been selected as powder for thermal barrier coatings instead of zirconium dioxide due to their similarities in structural modification, grating, chemical and physical properties and its high temperature structural transformations. It has been established that plasma thermal barrier HfO2 – ZrO2 – Y2O3 coatings consist of  one tetragonal phase. This phase is equivalent to a non-equilibrium tetragonal t' phase in the “zirconium dioxide stabilized with yttrium oxide” system. Affinity of  Hf+4 and Zr+4 cations leads to the formation of identical metastable phases during rapid quenching.

  3. Low Thermal Conductivity Yttria-Stabilized Zirconia Thermal Barrier Coatings Using the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Jordan, Eric H.; Jiang, Chen; Roth, Jeffrey; Gell, Maurice

    2014-06-01

    The primary function of thermal barrier coatings (TBCs) is to insulate the underlying metal from high temperature gases in gas turbine engines. As a consequence, low thermal conductivity and high durability are the primary properties of interest. In this work, the solution precursor plasma spray (SPPS) process was used to create layered porosity, called inter-pass boundaries, in yttria-stabilized zirconia (YSZ) TBCs. IPBs have been shown to be effective in reducing thermal conductivity. Optimization of the IPB microstructure by the SPPS process produced YSZ TBCs with a thermal conductivity of 0.6 W/mK, an approximately 50% reduction compared to standard air plasma sprayed (APS) coatings. In preliminary tests, SPPS YSZ with IPBs exhibited equal or greater furnace thermal cycles and erosion resistance compared to regular SPPS and commercially made APS YSZ TBCs.

  4. High Temperature Thermal Properties of Columnar Yttria Stabilized Zirconia Thermal Barrier Coating Performed by Suspension Plasma Spraying

    Science.gov (United States)

    Bernard, B.; Schick, V.; Remy, B.; Quet, A.; Bianchi, L.

    2016-09-01

    Performance enhancement of gas turbines is a main issue for the aircraft industry. Over many years, a large part of the effort has been focused on the development of more insulating Thermal Barrier Coatings (TBCs). In this study, Yttria Stabilized Zirconia (YSZ) columnar structures are processed by Suspension Plasma Spraying (SPS). These structures have already demonstrated abilities to get improved thermal lifetime, similarly to standard YSZ TBCs performed by EB-PVD. Thermal diffusivity measurements coupled with differential scanning calorimetry analysis are performed from room temperature up to 1100 °C, first, on HastelloyX substrates and then, on bilayers including a SPS YSZ coating. Results show an effective thermal conductivity for YSZ performed by SPS lower than 1 W.m-1K-1 whereas EB- PVD YSZ coatings exhibit a value of 1.5 W.m-1K-1.

  5. Factors affecting the microstructural stability and durability of thermal barrier coatings fabricated by air plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Helminiak, M.A.; Yanar, N.M.; Pettit, F.S.; Meier, G.H. [National Energy Technology Laboratory, Pittsburgh, PA 15236 (United States); Department of Mechanical Engineering and Materials Science, University of Pittsburgh, 636 Benedum Hall, 3700 O& #x27; Hara Street, Pittsburgh, PA 15261 (United States); Taylor, T.A. [Praxair Surface Technologies, Inc., 1400 Polco Street, Indianapolis, IN 46224 (United States)

    2012-10-15

    The high-temperature behavior of high-purity, low-density (HP-LD) air plasma sprayed (APS) thermal barrier coatings (TBCs) with NiCoCrAlY bond coats deposited by argon-shrouded plasma spraying is described. The high purity yttria-stabilized zirconia resulted in top coats which are highly resistant to sintering and transformation from the metastable tetragonal phase to the equilibrium mixture of monoclinic and cubic phases. The thermal conductivity of the as-processed TBC is low but increases during high temperature exposure even before densification occurs. The porous topcoat microstructure also resulted in good spallation resistance during thermal cycling. The actual failure mechanisms of the APS coatings were found to depend on topcoat thickness, topcoat density, and the thermal cycle frequency. The failure mechanisms are described and the durability of the HP-LD coatings is compared with that of state-of-the-art electron beam physical vapor deposition TBCs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. The Stability of Weakly Collisional Plasmas with Thermal and Composition Gradients

    CERN Document Server

    Pessah, Martin E; 10.1088/0004-637X/764/1/13

    2013-01-01

    Over the last decade, substantial efforts have been devoted to understanding the stability properties, transport phenomena, and long-term evolution of weakly-collisional, magnetized plasmas which are stratified in temperature. These studies have improved our understanding of the physics governing the intra-cluster medium (ICM), but assumed that ICM is a homogeneous. This, however, might not be a good approximation if heavy elements sediment in the inner region of the galaxy cluster. In this paper, we analyze the stability of a weakly-collisional, magnetized plane-parallel atmosphere which is stratified in both temperature and composition. This allows us to discuss for the first time the dynamics of weakly-collisional environments where heat conduction, momentum transport, and ion-diffusion are anisotropic with respect to the direction of the magnetic field. We show that, depending on the relative signs and magnitudes of the gradients in the temperature and the mean molecular weight, the plasma can be subject ...

  7. The stability of weakly collisional plasmas with thermal and composition gradients

    DEFF Research Database (Denmark)

    Pessah, M.E.; Chakraborty, S.

    2013-01-01

    Over the last decade, substantial efforts have been devoted to understanding the stability properties, transport phenomena, and long-term evolution of weakly collisional, magnetized plasmas which are stratified in temperature. The insights gained via these studies have led to a significant...... approximation if heavy elements are able to sediment in the inner region of the galaxy cluster. Motivated by the need to obtain a more complete picture of the dynamical properties of the ICM, we analyze the stability of a weakly collisional, magnetized plane-parallel atmosphere which is stratified in both...... in homogeneous media. We also find that there are new modes which are driven by heat conduction and particle diffusion. We discuss the astrophysical implications of our findings for a representative galaxy cluster where helium has sedimented. Our findings suggest that the core insulation that results from...

  8. Double-Layer Gadolinium Zirconate/Yttria-Stabilized Zirconia Thermal Barrier Coatings Deposited by the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Jiang, Chen; Jordan, Eric H.; Harris, Alan B.; Gell, Maurice; Roth, Jeffrey

    2015-08-01

    Advanced thermal barrier coatings (TBCs) with lower thermal conductivity, increased resistance to calcium-magnesium-aluminosilicate (CMAS), and improved high-temperature capability, compared to traditional yttria-stabilized zirconia (YSZ) TBCs, are essential to higher efficiency in next generation gas turbine engines. Double-layer rare-earth zirconate/YSZ TBCs are a promising solution. From a processing perspective, solution precursor plasma spray (SPPS) process with its unique and beneficial microstructural features can be an effective approach to obtaining the double-layer microstructure. Previously durable low-thermal-conductivity YSZ TBCs with optimized layered porosity, called the inter-pass boundaries (IPBs) were produced using the SPPS process. In this study, an SPPS gadolinium zirconate (GZO) protective surface layer was successfully added. These SPPS double-layer TBCs not only retained good cyclic durability and low thermal conductivity, but also demonstrated favorable phase stability and increased surface temperature capabilities. The CMAS resistance was evaluated with both accumulative and single applications of simulated CMAS in isothermal furnaces. The double-layer YSZ/GZO exhibited dramatic improvement in the single application, but not in the continuous one. In addition, to explore their potential application in integrated gasification combined cycle environments, double-layer TBCs were tested under high-temperature humidity and encouraging performance was recorded.

  9. Tribological and thermal stability study of nanoporous amorphous boron carbide films prepared by pulsed plasma chemical vapor deposition

    Science.gov (United States)

    Liza, Shahira; Ohtake, Naoto; Akasaka, Hiroki; Munoz-Guijosa, Juan M.

    2015-06-01

    In this work, the thermal stability and the oxidation and tribological behavior of nanoporous a-BC:H films are studied and compared with those in conventional diamond-like carbon (DLC) films. a-BC:H films were deposited by pulsed plasma chemical vapor deposition using B(CH3)3 gas as the boron source. A DLC interlayer was used to prevent the a-BC:H film delamination produced by oxidation. Thermal stability of a-BC:H films, with no delamination signs after annealing at 500 °C for 1 h, is better than that of the DLC films, which completely disappeared under the same conditions. Tribological test results indicate that the a-BC:H films, even with lower nanoindentation hardness than the DLC films, show an excellent boundary oil lubricated behavior, with lower friction coefficient and reduce the wear rate of counter materials than those on the DLC film. The good materials properties such as low modulus of elasticity and the formation of micropores from the original nanopores during boundary regimes explain this better performance. Results show that porous a-BC:H films may be an alternative for segmented DLC films in applications where severe tribological conditions and complex shapes exist, so surface patterning is unfeasible.

  10. Yttria-stabilized zirkonia / gadolinium zirconate double-layer plasma-sprayed thermal barrier coating systems (TBCs)

    Energy Technology Data Exchange (ETDEWEB)

    Bakan, Emine

    2015-07-01

    Thermal barrier coating (TBC) research and development is driven by the desirability of further increasing the maximum inlet temperature in a gas turbine engine. A number of new top coat ceramic materials have been proposed during the last decades due to limited temperature capability (1200 C) of the state-of-the-art yttria-stabilized zirconia (7 wt. % Y{sub 2}O{sub 3}-ZrO{sub 2}, YSZ) at long term operation. Zirconate pyrochlores of the large lanthanides((Gd → La){sub 2}Zr{sub 2}O{sub 7}) have been particularly attractive due to their higher temperature phase stability than that of the YSZ. Nonetheless, the issues related with the implementation of pyrochlores such as low fracture toughness and formation of deleterious interphases with thermally grown oxide (TGO, Al{sub 2}O{sub 3}) were reported. The implication was the requirement of an interlayer between the pyrochlores and TGO, which introduced double-layer systems to the TBC literature. Furthermore, processability issues of pyrochlores associated with the different evaporation rates of lanthanide oxides and zirconia resulting in unfavorable composition variations in the coatings were addressed in different studies. After all, although the material properties are available, there is a paucity of data in the literature concerning the properties of the coatings made of pyrochlores. From the processability point of view the most reported pyrochlore is La{sub 2}Zr{sub 2}O{sub 7}. Hence, the goal of this research was to investigate plasma-sprayed Gd{sub 2}Zr{sub 2}O{sub 7} (GZO) coatings and YSZ/GZO double-layer TBC systems. Three main topics were examined based on processing, performance and properties: (i) the plasma spray processing of the GZO and its impact on the microstructural and compositional properties of the GZO coatings; (ii) the cycling lifetime of the YSZ/GZO double-layer systems under thermal gradient at a surface temperature of 1400 C; (iii) the properties of the GZO and YSZ coatings such as

  11. Improvement of the thermal stability of nickel silicide using a ruthenium interlayer deposited via remote plasma atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Inhye [Department of Materials Science and Engineering, Hanyang University, Seoul 04763, South Korea and System LSI Manufacturing Operation Center, Samsung Electronics Co., Ltd, Gyeonggi-do 17113 (Korea, Republic of); Park, Jingyu; Jeon, Heeyoung; Kim, Hyunjung; Shin, Changhee [Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 04763 (Korea, Republic of); Shin, Seokyoon; Lee, Kunyoung [Department of Materials Science and Engineering, Hanyang University, Seoul 04763 (Korea, Republic of); Jeon, Hyeongtag, E-mail: hjeon@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, Seoul 04763, South Korea and Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 04763 (Korea, Republic of)

    2016-05-15

    In this study, the effects of a thin Ru interlayer on the thermal and morphological stability of NiSi have been investigated. Ru and Ni thin films were deposited sequentially to form a Ni/Ru/Si bilayered structure, without breaking the vacuum, by remote plasma atomic layer deposition (RPALD) on a p-type Si wafer. After annealing at various temperatures, the thermal stabilities of the Ni/Ru/Si and Ni/Si structures were investigated by various analysis techniques. The results showed that the sheet resistance of the Ni/Ru/Si sample was consistently lower compared to the Ni/Si sample over the entire temperature range. Although both samples exhibited the formation of NiSi{sub 2} phases at an annealing temperature of 800 °C, as seen with glancing angle x-ray diffraction, the peaks of the Ni/Ru/Si sample were observed to have much weaker intensities than those obtained for the Ni/Si sample. Moreover, the NiSi film with a Ru interlayer exhibited a better interface and improved surface morphologies compared to the NiSi film without a Ru interlayer. These results show that the phase transformation of NiSi to NiSi{sub 2} was retarded and that the smooth NiSi/Si interface was retained due to the activation energy increment for NiSi{sub 2} nucleation that is caused by adding a Ru interlayer. Hence, it can be said that the Ru interlayer deposited by RPALD can be used to control the phase transformation and physical properties of nickel silicide phases.

  12. Reactive Plasma Sprayed TiN Coating and Its Thermal Stability

    Institute of Scientific and Technical Information of China (English)

    ZOU Dong-li; YAN Dian-ran; HE Ji-ning; LI Xiang-zhi; DONG Yan-chun; ZHANG Jian-xin

    2007-01-01

    TiN coating was prepared by reactive plasma spraying in the Ar and N2 containing plasma jet. The results of XRD show that the TiN coating consists of TiN and Ti3O, neither Ti2N nor TiO2 phases. The toughening mechanism was characterized by analyzing the SEM morphologies of the TiN coating's indentation of microhardness and fracture surfaces. The results indicate that the coating possesses a high toughness. The adhesion strength among the TiN layers is 25.88 MPa, which is slightly lower than that of the Ni/Al bonding coating. The oxidation process of the RPS TiN coating is TiN→Ti3O→TiO2.

  13. Phase transformations in air plasma-sprayed yttria-stabilized zirconia thermal barrier coatings

    Directory of Open Access Journals (Sweden)

    Julián D. Osorio

    2014-01-01

    Full Text Available En este trabajo, las transformaciones de fase en Recubrimientos de Barrera Térmica (TBC constituidos por ZrO 2 – 8 wt.% Y2O3 (zirconia - 8 wt.% ytrria fueron estudiados a través de Difracción de Rayos X (XRD y refinamiento Rietveld. Las muestras de TBC fueron depositadas mediante aspersión por plasma atmosférico sobre un sustrato tipo Inconel 625 y fueron tratadas térmicamente con dos condiciones diferentes: en la primera se utilizó una temperatura de 1100oC con tiempos de exposición entre 1 hora y 1000 horas; en la segunda las muestras fueron sometidas a temperaturas entre 700oC y 1100o durante 50 horas. De acuerdo a los resultados obtenidos mediante refinamiento Rietveld el contenido de fase cúbica en el recubrimiento (TC se incrementa con el tiempo y la temperatura, desde 7.3 wt.% hasta 15.7 wt.% después de 1000 horas a 1100oC. La fase cúbica en grandes cantidades es indeseable debido a que presenta inferiores propiedades mecánicas cuando se compara con la fase tetragonal. Después de 800 horas de exposición a alta temperatura, el contenido de Y2O3 en la fase tetragonal se reduce hasta 6.6 wt.% y una fracción de la fase tetragonal transforma a monoclínica durante el enfriamiento. La fase monoclínica alcanza 18.0 wt.% después de 1000 horas. Esta fase es también indeseable porque además de tener una mayor conductividad térmica, la transformación de tetragonal a monoclínica viene acompañada de un cambio volumétrico de alrededor de 5% que promueve la formación y propagación de grietas, las cuales comprometen la integridad del recubrimiento.

  14. SUPERFAST THERMALIZATION OF PLASMA

    Science.gov (United States)

    Chang, C.C.

    1962-06-12

    A method is given for the superfast thermalization of plasma by shock conversion of the kinetic energy stored in rotating plasma rings or plasmoids colliding at near supersonic speeds in a containment field to heat energy in the resultant confined plasma mass. The method includes means for generating rotating plasmoids at the opposite ends of a Pyrotron or Astron containment field. The plasmoids are magnetically accelerated towards each other into the opposite ends of time containment field. During acceleration of the plasmoids toward the center of the containment field, the intensity of the field is sequentially increased to adiabatically compress the plasmoids and increase the plasma energy. The plasmoids hence collide with a violent shock at the eenter of the containment field, causing the substantial kinetic energy stored in the plasmoids to be converted to heat in the resultant plasma mass. (AEC)

  15. Comparison of CO{2} laser and atmospheric plasma treatments on thermal stability and structural modifications of microporous poly(vinyl chloride)/Silica composites

    Science.gov (United States)

    Becker, C.; Etienne, S.; Bour, J.; Ruch, D.; Aubriet, F.

    2008-09-01

    Several ways using surface modification are commonly used to enhance thermal stability of polymer matrices. In this study, Continuous-Wave carbon dioxide (CW CO{2}) laser irradiation and atmospheric pressure non-thermal He plasma treatment on microporous poly(vinyl chlo-ride)/Silica composite have been investigated and compared. On one hand the alternative was based on the efficiency of the thermal energy afforded by CW CO{2} laser irradiation and induced photodegradation processes to release HCl and form polyene sequences under well-controlled condition. On the other hand atmospheric plasma treatment involved surface modification by formation of unstable radicals, inducing crosslinking and dehydrochlorination. In both cases a global thermal stabilization of the composite was noticed by partial dehydrochlorination of PVC, even for short exposure time. The main effects observed after laser irradiation were related to the formation of a very dense structure on surface with very low chlorine content and an important chlorine atoms in-depth gradient on the cross section up to 150 μm in thickness; whereas atmospheric He plasma treatment led to a homogeneous decrease of the chlorine in-depth content due to the plasma interpenetration in the porous microstructure. Structural and chemical modifications both on extreme surface and in the thickness have been investigated respectively by Environmental Scanning Electron Microscope (ESEM) coupled with an Energy Dispersive X-ray analysis (EDX) and X-ray Photoelectron Spectroscopy (XPS). Composites thermal stability and investigation on chlorine release have been evaluated by Thermo Gravimetric Analysis (TGA) coupled with Mass Spectrometry (MS).

  16. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    Science.gov (United States)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  17. Transport of super-thermal particles and their effect on the stability of global modes in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Schneller, Mirjam Simone

    2013-08-02

    In thermonuclear plasmas, a population of super-thermal particles generated by external heating methods or fusion reactions can lead to the excitation of global instabilities. The transport processes due to nonlinear wave-particle interactions and the consequential particle losses reduce the plasma heating and the efficiency of the fusion reaction rate. Furthermore, these energetic or fast particles may cause severe damages to the wall of the device. This thesis addresses the resonance mechanisms between these energetic particles and global MHD and kinetic MHD waves, employing the hybrid code HAGIS. A systematic investigation of energetic particles resonant with multiple modes (double-resonance) is presented for the first time. The double-resonant mode coupling is modeled for waves with different frequencies in various overlapping scenarios. It is found that, depending on the radial mode distance, double-resonance is able to significantly enhance, both the growth rates and the saturation amplitudes. Small radial mode distances, however can lead to strong nonlinear mode stabilization of a linear dominant mode. For the first time, simulations of experimental conditions in the ASDEX Upgrade fusion device are performed for different plasma equilibria (particularly for different q profiles). An understanding of fast particle behavior for non-monotonic q profiles is important for the development of advanced fusion scenarios. The numerical tool is the extended version of the HAGIS code, which computes the particle motion in the vacuum region between vessel wall in addition to the internal plasma volume. For this thesis, a consistent fast particle distribution function was implemented, to represent the fast particle population generated by the particular heating method (ICRH). Furthermore, HAGIS was extended to use more realistic eigenfunctions, calculated by the gyrokinetic eigenvalue solver LIGKA. One important aim of these simulations is to allow fast ion loss

  18. Post-Plasma SiOx Coatings of Metal and Metal Oxide Nanoparticles for Enhanced Thermal Stability and Tunable Photoactivity Applications

    Directory of Open Access Journals (Sweden)

    Patrick Post

    2016-05-01

    Full Text Available The plasma-based aerosol process developed for the direct coating of particles in gases with silicon oxide in a continuous chemical vapor deposition (CVD process is presented. It is shown that non-thermal plasma filaments induced in a dielectric barrier discharge (DBD at atmospheric pressure trigger post-DBD gas phase reactions. DBD operating conditions are first scanned to produce ozone and dinitrogen pentoxide. In the selected conditions, these plasma species react with gaseous tetraethyl orthosilicate (TEOS precursor downstream of the DBD. The gaseous intermediates then condense on the surface of nanoparticles and self-reactions lead to homogeneous solid SiOx coatings, with thickness from nanometer to micrometer. This confirms the interest of post-DBD injection of the organo-silicon precursor to achieve stable production of actives species with subsequent controlled thickness of SiOx coatings. SiOx coatings of spherical and agglomerated metal and metal oxide nanoparticles (Pt, CuO, TiO2 are achieved. In the selected DBD operating conditions, the thickness of homogeneous nanometer sized coatings of spherical nanoparticles depends on the reaction duration and on the precursor concentration. For agglomerates, operating conditions can be tuned to cover preferentially the interparticle contact zones between primary particles, shifting the sintering of platinum agglomerates to much higher temperatures than the usual sintering temperature. Potential applications for enhanced thermal stability and tunable photoactivity of coated agglomerates are presented.

  19. Post-Plasma SiOx Coatings of Metal and Metal Oxide Nanoparticles for Enhanced Thermal Stability and Tunable Photoactivity Applications.

    Science.gov (United States)

    Post, Patrick; Jidenko, Nicolas; Weber, Alfred P; Borra, Jean-Pascal

    2016-05-13

    The plasma-based aerosol process developed for the direct coating of particles in gases with silicon oxide in a continuous chemical vapor deposition (CVD) process is presented. It is shown that non-thermal plasma filaments induced in a dielectric barrier discharge (DBD) at atmospheric pressure trigger post-DBD gas phase reactions. DBD operating conditions are first scanned to produce ozone and dinitrogen pentoxide. In the selected conditions, these plasma species react with gaseous tetraethyl orthosilicate (TEOS) precursor downstream of the DBD. The gaseous intermediates then condense on the surface of nanoparticles and self-reactions lead to homogeneous solid SiOx coatings, with thickness from nanometer to micrometer. This confirms the interest of post-DBD injection of the organo-silicon precursor to achieve stable production of actives species with subsequent controlled thickness of SiOx coatings. SiOx coatings of spherical and agglomerated metal and metal oxide nanoparticles (Pt, CuO, TiO₂) are achieved. In the selected DBD operating conditions, the thickness of homogeneous nanometer sized coatings of spherical nanoparticles depends on the reaction duration and on the precursor concentration. For agglomerates, operating conditions can be tuned to cover preferentially the interparticle contact zones between primary particles, shifting the sintering of platinum agglomerates to much higher temperatures than the usual sintering temperature. Potential applications for enhanced thermal stability and tunable photoactivity of coated agglomerates are presented.

  20. Impact of yttria stabilized zirconia nanoinclusions on the thermal conductivity of n-type Si80Ge20 alloys prepared by spark plasma sintering

    Science.gov (United States)

    Lahwal, Ali; Bhattacharya, S.; He, Jian; Wu, Di; Peterson, A.; Poon, S. J.; Williams, L.; Dehkordi, A. Mehdizadeh; Tritt, T. M.

    2015-04-01

    Nanocomposites have become a new paradigm for thermoelectric research in recent years and have resulted in the reduction of thermal conductivity via the nano-inclusion and grain boundary scattering. In this work, we report the preparation and thermoelectric study of SiGe-yttria stabilized zirconia (YSZ) nanocomposites prepared by Spark Plasma Sintering (SPS). We experimentally investigated the reduction of lattice thermal conductivity (κL) in the temperature range (30-800 K) of n-type Si80Ge20P2 alloys with the incorporation of YSZ nanoparticles (20-40 nm diameter) into the Si-Ge matrix. These samples synthesized by using the SPS technique were found to have densities > 95% of the theoretical density. The thermal conductivity, at both low and high temperatures, was measured by steady state and laser flash techniques, respectively. At room temperature, we observed approximately a 50% reduction in the lattice thermal conductivity as result of adding 10% YSZ by volume to the Si80Ge20P2 host matrix. A phenomenological model developed by Callaway was used to corroborate both the temperature dependence and reduction of κ L over the measured temperature range (30-800 K) of both Si80Ge20P2 and Si80Ge20P2 + YSZ samples. The observed κL is discussed and interpreted in terms of various phonon scattering mechanisms such as alloy disorder, the Umklapp phonon scattering, and boundary scattering. In addition, a contribution from the phonon scattering by YSZ nanoparticles was further included to account for the κL of Si80Ge20P2 + YSZ sample. The theoretical calculations are in reasonably good agreement with the experimental results for both the Si80Ge20P2 and Si80Ge20P2 + YSZ alloys.

  1. Thermally stabilized heliostat

    Science.gov (United States)

    Anderson, Alfred J.

    1983-01-01

    An improvement in a heliostat having a main support structure and pivoting and tilting motors and gears and a mirror module for reflecting solar energy onto a collector, the improvement being characterized by an internal support structure within each mirror module and front and back sheets attached to the internal support structure, the front and back sheets having the same coefficient of thermal expansion such that no curvature is induced by temperature change, and a layer of adhesive adhering the mirror to the front sheet. The adhesive is water repellent and has adequate set strength to support the mirror but has sufficient shear tolerance to permit the differential expansion of the mirror and the front sheet without inducing stresses or currature effect. The adhesive also serves to dampen fluttering of the mirror and to protect the mirror backside against the adverse effects of weather. Also disclosed are specific details of the preferred embodiment.

  2. Failure Behavior of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings Under Three-Point Bending Test via Acoustic Emission Technique

    Science.gov (United States)

    Wang, L.; Ni, J. X.; Shao, F.; Yang, J. S.; Zhong, X. H.; Zhao, H. Y.; Liu, C. G.; Tao, S. Y.; Wang, Y.; Li, D. Y.

    2017-01-01

    In this paper, the failure behavior of plasma-sprayed yttria-stabilized zirconia thermal barrier coatings fabricated by atmospheric plasma spraying (APS-TBCs) under three-point bending (3PB) test has been characterized via acoustic emission (AE) technique. Linear positioning method has been adopted to monitor dynamic failure process of the APS-TBCs under 3PB test. The investigation results indicate that the variation of AE parameters (AE event counts, amplitudes and AE energy) corresponds well with the change of stress-strain curve of the loading processes. The failure mechanism was analyzed based on the characteristics of AE parameters. The distribution of frequency of crack propagation has been obtained. The AE signals came from two aspects: i.e., plastic deformation of substrates, initiation and propagation of the cracks in the coatings. The AE analysis combined with cross-sectional observation has indicated that many critical cracks initiate at the surface of the top-coat. And some main cracks tend to propagate toward the substrate/bond-coat interface. The actual failure mechanism of the APS-TBCs under 3PB test is attributed to the debonding of metallic coating from the substrates and the propagation of the horizontal crack along the substrate/bond-coat interface under the action of flexural moment.

  3. Platinum thin films with good thermal and chemical stability fabricated by inductively coupled plasma-enhanced atomic layer deposition at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bo-Heng [Instrument Technology Research Center, National Applied Research Laboratories, Taiwan (China); Huang, Hung Ji, E-mail: hjhuang@itrc.narl.org.tw [Instrument Technology Research Center, National Applied Research Laboratories, Taiwan (China); Huang, Sheng-Hsin [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Hsiao, Chien-Nan [Instrument Technology Research Center, National Applied Research Laboratories, Taiwan (China)

    2014-09-01

    The inductively coupled plasma-enhanced atomic layer deposition (PEALD) method was used to fabricate ultrathin and smooth Pt thin films at low temperatures without the use of a Pt seed layer. The Pt thin metal films deposited at 200 °C onto Si and glass substrates exhibited high conductivities (< 12 μΩ cm for films with a thickness greater than 8 nm) and thermal stabilities resembling those of the bulk material. The measured density of the deposited Pt thin films was 20.7 ± 6 g/cm{sup 3}. X-ray photoelectron spectra of the films showed clear 4f peaks (74.3 eV (4f{sub 5/2}) and 71.1 eV (4f{sub 7/2})), and X-ray diffraction measurements showed the (111) peak of the fcc structure. The deposited Pt layers were in crystal form. The 25.5-nm Pt films coated onto 170-nm-wide trench structures (aspect ratio of 3.5:1) exhibited good step coverage. The PEALD-deposited Pt thin films were chemically stable under high-temperature light illumination and could serve as catalysts under strongly alkaline conditions (pH = 12) during the long-term oxidization of ammonium ions. - Highlights: • Inductively coupled plasma applied to enhance atomic layer deposition (PEALD) • Smooth Pt films fabricated by PEALD at low temperature • 8-nm Pt shows clear metal peaks in XPS and XRD. • 8-nm Pt shows low electrical resistivity of 16 μΩ cm. • 8-nm Pt shows stability under strong light and pH = 12 wash by NH{sub 4}{sup +}/NaOH solution.

  4. The role of stabilization centers in protein thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Magyar, Csaba [Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok krt 2, H-1117 Budapest (Hungary); Gromiha, M. Michael [Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600036 (India); Sávoly, Zoltán [Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok krt 2, H-1117 Budapest (Hungary); Simon, István, E-mail: simon.istvan@ttk.mta.hu [Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok krt 2, H-1117 Budapest (Hungary)

    2016-02-26

    The definition of stabilization centers was introduced almost two decades ago. They are centers of noncovalent long range interaction clusters, believed to have a role in maintaining the three-dimensional structure of proteins by preventing their decay due to their cooperative long range interactions. Here, this hypothesis is investigated from the viewpoint of thermal stability for the first time, using a large protein thermodynamics database. The positions of amino acids belonging to stabilization centers are correlated with available experimental thermodynamic data on protein thermal stability. Our analysis suggests that stabilization centers, especially solvent exposed ones, do contribute to the thermal stabilization of proteins. - Highlights: • Stabilization centers contribute to thermal stabilization of protein structures. • Stabilization center content correlates with melting temperature of proteins. • Exposed stabilization center content correlates with stability even in hyperthermophiles. • Stability changing mutations are frequently found at stabilization centers.

  5. Chemical and thermal stability of insulin

    DEFF Research Database (Denmark)

    Huus, Kasper; Havelund, Svend; Olsen, Helle B

    2006-01-01

    To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands.......To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands....

  6. Tribological properties and thermal stability of hydrogenated, silicon/nitrogen-coincorporated diamond-like carbon films prepared by plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Nakazawa, Hideki; Okuno, Saori; Magara, Kohei; Nakamura, Kazuki; Miura, Soushi; Enta, Yoshiharu

    2016-12-01

    We have deposited hydrogenated, silicon/nitrogen-incorporated diamond-like carbon (Si-N-DLC) films by plasma-enhanced chemical vapor deposition using hexamethyldisilazane [((CH3)3Si)2NH; HMDS] as the Si and N source, and compared the tribological performance and thermal stability of the Si-N-DLC films with those of hydrogenated, Si-incorporated DLC (Si-DLC) films prepared using dimethylsilane [SiH2(CH3)2] as the Si source. The deposited films were annealed at 723-873 K in air atmosphere. The friction coefficients of hydrogenated DLC films after annealing significantly increased at the initial stages of friction tests. On the other hand, the friction coefficients of the Si-N-DLC films deposited at an HMDS flow ratio [HMDS/(HMDS+CH4)] of 2.27% remained low after the annealing even at 873 K. We found that the wear rate of the Si-N-DLC film deposited at 2.27% and -1000 V remained almost unchanged after the annealing at 873 K, whereas that of the Si-DLC film with a similar Si fraction deposited at -1000 V significantly increased after the annealing at 773 K.

  7. The Kinetics, Stability and Thermal Contact Resistance of Nickel-Ca3Co4O9 Interfaces Formed by Spark Plasma Sintering

    DEFF Research Database (Denmark)

    Holgate, Tim; Wu, NingYu; Søndergaard, M.

    2012-01-01

    (Ca3Co4O9) have been formed directly by spark plasma sintering (SPS). An intermediate NiO phase is formed during the SPS processes, which grows during post heating with Co entering from the cobaltate side to form a graded Ni1-xCoxO interfacial layer. The electrical and thermal transport across...

  8. The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D. [Oak Ridge National Lab., TN (United States); Nagaraj, B.A. [General Electric Co., Cincinnati, OH (United States). Aircraft Engine Group

    1996-05-01

    Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging for plasma sprayed partially stabilized zirconia have been found to be less than for plasma sprayed fully stabilized zirconia coatings.

  9. System design description PFP thermal stabilization

    Energy Technology Data Exchange (ETDEWEB)

    LARKIN, K.A.

    1999-02-23

    The purpose of this document is to provide a system design description and design basis for the Plutonium Finishing Plant (PFP) Thermal Stabilization project. The sources of material for this project are residues scraped from glovebox floors and materials already stored in vault storage that need further stabilizing. Stabilizing this material will promote long term storage and reduced worker exposure. This document addresses: functional design, equipment, and safety requirements for thermal stabilization of plutonium residues and oxides.

  10. System design description PFP thermal stabilization

    Energy Technology Data Exchange (ETDEWEB)

    RISENMAY, H.R.

    1998-11-10

    The purpose of this document is to provide a system design description and design basis for the Plutonium Finishing P1ant (PFP) Thermal Stabilization project. The sources of material for this project are residues scraped from glovebox floors and materials already stored in vault storage that need further stabilizing to meet the 3013 storage requirements. Stabilizing this material will promote long term storage and reduced worker exposure. This document addresses: function design, equipment, and safety requirements for thermal stabilization of plutonium residues and oxides.

  11. Initial thermal plasma observations from ISEE-1

    Science.gov (United States)

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

    1980-09-01

    The initial measurements of magnetospheric thermal ions by the Plasma Composition Experiment on ISEE-1 are presented to demonstrate the surprising variety in this plasma population. The data provide evidence that the adiabatic mapping of the high latitude ionosphere to the equatorial plasma trough provides an insufficient description of the origin, transport, and accumulation processes which supply low energy ions to the outer plasmasphere and plasma trough.

  12. Thermal stability of aliphatic hyperbranched polyesters

    Directory of Open Access Journals (Sweden)

    Vuković Jasna

    2002-01-01

    Full Text Available The influence of the molar mass (generation, number and type of end groups on the thermal stability of aliphatic hyperbranched polyesters are presented in this study. Different end groups were obtained by modification of the samples with chlorides of propionic acid and stearic acid. The thermal stability of the hyperbranched polyesters was determined by thermogravimetry using a NET-ZSCH TG 209 instrument in nitrogen atmosphere at a heating rate of 10°C/min. A comparison of the temperatures obtained for mass losses of 5 20 and 40 wt% for unmodified samples showed that the thermal stability increased up to the fourth generation and then remained practically constant. An increase in the thermal stability of modified samples of the second, third and fourth generation was observed.

  13. Turbulence modelling of thermal plasma flows

    Science.gov (United States)

    Shigeta, Masaya

    2016-12-01

    This article presents a discussion of the ideas for modelling turbulent thermal plasma flows, reviewing the challenges, efforts, and state-of-the-art simulations. Demonstrative simulations are also performed to present the importance of numerical methods as well as physical models to express turbulent features. A large eddy simulation has been applied to turbulent thermal plasma flows to treat time-dependent and 3D motions of multi-scale eddies. Sub-grid scale models to be used should be able to express not only turbulent but also laminar states because both states co-exist in and around thermal plasmas which have large variations of density as well as transport properties under low Mach-number conditions. Suitable solution algorithms and differencing schemes must be chosen and combined appropriately to capture multi-scale eddies and steep gradients of temperature and chemical species, which are turbulent features of thermal plasma flows with locally variable Reynolds and Mach numbers. Several simulations using different methods under different conditions show commonly that high-temperature plasma regions exhibit less turbulent structures, with only large eddies, whereas low-temperature regions tend to be more turbulent, with numerous small eddies. These numerical results agree with both theoretical insight and photographs that show the characteristics of eddies. Results also show that a turbulence transition of a thermal plasma jet through a generation-breakup process of eddies in a torch is dominated by fluid dynamic instability after ejection rather than non-uniform or unsteady phenomena.

  14. Analysis of stability of a homogeneous state of anisotropic plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, V. Yu., E-mail: vladiyuz@mail.ru; Chernova, T. G., E-mail: chernova-tg@yandex.ru; Stepanov, S. E., E-mail: stepanov@bmstu-kaluga.ru [Bauman Moscow State Technical University, Kaluga Branch (Russian Federation)

    2015-04-15

    Small-amplitude waves in collisionless magnetized plasma are considered in the framework of one-fluid anisotropic magnetohydrodynamics with allowance for the anisotropy of the pressure and thermal flux. Stability of a homogeneous plasma state is analyzed using an eighth-order dispersion relation. Restrictions on the parameters of the homogeneous state at which the dispersion relation has no complex roots at any value of the angle between the wave vector and the unperturbed magnetic field are obtained. The applied method also makes it possible to determine the types of unstable waves.

  15. Thermal stability of bioactive enzymatic papers.

    Science.gov (United States)

    Khan, Mohidus Samad; Li, Xu; Shen, Wei; Garnier, Gil

    2010-01-01

    The thermal stability of two enzymes adsorbed on paper, alkaline phosphatase (ALP) and horseradish peroxidase (HRP), was measured using a colorimetric technique quantifying the intensity of the product complex. The enzymes adsorbed on paper retained their functionality and selectivity. Adsorption on paper increased the enzyme thermal stability by 2-3 orders of magnitude compared to the same enzyme in solution. ALP and HRP enzymatic papers had half-lives of 533 h and 239 h at 23 degrees C, respectively. The thermal degradation of adsorbed enzyme was found to follow two sequential first-order reactions, indication of a reaction system. A complex pattern of enzyme was printed on paper using a thermal inkjet printer. Paper and inkjet printing are ideal material and process to manufacture low-cost-high volume bioactive surfaces.

  16. Stability theory of Knudsen plasma diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, V. I., E-mail: victor.kuznetsov@mail.ioffe.ru; Ender, A. Ya. [Ioffe Institute, Russian Academy of Sciences (Russian Federation)

    2015-11-15

    A stability theory is developed for a plasma diode in which an electron beam supplied from the emitter propagates without collisions in the self-consistent electric field against the immobile ion background. An integral equation for the amplitude of the perturbed field is deduced using the Q,G method for the regime without electron reflection from a potential barrier. Analytic solutions to this equation are obtained for a number of important particular cases, and the plasma dispersion properties are examined.

  17. Thermal plasmas: fundamental aspects; Plasmas thermiques: aspects fondamentaux

    Energy Technology Data Exchange (ETDEWEB)

    Fauchais, P. [Limoges Univ. Faculte des Sciences, Lab. Science des Procedes Ceramiques et Traitements de Surface (SPCTS-UMR-6638-CNRS), 87 (France)

    2005-10-01

    This article treats of thermal plasmas, i.e. mainly produced by electric arcs and RF discharges. Their main characteristic is that they are generated at a pressure close to the atmospheric pressure (between 10{sup 4} and 10{sup 6} Pa) and refer to the classical kinetics of the Boltzmann equation. Because of the pressure, the collisions between particles are numerous and ionization is mainly due to a thermal effect. They correspond to electron densities between 10{sup 20} and 10{sup 24} m{sup -3} and temperatures between 6000 and 25000 K. In these plasmas, the electric fields and the average free trajectories are too weak to generate a ionization state by direct inelastic collision. Ionization is thus essentially a thermal phenomenon due to elastic collisions. This article presents: 1 - the particles present in a plasma: definition, energy states; 2 - characteristic data: collisions, average free path and collision cross-section, distribution function, ionization types, charged particles mobility inside an electric field, scattering, Debye length; 3 - plasmas at the thermodynamical equilibrium: conditions of equilibrium, calculation of composition, thermodynamic properties, transport properties, radiation; 4 - thermal plasmas away from equilibrium: conditions of non-equilibrium, calculation of plasma composition, calculation of transport properties, quenching phenomenon. (J.S.)

  18. Anisotropic Thermal Diffusivities of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Akoshima, Megumi; Takahashi, Satoru

    2017-09-01

    Thermal barrier coatings (TBCs) are used to shield the blades of gas turbines from heat and wear. There is a pressing need to evaluate the thermal conductivity of TBCs in the thermal design of advanced gas turbines with high energy efficiency. These TBCs consist of a ceramic-based top coat and a bond coat on a superalloy substrate. Usually, the focus is on the thermal conductivity in the thickness direction of the TBC because heat tends to diffuse from the surface of the top coat to the substrate. However, the in-plane thermal conductivity is also important in the thermal design of gas turbines because the temperature distribution within the turbine cannot be ignored. Accordingly, a method is developed in this study for measuring the in-plane thermal diffusivity of the top coat. Yttria-stabilized zirconia top coats are prepared by thermal spraying under different conditions. The in-plane and cross-plane thermal diffusivities of the top coats are measured by the flash method to investigate the anisotropy of thermal conduction in a TBC. It is found that the in-plane thermal diffusivity is higher than the cross-plane one for each top coat and that the top coats have significantly anisotropic thermal diffusivity. The cross-sectional and in-plane microstructures of the top coats are observed, from which their porosities are evaluated. The thermal diffusivity and its anisotropy are discussed in detail in relation to microstructure and porosity.

  19. The plasma scalpel: a new thermal knife.

    Science.gov (United States)

    Glover, J L; Bendick, P J; Link, W J; Plunkett, R J

    1982-01-01

    A new thermal knife, the plasma scalpel, capable of simultaneous division of tissue and coagulation of blood vessels, is described. A high temperature argon gas plasma (unrelated to blood plasma) is created by passing the gas through a direct current arc, ionizing the gas and elevating its temperature to 3000 degrees C. A small plasma cutting jet is formed by a nozzle at the tip of the handpiece. Liver resections and muscle transections performed in a canine model, and full thickness burn excisions in a pig skin model showed effective division of tissue and significantly less blood loss when compared to the steel scalpel. Wound healing studies of histologic comparisons and wound breaking strength were performed for steel, plasma, laser, and electrosurgical scalped incisions in the skin of mice and rats. All thermal knife wounds showed localized tissue damage at the edges of the incision, but the events of healing began at the same time. Compared to the steel scalpel, there was a three to six day delay in the onset of healing, but healing occurred in the normal fashion and all thermal knife wounds reached the same healed breaking strength as the steel scalpel wounds. Clinically, the plasma scalped has been used for 138 procedures in 96 patients. The majority of cases have been transection of muscle, hepatic resection or debridement, or soft tissue debridement. Muscle transection data for the plasma scalped compared to the electrosurgical scalpel has shown virtually no blood loss with a shorter time to hemostasis for the plasma scalpel. The plasma scalpel has proved to be an effective thermal knife, capable of simultaneous division and coagulation. Further development work and proof of its efficacy in the clinical setting are necessary to establish the plasma scalpel and adequately demonstrate its proper role in surgery.

  20. Plasma-Enhanced Chemical Vapor Deposition (PE-CVD) yields better Hydrolytical Stability of Biocompatible SiOx Thin Films on Implant Alumina Ceramics compared to Rapid Thermal Evaporation Physical Vapor Deposition (PVD).

    Science.gov (United States)

    Böke, Frederik; Giner, Ignacio; Keller, Adrian; Grundmeier, Guido; Fischer, Horst

    2016-07-20

    Densely sintered aluminum oxide (α-Al2O3) is chemically and biologically inert. To improve the interaction with biomolecules and cells, its surface has to be modified prior to use in biomedical applications. In this study, we compared two deposition techniques for adhesion promoting SiOx films to facilitate the coupling of stable organosilane monolayers on monolithic α-alumina; physical vapor deposition (PVD) by thermal evaporation and plasma enhanced chemical vapor deposition (PE-CVD). We also investigated the influence of etching on the formation of silanol surface groups using hydrogen peroxide and sulfuric acid solutions. The film characteristics, that is, surface morphology and surface chemistry, as well as the film stability and its adhesion properties under accelerated aging conditions were characterized by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and tensile strength tests. Differences in surface functionalization were investigated via two model organosilanes as well as the cell-cytotoxicity and viability on murine fibroblasts and human mesenchymal stromal cells (hMSC). We found that both SiOx interfaces did not affect the cell viability of both cell types. No significant differences between both films with regard to their interfacial tensile strength were detected, although failure mode analyses revealed a higher interfacial stability of the PE-CVD films compared to the PVD films. Twenty-eight day exposure to simulated body fluid (SBF) at 37 °C revealed a partial delamination of the thermally deposited PVD films whereas the PE-CVD films stayed largely intact. SiOx layers deposited by both PVD and PE-CVD may thus serve as viable adhesion-promoters for subsequent organosilane coupling agent binding to α-alumina. However, PE-CVD appears to be favorable for long-term direct film exposure to aqueous

  1. EXAFS investigation of nanoparticles produced in a thermal plasma process

    Energy Technology Data Exchange (ETDEWEB)

    Luetzenkirchen-Hecht, D.; Frahm, R. [Heinrich-Heine-Univ. Duesseldorf, Inst. fuer Angewandte Physik (Germany); Buchner, P. [Heinrich-Heine-Univ. Duesseldorf, Inst. fuer Laser- und Plasmaphysik (Germany); Strehblow, H.H. [Heinrich-Heine-Univ., Inst. fuer Physikalische Chemie (Germany)

    1999-11-01

    Nanosized ceramic powders (Cu/SiC, Y{sub 2}O{sub 3}-stabilized cubic ZrO{sub 2}) were produced by evaporation of coarsely grained powders of the respective materials in an inductively coupled thermal plasma process and rapid quenching of the vapor. The atomic short range order of these nanoparticles with an average diameter of about 10 nm was investigated ex situ with EXAFS. The results are compared to crystalline reference materials. (au) 10 refs.

  2. Cytocompatibility of Plasma and Thermally Treated Biopolymers

    Directory of Open Access Journals (Sweden)

    Petr Slepička

    2013-01-01

    Full Text Available This paper is focused on the surface characterization of plasma and consequently thermally treated biocompatible polymers. PLLA (poly(L-lactide acid and PMP (poly-4-methyl-1-pentene are studied. The influence of Ar plasma treatment on the surface polarity of substrate measured immediately after treatment and during the polymer surface aging is studied. Surface roughness, morphology, wettability, and surface chemistry were determined. Plasma treatment leads to significant changes in PLLA surface morphology and chemistry, with the PMP being slightly affected. The higher resistance to plasma fluence results in smaller ablation of PMP than that of PLLA. The plasma treatment improves cell adhesion and proliferation on the PMP. Plasma treatment of PLLA influences mostly the homogeneity of adhered and proliferated VSMC.

  3. Thermal stability of gas phase magnesium nanoparticles

    NARCIS (Netherlands)

    Krishnan, Gopi; Kooi, Bart J.; Palasantzas, George; Pivak, Yevheniy; Dam, Bernard

    2010-01-01

    In this work we present a unique transmission electron microscopy study of the thermal stability of gas phase synthesized Mg nanoparticles, which have attracted strong interest as high capacity hydrogen storage materials. Indeed, Mg nanoparticles with a MgO shell (similar to 3 nm thick) annealed at

  4. Thermal stability of gas phase magnesium nanoparticles

    NARCIS (Netherlands)

    Krishnan, G.; Kooi, B.J.; Palasantzas, G.; Pivak, Y.; Dam, B.

    2010-01-01

    In this work we present a unique transmission electron microscopy study of the thermal stability of gas phase synthesized Mg nanoparticles, which have attracted strong interest as high capacity hydrogen storage materials. Indeed, Mg nanoparticles with a MgO shell ( ∼ 3 nm thick) annealed at 300 °C

  5. Thermal stability of gas phase magnesium nanoparticles

    NARCIS (Netherlands)

    Krishnan, G.; Kooi, B.J.; Palasantzas, G.; Pivak, Y.; Dam, B.

    2010-01-01

    In this work we present a unique transmission electron microscopy study of the thermal stability of gas phase synthesized Mg nanoparticles, which have attracted strong interest as high capacity hydrogen storage materials. Indeed, Mg nanoparticles with a MgO shell ( ∼ 3 nm thick) annealed at 300 °C s

  6. Novel DTA method for thermal stability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Berty, J.M.; Gandhi, R.J.; Lee, S.

    1986-01-01

    A Differential Thermal Analysis (DTA) technique to study the kinetics of highly exothermic reactions for estimating thermal stability parameters has been developed. The technique involves measuring and analyzing the heat generated due to the reaction from a differential temperature curve. The technique has been tested by studying the kinetics of the reaction between sodium thiosulfate and hydrogen peroxide whose kinetic parameters are already known and whose thermal stability has been analyzed by a different technique. First the envisiones experiment was simulated on computer, then the DTA experimental equipment was designed on the basis of the computer simulation and finally the actual reaction between Na/sub 2/S/sub 2/O/sub 4/ and H/sub 2/O was performed. The satisfactory results demonstrated the feasibility of the DTA technique for estimating the kinetic parameters.

  7. Wall mode stabilization at slow plasma rotation

    Science.gov (United States)

    Hu, Bo; Betti, Riccardo; Reimerdes, Holger; Garofalo, Andrea; Manickam, Janardhan

    2007-11-01

    Unstable pressure-driven external kink modes, which become slowly growing resistive wall modes (RWMs) in the presence of a resistive wall, can lead to tokamak plasma disruptions at high beta. It has been shown that RWMs are stabilized by fast plasma rotation (about 1-2% of the Alfv'en frequency) in experiments. Conventional theories attribute the RWM suppression to the dissipation induced by the resonances between plasma rotation and ion bounce/transit or shear Alfv'en frequencies [1]. In those theories, the kinetic effects associated with the plasma diamagnetic frequencies and trapped-particle precession drift frequencies are neglected. It has been observed in recent experiments [2,3] that the RWM suppression also occurs at very slow plasma rotation (about 0.3% of the Alfv'en frequency), where the conventional dissipation is too small to fully suppress the RWMs. Here it is shown, that the trapped-particle kinetic contribution associated with the precession motion [4] is large enough to stabilize the RWM in DIII-D at low rotation. Work supported by the US-DoE OFES. [1] A. Bondeson and M. S. Chu, Physics of Plasmas, 3,3013 (1996). [2] H. Reimerdes et al., Physical Review Letters, 98,055001 (2007). [3] M. Takechi et al., Physical Review Letters, 98,055002 (2007). [4] B. Hu and R. Betti, Physical Review Letters, 93,105002 (2004).

  8. Plasma spray for forming nanostructured thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    LIN; Feng; JIANG; Xian-liang; YU; Yue-guang; ZENG; Ke-li; REN; Xian-jing

    2005-01-01

    Nanocrystalline powders of yttrium partially stabilized zirconia (YPSZ) are reprocessed into agglomerated feedstocks for plasma spraying thermal barrier coatings (TBCs), using the methods of ball milling, slurry dispersion, spray drying, and heat treatment. Atmospheric plasma is used to spray the agglomerated nanocrystalline particle feedstocks and coatings were deposited on the substrate of Ni-based superalloy. Scanning electron microscopy (SEM) is used to examine the morphology and cross-section of the agglomerated feedstocks and the free-section and cross-section of the nanostructured TBCs. Experimental results show that the agglomerated nanocrystalline particles are spherical and dense. Unlike conventional plasma-sprayed coatings, the micron/nano/micron sandwich structure can be found in the nanostructured YPSZ coatings deposited by atmospheric plasma spraying.

  9. Thermal stability of collagen triple helix.

    Science.gov (United States)

    Xu, Yujia

    2009-01-01

    Chief among the challenges of characterizing the thermal stability of the collagen triple helix are the lack of the reversibility of the thermal transition and the presence of multiple folding-unfolding steps during the thermal transition which rarely follows the simple two-state, all-or-none mechanism. Despite of the difficulties inherited in the quantitative depiction of the thermal transition of collagen, biophysical studies combined with proteolysis and mutagenesis approaches using full-chain collagens, short synthetic peptides, and recombinant collagen fragments have revealed molecular features of the thermal unfolding of the subdomains of collagen and led to a better understanding of the diverse biological functions of this versatile protein. The subdomain of collagen generally refers to a segment of the long, rope-like triple helical molecule that can unfold cooperatively as an independent unit whose properties (their size, location, and thermal stability) are considered essential for the molecular recognition during the self-assembly of collagen and during the interactions of collagen with other macromolecules. While the unfolding of segments of the triple helix at temperatures below the apparent melting temperature of the molecule has been used to interpret much of the features of the thermal unfolding of full-chain collagens, the thermal studies of short, synthetic peptides have firmly established the molecular basis of the subdomains by clearly demonstrating the close dependence of the thermal stability of a triple helix on the constituent amino acid residues at the X and the Y positions of the characteristic Gly-X-Y repeating sequence patterns of the triple helix. Studies using recombinant collagen fragments further revealed that in the context of the long, linear molecule, the stability of a segment of the triple helix is also modulated by long-range impact of the local interactions such as the interchain salt bridges. Together, the combined approaches

  10. Therapeutic Non Thermal Plasma, Significance and Challenges

    Directory of Open Access Journals (Sweden)

    Wameath Sh. Abdul-Majeed

    2014-06-01

    Full Text Available Plasma is an electrically neutral, highly ionized gas that consists of several species (electrons, ions, reactive species, and UV light and classified into localized thermal equilibrium (LTE plasmas and non-localized thermal equilibrium (n-LTE plasmas. In LTE plasmas, the electron temperature exists in equilibrium with the gas temperature. In contrast, the electron temperature in (n- LTE plasmas can reach temperatures of 1-10 (eV while the gas temperature is kept as low as room temperature, which makes it useful for a wide range of industrial applications (e.g. ozone generation, surface treatment, .., etc. In the past decade, non thermal (cold atmospheric pressure plasmas were developed and emerged as a promising new tool for medical applications as it’s proved to be more selective in its application (e.g. selective killing of microbes. Accordingly, developments of cold atmospheric plasma devices led to the possibility to apply plasma species to heat-sensitive surfaces (e.g. human skin with precise tuning, controllability and without damage of surrounding tissue. On this basis, medical plasma proved effective for skin sterilization, wound healing and tissue regeneration, cancer treatment, malignant cell apoptosis and blood coagulation. Moreover, cold plasma is known to inactivate a wide range of pathogens such as bacteria, viruses, fungi, spores and biofilms. Therefore it has been considered a very efficient alternative to superficially applied antibiotics or disinfectants. It’s worth noting that histological evaluation for the skin treated with atmospheric cold plasma showed that no morphological changes and no significant degree of necrosis or apoptosis were detectable after plasma treatment. Other studies denoted that a limited increase in the number of DNA double-strand breaks was observed in plasma-treated excised human skin. However, varieties of a new generation handheld and battery-operated devices makes it difficult to interpret the

  11. System Design Description PFP Thermal Stabilization

    Energy Technology Data Exchange (ETDEWEB)

    RISENMAY, H.R.

    2000-04-25

    The purpose of this document is to provide a system design description (SDD) and design basis for the Plutonium Finishing Plant (PFP) Thermal Stabilization project. The chief objective of the SDD is to document the Structures, Systems, and Components (SSCs) that establish and maintain the facility Safety Envelope necessary for normal safe operation of the facility; as identified in the FSAR, the OSRs, and Safety Assessment Documents (SADs). This safety equipment documentation should satisfy guidelines for the SDD given in WHC-SD-CP-TI-18 1, Criteria for Identification and Control of Equipment Necessary for Preservation of the Safety Envelope and Safe Operation of PFP. The basis for operational, alarm response, maintenance, and surveillance procedures are also identified and justified in this document. This document and its appendices address the following elements of the PFP Thermal Stabilization project: Functional and design requirements; Design description; Safety Envelope Analysis; Safety Equipment Class; and Operational, maintenance and surveillance procedures.

  12. Jet Fuel Thermal Stability Investigations Using Ellipsometry

    Science.gov (United States)

    Nash, Leigh; Vasu, Subith S.; Klettlinger, Jennifer Lindsey

    2017-01-01

    Jet fuels are typically used for endothermic cooling in practical engines where their thermal stability is very important. In this work the thermal stability of Sasol IPK (a synthetic jet fuel) with varying levels of naphthalene has been studied on stainless steel substrates using spectroscopic ellipsometry in the temperature range 385-400 K. Ellipsometry is an optical technique that measures the changes in a light beam’s polarization and intensity after it reflects off of a thin film to determine the film’s thickness and optical properties. All of the tubes used were rated as thermally unstable by the color standard portion of the Jet Fuel Thermal Oxidation Test, and this was confirmed by the deposit thicknesses observed using ellipsometry. A new amorphous model on a stainless steel substrate was used to model the data and obtain the results. It was observed that, as would be expected, increasing the temperature of the tube increased the overall deposit amount for a constant concentration of naphthalene. The repeatability of these measurements was assessed using multiple trials of the same fuel at 385 K. Lastly, the effect of increasing the naphthalene concentration in the fuel at a constant temperature was found to increase the deposit thickness.In conclusion, ellipsometry was used to investigate the thermal stability of jet fuels on stainless steel substrate. The effects of increasing temperature and addition of naphthalene on stainless steel tubes with Sasol IPK fuel were investigated. It was found, as expected, that increasing temperature lead to an increase in deposit thickness. It wasAmerican Institute of Aeronautics and Astronautics6also found that increasing amounts of naphthalene increased the maximum deposit thickness. The repeatability of these measurements was investigated using multiple tests at the same conditions. The present work provides as a better quantitative tool compared to the widely used JFTOT technique. Future work will expand on the

  13. Suspensions Plasma Spraying of Ceramics with Hybrid Water-Stabilized Plasma Technology

    Science.gov (United States)

    Musalek, Radek; Medricky, Jan; Tesar, Tomas; Kotlan, Jiri; Pala, Zdenek; Lukac, Frantisek; Chraska, Tomas; Curry, Nicholas

    2016-12-01

    Technology of water-stabilized plasma torch was recently substantially updated through introduction of a so-called hybrid concept that combines benefits of water stabilization and gas stabilization principles. The high-enthalpy plasma provided by the WSP-H ("hybrid") torch may be used for thermal spraying of powders as well as liquid feedstocks with high feed rates. In this study, results from three selected experiments with suspension plasma spraying with WSP-H technology are presented. Possibility of deposition of coatings with controlled microstructures was demonstrated for three different ceramics (YSZ—yttria-stabilized zirconia, YAG—yttrium aluminum garnet and Al2O3) introduced into ethanol-based suspensions. Shadowgraphy was used for optimization of suspension injection and visualization of the liquid fragmentation in the plasma jet. Coatings were deposited onto substrates attached to the rotating carousel with integrated temperature monitoring and air cooling, which provided an excellent reproducibility of the deposition process. Deposition of columnar-like YSZ and dense YAG and Al2O3 coatings was successfully achieved. Deposition efficiency reached more than 50%, as evaluated according to EN ISO 17 836 standard.

  14. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    B S Murty; M K Datta; S K Pabi

    2003-02-01

    Nanocrystalline materials, which are expected to play a key role in the next generation of human civilization, are assembled with nanometre-sized “building blocks” consisting of the crystalline and large volume fractions of intercrystalline components. In order to predict the unique properties of nanocrystalline materials, which are a combination of the properties of the crystalline and intercrystalline regions, it is essential to understand precisely how the structures of crystalline and intercrystalline regions vary with decrease in crystallite size. In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique properties of nanocrystalline materials. Therefore, extensive interest has been generated in exploring the size effects on the structure of crystalline and intercrystalline region of nanocrystalline materials, and the thermal stability of nanocrystalline materials against significant grain growth. The present article is aimed at understanding the structure and stability of nanocrystalline materials.

  15. Radiation and thermal stabilities of adenine nucleotides.

    Science.gov (United States)

    Demidov, V V; Potaman, V N; Solyanina, I P; Trofimov, V I

    1995-03-01

    We have investigated in detail radiation and thermal stabilities and transformations of adenosine mono- and triphosphates in liquid and frozen solid aqueous solutions within a wide range of absorbed radiation dose (up to 75 kGy) and temperature (up to 160 degrees C). Dephosphorylation is the main pathway of high temperature hydrolysis of adenine nucleotides. Basic thermodynamic and kinetic parameters of this process have been determined. Radiolysis of investigated compounds at room temperature results in scission of N-glycosidic bond with a radiation yield about of 1 mol/100 eV. Solution freezing significantly enhances radiation stability of nucleotides as well as other biomolecules. This circumstance is essential in the discussion of panspermia concepts.

  16. Thermal Hydraulic Stability in a Coaxial Thermosyphon

    Institute of Scientific and Technical Information of China (English)

    YANG Jianhui; LU Wenqiang; LI Qing; LI Qiang; ZHOU Yuan

    2005-01-01

    The heat transfer and thermal hydraulic stability in a two-phase thermosyphon with coaxial riser and down-comer has been experimentally investigated and theoretically analyzed to facilitate its application in cold neutron source. The flow in a coaxial thermosyphon was studied experimentally for a variety of heating rates, transfer tube lengths, charge capacities, and area ratios. A numerical analysis of the hydraulic balance between the driving pressure head and the resistance loss has also been performed. The results show that the presented coaxial thermosyphon has dynamic performance advantages relative to natural circulation in a boiling water reactor.

  17. The Thermal Stability of Unsymmetrical Dimethylhydrazine

    Science.gov (United States)

    Spakowski, Adolph E.

    1958-01-01

    The thermal stability of unsymmetrical dimethylhydrazine was investigated in a static system simulating conditions in an almost-empty fuel tank. The self-ignition temperature and spontaneous decomposition temperature of the pure fuel were determined at atmospheric pressure to be 454 and 740 F. respectively, with the larger (740 F) value, obtained in an inert atmosphere of nitrogen, representing the minimum temperature that would cause a rapid exothermic reaction. The addition of 40 weight percent dimethylenetriamine to unsymmetrical dimethylhydrazine did not significantly affect these properties.

  18. Speciation of copper in the thermally stabilized slag

    Energy Technology Data Exchange (ETDEWEB)

    Tuan, Y.-J. [Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Sustainable Environment Research Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Paul Wang, H., E-mail: wanghp@mail.ncku.edu.t [Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Sustainable Environment Research Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Chang, J.-E. [Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Sustainable Environment Research Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Chao, C.-C. [Sustainable Environment Research Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Tsai, C.-K. [Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2010-07-21

    The Taiwan universities laboratory hazardous wastes have been treated by incineration at the temperature range of 1173-1273 K. By X-ray absorption near edge structure (XANES) spectroscopy, mainly CuO and CuSO{sub 4} are found in the incineration bottom and fly ashes. The incineration fly ash can be stabilized thermally at 1773 K in the plasma melting reaction chamber (integrated with the incinerator), and converted to slag. The concentration of leachable copper in the slag is reduced significantly mainly due to the fact that copper is encapsulated in the SiO{sub 2} matrix. In addition, the refined extended X-ray adsorption fine structure (EXAFS) spectra of copper also indicate formation of the Cu-O-Si species in the slag as the bond distances of 1.95 A for Cu-O and 2.67 A for O-Si are observed. This work exemplifies utilization of the synchrotron X-ray absorption spectroscopy to facilitate the thermal stabilization treatments of the fly ash hazardous waste using the plasma melting method.

  19. Monoclinic zirconia distributions in plasma-sprayed thermal barrier coatings

    Science.gov (United States)

    Lance, M. J.; Haynes, J. A.; Ferber, M. K.; Cannon, W. R.

    2000-03-01

    Phase composition in an air plasma-sprayed Y2O3-stabilized ZrO2 (YSZ) top coating of a thermal barrier coating (TBC) system was characterized. Both the bulk phase content and localized pockets of monoclinic zirconia were measured with Raman spectroscopy. The starting powder consisted of ˜15 vol.% monoclinic zirconia, which decreased to ˜2 vol.% in the as-sprayed coating. Monoclinic zirconia was concentrated in porous pockets that were evenly distributed throughout the TBC. The pockets resulted from the presence of unmelted granules in the starting powder. The potential effect of the distributed monoclinic pockets on TBC performance is discussed.

  20. Electron thermal transport in tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Konings, J.A.

    1994-11-30

    The process of fusion of small nuclei thereby releasing energy, as it occurs continuously in the sun, is essential for the existence of mankind. The same process applied in a controlled way on earth would provide a clean and an abundant energy source, and be the long term solution of the energy problem. Nuclear fusion requires an extremely hot (10{sup 8} K) ionized gas, a plasma, that can only be maintained if it is kept insulated from any material wall. In the so called `tokamak` this is achieved by using magnetic fields. The termal insulation, which is essential if one wants to keep the plasma at the high `fusion` temperature, can be predicted using basic plasma therory. A comparison with experiments in tokamaks, however, showed that the electron enery losses are ten to hundred times larger than this theory predicts. This `anomalous transport` of thermal energy implies that, to reach the condition for nuclear fusion, a fusion reactor must have very large dimensions. This may put the economic feasibility of fusion power in jeopardy. Therefore, in a worldwide collaboration, physicists study tokamak plasmas in an attempt to understand and control the energy losses. From a scientific point of view, the mechanisms driving anomalous transport are one of the challenges in fudamental plasma physics. In Nieuwegein, a tokamak experiment (the Rijnhuizen Tokamak Project, RTP) is dedicated to the study of anomalous transport, in an international collaboration with other laboratories. (orig./WL).

  1. Experimental Study on Hydrocarbon Fuel Thermal Stability

    Institute of Scientific and Technical Information of China (English)

    J.S.Chin; A.H.Lefebvre

    1992-01-01

    The-thermal stability characteristics of kerosine-type fuels are examined using a heated-tube apparatus which allows independent control of fuel pressure,fuel temperature,tube-wall temperature and fuel flow rate.This method is identified simply as a "constant wall temperature method”,It is different from a previous widely used method ,which is identified as a “Constant heat flux method”,It is a single-pass system.Rate of deposition on the tube walls are measured by weighing the test tube before and after each test.For a fuel temperature of 250℃,it is found that deposition rates increease continuously with increase in tubewall temperature.This finding contradicts the results of previous studies which had led to the conclusion that deposition rates increase with increase in wall temperature up to a certain value(around 650K) beyond which any further increase in wall temperature causes the rate of deposition to decline.The present results show clearly that the constant wall temperature method is more suitable for assessing the thermal stability of gas turbine fuels.

  2. Kinetics, Stability, and Thermal Contact Resistance of Nickel–Ca3Co4O9 Interfaces Formed by Spark Plasma Sintering

    DEFF Research Database (Denmark)

    Holgate, Tim; Wu, NingYu; Søndergaard, M.;

    2013-01-01

    3Co4O9) have been formed directly by spark plasma sintering (SPS). An intermediate NiO phase is formed during the SPS processes, which grows during post-heating with Co entering from the cobaltate side to form a graded Ni1xCoxO interfacial layer. The electrical and thermal transport across...

  3. An optimal real-time controller for vertical plasma stabilization

    CERN Document Server

    Cruz, N; Coda, S; Duval, B P; Le, H B; Rodrigues, A P; Varandas, C A F; Correia, C M B A; Goncalves, B S

    2014-01-01

    Modern Tokamaks have evolved from the initial axisymmetric circular plasma shape to an elongated axisymmetric plasma shape that improves the energy confinement time and the triple product, which is a generally used figure of merit for the conditions needed for fusion reactor performance. However, the elongated plasma cross section introduces a vertical instability that demands a real-time feedback control loop to stabilize the plasma vertical position and velocity. At the Tokamak \\`a Configuration Variable (TCV) in-vessel poloidal field coils driven by fast switching power supplies are used to stabilize highly elongated plasmas. TCV plasma experiments have used a PID algorithm based controller to correct the plasma vertical position. In late 2013 experiments a new optimal real-time controller was tested improving the stability of the plasma. This contribution describes the new optimal real-time controller developed. The choice of the model that describes the plasma response to the actuators is discussed. The ...

  4. Thermal stability of PMMA–clay hybrids

    Indian Academy of Sciences (India)

    Tanushree Choudhury; Nirendra M Misra

    2010-04-01

    Materials with small particle size are being extensively used in composites and hybrid materials. Exfoliated clay–polymer hybrids show enhanced properties. Exfoliation of clay platelets can be affected by selecting dispersing agents. In the present work, clay dispersed by natural dispersant (soap stone powder), cetyl trimethyl ammonium bromide (CTAB) dispersed clay and acid clay (amorphous clay) are taken. They are then polymerized with poly methyl methacrylate (PMMA) by solution intercalation method. The thermal stability of these different clay–PMMA hybrids have been studied and compared with that of pure PMMA by differential scanning calorimeter (DSC). The bonding of clay with PMMA has been studied by IR. Morphology of clay–PMMA hybrids has been shown by SEM and XRD which indicate partially exfoliated structure in T606-4 and intercalated structures in T606-6 and T606-2.

  5. Thermal stability of nanoscale metallic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, A.S., E-mail: sofia.ramos@dem.uc.pt [CEMUC, Departamento de Engenharia Mecânica, Universidade de Coimbra, 3030-788 Coimbra (Portugal); Cavaleiro, A.J.; Vieira, M.T. [CEMUC, Departamento de Engenharia Mecânica, Universidade de Coimbra, 3030-788 Coimbra (Portugal); Morgiel, J. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Cracow (Poland); Safran, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, H-1121 Budapest (Hungary)

    2014-11-28

    Metallic nanolayered thin films/foils, in particular Ni/Al multilayers, have been used to promote joining. The objective of this work is to evaluate the thermal stability of nanoscale metallic multilayers with potential for joining applications. Multilayers thin films with low (Ti/Al and Ni/Ti), medium (Ni/Al) and high (Pd/Al) enthalpies of exothermic reaction were prepared by dual cathode magnetron sputtering. Their thermal stability was studied by: i) differential scanning calorimetry combined with X-ray diffraction (XRD), ii) in-situ XRD using cobalt radiation, and iii) in-situ transmission electron microscopy. It was possible to detect traces of intermetallic or amorphous phases in the as-deposited short period (bilayer thickness) multilayers, except for the Ti/Al films where no reaction products that might be formed during deposition were identified. For short periods (below 20 nm) the equilibrium phases are directly achieved upon annealing, whereas for higher periods intermediate trialuminide phases are present for Ti/Al and Ni/Al multilayers. The formation of B2-NiTi from Ni/Ti multilayers occurs without the formation of intermediate phases. On the contrary, for the Pd–Al system the formation of intermediate phases was never avoided. The viability of nanoscale multilayers as “filler” materials for joining macro or microparts/devices was demonstrated. - Highlights: • Me1 and Me2 (Me—metal) alternated nanolayers deposited by magnetron sputtering • Reactive Me1/Me2 multilayer thin films with nanometric modulation period • By heat treatment the films always evolve to the equilibrium intermetallic phase. • For some Me1–Me2 systems and periods, the formation of intermediate phases occurs. • Me1/Me2 multilayer thin films can be used as filler materials to enhance joining.

  6. Thermal Expansion of Vacuum Plasma Sprayed Coatings

    Science.gov (United States)

    Raj, S V.; Palczer, A. R.

    2010-01-01

    Metallic Cu-8%Cr, Cu-26%Cr, Cu-8%Cr-1%Al, NiAl and NiCrAlY monolithic coatings were fabricated by vacuum plasma spray deposition processes for thermal expansion property measurements between 293 and 1223 K. The corrected thermal expansion, (DL/L(sub 0) varies with the absolute temperature, T, as (DL/L(sub 0) = A(T - 293)(sup 3) + BIT - 293)(sup 2) + C(T - 293) + D, where, A, B, C and D are thermal, regression constants. Excellent reproducibility was observed for all of the coatings except for data obtained on the Cu-8%Cr and Cu-26%Cr coatings in the first heat-up cycle, which deviated from those determined in the subsequent cycles. This deviation is attributed to the presence of residual stresses developed during the spraying of the coatings, which are relieved after the first heat-up cycle. In the cases of Cu-8%Cr and NiAl, the thermal expansion data were observed to be reproducible for three specimens. The linear expansion data for Cu-8% Cr and Cu-26%Cr agree extremely well with rule of mixture (ROM) predictions. Comparison of the data for the Cu-8%Cr coating with literature data for Cr and Cu revealed that the thermal expansion behavior of this alloy is determined by the Cu-rich matrix. The data for NiAl and NiCrAlY are in excellent agreement with published results irrespective of composition and the methods used for processing the materials. The implications of these results on coating GRCop-84 copper alloy combustor liners for reusable launch vehicles are discussed.

  7. Effect of Plasma Pretreatment on Thermal Durability of Thermal Barrier Coatings in Cyclic Thermal Exposure

    Directory of Open Access Journals (Sweden)

    Sang-Won Myoung

    2014-01-01

    Full Text Available Plasma pretreatment on the top and bond coats was performed and its influence on the thermal durability of thermal barrier coating (TBC system was investigated through cyclic thermal exposure. Two types of bond coat were prepared by different methods, namely, air plasma spray (APS and high-velocity oxy-fuel (HVOF, and two kinds of feedstock powder were employed for preparing the top coat in APS process. The better thermal durability was achieved in the vertically cracked TBC with the surface modified bond coat or with the bond coat prepared by APS process. The hardness and fracture toughness values of TBCs increased because of densification of the top coat during cyclic thermal exposure, and the bond coat prepared by HVOF process showed higher values than that by APS process. The TBCs with the surface modified bond coat were more efficient in improving adhesive strength than those without plasma pretreatment on the bond coat. The relationship between microstructure evolution and thermomechanical characteristics of TBCs with plasma pretreatment was discussed in cyclic thermal exposure.

  8. System Design Description PFP Thermal Stabilization

    Energy Technology Data Exchange (ETDEWEB)

    RISENMAY, H.R.

    2000-01-27

    DOE has authorized in their letter of August 2, 1999, the operation of these three furnaces, quote ''Operation of the three uncompleted muffle furnaces (No.3, No.4, and No.5) located in Room 235B is authorized, using the same feed charge limits as the two existing furnaces (No.1, and No.2) located in Room 230C,''. The above statement incorrectly refers to Room 230C whereas the correct location is Room 230A. The current effort is directed to initiate the operation and to complete the design activities DOE authorized the operation of the furnaces based on their Safety Evaluation Report (SER). Based on analogy and the principle of similarity, the risks and consequences of accidents both onsite and offsite due to operation of three furnaces are not significantly larger than those already evaluated with the two operating furnaces. Thermal stabilization operations and the material of feed for furnaces in Glovebox HA-21 I are essentially the same as those currently being stabilized in furnaces in Glovebox HC-21 C. Therefore the accident analysis has utilized identical accident scenarios in evaluation and no additional failure modes are introduced by HA-21 I muffle furnace operation that would enhance the consequences of accidents. Authorization Basis documents as referenced below (PFP FSAR and DOE Letter authorizing the operation) appear to contradict each other, i.e. one allows and authorizes the operation and the other imposes the restriction on the operation. The purpose of the PFP FSAR restrictions was to review thoroughly the design and installation of three furnaces and perform acceptance testing before approving the startup for operation. With the experience of operating the two furnaces in Glovebox HC-21C, and the knowledge of risks and hazards the facility operation, the plant is adequately prepared to operate these additional furnaces. ECN 653595 has been prepared to incorporate operation of the muffle furnaces in Glovebox HA-21 I into the

  9. Vortex stabilized electron beam compressed fusion grade plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, Ady [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-03-19

    Most inertial confinement fusion schemes are comprised of highly compressed dense plasmas. Those schemes involve short, extremely high power, short pulses of beams (lasers, particles) applied to lower density plasmas or solid pellets. An alternative approach could be to shoot an intense electron beam through very dense, atmospheric pressure, vortex stabilized plasma.

  10. Thermal stability of brushite with chitosan samples

    Science.gov (United States)

    Chikanova, E. S.; Golovanova, O. A.; Malikova, T. V.; Kuimova, M. V.

    2017-01-01

    In this paper, the powders of brushite from an aqueous solution of Ca(NO3)2- (NH4)2HPO4 with different content of chitosan were synthesized. XRD data revealed that all samples are single-phase and are brushite (CaHPO4·2H2O). By FT-IR spectroscopy and BET methods, it was found that chitosan adsorbs onto the surface of powders. With increase of the content of the additive, the average size of crystallites increases 4.0 – 4.8 – 11.8 μm, respectively, and the dissolution rate in isotonic solution also decreases. The thermal stability of the composite powders was studied. It was established that the highest destruction of samples occurs in the range 473-673 K by removing of adsorption and crystallization water and partial change of the structure of the mineral and chitosan. At a temperature of 873 K, carbonization of the organic additive occurs.

  11. Free surface stability of liquid metal plasma facing components

    Science.gov (United States)

    Fiflis, P.; Christenson, M.; Szott, M.; Kalathiparambil, K.; Ruzic, D. N.

    2016-10-01

    An outstanding concern raised over the implementation of liquid metal plasma facing components in fusion reactors is the potential for ejection of liquid metal into the fusion plasma. The influences of Rayleigh-Taylor-like and Kelvin-Helmholtz-like instabilities were experimentally observed and quantified on the thermoelectric-driven liquid-metal plasma-facing structures (TELS) chamber at the University of Illinois at Urbana-Champaign. To probe the stability boundary, plasma currents and velocities were first characterized with a flush probe array. Subsequent observations of lithium ejection under exposure in the TELS chamber exhibited a departure from previous theory based on linear perturbation analysis. The stability boundary is mapped experimentally over the range of plasma impulses of which TELS is capable to deliver, and a new theory based on a modified set of the shallow water equations is presented which accurately predicts the stability of the lithium surface under plasma exposure.

  12. The effects of thermally reversible agents on PVC stability properties

    Science.gov (United States)

    Wang, J.; Yao, J.; Xiong, X. H.; Jia, C. X.; Ren, R.; Chen, P.; Liu, X. M.

    2016-07-01

    One kind of thermally reversible cross-linking agents for improving PVC thermally stability was synthesized. The chemical structure and thermally reversible characteristics of cross-linking agents were investigated by FTIR and DSC analysis, respectively. FTIR results confirmed that the cyclopentadienyl barium mercaptides ((CPD-C2H4S)2Ba) were successfully synthesized. DSC results showed it has thermally reversible characteristics and the depolymerization temperature was between 170 °C and 205 °C. The effects of cross-linking reaction time on gel content of Poly(vinyl chloride) compounds was evaluated. The gel content value arrived at 42% after being cross-linked for 25 min at 180 C. The static thermally stability measurement proved that the thermally stability of PVC compounds was improved.

  13. SELECTION OF OXIDES FOR STABILIZATION OF ZIRCONIUM DIOXIDE WHILE OBTAINING THERMAL BARRIER COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2015-01-01

    Full Text Available The paper analyzes selection of oxides and describes in details a majority of oxide systems which are applicable for stabilization of zirconium dioxide while obtaining thermal barrier coatings with maximum amount of tetragonal phase. Methodology of investigation is based on a review of analytical information on the current state of thermal barrier coatings on the basis of zirconium dioxide stabilized by oxides of rare-earth metals. The method used for application of  zirconium dioxide thermal barrier coatings is plasma spraying. Positive results have been also obtained while applying e-beam sputtering, ion-plasma deposition and magnetron sputtering. Nevertheless preferred plasma spraying application for thermal barrier coatings still continues due to its high productivity and versatility that permits to deposit metallic and ceramic materials of the ordered chemical and phase composition.Ytterbium and cerium oxides have been selected as oxides for stabilization of zirconium dioxide in order to obtain thermal barrier coatings. The paper also considers аn oxide system of zirconium dioxide: “hafnium oxide – yttrium oxide”, representing in itself the structure which is similar to zirconium dioxide.

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

    Science.gov (United States)

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

    2017-09-01

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

  15. Polyaniline Conducting Electroactive Polymers Thermal and Environmental Stability Studies

    Directory of Open Access Journals (Sweden)

    Reza Ansari

    2006-01-01

    Full Text Available In the current studies, polyaniline (PANi was prepared both chemical and electrochemically in the presence of different bronsted acids from aqueous solutions. The effect of thermal treatment on electrical conductivity, and thermal stability of the PANi conducting polymers were investigated using 4-point probe and TGA techniques respectively. It was found that polymer prepared by CV method is more thermally stable than those prepared by the other electrochemical techniques. In this paper we have also reviewed some fundamental information about synthesis, general properties, diverse applications, thermal and environmental stability of polyaniline conducting polymers.

  16. Stabilizing effect of plasma discharge on bubbling fluidized granular bed

    Science.gov (United States)

    Hu, Mao-Bin; Dang, Sai-Chao; Ma, Qiang; Xia, Wei-Dong

    2015-07-01

    Fluidized beds have been widely used for processing granular materials. In this paper, we study the effect of plasma on the fluidization behavior of a bubbling fluidized bed with an atmospheric pressure plasma discharger. Experiment results show that the bubbling fluidized bed is stabilized with the discharge of plasma. When the discharge current reaches a minimum stabilization current Cms, air bubbles in the bed will disappear and the surface fluctuation is completely suppressed. A simplified model is proposed to consider the effect of electric Coulomb force generated by the plasma. It is found that the Coulomb force will propel the particles to move towards the void area, so that the bubbling fluidized bed is stabilized with a high enough plasma discharge. Project supported by the National Natural Science Foundation of China (Grant Nos. 11035005 and 11034010).

  17. Thermal and pH Stability of Feline Calicivirus

    Science.gov (United States)

    Lee, Kyu M.; Gillespie, J. H.

    1973-01-01

    Molar concentration of sodium chloride partially stabilized feline calicivirus against thermal inactivation at 50 C. One strain of feline calicivirus was relatively acid labile compared to another. PMID:4762115

  18. Hot electron stabilization of a helically symmetric plasma

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.L.

    1986-04-01

    Furth and Boozer (private communication; Proceedings of the Advanced Bumpy Torus Concepts Workshop, CONF-830758, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1983, p. 161) have suggested the use of relativistic electrons to achieve the second stability regime in a helical axis stellarator (Heliac). The hot electrons would only be required until the background plasma reached the second stability regime; the heating power maintaining the hot electron layer would then be turned off. The basic correctness of Furth and Boozer's suggestion is confirmed numerically by a localized stability analysis of helically symmetric plasma equilibria, with anisotropic pressure profiles. Stability is evaluated using the localized interchange criterion in which the hot electrons, because of their large drift speeds, are treated as rigid. A hot electron pressure profile is exhibited; it provides a stable path to the second stability regime for the background plasma.

  19. 350℃ - Thermal Stability of Austempered Ductile Iron

    Institute of Scientific and Technical Information of China (English)

    M. Pellizzari; M. Zadra, A. Molinari

    2004-01-01

    The thermal stability of an ADI has been studied by isothermal aging at 350℃ for 150 hours, measuring the amount of retained austenite and its carbon content by X-ray diffractometry. The influence of different austempering treatments, carried out at temperatures between 300 and 450℃ (300, 330, 360, 410 and 450℃) and holding times between15 and 60 minutes (15, 30, 45, 60), was considered. Thermal stability depends on whether austempering temperature is higher or lower than the ageing one. Thermal stability increases by increasing austempering temperatures, from 300° to410℃. Samples treated at 410° and 450° show a lower austenite decomposition than samples at 300-330-360℃. A drop in stability is shown by increasing the austempering temperature from 410° to 450℃. The results have been interpreted on the basis of the austenite stability out of the processing window, which in turn depends on the austempering parameters.

  20. Stabilization of pulverized coal combustion by plasma assist

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, M.; Maruta, K.; Takeda, K.; Solonenko, O.P.; Sakashita, M.; Nakamura, M. [Akita Prefectural University, Akita (Japan). Faculty of System Science & Technology

    2002-03-01

    Ignition and stabilization of pulverized coal combustion by plasma assist is investigated with a 10 kW plasma torch for three different kinds of coal, such as high, medium and low volatile matter coals. Not only high volatile matter coal but also low quality coal can be successfully burned with plasma assist. Research for volatile component of coal shows that a higher temperature field is necessary to extract the volatile matter from inferior coal, while their compositions are almost the same.

  1. Polymer Nanofibers with Outstanding Thermal Conductivity and Thermal Stability: Fundamental Linkage between Molecular Characteristics and Macroscopic Thermal Properties

    CERN Document Server

    Zhang, Teng; Luo, Tengfei

    2014-01-01

    Polymer nanofibers with high thermal conductivities and outstanding thermal stabilities are highly desirable in heat transfer-critical applications such as thermal management, heat exchangers and energy storage. In this work, we unlock the fundamental relations between the thermal conductivity and thermal stability of polymer nanofibers and their molecular characteristics by studying the temperature-induced phase transitions and thermal transport of a series of polymer nanofibers. Ten different polymer nanofibers with systematically chosen molecular structures are studied using large scale molecular dynamics simulations. We found that high thermal conductivity and good thermal stability can be achieved in polymers with rigid backbones, exemplified by {\\pi}-conjugated polymers, due to suppressed segmental rotations and large phonon group velocities. The low probability of segmental rotation does not only prevent temperature-induced phase transition but also enables long phonon mean free paths due to reduced di...

  2. MHD equilibrium and stability in heliotron plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ichiguchi, Katsuji [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1999-09-01

    Recent topics in the theoretical magnetohydrodynamic (MHD) analysis in the heliotron configuration are overviewed. Particularly, properties of three-dimensional equilibria, stability boundary of the interchange mode, effects of the net toroidal current including the bootstrap current and the ballooning mode stability are focused. (author)

  3. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC's Non-Thermal Sanitation by Atmospheric Pressure Plasma technology sanitizes fresh fruits and vegetables without the use of consumable chemicals and without...

  4. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop a non-thermal technology based on atmospheric-pressure (AP) cold plasma to sanitize foods, food packaging materials, and other hardware...

  5. Stability of relativistic plasma-vacuum interfaces

    CERN Document Server

    Trakhinin, Yuri

    2010-01-01

    We study the plasma-vacuum interface problem in relativistic magnetohydrodynamics for the case when the plasma density does not go to zero continuously, but jumps. Unlike the nonrelativistic version of this problem, we have to assume that the plasma expands into the vacuum (otherwise, the problem is underdetermined). We show that even if this necessary condition is satisfied the planar interface can be still violently unstable. By using a suitable secondary symmetrization of the Maxwell equations in vacuum, we find a sufficient condition that precludes violent instabilities. Under this condition we derive a basic a priori estimate in the anisotropic weighted Sobolev space $H^1_*$ for the variable coefficients linearized problem for nonplanar plasma-vacuum interfaces and prove the well-posedness of this problem.

  6. Thermal stabilization of a microring modulator using feedback control.

    Science.gov (United States)

    Padmaraju, Kishore; Chan, Johnnie; Chen, Long; Lipson, Michal; Bergman, Keren

    2012-12-17

    We describe and demonstrate the use of a feedback control system to thermally stabilize a silicon microring modulator subjected to a thermally volatile environment. Furthermore, we establish power monitoring as an effective and appropriate mechanism to infer the temperature drift of a microring modulator. Our demonstration shows that a high-performance silicon microring-based device, normally inoperable in thermally volatile environments, can maintain error-free performance when a feedback control system is implemented.

  7. Stability of silanols and grafted alkylsilane monolayers on plasma-activated mica surfaces.

    Science.gov (United States)

    Liberelle, Benoît; Banquy, Xavier; Giasson, Suzanne

    2008-04-01

    We investigated the effect of physical and chemical modifications of mica surfaces induced by water vapor-based plasma treatments on the stability of silanols and grafted alkylsilane monolayers. The plasma-activated substrates were characterized using XPS, TOF-SIMS, and contact angle measurements. They revealed a large surface coverage of silanol groups (Si-OH) and a loss of aluminum atoms compared to freshly cleaved mica surfaces. The stability of plasma-induced silanol groups was investigated by contact angle measurements using ethylene glycol as a probe liquid. The Si-OH surface coverage decreased rapidly under vacuum or thermal treatment to give rise to hydrophobic dehydrated surfaces. The stability of end-grafted monofunctionalized n-alkylsilanes was investigated in different solvents and at different pH using water contact angle measurements. The degrafting of alkylsilanes from the activated mica was promoted in acidic aqueous solutions. This detachment was associated with the hydrolysis of covalent bonds between the alkylsilanes and the mica surface. The monolayer stability was enhanced by increasing the length of the alkyl chains that probably act as a hydrophobic protective layer against hydrolysis reactions. Stable alkylsilane monolayers in water with pH greater than 5.5 were obtained on mica surfaces activated at low plasma pressure. We attributed this stability to the loss of surface Al atoms induced by the plasma treatment.

  8. Synthesis of functional nanocrystallites through reactive thermal plasma processing

    Directory of Open Access Journals (Sweden)

    Takamasa Ishigaki and Ji-Guang Li

    2007-01-01

    Full Text Available A method of synthesizing functional nanostructured powders through reactive thermal plasma processing has been developed. The synthesis of nanosized titanium oxide powders was performed by the oxidation of solid and liquid precursors. Quench gases, either injected from the shoulder of the reactor or injected counter to the plasma plume from the bottom of the reactor, were used to vary the quench rate, and therefore the particle size, of the resultant powders. The experimental results are well supported by numerical analysis on the effects of the quench gas on the flow pattern and temperature field of the thermal plasma as well as on the trajectory and temperature history of the particles. The plasma-synthesized TiO2 nanoparticles showed phase preferences different from those synthesized by conventional wet-chemical processes. Nanosized particles of high crystallinity and nonequilibrium chemical composition were formed in one step via reactive thermal plasma processing.

  9. Thermal Stability of Otto Fuel Prepolymer

    Science.gov (United States)

    Tompa, Albert S.; Sandagger, Karrie H.; Bryant, William F., Jr.; McConnell, William T.; Lacot, Fernando; Carr, Walter A.

    2000-01-01

    Otto Fuel II contains a nitrate ester, plasticizer, and 2-NDPA as a stabilizer. Otto Fuel with stabilizers from three vendors was investigated by dynamic and isothermal DSC using samples sealed in a glass ampoule and by Isothermal Microcalorimetry (IMC) using 10 gram samples aged at 75 C for 35 days. DSC kinetics did not show differences between the stabilizer; the samples had an activation energy of 36.7 +/- 0.6 kcal/mol. However, IMC analysis was sensitive enough to detect small differences between the stabilizer, namely energy of interaction values of 7 to 14 Joules. DSC controlled cooling and heating at 5 C/min from 30 to -60 to 40 C experiments were similar and showed a crystallization peak at -48 +/- 1 C during cooling, and upon heating there was a glass transition temperature step at approx. -54 +/- 0.5 C and a melting peak at -28 +/- 0.4 C.

  10. Monitoring system for thermal plasma; Sistema de monitoreo para plasma termico

    Energy Technology Data Exchange (ETDEWEB)

    Romero G, M.; Vilchis P, A.E. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    In the Thermal plasma applications laboratory it has been the degradation project of oils for isolation in transformers. These are a very hazardous residues and at this time in the country they are stored in metal barrels. It has been the intention to undergo the oils to plasma for degradate them to non-hazardous residues. The system behavior must be monitored to establish the thermal plasma behavior. (Author)

  11. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    Energy Technology Data Exchange (ETDEWEB)

    Lunov, O., E-mail: lunov@fzu.cz; Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A. [Institute of Physics AS CR, Prague 18221 (Czech Republic); Deyneka, I. G.; Meshkovskii, I. K. [St. Petersburg State University of Information Technologies, Mechanics and Optics, St. Petersburg 197101 (Russian Federation); Syková, E. [Institute of Experimental Medicine AS CR, Prague 14220 (Czech Republic); Kubinová, Š. [Institute of Physics AS CR, Prague 18221 (Czech Republic); Institute of Experimental Medicine AS CR, Prague 14220 (Czech Republic)

    2015-02-02

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

  12. Electroweak absolute, meta-, and thermal stability in neutrino mass models

    Science.gov (United States)

    Lindner, Manfred; Patel, Hiren H.; Radovčić, Branimir

    2016-04-01

    We analyze the stability of the electroweak vacuum in neutrino mass models containing right-handed neutrinos or fermionic isotriplets. In addition to considering absolute stability, we place limits on the Yukawa couplings of new fermions based on metastability and thermal stability in the early Universe. Our results reveal that the upper limits on the neutrino Yukawa couplings can change significantly when the top quark mass is allowed to vary within the experimental range of uncertainty in its determination.

  13. Micellar Enzymology for Thermal, pH, and Solvent Stability.

    Science.gov (United States)

    Minteer, Shelley D

    2017-01-01

    This chapter describes methods for enzyme stabilization using micellar solutions. Micellar solutions have been shown to increase the thermal stability, as well as the pH and solvent tolerance of enzymes. This field is traditionally referred to as micellar enzymology. This chapter details the use of ionic and nonionic micelles for the stabilization of polyphenol oxidase, lipase, and catalase, although this method could be used with any enzymatic system or enzyme cascade system.

  14. Electroweak Absolute, Meta-, and Thermal Stability in Neutrino Mass Models

    CERN Document Server

    Lindner, Manfred; Radovčić, Branimir

    2015-01-01

    We analyze the stability of the electroweak vacuum in neutrino mass models containing right handed neutrinos or fermionic isotriplets. In addition to considering absolute stability, we place limits on the Yukawa couplings of new fermions based on metastability and thermal stability in the early Universe. Our results reveal that the upper limits on the neutrino Yukawa couplings can change significantly when the top quark mass is allowed to vary within the experimental range of uncertainty in its determination.

  15. On Stability of Targets for Plasma Jet Induced Magnetoinertial Fusion

    CERN Document Server

    Samulyak, Roman; Kim, Hyoungekun

    2015-01-01

    The compression and stability of plasma targets for the plasma jet-induced magneto-inertial fusion (PJMIF) have been investigated via large scale simulations using the FronTier code capable of explicit tracking of material interfaces. In the PJMIF concept, a plasma liner, formed by the merger of a large number of radial, highly supersonic plasma jets, implodes on a magnetized plasma target and compresses it to conditions of the fusion ignition. A multi-stage computational approach for simulations of the liner-target interaction and the compression of plasma targets has been developed to minimize computing time. Simulations revealed important features of the target compression process, including instability and disintegration of targets. The non-uniformity of the leading edge of the liner, caused by plasma jets as well as oblique shock waves between them, leads to instabilities during the target compression. By using front tracking, the evolution of targets has been studied in 3-dimensional simulations. Optimi...

  16. Experimental study of the thermal stability of austempered ductile irons

    Science.gov (United States)

    Pérez, M. J.; Cisneros, M. M.; Valdés, E.; Mancha, H.; Calderón, H. A.; Campos, R. E.

    2002-10-01

    A nonisothermal annealing was applied to austempered Ni-Cu-Mo alloyed and unalloyed ductile irons to determine the thermal stability of the ausferritic structure. Differential thermal analysis (DTA) results were used to build the corresponding stability diagrams. The transformation starting temperature of the high carbon austenite was found to be strongly dependent on the austempering temperature, the heating rate, and the chemical composition of the iron. The Ni-Cu-Mo alloying elements and high austempering temperature increased the stability. The transformation of the austenite to ferrite and cementite is achieved via the precipitation of transition carbides identified as silico-carbides of triclinic structure.

  17. STUDY OF THERMAL AND ACID STABILITY OF BENTONITE CLAY

    OpenAIRE

    Karna Wijaya; Ani Setyo Pratiwi; Sri Sudiono; Emi Nurahmi

    2010-01-01

    The thermal and acid stability of the bentonite clays (Na- and Ca-bentonite) have been tested. The thermal stability testing has been carried out by heating 5 gram of the clays  for five hours at 200, 300 and 500 °C respectively, meanwhile acid stability testing was performed by immersing 5 gram clays into 100 mL sulphuric acid 1M, 2M and 3M for 24 hours. The tested clays, then were characterized by means of X-Ray difractometry and IR-spectroscopy methods. The characterization results showed ...

  18. Effect of low-temperature plasma treatment on tailorability and thermal properties of wool fabrics

    Indian Academy of Sciences (India)

    V S Goud; J S Udakhe

    2011-10-01

    Dielectric barrier discharge type of plasma reactor was used for the low-temperature plasma (LTP) treatment of the wool fabrics. Air was used as the non-polymerizing gas for the plasma treatment at different time intervals. Low-stress mechanical properties of the treated and untreated wool fabrics were evaluated using Siro-fast technique which revealed that the tensile, bending, compression, shear, dimensional stability and surface properties were altered after the LTP treatment. Other properties such as thermal conductivity, thermal resistance and pilling propensity were also evaluated. The surface topographical changes of the wool fibres after LTP treatment were analysed by scanning electron microscopy. The changes in these properties are supposed to be related closely to the interfibre and interyarn frictional force and increased surface area of the fibres induced by the etching effect of plasma.

  19. Removal of Pollutants by Atmospheric Non Thermal Plasmas

    CERN Document Server

    Khacef, Ahmed; Pouvesle, Jean Michel; Van, Tiep Le

    2008-01-01

    Results on the application of non thermal plasmas in two environmentally important fields: oxidative removal of VOC and NOx in excess of oxygen were presented. The synergetic application of a plasma-catalytic treatment of NOx in excess of oxygen is also described.

  20. Current drive for stability of thermonuclear plasma reactor

    Science.gov (United States)

    Amicucci, L.; Cardinali, A.; Castaldo, C.; Cesario, R.; Galli, A.; Panaccione, L.; Paoletti, F.; Schettini, G.; Spigler, R.; Tuccillo, A.

    2016-01-01

    To produce in a thermonuclear fusion reactor based on the tokamak concept a sufficiently high fusion gain together stability necessary for operations represent a major challenge, which depends on the capability of driving non-inductive current in the hydrogen plasma. This request should be satisfied by radio-frequency (RF) power suitable for producing the lower hybrid current drive (LHCD) effect, recently demonstrated successfully occurring also at reactor-graded high plasma densities. An LHCD-based tool should be in principle capable of tailoring the plasma current density in the outer radial half of plasma column, where other methods are much less effective, in order to ensure operations in the presence of unpredictably changes of the plasma pressure profiles. In the presence of too high electron temperatures even at the periphery of the plasma column, as envisaged in DEMO reactor, the penetration of the coupled RF power into the plasma core was believed for long time problematic and, only recently, numerical modelling results based on standard plasma wave theory, have shown that this problem should be solved by using suitable parameter of the antenna power spectrum. We show here further information on the new understanding of the RF power deposition profile dependence on antenna parameters, which supports the conclusion that current can be actively driven over a broad layer of the outer radial half of plasma column, thus enabling current profile control necessary for the stability of a reactor.

  1. Thermal Stability of Rhodopsin and Progression of Retinitis Pigmentosa

    Science.gov (United States)

    Liu, Monica Yun; Liu, Jian; Mehrotra, Devi; Liu, Yuting; Guo, Ying; Baldera-Aguayo, Pedro A.; Mooney, Victoria L.; Nour, Adel M.; Yan, Elsa C. Y.

    2013-01-01

    Over 100 point mutations in the rhodopsin gene have been associated with retinitis pigmentosa (RP), a family of inherited visual disorders. Among these, we focused on characterizing the S186W mutation. We compared the thermal properties of the S186W mutant with another RP-causing mutant, D190N, and with WT rhodopsin. To assess thermal stability, we measured the rate of two thermal reactions contributing to the thermal decay of rhodopsin as follows: thermal isomerization of 11-cis-retinal and hydrolysis of the protonated Schiff base linkage between the 11-cis-retinal chromophore and opsin protein. We used UV-visible spectroscopy and HPLC to examine the kinetics of these reactions at 37 and 55 °C for WT and mutant rhodopsin purified from HEK293 cells. Compared with WT rhodopsin and the D190N mutant, the S186W mutation dramatically increases the rates of both thermal isomerization and dark state hydrolysis of the Schiff base by 1–2 orders of magnitude. The results suggest that the S186W mutant thermally destabilizes rhodopsin by disrupting a hydrogen bond network at the receptor's active site. The decrease in the thermal stability of dark state rhodopsin is likely to be associated with higher levels of dark noise that undermine the sensitivity of rhodopsin, potentially accounting for night blindness in the early stages of RP. Further studies of the thermal stability of additional pathogenic rhodopsin mutations in conjunction with clinical studies are expected to provide insight into the molecular mechanism of RP and test the correlation between rhodopsin's thermal stability and RP progression in patients. PMID:23625926

  2. On thermalization of electron-positron-photon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Siutsou, I. A., E-mail: siutsou@icranet.org [CAPES–ICRANet program, ICRANet–Rio, CBPF 22290-180, Rua Dr. Xavier Sigaud, 150, Urca, Rio de Janeiro, RJ (Brazil); Aksenov, A. G. [Institute for Computer-Aided Design, Russian Academy of Sciences 123056, 2nd Brestskaya st., 19/18, Moscow (Russian Federation); Vereshchagin, G. V. [ICRANet 65122, p.le della Republica, 10, Pescara (Italy)

    2015-12-17

    Recently a progress has been made in understanding thermalization mechanism of relativistic plasma starting from a non-equilibrium state. Relativistic Boltzmann equations were solved numerically for homogeneous isotropic plasma with collision integrals for two- and three-particle interactions calculated from the first principles by means of QED matrix elements. All particles were assumed to fulfill Boltzmann statistics. In this work we follow plasma thermalization by accounting for Bose enhancement and Pauli blocking in particle interactions. Our results show that particle in equilibrium reach Bose-Einstein distribution for photons, and Fermi-Dirac one for electrons, respectively.

  3. Analytical method for thermal stress analysis of plasma facing materials

    Science.gov (United States)

    You, J. H.; Bolt, H.

    2001-10-01

    The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed.

  4. CHEMICAL AND THERMAL STABILITY OF RICE HUSKS AGAINST ALKALI TREATMENT

    Directory of Open Access Journals (Sweden)

    Bwire S. Ndazi

    2008-11-01

    Full Text Available Chemical and thermal stability of rice husks against alkali treatment with 2 to 8% w/v NaOH are presented and discussed in this paper. The thermal stability of the rice husks was examined by using a thermal gravimetric analysis instrument. Chemical stability was evaluated by examining the organic components of rice husks using proximate analysis. The results indicated that the proportion of lignin and hemicellulose in rice husks treated with NaOH ranging from 4 to 8% decreased significantly by 96% and 74%, respectively. The thermal stability and final degradation temperatures of the alkali-treated rice husks were also lowered by 24-26°C due to degradation of hemicellulose and lignin during alkali treatment. Absence of the onset degradation zones in the alkali-treated rice husks was a further indication that hemicellulose and other volatile substances degraded during alkali treatment. This leads to a conclusion that alkali treatment of rice husks with more than 4% NaOH causes a substantial chemical degradation of rice husks, which subsequently decreases their thermal stability.

  5. Stability and energy confinement of highly elongated plasmas in TCV

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, F.; Behn, R.; Dutch, M.J.; Martin, Y.; Moret, J.M.; Nieswand, C.; Pietrzyk, Z.A.; Reimerdes, H.; Ward, D.J. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1997-06-01

    One of the principal aims of TCV is the creation and active stabilization of highly elongated plasmas, {kappa}{>=}3. This implies high growth rates of axisymmetric modes and a very low stability margin. To stabilize such modes, TCV is equipped with a vertical position control system using a combination of slow coils outside the vacuum vessel (response time {approx_equal}1 ms) and a fast coil inside the vessel (response time {approx_equal}0.2 ms). The fast coil became operational in August 1996 and this paper describes the first experiments using both fast and slow coils for vertical stabilization. (author) 4 figs., 8 refs.

  6. A Physics-Based Temperature Stabilization Criterion for Thermal Testing

    Science.gov (United States)

    Rickman, Steven L.; Ungar, Eugene K.

    2009-01-01

    Spacecraft testing specifications differ greatly in the criteria they specify for stability in thermal balance tests. Some specify a required temperature stabilization rate (the change in temperature per unit time, dT/dt), some specify that the final steady-state temperature be approached to within a specified difference, delta T , and some specify a combination of the two. The particular values for temperature stabilization rate and final temperature difference also vary greatly between specification documents. A one-size-fits-all temperature stabilization rate requirement does not yield consistent results for all test configurations because of differences in thermal mass and heat transfer to the environment. Applying a steady-state temperature difference requirement is problematic because the final test temperature is not accurately known a priori, especially for powered configurations. In the present work, a simplified, lumped-mass analysis has been used to explore the applicability of these criteria. A new, user-friendly, physics-based approach is developed that allows the thermal engineer to determine when an acceptable level of temperature stabilization has been achieved. The stabilization criterion can be predicted pre-test but must be refined during test to allow verification that the defined level of temperature stabilization has been achieved.

  7. Turbulent thermalization of the Quark Gluon Plasma

    CERN Document Server

    Berges, J; Schlichting, S; Venugopalan, R

    2013-01-01

    Classical-statistical lattice gauge theory simulations are employed to demonstrate the existence of a nonthermal fixed point in the space-time evolution of heavy ion collisions at ultrarelativistic energies. After an initial transient regime dominated by plasma instabilities and free streaming, the ensuing overpopulated non-Abelian plasma exhibits the universal self-similar dynamics characteristic of wave turbulence observed in a large variety of physical systems across different energy scales.

  8. Preparation of thermal barrier coatings by ultrasonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    WEN Xiong-wei; LI Lu-ming; ZHANG Hua-tang; HAO Hong-wei; LU Zhi-qing

    2004-01-01

    Modulated plasma arc not only can heat the powder, but also can excite ultrasonic of different frequencies and different powers. The principles and characters of the plasma arc-excited ultrasonic were described, and the ultrasonic plasma spraying was compared with normal plasma spraying. Zirconia thermal barrier coatings (TBCs) were fabricated with two kinds of method. The TBCs were studied by the optical microscope observation, SEM observation and bonding strength experiment. The results show that suitable ultrasonic changes the performance and microstructure of TBCs in evidence. And the mechanism of ultrasonic influencing the TBCs was also discussed.

  9. Stabilizing the thermal lattice Boltzmann method by spatial filtering.

    Science.gov (United States)

    Gillissen, J J J

    2016-10-01

    We propose to stabilize the thermal lattice Boltzmann method by filtering the second- and third-order moments of the collision operator. By means of the Chapman-Enskog expansion, we show that the additional numerical diffusivity diminishes in the low-wavnumber limit. To demonstrate the enhanced stability, we consider a three-dimensional thermal lattice Boltzmann system involving 33 discrete velocities. Filtering extends the linear stability of this thermal lattice Boltzmann method to 10-fold smaller transport coefficients. We further demonstrate that the filtering does not compromise the accuracy of the hydrodynamics by comparing simulation results to reference solutions for a number of standardized test cases, including natural convection in two dimensions.

  10. Thermal and mechanical stability of zeolitic imidazolate frameworks polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Bouëssel du Bourg, Lila; Ortiz, Aurélie U.; Coudert, François-Xavier, E-mail: fx.coudert@chimie-paristech.fr [PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Boutin, Anne [École Normale Supérieure, PSL Research University, Département de Chimie, Sorbonne Universités – UPMC Univ Paris 06, CNRS UMR 8640 PASTEUR, 24 rue Lhomond, 75005 Paris (France)

    2014-12-01

    Theoretical studies on the experimental feasibility of hypothetical Zeolitic Imidazolate Frameworks (ZIFs) have focused so far on relative energy of various polymorphs by energy minimization at the quantum chemical level. We present here a systematic study of stability of 18 ZIFs as a function of temperature and pressure by molecular dynamics simulations. This approach allows us to better understand the limited stability of some experimental structures upon solvent or guest removal. We also find that many of the hypothetical ZIFs proposed in the literature are not stable at room temperature. Mechanical and thermal stability criteria thus need to be considered for the prediction of new MOF structures. Finally, we predict a variety of thermal expansion behavior for ZIFs as a function of framework topology, with some materials showing large negative volume thermal expansion.

  11. Thermal and mechanical stability of zeolitic imidazolate frameworks polymorphs

    Directory of Open Access Journals (Sweden)

    Lila Bouëssel du Bourg

    2014-12-01

    Full Text Available Theoretical studies on the experimental feasibility of hypothetical Zeolitic Imidazolate Frameworks (ZIFs have focused so far on relative energy of various polymorphs by energy minimization at the quantum chemical level. We present here a systematic study of stability of 18 ZIFs as a function of temperature and pressure by molecular dynamics simulations. This approach allows us to better understand the limited stability of some experimental structures upon solvent or guest removal. We also find that many of the hypothetical ZIFs proposed in the literature are not stable at room temperature. Mechanical and thermal stability criteria thus need to be considered for the prediction of new MOF structures. Finally, we predict a variety of thermal expansion behavior for ZIFs as a function of framework topology, with some materials showing large negative volume thermal expansion.

  12. Chemical, thermal and mechanical stabilities of metal-organic frameworks

    Science.gov (United States)

    Howarth, Ashlee J.; Liu, Yangyang; Li, Peng; Li, Zhanyong; Wang, Timothy C.; Hupp, Joseph T.; Farha, Omar K.

    2016-03-01

    The construction of thousands of well-defined, porous, metal-organic framework (MOF) structures, spanning a broad range of topologies and an even broader range of pore sizes and chemical functionalities, has fuelled the exploration of many applications. Accompanying this applied focus has been a recognition of the need to engender MOFs with mechanical, thermal and/or chemical stability. Chemical stability in acidic, basic and neutral aqueous solutions is important. Advances over recent years have made it possible to design MOFs that possess different combinations of mechanical, thermal and chemical stability. Here, we review these advances and the associated design principles and synthesis strategies. We focus on how these advances may render MOFs effective as heterogeneous catalysts, both in chemically harsh condensed phases and in thermally challenging conditions relevant to gas-phase reactions. Finally, we briefly discuss future directions of study for the production of highly stable MOFs.

  13. Thermal stability of silicon nanowires:atomistic simulation study

    Institute of Scientific and Technical Information of China (English)

    Liu Wen-Liang; Zhang Kai-Wang; Zhong Jian-Xin

    2009-01-01

    Using the Stillinger-Weber (SW) potential model, we investigate the thermal stability of pristine silicon nanowires based on classical molecular dynamics (MD) simulations. We explore the structural evolutions and the Lindemann indices of silicon nanowires at different temperatures in order to unveil atomic-level melting behaviour of silicon nanowires.The simulation results show that silicon nanowires with surface reconstructions have higher thermal stability than those without surface reconstructions, and that silicon nanowires with perpendicular dimmer rows on the two (100) surfaces have somewhat higher thermal stability than nanowires with parallel dimmer rows on the two (100) surfaces. Furthermore, the melting temperature of silicon nanowires increases as their diameter increases and reaches a saturation value close to the melting temperature of bulk silicon. The value of the Lindemann index for melting silicon nanowires is 0.037.

  14. Thermal and radiation resistance of stabilized LDPE

    Energy Technology Data Exchange (ETDEWEB)

    Zaharescu, T., E-mail: traian_zaharescu@yahoo.co [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); Jipa, S. [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); ' Valahia' University of Targoviste, Faculty of Sciences, Targoviste 130024 (Romania); Henderson, D. [Trinity College, Hartford, CT 06106 (United States); Kappel, W. [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); Maris, D.A.; Maris, M. [' Ovidius' University, 7 Ilarie Voronca St, P.O. Box 8700, Constanta (Romania)

    2010-03-15

    The effect of capsaicin on the radiation stability of low density polyethylene was accomplished by applying the chemiluminescence procedure. The neat and modified polymer with 0.25% and 0.50% (w/w) capsaicin were exposed to gamma-irradiation in air receiving 10, 20 and 30 kGy. The synergistic effect due to the presence of metallic selenium was demonstrated. The significant improvement in oxidation induction time was obtained demonstrating the efficient antioxidant activity of capsaicin in LDPE. The simultaneous protection action of metallic selenium in LDPE/capsaicin systems brought about a supplementary enhancement in the oxidation resistance of irradiated samples.

  15. Thermal Stability Analysis for a Heliocentric Gravitational Radiation Detection Mission

    Science.gov (United States)

    Folkner, W.; McElroy, P.; Miyake, R.; Bender, P.; Stebbins, R.; Supper, W.

    1994-01-01

    The Laser Interferometer Space Antenna (LISA) mission is designed for detailed studies of low-frequency gravitational radiation. The mission is currently a candidate for ESA's post-Horizon 2000 program. Thermal noise affects the measurement in at least two ways. Thermal variation of the length of the optical cavity to which the lasers are stabilized introduces phase variations in the interferometer signal, which have to be corrected for by using data from the two arms separately.

  16. Study on the thermal stability of styrene butadiene rubber nanocomposites

    Science.gov (United States)

    Saeb, M. R.; Chenari, T. N.; Parast, O. Yazdan; Jafari, B.; Asadi, H.; Safari, M. Arfavi; Holisaz, H.

    2012-07-01

    This study aims to investigate the thermal stability of the styrene butadiene rubber (SBR) nanocomposites containig surface modified calcium carbonate (MCC). All nanocomposites were produced at various nanofiller contents, utilizing a laboratory scale two-roll mill. The thermal stability parameters including initial decomposing temperature, temperature at maximum rate of weight loss, and char content of the MCC/SBR nanocomposites were then compared. It was found that by increasing the filler content, the decomposition temperature of MCC/SBR nanocomposites increases. Furthermore, the char content at high temperatures rises by increasing nanofiller content.

  17. Novel Antimicrobial Organic Thermal Stabilizer and Co-Stabilizer for Rigid PVC

    Directory of Open Access Journals (Sweden)

    Nadia A. Mohamed

    2012-07-01

    Full Text Available Biologically active N-benzoyl-4-(N-maleimido-phenylhydrazide (BMPH was synthesized and its structure was confirmed by elemental analysis and various spectral tools. It was examined as a thermal stabilizer and co-stabilizer for rigid poly (vinyl chloride at 180 °C in air. Blending BMPH with reference samples in different ratios greatly lengthens the thermal stability value and improves the extent of discoloration of PVC. TGA confirmed the improved stability of PVC in presence of the investigated organic stabilizer. GPC measurements were done to investigate the changes occurred in the molecular masses of the degraded samples of blank PVC and PVC in presence of the novel stabilizer. BMPH showed good antimicrobial activity towards two kinds of bacteria and two kinds of fungi.

  18. Thermal stability of Cryptococcus albidus α-L-rhamnosidase

    Directory of Open Access Journals (Sweden)

    O. V. Gudzenko

    2015-06-01

    Full Text Available Yeast as well as micromycetes α-L-rhamnosidases, currently, are the most promising group of enzymes. Improving of the thermal stability of the enzyme preparation are especially important studies. Increase in stability and efficiency of substrate hydrolysis by α-L-rhamnosidase will improve the production technology of juices and wines. The aim of our study was to investigate the rate of naringin hydrolysis by α-L-rhamnosidase from Cryptococcus albidus, and also some aspects of the thermal denaturation and stabilization of this enzyme. We investigated two forms of α-L-rhamnosidase from C. albidus, which were obtained by cultivation of the producer on two carbon sources – naringin and rhamnose. A comparative study of properties and the process of thermal inactivation of α-L-rhamnosidases showed that the inducer of synthesis had no effect on the efficiency of naringin hydrolysis by the enzyme, but modified thermal stability of the protein molecule. Hydrophobic interactions and the cysteine residues are involved in maintaining of active conformation of the α-L-rhamnosidase molecule. Yeast α-L-rhamnosidase is also stabilized by 0.5% bovine serum albumin and 0.25% glutaraldehyde.

  19. Nanodomain stabilization dynamics in plasma membranes of biological cells

    Science.gov (United States)

    Das, Tamal; Maiti, Tapas K.; Chakraborty, Suman

    2011-02-01

    We discover that a synergistically amplifying role of stabilizing membrane proteins and continuous lipid recycling can explain the physics governing the stability, polydispersity, and dynamics of lipid raft domains in plasma membranes of biological cells. We establish the conjecture using a generalized order parameter based on theoretical formalism, endorsed by detailed scaling arguments and domain mapping. Quantitative agreements with morphological distributions of raft complexes, as obtained from Förster resonance energy transfer based visualization, support the present theoretical conjecture.

  20. Noise and thermal stability of vibrating micro-gyrometers preamplifiers

    CERN Document Server

    Levy, R; Mathias, H; Gilles, J -P; Parrain, F; Eisenbeis, B; Megherbi, S

    2008-01-01

    The preamplifier is a critical component of gyrometer's electronics. Indeed the resolution of the sensor is limited by its signal to noise ratio, and the gyrometer's thermal stability is limited by its gain drift. In this paper, five different kinds of preamplifiers are presented and compared. Finally, the design of an integrated preamplifier is shown in order to increase the gain stability while reducing its noise and size.

  1. Degradation Behavior of Thermal Stabilized Polyacrylonitrile Fibers

    Directory of Open Access Journals (Sweden)

    LEI Shuai

    2017-05-01

    Full Text Available In the temperature range of 300-800℃, 40%-50% of the mass lost during the processing of polyacrylonitrile based carbon fiber (PANCF. Understanding the degradation behavior will be valuable in understanding the formation mechanism of pseudo-graphite structure, and providing theoretic basis for producing high performance carbon fiber and increasing the carbonization yield. The simulation of the degradation progress was carried out on the thermogravimetric analyzer (TGA, the results show that there are two degradation steps for PAN fiber stabilized in air, and controlled by cyclization coefficient and oxygen content. The cyclization coefficient and oxygen content are effective to the density of carbon fiber by influencing the degradation behavior, which cause defects in the fiber. The higher cyclization coefficient leads to form less structural defects and higher density of the fiber; on the contrary, the higher oxygen content leads to form more structural defects and lower density of the fiber.

  2. On the cause of low thermal stability of ethyl halodiazoacetates

    Science.gov (United States)

    Mortén, Magnus; Hennum, Martin

    2016-01-01

    Summary Rates for the thermal decomposition of ethyl halodiazoacetates (halo = Cl, Br, I) have been obtained, and reported herein are their half-lives. The experimental results are supported by DFT calculations, and we provide a possible explanation for the reduced thermal stability of ethyl halodiazoacetates compared to ethyl diazoacetate and for the relative decomposition rates between the chloro, bromo and iodo analogs. We have also briefly studied the thermal, non-catalytic cyclopropanation of styrenes and compared the results to the analogous Rh(II)-catalyzed reactions. PMID:27559411

  3. Thermal Stability of Nanoporous Raney Gold Catalyst

    Directory of Open Access Journals (Sweden)

    Matthew C. Tai

    2015-07-01

    Full Text Available Nanoporous “Raney gold” sponge was prepared by de-alloying an Au-Al precursor alloy. Catalytic tests using a micro-reactor confirmed that Raney gold can serve as an active heterogeneous catalyst for CO oxidation, reduction of NO to N2, and oxidation of NO to NO2. In general, the specific surface area of a heterogeneous catalyst has an influence on its catalytic efficacy. Unfortunately, gold sponges coarsen readily, leading to sintering of their structure and reduction in surface area. This potentially places constraints on their upper operating temperature in catalytic reactors. Here we analyzed the behavior of Raney gold when the temperature was raised. We examined the kinetics and mechanism of coarsening of the sponge using a combination of in situ optical measurements and Metropolis Monte Carlo modeling with a Lennard-Jones interatomic potential. Modeling showed that the sponges started with an isotropic “foamy” morphology with negative average “mean curvature” but that subsequent thermally activated coarsening will drive the morphology through a bi-continuous fibrous state and on, eventually, to a sponge consisting of sintered blobs of predominantly positive “mean curvature”.

  4. Modeling of pulverized coal combustion stabilization by means of plasma torches

    Energy Technology Data Exchange (ETDEWEB)

    Miroslav Sijercic; Srdjan Belosevic; Predrag Stefanovic [VINCA Institute of Nuclear Science, Belgrade (Serbia and Montenegro)

    2005-07-01

    Application of plasma-system for pulverized coal ignition and combustion stabilization in utility boiler furnaces promises to achieve certain savings compared to the use of heavy oil burners. Plasma torches are built in air-coal dust mixture ducts between coal mills and burners. Characteristics of processes in the ducts with plasma-system for pulverized coal combustion stabilization are analyzed in the paper, with respect to the modeling and numerical simulation of mass, momentum and heat transfer in two-phase turbulent gas particle flow. The simulations have been performed for three different geometries of the air-coal dust mixture ducts with plasma torches, for TENT A1 utility boiler and pulverized lignite Kolubara-Field 'D'. Selected results of numerical simulation of processes are presented. The plasma-system thermal effect is discussed regarding corresponding savings of liquid fuel. The results of numerical simulations have been analyzed with respect to the processes in the duct and especially with respect to the influence of the duct shape to a temperature field at the out let cross section, as a basis for the duct geometry optimization. It has been emphasized that numerical simulation of processes can be applied in analysis and optimization of pulverized coal ignition and combustion stabilization and enables efficient and cost-effective scaling-up procedure from laboratory to industrial level. 22 refs., 4 figs.

  5. Stability of catecholamines in whole blood, plasma, and platelets.

    Science.gov (United States)

    Weir, T B; Smith, C C; Round, J M; Betteridge, D J

    1986-05-01

    Checking catecholamine stability in whole blood, plasma, and platelets, we found that specimens stored at room temperature or frozen for periods ranging from 1.5 h to three weeks show no significant difference in measured catecholamine concentration. The implications of these findings are discussed.

  6. Stability of plasma treated superhydrophobic surfaces under different ambient conditions.

    Science.gov (United States)

    Chen, Faze; Liu, Jiyu; Cui, Yao; Huang, Shuai; Song, Jinlong; Sun, Jing; Xu, Wenji; Liu, Xin

    2016-05-15

    Plasma hydrophilizing of superhydrophobic substrates has become an important area of research, for example, superhydrophobic-(super)hydrophilic patterned surfaces have significant practical applications such as lab-on-chip systems, cell adhesion, and control of liquid transport. However, the stability of plasma-induced hydrophilicity is always considered as a key issue since the wettability tends to revert back to the untreated state (i.e. aging behavior). This paper focuses on the stability of plasma treated superhydrophobic surface under different ambient conditions (e.g. temperature and relative humidity). Water contact angle measurement and X-ray photoelectron spectroscopy are used to monitor the aging process. Results show that low temperature and low relative humidity are favorable to retard the aging process and that pre-storage at low temperature (-10°C) disables the treated surface to recover superhydrophobicity. When the aging is performed in water, a long-lasting hydropholicity is obtained. As the stability of plasma-induced hydrophilcity over a desired period of time is a very important issue, this work will contribute to the optimization of storage conditions of plasma treated superhydrophobic surfaces.

  7. High energy density Z-pinch plasmas using flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  8. Thermal stability of liquid antioxidative extracts from pomegranate peel

    Science.gov (United States)

    This research was carried out to assess the potential of using the natural antioxidants in pomegranate peel extracts as replacement for synthetic antioxidants. As a result the thermal stability of pomegranate peel extract products during sterilization and storage, and its effect on industrial, color...

  9. Thermal stability of substitutional ag in CdTe

    NARCIS (Netherlands)

    Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

    1996-01-01

    The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the channelin

  10. Method for enhancing the thermal stability of ionic compounds

    DEFF Research Database (Denmark)

    2013-01-01

    This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA....

  11. Method for enhancing the thermal stability of ionic compounds

    OpenAIRE

    Riisager, Anders; Fehrmann, Rasmus; Robin, Roger; Gabriela, Gurau

    2013-01-01

    This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA.

  12. Thermal stability of substitutional ag in CdTe

    NARCIS (Netherlands)

    Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

    1996-01-01

    The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the channelin

  13. Can green solvents be alternatives for thermal stabilization of collagen?

    Science.gov (United States)

    Mehta, Ami; Rao, J Raghava; Fathima, Nishter Nishad

    2014-08-01

    "Go Green" campaign is gaining light for various industrial applications where water consumption needs to be reduced. To resolve this, industries have adopted usage of green, organic solvents, as an alternative to water. For leather making, tanning industry consumes gallons of water. Therefore, for adopting green solvents in leather making, it is necessary to evaluate its influence on type I collagen, the major protein present in the skin matrix. The thermal stability of collagen from rat tail tendon fiber (RTT) treated with seven green solvents namely, ethanol, ethyl lactate, ethyl acetate, propylene carbonate, propylene glycol, polyethylene glycol-200 and heptane was determined using differential scanning calorimetry (DSC). Crosslinking efficiency of basic chromium sulfate and wattle on RTT in green solvents was determined. DSC thermograms show increase in thermal stability of RTT collagen against heat with green solvents (>78°C) compared to water (63°C). In the presence of crosslinkers, RTT demonstrated thermal stability >100°C in some green solvents, resulting in increased intermolecular forces between collagen, solvent and crosslinkers. The significant improvement in thermal stability of collagen potentiates the capability of green solvents as an alternative for water.

  14. Gyrokinetic stability theory of electron-positron plasmas

    CERN Document Server

    Helander, Per

    2016-01-01

    The linear gyrokinetic stability properties of magnetically confined electron-positron plasmas are investigated in the parameter regime most likely to be relevant for the first laboratory experiments involving such plasmas, where the density is small enough that collisions can be ignored and the Debye length substantially exceeds the gyroradius. Although the plasma beta is very small, electromagnetic effects are retained, but magnetic compressibility can be neglected. The work of a previous publication (Helander, 2014) is thus extended to include electromagnetic instabilities, which are of importance in closed-field-line configurations, where such instabilities can occur at arbitrarily low pressure. It is found that gyrokinetic instabilities are completely absent if the magnetic field is homogeneous: any instability must involve magnetic curvature or shear. Furthermore, in dipole magnetic fields, the stability threshold for interchange modes with wavelengths exceeding the Debye radius coincides with that in i...

  15. Lanthanide phosphonates: Synthesis, thermal stability and magnetic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Amghouz, Z., E-mail: amghouz.uo@uniovi.es [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Garcia, J.R.; Garcia-Granda, S. [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Clearfield, A. [Department of Chemistry, Texas A and M University, College Station, TX 77842-3012 (United States); Rodriguez Fernandez, J.; Pedro, I. de [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Report of the complete series of lanthanide 1,4-phenylbis(phosphonate). Black-Right-Pointing-Pointer Synthesis under conventional hydrothermal synthesis or microwave-assisted hydrothermal synthesis. Black-Right-Pointing-Pointer Cation size is the key factor for the structural and particles size variations. Black-Right-Pointing-Pointer Thermal behaviour is characterized by unusual very high thermal stability. - Abstract: Series of novel organic-inorganic hybrids materials based on trivalent lanthanides (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and 1,4-phenylbis(phosphonate) obtained under hydrothermal conditions either by oven heat or microwave irradiation. The anhydrous compounds containing La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho, are isostructural. However, the compounds based on Y, Er, Tm, Yb, and Lu are hydrated and their structures have not yet been solved. The series of compounds are characterized by PXRD, TEM, SEM-EDX and thermal analyses (TG-MS and DSC). TEM study show a variable particles size with a minimum mean-particle size of ca. 30 nm. These compounds exhibit unusual very high thermal stability. The size of particles and the thermal stability are depending on lanthanide(III) cation features. All the investigated materials show paramagnetic behaviour. The magnetic susceptibility data follow a Curie-Weiss laws with paramagnetic effective moments in good agreement with those expected for Ln{sup 3+} free ions.

  16. Thermal Conductivity and Water Vapor Stability of Ceramic HfO2-Based Coating Materials

    Science.gov (United States)

    Zhu, Dong-Ming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

    2004-01-01

    HfO2-Y2O3 and La2Zr2O7 are candidate thermal/environmental barrier coating materials for gas turbine ceramic matrix composite (CMC) combustor liner applications because of their relatively low thermal conductivity and high temperature capability. In this paper, thermal conductivity and high temperature phase stability of plasma-sprayed coatings and/or hot-pressed HfO2-5mol%Y2O3, HfO2-15mol%Y2O3 and La2Zr2O7 were evaluated at temperatures up to 1700 C using a steady-state laser heat-flux technique. Sintering behavior of the plasma-sprayed coatings was determined by monitoring the thermal conductivity increases during a 20-hour test period at various temperatures. Durability and failure mechanisms of the HfO2-Y2O3 and La2Zr2O7 coatings on mullite/SiC Hexoloy or CMC substrates were investigated at 1650 C under thermal gradient cyclic conditions. Coating design and testing issues for the 1650 C thermal/environmental barrier coating applications will also be discussed.

  17. Grain boundary engineering to enhance thermal stability of electrodeposited nickel

    DEFF Research Database (Denmark)

    Alimadadi, Hossein

    by miniaturization of the grains down to nano-meter scale. However, this augments the total grain boundary energy stored in the material, hence, making the material less thermally stable. Coherent twin boundaries are of very low energy and mobility compared to all other boundaries in a FCC material. Accordingly......Manufacturing technologies such as injection molding and micro electromechanical systems demand materials with improved mechanical properties (e.g. hardness, ductility) and high durability at elevated temperatures. Significant improvement in some of the mechanical properties is obtained......, grain boundary engineering of electrodeposited nickel to achieve high population of coherent twin boundaries and, hence, higher thermal stability is a promising method to achieve simultaneous improvement in mechanical properties and thermal stability. This is of particular scientific and practical...

  18. Thermal stability assessment of anti-explosive ammonium nitrate

    Institute of Scientific and Technical Information of China (English)

    Lijin Shen; Xuguang Wang

    2005-01-01

    The explosivity experiment of anti-explosive ammonium nitrate (AEAN) shows that the explosive characteristic of AEAN is eliminated. The adiabatic decompositions of ammonium nitrate and AEAN were investigated with an accelerating rate calorimeter (ARC). The curves of thermal decomposition temperature and pressure versus time, self-heating rate and pressure versus temperature for two systems were obtained. The kinetic parameters such as apparent activation energy and pre-exponential factor were calculated.The safety of AEAN was analyzed. It was indicated that AEAN has a higher thermal stability than AN. At the same time, it can be shown that the elimination of its explosive characteristic is due to the improvement on the thermal stability of AEAN.

  19. Thermal stability analysis of the liquid phase methanol synthesis reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gogate, M.R.; Desirazu, S.; Berty, J.M.; Lee, S. (Akron University, Akron, OH (USA). Dept. of Chemical Engineering)

    1992-01-01

    The effect of addition of an inert liquid phase on the rate of heat generation in the catalytic synthesis of methanol from syngas has been studied. Gas compositions typical of product gases from Lurgi and Koppers-Totzek gasifiers, represented by H[sub 2]-rich and CO-rich syngas respectively, were used to experimentally verify the 'slope' and 'dynamic' criteria in a three-phase fixed bed recycle reactor. The liquid medium, Witco-40 oil, has been effective in controlling the rate of heat generation and in preventing catalyst overheating, signifying that the liquid phase synthesis is thermally far more stable than the vapour phase synthesis. The experimental thermal stability study provides crucial and valuable information in commercializing the liquid phase methanol synthesis process. The current approach of thermal stability analysis does not require any a priori assumption or predetermined reaction kinetics. 22 refs., 6 figs., 7 tabs.

  20. Network and guest dependent thermal stability and thermal expansion in a trigonal host

    Indian Academy of Sciences (India)

    Viswanadha G Saraswatula; Mukhtar Ahmad Bhat; Suman Bhattacharya; Binoy K Saha

    2014-09-01

    Thermal stability and thermal expansion of bromo trimer synthon mediated hexagonal inclusion compounds of 2,4,6-tris(4-bromophenoxy)-1,3,5-triazine (BrPOT) with dichloromethane (DCM), tetrahydrofuran (THF) and hexamethyl benzene (HMB) and also the guest-free form of BrPOT are reported. Each of these three guests produced two concomitant inclusion compounds with BrPOT. The thermal stability of the solvate lattice increases with decreasing cavity size. The channel network of the DCM inclusion compound is stable only for a few seconds at room temperature outside the mother liquor, whereas the cage network of the DCM solvate is stable for months under similar conditions. Thermal expansions of the lattices depend upon the network, guest content as well as the type of guest molecules. The guest-free form exhibits the least thermal expansion in this series of systems.

  1. Thermal analysis and stability of commercially available endodontic obturation materials.

    Science.gov (United States)

    Roberts, H W; Kirkpatrick, T C; Bergeron, B E

    2017-02-10

    The purpose of this study was to evaluate the thermal stability of 23 commercially-available endodontic obturation materials. Specimens (n = 10) were sealed in aluminum differential scanning calorimetry (DSC) crucibles and subjected to thermal scan series consisting of a 25 to 70 °C at 5 °C/min followed by a rapid increase to 230 °C, followed by a second scan from 25 to 70 °C at 5 °C/min. The first scan evaluated the materials as-received followed by a worse-case-scenario thermal challenge simulating temperatures involved with warm vertical condensation obturation techniques. The second thermal scan observed any phase changes from the high temperature challenge. This two-scan process was repeated twice to observe changes encountered by repeat high heat exposure during obturation. Mean thermal enthalpies were analyzed with Kruskal-Wallis and Games-Howell post-hoc test. (p = 0.05). Thermal behavior was material dependent. During the first thermal scan, materials typically demonstrated broad endothermic enthalpy curves suggesting either a gutta-percha phase mixture and/or an alpha crystalline phase. The first high-heat challenge produced definitive alpha/beta thermal phase signatures usually associated with gutta-percha. Changes in beta-phase enthalpies were noted with Therarmafil Plus and UltraFil Firmset while increase in alpha-phases was observed with GuttaCore, K3, Lexicon, and Schein Accessory Points. Commercial endodontic gutta-percha obturation materials displayed thermal characteristics that were material dependent. However, all demonstrated stability at temperatures in excess to that experienced during warm vertical condensation techniques. The gutta-percha obturation materials evaluated in this evaluation can be used successfully in warm vertical condensation techniques without fear of degradation.

  2. Thermal condensation mode in a dusty plasma

    Indian Academy of Sciences (India)

    B P Pandey; J Vranješ; S Parhi

    2003-03-01

    In the present work, the radiative condensation instability is investigated in the presence of dust charge fluctuations. We find that the charge variability of the grain reduces the growth rate of radiative mode only for fluctuation wavelength smaller or of the order of the Debye length and this reduction is not very large. Far from the Debye sphere, radiative mode can damp due to thermal conduction of electrons and ions.

  3. Non-thermal plasma treatment of hydrogen sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Frost, L.J.; Hartvigsen, J.; Elangovan, S. [Ceramatec Inc., Salt Lake City, UT (United States)

    2009-07-01

    This paper described a non-thermal plasma reforming process to treat hydrogen sulfide (H{sub 2}S) in heavy hydrocarbons. H{sub 2}S is present in natural gas, petroleum, and various process gases. It is an unwanted compound that is generally removed using an amine extraction process followed by a Claus process. Ceramatec Inc. has developed a GlidArc plasma reformer to recover some of the hydrogen from the H{sub 2}S. Non-thermal plasma reforming breaks hydrogen sulfide into hydrogen and elemental sulphur. Ceramatec has established the catalytic nature of the non-thermal plasma generated by its GlidArc plasma reformer. This treatment process is still in the laboratory stage, but it offers the possibility of a new method to treat acid gas that will provide an opportunity to recover hydrogen that is currently burned to water during the Claus sulphur removal process. Ceramatec, in conjunction with Albin Czernichowski of ECP in France, has demonstrated the ability to reform a variety of hydrocarbons using the non-thermal plasma catalyzed reaction. The plasma reaction can be initiated in either a partial oxidation or steam reforming mode. Multiple hydrocarbons can be processed by the same unit with only control parameters changing to meet the requirements of the individual hydrocarbons being processed. Although a tested unit did not accomplish complete conversion, some additional options will be tested that are expected to increase the conversion under an existing program operated by the United States Department of Energy. 4 refs., 9 figs.

  4. Rotation and plasma stability in the Fitzpatrick-Aydemir model

    Science.gov (United States)

    Pustovitov, V. D.

    2007-08-01

    The rotational stabilization of the resistive wall modes (RWMs) is analyzed within the single-mode cylindrical Fitzpatrick-Aydemir model [R. Fitzpatrick, Phys. Plasmas 9, 3459 (2002)]. Here, the consequences of the Fitzpatrick-Aydemir dispersion relation are derived in terms of the observable growth rate and toroidal rotation frequency of the mode, which allows easy interpretation of the results and comparison with experimental observations. It is shown that this model, developed for the plasma with weak dissipation, predicts the rotational destabilization of RWM in the typical range of the RWM rotation. The model predictions are compared with those obtained in a similar model, but with the Boozer boundary conditions at the plasma surface [A. H. Boozer, Phys. Plasmas 11, 110 (2004)]. Simple experimental tests of the model are proposed.

  5. Plasma circulating fibrinogen stability and moderate beer consumption.

    Science.gov (United States)

    Gorinstein, Shela; Caspi, Abraham; Zemser, Marina; Libman, Imanuel; Goshev, Ivan; Trakhtenberg, Simon

    2003-12-01

    MODERATE BEER CONSUMPTION (MBC) IS CARDIOPROTECTIVE: it positively influences plasma lipid levels and plasma antioxidant activity in beer-consuming individuals. The connection between MBC and blood coagulation is not clearly defined. Forty-two volunteers were equally divided into experimental (EG) and control (CG) groups following coronary bypass surgery. For 30 consecutive days, only patients of the EG consumed 330 mL of beer per day (about 20 g of alcohol). A comprehensive clinical investigation of 42 patients was done. Blood samples were collected before and after the investigation for a wide range of laboratory tests. The plasma fibrinogen was denatured with 8 M urea and intrinsic fluorescence (IF), hydrophobicity and differential scanning calorimetry (DSC) were used to reveal possible qualitative changes. After 30 days of moderate beer consumption, positive changes in the plasma lipid levels, plasma anticoagulant and plasma antioxidant activities were registered in patients of the EG group. In 17 out of 21 patients of the same group, differences in plasma circulating fibrinogen's (PCF), secondary and tertiary structures were found. The stability of fibrinogen, expressed in thermodynamic parameters, has shown that the loosening of the structure takes place under ethanol and urea denaturation. Also fluorescence stability of PCF was decreased. No changes in the lipid levels, anticoagulant and antioxidant activity or changes in PCF were detected in patients of CG. In conclusion, for the first time after a short term of moderate beer consumption some qualitative changes in the plasma circulating fibrinogen were detected: differences in the emission peak response, fluorescence intensity and all thermodynamic data. Together, with the decrease in the PCF concentration it may lead to an elevation of the blood anticoagulant activity.

  6. Interaction of electromagnetic and plasma waves in warm motional plasma: Density and thermal effects

    Science.gov (United States)

    Rashed-Mohassel, P.; Hasanbeigi, A.; Hajisharifi, K.

    2017-08-01

    In this paper, the electromagnetic-electrostatic coupling instability excited in the two-dimensional planar-layered plasma medium with median temperature (warm motional plasma beam) is investigated by applying the initial fluctuation propagating along the planar surfaces. The dielectric tensor, obtained by the Maxwell-fluid model, is used to find the dispersion relation (DR) and different excited modes in the system. Interacting modes are investigated, in detail, by focusing on the effect of temperature on the plasma beam instability aroused by coupling the thermal excited modes (thermal-extraordinary and electron plasma modes) in the systems with various amounts of beam density. The numerical analysis of the obtained DR shows that even though the temperature effect of the plasma beam has an important role on the suppression of streaming instabilities, it does not have a considerable effect on the behavior of the coupling instability in the fluid limitation.

  7. Carbon Dioxide Reforming of Methane to Syngas by Thermal Plasma

    Institute of Scientific and Technical Information of China (English)

    孙艳朋; 聂勇; 吴昂山; 姬登祥; 于凤文; 计建炳

    2012-01-01

    Experiments were conducted on syngas preparation from dry reforming of methane by carbon dioxide with a DC arc plasma at atmospheric pressure. In all experiments, nitrogen gas was used as the working gas for thermal plasma to generate a high-temperature jet into a horizontal tube reactor. A mixture of methane and carbon dioxide was fed vertically into the jet. In order to obtain a higher conversion rate of methane and carbon dioxide, chemical energy efficiency and fuel production efficiency, parametric screening studies were conducted, in which the volume ratio of carbon dioxide to methane in fed gases and the total flux of fed gases were taken into account. Results showed that carbon dioxide reforming of methane to syngas by thermal plasma exhibited a larger processing capacity, higher conversion of methane and carbon dioxide and higher chemical energy efficiency and fuel production efficiency. In addition, thermodynamic simulation for the reforming process was conducted. Experimental data agreed well with the thermodynamic results, indicating that high thermal efficiency can be achieved with the thermal plasma reforming process.

  8. Thermal Plasma Synthesis of Superparamagnetic Iron Oxide Nanoparticles

    NARCIS (Netherlands)

    Lei, P.Y.; Boies, A.M.; Calder, S.A.; Girshick, S.L.

    2012-01-01

    Superparamagnetic iron oxide nanoparticles were synthesized by injecting ferrocene vapor and oxygen into an argon/helium DC thermal plasma. Size distributions of particles in the reactor exhaust were measured online using an aerosol extraction probe interfaced to a scanning mobility particle sizer,

  9. Internal Transport Barrier Broadening through Subdominant Mode Stabilization in Reversed Field Pinch Plasmas

    Science.gov (United States)

    Lorenzini, R.; Auriemma, F.; Fassina, A.; Martines, E.; Terranova, D.; Sattin, F.

    2016-05-01

    The reversed field pinch (RFP) device RFX-mod features strong internal transport barriers when the plasma accesses states with a single dominant helicity. Such transport barriers enclose a hot helical region with high confinement whose amplitude may vary from a tiny one to an amplitude encompassing an appreciable fraction of the available volume. The transition from narrow to wide thermal structures has been ascribed so far to the transport reduction that occurs when the dominant mode separatrix, which is a preferred location for the onset of stochastic field lines, disappears. In this Letter we show instead that the contribution from the separatrix disappearance, by itself, is marginal and the main role is instead played by the progressive stabilization of secondary modes. The position and the width of the stochastic boundary encompassing the thermal structures have been estimated by applying the concept of a 3D quasiseparatrix layer, developed in solar physics to treat reconnection phenomena without true separatrices and novel to toroidal laboratory plasmas. Considering the favorable scaling of secondary modes with the Lundquist number, these results open promising scenarios for RFP plasmas at temperatures higher than the presently achieved ones, where lower secondary modes and, consequently, larger thermal structures are expected. Furthermore, this first application of the quasiseparatrix layer to a toroidal plasma indicates that such a concept is ubiquitous in magnetic reconnection, independent of the system geometry under investigation.

  10. Stability of Alfvén wings in uniform plasmas

    Science.gov (United States)

    Sallago, P. A.; Platzeck, A. M.

    2007-12-01

    A conducting source moving uniformly through a magnetized plasma generates, among a variety of perturbations, Alfvén waves. An interesting characteristic of Alfvén waves is that they can build up structures in the plasma called Alfvén wings. These wings have been detected and measured in many solar system bodies, and their existence has also been theoretically proven. However, their stability remains to be studied. The aim of this paper is to analyze the stability of an Alfvén wing developed in a uniform background field, in the presence of an incompressible perturbation that has the same symmetry as the Alfvén wing, in the magnetohydrodynamic approximation. The study of the stability of a magnetohydrodynamic system is often performed by linearizing the equations and using either the normal modes method or the energy method. In spite of being applicable for many problems, both methods become algebraically complicated if the structure under analysis is a highly non-uniform one. Palumbo has developed an analytical method for the study of the stability of static structures with a symmetry in magnetized plasmas, in the presence of incompressible perturbations with the same symmetry as the structure (Palumbo 1998 Thesis, Universidad de Firenze, Italia). In the present paper we extend this method for Alfvén wings that are stationary structures, and conclude that in the presence of this kind of perturbation they are stable.

  11. Antitumor action of non thermal plasma sources, DBD and Plasma Gun, alone or in combined protocols

    Science.gov (United States)

    Robert, Eric; Brullé, Laura; Vandamme, Marc; Riès, Delphine; Le Pape, Alain; Pouvesle, Jean-Michel

    2012-10-01

    The presentation deals with the assessment on two non thermal plasma sources developed and optimized for oncology applications. The first plasma source is a floating-electrode dielectric barrier discharge powered at a few hundreds of Hz which deliver air-plasma directly on the surface of cell culture medium in dishes or on the skin or organs of mice bearing cancer tumors. The second plasma source, so called Plasma Gun, is a plasma jet source triggered in noble gas, transferred in high aspect ratio and flexible capillaries, on targeting cells or tumors after plasma transfer in air through the ``plasma plume'' generated at the capillary outlet. In vitro evidence for massive cancer cell destruction and in vivo tumor activity and growth rate reductions have been measured with both plasma sources. DNA damages, cell cycle arrests and apoptosis induction were also demonstrated following the application of any of the two plasma source both in vitro and in vivo. The comparison of plasma treatment with state of the art chemotherapeutic alternatives has been performed and last but not least the benefit of combined protocols involving plasma and chemotherapeutic treatments has been evidenced for mice bearing orthotopic pancreas cancer and is under evaluation for the colon tumors.

  12. Edge and divertor plasma: detachment, stability, and plasma-wall interactions

    Science.gov (United States)

    Krasheninnikov, S. I.; Kukushkin, A. S.; Lee, Wonjae; Phsenov, A. A.; Smirnov, R. D.; Smolyakov, A. I.; Stepanenko, A. A.; Zhang, Yanzeng

    2017-10-01

    The paper presents an overview of the results of studies on a wide range of the edge plasma related issues. The rollover of the plasma flux to the target during progressing detachment process is shown to be caused by the increase of the impurity radiation loss and volumetric plasma recombination, whereas the ion-neutral friction, although important for establishing the necessary edge plasma conditions, does not contribute per se to the rollover of the plasma flux to the target. The processes limiting the power loss by impurity radiation are discussed and a simple estimate of this limit is obtained. Different mechanisms of meso-scale thermal instabilities driven by impurity radiation and resulting in self-sustained oscillations in the edge plasma are identified. An impact of sheared magnetic field on the dynamics of the blobs and ELM filaments playing an important role in the edge and SOL plasma transport is discussed. Trapping of He, which is an intrinsic impurity for the fusion plasmas, in the plasma-facing tungsten material is considered. A newly developed model, accounting for the generation of additional He traps caused by He bubble growth, fits all the available experimental data on the layer of nano-bubbles observed in W under irradiation by low energy He plasma.

  13. Preparation of spherical hollow alumina particles by thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonkyung [Department of Chemical Engineering, INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Regional Innovation Center for Environmental Technology of Thermal Plasma (RIC-ETTP), INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Choi, Sooseok [Center for Advance Research in Fusion Reactor Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151‐742 (Korea, Republic of); Oh, Seung-Min [Daejoo Electronic Materials Co., 1236‐10 Jeongwang-dong, Siheung-si, Kyunggi-do 429‐848 (Korea, Republic of); Park, Dong-Wha, E-mail: dwpark@inha.ac.kr [Department of Chemical Engineering, INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Regional Innovation Center for Environmental Technology of Thermal Plasma (RIC-ETTP), INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of)

    2013-02-01

    Spherical hollow particles were prepared from solid alumina powders using DC arc thermal plasma, and then spray coating was performed with the as-prepared particles. Operating variables for the hollow particle preparation process were additional plasma gas, input power, and carrier gas flow rate. The spherical hollow alumina particles were produced in the case of using additive gas of H{sub 2} or N{sub 2}, while alumina surface was hardly molten in the pure argon thermal plasma. In addition, the hollow particles were well produced in high power and low carrier gas conditions due to high melting point of alumina. Hollow structure was confirmed by focused ion beam-scanning electron microscopy analysis. Morphology and size distribution of the prepared particles that were examined by field emission-scanning electron microscopy and phase composition of the particles was characterized by X-ray diffraction. In the spray coating process, the as-prepared hollow particles showed higher deposition rate. - Highlights: ► Spherical hollow alumina powder was prepared by non-transferred DC arc plasma. ► Diatomic gasses were added in Ar plasma for high power. ► Prepared hollow alumina powder was efficient for the plasma spray coating.

  14. Photoacoustic thermal characterization of lime-partially stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, M.E.; Serrato, J.; Zarate, J.; Pacheco, C.; Villasenor, L. [Univ. Michoacana, Morelia Michoacan (Mexico)

    1997-01-01

    Photoacoustic and photothermal techniques are used to investigate the room-temperature thermophysical properties of 9.4 mol% lime-partially stabilized zirconia (C-PSZ) samples in the density range of 5.12 {times} 10{sup 3}--5.58 {times} 10{sup 3}kg/m{sup 3}. The open-photoacoustic-cell approach is used to measure thermal diffusivity, and the photothermal technique of continuous illumination of the sample in vacuum is used to measure the product of density and specific heat capacity. Thermal conductivity is shown to be the thermophysical parameter most sensitive to changes in porosity.

  15. Morphology, thermal stability and thermal degradation kinetics of cellulose-modified urea–formaldehyde resin

    Indian Academy of Sciences (India)

    M A ARSHAD; A MAAROUFI; G PINTO; S EL-BARKANY; A ELIDRISSI

    2016-10-01

    This article reports a study on the structural characterization and evaluation of thermal degradation kinetics of urea–formaldehyde resin modified with cellulose, known as UFC resin. Structural characterization of UFC undertaken by scanning electron microscopy, Fourier transform infrared and X-ray diffractionanalyses reveals that the resin is fairly homogenous, and it constitutes of partly crystalline structure including urea–formaldehyde/cellulose interface morphology different from UFC precursors. Measurement of inherent thermal stability, probing reaction complexity and the thermal degradation kinetic analysis of UFC have been carried out by thermogravimetric/differential thermal analyses (TGA/DTA) under non-isothermal conditions. The integral proceduredecomposition temperature elucidates significant thermal stability of UFC. TGA/DTA analyses suggest highly complicated reaction profile for thermal degradation of UFC, comprising various parallel/consecutive reactions.Different differential and integral isoconversional methods have been employed to determine the thermal degradation activation energy of UFC. Substantial variation in activation energy with the advancement of reaction verifiesmulti-step reaction pathway of UFC. A plausible interpretation of the obtained kinetic parameters of UFC thermal degradation with regard to their physical meanings is given and discussed in this study.

  16. Preparation of SrZrO3 Thermal Barrier Coating by Solution Precursor Plasma Spray

    Science.gov (United States)

    Li, Xinhui; Ma, Wen; Wen, Jing; Bai, Yu; Sun, Li; Chen, Baodong; Dong, Hongying; Shuang, Yingchai

    2017-02-01

    The solution precursor plasma spray (SPPS) process is capable of depositing highly durable thermal barrier coatings (TBCs). In this study, an aqueous chemical precursor feedstock was injected into the plasma jet to deposit SrZrO3 thermal barrier coating on metal substrate. Taguchi design of experiments was employed to optimize the SPPS process. The thermal characteristics and phase evolution of the SrZrO3 precursor, as well as the influence of various spray parameters on the coating deposition rate, microhardness, microstructure, and phase stability, were investigated. The experimental results showed that, at given spray distance, feedstock flow rate, and atomization pressure, the optimized spray parameters were arc current of 600 A, argon flow rate of 40 L/min, and hydrogen flow rate of 10 L/min. The SrZrO3 coating prepared using the optimized spray parameters had single-pass thickness of 6.0 μm, porosity of 18%, and microhardness of 6.8 ± 0.1 GPa. Phase stability studies indicated that the as-sprayed SrZrO3 coating had good phase stability in the temperature range from room temperature to 1400 °C, gradually exhibiting a phase transition from t'-ZrO2 to m-ZrO2 in the SrZrO3 coating at 1450 °C with increasing time, while the SrZrO3 phase did not change.

  17. Thermal stability analysis of the fine structure of solar prominences

    Science.gov (United States)

    Demoulin, Pascal; Malherbe, Jean-Marie; Schmieder, Brigitte; Raadu, Mickael A.

    1986-01-01

    The linear thermal stability of a 2D periodic structure (alternatively hot and cold) in a uniform magnetic field is analyzed. The energy equation includes wave heating (assumed proportional to density), radiative cooling and both conduction parallel and orthogonal to magnetic lines. The equilibrium is perturbed at constant gas pressure. With parallel conduction only, it is found to be unstable when the length scale 1// is greater than 45 Mn. In that case, orthogonal conduction becomes important and stabilizes the structure when the length scale is smaller than 5 km. On the other hand, when the length scale is greater than 5 km, the thermal equilibrium is unstable, and the corresponding time scale is about 10,000 s: this result may be compared to observations showing that the lifetime of the fine structure of solar prominences is about one hour; consequently, our computations suggest that the size of the unresolved threads could be of the order of 10 km only.

  18. Structure and Thermal Stability of Copper Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Guangan Zhang

    2013-01-01

    Full Text Available Copper nitride (Cu3N thin films were deposited on glass via DC reactive magnetron sputtering at various N2 flow rates and partial pressures with 150°C substrate temperature. X-ray diffraction and scanning electron microscopy were used to characterize the microstructure and morphology. The results show that the films are composed of Cu3N crystallites with anti-ReO3 structure. The microstructure and morphology of the Cu3N film strongly depend on the N2 flow rate and partial pressure. The cross-sectional micrograph of the film shows typical columnar, compact structure. The thermal stabilities of the films were investigated using vacuum annealing under different temperature. The results show that the introducing of argon in the sputtering process decreases the thermal stability of the films.

  19. Stability analysis of collisionless plasmas with specularly reflecting boundary

    CERN Document Server

    Nguyen, Toan

    2011-01-01

    In this paper we provide sharp criteria for linear stability or instability of equilibria of collisionless plasmas in the presence of boundaries. Specifically, we consider the relativistic Vlasov-Maxwell system with specular reflection at the boundary for the particles and with the perfectly conducting boundary condition for the electromagnetic field. Here we initiate our investigation in the simple geometry of radial and longitudinal symmetry.

  20. Thermal stability of -amylase in aqueous cosolvent systems

    Indian Academy of Sciences (India)

    Jay Kant Yadav; V Prakash

    2009-09-01

    The activity and thermal stability of -amylase were studied in the presence of different concentrations of trehalose, sorbitol, sucrose and glycerol. The optimum temperature of the enzyme was found to be 50 ± 2°C. Further increase in temperature resulted in irreversible thermal inactivation of the enzyme. In the presence of cosolvents, the rate of thermal inactivation was found to be significantly reduced. The apparent thermal denaturation temperature ()app and activation energy () of -amylase were found to be significantly increased in the presence of cosolvents in a concentration-dependent manner. In the presence of 40% trehalose, sorbitol, sucrose and glycerol, increments in the ()app were 20°C, 14°C, 13°C and 9°C, respectively. The of thermal denaturation of -amylase in the presence of 20% (w/v) trehalose, sorbitol, sucrose and glycerol was found to be 126, 95, 90 and 43 kcal/mol compared with a control value of 40 kcal/mol. Intrinsic and 8-anilinonaphathalene-1-sulphonic acid (ANS) fluorescence studies indicated that thermal denaturation of the enzyme was accompanied by exposure of the hydrophobic cluster on the protein surface. Preferential interaction parameters indicated extensive hydration of the enzyme in the presence of cosolvents.

  1. Dependence of thermal stability of lithiated Si on particle size

    Science.gov (United States)

    Li, Chao; Shi, Tongfei; Li, Decheng; Yoshitake, Hideya; Wang, Hongyu

    2016-12-01

    Thermal properties of the component materials are key issues in lithium ion batteries (LIBs). Si-based anodes are one of the most promising materials, but its thermal evolution have received much less attention than its electrochemical performance. In this article, the thermal behavior of various of Si material has been studied by differential scanning calorimetry (DSC). Three kinds of Si-particles, ranging from nano-to micro-sizes was subject to thermal analysis. It has been found that the thermal stability increases with the rise in particle-size. For the nanoparticles of 20 nm, both characteristic peaks of A and B regions in the heating process are stronger than the large-diameter particles. For three kinds of Si particles, the starting temperature of thermal reaction demonstrates a similar trend, gradually becoming lower with the increasing of the lithiation extent. At last, the ex situ XPS has also been conducted to explore the causes of surface state after temperature elevation. In A region, the heating decomposition of SEI with electrolyte, mainly consisting of a variety of esterification compounds, produces high content of lithium carbonate below 180 °C. When lithium in the inner phase of Si particles loses the protection of SEI film, the severe exothermic reaction occurred between lithium and the solvent species.

  2. Equilibrium and stability code for a diffuse plasma.

    Science.gov (United States)

    Betancourt, O; Garabedian, P

    1976-04-01

    A computer code to investigate the equilibrium and stability of a diffuse plasma in three dimensions is described that generalizes earlier work on a sharp free boundary model. Toroidal equilibria of a plasma are determined by considering paths of steepest descent associated with a new version of the variational principle of magnetohydrodynamics that involves mapping a fixed coordinate domain onto the plasma. A discrete approximation of the potential energy is written down following the finite element method, and the resulting expression is minimized with respect to the values of the mapping at points of a rectangular grid. If a relative minimum of the discrete analogue of the energy is attained, the corresponding equilibrium is considered to be stable.

  3. Stability analysis of tokamak plasmas; Analyse de stabilite de plasmas de tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Bourdelle, C

    2000-10-01

    In a tokamak plasma, the energy transport is mainly turbulent. In order to increase the fusion reactions rate, it is needed to improve the energy confinement. The present work is dedicated to the identification of the key parameters leading to plasmas with a better confined energy in order to guide the future experiments. For this purpose, a numerical code has been developed. It calculates the growth rates characterizing the instabilities onset. The stability analysis is completed by the evaluation of the shearing rate of the rotation due to the radial electric field. When this shearing rate is greater than the growth rate the ion turbulence is fully stabilised. The shearing rate and the growth rate are determined from the density, temperature and security factor profiles of a given plasma. Three types of plasmas have been analysed. In the Radiative Improved modes of TEXTOR, high charge number ions seeding lowers the growth rates. In Tore Supra-high density plasmas, a strong magnetic shear and/or a more efficient ion heating linked to a bifurcation of the toroidal rotation direction (which is not understood) trigger the improvement of the confinement. In other Tore Supra plasmas, locally steep electron pressure gradients have been obtained following magnetic shear reversal. This locally negative magnetic shear has a stabilizing effect. In these three families of plasmas, the growth rates decrease, the confinement improves, the density and temperature profiles are steeper. This steepening induces an increase of the rotation shearing rate, which then maintains the confinement high quality. (author)

  4. Characterization of thermal and current quench of JET plasmas

    Science.gov (United States)

    Riccardo, V.; Barabaschi, P.; Loarte, A.; Sugihara, M.

    2004-11-01

    JET provides crucial scaling points and unique physics access for the extrapolation of disruptions to ITER. Disruption and ELM heat loads influence the selection of materials for plasma facing components (PFCs). Most JET thermal quenches occur when the plasma thermal energy is less than half that at full performance, suggesting a more optimistic life expectancy for ITER PFCs. The exceptions are ITB collapses and pure VDEs, which are also more likely to lead to the shortest thermal quenches. For the fast current quench disruptions, the EM load due to the induced eddy currents represent the most severe electromechanical design condition for in-vessel components. The minimum linear decay time normalised to the plasma cross section extrapolates to a 40 ms disruption for ITER, based on data from JET and most other tokamaks. Some very fast JET events are better fit by an exponential, with the minimum characteristic current decay time scaling to 35 ms for ITER. Contrary to expectations, the quench rate of high and low thermal energy disruptions does not vary substantially.

  5. Stability of caffeic acid phenethyl amide (CAPA) in rat plasma.

    Science.gov (United States)

    Yang, John; Kerwin, Sean M; Bowman, Phillip D; Stavchansky, Salomon

    2012-05-01

    A validated C₁₈ reverse-phase HPLC method with UV detection at 320 nm was developed and used for the stability evaluation of caffeic acid phenethyl amide (CAPA) and caffeic acid phenethyl ester (CAPE) in rat plasma. CAPA is the amide derivative of CAPE, a naturally occurring polyphenolic compound that has been found to be active in a variety of biological pathways. CAPA has been shown to protect endothelial cells against hydrogen peroxide-induced oxidative stress to a similar degree to CAPE. CAPE has been reported to be rapidly hydrolyzed in rat plasma via esterase enzymes. CAPA is expected to display a longer half-life than CAPE by avoiding hydrolysis via plasma esterases. The stability of CAPA and CAPE in rat plasma was investigated at three temperatures. The half-lives for CAPA were found to be 41.5, 10 and 0.82 h at 25, 37 and 60 °C, respectively. The half-lives for CAPE were found to be 1.95, 0.35 and 0.13 h at 4, 25 and 37 °C, respectively. The energy of activation was found to be 22.1 kcal/mol for CAPA and 14.1 kcal/mol for CAPE. A more stable compound could potentially extend the beneficial effects of CAPE.

  6. Vortex Stabilized Plasma for Rapid Water Disinfection & Pharmaceutical Degradation

    Science.gov (United States)

    Hershcovitch, Ady

    2016-10-01

    Good quality drinking water is dwindling for large segments of the world population. Aggravating the problem is proliferation of antibiotics in the water supply, which give rise to drug resistant pathogens. One option for water supply increase is recycling waste and polluted water by inexpensive, environmentally friendly methods. Presently disinfection uses chemicals and UV radiation. Chemicals are limited by residual toxicity, while UV consumes much electricity. Current methods can remove only certain classes of drugs due to their large variety of physical and chemical properties. Plasmas in water are very attractive for degrading all pharmaceuticals and deactivating pathogens: intense arc current can physically break up any molecular bonds. UV radiation, ozone, etc. generation inside the water volume disinfects. Present utilized plasmas: glow, pulsed arcs are not power efficient; vortex stabilized plasmas are power efficient that can advance water treatment state-of-the-art by orders of magnitude. Proposed techniquefeatures novel components facilitating large diameter vortex stabilized in-water arcs with optimized plasma parameters for maximal UV-C emission; and harvests hydrogen centered by the vortex.

  7. Thermal stability of segmented polyurethane elastomers reinforced by clay particles

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2009-01-01

    Full Text Available The aim of this work was to determine the influence of clay nanoparticles on thermal properties of segmented polyurethanes based on hexamethylene- diisocyanate, aliphatic polycarbonate diol and 1,4-butanediol as chain extender. The organically modified particles of montmorillonite and bentonite were used as reinforcing fillers. The structure of elastomeric materials was varied either by diol type or chain extender content. The ratio of OH groups from diol and chain extender (R was either 1 or 10. Thermal properties of prepared materials were determined using modulated differential scanning calorimetry (MDSC. Thermal stability of obtained elastomers has been studied by simultaneously thermogravimetry coupled with DSC. The glass transition temperature, Tg, of soft segments for all investigated samples was about -33°C. On the basis of DTG results, it was concluded that obtained materials were very stable up to 300°C.

  8. Stability of thermal structures with an internal heating source

    CERN Document Server

    Sanchez, Nestor

    2008-01-01

    We study the thermal equilibrium and stability of isobaric, spherical structures having a radiation source located at its center. The thermal conduction coefficient, external heating and cooling rates are represented as power laws of the temperature. The internal heating decreases with distance from the source r approximately as exp(-tau)/(r**2), being tau the optical depth. We find that the influence of the radiation source is important only in the central region, but its effect is enough to make the system thermally unstable above a certain threshold central temperature. This threshold temperature decreases as the internal heating efficiency increases, but, otherwise, it does not depend on the structure size. Our results suggest that a solar-like star migrating into a diffuse interstellar region may destabilize the surrounding medium.

  9. Thermal Stability of Large Al-stabilized Superconducting Magnets Theoritical Analysis of CMS Solenoid.

    CERN Document Server

    Juster, F P

    1998-01-01

    The CMS detector magnet presently under design for the future Large Hadron Collider at CERN is an epoxy-impregnated structure, indirectly cooled by two-phase flow liquid helium. This magnet, based on aluminum-stabilized, mechanically reinforced conductor, is not cryostable : the heat generated by a thermal disturbance can be removed only by thermal diffusivity through the windings. In order to study the thermal stability of the magnet, we have developed numerical codes able to predict the thermal behaviour of an anisotropic and non-homogeneous medium against thermal perturbations due to friction or epoxy cracking. Our 3D finite element codes can calculate the propagation or the recovery of a normal zone in a superconducting magnet, taking into account the current diffusion effect, which strongly affects the heat generated by a transition in the case of large Al-stabilized conductors. Two different codes, CASTEM 2000 and HEATING are described in this paper. We present the results of the CMS Solenoid magnet sta...

  10. Flexible all-carbon photovoltaics with improved thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chun; Ishihara, Hidetaka; Sodhi, Jaskiranjeet; Chen, Yen-Chang; Siordia, Andrew; Martini, Ashlie; Tung, Vincent C., E-mail: ctung@ucmerced.edu

    2015-04-15

    The structurally robust nature of nanocarbon allotropes, e.g., semiconducting single-walled carbon nanotubes (SWCNTs) and C{sub 60}s, makes them tantalizing candidates for thermally stable and mechanically flexible photovoltaic applications. However, C{sub 60}s rapidly dissociate away from the basal of SWCNTs under thermal stimuli as a result of weak intermolecular forces that “lock up” the binary assemblies. Here, we explore use of graphene nanoribbons (GNRs) as geometrically tailored protecting layers to suppress the unwanted dissociation of C{sub 60}s. The underlying mechanisms are explained using a combination of molecular dynamics simulations and transition state theory, revealing the temperature dependent disassociation of C{sub 60}s from the SWCNT basal plane. Our strategy provides fundamental guidelines for integrating all-carbon based nano-p/n junctions with optimized structural and thermal stability. External quantum efficiency and output current–voltage characteristics are used to experimentally quantify the effectiveness of GNR membranes under high temperature annealing. Further, the resulting C{sub 60}:SWCNT:GNR ternary composites display excellent mechanical stability, even after iterative bending tests. - Graphical abstract: The incorporation of solvent resistant, mechanically flexible and electrically addressable 2-D soft graphene nanoribbons facilitates the assembly of photoconductive carbon nano-p/n junctions for thermally stable and flexible photovoltaic cells.

  11. Thermal stability of the C106 dye in robust electrolytes

    DEFF Research Database (Denmark)

    Lund, Torben; Phuong, Nguyen Tuyet; Pechy, Peter

    Thermal stability of the C106 dye in robust electrolytes. We have investigated the thermal stability and degradation chemistry of the ruthenium dye C106 (Figure 1) at 80 ◦C in the “robust” electrolyte “B” comprised of 1.0 M DMII, 0.03 M I2, 0.5 M NBB, and 0.1 M GuNCS in 3-methoxypropionitrile (3......-MPN) introduced by Gao et al. in 2008. [1]. Figure 1 Thermal degradation of C106 bound to TiO2 at 80 ºC in dark as a function of heating time. ● C106 = RuLL´(NCS)2 ■ RuLL´(NCS)(NBB)+ ▲ RuLL´(NCS)(3-MPN)+ The C106 dye was attached to the surface of TiO2 nano-particles and stable colloidal solutions...... of the particles were prepared in electrolyte mixture B. The solutions were thermally treated at 80 ◦C for 0-2000 hours followed by dye extraction and analysis by HPLC coupled to UV/Vis and electro spray mass spectrometry [2]. Figure 1 shows the concentration profiles of C106 samples prepared under ambient...

  12. Thermal cycling characteristics of plasma synthesized mullite films

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, O.R.; Hou, P.Y.; Brown, I.G. [Lawrence Berkeley National Lab., CA (United States)

    1997-12-01

    The authors have developed a plasma-based technique for the synthesis of mullite and mullite-like films on silicon carbide substrate material. The method, which they refer to as MePIIID (for Metal Plasma Immersion Ion Implantation and Deposition), uses two vacuum arc plasma sources and simultaneous pulse biasing of the substrate in a low pressure oxygen atmosphere. The Al:Si ratio can be controlled via the separate plasma guns, and the film adhesion, structure and morphology can be controlled via the ion energy which in turn is controlled by the pulse bias voltage. The films are amorphous as-deposited, and crystalline mullite is formed by subsequent annealing at 1000 C for 2 hours in air. Adhesion between the aluminum-silicon oxide film and the substrate increases after this first annealing. They have tested the behavior of films when subjected to repetitive thermal cycling between room temperature and 1100 C, and found that the films retain their adhesion and quality. Here they review the plasma synthesis technique and the characteristics of the mullite films prepared in this way, and summarize the status of the thermal cycling experiments.

  13. Thermomechanical behavior of plasma-sprayed zirconia thermal barrier coatings.

    Energy Technology Data Exchange (ETDEWEB)

    Singh, J. P.

    1998-04-01

    The effect of coating porosity and thickness on the resistance to damage of yttria stabilized zirconia thermal barrier coatings in an oxidizing environment by thermal cycling was evaluated. Hardness and elastic modulus of an as-processed porous coating were lower than those of a dense coating and the porous coating failed after fewer thermal cycles. Similarly, specimen with a thicker coating failed after fewer thermal cycles than specimen with a thinner coating. The earlier failure of the porous coating is due to lower fracture toughness and enhanced oxidation of the coating/substrate interface, whereas, the earlier failure of the thick coating is due to higher thermal transient stresses that developed in the coating during thermal cycling. Generally, an increase in coating density led to initial increase in both hardness and elastic modulus with increasing thermal cycles. However, hardness and density gradually decreased as the number of thermal cycles increase because of microcracks formation and growth. Microscopic observations indicated that the formation of multiple microcracks and their subsequent growth and coalescence led to final coating failure.

  14. Scandia-and-Yttria-Stabilized Zirconia for Thermal Barriers

    Science.gov (United States)

    Mess, Derek

    2003-01-01

    yttria in suitable proportions has shown promise of being a superior thermal- barrier coating (TBC) material, relative to zirconia stabilized with yttria only. More specifically, a range of compositions in the zirconia/scandia/yttria material system has been found to afford increased resistance to deleterious phase transformations at temperatures high enough to cause deterioration of yttria-stabilized zirconia. Yttria-stabilized zirconia TBCs have been applied to metallic substrates in gas turbine and jet engines to protect the substrates against high operating temperatures. These coatings have porous and microcracked structures, which can accommodate strains induced by thermal-expansion mismatch and thermal shock. The longevity of such a coating depends upon yttria as a stabilizing additive that helps to maintain the zirconia in an yttria-rich, socalled non-transformable tetragonal crystallographic phase, thus preventing transformation to the monoclinic phase with an associated deleterious volume change. However, at a temperature greater than about 1,200 C, there is sufficient atomic mobility that the equilibrium, transformable zirconia phase is formed. Upon subsequent cooling, this phase transforms to the monoclinic phase, with an associated volume change that adversely affects the integrity of the coating. Recently, scandia was identified as a stabilizer that could be used instead of, or in addition to, yttria. Of particular interest are scandia-and-yttria-stabilized zirconia (SYSZ) compositions of about 6 mole percent scandia and 1 mole percent yttria, which have been found to exhibit remarkable phase stability at a temperature of 1,400 C in simple aging tests. Unfortunately, scandia is expensive, so that the problem becomes one of determining whether there are compositions with smaller proportions of scandia that afford the required high-temperature stability. In an attempt to solve this problem, experiments were performed on specimens made with reduced

  15. Thermal Stability of Poly (acrylonitrile-methyl acrylate) Copolymers

    Institute of Scientific and Technical Information of China (English)

    HAN Na; ZHANG Xing-xiang; WANG Xue-chen

    2008-01-01

    Poly (acrylonitrile-methyl acrylate) copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1 - 3 wt% lauryl alcohol maleic anhydride (LAM) was adopted as stabilizer to mix with the acrylonitrile based copolymer. The mixtures were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H NMR ), Gel Permeation Chromatography ( GPC ), Differential Scanning Calorimetry (DSC), optic microscope and Ubbelohde viscosimetryr etc. The melting point (Tm) and glass transition temperature (Tg) of the 85/15 AN/MA copolymer mixed with LAM all decrease with the increase of stabilizer content. The lowest Tg and Tm were 116.1 ℃ and 209. 1℃ respectively at the heating rate of 100℃/min when the content of LAM is 2 wt%. The 85°/15 AN/MA copolymer mixed with 1 - 3 w t% LAM possess good thermal stability up to 30 min at 220 ℃.

  16. Thermal Stability of RP-2 for Hydrocarbon Boost Regenerative Cooling

    Science.gov (United States)

    Kleinhenz, Julie E.; Deans, Matthew C.; Stiegemeier, Benjamin R.; Psaras, Peter M.

    2013-01-01

    A series of tests were performed in the NASA Glenn Research Centers Heated Tube Facility to study the heat transfer and thermal stability behavior of RP-2 under conditions similar to those found in rocket engine cooling channels. It has long been known that hydrocarbon fuels, such as RP-2, can decompose at high temperature to form deposits (coke) which can adversely impact rocket engine cooling channel performance. The heated tube facility provides a simple means to study these effects. Using resistively heated copper tubes in a vacuum chamber, flowing RP-2 was heated to explore thermal effects at a range of test conditions. Wall temperature (850-1050F) and bulk fluid temperature (300-500F) were varied to define thermal decomposition and stability at each condition. Flow velocity and pressure were fixed at 75 fts and 1000 psia, respectively. Additionally, five different batches of RP-2 were tested at identical conditions to examine any thermal stability differences resulting from batch to batch compositional variation. Among these tests was one with a potential coke reducing additive known as 1,2,3,4-Tetrahydroquinoline (THQ). While copper tubes were used for the majority of tests, two exploratory tests were performed with a copper alloy known as GRCop-42. Each tube was instrumented with 15 thermocouples to examine the temperature profile, and carbon deposition at each thermocouple location was determined post-test in an oxidation furnace. In many tests, intermittent local temperature increases were observed visually and in the thermocouple data. These hot spots did not appear to correspond with a higher carbon deposition.

  17. Enhancement of thermal stability in microwave applicators by mismatching and detuning

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, E.M.

    1996-07-01

    Many microwave applicator systems experiencing thermal runaway can be stabilized by mismatching and/or detuning the system. The stability of the systems is discussed qualitatively and a conservative guide for adjusting microwave applicators for enhanced stability is described.

  18. Pre-treating water with non-thermal plasma

    Science.gov (United States)

    Cho, Young I.; Fridman, Alexander; Rabinovich, Alexander; Cho, Daniel J.

    2017-07-04

    The present invention consists of a method of pre-treatment of adulterated water for distillation, including adulterated water produced during hydraulic fracturing ("fracking") of shale rock during natural gas drilling. In particular, the invention is directed to a method of treating adulterated water, said adulterated water having an initial level of bicarbonate ion in a range of about 250 ppm to about 5000 ppm and an initial level of calcium ion in a range of about 500 ppm to about 50,000 ppm, said method comprising contacting the adulterated water with a non-thermal arc discharge plasma to produce plasma treated water having a level of bicarbonate ion of less than about 100 ppm. Optionally, the plasma treated water may be further distilled.

  19. Mechanism of NO reduction with non-thermal plasma

    Institute of Scientific and Technical Information of China (English)

    YU Gang; YU Qi; JIANG Yan-long; ZENG Ke-si; GU Fan

    2005-01-01

    Non-thermal plasma has been proved to be an effective and competitive technology for removing NO in flue gas since 1970. In this paper, the NO reduction mechanism of the non-thermal plasma reaction in NO/N2/O2 system was investigated using the method of spectral analysis and quantum chemistry. By the establishment of NO reduction and gas discharge plasma emission spectrum measuring system, the NO reduction results, gas discharge emission spectra of NO/N2O2 and pure N2 were obtained, and then the model of molecular orbit of N2 either in ground state or its excited state was worked out using the method of molecular orbit Ab initio in SelfConsistent Field(SCF). It was found that NO reduction in NO/N2 gas discharge plasma was achieved mainly through a series of fast elementary reactions and the N(E6) at excited state was the base for NO reduction.

  20. Review of mercury removal from flue gas using non-thermal plasma technology

    Directory of Open Access Journals (Sweden)

    Tao Zhu

    2014-06-01

    Full Text Available Mercury with various constituents in flue gas produced by burning coal could be an attractive alternative to non-thermal plasma process for mercury control. The mechanism of removal for pollutants using non-thermal plasma technology and the electric discharge form of non-thermal plasma are introduced. Then, we summary the research progress of mercury removal by non-thermal plasma in recent years, especially focus on how to oxide the elemental mercury from flue gas. We hope the non-thermal plasma technology can be improved to apply in the industry in the near future.

  1. Thermal stability, optical property, and morphology of flexible organoclay films.

    Science.gov (United States)

    Shin, Jieun; Chang, Jin-Hae

    2011-07-01

    Novel organo-saponite (organo-SPT) films with excellent thermal stability and optical property were synthesized by solution casting. Na ion-exchanged saponite (pristine SPT), hexadecylammonium ion-exchanged SPT (C16-SPT), hexadecyltriphenyl phosphonium ion-exchanged SPT (C16PPh3-SPT), and tetraphenyl phosphonium ion-exchanged SPT (PPh4-SPT) were used to prepare clay films. We examined the relationship between the structures and properties of the various SPT films. SPT films were examined by means of wide-angle X-ray diffraction (XRD), electronic microscopy (FE-SEM), thermogravimetric analysis (TGA), ultraviolet-visible (UV-vis.) spectrometer. On the basis of these analyses, we sought to improve both the thermal stability and the optical properties. Clay films composed of C16PPh3-SPT and PPh4-SPT were found to be more thermally stable than those composed of pristine SPT or C16-SPT. On the other hand, the transmittance was not significantly affected by variations in the organo-SPT material.

  2. Preparation, Thermal Stability and Electrochemical Properties of LiODFB

    Institute of Scientific and Technical Information of China (English)

    Hongming Zhou; Furong Liu; Jian Li

    2012-01-01

    Lithium oxalyldifluoroborate (LiODFB) was synthesized in dimethyl carbonate solvent and purified by the method of solvent-out crystallization. The structure characterization and thermal stability of LiODFB were performed by Fourier transform infrared (FTIR) spectrometry, nuclear magnetic resonance (NMR) spectrometry and thermogravimetric analyzer (TGA). LiODFB was exposed to 50% humid air at 25 ℃for different time, then dried at 80 ℃ for 12 h, and the electrochemical properties of the cells using 1 mol/L dried LiODFB in ethylene carbonate -I- dimethyl carbonate + ethyl(methyl)carbonate were investigated. The results showed that, pure crystallization LiODFB was obtained; it had good thermal stability with a thermal decomposition temperature of 248 ℃; when it was exposed to humid air, it was firstly converted into LiODFB.H20; with increasing exposure time, more and stronger impurity peaks in the X-ray diffraction (XRD) patterns of LiODFB were observed, and both the discharge specific capacity and the capacity retention decreased gradually.

  3. Flexible all-carbon photovoltaics with improved thermal stability

    Science.gov (United States)

    Tang, Chun; Ishihara, Hidetaka; Sodhi, Jaskiranjeet; Chen, Yen-Chang; Siordia, Andrew; Martini, Ashlie; Tung, Vincent C.

    2015-04-01

    The structurally robust nature of nanocarbon allotropes, e.g., semiconducting single-walled carbon nanotubes (SWCNTs) and C60s, makes them tantalizing candidates for thermally stable and mechanically flexible photovoltaic applications. However, C60s rapidly dissociate away from the basal of SWCNTs under thermal stimuli as a result of weak intermolecular forces that "lock up" the binary assemblies. Here, we explore use of graphene nanoribbons (GNRs) as geometrically tailored protecting layers to suppress the unwanted dissociation of C60s. The underlying mechanisms are explained using a combination of molecular dynamics simulations and transition state theory, revealing the temperature dependent disassociation of C60s from the SWCNT basal plane. Our strategy provides fundamental guidelines for integrating all-carbon based nano-p/n junctions with optimized structural and thermal stability. External quantum efficiency and output current-voltage characteristics are used to experimentally quantify the effectiveness of GNR membranes under high temperature annealing. Further, the resulting C60:SWCNT:GNR ternary composites display excellent mechanical stability, even after iterative bending tests.

  4. Macromolecular Crowding Enhances Thermal Stability of Rabbit Muscle Creatine Kinase

    Institute of Scientific and Technical Information of China (English)

    ZHU Jiang; HE Huawei; LI Sen

    2008-01-01

    The effect of dextran on the conformation (or secondary structure) and thermal stability of creatine kinase (CK) was studied using the far-ultraviolet (UV) circular dichroism (CD) spectra.The results showed that lower concentrations of dextran (less than 60 g/L) induced formation of the secondary CK structures.However,the secondary structure content of CK decreased when the dextran concentrations exceeded 60 g/L.Thermally induced transition curves were measured for CK in the presence of different concentrations of dextran by far-UV CD.The thermal transition curves were fitted to a two-state model by a nonlinear,least-squares method to obtain the transition temperature of the unfolding transition.An increase in the tran- sition temperature was observed with the increase of the dextran concentration.These observations qualita-tively accord with predictions of a previously proposed model for the effect of intermolecular excluded volume (macromolecular crowding) on protein stability and conformation.These findings imply that the effects of macromolecular crowding can have an important influence on our understanding of how protein folding oc-curs in vivo.

  5. Enhanced Thermal Stability of Polylactide by Terminal Conjugation Groups

    Science.gov (United States)

    Tran, Hang Thi; Matsusaki, Michiya; Akashi, Mitsuru; Vu, Ngo Dinh

    2016-05-01

    Various acids such as aliphatic or carbocyclic fatty or aromatic acids were successfully conjugated into the ending hydroxyl group of poly( l-lactide) (PLLA). The chemical structures of various acid-PLLAs were confirmed by Fourier transform infrared and proton nuclear magnetic resonance analysis. The crystallinity and solubility of the original PLLA were maintained after the terminal conjugation of various acids. The thermal properties were significantly improved, especially the 10% weight-loss temperature that showed an increase of over 80°C for conjugation of aliphatic or aromatic acids as compared to that of the corresponding original PLLA. In addition, more than 60 wt.% of the aliphatic acid-PLLAs was pyrolyzed, and aromatic acid-PLLAs degraded only about 10 wt.% for 150 min, although the original PLLA was pyrolyzed completely at 250°C for 7 min. The thermal stability of PLLA was controlled by the conjugation of aliphatic or aromatic acids into a chain end. These acid-PLLAs may be useful as materials with high thermal stability for various application fields.

  6. Plasma stability theory including the resistive wall effects

    Science.gov (United States)

    Pustovitov, V. D.

    2015-12-01

    > Plasma stabilization due to a nearby conducting wall can provide access to better performance in some scenarios in tokamaks. This was proved by experiments with an essential gain in and demonstrated as a long-lasting effect at sufficiently fast plasma rotation in the DIII-D tokamak (see, for example, Strait et al., Nucl. Fusion, vol. 43, 2003, pp. 430-440). The rotational stabilization is the central topic of this review, though eventually the mode rotation gains significance. The analysis is based on the first-principle equations describing the energy balance with dissipation in the resistive wall. The method emphasizes derivation of the dispersion relations for the modes which are faster than the conventional resistive wall modes, but slower than the ideal magnetohydrodynamics modes. Both the standard thin wall and ideal-wall approximations are not valid in this range. Here, these are replaced by an approach incorporating the skin effect in the wall. This new element in the stability theory makes the energy sink a nonlinear function of the complex growth rate. An important consequence is that a mode rotating above a critical level can provide a damping effect sufficient for instability suppression. Estimates are given and applications are discussed.

  7. Thermal conduction in a mirror-unstable plasma

    Science.gov (United States)

    Komarov, S. V.; Churazov, E. M.; Kunz, M. W.; Schekochihin, A. A.

    2016-07-01

    The plasma of galaxy clusters is subject to firehose and mirror instabilities at scales of order the ion Larmor radius. The mirror instability generates fluctuations of magnetic-field strength δB/B ˜ 1. These fluctuations act as magnetic traps for the heat-conducting electrons, suppressing their transport. We calculate the effective parallel thermal conductivity in the ICM in the presence of the mirror fluctuations for different stages of the evolution of the instability. The mirror fluctuations are limited in amplitude by the maximum and minimum values of the field strength, with no large deviations from the mean value. This key property leads to a finite suppression of thermal conduction at large scales. We find suppression down to ≈0.2 of the Spitzer value for the secular phase of the perturbations' growth, and ≈0.3 for their saturated phase. The effect operates in addition to other suppression mechanisms and independently of them. Globally, fluctuations δB/B ˜ 1 can be present on much larger scales, of the order of the scale of turbulent motions. However, we do not expect large suppression of thermal conduction by these, because their scale is considerably larger than the collisional mean free path of the ICM electrons. The obtained suppression of thermal conduction by a factor of ˜5 appears to be characteristic and potentially universal for a weakly collisional mirror-unstable plasma.

  8. Porous materials produced from incineration ash using thermal plasma technology.

    Science.gov (United States)

    Yang, Sheng-Fu; Chiu, Wen-Tung; Wang, To-Mai; Chen, Ching-Ting; Tzeng, Chin-Ching

    2014-06-01

    This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9-1.2 g cm(-3) and 50-60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946 W m(-1) K(-1). Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Isothermal Oxidation Behavior of Supersonic Atmospheric Plasma-Sprayed Thermal Barrier Coating System

    Science.gov (United States)

    Bai, Yu; Ding, Chunhua; Li, Hongqiang; Han, Zhihai; Ding, Bingjun; Wang, Tiejun; Yu, Lie

    2013-10-01

    In this work, Y2O3 stabilized zirconia-based thermal barrier coatings (TBCs) were deposited by conventional atmospheric plasma spraying (APS) and high efficiency supersonic atmospheric plasma spraying (SAPS), respectively. The effect of Al2O3 layer stability on the isothermal growth behavior of thermally grown oxides (TGOs) was studied. The results revealed that the Al2O3 layer experienced a three-stage change process, i.e., (1) instantaneous growth stage, (2) steady-state growth stage, and (3) depletion stage. The thickness of Al2O3 scale was proved to be an important factor for the growth rate of TGOs. The SAPS-TBCs exhibited a higher Al2O3 stability and better oxidation resistance as compared with the APS-TBCs. Additionally, it was found that inner oxides, especially nucleated on the top of the crest, continually grew and swallowed the previously formed Al2O3 layer, leading to the granulation and disappearance of continuous Al2O3 scale, which was finally replaced by the mixed oxides and spinel.

  10. Analysis of the step responses of laminar premixed flames to forcing by non-thermal plasma

    KAUST Repository

    Lacoste, Deanna A.

    2016-07-16

    The step responses of lean methane-air flames to non-thermal plasma forcing is reported. The experimental setup consists of an axisymmetric burner, with a nozzle made of a quartz tube. The equivalence ratio is 0.95, allowing stabilization of the flame in a V-shape or an M-shape geometry, over a central stainless steel rod. The plasma is produced by short pulses of 10-ns duration, 8-kV maximum voltage amplitude, applied at 10 kHz. The central rod is used as a cathode, while the anode is a stainless steel ring, fixed on the outer surface of the quartz tube. Plasma forcing is produced by positive or negative steps of plasma. The step response of the flame is investigated through heat release rate (HRR) fluctuations, to facilitate comparisons with flame response to acoustic perturbations. The chemiluminescence of CH* between two consecutive pulses was recorded using an intensified camera equipped with an optical filter to estimate the HRR fluctuations. First, the results show that the flame does not respond to each single plasma pulse, but is affected only by the average plasma power, confirming the step nature of the forcing. The temporal evolutions of HRR are analyzed and the flame transfer functions are determined. A forcing mechanism, as a local increase in the reactivity of the fluid close to the rod, is proposed and compared with numerical simulations. Experiments and numerical simulations are in good qualitative agreement. © 2016.

  11. High-temperature stability of yttria-stabilized zirconia thermal barrier coating on niobium alloy—C-103

    Indian Academy of Sciences (India)

    S S Panwar; T Umasankar Patro; K Balasubramanian; B Venkataraman

    2016-02-01

    Thermal barrier coatings (TBCs) of yttria-stabilized zirconia (YSZ) of different thicknesses with an intermediate bond coat were deposited on C-103 Nb alloy using the air plasma spraying technique. The coatings were subjected to rapid infra-red (IR) heating ($\\sim$25°C s$^{−1}$) up to $\\sim$1250°C and exposed up to 100 s at this temperature with heat flux varying from 55 to 61 Wcm$^{−2}$. The TBCs were found to be stable and intact after the heat treatment. In contrast, at the same conditions, the uncoated C-103 alloy specimen showed extensive oxidation followed by weight loss due to spallation. A maximum temperature drop of $\\sim$200°C was observed on the opposite side of the coated alloy with 600 $\\mu$m YSZ coat; as against negligible temperature drop in case of bare alloy specimen. The temperature drop was found to increase with the coating thickness of YSZ. The coatings before and after IR heating were investigated by scanning electron microscopy, X-ray diffraction, electron probe microanalysis, microhardness and residual stress measurements in order to understand the effect of thermal shock on the properties of the TBC. On account of these high-temperature properties, YSZ coating along with the bond coat is expected to find potential thermal barrier coating system on niobium alloys for supersonic vehicles.

  12. Nanostructured yttria stabilized zirconia coatings deposited by air plasma spraying

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hong; LI Fei; HE Bo; WANG Jun; SUN Bao-de

    2007-01-01

    Nanostructured yttria partially stabilized zirconia coatings were deposited by air plasma spraying with reconstituted nanosized powder. The microstructures and phase compositions of the powder and the as-sprayed nanostructured coatings were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results demonstrate that the microstructure of as-sprayed nanostructured zirconia coating exhibits a unique tri-modal distribution including the initial nanostructure of the powder, equiaxed grains and columnar grains. Air plasma sprayed nanostructured zirconia coatings consist of only the nontransformable tetragonal phase, though the reconstituted nanostructured powder shows the presence of the monoclinic, the tetragonal and the cubic phases. The mean grain size of the coating is about 42 nm.

  13. Thermal stability and nova cycles in permanent superhump systems

    CERN Document Server

    Retter, A

    2000-01-01

    Archival data on permanent superhump systems are compiled to test the thermal stability of their accretion discs. We find that their discs are almost certainly thermally stable as expected. This result confirms Osaki's suggestion (1996) that permanent superhump systems form a new subclass of cataclysmic variables (CVs), with relatively short orbital periods and high mass transfer rates. We note that if the high accretion rates estimated in permanent superhump systems represent their mean secular values, then their mass transfer rates cannot be explained by gravitational radiation, therefore, either magnetic braking should be extrapolated to systems below the period gap or they must have mass transfer cycles. Alternatively, a new mechanism that removes angular momentum from CVs below the gap should be invoked. We suggest applying the nova cycle scenarios offered for systems above the period gap to the short orbital period CVs. Permanent superhumps have been observed in the two non-magnetic ex-novae with binary...

  14. Molecular dynamics simulation of thermal stability of nanocrystalline vanadium

    Institute of Scientific and Technical Information of China (English)

    WEI; Mingzhi; XIAO; Shifang; YUAN; Xiaojian; HU; Wangyu

    2006-01-01

    The microstructure and thermal stability of nanocrystalline vanadium with an average grain size ranging from 2.86 to 7.50 nm are calculated by means of the analytic embedded-atom method and molecular dynamics. The grain boundary and nanocrystalline grain atoms are differentiated by the common neighbor analysis method. The results indicate that the fraction of grain boundary increases with the grain size decreasing, and the mean energy of atoms is higher than that of coarse crystals. The thermal-stable temperatures of nanocrystalline vanadium are determined from the evolution of atomic energy, fraction of grain boundary and radial distribution function. It is shown that the stable temperature decreases obviously with the grain size decreasing. In addition the reasons which cause the grain growth of nanocrystalline vanadium are discussed.

  15. Thermal stability of marks gold nanoparticles: A molecular dynamics simulation

    Science.gov (United States)

    Jia, Yanlin; Li, Siqi; Qi, Weihong; Wang, Mingpu; Li, Zhou; Wang, Zhixing

    2017-03-01

    Molecular dynamics (MDs) simulations were used to explore the thermal stability of Au nanoparticles (NPs) with decahedral, cuboctahedral, icosahedral and Marks NPs. According to the calculated cohesive energy and melting temperature, the Marks NPs have a higher cohesive energy and melting temperature compared to these other shapes. The Lindemann index, radial distribution function, deformation parameters, mean square displacement and self-diffusivity have been used to characterize the structure variation during heating. This work may inspire researchers to prepare Marks NPs and apply them in different fields.

  16. Synthesis, Thermal Stability and Sensitivity of 2, 4-Dinitroimidazole

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; DONG Hai-shan; ZHANG Xiao-yu; ZHOU Jian-hua; ZHANG Xiu-li; LI Jin-shan

    2010-01-01

    Pursuing new insensitive high explosive (IHE) is the main research hot-point in explosive field. Nitroimidazole compounds were mainly studied in the medicine chemistry in the past[1-2], seldom seen as the components of explosives and propellants. But now, several nitroimidazole compounds, such as 2, 4-dinitroimidazole (2, 4-DNI), 2, 4, 5-trinitroimidazole (2, 4, 5-TNI) and 1-methyl-2, 4, 5-trinitroimidazole (MTNI) etc are found to be the important intermediates of synthesizing new high explosives or itself possessing excellent explosive performances[3-5]. This paper introduces the synthesis, especially the experimental thermal stability, sensitivity and security of 2, 4-dinitroimidazole (2, 4-DNI).

  17. Thermal stability of atomically flat metal nanofilms on metallic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Calleja, F.; Hinarejos, J.J. [Departamento de Fisica de la Materia Condensada e Instituto de Ciencia de Materiales N. Cabrera, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Passeggi, M.C.G. [Laboratorio de Superficies e Interfases, INTEC (CONICET and UNL), S3000GLN Santa Fe (Argentina); Vazquez de Parga, A.L. [Departamento de Fisica de la Materia Condensada e Instituto de Ciencia de Materiales N. Cabrera, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Miranda, R. [Departamento de Fisica de la Materia Condensada e Instituto de Ciencia de Materiales N. Cabrera, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)], E-mail: rodolfo.miranda@uam.es

    2007-10-31

    By means of variable temperature scanning tunneling microscope we studied the morphology and electronic structure of Pb films grown on Cu(1 1 1). Due to the spatial confinement of electrons, the islands display quantized energy levels. At 300 K, Pb forms 3D nanostructures with magic heights, that correspond to islands having a quantum well state (QWS) far from the Fermi energy. Below 100 K Pb grows in a quasi-layer-by-layer fashion. The QWS that develop in the films determine their total energy and, accordingly, their thermal stability. Films of particularly magic thickness are stable upon heating to 300 K.

  18. Stability study for matching in laser driven plasma acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, A.R., E-mail: andrea.rossi@mi.infn.it [INFN - MI, via Celoria 16, 20133 Milan (Italy); Anania, M.P. [INFN - LNF, v.le E. Fermi, 00044 Frascati (Italy); Bacci, A. [INFN - MI, via Celoria 16, 20133 Milan (Italy); Belleveglia, M.; Bisesto, F.G.; Chiadroni, E. [INFN - LNF, v.le E. Fermi, 00044 Frascati (Italy); Cianchi, A. [Tor Vergata University, Physics Department, via della Ricerca Scientifica 1, 00133 Rome (Italy); INFN - LNF, v.le E. Fermi, 00044 Frascati (Italy); Curcio, A.; Gallo, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M. [INFN - LNF, v.le E. Fermi, 00044 Frascati (Italy); Marocchino, A.; Massimo, F. [La Sapienza University, SBAI Department, via A. Scarpa 14, 00161 Rome (Italy); Mostacci, A. [La Sapienza University, SBAI Department, via A. Scarpa 14, 00161 Rome (Italy); INFN - LNF, v.le E. Fermi, 00044 Frascati (Italy); Petrarca, M. [La Sapienza University, SBAI Department, via A. Scarpa 14, 00161 Rome (Italy); Pompili, R. [INFN - LNF, v.le E. Fermi, 00044 Frascati (Italy); Serafini, L. [INFN - MI, via Celoria 16, 20133 Milan (Italy); Tomassini, P. [University of Milan, Physics Department, via Celoria 16, 20133 Milan (Italy); Vaccarezza, C. [INFN - LNF, v.le E. Fermi, 00044 Frascati (Italy); and others

    2016-09-01

    In a recent paper [14], a scheme for inserting and extracting high brightness electron beams to/from a plasma based acceleration stage was presented and proved to be effective with an ideal bi-Gaussian beam, as could be delivered by a conventional photo-injector. In this paper, we extend that study, assessing the method stability against some jitters in the properties of the injected beam. We find that the effects of jitters in Twiss parameters are not symmetric in results; we find a promising configuration that yields better performances than the setting proposed in [14]. Moreover we show and interpret what happens when the beam charge profiles are modified.

  19. Microseconds-scale magnetic actuators system for plasma feedback stabilization

    Science.gov (United States)

    Kogan, K.; Be'ery, I.; Seemann, O.

    2016-10-01

    Many magnetic confinement machines use active feedback stabilization with magnetic actuators. We present a novel magnetic actuators system with a response time much faster than previous ones, making it capable of coping with the fast plasma instabilities. The system achieved a response time of 3 μs with maximal current of 500 A in a coil with inductance of 5.2 μH. The system is based on commercial solid-state switches and FPGA state machine, making it easily scalable to higher currents or higher inductivity.

  20. Stability of plasma metabolites and hormones in lactating dairy cows.

    Science.gov (United States)

    Phillips, R W; Athanasiou, V N

    1978-06-01

    Plasma concentration stability of glucose, free fatty acids, ketone bodies, growth hormone, insulin were determined in lactating dairy cows. Concentrations of these metabolites and hormones were measured during a 36- to 48-hour period in 3 normal, mature dairy cows in the 2nd month of lactation. Samples were taken at 30-minute intervals; also, intensive sampling (every 10 minutes) was done at varying times in relation to feeding and milking. Of the 5 components measured, glucose concentration was the most stable, easiest to assay, and most reliable for use as a diagnostic aid in assessing metabolic carbohydrate disturbances in dairy cattle.

  1. Plasma etching to enhance the surface insulating stability of alumina for fusion applications

    Directory of Open Access Journals (Sweden)

    M. Malo

    2016-12-01

    Full Text Available A significant increase in the surface electrical conductivity of alumina, considered one of the most promising insulating materials for numerous applications in fusion devices, has been observed during ion bombardment in vacuum due to oxygen loss by preferential sputtering. Although this is expected to cause serious limitations to insulating components functionality, recent studies showed it is possible to restore the damaged lattice by oxygen reincorporation during thermal treatments in air. These studies also revealed a correlation between conductivity and ion beam induced luminescence, which is being used to monitor surface electrical conductivity degradation and help qualify the post irradiation recovery. Work now carried out for Wesgo alumina considers oxygen implantation and plasma etching as additional methods to improve recovered layer depth and quality. Both conductivity and luminescence results indicate the potential use of plasma etching not only for damage recovery, but also as a pre-treatment to enhance material stability during irradiation.

  2. Optmized stability of a modulated driver in a plasma wakefield

    CERN Document Server

    Martorelli, Roberto

    2016-01-01

    We analyze the transverse stability for a configuration of multiple gaussian bunches subject to the self-generated plasma wakefield. Through a semi-analytical approach we first study the equilibrium configuration for the modulated beam and then we investigate the evolution of the equilibrium configuration due to the emittance-driven expansion of the beam front that results in a rigid backward shift. The rear-directed shift brings the modulated beam out of the equilibrium, with the possibility for some of the bunch particles to be lost with a consequent deterioration of the driver. We look therefore for the proper position of the single bunches that maximize the stability without severely affecting the accelerating field behind the driver. We then compare the results with 3D PIC simulations.

  3. Ionoluminscence of partially-stabilized zirconia for thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rebollo, N.R. [Departamento de Fisica Experimental, Instituto de Fisica, Universidad Nacional Autonoma de Mexico (UNAM), Circuito de la Investigacion Cientifica S/N, Ciudad Universitaria, Mexico D.F., C.P. 04510 (Mexico)]. E-mail: nrebollof@yahoo.com; Ruvalcaba-Sil, J.L. [Departamento de Fisica Experimental, Instituto de Fisica, Universidad Nacional Autonoma de Mexico (UNAM), Circuito de la Investigacion Cientifica S/N, Ciudad Universitaria, Mexico D.F., C.P. 04510 (Mexico); Miranda, J. [Departamento de Fisica Experimental, Instituto de Fisica, Universidad Nacional Autonoma de Mexico (UNAM), Circuito de la Investigacion Cientifica S/N, Ciudad Universitaria, Mexico D.F., C.P. 04510 (Mexico)

    2007-08-15

    Ionoluminescence is explored as an alternative technique to study the high temperature phase stability of zirconia-based oxides. The evolution of an initially metastable single tetragonal phase towards de-stabilization is investigated for three single-doped zirconia compositions with Y, Yb and Gd. The differences in de-stabilization paths are identified using X-ray diffraction and ionoluminescence; elemental analysis is also performed using particle-induced X-ray emission. X-ray diffraction studies reveal a different scenario for each of the compositions selected; the differences are strongly influenced by the thermodynamic driving forces associated to the fluorite-to-tetragonal displacive transformation. Ionoluminescence studies indicate a significant increment on the signal intensity for de-stabilized samples, relative to previous annealing stages. There are also more subtle differences in the luminescent response from the samples at intermediate annealing stages also related to phase changes. This study provides a basis to characterize phase evolution in single-doped zirconia compositions for thermal insulation applications using luminescence.

  4. Properties of stable nonstoichiometric nanoceria produced by thermal plasma

    Science.gov (United States)

    Lan, Yuan-Pei; Sohn, Hong Yong; Mohassab, Yousef; Liu, Qingcai; Xu, Baoqiang

    2017-08-01

    Thermally stable blue nonstoichiometric nanoceria was produced by feeding nanoceria with an average size of 50 nm into a DC thermal plasma reactor. The effects of different plasma power levels and atmospheres were investigated. XRD results showed the ceria lattice parameter increased with plasma power. SEM and TEM results showed that the shape of nanoparticles changed after plasma treatment; the blue nonstoichiometric nanoceria had highly regular shapes such as triangular pyramids and polyhedral in contrast to the irregular shape of the raw nanoceria. Significant downshift was found in the Raman spectra of the plasma products, with a 7.9-cm-1 shift compared with raw nanoceria, which was explained by the reduction of Ce4+. X-ray photoelectron spectroscopy results showed that the Ce3+ fraction increased from 14% in the raw nanoceria to 38-39% for the product CeO2- x , indicating the high reduction state on the ceria surface. It was determined that this blue nonstoichiometric nanoceria was stable up to 400 °C in air, but the color changed to pale yellow after 4 h at 500 °C in air indicating oxidation to CeO2. Additionally, this novel stable nano-CeO2- x caused a red shift in the UV-visible absorption results; a 48-nm red shift occurred for the nonstoichiometric nanoceria produced at 15 kW compared with the raw nanoceria. The band gap was calculated to be 2.5 eV while it was 3.2 eV for the raw nanoceria, indicating that this novel stable blue nonstoichiometric nanoceria should be a promising material for optical application.

  5. Stress Analysis and Failure Mechanisms of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Yang, Jiasheng; Wang, Liang; Li, Dachuan; Zhong, Xinghua; Zhao, Huayu; Tao, Shunyan

    2017-06-01

    Yttria-stabilized zirconia coatings were deposited by plasma spraying and heat-treated at 1100 °C for 50, 100, 150, and 200 h in air, respectively. Mechanical properties including microhardness and Young's modulus were evaluated using the nanoindentation test. Residual stresses in the ceramic topcoat and the thermally grown oxide (TGO) layer were measured using Raman spectroscopy and photoluminescence piezo-spectroscopy (PLPS) techniques, respectively. The results showed that both the modulus and hardness increased with the thermal exposure time up to 100 h and then gradually decreased. The accumulated tensile stress in the as-sprayed topcoat changed to compressive stress after thermal exposure, and the compressive stress in the topcoat increased with an increase of thermal exposure time up to 150 h. The average compressive stresses in the TGO layer were higher than that of the cross-sectional topcoat, and the measured in-plane compressive stress increased firstly and then gradually decreased with increasing exposure time. The local interface geometry strongly affect the nature and evolution of hydrostatic stresses in the TGO. Finally, the crack initiation and propagation at the topcoat/TGO/bondcoat interface has been discussed with respect to the residual stresses in the plasma-sprayed TBC system.

  6. Temperature measurements in thermal plasmas; Mesures de temperatures dans les plasmas thermiques

    Energy Technology Data Exchange (ETDEWEB)

    Fauchais, P.; Coudert, J.F. [Limoges Univ., 87 (France)

    1996-05-01

    Thermal plasmas are characterized by a high pressure (10{sup 4} to 10{sup 6} Pa) and a high density of particles. Plasmas considered in this paper are produced by electric discharges, arcs, injection torches with cold or hot cathodes, water vortex torches, RF devices and are characterized by temperatures ranging from 6000 to 40000 K and ionization energies ranging from 13.5 and 16 eV (in argon, argon-hydrogen, nitrogen, nitrogen-hydrogen, argon-helium, air, oxygen, CO{sub 2} or water). Temperature measurements in thermal plasmas are difficult due to their extreme luminosity, flow rate and thermal flux, and to their temperature and flow rate gradients. The most common measurement methods are the emission spectroscopy, the laser scattering (Rayleigh, Thomson and coherent anti-Stokes Raman scattering) and the enthalpy probes. The first two methods are non-intrusive, while the last method is intrusive. This paper gives first some general remarks about the principles of each technique and focusses on the problem of fluctuations due to the plasma jet instabilities. Then, it describes briefly each technique and gives some examples of results. Finally, it compares the spectroscopic measurements with other measurements. (J.S.) 80 refs.

  7. MERCURY OXIDIZATION IN NON-THERMAL PLASMA BARRIER DISCHARGE SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    V.K. Mathur

    2003-02-01

    In the past decade, the emission of toxic elements from human activities has become a matter of great public concern. Hg, As, Se and Cd typically volatilize during a combustion process and are not easily caught with conventional air pollution control techniques. In addition, there is no pollution prevention technique available now or likely be available in the foreseeable future that can prevent the emission of these trace elements. These trace elements pose additional scientific challenge as they are present at only ppb levels in large gas streams. Mercury, in particular, has attracted significant attention due to its high volatility, toxicity and potential threat to human health. In the present research work, a non-thermal plasma dielectric barrier discharge technique has been used to oxidize Hg{sup 0}(g) to HgO. The basic premise of this approach is that Hg{sup 0} in vapor form cannot be easily removed in an absorption tower whereas HgO as a particulate is amiable to water scrubbing. The work presented in this report consists of three steps: (1) setting-up of an experimental apparatus to generate mercury vapors at a constant rate and modifying the existing non-thermal plasma reactor system, (2) solving the analytical challenge for measuring mercury vapor concentration at ppb level, and (3) conducting experiments on mercury oxidation under plasma conditions to establish proof of concept.

  8. Nitrogen oxides and methane treatment by non-thermal plasma

    Science.gov (United States)

    Alva, E.; Pacheco, M.; Colín, A.; Sánchez, V.; Pacheco, J.; Valdivia, R.; Soria, G.

    2015-03-01

    Non thermal plasma was used to treat nitrogen oxides (NOx) and methane (CH4), since they are important constituents of hydrocarbon combustion emissions processes and, both gases, play a key role in the formation of tropospheric ozone. These gases are involved in environmental problems like acid rain and some diseases such as bronchitis and pneumonia. In the case of methane is widely known its importance in the global climate change, and currently accounts for 30% of global warming. There is a growing concern for methane leaks, associated with a rapid expansion of unconventional oil and gas extraction techniques as well as a large-scale methane release from Arctic because of ice melting and the subsequent methane production of decaying organic matter. Therefore, methane mitigation is a key to avoid dangerous levels of global warming. The research, here reported, deals about the generation of non-thermal plasma with a double dielectric barrier (2DBD) at atmospheric pressure with alternating current (AC) for NOx and CH4 treatment. The degradation efficiencies and their respective power consumption for different reactor configurations (cylindrical and planar) are also reported. Qualitative and quantitative analysis of gases degradation are reported before and after treatment with cold plasma. Experimental and theoretical results are compared obtaining good removal efficiencies, superior to 90% and to 20% respectively for NOx and CH4.

  9. Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

    Directory of Open Access Journals (Sweden)

    Ungyu Paik

    2013-08-01

    Full Text Available The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF and low-pressure plasma spray (LPPS methods showed a partial cracking (and/or delamination and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50% after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF.

  10. Thermodynamic analysis of alcohol effect on thermal stability of proteins.

    Science.gov (United States)

    Miyawaki, Osato; Tatsuno, Michiko

    2011-02-01

    Thermal unfolding of ribonuclease A and α-chymotrypsinogen A was analyzed in various alcohol solutions of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, trifluoroethanol, and glycerol. The change in thermal unfolding ratio with temperature was described well by the van't Hoff equation and the melting temperature and the enthalpy of protein unfolding were obtained. The reciprocal form of the Wyman-Tanford equation, which describes the unfolded-to-folded protein ratio as a function of water activity, was applied to obtain a linear plot. From the slope of this plot and water activity, the stabilization free energy (ΔΔG) in a solution was calculated. This shows an important role of water activity in protein stability. ΔΔG was linearly dependent on alcohol concentration and m-values of alcohols for protein unfolding were obtained. This provides a theoretical basis for the linear extrapolation model (LEM). The m-values for alcohols were negative except for glycerol. The negative higher m-value for longer and linear chain alcohols suggested the important role of the disturbance of hydrophobic interactions as well as the hydrogen-bonding in the mechanism of protein destabilization by alcohols. The number of change in bound-alcohol molecules upon protein unfolding was also obtained. Copyright © 2010 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  11. Preliminary hazards analysis of thermal scrap stabilization system. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, W.S.

    1994-08-23

    This preliminary analysis examined the HA-21I glovebox and its supporting systems for potential process hazards. Upon further analysis, the thermal stabilization system has been installed in gloveboxes HC-21A and HC-21C. The use of HC-21C and HC-21A simplified the initial safety analysis. In addition, these gloveboxes were cleaner and required less modification for operation than glovebox HA-21I. While this document refers to glovebox HA-21I for the hazards analysis performed, glovebox HC-21C is sufficiently similar that the following analysis is also valid for HC-21C. This hazards analysis document is being re-released as revision 1 to include the updated flowsheet document (Appendix C) and the updated design basis (Appendix D). The revised Process Flow Schematic has also been included (Appendix E). This Current revision incorporates the recommendations provided from the original hazards analysis as well. The System Design Description (SDD) has also been appended (Appendix H) to document the bases for Safety Classification of thermal stabilization equipment.

  12. Thermal Stabilization study of polyacrylonitrile fiber obtained by extrusion

    Directory of Open Access Journals (Sweden)

    Robson Fleming Ribeiro

    2015-12-01

    Full Text Available A low cost and environmental friendly extrusion process of the Polyacrylonitrile (PAN polymer was viabilized by using the 1,2,3-propanetriol (glycerol as a plasticizer. The characterization of the fibers obtained by this process was the object of study in the present work. The PAN fibers were heat treated in the range of 200 °C to 300 °C, which is the temperature range related to the stabilization/oxidation step. This is a limiting phase during the carbon fiber processing. The characterization of the fibers was made using infrared spectroscopy, thermal analysis and microscopy. TGA revealed that the degradation of the extruded PAN co-VA fibers between 250 °C and 350 °C, corresponded to a 9% weight loss to samples analyzed under oxidizing atmosphere and 18% when the samples were analyzed under inert atmosphere. DSC showed that the exothermic reactions on the extruded PAN co-VA fibers under oxidizing synthetic air was broader and the cyclization started at a lower temperature compared under inert atmosphere. Furthermore, FT-IR analysis correlated with thermal anlysis showed that the stabilization/oxidation process of the extruded PAN fiber were coherent with other works that used PAN fibers obtained by other spinning processes.

  13. Performance of water and hybrid stabilized electric arcs: the impact of dependence of radiation losses and plasma density on pressure

    Science.gov (United States)

    Jeništa, J.; Bartlová, M.; Aubrecht, V.

    2006-10-01

    Processes in the worldwide unique type of thermal plasma generator with water vortex stabilization and combined stabilization of arc by argon flow and water vortex have been numerically studied. Two-dimensional axisymmetric numerical model assumes laminar and compressible plasma flow in the state of local thermodynamic equilibrium. The calculation domain includes the arc discharge area between the near-cathode region and the outlet nozzle of the plasma torch. Radiation losses from the arc are calculated by the partial characteristics method for atmospheric pressure water and argon-water discharges. Thermal, electrical and fluid-dynamic characteristics of such arcs have been studied for the range of currents 150÷600 A under the assumption that radiation losses and plasma density depend linearly on pressure. It was proved that, taking this dependence into account, plasma velocity decrease while power losses from the arc by radiation and radial conduction increase with current. Outlet plasma temperature as well as electric potential drop remain practically unchanged.

  14. Molecular cloud formation via thermal instability of finite resistive viscous radiating plasma with finite Larmor radius corrections

    Science.gov (United States)

    Kaothekar, Sachin

    2017-06-01

    The effect of radiative heat-loss function and finite ion Larmor radius (FLR) corrections on the thermal instability of infinite homogeneous viscous plasma has been investigated incorporating the effects of thermal conductivity and finite electrical resistivity for the formation of a molecular cloud. The general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. Furthermore the wave propagation along and perpendicular to the direction of external magnetic field has been discussed. Stability of the medium is discussed by applying Routh Hurwitz's criterion and it is found that thermal instability criterion determines the stability of the medium. We find that the presence of radiative heat-loss function and thermal conductivity modify the fundamental criterion of thermal instability into radiatively driven thermal instability criterion. In longitudinal direction FLR corrections, viscosity, magnetic field and finite resistivity have no effect on thermal instability criterion. The presence of radiative heat-loss function and thermal conductivity modify the fundamental thermal instability criterion into radiatively driven thermal instability criterion. Also the FLR corrections modify the growth rate of the Alfven mode. For transverse wave propagation FLR corrections, radiative heat-loss function, magnetic field and thermal conductivity modify the thermal instability criterion. From the curves it is clear that heat-loss function, FLR corrections and viscosity have stabilizing effect, while finite resistivity has destabilizing effect on the thermal modes. Our results show that the FLR corrections and radiative heat-loss functions affect the evolution of interstellar molecular clouds and star formation.

  15. Thermal stability and modeling of lithium ion batteries

    Science.gov (United States)

    Botte, Gerardine Gabriela

    2000-10-01

    First-principles mathematical models were developed to examine the effect of the lithium-lithium ion interactions inside the anode particles on the performance of a lithium foil cell. Two different models were developed: the chemical potential model (CPM) that includes the lithium-lithium ion interactions inside the anode particles and the diffusion model (DIM) that does not include the interactions. Significant differences in the thermal and electrochemical performance of the cell were observed between the two approaches. The temperature of the cell predicted by the DFM is higher than the one predicted by the CPM at a given capacity. The discharge time of the cell predicted by the DFM is shorter than the one predicted by the CPM. The results indicate that the cell needs to be modeled using the CPM approach especially at high discharge rates. An evaluation of the numerical techniques, control volume formulation (CVF) and finite difference method (FDM), used for the models was performed. It is shown that the truncation error is the same for both methods when the boundary conditions are of the Dirichlet type, the system of equations are linear and represented in Cartesian coordinates. A new technique to analyze the accuracy of the methods is presented. The only disadvantage of the FDM is that it failed to conserve mass for a small number of nodes when both boundary conditions include a derivative term whereas the CVF did conserve mass for these cases. However, for a large number of nodes the FDM provides mass conservation. It is important to note that the CVF has only (DeltaX) order of accuracy for a Neumann type boundary condition whereas the FDM has (DeltaX) 2 order. The second topic of this dissertation presents a study of the thermal stability of LiPF6 EC:EMC electrolyte for lithium ion batteries. A differential scanning calorimeter (DSC) was used to perform the study of the electrolyte. For first time, the effect of different variables on its thermal stability

  16. Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2014-08-01

    Full Text Available Suspension plasma spraying (SPS has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air plasma spraying (APS or electron beam physical vapor deposition (EB-PVD coatings. Additionally, SPS coatings can have lower thermal conductivity than EB-PVD coatings, while also being easier to produce. The combination of similar or improved properties with a potential for lower production costs makes SPS of great interest to the gas turbine industry. This study compares a number of SPS thermal barrier coatings (TBCs with vertical cracks or column-like structures with the reference of segmented APS coatings. The primary focus has been on lifetime testing of these new coating systems. Samples were tested in thermo-cyclic fatigue at temperatures of 1100 °C for 1 h cycles. Additional testing was performed to assess thermal shock performance and erosion resistance. Thermal conductivity was also assessed for samples in their as-sprayed state, and the microstructures were investigated using SEM.

  17. Thermal stabilization of static single-mirror Fourier transform spectrometers

    Science.gov (United States)

    Schardt, Michael; Schwaller, Christian; Tremmel, Anton J.; Koch, Alexander W.

    2017-05-01

    Fourier transform spectroscopy has become a standard method for spectral analysis of infrared light. With this method, an interferogram is created by two beam interference which is subsequently Fourier-transformed. Most Fourier transform spectrometers used today provide the interferogram in the temporal domain. In contrast, static Fourier transform spectrometers generate interferograms in the spatial domain. One example of this type of spectrometer is the static single-mirror Fourier transform spectrometer which offers a high etendue in combination with a simple, miniaturized optics design. As no moving parts are required, it also features a high vibration resistance and high measurement rates. However, it is susceptible to temperature variations. In this paper, we therefore discuss the main sources for temperature-induced errors in static single-mirror Fourier transform spectrometers: changes in the refractive index of the optical components used, variations of the detector sensitivity, and thermal expansion of the housing. As these errors manifest themselves in temperature-dependent wavenumber shifts and intensity shifts, they prevent static single-mirror Fourier transform spectrometers from delivering long-term stable spectra. To eliminate these shifts, we additionally present a work concept for the thermal stabilization of the spectrometer. With this stabilization, static single-mirror Fourier transform spectrometers are made suitable for infrared process spectroscopy under harsh thermal environmental conditions. As the static single-mirror Fourier transform spectrometer uses the so-called source-doubling principle, many of the mentioned findings are transferable to other designs of static Fourier transform spectrometers based on the same principle.

  18. Thermal stability in exchange-spring chains of spins

    Science.gov (United States)

    Pellicelli, Raffaele; Solzi, Massimo

    2016-02-01

    Thermal stability and switching behaviour have been compared in pure-hard and soft-hard Heisenberg linear spin chains of the same total length and equal magnetic parameters (except for magnetic anisotropy) with the anisotropy axis and external magnetic field parallel to the chain direction. The zero-temperature energy barriers and finite-temperature transition rates between remanent equilibrium states have been calculated by utilizing the string method and the forward flux sampling (FFS) method, respectively. Depending on the assumed interfaces, the FFS method could in fact fail to correctly sample the characteristic transition paths at interfaces at which these paths have probabilities much lower than those associated with other non-characteristic transition paths. This can especially occur in the case of the asymmetric energy landscapes and multiple asymmetric minimum energy paths (MEPs) of soft-hard systems. Therefore, a proper interface definition is needed in order to deduce the correct transition rates. In particular, we show that the thermal switching of soft-hard chains starting in the soft or in the hard part turns out to occur with an equal rate provided that the interfaces of the FFS method are defined on the basis of the corresponding zero-temperature MEPs. The thermal stability of a soft-hard chain in the remanent equilibrium state could be to some extent lower with respect to that of a pure-hard chain, due to the shorter hard-part length crossed by the domain wall formed in the chain and also to the related slightly smaller energy barrier. However, its switching field at zero temperature is verified to be widely lower than that of the pure-hard chain. Analytical expressions of switching fields and energy barriers have been deduced in various cases.

  19. Treatment of Bone Waste Using Thermal Plasma Technology

    Institute of Scientific and Technical Information of China (English)

    KI Ho Beom; KIM Woo Hyung; KIM Bong Soo; K00 Hyung Joon; LI Mingwei; CHAE Jae Ou

    2007-01-01

    Daily meat consumption produces a lot of bone waste, and dumped bone waste without treatment would result in environmental hazards. Conventional treatment methods of waste bones have some disadvantages. Herein, an investigation of bone waste treated using thermal plasma technology is presented. A high-temperature plasma torch operated at 25.2 kW was used to treat bone waste for seven minutes. The bone waste was finally changed into vitric matter and lost 2/3 of its weight after the treatment. The process was highly efficient, economical, convenient, and fuel-free. This method could be used as an alternative for disposal of bone waste, small infectious animals, hazardous hospital waste, etc.

  20. Modeling ion interpenetration, stagnation, and thermalization in colliding plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jones, M.E.; Winske, D.; Goldman, S.R.; Kopp, R.A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Rogatchev, V.G.; Belkov, S.A.; Gasparyan, P.D.; Dolgoleva, G.V.; Zhidkov, N.V.; Ivanov, N.V.; Kochubej, Y.K.; Nasyrov, G.F.; Pavlovskii, V.A.; Smirnov, V.V.; Romanov, Y.A. [All Russian Scientific Research Institute of Experimental Physics, Sarov (Arzamas 16), Nizhniy Novgorod Region, 607200 (Russia)

    1996-03-01

    Ion interpenetration, stagnation, and energization processes are studied in colliding laser-produced plasma configurations relevant to Trident [R. G. Watt, Rev. Sci. Instrum. {bold 64}, 1770 (1993)] experiments using four different numerical methods: one-dimensional Monte Carlo and Lagrangian multifluid codes, and one- and two-dimensional hybrid (particle ions, fluid electrons) and single-fluid Lagrangian codes. Results from the four methodologies are compared for plasmas generated with gold and deuterated polyethylene (CD{sub 2}) targets. Overall, the various codes give similar results concerning the initial expansion of the plasmas and their collisional interaction, the degree of stagnation, stagnation time, and amount of ion thermalization for gold targets, while multispecies techniques indicate a much softer stagnation for CD{sub 2} plasmas than the single-fluid model. Variations in the results of the calculations due to somewhat different initializations and parameters, as well as to different physics in the codes, are discussed. {copyright} {ital 1996 American Institute of Physics.}

  1. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  2. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Science.gov (United States)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-12-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  3. Elastic behaviour of plasma sprayed thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Steinbrech, R.W.; Frahm, J.; Herzog, R.; Schubert, F. [Inst. for Materials and Processes in Energy Systems, Forschungszentrum Juelich GmbH, Juelich (Germany)

    2002-07-01

    The elastic behaviour of air plasma sprayed (APS) thermal barrier coatings (TBCs) of 8 wt.% yttria stabilised zirconia was studied using various mechanical tests with global and local resolution. Results are presented, which reveal the complex relationship between lamellar APS-microstructure and stiffness and illustrate scaling aspects. Also the influence of residual stresses is addressed. The obtained stiffness values for as-sprayed TBCs show a systematic variation between 10 and 100 GPa. Typically results from bending tests of free-standing TBCs are at the low end, whereas results from depth sensitive indentation tests with TBCs bonded to a substrate are found at the high end. When heat treated above 950 C the TBCs exhibit a rapid increase in stiffness which can be attributed to defect healing within the spraying lamellae. Discussion of the results focuses on the implications of a non-uniform stiffness modulus for the mechanical characterisation of thermal barrier systems. (orig.)

  4. Laser Remelting of Plasma Sprayed Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    Gang ZHANG; Yong LIANG; Yingna WU; Zhongchao FENG; Bingchun ZHANG; Fangjun LIU

    2001-01-01

    A CO2 continuous wave laser with defocused beam was used for remelting the surface of plasma sprayed ZrO2-8 wt pct Y2O3 (8YSZ)/Ni22Cr10AlY thermal barrier coatings (TBCs) on GH536 superalloy substrate. Two main laser processing parameters, power and travel speed, were adopted to produce a completely remelted layer, and their effects on remelted appearance,remelting depth, density and diameter of depression, space of segment crack and remelted microstructure were evaluated. With energy of 4.0 to 8.0 J.mm-2, an appropriate laser processing for applicable remelted layer was suggested.

  5. Thermal Plasma Decomposition Of Nickel And Cobalt Compounds

    Directory of Open Access Journals (Sweden)

    Woch M.

    2015-06-01

    Full Text Available The paper presents the study on manufacturing of nickel and cobalt powders by thermal plasma decomposition of the carbonates of these metals. It was shown the dependence of process parameters and grain size of initial powder on the composition of final product which was ether metal powder, collected in the container as well as the nanopowder with crystallite size of 70 - 90 nm, collected on the inner wall of the reaction chamber. The occurrence of metal oxides in the final products was confirmed and discussed.

  6. Stabilization effect of Weibel modes in relativistic laser fusion plasma

    Science.gov (United States)

    Belghit, Slimen; Sid, Abdelaziz

    2016-06-01

    In this work, the Weibel instability (WI) due to inverse bremsstrahlung (IB) absorption in a laser fusion plasma has been investigated. The stabilization effect due to the coupling of the self-generated magnetic field by WI with the laser wave field is explicitly shown. In this study, the relativistic effects are taken into account. Here, the basic equation is the relativistic Fokker-Planck (F-P) equation. The main obtained result is that the coupling of self-generated magnetic field with the laser wave causes a stabilizing effect of excited Weibel modes. We found a decrease in the spectral range of Weibel unstable modes. This decreasing is accompanied by a reduction of two orders in the growth rate of instable Weibel modes or even stabilization of these modes. It has been shown that the previous analysis of the Weibel instability due to IB has overestimated the values of the generated magnetic fields. Therefore, the generation of magnetic fields by the WI due to IB should not affect the experiences of an inertial confinement fusion.

  7. Thermal Insulation and Thermal Shock Behavior of Conventional and Nanostructured Plasma-Sprayed TBCs

    Science.gov (United States)

    Tamaddon Masoule, S.; Valefi, Z.; Ehsani, N.; Qazi Lavasani, H.

    2016-12-01

    This study investigated the thermal insulation and thermal shock resistance behavior of nanostructured versus conventional yttria-stabilized zirconia (YSZ) thermal barrier coatings. To evaluate their coating performance in service conditions, samples were furnace sintered at 1150 °C for 100 h in ambient atmosphere. The results show that the nanostructured coatings exhibited better heat transfer resistance and thermal shock resistance compared with the conventional coating. In addition, the larger size of the initial agglomerates in the nanostructured coatings increased the percentage area of nanozones and decreased the heat transfer resistance. The thermal insulation behavior of the conventional coating was improved after heat treatment because of horizontal cracking. Disappearance of cracks, bridging between grains, and their growth by connecting with each other were observed in the conventional coating. However, in the nanostructured coatings, the nanoareas and their related properties disappeared. Microstructural and phase investigations were carried out by optical microscopy, field-emission scanning electron microscopy (FE-SEM), and x-ray diffraction (XRD) analysis. The thermal behavior was investigated by thermal insulation capability testing.

  8. Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime: Experiments and Modeling

    Science.gov (United States)

    Gupta, Mohit; Kumara, Chamara; Nylén, Per

    2017-08-01

    Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.

  9. Hall MHD Stability and Turbulence in Magnetically Accelerated Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    H. R. Strauss

    2012-11-27

    The object of the research was to develop theory and carry out simulations of the Z pinch and plasma opening switch (POS), and compare with experimental results. In the case of the Z pinch, there was experimental evidence of ion kinetic energy greatly in excess of the ion thermal energy. It was thought that this was perhaps due to fine scale turbulence. The simulations showed that the ion energy was predominantly laminar, not turbulent. Preliminary studies of a new Z pinch experiment with an axial magnetic field were carried out. The axial magnetic is relevant to magneto - inertial fusion. These studies indicate the axial magnetic field makes the Z pinch more turbulent. Results were also obtained on Hall magnetohydrodynamic instability of the POS.

  10. Increasing Type 1 Poliovirus Capsid Stability by Thermal Selection

    Science.gov (United States)

    Adeyemi, Oluwapelumi O.; Nicol, Clare

    2016-01-01

    ABSTRACT Poliomyelitis is a highly infectious disease caused by poliovirus (PV). It can result in paralysis and may be fatal. Integrated global immunization programs using live-attenuated oral (OPV) and/or inactivated (IPV) PV vaccines have systematically reduced its spread and paved the way for eradication. Immunization will continue posteradication to ensure against reintroduction of the disease, but there are biosafety concerns for both OPV and IPV. They could be addressed by the production and use of virus-free virus-like particle (VLP) vaccines that mimic the “empty” capsids (ECs) normally produced in viral infection. Although ECs are antigenically indistinguishable from mature virus particles, they are less stable and readily convert into an alternative conformation unsuitable for vaccine purposes. Stabilized ECs, expressed recombinantly as VLPs, could be ideal candidate vaccines for a polio-free world. However, although genome-free PV ECs have been expressed as VLPs in a variety of systems, their inherent antigenic instability has proved a barrier to further development. In this study, we selected thermally stable ECs of type 1 PV (PV-1). The ECs are antigenically stable at temperatures above the conversion temperature of wild-type (wt) virions. We have identified mutations on the capsid surface and in internal networks that are responsible for EC stability. With reference to the capsid structure, we speculate on the roles of these residues in capsid stability and postulate that such stabilized VLPs could be used as novel vaccines. IMPORTANCE Poliomyelitis is a highly infectious disease caused by PV and is on the verge of eradication. There are biosafety concerns about reintroduction of the disease from current vaccines that require live virus for production. Recombinantly expressed virus-like particles (VLPs) could address these inherent problems. However, the genome-free capsids (ECs) of wt PV are unstable and readily change antigenicity to a form not

  11. Thermal stability of the krypton Hall effect thruster

    Directory of Open Access Journals (Sweden)

    Szelecka Agnieszka

    2017-03-01

    Full Text Available The Krypton Large IMpulse Thruster (KLIMT ESA/PECS project, which has been implemented in the Institute of Plasma Physics and Laser Microfusion (IPPLM and now is approaching its final phase, was aimed at incremental development of a ~500 W class Hall effect thruster (HET. Xenon, predominantly used as a propellant in the state-of-the-art HETs, is extremely expensive. Krypton has been considered as a cheaper alternative since more than fifteen years; however, to the best knowledge of the authors, there has not been a HET model especially designed for this noble gas. To address this issue, KLIMT has been geared towards operation primarily with krypton. During the project, three subsequent prototype versions of the thruster were designed, manufactured and tested, aimed at gradual improvement of each next exemplar. In the current paper, the heat loads in new engine have been discussed. It has been shown that thermal equilibrium of the thruster is gained within the safety limits of the materials used. Extensive testing with both gases was performed to compare KLIMT’s thermal behaviour when supplied with krypton and xenon propellants.

  12. Comparison of thermal shock behaviors between plasma-sprayed nanostructured and conventional zirconia thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    LIU Chun-bo; ZHANG Zhi-min; JIANG Xian-liang; LIU Min; ZHU Zhao-hui

    2009-01-01

    NiCoCrAlTaY bond coat was deposited on pure nickel substrate by low pressure plasma spraying(LPPS), and ZrO2-8%Y2O3 (mass fraction) nanostructured and ZrO2-7%Y2O3 (mass fraction) conventional thermal barrier coatings(TBCs) were deposited by air plasma spraying(APS). The thermal shock behaviors of the nanostructured and conventional TBCs were investigated by quenching the coating samples in cold water from 1 150, 1 200 and 1 250 ℃, respectively. Scanning electron microscopy(SEM) was used to examine the microstructures of the samples after thermal shock testing. Energy dispersive analysis of X-ray(EDAX) was used to analyze the interface diffusion behavior of the bond coat elements. X-ray diffractometry(XRD) was used to analyze the constituent phases of the samples. Experimental results indicate that the nanostructured TBC is superior to the conventional TBC in thermal shock performance. Both the nanostructured and conventional TBCs fail along the bond coat/substrate interface. The constituent phase of the as-sprayed conventional TBC is diffusionless-transformed tetragonal(t′). However, the constituent phase of the as-sprayed nanostructured TBC is cubic(c). There is a difference in the crystal size at the spalled surfaces of the nanostructured and conventional TBCs. The constituent phases of the spalled surfaces are mainly composed of Ni2.88Cr1.12 and oxides of bond coat elements.

  13. Thermal Conductivity and Erosion Durability of Composite Two-Phase Air Plasma Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Schmitt, Michael P.; Rai, Amarendra K.; Zhu, Dongming; Dorfman, Mitchell R.; Wolfe, Douglas E.

    2015-01-01

    To enhance efficiency of gas turbines, new thermal barrier coatings (TBCs) must be designed which improve upon the thermal stability limit of 7 wt% yttria stabilized zirconia (7YSZ), approximately 1200 C. This tenant has led to the development of new TBC materials and microstructures capable of improved high temperature performance. This study focused on increasing the erosion durability of cubic zirconia based TBCs, traditionally less durable than the metastable t' zirconia based TBCs. Composite TBC microstructures composed of a low thermal conductivity/high temperature stable cubic Low-k matrix phase and a durable t' Low-k secondary phase were deposited via APS. Monolithic coatings composed of cubic Low-k and t' Low-k were also deposited, in addition to a 7YSZ benchmark. The thermal conductivity and erosion durability were then measured and it was found that both of the Low-k materials have significantly reduced thermal conductivities, with monolithic t' Low-k and cubic Low-k improving upon 7YSZ by approximately 13 and approximately 25%, respectively. The 40 wt% t' Low-k composite (40 wt% t' Low-k - 60 wt% cubic Low-k) showed a approximately 22% reduction in thermal conductivity over 7YSZ, indicating even at high levels, the t' Low-k secondary phase had a minimal impact on thermal in the composite coating. It was observed that a mere 20 wt% t' Low-k phase addition can reduce the erosion of a cubic Low-k matrix phase composite coating by over 37%. Various mixing rules were then investigated to assess this non-linear composite behavior and suggestions were made to further improve erosion durability.

  14. Liquid Feedstock Plasma Spraying: An Emerging Process for Advanced Thermal Barrier Coatings

    Science.gov (United States)

    Markocsan, Nicolaie; Gupta, Mohit; Joshi, Shrikant; Nylén, Per; Li, Xin-Hai; Wigren, Jan

    2017-08-01

    Liquid feedstock plasma spraying (LFPS) involves deposition of ultrafine droplets of suspensions or solution precursors (typically ranging from nano- to submicron size) and permits production of coatings with unique microstructures that are promising for advanced thermal barrier coating (TBC) applications. This paper reviews the recent progress arising from efforts devoted to development of high-performance TBCs using the LFPS approach. Advancements in both suspension plasma spraying and solution precursor plasma spraying, which constitute the two main variants of LFPS, are presented. Results illustrating the different types of the microstructures that can be realized in LFPS through appropriate process parameter control, model-assisted assessment of influence of coating defects on thermo-mechanical properties and the complex interplay between pore coarsening, sintering and crystallite growth in governing thermal conductivity are summarized. The enhancement in functional performances/lifetime possible in LFPS TBCs with multilayered architectures and by incorporating new pyrochlore chemistries such as gadolinium zirconate, besides the conventional single 8 wt.% yttria-stabilized zirconia insulating ceramic layer, is specifically highlighted.

  15. Ceramic Top Coats of Plasma-Sprayed Thermal Barrier Coatings: Materials, Processes, and Properties

    Science.gov (United States)

    Bakan, Emine; Vaßen, Robert

    2017-08-01

    The ceramic top coat has a major influence on the performance of the thermal barrier coating systems (TBCs). Yttria-partially-stabilized zirconia (YSZ) is the top coat material frequently used, and the major deposition processes of the YSZ top coat are atmospheric plasma spraying and electron beam physical vapor deposition. Recently, also new thermal spray processes such as suspension plasma spraying or plasma spray-physical vapor deposition have been intensively investigated for TBC top coat deposition. These new processes and particularly the different coating microstructures that can be deposited with them will be reviewed in this article. Furthermore, the properties and the intrinsic-extrinsic degradation mechanisms of the YSZ will be discussed. Following the TBC deposition processes and standard YSZ material, alternative ceramic materials such as perovskites and hexaaluminates will be summarized, while properties of pyrochlores with regard to their crystal structure will be discussed more in detail. The merits of the pyrochlores such as good CMAS resistance as well as their weaknesses, e.g., low fracture toughness, processability issues, will be outlined.

  16. Thermal stability of Al-Mg-Sc-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei-tao; YAN De-sheng; RONG Li-jian

    2006-01-01

    The thermal stability of Al3(Sc,Zr) precipitates in the cold worked Al-Mg-Sc-Zr alloy after elevated temperature exposure was investigated. The evaluation was conducted using room temperature tensile, Vicker's hardness, optical metallography and scanning electron microscope (SEM) with the backscatter. The results show that the Al3(Sc,Zr) precipitates and mechanical properties have no obvious change, and the grains keep elongated along the working direction as that in cold worked sample after exposure at 300 ℃ for 1 000 h. The coarsening of Al3(Sc,Zr) precipitates occurs and is no longer effective on the recrystallization resistance, and partial recrystallization is observed after 400 ℃ exposure. In particular, after 500 ℃ exposure, the hardness decreases drastically and the alloy has fully recrystallized due to the obvious coarsening of Al3(Sc,Zr) precipitates.

  17. Hardness and thermal stability of cubic silicon nitride

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Kragh, Flemming; Frost, D. J.

    2001-01-01

    The hardness and thermal stability of cubic spinel silicon nitride (c-Si3N4), synthesized under high-pressure and high-temperature conditions, have been studied by microindentation measurements, and x-ray powder diffraction and scanning electron microscopy, respectively The phase at ambient...... temperature has an average hardness of 35.31 GPa, slightly larger than SiO2 stishovite, which is often referred to as the third hardest material after diamond and cubic boron nitride. The cubic phase is stable up to 1673 K in air. At 1873 K, alpha -and beta -Si3N4 phases are observed, indicating a phase...... transformation sequence of c-to-alpha -to-beta -Si3N4 phases....

  18. Thermal stability for a reactive viscous flow in a slab

    CERN Document Server

    Okoya, S S

    2002-01-01

    The paper deals with the effect of dimensionless non - Newtonian coefficient on the thermal stability of a reactive viscous liquid in steady flow between parallel heated plates. It is assumed that the liquid is symmetrically heated and the flow fully developed. Approximate analytical solution is obtained for the velocity of the flow and the criterion for which this solution is valid is determined. After the velocity distribution is known, the temperature distribution may be calculated. Criticality and disappearance of criticality (transition values) are obtained in the following cases: (i) Bimolecular (ii) Arrhenius and (iii) Sensitized temperature dependence. We have observed that nonlinear effect from velocity and temperature fields introduced decaying for the transitional values of the dimensionless central temperature. Other effects of this nonlinearity are reported. We also give results for the plane - Couette flow problem. The results help to enhance understanding of the interplay between Newtonian and ...

  19. Thermal stability of radiating fluids: The scattering problem

    Science.gov (United States)

    Bakan, Stephan

    1984-12-01

    The problem of convective instability of a radiating fluid layer with scattering is treated with an extension of the Eddington aproximation that allows the inclusion of anisotropic scattering into the solution of the radiative transfer equation. Introduction of scattering by keeping the optical depth of absorption constant reduces the critical Rayleigh number as well as the wavenumber, and thus, reduces the stabilizing influence of thermal radiation. It is shown that in cases of a narrow radiative boundary layer with a large temperature gradient, higher-order expansion terms are sometimes necessary to approximate the solution properly. In certain cases a two layer convection mode with a large critical wavenumber up to 50 sets in the first layer has two cells developing in and near the two radiative boundary layers.

  20. Thermal stability of gold-PS nanocomposites thin films

    Indian Academy of Sciences (India)

    Umananda M Bhatta; Deepa Khushalani; P V Satyam

    2011-07-01

    Low-temperature transmission electron microscopy (TEM) studies were performed on polystyrene (PS, w = 234 K) – Au nanoparticle composite thin films that were annealed up to 350°C under reduced pressure conditions. The composite thin films were prepared by wet chemical approach and the samples were then subsequently spin-coated on a carbon-coated copper grid for TEM measurements. TEM measurements were performed at liquid nitrogen temperatures to reduce the electron–beam-induced radiation damage. The results showed a marginal increase in Au nanoparticle diameter (2.3 nm–3.6 nm) and more importantly, an improved thermal stability of the polystyrene (PS) composite film much above its glass transition temperature

  1. Atmospheric Plasma Spraying of Single Phase Lanthanum Zirconate Thermal Barrier Coatings with Optimized Porosity

    Directory of Open Access Journals (Sweden)

    Georg Mauer

    2016-10-01

    Full Text Available The shortcomings at elevated operation temperatures of the standard material yttria-stabilized zirconia (YSZ for thermal barrier coatings (TBCs have initiated many research activities seeking alternatives. One candidate is the pyrochlore lanthanum zirconate La2Zr2O7 (LZ, which is phase-stable to its melting point. At the same time, it shows a lower thermal conductivity and a lower sintering tendency when compared to YSZ. Because of its low thermal expansion coefficient and poor toughness, it is applied in combination with YSZ in double layer TBC systems. It is the current state of knowledge that LZ is prone to lanthanum depletion if processed by plasma spraying. The process conditions have to be selected carefully to avoid this. Furthermore, the amount and morphology of the coating porosity is essential for a good thermo-mechanical performance. In this work, the development and testing of LZ/YSZ double layer TBC systems is described. Initially, suitable basic parameters (torch, plasma gas composition, and power were tested with respect to coating stoichiometry. Then, microstructures were optimized by adjusting feed rate, spray distance, and by selecting a more appropriate feedstock. Powder particles and coatings were characterized by digital image analysis.

  2. Ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconia

    DEFF Research Database (Denmark)

    Sillassen, M.; Eklund, P.; Sridharan, M.;

    2009-01-01

    Thermally stable, stoichiometric, cubic yttria-stabilized zirconia (YSZ) thin-film electrolytes have been synthesized by reactive pulsed dc magnetron sputtering from a Zr–Y (80/20 at. %) alloy target. Films deposited at floating potential had a texture. Single-line profile analysis of the 111 x.......5% at bias voltages of −175 and −200 V with additional incorporation of argon. The films were thermally stable; very limited grain coarsening was observed up to an annealing temperature of 800 °C. Temperature-dependent impedance spectroscopy analysis of the YSZ films with Ag electrodes showed that the in......-plane ionic conductivity was within one order of magnitude higher in films deposited with substrate bias corresponding to a decrease in grain size compared to films deposited at floating potential. This suggests that there is a significant contribution to the ionic conductivity from grain boundaries...

  3. Non-thermal atmospheric pressure plasma jet and its application for polymer treatment

    OpenAIRE

    Sarani, Abdollah

    2010-01-01

    Non-thermal atmospheric pressure plasma jet is a suitable source for polymer treatment. The main characteristic of this plasma jet is the remote operation and its scalable dimension, thus, allowing local treatment of 3D surfaces. In this work an atmospheric pressure DBD plasma jet has been constructed and the application of the plasma jet for polymer treatment is investigated.

  4. Superior Thermal Barrier Coatings Using Solution Precursor Plasma Spray

    Science.gov (United States)

    Jordan, E. H.; Xie, L.; Gell, M.; Padture, N. P.; Cetegen, B.; Ozturk, A.; Ma, X.; Roth, J.; Xiao, T. D.; Bryant, P. E. C.

    2004-03-01

    A novel process, solution precursor plasma spray (SPPS), is presented for depositing thermal barrier coatings (TBCs), in which aqueous chemical precursors are injected into a standard direct current plasma spray system. The resulting coatings microstructure has three unique features: (1) ultra fine splats (1 µm), (2) nanometer and micron-sized interconnected porosity, and (3) closely spaced, through-thickness cracks. Coatings over 3 mm thick can be readily deposited using the SPPS process. Coating durability is excellent, with SPPS coatings showing, in furnace cycling tests, 2.5 times the spallation life of air plasma coatings (APS) and 1.5 times the life of electron beam physical vapor deposited (EB-PVD) coatings. The conductivity of SPPS coatings is lower than EB-PVD coatings and higher than the best APS coatings. Manufacturing cost is expected to be similar to APS coatings and much lower than EB-PVD coatings. The SPPS deposition process includes droplet break-up and material arriving at the deposition surface in various physical states ranging from aqueous solution, gel phase, to fully-molten ceramic. The relation between the arrival state of the material and the microstructure is described.

  5. Treatment and recycling of incinerated ash using thermal plasma technology.

    Science.gov (United States)

    Cheng, T W; Chu, J P; Tzeng, C C; Chen, Y S

    2002-01-01

    To treat incinerated ash is an important issue in Taiwan. Incinerated ashes contain a considerable amount of hazardous materials such as dioxins and heavy metals. If these hazardous materials are improperly treated or disposed of, they shall cause detrimental secondary contamination. Thermal plasma vitrification is a robust technology to treat and recycle the ash residues. Under the high temperature plasma environment, incinerated ashes are vitrified into benign slag with large volume reduction and extreme detoxification. Several one-step heat treatment processes are carried out at four temperatures (i.e. 850, 950, 1,050 and 1,150 degrees C) to obtain various "microstructure materials". The major phase to form these materials is a solid solution of gehlenite (Ca2Al2SiO7) and åkermanite (Ca2MgSi2O7) belonging to the melilite group. The physical and mechanical properties of the microstructure materials are improved by using one-step post-heat treatment process after plasma vitrification. These microstructure materials with good quality have great potential to serve as a viable alternative for construction applications.

  6. Thermal stability of nafion membranes under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    Quintilii, M.; Struis, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

  7. Thermal Stability and Vertical Structure of Radiation Dominated Accretion Disks

    Science.gov (United States)

    Jiang, Yanfei; Stone, J. M.; Davis, S.

    2013-01-01

    Standard thin disk model predicts that radiation dominated accretion disk is thermally unstable. However, using a radiation MHD code based on flux-limited diffusion (FLD) approximation, Hirose et al. (2009) finds that when the accretion stress provided by Magneto-rotational instability (MRI) is calculated self-consistently, the disk is actually stable. We check this surprising result with our recently developed radiation transfer module in Athena. We modify the Godunov method to include the radiation source terms and close the radiation momentum equations with variable Eddington tensor. In this way, it works in both optically thin and thick regimes, and works for both radiation or gas pressure dominated flows. As a general purpose radiation MHD code, it can also be used to study other systems, where radiation field plays an important role, such as feedback effects of stars on the interstellar medium. I will show a set of tests to demonstrate that the code is working accurately as expected for different regimes. I will describe in detail our results on the thermal stability of accretion disks in both the gas pressure dominated regime and radiation pressure dominated regime. Detailed studies of the vertical structures of the accretion disk will also be presented. I will also comment on the differences between our results and the results from FLD calculations.

  8. Thermal Stability and Material Balance of Nanomaterials in Waste Incineration

    Science.gov (United States)

    Paur, H.-R.; Baumann, W.; Hauser, M.; Lang, I.; Teuscher, N.; Seifert, H.; Stapf, D.

    2017-06-01

    Nanostructured materials are widely used to improve the properties of consumer products such as tires, cosmetics, light weight equipment etc. Due to their complex composition these products are hardly recycled and thermal treatment is preferred. In this study we investigated the thermal stability and material balance of nanostructured metal oxides in flames and in an industrial waste incinerator. We studied the size distribution of nanostructured metal oxides (CeO2, TiO2, SiO2) in a flame reactor and in a heated reaction tube. In the premixed ethylene/air flame, nano-structured CeO2 partly evaporates forming a new particle mode. This is probably due to chemical reactions in the flame. In addition sintering of agglomerates takes place in the flame. In the electrically heated reaction tube however only sintering of the agglomerated nanomaterials is observed. Ceria has a low background in waste incinerators and is therefore a suitable tracer for investigating the fate of nanostructured materials. Low concentrations of Ceria were introduced by a two-phase nozzle into the post-combustion zone of a waste incinerator. By the incineration of coal dust in a burning chamber the Ceria nanoparticles are mainly found in the size range of the fly ash (1 - 10 µm) because of agglomeration. With gas as a fuel less agglomeration was observed and the Ceria nanoparticles were in the particle size range below 1 µm.

  9. Thermal stability and kinetic of decomposition of nitrated HTPB.

    Science.gov (United States)

    Wang, Qingfa; Wang, Li; Zhang, Xiangwen; Mi, Zhentao

    2009-12-30

    Nitrated HTPB (NHTPB) is a potential energetic binder to replace the conventional inert binder, HTPB, for the composite solid propellants and plastic bonded explosives (PBXs). The thermal stability of the NHTPB sample with 10% double bonds converted to dinitrate ester group (10% NHTPB) was evaluated by high-pressure differential scanning calorimeter (PDSC) measurement. The influences of pressure (0.1, 2.5 and 5.0 MPa) and the heating rate (4, 6, 8 and 10 degrees C min(-1)) on the DSC behavior of the 10% NHTPB sample were investigated. The decomposition temperature of this compound decreased with the increase of pressure, meanwhile, increased as the heating rate increasing. The thermal decomposition at 150-250 degrees C followed a first-order law. The kinetic parameters and thermodynamic parameters for the 10% NHTPB sample at 150-250 degrees C under ambient pressure were obtained from the DSC data by non-isothermal methods proposed by ASTM E698 and Flynn-Wall-Ozawa. The critical temperature for this compound was estimated at about 154 degrees C.

  10. Investigation on plasma-sprayed ZrO2 thermal barrier coating on nickel alloy substrate

    Institute of Scientific and Technical Information of China (English)

    卢安贤; 常鹰; 蔡小梅

    2002-01-01

    The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY-Y2O3 stabilized ZrO2 transition layer and Y2O3 stabilized ZrO2 ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investiga-ted by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introdu-cing a transition layer between Ni alloy substrate and ZrO2 ceramic coating guarantees the high quality and properties of the coatings; ZrO2 coatings doped with a little SiO2 possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO2 coating materials without SiO2 ;the improvement in performance of ZrO2 coating doped with SiO2 is due to forming more dense coating structure by self- closing effects of the flaws and pores in the ZrO2 coatings.

  11. Role of external magnetic field and current closure in the force balance mechanism of a magnetically stabilized plasma torch

    Science.gov (United States)

    G, Ravi; Goyal, Vidhi

    2012-10-01

    Experimental investigations on the role of applied external magnetic field and return current closure in the force balance mechanism of a plasma torch are reported. The plasma torch is of low power and has wall, gas and magnetic stabilization mechanisms incorporated in it. Gas flow is divided into two parts: axial-central and peripheral-shroud, applied magnetic field is axial and return current is co-axial. Results indicate that application of large external magnetic field gives rise to not only J x B force but also, coupled with gas flow, to a new drag-cum-centrifugal force that acts on the plasma arc root and column. The magnetic field also plays a role in the return current closure dynamics and thus in the overall force balance mechanism. This in turn affects the electro-thermal efficiency of the plasma torch. Detailed experimental results, analytical calculations and physical model representing the processes will be presented and discussed.

  12. Some applications of thermal field theory to quark-gluon plasma

    Indian Academy of Sciences (India)

    Munshi G Mustafa

    2006-04-01

    We briefly introduce the thermal field theory within imaginary time formalism, the hard thermal loop perturbation theory and some of its applications to the physics of the quark-gluon plasma, possibly created in relativistic heavy-ion collisions.

  13. Thermal stability of water ice in Ceres' crater Oxo

    Science.gov (United States)

    Formisano, Michelangelo; Federico, Costanzo; De Sanctis, Maria Cristina; Frigeri, Alessandro; Magni, Gianfranco; Tosi, Federico

    2016-10-01

    Dwarf planet Ceres, target of the NASA Dawn mission, exhibits evidences of ammoniated phyllosilicates on its surface [1], compatible with a likely outer Solar System origin. Considerable amounts of water ice have recently been detected in some craters by the Visible InfraRed mapping spectrometer (VIR) onboard Dawn in some small fresh crater, such as Oxo, located at about 40° N. The exposure mechanism of water ice is unknown: cryovolcanism, cometary type sublimation/recondensation [2]or impacts with other bodies are likely mechanisms. The evaluation of the time stability of the water ice is crucial to understand the plausible mechanism for its existence. For this purpose, we developed a 3D finite-elements model (FEM) by using the topography given by the shape model of Ceres derived on the basis of images acquired by the Framing Camera in the Survey mission phase. The illumination conditions are provided by the SPICE toolkit. We performed several simulations by analyzing the effect of thermal inertia and albedo on the temperature and rate of ice sublimation. The results of the simulations about the stability of water ice will be presented.[1] De Sanctis et al. NATURE, doi:10.1038/nature16172[2] Formisano et al. MNRAS, doi: 10.1093/mnras/stv2344

  14. Effect of cation trapping on thermal stability of magnetite nanoparticles.

    Science.gov (United States)

    Pati, S S; Philip, John

    2014-06-01

    We investigate the effect of sodium trapping on thermal stability of magnetite (Fe3O4) nanoparticles. The pure magnetite nanoparticles incubated in sodium hydroxide solutions and subsequently washed with water to remove the excess sodium. The amount of sodium in magnetite is measured using atomic absorption spectroscopy. The size distribution obtained from Small angle X-ray scattering measurements show that particles are fairly monodisperse. The FTIR spectra of nanoparticles show transmission bands at 441 and 611 cm(-1) are due to the symmetric stretching vibrations (v) of Fe-O in octahedral and tetrahedral sites respectively. With 500 ppm of sodium ions (Na+) in magnetite, the cubic ferrite structure of maghemite (gamma-Fe2O3) to hexagonal hematite (alpha-Fe2O3) phase transition is enhanced by -150 degrees C in air. The Rietveld analysis of sodium doped magnetite nanoparticles show that above 99% of metastable gamma-Fe2O3 is converted to a thermodynamically stable alpha-Fe2O3 after air annealing at 700 degrees C. A decrease in enthalpy observed in doped magnetite unambiguously confirms that the activation energy for maghemite to hematite transition is increased due to the presence of trapped sodium ions. These results suggest that the trapped cations in ferrite nanoparticles can stabilize them by increasing the activation energy.

  15. Thermal stability of graphene edge structure and graphene nanoflakes

    Science.gov (United States)

    Barnard, Amanda S.; Snook, Ian K.

    2008-03-01

    One of the most exciting recent developments in nanoscience was the discovery of graphene (single sheets of carbon atoms, a two-dimensional ``(2D) crystal'') and the subsequent discovery of the fascinating properties of this new material, e.g., electrons behaving as massless relativistic particles and an anomalous quantum Hall effect [A. K. Geim and K. S. Novoselov, Nat. Mater. 6, 183 (2007)]. It is also surprising that large sheets of graphene exist as it was widely believed that 2D crystals are unstable. Furthermore, because of the stability of folded graphene sheets, i.e., carbon nanotubes (CNTs), a fascinating question is why does not graphene spontaneously transform into CNTs? In this paper, we explore the thermal stability of small pieces of graphene, i.e., graphene nanoflakes by ab initio quantum mechanical techniques. We find that indeed nanoflakes are stable to being heated and do not under any conditions used here transform to CNTs. They do not, however, remain strictly 2D as at finite temperatures, they undergo extensive vibrational motion and remain buckled if annealed and then quenched to room temperature.

  16. Synthesis, solubility, plasma stability, and pharmacological evaluation of novel sulfonylhydrazones designed as anti-diabetic agents

    Directory of Open Access Journals (Sweden)

    Zapata-Sudo G

    2016-09-01

    Full Text Available Gisele Zapata-Sudo,1,2 Isabelle Karine da Costa Nunes,2 Josenildo Segundo Chaves Araujo,1,2 Jaqueline Soares da Silva,2 Margarete Manhães Trachez,2,3 Tiago Fernandes da Silva,1 Filipe P da Costa,2 Roberto Takashi Sudo,1,2 Eliezer J Barreiro,1,2 Lídia Moreira Lima1,2 1National Institute of Science and Technology on Drugs and Medicines, Federal University of Rio de Janeiro, Laboratory of Evaluation and Synthesis of Bioactive Compounds, Center of Health Sciences, Rio de Janeiro, Brazil; 2Program of Research in Drug Development, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; 3Department of Anesthesiology, Fluminense Federal University, Rio de Janeiro, Brazil Abstract: Neuropathy is a serious complication of diabetes that has a significant socioeconomic impact, since it frequently demands high levels of health care consumption and compromises labor productivity. Recently, LASSBio-1471 (3 was demonstrated to improve oral glucose tolerance, reduce blood glucose levels, and display an anti-neuropathy effect in a murine streptozotocin-induced diabetes model. In the present work, we describe the design, synthesis, solubility, plasma stability, and pharmacological evaluation of novel sulfonylhydrazone derivatives (referred to herein as compounds 4–9, which were designed by molecular modification based on the structure of the prototype LASSBio-1471 (3. Among the compounds tested, better plasma stability was observed with 4, 5, and 9 in comparison to compounds 6, 7, and 8. LASSBio-1773 (7, promoted not only hypoglycemic activity but also the reduction of thermal hyperalgesia and mechanical allodynia in a murine model of streptozotocin-induced diabetic neuropathic pain. Keywords: diabetes, sulfonylhydrazone, hypoglycemic activity, druglikeness, plasma stability, metabolite

  17. Thermal behavior of bovine serum albumin after exposure to barrier discharge helium plasma jet

    Science.gov (United States)

    Jijie, R.; Pohoata, V.; Topala, I.

    2012-10-01

    Non-thermal plasma jets at atmospheric pressure are useful tools nowadays in plasma medicine. Various applications are tested such as cauterization, coagulation, wound healing, natural and artificial surfaces decontamination, and sterilization. In order to know more about the effects of gas plasma on biological supramolecules, we exposed protein powders to a barrier discharge helium plasma jet. Then, spectroscopic investigations were carried out in order to obtain information on protein secondary, tertiary, and quaternary structures. We obtained a reduction of the protein alpha-helix content after the plasma exposure and a different behavior, for both thermal denaturation/renaturation kinetics and thermal aggregation process.

  18. Dust-acoustic waves and stability in the permeating dust plasma: II. Power-law distributions

    CERN Document Server

    Gong, Jingyu; Du, Jiulin

    2012-01-01

    The dust-acoustic waves and their stability driven by a flowing dust plasma when it cross through a static (target) dust plasma (the so-called permeating dust plasma) are investigated when the components of the dust plasma obey the power-law q-distributions in nonextensive statistics. The frequency, the growth rate and the stability condition of the dust-acoustic waves are derived under this physical situation, which express the effects of the nonextensivity as well as the flowing dust plasma velocity on the dust-acoustic waves in this dust plasma. The numerical results illustrate some new characteristics of the dust-acoustic waves, which are different from those in the permeating dust plasma when the plasma components are the Maxwellian distribution. In addition, we show that the flowing dust plasma velocity has a significant effect on the dust-acoustic waves in the permeating dust plasma with the power-law q-distribution.

  19. Stabilizing the Advancing Front of Thermally Driven Climbing Films.

    Science.gov (United States)

    Kataoka; Troian

    1998-07-15

    As known from thermodynamic principles, the surface tension of a liquid decreases with increasing temperature. This property can be used to force a liquid film to climb a vertical substrate whose lower end is held warmer than the top. The vertical gradient in surface tension generates a surface shear stress that causes the liquid film to spread upward spontaneously in the direction of higher surface tension. Experimental investigations have shown that the application of a large temperature gradient produces a thin climbing film whose leading edge develops a pronounced capillary rim which breaks up into vertical rivulets. In contrast, smaller temperature gradients produce thicker films whose profiles decrease monotonically toward the substrate with no evidence of a rim or subsequent film breakup. We have previously shown within linear stability analysis that a climbing film can undergo a fingering instability at the leading edge when the film is sufficiently thin or the shear stress sufficiently large for gravitational effects to be negligible. In this work we show that thicker films which experience significant drainage cannot form a capillary rim and spread in stable fashion. Gravitational drainage helps promote a straight advancing front and complete surface coverage. Our numerical predictions for the entire shape and stability of the climbing film are in good agreement with extensive experiments published years ago by Ludviksson and Lightfoot (AIChE J. 17, 1166 (1971)). We propose that the presence of a counterflow which eliminates the capillary rim can provide a simple and general technique for stabilizing thermally driven films in other geometries. Copyright 1998 Academic Press.

  20. Evaluation of the Lifetime and Thermal Conductivity of Dysprosia-Stabilized Thermal Barrier Coating Systems

    Science.gov (United States)

    Curry, Nicholas; Markocsan, Nicolaie; Östergren, Lars; Li, Xin-Hai; Dorfman, Mitch

    2013-08-01

    The aim of this study was the further development of dysprosia-stabilized zirconia coatings for gas turbine applications. The target for these coatings was a longer lifetime and higher insulating performance compared to today's industrial standard thermal barrier coating. Two morphologies of ceramic top coat were studied: one using a dual-layer system and the second using a polymer to generate porosity. Evaluations were carried out using a laser flash technique to measure thermal properties. Lifetime testing was conducted using thermo-cyclic fatigue testing. Microstructure was assessed with SEM and Image analysis was used to characterize porosity content. The results show that coatings with an engineered microstructure give performance twice that of the present reference coating.

  1. An experimental study on thermal stability of biodiesel fuel

    Science.gov (United States)

    Zhu, Yiying

    Biodiesel fuel, as renewable energy, has been used in conventional diesel engines in pure form or as biodiesel/diesel blends for many years. However, thermal stability of biodiesel and biodiesel/diesel blends has been minimally explored. Aimed to shorten this gap, thermal stability of biodiesel is investigated at high temperatures. In this study, batch thermal stressing experiments of biodiesel fuel were performed in stainless steel coils at specific temperature and residence time range from 250 to 425 °C and 3 to 63 minutes, respectively. Evidence of different pathways of biodiesel fuel degradation is demonstrated chromatographically. It was found that biodiesel was stable at 275 °C for a residence time of 8 minutes or below, but the cis-trans isomerization reaction was observed at 28 minutes. Along with isomerization, polymerization also took place at 300 °C at 63 minutes. Small molecular weight products were detected at 350 °C at 33 minutes resulting from pyrolysis reactions and at 360 °C for 33 minutes or above, gaseous products were produced. The formed isomers and dimers were not stable, further decomposition of these compounds was observed at high temperatures. These three main reactions and the temperature ranges in which they occurred are: isomerization, 275--400 °C; polymerization (Diels-Alder reaction), 300--425 °C; pyrolysis reaction, ≥350 °C. The longer residence time and higher temperature resulted in greater decomposition. As the temperature increased to 425 °C, the colorless biodiesel became brownish. After 8 minutes, almost 84% of the original fatty acid methyl esters (FAMEs) disappeared, indicating significant fuel decomposition. A kinetic study was also carried out subsequently to gain better insight into the biodiesel thermal decomposition. A three-lump model was proposed to describe the decomposition mechanism. Based on this mechanism, a reversible first-order reaction kinetic model for the global biodiesel decomposition was shown to

  2. Metal lanolin fatty acid as novel thermal stabilizers for rigid poly(vinyl chloride)

    Institute of Scientific and Technical Information of China (English)

    GUO Yong; ZHENG Yuying; QIU Shangchang; ZENG Anran; LI Baoming

    2011-01-01

    The synergistic stabilization effect of different metal lanolin fatty acids as natural-based thermal stabilizers for poly(vinyl chloride)(PVC) including calcium lanolin fatty acid (Calan2), zinc lanolin fatty acid (Znlan2) and lanthanum lanolin fatty acid (Lalan3) were studied through Congo red testing, color measurements, FTIR analyses and thermal behavior in this paper. The results showed that Lalan3/Calan2/Znlan2 stabilizers exhibited more excellent thermal stabilization efficiency to PVC than Calan2/Znlan2 thermal stabilizers, and the optimal mass ratio of Lalan3/Calan2/Znlan2 was 8:9:3. At last, the effect of degradation mechanism on PVC and synergistic stabilization was also investigated by FTIR analyses and thermal behavior.

  3. Cell death induced by ozone and various non-thermal plasmas: therapeutic perspectives and limitations

    Science.gov (United States)

    Lunov, Oleg; Zablotskii, Vitalii; Churpita, Olexander; Chánová, Eliška; Syková, Eva; Dejneka, Alexandr; Kubinová, Šárka

    2014-11-01

    Non-thermal plasma has been recognized as a promising tool across a vast variety of biomedical applications, with the potential to create novel therapeutic methods. However, the understanding of the molecular mechanisms behind non-thermal plasma cellular effects remains a significant challenge. In this study, we show how two types of different non-thermal plasmas induce cell death in mammalian cell cultures via the formation of multiple intracellular reactive oxygen/nitrogen species. Our results showed a discrepancy in the superoxide accumulation and lysosomal activity in response to air and helium plasma, suggesting that triggered signalling cascades might be grossly different between different plasmas. In addition, the effects of ozone, a considerable component of non-thermal plasma, have been simultaneously evaluated and have revealed much faster and higher cytotoxic effects. Our findings offer novel insight into plasma-induced cellular responses, and provide a basis for better controlled biomedical applications.

  4. Investigation of mechanical properties of thermal coatings obtained during plasma spraying of powder zirconium dioxide

    Science.gov (United States)

    Ibragimov, A. R.; Ilinkova, T. A.; Shafigullin, L. N.; Saifutdinov, A. I.

    2017-01-01

    Thermal coatings of zirconia partially stabilized with yttrium, deposited by low-temperature plasma, are the basis for the thermal protection of aircraft engine. At the same time there is an actual problem of selection of coating systems “ceramic layer - underlayer” of great thickness, providing better thermal protection, but having low strength characteristics due to the accumulation of internal stresses. To determine the optimal thickness of the test method used in the 4-point bending to allow the surface coating to explore in the elastic-plastic behavior of the field of coatings and strength. Based on the experimental results established the role of underlayer in the formation of the complex mechanical properties of thermal barrier coatings. With a well formed underlayer (PVNH16U6) system becomes sensitive to a change in thickness of the coating, to optimize the response on the strength and deformation criteria. According to the results the optimum ratio of the thickness of the ceramic layer and the underlayer should be regarded as the ratio of 3-5 for which the highest strength values were obtained for all the test coating systems.

  5. Final treatment of spent batteries by thermal plasma.

    Science.gov (United States)

    Cubas, Anelise Leal Vieira; Machado, Marina de Medeiros; Machado, Marília de Medeiros; Dutra, Ana Regina de Aguiar; Moecke, Elisa Helena Siegel; Fiedler, Haidi D; Bueno, Priscila

    2015-08-15

    The growth in the use of wireless devices, notebooks and other electronic products has led to an ever increasing demand for batteries, leading to these products being commonly found in inappropriate locations, with adverse effects on the environment and human health. Due to political pressure and according to the environmental legislation which regulates the destination of spent batteries, in several countries the application of reverse logistics to hazardous waste is required. Thus, some processes have been developed with the aim of providing an appropriate destination for these products. In this context, a method for the treatment of spent batteries using thermal plasma technology is proposed herein. The efficiency of the method was tested through the determination of parameters, such as total organic carbon, moisture content and density, as well as analysis by atomic absorption spectrometry, scanning electron microscopy and X-ray fluorescence using samples before and after inertization. The value obtained for the density was 19.15%. The TOC results indicated 8.05% of C in the batteries prior to pyrolisis and according to the XRF analysis Fe, S, Mn and Zn were the most stable elements in the samples (highest peaks). The efficiency of the paste inertization was 97% for zinc and 99.74% for manganese. The results also showed that the most efficient reactor was that with the DC transferred arc plasma torch and quartzite sand positively influenced by the vitrification during the pyrolysis of the electrolyte paste obtain from batteries.

  6. Star formation through thermal instability of radiative plasma with finite electron inertia and finite Larmor radius corrections

    Directory of Open Access Journals (Sweden)

    Sachin Kaothekar

    2016-08-01

    Full Text Available I have studied the effects of finite electron inertia, finite ion Larmor radius (FLR corrections, and radiative heat-loss function on the thermal instability of an infinite homogeneous, viscous plasma incorporating the effect of thermal conductivity for star formation in interstellar medium (ISM. A general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. The wave propagation is discussed for longitudinal and transverse directions to the external magnetic field and the conditions of modified thermal instabilities and stabilities are discussed in different cases. We find that the thermal instability criterion is get modified into radiative instability criterion by inclusion of radiative heat-loss functions with thermal conductivity. The viscosity of medium removes the effect of FLR corrections from the condition of radiative instability. Numerical calculation shows stabilizing effect of heat-loss function, viscosity and FLR corrections, and destabilizing effect of finite electron inertia on the thermal instability. Results carried out in this paper shows that stars are formed in interstellar medium mainly due to thermal instability.

  7. Suppression of thermal conduction in a mirror-unstable plasma

    CERN Document Server

    Komarov, S V; Kunz, M W; Schekochihin, A A

    2016-01-01

    The ICM plasma is subject to firehose and mirror instabilities at scales of order the ion Larmor radius. The mirror instability generates fluctuations of magnetic-field strength $\\delta B / B \\sim 1$. These fluctuations act as magnetic traps for the heat-conducting electrons, suppressing their transport. We calculate the effective parallel thermal conductivity in the ICM in the presence of the mirror fluctuations for different stages of the evolution of the instability. The mirror fluctuations are limited in amplitude by the maximum and minimum values of the field strength, with no large deviations from the mean value. This key property leads to a finite suppression of thermal conduction at large scales. We find suppression down to $\\approx 0.2$ of the Spitzer value for the secular phase of the perturbations' growth, and $\\approx 0.3$ for their saturated phase. The effect operates in addition to other suppression mechanisms and independently of them. Globally, fluctuations $\\delta B / B \\sim 1$ can be present...

  8. Using plasma-fuel systems at Eurasian coal-fired thermal power stations

    Science.gov (United States)

    Karpenko, E. I.; Karpenko, Yu. E.; Messerle, V. E.; Ustimenko, A. B.

    2009-06-01

    The development of plasma technology for igniting solid fuels at coal-fired thermal power stations in Russia, Kazakhstan, China, and other Eurasian countries is briefly reviewed. Basic layouts and technical and economic characteristics of plasma-fuel systems installed in different coal-fired boiles are considered together with some results from using these systems at coal-fired thermal power stations.

  9. Using plasma-fuel systems at Eurasian coal-fired thermal power stations

    Energy Technology Data Exchange (ETDEWEB)

    E.I. Karpenko; Y.E. Karpenko; V.E. Messerle; A.B. Ustimenko [RAO Unified Energy Systems of Russia, Gusinoozersk (Russian Federation). Russia Sectional Center for Plasma-Power Technologies

    2009-07-01

    The development of plasma technology for igniting solid fuels at coal-fired thermal power stations in Russia, Kazakhstan, China, and other Eurasian countries is briefly reviewed. Basic layouts and technical and economic characteristics of plasma-fuel systems installed in different coal-fired boiles are considered together with some results from using these systems at coal-fired thermal power stations.

  10. Electric field effects in combustion with non-thermal plasma

    Science.gov (United States)

    Casey, Tiernan Albert

    Chemically reacting zones such as flames act as sources of charged species and can thus be considered as weakly-ionized plasmas. As such, the action of an externally applied electric field has the potential to affect the dynamics of reaction zones by enhancing transport, altering the local chemical composition, activating reaction pathways, and by providing additional thermal energy through the interaction of electrons with neutral molecules. To investigate these effects, one-dimensional simulations of reacting flows are performed including the treatment of charged species transport and non-thermal electron chemistry using a modified reacting fluid solver. A particular area of interest is that of plasma assisted ignition, which is investigated in a canonical one-dimensional configuration. An incipient ignition kernel, formed by localized energy deposition into a lean mixture of methane and air at atmospheric pressure, is subjected to sub-breakdown electric fields by applied voltages across the domain, resulting in non-thermal behavior of the electron sub-fluid formed during the discharge. Strong electric fields cause charged species to be rapidly transported from the ignition zone across the domain in opposite directions as charge fronts, augmenting the magnitude of the electric field in the fresh gas during the pulse through a dynamic-electrode effect. This phenomenon results in an increase in the energy of the electrons in the fresh mixture with increasing time, accelerating electron impact dissociation processes. A semi-analytic model to represent this dynamic electrode effect is constructed to highlight the relative simplicity of the electrodynamic problem admitted by the far more detailed chemistry and transport. Enhanced fuel and oxidizer decomposition due to electron impact dissociation and interaction with excited neutrals generate a pool of radicals, mostly O and H, in the fresh gas ahead of the flame's preheat zone. The effect of nanosecond pulses are to

  11. Kinetic study of solid phase crystallisation of expanding thermal plasma deposited a-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Law, F., E-mail: felixlaw@nus.edu.sg [Solar Energy Research Institute of Singapore (SERIS), National University of Singapore (Singapore); Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore (Singapore); Hoex, B. [Solar Energy Research Institute of Singapore (SERIS), National University of Singapore (Singapore); Wang, J. [Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore (Singapore); Luther, J. [Solar Energy Research Institute of Singapore (SERIS), National University of Singapore (Singapore); Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore (Singapore); Sharma, K.; Creatore, M.; Van de Sanden, M.C.M. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven (Netherlands)

    2012-06-30

    In-situ X-ray diffraction was used to study the dynamics of the solid phase crystallisation (SPC) of hydrogenated amorphous silicon (a-Si:H) films deposited by expanding thermal plasma technique. The Johnson-Mehl-Avrami-Kolmogorov model was used for the analysis of the dynamic data and the activation energy associated with the SPC process was 2.9 eV, which was lower than a-Si:H films deposited by other techniques. Relationships between the Avrami exponent n, the SPC process stability and the subsequent grain structure were demonstrated. Under certain conditions, the films exhibited columnar grain structure with indications of good grain quality, suggesting that these films are suitable to be further developed into solar cell devices. Structure of the grains and the SPC dynamics in this work lend support to prior work that vacancies decorated by hydrogen clusters are related to nucleation sites. - Highlights: Black-Right-Pointing-Pointer The crystallisation of expanding thermal plasma (ETP) deposited a-Si:H was studied. Black-Right-Pointing-Pointer Johnson-Mehl-Avrami-Kolmogorov model was used to model the crystallisation process. Black-Right-Pointing-Pointer Activation energy of the solid phase crystallisation process was 2.9 eV. Black-Right-Pointing-Pointer Vacancies decorated by hydrogen clusters are suggested nucleation sites. Black-Right-Pointing-Pointer ETP is promising in the fabrication process of pc-Si thin film solar cells.

  12. Thermal stability of ladderane lipids as determined by hydrous pyrolysis

    Science.gov (United States)

    Jaeschke, A.; Lewan, M.D.; Hopmans, E.C.; Schouten, S.; Sinninghe, Damste J.S.

    2008-01-01

    Anaerobic ammonium oxidation (anammox) has been recognized as a major process resulting in loss of fixed inorganic nitrogen in the marine environment. Ladderane lipids, membrane lipids unique to anammox bacteria, have been used as markers for the detection of anammox in marine settings. However, the fate of ladderane lipids after sediment burial and maturation is unknown. In this study, anammox bacterial cell material was artificially matured by hydrous pyrolysis at constant temperatures ranging from 120 to 365 ??C for 72 h to study the stability of ladderane lipids during progressive dia- and catagenesis. HPLC-MS/MS analysis revealed that structural alterations of ladderane lipids already occurred at 120 ??C. At temperatures >140 ??C, ladderane lipids were absent and only more thermally stable products could be detected, i.e., ladderane derivatives in which some of the cyclobutane rings were opened. These diagenetic products of ladderane lipids were still detectable up to temperatures of 260 ??C using GC-MS. Thus, ladderane lipids are unlikely to occur in ancient sediments and sedimentary rocks, but specific diagenetic products of ladderane lipids will likely be present in sediments and sedimentary rocks of relatively low maturity (i.e., C31 hopane 22S/(22S + 22R) ratio 0.5). ?? 2008 Elsevier Ltd.

  13. Thermal stability and curing kinetics of polycarbosilane fibers

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Thermal stability and curing kinetics of polycarbosilane (PCS) fibers were studied by thermogravimetry (TG), Fourier transform infrared spectroscopy(FT-IR). Curing is an essential step in the preparation of SiC fibers and the properties of SiC fibers are affected greatly by curing conditions. TG measurement performed in air shows that mass gain starts at approximately 200℃ and PCS fibers are sensitive to oxygen. Curing with oxygen, which results in crosslinking on the surface, enabled PCS fibers to retain its shape during high-temperature pyrolysis. The curing of PCS fibers is oxidation of Si-H and Si-CH3, then Si-O-Si and Si-O-C bonds are formed. This is a first order reaction, with activation energy of 79.27 kJ/mol, and the pre-exponential factor is calculated as 3.07 × 106.The kinetics model was obtained and the experimental data of PCS fibers show good agreement with the kinetics model.

  14. Synthesis, thermal stability, and photocatalytic activity of nanocrystalline titanium carbide

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Youjian; Zhang, Hong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma, DeKun [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Nanomaterials and Chemistry Key Laboratory, Advanced Materials Research Center of Wenzhou, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma, Jianhua, E-mail: mjh820@ustc.edu [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Nanomaterials and Chemistry Key Laboratory, Advanced Materials Research Center of Wenzhou, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ye, Hongnan; Qian, Gaojin; Ye, Yi [Oujiang College, Wenzhou University, Wenzhou, Zhejiang 325027 (China)

    2011-11-15

    Highlights: {yields} The synthesized temperature is lower than some conventional methods. {yields} These raw materials are safe; all manipulations are rather safe and convenient. {yields} The product exhibits photocatalytic activity in degradation of Rhodamine-B. -- Abstract: Titanium carbide (TiC) was prepared via one simple route by the reaction of metallic magnesium powders with titanium dioxide (TiO{sub 2}) and potassium acetate (CH{sub 3}COOK) in an autoclave at 600 {sup o}C and 8 h. Phase structure and morphology were characterized by X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). The results indicated that the product was cubic TiC, which consisted of particles with an average size of about 100 nm in diameter. The product was also studied by the thermogravimetric analysis (TGA) and its photocatalysis. It had good thermal stability and oxidation resistance below 350 {sup o}C in air. In addition, we discovered that the cubic TiC powders exhibited photocatalytic activity in degradation of Rhodamine-B (RhB) under 500 W mercury lamp light irradiation.

  15. Increasing plasma parameters using sheared flow stabilization of a Z-pinch

    Science.gov (United States)

    Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Forbes, E. G.; Golingo, R. P.; Hughes, M. C.; Oberto, R. J.; Ross, M. P.; Weber, T. R.

    2017-05-01

    The ZaP and ZaP-HD Flow Z-pinch experiments at the University of Washington have successfully demonstrated that sheared plasma flows can be used as a stabilization mechanism over a range of parameters that has not previously been accessible to long-lived Z-pinch configurations. The stabilization is effective even when the plasma column is compressed to small radii, producing predicted increases in magnetic field and electron temperature. The flow shear value, extent, and duration are shown to be consistent with theoretical models of the plasma viscosity, which places a design constraint on the maximum axial length of a sheared flow stabilized Z-pinch. Measurements of the magnetic field topology indicate simultaneous azimuthal symmetry and axial uniformity along the entire 100 cm length of the Z-pinch plasma. Separate control of plasma acceleration and compression has increased the accessible plasma parameters and has generated stable plasmas with radii of 0.3 cm, as measured with a high resolution digital holographic interferometer. Compressing the plasma with higher pinch currents has produced high magnetic fields (8.5 T) and electron temperatures (1 keV) with an electron density of 2 ×1017 cm-3, while maintaining plasma stability for many Alfvén times (approximately 50 μs). The results suggest that sheared flow stabilization can be applied to extend Z-pinch plasma parameters to high energy densities.

  16. Thermal plasma technology for the treatment of wastes: a critical review.

    Science.gov (United States)

    Gomez, E; Rani, D Amutha; Cheeseman, C R; Deegan, D; Wise, M; Boccaccini, A R

    2009-01-30

    This review describes the current status of waste treatment using thermal plasma technology. A comprehensive analysis of the available scientific and technical literature on waste plasma treatment is presented, including the treatment of a variety of hazardous wastes, such as residues from municipal solid waste incineration, slag and dust from steel production, asbestos-containing wastes, health care wastes and organic liquid wastes. The principles of thermal plasma generation and the technologies available are outlined, together with potential applications for plasma vitrified products. There have been continued advances in the application of plasma technology for waste treatment, and this is now a viable alternative to other potential treatment/disposal options. Regulatory, economic and socio-political drivers are promoting adoption of advanced thermal conversion techniques such as thermal plasma technology and these are expected to become increasingly commercially viable in the future.

  17. Non-thermal Dupree diffusivity and shielding effects on atomic collisions in astrophysical turbulent plasmas

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2016-02-01

    The influence of non-thermal Dupree turbulence and the plasma shielding on the electron-ion collision is investigated in astrophysical non-thermal Lorentzian turbulent plasmas. The second-order eikonal analysis and the effective interaction potential including the Lorentzian far-field term are employed to obtain the eikonal scattering phase shift and the eikonal collision cross section as functions of the diffusion coefficient, impact parameter, collision energy, Debye length and spectral index of the astrophysical Lorentzian plasma. It is shown that the non-thermal effect suppresses the eikonal scattering phase shift. However, it enhances the eikonal collision cross section in astrophysical non-thermal turbulent plasmas. The effect of non-thermal turbulence on the eikonal atomic collision cross section is weakened with increasing collision energy. The variation of the atomic cross section due to the non-thermal Dupree turbulence is also discussed.

  18. Enhanced thermal stability of lysosomal beta-D-galactosidase in parenchymal cells of tumour bearing mice.

    OpenAIRE

    1986-01-01

    The thermal stability of the enzyme beta-D-galactosidase varies among different organs in normal C57Bl/6 mice, and increases in the same organs in mice with Lewis Lung carcinoma. Thermal stability of this enzyme is also increased by treatment of the mice with cell-free extracts of tumour cells or with inflammatory compounds such as carrageenan or orosomucoid. After desialylation, orosomucoid more effectively increases the heat stability of the enzyme. By contrast talc, which has no galactosyl...

  19. Thermal analysis of the in-vessel components of the ITER plasma-position reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Quental, P. B., E-mail: pquental@ipfn.tecnico.ulisboa.pt; Policarpo, H.; Luís, R.; Varela, P. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2016-11-15

    The ITER plasma position reflectometry system measures the edge electron density profile of the plasma, providing real-time supplementary contribution to the magnetic measurements of the plasma-wall distance. Some of the system components will be in direct sight of the plasma and therefore subject to plasma and stray radiation, which may cause excessive temperatures and stresses. In this work, thermal finite element analysis of the antenna and adjacent waveguides is conducted with ANSYS V17 (ANSYS® Academic Research, Release 17.0, 2016). Results allow the identification of critical temperature points, and solutions are proposed to improve the thermal behavior of the system.

  20. Evaluation of non-thermal plasma-induced anticancer effects on human colon cancer cells

    Science.gov (United States)

    Choi, Jae-Sun; Kim, Jeongho; Hong, Young-Jun; Bae, Woom-Yee; Choi, Eun Ha; Jeong, Joo-Won; Park, Hun-Kuk

    2017-01-01

    Non-thermal atmospheric-pressure plasma has been introduced in various applications such as sterilization, wound healing, blood coagulation, and other biomedical applications. The most attractive application of non-thermal atmospheric-pressure plasma is in cancer treatment, where the plasma is used to produce reactive oxygen species (ROS) to facilitate cell apoptosis. We investigate the effects of different durations of exposure to dielectric-barrier discharge (DBD) plasma on colon cancer cells using measurement of cell viability and ROS levels, western blot, immunocytochemistry, and Raman spectroscopy. Our results suggest that different kinds of plasma-treated cells can be differentiated from control cells using the Raman data. PMID:28663896

  1. Thermal analysis of the in-vessel components of the ITER plasma-position reflectometry

    Science.gov (United States)

    Quental, P. B.; Policarpo, H.; Luís, R.; Varela, P.

    2016-11-01

    The ITER plasma position reflectometry system measures the edge electron density profile of the plasma, providing real-time supplementary contribution to the magnetic measurements of the plasma-wall distance. Some of the system components will be in direct sight of the plasma and therefore subject to plasma and stray radiation, which may cause excessive temperatures and stresses. In this work, thermal finite element analysis of the antenna and adjacent waveguides is conducted with ANSYS V17 (ANSYS® Academic Research, Release 17.0, 2016). Results allow the identification of critical temperature points, and solutions are proposed to improve the thermal behavior of the system.

  2. Non-thermal atmospheric pressure plasma activates lactate in Ringer's solution for anti-tumor effects.

    Science.gov (United States)

    Tanaka, Hiromasa; Nakamura, Kae; Mizuno, Masaaki; Ishikawa, Kenji; Takeda, Keigo; Kajiyama, Hiroaki; Utsumi, Fumi; Kikkawa, Fumitaka; Hori, Masaru

    2016-11-08

    Non-thermal atmospheric pressure plasma is a novel approach for wound healing, blood coagulation, and cancer therapy. A recent discovery in the field of plasma medicine is that non-thermal atmospheric pressure plasma not only directly but also indirectly affects cells via plasma-treated liquids. This discovery has led to the use of non-thermal atmospheric pressure plasma as a novel chemotherapy. We refer to these plasma-treated liquids as plasma-activated liquids. We chose Ringer's solutions to produce plasma-activated liquids for clinical applications. In vitro and in vivo experiments demonstrated that plasma-activated Ringer's lactate solution has anti-tumor effects, but of the four components in Ringer's lactate solution, only lactate exhibited anti-tumor effects through activation by non-thermal plasma. Nuclear magnetic resonance analyses indicate that plasma irradiation generates acetyl and pyruvic acid-like groups in Ringer's lactate solution. Overall, these results suggest that plasma-activated Ringer's lactate solution is promising for chemotherapy.

  3. Geometric thermal phase diagrams for studying the thermal dynamic stability of hollow gold nanoballs at different temperatures.

    Science.gov (United States)

    Jiang, Luyun; Sun, Wei; Gao, Yajun; Zhao, Jianwei

    2014-04-14

    Thermal stability is one of the main concerns for the synthesis of hollow nanoparticles. In this work, molecular dynamics simulation gave an insight into the atomic reconstruction and energy evolution during the collapse of hollow gold nanoballs, based on which a mechanism was proposed. The stability was found to depend on temperature, its wall thickness and aspect ratio to a great extent. The relationship among these three factors was revealed in geometric thermal phase diagrams (GTPDs). The GTPDs were studied theoretically, and the boundary between different stability regions can be fitted and calculated. Therefore, the GTPDs at different temperatures can be deduced and used as a guide for hollow structure synthesis.

  4. Novel fragmentation model for pulverized coal particles gasification in low temperature air thermal plasma

    OpenAIRE

    Jovanović Rastko D.; Cvetinović Dejan B.; Stefanović Predrag Lj.; Škobalj Predrag D.; Marković Zoran J.

    2016-01-01

    New system for start-up and flame support based on coal gasification by low temperature air thermal plasma is planned to supplement current heavy oil system in Serbian thermal power plants in order to decrease air pollutions emission and operational costs. Locally introduced plasma thermal energy heats up and ignites entrained coal particles, thus starting chain process which releases heat energy from gasified coal particles inside burner channel. Important...

  5. Transport properties of multicomponent thermal plasmas: Grad method versus Chapman-Enskog method

    Energy Technology Data Exchange (ETDEWEB)

    Porytsky, P. [Institute for Nuclear Research, 03680 Kyiv (Ukraine); Krivtsun, I.; Demchenko, V. [Paton Welding Institute, 03680 Kyiv (Ukraine); Reisgen, U.; Mokrov, O.; Zabirov, A. [RWTH Aachen University, ISF-Welding and Joining Institute, 52062 Aachen (Germany); Gorchakov, S.; Timofeev, A.; Uhrlandt, D. [Leibniz Institute for Plasma Science and Technology (INP Greifswald), 17489 Greifswald (Germany)

    2013-02-15

    Transport properties (thermal conductivity, viscosity, and electrical conductivity) for multicomponent Ar-Fe thermal plasmas at atmospheric pressure have been determined by means of two different methods. The transport coefficients set based on Grad's method is compared with the data obtained when using the Chapman-Enskog's method. Results from both applied methods are in good agreement. It is shown that the Grad method is suitable for the determination of transport properties of the thermal plasmas.

  6. Modulating toroidal flow stabilization of edge localized modes with plasma density

    CERN Document Server

    Cheng, Shikui; Banerjee, Debabrata

    2016-01-01

    Recent EAST experiments have demonstrated mitigation and suppression of edge localized modes (ELMs) with toroidal rotation flow in higher collisionality regime, suggesting potential roles of plasma density. In this work, the effects of plasma density on the toroidal flow stabilization of the high-$n$ edge localized modes have been extensively studied in linear calculations for a circular-shaped limiter H-mode tokamak, using the extended MHD code NIMROD. In the single MHD model, toroidal flow has a weak stabilizing effects on the high-$n$ modes. Such a stabilization, however, can be significantly enhanced with the increase in plasma density. Furthermore, our calculations show that the enhanced stabilization of high-$n$ modes from toroidal flow with higher edge plasma density persists in the 2-fluid MHD model. These findings may explain the ELM mitigation and suppression by toroidal rotation in higher collisionality regime due to the enhancement of plasma density obtained in recent EAST experiments.

  7. Performance of Cobalt-Based Fischer-Tropsch Synthesis Catalysts Using Dielectric-Barrier Discharge Plasma as an Alternative to Thermal Calcination

    Science.gov (United States)

    Bai, Suli; Huang, Chengdu; Lv, Jing; Li, Zhenhua

    2012-01-01

    Co-based catalysts were prepared by using dielectric-barrier discharge (DBD) plasma as an alternative method to conventional thermal calcination. The characterization results of N2-physisorption, temperature programmed reduction (TPR), transmission electron microscope (TEM), and X-ray diffraction (XRD) indicated that the catalysts prepared by DBD plasma had a higher specific surface area, lower reduction temperature, smaller particle size and higher cobalt dispersion as compared to calcined catalysts. The DBD plasma method can prevent the sintering and aggregation of active particles on the support due to the decreased treatment time (0.5 h) at lower temperature compared to the longer thermal calcination at higher temperature (at 500° C for 5 h). As a result, the catalytic performance of the Fischer-Tropsch synthesis on DBD plasma treated Co/SiO2 catalyst showed an enhanced activity, C5+ selectivity and catalytic stability as compared to the conventional thermal calcined Co/SiO2 catalyst.

  8. Polarization of the Sunyaev-Zel'dovich effect: relativistic imprint of thermal and non-thermal plasma

    CERN Document Server

    Emritte, M S; Marchegiani, P

    2016-01-01

    [Abridged] Inverse Compton scattering of CMB fluctuations off cosmic electron plasma generates a polarization of the associated Sunyaev-Zel'dovich (SZ) effect. This signal has been studied so far mostly in the non-relativistic regime and for a thermal electron population and, as such, has limited astrophysical applications. Partial attempts to extend this calculation for a thermal electron plasma in the relativistic regime have been done but cannot be applied to a general relativistic electron distribution. Here we derive a general form of the SZ effect polarization valid in the full relativistic approach for both thermal and non-thermal electron plasmas, as well as for a generic combination of various electron population co-spatially distributed in the environments of galaxy clusters or radiogalaxy lobes. We derive the spectral shape of the Stokes parameters induced by the IC scattering of every CMB multipole, focusing on the CMB quadrupole and octupole that provide the largest detectable signals in galaxy c...

  9. Thermal plasma treatment of cell-phone waste : preliminary result

    Energy Technology Data Exchange (ETDEWEB)

    Ruj, B. [Central Mechanical Engineering Research Inst., Durgapur (India). Thermal Engineering Group; Chang, J.S.; Li, O.L. [McMaster Univ., Hamilton, ON (Canada). Dept. of Engineering Physics; Pietsch, G. [RWTH Aachen Univ., Aachen (Germany)

    2010-07-01

    The cell phone is an indispensable service facilitator, however, the disposal and recycling of cell phones is a major problem. While the potential life span of a mobile phone, excluding batteries, is over 10 years, most of the users upgrade their phones approximately four times during this period. Cell phone waste is significantly more hazardous than many other municipal wastes as it contains thousands of components made of toxic chemicals and metals like lead, cadmium, chromium, mercury, polyvinyl chlorides (PVC), brominated flame retardants, beryllium, antimony and phthalates. Cell phones also use many expensive rare metals. Since cell phones are made up of plastics, metals, ceramics, and trace other substances, primitive recycling or disposal of cell phone waste to landfills and incinerators creates irreversible environmental damage by polluting water and soil, and contaminating air. In order to minimize releases into the environment and threat to human health, the disposal of cell phones needs to be managed in an environmentally friendly way. This paper discussed a safer method of reducing the generation of syngas and hydrocarbons and metal recovery through the treatment of cell phone wastes by a thermal plasma. The presentation discussed the experiment, with particular reference to sample preparation; experimental set-up; and results four samples with different experimental conditions. It was concluded that the plasma treatment of cell phone waste in reduced condition generates gaseous components such as hydrogen, carbon monoxide, and hydrocarbons which are combustible. Therefore, this system is an energy recovery system that contributes to resource conservation and reduction of climate change gases. 5 refs., 2 tabs., 2 figs.

  10. Tungsten-zirconium carbide-rhenium alloys with extraordinary thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.D. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Xie, Z.M.; Miao, S. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Liu, R.; Jiang, W.B. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zhang, T., E-mail: zhangtao@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Wang, X.P., E-mail: xpwang@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Fang, Q.F. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Liu, C.S., E-mail: csliu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Luo, G.N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Liu, X. [Southwest Institute of Plasma Physics, Chengdu (China)

    2016-05-15

    The low recrystallization temperature (1200 °C) of pure W is a serious limitation for application as facing plasma materials in fusion reactor. In this paper, W-0.5wt.%ZrC-1wt.%Re (WZR) alloy with recrystallization temperature up to 1800 °C was prepared by mechanical milling and spark plasma sintering. The grain size of WZR alloy is about 2.6 μm, smaller than that of pure W (4.4 μm), which keeps unchanged until the annealing temperature increases to 1800 °C. Tensile tests indicate that the WZR alloys exhibit excellent comprehensive properties: the ductile to brittle transition temperature of WZR is in the range from 400 °C to 500 °C, about 200 °C lower than that of pure W prepared by the same process; the total elongation (TE) of WZR at 600 °C is above 30%, which is about 2 times that of pure W (at 700 °C). Meanwhile its tensile strength keeps ∼450 MPa before and after 1800 °C annealing as well as its TE increases after annealing. WZR alloy exhibits higher hardness (489HV) than that of pure W (453HV) at room temperature. Microstructure analysis indicates that the strengthening of nano-sized ZrC particles dispersion and Re solid solution improve tensile properties and thermal stability of WZR alloy.

  11. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi

    2014-11-11

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  12. Energy recovery from waste glycerol by utilizing thermal water vapor plasma.

    Science.gov (United States)

    Tamošiūnas, Andrius; Valatkevičius, Pranas; Gimžauskaitė, Dovilė; Jeguirim, Mejdi; Mėčius, Vladas; Aikas, Mindaugas

    2017-04-01

    Glycerol, considered as a waste feedstock resulting from biodiesel production, has received much attention in recent years due to its properties, which offer to recover energy. The aim of this study was to investigate the use of a thermal water vapor plasma for waste (crude) glycerol conversion to synthesis gas, or syngas (H2 + CO). In parallel of crude glycerol, a pure glycerol (99.5%) was used as a reference material in order to compare the concentrations of the formed product gas. A direct current (DC) arc plasma torch stabilized by a mixture of argon/water vapor was utilized for the effective glycerol conversion to hydrogen-rich synthesis gas. It was found that after waste glycerol treatment, the main reaction products were gases with corresponding concentrations of H2 50.7%, CO 23.53%, CO2 11.45%, and CH4 3.82%, and traces of C2H2 and C2H6, which concentrations were below 0.5%. The comparable concentrations of the formed gas products were obtained after pure glycerol conversion-H2 46.4%, CO 26.25%, CO2 11.3%, and CH4 4.7%. The use of thermal water vapor plasma producing synthesis gas is an effective method to recover energy from both crude and pure glycerol. The performance of the glycerol conversion system was defined in terms of the produced gas yield, the carbon conversion efficiency, the cold gas efficiency, and the specific energy requirements.

  13. Electrothermal efficiency, temperature and thermal conductivity of plasma jet in a DC plasma spray torch

    Indian Academy of Sciences (India)

    G Shanmugavelayutham; V Selvarajan

    2003-12-01

    A study was made to evaluate the electrothermal efficiency of a DC arc plasma torch and temperature and thermal conductivity of plasma jet in the torch. The torch was operated at power levels from 4 to 20 kW in non-transferred arc mode. The effect of nitrogen in combination with argon as plasma gas on the above properties was investigated. Calculations were made from experimental data. The electrothermal efficiency increased significantly with increase in nitrogen content. The plasma jet temperature and thermal conductivity exhibited a decrease with increase in nitrogen content. The experiment was done at different total gas flow rates. The results are explained on the basis of dissociation energy of nitrogen molecules and plasma jet energy loss to the cathode, anode and the walls of the torch.

  14. Collisional Thermalization of Hydrogen and Helium in Solar Wind Plasma

    CERN Document Server

    Maruca, Bennett A; Sorriso-Valvo, Luca; Kasper, Justin C; Stevens, Michael L

    2013-01-01

    In situ observations of the solar wind frequently show the temperature of $\\alpha$-particles (fully ionized helium), $T_\\alpha$, to significantly differ from that of protons (ionized hydrogen), $T_p$. Many heating processes in the plasma act preferentially on $\\alpha$-particles, even as collisions among ions act to gradually establish thermal equilibrium. Measurements from the $\\textit{Wind}$ spacecraft's Faraday cups reveal that, at $r=1.0\\ \\textrm{AU}$ from the Sun, the observed values of the $\\alpha$-proton temperature ratio, $\\theta_{\\alpha p} \\equiv T_\\alpha\\,/\\,T_p$ has a complex, bimodal distribution. This study applied a simple model for the radial evolution of $\\theta_{\\alpha p}$ to these data to compute expected values of $\\theta_{\\alpha p}$ at $r=0.1\\ \\textrm{AU}$. These inferred $\\theta_{\\alpha p}$-values have no trace of the bimodality seen in the $\\theta_{\\alpha p}$-values measured at $r=1.0\\ \\textrm{AU}$ but are instead consistent with the actions of the known mechanisms for $\\alpha$-particle p...

  15. Synthesis of antimony tris(mercaptoethyl carboxylates) as thermal stabilizer for polyvinyl chloride

    Institute of Scientific and Technical Information of China (English)

    舒万艮; 刘又年; 陈启元

    2002-01-01

    A novel type of thermal stabilizers-antimony tris(mercaptoethyl carboxylates) (Sb(SCH2CH2OOCR) 3), was synthesized from carboxylic acid, antimony trioxide and 2-mercaptoethanol in two steps. The experimental results show that the molar ratio of carboxylic acid to antimony tris(2-hydroxyethyl mercaptide) is 1.2, when adding 0.6% tetra-n-butyl titanate as catalyst and xylene as isotropic solvent, heating and refluxing for about 2~4h. The thermal stability was measured by heat-aging oven test. The thermal stability time is about 8~40min(at 200℃) when adding 2% tetra-n-butyl titanate in polyvinyl chloride(PVC). Among these stabilizers, antimony tris(mercaptoethyl stearate) has best thermal stability. Its thermal stability is better than that of Ca-Zn complex and basic lead stabilizers, and equal to that of organotin. In addition, the stabilization mechanism of this kind of stabilizers for PVC was discussed briefly.

  16. Rare Earth Stearates as Thermal Stabilizers for Rigid Poly(vinyl chloride)

    Institute of Scientific and Technical Information of China (English)

    Zheng Yuying; Cai Weilong; Fu Minglian; Wang Canyao; Zhang Xing

    2005-01-01

    A series of stearates with different rare-earth ion were investigated as thermal stabilizers for rigid PVC at 180 ℃ in air. Their stabilizing efficiency was based on measuring the rate of dehydrochlorination. The resulted revealed the higher stabilizing efficiency of the investigated rare-earth stearates as thermal stabilizers for rigid PVC compared with the thermal stabilizers for industry: calcium stearate, zinc stearate, butyl stannum mercaptide, phosphite esters, β-diketone and epoxidized sunflower oil. This was well illustrated by longer incubation period (TS) values and lower rate of dehydrochlorination. The stable efficiency was affected by the nature of rare-earth element's individual electronic shell. The mechanism for the stabilizing effect of rare-earth stearates was proposed. The result was experimentally proved based on IR spectrum.

  17. Thermal stability and thermodynamic properties of hybrid proton-conducting polyaryl etherketones.

    Science.gov (United States)

    Marani, D; Di Vona, M L; Traversa, E; Licoccia, S; Beurroies, I; Llewellyn, P L; Knauth, P

    2006-08-17

    The thermal and structural stability of sulfonated cross-linked PEEK (polyether ether ketone) and its silicon-containing class II hybrid derivatives were characterized by combination of mass spectrometry, infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. Thermodynamic properties of the hybrids were determined, including glass-transition temperature, degree of crystallinity, and thermal stability. The decomposition processes of the hybrid polymers could be consistently interpreted and their energetics quantitatively determined. The introduction of inorganic silanol moieties improves the thermal stability compared to sulfonated products.

  18. Mitochondria-Mediated Anticancer Effects of Non-Thermal Atmospheric Plasma.

    Directory of Open Access Journals (Sweden)

    Aigul Zhunussova

    Full Text Available Non-thermal atmospheric pressure plasma has attracted great interest due to its multiple potential biomedical applications with cancer treatment being among the most urgent. To realize the clinical potential of non-thermal plasma, the exact cellular and molecular mechanisms of plasma effects must be understood. This work aimed at studying the prostate cancer specific mechanisms of non-thermal plasma effects on energy metabolism as a central regulator of cell homeostasis and proliferation. It was found that cancer cells with higher metabolic rate initially are more resistant to plasma treated phosphate-buffered saline (PBS since the respiratory and calcium sensitive signaling systems were not responsive to plasma exposure. However, dramatic decline of cancer oxidative phosphorylation developed over time resulted in significant progression of cell lethality. The normal prostate cells with low metabolic activity immediately responded to plasma treated PBS by suppression of respiratory functions and sustained elevation of cytosolic calcium. However, over time the normal cells start recovering their mitochondria functions, proliferate and restore the cell population. We found that the non-thermal plasma induced increase in intracellular ROS is of primarily non-mitochondrial origin. The discriminate non-thermal plasma effects hold a promise for clinical cancer intervention.

  19. Mitochondria-Mediated Anticancer Effects of Non-Thermal Atmospheric Plasma

    Science.gov (United States)

    Zhunussova, Aigul; Vitol, Elina A.; Polyak, Boris; Tuleukhanov, Sultan; Brooks, Ari D.; Sensenig, Richard; Friedman, Gary; Orynbayeva, Zulfiya

    2016-01-01

    Non-thermal atmospheric pressure plasma has attracted great interest due to its multiple potential biomedical applications with cancer treatment being among the most urgent. To realize the clinical potential of non-thermal plasma, the exact cellular and molecular mechanisms of plasma effects must be understood. This work aimed at studying the prostate cancer specific mechanisms of non-thermal plasma effects on energy metabolism as a central regulator of cell homeostasis and proliferation. It was found that cancer cells with higher metabolic rate initially are more resistant to plasma treated phosphate-buffered saline (PBS) since the respiratory and calcium sensitive signaling systems were not responsive to plasma exposure. However, dramatic decline of cancer oxidative phosphorylation developed over time resulted in significant progression of cell lethality. The normal prostate cells with low metabolic activity immediately responded to plasma treated PBS by suppression of respiratory functions and sustained elevation of cytosolic calcium. However, over time the normal cells start recovering their mitochondria functions, proliferate and restore the cell population. We found that the non-thermal plasma induced increase in intracellular ROS is of primarily non-mitochondrial origin. The discriminate non-thermal plasma effects hold a promise for clinical cancer intervention. PMID:27270230

  20. Erosion Performance of Gadolinium Zirconate-Based Thermal Barrier Coatings Processed by Suspension Plasma Spray

    Science.gov (United States)

    Mahade, Satyapal; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per; Vaßen, Robert

    2017-01-01

    7-8 wt.% Yttria-stabilized zirconia (YSZ) is the standard thermal barrier coating (TBC) material used by the gas turbines industry due to its excellent thermal and thermo-mechanical properties up to 1200 °C. The need for improvement in gas turbine efficiency has led to an increase in the turbine inlet gas temperature. However, above 1200 °C, YSZ has issues such as poor sintering resistance, poor phase stability and susceptibility to calcium magnesium alumino silicates (CMAS) degradation. Gadolinium zirconate (GZ) is considered as one of the promising top coat candidates for TBC applications at high temperatures (>1200 °C) due to its low thermal conductivity, good sintering resistance and CMAS attack resistance. Single-layer 8YSZ, double-layer GZ/YSZ and triple-layer GZdense/GZ/YSZ TBCs were deposited by suspension plasma spray (SPS) process. Microstructural analysis was carried out by scanning electron microscopy (SEM). A columnar microstructure was observed in the single-, double- and triple-layer TBCs. Phase analysis of the as-sprayed TBCs was carried out using XRD (x-ray diffraction) where a tetragonal prime phase of zirconia in the single-layer YSZ TBC and a cubic defect fluorite phase of GZ in the double and triple-layer TBCs was observed. Porosity measurements of the as-sprayed TBCs were made by water intrusion method and image analysis method. The as-sprayed GZ-based multi-layered TBCs were subjected to erosion test at room temperature, and their erosion resistance was compared with single-layer 8YSZ. It was shown that the erosion resistance of 8YSZ single-layer TBC was higher than GZ-based multi-layered TBCs. Among the multi-layered TBCs, triple-layer TBC was slightly better than double layer in terms of erosion resistance. The eroded TBCs were cold-mounted and analyzed by SEM.

  1. Kinetic turbulence in relativistic plasma: from thermal bath to non-thermal continuum

    CERN Document Server

    Zhdankin, Vladimir; Uzdensky, Dmitri A; Begelman, Mitchell C

    2016-01-01

    We present results from particle-in-cell simulations of driven turbulence in collisionless, relativistic pair plasma. We find that turbulent fluctuations are consistent with the classical $k_\\perp^{-5/3}$ magnetic energy spectrum at fluid scales and a steeper $k_\\perp^{-4}$ spectrum at sub-Larmor scales, where $k_\\perp$ is the wavevector perpendicular to the mean field. We demonstrate the development of a non-thermal, power-law particle energy distribution, $f(E) \\sim E^{-\\alpha}$, with index well fit by $\\alpha \\sim 1 + C_0 (\\sigma \\rho_e/L)^{-1/2}$, where $C_0$ is a constant, $\\sigma$ is magnetization, and $\\rho_e/L$ is the ratio of characteristic Larmor radius to system size. In the absence of asymptotic system-size independent scalings, our results challenge the viability of turbulent particle acceleration in high-energy astrophysical systems such as pulsar wind nebulae.

  2. Study on Thermal Stability and Spectroscopic Properties of Nd3+ -Doped Phosphate Laser Glasses

    Institute of Scientific and Technical Information of China (English)

    Shi Qi; Lv Jingwen; Cheng Hong; Fu Xingguo; Sun Yu

    2004-01-01

    Fluorescence spectra, absorption spectra and thermal stability properties of Nd3 + -doped phosphate laser glasses were tested in this work. We calculated spectroscopic parameters of Nd3 + -doped phosphate laser glasses according to their absorption spectrum. Measuring and calculating linear thermal expansion coefficient, and analysising thermal stability of glasses show that this kind of Nd3 + -doped phosphate laser glasses has thermal expansion coefficient α = 38.75× 10 -7/℃ and optimal spectroscopic properties which extend application range of Nd +3-doped phosphate laser glasses.

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

    Science.gov (United States)

    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.

  4. Effects of actin-binding proteins on the thermal stability of monomeric actin.

    Science.gov (United States)

    Pivovarova, Anastasia V; Chebotareva, Natalia A; Kremneva, Elena V; Lappalainen, Pekka; Levitsky, Dmitrii I

    2013-01-08

    Differential scanning calorimetry (DSC) was applied to investigate the thermal unfolding of rabbit skeletal muscle G-actin in its complexes with actin-binding proteins, cofilin, twinfilin, and profilin. The results show that the effects of these proteins on the thermal stability of G-actin depend on the nucleotide, ATP or ADP, bound in the nucleotide-binding cleft between actin subdomains 2 and 4. Interestingly, cofilin binding stabilizes both ATP-G-actin and ADP-G-actin, whereas twinfilin increases the thermal stability of the ADP-G-actin but not that of the ATP-G-actin. By contrast, profilin strongly decreases the thermal stability of the ATP-G-actin but has no appreciable effect on the ADP-G-actin. Comparison of these DSC results with literature data reveals a relationship between the effects of actin-binding proteins on the thermal unfolding of G-actin, stabilization or destabilization, and their effects on the rate of nucleotide exchange in the nucleotide-binding cleft, decrease or increase. These results suggest that the thermal stability of G-actin depends, at least partially, on the conformation of the nucleotide-binding cleft: the actin molecule is more stable when the cleft is closed, while an opening of the cleft leads to significant destabilization of G-actin. Thus, DSC studies of the thermal unfolding of G-actin can provide new valuable information about the conformational changes induced by actin-binding proteins in the actin molecule.

  5. CREATION OF GRADIENT PLASMA-SPRAYED COATINGS ON BASIS OF ZIRCONIUM DIOXIDE STABILIZED WITH YTTERBIUM DIOXIDE

    Directory of Open Access Journals (Sweden)

    V. A. Okovity

    2011-01-01

    Full Text Available The process has been investigated and technological parameters for spraying gradient plasma coatings on the basis of zirconium dioxide stabilized with ytterbium dioxide have been optimized in the paper.

  6. Enhanced toroidal flow stabilization of edge localized modes with increased plasma density

    Science.gov (United States)

    Cheng, Shikui; Zhu, Ping; Banerjee, Debabrata

    2017-09-01

    Toroidal flow alone is generally thought to have an important influence on tokamak edge pedestal stability, even though theoretical analysis often predicts merely a weak stabilizing effect of toroidal flow on the edge localized modes (ELMs) in experimental parameter regimes. For the first time, we find from two-fluid MHD calculations that such a stabilization, however, can be significantly enhanced by increasing the edge plasma density. Our finding resolves a long-standing mystery whether or how toroidal rotation can indeed have an effective influence on ELMs, and explains why the ELM mitigation and suppression by toroidal rotation are more favorably achieved in higher collisionality regime in recent experiments. The finding suggests a new control scheme on modulating toroidal flow stabilization of ELMs with plasma density, along with a new additional constraint on the optimal level of plasma density for the desired edge plasma conditions.

  7. Core-shell structured titanium-nitrogen alloys with high strength, high thermal stability and good plasticity.

    Science.gov (United States)

    Zhang, Y S; Zhao, Y H; Zhang, W; Lu, J W; Hu, J J; Huo, W T; Zhang, P X

    2017-01-06

    Multifunctional materials with more than two good properties are widely required in modern industries. However, some properties are often trade-off with each other by single microstructural designation. For example, nanostructured materials have high strength, but low ductility and thermal stability. Here by means of spark plasma sintering (SPS) of nitrided Ti particles, we synthesized bulk core-shell structured Ti alloys with isolated soft coarse-grained Ti cores and hard Ti-N solid solution shells. The core-shell Ti alloys exhibit a high yield strength (~1.4 GPa) comparable to that of nanostructured states and high thermal stability (over 1100 °C, 0.71 of melting temperature), contributed by the hard Ti-N shells, as well as a good plasticity (fracture plasticity of 12%) due to the soft Ti cores. Our results demonstrate that this core-shell structure offers a design pathway towards an advanced material with enhancing strength-plasticity-thermal stability synergy.

  8. Core-shell structured titanium-nitrogen alloys with high strength, high thermal stability and good plasticity

    Science.gov (United States)

    Zhang, Y. S.; Zhao, Y. H.; Zhang, W.; Lu, J. W.; Hu, J. J.; Huo, W. T.; Zhang, P. X.

    2017-01-01

    Multifunctional materials with more than two good properties are widely required in modern industries. However, some properties are often trade-off with each other by single microstructural designation. For example, nanostructured materials have high strength, but low ductility and thermal stability. Here by means of spark plasma sintering (SPS) of nitrided Ti particles, we synthesized bulk core-shell structured Ti alloys with isolated soft coarse-grained Ti cores and hard Ti-N solid solution shells. The core-shell Ti alloys exhibit a high yield strength (~1.4 GPa) comparable to that of nanostructured states and high thermal stability (over 1100 °C, 0.71 of melting temperature), contributed by the hard Ti-N shells, as well as a good plasticity (fracture plasticity of 12%) due to the soft Ti cores. Our results demonstrate that this core-shell structure offers a design pathway towards an advanced material with enhancing strength-plasticity-thermal stability synergy.

  9. Equatorial Plasma Bubble Detection and Scintillation Specification by the Thermal Plasma Sensor (TPS) on NPOESS

    Science.gov (United States)

    Basu, S.; Groves, K.; Starks, M.; Rich, F.

    2005-12-01

    The thermal plasma sensor (TPS) on the National Polar-orbiting Operational Environmental Satellites System (NPOESS) will perform in-situ measurements of the total ion concentration, the ion concentration fluctuations and the ion temperature. The ion concentration measurements will have a range from less than 10e3 per c.c. to greater than 10e6 per c.c. The DMSP data is used to show that this range of total ion concentration measurements will be adequate to detect the smallest as well as the deepest equatorial plasma bubbles. The detection of deep plasma bubbles will indicate the disturbed state of the equatorial electrodynamics in the presence of much enhanced zonal electric fields. Furthermore, the bubbles generally indicate the presence of steep gradients in the total electron content of the ionosphere that may disable the GPS-based aircraft navigation systems currently undergoing development at equatorial latitudes. The TPS sensor will have the ability to measure the fluctuations in the electron concentration, DN/N, less than 0.1 per cent over distances of 25 km to as large as 50 per cent. These two bounds of DN/N in the equatorial region during the post-sunset hours correspond to weak VHF scintillations and saturated GHz scintillations respectively. It is well-known that with the 32 Hz sampling of the TPS data, the Fourier spectra of the ion concentration fluctuation data extends only to a Nyquist scale-length of 500 m. By using the high frequency comb filter outputs of the TPS sensor, the spectrum can, however, be extended to tens of meter scales, a decade smaller than the Fresnel dimension of GHz scintillation. It is shown that in the framework of radio wave diffraction theory, such data, in combination with the electron density profile measurements made by NPOESS can be used to specify scintillations in the range of VHF to GHz.

  10. Hemorheological alterations of red blood cells induced by non-thermal dielectric barrier discharge plasma

    Science.gov (United States)

    Kim, Jeongho; Kim, Jae Hyung; Chang, Boksoon; Choi, Eun Ha; Park, Hun-Kuk

    2016-11-01

    Atmospheric pressure non-thermal plasma has been introduced in various applications such as wound healing, sterilization of infected tissues, blood coagulation, delicate surgeries, and so on. The non-thermal plasma generates reactive oxygen species (ROS), including ozone. Various groups have reported that the produced ROS influence proliferation and differentiation of cells, as well as apoptosis and growth arrest of tumor cells. In this study, we investigated the effects of non-thermal plasma on rheological characteristics of red blood cells (RBC). We experimentally measured the extent of hemolysis, deformability, and aggregation of red blood cells (RBC) with respect to exposure times of non-thermal plasma. RBC morphology was also examined using field-emission scanning electron microscopy. The absorbance of hemoglobin released from the RBCs increased with increasing exposure time of the non-thermal plasma. Values of the elongation index and aggregation index were shown to decrease significantly with increasing plasma exposure times. Therefore, hemorheological properties of RBCs could be utilized to assess the performance of various non-thermal plasmas.

  11. 3-D MHD modeling and stability analysis of jet and spheromak plasmas launched into a magnetized plasma

    Science.gov (United States)

    Fisher, Dustin; Zhang, Yue; Wallace, Ben; Gilmore, Mark; Manchester, Ward; Arge, C. Nick

    2016-10-01

    The Plasma Bubble Expansion Experiment (PBEX) at the University of New Mexico uses a coaxial plasma gun to launch jet and spheromak magnetic plasma configurations into the Helicon-Cathode (HelCat) plasma device. Plasma structures launched from the gun drag frozen-in magnetic flux into the background magnetic field of the chamber providing a rich set of dynamics to study magnetic turbulence, force-free magnetic spheromaks, and shocks. Preliminary modeling is presented using the highly-developed 3-D, MHD, BATS-R-US code developed at the University of Michigan. BATS-R-US employs an adaptive mesh refinement grid that enables the capture and resolution of shock structures and current sheets, and is particularly suited to model the parameter regime under investigation. CCD images and magnetic field data from the experiment suggest the stabilization of an m =1 kink mode trailing a plasma jet launched into a background magnetic field. Results from a linear stability code investigating the effect of shear-flow as a cause of this stabilization from magnetic tension forces on the jet will be presented. Initial analyses of a possible magnetic Rayleigh Taylor instability seen at the interface between launched spheromaks and their entraining background magnetic field will also be presented. Work supported by the Army Research Office Award No. W911NF1510480.

  12. Studies of the influence of nonequilibrium plasma thermal exposure on the characteristics of the capillary-porous polymer material

    Science.gov (United States)

    Makhotkina, L. Yu; Khristoliubova, V. I.

    2017-01-01

    Capillary-porous materials, which include natural macromolecular tanning material, are exposed to a number of factors during the treatment by a nonequilibrium plasma. Plasma particles exchange the charge and energy with the atoms of the material during the interaction of the plasma with the surface. The results of treatment are desorption of atoms and molecules from the body surface, sputtering and evaporation of material’s particles, changes of the structure and phase state. In real terms during the modification of solids by nonequilibrium low-temperature plasma thermal effect influences the process. The energy supplied from the discharge during the process with low pressure, which is converted into heat, is significantly less than during the atmospheric pressure, but the thermal stability of high-molecular compounds used in the manufacture of materials and products of the tanning industry, is very limited and depends on the duration of the effect of temperature. Even short heating of hydrophilic polymers (proteins) (100-180 °C) causes a change in their properties. It decreases the collagen ability to absorb water vapor, to swell in water, acids, alkalis, and thus decreases their durability. Prolonged heating leads to a deterioration of the physical and mechanical properties. Higher heating temperatures it leads to the polymer degradation. The natural leather temperature during plasma exposure does not rise to a temperature of collagen degradation and does not result in changes of physical phase of the dermis. However, the thermal plasma exposure must be considered, since the high temperatures influence on physical and mechanical properties.

  13. Thermal Stability Comparison of Nanocrystalline Fe-Based Binary Alloy Pairs

    Science.gov (United States)

    Clark, B. G.; Hattar, K.; Marshall, M. T.; Chookajorn, T.; Boyce, B. L.; Schuh, C. A.

    2016-06-01

    The widely recognized property improvements of nanocrystalline (NC) materials have generated significant interest; yet, they have been difficult to realize in engineering applications due to the propensity for grain growth in these interface-dominated systems. Although traditional pathways to thermal stabilization can slow the mobility of grain boundaries, recent theories suggest that solute segregation in NC alloys can reduce the grain boundary energy such that thermodynamic stabilization is achieved. Following the predictions of Murdoch et al., here we compare for the first time the thermal stability of a predicted NC stable alloy (Fe-10 at.% Mg) with a predicted non-NC stable alloy (Fe-10 at.% Cu) using the same processing and characterization methodologies. Results show improved thermal stability of the Fe-Mg alloy in comparison with the Fe-Cu, and thermally-evolved microstructures that are consistent with those predicted by Monte Carlo simulations.

  14. Improving the Stability and Performance of Perovskite Light-Emitting Diodes by Thermal Annealing Treatment.

    Science.gov (United States)

    Yu, Jae Choul; Kim, Dae Woo; Kim, Da Bin; Jung, Eui Dae; Park, Jong Hyun; Lee, Ah-Young; Lee, Bo Ram; Di Nuzzo, Daniele; Friend, Richard H; Song, Myoung Hoon

    2016-08-01

    A perovskite LED with a perovskite film treated under optimum thermal annealing conditions exhibits a significantly enhanced long-term stability with full coverage of the green electroluminescence emission due to the highly uniform morphology of the perovskite film.

  15. Non-modal stability analysis and transient growth in a magnetized Vlasov plasma

    CERN Document Server

    Ratushnaya, Valeria

    2014-01-01

    Collisionless plasmas, such as those encountered in tokamaks, exhibit a rich variety of instabilities. The physical origin, triggering mechanisms and fundamental understanding of many plasma instabilities, however, are still open problems. We investigate the stability properties of a collisionless Vlasov plasma in a stationary homogeneous magnetic field. We narrow the scope of our investigation to the case of Maxwellian plasma. For the first time using a fully kinetic approach we show the emergence of the local instability, a transient growth, followed by classical Landau damping in a stable magnetized plasma. We show that the linearized Vlasov operator is non-normal leading to the algebraic growth of the perturbations using non-modal stability theory. The typical time scales of the obtained instabilities are of the order of several plasma periods. The first-order distribution function and the corresponding electric field are calculated and the dependence on the magnetic field and perturbation parameters is s...

  16. Stability of glucagon-like peptide-1 and glucagon in human plasma

    DEFF Research Database (Denmark)

    Albrechtsen, Nicolai Jacob Wewer; Bak, Monika Judyta; Hartmann, Bolette;

    2015-01-01

    To investigate the stability of glucagon-like peptide-1(GLP-1) and glucagon in plasma under short- and long-term storage conditions. Methods: Pooled human plasma (n=20), to which a dipeptidyl peptidase 4 (DPP-4) inhibitor and aprotinin were added, was spiked with synthetic GLP-1 (intact, 7-36NH2 ...

  17. Test of Cable Products in Respect of Thermal and Dynamic Stability

    Directory of Open Access Journals (Sweden)

    M. A. Коrotkevich

    2010-01-01

    Full Text Available The paper considers conditions for selection of  power supply of the unit which is used for testing samples of cable products by thermal and dynamic stability currents. It has been shown that while conducting testing by thermal and dynamic stability currents at nominal cable voltage it is more justifiable to use a percussive energy accumulator, and in the case when the voltage is low an inductive energy accumulator is used.

  18. Correlation between iron self-diffusion and thermal stability in doped iron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, Akhil; Gupta, Mukul, E-mail: mgupta@csr.res.in, E-mail: dr.mukul.gupta@gmail.com; Kumar, D.; Reddy, V. R.; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001 (India); Amir, S. M. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ Lichtenbergstrasse 1, 85747 Garching (Germany); Korelis, Panagiotis; Stahn, Jochen [Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2014-12-14

    Nanocrystalline Fe-X-N thin films (with doping X = 0, 3.1 at. % Al, 1.6 at. % Zr), were deposited using reactive ion beam sputtering. Magnetization study reveals that the deposited films exhibit a perpendicular magnetic anisotropy. Thermal stability of the films was investigated systematically and it was observed that the structural and the magnetic stability gets significantly enhanced with Al doping, whereas Zr doping has only a marginal effect. Fe self-diffusion, obtained using polarized neutron reflectivity, shows a suppression with both additives. A correlation between the thermal stability and the diffusion process gives a direct evidence that the enhancement in the thermal stability is primarily diffusion controlled. A combined picture of diffusion, structural, and magnetic stability has been drawn to understand the obtained results.

  19. EDITORIAL: Non-thermal plasma-assisted fuel conversion for green chemistry Non-thermal plasma-assisted fuel conversion for green chemistry

    Science.gov (United States)

    Nozaki, Tomohiro; Gutsol, Alexander

    2011-07-01

    This special issue is based on the symposium on Non-thermal Plasma Assisted Fuel Conversion for Green Chemistry, a part of the 240th ACS National Meeting & Exposition held in Boston, MA, USA, 22-26 August 2010. Historically, the Division of Fuel Chemistry of the American Chemical Society (ACS) has featured three plasma-related symposia since 2000, and has launched special issues in Catalysis Today on three occasions: 'Catalyst Preparation using Plasma Technologies', Fall Meeting, Washington DC, USA, 2000. Special issue in Catalysis Today 72 (3-4) with 12 peer-reviewed articles. 'Plasma Technology and Catalysis', Spring Meeting, New Orleans, LA, USA, 2003. Special issue in Catalysis Today 89 (1-2) with more than 30 peer-reviewed articles. 'Utilization of Greenhouse Gases II' (partly focused on plasma-related technologies), Spring Meeting, Anaheim, CA, USA, 2004. Special issue in Catalysis Today 98 (4) with 25 peer-reviewed articles. This time, selected presentations are published in this Journal of Physics D: Applied Physics special issue. An industrial material and energy conversion technology platform is established on thermochemical processes including various catalytic reactions. Existing industry-scale technology is already well established; nevertheless, further improvement in energy efficiency and material saving has been continuously demanded. Drastic reduction of CO2 emission is also drawing keen attention with increasing recognition of energy and environmental issues. Green chemistry is a rapidly growing research field, and frequently highlights renewable bioenergy, bioprocesses, solar photocatalysis of water splitting, and regeneration of CO2 into useful chemicals. We would also like to emphasize 'plasma catalysis' of hydrocarbon resources as an important part of the innovative next-generation green technologies. The peculiarity of non-thermal plasma is that it can generate reactive species almost independently of reaction temperature. Plasma

  20. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    National Research Council Canada - National Science Library

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W; Jeong, Chang-Mo; Jeon, Young-Chan

    2013-01-01

    .... To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated...

  1. Grey relationship analysis and grey forecasting modeling on thermal stability of synthetic single diamond

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Through analyzing 7 Ib-type samples of synthetic single diamonds by their DTA and TG in air, we ascertained the extrapolated onset temperature on the curves of DTA as the characteristic temperature of their thermal stabilities. Based on the grey system theory, we analyzed 4 factors influential in the thermal stability by the grey relationship analysis, a quantitative method, and derived the grey relationship sequence, that is, the rank of the influence extent of 4 factors on the thermal stability. Furthermore, we established the grey forecasting model, namely GM ( 1,5 ), for predicting the thermal stability of single diamonds with their intrinsic properties, which was then examined by a deviation-probability examination. The results illustrate that it is reasonable to take the Extrapolated Onset Temperature in DTA as the characteristic temperature for thermal stability (TS)of Ib -type synthetic single diamonds. The nitrogen content and grain shape regularity of diamonds are dominating factors. Likewise, grain size and compressive strength are minor factors. In addition, GM (1,5) can be used to predict the thermal stability of Ib-type synthetic single diamonds available. The precision rank of GM( 1,5 ) is‘GOOD’.

  2. Rayleigh-Taylor-Instability Evolution in Colliding-Plasma-Jet Experiments with Magnetic and Viscous Stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Colin Stuart [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States)

    2015-01-15

    The Rayleigh-Taylor instability causes mixing in plasmas throughout the universe, from micron-scale plasmas in inertial confinement fusion implosions to parsec-scale supernova remnants. The evolution of this interchange instability in a plasma is influenced by the presence of viscosity and magnetic fields, both of which have the potential to stabilize short-wavelength modes. Very few experimental observations of Rayleigh-Taylor growth in plasmas with stabilizing mechanisms are reported in the literature, and those that are reported are in sub-millimeter scale plasmas that are difficult to diagnose. Experimental observations in well-characterized plasmas are important for validation of computational models used to make design predictions for inertial confinement fusion efforts. This dissertation presents observations of instability growth during the interaction between a high Mach-number, initially un-magnetized plasma jet and a stagnated, magnetized plasma. A multi-frame fast camera captures Rayleigh-Taylor-instability growth while interferometry, spectroscopy, photodiode, and magnetic probe diagnostics are employed to estimate plasma parameters in the vicinity of the collision. As the instability grows, an evolution to longer mode wavelength is observed. Comparisons of experimental data with idealized magnetohydrodynamic simulations including a physical viscosity model suggest that the observed instability evolution is consistent with both magnetic and viscous stabilization. These data provide the opportunity to benchmark computational models used in astrophysics and fusion research.

  3. Rayleigh-Taylor-instability evolution in colliding-plasma-jet experiments with magnetic and viscous stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Colin Stuart [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Univ. of Washington, Seattle, WA (United States)

    2015-01-15

    The Rayleigh-Taylor instability causes mixing in plasmas throughout the universe, from micron-scale plasmas in inertial confinement fusion implosions to parsec-scale supernova remnants. The evolution of this interchange instability in a plasma is influenced by the presence of viscosity and magnetic fields, both of which have the potential to stabilize short-wavelength modes. Very few experimental observations of Rayleigh-Taylor growth in plasmas with stabilizing mechanisms are reported in the literature, and those that are reported are in sub-millimeter scale plasmas that are difficult to diagnose. Experimental observations in well-characterized plasmas are important for validation of computational models used to make design predictions for inertial confinement fusion efforts. This dissertation presents observations of instability growth during the interaction between a high Mach-number, initially un-magnetized plasma jet and a stagnated, magnetized plasma. A multi-frame fast camera captures Rayleigh-Taylor-instability growth while interferometry, spectroscopy, photodiode, and magnetic probe diagnostics are employed to estimate plasma parameters in the vicinity of the collision. As the instability grows, an evolution to longer mode wavelength is observed. Comparisons of experimental data with idealized magnetohydrodynamic simulations including a physical viscosity model suggest that the observed instability evolution is consistent with both magnetic and viscous stabilization. These data provide the opportunity to benchmark computational models used in astrophysics and fusion research.

  4. Specific cleavage of the DNase-I binding loop dramatically decreases the thermal stability of actin.

    Science.gov (United States)

    Pivovarova, Anastasia V; Khaitlina, Sofia Yu; Levitsky, Dmitrii I

    2010-09-01

    Differential scanning calorimetry was used to investigate the thermal unfolding of actin specifically cleaved within the DNaseI-binding loop between residues Met47-Gly48 or Gly42-Val43 by two bacterial proteases, subtilisin or ECP32/grimelysin (ECP), respectively. The results obtained show that both cleavages strongly decreased the thermal stability of monomeric actin with either ATP or ADP as a bound nucleotide. An even more pronounced difference in the thermal stability between the cleaved and intact actin was observed when both actins were polymerized into filaments. Similar to intact F-actin, both cleaved F-actins were significantly stabilized by phalloidin and aluminum fluoride; however, in all cases, the thermal stability of the cleaved F-actins was much lower than that of intact F-actin, and the stability of ECP-cleaved F-actin was lower than that of subtilisin-cleaved F-actin. These results confirm that the DNaseI-binding loop is involved in the stabilization of the actin structure, both in monomers and in the filament subunits, and suggest that the thermal stability of actin depends, at least partially, on the conformation of the nucleotide-binding cleft. Moreover, an additional destabilization of the unstable cleaved actin upon ATP/ADP replacement provides experimental evidence for the highly dynamic actin structure that cannot be simply open or closed, but rather should be considered as being able to adopt multiple conformations. © 2010 The Authors Journal compilation © 2010 FEBS.

  5. Plasma diagnostic techniques in thermal-barrier tandem-mirror fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Silver, E.H.; Clauser, J.F.; Carter, M.R.; Failor, B.H.; Foote, J.H.; Hornady, R.S.; James, R.A.; Lasnier, C.J.; Perkins, D.E.

    1986-08-29

    We review two classes of plasma diagnostic techniques used in thermal-barrier tandem-mirror fusion experiments. The emphasis of the first class is to study mirror-trapped electrons at the thermal-barrier location. The focus of the second class is to measure the spatial and temporal behavior of the plasma space potential at various axial locations. The design and operation of the instruments in these two categories are discussed and data that are representative of their performance is presented.

  6. Compressive and Rarefactive Waves in Dust Plasma with Non-thermal Ions

    Institute of Scientific and Technical Information of China (English)

    DUAN Wen-Shan; WANG Hong-Yan; John Parkes

    2006-01-01

    The governing equation of the dust fluid with non-thermal ions and variable dust charge on dust particles in hot dust plasmas is obtained. Both the compressive and rarefactive waves in this system are investigated. They can be determined by plasma parameters including the temperatures of dust fluid, ions and electrons, as well as the non-thermal parameter of ions, and the number densities of the dust particles, the ions and the electrons, etc.

  7. Analysis of Thermal Stability of Different Counter on 28nm FPGA

    DEFF Research Database (Denmark)

    Gupta, Daizy; Yadav, Amit; Hussain, Dil muhammed Akbar

    2016-01-01

    In this paper we are presenting the power analysis for thermal awareness of different counters. The technique we are using to do the analysis is based on 28 nm FPGA tech-nique. In this work during implementation on FPGA, we are going to analyze thermal stability of different counters in temperature...

  8. Analysis of Thermal Stability of Different Counter on 28nm FPGA

    DEFF Research Database (Denmark)

    Gupta, Daizy; Yadav, Amit; Hussain, Dil muhammed Akbar

    2016-01-01

    In this paper we are presenting the power analysis for thermal awareness of different counters. The technique we are using to do the analysis is based on 28 nm FPGA tech-nique. In this work during implementation on FPGA, we are going to analyze thermal stability of different counters in temperature...

  9. Stability of plasma metabolites and hormones in parturient dairy cows.

    Science.gov (United States)

    Athanasiou, V N; Phillips, R W

    1978-06-01

    Metabolic changes that accompany the transition from parturition to lactation in dairy cows were studied. To measure these changes, plasma samples were obtained from 20 mature Holstein-Friesian dairy cows 10 days before through 10 days after parturition. They were analyzed for glucose, free fatty acids (FFA), lactic acid, ketone bodies, glucocorticoids, insulin, and growth hormone concentration. Lactic acid and glucocorticoids remained constant during the experiment, except for the day of parturition itself. In the prepartum period, changes were not detected in concentrations of hormones (glucocorticoids, insulin, and growth hormone), whereas, plasma metabolites began changing prior to parturition. Most evident were prepartum increased in FFA, ketones, and glucose. Postpartum plasma glucose concentration rapidly returned to prepartum concentrations. Plasma concentration of FFA and ketone bodies remained elevated for longer periods.

  10. Thermal Plasma Synthesis of Crystalline Gallium Nitride Nanopowder from Gallium Nitrate Hydrate and Melamine

    Directory of Open Access Journals (Sweden)

    Tae-Hee Kim

    2016-02-01

    Full Text Available Gallium nitride (GaN nanopowder used as a blue fluorescent material was synthesized by using a direct current (DC non-transferred arc plasma. Gallium nitrate hydrate (Ga(NO33∙xH2O was used as a raw material and NH3 gas was used as a nitridation source. Additionally, melamine (C3H6N6 powder was injected into the plasma flame to prevent the oxidation of gallium to gallium oxide (Ga2O3. Argon thermal plasma was applied to synthesize GaN nanopowder. The synthesized GaN nanopowder by thermal plasma has low crystallinity and purity. It was improved to relatively high crystallinity and purity by annealing. The crystallinity is enhanced by the thermal treatment and the purity was increased by the elimination of residual C3H6N6. The combined process of thermal plasma and annealing was appropriate for synthesizing crystalline GaN nanopowder. The annealing process after the plasma synthesis of GaN nanopowder eliminated residual contamination and enhanced the crystallinity of GaN nanopowder. As a result, crystalline GaN nanopowder which has an average particle size of 30 nm was synthesized by the combination of thermal plasma treatment and annealing.

  11. Transition Region Emission and the Energy Input to Thermal Plasma in Solar Flares

    Science.gov (United States)

    Holman, Gordon D.; Holman, Gordon D.; Dennis, Brian R.; Haga, Leah; Raymond, John C.; Panasyuk, Alexander

    2005-01-01

    Understanding the energetics of solar flares depends on obtaining reliable determinations of the energy input to flare plasma. X-ray observations of the thermal bremsstrahlung from hot flare plasma provide temperatures and emission measures which, along with estimates of the plasma volume, allow the energy content of this hot plasma to be computed. However, if thermal energy losses are significant or if significant energy goes directly into cooler plasma, this is only a lower limit on the total energy injected into thermal plasma during the flare. We use SOHO UVCS observations of O VI flare emission scattered by coronal O VI ions to deduce the flare emission at transition region temperatures between 100,000 K and 1 MK for the 2002 July 23 and other flares. We find that the radiated energy at these temperatures significantly increases the deduced energy input to the thermal plasma, but by an amount that is less than the uncertainty in the computed energies. Comparisons of computed thermal and nonthermal electron energies deduced from RHESSI, GOES, and UVCS are shown.

  12. Synthesis and exceptional thermal stability of Mg-based bimetallic nanoparticles during hydrogenation

    NARCIS (Netherlands)

    Krishnan, Gopi; Negrea, Raluca F.; Ghica, Corneliu; ten Brink, Gert H.; Kooi, Bart J.; Palasantzas, Georgios

    2014-01-01

    Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during

  13. Synthesis and exceptional thermal stability of Mg-based bimetallic nanoparticles during hydrogenation

    NARCIS (Netherlands)

    Krishnan, Gopi; Negrea, Raluca F.; Ghica, Corneliu; ten Brink, Gert H.; Kooi, Bart J.; Palasantzas, Georgios

    2014-01-01

    Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during th

  14. Effects of non-thermal plasmas and electric field on hydrocarbon/air flames

    Science.gov (United States)

    Ganguly, Biswa

    2009-10-01

    Need to improve fuel efficiency, and reduce emission from hydrocarbon combustor in automotive and gas turbine engines have reinvigorated interest in reducing combustion instability of a lean flame. The heat generation rate in a binary reaction is HQ =N^2 c1c2 Q exp(-E/RT), where N is the density, c1 and c2 are mol fractions of the reactants, Q is the reaction heat release, E is the activation energy, R is the gas constant and T is the average temperature. For hydrocarbon-air reactions, the typical value of E/R ˜20, so most heat release reactions are confined to a thin reaction sheet at T >=1400 K. The lean flame burning condition is susceptible to combustion instability due to a critical balance between heat generation and heat loss rates, especially at high gas flow rate. Radical injection can increase flame speed by reducing the hydrocarbon oxidation reaction activation barrier and it can improve flame stability. Advances in nonequilibrium plasma generation at high pressure have prompted its application for energy efficient radical production to enhance hydrocarbon-air combustion. Dielectric barrier discharges and short pulse excited corona discharges have been used to enhance combustion stability. Direct electron impact dissociation of hydrocarbon and O2 produces radicals with lower fuel oxidation reaction activation barriers, initiating heat release reaction CnHm+O CnHm-1+ OH (and other similar sets of reactions with partially dissociated fuel) below the typical cross-over temperature. Also, N2 (A) produced in air discharge at a moderate E/n can dissociate O2 leading to oxidation of fuel at lower gas temperature. Low activation energy reactions are also possible by dissociation of hydrocarbon CnHm+e -> CnHm-2+H2+e, where a chain propagation reaction H2+ O OH+H can be initiated at lower gas temperature than possible under thermal equilibrium kinetics. Most of heat release comes from the reaction CO+OH-> CO2 +H, nonthermal OH production seem to improve

  15. Thermal Behaviour of AP Based CMDB Propellants with Stabilizers

    Directory of Open Access Journals (Sweden)

    S. N. Asthana

    1992-07-01

    Full Text Available Stability test results and DTA studies indicate the superiority of molecular sieve (MS over zirconium silicate (ZrSiO/sub 4/ as the stabilizer for a composite modified double base (CMDB system. Shelf life as computed from autoignition test results was 30 years for MS-based composition which is almost double the life of ZrSiO/sub 4/, but approximately half the life of resorcinol-based composition which was used as a reference. Higher stabilizing effect of MS as compared to ZrSiO/sub 4/ has been explained on the basis of the presence of channels and cavities in its structure, which makes it an effective adsorbent for decomposition catalysing species. Poor stabilization capability of m-dinitrobenzene as compared to resorcinol suggests the catalytic involvement of acidic decomposition products of nitrate esters in autodecomposition process of CMDB propellants.

  16. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    Science.gov (United States)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  17. MHD Spectroscopic Study of the Stabilizing Effect of Plasma Flow on the Resistive Wall Mode

    Science.gov (United States)

    Reimerdes, H.; Garofalo, A. M.; Navratil, G. A.; Chu, M. S.; Jackson, G. L.; Jensen, T. H.; La Haye, R. J.; Scoville, J. T.; Strait, E. J.; Edgell, D. H.; Jayakumar, R. J.; Okabayashi, M.

    2003-10-01

    MHD Spectroscopic Study of the Stabilizing Effect of Plasma Flow on the Resistive Wall Mode,* H. Reimerdes, A.M. Garofalo, G.A. Navratil, Columbia U, M.S. Chu, G.L. Jackson, T.H. Jensen, R.J. La Haye, J.T. Scoville, E.J. Strait, GA, D.H. Edgell, FAR-TECH, Inc., R.J. Jayakumar, LLNL, M. Okabayashi, PPPL - Resistive wall mode (RWM) stabilization by plasma rotation has been under study for the last decade. Dissipation caused by an interaction between the quasi-static magnetic perturbation and a near-sonic plasma flow alters the RWM stability [Bondeson, Phys. Rev. Lett. 72, 2709 (1994)]. To probe the RWM stability in DIII-D, we extend the technique of MHD spectroscopy, which was previously applied at frequencies above 10 kHz [Fasoli, et al., Phys. Rev. Lett. 75, 645 (1995)], to frequencies of a few Hz. Internal coils generate a rotating magnetic field, whose spatial structure largely overlaps with the RWM structure. The plasma response, measured as the perturbed field at the wall, is rigid and peaks when the external field rotates at a fraction of the inverse wall time in the direction of the plasma rotation, which is in good agreement with a single mode model [Garofalo, et al., Phys. Plasmas 9, 4573 (2002)]. This measurement is used to determine the contribution of the proposed dissipation mechanisms to the stabilization of the RWM.

  18. Development of innovative thermal plasma and particle diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, Benjamin-Leon

    2013-09-24

    Three original plasma diagnostic systems have been developed to investigate transient three-dimensional plasma processes with high spatial and temporal resolution. The developed diagnostics have been analyzed and tested by increasing the complexity from a stationary free burning Argon arc to a dc pulsed process and finally to a transient gas metal arc including droplet transfer through the plasma. The transient plasma parameters that have been determined include three-dimensional axially symmetric plasma densities (n{sub e}, n{sub A}, n{sub A+}, n{sub A++}), electron temperatures (T{sub e}), electrical conductivities (σ{sub el}), magnetic flux densities (B) and current densities (j{sub el}). In the case of a droplet transfer through an arc consisting of an Iron/Argon plasma, the droplet density, surface tension, viscosity, and temperature have been determined.

  19. Collisional Thermalization in Strongly Coupled Ultracold Neutral Plasmas

    Science.gov (United States)

    2017-01-25

    ultracold neutral plasmas, which are formed by photoionizing laser cooled atoms. These are the coldest neutral plasmas every created, and they allow...and received the “Editors’ Suggestion” distinction. We also completed numerical modeling of laser cooling a neutral plasma and construction of the...We also had to install several laser systems for driving the laser - cooling transitions in the ions and for repumping atoms out of dark states

  20. Microstructural evolution and growth kinetics of thermally grown oxides in plasma sprayed thermal barrier coatings

    Directory of Open Access Journals (Sweden)

    Xiaoju Liu

    2016-02-01

    Full Text Available The formation of thermally grown oxide (TGO during high temperature is a key factor to the degradation of thermal barrier coatings (TBCs applied on hot section components. In the present study both the CoNiCrAlY bond coat and ZrO2-8 wt.% Y2O3 (8YSZ ceramic coat of TBCs were prepared by air plasma spraying (APS. The composition and microstructure of TGO in TBCs were investigated using scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS and X-ray diffraction (XRD analysis. The growth rate of TGO for TBC and pure BC were gained after isothermal oxidation at 1100 °C for various times. The results showed that as-sprayed bond coat consisted of β and γ/γ′phases, β phase reducesd as the oxidation time increased. The TGO comprised α-Al2O3 formed in the first 2 h. CoO, NiO, Cr2O3 and spinel oxides appeared after 20 h of oxidation. Contents of CoO and NiO reduced while that of Cr2O3 and spinel oxides increased in the later oxidation stage. The TGO eventually consisted of a sub-Al2O3 layer with columnar microstructure and the upper porous CS clusters. The TGO growth kinetics for two kinds of samples followed parabolic laws, with oxidation rate constant of 0.344 μm/h0.5 for TBCs and 0.354 μm/h0.5 for pure BCs.

  1. Microstructural evolution and growth kinetics of thermally grown oxides in plasma sprayed thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    Xiaoju Liu; Teng Wang; Caicai Li; Zhenhuan Zheng; Qiang Li

    2016-01-01

    The formation of thermally grown oxide (TGO) during high temperature is a key factor to the degradation of thermal barrier coatings (TBCs) applied on hot section components. In the present study both the CoNiCrAlY bond coat and ZrO2-8 wt.% Y2O3 (8YSZ) ceramic coat of TBCs were prepared by air plasma spraying (APS). The composition and microstructure of TGO in TBCs were investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis. The growth rate of TGO for TBC and pure BC were gained after isothermal oxidation at 1100 °C for various times. The results showed that as-sprayed bond coat consisted of β and γ/γ'phases,β phase reducesd as the oxidation time increased. The TGO comprised α-Al2O3 formed in the first 2 h. CoO, NiO, Cr2O3 and spinel oxides appeared after 20 h of oxidation. Contents of CoO and NiO reduced while that of Cr2O3 and spinel oxides increased in the later oxidation stage. The TGO eventually consisted of a sub-Al2O3 layer with columnar microstructure and the upper porous CS clusters. The TGO growth kinetics for two kinds of samples followed parabolic laws, with oxidation rate constant of 0.344 μm/h0.5 for TBCs and 0.354 μm/h0.5 for pure BCs.

  2. Effect of Filler Concentration on Thermal Stability of Vinyl Copolymer Elastomer (VCE) Composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dali [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hubbard, Kevin Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devlin, David James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henderson, Kevin C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pacheco, Robin Montoya [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-06

    To study the thermal stability of vinyl copolymer elastomer (VCE) in its composite form, systematic TGA characterizations were conducted in both nonisothermal and isothermal modes. The effects of filler concentration on the aging behaviors of the VCE/filler composites were investigated under nitroplasticizer (NP) environment. FTIR characterization was used to probe the structural changes in the VCE polymer before and after the thermal treatments. This study suggests that the filler concentration significantly deteriorates the thermal stability of NP at a moderate temperature (< 70 °C). The degradation of NP, in turn, accelerates the aging process of the VCE polymer in its composite form.

  3. Stability of tokamak plasmas with internal transport barriers against high n ideal magnetohydrodynamic ballooning mode

    Institute of Scientific and Technical Information of China (English)

    Shi Bing-Ren; Qu Wen-Xiao

    2006-01-01

    A ballooning mode equation for tokamak plasma, with the toroidicity and the Shafranov shift effects included, is derived for a shift circular flux tokamak configuration. Using this equation, the stability of the plasma configuration with an internal transport barrier (IT2 against the high n (the toroidal mode number) ideal magnetohydrodynamic (MHD) ballooning mode is analysed. It is shown that both the toroidicity and the Shafranov shift effects are stabilizing.In the ITB region, these effects give rise to a low shear stable channel between the first and the second stability regions.Out of the ITB region towards the plasma edge, the stabilizing effect of the Shafranov shift causes the unstable zone to be significantly narrowed.

  4. Fatigue testing of plasma-sprayed thermal barrier coatings, volume 2

    Science.gov (United States)

    Cruse, T. A.; Nagy, A.; Popelar, C. F.

    1990-01-01

    A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.

  5. Fatigue testing of plasma-sprayed thermal barrier coatings, Volume 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cruse, T.A.; Nagy, A.; Popelar, C.F.

    1990-07-01

    A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.

  6. The Application of Thermal Plasma to Extraction Metallurgy and Related Fields

    Science.gov (United States)

    Akashi, K.

    1980-01-01

    Various applications of thermal plasma to extraction metallurgy and related fields are surveyed, chiefly on the basis of documents published during the past two or three years. Applications to melting and smelting, to thermal decomposition, to reduction, to manufacturing of inorganic compounds, and to other fields are considered.

  7. Sustained Rotational Stabilization of DIII-D Plasmas Above the No-Wall Beta Limit

    Science.gov (United States)

    Garofalo, A. M.

    2001-10-01

    Sustained stabilization of the n=1 kink mode by plasma rotation at beta approaching twice the stability limit calculated without a wall has been achieved in DIII-D by a combination of error field reduction and sufficient rotation drive. Previous experiments have transiently exceeded the no-wall beta limit, but demonstration of sustained rotational stabilization has remained elusive. Recent theory(A. Boozer, Phys. Rev. Lett. 86), 5059 (2001). predicts a resonant response to error fields in a plasma approaching marginal stability to a low-n kink mode. Enhancement of magnetic non-axisymmetry in the plasma leads to strong damping of the toroidal rotation, precisely in the high-beta regime where it is needed for stabilization. This ``error field amplification," EFA, is demonstrated in DIII-D experiments: applied n=1 error fields cause enhanced plasma response and strong rotation damping at beta above the no-wall limit, but have little effect at lower beta. The discovery of EFA has led to sustained operation above the no-wall limit through improved error field correction using an external coil set. The required correction is determined both by optimizing the external currents with respect to the plasma rotation, and by use of feedback to detect and minimize the plasma response to error fields as beta increases. Stability analysis and rotation braking experiments at different beta values show that beta is maintained 50% higher than the no-wall stability limit for duration greater than 1 second, and approaches beta twice the no-wall limit in several cases, with steady-state rotation levels. The results suggest that improved error field correction could allow plasmas to be maintained well above no-wall beta limit for as long as sufficient torque is provided.

  8. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Winterberg, F. [University of Nevada, Reno, Reno, Nevada (United States)

    2016-01-15

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  9. Thermal stability of n-dodecane : experiments and kinetic modelling

    CERN Document Server

    Herbinet, Olivier; Battin-Leclerc, Frédérique; Fournet, René

    2007-01-01

    The thermal decomposition of n-dodecane, a component of some jet fuels, has been studied in a jet-stirred reactor at temperatures from 793 to 1093 K, for residence times between 1 and 5 s and at atmospheric pressure. Thermal decomposition of hydrocarbon fuel prior the entrance in the combustion chamber is an envisaged way to cool the wall of hypersonic vehicles. The products of the reaction are mainly hydrogen, methane, ethane, 1,3-butadiene and 1-alkenes from ethylene to 1-undecene. For higher temperatures and residence times acetylene, allene, propyne, cyclopentene, 1,3-cyclopentadiene and aromatic compounds from benzene to pyrene through naphthalene have also been observed. A previous detailed kinetic model of the thermal decomposition of n-dodecane generated using EXGAS software has been improved and completed by a sub-mechanism explaining the formation and the consumption of aromatic compounds.

  10. Non-thermal Plasma Exposure Rapidly Attenuates Bacterial AHL-Dependent Quorum Sensing and Virulence

    Science.gov (United States)

    Flynn, Padrig B.; Busetti, Alessandro; Wielogorska, Ewa; Chevallier, Olivier P.; Elliott, Christopher T.; Laverty, Garry; Gorman, Sean P.; Graham, William G.; Gilmore, Brendan F.

    2016-01-01

    The antimicrobial activity of atmospheric pressure non-thermal plasma has been exhaustively characterised, however elucidation of the interactions between biomolecules produced and utilised by bacteria and short plasma exposures are required for optimisation and clinical translation of cold plasma technology. This study characterizes the effects of non-thermal plasma exposure on acyl homoserine lactone (AHL)-dependent quorum sensing (QS). Plasma exposure of AHLs reduced the ability of such molecules to elicit a QS response in bacterial reporter strains in a dose-dependent manner. Short exposures (30–60 s) produce of a series of secondary compounds capable of eliciting a QS response, followed by the complete loss of AHL-dependent signalling following longer exposures. UPLC-MS analysis confirmed the time-dependent degradation of AHL molecules and their conversion into a series of by-products. FT-IR analysis of plasma-exposed AHLs highlighted the appearance of an OH group. In vivo assessment of the exposure of AHLs to plasma was examined using a standard in vivo model. Lettuce leaves injected with the rhlI/lasI mutant PAO-MW1 alongside plasma treated N-butyryl-homoserine lactone and n-(3-oxo-dodecanoyl)-homoserine lactone, exhibited marked attenuation of virulence. This study highlights the capacity of atmospheric pressure non-thermal plasma to modify and degrade AHL autoinducers thereby attenuating QS-dependent virulence in P. aeruginosa. PMID:27242335

  11. Non-thermal Plasma Exposure Rapidly Attenuates Bacterial AHL-Dependent Quorum Sensing and Virulence.

    Science.gov (United States)

    Flynn, Padrig B; Busetti, Alessandro; Wielogorska, Ewa; Chevallier, Olivier P; Elliott, Christopher T; Laverty, Garry; Gorman, Sean P; Graham, William G; Gilmore, Brendan F

    2016-05-31

    The antimicrobial activity of atmospheric pressure non-thermal plasma has been exhaustively characterised, however elucidation of the interactions between biomolecules produced and utilised by bacteria and short plasma exposures are required for optimisation and clinical translation of cold plasma technology. This study characterizes the effects of non-thermal plasma exposure on acyl homoserine lactone (AHL)-dependent quorum sensing (QS). Plasma exposure of AHLs reduced the ability of such molecules to elicit a QS response in bacterial reporter strains in a dose-dependent manner. Short exposures (30-60 s) produce of a series of secondary compounds capable of eliciting a QS response, followed by the complete loss of AHL-dependent signalling following longer exposures. UPLC-MS analysis confirmed the time-dependent degradation of AHL molecules and their conversion into a series of by-products. FT-IR analysis of plasma-exposed AHLs highlighted the appearance of an OH group. In vivo assessment of the exposure of AHLs to plasma was examined using a standard in vivo model. Lettuce leaves injected with the rhlI/lasI mutant PAO-MW1 alongside plasma treated N-butyryl-homoserine lactone and n-(3-oxo-dodecanoyl)-homoserine lactone, exhibited marked attenuation of virulence. This study highlights the capacity of atmospheric pressure non-thermal plasma to modify and degrade AHL autoinducers thereby attenuating QS-dependent virulence in P. aeruginosa.

  12. Phase Behavior, Thermal Stability and Rheological Properties of PPEK/PC Blends

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Phase behavior, thermal stability and rheological properties of the blends of poly(phthalazinone ether ketone) (PPEK)with bisphenol-A polycarbonate (PC) prepared by solution coprecipitation were studied using differential scanning calorimetry (DSC), Frourier-Transform IR spectroscopy (FT-IR), thermogravimetric analysis (TGA) and capillary rheometer. The DSC results indicated that PPEK/PC blends are almost immiscible in full compositions. FT-IR investigation showed that there were no apparent specific interactions between the constituent polymers. The blends keep excellent thermal stability and the addition of PC degrades the thermal stability of blends to some degree. The thermal degradation processes of the blends are much similar to that of PC. The studies on rheological properties of blends show that blending PPEK with PC is beneficial to reducing the melt viscosity and improving the appearance of PPEK.

  13. Enhanced thermal stability of monodispersed silver cluster arrays assembled on block copolymer scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Xu, C H; Chen, X; Liu, Y J; Xie, B; Han, M [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); Song, F Q; Wang, G H, E-mail: sjhanmin@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2010-05-14

    Triblock copolymer poly(styrene-b-butadiene-b-styrene) (SBS) films with long-range ordered self-assembled nanopatterns are used as templates to selectively adsorb soft-landing silver clusters. Closely spaced cluster arrays with high monodispersity are formed through the confinement of the block copolymer scaffolds, and show a much enhanced thermal stability as compared with the cluster assemblies on the surfaces of covalent amorphous solids, or even on the disordered SBS films. Their morphologies are barely influenced by long time thermal annealing at a temperature as high as 180 deg. C, while in the latter case intense aggregations and coalescences of silver clusters are commonly observed upon annealing. The different thermal stabilities of the cluster assemblies also induce different evolutions of their optical extinction spectra under annealing. This promises a simple way to control the monodispersity and thermal stability of metal cluster assembly via self-assembled block copolymer template.

  14. Effects of Composition and Thermal Cycle on Transformation Behaviors, Thermal Stability and Mechanical Properties of CuAlAg Alloy

    Institute of Scientific and Technical Information of China (English)

    Yunqing MA; Chengbao JIANG; Lifen DENG; Huibin XU

    2003-01-01

    The phase transformation behavior, mechanical properties, and the thermal stability of CuAlAg alloy were studied andminor rare earth (0.1 wt pct La+Ce) was added to improve the mechanical property of the studied alloy. It was foundthat Ag addition in the CuAl binary alloy can improve the stability of martensitic transformation and high Al contentleads to the disappearing of martensitic transformation. The tensile strength and strain of the Cu-10.6Al-5.8Ag (wtpct) alloy were measured to be 383.5 MPa and 0.86%, respectively. With rare earth addition, the tensile strainincreased from 0.86% to 1.47%. The CuAlAg alloy did not exhibit martensitic transformation on the second heatingprocess. Its poor thermal stability still needs to be improved.

  15. Thermal rho`s in the quark-gluon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, R.D.

    1995-03-01

    I discuss different models which predict changes in the mass of the thermal {rho} field. I emphasize that while the predictions are strongly model dependent, nevertheless substantial shifts in the thermal {rho} mass are expected to occur at the point of phase transition. As long as the thermal {rho} peak does not become too broad, this should provide a striking signature of the existence of a phase transition.

  16. Thermal $\\varrho$s in the quark-gluon plasma

    CERN Document Server

    Pisarski, R D

    1995-01-01

    I discuss different models which predict changes in the mass of the thermal \\rho field. I emphasize that while the predictions are strongly model dependent, nevertheless substantial shifts in the thermal \\rho mass are expected to occur at the point of phase transition. As long as the thermal \\rho peak does not become too broad, this should provide a striking signature of the existence of a phase transition. (Based upon a talk presented at Quark Matter '95, Monterey, CA, Jan., 1995.)

  17. Analysis of protein stability and ligand interactions by thermal shift assay.

    Science.gov (United States)

    Huynh, Kathy; Partch, Carrie L

    2015-02-02

    Purification of recombinant proteins for biochemical assays and structural studies is time-consuming and presents inherent difficulties that depend on the optimization of protein stability. The use of dyes to monitor thermal denaturation of proteins with sensitive fluorescence detection enables rapid and inexpensive determination of protein stability using real-time PCR instruments. By screening a wide range of solution conditions and additives in a 96-well format, the thermal shift assay easily identifies conditions that significantly enhance the stability of recombinant proteins. The same approach can be used as an initial low-cost screen to discover new protein-ligand interactions by capitalizing on increases in protein stability that typically occur upon ligand binding. This unit presents a methodological workflow for small-scale, high-throughput thermal denaturation of recombinant proteins in the presence of SYPRO Orange dye.

  18. Boundary Conditions at the Walls with Thermionic Electron Emission in Two Temperature Modeling of "Thermal" Plasmas

    CERN Document Server

    Pekker, Leonid

    2015-01-01

    In this paper we propose new boundary conditions at the hot walls with thermionic electron emission for two-temperature thermal arc models. In the derived boundary conditions the walls are assumed to be made from refractory metals and that the erosion of the wall is small and, therefore, is not taken into account in the model. In these boundary conditions the plasma sheath formed at the electrode is considered as the interface between the plasma and the wall. The derived boundary conditions allow the calculation of the heat flux to the walls from the plasma and consequently the thermionic electron current that makes the two temperature thermal model self consistent.

  19. Thermal stability of boron nitride/silicon p-n heterojunction diodes

    Energy Technology Data Exchange (ETDEWEB)

    Teii, Kungen, E-mail: teii@asem.kyushu-u.ac.jp; Mizusako, Yusei; Hori, Takuro [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Matsumoto, Seiichiro [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Exploratory Materials Research Laboratory for Energy and Environment, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2015-10-21

    Heterojunctions of p-type cubic boron nitride (cBN) and n-type silicon with sp{sup 2}-bonded BN (sp{sup 2}BN) interlayers are fabricated under low-energy ion impact by plasma-enhanced chemical vapor deposition, and their rectification properties are studied at temperatures up to 573 K. The rectification ratio is increased up to the order of 10{sup 5} at room temperature by optimizing the thickness of the sp{sup 2}BN interlayer and the cBN fraction for suppressing the reverse leakage current. A highly rectifying p-type cBN/thick sp{sup 2}BN/n-type silicon junction diode shows irreversible rectification properties mainly characterized by a marked decrease in reverse current by an order of magnitude in an initial temperature ramp/down cycle. This irreversible behavior is much more reduced by conducting the cycle twice or more. The temperature-dependent properties confirm an overall increase in effective barrier heights for carrier injection and conduction by biasing at high temperatures, which consequently increases the thermal stability of the diode performance.

  20. Fabrication, thermal properties and thermal stabilities of microencapsulated n-alkane with poly(lauryl methacrylate) as shell

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xiaolin, E-mail: shirleyqiu2009@gmail.com [Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, School of Mechanical Engineering, Jiangnan University, Wuxi 214122 (China); Lu, Lixin; Wang, Ju [Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, School of Mechanical Engineering, Jiangnan University, Wuxi 214122 (China); Tang, Guoyi [Advanced Materials Institute and Clearer Production Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China); Song, Guolin [Advanced Materials Institute and Clearer Production Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

    2015-11-20

    Highlights: • Microencapsulation of octadecane and paraffin by crosslinked poly(lauryl methacrylate). • Octadecane microcapsules have a melting enthalpy of about 118 J g{sup −1}. • Weight loss temperatures of the microcapsules were increased by 67 °C and 28 °C. • Phase change enthalpies decreased by around 10 wt% after 500 thermal cycles. • Foams with microcapsules can be applied for passive temperature control. - Abstract: Microencapsulation of n-octadecane or paraffin with poly(lauryl methacrylate) (PLMA) shell was performed by a suspension-like polymerization. The polymer shell was crosslinked by pentaerythritol tetraacrylate (PETRA). The surface morphologies of microcapsules were investigated by scanning electron microscopy (SEM). Phase change properties, thermal reliabilities and thermal stabilities of microcapsules were determined by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The n-octadecane microcapsule exhibits higher melting enthalpy (118.0 J g{sup −1}) and crystallization enthalpy (108.3 J g{sup −1}) compared with the paraffin microcapsule. The thermal resistant temperatures were enhanced by more than 25 °C when n-alkanes were microencapsulated by PLMA. The PCM contents of microcapsules decreased by less than 4 wt% and 6 wt% after 500 and 1000 thermal cycles, respectively. Heat-up experiments indicated that microcapsule-treated foams exhibited upgraded thermal regulation capacities. Consequently, microencapsulated n-octadecane or paraffin with PLMA as shell possesses good potentials for heat storage and thermal regulation.

  1. Stabilization of immobilized glucose oxidase against thermal inactivation by silanization for biosensor applications.

    Science.gov (United States)

    Sarath Babu, V R; Kumar, M A; Karanth, N G; Thakur, M S

    2004-05-15

    An important requirement of immobilized enzyme based biosensors is the thermal stability of the enzyme. Studies were carried out to increase thermal stability of glucose oxidase (GOD) for biosensor applications. Immobilization of the enzyme was carried out using glass beads as support and the effect of silane concentration (in the range 1-10%) during the silanization step on the thermal stability of GOD has been investigated. Upon incubation at 70 degrees C for 3h, the activity retention with 1% silane was only 23%, which increased with silane concentration to reach a maximum up to 250% of the initial activity with 4% silane. Above this concentration the activity decreased. The increased stability of the enzyme in the presence of high silane concentrations may be attributed to the increase in the surface hydrophobicity of the support. The decrease in the enzyme stability for silane concentrations above 4% was apparently due to the uneven deposition of the silane layer on the glass bead support. Further work on thermal stability above 70 degrees C was carried out by using 4% silane and it was found that the enzyme was stable up to 75 degrees C with an increased activity of 180% after 3-h incubation. Although silanization has been used for the modification of the supports for immobilization of enzymes, the use of higher concentrations to stabilize immobilized enzymes is being reported for the first time.

  2. Small scale experiment on the plasma assisted thermal chemical preparation and combustion of pulverized coal

    Energy Technology Data Exchange (ETDEWEB)

    Masaya, Sugimoto; Koichi, Takeda [Akita Prefectural University (Japan); Solonenko, O.P. [Institute of Theoretical and Applied Mechanics, Novosibirsk (Russian Federation); Sakashita, M.; Nakamura, M. [Japan Technical Information Service, Tokyo (Japan)

    2001-07-01

    Ignition and stable combustion of pulverized coal with Nitrogen and Air plasmas are investigated experimentally for some different types of coal. The experimental results show that air plasma has strong effect for ignition and stabilization of coal combustion. In addition, suppression of NO{sub x} production could be possible even in air plasma. It is possible to ignite and burn stably for the inferior coal that contains volatile matter in the ratio of only 10% of dry total mass. (authors)

  3. Binary collision rates of relativistic thermal plasmas. I Theoretical framework

    Science.gov (United States)

    Dermer, C. D.

    1985-01-01

    Binary collision rates for arbitrary scattering cross sections are derived in the case of a beam of particles interacting with a Maxwell-Boltzmann (MB) plasma, or in the case of two MB plasmas interacting at generally different temperatures. The expressions are valid for all beam energies and plasma temperatures, from the nonrelativistic to the extreme relativistic limits. The calculated quantities include the reaction rate, the energy exchange rate, and the average rate of change of the squared transverse momentum component of a monoenergetic particle beam as a result of scatterings with particles of a MB plasma. Results are specialized to elastic scattering processes, two-temperature reaction rates, or the cold plasma limit, reproducing previous work.

  4. The non-thermal origin of the tokamak low-density stability limit

    Science.gov (United States)

    Paz-Soldan, C.; La Haye, R. J.; Shiraki, D.; Buttery, R. J.; Eidietis, N. W.; Hollmann, E. M.; Moyer, R. A.; Boom, J. E.; Chapman, I. T.; Contributors, JET

    2016-05-01

    DIII-D plasmas at very low density exhibit the onset of n  =  1 error field (EF) penetration (the ‘low-density locked mode’) not at a critical density or EF, but instead at a critical level of runaway electron (RE) intensity. Raising the density during a discharge does not avoid EF penetration, so long as RE growth proceeds to the critical level. Penetration is preceded by non-thermalization of the electron cyclotron emission, anisotropization of the total pressure, synchrotron emission shape changes, as well as decreases in the loop voltage and bulk thermal electron temperature. The same phenomena occur despite various types of optimal EF correction, and in some cases modes are born rotating. Similar phenomena are also found at the low-density limit in JET. These results stand in contrast to the conventional interpretation of the low-density stability limit as being due to residual EFs and demonstrate a new pathway to EF penetration instability due to REs. Existing scaling laws for penetration project to increasing EF sensitivity as bulk temperatures decrease, though other possible mechanisms include classical tearing instability, thermo-resistive instability, and pressure-anisotropy driven instability. Regardless of the first-principles mechanism, known scaling laws for Ohmic energy confinement combined with theoretical RE production rates allow rough extrapolation of the RE criticality condition, and thus the low-density limit, to other tokamaks. The extrapolated low-density limit by this pathway decreases with increasing machine size and is considerably below expected operating conditions for ITER. While likely unimportant for ITER, this effect can explain the low-density limit of existing tokamaks operating with small residual EFs.

  5. Thermal stability of the C106 dye in robust electrolytes

    DEFF Research Database (Denmark)

    Lund, Torben; Phuong, Nguyen Tuyet; Pechy, Peter

    of the particles were prepared in electrolyte mixture B. The solutions were thermally treated at 80 ◦C for 0-2000 hours followed by dye extraction and analysis by HPLC coupled to UV/Vis and electro spray mass spectrometry [2]. Figure 1 shows the concentration profiles of C106 samples prepared under ambient...

  6. Stability analysis of non-thermal complex astrofluids in the presence of polarized dust-charge fluctuations

    Science.gov (United States)

    Dutta, P.; Das, P.; Karmakar, P. K.

    2016-10-01

    The panoptic influence of plasma q-nonextensivity and dust-charge fluctuations on the gravito-electro-magnetic stability behaviour of a realistic non-thermal complex astroplasma model configuration with infinite geometrical extension is reconnoitered. It includes active viscoelasticity and dust polarization force-field effects in quasi-neutral hydrostatic equilibrium on the astrophysical fluid scales of space and time. The nontrivial linear model is simplified with the Jeans homogenization assumption (Jeans swindle, no zeroth-order force-field). It analytically and logically enables us to relax from the inclusion of large-scale inhomogeneities and of associated intrinsic complications. The role of boundary effects on the dynamical stability is assumed to be insignificant. We apply a standard technique of the Fourier formulaic plane-wave analysis over the basic cloud-structuring equations in a closed integrated form. It reduces the model Fourier algebraic equations decoupling into a unique form of cubic dispersion relation having mixed variable coefficients, which, indeed, explicitly, evolve on the diverse model plasma parameters. It is interestingly seen that the polarization and nonextensive effects directly play destabilizing roles. In contrast, the viscoelasticity and magnetic field create stabilizing effects on the instability. The pragmatic significance and applicability in the context of astro-cosmo-galactic environments are briefly indicated aboard analytic facts and introspective faults.

  7. Thermal Stability Influence of the Enclosure Structure on the Building’s Energy Efficiency

    Directory of Open Access Journals (Sweden)

    Zaborova Daria

    2016-01-01

    Full Text Available Thermal stability of the enclosure structures is one of the most important objective in the building design. Thermal processes in the wall depend not only on the internal and external air temperature, but also on many other factors. Therefore, complexity of this process make heat conservation in the room to be an actual problem. This paper presents dependence between thermal stability of the enclosure structure and its design. It was shown that thermophysical characteristics of materials directly affect the thermal processes in the wall. For the research, three frequently used types of enclosure structure in Russia were taken. For each wall was found the average temperature and cooling time. As a result, it was found that the higher values of thermal conductivity, specific heat and material density are, the higher average temperature of the wall is.

  8. Integrated parametric study of a hybrid-stabilized argon-water arc under subsonic, transonic and supersonic plasma flow regimes

    Science.gov (United States)

    Jeništa, J.; Takana, H.; Nishiyama, H.; Bartlová, M.; Aubrecht, V.; Křenek, P.; Hrabovský, M.; Kavka, T.; Sember, V.; Mašláni, A.

    2011-11-01

    This paper presents a numerical investigation of characteristics and processes in the worldwide unique type of thermal plasma generator with combined stabilization of arc by argon flow and water vortex, the so-called hybrid-stabilized arc. The arc has been used for spraying of ceramic or metallic particles and for pyrolysis of biomass. The net emission coefficients as well as the partial characteristics methods for radiation losses from the argon-water arc are employed. Calculations for 300-600 A with 22.5-40 standard litres per minute (slm) of argon reveal transition from a transonic plasma flow for 400 A to a supersonic one for 600 A with a maximum Mach number of 1.6 near the exit nozzle of the plasma torch. A comparison with available experimental data near the exit nozzle shows very good agreement for the radial temperature profiles. Radial velocity profiles calculated 2 mm downstream of the nozzle exit show good agreement with the profiles determined from the combination of calculation and experiment (the so-called integrated approach). A recent evaluation of the Mach number from the experimental data for 500 and 600 A confirmed the existence of the supersonic flow regime.

  9. DC Thermal Plasma Design and Utilization for the Low Density Polyethylene to Diesel Oil Pyrolysis Reaction

    Directory of Open Access Journals (Sweden)

    Hossam A. Gabbar

    2017-06-01

    Full Text Available The exponential increase of plastic production produces 100 million tonnes of waste plastics annually which could be converted into hydrocarbon fuels in a thermal cracking process called pyrolysis. In this research work, a direct current (DC thermal plasma circuit is designed and used for conversion of low density polyethylene (LDPE into diesel oil in a laboratory scale pyrolysis reactor. The experimental setup uses a 270 W DC thermal plasma at operating temperatures in the range of 625 °C to 860 °C for a low density polyethylene (LDPE pyrolysis reaction at pressure = −0.95, temperature = 550 °C with τ = 30 min at a constant heating rate of 7.8 °C/min. The experimental setup consists of a vacuum pump, closed system vessel, direct current (DC plasma circuit, and a k-type thermocouple placed a few millimeters from the reactant sample. The hydrocarbon products are condensed to diesel oil and analyzed using flame ionization detector (FID gas chromatography. The analysis shows 87.5% diesel oil, 1,4-dichlorobenzene (Surr, benzene, ethylbenzene and traces of toluene and xylene. The direct current (DC thermal plasma achieves 56.9 wt. % of diesel range oil (DRO, 37.8 wt. % gaseous products and minimal tar production. The direct current (DC thermal plasma shows reliability, better temperature control, and high thermal performance as well as the ability to work for long operation periods.

  10. Influence of high flux hydrogen-plasma exposure on the thermal shock induced crack formation in tungsten

    NARCIS (Netherlands)

    Wirtz, M.; Linke, J.; Pintsuk, G.; Rapp, J.; Wright, G. M.

    2012-01-01

    The influence of high flux hydrogen-plasma on the thermal shock behaviour of tungsten was investigated in a combined experiment using the linear plasma device Pilot-PSI and the electron beam facility JUDITH 1. Tungsten targets were exposed to high flux hydrogen plasma, cyclic thermal shock tests and

  11. Iron-stabilized nanocrystalline ZrO{sub 2} solid solutions: Synthesis by combustion and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Legorreta Garcia, Felipe [Universite de Toulouse, CIRIMAT, CNRS-UPS-INP, Universite Paul-Sabatier, 31062 Toulouse cedex 9 (France); Resende, Valdirene Gonzaga de; De Grave, Eddy [NUMAT, Department of Subatomic and Radiation Physics, University of Ghent, Proeftuinstraat 86, B-9000 Gent (Belgium); Peigney, Alain; Barnabe, Antoine [Universite de Toulouse, CIRIMAT, CNRS-UPS-INP, Universite Paul-Sabatier, 31062 Toulouse cedex 9 (France); Laurent, Christophe, E-mail: laurent@chimie.ups-tlse.fr [Universite de Toulouse, CIRIMAT, CNRS-UPS-INP, Universite Paul-Sabatier, 31062 Toulouse cedex 9 (France)

    2009-06-03

    The synthesis of Fe{sup 3+}-stabilized zirconia by the nitrate/urea combustion route was investigated. Using several characterization techniques, including X-ray diffraction, field-emission-gun scanning electron microscopy and notably Moessbauer spectroscopy, it was possible to determine the appropriate amount of urea that allows to obtain a totally stabilized Zr{sub 0.9}Fe{sub 0.1}O{sub 1.95} solid solution. The nanocrystalline zirconia solid solution is mostly tetragonal, but the presence of the cubic phase could not be ruled out. An in-depth study of the thermal stability in air showed that the Fe{sup 3+} solubility in the stabilized solid solution starts to decrease at about 875 deg. C which results in the formation of hematite (possibly containing some Zr{sup 4+}) at the surface of the zirconia grains and further provokes the progressive transformation into the monoclinic zirconia phase.

  12. Sterculia striata seed kernel oil: Characterization and thermal stability

    Directory of Open Access Journals (Sweden)

    Oliveira Cavalheiro, José Marcelino

    2008-06-01

    Full Text Available The objective of the present work was to characterize sterculia seed kernel oil. The chemical composition of the seeds, physicochemical properties as well as the fatty acid composition of the kernel oil was determined. The chemical composition of kernel flour presented about 25.8% lipid content. The physicochemical parameters such as acid, iodine, peroxide and saponification values were 0.82 (% as oleic acid, 69.2 (g iodine/100 g oil, 4.20 (m eq./kg and 136.1 (mg. KOH/g oil, respectively. With respect to fatty acid composition, the oil contained 36.2, 43.7 and 10.9% saturated, monounsaturated and polyunsaturated fatty acids, respectively. Palmitic acid (31.9%, oleic acid (41.7% and linoleic acid (10.73% were the principal saturated, monounsaturated and polyunsaturated fatty acids. Two cyclopropanoid fatty acids i.e. sterculic and malvalic acid were identified at a concentration of 5.3 and 2.3%, respectively. With regards to the thermal stability of the oil, a thermogravimetric analysis (TGA has shown that the oil was stable until about 284 °C, above that the oil started loosing mass, while a differential thermogravimetric analysis (DTGA revealed three stages of degradation with an increase in temperature. These stages corresponded to the degradation of polyunsaturated, monounsaturated and saturated fatty aids. The Differential Scanning Calorimetric (DSC analysis showed the existence of two exothermic events of energy transition, one of which is related to the oxidation reactions and another to the decomposition of the oil. Exothermic transitions in the oil were initiated at a temperature (Ti of 287.79 °C, and terminated at 347.81 °C, with an enthalpy variation of 11.69 joules.g–1 and at initial temperature (Ti of 384.87 °C, peak temperature (Tp 415.71 °C, final temperature (Tf 448.9 °C and an enthalpy of 200.83 Joules. G–1El objetivo de este trabajo fue la caracterización del aceite de almendra de la semilla de

  13. CHARACTERIZATION OF YTTRIA AND MAGNESIA PARTIALLY STABILIZED ZIRCONIA BIOCOMPATIBLE COATINGS DEPOSITED BY PLASMA SPRAYING

    Directory of Open Access Journals (Sweden)

    Roşu R. A.

    2013-09-01

    Full Text Available Zirconia (ZrO2 is a biocompatible ceramic material which is successfully used in medicine to cover the metallic implants by various methods. In order to avoid the inconvenients related to structural changes which may appear because of the temperature treatment while depositing the zirconia layer over the metallic implant, certain oxides are added, the most used being Y2O3, MgO and CaO. This paper presents the experimental results regarding the deposition of yttria (Y2O3 and magnesia (MgO partially stabilized zirconia layers onto titanium alloy substrate by plasma spraying method. X ray diffraction investigations carried out both on the initial powders and the coatings evidenced the fact that during the thermal spraying process the structure has not been significantly modified, consisting primarily of zirconium oxide with tetragonal structure. Electronic microscopy analyses show that the coatings are dense, uniform and cracks-free. Adherence tests performed on samples whose thickness ranges between 160 and 220 μm showed that the highest value (23.5 MPa was obtained for the coating of ZrO2 - 8 wt. % Y2O3 with 160 μm thickness. The roughness values present an increasing tendency with increasing the coatings thickness.

  14. Factors affecting the thermal shock behavior of yttria stabilized hafnia based graphite and tungsten composites.

    Science.gov (United States)

    Lineback, L. D.; Manning, C. R.

    1971-01-01

    Hafnia-based composites containing either graphite or tungsten were investigated as rocket nozzle throat inserts in solid propellant rocket engines. The thermal shock resistance of these materials is considered in terms of macroscopic thermal conductivity, thermal expansion, modulus of elasticity, and compressive fracture stress. The effect of degree of hafnia stabilization, density, and graphite or tungsten content upon these parameters is discussed. The variation of the ratio of elastic modulus to compressive fracture stress with density and its effect upon thermal shock resistance of these materials are discussed in detail.

  15. Structural stability of hydrogenated amorphous carbon overcoats used in heat-assisted magnetic recording investigated by rapid thermal annealing

    KAUST Repository

    Wang, N.

    2013-01-01

    Ultrathin amorphous carbon (a-C) films are extensively used as protective overcoats of magnetic recording media. Increasing demands for even higher storage densities have necessitated the development of new storage technologies, such as heat-assisted magnetic recording (HAMR), which uses laser-assisted heating to record data on high-stability media that can store single bits in extremely small areas (∼1 Tbit/in.2). Because HAMR relies on locally changing the coercivity of the magnetic medium by raising the temperature above the Curie temperature for data to be stored by the magnetic write field, it raises a concern about the structural stability of the ultrathin a-C film. In this study, rapid thermal annealing (RTA) experiments were performed to examine the thermal stability of ultrathin hydrogenated amorphous carbon (a-C:H) films deposited by plasma-enhanced chemical vapor deposition. Structural changes in the a-C:H films caused by RTA were investigated by x-ray photoelectron spectroscopy, Raman spectroscopy, x-ray reflectivity, and conductive atomic force microscopy. The results show that the films exhibit thermal stability up to a maximum temperature in the range of 400-450 °C. Heating above this critical temperature leads to hydrogen depletion and sp 2 clustering. The critical temperature determined by the results of this study represents an upper bound of the temperature rise due to laser heating in HAMR hard-disk drives and the Curie temperature of magnetic materials used in HAMR hard disks. © 2013 American Institute of Physics.

  16. Development of non-thermal atmospheric pressure plasma system for surface modification of polymeric materials

    Science.gov (United States)

    Kasih, T. P.

    2017-04-01

    Non-thermal plasma has become one of the new technologies which are highly developed now days. This happens because the cold plasma using the principle of generated reactive gases that have the ability to modify the surface properties of a material or product without changing the original characteristics of the material. The purpose of this study is to develop a cold plasma system that operates at atmospheric pressure and investigates the effect of cold plasma treatment to change the surface characteristics of the polymer material polyethylene (PE) at various time conditions. We are successfully developing a non-thermal plasma system that can operate at atmospheric pressure and can be run with Helium or Argon gas. The characteristics of plasma will be discussed from the view of its electrical property, plasma discharge regime andoperation temperature. Experiment results on plasma treatment on PE material shows the changes of surface properties of originally hydrophobic material PE becomes hydrophilic by only few seconds of plasma treatment and level of hydrophilicity become greater with increasing duration of plasma treatment. Confirmation of this is shown by the measurement of contact angle of droplets of water on the surface of PE are getting smaller.

  17. SEMICONDUCTOR DEVICES Design consideration of the thermal and electro stability of multi-finger HBTs based on different device structures

    Science.gov (United States)

    Yanhu, Chen; Huajun, Shen; Xinyu, Liu; Hui, Xu; Ling, Li; Huijun, Li

    2010-10-01

    The thermal and electro stability of multi-finger heterojunction bipolar transistors (HBTs) with different structures were analyzed and discussed simultaneously. The thermal stability of the devices with different layout structures was assessed by the DC-IV test and thermal resistance calculation. Their electro stability was assessed by the calculation of the stability factor K based on the S parameter of the HBT. It is found that HBTs with higher thermal stability are prone to lower electro stability. The trade-off relationship between the two types of stability was explained and discussed by using a compact K-factor analytic formula which is derived from the small signal equivalent circuit model of HBT. The electro stability of the device with a thermal ballasting resistor was also discussed, based on the analytic formula.

  18. Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    Bin Luo; Shuang-Nan Zhang

    2004-01-01

    In normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma.We calculate the Bremsstrahlung radiation of a two-temperature plasma by taking into account of the motion of ions.Our results show that the total radiation power is always lower if the motion of ions is considered.We also apply the two-temperature Bremsstrahlung radiation mechanism for an analytical Advection-Dominated Accretion Flow(ADAF)model:we find the two-temperature correction to the total Bremsstrahlung radiation for ADAF is negligible.

  19. Studies on Thermal Stability and Fluid Property of PVC Filled with Hydrotalcite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Hydrotalcite can act as a co-stabilizer with other main stabilizer for poly(vinyl chloride)(PVC). The thermal stability and fluid property of PVC filled with hydrotalcite surface-treated with titanate and silane were studied in this work. Organic Sn is a main stabilizer and hydrotalcite is a stabilizing assistant. The stability of the PVC resin mixed with organic Sn and hydrotalcite is better than that of the PVC resin mixed with organic Sn alone. It is shown that the PVC resin filled with hydrotalcite possesses a better static and dynamic heat stability. Moreover, hydrotalcite can improve the fluid property of PVC, which is advantageous to the processing of PVC, and the optimum content of hydrotalcite is about 1%-2%(mass fraction).

  20. Carbon dioxide dissociation in non-thermal radiofrequency and microwave plasma

    Science.gov (United States)

    Huang, Qiang; Zhang, Diyu; Wang, Dongping; Liu, Kezhao; Kleyn, Aart W.

    2017-07-01

    We have studied carbon dioxide dissociation in inductively coupled radiofrequency plasma and microwave plasma at low gas pressure. Both systems exhibit features of non-thermal plasma. The highest energy efficiency observed is 59.3% (2.13 mmol kJ-1), exceeding the maximum value of about 45% in case of thermodynamic equilibrium, and a maximum conversion of 80.6% is achieved. Different discharge conditions, such as the source frequency, discharge gas pressure and the addition of argon, will affect the plasma parameters, especially the electron energy distribution. This plays a great role in the energy transfer from non-thermal plasma to the molecular dissociation reaction channel by enabling the ladder climbing of the carbon dioxide molecular vibration. The results indicate the importance of ladder climbing.

  1. Non-thermal atmospheric-pressure plasma possible application in wound healing.

    Science.gov (United States)

    Haertel, Beate; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Lindequist, Ulrike

    2014-11-01

    Non-thermal atmospheric-pressure plasma, also named cold plasma, is defined as a partly ionized gas. Therefore, it cannot be equated with plasma from blood; it is not biological in nature. Non-thermal atmospheric-pressure plasma is a new innovative approach in medicine not only for the treatment of wounds, but with a wide-range of other applications, as e.g. topical treatment of other skin diseases with microbial involvement or treatment of cancer diseases. This review emphasizes plasma effects on wound healing. Non-thermal atmospheric-pressure plasma can support wound healing by its antiseptic effects, by stimulation of proliferation and migration of wound relating skin cells, by activation or inhibition of integrin receptors on the cell surface or by its pro-angiogenic effect. We summarize the effects of plasma on eukaryotic cells, especially on keratinocytes in terms of viability, proliferation, DNA, adhesion molecules and angiogenesis together with the role of reactive oxygen species and other components of plasma. The outcome of first clinical trials regarding wound healing is pointed out.

  2. Solution and solid state thermal stability of morpholinedithiocarbamates

    Directory of Open Access Journals (Sweden)

    Antunes Patrícia A.

    2001-01-01

    Full Text Available Thermogravimetric and differential scanning calorimetric investigation of the thermal behavior of NH4+, Mn2+, Co2+, Ni2+ e Cu2+ morpholinedithiocarbamates were performed under nitrogen and air atmospheres in order to investigate the effect, in the thermal decomposition, of the presence of an oxygen as the heteroatom in the amine ring. Decomposition products were identified by their X-ray diffraction patterns. Metal sulfites and oxides were the major residues under nitrogen and air atmospheres, respectively. Spectrophotometric measurements were used to estimate the pKa =3.56 for the morpholinedithiocarbamic acid at 0.50 mol dm-3 ionic strength (NaClO4 at 25.0 °C and kinetic parameters of decomposition at different pH values (k lim = 0.14 ± 0.04 s-1 e t½ lim = 5.3 ± 1.2 s.

  3. Thermal stability of butter oils produced from sheep’s non-pasteurized and pasteurized milk

    Directory of Open Access Journals (Sweden)

    FLAVIA POP

    Full Text Available The physical and chemical characteristics and thermal stability of butter oil produced from non-pasteurized and pasteurized sheep’s milk were studied. Thermal stability of samples was estimated by using the accelerated shelf-life testing method. Samples were stored at 50, 60 and 70oC in the dark and the reaction was monitored by measuring peroxide, thiobarbituric acid and free fatty acid values. The peroxide and thiobarbituric acid values increased as the temperature increased. The increase of acid values of the two samples was not significant. A slight increase in free fatty acid value showed that hydrolytic reactions were not responsible for the deterioration of butter oil samples in thermal stability studies. When compared, butter oil produced from pasteurized sheep’s milk has higher thermal stability than butter oil produced from non-pasteurized sheep’s milk. Although butter oil produced from non-pasteurized milk was not exposed to any heat treatment, the shelf-life of this product was lower than the shelf-life of butter oil produced from pasteurized sheep’s milk. Therefore, heat treatment for pasteurization did not affect the thermal stability of butter oil.

  4. Effect of various nanofillers on thermal stability and degradation kinetics of polymer nanocomposites.

    Science.gov (United States)

    Choudhury, Anusuya; Bhowmick, Anil K; Ong, Christopher; Soddemann, Matthias

    2010-08-01

    Structure of nanofillers and their subsequent interaction with a polymer is very important in determining thermal stability of polymer nanocomposite. In this paper, we tried to correlate structure of various 0, 1 and 2 dimensional nanofillers with the thermal stability of hydrogenated nitrile butadiene rubber (HNBR) nanocomposites. Organically modified and unmodified layered silicates such as montmorillonite (Cloisite Na+, Cloisite 30B and Cloisite 15A), rod-like fibrous filler (sepiolite) and spherical nanoparticles (nanosilica) were chosen for this purpose. A significant improvement in thermal stability (obtained by thermogravimeric analysis and differential scanning calorimetry) was observed for silica-filled nanocomposites. However, the activation energy of the nanocomposites calculated by different kinetic methods (both non-isothermal and isothermal methods) was found to be significantly high for sepiolite, 30B and silica-filled nanocomposites. The results were explained with the help of structure of the nanofillers, their interaction with the elastomer and the subsequent dispersion, as measured by X-ray diffraction, transmission electron microscopy and atomic force microscopy. From these analyses it was concluded that organically modified montmorillonite, sepiolite and nanosilica increase the thermal stability of the nanocomposite to a great extent due to the interaction of the reactive groups on the surface of these fillers with the polymer and high thermal stability of these inorganic fillers. Finally, degradation mechanism of HNBR in presence of the nanofillers at severe operating temperatures was investigated with the help of FTIR spectroscopy.

  5. Thermal stability of Al-Cr-N hard coatings

    Energy Technology Data Exchange (ETDEWEB)

    Willmann, H. [Materials Center Leoben, Franz-Josef Strasse 13, 8700 Leoben (Austria) and IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden)]. E-mail: herbert.willmann@unileoben.ac.at; Mayrhofer, P.H. [Department of Physical Metallurgy and Materials Testing, University of Leoben, 8700 Leoben (Austria); Materials Chemistry, RWTH-Aachen, 52074 Aachen (Germany); Persson, P.O.A. [IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden); FEI Company, 5651 GG Eindhoven (Netherlands); Reiter, A.E. [Balzers Ltd., 9496 Balzers (Liechtenstein); Hultman, L. [IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden); Materials Chemistry, RWTH-Aachen, 52074 Aachen (Germany); Mitterer, C. [Department of Physical Metallurgy and Materials Testing, University of Leoben, 8700 Leoben (Austria); Christian Doppler Laboratory for Advanced Hard Coatings, University of Leoben, 8700 Leoben (Austria)

    2006-06-15

    Heat treatment of arc-evaporated cubic Al{sub 0.7}Cr{sub 0.3}N hard coatings in Ar up to 1450 deg. C causes precipitation of AlN. The Cr-enriched matrix transforms into Cr via Cr{sub 2}N under N{sub 2} release. These reactions are investigated by simultaneous thermal analysis, mass spectrometry, X-ray diffraction, and analytical transmission electron microscopy.

  6. Thermal Decomposition of RP-2 with Stabilizing Additives

    Science.gov (United States)

    2010-04-01

    the reactors were removed from the thermostatted block and immediately cooled in room-temperature water . The thermally stressed fuel was then...34 Supercritical Fuel Deposition Mechanisms," Industrial & Engineering Chemistry Research 32, 3117-3122 (1993). 22. MacDonald, M.E., Davidson, D.F...H.H., and Hatcher, P.G., "Pyrolytic Degradation Studies of a Coal -Derived and a Petroleum-Derived Aviation Jet Fuel," Energy & Fuels 7, 234-243 (1993

  7. Thermal stability of zeolitic tuff from Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Bish, D.L.

    1990-04-01

    Thermal models of the proposed repository at Yucca Mountain, Nevada, suggest that rocks near the proposed host rock will experience elevated temperatures for at least 1000 yrs. In order to assess the effects of elevated temperatures on zeolites clinoptilolite and mordenite were investigated using a combination of high-temperature X-ray powder diffraction, thermogravimetric and differential scanning calorimetric analysis, and long-term heating experiments. 13 refs., 7 figs.

  8. Comparative proteomics evaluation of plasma exosome isolation techniques and assessment of the stability of exosomes in normal human blood plasma.

    Science.gov (United States)

    Kalra, Hina; Adda, Christopher G; Liem, Michael; Ang, Ching-Seng; Mechler, Adam; Simpson, Richard J; Hulett, Mark D; Mathivanan, Suresh

    2013-11-01

    Exosomes are nanovesicles released by a variety of cells and are detected in body fluids including blood. Recent studies have highlighted the critical application of exosomes as personalized targeted drug delivery vehicles and as reservoirs of disease biomarkers. While these research applications have created significant interest and can be translated into practice, the stability of exosomes needs to be assessed and exosome isolation protocols from blood plasma need to be optimized. To optimize methods to isolate exosomes from blood plasma, we performed a comparative evaluation of three exosome isolation techniques (differential centrifugation coupled with ultracentrifugation, epithelial cell adhesion molecule immunoaffinity pull-down, and OptiPrep(TM) density gradient separation) using normal human plasma. Based on MS, Western blotting and microscopy results, we found that the OptiPrep(TM) density gradient method was superior in isolating pure exosomal populations, devoid of highly abundant plasma proteins. In addition, we assessed the stability of exosomes in plasma over 90 days under various storage conditions. Western blotting analysis using the exosomal marker, TSG101, revealed that exosomes are stable for 90 days. Interestingly, in the context of cellular uptake, the isolated exosomes were able to fuse with target cells revealing that they were indeed biologically active.

  9. Thermal stability test and analysis of a 20-actuator bimorph deformable mirror

    Institute of Scientific and Technical Information of China (English)

    Ning Yu; Zhou Hong; Yu Hao; Rao Chang-Hui; Jiang Wen-Han

    2009-01-01

    One of the important characteristic of adaptive mirrors is the thermal stability of surface flatness. In this paper, the thermal stability from 13℃ to 25℃ of a 20-actuator bimorph deformable mirror is tested by a Shack-Hartmann wavefront sensor. Experimental results show that, the surface P-V of bimorph increases nearly linearly with ambient temperature. The ratio is 0.11 μm/℃ and the major component of surface displacement is defocused, compared with which, astigmatism, coma and spherical aberration contribute very small. Besides, a finite element model is built up to analyse the influence of thickness, thermal expansion coefficient and Young's modulus of materials on thermal stability. Calculated results show that bimorph has the best thermal stability when the materials have the same thermal expansion coefficient. And when the thickness ratio of glass to PZT is 3 and Young's modulus ratio is approximately 0.4, the surface instability behaviour of the bimorph manifests itself most severely.

  10. Correlation of aging and thermal stability of commercial 18650-type lithium ion batteries

    Science.gov (United States)

    Börner, M.; Friesen, A.; Grützke, M.; Stenzel, Y. P.; Brunklaus, G.; Haetge, J.; Nowak, S.; Schappacher, F. M.; Winter, M.

    2017-02-01

    Established safety of lithium ion batteries is key for the vast diversity of applications. The influence of aging on the thermal stability of individual cell components and complete cells is of particular interest. Commercial 18650-type lithium ion batteries based on LiNi0.5Co0.2Mn0.3O2/C are investigated after cycling at different temperatures. The variations in the electrochemical performance are mainly attributed to aging effects on the anode side considering the formation of an effective solid-electrolyte interphase (SEI) during cycling at 45 °C and a thick decomposition layer on the anode surface at 20 °C. The thermal stability of the anodes is investigated including the analysis of the evolving gases which confirmed the severe degradation of the electrolyte and active material during cycling at 20 °C. In addition, the presence of metallic lithium deposits could strongly affect the thermal stability. Thermal safety tests using quasi-adiabatic conditions show variations in the cells response to elevated temperatures according to the state-of-charge, i.e. a reduced reactivity in the discharged state. Furthermore, it is revealed that the onset of exothermic reactions correlates with the thermal stability of the SEI, while the thermal runaway is mainly attributed to the decomposition of the cathode and the subsequent reactions with the electrolyte.

  11. Effect of Pressure on Thermal Stability and Decomposition of KDP Crystal

    Institute of Scientific and Technical Information of China (English)

    DING Jian-Xu; WANG Tao; WANG Sheng-Lai; CUI De-Liang; MU Xiao-Ming; XU Xin-Guang

    2011-01-01

    @@ Effect of pressure on thermal behavior of KDP crystals is investigated by using the in-situ infrared reflective spectra.Compared with that under normal atmosphere, the onset temperature of decomposition under pressure of 1 MPa is improved to from 210℃ to 213℃, suggesting that the thermal stability of KDP is enhanced.Under pressure of 2 MPa, the thermal stability is deteriorated and KDP begins to decompose at 183℃.Under normal atmosphere KDP decomposes in route of translating to K4P2O7 firstly, and then to KPO3.Under pressures of 1 MPa and 2MPa, KDP translates to KPO3 directly without any other polymeric intermediates.%Effect of pressure on thermal behavior of KDP crystals is investigated by using the in-situ infrared reflective spectra.Compared with that under normal atmosphere, the onset temperature of decomposition under pressure of 1 MPa is improved to from 210 ℃ to 213℃, suggesting that the thermal stability of KDP is enhanced.Under pressure of 2 MPa, the thermal stability is deteriorated and KDP begins to decompose at 183℃.Under normal atmosphere KDP decomposes in route of translating to K4P2O7 firstly, and then to KPO3.Under pressures of 1 MPa and 2 MPa, KDP translates to KPO3 directly without any other polymeric intermediates.

  12. Investigation of non-thermal plasma effects on lung cancer cells within 3D collagen matrices

    Science.gov (United States)

    Karki, Surya B.; Thapa Gupta, Tripti; Yildirim-Ayan, Eda; Eisenmann, Kathryn M.; Ayan, Halim

    2017-08-01

    Recent breakthroughs in plasma medicine have identified a potential application for the non-thermal plasma in cancer therapy. Most studies on the effects of non-thermal plasma on cancer cells have used traditional two-dimensional (2D) monolayer cell culture. However, very few studies are conducted employing non-thermal plasma in animal models. Two dimensional models do not fully mimic the three-dimensional (3D) tumor microenvironment and animal models are expensive and time-consuming. Therefore, we used 3D collagen matrices that closely resemble the native geometry of cancer tissues and provide more physiologically relevant results than 2D models, while providing a more cost effective and efficient precursor to animal studies. We previously demonstrated a role for non-thermal plasma application in promoting apoptotic cell death and reducing the viability of A549 lung adenocarcinoma epithelial cells cultured upon 2D matrices. In this study, we wished to determine the efficacy of non-thermal plasma application in driving apoptotic cell death of A549 lung cancer cells encapsulated within a 3D collagen matrix. The percentage of apoptosis increased as treatment time increased and was time dependent. In addition, the anti-viability effect of plasma was demonstrated. Twenty-four hours post-plasma treatment, 38% and 99% of cell death occurred with shortest (15 s) and longest treatment time (120 s) respectively at the plasma-treated region. We found that plasma has a greater effect on the viability of A549 lung cancer cells on the superficial surface of 3D matrices and has diminishing effects as it penetrates the 3D matrix. We also identified the nitrogen and oxygen species generated by plasma and characterized their penetration in vertical and lateral directions within the 3D matrix from the center of the plasma-treated region. Therefore, the utility of non-thermal dielectric barrier discharge plasma in driving apoptosis and reducing the viability of lung cancer cells

  13. Comprehensive transient-state study for CARMENES NIR high-thermal stability

    Science.gov (United States)

    Becerril, Santiago; Sánchez, Miguel A.; Cárdenas, M. C.; Rabaza, Ovidio; Ramón, Alejandro; Abril, Miguel; Costillo, Luis P.; Morales, Rafael; Rodríguez, Alicia; Amado, Pedro J.

    2010-07-01

    CARMENES has been proposed as a next-generation instrument for the 3.5m Calar Alto Telescope. Its objective is finding habitable exoplanets around M dwarfs through radial velocity measurements (m/s level) in the near-infrared. Consequently, the NIR spectrograph is highly constraint regarding thermal/mechanical requirements. Indeed, the requirements used for the present study limit the thermal stability to +/-0.01K (within year period) over a working temperature of 243K in order to minimise radial velocity drifts. This can be achieved by implementing a solution based on several temperature-controlled rooms (TCR), whose smallest room encloses the vacuum vessel which houses the spectrograph's optomechanics. Nevertheless, several options have been taken into account to minimise the complexity of the thermal design: 1) Large thermal inertia of the system, where, given a thermal instability of the environment (typically, +/-0.1K), the optomechanical system remains stable within +/-0.01K in the long run; 2) Environment thermal control, where thermal stability is ensured by controlling the temperature of the environment surrounding the vacuum vessel. The present article also includes the comprehensive transient-state thermal analyses which have been implemented in order to make the best choice, as well as to give important inputs for the thermal layout of the instrument.

  14. The Stability of Magnetized Rotating Plasmas with Superthermal Fields

    DEFF Research Database (Denmark)

    Pessah, Martin Elias; Psaltis, Dimitrios

    2005-01-01

    findings for the stability of cold, magnetically dominated, rotating fluids and argue that, for these systems, the curvature of toroidal field lines cannot be neglected even when short wavelength perturbations are considered. We also comment on the implications of our results for the validity of shearing...

  15. Thermal charm and charmonium production in quark gluon plasma

    Directory of Open Access Journals (Sweden)

    Kai Zhou

    2016-07-01

    Full Text Available We study the effect of thermal charm production on charmonium regeneration in high energy nuclear collisions. By solving the kinetic equations for charm quark and charmonium distributions in Pb+Pb collisions, we calculate the global and differential nuclear modification factors RAA(Npart and RAA(pt for J/ψ s. Due to the thermal charm production in hot medium, the charmonium production source changes from the initially created charm quarks at SPS, RHIC and LHC to the thermally produced charm quarks at Future Circular Collider (FCC, and the J/ψ suppression (RAA1 at FCC at low transverse momentum.

  16. Stability of Rayleigh-Taylor Vortices in Dusty Plasma

    Institute of Scientific and Technical Information of China (English)

    MA Jun; CHEN Yin-Hua; GAN Bao-Xia; WANG Fei-Hu; WANG Dong

    2006-01-01

    @@ The evolution of Rayleigh-Taylor mode in dusty plasma with vortex-flow is investigated. Based on fluid theory and Bayly's method, we derive the coupling equations describing the Rayleigh-Taylor mode in the core of vortex,and research the evolution characteristics of the perturbation amplitude with time numerically. It is shown that the eccentric of vortex and the content of dust have considerable effects on the amplitude evolutions.

  17. Course of organized structures in thermal plasma inside and outside argon plasma torch

    Science.gov (United States)

    Gruber, Jan; Sonsky, Jiri; Hlina, Jan

    2016-09-01

    Arc chamber of direct-current (dc) argon plasma torch and area just above the nozzle outside of this dc plasma torch were observed by hi-speed camera. System of reflecting mirrors and transparent silica arc chamber walls were used to obtain simultaneous records of both i) cathode area with electric arc inside the plasma torch and ii) nozzle exit with resulting plasma jet outside the plasma torch. Such experimental arrangement allowed us to track localized repeating patterns (organized structures) in the arc chamber and in the plasma flow. Identification of various organized structures - for different experimental conditions - according to their origin and typical development is presented in this paper. Impact of 300 Hz ripple in arc current was compared between different areas of the plasma. Additional simultaneous observation of plasma flow in the same system by series of photodiodes was used for verification of the results. The work was possible with institutional support RVO:61388998.

  18. The thermal stability of nanocrystalline copper cryogenically milled with tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Atwater, Mark A., E-mail: maatwat2@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, 911 Partner' s Way, EB I, Room 3002 Raleigh, NC 27606 (United States); US Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States); Roy, Debdas [Department of Materials Science and Engineering, North Carolina State University, 911 Partner' s Way, EB I, Room 3002 Raleigh, NC 27606 (United States); Materials and Metallurgical Engineering Department, NIFFT, Ranchi 834003 (India); Darling, Kristopher A.; Butler, Brady G. [US Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States); Scattergood, Ronald O.; Koch, Carl C. [Department of Materials Science and Engineering, North Carolina State University, 911 Partner' s Way, EB I, Room 3002 Raleigh, NC 27606 (United States)

    2012-12-15

    Copper (Cu) was cryogenically milled with tungsten (W) in a high-energy ball mill. The process created W particles dispersed in a nanocrystalline Cu matrix. These 'alloys' were then annealed to a maximum temperature of 800 Degree-Sign C. The addition of W stabilized the Cu at{approx}40 nm during annealing to 400 Degree-Sign C for a 1 at% W composition and to 600 Degree-Sign C for 10 at% W. As evidenced through hardness measurement, the W provided a significant increase in strength over pure Cu, and the 10 at% W material maintained a 2.6 GPa hardness after annealing at 800 Degree-Sign C. The stabilization and strengthening mechanisms are compared against theoretical prediction and found to be in good agreement. Although the strength and stability are significantly improved over pure Cu, the maximum benefit was hindered by an extremely broad W particle size distribution ({approx}5-5000 nm). For the 10 at% W alloy, only half of the added W was reduced to nanoscale where kinetic pinning and strengthening become most effective.

  19. Thermal stability relationships between PMR-15 resin and its composites

    Science.gov (United States)

    Bowles, Kenneth J.; Jayne, Douglas; Leonhardt, Todd A.; Bors, Dennis

    1993-01-01

    A study was conducted to investigate the relationship between the thermo-oxidative stability of PMR-15 matrix resin and the stability of graphite-fiber-reinforced composites that contain this resin as the matrix material. Three areas were investigated. The first was the effect of fiber/matrix interfacial bond strength on the isothermal aging weight loss of composites. By using type-A graphite fibers produced by Hercules, it was possible to study composites reinforced with fibers that were processed to receive different surface treatments. One of the fibers was untreated, a second fiber was treated by oxidation to enhance fiber/matrix bonding, and the third type of fiber was coated with an epoxy sizing. These treatments produced three significantly different interfacial bond strengths. The epoxy sizing on the third fiber was quickly oxidized from the bare fiber surfaces at 288, 316, and 343 C. The weight loss due to the removal of the sizing was constant at 1.5 percent. This initial weight loss was not observed in thermo-oxidative stability studies of composites. The PMR-15 matrix satisfactorily protected the reinforcemnt at all three temperatures.

  20. Plasma stabilization experiment. First technical report, 1 May 1979-30 September 1979

    Energy Technology Data Exchange (ETDEWEB)

    Sziklas, E. A.; Fader, W. J.; Jong, R. A.; Polk, D. H.; Stufflebeam, J. H.

    1979-10-01

    The Plasma Stabilization Experiment is an effort to enhance stability in a mirror-confined plasma by stoppering cold ions with rf fields applied near the mirror throats. In this initial report period, primary and backup antennas were designed and fabricated. The primary pair was installed in the UTRC mirror facility and stabilization tests were initiated. In these initial tests rf power was applied to only one antenna at a time. Preliminary results indicate a stoppering effect at the mirror throat subjected to the rf and a simultaneous increase in the rate of decay of the confined plasma. These observations suggest the stoppering effect at one mirror throat is more than offset by an enhanced loss rate through the other throat. In the next test series rf power will be applied simultaneously in both mirror throats.

  1. Flow shear stabilization of rotating plasmas due to the Coriolis effect.

    Science.gov (United States)

    Haverkort, J W; de Blank, H J

    2012-07-01

    A radially decreasing toroidal rotation frequency can have a stabilizing effect on nonaxisymmetric magnetohydrodynamic (MHD) instabilities. We show that this is a consequence of the Coriolis effect that induces a restoring pressure gradient force when plasma is perturbed radially. In a rotating cylindrical plasma, this Coriolis-pressure effect is canceled by the centrifugal effect responsible for the magnetorotational instability. In a magnetically confined toroidal plasma, a large aspect ratio expansion shows that only half of the effect is canceled. This analytical result is confirmed by numerical computations. When the plasma rotates faster toroidally in the core than near the edge, the effect can contribute to the formation of transport barriers by stabilizing MHD instabilities.

  2. Thermal stability study for candidate stainless steels of GEN IV reactors

    Energy Technology Data Exchange (ETDEWEB)

    Simeg Veternikova, J., E-mail: jana.veternikova@stuba.sk [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Degmova, J. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Pekarcikova, M. [Institute of Materials Science, Faculty of Materials Science and Technology, Slovak University of Technology, Paulinska 16, 917 24 Trnava (Slovakia); Simko, F. [Department of Molten Salts, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 36 Bratislava (Slovakia); Petriska, M. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Skarba, M. [Slovak University of Technology, Vazovova 5, 812 43 Bratislava (Slovakia); Mikula, P. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Pupala, M. [Department of Molten Salts, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 36 Bratislava (Slovakia)

    2016-11-30

    Highlights: • Thermal resistance of advanced stainless steels were observed at 1000 °C. • GEN IV candidate steels were confronted to classic AISI steels. • ODS AISI 316 has weaker thermal resistance than classic AISI steel. • Ferritic ODS steels and NF 709 has better thermal resistance than AISI steels. - Abstract: Candidate stainless steels for GEN IV reactors were investigated in term of thermal and corrosion stability at high temperatures. New austenitic steel (NF 709), austenitic ODS steel (ODS 316) and two ferritic ODS steels (MA 956 and MA 957) were exposed to around 1000 °C in inert argon atmosphere at pressure of ∼8 MPa. The steels were further studied in a light of vacancy defects presence by positron annihilation spectroscopy and their thermal resistance was confronted to classic AISI steels. The thermal strain supported a creation of oxide layers observed by scanning electron microscopy (SEM).

  3. Lattice position and thermal stability of diluted As in Ge

    CERN Document Server

    Decoster, S; Cottenier, S; Correia, JG; Mendonça, T; Amorim, LM; Pereira, LMC; Vantomme, A

    2012-01-01

    We present a lattice location study of the n-type dopant arsenic after ion implantation into germanium. By means of electron emission channeling experiments, we have observed that the implanted As atoms substitute the Ge host atoms. However, in contrast to several implanted metal impurities in Ge, no significant fraction of As is found on interstitial sites. The substitutional As impurities are found to be thermally stable up to 600°C. After 700°C annealing a strong reduction of emission channeling effects was observed, in full accordance with the expected diffusion-induced broadening of the As profile.

  4. Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion

    Science.gov (United States)

    Jacobson, Nathan S.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Recently, refractive secondary solar concentrator systems were developed for solar thermal power and propulsion (ref. 1). Single-crystal oxides-such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO), and sapphire (Al2O3)-are candidate refractive secondary concentrator materials. However, the refractive concentrator system will experience high-temperature thermal cycling in the solar thermal engine during the sun/shade transition of a space mission. The thermal mechanical reliability of these components in severe thermal environments is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions. In this research at the NASA Lewis Research Center, a controlled heat flux test approach was developed for investigating the thermal mechanical stability of the candidate oxide. This approach used a 3.0-kW continuous-wave (wavelength, 10.6 mm) carbon dioxide (CO2) laser (ref. 2). The CO2 laser is especially well-suited for single-crystal thermal shock tests because it can directly deliver well-characterized heat energy to the oxide surfaces. Since the oxides are opaque at the 10.6-mm wavelength of the laser beam, the light energy is absorbed at the surfaces rather than transmitting into the crystals, and thus generates the required temperature gradients within the specimens. The following figure is a schematic diagram of the test rig.

  5. Dispersion stability and thermal conductivity of propylene glycol-based nanofluids

    CERN Document Server

    Palabiyik, Ibrahim; Witharana, Sanjeeva; Ding, Yulong; 10.1007/s11051-011-0485-x

    2012-01-01

    The dispersion stability and thermal conductivity of propylene glycol based nanofluids containing Al2O3 and TiO2 nanoparticles were studied in the temperature range of 20 to 80 {\\deg}C. Nanofluids with different concentrations of nanoparticles were formulated by the two-step method without use of dispersants. In contrast to the common belief the average particle size of nanofluids was observed to decrease with increasing temperature. The nanofluids showed excellent stability over the temperature range of interest. Thermal conductivity enhancement for both of studied nanofluids was a non-linear function of concentration while was temperature independent. Theoretical analyses were performed using existing models and comparisons were made with experimental results. The model based on the aggregation theory appears to yield the best fit. Keywords: Nanofluids, Propylene glycol, Alumina nanoparticles, Titania nanoparticles, Thermal conductivity, Dispersion stability.

  6. Effect of Pd on GFA and Thermal Stability of Zr-based Bulk Amorphous Alloy

    Institute of Scientific and Technical Information of China (English)

    Fengxiang QIN; Haifeng ZHANG; Aimin WANG; Bingzhe DING; Zhuangqi HU

    2004-01-01

    The effect of Pd addition on the glass-forming ability and thermal stability of the Zr5sAl10Cus0Nis-xPdx (x=0, 1, 3,5 at. Pct) alloys upon copper-mold casting has been investigated. The structure, thermal stability and microstructure were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), respectively. It was identified that a new bulk amorphous alloy with the larger supercooled liquid region Atx of 100 K is obtained with substituting Ni by 1 at. Pct Pd. Furthermore, the origins that thermal stability and GFA change with increasing of Pd have also beer discussed.

  7. FTIR and DSC studies of the thermal and photochemical stability of Balanites aegyptiaca oil (Toogga oil).

    Science.gov (United States)

    Gardette, Jean-Luc; Baba, Mohamed

    2013-01-01

    The oil extracted from the bean of Balanites aegyptiaca was characterized, and its photochemical and thermal stabilization were evaluated. The chemical composition was determined using gas chromatography (GC), revealing that the oil is very rich in unsaturated fatty acids (72% omega-6 and omega-9). The photochemical stability was assessed by subjecting it to artificially accelerated photo-aging and then examining the changes using infrared spectroscopy. The thermal stability was studied at six different temperatures ranging from 130 to 200°C and monitored in situ by differential scanning calorimetry (DSC). The kinetic parameters (EA and k) describing the thermal degradation of this oil were calculated. It has been shown that the antioxidants present in the oil delay the oxidation process (induction period). The degradation of the Toogga oil was compared with that of oleic and linoleic fatty acids. In addition, the degradation of the Toogga oil extracted with hexane was compared to that of the neat oil.

  8. Preparation, characterization and thermal stability of bentonite modified with bis-imidazolium salts

    Energy Technology Data Exchange (ETDEWEB)

    Makhoukhi, B., E-mail: benamarmakh@yahoo.fr [Laboratory of Separation and Purification Technologies, Department of Chemistry, Tlemcen University, Box 119, Tlemcen (Algeria); Villemin, D. [Laboratoire de Chimie Moléculaire et Thio-organique, UMR CNRS 6507, INC3M, FR 3038, ENSICAEN and Université de Caen, 14050 Caen (France); Didi, M.A. [Laboratory of Separation and Purification Technologies, Department of Chemistry, Tlemcen University, Box 119, Tlemcen (Algeria)

    2013-02-15

    Sodium bentonite was modified with several organic bis-imidazolium salts. Organoclays with water soluble surfactants were prepared by the traditional cation exchange reaction. The bis-imidazolium-bentonites were characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction analysis (PXRD) and thermogravimetric analysis (TGA). The effect of chemical composition and molecular weight of the salts on the thermal stability and basal spacing were evaluated. The bis-imidazolium-bentonites showed enhanced thermal stability (300–400 °C) and may be potentially useful materials for melt processing of polymer/layered silicates nanocomposites. - Highlights: ► Geometry and volume of the molecule influence on interlayer spacing of modified bentonites. ► The intercalation increases with molecule length. ► The modified bentonites have an appreciably higher thermal stability.

  9. The Thermal Stabilization of Vaccines Against Agents of Bioterrorism

    Science.gov (United States)

    2005-09-01

    Dextran T40 0.1 12.37 cc Cyclodextrin 2.50% 5.61 Dextran T40 2.5 1.18 Dextran Sulfate 0.1 0.00 Dextran Sulfate 1 0.00 Dextran Sulfate 2.5 0.00 Brij 35...storage stability, more like the original constructs. 60 The chimeric valley fever protein was encapsulated into nanoparticles in an effort to improve...glycerol (20%) 6 dextran sulfate (0.0003mM) diethanolamnine (.0.3M.) Tween 20 (0.05%) lactose (20%) a- cyclodextrin (2.5%) 5 dextran sulfate (0.003mM

  10. Thermal stability of soils and detectability of intrinsic soil features

    Science.gov (United States)

    Siewert, Christian; Kucerik, Jiri

    2014-05-01

    Soils are products of long term pedogenesis in ecosystems. They are characterized by a complex network of interactions between organic and inorganic constituents, which influence soil properties and functions. However, the interrelations cannot easily be determined. Our search for unifying principles of soil formation focuses on water binding. This approach was derived from water-dependent soil formation. It considers the importance of water binding in theories about the origin of genes, in the structural arrangement and functionality of proteins, and in the co-evolution of organism species and the biosphere during the history of earth. We used thermogravimetry as a primary experimental technique. It allows a simple determi-nation of bound water together with organic and inorganic components in whole soil samples without a special preparation. The primary goal was to search for fingerprinting patterns using dynamics of thermal mass losses (TML) caused by water vaporization from natural soils, as a reference base for soil changes under land use. 301 soil samples were collected in biosphere reserves, national parks and other areas as-sumingly untouched by human activity in Siberia, North and South America, Antarctica, and in several long term agricultural experiments. The results did not support the traditional data evaluation procedures used in classical differ-ential thermogravimetry. For example, peak positions and amplitudes did not provide useful information. In contrast, using thermal mass losses (TML) in prefixed smaller, e.g. 10 °C temperature intervals allowed the determination of the content of carbon, clay, nitrogen and carbonates with high accuracy. However, this approach was applicable for soils and neither for soil-like carbon containing mineral substrates without pedogenetic origin, nor for plant residues or soils containing ashes, cinder, or charcoal. Therefore, intrinsic soil regulation processes are discussed as a possible factor causing

  11. Influence of Carbon Nanotubes on Thermal Stability of Water-Dispersible Nanofibrillar Polyaniline/Nanotube Composite

    Directory of Open Access Journals (Sweden)

    Zhi-Bin Zhang

    2012-02-01

    Full Text Available Significant influence on the thermal stability of polyaniline (PANI in the presence of multi-walled carbon nanotubes (MWCNTs is reported. By means of in-situ rapid mixing approach, water-dispersible nanofibrillar PANI and composites, consisting of MWCNTs uniformly coated with PANI in the state of emeraldine salt, with a well-defined core-shell heterogeneous structure, were prepared. The de-protonation process in PANI occurs at a lower temperature under the presence of MWCNTs on the polyaniline composite upon thermal treatment. However, it is found that the presence of MWCNTs significantly enhances the thermal stability of PANI’s backbone upon exposure to laser irradiation, which can be ascribed to the core-shell heterogeneous structure of the composite of MWCNTs and PANI, and the high thermal conductivity of MWCNTs.

  12. A polymorphic position in electron transfer flavoprotein modulates kinetic stability as evidenced by thermal stress.

    Science.gov (United States)

    Henriques, Bárbara J; Fisher, Mark T; Bross, Peter; Gomes, Cláudio M

    2011-02-04

    The electron transfer flavoprotein (ETF) is a hub interacting with at least 11 mitochondrial flavoenzymes and linking them to the respiratory chain. Here we report the effect of the ETFα-T/I171 polymorphism on protein conformation and kinetic stability under thermal stress. Although variants have comparable thermodynamic stabilities, kinetically their behavior is rather distinct as ETFα-T171 displays increased susceptibility to cofactor flavin adenine dinucleotide (FAD) loss and enhanced kinetics of inactivation during thermal stress. Mimicking a fever episode yields substantial activity loss. However, the presence of substoichiometric concentrations of GroEL is sufficient to act as an effective buffer against long-term thermal denaturation. Our investigations are compatible with the notion that the ETFα-T171 variant displays an altered conformational landscape that results in reduced protein function under thermal stress.

  13. Influence of Sonication on the Stability and Thermal Properties of Al2O3 Nanofluids

    Directory of Open Access Journals (Sweden)

    Monir Noroozi

    2014-01-01

    Full Text Available Nanofluids containing Al2O3 nanoparticles (either 11 or 30 nm in size dispersed in distilled water at low concentrations (0.125–0.5 wt% were prepared using two different ultrasonic devices (a probe and a bath sonicator as the dispersant. The effect of the ultrasonic system on the stability and thermal diffusivity of the nanofluids was investigated. Thermal diffusivity measurements were conducted using a photopyroelectric technique. The dispersion characteristics and morphology of the nanoparticles, as well as the optical absorption properties of the nanofluids, were studied using photon cross correlation spectroscopy with a Nanophox analyzer, transmission electron microscopy, and ultraviolet-visible spectroscopy. At higher particle concentration, there was greater enhancement of the thermal diffusivity of the nanofluids resulting from sonication. Moreover, greater stability and enhancement of thermal diffusivity were obtained by sonicating the nanofluids with the higher power probe sonicator prior to measurement.

  14. The influence of polyol type on cell geometry and the thermal stability of polyurethane foams

    Directory of Open Access Journals (Sweden)

    Prendžov Slobodan J.

    2006-01-01

    Full Text Available The aim of this study was to examine the influence of substituting defined amounts of polyol Voranol 3322 by polyol Voranol CP 1055 on the cell geometry and thermal stability of the synthesized flexible polyurethane foams. The influence of the amount of antipyrene on the cell geometry and their thermal stability was also investigated. The following components were used in the synthesis of the polyurethanes: a mixture of two polyols (Voranol 3322 with the hydroxyl number 47 mg KOH/g, mean molecular mass 3400 and Voranol CP 1055 with the hydroxyl number 156 mg KOH/g, mean molecular mass 1000, toluene discarnate as the isocyanate component, a combination of an organic-metallic compound and a tertiary amine as catalysts, surfactant and water as the coreactant. The thermal stability was determined by thermogravimetric analysis (in a nitrogen atmosphere. The cell geometry was analyzed by optical microscopy. Examination of the cell geometry revealed different cell shapes. The form factor as an indicator of cell deviation from spherical shape increased (more round forms were observed with increasing amount of Voranol CP 1055. The TG examination showed that specimens with 6 and 8 g of Voranol 3322 substituted by Voranol CP 1055 completely degraded at 350 °C, while foams with 10 and 12 g of Voranol 3322 substituted by Voranol CP 1055 displayed lower mass loss at higher temperatures and had residual masses of 46 % and 43 % at 600°C respectively. The addition of antipyrene in an amount of 1% (based on the amount of polyol contributed to improved thermal stability, no visible color change of the specimen tested at 210°C for 40 minutes, and to rounder cell forms. Considering the obtained results it can be concluded that an increase in the amount of Voranol CP 1055 yielded more spherically shaped cells and better thermal stability of the synthesized flexible polyurethane foams. The addition of antipyrene improves the thermal stability and the cell geometry.

  15. Stress and Strain During the Process of Thermal Stabilization of Modified Pan Precursors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wang-xi; WANG Yan-zhi; PAN Wei

    2007-01-01

    Thermal mechanical analysis, FT- IR, WAXD and some conventional measurements, such as densities and mechanical properties, were used to characterize the effect of the modification using KMnO4 and SnCl4 on the thermal mechanical behaviors and structural changes dining the process of thermal stabilization of modified PAN precursors. to the unmodified original PAN precursors, some conclusions were drawn that the thermal stabilization starts at a lower temperature for modified PAN fibers, for example, the peak of thermal stress changes for modified PAN precursors using KMnO4 displays a decrease of 20℃ and a increase of 30% in the ultimate thermal stress, that chemical modification makes structural transformation perfect and increases by 25% of the thermal stress at the temperature range of 230℃- 300℃, that the modified PAN fibers display an increase of 100% in the thermal strain, once after pre-oxidized, show an increase of 7.8% in orientation index, and a decrease of 9.9% in crystal size for identical preload in the region of 13.1 - 14.5 MPa. It was also concluded that the modification using SnCl4 would alleviate the changes in physical and chemical stress regimes and result in improvement in structure and decrease in defects.

  16. Nanosize stabilization of cubic and tetragonal phases in reactive plasma synthesized zirconia powders

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, S., E-mail: sjayakumar.physics@gmail.com [Research and Development Centre, Bharathiar University, Coimbatore 641 014 (India); Department of Physics, Pollachi Institute of Engineering and Technology, Pollachi 642 205 (India); Ananthapadmanabhan, P.V.; Thiyagarajan, T.K. [Laser and Plasma Technology Division, BARC, Trombay, Mumbai 400 085 (India); Perumal, K. [Vision for Wisdom, Temple of Consciousness, Aliyar 642 101 (India); Mishra, S.C. [Department of Metallurgical and Materials Engg, National Institute of Technology, Rourkela 769 008 (India); Suresh, G. [Department of Physics, Park College of Engineering and Technology, Coimbatore 641 659 (India); Su, L.T.; Tok, A.I.Y. [School of Materials Science and Engg, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639 798 (Singapore)

    2013-06-15

    Pure zirconium oxide powders with particle size 2–33 nm are synthesized by reactive plasma processing. Transmission electron microscopy investigation of these particles revealed size dependent behavior for their phase stabilization. The monoclinic phase is found to be stable when particle size is ≥20 nm; Tetragonal is found to be stabilized in the range of 7–20 nm and as the particle size decreases to 6 nm and less, the cubic phase is stabilized. - Highlights: ► Direct conversion of micron-sized zirconium hydride powder to single crystal ZrO{sub 2} nanopowder. ► Size dependent stabilization of cubic, tetragonal and monoclinic phases in the reactive plasma synthesized ZrO{sub 2} nanopowder. ► Transmission electron microscopic investigation to identify particles of different sizes and their corresponding phase structure.

  17. Effect of gasification parameter on coal gasification in thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Shen, S.; Pang, X.; Bao, W.; Lo, Y.; Zhu, S. [Taiyuan University of Technology, Taiyuan (China)

    2004-12-01

    The influence of several parameters such as the power input of plasma jet, vapor and air input etc on gas composition and carbon conversion from coal gasification in an air-steam plasma jet was studied. The main gaseous products are H{sub 2}, CO, CO{sub 2}, CH{sub 2}4 and tar was discovered. Results show that the concentration of H{sub 2}, CO and carbon conversion increases, and the concentration of CO{sub 2} significantly decreases, when the power input of plasma jet is raised. The concentration of H{sub 2} increases when the vapor flux is increased, but excessive steam can decrease carbon conversion. The carbon conversion is enhanced by decreasing feed rate. The air flux should be reduced to improve the quality of coal gas in a certain range. The carbon conversion of Datong coal can exceed 95% at appropriate condition. 18 refs., 4 figs., 2 tabs.

  18. Thermal stability conditions of a weakly interacting Fermi gas in a weak magnetic field

    Institute of Scientific and Technical Information of China (English)

    Fudian Men; Hui Liu; Houyu Zhu

    2009-01-01

    On the basis of the results derived from pseudopotential method and ensemble theory,thermal stability of a weakly interacting Fermi gas in a weak magnetic field is studied by using analytical method of thermodynamics.The exact analytical expressions of stability conditions at different temperatures are given,and the effects of interactions as well as magnetic field on the stability of the system are discussed.It is shown that there is an upper-limit magnetic field for the stability of the system at low temperatures,and there is an attractive dividing value at high temperatures.If attractive interaction is lower than the critical value,the stability of the system has no request for magnetic field,but if attractive interaction is higher than the dividing value,a lower-limit magnetic field exists for the stability of the system.

  19. Thermal Stability Study of Five Newcastle Disease Attenuated Vaccine Strains.

    Science.gov (United States)

    Boumart, Zineb; Hamdi, Jihane; Daouam, Samira; Elarkam, Amal; Tadlaoui, Khalid Omari; El Harrak, Mehdi

    2016-12-01

    Newcastle disease (ND) is a big concern throughout the world because of the devastating losses that can occur with commercial and backyard poultry. The major problem in many countries is the loss of the vaccine's effectiveness due to inadequate use or storage conditions, particularly in hot climates. In the present study, stability of the five, most-used NDV vaccine strains (I-2, LaSota, B1, Clone 30 [C30], and VG-GA) was tested comparatively at different storage temperatures (4 and 37 C for the freeze-dried form and 4, 24, 37, and 45 C for the freeze-dried vaccine reconstituted in diluents). The vaccine stability was evaluated by the cumulative infectious titer drop and the theoretical shelf life at particular temperatures. Results showed that I-2 and LaSota are the most stable vaccine strains compared to B1, C30, and VG-GA; they registered the lowest titer drops and the longest shelf life whether at cool, high, or room temperatures and for both freeze-dried and reconstituted vaccines.

  20. Disinfection of Staphylococcus Aureus by pulsed non-thermal atmospheric plasma jet

    Science.gov (United States)

    Mirpour, Shahriar; Ghoranneviss, Mahmood; Shahgoli, Farhad

    2011-10-01

    The aim of this paper was to study the effect of low-temperature atmospheric plasma jet on non-pathogenic bacteria's colonies. In this regard, Germicidal effect of time and distance of ICP He and He/N2 plasma jet on Staphylococcus Aureus were reported. The gas discharges were generated by a 40 KHz high voltage power supply which led to the inductively coupled plasma. The results showed that He/N2 enhance the sterilization time in comparison of He plasma. To the best of our knowledge this is the first study which has compared the effect of sterilization of ICP Helium and Helium-Nitrogen plasma in listed conditions. Also, the distance dependence showed that the germicidal effect was not linear the distance of electrode and sample. The protein leakage test and SEM of bacteria morphology confirmed the sterilization effect of non-thermal atmospheric pressure plasma jet.

  1. Sterilization of Staphylococcus Aureus by an Atmospheric Non-Thermal Plasma Jet

    Science.gov (United States)

    Liu, Xiaohu; Hong, Feng; Guo, Ying; Zhang, Jing; Shi, Jianjun

    2013-05-01

    An atmospheric non-thermal plasma jet was developed for sterilizing the Staphylococcus aureus (S. aureus). The plasma jet was generated by dielectric barrier discharge (DBD), which was characterized by electrical and optical diagnostics. The survival curves of the bacteria showed that the plasma jet could effectively inactivate 106 cells of S. aureus within 120 seconds and the sterilizing efficiency depended critically on the discharge parameter of the applied voltage. It was further confirmed by scanning electron microscopy (SEM) that the cell morphology was seriously damaged by the plasma treatment. The plasma sterilization mechanism of S. aureus was attributed to the active species of OH, N2+ and O, which were generated abundantly in the plasma jet and characterized by OES. Our findings suggest a convenient and low-cost way for sterilization and inactivation of bacteria.

  2. Thermal Stability of Annealed Germanium-Tin Alloys Grown by Molecular Beam Epitaxy

    Science.gov (United States)

    Bhargava, Nupur; Gupta, Jay Prakash; Faleev, Nikolai; Wielunski, Leszek; Kolodzey, James

    2017-01-01

    The thermal stability of undoped and boron-doped germanium tin (Ge1-x Sn x ) alloys grown by molecular beam epitaxy with varying composition and layer thickness was investigated. The alloys were annealed in forming gas at various temperatures up to 800°C for 1 min using rapid thermal processing, and were characterized using high-resolution x-ray diffraction and Rutherford backscattering spectrometry. It was found that the Ge1-x Sn x alloys were stable to well above the growth temperature, but the stability decreased with increasing thickness, Sn content, and doping. Ge1-x Sn x alloys with low Sn composition (x ˜ 0.025) were stable up to 700°C, and for a given Sn composition, the undoped alloys were more thermally stable than the doped alloys. As the thickness of the Ge0.975Sn0.025 alloys increased to about 950 nm, the temperature of thermal stability dropped to 500°C. As the Sn composition of the 90 nm-Ge1-x Sn x alloys increased up to x = 0.08, the temperature of thermal stability dropped to 300°C. At higher annealing temperatures, the Ge1-x Sn x alloy degraded with lower crystal quality, and a gradient in the Sn composition appeared, which may be due to Sn diffusion or segregation.

  3. Applications of differential scanning calorimetry for thermal stability analysis of proteins: qualification of DSC.

    Science.gov (United States)

    Wen, Jie; Arthur, Kelly; Chemmalil, Letha; Muzammil, Salman; Gabrielson, John; Jiang, Yijia

    2012-03-01

    Differential scanning calorimetry (DSC) has been used to characterize protein thermal stability, overall conformation, and domain folding integrity by the biopharmaceutical industry. Recently, there have been increased requests from regulatory agencies for the qualification of characterization methods including DSC. Understanding the method precision can help determine what differences between samples are significant and also establish the acceptance criteria for comparability and other characterization studies. In this study, we identify the parameters for the qualification of DSC for thermal stability analysis of proteins. We use these parameters to assess the precision and sensitivity of DSC and demonstrate that DSC is suitable for protein thermal stability analysis for these purposes. Several molecules from different structural families were studied. The experiments and data analyses were performed by different analysts using different instruments at different sites. The results show that the (apparent) thermal transition midpoint (T(m)) values obtained for the same protein by same and different instruments and/or analysts are quite reproducible, and the profile similarity values obtained for the same protein from the same instrument are also high. DSC is an appropriate method for assessing protein thermal stability and conformational changes.

  4. PMR-15/Layered Silicate Nanocomposites For Improved Thermal Stability And Mechanical Properties

    Science.gov (United States)

    Campbell, Sandi; Scheiman, Daniel; Faile, Michael; Papadopoulos, Demetrios; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Montmorillonite clay was organically modified by co-exchange of an aromatic diamine and a primary alkyl amine. The clay was dispersed into a PMR (Polymerization of Monomer Reactants)-15 matrix and the glass transition temperature and thermal oxidative stability of the resulting nanocomposites were evaluated. PMR-15/ silicate nanocomposites were also investigated as a matrix material for carbon fabric reinforced composites. Dispersion of the organically modified silicate into the PMR-15 matrix enhanced the thermal oxidative stability, the flexural strength, flexural modulus, and interlaminar shear strength of the polymer matrix composite.

  5. Changes in the Thermal and Dimensional Stability of the Structure of a Polymer Composite After Carbonization

    Science.gov (United States)

    Gaidachuk, V. E.; Kondratiev, A. V.; Chesnokov, A. V.

    2017-01-01

    Based on the theory of reinforcement of polymer composites, approximate relations for the physicomechanical and strength properties of a carbon-carbon composite material are synthesized, which are used to perform a finite-element analysis of the degree and character of changes in the thermal and dimensional stability of its structure after carbonization. Using approximate criteria of structural optimization of carbon-carbon composites ensuring their maximum dimensional stability, a [0/±45/90] package of thermally nonquilibrium layers is investigated and compared with an analogous carbon-fiber-reinforced plastic.

  6. Improved insights into protein thermal stability: from the molecular to the structurome scale.

    Science.gov (United States)

    Pucci, Fabrizio; Rooman, Marianne

    2016-11-13

    Despite the intense efforts of the last decades to understand the thermal stability of proteins, the mechanisms responsible for its modulation still remain debated. In this investigation, we tackle this issue by showing how a multiscale perspective can yield new insights. With the help of temperature-dependent statistical potentials, we analysed some amino acid interactions at the molecular level, which are suggested to be relevant for the enhancement of thermal resistance. We then investigated the thermal stability at the protein level by quantifying its modification upon amino acid substitutions. Finally, a large scale analysis of protein stability-at the structurome level-contributed to the clarification of the relation between stability and natural evolution, thereby showing that the mutational profile of proteins differs according to their thermal properties. Some considerations on how the multiscale approach could help in unravelling the protein stability mechanisms are briefly discussed.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  7. Differential Scanning Calorimetry — A Method for Assessing the Thermal Stability and Conformation of Protein Antigen

    Science.gov (United States)

    Durowoju, Ibrahim B.; Bhandal, Kamaljit S.; Hu, Jian; Carpick, Bruce; Kirkitadze, Marina

    2017-01-01

    Differential scanning calorimetry (DSC) is an analytical technique that measures the molar heat capacity of samples as a function of temperature. In the case of protein samples, DSC profiles provide information about thermal stability, and to some extent serves as a structural “fingerprint” that can be used to assess structural conformation. It is performed using a differential scanning calorimeter that measures the thermal transition temperature (melting temperature; Tm) and the energy required to disrupt the interactions stabilizing the tertiary structure (enthalpy; ∆H) of proteins. Comparisons are made between formulations as well as production lots, and differences in derived values indicate differences in thermal stability and structural conformation. Data illustrating the use of DSC in an industrial setting for stability studies as well as monitoring key manufacturing steps are provided as proof of the effectiveness of this protocol. In comparison to other methods for assessing the thermal stability of protein conformations, DSC is cost-effective, requires few sample preparation steps, and also provides a complete thermodynamic profile of the protein unfolding process. PMID:28287565

  8. Differential Scanning Calorimetry - A Method for Assessing the Thermal Stability and Conformation of Protein Antigen.

    Science.gov (United States)

    Durowoju, Ibrahim B; Bhandal, Kamaljit S; Hu, Jian; Carpick, Bruce; Kirkitadze, Marina

    2017-03-04

    Differential scanning calorimetry (DSC) is an analytical technique that measures the molar heat capacity of samples as a function of temperature. In the case of protein samples, DSC profiles provide information about thermal stability, and to some extent serves as a structural "fingerprint" that can be used to assess structural conformation. It is performed using a differential scanning calorimeter that measures the thermal transition temperature (melting temperature; Tm) and the energy required to disrupt the interactions stabilizing the tertiary structure (enthalpy; ∆H) of proteins. Comparisons are made between formulations as well as production lots, and differences in derived values indicate differences in thermal stability and structural conformation. Data illustrating the use of DSC in an industrial setting for stability studies as well as monitoring key manufacturing steps are provided as proof of the effectiveness of this protocol. In comparison to other methods for assessing the thermal stability of protein conformations, DSC is cost-effective, requires few sample preparation steps, and also provides a complete thermodynamic profile of the protein unfolding process.

  9. Stability studies of plasma modification effects of polylactide and polycaprolactone surface layers

    Science.gov (United States)

    Moraczewski, Krzysztof; Stepczyńska, Magdalena; Malinowski, Rafał; Rytlewski, Piotr; Jagodziński, Bartłomiej; Żenkiewicz, Marian

    2016-07-01

    The article presents results of research on the stability of oxygen plasma modification effects of polylactide and polycaprolactone surface layers. The modified samples were aged for three, six or nine weeks. The studies were carried out using scanning electron microscopy, goniometry and Fourier transform infrared spectroscopy. Studies have shown that the plasma modification has significant impact on the geometric structure and chemical composition of the surface, wettability and surface energy of tested polymers. The modification effects are not permanent. It has been observed that over time the effects of plasma modification fade. Studies have shown that modifying effect lasts longer in the case of polycaprolactone.

  10. Hafnia-plugged microcavities for thermal stability of selective emitters

    Science.gov (United States)

    Lee, Heon-Ju; Smyth, Katherine; Bathurst, Stephen; Chou, Jeffrey; Ghebrebrhan, Michael; Joannopoulos, John; Saka, Nannaji; Kim, Sang-Gook

    2013-06-01

    Two-dimensional arrays of micro-cavities effectively control photon motion and selectively emit radiation tailored to the preferred bandgap of photovoltaic (PV) cells, thus enhancing the efficiency of thermophotovoltaic energy conversion. At the high operating temperatures, however, the micro- and nano-patterned structures of the selective emitters quickly lose their integrity--obliterating the tight tolerances required for precise spectral control. Even if oxidation, recrystallization, and grain growth could be avoided with single-crystal tungsten (W) selective emitters with vacuum packaging, surface diffusion, evaporation, and re-condensation are not avoidable in long-term operation at high temperatures. The concept of a planar array of plugged micro-cavities to suppress the curvature-dependent thermal degradation modes is proposed and tested. Based on scale-accelerated failure tests of silicon devices, the lifetime of W selective emitters operating at 1100 K is estimated to be at least 30 yr.

  11. The analysis of thermal stability of detonation nanodiamond

    Science.gov (United States)

    Efremov, V. P.; Zakatilova, E. I.

    2016-11-01

    The detonation nanodiamond is a new perspective material. Ammunition recycling with use of high explosives and obtaining nanodiamond as the result of the detonation synthesis have given a new motivation for searching of their application areas. In this work nanodiamond powder has been investigated by the method of synchronous thermal analysis. Experiments have been carried out at atmospheric pressure in the environment of argon. Nanodiamond powder has been heated in the closed corundum crucible at the temperature range of 30-1500 °C. The heating rates were varied from 2 K/min to 20 K/min. After the heat treatment, the samples have been studied by the x-ray diffraction and the electron microscopy. As one of the results of this work, it has been found that the detonation nanodiamond has not started the transition into graphite at the temperature below 800 °C.

  12. Examining the stability of thermally fissile Th and U isotopes

    Science.gov (United States)

    Kumar, Bharat; Biswal, S. K.; Singh, S. K.; Patra, S. K.

    2015-11-01

    The properties of recently predicted thermally fissile Th and U isotopes are studied within the framework of the relativistic mean-field approach using the axially deformed basis. We calculate the ground, first intrinsic excited state for highly neutron-rich thorium and uranium isotopes. The possible modes of decay such as α decay and β decay are analyzed. We found that neutron-rich isotopes are stable against α decay, however, they are very unstable against β decay. The lifetime of these nuclei is predicted to be tens of seconds against β decay. If these nuclei are utilized before their decay time, a lot of energy can be produced with the help of multifragmentation fission. Also, these nuclei have great implications from the astrophysical point of view. In some cases, we found that the isomeric states with energy range from 2 to 3 MeV and three maxima in the potential energy surface of Th-230228 and U-234228 isotopes.

  13. Vitrification of MSWI Fly Ash by Thermal Plasma Melting and Fate of Heavy Metals

    Institute of Scientific and Technical Information of China (English)

    倪国华; 赵鹏; 江贻满; 孟月东

    2012-01-01

    Municipal solid waste incinerator (MSWI) fly ash with high basicity (about 1.68) was vitrified in a thermal plasma melting furnace system. Through the thermal plasma treatment, the vitrified product (slag) with amorphous dark glassy structure was obtained, and the leachability of hazardous metals in slag was significantly reduced. Meanwhile, it was found that the cooling rate affects significantly the immobility of heavy metals in slag. The mass distribution of heavy metals (Zn, Cd, Cr, Pb, As, Hg) was investigated in residual products (slag, secondary residues and flue gas), in order to analyze the behavior of heavy metals in thermal plasma atmosphere. Heavy metal species with low boiling points accounting for the major fraction of their input-mass were adsorbed in secondary residues by pollution abatement devices, while those with high boiling points tended to be encapsulated in slag.

  14. Optimization simulation of thermal plasma reactor for acetylene production from coal

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J.; Yang, Y.; Bao, W.; Zhang, Y.; Kie, K. [Taiyuan University of Technology, Taiyuan (China)

    2007-07-01

    A heat-flow field mathematical model based on the computational; fluid dynamics (CFD) technique was developed for a thermal plasma reactor in order to optimize the reactor structure and operation conditions for the direct production of acetylene from coal. The simulation of the thermal plasma reactor with single inlet, double inlet and double inlet with protective gas was given; simulations of the heat-flow coupling field were carried out by using the method of Incomplete Cholesky Conjugate Gradient (ICCG). The optimization simulation results show that the load of the thermal plasma reactor with double inlet is increased, and the reactor wall surface coke is depressed. The anticoking effect is best under the gas flow rate of 50 m/s. 4 refs., 4 figs.

  15. Ion streaming instabilities in pair ion plasma and localized structure with non-thermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Khattak, M. Nasir; Qamar, A., E-mail: mnnasirphysics@gmail.com [Department of Physics, University of Peshawar (Pakistan); Mushtaq, A. [Department of Physics, Abdul Wali Khan University Mardan, National Center for Physics, Mardan (Pakistan)

    2015-12-15

    Pair ion plasma with a fraction of non-thermal electrons is considered. We investigate the effects of the streaming motion of ions on linear and nonlinear properties of unmagnetized, collisionless plasma by using the fluid model. A dispersion relation is derived, and the growth rate of streaming instabilities with effect of streaming motion of ions and non-thermal electrons is calculated. A quasi-potential approach is adopted to study the characteristics of ion acoustic solitons. An energy integral equation involving Sagdeev potential is derived during this process. The presence of the streaming term in the energy integral equation affects the structure of the solitary waves significantly along with non-thermal electrons. Possible application of the work to the space and laboratory plasmas are highlighted. (author)

  16. The pH-dependent thermal and storage stability of glycosylated caseinomacropeptide

    DEFF Research Database (Denmark)

    Siegert, Nadja; Tolkach, Alexander; Kulozik, Ulrich

    2012-01-01

    treatment and storage under different pH values. Process stability (preservation of native protein structure in terms of attached glycans) was analysed by quantifying the release of the terminal carbohydrate, N-acetylneuraminic acid (Neu5Ac), from gCMP. The results clearly showed that the thermal stability......, with a maximum release of 30% at pH 2. Acidic pH conditions were responsible for the hydrolysis of the glycans from the peptide backbone during heat treatment and storage....

  17. Inductive inhibition of cold-plasma stabilization of curvature-driven modes in finite-length plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Guest, G.E.; Miller, R.L.; Caponi, M.Z.

    1986-08-01

    A modified quasistatic theory that incorporates inductive effects in earlier electrostatic models connects the conventional electrostatic and magnetohydrodynamic (MHD) pictures of line tying by cold plasma. The modified theory predicts that curvature-driven flute modes in mirror-confined plasmas can be stabilized by moderate concentrations of cold plasma if the beta of the hot, mirror-confined plasma is less than a critical value. The maximum stable beta for an idealized stratified model of a hot-ion plasma, separated from conducting end walls by cold plasma, is given approximately by ..beta../sub crit/approx. =(4R-italic/sub p-italic/R-italic/sub c-italic//L-italic/sub h-italic/L-italic/sub c-italic/) x (..omega../sup 2//sub p-italic//sub e-italic//sub (cold)// (k-italic/sup 2//sub perpendicular/c-italic/sup 2/+..omega../sup 2//sub p-italic//sub e-italic//sub (cold)/)). For ..omega../sup 2//sub p-italic//sub e-italic//sub (cold)/ <plasmas if the hot-plasma beta exceeds a limiting value estimated to be ..pi../sup 2/R-italic/sub p-italic/R-italic/sub c-italic//L-italic/sup 2/.

  18. Design and evaluation of an emulsion vehicle for paclitaxel. I. Physicochemical properties and plasma stability.

    Science.gov (United States)

    Han, Jihong; Davis, Stanley S; Papandreou, Catherine; Melia, Colin D; Washington, Clive

    2004-09-01

    The current formulation of paclitaxel contains ethanol and Cremophor EL and has been reported to cause serious adverse reactions. The purpose of the present work was to develop an improved emulsion vehicle for paclitaxel and to study the physicochemical properties of such a system. Emulsions were prepared by either microfluidization or sonication method and the droplet size characterized by dynamic light scattering and light microscopy. Stable emulsions could be made using mixtures of lecithin/sodium deoxycholate as the emulsifiers. The formulation was further improved by using a combination of free acid and the sodium salt. Paclitaxel could be loaded into the emulsions at 2.5 mg/ml without the formation of drug crystals. While these emulsions were stable on storage, they flocculated when mixed with plasma. Steric stabilization of the emulsion droplets with poloxamer 188 increased the stability of the emulsions in plasma but promoted the crystallization of paclitaxel. The crystallization tendency could be reduced by using PEG5000PE (1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[poly (ethylene glycol) 5000]), a less water-soluble stabilizer. Emulsions with good stability characteristics containing 2.5 mg/ml paclitaxel could be made using bile salt/acid and lecithin, and the excellent stability of these emulsions in plasma was achieved by steric stabilization using PEG5000PE.

  19. Characteristics of NO reduction with non-thermal plasma

    Institute of Scientific and Technical Information of China (English)

    YU Gang; YU Qi; JIANG Yan-long; ZENG Ke-si

    2005-01-01

    As a new type of NO removal system, NO reduction in N2-NO plasma was applied to solve the difficulties in the traditional methods, such as higher energy-consumption, larger equipment size and high cost, and so on. Using the experimental NO reduction system with single-pair electrode tip discharge structure, the NO reduction characteristics of N2-NO system were revealed to guide the engineering practice; the results of NO reduction with single-pair electrode tip discharge plasma also have the same instructive meaning to the NO reduction with multi-pair electrode tip discharge plasma. The amount of both active N atom and NO removal rate increased with the distance /g increasing between the two electrode tips and then dropped when the distance exceeded a certain value. The NO removal rate increased while the voltage between two electrode tips or the resident time of gas flow increased. The distance is a key geometrical variable factor that can determine the intensity of electric field between two electrode tips and the resident time of gas. In this paper, the effects of the dielectric features on NO reduction using dielectric-barrier discharge plasma system were also studied. The results of NO removal rate with different dielectrics such as Al2 O3, CaO, MgO and glass showed that the electric field intensity is different with different dielectric, because it brings different energy to particles in discharge room and thus it causes different NO removal rate.

  20. Non-modal stability analysis and transient growth in a magnetized Vlasov plasma

    KAUST Repository

    Ratushnaya, V.

    2014-12-01

    Collisionless plasmas, such as those encountered in tokamaks, exhibit a rich variety of instabilities. The physical origin, triggering mechanisms and fundamental understanding of many plasma instabilities, however, are still open problems. We investigate the stability properties of a 3-dimensional collisionless Vlasov plasma in a stationary homogeneous magnetic field. We narrow the scope of our investigation to the case of Maxwellian plasma and examine its evolution with an electrostatic approximation. For the first time using a fully kinetic approach we show the emergence of the local instability, a transient growth, followed by classical Landau damping in a stable magnetized plasma. We show that the linearized Vlasov operator is non-normal leading to the algebraic growth of the perturbations using non-modal stability theory. The typical time scales of the obtained instabilities are of the order of several plasma periods. The first-order distribution function and the corresponding electric field are calculated and the dependence on the magnetic field and perturbation parameters is studied. Our results offer a new scenario of the emergence and development of plasma instabilities on the kinetic scale.

  1. Plasma stabilization experiment. Final report, 1 October 1979-30 April 1980

    Energy Technology Data Exchange (ETDEWEB)

    Sziklas, E. A.; Fader, W. J.; Jong, R. A.; Stufflebeam, J. H.

    1980-07-01

    The Plasma Stabilization Experiment is an effort to enhance stability in a mirror-confined plasma by trapping cold ions with rf fields applied near the mirror throats. Nagoya Type III antennas, coupled to a 60 kW rf power supply are mounted in the throats of the UTRC baseball magnet. An external washer gun provides a source of plasma for both streaming and confined plasma tests. Results show a strong stoppering effect on streaming plasmas and a marginal effect on confined plasmas. Theoretical calculations provide an explanation for the experimental observations. The field generates a ponderomotive force acting on the electrons. The resultant improvement in electron confinement changes the ambipolar potential and inhibits the flow of ions through the mirror throat. Criteria are derived for the validity of this trapping concept. The requisite field strengths are significantly lower than those required to trap ions directly. Scaling laws are developed for application of cold ion trapping to large mirror devices containing dense plasmas. The use of slow-wave antenna structures operated at frequencies above the lower hybrid frequency is recommended for these applications.

  2. Thermal-Mechanical Stability of Single Crystal Oxide Refractive Concentrators for High-Temperature Solar Thermal Propulsion

    Science.gov (United States)

    Zhu, Dongming; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO2 laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet and magnesium oxide.

  3. Thermal Stability of Magnesium Silicide/Nickel Contacts

    Science.gov (United States)

    de Boor, J.; Droste, D.; Schneider, C.; Janek, J.; Mueller, E.

    2016-10-01

    Magnesium silicide-based materials are a very promising class of thermoelectric materials with excellent potential for thermoelectric waste heat recovery. For the successful application of magnesium silicide-based thermoelectric generators, the development of long-term stable contacts with low contact resistance is as important as material optimization. We have therefore studied the suitability of Ni as a contact material for magnesium silicide. Co-sintering of magnesium silicide and Ni leads to the formation of a stable reaction layer with low electrical resistance. In this paper we show that the contacts retain their low electrical contact resistance after annealing at temperatures up to 823 K for up to 168 h. By employing scanning electron microscope analysis and time-of-flight (ToF)-secondary ion mass spectrometry, we can further show that elemental diffusion is occurring to a very limited extent. This indicates long-term stability under practical operation conditions for magnesium silicide/nickel contacts.

  4. A comparative study of ideal kink stability in two reactor-relevant tokamak plasma configurations with negative and positive triangularity

    Science.gov (United States)

    Ren, Jing; Liu, Yueqiang; Liu, Yue; Medvedev, S. Yu; Wang, Zhirui; Xia, Guoliang

    2016-11-01

    The effects of an ideal/resistive conducting wall, the drift kinetic resonances, as well as the toroidal plasma flow, on the stability of the ideal external kink mode are numerically investigated for a reactor-relevant tokamak plasma with strongly negative triangularity (NTR) shaping. Comparison is made for a similar plasma equilibrium, but with positive triangularity (PTR). It is found that the ideal wall stabilization is less efficient for the kink stabilization in the NTR plasma due to a less ‘external’ eigenmode structure compared to the PTR plasma. The associated plasma displacement in the NTR plasma does not ‘balloon’ near the outboard mid-plane, as is normally the case for the pressure-driven kink-ballooning instability in PTR plasmas, but being more pronounced near the X-points. The toroidal flow plays a similar role for the kink stability for both NTR and PTR plasmas. The drift kinetic damping is less efficient for the ideal external kink mode in the NTR plasma, despite a somewhat larger fraction of the particle trapping near the plasma edge compared to the PTR equilibrium. However, the drift kinetic damping of the resistive wall mode (RWM) in the NTR plasma is generally as efficient as that of the PTR plasma, although the RWM window, in terms of the normalized pressure, is narrower for the NTR plasma.

  5. Stability of Atmospheric-Pressure Plasma Induced Changes on Polycarbonate Surfaces

    Science.gov (United States)

    Sharma, Rajesh; Holcomb, Edward; Trigwell, Steve

    2006-01-01

    Polycarbonate films are subjected to plasma treatment in a number of applications such as improving adhesion between polycarbonate and silicon alloy in protective and optical coatings. The changes in surface chemistry due to plasma treatment have tendency to revert back. Thus stability of the plasma induced changes on polymer surfaces over desired time period is very important. The objective of this study was to examine the effect of ageing on atmospheric pressure helium-plasma treated polycarbonate (PC) sample as a function of treatment time. The ageing effects were studied over a period of 10 days. The samples were plasma treated for 0.5, 2, 5 and 10 minutes. Contact angle measurements were made to study surface energy changes. Modification of surface chemical structure was examined using, X-ray Photoelectron Spectroscopy (XPS). Contact angle measurements on untreated and plasma treated surfaces were made immediately, 24, 48, 72 and 96 hrs after treatment. Contact angle decreased from 93 deg for untreated sample to 30 deg for sample plasma treated for 10 minutes. After 10 days the contact angles for the 10 minute plasma treated sample increased to 67 deg, but it never reverted back to that of untreated surface. Similarly the O/C ratio increased from 0.136 for untreated sample to 0.321 for 10 minute plasma treated sample indication increase in surface energy.

  6. The degradation of oxadiazon by non-thermal plasma with a dielectric barrier configuration

    Science.gov (United States)

    Ying, ZHAO; Risheng, YAO; Yuedong, MENG; Jiaxing, LI; Yiman, JIANG; Longwei, CHEN

    2017-03-01

    To explore the feasibility of a degradation approach by non-thermal plasma and the corresponding degradation pathways, studies on the oxadiazon removal in synthetic wastewater by a dielectric barrier discharge plasma reactor were investigated. The loss of the nitro group, dechlorination and ring cleavage is mainly involved in the non-thermal plasma degradation pathways of oxadiazon in a solution based on the OES and LC-MS analysis. Detection of EC25 and the production of the chlorine ion and nitrate ion further demonstrate the feasibility and validity of the approach. The conditions with a proper applied voltage, solution flow rate, oxygen flow rate, and solution pH contribute to the plasma degradation processes with a degradation ratio of over 94%.

  7. Enhanced active aluminum content and thermal behaviour of nano-aluminum particles passivated during synthesis using thermal plasma route

    Science.gov (United States)

    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.

  8. Effect of Suspension Plasma-Sprayed YSZ Columnar Microstructure and Bond Coat Surface Preparation on Thermal Barrier Coating Properties

    Science.gov (United States)

    Bernard, Benjamin; Quet, Aurélie; Bianchi, Luc; Schick, Vincent; Joulia, Aurélien; Malié, André; Rémy, Benjamin

    2017-08-01

    Suspension plasma spraying (SPS) is identified as promising for the enhancement of thermal barrier coating (TBC) systems used in gas turbines. Particularly, the emerging columnar microstructure enabled by the SPS process is likely to bring about an interesting TBC lifetime. At the same time, the SPS process opens the way to a decrease in thermal conductivity, one of the main issues for the next generation of gas turbines, compared to the state-of-the-art deposition technique, so-called electron beam physical vapor deposition (EB-PVD). In this paper, yttria-stabilized zirconia (YSZ) coatings presenting columnar structures, performed using both SPS and EB-PVD processes, were studied. Depending on the columnar microstructure readily adaptable in the SPS process, low thermal conductivities can be obtained. At 1100 °C, a decrease from 1.3 W m-1 K-1 for EB-PVD YSZ coatings to about 0.7 W m-1 K-1 for SPS coatings was shown. The higher content of porosity in the case of SPS coatings increases the thermal resistance through the thickness and decreases thermal conductivity. The lifetime of SPS YSZ coatings was studied by isothermal cyclic tests, showing equivalent or even higher performances compared to EB-PVD ones. Tests were performed using classical bond coats used for EB-PVD TBC coatings. Thermal cyclic fatigue performance of the best SPS coating reached 1000 cycles to failure on AM1 substrates with a β-(Ni,Pt)Al bond coat. Tests were also performed on AM1 substrates with a Pt-diffused γ-Ni/γ'-Ni3Al bond coat for which more than 2000 cycles to failure were observed for columnar SPS YSZ coatings. The high thermal compliance offered by both the columnar structure and the porosity allowed the reaching of a high lifetime, promising for a TBC application.

  9. The role of thermal energy accommodation and atomic recombination probabilities in low pressure oxygen plasmas

    Science.gov (United States)

    Gibson, Andrew Robert; Foucher, Mickaël; Marinov, Daniil; Chabert, Pascal; Gans, Timo; Kushner, Mark J.; Booth, Jean-Paul

    2017-02-01

    Surface interaction probabilities are critical parameters that determine the behaviour of low pressure plasmas and so are crucial input parameters for plasma simulations that play a key role in determining their accuracy. However, these parameters are difficult to estimate without in situ measurements. In this work, the role of two prominent surface interaction probabilities, the atomic oxygen recombination coefficient γ O and the thermal energy accommodation coefficient α E in determining the plasma properties of low pressure inductively coupled oxygen plasmas are investigated using two-dimensional fluid-kinetic simulations. These plasmas are the type used for semiconductor processing. It was found that α E plays a crucial role in determining the neutral gas temperature and neutral gas density. Through this dependency, the value of α E also determines a range of other plasma properties such as the atomic oxygen density, the plasma potential, the electron temperature, and ion bombardment energy and neutral-to-ion flux ratio at the wafer holder. The main role of γ O is in determining the atomic oxygen density and flux to the wafer holder along with the neutral-to-ion flux ratio. It was found that the plasma properties are most sensitive to each coefficient when the value of the coefficient is small causing the losses of atomic oxygen and thermal energy to be surface interaction limited rather than transport limited.

  10. Enhanced thermal stability of lysosomal beta-D-galactosidase in parenchymal cells of tumour bearing mice.

    Science.gov (United States)

    Lenti, L; Lipari, M; Lombardi, D; Zicari, A; Dotta, A; Pontieri, G M

    1986-12-01

    The thermal stability of the enzyme beta-D-galactosidase varies among different organs in normal C57Bl/6 mice, and increases in the same organs in mice with Lewis Lung carcinoma. Thermal stability of this enzyme is also increased by treatment of the mice with cell-free extracts of tumour cells or with inflammatory compounds such as carrageenan or orosomucoid. After desialylation, orosomucoid more effectively increases the heat stability of the enzyme. By contrast talc, which has no galactosyl groups, is without effect on the stability of the enzyme in vivo. Macrophages of tumour bearing mice release into the culture medium a more heat resistant enzyme than macrophages from control mice. In both cases the heat resistance of the secreted enzyme is higher when fetal calf serum is present in the culture medium. Bovine serum does not modify the thermal stability of beta-D-galactosidase in this system. Incubation of lysosomal fractions of various organs with the synthetic beta-D-galactosidase substrate, p-nitrophenyl-galactopyranoside, also strongly increases the heat resistance of the enzyme. The results suggest that one factor influencing the heat resistance of this enzyme may be complex formation between the enzyme and its substrates, an example of substrate protection of the enzyme. This may not be the only factor involved in enzyme stabilization in vivo.

  11. Effect of single amino acid replacements on the thermal stability of the NH2-terminal domain of phage lambda repressor.

    Science.gov (United States)

    Hecht, M H; Sturtevant, J M; Sauer, R T

    1984-09-01

    The thermal stabilities of mutant phage lambda repressors that have single amino acid replacements in the NH2-terminal domain have been studied by means of circular dichroism and differential scanning calorimetry. The variations in stability determined by these physical methods correlate with the resistance to proteolysis at various temperatures and can be compared with the temperature-sensitive activity of the mutants in vivo. In general, mutant proteins bearing solvent-exposed substitutions have thermal stabilities identical to wild type, whereas buried substitutions reduce stability. In one case, a single amino acid replacement increases the thermal stability of the repressor.

  12. The intensity distribution and thermal stability of InnoSlab laser

    Institute of Scientific and Technical Information of China (English)

    Ning Wang; Peng Shi; Yutian Lu

    2005-01-01

    Partially end-pumped slab laser is an innovative solid state laser, namely InnoSlab. Combining the hybrid resonator with partially end-pumping, the output power can be scaled with high beam quality. In this paper, the output intensity distributions are simulated by coordinate transformation fast Fourier transform(FFT) algorithm, comparing the thermal lens influence. As the simulated curves showed, the output mode is still good when the thermal lens effect is strong, indicatingthe good thermal stability of InnoSlab laser.Such a new kind of laser can be designed and optimized on the base of this simulation.

  13. Thermal stability study for candidate stainless steels of GEN IV reactors

    Science.gov (United States)

    Simeg Veternikova, J.; Degmova, J.; Pekarcikova, M.; Simko, F.; Petriska, M.; Skarba, M.; Mikula, P.; Pupala, M.

    2016-11-01

    Candidate stainless steels for GEN IV reactors were investigated in term of thermal and corrosion stability at high temperatures. New austenitic steel (NF 709), austenitic ODS steel (ODS 316) and two ferritic ODS steels (MA 956 and MA 957) were exposed to around 1000 °C in inert argon atmosphere at pressure of ∼8 MPa. The steels were further studied in a light of vacancy defects presence by positron annihilation spectroscopy and their thermal resistance was confronted to classic AISI steels. The thermal strain supported a creation of oxide layers observed by scanning electron microscopy (SEM).

  14. Thermal Stability of Retained Austenite in TRIP Steel After Different Treatments

    Institute of Scientific and Technical Information of China (English)

    SHI Wen; LI Lin; Bruno C De Cooman; Patrick Wollants; YANG Chun-xia

    2008-01-01

    Thermal decomposition of retained austenite in TRIP steel was investigated by means of differential scanning calorimetry (DSC). The decomposition curve was abnormal, and the decomposition temperature and the activation energy were measured by the Kissinger method, which were all higher than those in quenched steel. The thermal decomposition data of samples soaked in liquid nitrogen after TRIP treatment were all similar to those without additional low temperature treatment. It indicated that there is a high thermal stability in retained austenite of the TRIP steel at low temperature, which was also proved by XRD analysis.

  15. Analysis of Residual Thermal Stress in CVD-W Coating as Plasma Facing Material

    Institute of Scientific and Technical Information of China (English)

    朱大焕; 王坤; 王先平; 陈俊凌; 方前锋

    2012-01-01

    Chemical vapor deposition-tungsten (CVD-W) coating covering the surface of the plasma facing component (PFC) is an effective method to implement the tungsten material as plasma facing material (PFM) in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method (ANSYS 10.0 code). The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.

  16. Analysis of Residual Thermal Stress in CVD-W Coating as Plasma Facing Material

    Science.gov (United States)

    Zhu, Dahuan; Wang, Kun; Wang, Xianping; Chen, Junling; Fang, Qianfeng

    2012-07-01

    Chemical vapor deposition-tungsten (CVD-W) coating covering the surface of the plasma facing component (PFC) is an effective method to implement the tungsten material as plasma facing material (PFM) in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method (ANSYS 10.0 code). The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.

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

    Science.gov (United States)

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

    2017-03-01

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

  18. Thermal shock behaviour of tungsten after high flux H-plasma loading

    Science.gov (United States)

    Wirtz, M.; Linke, J.; Pintsuk, G.; De Temmerman, G.; Wright, G. M.

    2013-11-01

    Previous studies have shown that transient thermal shock loads induce crack networks on tungsten samples especially at low base temperatures. To achieve test conditions which are more relevant for the performance of tungsten-armoured plasma facing components in next step thermonuclear fusion devices tungsten tiles were exposed to high flux hydrogen-plasma in the linear plasma generator Pilot-PSI and the high heat flux ion beam test facility MARION. Subsequently, the cyclic transient heat load tests were done in the electron beam facility JUDITH 1. The induced damages after these combined tests were examined by microscopically means, profilometry and metallography. The comparison of the obtained results and damage characteristics with those obtained after thermal shock loading show that the preloading of tungsten targets with high flux hydrogen-plasma has significant influence on the thermal shock behaviour of tungsten in terms of crack distance, width, and depth as well as cracked area. Furthermore the plasma parameters, in particular pulse duration and sample temperature during loading, have strong impact on the damage pattern after thermal shock loading.

  19. Desorption of isopropyl alcohol from adsorbent with non-thermal plasma.

    Science.gov (United States)

    Shiau, Chen Han; Pan, Kuan Lun; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

    2016-11-24

    Effective desorption of isopropyl alcohol (IPA) from adsorbents with non-thermal plasma is developed. In this system, IPA is effectively adsorbed with activated carbon while dielectric barrier discharge is applied to replace the conventional thermal desorption process to achieve good desorption efficiency, making the treatment equipment smaller in size. Various adsorbents including molecular sieves and activated carbon are evaluated for IPA adsorption capacity. The results indicate that BAC has the highest IPA adsorption capacity (280.31 mg IPA/g) under the operating conditions of room temperature, IPA of 400 ppm, and residence time of 0.283 s among 5 adsorbents tested. For the plasma desorption process, the IPA selectivity of 89% is achieved with BAC as N2 is used as desorbing gas. In addition, as air or O2 is used as desorbing gas, the IPA desorption concentration is reduced, because air and O2 plasmas generate active species to oxidize IPA to form acetone, CO2, and even CO. Furthermore, the results of the durability test indicate that the amount of IPA desorbed increases with increasing desorption times and plasma desorption process has a higher energy efficiency if compared with thermal desorption. Overall, this study indicates that non-thermal plasma is a viable process for removing VOCs to regenerate adsorbent.

  20. The relationship between the microstructure and thermal diffusivity of plasma-sprayed tungsten coatings

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, C. [National Research Council Canada, Boucherville, Quebec (Canada); Boire-Lavigne, S.; Saint-Jacques, R.G. [INRS-Energie et Materiaux, Varennes, Quebec (Canada)

    1994-12-31

    Tungsten and tungsten alloy coatings are candidate materials for plasma facing components of divertor plates in future fusion reactors. In normal operation, the sprayed coatings will be submitted to intense heat fluxes and particle bombardment. This work intends to investigate the relationship between the microstructure of plasma-sprayed tungsten coatings and their thermal diffusivity as determined by the laser flash method. The microstructural investigation was carried out on copper-infiltrated coatings. Such a preparation technique permitted the measurement of the total real contact area between the lamellae within the tungsten coatings. The spraying atmosphere was found to strongly influence the interfacial contact between lamellae and coating thermal diffusivity.

  1. Synthesis of Fullerene by Pyrolysis of Acetylene in Thermal HF-Plasma

    Institute of Scientific and Technical Information of China (English)

    ZHU Yanjuan; ZHANG Guofu; ZHANG Wei; LIN Tianjin; XIE Hongbo; LIU Qiuxiang; ZHANG Haiyan

    2007-01-01

    Carbon soot containing fullerene was continuously produced in volume by pyrolyzing acetylene in thermal HF-Plasma. The characteristics of the carbon soot and C60 were analyzed by thtransmission electron microscopy, UV/visible, IR and Raman spectroscopy. The results show that the main ingredients of the carbon soot with size of about 25 nm are amorphous carbon, graphite and fullerene. The fullerene yield in carbon soot is about 2.5 g·h-1. Compared with the graphite arc discharge method, the acetylene thermal plasma method is a preferential one for synthesis of fullerene.

  2. Physics of Nonmagnetic Relativistic Thermal Plasmas. Ph.D. Thesis - Calif. Univ., San Diego

    Science.gov (United States)

    Dermer, C. D.

    1984-01-01

    A detailed treatment of the kinematics of relativistic systems of particles and photons is presented. In the case of a relativistic Maxwell-Boltzmann distribution of particles, the reaction rate and luminosity are written as single integrals over the invariant cross section, and the production spectrum is written as a double integral over the cross section differential in the energy of the produced particles (or photons) in the center-of-momentum system of two colliding particles. The results are applied to the calculation of the annihilation spectrum of a thermal electron-positron plasma, confirming previous numerical and analytic results. Relativistic thermal electron-ion and electron-electron bremsstrahlung are calculated exactly to lowest order, and relativistic thermal electron-positron bremsstrahlung is calculated in an approximate fashion. An approximate treatment of relativistic Comptonization is developed. The question of thermalization of a relativistic plasma is considered. A formula for the energy loss or exchange rate from the interaction of two relativistic Maxwell-Boltzmann plasmas at different temperatures is derived. Application to a stable, uniform, nonmagnetic relativistic thermal plasma is made. Comparison is made with other studies.

  3. Non-thermal Dupree diffusivity and shielding effects on atomic collisions in Lorentzian turbulent plasmas

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2016-05-01

    The influence of non-thermal Dupree turbulence and the plasma shielding on the electron-ion collision is investigated in Lorentzian turbulent plasmas. The second-order eikonal analysis and the effective interaction potential including the Lorentzian far-field term are employed to obtain the eikonal scattering phase shift and the eikonal collision cross section as functions of the diffusion coefficient, impact parameter, collision energy, Debye length and spectral index of the astrophysical Lorentzian plasma. It is shown that the non-thermal effect suppresses the eikonal scattering phase shift. However, it enhances the eikonal collision cross section in astrophysical non-thermal turbulent plasmas. The effect of non-thermal turbulence on the eikonal atomic collision cross section is weakened with increasing collision energy. The variation of the atomic cross section due to the non-thermal Dupree turbulence is also discussed. This research was supported by Nuclear Fusion Research Program through NRF funded by the Ministry of Science, ICT & Future Planning (Grant No. 2015M1A7A1A01002786).

  4. Low temperature synthesis of silicon quantum dots with plasma chemistry control in dual frequency non-thermal plasmas.

    Science.gov (United States)

    Sahu, Bibhuti Bhusan; Yin, Yongyi; Han, Jeon Geon; Shiratani, Masaharu

    2016-06-21

    The advanced materials process by non-thermal plasmas with a high plasma density allows the synthesis of small-to-big sized Si quantum dots by combining low-temperature deposition with superior crystalline quality in the background of an amorphous hydrogenated silicon nitride matrix. Here, we make quantum dot thin films in a reactive mixture of ammonia/silane/hydrogen utilizing dual-frequency capacitively coupled plasmas with high atomic hydrogen and nitrogen radical densities. Systematic data analysis using different film and plasma characterization tools reveals that the quantum dots with different sizes exhibit size dependent film properties, which are sensitively dependent on plasma characteristics. These films exhibit intense photoluminescence in the visible range with violet to orange colors and with narrow to broad widths (∼0.3-0.9 eV). The observed luminescence behavior can come from the quantum confinement effect, quasi-direct band-to-band recombination, and variation of atomic hydrogen and nitrogen radicals in the film growth network. The high luminescence yields in the visible range of the spectrum and size-tunable low-temperature synthesis with plasma and radical control make these quantum dot films good candidates for light emitting applications.

  5. Enhanced active aluminum content and thermal behaviour of nano-aluminum particles passivated during synthesis using thermal plasma route

    Energy Technology Data Exchange (ETDEWEB)

    Mathe, Vikas L., E-mail: vlmathe@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007, Maharashtra (India); Varma, Vijay; Raut, Suyog [Department of Physics, Savitribai Phule Pune University, Pune 411007, Maharashtra (India); Nandi, Amiya Kumar; Pant, Arti; Prasanth, Hima; Pandey, R.K. [High Energy Materials Research Lab, Sutarwadi, Pune 411021, Maharashtra (India); Bhoraskar, Sudha V. [Department of Physics, Savitribai Phule Pune University, Pune 411007, Maharashtra (India); Das, Asoka K. [Utkal University, VaniVihar, Bhubaneswar, Odisha 751004 (India)

    2016-04-15

    Graphical abstract: - Highlights: • Synthesis of nano crystalline Al (nAl) using DC thermal plasma reactor. • In situ passivation of nAl by palmitic acid and air. • Enhanced active aluminum content obtained for palmitic acid passivated nAl. • Palmitic acid passivated nAl are quite stable in humid atmospheres. - Abstract: 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.

  6. Examining the stability of thermally fissile Th and U isotopes

    CERN Document Server

    Kumar, Bharat; Singh, S K; Patra, S K

    2015-01-01

    The properties of recently predicted thermally fissile Th and U isotopes are studied within the framework of relativistic mean field (RMF) approach using axially deformed basis. We calculated the ground, first intrinsic excited state and matter density for highly neutron-rich thorium and uranium isotopes. The possible modes of decay like $\\alpha$-decay and $\\beta$-decay are analyzed. We found that the neutron-rich isotopes are stable against $\\alpha$-decay, however they are very much unstable against $\\beta$-decay. The life time of these nuclei predicted to be tens of second against $\\beta$-decay. If these nuclei utilize before their decay time, a lots of energy can be produced within the help of multi-fragmentation fission. Also, these nuclei have a great implication in astrophysical point of view. The total nucleonic densities distribution are calculated, from which the clusters inside the parent nuclei are determined. %Most of the thorium isotopes are $\\alpha$ emitters, where as some %of them have short ha...

  7. Thermal stabilization of collagen in skin and decalcified bone

    Science.gov (United States)

    Miles, Christopher A.; Avery, Nicholas C.

    2011-04-01

    The state of collagen molecules in the fibres of tail tendon, skin and demineralized bone has been investigated in situ using differential scanning calorimetry (DSC). Hydroxyproline analysis and tissue digestion with bacterial collagenase and trypsin were used to confirm that the common cause of all the DSC endotherms was collagen denaturation. This occurred within a narrow temperature range in tendons, but over a wide temperature range in demineralized bone and old skin and demonstrated that in tendon and demineralized bone at least the same type I collagen molecule exists in different thermal states. Hypothesizing that this might be caused by different degrees of confinement within the fibre lattice, experiments were performed to measure the effect of changing the lattice dimensions by extracting the collagen into dilute solution with pepsin, swelling the lattice in acetic acid, and contracting the lattice by dehydration. A theoretical analysis was undertaken to predict the effect of dehydration. Results were consistent with the hypothesis, demonstrating that collagen molecules within the natural fibres of bone and old skin are located at different intermolecular spacings, revealing differences between molecules in the magnitude of either the attractive or repulsive forces controlling their separation. One potential cause of such variation is known differences in covalent cross-linking.

  8. Preparation of Al-SiC{sub p} composite coating by plasma thermal spray

    Energy Technology Data Exchange (ETDEWEB)

    Min, J.W. [Chungnam National University, Taejeon (Korea); Yoo, S.E. [Korea Automotive Technology Institute, Chonan (Korea); Kim, Y.J. [Sunmoon University, Asan (Korea); Kim, J.S.; Suhr, D.S. [Chungnam National University, Taejeon (Korea)

    2003-03-01

    Al-SiC{sub p} composite layer was prepared by plasma thermal spray on aluminum substrate using composite powder prepared by mechanical alloying. Mechanically alloyed powder was achieved after 24 h milling, which was used for thermal spray coating. The correlations between process conditions and thickness/porosity were analyzed, and increase of hardness was confirmed. The presence of Al-Si-C-O compound was detected by TEM analysis. (author). 16 refs., 6 tabs., 11 figs.

  9. Electrostatic envelope modes in multi-component non-thermal plasmas

    Science.gov (United States)

    Saiful Islam, Md; Sultana, Sharmin; Mamun, A. A.

    2016-07-01

    A theoretical study of envelope type solitary structures and their modulational instability has been made in a multi-component unmagnetized non-thermal plasma (consisting of negatively charged immobile heavy ions, inertial light ions and non-thermal electrons of two distinct temperatures). The cubic nonlinear Schrödinger equation (which describes the evolution of a slowly varying wave envelope with space and time) is derived by adopting the multiple scale (in space and time) perturbation technique. It is found that the plasma system under consideration supports two types (bright and dark) envelope solitons. It is also seen that the dark (bright) envelope solitons are modulationally stable (unstable). The variation of the growth rate of the unstable bright envelope solitons with various plasma parameters (e.g. wave number, temperature of plasma non-thermality, etc.) are found to be significant. The modulational instability criterions of the envelope modes are also seen to be influenced due to the variation of the intrinsic plasma parameters. This theoretical study may be useful in understanding the basic features of localized electrostatic structures in some space plasma systems (viz. Saturn's magnetosphere) where high energetic particles are available.

  10. Ion acoustic solitary waves in plasmas with nonextensive distributed electrons, positrons and relativistic thermal ions

    Science.gov (United States)

    Hafez, M. G.; Talukder, M. R.; Sakthivel, R.

    2016-05-01

    The theoretical and numerical studies have been investigated on nonlinear propagation of weakly relativistic ion acoustic solitary waves in an unmagnetized plasma system consisting of nonextensive electrons, positrons and relativistic thermal ions. To study the characteristics of nonlinear propagation of the three-component plasma system, the reductive perturbation technique has been applied to derive the Korteweg-de Vries equation, which divulges the soliton-like solitary wave solution. The ansatz method is employed to carry out the integration of this equation. The effects of nonextensive electrons, positrons and relativistic thermal ions on phase velocity, amplitude and width of soliton and electrostatic nonlinear propagation of weakly relativistic ion acoustic solitary waves have been discussed taking different plasma parameters into consideration. The obtained results can be useful in understanding the features of small amplitude localized relativistic ion acoustic solitary waves in an unmagnetized three-component plasma system for hard thermal photon production with relativistic heavy ions collision in quark-gluon plasma as well as for astrophysical plasmas.

  11. Correlation between calculated molecular descriptors of excipient amino acids and experimentally observed thermal stability of lysozyme

    DEFF Research Database (Denmark)

    Meng-Lund, Helena; Friis, Natascha; van de Weert, Marco

    2017-01-01

    A quantitative structure-property relationship (QSPR) between protein stability and the physicochemical properties of excipients was investigated to enable a more rational choice of stabilizing excipients than prior knowledge. The thermal transition temperature and aggregation time were determined...... analysis was applied to correlate the descriptors with the experimental results. It was possible to identify descriptors, i.e. amino acids properties, with a positive influence on either transition temperature or aggregation onset time, or both. A high number of hydrogen bond acceptor moieties was the most....... The QSPR shows good correlation between calculated molecular descriptors and the measured stabilizing effect of amino acids on lysozyme....

  12. Experimental measurement of the thermal stability criteria for low pressure methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Berty, J.M.; Lenczyk, J.P.; Shah, S.M.

    1982-11-01

    The mathematical basis was derived for the experimental measurement of the ''Slope Condition'' and of the ''Dynamic Condition'' of the thermal stability criteria in a laboratory-scale internal recycle reactor. This work also resulted in clearer interpretations and simpler expressions for the two stability criteria. The method was experimentally demonstrated on the example of the low pressure methanol synthesis. Only seven experiments were needed to evaluate the stability criteria of this reaction for which the kinetics is unknown.

  13. Microstructural Evolution and Residual Stresses of Air-Plasma Sprayed Thermal Barrier Coatings Under Thermal Exposure

    Science.gov (United States)

    Kwon, Jae-Young; Kim, Jae-Hyoun; Lee, Sang-Yeop; Jung, Yeon-Gil; Cho, Hyun; Yi, Dong-Kee; Paik, Ungyu

    Microstructural evolution and fracture behavior of zirconia (ZrO2)-based thermal barrier coatings (TBCs) were investigated under thermal exposure. New ZrO2 granule with 8 wt.% yttria (Y2O3) with a deformed hollow morphology was developed through a spray drying process and employed to prepare TBCs. The thermal exposure tests were conducted at 1210°C with a dwell time of 100 h till 800 h. The residual stress at the interface between top coat and thermally grown oxide (TGO) layer was measured using a nanoindentation technique before and after thermal exposure. Vertical cracks on the top coat were newly formed and interlamellar cracks at the interface were enhanced after the thermal exposure of 800 h. Especially, partial delamination was observed at the interface after the thermal exposure of 800 h in TBC samples tested. The microstructural evolution in the top coat could be defined through load-displacement curves, showing a higher load or a less displacement after the thermal exposure of 800 h. The stress state was strongly dependent on the TGO geometry, resulting in the compressive stresses at the "valleys" or the "troughs," and the tensile stresses at the "crests" or peak areas, in the ranges of -500 to -75 MPa and of +168 to + 24 MPa, respectively. These stress terms incorporated with resintering during thermal exposure affected the mechanical properties such as hardness and elastic modulus of the top coat.

  14. Relation between dynamics, activity and thermal stability within the cholinesterase family.

    Science.gov (United States)

    Trovaslet, Marie; Trapp, Marcus; Weik, Martin; Nachon, Florian; Masson, Patrick; Tehei, Moeava; Peters, Judith

    2013-03-25

    Incoherent neutron scattering is one of the most powerful tools for studying dynamics in biological matter. Using the cold neutron backscattering spectrometer IN16 at the Institut Laue Langevin (ILL, Grenoble, France), temperature dependence of cholinesterases' dynamics (human butyrylcholinesterase from plasma: hBChE; recombinant human acetylcholinesterase: hAChE and recombinant mouse acetylcholinesterase: mAChE) was examined using elastic incoherent neutron scattering (EINS). The dynamics was characterized by the averaged atomic mean square displacement (MSD), associated with the sample flexibility at a given temperature. We found MSD values of hAChE above the dynamical transition temperature (around 200K) larger than for mAChE and hBChE, implying that hAChE is more flexible than the other ChEs. Activation energies for thermodynamical transition were extracted through the frequency window model (FWM) (Becker et al. 2004) [1] and turned out to increase from hBChE to mAChE and finally to hAChE, inversely to the MSDs relations. Between 280 and 316K, catalytic studies of these enzymes were carried out using thiocholine esters: at the same temperature, the hAChE activity was systematically higher than the mAChE or hBChE ones. Our results thus suggest a strong correlation between dynamics and activity within the ChE family. We also studied and compared the ChEs thermal inactivation kinetics. Here, no direct correlation with the dynamics was observed, thus suggesting that relations between enzyme dynamics and catalytic stability are more complex. Finally, the possible relation between flexibility and protein ability to grow in crystals is discussed.

  15. Thermal Stability: The Next Frontier for Nanocrystalline Materials

    Energy Technology Data Exchange (ETDEWEB)

    Mathaudhu, Suveen; Boyce, Brad L.

    2015-11-06

    For the past quarter decade, the science and technology of nanocrystalline materials (materials with grain sizes less than 100 nm) has been an extremely rich and diverse field of study.1,2 Generally, it has been observed that tremendous improvements in physical and mechanical properties, including order-of-magnitude increases in yield strength, are possible.2 As predicted by the Hall– Petch equation,3,4 a reduction in grain size should be accompanied by an increase in strength. But, despite the promise of nanocrystalline materials for a host of structural and functional applications, their use has been severely limited by their lack of microstructural stability at elevated temperatures5 or under mechanical loads.6,7 In the case of pure metals, this coarsening often occurs even at ambient temperatures.5 Ironically, the same features that often result in the enhancement of properties in nanocrystalline materials, namely the high volume fraction of high-energy grain boundaries, are responsible for the observed grain growth or phase transformation.8

  16. The Effect of Homogenization Heat Treatment on Thermal Expansion Coefficient and Dimensional Stability of Low Thermal Expansion Cast Irons

    Science.gov (United States)

    Chen, Li-Hao; Liu, Zong-Pei; Pan, Yung-Ning

    2016-08-01

    In this paper, the effect of homogenization heat treatment on α value [coefficient of thermal expansion (10-6 K-1)] of low thermal expansion cast irons was studied. In addition, constrained thermal cyclic tests were conducted to evaluate the dimensional stability of the low thermal expansion cast irons with various heat treatment conditions. The results indicate that when the alloys were homogenized at a relatively low temperature, e.g., 1023 K (750 °C), the elimination of Ni segregation was not very effective, but the C concentration in the matrix was moderately reduced. On the other hand, if the alloys were homogenized at a relatively high temperature, e.g., 1473 K (1200 °C), opposite results were obtained. Consequently, not much improvement (reduction) in α value was achieved in both cases. Therefore, a compound homogenization heat treatment procedure was designed, namely 1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ, in which a relatively high homogenization temperature of 1473 K (1200 °C) can effectively eliminate the Ni segregation, and a subsequent holding stage at 1023.15 K (750 °C) can reduce the C content in the matrix. As a result, very low α values of around (1 to 2) × 10-6 K-1 were obtained. Regarding the constrained thermal cyclic testing in 303 K to 473 K (30 °C to 200 °C), the results indicate that regardless of heat treatment condition, low thermal expansion cast irons exhibit exceedingly higher dimensional stability than either the regular ductile cast iron or the 304 stainless steel. Furthermore, positive correlation exists between the α 303.15 K to 473.15 K value and the amount of shape change after the thermal cyclic testing. Among the alloys investigated, Heat I-T3B (1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ) exhibits the lowest α 303 K to 473 K value (1.72 × 10-6 K-1), and hence has the least shape change (7.41 μm) or the best dimensional stability.

  17. Flow shear stabilization of rotating plasmas due to the Coriolis effect

    NARCIS (Netherlands)

    Haverkort, J. W.; de Blank, H. J.

    2012-01-01

    A radially decreasing toroidal rotation frequency can have a stabilizing effect on nonaxisymmetric magnetohydrodynamic (MHD) instabilities. We show that this is a consequence of the Coriolis effect that induces a restoring pressure gradient force when plasma is perturbed radially. In a rotating cyli

  18. The Effect of Plasma Beta on High-n Ballooning Stability at Low Magnetic Shear

    CERN Document Server

    Connor, J W; Hastie, R J

    2016-01-01

    An explanation of the observed improvement in H-mode pedestal characteristics with increasing core plasma pressure or poloidal beta, as observed in MAST and JET, is sought in terms of the impact of the Shafranov shift, d', on ideal ballooning MHD stability.

  19. Flow shear stabilization of rotating plasmas due to the Coriolis effect

    NARCIS (Netherlands)

    Haverkort, J. W.; de Blank, H. J.

    2012-01-01

    A radially decreasing toroidal rotation frequency can have a stabilizing effect on nonaxisymmetric magnetohydrodynamic (MHD) instabilities. We show that this is a consequence of the Coriolis effect that induces a restoring pressure gradient force when plasma is perturbed radially. In a rotating cyli

  20. Testing of High Thermal Cycling Stability of Low Strength Concrete as a Thermal Energy Storage Material

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2016-09-01

    Full Text Available Concrete has the potential to become a solution for thermal energy storage (TES integrated in concentrating solar power (CSP systems due to its good thermal and mechanical properties and low cost of material. In this study, a low strength concrete (C20 is tested at high temperatures up to 600 °C. Specimens are thermally cycled at temperatures in the range of 400–300 °C, 500–300 °C, and 600–300 °C, which TES can reach in operation. For comparison, specimens also cycled at temperature in the range of 400–25 °C (room temperature, 500–25 °C, and 600–25 °C. It is found from the test results that cracks are not observed on the surfaces of concrete specimens until the temperature is elevated up to 500 °C. There is mechanical deterioration of concrete after exposure to high temperature, especially to high thermal cycles. The residual compressive strength of concrete after 10 thermal cycles between 600 °C and 300 °C is about 58.3%, but the specimens remain stable without spalling, indicating possible use of low strength concrete as a TES material.

  1. Non-thermal atmospheric plasma brush induces HEMA grafting onto dentin collagen

    Science.gov (United States)

    Chen, Mingsheng; Zhang, Ying; Dusevich, Vladimir; Liu, Yi; Yu, Qingsong; Wang, Yong

    2014-01-01

    Objective Non-thermal atmospheric plasma (NTAP) brush has been regarded as a promising technique to enhance dental interfacial bonding. However, the principal enhancement mechanisms have not been well identified. In this study, the effect of non-thermal plasmas on grafting of HEMA, a typical dental monomer, onto dentin collagen thin films was investigated. Methods Human dentin was sectioned into 10-um-thick films. After total demineralization in 0.5 M EDTA solution for 30 min, the dentin collagen films were water-rinsed, air-dried, treated with 35 wt% HEMA aqueous solution. The films were then subject to plasma-exposure under a NTAP brush with different time (1–8 min) / input power (5–15 w). For comparison, the dentin collagen films were also treated with the above HEMA solution containing photo-initiators, then subject to light-curing. After plasma-exposure or light-curing, the HEMA-collagen films were rinsed in deionized water, and then examined by FTIR spectroscopy and TEM. Results The FITR results indicated that plasma-exposure could induce significant HEMA grafting onto dentin collagen thin films. In contrast, light-curing led to no detectable interaction of HEMA with dentin collagen. Quantitative IR spectral analysis (i.e., 1720/3075 or 749/3075, HEMA/collagen ratios) further suggested that the grafting efficacy of HEMA onto the plasma-exposed collagen thin films strongly depended on the treatment time and input power of plasmas. TEM results indicated that plasma treatment did not alter collagen’s banding structure. Significance The current study provides deeper insight into the mechanism of dental adhesion enhancement induced by non-thermal plasmas treatment. The NTAP brush could be a promising method to create chemical bond between resin monomers and dentin collagen. PMID:25458523

  2. Thermal Stability and Thermodynamics of Xylanase from Melanocarpus albomyces in Presence of Polyols and Salts

    Directory of Open Access Journals (Sweden)

    Gupteshwar Gupta

    2014-08-01

    Full Text Available An extracellular xylanase from the thermophilic fungus Melanocarpus albomyces IIS 68 was evaluated for its activity and stability in the presence of polyols and salts at 60 °C, and found to be an effective protecting agent for thermal deactivation of enzyme. Response surface methodology was employed to study the synergistic effects of glycerol and NaCl (thermo-stabilizers for xylanase stability. The addition of these thermo-stabilizers resulted in more than a 10-fold increment in enzyme half-life. Activation energy (Ea and thermodynamic parameters such as ∆H, ∆G, and ∆S were calculated for the thermal inactivation of free and immobilized xylanase. The immobilized enzyme underwent substantially less conformational changes because of its enhanced stability and increased compactness, providing better thermo-stability at elevated temperatures. These findings suggest that the combined effect of glycerol and sodium chloride serves as a potential stabilizer for extracellular thermophilic xylanase, which finds commercial application in many industries, especially in the pulp and paper industry.

  3. Towards higher stability of resonant absorption measurements in pulsed plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Britun, Nikolay, E-mail: nikolay.britun@umons.ac.be [Chimie des Interactions Plasma Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons (Belgium); Michiels, Matthieu [Materia Nova Research Center, Parc Initialis, B-7000 Mons (Belgium); Snyders, Rony [Chimie des Interactions Plasma Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons (Belgium); Materia Nova Research Center, Parc Initialis, B-7000 Mons (Belgium)

    2015-12-15

    Possible ways to increase the reliability of time-resolved particle density measurements in pulsed gaseous discharges using resonant absorption spectroscopy are proposed. A special synchronization, called “dynamic source triggering,” between a gated detector and two pulsed discharges, one representing the discharge of interest and another being used as a reference source, is developed. An internal digital delay generator in the intensified charge coupled device camera, used at the same time as a detector, is utilized for this purpose. According to the proposed scheme, the light pulses from the reference source follow the gates of detector, passing through the discharge of interest only when necessary. This allows for the utilization of short-pulse plasmas as reference sources, which is critical for time-resolved absorption analysis of strongly emitting pulsed discharges. In addition to dynamic source triggering, the reliability of absorption measurements can be further increased using simultaneous detection of spectra relevant for absorption method, which is also demonstrated in this work. The proposed methods are illustrated by the time-resolved measurements of the metal atom density in a high-power impulse magnetron sputtering (HiPIMS) discharge, using either a hollow cathode lamp or another HiPIMS discharge as a pulsed reference source.

  4. On plasma edge ideal MHD stability/instability condition in Mercier stable magnetic hill configurations

    Science.gov (United States)

    Shchepetov, S. V.

    2016-11-01

    The stability of peeling modes in zero net current stellarator plasma is studied in high poloidal mode number m \\gg 1 approximation. The vacuum region solution is taken into account. Under these conditions in Mercier stable magnetic hill plasmas internal peeling modes are stable. External peeling modes can be unstable, but several limitations on them are found. It is shown that an analytically derived pressure gradient threshold is in reasonable agreement with the experimental observations and numerical calculations. The threshold decreases with increasing poloidal mode number m. It is shown, however, that higher modes may be stabilized due to finite ion Larmor radius effects. For the sake of definiteness, we have investigated peeling mode behavior in Mercier unstable plasma. It is shown that both external and internal peeling modes can be unstable in this regime. However, external and internal peeling modes in this case are definitely different.

  5. Control of magnetohydrodynamic stability by phase space engineering of energetic ions in tokamak plasmas.

    Science.gov (United States)

    Graves, J P; Chapman, I T; Coda, S; Lennholm, M; Albergante, M; Jucker, M

    2012-01-10

    Virtually collisionless magnetic mirror-trapped energetic ion populations often partially stabilize internally driven magnetohydrodynamic disturbances in the magnetosphere and in toroidal laboratory plasma devices such as the tokamak. This results in less frequent but dangerously enlarged plasma reorganization. Unique to the toroidal magnetic configuration are confined 'circulating' energetic particles that are not mirror trapped. Here we show that a newly discovered effect from hybrid kinetic-magnetohydrodynamic theory has been exploited in sophisticated phase space engineering techniques for controlling stability in the tokamak. These theoretical predictions have been confirmed, and the technique successfully applied in the Joint European Torus. Manipulation of auxiliary ion heating systems can create an asymmetry in the distribution of energetic circulating ions in the velocity orientated along magnetic field lines. We show the first experiments in which large sawtooth collapses have been controlled by this technique, and neoclassical tearing modes avoided, in high-performance reactor-relevant plasmas.

  6. Thermal stability of structurally different viruses with proven or potential relevance to food safety

    NARCIS (Netherlands)

    Tuladhar, E.; Bouwknegt, M.; Zwietering, M.H.; Koopmans, M.; Duizer, E.

    2012-01-01

    Aims: To collect comparative data on thermal stability of structurally different viruses with proven or potential relevance to food safety. Methods and Results: Suspensions with poliovirus Sabin1, adenovirus type5, parechovirus1, human norovirus (NoV) GII.4, murine NoV (MNV1) and human influenza A (

  7. Thermal stability and practical applications of UV induced index changes in silica glasses

    DEFF Research Database (Denmark)

    Rathje, Jacob

    2000-01-01

    This thesis represents the partial fulfilment of the requirements for the danish ph.d. degree. I have been involved in both basic research of UV induced refractive index changes in silica glasses and in concrete applications. I have performed work on the thermal stability of UV-induced index...

  8. Thermal stability of Nb3Sn Rutherford cables for accelerator magnets

    NARCIS (Netherlands)

    Rapper, de Willem Michiel

    2014-01-01

    In large scale superconducting applications, like bending magnets in particle colliders, thermal stability is an important issue. A relatively small perturbation of about 100 µJ in a single point can create a small normal zone in the superconductor, which will experience sever joule heating. If the

  9. Tribological behavior and thermal stability of TiC/a-C : H nanocomposite coatings

    NARCIS (Netherlands)

    Pei, Y.T.; Galvan, D.; Hosson, J.Th.M. De

    2006-01-01

    Advanced TiC/a-C:H nanocomposite coatings have been produced via reactive deposition in a closed-field unbalanced magnetron sputtering system (Hauzer HTC-1200). These wear-resistant coatings are targeted for automotive applications where high load-bearing capacity and thermal stability, low friction

  10. Effect of graphene oxide sheet size on the curing kinetics and thermal stability of epoxy resins

    Science.gov (United States)

    Wang, Xiao; Jin, Jie; Song, Mo; Lin, Yue

    2016-10-01

    This work revealed the influences of graphene oxide (GO) sheet size on the curing kinetics and thermal stability of epoxy resins. A series of GO/epoxy nanocomposites were prepared by the incorporation of three different sized GO sheets, namely GO-1, GO-2 and GO-3, the average size of which was 10.79 μm, 1.72 μm and 0.70 μm, respectively. The morphologies of the nanocomposites were observed by field emission gun scanning electron microscope. The dispersion quality of each sized GO was comparable in the epoxy matrix. The curing kinetics was investigated by means of differential scanning calorimetry and analyzed based on kinetics model. Addition of a small amount of GO (0.1 wt%) exhibited strong catalytic effect on the curing reaction of epoxy resin. The activation energy was reduced by 18.9%, 28.8% and 14.6% with addition of GO-1, GO-2 and GO-3, respectively. GO-2 with medium size (1.72 μm) showed the most effective catalysis on the cure. The thermal stability of the cured resins was evaluated based on thermogravimetric analysis. GO/epoxy nanocomposites showed improved thermal stability in the range of 420 °C-500 °C, compared with the pure resin. A ˜ 4% more residue was obtained in each of the incorporated system. The variations of GO sheet size did not influence the enhancement effect on the thermal stability.

  11. Thermal stability of high concentration lysozyme across varying pH: A Fourier Transform Infrared study

    Directory of Open Access Journals (Sweden)

    Sathyadevi Venkataramani

    2013-01-01

    Full Text Available Aim: The current work is aimed at understanding the effect of pH on the thermal stability of hen egg white lysozyme (HEWL at high concentration (200 mg/mL. Materials and Methods: Fourier Transform Infrared (FTIR Spectroscopy with modified hardware and software to overcome some of the traditional challenges like water subtraction, sample evaporation, proper purging etc., are used in this study. Results: HEWL was subjected to thermal stress at pH 3.0-7.0 between 25°C and 95°C and monitored by FTIR spectroscopy. Calculated T m values showed that the enzyme exhibited maximum thermal stability at pH 5.0. Second derivative plots constructed in the amide I region suggested that at pH 5.0 the enzyme possessed higher amount of α-helix and lower amount of aggregates, when compared to other pHs. Conclusions: Considering the fact that HEWL has attractive applications in various industries and being processed under different experimental conditions including high temperatures, our work is able to reveal the reason behind the pH dependent thermal stability of HEWL at high concentration, when subjected to heat denaturation. In future, studies should aim at using various excipients that may help to increase the stability and activity of the enzyme at this high concentration.

  12. Pickering emulsions stabilized by whey protein nanoparticles prepared by thermal cross-linking

    NARCIS (Netherlands)

    Wu, Jiande; Shi, Mengxuan; Li, Wei; Zhao, Luhai; Wang, Ze; Yan, Xinzhong; Norde, Willem; Li, Yuan

    2015-01-01

    A Pickering (o/w) emulsion was formed and stabilized by whey protein isolate nanoparticles (WPI NPs). Those WPI NPs were prepared by thermal cross-linking of denatured WPI proteins within w/o emulsion droplets at 80. °C for 15. min. During heating of w/o emulsions containing 10% (w/v) WPI protein

  13. Thermal stability of structurally different viruses with proven or potential relevance to food safety

    NARCIS (Netherlands)

    Tuladhar, E.; Bouwknegt, M.; Zwietering, M.H.; Koopmans, M.; Duizer, E.

    2012-01-01

    Aims: To collect comparative data on thermal stability of structurally different viruses with proven or potential relevance to food safety. Methods and Results: Suspensions with poliovirus Sabin1, adenovirus type5, parechovirus1, human norovirus (NoV) GII.4, murine NoV (MNV1) and human influenza A

  14. Improved thermal stability of gas-phase Mg nanoparticles for hydrogen storage

    NARCIS (Netherlands)

    Krishnan, Gopi; Palasantzas, G.; Kooi, B. J.

    2010-01-01

    This work focuses on improving the thermal stability of Mg nanoparticles (NPs) for use in hydrogen storage. Three ways are investigated that can achieve this goal. (i) Addition of Cu prevents void formation during NP production and reduces the fast evaporation/voiding of Mg during annealing. (ii) Al

  15. Digalactosyl-diacylglycerol-deficiency lowers the thermal stability of thylakoid membranes

    NARCIS (Netherlands)

    Krumova, S.K.B.; Laptenok, S.; Kovács, L.; Toth, T.; Hoek, van A.; Garab, G.; Amerongen, van H.

    2010-01-01

    We investigated the effects of digalactosyl-diacylglycerol (DGDG) on the organization and thermal stability of thylakoid membranes, using wild-type Arabidopsis thaliana and the DGDG-deficient mutant, dgd1. Circular-dichroism measurements reveal that DGDG-deficiency hampers the formation of the

  16. Thermal stability of catalytically grown multi-walled carbon nanotubes observed in transmission electron microscopy

    DEFF Research Database (Denmark)

    Wang, Cheng-Yu; Liu, Chuan-Pu; Boothroyd, Chris

    2009-01-01

    The thermal stability of multi-walled carbon nanotubes (MWCNTs) was assessed in situ by transmission electron microscopy. Upon heating, Ni catalysts in MWC-NTs containing bamboo structures shrank from the tail due to evaporation, leading to additional bamboo formation and tube elongation at 800...

  17. Synthesis and thermal stability of a novel phosphorus-nitrogen containing intumescent flame retardant

    Institute of Scientific and Technical Information of China (English)

    Zhi Yu Ju; Yong Ye; Ru Yi Zou; Xin Cheng Liao; Yu Fen Zhao

    2008-01-01

    A novel phosphorus-nitrogen containing intumescent flame retardant (P-N IFR) was prepared via the reaction of dichlor-opentate with JV-methylaniline. The structure of the product was confirmed by 1H NMR, 31P NMR, MS and IR. TGA analysis showed it has effective thermal stability.

  18. Design of Ag nanorods for sensitivity and thermal stability of surface-enhanced Raman scattering

    Science.gov (United States)

    Ma, Lingwei; Zhang, Zhengjun; Huang, Hanchen

    2017-10-01

    The technology of surface-enhanced Raman scattering (SERS) has found many applications and may find more if it can possess both sensitivity and thermal stability. This paper reports a rational design of Ag nanorods to simultaneously achieve two competing goals: the sensitivity and the thermal stability of SERS substrates. The Ag nanorods are designed and synthesized using physical vapor deposition under the condition of glancing angle incidence. The working pressure of the vacuum chamber is controlled so the mean free path of depositing atoms is comparable to the dimension of the chamber, so as to grow Ag nanorods with small diameter, and small but clear separation for optimal SERS sensitivity. Such Ag nanorods are further capped with Al2O3 on their top surfaces to reduce the diffusion-induced coarsening at high temperatures, and thereby to improve the thermal stability for SERS detections. Meanwhile, since the side surfaces of Ag nanorods are not coated with oxides in this approach, the SERS sensitivity is largely preserved while good thermal stability is achieved.

  19. Stability of lysozyme in aqueous extremolyte solutions during heat shock and accelerated thermal conditions.

    Directory of Open Access Journals (Sweden)

    Christina Avanti

    Full Text Available The purpose of this study was to investigate the stability of lysozyme in aqueous solutions in the presence of various extremolytes (betaine, hydroxyectoine, trehalose, ectoine, and firoin under different stress conditions. The stability of lysozyme was determined by Nile red Fluorescence Spectroscopy and a bioactivity assay. During heat shock (10 min at 70°C, betaine, trehalose, ectoin and firoin protected lysozyme against inactivation while hydroxyectoine, did not have a significant effect. During accelerated thermal conditions (4 weeks at 55°C, firoin also acted as a stabilizer. In contrast, betaine, hydroxyectoine, trehalose and ectoine destabilized lysozyme under this condition. These findings surprisingly indicate that some extremolytes can stabilize a protein under certain stress conditions but destabilize the same protein under other stress conditions. Therefore it is suggested that for the screening extremolytes to be used for protein stabilization, an appropriate storage conditions should also be taken into account.

  20. Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling

    Science.gov (United States)

    DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.

    2008-02-01

    Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.